[Federal Register Volume 65, Number 179 (Thursday, September 14, 2000)]
[Proposed Rules]
[Pages 55684-55782]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-22810]
[[Page 55683]]
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Part II
Environmental Protection Agency
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40 CFR Part 148 et al.
Hazardous Waste Management System; Identification and Listing of
Hazardous Waste: Inorganic Chemical Manufacturing Wastes; Land Disposal
Restrictions for Newly Identified Wastes; and CERCLA Hazardous
Substance Designation and Reportable Quantities; Proposed Rule
Federal Register / Vol. 65, No. 179 / Thursday, September 14, 2000 /
Proposed Rules
[[Page 55684]]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Parts 148, 261, 268, 271, and 302
[SWH-FRL-6864-5]
RIN 2050-AE49
Hazardous Waste Management System; Identification and Listing of
Hazardous Waste: Inorganic Chemical Manufacturing Wastes; Land Disposal
Restrictions for Newly Identified Wastes; and CERCLA Hazardous
Substance Designation and Reportable Quantities
AGENCY: Environmental Protection Agency.
ACTION: Proposed rule.
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SUMMARY: The Environmental Protection Agency (EPA) proposes to amend
the regulations for hazardous waste management under the Resource
Conservation and Recovery Act (RCRA) by listing as hazardous three
wastes generated from inorganic chemical manufacturing processes. We
also propose not to list as hazardous various other process wastes.
This action proposes to add the toxic constituents found in the wastes
to the list of constituents that serves as the basis for classifying
wastes as hazardous, and to establish treatment standards for the
wastes.
The effect of this proposed regulation would be to subject the
wastes to stringent management and treatment standards under Subtitle C
of RCRA. Additionally, this action proposes to designate the wastes
proposed for listing as hazardous substances subject to the
Comprehensive Environmental Response, Compensation, and Liability Act
(CERCLA) and to adjust the one-pound statutory reportable quantities
(RQs) for some of these substances.
DATES: EPA will accept public comments on this proposed rule until
November 13, 2000. Comments postmarked after this date will be marked
``late'' and may not be considered. Any person may request a public
hearing on this proposal by filing a request with Mr. David Bussard by
September 28, 2000.
ADDRESSES: If you wish to comment on this proposed rule, you must send
an original and two copies of the comments referencing docket number F-
2000-ICMP-FFFFF to: RCRA Information Center, Office of Solid Waste
(5305G), U.S. Environmental Protection Agency Headquarters, 1200
Pennsylvania Avenue, NW, Washington, D.C. 20460. Hand deliveries of
comments should be made to RCRA Information Center, Crystal Gateway I,
First Floor, 1235 Jefferson Davis Highway, Arlington, VA.
You also may submit comments electronically by sending electronic
mail through the Internet to: [email protected]. You should
identify comments in electronic format with the docket number F-2000-
ICMP-FFFFF. You must submit all electronic comments as an ASCII (text)
file, avoiding the use of special characters and any form of
encryption.
Address requests for a hearing to Mr. David Bussard at: Office of
Solid Waste, Hazardous Waste Identification Division (5304W), U.S.
Environmental Protection Agency, 1200 Pennsylvania Avenue, NW,
Washington, D.C. 20460, (703) 308-8880.
FOR FURTHER INFORMATION CONTACT: For general information, contact the
RCRA/Superfund Hotline at (800) 424-9346 or TDD (800) 553-7672 (hearing
impaired). In the Washington, D.C., metropolitan area, call (703) 920-
9810 or TDD (703) 412-3323. For specific aspects of the rule, contact
Ms. Gwen DiPietro, Office of Solid Waste (5304W), U.S. Environmental
Protection Agency, 1200 Pennsylvania Avenue, NW, Washington, D.C.,
20460. [E-mail addressee and telephone number: [email protected]
(703-308-8285).] For technical information on the CERCLA aspects of
this rule, contact Ms. Lynn Beasley, Office of Emergency and Remedial
Response, Analytical Operations and Data Quality Center (5204G), U.S.
Environmental Protection Agency, 1200 Pennsylvania Avenue, NW,
Washington, D.C. 20460, [E-mail address and telephone number:
[email protected] (703-603-9086).]
SUPPLEMENTARY INFORMATION: If you do not submit comments
electronically, we ask you to voluntarily submit one additional copy of
your comments on labeled personal computer diskettes in ASCII (text)
format or a word processing format that can be converted to ASCII
(text). It is essential to specify on the disk label the word
processing software and version/edition as well as your name. This will
allow us to convert the comments into one of the word processing
formats we utilize. Please use mailing envelopes designed to physically
protect the submitted diskettes. We emphasize that submission of
comments on diskettes is not mandatory nor will it result in any
advantage or disadvantage to any commenter.
You should not submit electronically any confidential business
information (CBI). You must submit an original and two copies of CBI
under separate cover to: RCRA CBI Document Control Officer, Office of
Solid Waste (5305W), U.S. EPA, 1200 Pennsylvania Avenue, NW,
Washington, D.C. 20460. Any CBI data should be specifically and clearly
marked. In addition, please submit a non-CBI version of your comments
for inclusion in the public record.
Supporting documents in the docket for this proposal are also
available in electronic format on the Internet: http://www.epa.gov/epaoswer/hazwaste/id/inorchem/pr2000.htm>.
We will keep the official record for this action in paper form.
Accordingly, we will transfer all comments received electronically into
paper form and place them in the official record, which also will
include all comments submitted directly in writing. The official record
is the paper record maintained at the RCRA Information Center, also
referred to as the Docket.
Our responses to comments, whether the comments are written or
electronic, will be in a notice in the Federal Register or in a
response to comments document placed in the official record for this
rulemaking. We will not immediately reply to commenters electronically
other than to seek clarification of electronic comments that may be
corrupted in transmission or during conversion to paper form, as
discussed above.
You may view public comments and supporting materials in the RCRA
Information Center (RIC), located at Crystal Gateway I, First Floor,
1235 Jefferson Davis Highway, Arlington, VA. The RIC is open from 9
a.m. to 4 p.m., Monday through Friday, excluding federal holidays. To
review docket materials, we recommend that you make an appointment by
calling 703-603-9230. You may copy a maximum of 100 pages from any
regulatory docket at no charge. Additional copies cost $0.15/page.
Customer Service
How Can I Influence EPA's Thinking on This Proposed Rule?
In developing this proposal, we tried to address the concerns of
all our stakeholders. Your comments will help us improve this rule. We
invite you to provide your comments on all data, assumptions and
methodologies used to support our proposal, your views on options we
have proposed, your ideas on new approaches we have not considered, any
new data you may have, your views on how this rule may affect you, and
other relevant information. Your comments must be submitted by the
deadline in this proposal. Your
[[Page 55685]]
comments will be most effective if you follow the suggestions below:
Explain your views as clearly as possible and provide a
summary of the reasoning you used to arrive at your conclusions.
Provide examples to illustrate your views wherever possible.
Provide solid technical data to support your views.
If you estimate potential costs, explain how you arrived
at your estimate.
Tell us which parts of this proposal you support, as well
as which parts you disagree with.
Offer specific alternatives.
Reference your comments to specific sections of the
proposal by using section titles or page numbers of the preamble or the
regulatory citations.
Clearly label any CBI submitted as part of your comments.
Include your name, date, and docket number with your
comments.
Contents of This Proposed Rule
I. Overview
A. Who Potentially Will be Affected by this Proposed Rule?
B. Why Does this Rule Read Differently from Other Listing Rules?
C. What are the Statutory Authorities for this Proposed Rule?
II. Background
A. How Does EPA Define a Hazardous Waste?
B. How Does EPA Regulate RCRA Hazardous Wastes?
C. What is the Consent Decree Schedule for and Scope of this
Proposal?
III. Approach Used in this Proposed Listing
A. Summary of Today's Action
B. What Wastes Associated with the 14 Sectors Are Outside the
Scope of the Consent Decree?
1. Mineral processing wastes exempt under the ``Bevill''
exemptions
2. Residuals used or reused in different industrial processes
3. Debris and other nonprocess wastes
C. What Information Did EPA Collect and Use?
1. The RCRA Section 3007 Survey
2. Field work: site visits, sampling and analysis
3. Other sources
D. How Did EPA Evaluate Wastes for Listing Determinations?
1. Listing policy
2. Characteristic hazardous waste
3. Evaluations of particular units and pathways of release
4. Evaluation of Secondary Materials
E. Description of Risk Assessment Approaches
1. What risk thresholds were used?
2. What leaching procedures were used?
3. How were wastes screened to determine if further assessment
was needed?
4. How was the groundwater pathway evaluated?
5. How was the surface water pathway evaluated?
6. What are the limitations and uncertainties of the assessment?
F. Sector-specific Listing Determination Rationales
1. Antimony oxide
2. Barium carbonate
3. Boric acid
4. Cadmium pigments
5. Inorganic hydrogen cyanide
6. Phenyl mercuric acetate
7. Phosphoric acid from the dry process
8. Phosphorus pentasulfide
9. Phosphorus trichloride
10. Potassium dichromate
11. Sodium chlorate
12. Sodium dichromate
13. Sodium phosphate from wet process phosphoric acid
14. Titanium dioxide
G. What is the Status of Landfill Leachate from Previously
Disposed Wastes?
IV. Proposed Treatment Standards Under RCRA's Land Disposal
Restrictions
A. What are EPA's Land Disposal Restrictions (LDRs)?
B. What are the treatment standards for K176 (baghouse filters
from production of antimony oxide)
C. What standards are the treatment standards for K177 (slag
from the production of antimony oxide that is disposed of or
speculatively accumulated)?
D. What are the treatment standards for K178 (nonwastewaters
from the production of titanium dioxide by the chloride-ilmenite
process)?
E. What Other LDR Provisions Are Proposed to Apply?
1. Debris
2. Soil
3. Underground Injection Wells that can be found in the
administrative record for this rule
F. Is There Treatment Capacity for the Proposed Wastes?
1. What Is a Capacity Determination?
2. What are the Capacity Analysis Results?
V. Compliance Dates
A. Notification
B. Interim Status and Permitted Facilities
VI. State Authority
A. Applicability of Rule in Authorized States
B. Effect on State Authorizations
VII. Designation of Inorganic Chemical Wastes under the
Comprehensive Environmental Response, Compensation, and Liability
Act (CERCLA)
A. Reporting Requirements
B. Basis for Proposed RQ Adjustment
VIII. Administrative Assessments
A. Executive Order 12866
1. Methodology Section
2. Results
B. Regulatory Flexibility Act (RFA), as amended by the Small
Business Regulatory Enforcement Fairness Act of 1996 (SBREFA), 5
U.S.C. 601 et seq.
C. Paperwork Reduction Act
D. Unfunded Mandates Reform Act
E. Executive Order 12898: Environmental Justice
F. Executive Order 13045 : Protection of Children From
Environmental Health Risks and Safety Risks
G. Executive Order 13084: Consultation and Coordination With
Indian Tribal Governments
H. Executive Order 13132: Federalism
I. National Technology Transfer and Advancement Act
I. Overview
A. Who Potentially Will Be Affected by This Proposed Rule?
Beginning January 1, 1999 all documents related to EPA's
regulatory, compliance and enforcement activities, including rules,
policies, interpretive guidance, and site-specific determinations with
broad application, should properly identify the regulated entities,
including descriptions that correspond to the applicable SIC codes or
NAICS codes (source: October 9, 1998 USEPA memo from Peter D.
Robertson, Acting Deputy Administrator of USEPA). Today's action, if
finalized, could potentially affect those who handle the wastes that we
are proposing to add to EPA's list of hazardous wastes under the RCRA
program. This action also may affect entities that may need to respond
to releases of these wastes as CERCLA hazardous substances. These
potentially-affected entities are described in the Economics Background
Document placed in the docket in support of today's proposed rule. A
summary is shown in the table below.
Summary of Facilities Potentially Affected by the USEPA's 2000 Inorganic Chemical Manufacturing Waste Listing
Proposal
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Number of U.S.
relevant
Item SIC code Industry sector name inorganic mfg.
facilities
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1...................................... 2816 Inorganic Pigments..................... 3
1...................................... 2819 Industrial Inorganic Chemicals, not 3
elsewhere classified.
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[[Page 55686]]
The list of potentially affected entities in the above table may
not be exhaustive. Our aim is to provide a guide for readers regarding
entities likely to be regulated by this action. This table lists those
entities that we are aware potentially could be affected by this
action. However, this action may affect other entities not listed in
the table. To determine whether your facility is regulated by this
action, you should examine 40 CFR Parts 260 and 261 carefully in
concert with the proposed rules amending RCRA that are found at the end
of this Federal Register document. If you have questions regarding the
applicability of this action to a particular entity, consult the person
listed in the preceding section entitled FOR FURTHER INFORMATION
CONTACT.
B. Why Does This Rule Read Differently From Other Listing Rules?
Today's proposed listing determination preamble and regulations are
written in ``readable regulations'' format. The authors tried to use
active rather than passive voice, plain language, a question-and-answer
format, the pronouns ``we'' for EPA and ``you'' for the owner/
generator, and other techniques to make the information in today's rule
easier to read and understand. This new format is part of our efforts
toward regulatory re-invention, and it makes today's rule read
differently from other listing rules. We believe that this new format
will help readers understand the regulations, which should then
increase compliance, make enforcement easier, and foster better
relationships between EPA and the regulated community.
C. What Are the Statutory Authorities for This Proposed Rule?
These regulations are proposed under the authority of Sections
2002(a), 3001(b), 3001(e)(2), 3004(d)-(m) and 3007(a) of the Solid
Waste Disposal Act, 42 U.S.C. 6912(a), 6921(b) and (e)(2), 6924(d)-
(m)and 6927(a), as amended several times, most importantly by the
Hazardous and Solid Waste Amendments of 1984 (HSWA). These statutes
commonly are referred to as the Resource Conservation and Recovery Act
(RCRA), and are codified at Volume 42 of the United States Code
(U.S.C.), Sections 6901 to 6992(k) (42 U.S.C. 6901-6992(k)).
Section 102(a) of the Comprehensive Environmental Response,
Compensation, and Liability Act of 1980 (CERCLA), 42 U.S.C. 9602(a) is
the authority under which the CERCLA aspects of this rule are proposed.
II. Background
A. How Does EPA Define a Hazardous Waste?
Section 3001 of RCRA and EPA's regulations establish two ways of
identifying wastes as hazardous under RCRA. A waste may be hazardous
either if it exhibits certain properties (called ``characteristics'')
which pose threats to human health and the environment, or if it is
included on a specific list of wastes EPA has evaluated and found to
pose unacceptable risks. EPA's regulations in the Code of Federal
Regulations (CFR) define four hazardous characteristics: ignitability,
corrosivity, reactivity, or toxicity. (See 40 CFR 261.21 through
261.24.) As a generator, you must determine whether or not a waste
exhibits any of these characteristics by testing the material or by
using your knowledge of the process that produced the waste. (See 40
CFR 262.11(c).)
EPA may also conduct a more specific assessment of a waste or
category of wastes and ``list'' them if they meet criteria set out in
40 CFR 261.11. As described in 40 CFR 261.11, we may list a waste as
hazardous if it:
--Exhibits any of the characteristics noted above , i.e., ignitability,
corrosivity, reactivity, or toxicity (261.11(a)(1));
--Is ``acutely'' hazardous, i.e., if they are fatal to humans or in
animal studies at low doses, or otherwise capable of causing or
significantly contributing to an increase in serious illness
(261.11(a)(2)); or
--Is capable of posing a substantial present or potential hazard to
human health or the environment when improperly managed (261.11(a)(3)).
Under the third criterion at 40 CFR 261.11(a)(3), we may decide to
list a waste as hazardous (1) if it contains hazardous constituents
identified in Appendix VIII to 40 CFR Part 261, and (2) if, after
considering the factors noted in this section of the regulations, we
``conclude that the waste is capable of posing a substantial present or
potential hazard to human health or the environment when improperly
treated, stored, transported, or disposed of, or otherwise managed.''
We place a chemical on the list of hazardous constituents on Appendix
VIII only if scientific studies have shown a chemical has toxic effects
on humans or other life forms. When listing a waste, we also add the
hazardous constituents that serve as the basis for listing to Appendix
VII to part 261.
Residuals from the treatment, storage, or disposal of most listed
hazardous wastes are also classified as hazardous wastes based on the
``derived-from'' rule (see 40 CFR 261.3(c)(2)(i)). For example, ash or
other residuals from the treatment of a listed waste generally carries
the original hazardous waste code and is subject to the hazardous waste
regulations. Also, the ``mixture'' rule (see 40 CFR 261.3(a)(2)(iii)
and (iv)) provides that, with certain limited exceptions, any mixture
of a listed hazardous waste and a solid waste is itself a RCRA
hazardous waste.
Some materials that would otherwise be classified as hazardous
wastes under the rules described above are excluded from jurisdiction
under RCRA if they are recycled in certain ways. The current definition
of solid waste at 40 CFR 261.2 excludes secondary materials from the
definition of solid waste that are used directly (i.e., without
reclamation) as ingredients in manufacturing processes to make new
products, used directly as effective substitutes for commercial
products, or returned directly to the original process from which they
are generated as a substitute for raw material feedstock. (See 40 CFR
261.2(e).) As discussed in the January 4, 1985, rulemaking that
promulgated this regulatory framework, these are activities which, as a
general matter, resemble ongoing manufacturing operations more than
conventional waste management and so are more appropriately classified
as not involving solid wastes. (See 50 FR 637-640). Our approach to
these issues is described in more detail below in section III.D.4.
B. How Does EPA Regulate RCRA Hazardous Wastes?
Wastes exhibiting any hazardous characteristic or listed as
hazardous are subject to federal requirements under RCRA. These
regulations affect persons who generate, transport, treat, store or
dispose of such waste. Facilities that must meet the hazardous waste
management requirements, including the need to obtain permits to
operate, commonly are referred to as ``Subtitle C'' facilities.
Subtitle C is Congress' original statutory designation for that part of
RCRA that directs EPA to issue those regulations for hazardous wastes
as may be necessary to protect human health or the environment. EPA
standards and procedural regulations implementing Subtitle C are found
generally at 40 CFR Parts 260 through 272.
All RCRA hazardous wastes are also hazardous substances under the
Comprehensive Environmental Response, Compensation, and Liability Act
(CERCLA), as described in section 101(14)(C) of the CERCLA statute.
This
[[Page 55687]]
applies to wastes listed in 40 CFR 261.31 through 261.33, as well as
any wastes that exhibit a RCRA characteristic. Table 302.4 at 40 CFR
302.4 lists CERCLA hazardous substances along with their reportable
quantities (RQs). Anyone spilling or releasing a substance at or above
the RQ must report this to the National Response Center, as required in
CERCLA Section 103. In addition, Section 304 of the Emergency Planning
and Community Right-to-Know Act (EPCRA) requires facilities to report
the release of a CERCLA hazardous substance at or above its RQ to State
and local authorities. Today's rule proposes to establish RQs for some
of the newly listed wastes.
C. What Is the Consent Decree Schedule for and Scope of This Proposal?
The 1984 Hazardous and Solid Waste Amendments (HSWA) to RCRA
require EPA to make listing determinations for several specified
categories of wastes, including ``inorganic chemical industry wastes''
(see RCRA section 3001(e)(2)). In 1989, the Environmental Defense Fund
(EDF) filed a lawsuit to enforce the statutory deadlines for listing
decisions in RCRA Section 3001(e)(2). (EDF v. Browner; D.D.C. Civ. No.
89-0598). To resolve most of the issues in the case, EDF and EPA
entered into a consent decree, which has been amended several times to
revise deadlines for EPA action. Paragraph 1.g (as amended) of the
consent decree addresses the inorganic chemical industry:
EPA shall promulgate a final listing determination for inorganic
chemical industry wastes on or before October 31, 2001. This listing
determination shall be proposed for public comment on or before
August 30, 2000. The listing determination shall include the
following wastes: sodium dichromate production wastes, wastes from
the dry process for manufacturing phosphoric acid, phosphorus
trichloride production wastes, phosphorus pentasulfide production
wastes, wastes from the production of sodium phosphate from wet
process phosphoric acid, sodium chlorate production wastes, antimony
oxide production wastes, cadmium pigments production wastes, barium
carbonate production wastes, potassium dichromate production wastes,
phenyl mercuric acetate production wastes, boric acid production
wastes, inorganic hydrogen cyanide production wastes, and titanium
dioxide production wastes (except for chloride process waste
solids). However, such listing determinations need not include any
wastes which are excluded from hazardous waste regulation under
section 3001(b)(3)(A)(ii) of RCRA and for which EPA has determined
that such regulation is unwarranted pursuant to section
3001(b)(3)(C) of RCRA.
Today's proposal satisfies EPA's duty under paragraph 1.g to propose
determinations for inorganic chemical industry wastes.
As described above, the consent decree provides that EPA does not
need to make listing determinations for certain wastes that it has
exempted from hazardous waste regulations under the ``Bevill
amendments'' to RCRA. See the discussion of ``exempt mineral
processing'' wastes in section III.B.1 below.
III. Approach Used in This Proposed Listing
A. Summary of Today's Action
Manufacturers of the inorganic chemical products described above
identified over 170 categories of residuals generated as part of their
production processes. We first determined which of these residuals fell
within the scope of our consent decree obligations. We then evaluated
the risks posed by each of the remaining categories of residual
materials. In some cases we used quantitative or qualitative screening
methods. For 18 wastes we conducted full-scale modeling to predict
risks.
As a result of this evaluation, we found that three wastes
generated in the 14 inorganic chemicals manufacturing operations which
we evaluated meet the criteria for listing set out in either 40 CFR
261.11(a)(1) or 261.11(a)(3). We conducted full-scale modeling of two
of these wastes and propose to list them under 40 CFR 261.11(a)(3). We
found that one waste warranted listing under 40 CFR 261.11(a)(1)
because it exhibited hazardous waste characteristics. We did not model
this waste. Since these are wastes from specific inorganic chemical
industries, we propose to add them to Section 261.32 with K-waste
codes. The three wastestreams we propose to list as hazardous, along
with their corresponding hazard code and proposed EPA Hazardous Waste
Numbers, are: \1\
\1\ As required in 40 CFR 262.30, the listing description
includes the hazard code. Wastes listed under 40 CFR 261.11(a)(1)
due to the toxicity characteristic are designated ``E,'' and wastes
listed under 40 CFR 261.11(a)(3) for toxicity are designated ``T''.
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K176 Baghouse filters from the production of antimony oxide. (E)
K177 Slag from the production of antimony oxide that is disposed of or
speculatively accumulated. (T)
K178 Nonwastewaters from the production of titanium dioxide by the
chloride-ilmenite process. (This listing does not apply to chloride
process waste solids from titanium tetrachloride production exempt
under 40 CFR 261.4(b)(7).) (T)
We found that all of the remaining wastes that we evaluated did not
meet the criteria for listing in 40 CFR 261.11, and we are proposing
not to list them as hazardous wastes. More information on our
evaluations of particular wastes is set out in the background documents
and the sector-specific discussions in section III.F of this preamble.
We have previously listed as hazardous a number of wastes in 40 CFR
261.32 from other inorganic chemicals industries, including wastes from
the production of inorganic pigments (codes K002 through K008), and
wastes from chlorine production (codes K071, K073, and K106). Today's
proposal does not affect the scope of any existing hazardous waste
listing, and we are not soliciting comments on those existing listing
determinations.
We are also proposing other changes to the RCRA regulations as a
result of the proposed listings. These changes include adding
constituents to Appendices VII and VIII for Part 261, and setting new
land disposal restrictions. We are proposing to add the following
constituents to Appendix VII that serve as the basis for listing:
K176--arsenic and lead, K177--antimony, and K178--manganese and
thallium. We are also proposing to add manganese to the list of
hazardous constituents in Appendix VIII, based on scientific studies
that demonstrate manganese has toxic effects on humans and other life
forms. Section IV of today's proposal describes the proposed changes to
the land disposal restrictions, which would establish treatment
standards for specific constituents in the wastes proposed for listing.
Also as a result of the proposed listings, these wastes would
become hazardous substances under CERCLA. Therefore, in today's rule we
are proposing to designate these wastestreams as CERCLA hazardous
substances, and to adjust the one-pound statutory RQs for two of these
wastestreams; this is described in section VII of today's proposal.
B. What Wastes Associated With the 14 Sectors Are Outside the Scope of
the Consent Decree?
Determining the scope of our consent decree obligations was more
complicated than usual for two reasons. First, Paragraph 1.g (quoted
above in II.C) does not tell EPA which wastestreams it must evaluate.
For most other listing obligations set out in the consent decree, the
decree specifies particular wastestreams which EPA must evaluate for
listing. See, for
[[Page 55688]]
example, paragraph 1.k identifying 14 specific petroleum
wastestreams.\2\ Second, paragraph 1.g contains an exemption for wastes
found to be exempt from hazardous waste regulation in previous EPA
actions implementing the so-called ``Bevill exemptions'' for mineral
processing wastes. Thus, we needed to conduct some analysis to
determine the scope of our obligations.
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\2\ The revised consent decree is available in the docket for
today's proposal.
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We began by asking facilities to identify all of the residuals
generated by their production processes. We then reviewed their lists.
We found that some residuals were actually exempt ``Bevill'' wastes
that we need not address. We found that other wastes were really
associated with the manufacture of other materials. Also, we concluded
that a few residuals were not ``production'' wastes and therefore were
not covered by the decree. With the exceptions discussed below in our
evaluation of the sodium dichromate and titanium dioxide sectors, we
chose not to evaluate any of the wastes that we considered to be
outside the scope of the decree. We concluded that evaluation was not
possible under the time frame set out in the decree. In the following
sections we provide an overview of the types of wastes that we consider
outside the scope.
1. Mineral Processing Wastes Exempt Under the ``Bevill'' Exemptions
Many of the inorganic chemical manufacturing processes we address
in this rule use ores and minerals as feedstocks. Some wastes derived
from the processing of ores and minerals are exempt from regulation as
RCRA hazardous wastes under decisions EPA made under statutory
requirements known as the ``Bevill'' amendments. RCRA Sections
3001(b)(3) and 8002(p) required EPA to determine whether wastes from
the extraction, beneficiation or processing of ores and minerals
warranted regulation as hazardous wastes under Subtitle C of RCRA.
Between 1989 and 1991 EPA completed a series of rules and studies
establishing which mining wastes fit within the ``extraction,''
``beneficiation,'' or ``processing'' definitions, and which of the
wastes within each category were exempt from regulation as hazardous
wastes. EPA concluded that all wastes produced during extraction and
beneficiation are entitled to an exemption. EPA found that 20
categories of wastes from subsequent ``mineral processing'' operations
met the ``high volume/low toxicity'' criteria and were exempt as well.
See 54 FR 36592 (Sept. 1, 1989), 55 FR 2322 (Jan. 23, 1990), the July
31, 1990 Report to Congress on Wastes from Mineral Processing, and 56
FR 27300 (June 13, 1991).
EPA codified these ``Bevill'' exemptions at 40 CFR 261.4 (b)(7).
EPA discussed some of these exemptions further in a 1998 final rule
promulgating treatment standards for non-exempt mineral processing
wastes that exhibit the toxicity characteristic. See the Land Disposal
Restrictions Phase IV Final Rule at 63 FR 28598 (May 26, 1998).
Paragraph 1.g of the consent decree provides that EPA need not make
listing determinations for wastes from any of the 14 inorganic chemical
manufacturing processes which are ``excluded from hazardous waste
regulation under Section 3001(b)(3)(A)(ii) of RCRA and for which it has
determined that such regulation is unwarranted pursuant to Section
3001(b)(3)(C) of RCRA.'' In other words, the consent decree does not
require us to make listing determinations for wastes which we exempted
under the statute's ``Bevill'' provisions.
Paragraph 1.g. of the consent decree requires EPA to make a listing
determination for ``* * * titanium dioxide production wastes (except
for chloride process waste solids).'' EPA interprets the exception to
refer to the chloride process waste solids from the production of
titanium tetrachloride which are exempt under the Bevill rule, rather
than all solids from the chloride process. Solids generated after
titanium tetrachloride forms fall within the scope of the consent
decree.
We reviewed the generators' lists of process residuals to determine
whether they had included any Bevill exempt wastes which we need not
assess. (In some cases, the generators had claimed that certain wastes
were exempt under EPA's Bevill decisions.) This process was not always
simple. We found it was sometimes difficult to determine whether a
particular facility's waste fit within one of the exempt categories.
For example, the mineral processing exemption for titanium dioxide
covers only solid materials from an initial step in the production
process. It was not always easy to tell whether particular waste solids
were generated from the portion of the process that would make them
exempt, or from later production steps. Sector-specific information
regarding our conclusions appears in section III.F of this preamble for
those sectors where we found this exemption had some relevance. We
found that facilities in only three of the consent decree sectors
generate Bevill exempt wastes: Boric acid, sodium dichromate, and
titanium dioxide.
In other sectors, the facilities produce inorganic product
chemicals from a mineral product. Under the Bevill exemption (54 FR
36620-21), chemical manufacturing begins if there is any further
processing of a saleable mineral product. Since these facilities use
saleable mineral products as feedstock, their processes are chemical
manufacturing, and may not be classified as mineral processing.
Therefore, none of the wastestreams generated by these facilities in
the production of the other inorganic chemicals are Bevill exempt.
We emphasize that we are not re-opening any Bevill decisions made
in earlier actions regarding the exemptions. We are not re-defining the
boundaries between ``extraction'' and ``beneficiation,'' between
``beneficiation'' and ``mineral processing,'' or between ``mineral
processing'' and non-exempt chemical manufacturing. Nor are we
revisiting our decision that all wastes uniquely associated with the
extraction and beneficiation of ores and minerals are exempt.
Similarly, we are not re-opening any of our earlier decisions as to
which categories of mineral processing wastes are exempt. Rather, we
are determining whether particular wastestreams fall within any of the
exempt categories. We are not requesting comment on, and do not intend
to respond to comments relating to the earlier decisions.
We also found that some inorganic chemical processes generate
composite wastestreams that contain both a Bevill exempt waste and one
or more non-exempt wastes. We evaluated the non-exempt portions of such
wastes to fulfill our consent decree requirements. We apportioned risks
between the exempt and nonexempt portion of such commingled wastes, and
made listing determinations for the non-exempt portions. We did not,
however, assess the exempt portions of such streams. This assessment,
therefore, does not re-open any earlier decision regarding exemptions
for the ``Bevill'' component of the commingled streams.
2. Residuals Used or Reused in Different Industrial Processes
In some cases, facilities within the 14 inorganic chemicals sectors
set out in the consent decree produce residuals that are used or reused
in processes that are not among those listed in the decree. Those
industries in turn produced residuals derived from the materials
generated in the consent decree industries. We evaluated the
[[Page 55689]]
management of the original industry's material up to the point that the
second industry inserts it into its production process. However, we
generally considered the second production process and its associated
wastes to be beyond the scope of the consent decree. We did not
evaluate for listing purposes wastes generated from these non-consent
decree industries. For example, in the titanium dioxide sector, one
facility uses a residual from the production of titanium dioxide as an
ingredient to make salt. We considered salt-making to be a separate
production process outside the scope of the consent decree. We are not
proposing any listing determinations for wastes generated in the salt
plant.
However, in some cases, the reuse of the residual from a consent
decree process involved an activity which we always regulate as waste
management. In this situation, we considered the reuse to be waste
management, and the waste to be within the scope of the consent decree.
Consequently, we evaluated the residual for listing. For example, we
found that one of the facilities which produces boric acid generates a
waste which is used as a fuel. Under our recycling regulations, we
regulate burning for energy recovery and so, we evaluated this waste.
See 40 CFR 261.2(c)(2). We found that the waste is already being
managed in a RCRA Subtitle C unit and decided not to list the waste.
Others examples of reuse that we evaluated include land application of
biological treatment solids from hydrogen cyanide production as a
fertilizer or soil amendment, and land application of gypsum from the
titanium dioxide sector. In two cases, however, we decided to make
listing decisions for residuals generated during the production of non-
consent decree products. In the titanium dioxide sector, the residuals
are commingled with other wastes clearly within the scope of the
decree. See the discussions of the sodium dichromate sector and the
titanium dioxide sector in section III.F. In the sodium dichromate
sector, residuals from the non-consent decree process are piped back to
the consent decree process, making it difficult to determine whether
the two processes are really separate.
3. Debris and Other Nonprocess Wastes
Some generators also identified debris and structural components of
their production plants as intermittently-generated wastes. We
concluded that these materials do not fall within the scope of the
decree. Most of the wastes that fell in this category were refractory
bricks which become wastes when facilities remove them to refurbish
their furnaces. We consider this material to be a structural component
of the plant where production takes place rather than a waste from the
``production'' of an inorganic chemical. Similarly, we consider a few
analogous types of plant debris to fall outside the scope of the
decree. This debris includes miscellaneous construction materials,
insulation, reactor bed material, and piping. These wastes were
reported for the following inorganic sectors: Phosphoric acid, barium
carbonate, sodium dichromate, hydrogen cyanide, antimony oxide, sodium
phosphate, and titanium dioxide.
We have never interpreted the decree to require us to consider
listing tanks, pads, or other structural components housing production
processes when they become wastes by being removed from use. Other
paragraphs of the decree support this position. Paragraphs 1.c. (coke
byproducts) and 1.k. (petroleum refining wastes) cover production
processes involving reaction vessels lined with refractory or similar
materials, and in neither case did the decree include wastes related to
the reaction vessels themselves or related materials. Nor do any other
provisions in the decree direct us to list any other type of structural
components. We note that discarded refractory bricks and other debris
would be regulated as hazardous wastes, if these materials were
contaminated with a listed waste (including wastes listed as a result
of today's rulemaking), or if they exhibited a hazardous waste
characteristic.
A few facilities also reported environmental media (excavated soils
or recovered groundwater) contaminated with process residuals as wastes
from their production processes. We consider such contaminated media to
be outside the scope of today's listing determinations, because these
are not wastes generated during production processes, but rather wastes
generated due to construction or remedial action. We note that none of
the other consent decree provisions require us to evaluate contaminated
media. See the specific listing background documents for the different
sectors for a full listing of the wastes we considered to be out of
scope of the decree.
C. What Information Did EPA Collect and Use?
Our investigation of the wastes generated by the inorganic
chemicals manufacturing industry included two major information
collection efforts: A survey of the industries and field
investigations. The survey effort included the development,
distribution, and assessment of an extensive questionnaire sent under
the authority of RCRA section 3007 to all known facilities engaged in
any of the 14 inorganic chemical manufacturing processes. During our
field investigations we made site visits to familiarize ourselves with
processes and residuals, and made additional visits to collect samples
of residuals which we sent to laboratories for analysis. Finally, we
collected data from other sources to help characterize the settings in
which some of the wastes are managed. Each of these efforts is
summarized below.
1. The RCRA Section 3007 Survey
We developed an extensive questionnaire under the authority of
Section 3007 of RCRA for distribution to the inorganic chemicals
manufacturing industry. The purpose of the survey was to gather
information about solid and hazardous waste generation and management
practices in the U.S. for the fourteen inorganic chemical industry
sectors. The questionnaire collected information about the inorganic
chemical products manufactured, the processes used, the wastes
generated, the wastes characteristics, and how the wastes were managed.
The questionnaire is included in the ``General Background Document for
the Inorganic Chemical Listing Determination.'' which is in the docket
for today's proposal. This document also provides more details on the
producers identified in the inorganic sectors.
We distributed the survey in March of 1999 to all 124 facilities
that we had identified as potential manufacturers of chemicals in the
14 targeted sectors. We developed the list of facilities from a review
of the available literature, which included directories of chemical
producers, reference works of chemical technology, chemical profile
information, and previous work by EPA on these industries. From the
surveys distributed, 57 facilities indicated that they manufacture
chemicals from at least one of the 14 sectors. The other facilities
notified us that they had either stopped operations or did not
manufacture inorganic chemical products. From the survey, we confirmed
that one product was no longer manufactured in this country (phenyl
mercuric acetate).
We also conducted an exhaustive engineering review of the submitted
surveys for accuracy and completeness. We conducted quality assurance
reviews of the data to identify any inappropriate entries and missing
data. The engineering review of each facility's
[[Page 55690]]
response resulted in follow-up letters and/or telephone calls to the
facilities seeking clarifications, corrections, and additional data
where needed.
Where we conducted sampling and analysis of the waste, we used this
analytical data in our analysis (see the following section). Facilities
also submitted data in their survey on the composition of some of their
wastes. In the absence of our own analytical data, we used data
provided by facilities in our evaluation. These cases are noted in the
sector-specific discussions in section III.F. In some cases, these data
consisted of results from testing to determine whether the wastes
exhibited characteristics. We thought such data were reliable because
of the consequences the facilities would face if their characteristic
data were not accurate. In addition, survey respondents were required
to certify the accuracy of their submittal.
2. Field Work: Site Visits, Sampling and Analysis
As part of our field work, we visited production facilities
(engineering site visits), we took preliminary samples (familiarization
sampling), and we obtained samples to fully characterize the waste for
constituents of concern (record sampling). We initiated the sampling
phase of this listing determination with the development of a Quality
Assurance Project Plan (QAPP) for sampling and analysis. The QAPP
describes the quality assurance and quality control requirements for
the data collection. We also developed sampling and analysis plans
(SAPs) for sampling at individual facilities. The QAPP and the SAPs are
available in the public docket for this proposal.
The primary purpose of the engineering site visits was to gain
first hand knowledge of the manufacturing processes, the waste
generation and management, and to identify potential locations for
waste sampling. We conducted site visits at 25 facilities in 12 of the
sectors. We selected the facilities to visit based on logistics and to
visit sites that represent the variety of process and wastes generated
within industry sectors. Site visit reports are available in the docket
for today's rule. During some of the engineering site visits, we
collected 22 familiarization samples to help us identify potential
sampling or analytical problems for the wastes of interest. For
example, we used the familiarization samples to assess the
effectiveness of the analytical methods that we planned to use during
record sampling for a number of the targeted waste matrices.
During record sampling, we collected 69 waste samples from 13
different facilities. Additional samples were collected for QA/QC
purposes. Largely due to the time constraints imposed by our consent
decree schedule, we focused the sampling effort on the wastes that we
most expected to present significant potential risks. Based on
information obtained from the RCRA Section 3007 Surveys, we established
sampling priorities by considering the reported management practices
(e.g., wastes going to Subtitle D landfills and impoundments were of
concern), and the likely presence of contaminants of concern.
We also found that we were able to make listing decisions on a
variety of reported wastes without conducting sampling. In some cases,
we were able to use information about the processes and the raw
materials to conclude that a waste was not likely to present a
significant risk. Also, we did not typically sample wastes that were
reported to be characteristically hazardous waste and were already
regulated as hazardous under RCRA. We felt that, for these wastes, we
could make listing decisions without further information on waste
constituents. In addition, we did not attempt to sample wastes that we
found to be outside the scope of the consent decree, as described in
Section III.B. Thus, for example, we did not sample a number of wastes
that appeared to be exempt under the Bevill regulations.
We believe that the 69 record samples from 13 sites provide an
adequate characterization of the wastes that we sampled. The 13 sites
represent approximately 30% of the 42 identified production facilities
within the specific sectors we chose for sampling. The wastes sampled
also represent the major waste types of concern, e.g., specific process
wastes/sludges, wastewater treatment sludges, wastewaters, and spent
filter material. Section III.F of this proposal provides information on
the specific wastes sampled in each sector. The docket for today's
proposal also contains background documents for the specific sectors,
which give details on which wastes we sampled and our evaluation of the
need for sampling or modeling certain wastes.
For most sectors, we focused our analyses on metal constituents,
because these are the constituents expected from the inorganic
processes under evaluation. We analyzed for other constituents in those
cases where we expected they might be present in the waste, or if other
constituents showed up in the familiarization sampling. Thus, we
analyzed wastes from the inorganic hydrogen cyanide industry for
cyanide and volatile organics because of their potential to be present
from the process. Similarly, in the titanium dioxide sector, we
analyzed waste samples for semivolatile and chlorinated organics due to
the use of coke and chlorine as raw materials in the production process
for the titanium chloride intermediate. The overall list of target
analytes are in the QAPP, which is in the docket for today's rule. The
docket also contains the background documents for each sector and the
corresponding waste characterization data reports, which show the
chemical analyses performed and the analytes found in the waste
samples.
In our analyses of wastes samples, we performed analyses to measure
constituent concentrations in the wastes themselves (``total''
analysis), as well as analyses for constituents that leach out of the
wastes. We generally used the methods specified in OSW's methods manual
(``Test Methods for Evaluating Solid Waste, Physical/Chemical
Methods,'' SW-846), as described in the QAPP, the SAPs, and the
background documents for the specific sectors. We used two extraction
methods to measure leaching, the Toxicity Characteristic Leaching
Procedure (TCLP, SW-846 method 1311), and the Synthetic Precipitation
Leaching Procedure (SPLP, SW-846 method 1312).
In general, we were able to measure the concentrations of
constituents in waste samples at very low detection levels. However,
for some constituents in some matrices the SPLP and/or TCLP analyses
provided detection limits that were somewhat above health-based levels
of concern. In such cases, we examined all of the analytical data to
determine if the undetected constituent might possibly present a
potential risk. Where we did not detect the constituent in the total
analysis (i.e., the analysis of a sample prior to any leaching), we
assumed that the constituent was not present in the leachate. However,
if the totals analysis showed the presence of a constituent that we did
not detect in the leachate, then we assessed the risk that would be
posed if the constituent were present at a concentration equal to one-
half the detection limit. Section III.F shows the cases where we used
this assumption in our evaluation of wastes for the different inorganic
sectors, and further details are available in the background documents
for each sector.
3. Other Sources
We also collected data from a variety of other sources to help
characterize the settings in which these wastes are managed. For
example, we contacted
[[Page 55691]]
several state and local authorities to collect information regarding
the location of drinking water wells. We also obtained information and,
in some cases analytical data, from state authorities and other sources
to help in our evaluations. We note these sources in the sector-
specific discussions in Section III.F when we relied on such data.
D. How Did EPA Evaluate Wastes for Listing Determinations?
1. Listing Policy
As discussed in section II.A. of this preamble, we consider the
listing criteria set out in 40 CFR 261.11, in light of all the
information we have relevant to the criteria, in making listing
determinations. For decisions made under 40 CFR 261.11(a)(3), today's
proposed listing determinations follow the elements of the EPA's
hazardous waste listing policy presented the proposed listing for
wastes generated by the dyes and pigments industry (see FR 66072,
December 22, 1994). We have modified and adapted this policy in
subsequent listings. See for example the recent Petroleum Refining
proposal (60 FR 57747; November 20, 1995) and the Solvents waste
proposal (61 FR 42318; August 14, 1996).
This policy uses a ``weight-of-evidence'' approach in which
calculated risk information is a key factor to consider in making a
listing determination under 40 CFR 261.11(a)(3). The criteria provided
in 40 CFR 261.11(a)(3) include eleven factors for determining
``substantial present or potential hazard to human health and the
environment.'' We incorporate nine of these factors, as described
generally below, into our risk evaluation for the wastestreams of
concern:
--Toxicity (261.11(a)(3)(i)) is considered in developing the health
benchmarks used in the risk evaluation.
--Constituent concentrations and waste quantities (261.11(a)(3)(ii) and
261.11(a)(3)(viii)) are used to define the initial conditions for the
risk evaluation.
--Potential to migrate, persistence, degradation, and bioaccumulation
of the hazardous constituents and any degradation products
(261.11(a)(3)(iii), 261.11(a)(3)(iv), 261.11(a)(3)(v), and
261.11(a)(3)(vi)) are all considered in our evaluation of constituent
mobility (e.g., leaching from waste) and fate and transport models we
used to project potential concentrations of the contaminants to which
individuals might be exposed.
We considered two additional factors, plausible mismanagement and
other regulatory actions (261.11(a)(3)(vii) and 261.11(a)(3)(x)) in
selecting the waste management scenarios we evaluated in our risk
assessments. For example, we used information that the waste generators
submitted in their Section 3007 questionnaires to decide what types of
waste management units are used. Using information about other federal
environmental regulatory programs, we concluded that some units or some
pathways did not pose risks requiring evaluation.
We separately considered the remaining factor, whether the
available information indicated any impact on human health or the
environment from improper management of the wastes of concern
(261.11(a)(3)(ix)). Thus, we examined a variety of databases for
information on damage incidents for the inorganic chemical production
processes under investigation. For example, we examined databases for
information on potential and actual Superfund sites (CERCLIS), releases
reported under the Toxic Release Inventory System (TRIS), civil cases
filed on behalf of EPA, and spills and releases reported to the
National Response Center (NRC). A full description of our search is in
the docket for this rule.
Most of the cases found for these industries typically resulted
from spills or releases of products, and did not provide any useful
information of possible risks presented by the wastes we evaluated for
listing. In a few cases we found sites on the Superfund National
Priority List (NPL) that included inorganic manufacturing processes.
However these sites usually encompassed a variety of chemical
manufacturing and mining industries, and it is difficult to attribute
the damage reported to the specific inorganic manufacturing wastes
under evaluation. Furthermore, contamination at these sites appears
linked to historical management practices at closed or inactive
manufacturing plants, and these were not useful in assessing current or
potential hazards for the wastes at issue. In addition, Federal and
State regulatory controls are now in place that would prevent
mismanagement. For example, many of the wastes examined in today's
proposal are regulated as characteristic waste, and releases or
disposal to the land are addressed under the existing RCRA regulations.
We did not find any evidence of actual damage cases.
We describe our decisions under 40 CFR 261.11(a)(3) in more detail
in the sector-specific discussion in section III.F below, and in the
background documents. Generally, we conducted full-scale risk modeling
for 18 wastes in 5 sectors. We found that we could adequately address
the risks of the remaining wastes with a variety of less time-consuming
approaches. Some were qualitative; others were quantitative, but not as
complex as full modeling.
We evaluated one waste using the single criterion set out in 40 CFR
261.11(a)(1) rather than the eleven factors referenced in 40 CFR
261.11(a)(3). This is the first time under this consent decree that we
have proposed to make a listing decision based on this criterion. It
relies on the existing characteristics to identify wastes posing
significant risks and does not require the use of modeling. See the
discussion of wastes from the production of antimony oxide in section
III.F.1 of the preamble.
Our proposed listing determinations are based upon estimates of
individual risk. We relied on individual risk estimates (HQs > 1), and
not population risk estimates, because we are concerned about risks to
individuals who are exposed to potential releases of hazardous
constituents. We believe that using individual risk as a basis for our
listing determinations (rather than population risk estimates) also is
appropriate to protect against potential risks, as well as present
risks that may arise due to the generation and management of particular
wastestreams. EPA acknowledges that in cases where small populations
are exposed to particular wastes and waste management practices,
population risks may be very small. We did not attempt to calculate
population risks for the proposed listings. In general, we expect
population risks arising from contaminated groundwater due to waste
management to be small, because often only a limited number of domestic
wells will be near these facilities, and groundwater contamination
often moves very slowly. Nevertheless, the increased risk for an
exposed individual may be significant. In proposing the listing
determinations for K176, K177, and K178, EPA is protecting against the
potential risk for exposed individuals, regardless of how many
individuals are exposed.
We set out below general observations about some of our approaches
to risk assessment.
2. Characteristic Hazardous Waste
We describe in Section a. below our analysis for wastes which are
``100% characteristic''--wastes which all generators report as
characteristic and which all generators appear to manage in compliance
with applicable hazardous waste regulations. We
[[Page 55692]]
describe our approach to wastes which are occasionally characteristic--
but managed in compliance--in Section b. below. Finally, we discuss in
Section c. one waste which appears to exhibit a characteristic
frequently, but does not appear to be managed in compliance with
hazardous waste regulations.
a. Wastes consistently exhibiting characteristics. For wastes which
these industries identified as characteristic and managed in compliance
with hazardous waste regulations, we are proposing to find that there
is no ``plausible mismanagement'' scenario to evaluate for listing.
(See 40 CFR 261.11(a)(3)(vii).) The Subtitle C rules applying to
characteristic wastes adequately protect human health and the
environment, especially where waste generators are complying with them.
40 CFR 261.11(a)(3)(x) authorizes us to consider actions taken by other
regulatory programs. We believe we can reasonably interpret this to
include the rules for characteristic wastes under Subtitle C .
We acknowledge that the regulation of characteristic wastes differs
in some ways from the regulation of listed wastes. For example, for
characteristic wastes, residues from treatment required by the land
disposal restrictions need not always be placed in hazardous waste
disposal units. However, we do not regard the differences as
``mismanagement.'' Rather, we believe that both approaches protect
human health and the environment. Consequently, for the purposes of
this rule we decided that we would not propose to list a ``100%
characteristic'' waste unless we found evidence of extraordinary risks
under one or more of the other factors in 40 CFR 261.11(a)(3).
For a few of the 100% characteristic wastes in this rule, we found
factors warranting further consideration. For example, we found that
the sole generator of cadmium pigment wastes codes them as hazardous,
arranges for treatment to comply with the land disposal restrictions,
and then disposes of treated residues in a Subtitle D landfill. At the
same time, we found that the waste contains very high levels of
cadmium. We decided to investigate further to ensure that the treatment
residues did not present significant risks. We examined data relating
to the treatment process and leachate monitoring data from the landfill
receiving the residues. Based on these data, we concluded that the
residues did not pose risks warranting listing.
b. Wastes which sometimes exhibit characteristics. Information
submitted in responses to the Section 3007 questionnaires also showed
that there are a number of wastes that exhibit characteristics at some
facilities, but not others. Consistent with previous listing decisions
(see for example, the most recent petroleum refining listing at 63 FR
42137), we focused on the volumes of waste that did not exhibit
characteristics in our listing evaluation. For wastestreams identified
as exhibiting characteristics and apparently managed in compliance with
applicable regulations, we relied on the ``no plausible mismanagement''
and ``other regulations'' analysis described above. A hypothetical
example follows. If one facility generated 40 tons per year of a
properly-managed characteristic waste, and a second facility generated
60 tons per year of a non-characteristic waste, we would not evaluate
the total of 100 tons of waste under a single approach. Rather, we
would evaluate the characteristic waste under the approach described
above. For the waste that did not exhibit a characteristic, we would
conduct the type of risk assessment described below in section III.E.
c. Characteristic wastes not managed in compliance with Subtitle C.
In one case, we found a characteristic waste where we believe that
existing Subtitle C rules do not adequately prevent mismanagement. Four
facilities generate a baghouse filter waste from the production of
antimony oxide. Data from our sampling and analysis at 2 facilities
showed exceedences of the toxicity characteristic. Two facilities
recycle these wastes in a manner that may comply with applicable
regulations. Two other facilities, however, did not identify their
waste as characteristic wastes, and appear to manage them in ways which
do not comply with Subtitle C rules. Because of this apparent
noncompliance, we concluded that it would be appropriate to disregard
the characteristic rules in an analysis of the factors in 40 CFR
261.(a)(3). However, we also concluded that it was not necessary to
conduct such an analysis. Since this waste fails the toxicity
characteristic, it clearly contains levels of constituents which could
pose threats to human health via groundwater when placed in a municipal
landfill, if leachate were to migrate to a drinking water well at
sufficient concentrations. Since the generators are not managing the
wastes in compliance with applicable Subtitle C regulations, we assume
that this type of mismanagement could occur at other sites.
Accordingly, we exercised our authority to propose to list this waste
under 40 CFR 261.11(a)(1). As noted above, this provision authorizes
(but does not require) EPA to list wastes that exhibit characteristics
without the analysis required under 40 CFR 261.11(a)(3). We believe
that noncompliance is an appropriate reason to use this authority to
list a characteristic waste.
d. Non-characteristic wastes disposed of in hazardous waste units.
We identified nine wastes which do not appear to exhibit any
characteristic, but which are disposed of in Subtitle C management
units. Four of these wastes are sent to combustion unit regulated under
Subtitle C of RCRA. The remaining 5 wastes are sent to Subtitle C
landfills. We found that all of these wastes receive some treatment
before land disposal. In one case available data indicates that the
waste meets applicable LDR treatment standards as generated.
In general, these wastes have very limited potential for
mismanagement under 40 CFR 261.11(a)(3)(vii). This is particularly true
for wastes which generators place in on-site, Subtitle C units with
ample capacity. Also, in some cases, some of the wastes are generated
in very small quantities (less than 1 metric ton per year). These
wastes are distinguishable from a non-characteristic organobromine
waste sent to a hazardous waste unit that we decided to list in 1998.
That waste had extremely high concentrations of a constituent posing
significant risks, and received no treatment (see May 4, 1998; 63 FR
24596).\3\ We request comment on the individual rationales set out in
the sector-specific discussions and the background documents.
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\3\ On April 9, 1999, the D.C. Circuit in Great Lakes Chemical
Corporation v. EPA ordered that the organobromine listing
determinations be vacated. Accordingly, EPA removed the listings
from CFR (see 65 FR 14472: March 17, 2000).
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3. Evaluations of Particular Units and Pathways of Release
We are proposing to find that some pathways of release from some
units present low risks because they are adequately controlled under
other Federal environmental regulations that minimize the likelihood of
releases. We are also proposing to find that other risk pathways
present low risks due to physical or chemical attributes of the wastes.
In some cases, we evaluated all release pathways at a single unit under
a combination of these approaches.
a. Wastewater management. Facilities in these industries generally
treat wastewaters in on-site wastewater treatment plants and discharge
to surface waters, or pretreat the waste and discharge to an off-site
wastewater
[[Page 55693]]
treatment facility, e.g., a Publicly Owned Treatment Works (POTW).
Under the Clean Water Act (CWA), discharges to surface waters are
controlled under the National Pollutant Discharge Elimination System
(NPDES) and require an NPDES permit, while discharges to a POTW are
subject to State and national pretreatment standards.\4\ Point source
discharges for the various sectors in the inorganics listing are
regulated under the CWA by the effluent guidelines and pretreatment
standards in 40 CFR Parts 415 (Inorganic chemical manufacturing) and
422 (Phosphate manufacturing). Therefore, we did not evaluate NPDES
effluent or discharges to POTWs in today's proposal. This approach is
consistent with other listing rules. See, for example, 60 FR 57759
(November 20, 1995, petroleum refining wastes proposal). In a few
cases, facilities reported disposal of wastewaters by deep well
injection in a permitted Class I UIC hazardous waste injection well. In
these cases, the wells were units regulated by the Underground
Injection Control (UIC) program under the Safe Drinking Water Act (40
CFR Part 144). These wells also had no migration exemptions under
Section 148.20 to allow disposal of untreated hazardous waste.
Therefore, we did not evaluate this scenario further.
---------------------------------------------------------------------------
\4\ In fact, 40 CFR 261.4 excludes ``any mixture of domestic
sewage and other wastes that passes through a sewer system to a POTW
for treatment'' (40 CFR 261.4(a)(1)(ii), and industrial wastewater
discharges that are point source discharges subject to regulation
under Section 402 of the CWA (40 CFR 261.4(a)(2)).
---------------------------------------------------------------------------
For surface impoundments, we concluded that releases to air were
not likely to present concerns. For most sectors, the constituents of
concern are nonvolatile metals, and this makes volatilization a highly
unlikely pathway for constituents from normal wastewater treatment
practices. We recognize that releases of volatile organic chemicals
from impoundments may be a potential route of concern for one sector,
inorganic hydrogen cyanide production. EPA is developing maximum
achievable control technology (MACT) standards for cyanide
manufacturing under the Clean Air Act (CAA), which may address these
emissions.\5\ EPA is evaluating possible air releases from wastewaters
in impoundments as part of the MACT rulemaking. Therefore, we did not
do any further evaluation of these emissions as part of today's listing
determination. We assessed the potential for groundwater releases from
the impoundments.
---------------------------------------------------------------------------
\5\ Clean Air Act--Title III: Upcoming MACT Standards--Cyanide
Chemical Manufacturing; Unified Air Toxics Website: http://www.epa.gov/ttn/uatw/mactupd.html: The hydrogen cynaide industry
would also be subject to regulations under 40 CFR Part 60, Subpart
YYY under the CAA for volatile organic compound (VOC) emissions from
wastewater treatment at facilities in the synthetic organic chemical
manufacturing industry (SOCMI), which was proposed September 19,
1994 (59 FR 46780).
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For sectors and wastes where facilities did not use surface
impoundments for wastewater management, we determined that ``plausible
mismanagement'' would be continued management in existing tank-based
treatment systems. We do not view abandonment of existing treatment
systems for surface impoundments as ``plausible,'' because the
manufacturers have already made a considerable investment in wastewater
treatment systems using tanks and will continue to use them. Further,
we assumed that wastewater treatment tanks retain sufficient structural
integrity to prevent wastewater releases to the subsurface (and
therefore to groundwater), and that overflow and spill controls prevent
significant wastewater releases. Thus, based on the lack of any
significant likelihood of release of the constituents to groundwater,
we did not project significant risks to groundwater from these wastes
in the tank-based wastewater treatment scenario. We did not model any
releases to groundwater from tanks. This is consistent with our
approach in other listing rules (see, for example, the proposed rule
for chlorinated aliphatics production wastes at 64 FR 46476; August 25,
1999). We also considered the possibility of air releases from tanks.
For most wastes, the constituents of concern are nonvolatile metals,
making volatilization a very unlikely pathway of release from tanks.
For the hydrogen cyanide sector, where volatile compounds are likely
and tanks are used in wastewater treatment systems, the tanks will also
be covered by other CAA regulations as described above. In addition, in
many cases facilities have installed tank covers, further reducing the
likelihood of release to the air. As a result, we have not modeled
releases to air from tanks for any wastes in this listing
determination.
b. Waste solids management. We concluded that we did not need to
model any releases of volatile constituents from solids for the same
reasons set out above. The management practices of concern for waste
solids were landfills, including disposal in on-site and off-site
landfills, and in a few cases, waste piles. We evaluated the potential
for groundwater releases from all landfills and piles. We also
considered the possibility of releases of airborne particulates by a
multistep process where we compared the total concentrations of the
constituents of concern to a series of soil screening levels (see
section III.E.3).
4. Evaluation of Secondary Materials
RCRA gives EPA jurisdiction only over materials that are discarded.
EPA's current definition of discard is set out in the definition of
solid waste at 40 CFR 261.2. Under this approach, process residuals (or
``secondary materials'') destined for recycling are solid wastes within
our jurisdiction if the recycling closely resembles waste management.
Conversely, if the materials are recycled as part of an ongoing
manufacturing process, they are not solid wastes. The existing rules
specifically exclude secondary materials from jurisdiction that are
used directly (without reclamation), as ingredients in manufacturing
processes to make new products, used directly as effective substitutes
for commercial products, or returned directly to the original process
from which they are generated as a substitute for raw material
feedstock. 40 CFR 261.2(e). In addition, the existing rules allow for
closed loop reclamation where secondary materials can be reclaimed and
returned to the original production process provided that the entire
process is closed, the reclamation does not involve controlled flame
combustion, and the reclaimed material is not used to produce a fuel or
a material that is used in a manner constituting disposal. (40 CFR
261.4(a)(8)) As discussed in the January 4, 1985, rulemaking, these are
activities which, as a general matter, resemble ongoing manufacturing
operations more than conventional waste management and so are more
appropriately classified as not involving solid wastes. However,
materials which would otherwise qualify for exclusion under these
provisions are not excluded if EPA finds that the recycling is not
legitimate. EPA considers a variety of economic and chemical factors
when it determines whether or not a specific recycling practice is
legitimate. (See Memorandum from Sylvia K. Lowrance, Director Office of
Solid Waste, concerning F006 Recycling, dated April 26, 1989). These
determinations are very site-specific and tend to be very time
consuming. EPA typically makes them in the context of site-specific
enforcement or permitting actions.
The existing rules, however, do not exclude materials that are
either contained in or used to produce fuels or that are directly used,
or incorporated into a product that is used, in a manner constituting
disposal. EPA asserts RCRA jurisdiction for these types of use/reuse
[[Page 55694]]
circumstances as they more closely resemble conventional waste
management rather than ongoing manufacturing. (See 50 FR 637-640,
January 4, 1985).
A series of court decisions also address the issue of our
jurisdiction over recycled materials. In general, they hold that EPA
lacks authority to regulate materials that are immediately reused in an
ongoing manufacturing or industrial process. American Mining Congress
v. EPA (824 F. 2d 1177 (D.C. Cir. 1987) (AMC I)); American Mining
Congress v. EPA (907 F. 2d 1179, 1186 (D.C. Cir. 1990) (AMC II));
American Petroleum Institute v. EPA (216 F. 3d 50 (D.C. Cir. 2000)).
The most recent decision, Association of Battery Recyclers, Inc. v. EPA
(208 F. 3d 1047 (D.C. Cir 2000)), remanded a rule regulating the reuse
of some closely related materials. We are still evaluating the impacts
of this decision. However, the remand does not affect this rule because
we are not relying on the exemptions in the remanded rule.\6\
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\6\ On May 26, 1998, we promulgated a conditional exclusion from
the definition of solid waste for secondary materials (other than
listed wastes) generated within the primary mineral processing
industry from which minerals, acids, cyanide, water, or other values
are recovered by mineral processing, with certain provisions.
Because this conditional exclusion only applied to non-listed
wastes, and we were making listing determinations, we did not use
this exclusion as a basis to not evaluate wastes for listing
purposes. On April 21, 2000, the D.C. Circuit Court issued a
decision vacating a portion of this conditional exclusion. [See
Association of Battery Recyclers, Inc. v. EPA. 208 F.3d 1047 (D.C.
Cir. 2000)].
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For almost all of the residual materials from these manufacturing
processes which are re-used or recycled in some way, we decided not to
attempt to determine whether the recycling practice is not subject to
regulation under the court decisions and regulations described above.
Such determinations can be very time-consuming, particularly where we
find recycling practices that appear not to be regulated, and then need
to determine whether or not such practices are legitimate.
Consequently, we decided that it would be more efficient to examine
first the potential risks posed by the reported recycling practices. If
we found no significant risks, we would decide not to list the
material. If, on the other hand, we found risks, we evaluate the
recycling practice prior to making a listing decision.
To assess the risks of materials recycled on-site by reusing them
in one of the consent decree manufacturing processes, we first
evaluated the management of the materials prior to their re-use. We
looked for closed piping, covers on containers, or similar barriers to
releases to the environment. Where we found such management practices,
we determined that there was no significant potential for releases. We
then evaluated the potential for releases from the consent decree
process itself. We found that the only points at which releases were
expected were either those where we were already evaluating solid
wastes for the purposes of this listing or points where the facility
released uncontained gases outside of RCRA jurisdiction. Consequently,
we felt that we were evaluating all of the potential risks (within our
jurisdiction) associated with the recycling of these materials. In the
antimony oxide sector, however, we found one residual that was being
held in containers for several years for potential reuse. Our rules
identify this practice as ``speculative accumulation'' and classify the
materials held in such a manner as solid wastes. Accordingly, we
assessed the risks posed by these accumulated wastes.
We found that a few materials are inserted into separate
manufacturing processes co-located on-site with consent decree
processes. We evaluated the potential for releases prior to reinsertion
into that separate process. However, as explained above in section
III.B, we did not evaluate any risks posed by use of residuals in
processes that are not subject to our consent decree deadline.
We also considered the risks of materials recycled off-site. We
considered the potential for release before the materials were
transferred off-site. We did not assess the off-site uses which
involved non-consent decree manufacturing processes. In a few cases,
however, we found that the reuse involved land placement or burning for
energy recovery. These activities are always regulated as waste
management under the rules and court decisions described above. In
those cases, we concluded that the materials were wastes from the
consent decree process where they were generated, and we evaluated
risks posed by the use. For example, we evaluated the risks posed by
use of residual materials from the production of boric acid as fuels
for cement kilns. In one case involving antimony oxide residuals, we
found that the residuals were sent off-site to another smelter
producing antimony oxide. This smelter happens to be located outside of
the country. We did not evaluate risks from its residuals, as we have
no legal jurisdiction to regulate them. We have evaluated the
production of antimony oxide within the U.S. in this rulemaking, so we
have evaluated the risks that would be posed if this generator changed
its practice and sent the materials to an antimony oxide smelter
located within the U.S.
For purposes of convenience, in the sector specific discussions
below (and in the various background documents) we describe all of the
residuals as wastes. We emphasize, however, that we have not determined
whether any of the residuals that are recycled are solid wastes as
defined in 40 CFR 260.2. We believe it is more appropriate to leave
such site-specific determinations to other decision-making processes.
E. Description of Risk Assessment Approaches
Before turning to the details of the risk assessment approaches
used, we want to highlight two general issues. First, we note that for
this proposal we used a variety of screening methodologies to assess a
large number of wastes. Due to time constraints imposed by the consent
decree schedule, we chose --where appropriate-- to use these
methodologies rather than conducting more time-consuming, full-scale,
risk assessment modeling. In general, however, we believe that these
screening methodologies conservatively assessed risks, so that wastes
that we ``screened out'' are unlikely to present significant risks.
Second, we want to describe our selection of plausible
mismanagement practices for both screening and full modeling
assessments. In general, we assessed the types of management units
which, according to data available to us, facilities have actually used
or contemplated using. Frequently, we found that facilities had made
economic investments that would make them likely to continue to use the
same types of units. For example, where facilities had paid to install
tanks to store or treat wastes, we assumed that they would continue to
use tanks rather than place wastes in pits or surface impoundments.
Furthermore, we found that some waste quantities were so large that it
would be prohibitively expensive to transport wastes off-site.
Similarly, where facilities had installed piping to return residual
materials to their production processes, we assumed that they would
continue to use these systems to recycle those residuals. We also
assumed that such facilities had found it more economical to return
those residuals to their processes, and were thus not likely to send
them to landfills or other types of disposal units.
We seek comment on all data, assumptions and methodologies used in
our risk assessment for this proposal.
[[Page 55695]]
1. What Risk Thresholds Were Used?
EPA's listing program generally defines risk levels of concern for
carcinogens as risks within or above a range of 1 x 10-6 to
1 x 10-4 (from 1 in 1,000,000 to 1 in 10,000) at the upper
end of the risk distribution (e.g., 90th or 95th percentile risk for a
particular exposure scenario). The level of concern for non-cancer
effects is generally indicated by a hazard quotient (HQ) of 1 or
greater at the upper end of the distribution. Consistent with the
listing policy described in the dyes and pigments proposal (59 FR
66075-66078) we used a 1 x 10-5 risk level and/or HQs of one
to identify which wastes are candidates for listing. To make a listing
determination, we then used a weight-of-evidence approach that
considers the risk estimates along with other information related to
the factors described in 40 CFR 261.11(a)(3). For cancer, a risk
threshold of one in 1,000,000 represents the probability that an
individual will develop cancer over a lifetime as a result of exposure
to a chemical contaminant. When we estimate the lifetime excess cancer
risk, we use an upper bound estimate of the carcinogenic slope factor
(CSF) as derived from laboratory studies in animals or from human
epidemiological studies. In addition, because the CSF typically relies
on a number of extrapolations (e.g., from animals to humans and from
high doses to low doses) there is some uncertainty in the value of the
CSF.
For non-cancer effects, which include a wide variety of health
effects, we used EPA's reference dose (RfD) as a risk threshold. A
reference dose is an estimate of an oral exposure that is likely to be
without an appreciable risk of adverse effects in the general
population, including sensitive individuals, over a lifetime. The RfD
can be derived from a NOAEL, LOAEL, or benchmark dose. Uncertainty
factors are applied to address limitations of the available
toxicological data and are necessary to ensure the RfD is protective of
individuals in the general population. The use of uncertainty factors
is based on long-standing scientific practice. Uncertainty factors when
combined commonly range from 10 to 1000 depending on the nature and
quality of the underlying data. The RfD methodology is expected to have
an uncertainty spanning perhaps an order of magnitude. To assess risks
associated with non-cancer effects, we used a hazard quotient (HQ),
which is defined as the ratio of the estimated dose of a given chemical
to an individual to the reference dose for that chemical. A hazard
quotient (HQ) of one (1) indicates that the estimated dose is equal to
the reference dose (RfD) and, therefore an HQ of 1 is EPA's threshold
of concern for non-cancer effects. Usually, doses less than the RfD
(HQ1) are not likely to be associated with adverse health risks and,
therefore, are less likely to be of regulatory concern. As the
frequency and/or magnitude of the exposures exceeding the RfD increase
(HQ>1), the probability of adverse effects in a human population
increases. However, it should not be categorically concluded that all
doses below the RfD are ``acceptable'' (or will be risk-free) and that
all doses in excess of the RfD are ``unacceptable'' (or will result in
adverse effects).
The values of the CSF and RfD that we use for assessing risks are
generally taken from EPA's on-line toxicity data base called IRIS.
However, in some cases we used EPA's compilation of toxicity benchmarks
known as HEAST or other sources, such as toxicological issue papers
prepared by EPA's National Center for Environmental Assessment
(NCEA).\7\
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\7\ EPA's Integrated Risk Information System (IRIS) may be found
at http://www.epa.gov/iris. See also ``Risk Assessment for the
Listing Determinations for Inorganic Chemical Manufacturing Wastes''
(August 2000) for a discussion of the toxicity benchmark values used
in today's rule.
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2. What Leaching Procedures Were Used?
As noted in III.C, we used the TCLP and SPLP leaching procedures to
evaluate the wastes in today's rule. EPA developed the TCLP as a tool
to predict the leaching of constituents from the waste in a municipal
solid waste landfill, and the TC regulations use this method to
determine if a waste is hazardous under 261.24 (see the Toxicity
Characteristic rule, 55 FR 46369; November 2, 1990). We have also used
the TCLP in the listing program to estimate leaching concentrations for
use in groundwater modeling (for example, see the recent petroleum
listing, 63 FR 42110, August 6, 1998). We believe the TCLP is the most
appropriate leaching procedure to use for wastes in municipal
landfills, because the leaching solution is similar to the type of
leachate generated from the decomposition of municipal waste. The TCLP
leaching solution is a solution containing acetic acid that is adjusted
to a pH of 4.93 or 2.88, depending on the acidity of the waste sample.
EPA developed the SPLP as a method to predict leaching from wastes
or soils under exposure to the slightly acidic, dilute solution
generated by normal rainfall. The SPLP test uses a leach solution which
mimics acid rain, while the TCLP uses a leach solution which mimics
acids formed in municipal landfills. In past actions, EPA has
recognized that the TCLP's use of organic acids may not be appropriate
for disposal scenarios that do not involve municipal landfills. For
example, in the proposed rule for management and disposal of lead-based
paint debris, EPA used the SPLP to assess leaching from landfills that
do not accept municipal wastes (see 63 FR 70189; December 18, 1998).
Similarly, EPA utilized the SPLP in screening low hazard wastes as part
of its 1989 Bevill determination (see 54 FR 36592; September 1, 1989).
In the context of EPA's more recent mineral processing sector
actions, we considered the relative merits of both the TCLP and the
SPLP for various wastes in the mineral processing industries; EPA
decided to continue to rely on the TCLP for defining characteristically
hazardous Bevill wastes, in part because we found that disposal in
municipal landfills did occur for some sectors. See the Land Disposal
Restrictions Phase IV Final Rule at 63 FR 28598 (May 26, 1998). For
today's rule, however, we have specific data showing that some wastes
do not go to municipal landfills and are unlikely to be disposed of in
municipal landfills. We used the SPLP sampling results for wastes that
were not likely to go to municipal landfills, and we used the TCLP
results for wastes going to municipal landfills.
3. How Were Wastes Screened To Determine If Further Assessment Was
Needed?
We used a number of approaches to eliminate from further
consideration those wastes that could not plausibly pose unacceptable
risks. This served to identify those wastes and chemical constituents
that required further assessment. Different screening approaches were
used depending on the type of waste management practices employed in
the industry and, in some instances, the waste volume and the location
of the waste management units.
For wastes that are managed in landfills, groundwater contamination
is the primary source of human exposures, particularly for certain
metals and other inorganic compounds that are nonvolatile, such as
those present in the wastes that are the subject of today's rule. We
compared leachate concentrations derived from the TCLP or SPLP test
measurements to levels in drinking water that are protective of human
health. These levels, referred to as health-based levels (HBLs), are
designed to be protective of both
[[Page 55696]]
children and adults. Health-based levels (HBLs) are levels in
environmental media that would not exceed EPA's risk thresholds given
conservative assumptions regarding exposure (e.g., a level in drinking
water that would not exceed a risk threshold for an individual whose
drinking water intake was at the high end of the distribution for the
general population).\8\ Although an HBLs represents a concentration
level at the point of exposure, we conservatively assumed direct
contact with the wastes (i.e., no dilution) for the purpose of
screening out wastes and chemical constituents that could not pose
unacceptable risks and, therefore, do not merit further analysis. As
explained previously, we used SPLP measurements for wastes that are
managed in landfills containing only industrial wastes and TCLP
measurements for wastes that are managed in landfills which also
contain municipal wastes. For wastewaters that are managed in surface
impoundments, we used the concentration in the filtered liquid (i.e.,
the SPLP filtrate) because the filtrate is more representative of the
fraction of the waste that could infiltrate into the subsurface
environment. Regardless of the type of measurement, if the result of
the chemical analysis for a particular compound was below the limit of
detection but the compound was detected in the waste, then we used \1/
2\ the value reported by the laboratory as the limit of detection for
that compound. Any chemical contaminant in a waste that did not screen
out against HBLs (i.e., the waste concentration was a factor of 2 or
less times the HBLs \9\) we identified as a constituent of concern
(CoC) requiring further assessment. However, very low volume wastes
were subject to further screening, as described below.
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\8\ Details on how HBLs are derived may be found in the risk
assessment background document for today's proposal, ``Risk
Assessment for the Listing Determinations for Inorganic Chemical
Manufacturing Wastes'' (August 2000).
\9\ We used professional judgment to screen out constituents
with concentrations within a factor of two of the HBLs.
Historically, our models have suggested that the dilution and
attenuation of constituents in the subsurface will generally result
in dilution and attenuation factors (DAFs) of 2 or greater. (See,
for example, the DAFs estimated for the petroleum refining listing
determination, 63 FR 42110, and the docket for today's rulemaking
for DAFs calculated to support today's proposal.) If our
consideration of site-specific factors had indicated that a very low
DAF were likely for actual exposure (e.g. known drinking water wells
placed very close to the management until boundary), we would have
modeled that waste rather than screening it out using professional
judgment.
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For very low volume wastes that did not screen out against HBLs, we
performed an additional conservative screen to determine if the waste
could plausibly pose a risk to human health when disposed of in a
landfill. Typically wastes generated in volumes of less than 1 or 2
metric tons per year were considered as candidates for this de minimis
analysis. This analysis assumed that the entire mass of the chemical
contaminant in a volume of waste that is generated in a year's time
would leach out of the waste and infiltrate into groundwater in the
same year. The only dilution that was assumed to occur was with the
volume of water that infiltrated into the landfill. To minimize the
amount of dilution we chose a conservative infiltration rate based on
the infiltration that could occur for a relatively low permeability
soil underlying a relatively small landfill (corresponding to the 10th
percentile of the distribution of municipal landfill areas nationwide).
However, in some cases the resulting infiltration was less than the
amount of water that would be withdrawn from a well by a household for
domestic usage. In these instances, we diluted the infiltrate into the
minimum volume of water needed to support a household well, which we
estimated from data on U.S. per capita water consumption assuming a
family of four. The concentration derived using this procedure was then
compared to the HBLs. Any chemical contaminant that did not screen out
as a result of this analysis we identified as a constituent of concern
(CoC) requiring further assessment. While we do expect the de minimis
screen to be conservative overall, the degree to which it is
conservative depends on many waste and site-specific factors. (For
example, our sampling and analysis data indicate that in some cases
essentially all of the chemical constituent leached out of the sample
over the duration of the leach test.)
For wastes managed in waste piles and landfills, we performed a
multi-level screening analysis to determine if further assessment of
the air pathway was needed. Wind blown dust from wastes managed in
piles is a potential source of human exposures. This pathway is also
possible for landfills, but likely to result in much lower releases due
to the common usage of daily and longer-term cover at landfills. In the
first level screen we compared the waste contaminant total
concentrations to background levels in soils. Background soil levels
were taken from published compilations of levels in native soils
nationwide and were generally characterized using a geometric mean or
(in a few instances) an arithmetic mean concentration of the available
data.\10\ If the waste concentrations exceeded background levels in
soils, we performed a second level screen by comparing the waste
concentrations with soil ingestion HBLs. Soil ingestion HBLs assume
direct contact with the waste and, therefore, are more conservative
than HBLs based on inhalation exposures. In those instances when the
waste concentrations exceeded both background levels and soil ingestion
HBLs, we performed a third level screen using the results of EPA's air
characteristics study. This study developed levels of chemical
contaminants in wastes that are protective of human health with respect
to inhalation exposures when managed in a variety of ways.\11\ In
particular, air characteristic levels were developed for waste piles at
several different distances from a potential receptor. We used the air
characteristic levels corresponding to a downwind distance of 25 or 150
meters (80 or 500 feet). Because the air characteristic levels include
the effect of atmospheric dilution, they are significantly higher than
soil ingestion HBLs. In most cases waste concentrations are either
below background or below soil ingestion HBLs for the wastes EPA
evaluated. Moreover, we found no instances in which air characteristic
levels are exceeded. In the cases where waste concentrations exceeded
the soil ingestion levels, the exceedence was typically less than a
factor of 2 to 3. We believe it is highly unlikely that off-site
exceedences due to windblown dust from piles or landfills would
actually exceed the soil ingestion levels given this low level of
exceedence in the waste. Therefore, we conclude that risks associated
with particulates from piles and landfills transported by an air
pathway are not significant and no further assessment is needed.
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\10\ Different statistics may be used for characterizing
background levels depending on the data available. The mathematical
properties of the arithmetic mean allow it to be used when only
average values rather than the original data are available. However,
if the original data are available, the data can be pooled and a
geometric mean can be calculated. If the data are positively skewed,
as is often the case, the arithmetic mean will be higher than the
geometric mean. We consider either statistic to be a central
tendency measure of background levels. However, background levels
are highly variable and may be considerably higher or lower than the
national average at any given location. See, for example, the U.S.
Geological Survey paper ``Elemental Concentrations in Soils and
Other Surficial Materials in the Conterminous United States,'' paper
1270, U.S. Government Printing Office, 1984.
\11\ See U.S. EPA, ``Revised Risk Assessment for the Air
Characteristic Study,'' Office of Solid Waste, EPA 530-R-99-019,
November 1999.
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[[Page 55697]]
EPA derived HBLs for chemical contaminants from toxicity benchmarks
and a set of exposure assumptions that differ depending on the type of
health effect and exposure pathway. For carcinogenic effects, HBLs were
derived from a cancer slope factor (CSF) for the oral route of
exposure. For non-cancer effects, HBLs were derived from EPA's oral
reference dose (RfD) for the compound. Risk thresholds were as
described previously. Drinking water and soil ingestion HBLs for
individual chemical contaminants are presented elsewhere.\12\ The
exposure assumptions we used for deriving the HBLs are described as
follows.
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\12\ See the risk assessment background document for today's
proposal, ``Risk Assessment for the Listing Determinations for
Inorganic Chemical Manufacturing Wasters'' (August 2000).
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For drinking water exposures, we derived HBLs for carcinogenic
effects for an adult exposed for 30 years and having a tap water intake
of 1.4 liters per day. This represents 21 milliliters per day on a per
kilogram body weight basis, which is the mean tap water intake for
adults. A duration of exposure of 30 years represents the 95th
percentile of the distribution of residential occupancy periods for
adults nationwide. We derived HBLs for non-cancer effects for a child
having a tap water intake of 1.3 liters per day. This represents 64
milliliters per day on a per kilogram body weight basis and corresponds
to the 90th percentile of the distribution of tap water intakes in
children that are 1 to 10 years of age.\13\ Because the drinking water
HBLs incorporate conservative exposure assumptions, we consider them to
be appropriate for screening purposes.
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\13\ See EPA's ``Exposure Factors Handbook'' (EPA/600/P-95/
002Fa), August 1997, for additional details on human exposure
factors.
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Soil ingestion HBLs were derived from either the CSF or the RfD
assuming a soil ingestion rate of 200 milligrams per day and an
exposure duration of 8 years. A soil ingestion rate of 200 milligrams
per day (about 3/100th of a teaspoon) is a conservative estimate of the
mean intake rates for children in the age range of 1 to 7. An exposure
duration of 8 years is an estimate of the mean residential occupancy
period for a 6 year old child. In selecting these values for use in
deriving soil ingestion HBLs, we considered the likelihood that
children would actually come into direct contact with the wastes.
In cases where wastes are known to be managed in on-site landfills
or surface impoundments that are located adjacent to or in close
proximity to surface waters, we used additional screening criteria to
identify wastes that could have the potential to adversely impact
surface waters before eliminating the wastes from further
consideration. We used EPA's national water quality criteria for this
purpose. Specifically, we compared waste concentrations (i.e., SPLP
measurements for wastes managed in on-site landfills and SPLP filtrate
measurements for wastes managed in surface impoundments) directly to
ambient water quality criteria that have been established for the
protection of both human health and aquatic life. Any chemical
contaminant in a waste managed under these circumstances that did not
screen out against ambient water quality criteria (within a factor of
2) we identified as a constituent of concern (CoC) requiring further
assessment.
EPA recently republished ambient water quality criteria for a large
number of chemical contaminants (see 63 FR 68354; December 10, 1998).
Separate criteria for the protection of aquatic life have been
established for fresh water and salt water. In a number of instances
waste management units are located adjacent to estuarine environments.
In these cases, for screening purposes, we used the lower of the fresh
water and salt water criteria.
4. How Was the Groundwater Pathway Evaluated?
We conducted modeling analyses to assess possible risks to human
health from wastes managed in land-based units such as landfills and
surface impoundments. We used fate and transport models to estimate
contaminant concentrations that might occur in a residential drinking
water well from migration of uncontrolled releases of leachate from a
waste management unit through the subsurface environment. We assessed
human exposures to these contaminants from information on the amount of
tap water an individual drinks and the length of time an individual
might reside at a residence and utilize water from a residential well.
We then assessed what the human health risks would be as a consequence
of such exposures.
We took a probabilistic approach to the assessment of human
exposures. In this approach, we used Monte Carlo simulation techniques
to determine the distribution of groundwater concentrations to which an
individual could be exposed and combined this with distributional data
for the general population on the intake rates of tap water and the
duration of exposure. We then assessed the risks to human health from
both the middle (central tendency) and upper (high end) portions of the
distribution of human exposures. EPA defines high end as the 90th
percentile and greater of the distribution of exposures in the
population. Central tendency generally refers to the mean or 50th
percentile of the distribution. Central tendency and high end estimates
may be generated using either probabilistic or deterministic
approaches.\14\
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\14\ We relied upon the probabilistic risk estimates for today's
proposal. However, both deterministic and probabilistic approaches
are presented in the risk assessment background document.
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We evaluated potential groundwater exposures over a 10,000 year
time period. Evaluating peak doses over this time horizon allows the
model to capture the slow movement of some chemicals through the
subsurface. While exposure assumptions (e.g., land use patterns,
climate, environmental and other exposure assumptions) are expected to
change over 10,000 years, such changes are difficult to predict. We
believe such a time period is appropriate to ensure human health is
protected. Even with long time periods, we are still concerned with the
risk that would result once contamination reaches potential drinking
water wells. Given that the metals of concern do not degrade in the
environment, we believe a long modeling time period is necessary.
Further, there is uncertainty in when peak concentrations at the
receptor well may occur, and using the 10,000 year time frame makes it
more likely that we will capture the peak risk in our evaluation. EPA
has used similar time horizons for groundwater modeling in past
hazardous waste rules. \15\
---------------------------------------------------------------------------
\15\ See HWIR proposal at 64 FR 63429, November 19, 1999, and
the final rule for the recent listing of wastes from petroleum
refining at 63 FR 42157, August 6, 1998.
---------------------------------------------------------------------------
For modeling chemical concentrations in ground water, many input
parameters were varied. These included waste characterization data
(e.g., chemical concentrations and waste volumes), waste management
practices (e.g., waste management unit size and infiltration rates),
hydrogeological parameters (e.g., depth to water table, hydraulic
conductivity, and aquifer thickness), and chemical parameters (e.g.,
soil-water partition coefficient). We conducted extensive sensitivity
analyses to determine which of these parameters had the greatest
influence on the risk results. For a detailed discussion of the ground
water analysis, including parameter distributions, input assumptions,
and sensitivity analyses, see the risk assessment background document
for today's proposal, ``Risk Assessment for the Listing Determinations
for Inorganic Chemical Manufacturing Wastes'' (August 2000).
[[Page 55698]]
In assessing groundwater exposures for wastes managed in off-site
landfills, we considered the locations of every industrial and
municipal landfill known to receive the wastes and the volume of wastes
managed at each of these sites. In so doing, we considered only that
volume of waste that is currently not being managed as hazardous waste.
For wastes managed on-site by multiple facilities, we generally
considered only those facilities where groundwater exposures are
expected to be the highest. These locations were identified by
considering the concentration levels of chemical constituents in the
waste managed at the site and the proximity of on-site waste management
units, namely landfills and surface impoundments, to potential off-site
receptors. Our rationale for selecting particular locations for
conducting modeling analyses is discussed in section III.F for the
specific inorganic sectors.
a. How were contaminant concentrations in groundwater modeled? For
modeling fate and transport in the subsurface environment, we used the
groundwater model EPACMTP (EPA's Composite Model for Leachate Migration
with Transformation Products). The model consists of two coupled
modules: (1) A one-dimensional module that simulates infiltration and
dissolved contaminant transport through the unsaturated zone, and (2) a
three-dimensional saturated zone flow and transport module. Fate and
transport processes accounted for in the model are advection,
hydrodynamic dispersion, sorption equilibria, hydrolysis, and dilution
from recharge to the saturated zone. The model assumes that the soil
and aquifer are uniform porous media. EPACMTP (as used in this
analysis) does not account for heterogeneity of the aquifer or for
preferential migration pathways such as fractures and macro-pores or
for colloidal transport, any or all of which could be important at a
particular site. Although EPACMTP simulates steady-state groundwater
flow in both the unsaturated zone and the saturated zone, the model (as
used in this analysis) simulates contaminant transport from a finite
source and predicts the peak contaminant concentration arriving at a
down-gradient groundwater well. Only migration of chemical contaminants
within the surficial aquifer is modeled by EPACMTP. We did not model
migration of contaminants to deeper aquifers but, instead, based our
assessment on exposures that might occur from groundwater withdrawn
from the uppermost aquifer where contaminant concentrations are
expected to be the highest.
Equilibrium sorption of chemical contaminants onto soil and aquifer
materials is parameterized in the EPACMTP model using a soil-water
partition coefficient (Kd). For today's proposed rule, we used values
for Kd that have been derived from field studies and have been
published in the scientific literature. An empirical distribution was
used to characterize the variability of Kd for chemical contaminants
for which sufficient published data were available. However, for
several chemical contaminants having relatively few published values
(e.g., antimony and thallium), a log uniform distribution was used.\16\
Our use of empirically derived partition coefficients assumes that
sorption is linear with respect to groundwater concentration (i.e., the
Kd isotherm is linear). However, sorption is not unlimited and will
tend to level off as groundwater concentrations increase beyond the
linear range (i.e., the Kd isotherm becomes non-linear). This condition
is most likely to occur in the unsaturated zone where dilution is
limited, if leachate concentrations are sufficiently high.
---------------------------------------------------------------------------
\16\ A log uniform distribution is a distribution that has equal
probabilities at all percentiles when the parameter is transformed
into logarithms. For these chemical constituents, we used a log
uniform distribution that was centered on the geometric mean of the
available data and had a width of 3 logs. This was done to better
account for the variability normally seen in measurements of Kd.
---------------------------------------------------------------------------
EPA has sometimes used the MINTEQA2 equilibrium speciation model to
estimate Kd's for a variety of metals rather than relying solely on
field measurements. However, recently a number of technical issues have
been raised concerning the model and its application. EPA is in the
process of evaluating the model to address those issues. Therefore, we
have decided not to use MINTEQA2 for today's proposed rule. Once the
evaluation is completed and the issues are satisfactorily resolved, EPA
may again choose to use the model in an appropriate form in future
rulemakings.
Infiltration of leachate from landfills into the subsurface is
modeled using the HELP model (Hydrologic Evaluation for Landfill
Performance), a quasi-two-dimensional hydrologic model used to compute
water balances for landfills. We assumed that landfills have a final
earthen cover but no liner or leachate collection system. The net
infiltration rate that is calculated by the model considers, among
other factors, precipitation, evapotranspiration, and surface runoff
and depends on the type of soil and the climate where the landfill is
located. For surface impoundments, the infiltration rate is estimated
from the liquid depth in the impoundment and from the hydraulic
conductivities and thicknesses of the sediments and the underlying
soil. We assumed that surface impoundments have no liner or leachate
collection system. Unconsolidated or loose sediments are treated as
free liquid so that the pressure head on the underlying, consolidated
sediments is determined by the depth of the liquid in the impoundment
and the depth of the unconsolidated sediments. As sediment accumulates
at the base of the impoundment, the weight of the liquid and upper
sediments acts to compress (or consolidate) the lower sediments. The
result is the formation of a consolidated sediment layer having a
hydraulic conductivity that is much lower than the previously
unconsolidated sediment.
We assumed that landfills have an operational life of 30 years.\17\
In landfills, leaching of contaminants from the waste leads to an
exponential decrease in the leachate concentration with time. The rate
at which this occurs depends on the volume of waste disposed of in the
landfill and the total concentration of chemical contaminants in the
waste. We used the measured TCLP concentration (for disposal in a
municipal landfill) or SPLP concentration (for disposal in an
industrial landfill) as the initial leachate concentration for
modeling. In contrast, we assumed that surface impoundments have an
operational life of 50 years.\18\ Many surface impoundments are
periodically dredged and, therefore, can be maintained in service for
longer periods of time. With surface impoundments, leachate
concentrations are not expected to decrease over time and, therefore,
leachate concentrations are assumed to remain constant during their
operational life. We used the total concentration of chemical
contaminant measured in the wastewater or (for wastewaters with high
levels of solids) the concentration measured in the SPLP filtrate as
the leachate concentration for modeling.
---------------------------------------------------------------------------
\17\ U.S. Environmental Protection Agency, ``Draft National
Survey of Solid Waste (Municipal) Landfill Facilities,'' Office of
Solid Waste, Washington, D.C., 1988 (EPA/530-SW-88-034).
\18\ See assumptions made for the recent proposed hazardous
waste identification rule at 64 FR 63382; November 19, 1999.
---------------------------------------------------------------------------
The fate and transport simulation modules in EPACMTP are linked to
a Monte Carlo module to allow quantitative consideration of variability
[[Page 55699]]
and uncertainty in groundwater concentrations due to variability and
uncertainty in model input parameters. We use a regional site-based
methodology to associate the appropriate regional climatic and
hydrogeologic conditions to the location of actual waste management
sites. This methodology accommodates dependencies between the various
model input parameters. In this approach, a site location is assigned
to one of 13 hydrogeologic regions and one of 97 climatic regions that
are linked to databases of climatic and hydrogeologic parameters. A
climatic data set provides infiltration and recharge values for three
soil textures at each of 97 climatic centers in the contiguous United
States. The soil textures are based on a Soil Conservation Service soil
mapping database and U.S. Department of Agriculture definitions of
coarse, medium, and fine soil textures. (These textures are represented
in EPACMTP by sandy loam, silt loam, and silty clay loam,
respectively.) Infiltration rates for the waste management unit and the
recharge rate for the surrounding region were determined for each soil
type and climatic center using the HELP model. A site location is
generally assigned to the climatic center that is geographically
closest to the site.
Each site location is also located on a groundwater resource map
(from a U.S. Geological Survey inventory of State groundwater resource
maps) and a hydrogeologic region is assigned to the site based on the
primary aquifer type at that location. A hydrogeologic database
provides a distribution of values for depth to groundwater, aquifer
thickness, hydraulic gradient, and hydraulic conductivity for each of
13 hydrogeologic regions. The hydrogeologic data base (HGDB) was
developed from a survey of hydrogeologic parameters for approximately
400 hazardous waste sites nationwide. These site-specific data were
then regrouped according to hydrogeologic classifications, and a
distribution of parameter values was generated for each of the 13
hydrogeologic regions (made up of 12 specific hydrogeologic
environments and one miscellaneous category). In the analysis for
today's rule, we modified the above approach for on-site waste
management units to enable available site-specific information on depth
to groundwater to be used in place of the values found in the database.
We also used a regional site-based methodology to associate the
appropriate soil characteristics to a given site location. In this
approach, a distribution of soil textures at a site is determined by
associating the site location with a soils classification region. We
defined soil classification regions from information on the soil types
found within a 100 mile radius of the site location. The distribution
of soil textures for the region was determined by identifying the soil
texture classifications from data contained in the U.S. Department of
Agriculture (Natural Resources Conservation Service) STATSGO (State
Soil Geographic) data base. The predominant soil textures within each
mapping unit (which represents a collection of soils) were identified
and the fraction of the three soil textures used in the EPACMTP model
were determined (i.e, sandy loam, silt loam, and silty clay loam).
These soil classification regions were used for modeling off-site
municipal and industrial landfill sites. A similar approach was taken
for on-site landfills and surface impoundments except that the
predominate soil textures from mapping units that correspond to the
site location itself were identified. These were compared for
consistency with other soils information available for the site. Once
the fraction of the three soils textures is determined for a given site
location, a distribution of soil parameter values is generated from
information on the distribution of soil parameter values for the three
soil textures and the fraction of each soil texture for the site. These
parameters are used for modeling groundwater flow and contaminant
transport in the unsaturated zone and include saturated conductivity,
moisture retention properties, water content, and organic matter
content.
A full description of the groundwater modeling analyses conducted
for today's proposed rule may be found in the background document,
``Risk Assessment for the Listing Determinations for Inorganic Chemical
Manufacturing Wastes'' (August, 2000).
b. How were human exposures assessed? Our assessment of human
exposures to contaminated ground water is based on a residential
drinking water scenario. A different approach was used for determining
the location of exposure depending on whether the wastes are managed
on-site or are shipped off-site for disposal. For waste shipped to off-
site municipal landfills, we used EPA's National Survey of Municipal
Landfills \19\ to determine the distance from the landfill to the
receptor well. We also used these same data for off-site industrial
landfills. For wastes managed on-site in either landfills or surface
impoundments, we attempted to determine the closest point at which a
residential well could be located and, therefore, the point at which
human exposures could plausibly occur. We considered the location of
the facility property boundary, the type of land use adjacent to the
property boundary, the presence of surface waters that could intercept
ground water flow, utilization of ground water for residential or
agriculture uses, and the existence of residential drinking water wells
in the direction of ground water flow. For both on-site and off-site
waste management, we assumed the receptor well was located down-
gradient from the waste management unit and that ground water is
withdrawn from the top ten meters of the aquifer and within the lateral
extent of the contaminant plume. Exposures were further assumed to
occur out to a distance of a mile from the waste management unit.
---------------------------------------------------------------------------
\19\ Ibid.
---------------------------------------------------------------------------
Our assessment of human exposures did not consider naturally
occurring background levels in ground water. Background levels in
ground water are not a significant source of human exposure for several
of the more important chemical constituents in the wastes that are the
subject of today's proposal (e.g., antimony and thallium). However, for
manganese, dietary exposures are a significant source of background
exposures. We did not attempt to quantify the cumulative risks from
both dietary and drinking water exposures combined and, therefore, this
is a source of uncertainty in our assessment of risks from manganese in
these wastes.
Human exposures were characterized in terms of lifetime average
daily dose (LADD) and average daily dose (ADD) for both children and
adults. We used the LADD for assessing cancer risks and the ADD for
assessing risks from non-cancer effects (including reproductive,
developmental, neurological, cardiovascular, hematologic, metabolic,
and a wide variety of other physiologic effects). Exposures to children
of age one to six years and adults of age 20 to 64 years were assessed.
We used information from EPA's Exposure Factors Handbook \20\ to
characterize tap water intake rates for individuals and residential
occupancy periods of households (and, therefore, the length of time an
individual could be exposed to contaminated ground water).
Distributional data on tap water intake rates for individuals and
residential occupancy periods for households were
[[Page 55700]]
used to generate both the ADD and LADD exposure estimates. For
assessing lifetime exposures, we averaged the well water concentrations
over the duration of exposure (i.e., the residential occupancy period).
We also averaged the tap water intake rates over the duration of
exposure to account for the changes in tap water intake rates with age
that are seen among children. For estimating the ADD, we used the peak
9-year average well water concentration but did not further average the
estimated exposure (which we believe would be inappropriate given the
range of possible health effects we want to protect against). Previous
work with the EPACMTP ground water model has shown that the peak 9-year
concentration and the maximum predicted concentration are nearly
identical.
---------------------------------------------------------------------------
\20\ U.S. Environmental Protection Agency, ``Exposure Factors
handbook'', Volumes I and III, Office of Research and Development,
National Center for Enironmental Assessment, Washington, DC., August
1997 (EPA/600/P-95/002Fa and c).
---------------------------------------------------------------------------
A full description of the methods and data used in the exposure
assessment for today's proposed rule may be found in the background
document, ``Risk Assessment for the Listing Determinations for
Inorganic Chemical Manufacturing Wastes'' (August, 2000).
5. How Was the Surface Water Pathway Evaluated?
A number of facilities that generate wastes covered by today's
proposed rule are located adjacent to rivers or bays. As a consequence,
the potential exists for subsurface releases of chemical contaminants
from on-site management of the wastes to enter these river and bay
systems through ground water inflow. In instances where no direct
contact with ground water is likely to occur (as there would otherwise
be if, for example, ground water was being used for residential
drinking water), it becomes important to evaluate the potential water
quality impacts of these releases on surface waters in the context of
hazardous waste listings. However, we wish to emphasize that the
surface water impacts considered in today's proposed rule are due to
subsurface releases to ground water only. Direct discharges to surface
waters are already regulated by the Clean Water Act under the NPDES
permit system and are not considered further in today's proposal.\21\
---------------------------------------------------------------------------
\21\ Industrial wastewater discharges that are regulated under
the National Pollutant Discharge Elimination System (NPDES) Permit
Program are specifically excluded from regulation as hazardous
wastes under 40 CFR 261.4(a)(2).
---------------------------------------------------------------------------
We conducted a screening level analysis to evaluate potential
surface water impacts. In this analysis, we estimated the volume of
leachate that would infiltrate into ground water and assumed that this
entire volume would be intercepted by surface water. Because this is a
screening analysis, we made conservative assumptions that are likely to
overstate the infiltration of leachate and, therefore, the potential
release to surface water. For example, for on-site landfills, we
assumed a soil type (sandy loam) that is likely to overstate the
infiltration rate even in the absence of liners or leachate collection
systems. Similarly, for surface impoundments we assumed a sludge
thickness (8 inches) and soil type (sandy loam) that is likely to
overstate the infiltration rate. In addition, we assumed no retardation
in the migration of chemical contaminants in ground water due to
sorption or other processes.
Due to the nature of these releases, which are likely to occur over
a wide area, we assumed that the inflow of contaminated ground water
was rapidly diluted into surface water and that there was little or no
mixing zone. We followed EPA's Office of Water guidance for determining
the design flows for rivers as regards water quality criteria. The
appropriate design flow depends on the particular water quality impact
being evaluated. For assessing potential impacts on aquatic life, we
used the ``7Q10'' as the design flow. The 7Q10 is the seven day low
flow with a return frequency of once every 10 years and is the
recommended design flow for use with chronic water quality criteria for
the protection of aquatic life. We believe that chronic water quality
criteria are the appropriate criteria for evaluating the potential
impact of continuing steady releases, such as those that would result
from subsurface discharge of contaminated ground water. On the other
hand, EPA generally uses the ``30Q5'' as the design flow for assessing
potential impacts on human health. The 30Q5 is the thirty day low flow
with a return frequency of once every 5 years and is the recommended
design flow for use with water quality criteria for the protection of
human health as regards non-cancer effects. However, a 30Q5 design flow
was not available in all cases. In these instances, we estimated the
30Q5 based on the 7Q10 design flow.\22\ For carcinogens (e.g.,
arsenic), lifetime exposures are the primary concern and a design flow
that corresponds to a longer averaging time is appropriate. For this
reason, EPA recommends the long-term harmonic mean be used as the
design flow.\23\ The harmonic mean is always less than the arithmetic
mean and is used in place of it because low flow conditions drive long-
term average water quality. However, because this flow statistic was
not available, we estimated the harmonic mean flow from the arithmetic
mean flow and the 7Q10.
---------------------------------------------------------------------------
\22\ EPA guidance provides a simple rule of thumb for estimating
the 30Q5 from the 7Q10 depending on the size of the river. For
smaller rivers (defined as those with a low flow of 50 cfs or less),
the 30Q5 is 1.1 times the 7Q10. For larger rivers (low flow of 600
cfs or greater), the 30Q5 is 1.4 times the 7Q10. See ``Technical
Support Document for Water Quality-Based Toxics Control,'' EPA/505/
2-90-001, March 1991.
\23\ The harmonic mean is defind as the inverse of the average
of the sum of the inverses of the recorded flows.
---------------------------------------------------------------------------
As a result of the screening level analysis, all wastes screened
out for which the ground water to surface water pathway was a concern.
Therefore, no additional analysis of this pathway was conducted.
6. What Are the Limitations and Uncertainties of the Assessment?
Our assessment of exposures and risks is subject to a variety of
limitations and uncertainties. These are discussed in some detail in
the background document for today's proposed rule. A number of these
are highlighted here.
We assumed our sampling and analysis data are fully representative
of the range of wastes generated in the effected industries. However,
our own data show that there are significant variations in waste
concentrations across facilities in a given industry. Variability in
waste concentration that is unaccounted for could lead to an over- or
under-estimation of risks. However, any tendency toward under-
estimation is likely to be mitigated to some extent by our selection of
wastes and exposure scenarios that are intended to capture the highest
risks.
We also assumed that our methods for measuring the leaching
behavior of wastes (i.e., the TCLP and SPLP test procedures) are both
representative of the range of leaching conditions that exist under
real world conditions and accurately quantify the concentrations of
contaminants that leach into the subsurface environment from a given
waste management unit. However, we know that many metals exhibit
varying (or amphoteric) behavior with respect to pH and that any one
test procedure is capable of characterizing leaching behavior only
under a particular set of conditions.
The ground water model we used in our analysis (i.e., EPACMTP) is
designed to characterize dilution and attenuation in the subsurface
environment under homogeneous conditions. The model does not account
for subsurface heterogeneities, nor does it account for fractured flow
or colloidal transport. These conditions, if present at
[[Page 55701]]
a site, can lead to less dilution and attenuation of contaminant levels
than predicted by the model, causing ground water concentrations to be
under estimated. In addition, sorption of metal species onto soil and
aquifer materials exhibits considerable variability depending on
geochemical conditions and the total concentration of the metal present
at a given location. Although our use of empirically derived Kd values
captures some of this variability, the available published data are
fairly limited for certain metals (e.g., antimony). We have accounted
for the uncertainty associated with the small number of data points
explicitly for these metals by expanding the range of Kd values used
for modeling (to three orders of magnitude). Even for metals that have
abundant data (e.g., arsenic), it is unlikely that the range of
variability apparent in the data could exist at a given site.
Uncertainty associated with the specification of Kd as noted above
could lead to an over- or under-estimation of risk. However, a tendency
toward over-estimation is likely to be mitigated by the fact that under
near steady-state conditions (when ground water impacts are the
greatest), concentrations in ground water are little influenced by Kd.
Under non-steady conditions, any tendency toward over- or under-
estimation is limited by the variability inherent in the empirical
distributions of Kd used in the analysis, which include both relatively
high and relatively low values of Kd. Nevertheless, in general the risk
estimates are sensitive to the specification of Kd and, therefore, this
is an important source of uncertainty in our analysis.
As indicated previously, for wastes managed on-site we based our
assessment of human exposures on the plausibility of ground water being
used for drinking water. While some information was available on
utilization of ground water for drinking water, very limited
information was available from which to determine the location of
exposure at a given site. For wastes managed off-site we assumed that
ground water is used for drinking water (or will be in the future) and
we used national data on the distribution of distances to residential
wells to assess human exposures and risk. Our analysis did not consider
possible changes in the location of on-site waste management operations
in the future. These exposure assumptions (about which there is
considerable uncertainty) may have an impact on the estimated risks
and, therefore, the outcome of the risk assessment.
Other important uncertainties include those related to the health
effects of chemical contaminants in humans (hazard identification),
absorption and metabolism of ingested contaminates (pharmacokinetics),
and biological response (dose-response relationships). These and other
limitations and uncertainties are discussed in the background document,
``Risk Assessment for the Listing Determinations for Inorganic Chemical
Manufacturing Wastes'' (August, 2000).
F. Sector-Specific Listing Determination Rationales
We seek comments on all proposed listing decisions in this section,
and the underlying rationales used to support our proposals.
1. Antimony Oxide
a. Summary. We have evaluated antimony oxide production wastes and
propose to list two wastes from this process as hazardous: (1) Baghouse
filters and (2) slag that is disposed of or speculatively accumulated.
We propose to list the baghouse filter waste under the criterion in 40
CFR 261.11(a)(1) because it routinely exhibits one or more of the
characteristics of hazardous waste, but the waste is not consistently
managed in compliance with Subtitle C regulations. We propose to list
the slag under the criteria in 40 CFR 261.11(a)(3) because of risks
associated with land disposal.
K176 Baghouse filters from the production of antimony oxide. (E)
K177 Slag from the production of antimony oxide that is disposed of or
speculatively accumulated (T).
Other wastes generated by the antimony oxide industry do not meet
the criteria set out at 40 CFR 261.11(a)(3) for listing a waste as
hazardous. They do not pose a substantial present or potential threat
to human health or the environment. We identified no risks of concern
associated with the current management of these other wastes.
b. Description of the antimony oxide industry. Antimony oxide was
produced by four facilities in the United States in 1998. Antimony
oxide is used as a flame retardant in plastics and textiles, a smoke
suppressant, a stabilizer for plastics, an opacifier in glass, ceramics
and vitreous enamels, and a coating for titanium dioxide pigments and
chromate pigment.
The manufacturers use two different processes to produce antimony
oxide. In the first process, antimony metal is roasted in the presence
of air. The antimony oxide forms as a fume, cools and condenses in a
baghouse. In the second process, crude (low grade) antimony oxide is
roasted in the presence of air to produce higher grade antimony oxide.
The antimony oxide cools and condenses in a baghouse. The crude
antimony oxide comes either from off-site or is recycled from within
the facility.
c. How does the Bevill Exclusion apply to wastes from the antimony
oxide manufacturing processes? Antimony oxide producers use a range of
raw materials to produce antimony oxide, including antimony metal
ingots, sodium antimonate, and antimony ore concentrate, and some
facilities have claimed that wastes generated from the production of
antimony oxide are Bevill exempt. Wastes generated from processes using
either antimony ingots or sodium antimonate (both of which are saleable
mineral products) are considered chemical manufacturing wastes rather
than mineral processing wastes and are not eligible for the Bevill
exemption. The September 1, 1989 Bevill final rule states at 54 FR
36620-21 that chemical manufacturing begins if there is any further
processing of mineral product.
Two of the facilities also purchase an antimony ore concentrate as
a raw material and place this material in kilns to produce antimony
oxide. The smelting of a ore concentrate above the fusion point is
defined as mineral processing (See 54 FR 36618). At these antimony
oxide facilities, since mineral processing has begun, wastes from the
process are not eligible for the Bevill exemption as beneficiation
wastes (See 40 CFR 261.4(b)(7)(i)). In addition, although there is a
Bevill exemption for 20 specific mineral processing wastes form various
mineral processing sectors, the wastes generated from antimony oxide
mineral processing are not included as one of these 20 wastes and are
not excluded. (See 40 CFR 261.4(b)(7)(ii)). Thus there are no antimony
oxide wastes that qualify for the Bevill exemption.
d. Wastes generated by these processes. Table III-1 summarizes our
information about the wastes generated from the production of antimony
oxide:
[[Page 55702]]
Table III-1.--Antimony Oxide Production Wastes
----------------------------------------------------------------------------------------------------------------
Number of
Waste category reported 1998 volume Reported waste Management practices
generators (MT) hazard codes
----------------------------------------------------------------------------------------------------------------
Antimony slag not recycled in 3 113 D008................. Sent to lead smelters for
process. lead and/or antimony
recovery; or on-site
drum storage prior to
future on-site land
disposal.
Baghouse filters.................. 4 9 No code reported..... In-process antimony
recovery; off-site
antimony recovery;
industrial Subtitle D
landfill; or non-
hazardous waste
incinerator.
Empty supersacks.................. 1 15 No code reported..... Disposal in off-site
Subtitle D landfill or
recycled.
----------------------------------------------------------------------------------------------------------------
In addition to these wastes, there are other materials produced
that are reused in the antimony oxide production process. Antimony
oxide and antimony slag are captured at various points in the facility
and reinserted into a furnace to produce antimony oxide, either on-site
or off-site. Because these materials are managed prior to reuse in ways
that present low potential for release, and because we evaluated
process waste generated after the secondary materials are reinserted
into the process, we do not believe that these secondary materials
present significant risks.
e. Agency evaluation. (1) Antimony slag not recycled in antimony
oxide process.
How Are These Wastes Currently Managed?
Three facilities produced antimony slag that is not recycled in the
antimony oxide process. Two of these facilities send the slag to lead
smelters. One of the two facilities reported its slag to be TC
hazardous because of its lead content (D008). The third facility,
however, has historically stored a portion of its slag on-site in
drums, reporting that they plan to reclaim antimony when antimony
prices are more favorable. Recent revisions to the facility's Operating
Permit,\24\ however, require that the slag be placed in an on-site
engineered ``slag storage pit'' to be constructed in the next two to
three years.
---------------------------------------------------------------------------
\24\ ``United States Antimony Corp. Stibnite Hill Mine Project
Operating Permit 00045'', 6th review draft, January 1999. This draft
permit is issued under the Metal Mine Reclamation Act, 82-4-301 MCA.
It was prepared by the facility, approved by the State of Montana on
August 12, 1999 (with a number of stipulations), and subsequently
approved by the Forest Service.
---------------------------------------------------------------------------
We assessed the on-site disposal scenario, reflecting the projected
management practice for this waste. For a number of years, the facility
has been placing approximately 20 MT/yr in steel drums on pallets on
the ground. The facility reported that they intend to reclaim the
antimony from this slag when antimony prices are favorable. We consider
storage on-site for more than one year to be speculative accumulation
and consider these materials to be solid wastes. We believe that the
length of time secondary materials are accumulated before being
recycled is an important indicator of whether or not they are wastes.
This is supported by the large number of recycling damage cases where
secondary materials that were overaccumulated over time caused
extensive harm. (See 50 FR 614) ``Under RCRA and the implementing
regulations, permanent placement of hazardous waste, including
perpetual ``storage'' falls into the regulatory category of land
disposal.'' \25\ (See also American Petroleum Institute v. EPA, 216 F.
3d 50 (D.C. Cir. 2000).) Since the Operating Permit requires the
facility to build and use an on-site, land-based unit for this waste,
we assessed the on-site landfill scenario for this waste.
---------------------------------------------------------------------------
\25\ ``Above Ground Land Emplacement Facilities, N.J. Law,''
Letter to Honorable James J. Florio, Chairman, Subcommittee on
Commerce, Transportation, and Tourism, Committee on Energy and
Commerce, House of Representatives, from J. Winston Porter,
Administrator, EPA, dated March 26, 1986.
---------------------------------------------------------------------------
How Was This Waste Category Characterized?
We selected two of the three facilities for sampling and analysis.
At the site which stores the slag indefinitely, we collected one sample
of ``reduction furnace slag'' that was designated as containing less
than 5 percent antimony (AC-1-AO-01) and one sample of ``reduction
furnace slag'' that was designated as containing between 5 and 10
percent antimony (AC-1-AO-06). Based on characterization information
provided by the facility in its RCRA Section 3007 Survey response, we
believe these samples are representative of all of the slags generated
at the facility. We conducted total, TCLP and SPLP analyses of these
slags. The analytical results for the constituents found to be present
in the leachates at levels exceeding the HBLs are presented in Table
III-2.
We collected a third sample (LI-1-AO-01) at a facility that
reclaims its slag for lead. This sample failed the TC for lead, as the
facility reported in its RCRA Section 3007 Survey response. The results
are available in ``Waste Characterization Report, Laurel Industries
Inc., La Porte, Texas'' in the docket for today's proposal.
Table III-2.--Characterization of Speculatively Accumulated Antimony Slag
--------------------------------------------------------------------------------------------------------------------------------------------------------
AC-1-AC-01 AC-1-AO-06
---------------------------------------------------------------------------------
Constituent of concern Total mg/ Total mg/ HBL mg/L
kg TCLP mg/L SPLP mg/L kg TCLP mg/L SPLP mg/L
--------------------------------------------------------------------------------------------------------------------------------------------------------
Antimony................................................. 11,500 55.8 114 127,000 110 211 0.006
Arsenic.................................................. 301 2.0 2.9 478 3.1 3.8 0.0007
Boron.................................................... 500 9.8 9.3 2,500 8.5 8.1 1.4
Selenium................................................. 50 0.6 0.6 250 0.6 0.3 0.08
Vanadium................................................. 50 1.3 1.1 250 0.6 1.0 0.14
--------------------------------------------------------------------------------------------------------------------------------------------------------
[[Page 55703]]
How Was the Groundwater Ingestion Risk Assessment Established?
We modeled the annual volume reported to be stored on-site
indefinitely (20 MT). (The facility reports that it processes sodium
antimonate from two facilities and returns the resultant slag to the
process for further processing. We did not include these recycled slag
volumes in our modeling.)
We used the total and SPLP results as model inputs, reflecting the
industrial nature of the on-site unit. We used only the analytical
results for the facility that stores the slag indefinitely. Both of the
samples for this facility are relevant because they represent the
material stored on-site and destined for the on-site slag pit. We did
not model the sample from the other sampled facility because they
acknowledged that their waste exhibited the TC. Both this facility and
the facility that was not sampled reclaim these wastes in a manner that
is excluded from regulation under Subtitle C. We believe that it is
reasonable to assume that they will continue to manage their slags in
ways that do not violate Subtitle C regulations. Also, in this case,
the SPLP results are higher than the TCLP results, making the
industrial landfill the worst case scenario.
We examined records available from the State where the slag is
stored to determine the appropriate distance-to-well to model. We
identified four residential wells within several miles of the facility.
These data demonstrate that groundwater is a viable and actively used
resource in this area. One well is located 1.4 miles directly
downgradient. Based on local topography and groundwater information, we
do not believe the other identified wells could be affected by releases
to groundwater from the facility. We modeled potential releases to a
downgradient residential well. Given that our groundwater model is not
configured at this time to model releases further than one mile, we did
not assess the full distance to the known well. In our probabilistic
analysis, we varied the well distance from the closest property
boundary that appeared to be potentially downgradient to the limit of
the model (one mile). Our results therefore are conservative with
respect to this particular well, but otherwise reflect the fact that
future residences and wells may be placed closer to the facility and
any potential groundwater plumes associated with its operation.
Specifically, we modeled potential distances to wells from the
facility's southern boundary to one mile.
We used a regional site-based approach in modeling this unit, as
described in section III.E.4. We modified this to enable us to use
available depth to groundwater information at this particular site.
What Is EPA's Listing Rationale for This Waste?
Where these slags are reused and present no exposure route of
concern, we did not evaluate these secondary materials further.
The results of the risk assessment for the on-site disposal
scenario for boron, selenium, and vanadium were very low. In the 90th
to the 95th percentile range, the highest hazard quotient for these
three constituents was in the range of 0.001. For this reason, the full
results for these three constituents are not presented here. The
results of the risk assessment for the on-site disposal scenario for
antimony and arsenic are presented in Table III-3:
Table III-3.--Probabilistic Risk Assessment Results for Speculatively Accumulated Antimony Slag
----------------------------------------------------------------------------------------------------------------
Percentile Adult risk Child risk Adult risk Child risk
----------------------------------------------------------------------------------------------------------------
\1\Antimony hazard
quotient
\1\Arsenic--cancer risk
----------------------------------------------------------------------------------------------------------------
90th%............................... 2.2 4.6 4 E-07 3 E-07
95th%............................... 4.5 9.4 1 E-06 9 E-07
----------------------------------------------------------------------------------------------------------------
For a more complete description of this analysis, see ``Risk Assessment
for the Listing Determinations for Inorganic Chemical Manufacturing
Wastes'' (August 2000) in the docket for today's proposal.
In our modeling results, the dilution and attenuation factors
(DAFs) were relatively high. For example, high end antimony DAFs were
as high as 8,000. This is the result of the hydrogeological setting of
the site evaluated. Due to the high hydraulic conductivity we used in
modeling, the landfill leachate is readily diluted into a large volume
of groundwater. Given the uncertainty about the actual ultimate
management practice and the site-specific nature of the modeling, DAFs
could be considerably lower in other disposal scenarios, resulting in
much higher hazard quotients and, therefore, higher potential risks.
Our modeling approach assumes that the slag will be placed in an
unlined unit. Information from the facility, however, indicates that
they plan to place the waste in an on-site lined storage pit, upon
completion of construction, that will be governed by a state mining
permit. We considered whether our decisionmaking should account for the
added protection provided by a liner system. Our first consideration is
the current uncertainty regarding this waste's disposition. While the
facility has stated its intended placement of this waste in a lined
unit, our most recent information indicates that construction had not
yet begun. The facility may in fact choose to place this waste in an
off-site commercial landfill that would not necessarily be lined. This
uncertainty is greater than in most waste management scenarios that we
have assessed in this rulemaking, where there is a long term history of
management in a particular type of management unit (e.g., an operating
on-site landfill, a local off-site landfill). Because of this
uncertainty, we are hesitant to give much weight to a liner system that
may be constructed in the future.
More generally, we considered the efficacy of landfills (and any
liners) over the modeled risk assessment period, which covers 10,000
years. Landfills are used actively until their capacity is reached (our
models assume an active life of 30 years), and at the end of their
active life, we assume landfills are closed and the wastes remain in
the unit indefinitely. The effectiveness of liner systems depends on
how they are designed. Composite and double liners that combine two or
more layers of liner material with leachate collection and leak
detection will no doubt minimize leakage to the subsurface during the
period when the leachate collection system is actively managed.
However, depending on the regulatory controls relevant for a particular
unit, monitoring would continue for a limited post-closure period.
There is also uncertainty associated with liner performance, in the
near term as well as in the long term. There are a variety of factors
that may influence longevity and performance, such as poor
construction, installation
[[Page 55704]]
or facility operation, or geologic movement below the liner that can
cause holes, tears or larger failures. Some defects may have a
significant effect. Because of our uncertainty regarding the efficacy
of the liner system over long periods of time, and the uncertainty over
the ultimate disposal for this waste, we believe our use of the
modeling results for an unlined landfill is appropriate.
In deciding whether to list this waste as hazardous, we also
considered other factors in addition to the risk results noted above.
First, we considered the very high levels of toxic constituents present
in the waste and in test leachate (which is one of the criterion cited
in 261.11(a)(3)(ii)). The levels of antimony and arsenic are quite
high. The antimony level exceeds 10% in the waste (up to 127,000 mg/
kg), and the SPLP antimony concentration exceeds the drinking water HBL
by a factor of >35,000. Another key factor is the lack of any
appreciable degradation expected for these metals (a constituent's
degradation or persistence is also a criterion for listing given in
261.11(a)(3)). Unlike some organic compounds, metals such as antimony
will not degrade over time. Thus, even if the loss in effectiveness of
a liner system only occurs over the very long term, the metals would
still be present for leaching. It is difficult to assess the impact of
the long-term effectiveness of the liner system in question for today's
proposal. However, we note that the effectiveness of the liner system
would have to be sufficient to reduce the antimony concentration at the
well by close to 90% in order to keep the risks below an HQ of 1.
Therefore, given the reasons cited above, we propose to list these
slags as hazardous:
K177 Slag from the production of antimony oxide that is disposed of or
speculatively accumulated.
It is important to note that this listing has been developed to
capture only those wastes that are not recycled. Thus, this listing, as
proposed, would not apply to generators that recycle or reclaim this
material as long as it is not speculatively accumulated. If slags have
been speculatively accumulated (i.e., held for more than a calendar
year without recycling) at the time of the effective date of this final
rule, these slags would meet the listing immediately.\26\
---------------------------------------------------------------------------
\26\ A material is not accumulatively speculatively, however, if
the person accumulating it can show that the material is potentially
recyclable and has a feasible means of being recycled and that--
during the calendar year (commencing on January 1)--the amount of
material that is recycled or transferred to a different site for
recycling equals at least 75 percent by weight or volume of the
amount of that material accumulated at the beginning of the period.
(40 CFR 261.1(c)(8))
---------------------------------------------------------------------------
We also propose to add antimony to Appendix VII to Part 261, which
designates the hazardous constituents for which K177 would be listed.
(2) Baghouse filters.
How Are These Wastes Currently Managed?
These filters capture product or off-specification product. Two
facilities place antimony laden baghouse filters in their on-site
production furnaces. One of these facilities also sends a portion of
its baghouse filters to Mexico for antimony recovery. Two other
facilities dispose of these wastes in a non-hazardous waste incinerator
and an industrial Subtitle D landfill. None of these wastes are handled
as hazardous, although our sampling efforts showed this waste to
exhibit the toxicity characteristic for lead and arsenic.
How Was This Waste Category Characterized?
We collected a total of three samples of this waste category from
two facilities. At one facility we collected one sample of the
``oxidation furnace'' baghouse filters (AC-1-AO-03) and one sample of
the ``reduction furnace'' baghouse filters (AC-1-AO-07). At the other
facility, we collected a sample of the baghouse associated with its
kiln (LI-1-AO-03). Because the facilities sampled represented the range
of production practices within the industry, we believe these samples
are representative of all of the baghouse filters generated by this
industry. We conducted total, TCLP and SPLP analyses of these baghouse
filters. The analytical results for the constituents found to be
present in the leachates at levels exceeding the HBLs are presented in
Table III-4. Two of the three samples of the waste, one from each
facility that generate this waste, exceed the toxicity characteristic
for either lead or arsenic. (The third sample exhibits TCLP lead levels
close to the TC standard).
Table III-4.--Characterization of Baghouse Filters From Antimony Oxide Production (mg/kg or mg/L)
--------------------------------------------------------------------------------------------------------------------------------------------------------
LI-1-AO-03 AC-1-AC-03 AC-1-AO-07 TC
Constituent of Concern ------------------------------------------------------------------------------------------ HBL ---------
Total TCLP SPLP Total TCLP SPLP Total TCLP SPLP Limit
--------------------------------------------------------------------------------------------------------------------------------------------------------
Antimony.................................. 91,400 9.3 6.2 150,000 9.9 4.3 145,000 68.7 287 0.006 ........
Arsenic................................... 114 0.5 0.6 250 0.5 0.09 250 \1\ 6.9 6.9 0.0007 5.0
Boron..................................... 24.0 6.5 1.0 2500 2 0.2 2500 2 0.7 1.4 ........
Cadmium................................... 5.3 0.3 0.5 250 0.3 0.3 411 0.05 0.9 0.0078 1.0
Lead...................................... 3.1 \1\ 8.5 16.9 2500 2.8 1.0 250 0.5 0.05 0.015 5.0
Mercury................................... 0.9 0.002 0.001 0.1 0.002 0.0002 95.2 0.03 0.4 0.0047 0.2
Thallium.................................. 2 2 0.06 1000 2 0.06 1000 2 0.1 0.0013 ........
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Exceeds Toxicity Characteristic level.
What Is EPA's Listing Rationale for This Waste?
We propose to list the baghouse filters waste because our data show
it routinely exhibits one or more of the characteristics of hazardous
waste (i.e., TC lead or arsenic), yet the generators do not identify
their wastes as exhibiting the toxicity characteristic and the
generators that dispose of this waste do not comply with Subtitle C
regulations. We propose to list this waste under the 261.11(a)(1)
criteria:
K176 Baghouse filters from the production of antimony oxide (E).
Because we believe we have sufficient reason to list this waste
under 261.11(a)(1) based on the TC exceedences and lack of compliance
with hazardous waste regulation, we chose to conserve our time and
resources and did not conduct formal risk assessment modeling of the
off-site landfill scenario, as we would traditionally do to support a
261.11(a)(3) listing. Such modeling would reflect reported management
practices. Antimony is not a TC constituent and, therefore, was not
considered in the 261.11(a)(1) listing decision. However, antimony
levels are high and would likely result in risk if modeled. Leach
results for the waste exceed the HBLs by
[[Page 55705]]
a wide margin, e.g., the SPLP results for antimony are up to 48,000
times the HBL. The high levels of antimony in the waste (up to 15%)
would provide a long-term source of the metal for leaching into the
groundwater. Thus, we expect that modeling an off-site Subtitle D
scenario would yield significant drinking water risk.
Note that, when facilities process the antimony oxide product
captured in these filters by reinserting the product-containing filters
back into the furnace where the antimony oxide originated, without
reclamation, these materials would not be solid wastes.\27\
---------------------------------------------------------------------------
\27\ As noted above, these filters capture product materials.
EPA does not regulate reclamation of these products. See 50 FR
14216, April 11, 1985: ``Under the final rules, commercial chemical
products and intermediates, off-specification variants, spill
residues, and container residues listed in 40 CFR 261.33 are not
considered solid wastes when recycled except when they are recycled
in ways that differ from their normal use--namely, when they are
burned for energy recovery or used to produce a fuel''
---------------------------------------------------------------------------
We also propose to add arsenic and lead to Appendix VII to Part
261, which designates the hazardous constituents for which K176 would
be listed.
The ``mixture'' rule for listed wastes currently provides an
exemption for wastes listed solely because they exhibit characteristics
(see 40 CFR 261.3(a)(2)(iii)). Mixtures of such listed wastes lose
their listed waste status when they cease to exhibit characteristics
for which they were listed. (However, they would still need to comply
with Land Disposal Restriction requirements.) In the both of the last
two Hazardous Waste Identification Rule (HWIR) proposals (60 FR 66344,
December 21, 1995) and (64 FR 63382, November 19, 1999), we proposed to
narrow the exemption to only include wastes listed for ignitability,
corrosivity, and reactivity.
This narrowing would make any waste listed for the toxicity
characteristic (TC) (including the waste proposed today for listing
under the (a)(1) criteria) ineligible for the current exemption. In
other words, under current mixture rule regulations, mixtures
containing these baghouse filters would become nonhazardous wastes once
they ceased exhibiting the characteristic. Under the HWIR proposal,
however, such mixtures would remain hazardous wastes even after they
cease to exhibit the TC. As we state in the TC rule, chemicals can
still pose hazardous at levels below the TC (see 55 FR 11799, March 29,
1990). Under an amended consent decree (Environmental Technology
Council v. Browner, C.A. No. 94-2119 (TFH), April 11, 1997), EPA is
required to sign a notice taking final action with respect to the
proposed revisions to the mixture rule by April 30, 2001.
(3) Empty supersacks. One facility ships crude antimony oxide in
supersacks and then reuses them to store intermediate materials until
they wear out. The facility then sends these empty supersacks either to
an off-site industrial Subtitle D landfill or to an off-site plastic
recycler. The facility claims that the supersacks are empty and would
meet the standard in 40 CFR 261.7 (which exempts ``empty'' containers
formerly used to manage hazardous waste). Although 40 CFR 261.7 does
not literally apply to these sacks, we think it is reasonable to take a
similar approach here. We believe that the levels of crude antimony
oxide in worn-out supersacks would be low because the material is the
primary feedstock (raw material) used in this process. We do not
believe it follows that these supersacks should be regulated, when
other similarly empty containers would be exempt. Therefore, we propose
not to list this waste as hazardous.
2. Barium Carbonate
a. Summary. We have evaluated the wastes, waste management
practices, and potential risk exposure pathways associated with the
barium carbonate production processes and propose not to list any
wastes from this industry as hazardous under Subtitle C of RCRA. Some
wastes in this industry are D002 or D005 characteristic hazardous
wastes, which are both currently subject to RCRA Subtitle C regulation
and managed in compliance with those regulations. For other wastes, not
identified as characteristic hazardous wastes, we have identified no
risks of concern associated with the current management of these wastes
that would warrant listing. These wastes do not meet the criteria
listed under 40 CFR 261.11(a)(3) for listing a waste as hazardous.
b. How is barium carbonate produced? There are two facilities in
the United States that produce significant quantities of barium
carbonate. A Georgia facility produces barium carbonate for commercial
sale. A Pennsylvania facility produces barium carbonate only for use as
a feedstock in its own internal manufacturing processes. A third
facility is a specialty manufacturer that produces extremely small
amounts of barium carbonate (approximately 10 kg in 1998).\28\ For more
detailed information concerning this industry, see ``Barium Carbonate
Listing Background Document for the Inorganic Chemical Listing
Determination'' in the docket for today's proposal.
---------------------------------------------------------------------------
\28\ Since, as explained below, we find no significant risks
from the larger volume wastes we assessed, we conclude that any low
volume wastes from this third facility also would not pose any risks
warranting listing.
---------------------------------------------------------------------------
Barium carbonate (BaCO3) has a wide range of uses,
including feedstock for production of other barium chemicals, an
additive in various glasses, ceramics, bricks, and other construction
materials, an additive in oil-drilling suspensions, and a brine
purification chemical in the chlor-alkali industry.
The two primary barium carbonate production facilities use
different manufacturing processes to make barium carbonate. The Georgia
facility uses locally mined barite ore, containing barium in the form
of barium sulfate, as the primary feedstock. The ore is crushed and
milled, thermally reduced in a roasting kiln, and leached with water to
dissolve the barium. The resulting barium sulfide solution is filtered
and reacted with carbon dioxide gas to produce a barium carbonate
precipitate. This precipitate is then dried, and sized for sale.
The Pennsylvania facility uses a commercially purchased high purity
barium chloride solid as the primary feedstock. The facility dissolves
the barium chloride in water, heats and filters the resulting solution,
and precipitates barium carbonate by reacting the barium chloride
solution with ammonium bicarbonate. The resulting barium carbonate
precipitate is washed, filtered, dried and sized before the facility
utilizes it as a feedstock in other manufacturing processes on-site.
c. What wastes are generated? Table III-5 below briefly lists the
facility-reported residuals from the barium carbonate manufacturing
processes, residual volumes generated in 1998, reported RCRA hazard
codes, and residual management practices.
[[Page 55706]]
Table III-5.--Barium Carbonate Production Wastes
----------------------------------------------------------------------------------------------------------------
Reported RCRA hazard Sequential residual
Waste category 1998 volume (MT) codes management practices
----------------------------------------------------------------------------------------------------------------
Barite Ore Feedstock Process--Georgia Facility
----------------------------------------------------------------------------------------------------------------
Treated barium wastes (D005 barium 18,300................ None (D005 prior to Disposal in local, captive,
wastes include barite ore leaching treatment). industrial Subtitle D
waste, barium sulfide filtration landfill (after treatment
sludge, and barium carbonate of D005 wastes in on-site
production area cleaning and Subtitle C treatment
maintenance wastes). unit).
Wastewater from BaCO3 precipitate 313,000............... None.................. Treatment in on-site, tank-
dewatering. based WWTP prior to NPDES
discharge to Etowah River.
WWTP sludge........................ 11,000................ None.................. (1) Dewatered;
(2) Treated on-site;
(3) Disposal in local,
captive, industrial
Subtitle D landfill.
Spent polypropylene and nylon 3 (filter media)...... None.................. (1) Washed and washwaters
filter media and baghouse dust 1.5 re-inserted to barium
collector bags. (baghouse bags). carbonate production
process. Solids managed as
barium carbonate
production area cleaning
and maintenance wastes.
(2) Treated materials
disposed in off-site
municipal Subtitle D
landfill.
----------------------------------------------------------------------------------------------------------------
High Purity Barium Chloride Feedstock Process--Pennsylvania Facility
----------------------------------------------------------------------------------------------------------------
Ammonia vapor scrubber water and Not reported.......... D002.................. Treatment in on-site, tank-
ammonia reclamation unit based WWTP.
wastewaters.
Barium carbonate precipitate 1,600................. None.................. Treatment in on-site, tank-
washwater. based WWTP prior to NPDES
discharge to Susquehanna
River.
WWTP sludge........................ 8,200................. None.................. (1) Stored in roll-off bin;
(2) Disposal in off-site
municipal Subtitle D
landfill.
Ammoniated spent process solution 1..................... None.................. Disposal in off-site
storage tank solids. municipal Subtitle D
landfill.
Sludge and spent filter media from 1.23.................. D005.................. (1) Stored in closed
filtration of barium chloride container;
solution and BaCO3 drying and (2) Sent to off-site
sizing unit dusts. Subtitle C facility for
treatment and disposal.
----------------------------------------------------------------------------------------------------------------
In addition to these wastes, the two barium carbonate manufacturing
facilities also produce other materials which are either piped directly
back to the production process or are used for other purposes. Residues
from the barite ore feedstock production process, ore crusher/grinder,
kiln, barium carbonate drier, granulation and packaging processes are
directly returned to their unit of origin with no significant pathways
for exposure of these materials to the environment prior to reuse.
Barium carbonate production area cleaning and maintenance wastewaters
are also re-inserted to the barium carbonate production process with no
significant pathways for exposure of these materials to the environment
prior to reuse. Because these materials are managed prior to reuse in
ways that present low potential for release, and because we evaluated
all wastes generated after they are reinserted into the process, we do
not believe that these secondary materials present significant threats.
The barite ore feedstock facility also produces molten sulfur or
sodium hyposulfate from hydrogen sulfide gas piped from the barium
carbonate manufacturing process. Because the material is a gas from a
production unit, rather than from a waste management unit, and is
conveyed to its destination through piping, the gas is not a solid
waste. RCRA Section 1004(27) excludes non-contained gases from the
definition of solid waste, and therefore they cannot be considered a
hazardous waste (see 54 FR 50973).
The facility using barium chloride as its feedstock reclaims
ammonia in the form of ammonium hydroxide from barium carbonate
production wastes and uses this material throughout the facility as a
feedstock and reagent. Spent ammoniated process solution is piped from
the process unit where it forms to a storage tank where it is
commingled with ammoniated spent process solutions from several other
on-site manufacturing processes. The ammoniated spent process solutions
from these other manufacturing processes are beyond the scope of this
listing determination. From the storage tank, the facility pipes the
commingled ammoniated spent process solutions to an ammonia reclamation
unit which reclaims the ammonia in the form of ammonium hydroxide.
Ammonium hydroxide is used on-site in various manufacturing processes,
including the production of ammonium bicarbonate solution for use in
the barium carbonate production process. Because the spent solution is
piped to the reclamation unit with no significant potential for
exposure to the environment, we did not evaluate the solution further.
Both facilities produce barium carbonate from a saleable mineral
product.\29\ Under the Bevill exemption (54 FR 36620-21), chemical
manufacturing begins if there is any further processing of a saleable
mineral product. Since these facilities use saleable mineral products
as feedstock, their processes are chemical manufacturing, and are not
classified as mineral processing. Therefore none of the wastestreams
generated by these facilities during the production of barium carbonate
are Bevill exempt.
---------------------------------------------------------------------------
\29\ Note that primary barite ore has wide use in drilling muds
for the petroleum industry and numerous other industrial uses,
including use as feedstock for barium chemicals; see ``Barite'' U.S.
Geological Survey--Minerals Information, 1997, http://minerals.usgs.gov/minerals/pubs/commodity/barite/index.htm.
---------------------------------------------------------------------------
See the ``Barium Carbonate Listing Background Document for the
Inorganic Chemical Listing Determination'' for more details on these
residuals.
[[Page 55707]]
d. Waste characterization and Agency evaluation. Barium is the
primary constituent of potential concern in the wastes from both
facilities. Barium occurs in several production wastes at high levels,
in some cases exceeding the TC level (100 mg/L) in TCLP leachate
samples. These TC wastes are coded and treated as hazardous (D005). The
Georgia facility holds a hazardous waste treatment permit to allow on-
site stabilization of barium, and the Pennsylvania facility sends all
of their D005 wastes off-site for treatment and disposal at a hazardous
waste treatment and disposal facility.
We decided not to do characterization sampling for wastes from
either facility because both facilities submitted information to us on
the nature of their wastes. We also received some additional analytical
data from the State of Georgia for the Georgia facility. These data
provided information on the concentrations (or absence) of the metal
constituents of potential concern in the wastes and in test leachates
from the wastes. We believe the available information is sufficient to
adequately characterize the wastes and to allow us to evaluate their
risk potential for the purposes of a listing decision. ``Barium
Carbonate Listing Background Document for the Inorganic Chemical
Listing Determination'' summarizes the analytical data and other
information available for these wastes.
We propose not to list any of the wastes from the barium carbonate
manufacturing industry. Many wastes from this industry are
characteristically hazardous and managed as hazardous wastes either on-
site or at permitted Subtitle C treatment facilities off-site. Other
wastes did not exhibit constituents at levels of concern for purposes
of a listing given the nature of their management and disposal.
Several groups of wastes from each of the facilities are disposed
of in a treated form, rather than an as-generated form. In general,
therefore, we focused our evaluation on the treated form of the wastes.
The paragraphs below describe how the wastes are generated and
managed for the two processes and our rationale for proposing not to
list the wastes. We solicit comments on the proposed listing decisions
described below.
(1) Wastes from the production of barium carbonate from barite ore
feedstock. (a) Treated barium wastes. The waste category, ``treated
barium wastes,'' is the treatment residue from the commingling and
treatment of several barium wastes in an on-site hazardous waste
treatment unit. The barium wastes, which are consistently
characteristically hazardous for barium (D005) before treatment (or are
consistently assumed by the facility to be D005 wastes), include:
--Barite ore leaching waste, which is solids from the filtration of the
liquid product stream from the barite ore roasting and leaching units,
--Barium sulfide sludge, which is from polishing filtration of liquid
barium sulfide, and,
--Wastes from cleaning and maintenance of the barium carbonate
production area.
A RCRA Subtitle C hazardous waste treatment facility permit governs
the on-site treatment process for these barium wastes. The three wastes
are sent directly to the treatment unit, or they are stored prior to
treatment for short time periods in Subtitle C closed containers. The
treatment process is a stabilization process for barium using gypsum
(primarily calcium sulfate) to precipitate soluble barium as less
soluble barium sulfate. According to RCRA Subtitle C regulations, the
treated barium waste must meet the LDR UTS. Treatment takes place in
concrete mixer-type trucks. Once treatment is complete, the treatment
trucks immediately transport the waste to the facility's captive
Subtitle D landfill for disposal, located approximately 2 miles from
the production facility on facility-owned property.
State and facility information indicate that the treated barium
wastes no longer exceed the TC level for barium (100 mg/L from TCLP
analysis) and typically leach less than 1 mg/L barium, according to
both SPLP and TCLP analyses. In addition, according to data the
facility and the state of Georgia submitted to EPA from sampling events
conducted during the past two years at the facility, the waste meets
the LDR UTS for all regulated constituents.
The treated barium wastes are disposed of in the landfill without
daily cover. However, the waste has a relatively high moisture content
(approximately 50%) when placed in the landfill and, according to the
facility, hardens over time and does not create dust. In addition, the
waste does not contain any known volatile constituents of concern.
To assess the potential for groundwater releases from the captive,
industrial landfill, we compared the SPLP leaching data from the
facility and the state of Georgia to existing HBLs for ingestion of
groundwater. SPLP data are appropriate for evaluating this waste
because it is placed in a Subtitle D industrial landfill. We did not
find any constituents in the available SPLP data that exceeded the
health-based levels by more than a factor of 2 (see section III.E.3 for
a discussion of this risk-screening criterion). See the ``Barium
Carbonate Listing Background Document for the Inorganic Chemical
Listing Determination'' for further details on the available data.
In addition, we found only one exceedence of AWQC standards among
the SPLP leaching data for treated barium wastes. Selenium was found at
a level of 0.04-0.06 mg/L, which exceeds the AWQC standard (0.0050 mg/
L) by a factor of 8 to 12. However, the landfill in which the treated
barium wastes are placed is 1,700 feet from the nearest downgradient
water body, the Etowah River, and also lies beyond the river's 100 year
flood plain. In recent years, the Etowah River in the vicinity of the
landfill has had a flow rate varying between 9.9 to 230 m 3
per second on a daily basis. Given the distance over which leachate
from the treated barium wastes would need to travel before reaching the
river, dilution and attenuation during transport in local groundwater,
and further dilution in the Etowah River, we believe the levels of
selenium in the leachate would decrease to a level which would no
longer pose a risk to the environment.
We do not believe it is necessary to assess other management
practices for the treated barium wastes. The facility has treated and
disposed of their treatment residues in a similar manner for over 15
years. The production facility itself relies on a local source of
barite ore, has operated from its current location since 1942 and is
therefore not likely to change its location in the near future. The
dedicated landfill has a remaining life of nearly 20 years and is
located approximately 2 miles from the production facility. Given the
dedicated nature of the landfill, its proximity to the production
facility, and the significant remaining capacity, we believe it is
unlikely that the Georgia facility will dispose of their wastes in any
other unit in the near future. Thus there is no need to assess
additional management scenarios for this wastestream.
Given the facility's Subtitle C waste treatment permit, we believe
that the facility's untreated D005 wastes are adequately managed with
respect to this rulemaking. In addition, we have found no potential for
releases to air, groundwater, or surface water at levels of concern
from the treated wastes. Therefore we propose not to list these wastes.
(b) Wastewater from barium carbonate precipitate dewatering. The
facility filters barium carbonate precipitate from
[[Page 55708]]
residual process solutions and sends this filtrate to the facility's
tank-based wastewater treatment plant (WWTP) for treatment. According
to the facility's RCRA Section 3007 Survey response, the wastewater
does not exceed the TC level for any constituent.
Wastewater from the barium carbonate production process commingle
in the WWTP with wastewaters from other facility processes beyond the
scope of this rulemaking and comprise approximately 17% of the total
WWTP flow-through. The wastewater treatment is an oxidation process.
Treatment of the wastewaters occurs in tanks equipped with secondary
containment. Given the controlled manner in which the wastewater is
managed in tanks, the lack of any volatile constituents of concern, and
NPDES regulation of the WWTP effluent, we propose not to list this
wastewater.
(c) Treated wastewater treatment plant sludge. The facility's WWTP
generates a treatment sludge from the commingling and treatment of
wastewaters discussed above in the preceding section. The resulting
sludge is dewatered to 25% solids content in an uncovered tank. None of
the information the facility provided on this waste indicates the
presence of volatile constituents of concern.
The facility places the dewatered WWTP sludge directly from the
WWTP unit into a treatment unit consisting of a concrete mixer-type
truck containing gypsum (primarily calcium sulfate). The truck mixes
the wastewater treatment sludge with the gypsum to convert soluble
barium to a less soluble barium sulfate prior to transporting the waste
to the facility's off-site, captive, Subtitle D landfill. We found low
potential for releases from either the dewatering tank or the treatment
unit. Analytical data from the state shows that the treatment process
reduced leachable barium in the sludge, according to SPLP analysis,
from 53 mg/L to 0.03 mg/L.
SPLP analytical data from the State also show no potential
constituents of concern in treated WWTP sludge samples at
concentrations above HBLs or above AWQCs. Therefore, this waste
screened out from any further risk evaluation for groundwater or
surface water. The SPLP data are appropriate for evaluating this waste
because it is placed in a Subtitle D industrial landfill.
Similar to the treated barium wastes described above in section
(a), the waste has a high moisture content when placed in the landfill
and is reported by the facility to harden over time. Therefore, we do
not believe this waste poses a significant risk through releases of
airborne dust. In addition, the waste does not contain any known
volatile constituents of concern.
We do not believe it is necessary to assess other management
practices for this waste. The facility has treated and disposed of
their wastewater treatment plant sludge in a similar manner for over 15
years. Given the dedicated nature of the landfill, its proximity to the
production facility, and the significant remaining capacity, we believe
it is unlikely that the facility will dispose of their wastes in any
other facility in the foreseeable future.
Based on our knowledge of the current nature of the management of
the treated wastewater treatment plant sludge and of the low level of
constituents of concern it contains, including volatile constituents,
we propose not to list the treated wastewater treatment plant sludge.
(d) Spent polypropylene and nylon filter media and baghouse dust
collector bags. Baghouse dust collector bags and polypropylene and
nylon filter media fabric at the Georgia facility deteriorate over time
and must be replaced periodically. The facility washes the bags and
filters with water and then soaks them in sulfate solution to stabilize
any remaining barium. The facility then disposes of the bags and filter
fabric in a local municipal Subtitle D landfill. Wastewaters from the
washing of the filters and bags are returned to the production process.
Solids from the washing of the filters and bags become part of the
cleaning and maintenance wastes that are treated as discussed above in
section (a).
The facility did not provide chemical composition analyses for
these wastes. However, we do not expect either baghouse bags or nylon
and polypropylene filter fabrics, which are used primarily for physical
separation of solids from liquids in the barium carbonate production
process, to contain notable levels of any potential constituent of
concern besides barium. According to the facility, neither the bags nor
the filters exceed the TC level for any constituent. In addition, the
facility treats the materials to stabilize any remaining barium before
disposing of them in a Subtitle D municipal solid waste landfill. The
facility does not produce a large volume of these wastes; approximately
3 metric tons per year of filters and approximately 1.5 metric tons per
year of baghouse bags. Because barium is not volatile, and because we
do not expect the filter media and bags to contain any other volatile
constituents, we do not believe these residuals pose any risk through
airborne pathways.
Given the relatively small volume of these wastes, the inert nature
of the filters and bags themselves, and the facility's washing and
stabilization of barium prior to disposal, we believe these treated bag
wastes do not warrant listing as hazardous wastes.
(2) Wastes from the production of barium carbonate from high purity
barium chloride feedstock. (a) Barium carbonate production wastewaters
and wastewater treatment plant sludge. The Pennsylvania facility
commingles and treats wastewaters from several manufacturing processes
at their facility in an on-site, tank-based WWTP. Wastewaters from the
barium carbonate production process are piped directly to the WWTP and
comprise less than 1% of total WWTP flow through; the remainder of the
wastewaters entering the WWTP are from manufacturing processes not
within the scope of this listing determination. Wastewaters from the
barium carbonate production process include:
--Ammonia vapor scrubber waters and ammonia reclamation unit
wastewater.
--Barium carbonate precipitate washwater.
A scrubber captures ammonia vapor from the mixing of ammonium
bicarbonate solution with the barium chloride solution to precipitate
barium carbonate. Water, sodium hydroxide, and emissions from other
manufacturing processes in the facility mix with the ammonia vapor in
the scrubber to produce this wastestream.
An ammonia reclamation unit recovers ammonia from ammoniated spent
process solutions from multiple manufacturing processes, including the
barium carbonate manufacturing process, in the form of 28% ammonium
hydroxide solution. The unit also produces a wastewater. Approximately
1% of the total ammonia reclamation unit inflow derives from the barium
carbonate production process. Therefore, a small percentage of the
unit's wastewater derives from barium carbonate production.
The facility also produces a wastewater from the washing of barium
carbonate precipitate with deionized water in order to remove any
process solution remaining on the precipitate.
The only possible release route of concern from the tank-based
system for the wastewaters would be through air releases. This pathway
is highly unlikely for the nonvolatile metals that are the potential
constituents of concern in these wastes. Given the controlled manner in
which the wastewaters are managed and the regulation of the
[[Page 55709]]
treatment unit's discharge under the NPDES program, we propose not to
list these wastewaters.
Treatment of the commingled wastewaters consists of neutralization
followed by filtration. The treatment generates a sludge. According to
the facility's RCRA Section 3007 Survey response, the sludge does not
exceed the TC level for any constituent. The facility disposes of the
sludge in a local Subtitle D municipal solid waste landfill. We do note
the presence of some potential constituents of concern in the WWTP
sludge. These constituents include vanadium, nickel, and antimony.
However, we do not believe that these constituents derive from the
barium carbonate manufacturing process.
Because the barium carbonate production process wastewaters
contribute less than 1% of the total input to the on-site WWTP, any
constituents in the barium carbonate production wastewaters sent to the
WWTP also make a minimal contribution to the total level of
constituents in the combined wastewater in the WWTP and the resulting
sludge. In addition, the process uses high purity barium chloride
dissolved in deionized water as its primary feedstock and reclaims much
of the residual ammonia from its ammonium bicarbonate feedstock.
Therefore, the likelihood that the constituents of concern in the
sludge might arise from the barium carbonate production process is very
low. Moreover, the facility has provided information to us indicating
that the barium carbonate process is not the source of these potential
constituents of concern and that they derive instead from on-site
manufacturing processes beyond the scope of today's listing proposal
(see ``Barium Carbonate Listing Background Document for the Inorganic
Chemical Listing Determination'' for further details). Given the
minimal potential for contribution of constituents of concern by the
barium carbonate process wastewaters to the WWTP sludge, we propose not
to list this sludge under this rulemaking effort.
(b) Ammoniated spent process solution storage tank solids. The
facility pipes residual process solution containing ammonia directly
from the barium carbonate precipitate settling unit to covered storage
tanks prior to routing it through an on-site ammonia reclamation unit.
The barium carbonate process wastewater is one of many ammoniated
residual process solutions the facility routes to the storage tanks and
constitutes approximately 1% of the unit's total input.
The ammoniated spent process solution storage tank accumulates
solids which the facility removes and disposes of in a local Subtitle D
municipal solid waste landfill on a yearly basis. The tank solids are a
small volume waste of 1 MT/yr. According to analytical data provided by
the facility, the solids do not exceed the TC level for any
constituent, though they do contain vanadium, nickel, and antimony at
levels of potential concern. However, as noted for the wastewater
treatment plant sludge, the constituents of concern in the solids are
unlikely to arise from the barium carbonate production process because
the barium carbonate production process contributes only 1% of the
total wastewaters in the storage tanks. In addition, information the
facility provided indicates that the nickel, vanadium and antimony
found in the sludge derive from other manufacturing processes that are
beyond the scope of this listing determination. Thus, given the solids'
small volume and the low likelihood that the barium carbonate process
wastewater contributes any constituents of concern, we propose not to
list the ammoniated spent process solution tank solids in this listing
determination.
(c) Sludge and spent filter media from filtration of barium
chloride solution and barium carbonate drying and sizing unit air
pollution control residues. Both the air pollution control dusts from
the barium carbonate drying and sizing unit and sludge and the spent
filter materials from barium chloride solution filtration exceed the TC
regulatory level for barium (100 mg/L). The facility codes the waste as
characteristic hazardous waste (D005). The facility stores these small
volume wastes in closed containers on-site before sending them to a
RCRA Subtitle C hazardous waste treatment and disposal facility for
treatment and disposal. We believe that the containers present no
significant potential for release to the environment. We believe that
regulations applying to characteristic wastes adequately protect
against mismanagement. Furthermore, these wastes comprise a very small
volume (1.23 metric tons per year). Thus, we propose not to list these
wastes.
3. Boric Acid
a. Summary. We have evaluated the wastes from the production of
boric acid and propose not to list any wastes from this process as
hazardous under RCRA. These wastes do not meet the criteria set out at
40 CFR 261.11(a)(3) for listing wastes as hazardous. They do not pose a
substantial present or potential threat to human health or the
environment. We have identified no risks of concern associated with the
current management of the wastes.
b. Description of the boric acid industry. Boric acid was produced
by two facilities in the United States in 1998. These two facilities
are both located in the Mojave Desert in California, one of the few
areas where borate minerals can be mined in the United States.
The two facilities mine borates from different sources to produce
boric acid. The first recovers borate from brines pumped from beneath
Searles Dry Lake, California. The second facility mines sodium borate
ores near Boron, California.
The first facility extracts highly mineralized brine and uses a
liquid-liquid extraction process to remove the borates from the brine.
During the first production step, called the ``loading section,'' the
facility mixes the brine with a chelating agent in a kerosene solution
that causes most of the boron and some of the sodium and potassium
compounds in the brine to bind to the extractant. The loaded extractant
is sent through strippers where it is mixed with dilute sulfuric acid
to strip the boron, sodium and potassium from the extractant to form
boric acid, sodium sulfate and potassium sulfate. The solution is then
sent to a solution settler from which the liquor goes to boric acid
recovery using crystallization and evaporation techniques.
The second facility mines sodium borate kernite ore to produce
boric acid through a process of dissolution, classification,
thickening, filtration and crystallization.
Because the facilities use such different sources and production
processes, their resulting wastes are very different and are discussed
separately. For more detailed information concerning this industry, see
the ``Boric Acid Background Document for the Inorganic Chemical Listing
Determination'' in the docket for today's proposal.
c. Agency evaluation of wastes generated by the brine recovery
process.
Are There Any Wastes in This Process That Fall Under the Bevill
Exemption?
The depleted brine from the loading section of the brine recovery
process is exempt as a mineral processing beneficiation waste under 40
CFR 261.4(b)(7)(i).\30\ This waste from the
[[Page 55710]]
extraction/beneficiation of ores and minerals is thus outside the scope
of the consent decree. The facility reported generating 4,600,000 MT in
1998. This Bevill exempt waste is commingled with wastes which do not
qualify for the Bevill exclusion later in the process. The portion of
the waste which does not qualify for the Bevill exclusion is within the
scope of the consent decree and is discussed below.
---------------------------------------------------------------------------
\30\ The Agency has previously evaluated the Bevill status of
wastestreams at the Searles Lake facility; see memos dated February
14, 1992 and June 30, 1993 in Appendix E of the ``Boric Acid
Background Document for the Inorganic Chemical Listing
Determination'' in the docket.
---------------------------------------------------------------------------
As discussed in the Agency's prior Bevill evaluations for this
facility, mineral processing begins at the liquid-liquid extraction
step where sulfuric acid is added to the loaded extractant to produce
sodium sulfate and boric acid. Wastes generated before this step,
including spent brine, are beneficiation wastes and retain their Bevill
exemption. All wastes generated after the beginning of mineral
processing are non-exempt solid wastes. Therefore, all of the wastes at
this facility which are generated from the liquid extraction step to
the end of the process are all non'exempt solid wastes. See the ``Boric
Acid Background Document for the Inorganic Chemical Listing
Determination'' in the docket for more information on the Bevill
exemption for wastes at this facility.
What Kinds of Wastes Are Generated by the Brine Recovery Process?
The Bevill exempt depleted brine from the loading section is sent
through an API settler and Wemco floatation cells designed to separate
organic compounds from the brine. The organic emulsions generated in
these units and in the process settlers are sent to an on-site ``crud''
treatment facility which breaks down the emulsion into aqueous and
organic components. This treatment process generates a non-exempt
hydrocarbon waste (fuel oil) that is sent off-site to a used oil
refinery. The Bevill exempt brine is sent to the ``Trona skimmer''
where it is combined with other non-exempt wastewaters generated during
the process. The Trona skimmer acts as a settling pond promoting phase
separation of remaining organic materials in the brine. The Bevill
exempt brine is then returned to the dry lake for recharging as
required by the facility's Bureau of Land Management permit. Because
the non-exempt wastewaters are commingled with the Bevill exempt brine
in the Trona skimmer, the non-exempt wastewaters are also returned to
the dry lake as a small percentage of the overall volume. The non-
exempt organic waste removed at the Trona skimmer is stored on-site in
a tank until it is shipped off-site to a commercial blender and
subsequently burned for energy recovery.
Additional wastes generated by the brine recovery process that are
not Bevill exempt include:
--Petroleum contaminated sludges from containment areas around the API
settler, Wemco floatation cells, loading section and liquid-liquid
extraction (LLX) strippers
--Spent activated carbon collected from the carbon filter system used
to purify the borate liquor before it goes into the crystallization
units
In addition to the above wastes, the facility also produces other
materials during the production of boric acid that are either piped
directly back to the production process or used for other purposes.
These materials include aqueous residuals and kerosene recovered from
the crud treatment process, off-specification product, scrubber water
and condensate that are returned to on-site production units for use.
Because these materials are reused on-site in production units and
there is no significant potential for exposure of these materials to
the environment prior to reuse, we found that they present no
significant threat. Also, off-specification product, when reinserted
without reclamation into the process where it originated, is not a
solid waste.
How Are the Wastes From the Brine Recovery Process Currently Managed?
Table III-6 summarizes our information about the wastes from this
process:
Table III.-6.--Boric Acid: Brine Recovery Process Wastes
------------------------------------------------------------------------
Sequential
Waste category 1998 volume (MT) management practices
------------------------------------------------------------------------
Fuel oil from crud treatment 690................. (1) Stored in
facility. covered tank;
(2) Sent off-site to
a Subtitle C
permitted used oil
refinery.
Miscellaneous wastewaters... 194,040 (The Bevill (1) Combined
exempt partially wastewaters;
depleted brine discharged to Trona
volume is 4.6 skimmer with the
million MT). Bevill exempt
partially depleted
brine;
(2) Removal of
organics in skimmer
unit;
(3) Commingled
partially depleted
brine and process
wastewaters are
returned to Searles
Dry Lake for
recharging.
Organics from Trona skimmer. 10.................. (1) Stored in
covered tank;
(2) Sent to off-site
Subtitle C blender;
(3) Burned for
energy recovery.
Sludges from containment 20.................. (1) Drum storage;
areas. (2) 20 cubic yard
roll-off bins;
(3) Transported with
manifest off-site
to Subtitle C
landfill as
California-only
hazardous waste.
Spent activated carbon...... 43.................. (1) Washed;
(2) Reclaimed in an
on-site furnace;
(3) Reused in the
process.
------------------------------------------------------------------------
[[Page 55711]]
What Is EPA's Decision About Whether to List These Wastes as Hazardous?
We propose not to list any wastes from the brine recovery process
for the production of boric acid. Our rationale for each waste is
presented below.
(1) Fuel oil from the crud treatment facility. We propose not to
list the fuel oil generated at the crud treatment facility. The
facility characterized the fuel oil as 100 percent hydrocarbons. The
fuel oil is stored on-site in a covered tank prior to being shipped
off-site to a Subtitle C permitted used oil refinery. For those
scenarios where wastes are managed in a tank, the impervious nature of
the construction materials (concrete, fiberglass, or steel) of tanks is
unlikely to result in releases to groundwater in all but the most
catastrophic scenarios. We also are not concerned with potential air
releases because the tank is covered. The subsequent treatment at the
permitted used oil refinery is already regulated under Subtitle C and
the used oil regulations. Therefore, we propose not to list this waste.
(2) Miscellaneous wastewaters. We propose not to list the
miscellaneous wastewaters. We evaluated the potential for an exposure
pathway via groundwater ingestion and determined that no such pathway
exists. The facility producing boric acid by recovering borates mined
from Searles Dry Lake is located in California's Mojave Desert. The
process and associated wastewaters are tied to the Mojave Desert
location because it is the source of the borate rich brine. The
environment is arid with only 4 inches of precipitation annually. The
groundwater under the facility has total dissolved solids (TDS) levels
as high as 450,000 ppm. All wastewaters, including the Bevill exempt
depleted brine, are co-managed and ultimately returned to the dry lake
resource. Due to the extremely high TDS levels in the area, the water
is non-potable. The surrounding communities have drinking water piped
in from 25 miles away. Therefore, no groundwater exposure pathway
exists.
Furthermore, the total volume of the miscellaneous wastewaters is 4
percent of the volume of the depleted brine; any contaminants in these
wastewaters would therefore be diluted by a factor of 25 prior to
return to the dry lakebed. Most of the miscellaneous wastewaters are
generated in the later part of the process and thus we do not expect
they will contain constituents of concern at significant levels. There
is one wastewater that contains organic constituents not found in the
influent brine (formaldehyde and fuel hydrocarbons). This wastewater is
generated at the carbon column. However, it only represents 0.03
percent of the total volume that is returned to the dry lake. Also, the
reported level of formaldehyde in the waste would be well below the HBL
for this chemical (3 mg/L) \31\ after mixing with other wastewaters. We
are not concerned with potential air releases because the Trona
skimmer, where the wastes are mixed, is covered. The facility also
mixes a characteristic (D002) HCl acid waste stream with the Bevill
exempt depleted brine prior to reaching the Trona skimmer. The
resultant mixture is not characteristic and the mixing takes place
within a pipeline where there is no opportunity for exposure to the
characteristic waste before or during the mixing. Given the factors
listed above, particularly the lack of an exposure pathway, we propose
not to list the miscellaneous wastewaters.
---------------------------------------------------------------------------
\31\ Based on the RfD in IRIS (2E-1 mg/kg-day) and a 90th
percentile drinking water intake rate in children (64 mL/Kg/day).
---------------------------------------------------------------------------
(3) Organics from the Trona skimmer. We propose not to list the
organics (chlorinated hydrocarbons) recovered from the Trona skimmer.
The organics are stored in a covered tank before being shipped off-
site. For those scenarios where wastes are managed in a tank, the
impervious nature of the construction materials (concrete, fiberglass,
or steel) of tanks is unlikely to result in releases to groundwater in
all but the most catastrophic scenarios. We also are not concerned with
potential air releases because both the Trona skimmer and tank are
covered. The waste is shipped off-site to a Subtitle C permitted
blender prior to being burned for energy recovery in cement kilns.
Burning by cement kilns is regulated under MACT standards for cement
kilns (64 FR 31989, June 14, 1999 and 64 FR 52827, September 30, 1999).
Therefore, we did not further evaluate potential risks from burning the
organics under this listing. The facility reported a California-only
hazardous waste code CA343 (organic liquids, unspecified) for the waste
but did not report any federal characteristic codes. The facility
manifests the waste using the California code when they send it to the
blender. Because this waste has significant BTU value and also carries
a state hazardous waste code, we expect this management practice to
continue; we do not believe there would be any significant benefit to
the environment by listing this waste.
(4) Sludges from containment areas. We propose not to list the
sludges collected from containment areas around the process tanks, the
loading section, LLX strippers, Wemco flotation cells and API settlers.
The facility reported a California-only hazardous waste code CA611
(petroleum contaminated soils) for the waste but did not report any
federal characteristic codes. The facility stores the waste on-site in
drums, transfers to it to 20 cubic yard roll-off bins and mixes the
sludge with soil, and then ships the waste off-site with a manifest as
a California-only hazardous waste to a Subtitle C landfill. The
facility is tied to its location in California so we believe it is
plausible that the waste will always be treated as a California-only
hazardous waste. We do not believe there would be any significant
benefit to the environment by listing this waste.
(5) Spent activated carbon. We propose not to list the carbon that
is regenerated on-site. The carbon is regenerated in an on-site
furnace. The carbon filtration process occurs later in the process
after much of the organic additives have settled out of the borate
liquor. Consequently, we expect that the filters will not collect high
concentrations of constituents of concern, except perhaps kerosene
related organics. We expect any such constituents that are filtered out
using carbon adsorption to be combustible. There is no potential for
exposure prior to the regeneration process or during the return of the
activated carbon to the carbon filter. The furnace is permitted by the
State of California Air Control Board. Although the permit does not
contain any requirements for emission controls, it does require annual
reporting. We reviewed the emissions data and do not believe that the
emissions from the furnace are of concern. The reported emission levels
are significantly below the MACT standards for permitted hazardous
waste incinerators (64 FR 52827, September 30, 1999). We expect the use
of this furnace to continue because it is expedient to regenerate the
carbon on-site, and the facility is unlikely to relocate given the
proximity of the mineralized brine source. Therefore, we propose not to
list this waste.
d. Agency evaluation of wastes generated by the kernite ore
process.
What Kinds of Wastes Are Generated by the Kernite ore Process?
The facility generates two primary wastestreams: Tailings and
gangue. The tailings include the wastewaters and fine insolubles from
ore processing and boric acid production. The tailings are managed in
tanks and then pumped to on-site evaporation ponds/surface
impoundments. The boric acid gangue which includes clay, sand and other
[[Page 55712]]
course insolubles, is produced during the separation of solids from the
borate liquor, a step the facility calls ``classification.'' The gangue
is placed on a slab for drainage and then managed in on-site waste
piles with gangue produced from the other production process at the
facility. The drainage from the slab is sent to the tailings ponds. The
remaining wastestream is comprised of the filters from the filtration
of the borate liquor to remove any remaining insoluble ore material
prior to crystallization. The filter aid is washed off weekly and
managed with the tailings. The spent filters are transferred to a solid
waste bin in preparation for on-site disposal in a industrial Subtitle
D landfill.
In addition to the above wastes, the facility also produces off-
specification product that is put directly back to the production
process. Because the material is reused on-site in production units in
ways that present low potential for release, and because we evaluated
process waste generated after the secondary material is reinserted into
the process, we do not believe that the off-specification product
presents significant risks. Note that, when facilities process off-
specification product by reinserting the off-specification product back
into the process where it originated, without reclamation, the off-
specification product would not be a solid waste.
The facility made beneficiation exemption claims under the Bevill
amendments for the tailings and gangue wastes. Because we propose not
to list these wastes, we did not review the facility's Bevill exemption
claims.
How Are the Wastes From the Kernite Ore Process Currently Managed?
Table III-7 summarizes our information about these wastes:
Table III-7.--Boric Acid: Kernite Ore Process Wastes
------------------------------------------------------------------------
Sequential
Waste category 1998 volume management practices
------------------------------------------------------------------------
Tailings................... Up to 750,000 (1) Stored in tank;
gallons/day1. (2) Pumped to
evaporation ponds/
surface
impoundments.
Gangue..................... Portion of 900,000 (1) Placed on slab
MT2. for drainage;
(2) Trucked to on-
site waste piles.
Spent filters............... 3................... (1) Stored in solid
waste bin;
(2) On-site
industrial Subtitle
D landfill.
------------------------------------------------------------------------
1 Capacity volume for boric acid surface impoundments. Current daily
quantity is lower. Source: California Regional Water Quality Control
Board permit, board order 6-93-17.
2 The boric acid coarse gangue is co-mingled with gangue from the other
production process at the facility. That process is outside the scope
of the consent decree. The boric acid gangue represents only a minor
proportion of the total 900,000 tons of gangue typically deposited
annually on the waste piles. Source: California Regional Water Quality
Control Board permit, board order 6-93-17.
What Is EPA's Decision About Whether To List These Wastes as Hazardous?
For the reasons set out below, we propose not to list any wastes
from the kernite ore process for the production of boric acid.
(1) Tailings. We propose not to list the tailings from boric acid
production. The tailings are managed in a tank and then pumped to
evaporation ponds. The facility provided TCLP data for the tailings.
Those data show waste contains arsenic and antimony above health-based
drinking water levels. The Agency also assumed that boron was present
in significant levels due to the nature of the ore. The facility
provided total levels for the boron concentration in the waste. We
conducted an in-depth review of the groundwater conditions at the site
and have concluded that a groundwater exposure pathway does not exist.
No one is currently living near the facility boundary closest to the
waste management unit areas and it is unlikely that future development
will occur. The closest existing drinking water well is two miles away
from the waste management units. It is a community well and is subject
to all applicable drinking water standards. In addition, there are
several factors described below which make contamination of this well
from a potential release from the facility's evaporation ponds
unlikely.
The groundwater under the off-site area of land closest to the
waste management units is not suitable for use as drinking water. The
ore body, which is the raw material for the process, has a localized
impact on the groundwater in its vicinity. Monitoring wells in the area
show that the groundwater in the geologic strata underneath the off-
site area adjacent to the waste management units has total dissolved
solids (TDS) levels in excess of three times the maximum level for an
aquifer to be considered a drinking water source in California.\32\
Additional factors such as low flow rate and high treatment cost make
the potential for a private well in that area highly unlikely.
Municipalities can tap into an alternative water source through a
regional pipeline and need not rely on groundwater.
---------------------------------------------------------------------------
\32\ California Water Quality Control Plan for the Lathontan
Regions, revised 1991 (p. 4.6-1)
---------------------------------------------------------------------------
The geology of the area has several characteristics that reduce the
potential for releases from the impoundments from reaching known
drinking water sources. The transport time to groundwater for the
constituents of concern appears to be significant given the depth to
groundwater under the waste management units (170-220 feet) and the
affinity of these constituents to bind with soil.\33\ The area under
the facility has several geologic faults that act as groundwater
barriers. The South Borax fault is likely to prevent any potential
release from the waste management units from reaching the drinking
water source for the existing community well. The fault is located just
south of the waste management units, between the units and the well. In
addition, the groundwater underlying the waste management units is
contained in the tertiary soil layer whereas the community well draws
from the quaternary layer. We believe that migration between these two
layers would be limited. (The facility submitted a detailed summary of
the geologic conditions at the site. This information has been placed
in the docket for this rulemaking. See ``Summary of Boron Operations
Hydrogeology, Potential Groundwater Receptors and BAP Waste Management
Parameters''). Finally, we note that the impoundments in question are
designed with a triple liner and leachate collection system, making any
significant release less likely over the active life of the units.
Based on these factors, we do not believe there is a
[[Page 55713]]
groundwater exposure pathway from the tailings.
---------------------------------------------------------------------------
\33\ Source: California Regional Water Quality Control Board
permit, board order 6-93-17.
---------------------------------------------------------------------------
We also assessed the potential for air releases from the tailings
ponds. Because the constituents of concern from this process are
nonvolatile metals, we are not concerned with releases through
volatilization. Although the surface impoundments are evaporation
ponds, the facility claims that there is still some level of moisture
in the ponds at all times, thereby minimizing release of particulates
to the air. The particulates would not likely be subject to wind blown
erosion due to the moisture level of the waste. Furthermore, the
closest off-site receptors are at least two miles away from the unit.
Due to dispersion, it is unlikely that any particulate releases would
reach such receptors at significant levels. The facility also provided
a risk assessment which assessed the air risks from the tailings ponds.
Their assessment did not show any air risks from the tailings ponds
even when they assumed a conservative dry down process for the unit.
(The facility's air risk assessment is available in the RCRA docket for
today's proposal).
In summary, there are several site specific factors that need to be
taken into account when evaluating risks from this waste. This is the
only facility in the country producing boric acid from ore. The
facility is tied to its location because it is the source of the ore.
The hydrogeology of the site is such that local groundwater is not
suitable for drinking water use, and any potential releases from the
unit would be unlikely to migrate to any drinking water source.
Furthermore, the facility is remote with the nearest receptors two
miles away. Based on all of these facts, we propose not to list the
tailings from the kernite ore process for the production of boric acid.
(2) Gangue. We propose not to list the gangue generated during the
boric acid process. Initially, the gangue is placed on a slab to drain.
The drainage from the gangue is collected and managed with the tailings
(we assessed the drainage as part of the tailings wastestream; see
section (1) above for our listing recommendation). The drained gangue
is trucked to on-site waste piles. The gangue is wet when transported
to the waste pile but most of the moisture evaporates quickly in the
dry desert environment. The same geological conditions apply to the
gangue waste unit as described above for the tailings waste unit. The
gangue is ultimately managed as a dry waste pile and there is virtually
no precipitation to cause leaching. We assumed a greater risk to
groundwater would come from the tailings because there is any liquid
associated with the gangue would evaporate before leaching into the
subsurface. Based on our decision regarding the tailings, we did not
further evaluate the risks to groundwater from the gangue.
We did assess in more detail the potential for air releases from
the waste pile. We do not expect releases of the nonvolatile metals
from this waste. The moist gangue solids are trucked to on-site waste
piles. The gangue contains enough sodium sulfate to cause the gangue
piles to set up like cement when it dries, helping prevent erosion and
air release of particulates from the pile. As a further check of
potential air releases, we examined the potential for release of the
constituent of most concern, arsenic. According to data provided by the
facility, the total levels of arsenic in the gangue vary between 25 and
78 mg/kg. We compared these total concentrations to one of the levels
calculated as part of the EPA's Air Characteristic Study (530-R-99-
019b, Aug 1999, Table 4-3). The Study evaluated different waste
management and receptor scenarios to determine waste concentrations
that would remain below a specific target risk. Using the waste pile
scenario at a receptor distance of 150 meters, the study showed that
arsenic levels of 6,000 ppm did not cause exceedences of the target
risk levels. The concentration levels in the gangue are well below this
number. In addition, the location of the facility is remote with the
closest residence two miles away, which is significantly beyond the 150
meter range. The Air Characteristics Study only evaluated direct risks
from inhalation, not indirect risks. However, due to the desert
environment where the facility is located, risks related to consumption
of soil, plants or animals are highly unlikely to arise. Based on these
factors, we believe that the arsenic levels in the gangue do not
present unacceptable risks via the air pathway.
In addition to arsenic, boron and antimony are the two other
constituents of concern present in the gangue. Based on data provided
by the facility, antimony is found at total concentrations ranging from
36 mg/kg to 84 mg/kg in the gangue. The facility estimated the boron
total concentration levels to be 25,000 ppm based on average daily
sampling of the gangue. Arsenic is the most toxic of the three
constituents. Because the particulate releases and exposure scenario
would likely be the same for all three constituents and because, as
discussed above, we do not believe arsenic poses a concern, we also
believe there are no unacceptable levels of risk from the antimony and
boron in the gangue. After assessing possible risks from arsenic, we
compared the ratios of the waste concentrations for the three
constituents to the ingestion health-based level for each constituent.
This ratio for arsenic was an order of magnitude higher than the ratios
for antimony and boron, indicating that the highest potential risk from
ingestion would arise from the arsenic. Thus, based on the lack of
significant risk for arsenic in this waste, the Agency concluded that
neither antimony nor boron pose a significant air risk at this site. In
addition, as mentioned above in the tailings section, the facility has
conducted an air risk assessment. The document shows no significant
risk from the management practices for the gangue waste pile. The
facility's risk assessment is available in the docket for today's
proposal. Therefore, based on all of these factors, we propose not to
list the gangue from the production of boric acid using the kernite ore
process.
(3) Spent filters. We propose not to list the spent filters
generated during the filtration step of the boric acid production
process. The spent filters are stored in a solid waste bin and then
managed in an on-site industrial Subtitle D landfill. The filtration
step occurs late in the process, so we expect minimal contamination. In
addition, because the filters are washed weekly, the vast majority of
any contaminants filtered out at this stage would be captured by the
wash process and managed with the tailings (see section (1) above for
listing determination on the tailings). The facility applies a daily
cover at the landfill which protects against residual particulates from
being released into the air. Furthermore, the quantity of spent filters
is relatively small (3 MT), making it unlikely to present a significant
risk in the landfill. Finally, the location of the facility is remote
with the closest residence being two miles away. Therefore, we propose
not to list the spent filters from the kernite ore process for the
production of boric acid.
4. Cadmium Pigments
a. Summary. We propose not to list any wastes from the production
of cadmium pigments. All of the non-wastewater residuals consistently
exhibit the toxicity characteristic for barium, cadmium, and selenium.
There is only one producer, and over the past seven years the producer
has drummed and shipped with manifests all its non-wastewater residuals
to an off-site Subtitle C facility for treatment to applicable LDR
standards. The
[[Page 55714]]
wastewaters are pretreated on-site in closed tanks prior to discharge
to a POTW, which is regulated under the Clean Water Act. We conclude
that the existing regulatory controls adequately reduce risks, and
there are no exposure pathways of concern. These wastes do not pose a
substantial present or potential hazard, and thus do not meet the
criteria for listing set out in 40 CFR 261.11(a)(3).
b. Description of the cadmium pigments industry. One facility
produced cadmium pigments in the United States in 1998 and 1999.
Cadmium pigments are cadmium sulfides of variable composition, usually
produced as powders but also available in other forms such as pastes
and liquids. Cadmium pigments are used to provide shades of bright
yellow, orange, red, and maroon. The shades depend on the ratio of
cadmium and zinc to sulfides and selenium. Current uses of cadmium
pigments include decorative and protective coatings for plastics,
glass, ceramics, rubber and other materials. The coatings provide heat
resistance to surfaces and a barrier to chemical and sunlight
exposures.
Cadmium pigments are produced by digesting cadmium metal in
sulfuric acid, nitric acid, and water to produce a cadmium sulfate
solution (liquor). Chemical reagents are added to the liquor to
selectively precipitate out metals which are present as impurities.
Sodium sulfide and metals (e.g., zinc, selenium) are added to the
purified liquor to yield a slurry which, after filtration, is the
``greencake'', the first intermediate product from the cadmium pigments
production. The greencakes are then washed, sized, and calcined. The
calcined materials are ground, rewashed, filtered, dried, milled, and
blended to make different shades.
The use of cadmium pigments is declining.\34\ Growth in the overall
demand for cadmium pigments is limited to the manufacturing areas
requiring use of cadmium pigments, such as the plastics industry, where
no substitute is adequate. Our RCRA Section 3007 Survey results show
that six out of seven facilities ceased production of cadmium pigments
in recent years. The domestic demand for cadmium pigments in the next
few years is likely to remain stable. A more complete discussion of
this process and the industry is provided in the ``Cadmium Pigments
Listing Background Document for the Inorganic Chemical Listing
Determination'' in the docket for today's proposal.
---------------------------------------------------------------------------
\34\ USGS Minerals Information, Mineral Commodity Summary, 1996
(see http://minerals.usgs.gov/minerals/pubs/commodity/cadmium/140396.txt)
---------------------------------------------------------------------------
b. What kinds of wastes are generated by this process?. Using the
facility's survey response, we divided the wastes into two broad
categories: Wastewaters and non-wastewaters. Table III-8 summarizes the
types of wastes in each category, the characteristics of each waste,
waste volume, and current management practices:
Table III-8.--Cadmium Pigment Production Wastes
----------------------------------------------------------------------------------------------------------------
Reported waste
Waste category codes 1998 waste volume (MT) Management practice
----------------------------------------------------------------------------------------------------------------
Non-wastewaters
----------------------------------------------------------------------------------------------------------------
Miscellaneous solid wastes, D005 33.5...................... Each waste is drummed
including materials from dust D006 (separately or sometimes
collectors, plant cleanup, D010 combined) and shipped to
filtered pigments from the a commercial off-site
presses, and from the on-site hazardous waste treatment
wastewater pre-treatment process. facility to be treated
and decharacterized
before placing in a
Subtitle D landfill.
Note:
D005--barium
D006--cadmium
D010--selenium
Contaminated paper and cloth, D005 9.3
including filter bags, filter D006
cloths, filter cartridges, and D010
dust collector bags.
Contaminated gaskets generated from D005 0.3
the red and yellow calciners. D006
D010
Iron press residue generated from D005 4.5 ..........................
digestion of cadmium metal. D006
D010
----------------------------------------------------------------------------------------------------------------
Wastewaters
----------------------------------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------------------------------
Gas scrubber wastewater (spent ................ Not reported........... pH adjusted, All these
caustic from scrubbing vapors treated to wastewaters are
generated from calcination remove zinc and then combined
process). cadmium. The and further
resulting sludge treated in on-
is a part of the site closed
miscellaneous tanks for pH
solid wastes. adjustment; 2-
step filtration;
monitoring for
turbidity prior
to discharge to
a POTW.
Process wastewater from ................ Not reported........... pH adjusted,
filtering the greencake. treated to
recover cadmium.
Process wastewaters from wet ................ Not reported...........
washing system.
----------------------------------------------------------------------------------------------------------------
[[Page 55715]]
c. Agency evaluation. After evaluating the characteristics and
current management practices of all the waste residuals, we determined
that: (1) all the non-wastewater wastes are being properly treated and
managed as hazardous wastes under RCRA regulations, and (2) all the
wastewaters are being treated on-site in closed tanks and discharged to
a permitted POTW, where they are subject to the Clean Water Act.
Therefore, we did not pursue risk assessment modeling for any of these
wastes. The following are the details of our evaluation:
(1) Non-wastewaters. In its RCRA Section 3007 Survey, the facility
classified all four wastes of this category as characteristic
hazardous, as generated, for barium, cadmium, and selenium. The
facility also provided data characterizing each non-wastewater residual
for total and TCLP concentrations of eight TC metals. Except for
chromium (which was detected in the TCLP leachate of one waste below
its health-based level), no other hazardous constituents were reported.
The total volume of these four wastes was 47.6 metric tons in 1998.
Over the past seven years the generator has managed all its non-
wastewater wastes generated from the production of cadmium pigments as
TC hazardous wastes. These wastes are drummed and shipped with
manifests to a commercial off-site Subtitle C facility for treatment.
The off-site treatment includes mixing and treating the wastes with
other solid wastes and the addition of lime and fly ash to meet the
current LDR treatment standards (via stabilization). The resultant
mixture forms a concrete-like residue, which no longer exhibits a
characteristic and is managed in a Subtitle D landfill. We believe this
management, which complies with existing Subtitle C regulations,
adequately protects human health and the environment.
Although we generally believe that Subtitle C regulations for
characteristic wastes adequately prevent mismanagement, we have
additional data that help confirm our conclusion for this waste. The
landfill information and leachate data provided by the local and state
governments (per our request) indicate that the landfill has a liner
with a leachate collection system. The landfill leachate data \35\ we
have to date demonstrate that constituents detected in the landfill
leachates are not attributable to the cadmium pigments production
wastes. The landfill information and leachate data are provided in the
``Cadmium Pigments Listing Background Document for the Inorganic
Chemical Listing Determination'' in the docket for today's proposal. We
recognize that the residues from commercial treatment facilities
represent the commingling of wastes from a variety of facilities and
wastes. Therefore, information on the landfill leachate from treated
material is of limited use. However, the data available indicate that
the cadmium pigment wastes do not present a substantial hazard when
disposed. Given that the generating facility has followed the reported
management practice for seven years, we believe use of this or
comparable treatment and disposal will continue.
---------------------------------------------------------------------------
\35\ Quarterly leachate monitoring data from March 95 to
September 98, provided by Michigan's Department of Environment,
Wayne County District Office and Local Office.
---------------------------------------------------------------------------
What Is EPA's Listing Rationale for These Wastes?
We propose not to list any of the four wastes in this category as
hazardous because they are already managed in compliance with existing
hazardous waste regulations, including full compliance with the BDAT
requirements for treatment prior to land disposal. We conclude that
available data on the specific cadmium pigment manufacturing wastes do
not support a decision to list the wastes as hazardous.
(2) Wastewaters. We propose not to list the wastewaters as
hazardous because the gas scrubber and the process wastewaters are
pretreated on-site in closed tanks prior to discharge to a POTW. The
wastewater treatment tanks provide sufficient structural integrity to
minimize potential releases to groundwater. We are unlikely to find
potential air releases from these tanks as neither volatile
contaminants nor airborne particulates are likely to be present in
these wastewaters. During treatment, the closed tanks present no
significant threat of release to the environment. After treatment, the
wastewaters are subject to the Clean Water Act program. We conclude
that the wastewaters do not warrant listing. We assessed solids from
the on-site treatment as miscellaneous wastes discussed above in
section (1).
5. Inorganic Hydrogen Cyanide
a. Summary. We propose not to list any wastes from the production
of inorganic hydrogen cyanide (HCN) as hazardous under Subtitle C of
RCRA. These wastes are managed in on-site wastewater treatment
processes, industrial landfills, municipal landfills, hazardous waste
incinerators, hazardous waste landfills, and hazardous waste injection
wells. After analysis of these waste management practices and potential
exposure pathways, we concluded that there are no risk pathways of
concern. These wastes do not meet the criteria set out at 40 CFR
261.11(a)(3) for listing as hazardous. They do not pose a substantial
present or potential hazard to human health or the environment.
b. Description of the inorganic hydrogen cyanide industry. Hydrogen
cyanide (HCN) is used in the manufacture of a number of important
chemicals including: adiponitrile to produce nylon, methyl methacrylate
to produce clear acrylic plastics, sodium cyanide for the recovery of
gold, triazines for agricultural herbicides, methionine for animal food
supplements, and chelating agents for water treatment.
HCN is manufactured via two primary inorganic synthesis processes:
Andrussow and Blausaure-Methan-Ammoniak (BMA). The Andrussow process
involves the reaction of ammonia, methane (natural gas) and air over a
platinum catalyst; the BMA process is similar except the reaction
occurs in the absence of air. The reaction products are quenched with
water. Excess ammonia reactant is recovered for reuse in the reaction
or converted to an ammonium salt. The aqueous HCN product is purified
and concentrated for use as a liquid feedstock for manufacturing of one
or more of the final products mentioned above. Two of the Andrussow
process manufacturers do not produce a liquid hydrogen cyanide
intermediate product but immediately convert the hydrogen cyanide in
the reactor gases in a sodium hydroxide contactor to produce liquid
sodium cyanide.
There are ten manufacturers of hydrogen cyanide in the United
States who use the Andrussow or the BMA process. Of these ten
manufacturers, only one uses the BMA process. Two of the nine Andrussow
manufacturers use an abbreviated version of the Andrussow process to
produce sodium cyanide. Manufacture of sodium cyanide as a final
product results in fewer wastes and significantly lower wastewater
volumes.
The inorganic hydrogen cyanide industry subject to this rulemaking
is composed only of the facilities that produce hydrogen cyanide as an
intermediate product or feedstock to manufacture a variety of
commercial chemicals using the Andrussow and BMA processes. This
proposal specifically does not cover wastes from the manufacturing of
HCN as a byproduct in the manufacture of acrylonitrile by the
ammoxidation of
[[Page 55716]]
propylene (Sohio process). The Sohio process is inherently an organic
chemical manufacturing process, and is not within the scope of the
inorganic chemicals manufacturing industry or the consent decree.
Furthermore, we have already evaluated wastes for acrylonitrile
manufacturing, and the cyanide wastes associated with the Sohio process
(K011, K013, and K014) are subject to Subtitle C regulation.
c. What kinds of wastes are generated by this process?
How Did We Categorize the Wastes?
Wastes generated from the production of hydrogen cyanide consist of
various types of wastewater, various types of spent filter media, spent
catalyst, biological solids from wastewater treatment, and ammonium
salts. Based on an assessment of the wastes reported in the survey, the
wastes were categorized as follows:
--Commingled wastewaters. This waste includes continuously generated
wastewaters such as HCN purification wastewater and ammonia
purification wastewater.
--Ammonia recycle cartridge and spent carbon filters. This waste
consists of spent filter material and filter solids that are generated
during the filtration of the recycled unreacted ammonia stream prior to
being reused as process feedstock.
--Biological wastewater treatment solids. The biosolids are generated
from the biological treatment of process and non-process wastewaters to
remove residual cyanide and organonitrile contaminants.
--Feed gas cartridge and spent carbon filters. This waste consists of
spent filter material and filter solids that are generated during the
filtration of natural gas prior to being used as process feedstock.
--Process air cartridge filters. This waste consists of spent filter
material and filter solids that are generated during the filtration of
ambient air that is used in the reaction.
--Acid spray cartridge filters. The waste consists of spent filter
cartridges and filter solids from acid spray filters used in the
hydrogen cyanide stripper.
--Spent catalyst. This waste consists of metal gauze panels that
contain the precious-metal catalyst used to catalyze the synthesis
reaction. The catalyst activity diminishes with time and needs to be
replaced with fresh catalyst periodically.
--Ammonium sulfate and ammonium phosphate. The ammonium wastes are
generated from the neutralization of excess ammonia in the process
using sulfuric or phosphoric acid.
--Miscellaneous wastewaters. These numerous wastewaters are generated
during plant upsets or shutdowns for maintenance and are reported in
detail in the ``Inorganic Hydrogen Cyanide Listing Background Document
for the Inorganic Chemical Listing Determination.''
--HCN polymer and sump wastes. These wastes are generated in process
vessels, tanks, and wastewater collection sumps and removed during
periodic plant maintenance operations.
--Sludge from wastewater collection tank. This waste is generated from
the settling of suspended solids in wastewater tanks and removed during
periodic plant maintenance operations.
--HCN storage tank solids. These solids settle out of the HCN product.
The solids are generated during manual tank cleaning after thorough
washing.
--Wastewater filters. These are generated from the filtration of
process wastewater prior to deep-well injection.
--Ammonium sulfate filters. This waste is from the filtration of the
ammonium sulfate solution from the neutralization of excess ammonia by
sulfuric acid. The filtered ammonium sulfate solution is then
crystallized into solid form prior to sale as fertilizer.
--Spent ammonium phosphate. Ammonium phosphate solution is used to
scrub the off-gas from the reactor to assist in ammonium recovery.
--Organic layer from wastewater collection tank. This is generated from
the treatment of commingled HCN wastewater and predominantly non-HCN
process wastewater.
In addition to these wastes, other residuals are produced by some
of the facilities that are recycled back to the production process.
These materials consist of process water and recovered ammonia. These
residuals are reused on-site via enclosed piping systems and tanks,
minimizing the potential for environmental releases. Also, we evaluated
all wastes generated after these secondary materials are reinserted or
reused; we do not believe that these secondary materials present
significant risks. Consequently, we did not evaluate them further.
How Are These Wastes Currently Being Managed?
Table III-9 summarizes the major waste categories, waste
characteristics, waste volumes, and their current management practices:
Table III-9.--Inorganic Hydrogen Cyanide Production Wastes
------------------------------------------------------------------------
1998
Waste Category (Number of Reported volume Management
facilities) Waste Codes 1 (MT) practices
------------------------------------------------------------------------
Commingled wastewaters (8).. D002......... 5,600,000 On-site
wastewater
treatment in
tanks or
surface
impoundments,
discharge to
NPDES outfall
or POTW.
Ammonia recycle cartridge none......... 73 Off-site
and spent carbon filters municipal D
(5). landfill; off-
site
industrial D
landfill; on-
site Subtitle
C landfill; on-
site Subtitle
C
incineration.
Biological wastewater none; F0393.. 45,397 Off-site
treatment solids (4). industrial
Subtitle D
landfill; off-
site municipal
Subtitle D
landfill; on-
site Subtitle
C landfill.
Feed gas cartridge and spent none......... 9.7 Off-site
carbon filters (9). municipal D
landfill; off-
site
industrial D
landfill; on-
site Subtitle
C landfill as
non-hazardous
waste; off-
site recycle/
reuse via
return to
manufacturer.
Process air cartridge none......... 7.5 Off-site
filters (8). municipal D
landfill; off-
site
industrial D
landfill;
reclamation.
[[Page 55717]]
Acid spray cartridge filters none......... 1.1 On-site
(1). Subtitle C
landfill as
nonhazardous
waste.
Spent catalyst (10)......... none......... 4.06 Off-site
reclamation.
Ammonium sulfate and none......... 27,425 Off-site use as
ammonium phosphate (3). fertilizer.
Miscellaneous wastewaters none......... 209,000 Managed with
(4). commingled
wastewaters
described
above.
HCN polymer and sump wastes none......... 0.7 Off-site
(1). industrial D
landfill
Sludge from wastewater D001;D018.... 23.9 Stabilization/
collection tank (2). off-site
Subtitle C
landfill; off-
site Subtitle
C
incineration.
HCN storage tank solids (1). none......... 0.3 Off-site
municipal D
landfill
Wastewater filters (1)...... none......... 450 Captive off-
site Subtitle
C
incineration.
Ammonium sulfate filters (1) none......... 1.1 Off-site
industrial D
landfill
Spent Ammonium Phosphate (1) none......... 230 On-site reuse
as biological
treatment
system
nutrient
source or on-
site
nonhazardous
waste
incineration
Organic layer from D001......... 43.3 Off-site
wastewater collection tank (1993) Subtitle C
(1). incineration
------------------------------------------------------------------------
1 D001 (ignitability), D002 (corrosivity), D018 (benzene).
2 Includes 2.1 MT reported for 1993.
3 One facility commingles wastewater to generate a hazardous waste
derived from F039 wastewater.
d. Agency evaluation. We selected three facilities in Alabama,
Tennessee, and Texas to collect record samples of wastes for the
listing determination. These facilities were selected based on the
survey information for the entire industry sector and collectively
represent all the wastes generated and all of the waste management
practices used by the manufacturing sector.
(1) Commingled wastewaters.
How Many Facilities Generate This Waste Category and How Is It Managed?
Eight of the ten facilities generated commingled wastewaters from
the inorganic hydrogen cyanide process. The total volume of commingled
wastewaters reported by these facilities was 5.5 million MT in 1998.
Six of these eight facilities treat the commingled wastewaters using
one or more of the following operations in their on-site wastewater
treatment processes: (a) steam stripping to remove cyanide and ammonia,
with off-gasses vented to flares, scrubbers or incinerators; (b) pH
adjustment; (c) aerated or non-aerated biological treatment in tanks or
lined/unlined surface impoundments; (d) ozone treatment in tanks; (e)
oxychlorination in surface impoundments; (f) settling in surface
impoundments; and NPDES outfalls, or POTWs. In addition to commingling
of the hydrogen cyanide process wastewaters, some facilities also
commingle these wastewaters with wastewaters from other non-HCN
processes generated in the same chemical manufacturing complex. The
remaining two facilities manage their commingled wastewaters by
filtration and disposal via deepwell injection.
What Management Scenarios Were Assessed?
Based on the reported management practices, we assessed the
potential for releases from tanks and surface impoundments. We decided
that risks from the ultimate discharges to NPDES outfalls and POTWs are
adequately controlled by the Clean Water Act. Risks from discharges to
Class I injection wells with RCRA ``no-migration'' variances are
adequately regulated under the Safe Drinking Water Act and RCRA (see
section III.D.3).
Potential releases to groundwater. We assessed both the tank and
surface impoundment scenarios for potential releases to groundwater and
determined that the unlined surface impoundment scenario poses a more
significant potential risk to groundwater than the tank scenario. We
focused on the surface impoundment pathway because several of the
reported surface impoundments are unlined, posing a potential direct
release pathway to groundwater. We take the position that tanks, by the
impervious nature of the construction materials (concrete, fiberglass,
or steel) are not likely to result in significant releases to
groundwater. We conducted sampling and analysis of these wastewaters at
the three facilities located in Alabama, Tennessee, and Texas currently
using surface impoundment-based wastewater treatment systems. We
assessed each site individually, because we believe it is reasonable to
assume that large volume wastewaters managed in impoundments in
question would not be moved off-site or to different locations.
Our decision on what scenario to assess was based on review of our
analytical data and the characteristics of the surface impoundments
used at the three facilities. We evaluated the potential for
groundwater releases to drinking water wells at the Alabama site, and
potential surface water impacts at the Tennessee facility. The
analytical data for the wastewater managed in the surface impoundment
at the Texas facility showed that all levels of the toxicants of
concern are below health-based levels, or are associated with other
commingled on-site production processes and are not due to HCN
production.
The Alabama facility manages wastewater in a series of surface
impoundments and tanks that provide equalization, oxidation,
maturation, rock-reed filtration, and mixing. In addition, the facility
has an emergency holding basin which has also been used for HCN process
wastewaters. The surface impoundments are equipped with double
synthetic liners with leachate detection and collection systems. The
oxidation basin is a concrete-lined structure with an additional
synthetic liner. Our analytical data indicates that concentrations at
the inlet to the impoundments would exceed the HBLs for one constituent
of concern (acetonitrile). A study of existing wells near the facility
indicates the presence of private water wells within a one-mile radius
of the property boundary. We
[[Page 55718]]
therefore assessed these units further for potential releases to
groundwater.
The Tennessee facility manages the wastewater in unlined surface
impoundments and some of the toxicants of concern were above the
health-based levels and water quality criteria, thus, we assessed this
facility's impoundments for potential releases to groundwater. As
described below, the Tennessee facility and its surface impoundments
are sited on the banks of the Loosahatchie River, with no off-site
downgradient wells. However, we did assess the impact from potential
releases to groundwater to the nearby river at this site.
Potential releases to air. We also examined the air exposure
pathway for the wastewater treatment impoundments and tanks because of
the potential release of volatile organic compounds and hydrogen
cyanide from the wastewater treatment units. EPA is developing maximum
achievable control technology (MACT) standards for cyanide
manufacturing under the Clean Air Act (CAA), which may address these
emissions. Although this rule will be technology-based, the CAA
ultimately requires EPA to regulate significant risks remaining after
the imposition of technology-based controls. EPA has also proposed
regulations under the CAA for volatile organic compound (VOC) emissions
from wastewater at Synthetic Organic Chemical Manufacturing Industry
(SOCMI) facilities, which would cover the HCN manufacturers (see
proposal at 60 FR 46780, September 12, 1994). Therefore, we are
deferring control of any air releases to the MACT and SOCMI standards
and did not assess this pathway further in today's proposal.
How Was This Waste Category Characterized?
We conducted sampling and analysis of these wastewaters at the
three facilities currently using surface impoundment-based wastewater
treatment systems. We collected samples at various places in the
process, including prior to commingling, so that we could assess the
risks of the wastestream at issue here. Today's proposal is based
primarily on samples of the commingled wastewaters collected in the
wastewater treatment plants.\36\ For assessing the groundwater-to-
drinking water pathway at the Alabama facility, we used the sample
collected at the HCN wastewater collection tank where the HCN
wastewaters are collected prior to mixing with other non-HCN
wastewaters in the equalization impoundment. We estimated the
concentration of the constituents of concern in the equalization
impoundment by applying the dilution factor in the impoundment (e.g.,
36 to 1 total wastewaters to HCN wastewaters), and we assessed these
concentrations in our modeling for this pathway. For the groundwater-
to-surface water pathway at the Tennessee facility, we used the sample
collected at the exit from the surface impoundments. We used the sample
from wastewater exiting the unit, rather than at the inlet, because
treatment occurs in the impoundment. However, the inlet data are
similar, and even using the inlet data would not significantly increase
the surface water screening results.
---------------------------------------------------------------------------
\36\ The ``Inorganic Hydrogen Cyanide Listing Background
Document for the Inorganic Chemical Listing Determination,''
available in the docket for today's proposal, provides all
analytical data we developed, as well as split samples collected by
industry, where available.
---------------------------------------------------------------------------
We analyzed the waste for both amenable and total cyanide, as well
as a number of volatile organics and metals. We used the amenable
cyanide results as our cyanide risk assessment inputs because we
believe that amenable cyanide most closely represents the fraction of
cyanide likely to be mobile in a groundwater scenario and the ``free
cyanide'' assessed in our health-based level (HBL). However, this had
no impact on our risk results, because our data show that amenable and
total cyanide results for this waste are the same.
We sampled the wastewater at the Alabama facility in August, 1999.
The analytical data for the commingled HCN wastewaters (DG-1-HC-07)
represent waste concentrations prior to commingling with other non-HCN
wastewaters. Our results for a key chemical, acetonitrile, are
qualified as ``estimated'' for this sample as a result of problems
during sampling and analyses at this site as described further in Waste
Characterization Report, Degussa-Huls; February 25, 2000, available in
the docket for today's proposal. The facility's split samples were more
problematic, because the analytical instruments were not calibrated for
key constituents being analyzed; thus, the split sample results appear
even more uncertain. Despite the estimated nature of the results for
acetonitrile in this waste sample, the data clearly indicate that
acetonitrile is likely to be present in the waste. Acetonitrile, also
commonly referred to as methyl cyanide, is a likely by-product from the
main reaction between methane and ammonia to form hydrogen cyanide. In
addition, samples we collected at the Tennessee facility show that
significant levels of acetonitrile are present in the wastewater,
albeit at somewhat lower levels than we found at the Alabama site.
We initially sampled at the Tennessee facility in August of 1999
(sample DM-1-HC-08). We used the analytical results for this sample as
input to the risk assessment (described further below). However,
because our analytical results for amenable cyanide were qualified due
to holding time exceedences, we sampled at this facility a second time
in October of 1999 to better understand the potential impact of this
waste on the environment (DM-2-HC-08). All of the analytical data for
these samples are available in ``Inorganic Hydrogen Cyanide Listing
Background Document for the Inorganic Chemicals Listing Determination''
in the docket for today's proposal. The second round of sampling showed
lower levels of the key constituent of potential concern than found in
the first round of sampling. Due to time constraints, we did not re-run
the risk assessment model for this pathway to incorporate the second
round of analytical data. However, this would result in somewhat lower
risks, and thus would have had not impacted our proposed decision.
The critical analytical results for the commingled wastewaters for
the Tennessee and Alabama surface impoundments are presented below in
Table III-10. These represent the constituents found to be present in
the wastewaters at level exceeding the HBLs or AWQC. (Several other
constituents were marginally above the AWQC and were not important in
the surface water screening.)
[[Page 55719]]
Table III-10.--Characterization of Commingled Wastewaters From Inorganic HCN Production (mg/L)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Sample DM-2-HC-08
Constituent of concern Sample DM-1-HC-08 2nd Rnd Sample DG-1-HC-07 1 HBL AWQC
--------------------------------------------------------------------------------------------------------------------------------------------------------
Amenable CN....................... 0.638 0.01 0.509 0.3 0.005
Nitrite as N...................... 11.5 no analysis 2.5 2 1
Vinyl chloride.................... 0.029 3 0.0066 L 0.001 0.0009 (0.1) 0.002
Acetonitrile...................... 4 50 K 28 L 190 0.09 (0.045) 2 N/A
Acrylonitrile..................... 0.013 0.001 0.0005 0.002 (0.03) 5.9E-05
--------------------------------------------------------------------------------------------------------------------------------------------------------
1 HBL in parenthesis based on inhalation pathway from residential use of water (e.g., showering).
2 N/A: Not Applicable.
3 L: Qualified result with a low bias for positive result.
4 K: Qualified result with a high bias for positive result.
How Was the Groundwater-To-Drinking Water Risk Assessment Established?
The Alabama facility's surface impoundments are located in the
center of an industrial park on the west side of Mobile Bay. The
wastewater treatment impoundments are located near the eastern property
boundary of the facility and approximately 4,000 feet south of the
State of Alabama barge canal. We chose to assess surface water risks at
the Tennessee facility, which is closer to a surface water body.
However, given the use of groundwater in the area around the Alabama
facility, we assessed the possible impact on drinking water wells. We
selected the equalization basin as the unit for quantitative modeling.
This is the first surface impoundment in the series and is likely to
hold the highest level of constituents of concern. We elected not to
assess the emergency holding pond, which is used primarily during high
stormwater events. Due to the intermittent use of the holding pond, we
expect the potential for significant groundwater releases to be greater
for the equalization pond. In addition, the equalization pond is
covered with a floating synthetic membrane, while the holding pond is
not.\37\ Our modeling of the covered equalization pond did not assume
any loss of the volatile constituents of concern, thus allowing more of
the constituents to infiltrate to the groundwater rather than
volatilize to the air.
---------------------------------------------------------------------------
\37\ The facility reported that the cover on the equalization
unit was installed to ensure compliance with expected new
regulations to control volatile organic carbon emissions from
wastewater sources for the Synthetic Organic Chemical Manufacturing
Industry (SOCMI) (proposal, 59 FR 46780, September 9, 1994).
---------------------------------------------------------------------------
Based on information available in a corrective action plan related
to a product spill on-site (Risk-Based Corrective Action Plan for the
Sodium Cyanide Production Unit at Degussa Corporation Alabama Facility,
Theodore, Alabama; March 19, 1998), the most likely direction of
groundwater flow is to the low-lying areas to the north-northeast of
the surface impoundments. We found there are drinking water wells
located due east of the equalization surface impoundment. Although the
wells are located east of the surface impoundment instead of the
estimated north-northeast groundwater flow direction, they are at
somewhat lower ground elevation than the surface impoundment. Given the
uncertainty in the direction of the groundwater flow, we assumed that
contaminated groundwater from the surface impoundment could migrate to
the east and reach these wells. Based on the available land use and
groundwater use information for this area, we performed risk modeling
for potential releases to drinking water wells located between 3,100
and 5,280 feet east of the surface impoundment. The minimum distance of
3,100 feet is based on the distance from the impoundment to the eastern
boundary of the industrial area controlled by the facility. The maximum
distance of 5,280 is the distance east from the impoundment to the
closest known well. This drinking water well appears to be located just
inside the eastern boundary of the state property, which lies to the
east of the industrial park where the facility is located. We also
assumed that a future well may be placed in the same State property
directly east of the facility's undeveloped tract at approximately
3,100 feet from the surface impoundment. The details of this assessment
are presented in the ``Risk Assessment for the Listing Determinations
for Inorganic Chemical Manufacturing Wastes'' in the docket for today's
proposal. The results of the risk modeling for the only drinking water
constituent of concern are presented in Table III-11 below.
Table III-11.--Groundwater Risk Results for Commingled Wastewaters From
the Production of Inorganic Hydrogen Cyanide
------------------------------------------------------------------------
Acetonitrile
hazard
Percentile quotient
(HQ) 1
------------------------------------------------------------------------
90th %.................................................... 0.3
95th %.................................................... 0.5
------------------------------------------------------------------------
1 Risk from inhalation scenario during showering included exposure
factors for both adult and child in the analysis.
How Was The Groundwater-To-Surface Water Risk Assessment Established?
The Tennessee facility and its surface impoundments are sited on
the banks of the Loosahatchie River. The surface impoundments are
located approximately 800 feet from the river. Based on information
available in the Remedial Facility Investigation (RFI),\38\ the
direction of the groundwater flow is documented to be south towards the
Loosahatchie River. The possibility of a public water supply well or
private well being located downgradient of the Tennessee surface
impoundments is unlikely because the facility boundary extends to the
river to the south. Hence, based on the geologic setting of the
facility as detailed above, we believe it is highly unlikely that these
impoundments could impact drinking water wells via migration of a
contaminated groundwater plume. Based on these facts we did not assess
the groundwater-to-drinking water well pathway further at this site. We
did, however, conduct a screening analysis of potential releases of
groundwater to surface water and subsequent exposure via ingestion
because of the proximity of the unit to the river. We calculated the
concentrations in the river that would result from discharge of
contaminated
[[Page 55720]]
groundwater by estimating the infiltration rate for the unlined
impoundment and diluting the resulting leachate volume into the river
under various flow conditions. The results of this screening level
analysis suggest that concentrations of the constituents of concern in
the river would be well below the aquatic life AWQC and HBLs for
drinking water. The details of the screening analysis are presented in
``Risk Assessment for the Listing Determinations for Inorganic Chemical
Manufacturing Wastes'' in the docket for today's proposal.
---------------------------------------------------------------------------
\38\ U.S. EPA Phase II RFI Workplan, Potentiometric Surface
Plan, March 3 & 4, 1999.
---------------------------------------------------------------------------
What Is EPA's Listing Rationale for This Waste?
Our risk assessment results for the surface impoundment scenario,
summarized above for drinking water in Table III-11, suggest that the
only constituent of concern that required modeling (acetonitrile) does
not pose a substantial present or potential hazard to human health and
the environment. The HQ was below one at both the 90th and 95th
percentile in the probabilistic risk distribution.
The results of our risk analysis also show that hypothetical
releases to the adjacent river would not result in exceedences of risk
thresholds. Our analysis was conducted at a screening level and thus is
based on a number of conservative assumptions that may overstate actual
risk. We did not account for dilution of the potential plume in
groundwater flowing under the surface impoundment that would result in
yet lower river concentrations. We did not account for the likelihood
that river water would be pretreated prior to use for drinking and
showering. We did not account for volatilization, biodegradation, or
hydrolysis of the cyanide and other constituents prior to exposure.
Even if we used the surface impoundment influent concentrations, rather
than the exit concentrations, as input to the analysis, this waste
would not exceed risk thresholds in the adjacent river.
For these reasons, we propose not to list this waste category as
hazardous. For a more complete description of this analysis, see ``Risk
Assessment for the Listing Determination for Inorganic Chemical
Manufacturing Wastes'' in the docket for this proposal.
(2) Ammonia recycle cartridge and spent carbon filters.
How Many Facilities Generate This Waste Category and How Is It Managed?
Five facilities reported generating 73 MT/year of filter media and
waste solids in 1998 from the removal of organonitrile polymers from
the ammonia recycle stream. The management methods reported by the
industry were off-site municipal Subtitle D landfill, off-site
industrial Subtitle D landfill, on-site Subtitle C incineration, and
on-site Subtitle C landfill.
What Management Scenarios Were Assessed?
We conducted risk assessment modeling for off-site disposal in both
a municipal and an industrial landfill, using only those two waste
volumes reported to be managed in off-site Subtitle D landfills;
volumes managed as hazardous wastes were not included in this array. No
significant volatile constituents were detected in this waste (only
non-volatile metals were detected; see following section), thus
volatilization from landfills to the air was not a pathway of concern.
We did not conduct risk assessment of the voluntary Subtitle C
landfill and incineration practices because we assumed that listing
would not significantly increase regulatory control for these wastes.
Note that these on-site captive units have sufficient capacity and
flexibility to accept these relatively small volume non-hazardous
wastes.
How Was This Waste Category Characterized?
Two samples were collected at different facilities. We sampled
again at both facilities because of problems with the cyanide analyses
for the first set of analyses and elevated detection limits for certain
metals in the Tennessee sample. Due to the schedule constraints of this
determination, we initiated the risk analyses using the first round of
samples. The risk analysis and second round of sampling and analysis
were conducted in parallel. HBLs are shown in Table III-12.
Table III-12.--Characterization of Ammonia Recycle Filters
[mg/L]
--------------------------------------------------------------------------------------------------------------------------------------------------------
RH-1-HC-05 (1st data RH-2-HC-05 (2nd data DM-1-HC-04 (1st data DM-02-HC-04 (2nd
set) set) set) data set)
Parameter ---------------------------------------------------------------------------------------- HBL
TCLP SPLP TCLP SPLP TCLP SPLP TCLP SPLP
--------------------------------------------------------------------------------------------------------------------------------------------------------
Antimony............................................. 1 0.55 J 0.59 0.5 0.237 0.5 0.5 0.8 0.08 0.006
Arsenic.............................................. 2 0.045 L 0.039 0.5 0.0137 0.5 0.05 0.5 0.0112 0.0007
Nickel............................................... 0.50 J 0.61 0.2 0.303 0.2 0.0654 0.2 0.0178 0.31
Total CN......................................... N/A 2.4 L 0.230 0.243 0.218 0.187 L 3 0.222 0.303 4 0.31
--------------------------------------------------------------------------------------------------------------------------------------------------------
1 J: Estimated result, due to poor field duplication.
2 L: Qualified result with a low bias for positive result.
3 Average of duplicate sample results.
4 HBL for hydrogen cyanide.
How Was the Groundwater Ingestion Risk Assessment Established?
We assessed the off-site landfill scenario for the ammonia recycle
filter cartridges, reflecting the types of management reported for this
waste. We assessed the groundwater ingestion pathway for these
landfills. Our model inputs included different hydrogeologic settings
reflecting the two regions where the wastes are reported to be managed.
As noted in section III.C., we used the TCLP results for the municipal
landfill scenario and the SPLP for the industrial landfill scenario.
As described above, we had some initial concerns about our
analytical data and determined that re-analysis would serve to
demonstrate the validity of these data. Due to the time constraints of
this listing determination, we could not delay the risk assessment
modeling until the validated results of the second round of analyses
became available, and thus used the first round of samples for the
Texas facility as model input. Subsequently, having reviewed all the
analytical data, we believe that the modeled data set appropriately
characterizes the risks of
[[Page 55721]]
all constituents included in the first sampling round, and that re-
running the model with the second round of analytical data would not
increase the predicted risk. The only additional constituent of concern
found in the second analysis was cadmium. We modeled this constituent
using the same two scenarios and found no significant risk.
What is EPA's Listing Rationale for This Waste?
The results of our probabilistic risk assessment are provided in
Table III-13 below (we also completed deterministic risk modeling and
the results were comparable; see ``Risk Assessment for the Listing
Determinations for Inorganic Chemical Manufacturing Wastes'' for
details). At the 90th and 95th percentile cumulative risk level, we
found no cancer risk in excess of 1E-07, nor did we find any hazard
quotients that exceeded one. As a matter of policy, we generally do not
consider listing wastes with predicted cancer risks of less than 1E-06
or hazard quotients of less than 1.0. We see no special concerns
warranting an exception to this policy. Based on these results we
conclude that this waste does not pose risk to human health and the
environment at levels that warrant listing. We therefore are proposing
not to list ammonia recycle filters from inorganic hydrogen cyanide
production.
Table III-13.--Groundwater Risk Results for Ammonia Recycle Filters 1
----------------------------------------------------------------------------------------------------------------
Antimony Arsenic Cadmium
-----------------------------------------------------------------------------
Percentile Adult Child
Adult HQ Child HQ cancer risk cancer risk Adult HQ Child HQ
----------------------------------------------------------------------------------------------------------------
Industrial Landfill:
90th.......................... 7.9E-02 1.6E-01 3.8E-08 2.8E-08 3.6E-04 7.7E-04
95th.......................... 1.9E-01 3.9E-01 1.6E-07 1.2E-07 1.6E-03 3.4E-03
Municipal Landfill:
90th.......................... 8.7E-02 1.8E-01 3.9E-08 3.1E-08 4.0E-04 8.5E-04
95th.......................... 2.0E-01 4.2E-01 1.8E-07 1.3E-07 1.7E-03 3.7E-03
----------------------------------------------------------------------------------------------------------------
1 Modeling for two other constituents (nickel and cyanide) yielded HQs that were extremely small (1E-16) even at
the 95th%.
(3) Biological wastewater treatment solids.
How Many Facilities Generate This Waste Category and How Is It Managed?
Four facilities reported a total volume of 45,397 MT/year for this
waste. The management methods reported are off-site municipal and
industrial Subtitle D landfills, on-site Subtitle C landfill, and off-
site use as agricultural liming agent (volume not reported).
What Management Scenarios Were Assessed?
We evaluated the Subtitle D landfill and the agricultural liming
agent scenario reflecting the reported management practices. We
assessed the landfill scenario using our TCLP and SPLP results for the
wastes reported managed in such landfills. We assessed the agricultural
use scenario by comparing total constituent concentrations to the soil
screening levels (see section III.C.3).
How Was This Waste Category Characterized?
We collected two samples of this waste at two different facilities.
We conducted total and leaching analyses of these samples. To evaluate
the industrial landfill disposal scenario we compared the SPLP leaching
results to constituent HBLs, and for the municipal landfill scenario we
compared TCLP leaching results to the HBLs. In all cases the SPLP and
TCLP levels corresponding to the management practice were below the
HBLs.
For the agricultural liming scenario, we compared the total
concentrations in the waste to the soil screening levels; no
constituents exceeded these screening levels, i.e., all constituents
were below background or direct soil ingestion levels.
The full analyses are summarized in the ``Inorganic Hydrogen
Cyanide Listing Background Document for the Inorganic Chemicals Listing
Determination'' and the analytical results are reported in detail in
the Waste Characterization Reports for this sector; these documents are
available in the docket for today's proposal.
What Is EPA's Listing Rationale for This Waste?
We propose not to list this waste as hazardous because the levels
of toxicant constituents found in the waste are below the levels of
concern.
(4) Feed gas cartridge and spent carbon filters.
How Many Facilities Generate This Waste Category and How Is It Managed?
Nine facilities reported a total volume of 9.7 MT/year for this
waste. The management methods reported are off-site manufacturer
refurbishing for reuse, off-site municipal D landfill, off-site
industrial D landfill, and on-site C hazardous landfill. The facility
using the hazardous C landfill for disposal of the filters is managing
the filters as nonhazardous waste in a captive on-site C landfill.
What Management Scenarios Were Assessed?
We assessed the municipal and industrial Subtitle D landfill
scenarios using our TCLP and SPLP results, respectively. No volatile
constituents were detected in this waste (only non-volatile metals were
detected; see following section), thus volatilization from landfills to
the air was not a pathway of concern. We did not assess the voluntary
Subtitle C landfill scenario because we assumed that listing would not
significantly increase regulatory control. Note that the on-site unit
has sufficient capacity to continue to accept this small volume waste.
How Was This Waste Category Characterized?
We collected one sample of this waste. The analytical results
showed that SPLP levels for all constituents are below drinking water
HBLs. The TCLP results showed levels that exceeded HBLs for the
constituents summarized below in Table III-14:
[[Page 55722]]
Table III-14.--Characterization of Feed Gas Filters From Inorganic HCN Production
[mg/kg or mg/L]
----------------------------------------------------------------------------------------------------------------
Constituent Total TCLP SPLP HBL
----------------------------------------------------------------------------------------------------------------
Boron....................................................... 17,900 7.4 0.5 1.4
Lead........................................................ 18.5 1 0.03 1 0.003 0.015
Nickel...................................................... 91.0 0.4 0.05 0.31
Zinc........................................................ 1,060 13 0.5 5
----------------------------------------------------------------------------------------------------------------
1 Results are less than the typical laboratory reporting limit, but are greater than the calculated instrument
detection limits.
Split sample results provided by the facility were comparable. We
did not find cyanide in these wastes.
The full analytical results are summarized in the ``Inorganic
Hydrogen Cyanide Listing Background Document for the Inorganic
Chemicals Listing Determination'' and are reported in detail in the
Waste Characterization Reports for this sector; these documents are
available in the docket for today's proposal.
How Was the Groundwater Ingestion Risk Assessment Established?
We assessed the groundwater ingestion pathway for the off-site
landfill scenario for this waste, reflecting the types of management
reported. As noted in section III.E., we used the TCLP results for the
municipal landfill scenario and the SPLP for the industrial landfill
scenario. We found that the industrial Subtitle D landfill scenario
screened out because all constituents in the SPLP analysis were below
their respective HBLs.
The constituents of concern that exceeded their respective HBLs in
the TCLP results were boron, lead, nickel, and zinc. We evaluated these
constituents using the de minimis volume screening analysis, as
described in section III.E.3 of today's proposal. The analysis suggests
that lead, nickel and zinc are not of concern. We modeled the remaining
constituent, boron, using our standard groundwater model for the
municipal landfill scenario. We modeled the municipal landfill
scenario, using a hydrogeologic setting reflecting the region where the
waste was reported to be managed.
What Is EPA's Listing Rationale for This Waste?
As noted above, the industrial landfill scenario screened out. For
the municipal landfill scenario, the results in Table III-15 show that
the HQs are well below one at both the 90th and 95th% for the
constituent of concern. Thus, our risk assessment results suggest that
the only constituent of concern that required modeling (boron) does not
pose a substantial present or potential hazard to human health and the
environment. For a more complete description of this analysis, see
``Risk Assessment for the Listing Determinations for Inorganic Chemical
Manufacturing Wastes' in the docket. Thus, we propose not to list this
waste as hazardous.
Table III-15.--Groundwater Risk Results for Feed Gas Filters for Boron
------------------------------------------------------------------------
Adult Child
Percentile HQ HQ
------------------------------------------------------------------------
90th.................................................... 0.007 0.01
95th.................................................... 0.01 0.05
------------------------------------------------------------------------
(5) Process air cartridge filters.
How Many Facilities Generate This Waste Category and How Is It Managed?
Eight facilities reported a total volume of 7.5 MT/year for this
waste. The management methods reported are off-site industrial D
landfill, off-site manufacturer refurbishing for reuse, off-site
municipal D landfill, and on-site industrial D landfill. Most
facilities reported the practice of filtering the air that they feed to
the reactors. Very small volumes of spent filters are generated
periodically. We did not assess these wastes beyond the
characterization provided in the RCRA Section 3007 Survey results
because no wastes were available to sample when we conducted our
sampling. The level of toxic constituents is expected to be low because
the filters are only used to remove airborne solids from the ambient
air used in the process.
What Is EPA's Listing Rationale for This Waste?
We propose not to list this waste as hazardous because we do not
believe that the level of any toxic constituents in these small waste
volumes would exceed levels of concern that would pose a risk based on
management in Subtitle D landfills.
(6) Acid spray cartridge filters.
How Many Facilities Generate This Waste Category and How Is It Managed?
One facility reported a total volume of 1.1 MT/year for this waste.
The management method reported was on-site Subtitle C disposal as a
nonhazardous waste. The cartridge-type filter elements are used in the
process to prevent clogging of spray nozzles used to inject the
hydrogen cyanide intermediate product into the HCN stripper. The
filters remove process particulates, including rust, from the hydrogen
cyanide intermediate product. The waste is generated when the spent
filter elements are replaced weekly. While this waste is classified as
nonhazardous, the generator disposes of it in the facility's on-site
Subtitle C landfill.
How Was This Waste Category Characterized?
No sample of this waste was collected because of unavailability
during the sampling time frame and because the level of toxic
constituents is expected to be low. The filters are used to remove
inert impurities such as pipe scale. The facility washes the filters
prior to removal of the filters from the process. We expect that any
hydrogen cyanide contamination is removed during this washing. The
facility reported in its RCRA Section 3007 Survey that the waste
contains a total concentration of cyanide of one ppm.
What Is EPA's Listing Rationale for This Waste?
We propose not to list this waste as hazardous because the level of
toxic constituents found in this waste are expected to be below levels
of concern. While we do not have any leaching test data, we can
conservatively estimate that any leachable level of cyanide would be at
least 20-fold less than the 1 ppm total level reported, i.e, less than
0.05 mg/L. This is well below the HBL for amenable cyanide (0.3 mg/L).
Furthermore, this small volume waste is already managed in a Subtitle C
landfill.
(7) Spent catalyst. All ten facilities reported generation of this
waste, with a combined total volume of 4.1 MT/year. The management
method reported was off-site metals reclamation or regeneration. These
catalysts gradually lose their effectiveness over time and are
periodically reclaimed. Due to the
[[Page 55723]]
high value of these precious-metal materials, generators maintain close
control over these materials. The spent material is an impermeable
metal gauze that undergoes thorough cleaning and decontamination to
eliminate cyanide concentrations prior to removal from the reactor. We
have chosen not to evaluate these materials further because management
practices for these materials prior to reuse minimize the potential for
environmental releases. Therefore, we propose not to list this waste as
hazardous because there are no significant known exposure pathways that
would present risk.
(8) Ammonium sulfate and ammonium phosphate.
How Many Facilities Generate This Waste Category and How Is It Managed?
Three facilities reported a total volume of 27,425 MT/year for this
waste. The management method reported was off-site use as fertilizer.
What Management Scenarios Were Assessed?
We assessed the agricultural end use of this waste by comparing the
total constituent results to the soil screening levels. In this case we
evaluated the material, because it is land applied.
How Was This Waste Category Characterized?
One sample of this by-product was collected from the Alabama site.
The analytical data results show that the detected constituents of
concern in the total analyses are below the soil screening levels. In
addition, we compared the SPLP leaching results to the HBLs as a screen
of potential groundwater exposure.\39\ The detected SPLP results are
below the HBLs. The analytical results showing the level of toxic
constituents are included in the ``Inorganic Hydrogen Cyanide Listing
Background Document for the Inorganic Chemicals Listing
Determination.''
---------------------------------------------------------------------------
\39\ Note that the SPLP/HBL groundwater screen for this scenario
is likely to be a worse-case screening, because the fertilizer
application scenario isn ot analogous to a landfill scenario,
particularly with respect to application rates.
---------------------------------------------------------------------------
What Is EPA's Listing Rationale for This Waste?
We propose not to list this waste as hazardous because the levels
of toxic constituents found in the waste are below levels of concern.
(9) Miscellaneous wastewaters.
How Many Facilities Generate This Waste Category and How Is It Managed?
Four facilities reported a total volume of 209,000 MT/year for this
waste category; the total volume represents twenty two different
miscellaneous wastestreams that are generated on an intermittent or
periodic basis. The management method reported was commingling with
other major process wastewater streams described above as the
``commingled wastewaters'' category.
What Management Scenarios Were Assessed?
We did not assess these numerous wastewater streams individually.
The wastewaters were assessed indirectly within the commingled
wastewater category discussed earlier. The volume and constituents
represented by these miscellaneous wastewaters are represented in the
total commingled major and miscellaneous wastewater streams.
How Was This Waste Category Characterized?
We did not collect samples of these miscellaneous wastewater
streams. The levels of toxic contaminants in these wastewaters are
reflected in the contaminant concentrations of the total commingled
wastewater streams at each facility. See the commingled wastewater
category discussed earlier in this section for a discussion on how the
commingled major and miscellaneous wastewater streams were
characterized. Two of the miscellaneous wastewaters were reported to
contain potentially high concentrations of hydrogen cyanide when
generated.
What Is EPA's Listing Rationale for This Waste Category?
We propose not to list this waste category as hazardous. There is
no direct exposure pathway into the environment from these individual
wastes, because they are treated and commingled with the other
wastewaters generated at each facility. Although high concentrations of
hydrogen cyanide in the wastewaters are possible for some of these
wastes, the risk is reduced by the high dilution that occurs when these
wastewaters are mixed with other large volume wastewaters in the
facility-wide wastewater collection system. These miscellaneous
wastewaters are generated intermittently and infrequently. Thus, any
potential releases from land-based management of the wastes after
dilution in with other wastewaters would be short-lived, and unlikely
to result in any significant long-term risk. In addition, the hydrogen
cyanide contaminant is readily and rapidly treated in the wastewater
treatment systems, so that any risk is minimized. For example, the tank
farm scrubber water from the Tennessee facility is treated through
oxychlorination, which rapidly destroys the hydrogen cyanide. As noted
earlier, potential hydrogen cyanide releases via the air pathway would
be covered by the Hydrogen Cyanide MACT rule.
(10) HCN polymer and HCN sump wastes. One facility reported a total
volume of 0.7 MT/year (0.3 MT/yr polymer and 0.4 MT/year sump wastes)
for these two wastes. The physical description of the wastes was
reported as dirt, debris and inert polymer solids. The wastes are
disposed of in an off-site industrial Subtitle D landfill. Very small
volumes of these wastes are generated periodically. We did not assess
these wastes beyond the characterization provided in the RCRA Section
3007 Survey results because of the unavailability under the sample
schedule and because of the low concentrations of toxic constituents
expected to be present in this waste.
In the RCRA Section 3007 Survey, the one generator reported that
total levels of cyanide were 50 mg/kg for the HCN polymer and 5 mg/kg
for the sump wastes. These levels are unlikely to pose a risk in a
landfill scenario for these very small waste volumes. In support of
this, we note here, as we did above for the acid spray filter cartridge
waste category, leaching test results would be at least 20-fold less
than the total levels. This would mean any leaching from sump waste
would be below the HBL for cyanide. While this 20-fold factor would
leave the HCN polymer somewhat above the HBL at 2.5 ppm cyanide, we
note that groundwater modeling for cyanide for the ammonia recycle
filters indicates similar levels of cyanide in a larger waste volume
presents very low levels of risk in a landfill scenario. Therefore, we
propose not to list HCN polymer and HCN sump wastes.
(11) Sludge from wastewater collection tank. One facility reported
a volume of 2.1 MT over a seven year period, or approximately 0.3 MT/
year for this waste. The waste was coded as hazardous (D001),
stabilized on-site and disposed of in an off-site Subtitle C landfill.
The waste is generated approximately every ten years; the volume
reported was for 1993 with no generation of that waste since that date.
This waste results from sedimentation in a wastewater collection tank.
HCN wastewaters managed in this tank only account for ten percent of
throughput; the sediment thus is only marginally associated with HCN
production. One other facility reported generating 1.8 MT of this
waste, and also codes it as characteristically hazardous waste (in this
case as D018 for benzene). This
[[Page 55724]]
second facility sends the waste off-site to a Subtitle C incinerator;
the facility reported that the benzene was derived from other on-site
processes. We propose not to list these wastes because they are very
small volume wastes that are already managed as characteristically
hazardous wastes in full compliance with the Subtitle C regulations. In
addition, the wastes are generated from the treatment of predominantly
non-HCN wastewater from unrelated petrochemical processes at the
facilities.
(12) HCN storage tank solids. One facility reported a volume of 0.3
MT/year for this waste. During periodic shutdowns of this product tank
for cleaning, solids are removed after rigorous washing of the tank
interior to remove soluble cyanide. The waste consists of polymer and
tank scale. The waste is disposed of in an off-site municipal Subtitle
D landfill. A sample of this waste was not collected because of
unavailability during the sampling time frame. However, the waste
description provided by the facility indicates the waste is similar in
composition to the ammonia recycle filters, which we have proposed not
to list. Given the much smaller volume here, this waste is not expected
to present significant risk. Therefore, we are proposing not to list
this waste as hazardous.
(13) Wastewater filters. One facility reported a volume of 450 MT/
year for this waste. The waste is managed in a captive, off-site
Subtitle C incinerator as characteristically hazardous waste. The waste
is spent filters from the filtration of commingled wastewaters from
various on-site processes prior to on-site deepwell injection and is
generated periodically. A sample of this waste was not available during
the sampling time frame. However, the one generator reported that the
waste is characteristically hazardous due to benzene, and the facility
manages the waste as D018. The source of the benzene is the waste from
other non-HCN process wastewaters at the facility. We propose not to
list this waste because it is already managed as a hazardous waste in
accordance with Subtitle C regulations.
(14) Ammonium sulfate filters. One facility reported a volume of
1.1 MT/year for this waste. The waste is managed in an off-site
industrial landfill. The waste is generated periodically. We did not
assess this waste beyond the characterization provided in the RCRA
Section 3007 Survey results because of the unavailability of samples
under the sample schedule. However, the facility reported
concentrations of cyanide (1 mg/kg) and ammonium sulfate (5,000 mg/kg).
This concentration of cyanide is considered to be very small and is not
expected to be of concern (see discussion of cyanide for acid spray
cartridge filters). In addition, we collected a sample of the ammonium
sulfate by-product (i.e., the material being filtered to generate this
waste) and did not find any constituents of concern. See discussions
for ammonium sulfate and ammonium phosphate. Therefore, we propose not
to list this waste as hazardous because we do not believe that there
are any significant levels of toxic constituents in the waste.
(15) Spent ammonium phosphate. One facility reported a volume of
230 MT/year for this waste. The waste is reused on-site as a nutrient
source in the biological treatment unit or incinerated on-site in a
nonhazardous waste incinerator. The waste is generated in batches one
or two times per year. The waste is generated from the scrubbing of the
reactor off-gas stream using aqueous monoammonium phosphate solution in
the ammonia recovery process. The resulting diammonium phosphate
solution is then purified to recover the ammonia and the resulting
spent ammonium phosphate solution is stored in tanks prior to final
management. We did not assess this waste beyond the characterization
provided in the Sec. 3007 Survey results because of the unavailability
of samples under the sample schedule; the characterization indicates
the presence of organonitrile compounds in the waste. However, the
preferred management method is to reuse the waste as a nutrient source
in the biotreatment system, with incineration only when this is not
possible due to the solution becoming spent or when the concentrations
of phosphate and ammonia are incompatible with the wastewater treatment
system. We believe the levels of organonitrile compounds do not pose a
risk under either management scenario. The wastewater treatment
scenario results in the destruction of the compounds via biodegradation
and the incineration scenario would also result in destruction of the
volatile organonitriles. Additionally, emissions from the on-site
incinerator would be regulated under the Hydrogen Cyanide MACT
standards which will be proposed in 2000. Therefore, we propose not to
list this waste as hazardous.
(16) Organic layer from wastewater collection tank. One facility
reported a volume of 43.3 MT/year for this waste. The waste is coded as
D001 and sent off-site Subtitle C incineration. This waste is generated
approximately every ten years; the volume reported was for 1993 with no
generation of the waste since that date. Thus, on an annualized basis
the waste quantity generated would be approximately 4 MT/yr. We did not
assess these wastes beyond the characterization provided in the RCRA
Section 3007 Survey results because of the unavailability of samples
under the sample schedule. We propose not to list this waste as
hazardous because the waste is managed as characteristically hazardous
in accordance with all applicable Subtitle C standards, which
adequately protect against mismanagement. Further, the waste is
generated from the treatment of predominantly non-HCN wastewater from
other unrelated petrochemical processes at the facility. Only ten
percent of the wastewater throughput in the tank generating this waste
is associated with HCN production; the percentage contribution from the
HCN process to this oily layer is likely to be much lower, because
other petrochemical processes on-site are likely sources of the organic
material.
6. Phenyl Mercuric Acetate
a. Summary. We propose not to list any wastes from the production
of phenyl mercuric acetate (PMA) as hazardous under Subtitle C of RCRA.
PMA currently is not manufactured in the United States, and it is
extremely unlikely that it will be manufactured in the United States in
the future. Therefore, there are no wastes being generated that could
be subject to a listing determination.
b. Description of the phenyl mercuric acetate industry. PMA
(C8H8Hg O2) is an organic mercury
compound, a white to creamy white odorless crystalline powder or clear
solution. Prior to 1990 it was the predominant fungicide used in the
latex paint industry. In 1990, EPA banned the use of PMA in interior
paint (55 FR 26754, June 29, 1990) and subsequently, the paint industry
ceased using PMA in paint production. PMA is still used for other
limited purposes (e.g., slimicide in paper mills; selective herbicide
for crabgrass; fungicide for diseases of turf on golf greens and tees;
fungicidal seed dressing for seed- and soil-borne diseases of cereals,
sorghum, and groundnuts).
Based on our research and the results of our RCRA Section 3007
Survey, we conclude that there is no domestic production of PMA. Any
domestic demand is met by imports from other countries. See the
``Phenyl Mercuric Acetate Listing Background Document for the Inorganic
Chemical Listing Determination'' for details.
[[Page 55725]]
c. Agency evaluation. PMA is not produced within the United States
and is not widely used in domestic manufacturing processes. Therefore,
we have no reason to believe that wastes from the production of PMA are
generated within the U.S. Given the compound's limited market within
the U.S., it is highly unlikely that new production of PMA will occur
within the U.S. in the future. As a result of these market conditions,
there are no wastes that can be assessed for this sector. Therefore, we
propose not to list any PMA production wastes as hazardous.
7. Phosphoric Acid From the Dry Process
a. Summary. We have evaluated the wastes from the production of
phosphoric acid manufactured via the dry process, and propose not to
list any wastes from this process as hazardous wastes. These
wastestreams do not meet the criteria set out at 40 CFR 261.11(a)(3)
for listing wastes as hazardous. They do not pose a substantial present
or potential threat to human health or the environment. We have
identified no risks of concern associated with the current management
of these wastes.
b. Description of the phosphoric acid industry.
Phosphoric acid was produced by the dry process by eight facilities
in the United States in 1998. The majority of phosphoric acid is
consumed in the manufacture of phosphate salts. These phosphorus-
containing compounds are used in detergents, animal feed supplements,
dentifrices, fertilizers, metal treating, water softening, leavening
agents, and flame and fire retardants.
In the dry process, elemental phosphorous is burned in excess air
generating phosphorous pentoxide (P2O5). The
resulting phosphorus pentoxide is hydrated with a spray of recycled
phosphoric acid and water, forming phosphoric acid that is collected as
product. Scrubbers are employed for the hydrator off-gases to absorb as
much phosphoric acid mist as possible from the excess air. The strong
phosphoric acid stream from the hydrator is purified with hydrogen
sulfide to precipitate out arsenic trisulfide. This sludge is removed
by filtration. In some cases, off-specification product is filtered and
recycled into the process. The product may also be filtered after it
leaves the storage tank and prior to loading in truck and railcars.
c. Description of wastes generated by the phosphoric acid process.
We have identified fourteen waste categories from the production of
phosphoric acid (via the dry process) that required assessment. These
waste categories are described briefly and in more detail in the
following subsections.\40\
---------------------------------------------------------------------------
\40\ One facility has shut down their phosphoric acid process
and reported few wastes generated in 1998. This facility's wastes
therefore are not included in the following overview, but were
evaluated to determine their potential threat to human health or the
environment. The details of this facility's waste generation and
management practices are included in the ``Phosphoric Acid Listing
Background Document for the Inorganic Chemical Listing
Determination''.
--Arsenic filter cake is the result of filtering the phosphoric acid
after the addition of sodium hydrosulfide or hydrogen sulfide gas and a
filter aid. The precipitate consists of arsenic trisulfide and other
heavy metal sulfides which are essentially insoluble in strong acid.
--Combustion chamber slag (infrequently generated) is the result of
residue buildup on the walls of the chamber.
--Off-specification phosphoric acid is generated when the product does
not meet color or concentration specifications.
--Spent filters (from purification) are generated from the units that
are used to remove arsenic from the phosphoric acid.
--Caustic scrubber water is generated when air used to remove hydrogen
sulfide gas at the acid purification step is scrubbed. This scrubbing
operation controls odor and acid mist before the air is discharged to
the atmosphere.
--Phosphoric acid spills occur around the process or storage tanks
area. These materials are collected in contained areas and pumped to
management units.
--Clean-up and washdown water from across the units is collected in a
sump and discharged to the wastewater treatment system.
--Process acid leaks occur when piping and coupling break, or during
equipment maintenance. These materials are collected in contained areas
and pumped to management units.
--Spent mist eliminator packing (filters) are used in the scrubber
system to remove gas and acid particulates from the phosphoric acid.
The filter packing material is reported to consist of polyester fibers,
stainless steel, steel wool or fiberglass. The filters are periodically
replaced and the spent packing is washed prior to disposal.
--Rubber liners of product storage tanks are periodically replaced.
--Spent filters for product are generated when product is filtered
prior to loading into tank cars and trucks to remove settled solids.
The filters are changed periodically and rinsed with water prior to
disposal.
--Spent activated carbon for off-specification product is generated
when carbon is used to remove traces of contaminants from the off-
specification product.
--Spent filters for off-specification product is generated when filters
are used to remove solids from the off-specification product.
--Wastewater treatment sludges are generated when wastewaters from the
phosphoric acid and other processes are treated. These sludges are only
marginally derived from phosphoric acid wastewaters due to commingling
with large volumes of other non-phosphoric acid wastewaters. The solids
that are removed by filtration are landfilled or sold.
Three facilities reported that they collect phosphoric acid in air
pollution control devices (i.e., vent scrubbers, absorbers, mist
eliminator). Each site reported that they then recycle these acids into
the production process. This material is continuously reused in the
production process. Based on our site visits, the material is piped
from the generating unit to the production process, minimizing the
potential for releases to the environment prior to reuse. We evaluated
all wastes generated after the materials are reused and concluded that
none merited listing. Consequently, we do not believe that these
materials present significant threats.
At two of the facilities, the caustic scrubber water, generated
from scrubbing the air to remove hydrogen sulfide gas, is returned as
makeup solution to the purification process. Based on information from
one of the facilities and our site visit, the material is piped from
the generating unit to the production process, and there is no
significant potential for exposure. Also, process acid leaks are
collected in tanks at one facility and piped back to the acid process,
with no significant exposure route for this material. As stated above,
we evaluated all wastes generated after the materials are reused and
concluded that none merited listing. Consequently, we do not believe
that these materials present significant threats.
We have organized our discussion of these wastes in terms of how
they are currently managed: characteristic wastes, wastewaters, and
non-characteristic solid wastes.
[[Page 55726]]
d. Agency evaluation. (1) Characteristic wastes. The RCRA Section
3007 Surveys show that a number of wastes are managed as RCRA
characteristic wastes at all times. These wastes are hazardous wastes
because they exhibit the characteristics of corrosivity or toxicity for
arsenic. We believe that these wastes are managed according to the
applicable RCRA Subtitle C regulations, including LDR standards. The
LDR restrictions apply prior to land disposal. Furthermore, these
wastes are managed or disposed in Subtitle C management units. Table
III-16 summarizes our information regarding the generation and
management of these wastes.
Table III-16.--Characteristic Wastes From Phosphoric Acid Production Disposed in Subtitle C Units
----------------------------------------------------------------------------------------------------------------
Number of
Waste category reported 1998 Volume Reported hazard codes Final management
generators (MT) practices
----------------------------------------------------------------------------------------------------------------
Arsenic filter cake............... 7 614 D002, D004........... Subtitle C landfill
Combustion chamber slag........... 1 0.1 D002................. Subtitle C
incineration
Off-specification phosphoric acid. 1 0.71 D002................. Subtitle C landfill
Spent filters (from purification). 2 4.6 D004................. Subtitle C
incineration or
Subtitle C landfill
----------------------------------------------------------------------------------------------------------------
We propose not to list these four waste categories as hazardous
wastes under RCRA. All generators of these wastes already report
managing these materials as hazardous from the point of generation
through disposal, because they exhibit one or more of the hazardous
waste characteristics. We believe that the rules applying to
characteristic wastes adequately protect against mismanagement.
(2) Other characteristic waste.
Table III-17.--Other Characteristic Wastes from the Production of Phosphoric Acid
----------------------------------------------------------------------------------------------------------------
Number of
Waste category reported 1998 Volume Reported hazard codes Sequential management
generators (MT) practices
----------------------------------------------------------------------------------------------------------------
Phosphoric acid spills............ 2 2.2 D002................. (1) Neutralized, (2)
roll-off bin, (3)
Subtitle D landfill;
(1) Tanks, (2)
neutralized in
surface impoundment,
(3) NPDES
----------------------------------------------------------------------------------------------------------------
We assessed the specific management practices employed for this
wastestream, as summarized in Table III-17, and determined that no
exposure scenarios of concern exist. One facility reported that the
wastestream is managed as hazardous (D002), neutralized, and disposed
of in a Subtitle D landfill. These product spills are expected to be
mostly phosphoric acid, which is hazardous because it is corrosive. The
facility effectively treats and neutralizes these wastes prior to
disposal. There is no significant risk expected from the disposal of
the small volume (0.5 MT/yr) of treated spills to the landfill.
The second facility reported placing the untreated spills into its
wastewater treatment system, which includes both tanks and
impoundments. Again, we expect that this waste presents hazards because
of its corrosivity, not because it contains hazardous constituents. We
do not expect releases to groundwater from tanks because we assume that
they function effectively. With regard to the surface impoundment, we
note that the facility has estimated that these small volume spills
make up less than 0.001% of the total wastewater volumes. We expect
that dilution of this magnitude would effectively treat the spills
rapidly. Further, the facility reported that the wastewaters in the
impoundment are neutralized. Consequently, we do not anticipate that
any potential releases from the surface impoundment would pose a
significant threat to groundwater. Ultimately, the spills are
discharged, along with the much larger volume of wastewaters generated
on-site, to surface waters under a NPDES permit, which provides
effective control and an exemption from RCRA regulations. We also note
that we expect no release of constituents of concern to the air from
either the tank or the impoundments, because the waste contains no
volatile constituents.
(3) Wastewaters. Wastewaters are generated at various points in the
process as a result of scrubbing operations, equipment cleanup, and
management of leaks and spills. As reported by the facilities, the
primary constituents of concern in these wastewaters are phosphoric
acid and traces of hydrogen sulfide, which are readily treated and
controlled via neutralization. Phosphoric acid, when neutralized, forms
various phosphate salts, none of which are known to pose a significant
risk to human health and the environment. Similarly, hydrogen sulfide
is neutralized to form nonvolatile salts. All facilities report that
these wastewaters comprise very small portions of the overall
wastewater treatment throughput, which contains wastewaters from other
unrelated on-site processes. Table III-18 summarizes our information on
these wastewaters.
Table III-18.--Wastewaters From Phosphoric Acid Production
----------------------------------------------------------------------------------------------------------------
Number of Sequential
Waste category reported 1998 Volume Reported hazard codes management
generators (MT) practices
----------------------------------------------------------------------------------------------------------------
Caustic scrubber water........... 1 36 none.................... (1) pretreatment in
covered tanks,
(2) POTW
[[Page 55727]]
Cleanup water.................... 1 small volume none.................... (1) pretreatment in
(volume not covered tanks,
reported) (2) POTW
Process acid leaks............... 1 25\1\ none.................... (1) pretreatment in
covered tanks,
(2) NPDES
----------------------------------------------------------------------------------------------------------------
\1\ The 25 tons include leaks from eight processes, of which one is phosphoric acid production. The individual
volume of leaks from phosphoric acid production is unknown.
We have assessed the management practices employed for these wastes
and determined that no exposure pathway of concern exists. We believe
these wastewaters will continue to be managed in existing tank-based
treatment systems. We believe the manufacturers have made a
considerable investment in wastewater treatment systems using tanks and
will continue to use them. Further, we assumed that wastewater
treatment tanks retain sufficient structural integrity to prevent
wastewater releases to the subsurface (and therefore to groundwater),
and that overflow and spill controls prevent significant wastewater
releases. Thus, based on the lack of any significant likelihood of
release of the constituents to groundwater, we did not project
significant risks to groundwater from these wastes in the tank-based
wastewater treatment scenario. Furthermore, discharges to POTWs and
surface waters under NPDES are regulated under the Clean Water Act and
are exempt from RCRA Subtitle C regulation and thus were not assessed.
We also considered the possibility of air releases from tanks. The
only potential volatile constituent of concern in these wastes is
hydrogen sulfide. The treatment processes employed are designed to
neutralize this compound, reducing the potential for volatilization. In
addition, the facilities have installed tank covers, further reducing
the likelihood of release to the air. As a result, we did not model
releases to air from tanks from the production of phosphoric acid.
Thus, we propose not to list these wastewaters as hazardous wastes
under RCRA.
(4) Non-characteristic solid wastes. The phosphoric acid sector
reported six waste categories that do not routinely exhibit any of the
hazardous waste characteristics and that are often managed in Subtitle
D landfills, as summarized in Table III-19:
Table III-19.--Non-characteristic Solid Wastes
----------------------------------------------------------------------------------------------------------------
Number of Sequential
Waste category reported 1998 Volume Reported hazard codes management
generators (MT) practices
----------------------------------------------------------------------------------------------------------------
Spent mist eliminator packing.... 5 28.4 None.................... (1) storage in
containers, (2)
treatment to
control acid
(washing,
neutralization, or
off-site
stabilization by
one facility), (3)
recycling or
disposal in
Subtitle C or D
landfills.
Rubber liners.................... 2 19.8 None.................... (1) storage in
containers, (2)
Subtitle C
incineration or
neutralization
before Subtitle D
landfill.
Spent filters for product........ 1 0.5 None.................... (1) storage in
containers, (2)
off-site
stabilization, (3)
Subtitle D
landfill.
Spent activated carbon for off- 1 1 3 None.................... (1) storage in
specification product. containers, (2)
off-site
stabilization, (3)
Subtitle D
landfill.
Spent filters for off- 1 0.5 None.................... (1) storage in
specification product. containers, (2)
off-site
stabilization, (3)
Subtitle D
landfill.
Wastewater treatment sludges..... 3 2 0.005 None.................... (1) storage in
containers, (2)
Subtitle D
landfill.
----------------------------------------------------------------------------------------------------------------
\1\ 1996 volume; none generated in 1997 or 1998.
\2\ Two facilities did not report volumes due to very small input of phosphoric acid production wastes to the
WWT system; one facility estimated that 0.0001% of 4,640 MT sludge generated (or 0.005 MT) was from phosphoric
acid production.
The spent mist filters collect phosphoric acid mist before arsenic
trisulfide is precipitated out. The material which condenses in the
filters is expected to be corrosive and may contain some arsenic.
However, the material used for filter packing in the mist eliminators
is typically polyester, fiberglass, or steel wool. The filter packing
provides surface area for condensation, not absorption, and is not
expected to accumulate waste or constituents. Thus, arsenic is not
expected to adhere to the filters as condensate drops back into
process. The generators treat the spent filters prior to disposal to
remove or immobilize any low levels of constituents that may remain.
The rubber liners and spent filters for product are associated with
food-grade products. We expect any contaminant levels to be extremely
low due to purity requirements. Consequently, we believe it is unlikely
that they contain any constituent at levels of concern (i.e., above
health-based limits for ingestion). We also note that both wastes are
treated prior to disposal in landfills.
Similarly, we do not expect the spent carbon or spent filters
associated with off-specification product to contain significant levels
of constituents of concern. Product is classified as ``off-
specification'' due to color and concentration of acid, rather than
[[Page 55728]]
because of the presence of any contaminants. We note again that these
wastes undergo treatment prior to placement in landfills. In addition,
both the activated carbon, which is infrequently generated, and the
off-specification filters are very low volume wastes (on an annualized
basis, the spent carbon totals about 1 MT and the spent off-
specification filters equal 0.5 MT).
As stated in the wastewater rationale, the wastewater contribution
from the phosphoric acid process is insignificant. Therefore, the
volumes of treatment sludge (and any constituents of potential concern)
attributable to the phosphoric acid process are small and unlikely to
present any significant risk.
We do not believe any of these materials contain significant
concentrations of any contaminants of concern. Therefore, we propose
not to list these wastes as listed hazardous wastes under RCRA.
8. Phosphorus Pentasulfide
a. Summary. We have evaluated the wastes from the production of
phosphorus pentasulfide and propose not to list any wastes from this
process as hazardous. These wastestreams do not meet the criteria set
out at 40 CFR 261.11(a)(3) for listing a waste as hazardous. They do
not pose a substantial present or potential threat to human health or
the environment. We have identified no risks of concern associated with
the current management of these wastes.
b. Description of the phosphorus pentasulfide industry. Phosphorus
pentasulfide was produced by three facilities in the United States in
1998. Phosphorus pentasulfide is used in the manufacture of lubricating
oil additives, insecticides, ore flotation agents and specialty
chemicals.
The production of phosphorus pentasulfide begins by feeding liquid
phosphorus and liquid sulfur into a reactor. The reaction is carefully
controlled because phosphorus pentasulfide reacts violently with air
forming phosphorus pentoxide and sulfur dioxide and because toxic
hydrogen sulfide gas forms when phosphorus pentasulfide combines with
moisture on exposure to air. To reduce this hazard, the process
equipment is continuously purged with nitrogen. The phosphorus
pentasulfide vapors are distilled and the liquid from the process is
solidified, milled and packaged.
One facility operates its entire process under nitrogen blanket.
The blanketed vessels, packaging area and tote-bin wash systems are all
vented to a caustic scrubber. A second facility vents the reactor to a
caustic scrubber that removes the sulfur dioxide and hydrogen sulfide
and generates a blowdown wastestream. The facility has other scrubbers
that remove phosphorus pentoxide from the exhaust stream and reacts it
with water to produce a dilute phosphoric acid that is routed to their
acid plant. The third facility fills the reactor, condenser and
packaging equipment with nitrogen to prevent oxidation. This nitrogen
stream is scrubbed with recirculating water to remove phosphorus
pentasulfide dust. The scrubber liquor is treated and discharged.
c. Description of wastes generated by the phosphorus pentasulfide
process. We have identified nine waste categories from the production
of phosphorus pentasulfide that required assessment. These waste
categories are described briefly and in more detail in the following
subsections.
--Still residue/reactor waste is the result of impurities being left
behind when the phosphorus pentasulfide is distilled to remove
undesirables (high boilers). This residue consists of glassy
phosphates, carbon, and iron sulfide compounds and is removed from the
reactor during unit turn-around.
--Phosphorus pentasulfide scrap waste is occasionally generated during
certain maintenance operations or equipment failure. This waste can
also consist of commercial off-specification material and fugitive dust
from the packaging operation.
--Absorbents contaminated with phosphorus pentasulfide and Therminol
(benzylated ethyl benzene) are generated from cleaning up leaks during
maintenance operations. The absorbent material may be in the form of
floor dry (a granular material) or an absorbent pillow.
--Waste Therminol is a spent heat transfer product used for the vessels
and pipes to prevent freeze up of the liquid phosphorus pentasulfide.
--Scrubber water is generated as a result of a nitrogen stream being
scrubbed to remove phosphorus pentasulfide dust. The packaging
equipment is filled with nitrogen to prevent oxidation.
--Caustic scrubber water is the result of the reactor, packing and tote
bin wash system being vented to the scrubber to remove sulfur dioxide
and residual hydrogen sulfide.
--Tote bin wash water results from cleaning the shipping containers
that hold the product. The phosphorus pentasulfide residue is washed
from the returned containers with water and caustic.
--Scrap sulfur is occasionally generated when making or breaking
couplings to hoses where sulfur comes into the reaction.
One facility reported that they filter elemental phosphorus before
feeding it to the reactor. The filter solids, called phosphorus
impurities, are managed in tanks and then are piped to that facility's
phosphoric acid production furnace for phosphorus reclamation. Because
there is low potential for significant exposure from on-site storage
prior to entry in the furnace, we did not evaluate this material
further under this sector. Note that wastes generated from the
production of phosphoric acid via the dry process, including this
facility's phosphoric acid furnace, are addressed in section III.F.7 of
today's proposal.
We have organized our discussion of these wastes in terms of how
they are currently managed: characteristic wastes, wastewaters, and
scrap sulfur.
d. Agency evaluation. (1) Characteristic wastes. The RCRA Section
3007 Surveys show that a number of the phosphorus pentasulfide wastes
categories are managed as RCRA hazardous wastes at all times. These
wastes are hazardous because they exhibit the characteristics of
ignitability, reactivity or toxicity for chromium or benzene. The
facility that generates the largest volume waste, phosphorus
pentasulfide scrap waste, considers it to be a listed hazardous waste
(U189). The surveys also show that these wastes are managed as
hazardous wastes, with final disposition by incinerated in Subtitle C
units. Table III-20 summarizes our information about these wastes.
[[Page 55729]]
Table III-20.--Characteristic Wastes from Phosphorus Pentasulfide Production Disposed in Subtitle C Units
----------------------------------------------------------------------------------------------------------------
Number of
Waste category reported 1998 volume Reported hazard codes Final management
generators (MT) practices
----------------------------------------------------------------------------------------------------------------
Still residue/reactor waste...... 2 4.6 D003, D007.............. Subtitle C
incineration.
Phosphorus pentasulfide scrap 3 67.75 D001, D003, U189........ Subtitle C
waste. incineration.
Contaminated absorbent........... 1 1.2 (1996) D003.................... Subtitle C
incineration.
Waste Therminol.................. 1 1.4 D018.................... Subtitle C
incineration.
----------------------------------------------------------------------------------------------------------------
We propose not to list these four waste categories as hazardous
wastes under RCRA. All generators of these wastes already report
managing these materials as hazardous from the point of generation
through incineration because they exhibited one or more of the
hazardous waste characteristics. Again, the rules applying to
characteristic wastes adequately protect against mismanagement.
Furthermore, ninety percent of the waste are already listed as
commercial chemical product (U189). Therefore, we propose not to list
these wastes.
(2) Wastewaters. Wastewaters are generated at various points in the
process as a result of scrubbing operations and tote bin washing. As
identified by the facilities, the primary constituents of concern in
these wastewaters are phosphoric acid and hydrogen sulfide which are
readily controlled via neutralization. The management practices for
these wastewaters do not allow for the release of phosphoric acid and
hydrogen sulfide to the environment in an undiluted or unneutralized
state. Table III-21 summarizes our information on these wastewaters:
Table III-21.--Wastewaters From Phosphorus Pentasulfide Production
----------------------------------------------------------------------------------------------------------------
Number of Sequential
Waste category reported 1998 Volume Reported hazard codes management
generators (MT) practices
----------------------------------------------------------------------------------------------------------------
Process scrubber water........... 1 77,377 none.................... (1) Sewer,
(2) POTW
Caustic scrubber water........... 2 2,177 none.................... (1) Covered tanks,
(2) off-site
treatment,
(3) NPDES;
(1) Treatment in
covered tanks,
(2) POTW.
Tote bin wash water.............. 2 188 (1) D003................ (1) Covered tanks,
(2) none................ (2) off-site
treatment,
(3) NPDES;
(1) Treatment in
covered tanks,
(2) POTW.
----------------------------------------------------------------------------------------------------------------
We assessed the management practices for these wastes and
determined that no exposure pathway of concern exists. Thus, we propose
not to list these wastes as listed hazardous wastes under RCRA. The
covered tanks employed minimize potential for releases to groundwater
and air. Discharges to surface waters under NPDES are exempt from RCRA
regulation. Discharges to POTWs via the facility's common sewage line
are excluded from RCRA (40 CFR 261.4(a)(1)(ii)).
(3) Scrap sulfur. One facility reported generation of scrap sulfur
that occasionally exhibits the characteristic of TC for lead. This
sulfur is managed as hazardous in a Subtitle C incinerator. The 1998
waste volume was 0.12 MT.
We do not believe this material warrants listing as hazardous waste
and, therefore, propose not to list this waste as hazardous under RCRA.
While this waste category was reported to periodically exhibit a
characteristic, the generator always manages the waste in a Subtitle C
incinerator. We believe this management practice is likely to continue
because the cost to treat it as hazardous is low for such a small
volume wastes, and because the waste may be TC hazardous as generated.
This waste is also small volume and highly unlikely to present a
significant risk.
9. Phosphorus Trichloride
a. Summary. We have evaluated the wastes from the production of
phosphorus trichloride and propose not to list any wastes from this
process as hazardous wastes. These wastes do not meet the criteria set
out at 40 CFR 261.11(a)(3) for listing a waste as hazardous. They do
not pose a substantial present or potential threat to human health or
the environment. We have identified no risks of concern associated with
the current management of these wastes.
b. Description of the phosphorus trichloride industry. Six
facilities in the United States reported producing phosphorus
trichloride in 1997 or 1998. We are assessing wastes from the five
facilities that still produce this product.\41\
---------------------------------------------------------------------------
\41\ One facility discontinued production as of November 1999
and has no future plans to resume production of phosphorus
trichloride. This facility's wastes therefore are not included in
the following overview, but were evaluated to determine their
potential threat to human health or the environment. The details of
this facility's waste generation and management practices are
included in the ``Phosphoric Acid Listing Background Document for
the Inorganic Chemical Listing Determination.''
---------------------------------------------------------------------------
Phosphorus trichloride is used as an intermediate in the production
of a variety of chemicals. These chemicals are used to make pesticides,
herbicides, antiscaling additives, corrosion inhibitors for cooling
towers and heat exchangers, surfactants, sequestrants, and textile-
treating agents. Phosphorus
[[Page 55730]]
trichloride is used as a raw material in the production of chemicals
that are used extensively as lubricating oil additives to control
corrosion and as antioxidants and flame retardants in plastics.
Phosphorus trichloride (PCl3) is a clear, volatile
liquid with a pungent, irritating odor. Phosphorus trichloride is
produced by one basic process. Liquid phosphorus and chlorine gas are
continuously introduced into a reaction vessel. The phosphorus
trichloride vapor phase is purified in a packed column and then
liquified in a condenser. Most raw material impurities remain in the
reactor and are removed as solid waste periodically during unit
turnaround. Some facilities filter the product before shipment to
ensure there is no dirt or other particles in the final product.
A scrubber is used to collect materials from various points in the
process. For example, hydrochloric acid and phosphorus acid
(H3PO3), the hydrolysis products of phosphorus
trichloride vapors are vented to the scrubber from the reactor. Also,
phosphorus trichloride vapor generated during transfer of the product
into shipping containers is collected and vented to the same scrubber.
The wastewater generated from the scrubber(s) is commingled with
miscellaneous wastewaters (e.g., reactor washout, spent filter wash,
process area wash water) and sent for treatment. Some facilities
generate a wastewater treatment sludge from the cleanout of treatment
tanks. All of these facilities produce a variety of other products that
are outside the scope of today's rule, and they commingle the
wastewaters from PCl3 production with wastewaters from other
processes.
c. What kinds of wastes are generated by this process?. We have
organized our discussion of these wastes in terms of how they are
currently managed: characteristic wastes, wastewaters, recycled
phosphorus, and non-characteristic non-wastewaters. The wastes
generated by this process include:
--Reactor cleanout sludge consists of impurities from the elemental
phosphorus and chlorine raw materials, including high boiling
impurities such as arsenic trichloride that are retained in the
reactor. These materials are sent to Subtitle C incinerators.
--Initial washout water from reactor is generated as a result of
rinsing out the reactor after sludge removal. In one case, the reactor
is cleaned with hot water only and there is no initial sludge removal
step. These materials are treated and discharged to an POTW and under a
NPDES permit.
--Product storage tank cleanout with nonreactive phosphate ester is the
rinsate generated from cleaning the storage tank or equipment. When
this rinse is done, the rinsate is drummed for off-site disposal as a
hazardous waste.
--Product storage tank cleanout with water is generated as a result of
additional rinsing that follows phosphate ester rinsing. This
potentially acidic rinse water is sent to wastewater treatment for
neutralization.
--Spent filter washwater for product is generated as the result of
washing the spent filters used to remove dirt and particles from the
product. This wash water is mixed with other wastewaters and sent to
wastewater pretreatment.
--Process area wash water consists of pad washdown/rain water and any
spilled material collected in contained areas. This wash water is mixed
with other wastewaters and sent to wastewater pretreatment.
--Final washout water from reactor is the rinsate from additional
reactor washing after sludge removal. The one facility reporting this
rinsate commingles it with other wastewaters prior to wastewater
pretreatment.
--Caustic scrubber water consists of small amounts of sodium salts and
residual caustic. Phosphorus trichloride, acid vapors, traces of
chlorine and carbon dioxide are vented from various points of the
process. The vent releases mixed with air are scrubbed before the air
is released to the atmosphere. The spent scrubber charge is sent along
with other wastewaters to wastewater pretreatment.
--Process scrubber water consists of a weak acidic solution from
scrubbing residual gases from distillation and from various storage
tank vents.
--Spent filters for product are generated due to filtering dirt and
other particles from the product before shipment. The filters are
washed and dried before disposal.
--Wastewater treatment sludges are generated when wastewaters from the
phosphorus trichloride and other processes are biologically treated.
These sludges are only marginally derived from phosphorus trichloride
wastewaters due to commingling with large volumes of other non-
phosphorus trichloride wastewaters. The solids that are removed by
filtration are landfilled.
One facility reported recycling three secondary materials:
phosphorous storage tank sediment; phosphorous transfer water; and
absorber residual. The phosphorous storage tank sediment is generated
periodically when the phosphorus storage tanks are cleaned. Because the
material is stored in containers prior to being sent off-site for
recovery of phosphorus we found low potential for significant exposure
from on-site storage. The phosphorous recovery process is outside the
scope of the consent decree so we did not evaluate its wastes. At this
same facility, raw material phosphorous is unloaded from rail cars and
conveyed through the facility using a closed pressurized piping system
that uses water to push the phosphorous in the piping system. To unload
the phosphorous from each rail car, water is pumped into the rail car
to push the phosphorous out. Because the phosphorous/water filled rail
cars are then returned to the phosphorous manufacturers, where the
phosphorous is then recovered, we found no potential for significant
exposure, and did not evaluate this material further. The third
instance of recycling at this facility, gases vented from the product
check, storage tanks, and reflux separator are collected in an
absorber. The vapors from the absorber are captured in a caustic
scrubber and sent to wastewater treatment (see wastewaters in section
d(2) below). According to the facility, the non-vapor phosphorous
trichloride residual from the absorber is collected and piped to a non-
consent decree production process where the phosphorous trichloride is
incorporated into the non-consent decree product. Because this material
is piped from the phosphorous trichloride process to the non-consent
decree process, and there is no significant potential for exposure, we
did not evaluate this residual further.
d. Agency evaluation. We have organized our discussion of these
wastes in terms of how they are currently managed: characteristic
wastes, non-characteristic wastewaters, and non-characteristic solid
wastes.
(1) Wastes that are characteristically hazardous wastes. Many of
the phosphorus trichloride producers stated that a number of their
wastes exhibit RCRA characteristics. These wastes are hazardous wastes
because they exhibit the characteristics of ignitability, corrosivity,
reactivity or toxicity. The Toxicity Characteristic was reported for
arsenic, cadmium, chromium, lead, mercury, selenium or silver.
These characteristic wastes are subject to the applicable LDR
standards. Furthermore, these wastes are
[[Page 55731]]
ultimately disposed in Subtitle C management units or as discharges
regulated under the Clean Water Act. We believe that the applicable
Subtitle C and Clean Water Act regulations adequately protect against
mismanagement.
Table III-22 summarizes our information about these wastes.
Table III-22.--Characteristic Wastes From Phosphorus Trichloride Production
----------------------------------------------------------------------------------------------------------------
Number of Sequential
Waste category reported 1998 Volume Reported hazard codes management
generators (MT) practices
----------------------------------------------------------------------------------------------------------------
Reactor cleanout sludge.......... 4 \1\ 66 D001-004, D006-009, (1) container
D010, D011. (2) Subtitle C
incineration
Initial washout water from 4 \1\ 478 (1) D002, D004, D006, (1) off-site
reactor. D007. pretreatment,
(2) D002, D004.......... (2) POTW;
(3) D004, D007.......... (1) neutralized in
tanks,
(2) surface
impoundment,
(3) biotreat in
tank,
(4) NPDES;
(1) tank,
(2) off-site
biotreatment,
(3) NPDES
Product storage tank cleanout 1 10 D002, D003.............. (1) container
with nonreactive phosphate ester. (2) Subtitle C
incineration
Product storage tank cleanout 1 15 D002.................... (1) neutralized in
with water. tanks,
(2) NPDES
Spent filter wash for product.... 1 15 D002.................... (1) pretreatment in
tanks,
(2) NPDES
Process area wash water.......... 1 1,400 D002.................... (1) tanks,
(2) NPDES
----------------------------------------------------------------------------------------------------------------
\1\ Volumes from 1996 or 1997 are included in the totals when the wastes were not generated by a facility in
1998.
For all but one of the wastes in the above table, the generators
report managing these materials as hazardous from the point of
generation through disposal (or the point at which they become
discharges to surface water regulated under NPDES or POTW regulations).
We believe these wastes are sufficiently regulated such that
mismanagement is unlikely. Thus, we propose not to list these seven
waste categories.
One facility appears to treat initial washout reactor water in
tanks and then pass it through a nonhazardous waste surface
impoundment. (All other units used to manage this waste have RCRA
permits or are exempt from permitting.) While we have no analytical
data on the treated waste that enters the impoundment, we do not
believe this waste is likely to pose significant risk. The waste is
generated infrequently (once a year) and combined with wastewaters from
other processes. Based on information supplied by the facility, we
estimated that the washout water would be diluted at least a hundred-
fold by the daily throughput to the wastewater treatment system. Any
potential releases from the impoundment after dilution with other
wastewaters would be unlikely to result in any significant long-term
risk. Therefore, we believe that this specific waste also does not pose
significant threats to human health or the environment.
(2) Non-characteristic wastewaters. Wastewaters are generated at
various points in the process as a result of scrubbing operations,
equipment cleanup, and washing the process area. According to the data
submitted by the facility, the primary constituents of concern in these
wastewaters are hydrochloric acid and phosphorous acid, which are
readily controlled via neutralization. The management practices for
these wastewaters minimize opportunities for the release of
hydrochloric acid or phosphorous acid to the environment in an
undiluted or unneutralized state. Table III-23 summarizes our
information on these wastewaters.
Table III-23.-- Wastewaters From Phosphorus Trichloride Production
----------------------------------------------------------------------------------------------------------------
Number of Sequential
Waste category reported 1998 Volume Reported hazard codes management
generators (MT) practices
----------------------------------------------------------------------------------------------------------------
Final washout water from reactor. 1 not reported none.................... (1) pretreatment in
tanks,
(2) POTW.
Caustic scrubber water........... 3 4,236 \1\ none................... (1) pretreatment in
tanks,
(2) POTW or NPDES.
Process scrubber water........... 3 12,528 \1\ D002 (one facility)..... (1) pretreatment or
neutralized in
tanks,
(2) POTW or NPDES.
----------------------------------------------------------------------------------------------------------------
\1\ Volumes from 1996 or 1997 are included in the totals when the wastes were not generated by a facility in
1998.
We have assessed the management practices employed for these wastes
and determined that no exposure pathway of concern exists that warrants
listing. We have determined that plausible management would be
continued management in existing tank-based treatment systems. We
believe the manufacturers have made a
[[Page 55732]]
considerable investment in wastewater treatment systems using tanks and
will continue to use them. Further, we assumed that wastewater
treatment tanks retain sufficient structural integrity to prevent
wastewater releases to the subsurface (and therefore to groundwater),
and that overflow and spill controls prevent significant wastewater
releases. Thus, based on the lack of any significant likelihood of
release of the constituents to groundwater, we did not project
significant risks to groundwater from these wastes in the tank-based
wastewater treatment scenario. Furthermore, discharges to POTWs and
surface waters under NPDES are regulated under the Clean Water Act and
are exempt from RCRA Subtitle C regulation and thus were not assessed.
We also considered the possibility of air releases from tanks. For
most wastes, the constituents of concern are nonvolatile metals, making
volatilization a very unlikely pathway of release from tanks. In
addition, the facilities have installed tank covers, further reducing
the likelihood of release to the air. As a result, we did not model
releases to air from tanks from the production of phosphorus
trichloride. Thus, we propose not to list these wastewaters as
hazardous wastes under RCRA.
(3) Non-characteristic non-wastewaters. The phosphorus trichloride
sector reported two waste categories that do not routinely exhibit any
characteristic and that are often managed in Subtitle D landfills;
these wastes are summarized in Table III-24.
Table III-24.--Non-Characteristic Solid Wastes
----------------------------------------------------------------------------------------------------------------
Number of
Waste category reported 1998 Volume Reported hazard codes Management
generators (MT) practices
----------------------------------------------------------------------------------------------------------------
Spent filters for product........ 1 0.1 none.................... industrial Subtitle
D landfill.
Wastewater treatment sludges..... 4 \1\ 1,100 none \2\................ Subtitle D landfill
or Subtitle C
landfill.
----------------------------------------------------------------------------------------------------------------
\1\ Volumes from 1997 are included in the totals when the wastes were not generated by a facility in 1998.
\2\ One facility reported that this wastewater treatment sludge is occasionally characteristically hazardous for
D028 (dichloroethane), and the waste is then sent to a Subtitle C landfill. The dichloroethane is used in a
process unrelated to the phosphorus trichloride process of interest in today's proposal.
The phosphorus trichloride product is filtered to remove
PCl4 and PCl5. These compounds produce a slime on
the product and are more viscous than the product. The facility washes
the filters before sending them to disposal. The contaminants are
easily washed off because of their ready solubility in water. The spent
filters are generated in very small volumes. We are proposing not to
list them because we do not expect the washed filters to contain
significant levels of contaminants of concern.
All four of the facilities that generate wastewater treatment
sludges commingle wastewaters from PCl3 production with
wastewaters from other processes. The wastewater contribution from the
phosphorus trichloride process is very small compared to volumes of
wastewaters from the other processes. Therefore, the phosphorus
trichloride process does not contribute significant amounts of
constituents to this sludge.
We do not believe any of these materials warrant listing as
hazardous wastes from the production of phosphorus trichloride.
Therefore, we propose not to list these wastes as hazardous wastes
under RCRA in this rulemaking.
10. Potassium Dichromate
a. Summary. We evaluated the wastes from the production of
potassium dichromate and propose not to list any wastes from this
process as hazardous wastes under RCRA. These wastes do not meet the
criteria set out at 40 CFR 261.11(a)(3) for listing as hazardous. They
do not pose a substantial present or potential hazard to human health
or the environment.
b. Description of the potassium dichromate industry. Potassium
dichromate, which has a wide variety of industrial uses, was produced
by a single facility in the United States in 1998. The U.S. demand for
this chemical is very limited and has mostly been replaced by sodium
dichromate for industrial use. Any demand not met by the U.S. facility
is met by imports to U.S. distributors. Potassium dichromate is
produced by reacting chromium trioxide with potassium hydroxide. The
reactants are mixed in a reactor along with a crystal modifier. The
potassium dichromate is crystallized, sent through a centrifuge to
remove any remaining mother liquor, dried and packaged for sale. The
single waste is filtered out from the mother liquor. The mother liquor
is recycled back into the process.
c. What kinds of wastes are generated by this process? There is one
waste category generated from this process: filter solids and spent
filter media. According to data submitted by the facility, this waste
typically contains 12.5 percent chromium. The facility reports the
waste as hazardous for chromium and manages it as hazardous (D007). The
reported waste volume for 1998 was 0.6 MT. The waste is stored on-site
in drums and is shipped off-site to a commercial Subtitle C facility
for stabilization to meet the land disposal restrictions (40 CFR 268.40
and 268.48) and final disposal in a Subtitle C landfill. Because the
total chromium levels are so high, we believe this waste will always
exhibit the toxicity characteristic.
d. Agency evaluation. We propose not to list this waste as
hazardous under Subtitle C of RCRA. This waste is currently managed as
hazardous from the point of generation through ultimate disposal
because it is characteristically hazardous. The composition of the
waste is such that it is likely to always be characteristic for
chromium. The rules applying to characteristic wastes adequately
protect against mismanagement.
11. Sodium Chlorate
a. Summary. We propose not to list any wastes from the production
of sodium chlorate (NaClO3) as hazardous under Subtitle C of
RCRA. Process sludges, spent filters, wastewaters and hydrogen gas are
generated from the production of sodium chlorate. These wastes and
materials are managed in a variety of ways. After analysis of the
management practices and potential exposure pathways of these wastes
and materials, we concluded that there are no risk pathways of concern.
These wastes and materials do not meet the criteria set out at 40 CFR
261.11(a)(3) for listing as hazardous. They do not pose a substantial
present or potential hazard to human health or the environment.
b. Description of the sodium chlorate industry. There were ten
facilities producing sodium chlorate in 1999. This industry
manufactures sodium chlorate crystals and solutions from electrolysis
of a sodium chloride brine.
[[Page 55733]]
Sodium chlorate is the raw material used for the production of chlorine
dioxide, which is replacing chlorine and sodium hypochlorite to be used
as an oxidizing bleaching agent by the pulp and paper industry. The
replacement of elemental chlorine with chlorine dioxide reduces
effluent emissions of dioxin formed in the bleaching process of paper
and pulp. Approximately ninety-eight percent of sodium chlorate is used
to generate chlorine dioxide. The other important use of sodium
chlorate is as an intermediate in the production of other chlorates,
perchlorates, and chlorites.
All ten facilities use a similar process in producing sodium
chlorate. These facilities dissolve sodium chloride salt in water to
create a liquid brine. The brine is treated to remove impurities, such
as calcium carbonate and magnesium hydroxide. The treated brine is
filtered and pumped into electrolytic cells. In the cells, sodium
chloride is converted to chlorine and sodium hydroxide which further
react to form sodium chlorate and hydrogen gas. This reaction is
catalyzed by sodium dichromate. Sodium chlorate is then treated with
heat and urea to remove residual sodium hypochlorite. Sodium chlorate
is then processed further for crystallization, centrifuging, drying,
and packaging. A more complete discussion of this process and the
industry can be found in ``Sodium Chlorate Listing Background Document
for the Inorganic Chemical Listing Determination'' in the docket for
today's proposal.
c. What kinds of wastes are generated by this process? Wastes
generated from the production of sodium chlorate consist of process
sludges, spent filters and wastewaters. Based on an evaluation of
survey responses from the ten sodium chlorate producers, we divided the
wastes further into six general waste categories based on the presence
or absence of chromium and lead. The sodium chlorate industry in
general characterizes wastes that have been in contact with chromium or
lead as hazardous (D007 or D008). Chromium is introduced into the
process by the addition of sodium dichromate into electrolytic cells to
protect electrodes from corrosion and to improve product yields. The
presence of lead in the wastes results from the deterioration of anodes
that can be used in the electrolytic cells. The six waste categories
are:
--Process sludges with chromium or lead. These include electrolytic
cells sludge, product filter press sludge, and those brine treatment
sludges generated from purification where brine is formed by mixing
salts with chrome-laden wastewaters recycled from various steps of the
process.
--Process sludges without chromium and lead. These wastes include
filter press sludge or drum sludge from treatment of brine, when
recycled chrome-laden wastewater is not used in the brine dissolution
step.
--Spent filters with chromium or lead. The filters are generated at
several points in the production process, but most are generated after
the electrolysis of the brine solution when the mother liquor is
filtered to remove impurities.
--Spent filters without chromium and lead. Examples include disposable
cartridge and sock filters from treatment of brine, when recycled
chrome-laden wastewater is not used in the brine dissolution step.
--Wastewaters with chromium that are not recycled back to the process.
--Other wastewaters that do not contain chromium or lead and are not
recycled (condensate, cooling water, and ion-exchange wastewater).
In addition to these wastes, other materials are produced by all
ten facilities during the production of sodium chlorate that are piped
directly back to the production process. Scrubber waters and filtrates
are piped to on-site sodium chlorate production units for use. Because
these materials are managed prior to reuse in ways that present low
potential for releases to the environment, and because we evaluated
process wastes generated after they are reused, we do not believe that
these secondary materials present significant threats. At all ten
facilities, hydrogen gas is produced by the electrolysis units and is
either piped to on-site boilers, vented, or in one case, piped to a
compression plant where it is compressed and sold. Because the material
is a gas produced from a production unit rather than a waste management
unit and is conveyed to its destination via piping, the gas is not a
solid waste. RCRA Section 1004(27) excludes non-contained gases from
the definition of solid waste and thus they cannot be considered a
hazardous waste. (See 54 FR 50973) Because the gaseous materials are
not solid wastes when produced, we did not evaluate them further for
purposes of listing.
One facility reports generating a wastewater (sulfate solution)
from brine treatment. The wastewater is transported to an off-site
facility and used in their black liquor pulping process. The sulfate
solution is added to black liquor for use in a wood digester. The
process in the digester is outside the scope of the consent decree and
we have not evaluated risks from wastes that it produces. We note,
however, that the reuse of black liquor is excluded from regulation (40
CFR 261.4(a)(6)). The sulfate solution is stored in tanks prior to use
in the pulping process, which minimizes the potential for releases.
How Are These Wastes Currently Being Managed?
Table III-25 summarizes the six waste categories, waste
characteristics, waste volumes, and their current management practices:
Table III-25.--Waste From Sodium Chlorate Production
----------------------------------------------------------------------------------------------------------------
1998 Volume
Waste category (number of facilities) Reported Waste Codes \1\ (MT) Management practices
----------------------------------------------------------------------------------------------------------------
Process sludges with chromium or lead D001, D002, D007, D008.... 28,547 Nine facilities store the
(10). waste on site in
containers and then send
it to Subtitle C
landfills or
incinerators; one
facility decharacterizes
the waste in tanks before
managing it in on-site
surface impoundments. Two
facilities did not report
hazard codes.
[[Page 55734]]
Process sludges without chromium and none reported............. 1,886 Three facilities store the
lead (5 \2\). waste on site in
containers and then send
it off-site to municipal
Subtitle D landfills; one
facility stores the waste
on a concrete pad with
secondary containment
before applying it to an
on-site land farm; one
facility stores the waste
on site in containers and
then sends it off-site to
an industrial Subtitle D
landfill; one facility
stores the waste on site
in containers before
sending it off-site for
recycling.
Spent filters with chromium or lead (7). D001, D007, D008.......... 82.9 All seven facilities
classify the waste as
hazardous; six send the
waste to Subtitle C
landfills or
incinerators; one
facility decharacterizes
the waste on-site in
tanks, stores it in a
closed compactor, then
ships the waste off-site
to an industrial Subtitle
D landfill.
Spent filters without chromium and lead none reported............. 3.52 Three facilities store the
(4). waste on site in
containers and send it
off-site to Subtitle D
landfills. One facility
stores the waste with
process sludge in on-site
containers and then sends
it off-site to a Subtitle
C facility for
stabilization prior to
disposal in a Subtitle C
landfill.
Wastewaters with chromium that are not D002, D007................ 26,736 One facility sends the
recycled back to the process (2). wastewater to an off-site
Subtitle C facility for
treatment and disposal.
One facility combines and
treats the wastewater
with other process
wastewaters in tanks
prior to discharge to on-
site surface
impoundments.
Other wastewaters that do not contain none reported............. 10,744 \3\ Discharged via NPDES
chromium or lead and are not recycled permit or to a POTW.
(condensate, cooling water, ion-
exchange wastewater).
----------------------------------------------------------------------------------------------------------------
\1\ D001 (ignitability); D002 (corrosivity); D007 (chromium); D008 (lead).
\2\ One facility contributes more than one residuals to this waste group.
\3\ Two facilities did not report volumes of this wastewater.
d. Agency evaluation. We selected wastes from three facilities for
sampling. As described in detail in ``Sodium Chlorate Listing
Background Document for the Inorganic Chemical Listing Determination''
in the docket for today's proposal, we selected these facilities and
wastes because based on the survey information collected, we believe
that the wastes generated by these three facilities are fully
representative of the wastes generated by this industry and their
management practices.
We evaluated the characteristics and current management practices
of each of the six waste categories. The details of our evaluation
follow.
(1) Process sludge with chromium or lead.
How Is This Waste Managed?
The predominant source of process sludge with chromium or lead is
from the periodic cleanout of electrolytic cells used to convert the
brine solution to sodium chlorate. All ten facilities generate this
waste. Seven facilities classify their wastes as characteristic and
send it off-site to Subtitle C landfills or incinerators. Two
facilities do not classify their wastes as characteristic but
nevertheless send their wastes to Subtitle C landfills.
The tenth facility, located in Hamilton, Mississippi, reports this
waste to be characteristic and treats it in tanks to reduce hexavalent
chromium to the relatively stable trivalent state. The facility
commingles this sludge with wastes from the production of titanium
dioxide (TiO2) in these tanks. The treated mixture is
subsequently managed in a series of four surface impoundments, three of
which are lined with leachate collection systems. Today's proposal
separately addresses the titanium dioxide wastes that are commingled
with this sodium chlorate sludge (see section III.F.14.c.(14)).
How Was This Waste Characterized?
We collected a total of six samples to assess this waste
categories. Three samples of the sludge from electrolytic cells were
collected at two facilities where the wastes were destined for Subtitle
C treatment and disposal. These two facilities generate and manage this
waste as characteristically hazardous. These samples were part of the
record characterizing this waste category, but were not used for risk
assessment.
We collected another three samples from the Hamilton, Mississippi
facility that classifies this waste as characteristically hazardous and
treats it in tanks to remove the characteristic prior to pumping the
effluent to on-site surface impoundments. One sample (KM-SC-01)
reflects the untreated sodium chlorate sludge collected from a
dedicated sump prior to commingling with the titanium dioxide
wastewaters. The second sample (KM-SI-01) is the treated combined
wastes collected at the inlet to the surface impoundments. The
[[Page 55735]]
third sample (KM-SI-04) is the treated commingled sludge collected from
one of the on-site surface impoundments.
Table III-26, below, represents the analytical results for the
Hamilton, Mississippi samples for total and hexavalent chromium, the
primary constituent of concern. Total constituent analyses were
conducted for the untreated waste. No other toxicants in the untreated
wastewater sample (KM-SC-01) exceed the health-based levels. For the
treated waste and the sludge collected from the impoundment, total and
leaching analyses were conducted to allow us to assess potential
releases to the environment. Our analytical data shows that total
hexavalent chromium level in the treated sample (KM-SI-01) is below the
HBL for hexavalent chromium, demonstrating the effectiveness of the
treatment process. We assessed the treated commingled sludge settled in
the impoundments and found that the chromium levels did not exceed the
HBLs.
Table III-26.--Analytical Data for Sodium Chlorate
----------------------------------------------------------------------------------------------------------------
KM-SC-01 KM-SI-01 (Treated KM-SI-04 (Treated
(Untreated commingled NaC1O3 and commingled NaC1O3 and
NaC1O3 TiO2 wastes) TiO2 sludge in
wastes -------------------------- impoundment)
Constituents of concern only) -------------------------- HBL
------------- Total (mg/ SPLP (mg/
Total (mg/ kg) l) Total (mg/ SPLP (mg/
1) kg) l)
----------------------------------------------------------------------------------------------------------------
Chromium.......................... 0.99 31.1 0.05 1,140 0.05 23
Hexavalent Chromium............... 0.85 L 0.02 0.02 0.8 0.03 0.05
----------------------------------------------------------------------------------------------------------------
L: Concentration reported from analysis performed outside method recommended holding time. Value should be
considered biased low.
The total chromium concentration in the treated waste is higher
than the untreated waste due to commingling with other wastes from the
titanium dioxide production process. There are other constituents
detected in the treated commingled waste sample (KM-SI-01) that are
attributable to the titanium dioxide production process; these
constituents are assessed in section III.F.14.c.(14) of today's
proposal.
What Is EPA's Listing Rationale for This Waste?
We propose not to list this waste category. Seven facilities
consider wastes in this category to be characteristically hazardous
(for D001, D002, D007 or D008) and manage the wastes under Subtitle C
regulations. We believe that these regulations adequately protect
against mismanagement. Two facilities do not classify their wastes as
characteristic but send them to Subtitle C landfills. We also believe
that this practice adequately prevents mismanagement. The remaining
facility (which does not identify its sludges as characteristic
hazardous wastes) treats the sludge in tanks to reduce hexavalent
chromium to trivalent chromium prior to placement in on-site surface
impoundments. We found that the waste did not pose risks during
treatment because there are no exposure pathways of concern for the on-
site treatment tanks. The wastes are treated in concrete tanks with
secondary containment which minimize potential releases to groundwater.
We also are not concerned with potential air releases from these tanks
as neither volatile contaminants nor airborne particulates are likely
to be present in the wastes. As discussed above, the primary
constituent of concern in this waste is hexavalent chromium, which is
treated to form relatively stable trivalent chromium. The physical form
of the wastes (i.e., sludge with high water content) eliminates the
potential for a significant release of airborne particulates.
Furthermore, our analytical data show that the waste, after treatment,
does not contain any constituents of concern at levels exceeding
health-based levels.
(2) Process sludge without chromium and lead.
How Is This Waste Managed?
This sludge is produced as part of the initial purification of the
brine solution. Five facilities report generating this type of waste
and managing it as nonhazardous. Four facilities manage the waste in an
on-site land farm, off-site municipal Subtitle D landfills, and an
industrial Subtitle D landfill. One facility ships their waste off-site
for recycling.
We collected a total of four samples of this waste category from
two facilities. Two of the four samples (HT-SN-01 and EC-SN-03) are
representative of wastes that are land disposed. The other two samples
(EC-SN-01 and EC-SN-02) are representative of wastes that are generally
recycled and occasionally also landfilled. Table III-27 identifies the
constituents of concern that we found to be present in the waste at
levels exceeding their respective HBLs and/or soil screening levels.
Table III-27.--Analytical Results for Sodium Chlorate Process Sludge Without Chromium and Lead (ppm)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
HT-SN-01 EC-SN-03 EC-SN-01 EC-SN-02
Parameter ------------------------------------------------------------------------------------------------------------------------ HBL \1\SSL
Total TCLP SPLP Total TCLP SPLP Total TCLP SPLP Total TCLP SPLP
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Arsenic............................................. 14.3 \2\0.03 0.05 5 0.005 0.05 5 0.005 0.05 5 0.005 0.05 0.0007 5.2
Cadmium............................................. 27.4 0.05 0.05 5 0.05 0.05 5 0.05 0.05 5 0.05 0.05 0.0078 4.3
Chromium............................................ 57.3 0.05 0.05 15.3 0.05 0.05 5 0.05 0.05 10.1 0.05 0.05 23 37
Copper.............................................. 17.2 0.25 0.05 15.3 0.05 0.05 5 0.25 0.05 5.3 0.25 0.05 1.3 17
Lead................................................ 14.8 0.024 0.03 139 0.03 0.03 19.3 0.12 E 0.001 34.9 0.05 E 0.002 E 0.015 400*
Manganese........................................... 69.2 0.08 0.05 238 4.5 0.05 125 0.5 0.05 51.9 0.7 0.05 0.73 330
Mercury............................................. 0.5 L 0.002 0.0002 0.1 0.002 0.0002 0.1 0.002 0.0002 0.1 0.002 0.0002 0.0047 24*
Nickel.............................................. 7.4 0.2 0.05 12.1 0.4 0.05 5 0.2 0.05 5 0.2 0.05 0.31 13
Silver.............................................. 1.1 0.1 0.01 1 0.1 0.01 1 0.1 0.01 1 0.1 0.01 0.078 400*
Zinc................................................ 111 2 0.5 279 10.6 0.5 50 2 0.5 50 2 0.5 4.7 48
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ SSL: Soil Screening Level based on geometric mean background concentration (mg/kg) in soils in conterminous U.S. or soil ingestion HBL (marked *).
\2\ Results are less than the typical laboratory reporting limit, but are greater than the calculated instrument detection limit.
E: Analysis performed outside recommended holding time. Reported value should be considered as estimated.
[[Page 55736]]
What Management Scenarios Did We Aassess?
We evaluated wastes managed under the four identified management
scenarios: on-site land farm, municipal Subtitle D landfill, industrial
Subtitle D landfill, and recycling.
Land farm scenario. One facility reports managing 37 MT/year of
this waste in an on-site permitted land farm. EPA previously assessed
this same land farm as part of the chlorinated aliphatics listing
determinations (see proposed rule at 64 FR 46475, August 25, 1999).
Today's assessment of sodium chlorate waste placed in the same unit is
based on our earlier modeling of this unit for a waste from the
production of chlorinated aliphatics (EDC/VCM sludges).
In assessing this management scenario, we first compared the total
constituent concentrations of all four record samples to background
soil concentrations. The following metals exceeded this screening
criteria: arsenic, cadmium, chromium, copper, lead, mercury, silver,
and zinc. We then used the metal modeling results generated from the
chlorinated aliphatics listing determination to calculate the
proportional sodium chlorate risk. The calculated modeling results of
arsenic, cadmium, hexavalent chromium, and zinc for the same land farm
are all below a hazard quotient (HQ) of 1 and 10-6 risk
thresholds for the land treatment scenario. Finally, we compared the
total concentrations of copper, lead, mercury, and silver of all
samples to the soil ingestion HBL because these constituents were not
assessed in the chlorinated aliphatics risk analyses. The maximum total
concentrations of lead, mercury, and silver are well below the soil
ingestion HBL, and the maximum total concentration of copper in this
waste (i.e., 17.2 mg/kg) is very close to the soil ingestion HBL (i.e.,
17 mg/kg). We believe that after mixing with soil in the land
application unit, the copper concentration in the unit will be even
lower. We do not believe this waste poses risk via volatilization to
the air pathway because it does not contain any significant toxic
volatile chemicals. In addition, the comparison described above for
this unit, where we determined that the detected waste constituents are
present in the waste at levels below or very close to the soil
ingestion levels, suggests that any wind blown dust from the unit
should not pose risk at levels of concern.
Based on our analysis, we conclude that the waste does not present
a substantial risk to human health or the environment when land
applied.
Landfill scenarios. Three facilities manage their wastes in
municipal Subtitle D landfills and one facility manages its waste in an
industrial Subtitle D landfill.
We used the SPLP results of all four relevant samples to evaluate
the industrial Subtitle D landfill management scenario. We found that
the waste poses no substantial present or potential hazard to human
health and the environment when managed in an industrial Subtitle D
landfill because the SPLP leachate concentration of all constituents of
the four samples of this waste category are below their respective
HBLs.
We used the TCLP results of all four relevant samples to assess the
municipal Subtitle D landfill scenario. We modeled all three volumes
reported being sent to municipal Subtitle D landfills. We focused our
assessment on the geological regions in the northwestern and
southeastern areas of the country because of the locations of the
facilities and the landfills currently being used. The constituents we
modeled are arsenic, lead, manganese, nickel, and zinc. The details
regarding our modeling inputs and assumptions are provided in ``Sodium
Chlorate Listing Background Document for the Inorganic Chemical Listing
Determination'' and ``Risk Assessment for the Listing Determinations
for Inorganic Chemical Manufacturing Wastes' in the docket for today's
proposal. The results of our risk assessment are summarized below in
Table III-28.
Table III-28.--Groundwater Pathway Risk Assessment Results for Process Sludge Without Chromium and Lead
--------------------------------------------------------------------------------------------------------------------------------------------------------
Arsenic Manganese Nickel Zinc
--------------------------------------------------------------------------------------------------------------------------
Percentile Adult cancer Child cancer
risk risk Adult HQ Child HQ Adult HQ Child HQ Adult HQ Child HQ
--------------------------------------------------------------------------------------------------------------------------------------------------------
90th......................... 3E-08......... 2E-08......... 2E-04......... 4E-04........ 2E-06........ 3E-06........ 5E-08........ 1E-07
95th......................... 2E-07......... 2E-07......... 6E-04......... 1E-03........ 2E-05........ 3E-05........ 5E-06........ 1E-05
--------------------------------------------------------------------------------------------------------------------------------------------------------
Based on these risk assessment results, we conclude that process
sludge without chromium and lead does not pose a substantial present or
potential hazard to human health and the environment when managed in
municipal Subtitle D landfills. We calculated hazard quotients for non-
carcinogenic compounds (lead, manganese, nickel, and zinc), and all of
these were well below a value of one. We found no adult or child cancer
risk for arsenic in excess of 1E-06 at the 95th percentile. Based on
these results we conclude that this waste does not pose risk to human
health and the environment. For a more complete description of this
analysis, see ``Risk Assessment for the Listing Determinations for
Inorganic Chemical Manufacturing Wastes'' in the docket for this
proposal.
Recycling scenario.--One facility ships their wastes to an off-site
facility for reuse. The material is added to mined gypsum used to
retard the setting of concrete. We assessed this use because it
involves land placement, with higher likelihood of releases to the
environment. Two samples of this waste category were collected from the
facility that produces and manages this waste in such a fashion. We
compared this use to a less protective landfarming scenario, which we
modeled, and found no risk of concern. The volume of the waste is quite
small (1%) when compared to the volume of mined gypsum used by the off-
site facility. We believe that the constituent concentrations in the
final cement product would be even lower due to mixing with other
materials.
What Is EPA's Listing Rationale For This Waste?
Based on our assessments of the four management scenarios (on-site
land farm, municipal Subtitle D landfill, industrial Subtitle D
landfill, and recycling), we found that the wastes do not present a
substantial risk to human health or the environment. Therefore, we
propose not to list these wastes.
(3) Spent filters with chromium or lead.
[[Page 55737]]
How Is This Waste Managed?
Spent filters are generated at several points in the production
process but most are generated after the electrolysis of the brine
solution. Seven facilities report generating this waste. Six of the
seven facilities report this waste to be characteristic and ship it to
off-site Subtitle C landfills or incinerators. The seventh facility
generates a very small volume of D007 waste that is acid-washed and
decharacterized (to meet UTS) before being landfilled at an off-site
industrial Subtitle D landfill.
How Was This Waste Characterized?
We collected one sample of the spent filter that was
decharacterized prior to being sent to an industrial Subtitle D
landfill. We did not sample any of the six facilities that already
adequately managed the waste under Subtitle C regulations. Table III-29
presents the analytical results for the total and leaching analyses of
the decharacterized spent filter sample (KM-FB-01) for arsenic, lead,
total chromium, and hexavalent chromium. Chromium and lead are the two
primary constituents of concern in wastes of this category. The sample
was not collected from the facility that uses anodes with lead coating,
thus lead was not present in this sample. Arsenic was the only
constituent detected in the SPLP analysis of this sample at levels
exceeding the HBL.
Table III-29.--Analytical Results for Spent Filters With Chromium (KM-FB-01)
----------------------------------------------------------------------------------------------------------------
Drinking water
Parameter Total (mg/kg) TCLP (mg/l) SPLP (mg/l) HBLs (mg/l)
----------------------------------------------------------------------------------------------------------------
Arsenic......................................... 0.5 0.5 \1\0.005 0.0007
Chromium........................................ 41.0 0.05 0.05 20
Hexavalent Chromium............................. 16.8 \2\NA \2\0.022 0.05
Lead............................................ 5 0.5 0.03 0.015
----------------------------------------------------------------------------------------------------------------
\1\ Results are less than the typical laboratory reporting limit, but are greater than the calculated instrument
detection.
\2\ NA Not applicable. Typical TCLP leaching solution is not suitable for leachable hexavalent chromium because
most (or all) hexavalent chromium in TCLP waste leachates were converted to trivalent chromium. The leach test
for hexavalent chromium was modified by replacing the typical (TCLP/SPLP) solution with deionized water.
What Is EPA's Listing Rationale For This Waste?
As previously noted, six of the seven generators of this waste
report managing their wastes in Subtitle C facilities as
characteristically hazardous from the point of generation through
ultimate disposal. We did not conduct risk assessment on wastes
identified as hazardous wastes and managed in Subtitle C facilities
because listing would not provide any significant incremental control
of wastes already managed under Subtitle C. We evaluated the small
volume waste (i.e., 2.3 MT/yr) generated by the seventh facility that
decharacterizes its waste before landfilling in an industrial Subtitle
D landfill.
Because the volume of this waste is relatively small, we used a
screening analysis (described in section III.E.3) to screen the
potential risk to groundwater associated with landfilling this waste.
We found that the SPLP data for arsenic screens out because the volume
of the waste generated by the facility is insufficient to release
arsenic at levels of concern. For a more complete description of this
analysis, see ``Risk Assessment for the Listing Determinations for
Inorganic Chemical Manufacturing Wastes'' in the docket for this
proposal.
Our analytical data demonstrate that the waste is effectively
decharacterized and does not pose risks warranting listing for
chromium, the primary constituent of concern in this waste. The result
of the screening analysis for arsenic, the only constituent present in
the waste's leachate at levels exceeding the HBL, shows that the
arsenic in this waste does not pose risk to human health and the
environment. Therefore, we propose not to list spent filters with
chromium.
(4) Spent filters without chromium and lead.
How Is This Waste Managed?
This residual is usually generated as part of the initial brine
purification steps, where impurities are removed from the brine
solution, and from filtering of product during packaging. Four
facilities report generating this type of waste. Two of these four
facilities manage their wastes as nonhazardous in municipal Subtitle D
landfills. One facility manages its waste as nonhazardous in an
industrial Subtitle D landfill. One facility sends their spent filters
along with process sludge off-site to a Subtitle C facility for
stabilization prior to disposal in a Subtitle C landfill. These wastes
are generated in very small volumes.
How Was This Waste Characterized?
We collected two samples (HT-FB-01 and HT-FB-02) from one facility.
These two samples are representative of wastes in this category that
are land disposed. We found that antimony, arsenic, boron, hexavalent
chromium, and lead in the TCLP or SPLP waste leachates exceeded their
HBLs. We also found that cadmium was not detected in the leachates at a
detection level of six times higher than its HBL. The detection limit
was high due to dilution to minimize sample matrix interferences.
Information on constituents of concern is summarized in Table III-30.
Table III-30.--Analytical Results for Spent Filters Without Chromium or Lead
--------------------------------------------------------------------------------------------------------------------------------------------------------
HT-FB-01 HT-FB-02
Parameter ------------------------------------------------------------------------------------------------ HBL (mg/l)
Total (mg/kg) TCLP (mg/l) SPLP (mg/l) Total (mg/kg) TCLP (mg/l) SPLP (mg/l)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Antimony................................ 34.1 0.018 0.005 5 0.012 0.005 0.006
Arsenic................................. 7.3 0.014 0.003 5.3 0.005 0.005 0.0007
Boron................................... 50 6.1 0.05 50 0.67 0.5 1.4
Cadmium................................. 22.5 0.05 0.05 5 0.05 0.05 0.008
Cr, +6.................................. 0.8 NA 0.02 2.8 L NA 0.19 L 0.05
[[Page 55738]]
Lead.................................... 8.7 0.024 0.06 7.1 0.020 0.012 0.015
--------------------------------------------------------------------------------------------------------------------------------------------------------
L: Concentration reported from analysis performed outside required holding time. Value should be considered biased low.
What Management Scenarios Were Assessed?
We modeled both the industrial (0.6 MT/year) and municipal (2.8 MT/
year) landfill scenarios, based on the reported management practices.
We used the SPLP leachate concentrations to evaluate the industrial
landfill scenario. The constituents of concern that exceeded their
respective HBLs in the SPLP results were arsenic, hexavalent chromium,
and lead. We evaluated these constituents using the de minimis volume
screening analysis, as described in section III.E.3 of today's
proposal. The analysis suggests that hexavalent chromium and lead are
not of concern. We then modeled arsenic using our standard groundwater
model for the industrial landfill scenario.
We used the TCLP leachate concentrations to evaluate the municipal
landfill scenario. Using the de minimis volume analysis, we screened
out boron, hexavalent chromium, and lead. We then conducted full
groundwater modeling for the municipal scenario for antimony, arsenic,
and cadmium.
What Are the Results of EPA's Risk Assessment for This Waste When
Managed in an Industrial Subtitle D Landfill?
Our risk assessment results for the industrial landfill scenario,
summarized below in Table III-31, suggest that the only constituent of
concern that required modeling (arsenic) does not pose a substantial
present or potential hazard to human health and the environment. We
found no arsenic cancer risk in excess of 1E-08 at the 95th percentile
for either adult or child exposure scenarios. Therefore, we believe
that this waste when managed in industrial Subtitle D landfills clearly
does not warrant listing. For a more complete description of this
analysis, see ``Risk Assessment for the Listing Determinations for
Inorganic Chemical Manufacturing Wastes'' in the docket for this
proposal.
Table III-31.--Risk Results for Filters Without Chromium and Lead--
Industrial Subtitle D Landfill Scenario
------------------------------------------------------------------------
Arsenic
Percentile --------------------------------------
Adult cancer risk Child cancer risk
------------------------------------------------------------------------
90th............................. 1E-09 8E-10
95th............................. 5E-09 4E-09
------------------------------------------------------------------------
What Are the Results of EPA's Risk Assessment for This Waste When
Managed in Municipal Subtitle D Landfills?
Our risk assessment results for the municipal landfill scenario,
summarized below in Table III-32, suggest that the three constituents
of concern (antimony, arsenic, and cadmium) do not pose a substantial
present or potential hazard to human health and the environment. The
hazard quotients, for both the adult and child exposure scenarios, of
antimony are less than 0.01 at the 95th percentile, and of cadmium, are
less than 0.001 at the 95th percentile. We found no arsenic cancer risk
in excess of 1E-08 at the 95th percentile for either adult or child
exposure scenarios. Therefore, we believe that this waste when managed
in municipal Subtitle D landfills does not warrant listing. For a more
complete description of this analysis, see ``Risk Assessment for the
Listing Determinations for Inorganic Chemical Manufacturing Wastes'' in
the docket for this proposal.
Table III-32. Risk Results for Filters Without Chromium and Lead Municipal Subtitle D Landfill Scenario
--------------------------------------------------------------------------------------------------------------------------------------------------------
Antimony Arsenic Cadmium
Percentile ----------------------------------------------------------------------------------------------------------------------
Adult HQ Child HQ Adult cancer risk Child cancer risk Adult HQ Child HQ
--------------------------------------------------------------------------------------------------------------------------------------------------------
90th............................. 5E-04 1E-03 5E-10 4E-10 3E-05 6E-05
95th............................. 2E-03 4E-03 5E-09 4E-09 1E-04 3E-04
--------------------------------------------------------------------------------------------------------------------------------------------------------
(5) Wastewaters with chromium that are not recycled back to the
process.
How Is This Waste Managed and How Is It Characterized?
Two facilities report generating this wastewater and characterize
it as hazardous (D002 and D007). One facility generates 11 MT per year
of this wastewater from its on-site laboratory testings of the
electrolyte in the electrolytic cells, the excess caustic from the
hydrogen purification step, and the wastewater from the production of
sodium chlorate crystals. The facility stores the wastewater on-site in
closed tanks before sending it off-site to a hazardous waste facility
for treatment and disposal. The other facility generates 26,725 MT per
year of this wastewater from acid washing filters and anodes to remove
buildup of trace metals on the surface. The facility combines the
wastewaters with the wastewaters from its titanium dioxide production
process and treats the commingled wastewaters in tanks. The treated
wastewater is then discharged to on-site surface impoundments.
[[Page 55739]]
What Is EPA's Listing Rationale for This Waste?
One facility identifies the waste as hazardous and manages it in
accordance with Subtitle C regulations. We believe that applicable
Subtitle C regulations adequately protect against mismanagement, and we
did not investigate it further.
For the other facility, in Hamilton, Mississippi, we evaluated its
combined wastewaters and solids as described above in the ``process
sludges with chromium or lead'' category. Today's proposal separately
addresses the titanium dioxide wastes that are commingled with this
sodium chlorate waste. We propose not to list these wastes.
(6) Other wastewaters that do not contain chromium or lead and are
not recycled.
How Is This Waste Managed?
There are other wastewaters generated from several points of the
process, including process condensate, cooling waters, and ion-exchange
wastewater. Four facilities reported generating these wastewaters. Two
facilities generate process condensates from condensing water vapor
from their crystalizers, steam jets, or pad water evaporator. Both
facilities store their process condensates in closed tanks. One
facility neutralizes the condensate prior to discharging it to an NPDES
permitted outfall. The other facility does not treat the condensate,
but tests to ensure it meets its State Pollutant Discharge Elimination
System permit prior to discharge to a river. One facility generates
wastewater from regeneration of the ion-exchange unit that is used for
purification of the brine. The wastewater is collected in a tank for pH
neutralization before it is discharged to a POTW. One facility
generates wastewater from cooling tower blowdown, chemical storage tank
scrubber pad, hydrogen scrubber pad, and water demineralization area.
These wastewaters are piped to its on-site NPDES facility to be
processed and discharged.
What Is EPA's Listing Rationale for This Waste?
We propose not to list these wastewaters as hazardous. We evaluated
these wastewaters that are stored and treated in tanks or in a NPDES
permitted facility. We found that these wastewaters do not pose risks
warranting regulation during treatment because there are no exposure
pathways of concern. The wastewater treatment tanks and the wastewater
treatment facility provide sufficient structural integrity and have
secondary containment areas to minimize potential releases to
groundwater. We are unlikely to find potential air releases from these
tanks or the permitted facility as neither volatile contaminants nor
airborne particulates are likely to be present in these wastewaters.
12. Sodium Dichromate
a. Summary. We have evaluated the wastes, waste management
practices, and potential risk exposure pathways associated with the
sodium dichromate production processes and propose not to list any
wastes from this industry as hazardous wastes under Subtitle C of RCRA.
These wastes do not meet the criteria listed under 40 CFR 261.11(a)(3)
for listing a waste as hazardous. They do not pose a substantial
present or potential threat to human health or the environment. We have
identified no risks of concern associated with the current management
of these wastes. Note that certain wastes from this sector are exempt
mineral processing wastes which are not within the scope of today's
listing proposal.
b. Description of the sodium dichromate industry. Two facilities in
the United States produce sodium dichromate; one in North Carolina and
one in Texas. Both facilities sell their product on the open market in
addition to using the material as a feedstock for various manufacturing
processes on-site. The majority of sodium dichromate is used as a
feedstock for the production of chromic acid. It is also used in a wide
variety of other uses. For more detailed information concerning this
industry, see ``Sodium Dichromate Listing Background Document for the
Inorganic Chemical Listing Determination'' in the docket for today's
proposal.
The two sodium dichromate production facilities use somewhat
different manufacturing processes and generate somewhat different
wastes. Both facilities use imported chromite ore as their primary
feedstock. They dry and grind the ore and feed it into a roasting kiln
or hearth with other materials such as soda ash, lime, and sodium
hydroxide. The facilities roast, then quench and leach the ore with
water, producing sodium chromate solution and solid ore residues. Both
facilities return the ore residues to the manufacturing process for
further roasting and leaching. The facilities purify the resulting
sodium chromate solution product stream by adjusting its pH, treating
it with sodium carbonate, and, at the Texas facility, sodium
dichromate, and filtering out the resulting solid impurities.
The two facilities' processes diverge significantly at this point.
At the Texas facility, the sodium chromate solution is either
crystallized and sold or processed electrolytically to convert the
sodium chromate to sodium dichromate. The electrolytic cell system also
produces sodium hydroxide solution which, the facility reports, they
sell. The North Carolina facility converts the sodium chromate solution
to sodium dichromate through acidification, and the sodium dichromate
is then partially evaporated. The acidification process also produces
sodium sulfate and lower purity sodium sulfate ``saltcake,'' both of
which the facility sells. The sodium dichromate is then either used in
liquid form or further evaporated to produce a crystalline product.
c. How does the Bevill Exclusion apply to wastes from the sodium
dichromate manufacturing processes? The sodium dichromate manufacturing
facilities produce two types of residuals which are eligible for the
Bevill exemption once disposed: beneficiation wastes (See 40 CFR
261.4(b)(7)(i)) and mineral processing wastes referred to as treated
residue from roasting/leaching of chromium ore (see 40 CFR
261.4(b)(7)(ii)(N)).
Under the Bevill exemption, any wastes generated from beneficiation
of ores, such as crushing, mixing, and milling, are Bevill exempt. Both
facilities beneficiate ore by drying and grinding chromite ore and
mixing the ore with other ingredients prior to placement in the
roasting kiln and generate air pollution control dusts from these
processes. However, the residuals from these processes, which would be
Bevill exempt, are not disposed of but rather captured and returned to
the process from which they originated for chromium recovery.
In terms of when beneficiation stops and mineral processing starts,
EPA determined in 1989 that the roasting/leaching of chromium ore to
produce sodium chromate is mineral processing rather than
beneficiation. 54 FR 36592 (September 1, 1989) stated:
``A specific exception to the above categorization system
applies when the roasting/leaching sequence produces a final or
intermediate product that does not undergo further beneficiation or
processing steps (e.g., the leach liquor serves as an input to
inorganic chemical manufacturing). In this type of situation, the
Agency believes that the operation is most appropriately considered
a processing, rather than a beneficiation, operation. In the context
of this rulemaking, one candidate Bevill waste (roast/leach ore
residue from primary chrome ore processing) is affected by this
distinction; EPA believes that this material is clearly a waste from
[[Page 55740]]
processing, rather than beneficiation, of an ore or mineral.''
The wastes generated after mineral processing begins are not Bevill
exempt unless and until they become treated residue from the roasting/
leaching of chromium ore as specified in 40 CFR 261.4(b)(7)(ii)(N). The
wastes eligible for the exclusion, once they are treated, are referred
to later in this preamble and associated background documents as spent
post-leach, spent post-neutralization ore residue, and waste heat
boiler washout. These wastes are generated from roasting and leaching
(including precipitation and filtration to remove the resulting
impurities) of chromite ore. Both facilities generate these wastes,
treat them in on-site treatment systems, and dispose of them in on-site
surface impoundments. Note that in the January 23, 1990 Federal
Register, EPA stated that the Bevill exemption applies to ``only those
solids which are entrained in the slurry as it leaves the treatment
facility and which settle out in disposal impoundments.''
Wastes generated following the roasting/leaching processes to
produce sodium chromate for sodium dichromate production are not Bevill
exempt because they are not from the roasting/leaching of chromite ore.
Wastes generated at these facilities that are not Bevill exempt include
sodium chromate evaporation unit wastewaters (Texas facility), sodium
dichromate evaporation unit wastewaters (Texas facility), caustic
filter sludge (Texas facility), and salt cake drier scrubber wastewater
(North Carolina facility).
As described below, both facilities in the sodium dichromate
manufacturing industry commingle wastes during the treatment process,
ultimately producing a commingled treatment residue which is a mixture
of Bevill exempt wastes and wastes which do not qualify for the Bevill
exemption. In general, the majority of these mixtures consist of Bevill
exempt wastes. Mixing Bevill exempt wastes with non-hazardous wastes
does not affect the regulatory status of the Bevill wastes, but it also
does not conversely extend Bevill exempt status to the non-hazardous
wastes in the mixture (see 63 FR 28595). Therefore, in this rulemaking
we have addressed that portion of the treatment residue mixture which
derives from wastes which do not qualify for the Bevill exemption. In
addition, in general, if any of the non-Bevill wastes exhibit a
characteristic and is mixed with the Bevill wastes, the entire mixture
may become subject to Subtitle C based on the Bevill mixture rule (See
40 CFR 261.3(a)(2)).
d. What kinds of wastes are generated by these processes? Table
III-33 below briefly lists the facility-reported residuals from the
sodium dichromate manufacturing industry, total industry residual
volumes generated in 1998, RCRA hazard codes, and residual management
practices.
Table III-33.--Sodium Dichromate Production Residuals
----------------------------------------------------------------------------------------------------------------
Sequential management
Waste category 1998 volumes (MT) Reported waste codes practices
----------------------------------------------------------------------------------------------------------------
North Carolina Facility
----------------------------------------------------------------------------------------------------------------
Residuals commingled in spent ore
residue treatment unit \1\:
Spent post-neutralization ore 146,937.................. D007.................... Sent on-site to tank-
residue (Bevill exempt after based spent ore residue
treatment). treatment unit with
NPDES permitted
discharge.
Spent post-leach ore residue 25,930................... D007.................... Sent on-site to tank-
(Bevill exempt after based spent ore residue
treatment). treatment unit with
NPDES permitted
discharge.
Saltcake drier scrubber 13,851................... D007.................... Sent on-site to tank-
wastewater. based spent ore residue
treatment unit with
NPDES permitted
discharge.
Waste heat boiler washout 70....................... D007.................... Sent on-site to tank-
(Bevill exempt after based spent ore residue
treatment). treatment unit with
NPDES permitted
discharge.
Residuals disposed of on-site:
Reduced chromium treatment 129,503.................. None.................... Sent to on-site
residues (commingled Bevill industrial Subtitle D
exempt and non-exempt disposal unit.
residues).
Commingled treated 920,161.................. None.................... Passed through sand
wastewaters (commingled filters then discharged
Bevill exempt and non-exempt directly under NPDES
residues). permit or sent to on-
site industrial
Subtitle D disposal
unit.
Residuals disposed of off-site:
Chromium-contaminated 67....................... D007.................... Stored in on-site roll-
filters, membranes, and off bin before off-site
other plant waste. treatment and landfill
disposal at Subtitle C
facility.
Spent sand filter sands 21.7 (1997).............. None.................... Stored in on-site drums
(commingled Bevill exempt or roll-off bins before
and non-exempt residues). disposal in off-site
industrial Subtitle D
landfill.
----------------------------------------------------------------------------------------------------------------
Texas Facility
----------------------------------------------------------------------------------------------------------------
Residuals commingled in spent ore
residue treatment unit:
Spent post-neutralization ore 60,000................... D007.................... Sent to on-site,
residue (Bevill exempt after covered, tank-based,
treatment). spent ore residue
treatment unit with
NPDES permitted
discharge.
Caustic filter sludge........ 80....................... D002.................... Sent to on-site,
covered, tank-based,
spent ore residue
treatment unit with
NPDES permitted
discharge.
Residuals commingled in
wastewater treatment unit \2\:
Sodium dichromate evaporation 2,500....... None.................... Sent to on-site, tank-
unit wastewater. based wastewater
treatment unit with
NPDES permitted
discharge.
Sodium chromate evaporation 300.......... None.................... Sent to on-site, tank-
unit wastewater. based wastewater
treatment unit with
NPDES permitted
discharge.
[[Page 55741]]
Residuals disposed of on-site:
Reduced chromium treatment 60,000................... None.................... Sent to on-site
residues from spent ore industrial Subtitle D,
residue treatment unit double-lined surface
(commingled Bevill exempt impoundment for
and non-exempt residues). dewatering and
disposal. Impoundment
has NPDES permitted
outflow.
Reduced chromium treatment 30,000 (1999) None.................... Sent to on-site
residues from wastewater industrial Subtitle D,
treatment unit (commingled double-lined surface
Bevill exempt and non-exempt impoundment for
residues). dewatering and
disposal. Impoundment
has NPDES permitted
outflow.
Commingled treated 186,515.................. None.................... Sent to on-site
wastewaters (commingled industrial Subtitle D
Bevill exempt and non-exempt surface impoundment,
residues). filtered through sand
filters, then
discharged directly
under NPDES permit.
Residuals disposed of off-site:
Process filters and 24....................... D007.................... Stored in on-site roll-
membranes, baghouse bags, off box before
chromium-contaminated empty treatment and landfill
containers, and other plant disposal at Subtitle C
wastes. facility.
Spent sand filter sands 2 MT once None.................... Placed in on-site non-
(commingled Bevill exempt every two years. hazardous soil waste
and non-exempt wastes). bin and then disposed
of in off-site
industrial Subtitle D
landfill.
----------------------------------------------------------------------------------------------------------------
\1\ Remediation well water, cooling tower blowdown, and stormwater are also treated in this unit. These
materials are beyond the scope of this listing determination.
\2\ Stormwater and remediation well water are also treated in this unit. Contaminated media are not within the
scope of this listing determination.
In addition to these wastes, the sodium dichromate manufacturers
produce residuals which are either piped back to the production process
or sold for use in other manufacturing processes. Air pollution control
devices capture materials that are returned to their units of origin or
to other manufacturing process units. At the North Carolina facility,
ore residue washwaters and calcium carbonate residuals are returned to
the production process for chromium recovery. Chromium-bearing solution
from the saltcake purification process is directly reused in the
roasted ore quench, leach and filter process. At the Texas facility,
chromium-containing residuals from scrubbers on the hearth and on the
sodium chromate and dichromate evaporation/crystallization units are
reused in the hearth kiln and quench tank units. Because these
materials are reused in production units in ways that present low
potential for release, and because we evaluated process wastes
generated after the secondary material is reinserted into the process,
we do not believe that these materials present significant risk.
The North Carolina facility also produces for sale sodium sulfate
``saltcake'' and purified sodium sulfate anhydrous from the sodium
dichromate production process. The Texas facility sells hydroxide
solution from their sodium dichromate production process. We found no
information indicating that the facilities which purchase these
materials burn them for energy recovery or incorporate them into
products that are used on the land (use constituting disposal). Since
these processes are outside the scope of the consent decree we did not
evaluate any of these materials further. We did however, evaluate some
residuals produced on-site at the North Carolina and Texas facilities
during the preparation of the materials that are sold. See the
discussions in the sections below of salt cake drier scrubber water and
caustic filter sludge. Finally, the North Carolina facility produces
some off-specification product, which it reinserts into the sodium
dichromate manufacturing process. Off-specification product, when
reinserted without reclamation into the process from where it
originated, is not a solid waste. See the ``Sodium Dichromate Listing
Background Document for the Inorganic Chemical Listing Determination''
for more details on these residuals.
e. Waste characterization and Agency evaluation. Chromium is the
primary constituent of concern in the wastes from both facilities.
Chromium occurs in several production wastes at high levels, in some
cases exceeding the TC level (5.0 mg/L) in TCLP leachate samples. These
wastes are coded as hazardous (D007). Both facilities treat some of
their D007 wastes on-site and send other D007 wastes off-site for
treatment and disposal at permitted Subtitle C hazardous waste
facilities. Various other wastes which fall below D007 regulatory
levels are either treated on-site or sent off-site for disposal. No
other constituents of concern were reported to be present in the wastes
at levels of concern.
We propose not to list any of the wastes from the sodium dichromate
manufacturing industry. Many wastes from this industry are Bevill
exempt once treated, and therefore not within the scope of the consent
decree requirements. Other wastes are characteristically hazardous and
are managed at permitted Subtitle C facilities off-site. Some wastes
did not exhibit constituents at levels of concern for purposes of a
listing given the nature of their management and disposal. The main
constituent of concern, chromium, is treated on-site for many of the
wastes.
Several wastes from each of the facilities are disposed of in a
treated form, rather than an as-generated form. In general, we focused
our evaluation on the treated form of wastes because it is ultimately
only the treated wastes which are disposed.
The sections below describe how wastes are generated and managed at
the two sodium dichromate manufacturing facilities, each with its own
production process, and our rationale for proposing not to list the
wastes. We solicit comments on the proposed listing decisions described
below.
(1) North Carolina Facility.
(a) Residuals Commingled in Spent Ore Residue Treatment Unit. The
North Carolina facility commingles and treats several characteristic
wastes from sodium dichromate manufacturing in an on-site, tank-based
treatment unit at the North Carolina facility. These four sodium
dichromate manufacturing wastes are:
--Waste heat boiler washout, which are accumulated solids from the
internal
[[Page 55742]]
components of the roasting kiln waste heat boilers (Bevill exempt after
treatment)
--Spent post-leach ore residue (Bevill exempt after treatment)
--Spent post-neutralization ore residue (Bevill exempt after treatment)
--Saltcake drier scrubber wastewater
We consider the saltcake drier scrubber wastewater to be a
wastestream associated with the production of sodium sulfate at the
North Carolina facility, rather than a sodium dichromate manufacturing
waste. Nevertheless, we chose to exercise our discretion to evaluate
the risk posed by the treated and untreated form of this residue. As
explained below, we did not find risks warranting listing.
All four wastes catalogued above go directly from their points of
generation to the on-site spent ore residue treatment unit without
intervening storage. The facility treats non-contact cooling tower
blowdown, remediation well water, and stormwater in the treatment unit
as well. The four manufacturing wastes comprise approximately 60-65% by
volume of the wastes entering the treatment unit. The entire treatment
process takes place in a series of tanks with secondary containment.
Treatment consists of conversion of hexavalent chromium in the wastes
to trivalent chromium with pickle liquor (ferrous chloride reducing
agent). Trivalent chromium is a generally less toxic and less soluble
form of chromium. Wastes containing a high percentage of solids (waste
heat boiler washout, spent post-leach ore residue, and spent post-
neutralization ore residue) are also neutralized with lime slurry in
order to increase precipitation of trivalent chromium compounds out of
solution.
The treatment sludge is then thickened in a series of clarifier
tanks. Limestone is added to the thickened sludge to further stabilize
chromium and other metals. All of the tanks in the treatment train have
secondary containment and some are covered. Treated wastewaters, after
passing through sand filters, discharge from the treatment unit under
an NPDES permit or travel with the treated solid residues to the on-
site industrial Subtitle D disposal unit (see section
III.F.12.e(1)(b)ii below regarding the commingled treated wastewaters).
The Bevill exemption applies to the waste heat boiler washout,
spent post-leach ore residue, and spent post-neutralization ore residue
only after the wastes are treated. We evaluated the potential for
releases from the treatment tanks. We assumed that the tanks were
intact structures with minimal potential for releases to groundwater.
We do not anticipate significant air releases because the wastes do not
contain volatile constituents and have high moisture content. Also,
some of the tanks have covers which further reduce the possibility of
air releases. We are proposing not to list any of these four
wastestreams undergoing treatment in this tank system.
(b) Residuals Disposed of On-Site. (i) Commingled reduced chromium
treatment residues. The reduced chromium sludge from the on-site spent
ore residue treatment unit is slurried and conveyed directly from the
treatment unit to one of two on-site industrial Subtitle D disposal
units (former limestone quarries). Of the several treatment residues
contributing to the final commingled treatment residue, only one falls
within the scope of today's listing proposal; residue from treatment of
saltcake drier scrubber wastewater (we believe this is not within scope
of the consent decree but are evaluating it in this rule making).
Residues from the treatment of waste heat boiler washout, spent post-
leach ore residue, and spent post-neutralization ore residue are Bevill
exempt mineral processing wastes beyond the scope of today's listing
proposal (see Section III.F.12(c)). Stormwater and remediation well
water are contaminated media whose treatment residues we also consider
to be beyond the scope of the consent decree (see section III.B of
today's proposal). Therefore, we do not consider the risks posed by
these treatment residues.
According to information the facility submitted in their RCRA
Section 3007 Survey response, the only potential constituent of concern
in the untreated saltcake drier scrubber wastewater is chromium,
detected at a level of 6 mg/L. Therefore, chromium is the only
constituent we considered when assessing the level of risk from
saltcake drier scrubber wastewater treatment residues.
Of the total mass of chromium found in the commingled reduced
chromium treatment residues, the saltcake drier scrubber wastewater
contributes approximately 0.001%. This estimate is based on
calculations using information the North Carolina facility provided to
us on chromium contents and tonnages of waste exiting the spent ore
residue treatment unit. Both the information and the calculations are
further detailed in the ``Sodium Dichromate Listing Background Document
for the Inorganic Chemical Listing Determination.''
We found the treatment residues from saltcake drier scrubber
solution to pose no significant risks to groundwater. After treatment
for hexavalent chromium, the commingled reduced chromium treatment
residues from 1998 showed weekly TCLP analysis levels of leachable
chromium in the range of 0.01-1.00 mg/L for composite samples and 0.01-
0.76 mg/L for grab samples. Assuming that the saltcake drier scrubber
wastewater's percent contribution to total chromium in the commingled
residues is equal to its percent contribution to total chromium
leaching from the commingled residues (0.001%), the saltcake scrubber
solution was responsible for TCLP leaching levels of
1 x 10-7 to 1 x 10-5 mg/L for composite samples
and 3 x 10-7 to 2.28 x 10-5 mg/L for grab
samples. The HBL for ingestion of hexavalent chromium is 0.047 mg/L and
23 mg/L for trivalent chromium. The AWQC for hexavalent chromium is
0.011 mg/L and 0.74 mg/L for trivalent chromium. Even at a maximum
leaching level of 1 x 10-5 mg/L, the leachable chromium
contribution of the saltcake drier scrubber wastewater indicates a very
low level of risk to groundwater.
The treated wastes are disposed in an uncovered disposal unit that
resembles a surface impoundment. However, given the inorganic,
nonvolatile nature of the treated wastes, we do not believe they pose a
risk through airborne pathways. Given the low level of chromium
leaching attributable to the one treatment residue within the scope of
today's listing proposal and the lack of volatile constituents of
concern, we propose not to list residues deriving from the treatment of
saltcake drier scrubber wastewater.
(ii) Commingled treated wastewaters. The spent ore residue
treatment unit described in the sections above has clarifier units
which discharge a wastewater stream to tank-based sand filters. After
passing through sand filters, the treated wastewaters discharge through
an NPDES-permitted outfall. These wastewaters are a mixture of non-
Bevill exempt and Bevill exempt treatment residues, and other treatment
residues beyond the scope of the consent decree. The solids suspended
in the wastewaters are a mixture of Bevill exempt and non-Bevill exempt
treatment residues. The liquid portion, the majority of this
wastestream, is a mixture of non-Bevill exempt residues, some of which
are within the scope of this listing determination, and some of which
derive from treatment of contaminated media and are therefore not with
the scope of this listing determination. We did not find any
[[Page 55743]]
significant potential for releases from the tanks. (We assess spent
filter media from the sand filters separately in section
III.F.12.e(1)(c)ii below.) We concluded that the NPDES discharge is
exempt from RCRA regulation.
A portion of the commingled treated wastewaters remains with the
commingled reduced chromium treatment residues discharged for disposal
to the facility's on-site industrial Subtitle D disposal units. The
facility also adds water to this mixture from either the nearby
Northeast Cape Fear River or the quarry in order to help slurry and
convey the residues to the disposal units.
The liquids which separate from the settled treatment residues in
the facility's disposal units are not Bevill exempt wastes (see Section
III.F.12.c). Because these liquids derive from the same treatment unit
from which the NPDES-discharged wastewaters discussed above derive, we
are assuming their chemical composition is very similar to that of the
wastewaters discharged under the facility's NPDES permit. We used NPDES
permit discharge data, available to the public from the EPA's
Envirofacts database, \42\ as a surrogate for characterization of this
wastewater (see discussion of SPLP filtrate in Section III.E.3). The
exposure pathway of concern is the groundwater underlying the
facility's disposal units and consumption of the groundwater as
drinking water.
---------------------------------------------------------------------------
\42\ http://www.epa.gov/enviro/index_java.html.
---------------------------------------------------------------------------
According to the North Carolina facility's NPDES permit, the
facility is allowed to discharge 0.31 pounds per day of hexavalent
chromium to the Northeast Cape Fear River. Given the amount of treated
wastewater reported to be discharged in 1998 and using the permit
loading as an upperbound value, we estimate that the facility produced
an NPDES effluent with an average hexavalent chromium concentration of
0.056 mg/L. This concentration is less than twice the HBL for
hexavalent chromium (0.047 mg/L).\43\ However, according to NPDES
compliance monitoring data for the facility, no hexavalent chromium was
detected in the facility's NPDES effluent in 1998. Therefore, it is
likely that the actual concentration of hexavalent chromium in the
facility's commingled treated wastewaters is less than the
concentration the facility is permitted to release.
---------------------------------------------------------------------------
\43\ As described in Section III.E.3, we used engineering
judgment to screen out constituents with concentrations within a
factor of two of the HBL.
---------------------------------------------------------------------------
According to the North Carolina facility's NPDES permit, the
facility is also permitted to discharge 2.72 pounds of combined
hexavalent and trivalent chromium per day. Making the conservative
assumption that all 2.72 pounds of chromium are trivalent chromium and
given the amount of treated wastewater discharged in 1998, we estimated
that the facility produced an NPDES effluent with an average chromium
concentration of 0.49 mg/L, which is less than 23 mg/L, the HBL for
trivalent chromium. Actual reported levels of total chromium release
were well below the permit limit.
Given that the levels of chromium present in the on-site disposal
unit liquids are less than or within a factor of two of the HBLs, we do
not believe they pose a risk to human health or the environment through
groundwater underlying the disposal unit that supports listing these
wastewaters as a hazardous waste.
(c) Residuals Disposed of Off-Site. (i) Chromium-contaminated
filters, membranes, and other plant wastes. This waste category from
the North Carolina facility includes spent filters, membranes, and
various other plant wastes which exceed the TC level for chromium. The
wastes are stored in a closed roll-off bin on-site before being sent
off-site to a permitted Subtitle C facility for treatment and disposal
in a landfill. We feel that applicable Subtitle C regulations
adequately prevent mismanagement and therefore propose not to list
these wastes.
(ii) Spent sand filter sands. The North Carolina facility generates
waste sand material from the spent ore residue treatment unit sand
filters which filter treated wastewaters prior to their NPDES-permitted
discharge. The purpose of the sand filters is to remove any residual
solids which the treatment unit clarifiers fail to remove upstream in
the treatment process. Since the clarifiers capture the majority of the
solids, the sand filters capture smaller amounts of treatment residue.
The most recent disposal of sand from the filters took place in 1997.
The facility stores the spent sand in closed drums or roll-off bins on-
site before disposing of them in an off-site industrial Subtitle D
solid waste landfill.
According to information submitted to EPA by the North Carolina
facility, this residue does not exhibit any constituent above the TC
level according to TCLP leachate analysis. The only detected
constituent of potential concern was chromium, at a level of 0.2 mg/L.
Residue from treatment of saltcake drier scrubber wastewater is the
only residue contributing to the chromium levels in the spent sand
filters which also falls within the scope of today's listing proposal.
All other wastes are either Bevill exempt wastes or treatment residues
from contaminated media or non-contact cooling water, none of which
falls within the scope of the consent decree.
As discussed in section III.F.12.e(1)(b), the saltcake drier
scrubber solution contributes approximately 0.001% of the total
chromium exiting the spent ore residue treatment unit. Assuming that a
waste's percent contribution to total chromium exiting the treatment
unit is equal to its percent contribution to total chromium leaching
from waste exiting the unit, the figures above indicate a TCLP leaching
level of 2 x 10-\6\ mg/L due to the contributions of the
saltcake drier scrubber wastewater.
The HBL for hexavalent chromium is 0.047 mg/L and 23 mg/L for
trivalent chromium. The AWQC for hexavalent chromium is 0.011 mg/L and
0.74 mg/L for trivalent chromium. At a level of 2 x 10-\6\
mg/L, the leachable chromium contribution of the saltcake drier
scrubber wastewater presents a very low level of risk.
The waste is inorganic in nature and therefore we do not expect it
to contain volatile constituents of concern. In addition, the waste is
stored before disposal in a closed container. We do not believe,
therefore, that this waste poses a risk via airborne pathways. Given
the low level of risk posed by the saltcake drier scrubber wastewater
treatment residue contribution to leachable chromium levels in the
spent sand filters and its nonvolatile nature, we propose not to list
this waste.
(2) Texas Facility. (a) Residuals Commingled in On-Site Treatment
Units. At the Texas facility, commingling and treatment of four
untreated wastes takes place in two different on-site, tank-based
treatment units. The treatment residues from the two treatment units
are then co-disposed in an on-site, Subtitle D treatment surface
impoundment. The first treatment unit, the spent ore residue treatment
unit, treats the following two sodium dichromate manufacturing
wastestreams:
--spent post-neutralization ore residue (Bevill exempt after treatment)
--caustic filter sludge from filtration of sodium hydroxide
We consider caustic filter sludge to be a wastestream associated
with the production of sodium hydroxide rather than a sodium dichromate
manufacturing waste. Nevertheless, we chose to exercise our discretion
to
[[Page 55744]]
evaluate the risk posed by the treated and untreated forms of this
residue.
The spent ore residue treatment unit treatment tanks have both
secondary containment and covers. Treatment consists of converting the
hexavalent chromium in the units to trivalent chromium. Trivalent
chromium is typically a less soluble and less toxic form of chromium.
Ore residue wastes are not Bevill exempt and therefore beyond the scope
of the consent decree until treatment occurs. Therefore, we have
evaluated the potential for releases from these treatment tanks. We
assume the tanks are intact structures with minimal potential for
releases to groundwater. We believe the covers on the tanks reduce the
potential for air releases. Also, the wastes do not contain volatile
constituents.
The second treatment unit, the wastewater treatment unit, treats
the following two sodium dichromate manufacturing wastestreams:
--sodium chromate evaporation unit wastewaters
--sodium dichromate evaporation unit wastewaters
The wastewater treatment unit also treats remediation well water
and stormwater, two types of contaminated media which are outside the
scope of the consent decree. The two wastewaters within the scope of
the consent decree make up approximately 9% of the total volume of the
wastes entering the treatment unit. The facility converts hexavalent
chromium to less toxic trivalent chromium during this treatment
process. The tanks do not have covers.
We evaluated the tanks for potential releases to the environment.
We assumed the tank structures were intact and therefore posed minimal
potential for releases to groundwater. Since the wastewaters contain no
volatile constituents, we found no significant potential for air
releases. We are proposing not to list the wastes in these treatment
tanks.
The facility disposes the treatment materials from the two tank
systems described above in an on-site surface impoundment. We describe
that surface impoundment in the next section.
(b) Residuals Disposed of On-Site. (i) Commingled reduced chromium
treatment residues. The treatment residues from the two treatment tank
systems described in the section above are piped directly to the
facility's on-site, double-lined, Subtitle D surface impoundment for
co-disposal and dewatering. Of the several treatment residues
contributing to the mass of reduced chromium treatment residue disposed
of in the Subtitle D surface impoundment at the Texas facility, only
three fall within the scope of today's listing proposal: residue from
treatment of caustic filter sludge, residue from treatment of sodium
chromate evaporation unit wastewaters, and residue from treatment of
sodium dichromate evaporation unit wastewaters. Residues from the
treatment of post-neutralization spent ore residue are Bevill exempt
mineral processing wastes beyond the scope of today's listing proposal
(see section III.F.12.c). Stormwater and remediation well water are
contaminated media whose treatment residues we also consider to be
beyond the scope of the consent decree (see section III.B). Therefore,
we do not consider the risks posed by these residues.
According to information the facility submitted in their RCRA
Section 3007 Survey response, the only potential constituent of concern
in the untreated sodium dichromate evaporation unit wastewater, sodium
dichromate evaporation unit wastewaters, and the caustic filter sludge
is chromium, measured at a level of 0.5 mg/L, 0.5 mg/L and 20 mg/kg,
respectively. Therefore, chromium is the only constituent we considered
when assessing the level of risk from sodium dichromate evaporation
unit wastewater, sodium chromate evaporation unit wastewater, and
caustic filter sludge treatment residues.
Of the total chromium contributed to the co-disposed reduced
chromium treatment residue by all incoming wastes, the sodium
dichromate evaporation unit wastewater, sodium chromate evaporation
unit wastewater, and the caustic filter sludge contribute
5 x 10-5 percent by weight. This estimate is based on
calculations using information the Texas facility provided to us on
chromium contents and tonnages of wastes entering the spent ore residue
treatment unit and the wastewater treatment unit on-site. Both the
information and the calculations are described further in the ``Sodium
Dichromate Listing Background Document for the Inorganic Chemical
Listing Determination.''
The facility did not provide us with TCLP, SPLP, or total
constituent analyses for the co-disposed reduced chromium treatment
residues. However, the facility did report to us that reduced chromium
treatment residues do not exceed the TC level of 5.0 mg/L according to
TCLP analysis. In addition, the facility reported that for the time
period between October 1, 1998 and December 31, 1998, weekly samples of
reduced chromium treatment residues from the spent ore residue
treatment unit analyzed with a facility-modified version of the TCLP
ranged between 0.16 and 1.75 mg/L chromium (see ``Sodium Dichromate
Listing Background Document for the Inorganic Chemical Listing
Determination'' for details). Therefore, conservatively assuming a
maximum TCLP chromium leaching level of 4.9 mg/L and assuming that the
percent contribution by the three wastes to total chromium entering the
treatment units is equal to their percent contribution to total
chromium leaching from treatment residues exiting the treatment units,
the caustic filter sludge, sodium chromate evaporation unit
wastewaters, and sodium dichromate evaporation unit wastewaters were
responsible for TCLP chromium leaching levels of 2.45 x 10-6
mg/L.
The HBL for hexavalent chromium is 0.047 mg/L and 23 mg/L for
trivalent chromium. The AWQC for hexavalent chromium is 0.011 mg/L and
0.74 mg/L for trivalent chromium. At a leaching level of
2.45 x 10-6 mg/L, the leachable chromium contribution of the
caustic filter sludge, sodium chromate evaporation unit wastewaters,
and the sodium dichromate evaporation unit wastewaters indicates a very
low level of risk to groundwater from potential releases from the
surface impoundment.
The waste is metallic and inorganic in nature and therefore we do
not expect it to contain volatile constituents of concern. We do not
believe, therefore, that this waste poses a risk via airborne pathways.
Given the low level of chromium leachate deriving from the three
treatment residues within the scope of today's listing proposal and
placed into the surface impoundments, we propose not to list residues
deriving from the treatment of caustic filter sludge, sodium chromate
evaporation unit wastewater, and sodium dichromate evaporation unit
wastewater.
(ii) Commingled treated wastewaters. Treated wastewaters commingled
with the commingled reduced chromium treatment residues separate from
these solid residues in the Texas facility's surface impoundment
disposal unit. These liquids are not Bevill exempt wastes (see Section
III.F.12.3). The solids suspended in the wastewaters are a mixture of
Bevill exempt and non-Bevill exempt treatment residues. The liquid
portion, the majority of this wastestream, is a mixture of non-Bevill
exempt residues, some of which are within the scope of this listing
determination, and some of which derive from treatment of contaminated
[[Page 55745]]
media and are therefore not within the scope of this listing
determination.
The commingled treated wastewaters discharge from the surface
impoundment through an NPDES-permitted outfall after passing through
sand filters to remove residual solids (see discussion below in Section
III.F.12.e(2)(c)(ii). We therefore assume that the chemical composition
of the treated wastewaters in the surface impoundment is very similar
to that of the NPDES permitted discharge. We used NPDES permit
discharge data, available to the public from the EPA's Envirofacts
database,\44\ as a surrogate for characterization of this wastewater
(see discussion of SPLP filtrate in Section III.E.3). The exposure
pathway of concern is the groundwater underlying the facility's
disposal units and consumption of the groundwater as drinking water.
---------------------------------------------------------------------------
\44\ http://www.epa.gov/enviro/index_java.html
---------------------------------------------------------------------------
According to the Texas facility's 1998 NPDES monitoring data, the
facility discharged an average of 0.018 pounds of hexavalent chromium
each day through their internal NPDES outfall. Given the amount of
treated wastewater the facility reported as discharge from the surface
impoundment in 1998, we estimate that the facility produced an NPDES
effluent with an average hexavalent chromium concentration of 0.016 mg/
L. This concentration is less than the HBL for hexavalent chromium
(0.047 mg/L).
According to the Texas facility's NPDES monitoring data for 1998,
the facility released an average of 0.46 pounds of combined hexavalent
and trivalent chromium per day. Making the conservative assumption that
all 0.46 pounds of chromium are trivalent chromium and given the amount
of treated wastewater discharged in 1998, we estimated that the
facility produced an NPDES effluent with an average chromium
concentration of 0.41 mg/L, which is less than 23 mg/L, the HBL for
trivalent chromium.
Wastes in the surface impoundment dewater and the resulting
wastewaters pass out of the surface impoundment and through tank-based
sand filters. From the sand filters, the treated wastewaters then
discharge through an NPDES-permitted outfall. These wastewaters are a
mixture of non-Bevill exempt and Bevill exempt treatment residues, and
other treatment residues beyond the scope of the consent decree. We did
not find any significant potential for releases from the sand filter
tanks. (We assess spent filter media from the sand filters separately
in Section III.F.12.e(2)(c)(ii) We concluded that the NPDES discharge
is exempt from RCRA regulation.
(c) Residuals Disposed of Off-Site. (i) Process filters and
membranes, baghouse bags, chromium-contaminated empty containers, and
other plant wastes. The Texas facility reports in their RCRA Section
3007 Survey response that process filters and membranes and baghouse
bags from their facility exceed the TC level for chromium and are coded
D007. The facility also reports that they produce empty containers and
other plant wastes contaminated with chromium which are also coded
D007. The facility stores these hazardous wastes in a closed rolloff
bin on-site before sending them off-site to a permitted Subtitle C
hazardous waste facility for treatment and landfill disposal. These
wastes are sufficiently managed under current RCRA Subtitle C
regulations and therefore we propose not to list these wastes.
(ii) Spent sand filter sands. The Texas facility generates waste
sand material from the sand filters which filter treated wastewaters
prior to their NPDES permitted discharge from the facility's on-site
surface impoundment. The purpose of the sand filters is to remove any
residual solids which fail to settle in the surface impoundment. Since
the majority of the solids settle in the surface impoundment, the sand
filters captures smaller amounts of reduced chromium treatment residue.
Approximately 2 MT of spent sand filter sand is disposed of every two
years. The facility stores the spent sand in non-hazardous soil bins
on-site before disposing of it at an off-site Subtitle D industrial
landfill.
According to the Texas facility, this residue does not exhibit any
constituent above the TC level according to TCLP leachate analysis.
Residues from treatment of caustic filter sludge, sodium chromate
evaporation unit wastewaters, and sodium dichromate evaporation unit
wastewaters are the only residues contributing to the potential
constituent of concern levels in the spent sand filters which also fall
within the scope of today's listing proposal. All other wastes are
either Bevill exempt wastes or treatment residues from contaminated
media, neither of which falls within the scope of the consent decree.
Chromium was the only potential constituent of concern detected in
the sodium chromate evaporation unit wastewaters, sodium dichromate
evaporation unit wastewaters and the caustic filter sludge, and is
therefore the only potential constituent of concern we considered in
the spent sand filter sands. As discussed in the section on commingled
reduced chromium treatment residues, the residues contribute
5 x 10-5 percent of the total chromium mass entering the
spent ore residue treatment unit. Assuming a maximum TCLP chromium
leaching level of 4.9 mg/L, and assuming that the percent contribution
to total chromium by the three wastes entering the treatment units is
equal to their percent contribution to total chromium leaching from
treatment residues exiting the treatment units, the caustic filter
sludge, sodium chromate evaporation wastewaters, and sodium dichromate
evaporation unit wastewaters were responsible for TCLP chromium
leaching levels of 2.4 x 10-6 mg/L.
The HBL for hexavalent chromium is 0.047 mg/L and 23 mg/L for
trivalent chromium. The AWQC for hexavalent chromium is 0.011 mg/L and
0.74 mg/L for trivalent chromium. At a level of 2.4 x 10-6
mg/L, the leachable chromium contribution of the sodium dichromate
evaporation unit wastewater, the sodium chromate evaporation
wastewaters, and the caustic filter sludge presents a very low level of
risk.
The waste is metallic and inorganic in nature, and therefore we do
not expect it to contain volatile constituents of concern. We do not
believe, therefore, that this waste poses a risk via airborne pathways.
Given the low level of risk posed by the contribution of constituents
in the spent filter sands attributable to caustic filter sludge, sodium
chromate evaporation unit wastewaters, and sodium dichromate
evaporation unit wastewater treatment residue, the absence of volatile
constituents of concern, and the relatively small volume of the total
waste, we propose not to list this waste.
13. Sodium Phosphate From Wet Process Phosphoric Acid
a. Summary. We propose not to list any wastes from the production
of sodium phosphate from wet process phosphoric acid as hazardous under
subtitle C of RCRA. Many of these secondary materials are piped back
into the production process; other wastes are discharged to a permitted
publicly-owned treatment works (POTW). Other materials are sent to
Subtitle D industrial landfills. After an analysis of waste management
practices and potential exposure pathways, we conclude that there are
no risk pathways of concern. These wastes do not meet the criteria set
out at 40 CFR 261.11(a)(3) for listing as hazardous.
b. Description of the sodium phosphate industry. Sodium phosphate
is the more general chemical name for
[[Page 55746]]
a wide variety of salts produced from the neutralization of phosphoric
acid. Some of the salts produced by the facilities in this industry are
monosodium dihydrogen phosphate (H2NaPO4),
disodium monohydrogen phosphate (HNa2PO4),
trisodium phosphate (Na3PO4), sodium
hexametaphosphate (Na4P 4O12), and
sodium tripolyphosphate (Na5P3O10).
The various phosphate salts produced are used for a wide variety of
purposes, ranging from a water soluble solid acid and pH buffer for
acidic cleaners to products manufactured for the food industry \45\.
Sodium phosphate is produced from wet process phosphoric acid by two
manufacturing companies at four locations in the United States. For
more detailed information concerning this industry, see ``Sodium
Phosphate Listing Background Document for the Inorganic Chemical
Listing Determination'' in the docket for today's proposal.
---------------------------------------------------------------------------
\45\ In this preamble, we often refer to sodium phosphate
produced for the food industry as ``food grade.'' The Food and Drug
Administration (FDA), Department of Health and Human Services,
refers to the various sodium phosphates used in the food industry as
``substances generally recognized as safe'' (GRAS). The FDA states
that: ``This substance is generally recognized as safe when used as
in accordance with good manufacturing practice.'' (See, for example,
21 CFR 182.1778, 182.6290, 182.6778, and 182.8778.) In deciding
whether a food additive should be approved, the FDA considers the
composition and properties of the substance, the amount likely to be
consumed, its probable long-term effects and various safety factors.
---------------------------------------------------------------------------
The processes for monosodium dihydrogen phosphate, disodium
monohydrogen phosphate, and trisodium phosphate are similar except for
the ratio of phosphoric acid to soda ash at the reactor stage and the
type, size and construction of the crystallizing and drying equipment.
The raw materials are water, phosphoric acid, soda ash, and caustic.
The purified phosphoric acid is manufactured elsewhere through the wet-
acid purification method and is food grade. The process starts with a
reaction between phosphoric acid, soda ash, and caustic. The solution
is used to make the monosodium dihydrogen phosphate, which passes
through a polishing filter before shipment to customers. The sodium to
phosphorus ratio of the solution is adjusted with caustic to make
disodium monohydrogen phosphate and trisodium phosphate. These
solutions are filtered and then crystallized. The crystals from each
process pass through dryers. The finished product is packaged or
shipped in bulk.
Sodium hexametaphosphate and sodium tripolyphosphate are also
produced from food-grade phosphoric acid and soda ash. Both processes
start with a reaction between phosphoric acid and soda ash. For the
sodium hexametaphosphate process, the product is fed to a furnace which
melts the mix and converts it to sodium hexametaphosphate. For the
sodium tripolyphosphate process, the reaction discharge is dried and
heat treated in a converter to convert it to sodium tripolyphosphate.
In both processes, the product is cooled, sized, stored, and packaged
for shipment.
c. What kinds of wastes are generated by these processes? A brief
description of the waste categories, how they are generated, their
volumes across the industry, and how they are managed is presented in
Table III-34:
Table III-34.--Sodium Phosphate Production Wastes
----------------------------------------------------------------------------------------------------------------
Waste category 1998 Volume (MT) Source Management practices
----------------------------------------------------------------------------------------------------------------
Filter press cakes............... 120...................... Product polishing....... Recycled or Subtitle D
landfill.
Mix area filters................. 0.009.................... Product polishing....... Subtitle D landfill.
Dust collector filter bags....... 2.1...................... Drying and grinding Subtitle D landfill.
processes.
Scrubber waters and effluents.... 32....................... Process vapor scrubbers. POTW or recycled.
Product dust collected........... Not reported............. Drying and grinding Recycled or Subtitle D
processes. landfill.
Off-specification product........ 771...................... Off-specification Recycled or Subtitle D
grinding or customer landfill.
returns.
----------------------------------------------------------------------------------------------------------------
For those scenarios where secondary materials (filter press cakes,
product dust, off-specification product, and scrubber water) are piped
back to the production process, we could identify no potential route
for significant exposure prior to reuse. In addition, we evaluated all
wastes generated after reinsertion of these materials into the process
and we do not believe that these secondary materials present
significant threats. Also, off-specification product, when reinserted
without reclamation into the process from where it originated, is not a
solid waste. For those scenarios where wastes are discharged via the
facility's common sewage line to permitted publicly-owned treatment
works (POTWs), these wastes are excluded from RCRA (40 CFR
261.4(a)(1)(ii)). For those scenarios where wastes are sent to
industrial subtitle D landfills, we performed a risk assessment to help
us determine whether these risks warranted listing.
d. Agency evaluation. (1) Filter press cake and mix area filters.
How Was This Waste Characterized?
We collected two samples of this residual at one facility. Based on
our assessment of the raw materials and production processes used
across the industry, we believe these samples are representative of the
range of waste characteristics at the other three sodium phosphate
production facilities. Constituents detected above their HBLs are
summarized in Table III-35.
Table III-35.--Characterization of Filter Press Cakes From Sodium Phosphate Production
----------------------------------------------------------------------------------------------------------------
Total (mg/ TCLP (mg/ SPLP (mg/
Parameter kg) l) l) HBL (mg/l)
----------------------------------------------------------------------------------------------------------------
Primary filter press cake (Sample RCH-1-SP-01):
Antimony................................................ 0.5 0.5 0.0298 0.006
Thallium................................................ 2 2 0.0055 0.001
[[Page 55747]]
Tray filter cake (Sample RCH-1-SP-02):
Antimony................................................ 0.5 0.5 0.025 0.006
Thallium................................................ 2 2 0.0079 0.001
----------------------------------------------------------------------------------------------------------------
What Management Scenarios Were Assessed and How Was the Risk Assessment
Established?
These wastes go to industrial subtitle D landfills and we therefore
determined that we would model the scenario of off-site disposal in an
industrial D landfill. We assessed the off-site landfill scenario using
the hydrogeologic properties associated with the geographic areas where
the landfills reported in the survey are located.
We gave the SPLP results primary consideration as there is no
reported management in municipal landfills (where the TCLP results
would be relevant). Based on the sampling results summarized above, we
decided that modeling was necessary for two constituents of concern:
antimony and thallium. For antimony, we used one-half of the detection
limit as a model input for sample RCH-1-SP-02. We used the
probabilistic approach for an off-site industrial Subtitle D landfill
described in section III.E of today's proposal.
What Is EPA's Listing Rationale for This Waste?
From the results of the risk assessment, summarized below in Table
III-36, neither antimony nor thallium (the constituents of concern)
pose a substantial present or potential hazard to human health and the
environment. The hazard quotients for both constituents, for both the
adult and child exposure scenarios, are less than 0.008 at the 95th
percentile. As a matter of policy, EPA generally does not consider
listing wastes with predicted hazard quotients of less than 1.0. We see
no special concerns warranting an exception to this policy. Therefore,
we believe that these wastes do not warrant listing.
For the mix area filters, the location of these filters indicates
that any contaminants found would be similar to those of the filter
press cake. Given that our evaluation of the much larger volume filter
press cake yielded no significant risk, we are also proposing not to
list the very small volume mix area filters.
For a more complete description of these analyses, see ``Risk
Assessment for the Listing Determinations for Inorganic Chemical
Manufacturing Wastes'' in the docket for this proposed rulemaking.
Table III-36.--Probabilistic Risk Results for Filter Press Cakes
------------------------------------------------------------------------
Antimony Thallium
-------------------------------
Percentile Adult Child Adult Child
HQ HQ HQ HQ
------------------------------------------------------------------------
Industrial landfill:
90th.................................... 0.001 0.003 0.002 0.003
95th.................................... 0.004 0.008 0.004 0.008
------------------------------------------------------------------------
(2) Dust collector filter bags.
How Was This Waste Characterized?
We collected one sample of this residual. Based on our assessment
of the raw materials and production processes used across the industry,
we believe this sample is representative of similar wastes at the other
three sodium phosphate production facilities. The waste constituents
detected at levels above their HBLs are summarized in Table III-37:
Table III-37.--Characterization of Dust Collector Filter Bag From Sodium
Phosphate Production
[Sample RCH-1-SP-03]
------------------------------------------------------------------------
Total
Parameter (mg/ TCLP SPLP HBL
kg) (mg/l) (mg/l) (mg/l)
------------------------------------------------------------------------
Antimony.............................. 48.8 0.5 0.309 0.006
Arsenic............................... 0.5 0.5 0.0064 0.0007
------------------------------------------------------------------------
What Management Scenarios Were Assessed and How Was the Risk Assessment
Established?
Industry reported that this waste is managed in off-site industrial
D landfills. We assessed this scenario. Antimony and arsenic are the
constituents of concern.
Because the volume of this waste is relatively small, we first used
the de minimis waste quantity screening analysis (described in section
III.E.3) to screen the potential risk to groundwater associated with
landfilling this waste. We found that the SPLP data for arsenic screens
out because the waste volume is insufficient to release arsenic at
levels of concern. For a more complete description of this analysis,
see ``Risk Assessment for the Listing Determinations for Inorganic
Chemical Manufacturing Wastes'' in the docket for this proposed
rulemaking.
The detected SPLP levels for antimony did not screen out using the
de minimis volume analysis. We conducted full groundwater modeling for
the industrial landfill scenario for this constituent. We assessed the
off-site landfill scenario using the probabilistic approach for off-
site landfills described in section III.E.
What Is EPA's Listing Rationale for This Waste?
From the results of the risk assessment, summarized below in Table
III-38, antimony (the constituent of concern) does not pose a
substantial present or potential hazard to human health and the
environment. The hazard quotients for antimony, for both the adult and
child exposure scenarios, are less than 0.007 at the 95th percentile.
As a matter of policy, EPA generally does not consider listing wastes
with predicted hazard quotients of less than 1.0. We see no special
concerns warranting an exception to this policy. Therefore, we believe
that this waste does not warrant listing. For a more complete
description of this analysis, see ``Risk Assessment for the Listing
Determinations for Inorganic Chemical Manufacturing Wastes'' in the
docket for this proposed rulemaking.
Table III-38.--Probabilistic Risk Results for Dust Collector Bags
------------------------------------------------------------------------
Antimony
-----------------
Percentile Adult Child
HQ HQ
------------------------------------------------------------------------
Industrial landfill:
90th.............................................. 0.001 0.002
95th.............................................. 0.003 0.003
------------------------------------------------------------------------
(3) Scrubber waters and effluents. We did not evaluate scenarios
where these secondary materials are piped back into the production
process because there is no potential for exposure. For those scenarios
where wastes are managed in a tank, the impervious nature of the
construction materials (concrete,
[[Page 55748]]
fiberglass, or steel) of tanks are unlikely to result in releases to
groundwater in all but the most catastrophic scenarios. We also are not
concerned with potential air releases from these tanks as neither
volatile contaminants nor airborne particulates are likely to be
present in these aqueous wastes. For those scenarios where wastes are
discharged via the facility's common sewage line to POTWs, these wastes
are excluded from RCRA (40 CFR 261.4(a)(1)(ii)). Furthermore, these
discharges are regulated by the Clean Water Act pretreatment standards.
They do not warrant listing. We propose not to list this waste.
(4) Product dust collected. All collected dust that can be recycled
is recycled back into the production process. Due to production
constraints, some portion of this collected product dust cannot be
recycled back to the process and is instead sent to an industrial
Subtitle D landfill. However, this landfilled product is still food-
grade product. Because this ``waste'' is, in fact, food-grade product,
we believe it unlikely that it contains any constituent exceeding
health-based limits based on ingestion. Therefore, we propose not to
list this waste.
(5) Off-specification product. Much of this material is reused in
the production process with no potential for exposure. However, because
of production constraints, they cannot always work all of this material
back into the process, and it must be disposed in an industrial
subtitle D landfill. In all cases, product is rejected by a customer
because of physical property problems--i.e., particle size--rather than
chemical problems or contaminants. Because this ``waste'' is, in fact,
food-grade product, we believe it unlikely that it contains any
constituent exceeding health-based limits based on ingestion.
Therefore, we propose not to list this waste.
14. Titanium Dioxide
a. Summary. We evaluated wastes from the production of titanium
dioxide and propose to list one waste and not to list all of the
others. Certain wastes from titanium dioxide production are exempt
mineral processing wastes and were not assessed as part of today's
listing determination because they are outside the scope of the consent
decree. We are proposing to list nonwastewaters from the chloride
ilmenite process (unless otherwise exempted).
K178 Nonwastewaters from the production of titanium dioxide by the
chloride-ilmenite process. (T) [This listing does not apply to chloride
process waste solids from titanium tetrachloride production exempt
under section 261.4(b)(7)]
We propose not to list the remainder of the wastes generated by
this sector. We do not believe these wastes pose threats to human
health or the environment that warrant listing. We have not identified
risks of concern associated with the current management of these wastes
that support a listing determination. Our findings, however, do not
change the applicability of existing standards and regulations, such as
the hazardous waste characteristics, to these wastes and this industry.
b. Description of the titanium dioxide industry. There are nine
facilities producing titanium dioxide. There are three distinct
processes currently in use: the chloride process, the sulfate process,
and the chloride-ilmenite process. Six facilities use the chloride
process. Two of these six facilities also produce titanium dioxide via
the sulfate process. Three separate facilities use only the chloride-
ilmenite process.
Chloride Process. In the chloride process, rutile or high-grade
ilmenite is converted to titanium tetrachloride (TiCl4). The
conversion takes place in a chlorinator in the presence of chlorine gas
with petroleum coke added as a reductant. All U.S. producers of
TiCl4 use fluidized bed chlorinators. Vent gases from the
chlorinator are scrubbed prior to venting to the atmosphere. Non-
volatile metal chlorides and unreacted coke and ore solids are removed
from the gaseous product stream. The facilities also generate waste
acid, which they mingle with coke and ore solids before treatment. Vent
gases from the chlorinator are scrubbed prior to venting to the
atmosphere. The volatile TiCl4 and other volatile metal
compounds such as vanadium oxychloride, exit the chlorinator as
overhead vapor. The gaseous product stream is purified to separate the
titanium tetrachloride from other metal chloride impurities using
processes such as partial condensation and chemical treatment. Finally,
vanadium compounds, which have boiling points close to that of
TiCl4, are removed from the titanium tetrachloride by
complexing with mineral oil and reducing with hydrogen sulfide, or by
complexing with copper. The purified TiCl4 is then oxidized
to TiO2, driving off chlorine gas, which is recycled to the
chlorinator. The pure TiO2 is slurried and sent to the
finishing process which includes milling, addition of inorganic and
organic surface treatments, and/or spray drying of the product
TiO2. The product can be sold as a packaged dry solid or a
water-based slurry.
Sulfate Process. In the sulfate process, ilmenite ore or slag with
high TiO2 content is digested with sulfuric acid, forming a
porous cake; this cake is further dissolved by dilute acid to form
titanyl sulfate (TiOSO4). Iron may be added to the digestion
process to ensure that iron impurities remain in the ferrous
(Fe2+) state so that the eventual TiO2 product
can be easily washed. The titanyl sulfate solution is then clarified,
yielding a waste sulfate digestion sludge, and then concentrated
through vacuum evaporation. The filtered titanyl sulfate solution is
vacuum-evaporated a second time and hydrolyzed to precipitate hydrated
titania (TiO(OH)2). The titania hydrate is then filtered and
washed, yielding filtrate waste and wastewater, respectively, before
being calcined at 1,000 deg.C to produce the TiO2 product.
Chloride-Ilmenite Process. In the chloride-ilmenite process,
ilmenite ore is converted to titanium tetrachloride. As in the chloride
process, the chloride-ilmenite process takes place in a chlorinator in
which the ore is chlorinated in the presence of coke as a reducing
agent. Vent gases from the chlorinator are scrubbed prior to venting to
the atmosphere. Non-volatile metal chlorides and unreacted coke and ore
solids are removed from the gaseous product stream. The gaseous product
stream then is purified further to separate the titanium tetrachloride
from other volatile metal chloride impurities, including ferric
chloride (FeCl3) which is present in higher concentrations
than the chloride process due to the high iron content in the ore. The
separation is done via condensation and chemical treatment. The process
for converting the purified TiCl4 product stream to
TiO2 is similar to that used in the chloride process, as
described above.
c. What kind of wastes are generated by these processes?. The
wastes generated by the titanium dioxide sector are described in
overview below, organized by process. Additional detail on these wastes
is provided in the background document for this sector.
The wastes generated by the chloride process include:
--Commingled wastewaters, including process and non-process wastewaters
from chlorinator coke and ore solids recovery, reaction and chemical
tank storage scrubbers, product finishing operations, wastewater
treatment and chlorinator solids decantation, and on-site landfill
leachate.
--Chloride process waste solids from titanium tetrachloride production
(exempt as mineral processing wastes, see 40 CFR 261.4(b)(7)).
[[Page 55749]]
--Wastewater treatment sludges generated by facilities that have
chloride-only processes (exempt mineral processing wastes at those
facilities with no contribution of solids from oxidation and finishing)
--Waste sands from finishing (milling) of the titanium dioxide product
and scouring of oxidation process units.
--Vanadium wastes generated in the purification process.
The wastes generated by the sulfate process (used at two plants
that also use the chloride process) include:
--Primary and secondary gypsum, which is produced when the waste
sulfuric acid generated from the filtering of titanium dioxide hydrate
solution is neutralized with calcium carbonate.
--Digestion sludge from the clarification of the titanyl sulfate liquor
that is produced during the acid digester step.
--Wastewaters from the sulfuric acid digestion scrubber which removes
acidic components and entrained solids from reaction gases, evaporator
condensate from the precipitation unit, the calciner scrubber, the
sulfate waste sludge settling pond supernatant, and the primary and
secondary gypsum precipitation units. These wastewaters are commingled
with wastewaters from the chloride process.
--Wastewater treatment sludges. These wastewater treatment sludges are
generated from commingled chloride process and sulfate process
wastewaters by facilities that have both processes. The wastewater
treatment consists of elementary neutralization and precipitation or
filtration.
--Acids from intermediate titanium product filtration/bleaching units
and product calciner overhead scrubbers.
--Product milling sand from finishing operations.
The wastes generated by the chloride-ilmenite process include:
--Coke and ore solids (exempt as mineral processing wastes, see 40 CFR
261.4(b)(7)) that are not consumed by the chlorination process. These
solids are conveyed through the process as part of various
wastestreams.
--Waste acid (metal chloride) solution, usually called ferric or iron
chloride, that is separated from the gaseous titanium tetrachloride
product stream and acidified.
--Process and non-process wastewaters from reaction and oxidation
scrubbers, reactant and treatment chemical storage scrubbers, product
finishing, HCl storage vent scrubber, oxidation unit tank and equipment
vents, supernatant or filtrate from coke and ore solids management and
wastewater treatment disposal impoundments. The wastewaters are
commingled prior to being introduced into the wastewater treatment
system.
--Other spent scrubber waters from the reaction fume disposal system.
The wastewaters are pretreated and are subsequently commingled with
other wastewaters prior to being introduced to the wastewater treatment
system.
--Non-exempt non-wastewaters, including the portion of wastewater
treatment solids derived from the neutralization of process and non-
process wastewaters from oxidation and finishing, and solids from
ferric chloride filtration.
--HCl from the reaction scrubber.
--Additive feeder vent filter solids generated in the oxidation
process.
--Vanadium waste generated in the purification process.
--Off-specification titanium dioxide product.
--Rail car product washout wastewater.
--Waste sand removed from a reactor purge stream (coke and ore solids)
Table III-39, below, summarizes our information about the wastes
generated rom the production of titanium dioxide.
Table III-39.--Titanium Dioxide Wastes
----------------------------------------------------------------------------------------------------------------
Number of
Waste category generators 1998 volumes (MT) Reported hazard codes Management practices
----------------------------------------------------------------------------------------------------------------
Commingled chloride process 4 7,614,358............ D002, D007........... Neutralization,
wastewaters. solids settling,
NPDES discharge.
Chloride process solids 6 1,200,000............ none................. On-site impoundments,
(Bevill exempt). on-site Subtitle D
landfills.
Waste sands from oxidation, 3 9,485................ none................. On-site industrial
milling and scouring. Subtitle D landfill;
off-site industrial
Subtitle D landfill.
Gypsum from sulfate process.. 2 \46\ 69,500.......... none................. On-site waste pile
storage; on-site
industrial Subtitle
D landfill; sold for
various uses.
Digestion scrubber water..... 2 2,000,333............ Neutralization in
dedicated
impoundment;
commingled with
other wastewaters.
Digestion sludge from sulfate 2 41,494............... D002................. Unlined impoundment,
process. dewatering, on-site
industrial Subtitle
D landfill.
Commingled wastewaters from 2 16,184,031........... none................. Neutralization,
the chloride and sulfate solids settling in
process. unlined surface
impoundments, NPDES
discharge.
Wastewater treatment sludges 2 159,121.............. none................. Dewatering, on-site
from commingled chloride and industrial Subtitle
sulfate process (partially D landfill.
Bevill exempt).
Waste acid (ferric chloride) 3 1,883,000............ D002, D007, D008..... On-site hazardous
from chloride-ilmenite waste underground
process. injection; reuse as
raw material in
sodium chloride
production; storage
in tanks and unlined
impoundment prior to
sale as water and
wastewater treatment
reagent.
Chloride ilmenite process 3 not reported......... none................. On-site dewatering;
solids (Bevill exempt). on-site Subtitle D
industrial landfill;
on-site unlined
impoundment; various
reuses.
Non-exempt nonwastewaters 3 14,600............... none................. On-site dewatering;
from the chloride-ilmenite on-site Subtitle D
process. industrial landfill;
on-site unlined
impoundment; various
reuses.
HCl from reaction scrubber, 3 not reported......... D002................. On-site wastewater
chloride-ilmenite process. treatment, on-site
reuse.
Commingled wastewaters from 3 13,556,000........... none................. On-site
the chloride-ilmenite neutralization,
process. solids settling,
NPDES discharge.
[[Page 55750]]
Additive vent filter solids 1 1................... none................. Off-site Subtitle D
from chloride-ilmenite industrial landfill.
process.
Vanadium waste from the 4 not reported......... none................. Returned to reaction
chloride-ilmenite and area for TiCl 4
chloride process. recovery, remaining
vanadium wastes are
incorporated in
solids streams.
Off-spec titanium dioxide 2 563.................. none................. Off-site Subtitle D
product. industrial landfill.
Railcar/trailer product 1 10,000............... none................. On-site storage in
washout. unlined surface
impoundment, on-site
wastewater
treatment.
----------------------------------------------------------------------------------------------------------------
\46\ Additional volumes are used as products.
The manufacturers also produce materials that are reused in other
processes that are outside the scope of the consent decree. With one
exception described below, we did not evaluate these materials, or
wastes generated during co-product production for the purposes of
today's listing determinations, because they were outside the scope of
the consent decree.
One facility produces sulfur from the treatment of off-gases.
Because the off-gas is produced from a production unit rather than a
waste management unit and is conveyed to its destination via piping,
the gas is not a solid waste. RCRA Section 1004(27) excludes non-
contained gases from the definition of solid waste and thus they cannot
be considered a hazardous waste. (See 54 FR 50973) Because this gas is
not a solid waste when produced, we did not evaluate it further for
purposes of listing.
d. What wastes from these processes are exempt mineral processing
wastes? In July of 1988, the U.S. Court of Appeals, for the D.C.
Circuit in Environmental Defense Fund v. EPA (EDF II), 852 F.2d 1316
(D.C. Cir. 1988), cert. denied, 489 U.S. 1011(1989), ordered EPA to
restrict the scope of the Bevill mining waste exclusion, as it applied
to mineral processing wastes. In response, EPA promulgated rules on
September 1, 1989 (54 FR 36592) and on January 23, 1990 (55 FR 2322),
issued a Report to Congress on Wastes from Mineral Processing on July
31, 1990, and published a regulatory determination published on June
13, 1991 (56 FR 27300). The list of Bevill exempt wastes is set out at
40 CFR 261.4(b)(7). We relied on these Bevill rulemakings to determine
the Bevill status of waste streams in the titanium dioxide sector.
The production of titanium dioxide results in the generation of 2
categories of exempt waste: beneficiation wastes and exempt mineral
processing wastes. These categories are described below.
The industry reported a number of wastes generated from the storage
and handling of various raw materials which are exempt because they are
associated with beneficiation. Solid wastes from the extraction/
beneficiation of ores and minerals are Bevill exempt solid wastes (see
51 FR 24496, July 3, 1986 and 54 FR 36592, September 1, 1989). These
wastes are described in the background document for this sector. We
have not assessed these wastes because they are exempt under 40 CFR
261.4(b)(7).
The only relevant mineral processing waste exemption consists of
``chloride process waste solids from titanium tetrachloride
production'' (see 40 CFR 261.4(b)(7)(ii)(S)). The consent decree
mandating today's proposal states in paragraph 1.g that Bevill exempt
wastes are not within the scope of the consent decree as it applies to
the inorganic chemical listing determinations, and specifically that
``chloride process waste solids'' need not be assessed within the
titanium dioxide sector. Titanium tetrachloride production occurs in
both the chloride and chloride-ilmenite processes.\47\
---------------------------------------------------------------------------
\47\ All sulfate process waste solids and liquids are non-exempt
mineral processing wastes (see 55 FR 2322, January 23, 1990). 55 FR
2392 noted that all sulfate process waste solids and wastewaters
from the production of titanium dioxide do not meet the high volume/
low hazard criteria established in the September 1, 1989 Bevill rule
and therefore were not eligible for continued coverage under the
Bevill exclusion (see 54 FR 36592).
---------------------------------------------------------------------------
The chloride process waste solids are generated during the
chlorination reaction of the titanium ore in the reducing presence of
coke at elevated temperatures, and are generated from both the chloride
process and the chloride-ilmenite process. The majority of these solids
are removed from the reaction area as a mass and are quenched,
neutralized, settled and disposed as exempt materials. Additional
solids from the reactor are carried overhead with the TiCl4 product gas
stream and are subsequently removed in various scrubbing units.
Although EPA has not previously discussed these solids, we believe that
they also fall within the exemption. While they are removed from the
product stream and various other wastes at points other than where the
majority of the solids are separated from the TiCl4 gas stream, they
are similarly composed of unreacted ore and coke solids from the
chlorination reactor. They fit within the plain language of the
exemption.
Solids also are generated from the oxidation and finishing stages
of titanium dioxide production. These solids are non-exempt solid
wastes (not covered by the exemption). Most titanium dioxide producers
commingle wastewaters from titanium tetrachloride production with
wastewaters from oxidation and finishing. To the extent that the
resultant sludges contain non-exempt solids, we have assessed that
portion of those solids.
Due to process variations, each facility using the chloride or
chloride-ilmenite process generates its exempt solids in slightly
different ways. The general principles that we used to determine the
Bevill status of these wastes include the following:
--Extraction and beneficiation ends just before chlorination occurs.
Wastes generated prior to this point are Bevill exempt, outside the
scope of the consent decree and therefore not addressed in this
rulemaking. The chlorinator marks the beginning of mineral
processing because the ore undergoes a physical/chemical change (see
54 FR 36619, September 1, 1989). 54 FR 36621 further notes,
``Likewise, EPA considered titanium tetrachloride produced during
the titanium chloride [sic] process to be a saleable product; any
further processing subsequent to its production is considered to be
chemical manufacturing.''
--Mineral processing ends when titanium dioxide is produced in the
oxidation unit. Further steps are chemical manufacturing. The Agency
defines the beginning of oxidation as the beginning of chemical
manufacturing because the facility is using a saleable mineral
product, titanium tetrachloride, to produce titanium dioxide (see 54
FR 366211).
[[Page 55751]]
--The mineral processing exemption only covers solids from the
production of titanium tetrachloride. These solids, therefore, are
outside of the consent decree. At least six streams of solid-bearing
material leave the chlorination reaction area. The status of these
streams is as follows:
(1) Titanium tetrachloride going on for further production. All
wastes formed during further processing of this gaseous product
stream are chemical manufacturing wastes that are outside the scope
of the Bevill exemption.
(2) Solids removed from the gaseous titanium tetrachloride
stream. These solids are associated with the production of titanium
tetrachloride. These solids are typically slurried to impoundments
for storage or disposal and are Bevill-exempt (with one exception
described below).
(3) Waste acids. In 1990 and 1998 rulemakings for LDR Phase IV
(see 63 FR 28601), EPA took the position that the waste acids do not
meet the high-volume, low-toxicity test and thus are not exempt
mineral processing wastes.
(4) Gases going to scrubbers. Offgases from the chlorinators
pass through various air pollution control systems which generate
scrubber waters. In 1998, EPA stated that scrubber waters and
sludges from scrubber waters were not Bevill-exempt. However, as a
result of the information collection activities associated with
today's proposal, it is now clear to EPA that gases from the
chlorinator contain some solids from the chlorinator. We are
interpreting the exemption today to cover these particles when they
drop out of scrubber waters to form sludges. (Gas streams and
wastewaters are not Bevill exempt, even when they are carrying solid
particles from chlorinator.)
(5) Solids purged from the reactor. A purge stream from the
reactor may be taken to reduce silica levels in the reactor. This
stream is Bevill exempt.
(6) Recovered solids from the reaction area. Housekeeping
results in the collection of coke and ore solids from the vicinity
of the reaction area. These wastes are Bevill exempt.
In one case, the facility conducts some processing of their
ferric chloride waste acid (which is subsequently sold as a water
and wastewater reagent), and generates a solids stream. We consider
the processing that this facility conducts to be either an ancillary
process or chemical manufacturing, and thus the subsequent solids
stream is not generated from mineral processing and therefore is not
exempt.
What Is The Status of the Mineral Processing Exemption for ``Chloride
Waste Solids From Titanium Tetrachloride Production'?
As part of our waste characterization of the titanium dioxide
sector, we conducted analyses for chlorinated dibenzo-p-dioxins (CDDs)
and dibenzo-p-furans (CDFs). We were concerned that these compounds
might be present in the wastes as a result of the chlorination step
which occurs in the presence of coke, and in fact we found measurable
levels of these compounds in wastes from the chloride and chloride-
ilmenite processes. These data are presented in the Titanium Dioxide
Listing Background Document and associated analytical data reports in
the docket for today's notice. As explained in this background
document, we believe that these compounds are formed in the
chlorinator, and are predominantly associated with the exempt mineral
processing solids (additional details regarding this conclusion are
provided in the referenced background document). These compounds were
not assessed, however, as part of the rulemakings which established the
mineral processing exemptions, and so these results could present new
issues for these wastes if such compounds were found to pose
unacceptable risks. During the development of the mineral processing
exemption, EPA anticipated certain conditions might suggest the
appropriateness of re-opening these exemptions.\48\ We are considering
whether we should re-assess the status of these wastes as exempt
mineral processing wastes. Any reassessment of these wastes would
involve a separate analysis and opportunity for notice and comment.
---------------------------------------------------------------------------
\48\ ``If EPA finds that this exemption is not protective of
human health and the environment and if an examination of titanium
tetrachloride waste management shows any continuing or new problems,
the Agency will reconsider this subtitle D determination for
chloride process waste solids from titanium tetrachloride
production.'' 56 FR 273000, June 13, 1991.
---------------------------------------------------------------------------
How Did EPA Assess Mixtures of Exempt and Non-Exempt Wastes From the
Production of Titanium Dioxide?
There are a number of wastes from the titanium dioxide sector that
remain partially within the scope of the consent decree because they
are composed of both exempt and non-exempt solids. Because they are not
``100 percent exempt'' in composition, we have assessed their potential
impacts on the environment, and attempted to isolate the risks
associated with the non-exempt solids and wastewaters. Any assessment
of the CDD and CDF loading in exempt wastes will involve a separate
analysis and opportunity for notice and comment.
Finally, we are assessing one non-exempt waste generated at the
Delaware facility, non-exempt non-wastewaters from the chloride-
ilmenite process, which contains some CDDs and CDFs at levels exceeding
our initial screening criteria. We did not, as part of today's listing
determination, conduct sufficient risk assessment to fully evaluate the
potential for risks. See section III.F.14.e(10) below.
5. Agency Evaluation
(1) Commingled wastewaters from the chloride process, including
wastewaters from coke and ore recovery, scrubber water, finishing
wastewaters and sludge supernatants.
How Many Facilities Generate This Waste Category and How Is It Managed?
Four facilities generated commingled wastewaters from the chloride
process. (As will be discussed further in III.F.14.e(7), two additional
facilities generate the same wastewaters and commingle them with
wastewaters from the sulfate process.) Three of the four ``chloride
only'' facilities treat their wastewaters in surface impoundment-based
treatment systems; the fourth facility uses a tank-based wastewater
treatment system. Each of the impoundment systems include unlined
units. These large volume wastes are generated in excess of 29 million
metric tons per year. These wastewaters are not Bevill-exempt (but
convey exempt solids into the wastewater treatment system where those
solids are removed to form sludges that are comprised of exempt solids
and non-exempt solids, depending on the specific piping of the plants).
Many facilities commingle waste hydrochloric acids (generated as
scrubber water) with their combined wastewaters. Three other
facilities, however, return waste acids on site or sell the acids for
reuse. Because these materials have no exposure route of concern, we
did not further evaluate risk scenarios associated with reuse of this
material.
What Management Scenarios Were Assessed?
For this rulemaking, we determined that the surface impoundment
scenario poses a more significant potential risk than the tank
scenario, and thus assessed the groundwater pathway for surface
impoundments. We assessed potential groundwater releases to both
surface water and drinking water wells. We concluded that the air
pathway does not present significant risks for these wastes because the
wastes do not contain volatile organics or other constituents that pose
risk due to air releases.
How Was This Waste Category Characterized?
One of the four facilities, located in Hamilton, Mississippi, was
selected for sampling and analysis. This facility's
[[Page 55752]]
waste is representative of the four chloride-only facilities. The
sample was collected at the inlet to this facility's surface
impoundment train.\49\ This sample contained a high level of solids,
reflecting the facility's practice of managing all waste solids
(including Bevill-exempt solids) and process wastewaters in the same
units which serve as settling ponds. To isolate the impact of the
wastewater on the environment from that of the sludge, we conducted the
SPLP on the waste matrix, and separately analyzed the filtrate and the
leachate generated from the leaching step. We are proposing to use the
filtrate analysis as representative of the wastewater portion of the
commingled waste matrix (see III.E.2 and 3 for further discussion on
the use of SPLP filtrate). The analytical results for the constituents
found to be present in the filtrate at levels exceeding HBLs and/or
AWQC are presented below in Table III-40 (the Titanium Dioxide Listing
Background Document contains the full set of analytical results).
---------------------------------------------------------------------------
\49\ This facility also commingles wastewaters from sodium
clorate production, which account for approximately 1.7 percent of
the total 4aste volume.
Table III-40.--Characterization of Commingled Wastewaters From Chloride
Process, Titanium Dioxide
------------------------------------------------------------------------
Detected levels in
Sample KM-SI-01 (mg/
L)
Constituent of concern ---------------------- HBL AWQC
SPLP
Total Filtrate
------------------------------------------------------------------------
Antimony.................... 0.05 0.044 0.006 0.014
Arsenic..................... 0.04 0.001 0.0007 0.000018
Manganese................... 25.9 0.46 0.73 0.05
Molybdenum.................. 0.53 0.23 0.078 NA
Thallium.................... 0.086 \1\ 0.005 0.001 0.0017
------------------------------------------------------------------------
\1\ Thallium is identified as a potential constituent of concern because
it was detected in the totals analysis at levels exceeding the HBL and
AWQC, and the SPLP filtrate analysis detection limit was too high to
confirm that mobile levels of thallium do not exceed these standards.
One half the detection limit was used as input to the risk assessment
(see III.E.3).
How Was the Groundwater-to-Surface Water Risk Assessment Established?
We assumed that surface impoundments present greater risks to the
environment than tanks. Therefore we focused on the 3 facilities that
manage wastewaters in impoundments. We selected the sampled facility
for modeling because (1) its management practices (i.e., treatment in
surface impoundments) are representative of 3 of the 4 chloride-only
facilities, (2) the analytical data for this waste were obtained from
this site, and (3) its setting is similar to the other 2 facilities
that use surface impoundments. The facility selected for modeling is
bounded on two sides by a river, tributary creeks, and swamps. The RCRA
Facility Assessment \50\ for this site provides maps showing distances
to these potential receptors and groundwater flow directions in the
vicinity of the surface impoundments and plant-wide flow directions,
with the overall flow being toward the river. We calculated
infiltration rates for the unlined impoundment, and divided this flow
rate into the flow rate of the river to determine potential
concentrations of the five metals of concern in the river as a result
of recharge with contaminated groundwater. The results of this
screening (see ``Risk Assessment Support to the Inorganic Chemical
Industry Listing: Background Information Document'') demonstrate that
concentrations of the constituents of concern are likely to be well
below risk thresholds for both human health and aquatic life in surface
water.
---------------------------------------------------------------------------
\50\ U.S. EPA RCRA Facility Assessment of Kerr McGee Chemical
Corporation; Hamilton, MS. June 16, 1995.
---------------------------------------------------------------------------
How Was the Groundwater Ingestion Risk Assessment Established?
We were able to collect specific information regarding the physical
setting of the modeled facility, and thus used primarily site-specific
data as input to the risk assessment. We chose this site for modeling
because the amount of available information best supported our data
requirements for modeling and because we believe this facility is
representative of other generators of this waste category in terms of
hydrogeological setting and waste characterization. Based on
information presented in the RFA for the facility of concern, as well
as from the U.S. Geological Survey Ground-water Site Inventory, there
are groundwater wells north of the plant. The RFA also indicates that
groundwater flow direction in the localized vicinity of the surface
impoundments is to the northwest. We modeled the potential impact of
the unlined portion of the surface impoundment train on drinking water
wells located within 2,000-5,000 feet (based on well locations and the
closest facility property lines). The resultant concentrations are
presented below in Table III-41.
Table III-41.--Groundwater Pathway Risk Assessment Results for Commingled Wastewaters From Chloride Process,
Titanium Dioxide
----------------------------------------------------------------------------------------------------------------
Risk or hazard quotient
---------------------------------------------------
Constituent of concern 90th% 95th%
---------------------------------------------------
Adult Child Adult Child
----------------------------------------------------------------------------------------------------------------
Antimony HQ................................................. 0.1 0.2 0.2 0.5
Arsenic cancer risk......................................... 2E-08 2E-08 8E-08 6E-08
Molybdenum HQ............................................... 0.03 0.07 0.06 0.1
[[Page 55753]]
Thallium HQ................................................. 0.02 0.03 0.03 0.07
----------------------------------------------------------------------------------------------------------------
What Is EPA's Listing Rationale for This Waste?
We propose not to list commingled wastewaters from the production
of titanium dioxide via the chloride process. The results of our risk
assessment show that this waste category does not pose significant risk
to human health and the environment. Our assessment of the air and
surface water exposure pathways shows no risk of concern. Our
assessment of the groundwater exposure pathway similarly shows no risk
of concern for the constituents of concern.
(2) Chloride process solids (Bevill exempt). Six facilities
generate waste solids from the chloride process. As previously
discussed, the Agency determined at 56 FR 27312 (June 13, 1991) that
chloride process waste solids from titanium tetrachloride production
are Bevill exempt mineral processing wastes (40 CFR
261.4(b)(7)(ii)(S)). Five of the six facilities generate their solids
in surface impoundments; the sixth, located in Louisiana, uses tank-
based settling to segregate the solids from their wastewaters. All six
facilities dispose of their solids in their surface impoundments or on-
site landfills. Approximately 1.2 million MT of this waste was
generated in 1998.\51\ The waste solids at each of these sites contains
contributions from Bevill exempt solids ranging from 100% to 40%, as
discussed further below.
---------------------------------------------------------------------------
\51\ This waste volume includes the non-exempt sulfate solids
generated at one of the 2 facilities that commingle wastes from the
chloride and sulfate processes.
---------------------------------------------------------------------------
At the two facilities located in Georgia and Louisiana, coke and
ore solids are generated as entirely segregated wastes that are not
commingled with non-exempt solids; these exempt wastes are clearly
outside the scope of the consent decree dictating today's proposal and
have not been assessed further.
At three other facilities, the facilities conduct some commingling
of their wastewaters, resulting in small potential contributions of
non-exempt solids to their waste solids. Two of these facilities, both
located in Ohio, commingle wastewaters from oxidation and finishing
(i.e., generated after the production of titanium tetrachloride and
therefore potentially bearing non-exempt solids) with the wastewaters
from titanium tetrachloride production that bear exempt solids. Neither
facility reported any solids in their oxidation and finishing
wastewaters, although data from similar wastewaters from the chloride-
ilmenite process indicate that very low levels of solids can be present
in similar wastewaters. (We assess solids from the chloride-ilmenite
process in section III.F.14.e(10) of this proposal.) At the third
facility (located in Mississippi), which operates a slightly different
process, there were no reported wastewaters or solids from oxidation
and finishing. Note that the wastewaters bearing the exempt solids at
this facility are commingled with comparatively small volumes of
wastewaters from sodium chlorate production (described in section
III.F.11 of today's proposal).\52\ We believe that the contribution of
any non-exempt solids to the volume of exempt solids from these three
facilities would be very small. Thus, we have chosen not to attribute
any risks to the nonexempt portion of these commingled solids.
---------------------------------------------------------------------------
\52\ The sodium chlorate wastewaters account for only 1.7% of
the total volume of managed wastewater, and for only 4.4% of the
solids generated. The predominant potential constituent of concern
in the sodium chlorate solids is chromium; analytical data for the
commingled solids (KM-SI-04) show that the SPLP concentration is
0.05 mg/L and not of concern. See section III.F.11 for further
discussion of this facility's sludge.
---------------------------------------------------------------------------
Two of the six facilities generating chloride process waste solids
also operate sulfate-based titanium dioxide production lines. These
plants are sited in Georgia and Maryland. Wastewaters from the chloride
process and sulfate processes are commingled and results in commingled
wastewater treatment solids that are partially composed of exempt
solids. The non-exempt wastewater treatment solids are described
separately in section III.F.14.e(8). They contain significant volumes
of non-exempt solids (>35%).
(3) Various sands from oxidation, milling and scouring.
How Many Facilities Generate This Waste Category and How Is It Managed?
Two facilities using the chloride process reported disposal of 250
MT of milling sand in off-site and dedicated on-site Subtitle D
landfills. One facility also reported landfilling over 2,300 MT of
scouring sand. One facility reported 6,935 MT/yr of waste oxidation
sand that is managed in an on-site industrial Subtitle D landfill. All
of these sands are similar and are associated with titanium dioxide
finishing operations. All of these sands are produced after the
beginning of chemical manufacturing and therefore are not exempt.
What Management Scenarios Were Assessed?
We assessed the off-site industrial landfill scenario for milling
sand and a dedicated on-site landfill for scouring sand, reflecting the
types of management reported for these wastes. We assessed the
groundwater ingestion pathway for these landfills. The on-site landfill
scenario for scouring sand screened out when we compared the SPLP
results for this waste directly to the HBLs.
How Was This Waste Category Characterized?
We collected samples of both the milling sand and the scouring
sand. We conducted total, TCLP and SPLP analyses on the waste matrix.
We used the SPLP results (rather than the TCLP) to assess potential
releases to groundwater because there is no contact with municipal
landfill leachate in the reported management practices, and no
indication that other practices are likely. The SPLP analytical results
of concern for the milling sand are presented below in Table III-42.
[[Page 55754]]
Table III-42.--Characterization of Milling Sand From Titanium Dioxide
Production
------------------------------------------------------------------------
Detected
SPLP
Constituent of concern levels in HBL (mg/
KP-SO-05 L)
(mg/L)
------------------------------------------------------------------------
Antimony............................................ 0.024 0006
------------------------------------------------------------------------
How Was the Groundwater Ingestion Risk Assessment Established?
As described in Section III.D.4. we used our standard distance-to-
well assumptions for an off-site landfill, and assumed hydrogeologic
conditions would be comparable to those for the reported off-site
landfill. As shown in Table III-43, the resultant risks were
calculated.
Table III-43.--Groundwater Pathway Risk Assessment Results for Milling
Sand From Titanium Dioxide Production
------------------------------------------------------------------------
Antimony HQ
-------------------------------------------------------------------------
Adult Child
Percentile risk risk
------------------------------------------------------------------------
90th.................................................... 0.003 0.006
95th.................................................... 0.008 0.02
------------------------------------------------------------------------
What is EPA's Listing Rationale for This Waste?
We propose not to list this waste because the modeled and screening
risk for antimony, the sole constituent of concern, is well below a
hazard quotient of unity.
(4) Gypsum from the sulfate process.
How Many Facilities Generate This Waste Category and How Is It Managed?
The Maryland and Georgia facilities generate this waste. Both sites
pipe their acid directly to their gypsum plants where it is neutralized
to form gypsum. We found no significant potential for release of this
acid waste prior to its treatment in the gypsum plant. The two
facilities reported production of 69,500 MT/yr of gypsum that is
landfilled.\53\ We chose to look further at this material because it is
disposed of in a landfill and used in a manner constituting disposal
(i.e., as fertilizer), and because the generators conduct on-site land
placement (piles). Specifically, the Georgia facility places their
gypsum in piles prior to sale for use in agricultural chemicals,
cement, chemical products, and wall board. The Maryland facility
generates primary and secondary gypsum, both of which are also placed
in piles prior to use in wall board manufacture or disposal in an on-
site landfill. As described above, the gypsum is not an exempt mineral
processing waste because this sulfate process wastestream did not meet
the high volume/low toxicity criteria noted in 54 FR 36592 (September
1, 1989).
---------------------------------------------------------------------------
\53\ Additional volumes are used as products.
---------------------------------------------------------------------------
What Management Scenarios Were Assessed?
We assessed each of the reported management scenarios that involve
land placement: agricultural chemicals, cement, piles and landfills. We
evaluated potential releases to both air and groundwater. Samples were
collected at both facilities, and included both primary and secondary
gypsum samples at the Maryland site. The management scenarios were
assessed using the appropriate sample for the type of gypsum reported
for that scenario. All pathways screened out except for the landfill
scenario at the Maryland site. For the Maryland landfill we found
constituent concentrations at levels of potential concern for the
groundwater and surface water pathways. The primary gypsum contained
lower levels of leachable metals than the secondary gypsum; we focused
our modeling efforts on the higher volume secondary gypsum as it was
more likely to show risk when modeled and the management scenarios are
identical (they are placed in the same on-site industrial landfill).
The screening results are discussed further in the ``Titanium Dioxide
Listing Background Document for the Inorganic Chemical Listing
Determination,'' available in the docket for today's notice.
We assessed the landfill scenario for potential impacts to both
surface water and drinking water wells. The facility selected for
modeling is bounded to the north and east by the Patapsco River, which
is an estuary. The expected groundwater flow, while not characterized
definitively, is expected to be eastward, toward the river.\54\
---------------------------------------------------------------------------
\54\ See ``Update of the Hazardous Waste Groundwater Task
Force'', April 1998. Maryland Department of the Environment. RCRA
Operation and Maintenance Inspection of SCM Chemicals (now
Millennium Inorganic Chemicals, Inc.); Hawkins Point Plant;
Baltimore, MD. October 1994.
---------------------------------------------------------------------------
How Was This Waste Category Characterized?
We collected three samples of this waste for analysis. We conducted
total, TCLP and SPLP analyses on the waste matrices. We used the SPLP
results (rather than TCLP) to assess potential releases to groundwater
and surface water because there is no contact with municipal landfill
leachate in the reported management practices. We used total results to
assess potential air releases, and this pathway screened out. The SPLP
analytical results for the secondary gypsum that we used to assess
groundwater releases from landfilling are presented below in Table III-
44.
Table III-44.--Characterization of Secondary Gypsum from Sulfate
Process, Titanium Dioxide
------------------------------------------------------------------------
Detected
SPLP levels AWQC (mg/
Constituent of concern in MI-SO-03 HBL (mg/L) L)
(mg/L)
------------------------------------------------------------------------
Antimony......................... 0.055 0.006 0.014
Arsenic.......................... 0.0035 0.0007 0.000018
Manganese........................ 3.1 0.73 0.05
------------------------------------------------------------------------
[[Page 55755]]
How Was the Groundwater-to-Surface Water Risk Assessment Established?
We calculated infiltration rates for the unlined landfill, and
divided this flow rate into the flow rate of the river to determine
potential concentrations of the three metals of concern (see Table III-
44) in the river as a result of recharge with contaminated groundwater.
The results of this screening (available in the Risk Assessment
Background Document) demonstrate that concentrations of the
constituents of concern are expected to be well below risk thresholds
for human health and aquatic life in surface water.
How Was the Groundwater Ingestion Risk Assessment Established?
While we are not aware of any actual drinking water wells in the
vicinity of the Maryland facility, we were unable to determine
definitively that there are not private wells in use in the residential
area to the south of the facility, or that potentially contaminated
groundwater would not reach this neighborhood. We thus decided to model
potential exposure at this neighborhood. We modeled the potential
impact of the unlined landfill on drinking water wells located within
2,500-5,000 feet (based on distances to the nearest residential area).
The resultant risks were calculated and are summarized in Table III-45.
Table III-45.--Groundwater Pathway Risk Assessment Results for Secondary Gypsum from Sulfate Process, Titanium
Dioxide
----------------------------------------------------------------------------------------------------------------
Antimony HQ Arsenic--cancer risk Manganese HQ
-----------------------------------------------------------------------------------
Adult risk Child risk Adult risk Child risk Adult risk Child risk
----------------------------------------------------------------------------------------------------------------
90th........................ 0.23 0.49 6.E-07 4.E-07 0.1 0.2
95th........................ 0.35 0.75 1.E-06 1.E-06 0.1 0.3
----------------------------------------------------------------------------------------------------------------
What is EPA's Listing Rationale for This Waste?
We propose not to list gypsum from the sulfate process. The results
of our risk assessment demonstrate that there is no significant risk
associated with this material, and that it does not warrant control as
a listed hazardous waste. At the 95th percentile, the risks for
antimony (HQ=0.75) and arsenic (1E-6), approach levels at
which EPA considers listing wastes (HQ=1.0 and cancer
risk>10-6, respectively). We believe that our modeled
exposure scenario, while plausible, contains a number of conservative
assumptions that likely overstate these marginal risks. In particular,
our assumptions regarding groundwater flow direction (i.e., that a
contaminated plume from the landfill would flow to the south toward the
nearest residences, rather than due west toward the river) and the use
of groundwater for drinking water at these residences (records indicate
this community uses public water) may overstate actual risks.
(5) Digestion scrubber water from the sulfate process.
How Many Facilities Generate This Waste Category and How Is It Managed?
The Maryland and Georgia facilities reported generation of
digestion scrubber water from the sulfate process. The Maryland
facility manages this wastewater in a dedicated surface impoundment
after neutralization. The other facility commingles this wastewater
with other wastewaters from their chloride and sulfate processes. As
described above, the gypsum is not an exempt mineral processing waste
because this sulfate process wastestream did not meet the high volume/
low toxicity criteria noted in 54 FR 36592 (September 1, 1989). (See 40
CFR 261.4(b)(7)(ii).)
What Management Scenarios Were Assessed?
We assessed the waste in its commingled form as managed by the
Maryland facility, as described below in section III.F.14.e(7). We also
modeled the dedicated surface impoundment scenario using the physical
parameters describing the dedicated Georgia impoundment. This
impoundment is placed directly on the banks of a river, and thus we
were primarily concerned with potential releases to surface water. We
did not model a drinking water well scenario because there are no
constituents of concern in this wastewater at levels exceeding HBLs.
How Was This Waste Category Characterized?
We collected one sample of this waste for analysis. We conducted
total analyses (leaching was not conducted given the low levels of
percent solids in this waste), which are summarized below in Table III-
46 for the constituents of potential concern.
Table III-46.--Characterization of Digestion Scrubber Water from Sulfate
Process, Titanium Dioxide
------------------------------------------------------------------------
Detected
levels in MI-
Constituent of concern WW-03 (mg/ HBL (mg/L) AWQC (mg/L)
L)
------------------------------------------------------------------------
Aluminum...................... 0.58 16 0.087
Manganese..................... 0.58 0.73 0.05
Mercury....................... 0.0032 0.005 0.000050
------------------------------------------------------------------------
How Was the Groundwater-to-Surface Water Risk Assessment Established?
We calculated infiltration rates for the unlined surface
impoundment, and divided this flow rate into the flow rate of the river
to determine potential concentrations of the three metals of concern
(see Table III-46) in the river as a result of recharge with
contaminated groundwater. The results of this screening (available in
the Risk Assessment Background Document) demonstrate that
concentrations of the constituents of concern are likely to be
[[Page 55756]]
well below risk thresholds for human health and aquatic life in surface
water.
What is EPA's Listing Rationale for This Waste?
We propose not to list digestion scrubber water from the production
of titanium dioxide via the sulfate process. The results of our risk
assessment show that this waste category does not warrant listing as a
hazardous waste.
(6) Sulfate process digestion sludges.
How Many Facilities Generate This Waste Category and How Is It Managed?
The Maryland and Georgia facilities generate this sludge. The
Georgia facility manages it in a dedicated surface impoundment and the
Maryland facility places it in an on-site landfill. As described above,
the waste is not an exempt mineral processing waste because this
sulfate process wastestream did not meet the high volume/low toxicity
criteria noted in 54 FR 36592 (September 1, 1989). (See 40 CFR
261.4(b)(7)(ii).)
What Management Scenarios Were Assessed?
We assessed both management scenarios using the respective samples
collected at each facility. The surface impoundment scenario screened
out; the levels of constituents in the wastewater were below HBLs and
AWQC. We modeled the landfill scenario for potential releases to both
groundwater drinking wells and surface water.
How Was This Waste Category Characterized?
We collected one sample of this waste for analysis at the Maryland
facility. We conducted total, TCLP, and SPLP analyses. We used the SPLP
results as inputs to the on-site landfill, which are summarized below
in Table III-47 for the constituents of potential concern.
Table III-47.--Characterization of Digestion Sludge From Sulfate
Process, Titanium Dioxide
------------------------------------------------------------------------
Detected
SPLP Levels
Constituent of concern in MI-SO-02 HBL (mg/L) AWQC (mg/L)
(mg/L)
------------------------------------------------------------------------
Aluminum...................... 2.0 16 0.087
Antimony...................... 0.023 0.006 0.014
Copper........................ 0.37 1.3 0.0031
Iron.......................... 12.0 5 1
Lead.......................... \1\ 0.004 0.015 0.0025
Manganese..................... 0.36 0.73 0.05
Vanadium...................... 0.42 0.14
Zinc.......................... 0.30 4.7 0.12
------------------------------------------------------------------------
\1\ Results are less than the typical laboratory reporting limit, but
are greater than the calculated instrument detection limits.
How Was the Groundwater-to-Surface Water Risk Assessment Established?
We calculated infiltration rates for the landfill, and divided this
flow rate into the flow rate of the river to determine potential
concentrations of the three metals of concern (see preceding table) in
the river as a result of recharge with contaminated groundwater. Note
that this is the same Maryland landfill described elsewhere in
III.F.14.e(4) and (8). The results of this screening (available in the
Risk Assessment Background Document) demonstrate that concentrations of
the constituents of concern are likely to be well below risk thresholds
for human health and aquatic life in surface water.
How Was the Groundwater Ingestion Risk Assessment Established?
See the comparable discussion for the gypsum (III.F.14.e(4)). The
groundwater ingestion scenario was assessed for antimony and vanadium
because the detected SPLP concentrations exceeded their respective
HBLs. We did not assess the iron HBL exceedence because the HBL is at
or above the solubility limit in ground water under most conditions.
The resultant risks were calculated and are summarized in Table III-48.
Table III-48.--Groundwater Pathway Risk Assessment Results for Digestion Sludge From Sulfate Process, Titanium
Dioxide
----------------------------------------------------------------------------------------------------------------
Antimony HQ Vanadium HQ
---------------------------------------------------
Adult risk Child risk Adult risk Child risk
----------------------------------------------------------------------------------------------------------------
90th........................................................ 0.13 0.27 0.02 0.03
95th........................................................ 0.18 0.39 0.03 0.07
----------------------------------------------------------------------------------------------------------------
What Is EPA's Listing Rationale for This Waste?
We propose not to list this waste. The results of our risk
assessment modeling show that this waste does not contain mobile metals
that are likely to pose risk to human health and the environment due to
transport through the subsurface.
(7) Commingled wastewaters from the chloride and sulfate process.
How Many Facilities Generate This Waste Category and How Is It Managed?
The Maryland and Georgia facilities generate this waste category.
Both facilities neutralized their commingled wastewaters and manage
them in surface impoundments prior to NPDES discharge (but convey
exempt solids into the wastewater treatment system where those solids
are removed to form sludges that are comprised of exempt solids and
non-exempt solids, depending on the specific piping of the plants).
What Management Scenarios Were Assessed?
We collected samples at both facilities at the influent to their
surface impoundment trains. We screened the
[[Page 55757]]
risk at both facilities using the analytical data describing their
respective wastes. We concluded that the Georgia facility was not a
modeling candidate because none of the constituents detected in its
waste exceeded our health-based levels or the ambient water quality
criteria. At the Maryland facility, we modeled the surface impoundment
scenario using the physical parameters describing their unlined
impoundment. We assessed both the surface water and drinking water well
scenario.
How Was This Waste Category Characterized?
The sample contained a high level of solids, reflecting the
facility's practice of managing all waste solids and process
wastewaters in the same unit. To isolate the impact of the wastewater
on the environment from that of the sludge, we conducted the SPLP on
the waste matrix, and separately analyzed the filtrate and the leachate
generated from the leaching step. We are proposing to use the filtrate
analysis as representative of the wastewater portion of the commingled
waste matrix. The analytical results for the constituents found to be
present in the filtrate at levels exceeding HBLs and/or AWQC are
presented below in Table III-49.
Table III-49.--Characterization of Commingled Wastewaters From Chloride and Sulfate Process, Titanium Dioxide
[mg/L]
----------------------------------------------------------------------------------------------------------------
Detected levels in sample MI-
WW-04
Constituent of concern -------------------------------- HBL AWQC
Total SPLP Filtrate
----------------------------------------------------------------------------------------------------------------
Arsenic......................................... 0.022 0.005 (1) 0.0007 0.000018
Manganese....................................... 119 9.95 0.73 0.05
Thallium........................................ 0.005 0.004 0.001 0.0017
----------------------------------------------------------------------------------------------------------------
(1) 1/2 the detection limit was used as input to the risk assessment.
How Was the Groundwater-to-Surface Water Risk Assessment Established?
We calculated infiltration rates for the surface impoundment, and
divided this flow rate into the flow rate of the river to determine
potential concentrations of the two metals of concern (see preceding
table) in the river as a result of recharge with contaminated
groundwater. The results of this screening (available in the Risk
Assessment Background Document) demonstrate that concentrations of the
constituents of concern are likely to be well below risk thresholds for
human health and aquatic life in surface water.
How Was the Groundwater Ingestion Risk Assessment Established?
See the comparable discussion for the gypsum (III.F.14.e(4)). The
resultant risks were calculated and are summarized in Table III-50.
Table III-50.--Groundwater Pathway Risk Assessment Results for Commingled Wastewaters From Chloride and Sulfate
Processes, Titanium Dioxide
----------------------------------------------------------------------------------------------------------------
90th percentile 95th percentile
Constituent of concern ---------------------------------------------------
Adult Child Adult Child
----------------------------------------------------------------------------------------------------------------
Arsenic cancer risk......................................... 5E-08 3E-08 2E-07 1E-07
Manganese HQ................................................ 0.009 0.02 0.02 0.04
----------------------------------------------------------------------------------------------------------------
What Is EPA's Listing Rationale for This Waste?
We propose not to list commingled wastewaters from the production
of titanium dioxide from the chloride and sulfate processes. The
results of our risk assessment demonstrate that this waste category
does not pose risks warranting listing as hazardous waste. Arsenic
levels at the receptor result in cancer risks well below 1E-06, and
manganese levels at the receptor are similarly well below a hazard
quotient of one.
(8) Wastewater treatment sludges from commingled chloride-and
sulfate-process wastewaters.
How Many Facilities Generate This Waste Category and How Is It Managed?
Two facilities, sited in Georgia and Maryland, generate this waste
category, and after de-watering, place their sludges in on-site
landfills. Over 159,000 MT of this waste was generated in 1998.
What Is the Bevill Exemption Status of This Waste Category?
As discussed above, the chloride process waste solids are exempt
mineral processing wastes, to the extent that they are associated with
the titanium tetrachloride process. Data provided by these two
facilities, however, show that these waste contain at least 35% non-
exempt solids. Our quantitative assessment of the potential risk
associated with these non-exempt solids is provided here.
The wastewater treatment solids at the Maryland site are derived
from at least four primary sources. Two residuals from the chloride
process contribute exempt solids (i.e., solids slurry and scrubber
water from the reaction area) as identified in 261.4(b)(7)(ii)(S) and
discussed above in III.F.14.e(2). Two scrubber waters from the
calcination \55\ and finishing portion of the sulfate process
contribute non-exempt solids to the wastewater treatment solids
(sulfate process wastes
[[Page 55758]]
are not exempt because, as described above, the sulfate process
wastestreams did not meet the high volume/low toxicity criteria noted
in 54 FR 36592 (September 1, 1989)). Additional potential sources of
minor amounts of solids are other wastewaters that are treated in this
facility's wastewater treatment system, including cooling water,
stormwater, drainage water and landfill leachate. Based on the
information reported in this facility's Sec. 3007 survey response, we
estimate that their wastewater treatment solids are more than 35% non-
exempt.
---------------------------------------------------------------------------
\55\ Although wastes from calcining are generally treated as
Bevill exempt extraction/beneficiation wastes, wastes from titanium
dioxide calcination are post-mineral processing, chemical
manufacturing wastes. The Agency noted at 54 FR 36619, ``As
discussed in the April NPRM, the Agency considers any operations
following the initial [mineral] processing operation to be [mineral]
processing operations, regardless of whether the activity was
included on the list of RTC beneficiation activities or has
traditionally been considered beneficiation.'' Therefore, since
mineral processing ends and chemical manufacturing starts at the
beginning of oxidation, and the calcining step occurs after
oxidation, all wastes generated from the calcining step are non-
exempt wastes.
---------------------------------------------------------------------------
The wastewater treatment solids at the Georgia site are derived
from at least six sources. Two residuals from the chloride process
contribute exempt solids (i.e., waste acid from the chloride reaction
area and supernatant from the chloride solids impoundment)
(261.4(b)(7)(ii)(S)). Finishing wastewaters from the chloride process
contribute non-exempt solids (these wastewaters are generated from the
chemical manufacturing end of the production process). At least three
wastewaters from the sulfate process contribute non-exempt solids.
Based on the information reported in this facility's Sec. 3007 survey
response, we estimate that their wastewater treatment solids are
significantly more than 35% non-exempt.
What Management Scenarios Were Assessed?
We collected samples of both facilities' wastes and therefore
assessed the management practices at the two sites individually. The
Maryland facility treats its wastewater in surface impoundments; the
sludge is generated from a filter press, and the facility then places
the sludge in an on-site landfill. We assessed potential groundwater
releases to both surface water and drinking water wells from this
landfill. The Georgia facility dredges its sludge from its surface
impoundments, filter presses the solids, places the filter solids in
piles for further drainage and air drying, and then places the filter
solids in an industrial on-site landfill. We assessed the groundwater
pathways for the landfill and pile, and the air pathway for the pile.
(Note that we elsewhere assess the groundwater impact of the Maryland
surface impoundments using sampling data for the wastewater in that
unit. See III.F.14.e(7)). All pathways for the Georgia facility
screened out and are not discussed further in this notice (see the
``Titanium Dioxide Listing Background Document for the Inorganic
Chemical Listing Determination'' for details of this screening).
How Was This Waste Category Characterized?
Both facilities were selected for sampling and analysis. Both
samples were collected from filter cake discharge of the filter press.
We conducted total, TCLP and SPLP analyses on the waste matrix. We used
the SPLP results (rather than the TCLP) to assess potential releases to
groundwater and surface water because there is no potential for contact
with municipal landfill leachate in the reported management practices
for these two facilities. Given the large waste quantities reported for
this category, we believe it would be prohibitively expensive for off-
site disposal to occur. We used total results to assess potential air
releases from the piles, and found no significant risks. The SPLP
analytical results used to assess groundwater releases at the Maryland
facility that generates commingled chloride/sulfate wastewater
treatment sludge (as described in the previous paragraph) are presented
below in Table III-51.
Table III-51.--Characterization of Commingled Wastewater Treatment
Sludges From Chloride and Sulfate Processes, Titanium Dioxide
------------------------------------------------------------------------
Detected
SPLP levels AWQC (mg/
Constituent of concern in MI-SO-01 HBL (mg/L) L)
(mg/L)
------------------------------------------------------------------------
Aluminum......................... 0.24 16 0.087
Arsenic.......................... \1\ 0.00005 0.0007 0.000018
Manganese........................ 2.63 0.73 0.05
Thallium......................... \1\ 0.003 0.001 0.0017
------------------------------------------------------------------------
\1\ Estimated results are less than the typical laboratory reporting
limit, but are greater than the calculated instrument detection
limits.
In addition to the metals described above, our analytical data show
that this waste contains polychlorinated dioxins and furans (PCDD/F).
These data are provided in the background document for the titanium
dioxide sector. As discussed previously (III.F.14.d), we believe that
these contaminants are clearly associated with the exempt solids
contained in this waste, and thus we did not assess them. Samples
collected at these two facilities bear out this association with the
exempt solids. The Maryland facility, which does not segregate any of
its exempt solids from other wastewater treatment solids, has
significantly higher PCDD/F levels than the Georgia facility (i.e.,
several orders of magnitude), which segregates the majority of its
exempts solids from its wastewater treatment solids.
How Was the Groundwater-to-Surface Water Risk Assessment Established?
The Maryland facility selected for modeling this scenario was also
modeled for several other wastes, and is described further in section
III.F.14.e(5) above. We calculated infiltration rates for the unlined
landfill, and divided this flow rate into the flow rate of the river to
determine potential concentrations of the four metals of concern (see
preceding table) in the river as a result of recharge with contaminated
groundwater. The results of this screening (available in the Risk
Assessment Background Document) demonstrate that concentrations of the
constituents of concern are likely to be well below risk thresholds in
surface water.
How Was the Groundwater Ingestion Risk Assessment Established?
The facility selected for modeling this scenario was also modeled
for several other wastes, and is described further in section
III.F.14.e(4) above. The resultant risks were calculated and are
summarized in Table III-52.
[[Page 55759]]
Table III-52.--Groundwater Pathway Risk Assessment Results for Commingled Wastewater Treatment Sludges From
Chloride and Sulfate Processes, Titanium Dioxide
----------------------------------------------------------------------------------------------------------------
Manganese HQ Thallium HQ
-------------------------------------------------------
Adult risk Child risk Adult risk Child Risk
----------------------------------------------------------------------------------------------------------------
90th.................................................... 0.1 0.3 0.1 0.3
95th.................................................... 0.2 0.5 0.2 0.4
----------------------------------------------------------------------------------------------------------------
What Is EPA's Listing Rationale for This Waste?
We are proposing not to list commingled wastewater treatment
sludges from chloride and sulfate processes because our modeling of
potential groundwater releases shows no risk at levels which warrant
listing this waste as hazardous. No scenario modeled (groundwater-to-
surface water and groundwater-to-drinking water wells) showed risk at
levels of regulatory concern.
(9) Waste acid (ferric chloride) from the chloride-ilmenite
process.
How Many Facilities Generate This Waste Category and How Is It Managed?
All three facilities that utilize the chloride-ilmenite process
generate this waste category. The DeLisle, Mississippi facility
identifies the waste as characteristic for corrosivity, chromium and
lead and disposes of its waste in an on-site underground injection
well. The Tennessee facility pipes its ferric chloride to an on-site
sodium chloride plant. Both the Mississippi and Tennessee facilities
generate the majority of their exempt-mineral processing solids from
the filtration of this waste acid. The Delaware facility's process is
slightly different in that the majority of their exempt solids are
generated prior to the generation of the waste acid, and only a
relatively small portion of their solids are generated from the removal
of solids from this waste. The Delaware facility adds a processing
chemical to their waste acid, removes solids, stores the acid in tanks
(as well as an on-site surface impoundment when their tank capacity is
exceeded), and sells the acid to a broker for resale as a wastewater
and drinking water treatment reagent. However, EPA is not at this time
assessing whether the ferric chloride is a legitimate product. We did
not attempt to address this complex and site-specific issue in this
proposal. We note that the Delaware facility uses a surface impoundment
to store a portion of the ferric chloride prior to its sale as a water
and wastewater treatment reagent. EPA has often considered land-based
units, and impoundments in particular, to be associated with the
discard of wastes, rather than the storage of products, because of
their potential for releases to the environment.\56\ In addition, we
sampled the ferric chloride at the Delaware facility and found that it
contains a variety of metals, as well as some chlorinated dioxins and
furans. (See the background document for this sector for more details
on this sampling and analysis). These factors may lead to concerns
about the legitimacy of the use of this material as a drinking water
and wastewater treatment reagent. However, as explained below, we do
not need to resolve this issue to make a decision about listing ferric
chloride.
---------------------------------------------------------------------------
\56\ Surface impoundments pose essentially inherent risks of
groundwater contamination due to the hydraulic pressure created by
the contained liquids. Chemical Waste Management v. EPA, 919 F.2d
158, 166 (D.C. Cir. 1992). Material that is placed in a surface
impoundment, where it is capable of posing a substantial present or
potential hazard to human health or the environment when improperly
treated, stored, transported or disposed of or otherwise managed,
``by leaching into the ground, is `discarded material' and hence a
solid waste.'' (AMC II, 907 F.2d) Although secondary materials may
have value and be reused, their value does not protect them from
being considered solid wastes for the purposes of RCRA regulation if
they are discarded prior to use (API, 906 F.2d at 741 n.16).
---------------------------------------------------------------------------
This waste routinely exhibits the characteristic of corrosivity and
the toxicity characteristic for chromium and lead. All three generators
of the ferric chloride waste acid acknowledge the hazardous nature of
this waste. Each generator reported pH levels at 1 or less, and the one
facility that disposes of this waste via deep well injection assigns
three separate characteristic codes to this material. EPA sampled the
ferric chloride at the Delaware facility, and both EPA and the facility
analyzed the waste. The results showed that this material exhibits the
characteristics of D001, D007, and D008.
What Is the Bevill Status of This Waste?
Ferric chloride waste acid is a liquid mineral processing waste
that did not meet the high volume/low toxicity criteria for determining
eligibility for the Bevill exemption and therefore is not Bevill-exempt
(see 63 FR 28601).
What Is the Bevill Status of Solids Removed From This Waste?
Prior to disposal or reuse of their waste acids, both the
Mississippi and Tennessee plants filter their waste acid to remove the
exempt solids. At the Delaware site, however, the waste acid is
processed via the addition of a chemical prior to solids removal. The
purpose of the chemical addition is to modify the properties of the
waste acid to enhance its value as a saleable potable water and
wastewater treatment reagent.
The addition of this chemical at the Delaware plant marks the end
of titanium tetrachloride production (i.e., mineral processing) and the
beginning of ferric chloride production (assuming ferric chloride is a
legitimate product). Ferric chloride production can be considered
either chemical manufacturing \57\ or an ancillary process.\58\
Consequently, as explained below in section III.F.14.e(10), solids
removed from the ferric chloride at the Delaware plant are not Bevill-
exempt.
---------------------------------------------------------------------------
\57\ 54 FR 36616, September 1, 1989.
\58\ All wastes from ancillary activities are not uniquely
associated with extraction/beneficiation and processing of ores and
minerals (see 45 FR 76619, November 19, 1980, and 63 FR 28590, May
26, 1998).
---------------------------------------------------------------------------
What Is EPA's Listing Rationale for This Waste?
We are proposing to not list this waste and rely instead on the
existing regulatory controls provided by the hazardous waste
characteristics. Data from all three facilities clearly demonstrates
that this waste exhibits several of the characteristics. At this time
we have not determined whether any of the facilities are out of
compliance. State and EPA authorities are examining these sites in
detail for compliance with the existing regulations. Listing would not
serve to better establish this jurisdiction.
The Mississippi facility that injects this waste identifies the
waste as hazardous and manages it as a hazardous waste under Subtitle C
regulations. Within the context of this consent decree, we did not
investigate in depth the Tennessee facility's use of this material in
production of sodium
[[Page 55760]]
chloride (an inorganic chemical not identified as one of the 14
products of concern in the consent decree) because there was no known
exposure route associated with the management of the material prior to
inserting it into a non-consent decree production process. As discussed
previously, the Delaware facility stores the material in a surface
impoundment. EPA can address concerns, if appropriate, by the use of
enforcement, based on the existing characteristics associated with this
material. In addition, the questions framed above about the potential
legitimacy of this facility's use of ferric chloride as a product and
its storage in a surface impoundment are equally relevant whether the
ferric chloride is listed as a hazardous waste or is known to exhibit
the characteristics of hazardous waste. Therefore we have decided to
not list this waste as a hazardous waste and rely on the hazardous
characteristics of the material for any necessary control.
(10) Non-exempt nonwastewaters from the chloride-ilmenite process.
How Many Facilities Generate This Waste Category and How Is It Managed?
All three chloride-ilmenite facilities generate wastes that contain
commingled exempt and non-exempt components. Depending on the specific
configuration of the individual plants, these wastes are composed to
different degrees of exempt and non-exempt solids, as described further
below.
Solids are generated in several places in the chloride ilmenite
process:
--Coke and ore solids are removed from the gaseous titanium
tetrachloride product stream, quenched and neutralized. While the
Agency believes this stream is largely exempt, we note that any
contributions to this stream from the disposal of the vanadium waste is
non-exempt.
--Solids are generated during wastewater treatment and are non-exempt
to the extent they are generated from oxidation and finishing
wastewaters.
--Coke and ore solids can also be generated from the removal of solids
from waste acid. These residuals may contain a non-exempt portion if
they are partially comprised of vanadium waste. These solids cannot be
exempt if they are removed from the waste acid after the initiation of
chemical manufacturing and/or ancillary operations.
We assessed these various sources of non-exempt materials as one
waste category because of the expected similarities among these
materials and the commingled management practices used by these
facilities. The total non-exempt portion of this waste category is
approximately 10% with variations among the three sites. The specific
sources of non-exempt materials for each of the three chloride-ilmenite
facilities is described below.
All three facilities generate non-exempt vanadium waste when they
separate vanadium compounds from titanium tetrachloride. The facilities
reinsert these materials into the reaction area. Titanium tetrachloride
is recovered and maybe reused; however, the remainder of this waste is
not reused and is incorporated into the unreacted coke and ore solids
stream from the reaction area, the solids separated from the ferric
chloride, or the ferric chloride. This vanadium waste is not exempt
because it is not a solid. However we were not able to determine the
volume contribution of this vanadium waste to the various wastes into
which it is ultimately incorporated. Hence, the estimates of total
exempt solids provided below are likely to be underestimated. (This
waste is also discussed in III.F.14.e(14) below.)
The Delaware facility combines and neutralizes three sources of
solids (reactor solids, solids removed from ferric chloride waste acid,
and solids from wastewater treatment), and markets the resulting
material as ``Iron Rich'' material. As asserted by the company, uses of
Iron Rich include structural fill, landfill caps and covers, and
construction of dikes for containment of dredged spoils on the Delaware
River. The facility may also stabilize some portion of the Iron Rich
with fly ash prior to sale. Each component of the Delaware commingled
residuals is described in the following paragraphs.
The majority of the commingled Delaware solids are unreacted coke
and ore materials that are removed from the gaseous titanium
tetrachloride product stream after the reactor. These ``reactor
solids'' make up more than 80% of the volume of commingled ``Iron
Rich'' at this facility. This stream is comprised of exempt chloride
process solids and non-exempt vanadium waste.
The Delaware facility also removes solids from its ferric chloride.
This solids removal step takes place after the facility incorporates a
chemical additive into the ferric chloride. We have concluded that the
use of this chemical constitutes chemical processing that is outside
the scope of the Bevill exemption (see 54 FR 36592, September 1, 1989
and previous waste acid discussion in III.F.14(e)(9)). In addition,
this stream is partially derived from the Delaware facility's non-
exempt vanadium waste. These ferric chloride solids are not exempt.
They make up approximately 10% of the commingled ``Iron Rich''.
The Delaware facility also uses scrubbers at various points in its
process. Some solids make their way into scrubber waters. When the
facility treats these wastewaters, the solids precipitate and the
resultant wastewater treatment solids are added to the two wastes
described above to form ``Iron Rich''. Solids from the scrubber used to
treat gasses from the titanium tetrachloride reactor are Bevill-exempt.
Solids from scrubbers associated with oxidation and finishing (steps
that take place after the formation of titanium tetrachloride) are not
exempt. Based on facility data, we estimate that approximately 1.5% of
the total volume of ``Iron Rich'' consists of non-exempt solids from
wastewater treatment.
The Tennessee facility generates solids from ferric chloride
filtration and from wastewater treatment. The filter solids are exempt
(261.4(b)(7)(ii)(S)) because such filtration simply removes exempt
solids. Unlike the processing that occurs at the Delaware plant, no
chemical manufacturing is taking place at this step at the Tennessee
plant. The facility landfills these ferric chloride solids as a
discrete wastestream; we do not assess this exempt waste further in
this rule. This facility commingles wastewaters from both the titanium
tetrachloride and titanium dioxide sides of the process, and the
resultant wastewater treatment sludge is thus comprised of exempt and
non-exempt sources. The Tennessee facility reported estimated percent
solids data for most of their wastewaters. We reviewed these data and
determined that a significant portion (74%) of the resultant sludge
would be nonexempt (see Titanium Dioxide Listing Background Document
for calculations). These nonexempt solids are within the scope of
today's proposal. We sampled the commingled exempt and nonexempt waste
and describe our assessment of this material in this section.
The Mississippi facility also generates exempt solids from
filtering ferric chloride prior to deep well injection. No chemical
manufacturing occurs. These solids are placed in a dedicated on-site
landfill, and are not assessed further in this rule. The facility also
operates a wastewater treatment system which is similar to the
Tennessee facility in that it commingles wastewaters from condensation
and purification (associated with the titanium tetrachloride production
process), as well as oxidation and finishing
[[Page 55761]]
(associated with the titanium dioxide production process). The
commingled wastewaters are managed in on-site surface impoundments and
the dredged solids from these units (comprised of exempt and nonexempt
materials) are placed in an on-site landfill. The facility provided
detailed information regarding the amounts of solids present in each of
the wastewaters managed in this system, demonstrating that there is a
small contribution (3%) of non-exempt solids (i.e., solids
in wastewaters from oxidation and finishing) in the wastewater
treatment sludge. We did not select this facility for site visits and
thus did not sample this waste. We believe our sampling and modeling of
the Tennessee and Delaware sites is an appropriate surrogate for this
waste given the similar nature of the processes at the three facilities
(with particular similarities between the wastewater treatment
facilities at Mississippi and Tennessee). Furthermore, the percentages
of non-exempt solids in the commingled wastes at the Tennessee and
Delaware sites are higher than at the Mississippi site.
What Management Scenarios Were Assessed?
The Delaware facility asserts that there are a variety of end uses
for the Iron Rich. The predominant recent use has been for the
construction of dikes to contain dredged river sediments at U.S. Army
Corp of Engineer disposal sites in the vicinity of the titanium dioxide
plant. We assessed this scenario as comparable to an industrial D
landfill scenario. The Iron Rich has also been used as daily cover at a
municipal landfill (demonstration project) and as final cover for a
closed on-site landfill. These uses clearly constitute disposal. Other
proposed uses include use as subsidence fill at a closed municipal
landfill, structural fill by the local Port Authority, surcharge for
road bed compaction, and construction of a wildlife refuge at the site
of the closed on-site industrial landfill. These uses all involve
placement on the ground and also appear to also be uses that constitute
disposal (see 40 CFR 266.20). We chose to model risks for disposal in
an off-site industrial D landfill because this seemed to fit the
largest number of the varied potential disposal or land-based use
scenarios. We believe the municipal landfill scenario is also relevant.
Our assessment addresses the municipal scenario qualitatively. These
scenarios were assessed for potential releases to drinking water wells
and air releases. In addition, we modeled the on-site landfill at the
Tennessee facility for potential releases to surface water.
How Was This Waste Category Characterized?
We collected samples of this waste at the Tennessee and Delaware
facilities. For the Tennessee facility, we collected the sample
directly from a holding/dewatering pond where the dredged wastewater
treatment solids are dewatered prior to landfilling on site. We
collected the sample from the Delaware facility directly from the Iron
Rich dewatering unit press; this sample consisted of commingled
chlorinator solids, ferric chloride solids, and wastewater treatment
solids. This material is sometimes mixed with fly ash prior to use; our
sample was collected prior to fly ash addition. Both samples were
analyzed for total, TCLP and SPLP constituent analyses. These data are
summarized below in Table III-54 for the constituents of concern that
were present in the wastes at levels exceeding the health-based levels
and/or ambient water quality criteria.
Table III-54.--Characterization of Wastewater Treatment Solids From the Chloride-Ilmenite Process, Titanium Dioxide
--------------------------------------------------------------------------------------------------------------------------------------------------------
Detected levels, Delaware site Detected levels, AWQC (mg/L) Soil
--------------------------------- Tennessee site ---------------------- screening
Constituent of concern ---------------------- HBL (mg/ levels
Total TCLP (mg/ SPLP (mg/ Total SPLP (mg/ L) Human Aquatic (mg/
(mg/kg) L) L) (mg/kg) L) health life kg)\1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Antimony............................................. 0.9 \2\ 0.021 0.02 0.7 0.021 0.006 0.014 n/a 32
Arsenic.............................................. 2.2 0.0035 \2\ 0.001 2.8 \3\ 0.003 0.0007 1.8E-05 0.15 4.7
5
Barium............................................... 178 \2\ 2.4 0.92 49.6 0.12 1.1 n/a n/a 5600
Boron................................................ 30 1.7 0.61 24.5 0.45 1.4 n/a n/a 7,200
Lead................................................. 309 \2\ 0.032 \2\ 0.003 42.4 \2\ 0.002 0.015 ......... 0.0025 400
2
Manganese............................................ 10,600 252 16.3 2,890 1.5 0.7 0.05 n/a \4\ 3,800
Nickel............................................... 91.8 0.5 0.005 59.8 0.007 0.31 0.61 0.052 1,600
Thallium............................................. 3.7 0.28 0.012 7.2 0.0022 0.001 0.0017 n/a 6.4
Vanadium............................................. 240 \2\ 0.000 0.005 1,060 0.005 0.14 n/a n/a 720
3
--------------------------------------------------------------------------------------------------------------------------------------------------------
n/a: not applicable.
\1\ Soil ingestion health-based levels.
\2\ Results are less than the typical laboratory reporting limit, but are greater than the calculated instrument detection limits.
\3\ One half the detection limit was used as model input.
\4\ The air characteristic level is 3,000 mg/kg at 25m and drops to 30,000 at 150m.
[[Page 55762]]
In addition, our analytical data show that chlorinated dioxins and
furans are present in these wastes. As discussed previously, we believe
these compounds are associated with the exempt solids. However, the
Delaware waste contains the ferric chloride solids; these solids have
lost their exempt status because of the facility's chemical
manufacturing/ancillary activities necessary for the production of
ferric chloride for sale as a water and wastewater treatment reagent.
As a result, we have considered the chlorinated dioxin and furan
content of the waste as part of today's listing determination. The
PCDD/PCDF analytical results for the Delaware site are summarized below
(detected homologs only) in Table III-55.
Table III-55.--Characterization of Wastewater Treatment Solids from the
Chloride-Ilmenite Process, Titanium Dioxide Chlorinated Dibenzo-p-
Dioxins (CDD) and Furans (CDF)
------------------------------------------------------------------------
Total
Detected
levels in
Constituent of concern Delaware
waste (ng/
kg, wet
basis)
------------------------------------------------------------------------
2378-TetraCDF.............................................. 12.2
12378-PentaCDF............................................. 21.8
23478-PentaCDF............................................. 48.1
123478-HexaCDF............................................. 237
123678-HexaCDF............................................. 8.1
234678-HexaCDF............................................. 2.5
123789-HexaCDF............................................. 5.6
1234678-HeptaCDF........................................... 189
1234789-HeptaCDF........................................... 126
OctaCDF.................................................... 24,000
OctaCDD.................................................... 22.2
2378-TetraCDD Equivalent\1\................................ 57.2
------------------------------------------------------------------------
\1\ 12378-TetraCDD equivalent calculated using the World Health
Organization Toxic Equivalency Factors (WHO-TEF). Van den Berg, et al.
1998. Toxic Equivalency Factors (TEFs) for PCBs, PCDDs, PCDFs for
Human and Wildlife. Environmental Health Perspectives, v.106, n.12,
pp. 775-792. December.
How Was the Groundwater-to-Surface Water Risk Assessment Established?
The Tennessee facility is bounded to the west by the Tennessee
River. The facility indicated that the overall groundwater flow is
toward the river. There have been several projects to determine
placement of down gradient monitoring wells for individual on-site
landfill units. These borings indicate that the groundwater elevation
declines to the northwest towards the river. In addition, a contract
geologist familiar with the local hydrogeology has indicated that
shallow groundwater flow will generally follow the natural topography.
A ridgeline running north and south is located just east of the
facility boundary. This ridge is approximately 200 feet higher in
elevation than the elevation at the facility. Based on this topography,
we expect that the groundwater flow direction is to the west towards
the river. We calculated the concentrations in the river that would
result from discharge of contaminated ground water by estimating the
infiltration rate for the unlined landfill, and (given the area of the
landfill) diluting the resulting leachate volume into the river under
various design flow conditions. The results of this screening level
analysis (available in the Risk Assessment Background Document)
demonstrate that concentrations of the constituents of concern in the
river are likely to be well below the national AWQC for human health
and aquatic life for these constituents.
How Was the Groundwater Ingestion Risk Assessment Established?
The Delaware facility reported actual or contemplated use of the
Iron Rich at a variety of landfills and land placement usages in the
general vicinity of the plant. We used our usual distance-to-well
assumptions for an off-site landfill, and assumed hydrogeologic
conditions that are representative of the principal soil and aquifer
types present regionally (within a 100 mile radius) of the facility.
The resultant risk assessment results are presented below in Table III-
56.
Table III-56.--Groundwater Pathway Risk Assessment Results for Non-wastewaters From Chloride-Ilmenite Process,
Titanium Dioxide
----------------------------------------------------------------------------------------------------------------
Hazard quotient or cancer risk
Constituents of concern -------------------------------------------------------
90th% adult 90th% child 95th% adult 95th% child
----------------------------------------------------------------------------------------------------------------
Antimony................................................ 0.2 0.5 0.4 0.8
Arsenic (cancer risk)................................... 3E-07 2E-07 1E-06 9E-07
Manganese............................................... 0.8 1.6 1.6 3.3
Thallium................................................ 0.7 1.4 1.1 2.4
----------------------------------------------------------------------------------------------------------------
What Is EPA's Listing Rationale for This Waste?
We propose to list as hazardous the non-exempt portion of the solid
wastes generated from the production of titanium dioxide via the
chloride-ilmenite process. This listing covers the non-exempt portions
of the wastewater treatment solids generated at all three facilities,
any non-exempt portions of the chlorinator solids (e.g., any mass
derived from the vanadium wastes), and ferric chloride solids generated
at the Delaware facility. To the extent that these listed materials
remain commingled with solids that would otherwise be exempt, the
entire commingled mass is subject to the listing (see
Sec. 261.3(b)(2)). Our risk results indicate that metals in these
materials leach at levels that may pose a risk to human health and the
environment. Specifically, in the commingled wastes, the risks exceed
an HQ of one for both manganese (3.3) and thallium (2.4) at the 95th
percentile; the risks similarly exceed an HQ of one for both manganese
(1.6) and thallium (1.4) at the 90th percentile.
In addition, the management practices reported for this waste,
particularly as reported for the Delaware site, are expected to provide
less control than the scenario modeled (i.e., an industrial landfill).
Potential future management practices include use at municipal
landfills for interim and final cover, as well as subsidence fill at a
closed municipal landfill. These scenarios, particularly the interim
cover scenario, indicate that the waste may come in contact with
municipal landfill leachate in the future, if not listed. The TCLP
results for this waste indicate even
[[Page 55763]]
higher mobility of metals than those modeled for the industrial
landfill scenario using the SPLP. The TCLP concentrations of manganese
and thallium exceed the SPLP levels by factors of 15-fold and 23-fold,
respectively. We expect, therefore, that HQs resulting from disposal in
a landfill with municipal waste would likely be higher by an order of
magnitude than the industrial landfill scenario we modeled.
The modeling presented above uses the entire waste volume reported
for the Delaware facility's Iron Rich. We used this volume because it
corresponds to the sample that we collected of this material, and there
is considerable uncertainty on the portion of the waste that would be
Bevill exempt. (This uncertainty is related to the estimated nature of
the solids contributions provided by the facilities and the variability
reported between the facilities.) We conducted a supplemental analysis
to determine how sensitive our modeling results are to changes in
volume, in recognition that we are only proposing at this time to list
approximately 10% of the current Iron Rich volume (the balance of the
Delaware site's waste being exempt and outside the scope of today's
listing determination). These results, presented below in Table III-57,
show that the risks are somewhat sensitive to the volume modeled, but
the risks are not reduced below EPA's HQ threshold of one for
noncarcinogens. In other words, if the facility were to segregate all
exempt solids from the materials being proposed for listing prior to
disposal, the remaining volume could still pose risk to human health
and the environment. Further, as noted above, based on the TCLP
results, the manganese and thallium HQs would be an order of magnitude
higher in a municipal landfill scenario.
Table III-57.--Reduced Volume Analysis; Groundwater Pathway Risk Assessment Results for Non-wastewaters From
Chloride-Ilmenite Process, Titanium Dioxide
----------------------------------------------------------------------------------------------------------------
Hazard quotient or cancer risk
Constituents of concern -------------------------------------------------------
90th % adult 90th % child 95th % adult 95th % child
----------------------------------------------------------------------------------------------------------------
Antimony................................................ 0.1 0.2 0.2 0.4
Arsenic................................................. not modeled
Manganese............................................... 0.5 1.0 1.0 2.2
Thallium................................................ 0.4 0.9 0.8 1.6
----------------------------------------------------------------------------------------------------------------
This waste also contains 57 ppt TCDD equivalents. This
concentration exceeds the background level in soils (8 ppt) and the
soil ingestion HBL of 45 ppt\59\. We were not able to compare this
concentration with a screening level from the Air Characteristics Study
because the study did not establish levels for TCDD. While we did not
conduct a risk assessment of the detected TCDD TEQ, the presence of
TCDD equivalents in the wastes is an additional factor that supports a
listing determination, particularly in light of the fact that the
management practices reported by the facility were varied and, in many
cases, would constitute releases to the circulating environment with a
greater potential for a variety of exposure pathways than would occur
from a well managed landfill.
---------------------------------------------------------------------------
\59\ EPA is currently evaluating the health risks from 2,3,7,8-
TCDD and once the review process is completed, EPA may re-examine
the soil ingestion HBL. See http://www.epa.gov.ncea.dioxin.htm for
additional information.
---------------------------------------------------------------------------
The proposed listing address all non-wastewaters that are not
covered by the mineral processing waste exemption, and is not limited
to non-exempt wastewater treatment solids. The listing therefore would
cover non-exempt non-wastewaters from the removal of vanadium wastes
from the product titanium tetrachloride stream that are currently
returned to the reaction area and ultimately commingled with the exempt
reactor solids or ferric chloride (these solids were part of the Iron
Rich sample collected by EPA to support this listing determination).
Similarly, at the Delaware facility, solids that collect in the ferric
chloride product storage tanks and impoundments would be covered by the
listing as these solids are ineligible for the mineral processing
exemption (because they are generated after the initiation of chemical
manufacturing and/or ancillary operations), they are comparable to the
ferric chloride solids that are commingled in the Iron Rich, and they
are derived to some degree from non-exempt vanadium materials. The
proposed listing, therefore, reads:
K178 Non-wastewaters from the production of titanium dioxide by the
chloride-ilmenite process. (T) [This listing does not apply to
chloride process waste solids from titanium tetrachloride production
exempt under section 261.4(b)(7)]
We are also proposing to add manganese and thallium to Appendix VII
to Part 261, which designates the hazardous constituents for which K178
would be listed. In addition, we are proposing to add manganese to the
list of hazardous constituents in Appendix VIII to Part 261. We believe
the available studies clearly show that manganese has toxic effects on
humans and other life forms.\60\
---------------------------------------------------------------------------
\60\ See information in EPA's IRIS database, which may be found
at http://www.epa.gov/iris, and ``Risk Assessment Support to the
Listing Determinations for the Inorganic Chemical Manufacturing
Wastes'' (August 2000) in the docket for today's rule.
---------------------------------------------------------------------------
(11) HCl from reaction scrubber, chloride-ilmenite process. All
three chloride-ilmenite facilities reported generating HCl from
scrubbing reactor off-gasses. These wastes are stored in covered tanks
with vent scrubbers and are re-used on site, predominantly as pH
control in wastewater treatment systems. We assessed this waste as part
of the following category, ``Commingled wastewaters from chloride-
ilmenite process''.
(12) Commingled wastewaters from the chloride-ilmenite process.
How Many Facilities Generate This Waste Category and How Is It Managed?
All three chloride-ilmenite facilities commingle their wastewaters
and treat them on-site. The Delaware facility utilizes a tank-based
system, with final NPDES discharge through an unlined cooling pond to
the adjacent river. Both the Tennessee and Mississippi facilities
utilized surface impoundment based wastewater treatment systems. These
wastewaters are not Bevill-exempt (but convey exempt solids into the
wastewater treatment system where those solids are removed to form
sludges that are comprised of exempt solids and non-exempt solids,
depending on the specific piping of the plants).
[[Page 55764]]
What Management Scenarios Were Assessed?
We modeled the surface impoundment scenarios at both the Tennessee
and Mississippi sites. (We assumed any releases from the unlined
cooling pond at the Delaware facility would be intercepted by the
river, and would be comparable in concentration, but much less volume
than the actual NPDES discharge point.)
At the Tennessee site, we assessed the potential releases from the
impoundment system to the adjacent river. We do not believe any
drinking water wells could possibly be impacted by these impoundments
given their placement on the river banks and within the facility
property. We sampled at this facility at the headworks to the
impoundment train.
We assessed the Mississippi facility's impact on both surface water
and potential drinking water wells. The RFI \61\ for this site
indicates that the local groundwater flow is generally toward the south
and east. It is unclear what the patterns are off site and how these
patterns might change seasonally, but the groundwater elevation maps
included in the RFI indicated that the direction of groundwater flow
does vary seasonally and that a shift to a more westerly direction may
occur under some conditions. Information from the U.S. Geological
Survey's Ground-water Site Inventory, available in the docket for
today's proposal, shows numerous drinking water wells in the vicinity
of the plant, both to the east and southwest. The facility also
reported wells on their property which they believe are cross-gradient
and, in some cases, unused. We chose to model the groundwater scenario
because of potential impacts on these known wells. We also assessed the
potential impact of the Mississippi facility's surface impoundments on
surface water because the facility is bounded to the south by the Bay
of St. Louis.
---------------------------------------------------------------------------
\61\ Draft RCRA Facility Investigation Report; DuPont DeLisle,
NS. December 7, 1999.
---------------------------------------------------------------------------
We did not conduct sampling and analysis at the Mississippi
facility. Our risk assessment inputs for this facility used the
combined analytical data set for the Delaware and Tennessee facilities,
which are sister plants of the Mississippi plant. We used the physical
parameters for the Mississippi site to describe wastewater flows,
surface impoundment sizes, and distances to potential receptors for
this modeling.
How Was This Waste Category Characterized?
The analytical results for the constituents found to be present in
the wastewaters at levels exceeding HBLs and/or AWQC are presented
below in Table III-58.
Table III-58.--Characterization of Commingled Wastewaters From Chloride-Ilmenite Process, Titanium Dioxide
----------------------------------------------------------------------------------------------------------------
Detected Detected
levels in levels in AWQC--Aquatic
Constituent of concern Delaware Tennessee HBL (mg/L) life (mg/L)
sample (mg/L) sample (mg/L)
----------------------------------------------------------------------------------------------------------------
Aluminum........................................ 0.65 3.1 16 0.087
Copper.......................................... 0.03 0.007 1.3 0.0031
Lead............................................ 0.003 0.005B 0.015 0.0025
Manganese....................................... 3.3 3.34 0.73 N/A
Nickel.......................................... 0.013 0.020 0.3 0.052
Thallium........................................ 0.005 0.013 0.001 N/A
Vanadium........................................ 0.018 0.63 0.14 N/A
----------------------------------------------------------------------------------------------------------------
B: also detected in blank
N/A: not available
How Was the Groundwater-to-Surface Water Risk Assessment Established?
The Tennessee facility is bounded to the west by a river. As noted
above, the facility indicated that the overall groundwater flow is
toward the river. The Mississippi facility is bounded to the south by
the Bay of St. Louis, which is fed by 2 rivers to the east and west of
the plant. Additional details are available in the docket. We
calculated the concentration in the river that would result from
discharge of contaminated groundwater by estimating the infiltration
rate for the unlined surface impoundment, and (given the area of the
impoundment) diluting the resulting leachate volume into the river
under various design flow conditions. The results of this screening
level analysis (available in Risk Assessment Support to the Inorganic
Chemical Industry Listing: Background Information Document'')
demonstrate that concentrations of the constituents of concern in the
river are likely to be well below the human health and aquatic life
AWQC for these constituents.
How Was the Groundwater Ingestion Risk Assessment Established?
Based on information presented in the RFI for the Mississippi
facility, as well as from the U.S. Geological Survey Ground-water Site
Inventory, there are groundwater wells to the east and southwest of the
plant within 2,000-5,000 feet. We modeled the potential impact of the
unlined surface impoundment train on drinking water wells located
within this range. The results are presented below in Table III-59.
[[Page 55765]]
Table III-59.--Groundwater Pathway Risk Assessment Results for Commingled Wastewaters From Chloride-Ilmenite
Process, Titanium Dioxide
----------------------------------------------------------------------------------------------------------------
Hazard quotient
Constituent of concern ---------------------------------------------------------------
90th % adult 90th % child 95th % adult 95th % child
----------------------------------------------------------------------------------------------------------------
Manganese....................................... 0.0002 0.0003 0.0003 0.0007
Thallium........................................ 0.002 0.004 0.004 0.009
Vanadium........................................ 0.00009 0.0002 0.0003 0.0006
----------------------------------------------------------------------------------------------------------------
What Is EPA's Listing Rationale for This Waste?
We propose not to list commingled wastewaters from the production
of titanium dioxide via the chloride-ilmenite process. The results of
our risk assessment demonstrate that this waste category poses no risks
that warrant listing as hazardous waste. The concentrations of the
constituents of concern at the modeled exposure points are well below
an HQ of one.
(13) Additive vent filter solids from the chloride-ilmenite
process. One facility reported production of vent filter solids from
additive handling. This material is placed in an off-site industrial D
landfill. Small amounts of this waste are generated (1 MT). This
material is not Bevill exempt. Handling of this additive is an
ancillary activity. All wastes from ancillary activities are not
uniquely associated with extraction/beneficiation and processing of
ores and minerals (see 45 FR 76619, November 19, 1980, and 63 FR 28590,
May 26, 1998).
Information from the facility indicates that a constituent of
concern in this material is aluminum. The drinking water HBL for
aluminum is higher than the solubility limit in ground water and,
therefore, contamination of ground water is not likely to pose a
significant risk to human health. Based on this fact, and the very
small volume generated by one facility, we propose not to list this
material as a hazardous waste.
(14) Vanadium waste from the chloride-ilmenite and chloride
process. Vanadium containing material is generated from the production
of titanium dioxide via the chloride and the chloride-ilmenite
processes. This is not an exempt mineral processing waste because it is
not a solid (see also 63 FR 28602). This waste is generally returned to
the reaction area where titanium tetrachloride is recovered and the
remainder of the vanadium waste is incorporated into the mass of the
unreacted coke and ore solids (i.e., the exempt solids) and/or the
waste acid. There is no potential for exposure prior to mixing with the
exempt waste or waste acid. We assessed the mixtures of exempt and non-
exempt wastes as discussed above in III.D.14.e(8) and (10).
Specifically, we assessed the wastewater treatment solids at the
Maryland facility, the Iron Rich material at the Delaware facility, and
the waste acid.
(15) Off-specification titanium dioxide product.
How Many Facilities Generate This Waste Category and How is it Managed?
Two facilities reported generating this waste, although we believe
that all titanium dioxide manufacturers may generate this waste at some
time. The two reporting facilities both describe off-site Subtitle D
landfills that accept both municipal and industrial wastes as the final
management practice for this waste. As noted in the September 1, 1989
Bevill rulemaking, off-specification commercial product wastes are non-
exempt solid wastes.
What Management Scenarios Were Assessed?
We modeled the off-site municipal D landfill scenario using the
regional locations of the reported landfills.
How Was This Waste Category Characterized?
We collected one sample of this waste and conducted totals, TCLP,
and SPLP analyses. The analytical results for the one constituent found
to be present in the waste TCLP sample at a level exceeding its HBL are
presented below in Table III-60 (no constituent exceeded HBLs in the
SPLP).
Table III-60.--Characterization of Off-specification Titanium Dioxide Product
----------------------------------------------------------------------------------------------------------------
Detected levels in sample DPN-
SO-02 (mg/L)
Constituent of concern -------------------------------- HBL (mg/L)
Total TCLP
----------------------------------------------------------------------------------------------------------------
Lead............................................................ 0.6 \1\ 0.06 0.015
----------------------------------------------------------------------------------------------------------------
\1\ Results are less than the typical laboratory reporting limit, but are greater than the calculated
instrument detection limits.
How Was the Groundwater Ingestion Risk Assessment Established?
The facilities reported use of landfills in the vicinity of their
plant. We used our usual distance-to-well assumptions for an off-site
landfill, and assumed hydrogeologic conditions that are representative
of the principal soil and aquifer types present regionally (within a
100 mile radius) for the particular landfill sites that were reported
for these wastes. The resultant groundwater concentrations were very
low and are presented below in Table III-61.
Table III-61.--Groundwater Pathway Risk Assessment Results for Off-specification Titanium Dioxide
----------------------------------------------------------------------------------------------------------------
Predicted well concentrations
(mg/L)
Constituent of concern -------------------------------- HBL (mg/L)
90th% 95th%
----------------------------------------------------------------------------------------------------------------
Lead............................................................ 2.5E-08 1.1E-06 0.015
----------------------------------------------------------------------------------------------------------------
[[Page 55766]]
The modeled levels of lead were so far below the HBL that we
determined it was unnecessary to further assess the risks from lead.
Clearly those risks would be well below an HQ of one.
What Is EPA's Listing Rationale for This Waste?
We propose not to list off-specification titanium dioxide as a
hazardous waste. Our risk analysis shows that this waste does not pose
risks that warrant listing.
(16) Railcar/trailer product washout. One facility reported
generation of this residual (10,000 MT). The washwater, containing
titanium dioxide, is placed in a surface impoundment. This waste is not
Bevill exempt because it is a liquid and it is associated with the
chemical manufacturing part of the process. The water from this pond is
subsequently sent to wastewater treatment where it is commingled with
all other chloride-ilmenite wastewaters (assessed in III.D.14.e(12)).
The titanium dioxide product that settles to the bottom of this pond is
mechanically recovered and returned to the production process. We
assessed the potential impact of this impoundment via the SPLP
analytical data collected for off-specification product (previously
discussed in III.D.14.e(15)). These data are available in the
background document for this sector, and show no constituents of
concern. We chose the SPLP to assess this management scenario because
there is no potential for contact with municipal landfill leachate. We
therefore do not propose to list this waste.
G. What Is the Status of Landfill Leachate From Previously Disposed
Wastes?
Leachate derived from the treatment, storage, or disposal of listed
hazardous wastes is classified as a hazardous waste by virtue of the
``derived-from'' rule in 40 CFR 261.3(c)(2). The Agency has been clear
in the past that hazardous waste listings apply to wastes disposed of
prior to the effective date of a listing, even if the landfill ceases
disposal of the waste when the waste becomes hazardous. (See 53 FR
31147, August 17, 1988). We also have a well-established interpretation
that listings apply to leachate derived from the disposal of listed
hazardous wastes, including leachate derived from wastes meeting the
listing description that were disposed before the effective date of a
listing. We are not reopening any of these issues with this proposed
rulemaking.
Of course, as set out in detail in the August 1988 notice, this
does not mean that landfills holding wastes that are listed now as
hazardous become subject to Subtitle C regulation. However, previously
disposed wastes now meeting a listing description, including residues
such as leachate that are derived from such wastes, and that are
managed actively do become subject to Subtitle C regulation. See 53 FR
at 31149, August 17, 1988. In many, indeed most, circumstances, active
management of leachate would be exempt from Subtitle C regulation
because the usual pattern of management is discharge either to POTWs
via the sewer system, where leachate mixes with domestic sewage and is
excluded from RCRA jurisdiction (see RCRA Section 1004(27) and 40 CFR
261.4(a)(1)), or to navigable waters, also excluded from RCRA
jurisdiction (see RCRA Section 1004(27) and 40 CFR 261.4(a)(2)). In
addition, management of leachate in wastewater treatment tanks prior to
discharge under the CWA is exempt from RCRA regulation (40 CFR
264.1(g)(6)).
If actively managed, landfill leachate and gas condensate derived
from the newly-listed wastes proposed for listing in today's proposal
could be classified as K176, K177, or K178. In such circumstances, we
would be concerned about the potential disruption in current leachate
management that could occur, and the possibility of redundant
regulation. This issue was raised to the Agency in the context of the
petroleum refinery waste listings (see 63 FR 42173, August 6, 1998). A
commenter expressed concern that, because some of the commenter's non-
hazardous waste landfills received newly-listed petroleum wastes prior
to the effective date of the listing decision, the leachate that is
collected and managed from these landfills would be classified as
hazardous. The commenter argued that this could lead to vastly
increased treatment and disposal costs without necessarily any
environmental benefit. After examining and seeking comment on this
issue, we published a final rule that temporarily defers regulation of
landfill leachate and gas condensate derived from certain listed
petroleum refining wastes (K169-K172) that were disposed before, but
not after, the new listings became effective, provided certain
conditions are met. See 64 FR 6806, February 11, 1999. Since then, we
have published proposed rules for wastes from the dye and pigment
industries (64 FR 40192, July 23, 1999) and the chlorinated aliphatics
industry (64 FR 46476, August 25, 1998) that also propose deferrals for
similar wastes derived from landfills.
At the time this issue was brought to the Agency's attention in the
context of the petroleum refinery waste listings, EPA's Office of Water
had recently proposed national effluent limitations guidelines and
pretreatment standards for wastewater discharges--most notably,
leachate--from certain types of landfills. See 63 FR 6426, February 6,
1998. In support of this proposal, EPA conducted a study of the volume
and chemical composition of wastewaters generated by both subtitle C
(hazardous waste) and subtitle D (non-hazardous waste) landfills,
including treatment technologies and management practices currently in
use. Most pertinent to finalizing the temporary deferral for the
petroleum refining wastes, EPA did not propose (or subsequently
finalize) pretreatment standards for subtitle D landfill wastewaters
sent to POTWs because the Agency's information indicated that such
standards were not required (see 65 FR 3008, January 19, 2000).
The conditions included in the temporary deferral we published on
February 11, 1999 are that the leachate is subject to regulation under
the Clean Water Act, and the leachate cannot be stored in surface
impoundments after February 13, 2001. See 40 CFR 261.4(b)(15). We
believe that it was appropriate to temporarily defer the application of
the new waste codes to such leachate in order to avoid disruption of
ongoing leachate management activities while the Agency decides if any
further integration is needed of the RCRA and CWA regulations
consistent with RCRA Section 1006(b)(1). We believe that it is still
appropriate to defer regulation and avoid leachate management
activities, and to permit the Agency to decide whether any further
integration of the two programs is needed. As such, we would be
concerned about forcing pretreatment of leachate even though
pretreatment is neither required by the CWA, nor needed. Therefore, we
are proposing to temporarily defer the regulation of landfill leachate
and gas condensate derived from the wastes we are proposing for listing
in today's rule, with the same conditions as described in 40 CFR
261.4(b)(15) for petroleum wastes. We seek comment on our proposed
decision to extend the temporary deferral to include the wastes
proposed for listing in today's notice.
[[Page 55767]]
IV. Proposed Treatment Standards Under RCRA's Land Disposal
Restrictions
A. What Are EPA's Land Disposal Restrictions (LDRs)?
RCRA requires us to establish treatment standards for all wastes
destined for the land disposal. These are the ``land disposal
restrictions'' or LDRs. For any hazardous waste identified or listed
after November 8, 1984, we must promulgate these LDR treatment
standards within six months of the date of identification or final
listing (RCRA Section 3004(g)(4), 42 U.S.C. 6924(g)(4)). RCRA also
requires us to set as these treatment standards ``* * * levels or
methods of treatment, if any, which substantially diminish the toxicity
of the waste or substantially reduce the likelihood of migration of
hazardous constituents from the waste so that short-term and long-term
threats to human health and the environment are minimized.'' (RCRA
Section 3004(m)(1), 42 U.S.C. 6924(m)(1)).
Once a hazardous waste is prohibited from land disposal, the
statute provides only two options for legal land disposal: Meet the
treatment standard for the waste prior to land disposal, or dispose of
the waste in a land disposal unit that satisfies the statutory no
migration test. A no migration unit is one from which there will be no
migration of hazardous constituents for as long as the waste remains
hazardous. RCRA sections 3004 (d), (e), (f), and (g)(5). Each waste
identified for listing as hazardous in this rule will be subject to all
the land disposal restrictions on the same day their respective listing
becomes effective.
We gathered data on waste characteristics and current management
practices for wastes proposed to be listed in this action. These data
can be found in the administrative record for this rule. An examination
of the constituents that are the basis of the proposed listings shows
that we have previously developed numerical treatment standards for
most of the constituents. We have determined that it is technically
feasible and justified to apply existing universal treatment standards
(UTS) to the hazardous constituents in the wastes proposed to be listed
as K176, K177, and K178 that were found to be present at concentrations
exceeding the treatment standards, because the waste compositions are
similar to other wastes for which applicable treatment technologies
have been demonstrated. Also see LDR Phase II final rule, 59 FR 47982,
September 19, 1994, for a further discussion of UTS. A list of the
proposed regulated hazardous constituents and the proposed treatment
limits can be found in the following preamble sections and in the
proposed regulatory Table 268.40--Treatment Standards for Hazardous
Wastes. If we make a final decision to list the identified wastes,
these constituents and treatment standards would apply.
We have provided in the BDAT background document a review of
technologies that can be used to meet the proposed numerical
concentration limits for K176, K177, and K178, assuming optimized
design and operation. Where we are proposing numerical concentration
limits, the use of other technologies capable of achieving the proposed
treatment standards would be allowed, except for those treatment or
reclamation practices constituting land disposal or impermissible
dilution (see 40 CFR 268.3).
B. What Are the Treatment Standards for K176 (Baghouse Filters From
Production of Antimony Oxide)?
The constituents identified to require treatment in this waste are
antimony, arsenic, cadmium, lead, and mercury. We are proposing to
apply the UTS levels to these constituents as the treatment standards.
Therefore, the nonwastewaters treatment standard proposed for antimony
is 1.15mg/L TCLP; arsenic is 5.0 mg/L TCLP; cadmium is 0.11 mg/L TCLP;
lead is 0.75 mg/L TCLP; and, mercury is 0.025 mg/L TCLP. In the event
that there are wastewater treatment residuals from treatment of K176
(which under the derived-from rule would also be considered as K176),
the wastewater treatment standards are as follows: Antimony is 1.9 mg/
L; arsenic is 1.4 mg/L; cadmium is 0.69 mg/L; lead is 0.69 mg/L; and,
mercury is 0.15 mg/L.
We are requesting data and comment on the stabilization of
antimony. Available stabilization data for antimony show effective
treatment for wastes with initial antimony concentrations below those
found in K176. Therefore, based on the available data, we are uncertain
if stabilization will be effective for the antimony in this waste.
C. What Standards Are the Treatment Standards for K177 (Slag From the
Production of Antimony Oxide That is Disposed of or Speculatively
Accumulated)?
The constituents identified to require treatment in this waste are
antimony, arsenic, and lead. We are proposing to apply the UTS levels
to these constituents as the treatment standards. Therefore, the
nonwastewater treatment standard for antimony is 1.15 mg/L TCLP, for
arsenic is 5.0 mg/L TCLP, and for lead is 0.75 mg/L TCLP. In the event
that there are wastewater treatment residuals from treatment of K177
(which under the derived-from rule also would be considered K177), the
wastewater treatment standard for antimony is 1.9 mg/L, for arsenic is
1.4 mg/L, and for lead is 0.69 mg/L.
We are requesting data and comment on the stabilization of
antimony. Available stabilization data for antimony show effective
treatment for wastes with initial antimony concentrations below those
found in K177. Therefore, based on the available data, we are uncertain
if stabilization will be effective for the antimony in this waste.
D. What Are the Treatment Standards for K178 (Nonwastewaters From the
Production of Titanium Dioxide by the Chloride-Ilmenite Process)?
The constituents of concern in this waste are the chlorinated
congeners of dibenzo-p-dioxin and dibenzofuran, thallium and manganese.
We are proposing to apply the UTS levels to the chlorinated congeners
of dibenzo-p-dioxin and dibenzofuran, and thallium, as indicated in
Table V-1. In addition we are also proposing the option of complying
with the technology standard of combustion (CMBST) for the chlorinated
dibenzo-p-dioxin and dibenzofuran (dioxins and furans) constituents
present in K178.
We note at the outset that we typically promulgate numerical
performance standards to allow facilities maximum flexibility in
determining for themselves how best to achieve compliance with the LDR
treatment standards. By promulgating combustion as an alternative
compliance option, we are not disturbing the degree of flexibility
afforded to facilities; rather, we are enhancing it.
However, when we specify a treatment technology like CMBST as the
treatment standard, the analytical elements of compliance change.
Typically, with specified technologies, no testing and analysis of
treatment residuals is required because we are confident that use of
the specified technology will reduce the level of target organic
constituents to levels that minimize threats to human health and the
environment. For K178, the regulated organic constituents of concern
are dioxin/furan congeners. If combustion in well designed and operated
units is used to treat K178, the dioxin/furan congeners in the K178
should be substantially destroyed. By
[[Page 55768]]
prescribing CMBST, we ensure that the units treating K178 will be units
subject to the standards in Part 264 Subpart O or Part 266 Subpart H,
or from interim status incinerators which have made a specific
demonstration that they operate in a manner equivalent to a Part 264 or
Part 266 combustion unit. The practical effect of this change will be
to limit the type of facilities that can combust K178 to well-regulated
RCRA units (or, after the current transition period, Clean Air Act
permitted units subject to MACT standards). This will ensure that
combustion is done in a closely-regulated facility and in a manner that
provides protection for human health and the environment. Furthermore,
by restricting combustion of K178 to these units, combustion will only
occur in units subject to the recently upgraded dioxin/furan emission
standards of the MACT Hazardous Waste Combustion Rule as well as
standards for other hazardous air pollutants, such as metals (64 FR
52828, September 30, 1999).
K178 does have metal constituents of concern, which would not be
treated by the combustion process and that would remain in the
combustion treatment residuals (e.g., ash and scrubber water). We
therefore are retaining metal treatment standards for all
circumstances, i.e., whether or not the treatment used by a facility
involves combustion. When combustion is used to treat the organics to
achieve LDR compliance, facilities will still need to conduct
compliance testing and analysis for all regulated metal constituents in
the combustion treatment residuals prior to disposal. This approach is
patterned after EPA's promulgation of a similar alternative treatment
standard for F024 (wastes from production of chlorinated aliphatics)
and also for F032 (wastes from wood preserving processes). See 55 FR
22580-81, June 1, 1990. See also 62 FR 26000-3, May 12, 1997.
For both solid and wastewater treatment residuals, we are proposing
use of the Universal Treatment Standards (UTS) for all constituents of
concern except manganese. Universal treatment standards have not been
developed for manganese, although we are proposing standards below. We
did not study this constituent in the development of F039 treatment
standards in 1990 or UTS in 1994. Furthermore, we lack studies
demonstrating treatment effectiveness for highly concentrated manganese
nonwastewaters, such as those containing manganese at levels such as
those found in K178. We did, however, identify treatability data for
less concentrated manganese waste in our treatability database.
These data show that solidification offers promising results in
reducing the mobility of manganese, at least in less concentrated
manganese waste. Such treatment yielded concentrations of 0.002, 0.003,
and 0.46 mg/L TCLP. Under the LDR program, we typically apply a
variability factor of 2.8 to the treated waste data, to account for
variations arising from mechanical limitations in the treatment
equipment. Therefore we calculated potential treatment standards based
on solidification treatment from our treatability database as 0.006,
0.008, and 1.29 mg/L TCLP. We are unsure whether these treatment
standards would be achievable in a waste with the significantly higher
concentrations of manganese found in K178. Therefore, we are not
proposing treatment standards based on solidification. Rather, to
propose a more achievable standard, we based it on a technology which
results in higher post-treatment manganese levels. High temperature
metals recovery (which vitrifies the manganese in the slag) resulted in
a treated manganese concentration of 1.3 mg/L TCLP. Using this datum
and our typical variability factor of 2.8, we calculated a proposed
manganese treatment standard of 3.6 mg/L TCLP. We request comment and
data on this proposed treatment standard, and we request anyone who has
an interest in the treatment standard for manganese to comment to that
effect. We may use the list of commenters on this topic as the only
individuals notified of potential changes to this proposed treatment
standard, so it is important for you to comment if you are in any way
interested.
Because it is possible that commenters may submit data showing that
this treatment option is inappropriate for K178, we request comment on
the option of setting a treatment standard for manganese that is
identical to the current UTS level for thallium, the other metal found
in proposed K178. The thallium treatment level of 0.20 mg/L TCLP is
based on stabilization. We also request any information regarding the
similarity of manganese nonwastewater treatment to the treatment of
other RCRA-regulated metals that now appear in the UTS, both from a
structural or physico-chemical perspective as well as from a treatment
performance perspective.
We have some treatment data for manganese in wastewater matrices
derived from wastes other than K178 in our treatability database. It
has been difficult to determine whether these treatment data are
relevant because we have no examples of wastewaters derived from K178.
We are therefore unsure if the wastes in our database are more or less
concentrated than actual K178 wastewaters. To account for this
uncertainty, we selected treatment data representing relatively high
initial concentrations (up to 1000 mg/L), but also representing full
scale operation and satisfactory treatment (at least 90 percent
reduction in concentration). We found that sedimentation technology,
the most effective treatment method in our database, resulted in a
final effluent concentration of 6.1 mg/L and chemical precipitation
technology resulted in final effluent concentrations of 2.4 and 4.8 mg/
L (both operated at full scale and resulted in greater than 90 percent
reduction). We have selected, to be conservative, the highest
concentration (6.1 mg/L) to calculate a K178 wastewater standard. We
applied a variability factor of 2.8 to obtain a proposed K178 LDR
treatment standard of 17.1mg/L. Again, we request comments on and data
relevant to this proposed treatment standard for wastewater forms of
K178, both from those who support the standard and those who believe
the standard is not achievable. We also request any information
regarding the similarity of manganese wastewater treatment to the
treatment of other RCRA-regulated metals that now appear in the UTS,
both from a structural or physico-chemical perspective as well as from
a treatment performance perspective. Only commenters on this subject
may be notified of future changes we may make based on newly submitted
data.
Because we typically include the same treatment standards for new
listings into those for F039 (multisource leachate) to maintain
equivalence within the LDR regulatory structure, we are also proposing
to add the manganese treatment standard to the F039 section of the
268.40 table. The F039 waste code applies to hazardous waste landfill
leachates in lieu of the original waste codes when multiple waste codes
would otherwise apply. F039 wastes are subject to numerical treatment
standards equivalent to UTS. We are proposing this addition to the
constituents regulated by F039 to maintain the implementation benefits
of having one waste code for multisource leachate. We are also
proposing to add manganese to the UTS Table at 40 CFR 268.48. Manganese
represents significant risk to human health and the environment, as
shown in the risk assessment accompanying this rule. Its presence in
other hazardous wastes
[[Page 55769]]
should be mitigated by effective treatment to avoid similar risks after
land disposal. Furthermore, when manganese is added to the UTS list,
all characteristic wastes that have this constituent as an underlying
hazardous constituent above the UTS levels will require treatment of
manganese before land disposal. We solicit comments on these proposed
conforming changes and especially on the impacts that they may have on
other wastes beyond just K178.
We request comment on the full set of proposed standards for K178
listed in the following table.
Table IV-1.--Treatment Standards for K178
----------------------------------------------------------------------------------------------------------------
Regulated hazardous constituent Wastewaters Nonwastewaters
----------------------------------------------------------------------------------------------------------------
Concentration in mg/kg4
Common name CAS1 No. Concentration in mg/L 2, unless noted as ``mg/L
or technology code 3 TCLP'', or technology code
----------------------------------------------------------------------------------------------------------------
1,2,3,4,6,7,8-Heptachlorodibenzo-p-dioxin 35822-39-4 0.000035 or CMBST 5........ 0.0025 or CMBST 5
1,2,3,4,6,7,8-Heptachlorodibenzofuran.... 67562-39-4 0.000035 or CMBST 5........ 0.0025 or CMBST 5
1,2,3,4,7,8,9-Heptachlorodibenzofuran.... 55673-89-7 0.000035 or CMBST 5........ 0.0025 or CMBST 5
HxCDDs (All Hexachlorodibenzo-p-dioxins). 34465-46-8 0.000063 or CMBST 5........ 0.001 or CMBST 5
HxCDFs (All Hexachlorodibenzofurans)..... 55684-94-1 0.000063 or CMBST 5........ 0.001 or CMBST 5
1,2,3,4,6,7,8,9-Octachlorodibenzo-p- 3268-87-9 0.000063 or CMBST 5........ 0.005 or CMBST 5
dioxin (OCDD).
1,2,3,4,6,7,8,9-Octachlorodibenzofuran 39001-02-0 0.000063 or CMBST 5........ 0.005 or CMBST 5
(OCDF).
PeCDDs (All Pentachlorodibenzo-p-dioxins) 36088-22-9 0.000063 or CMBST 5........ 0.001 or CMBST 5
PeCDFs (All Pentachlorodibenzofurans).... 30402-15-4 0.000035 or CMBST 5........ 0.001 or CMBST 5
TCDDs (All tetrachlorodi-benzo-p-dioxins) 41903-57-5 0.000063 or CMBST 5........ 0.001 or CMBST 5
TCDFs (All tetrachlorodibenzofurans)..... 55722-27-5 0.000063 or CMBST 5........ 0.001 or CMBST 5
Manganese................................ 7439-96-5 17.1....................... 3.6 mg/L TCLP
Thallium................................. 7440-28-0 1.4........................ 0.20 mg/L TCLP
----------------------------------------------------------------------------------------------------------------
1 CAS means Chemical Abstract Services. When the waste code and/or regulated constituents are described as a
combination of a chemical with its salts and/or esters, the CAS number is given for the parent compound only.
2 Concentration standards for wastewaters are expressed in mg/L and are based on analysis of composite samples.
3 All treatment standards expressed as a Technology Code or combination of Technology Codes are explained in
detail in 40 CFR 268.42 Table 1-Technology Codes and Descriptions of Technology-Based Standards.
4 Except for Metals (EP or TCLP) and Cyanides (Total and Amenable) the nonwastewater treatment standards
expressed as a concentration were established, in part, based upon incineration in units operated in
accordance with the technical requirements of 40 CFR part 264, subpart O or 40 CFR part 265, subpart O, or
based upon combustion in fuel substitution units operating in accordance with applicable technical
requirements. A facility may comply with these treatment standards according to provisions in 40 CFR
268.40(d). All concentration standards for nonwastewaters are based on analysis of grab samples.
5 For these wastes, the definition of CMBST is limited to: (1) combustion units operating under 40 CFR 266, (2)
combustion units permitted under 40 CFR Part 264, Subpart O, or (3) combustion units operating under 40 CFR
265, Subpart O, which have obtained a determination of equivalent treatment under 268.42(b).
What Other LDR Provisions Are Proposed to Apply?
1. Debris. We propose to apply the regulations at 40 CFR 268.45 to
hazardous debris contaminated with K176, K177 or K178. Debris
contaminated with these wastes would have to be treated prior to land
disposal, using specific technologies from one or more of the following
families of debris treatment technologies: extraction, destruction, or
immobilization. Hazardous debris contaminated with a listed waste that
is treated by an immobilization technology specified in 40 CFR 268.45
Table 1 is a hazardous waste and must be managed in a hazardous waste
facility. Residuals generated from the treatment of debris contaminated
with K176, K177, or K178 would remain subject to the treatment
standards proposed today. See 57 FR 37277, August 18, 1992, for
additional information on the applicability, scope, and content of the
hazardous debris provisions.
2. Soil. In addition, we propose to apply the regulations at 40 CFR
268.49 to hazardous soil contaminated with K176, K177, or K178. Soil
contaminated with these wastes would have to be treated prior to land
disposal, meeting either alternative treatment standards (i.e., 10
times UTS or 90 percent reduction in initial constituent
concentrations) or the standards at 40 CFR 268.40 being proposed today.
Non-soil residuals generated from the treatment of soil contaminated
with K176, K177, or K178 would remain subject to the treatment
standards proposed today. See 63 FR 28602, May 26, 1998, for additional
information on the applicability, scope, and content of the alternative
soil treatment standard provisions.
3. Underground Injection Wells that can be found in the
administrative record for this rule. Finally, because land disposal
also includes placement in injection wells (40 CFR 268.2(c))
application of the land disposal restrictions to K176, K177, and K178
requires the modification of injection well requirements found in 40
CFR 148. We propose that K176, K177, and K178 be prohibited from
underground injection. Therefore, these wastes could not be underground
injected unless they have been treated in compliance with the LDR
treatment standards being proposed today, or if they are disposed in a
deep injection well that has been granted a no migration petition for
those wastes.
E. Is There Treatment Capacity for the Proposed Wastes?
1. What Is a Capacity Determination?
EPA must determine whether adequate alternative treatment capacity
exists nationally to manage the wastes subject to LDR treatment
standards. RCRA section 3004 (h)(2). Thus, LDRs are effective when the
new listings are effective (typically 6 months after the new listings
are published in the Federal Register), unless EPA grants a national
capacity variance from the otherwise-applicable date and establishes a
different date (not to exceed two years beyond the statutory deadline)
based on ``* * * the earliest date on which adequate alternative
treatment, recovery, or disposal capacity which protects human health
and the environment will be available'' (RCRA section 3004(h)(2), 42
U.S.C.6924(h)(2)).
Our capacity analysis methodology focuses on the amount of waste
[[Page 55770]]
currently disposed on the land, which will require alternative or
additional treatment as a result of the LDRs. The quantity of wastes
that is not disposed on the land, such as discharges regulated under
NPDES, discharges to a POTW, or treatment in a RCRA-exempt tank, is not
included in the quantities requiring additional treatment as a result
of the LDRs. Also, land-disposed wastes that do not require alternative
or additional treatment are excluded from the required capacity
estimates (i.e., those that currently are treated to meet the LDR
treatment standards). Land-disposed wastes requiring alternative or
additional treatment or recovery capacity that is available on site or
within the same company also are excluded from the required commercial
capacity estimates. The resulting estimates of required commercial
capacity then are compared to estimates of available commercial
capacity. If adequate commercial capacity exists, the waste is
restricted from further land disposal. If protective alternative
capacity does not exist, EPA has the authority to grant a national
capacity variance.
In making the estimates described above, the volume of waste
requiring treatment depends on the current waste management practices
employed by the waste generators before this proposed regulation is
promulgated and becomes effective. Data on waste management practices
for these wastes were collected during the development of this proposed
rule. However, we realize that as the regulatory process proceeds,
generators of these wastes may decide to minimize or recycle their
wastes or otherwise alter their management practices. Thus, we will
monitor changes and update data on current management practices as
these changes will affect the volume of wastes ultimately requiring
commercial treatment or recovery capacity.
The commercial hazardous waste treatment industry may change
rapidly. For example, national commercial treatment capacity changes as
new facilities come on line or old facilities go off line, and as new
units and new technologies are added at existing facilities. The
available capacity at commercial facilities also changes as facilities
change their commercial status (e.g., changing from a fully commercial
to a limited commercial or ``captive''--company owned--facility). Thus,
we also continue to update and monitor changes in available commercial
treatment capacity.
For wastes required to meet today's proposed treatment standards,
we request data on the annual generation volumes and characteristics of
wastes affected by this proposed rule, including proposed hazardous
wastes K176, K177, and K178 in wastewater and nonwastewater forms. We
also request data on soil or debris contaminated with these wastes,
residuals generated from the treatment or recycling of these wastes,
and the current and planned management practices for the wastes, waste
mixtures, and treatment residuals.
For available capacity to meet the LDR requirements, we request
data on the current treatment or recovery capacity capable of treating
these wastes, facility and unit permit status related to treatment of
the proposed wastes, and any plans that facilities may expand or reduce
existing capacity or construct new capacity. In addition, we request
information on the time and necessary procedures required for permit
modification for generators or commercial treatment or disposal
facilities to manage the wastes, required changes for operating
practices due to the proposed listings or proposed additional
constituent to be regulated in the wastes, and any waste minimization
activities associated with the wastes. Of particular interest to us are
chemical and physical constraints of treatment technologies for these
wastes and any problems for disposing of these wastes. Also of interest
are any analytical difficulties associated with identifying and
monitoring the regulated constituents in these wastes.
F. What are the Capacity Analysis Results?
This preamble only provides a summary of the capacity analysis
performed to support this proposed regulation. For additional and more
detailed information, please refer to the ``Background Document for
Capacity Analysis for Land Disposal Restrictions: Inorganic Chemical
Production Wastes (Proposed Rule),'' August 2000 (i.e., the Capacity
Background Document).
For this capacity analysis, we examined data on waste
characteristics and management practices gathered for the inorganic
chemical hazardous waste listing determinations. We also examined data
on available treatment or recovery capacity for these wastes. The
sources for these data are the RCRA Section 3007 Survey distributed in
the spring of 1999, record sampling and site visits (see the docket for
today's rule for more information on these survey instruments and
facility activities), the available treatment capacity data submission
that was collected in the mid-1990's, and the 1997 Biennial Report.
For K176 and K177 wastes, the information from the surveys,
sampling, and site visits indicates that there is no quantity of the
wastewater form of K176 or K177 that is expected to be generated and
therefore, there is no quantity of the wastewater form of K176 or K177
that will require alternative commercial treatment. These wastes are
typically present in a nonwastewater form. Based on the RCRA Sec. 3007
Survey information presented in the Capacity Background Document,
required alternative treatment capacity for K176 nonwastewaters is
estimated to be eight tons per year. Required alternative treatment
capacity for K177 nonwastewaters is estimated to be 22 tons per year.
As described in the section of proposed LDR treatment standards above,
we are proposing that numerical treatment standards be applied to K176
and K177 nonwastewaters. We anticipate that commercially available
stabilization, as well as other technologies, can be used in meeting
these treatment standards. We estimate that the commercially available
stabilization capacity is at least eight million tons per year based on
the 1995 Biennial Report. Thus we expect there is sufficient capacity
to treat the proposed K176 and K177 hazardous wastes that would require
treatment. Therefore, we are proposing not to grant a national capacity
variance for K176 or K177 wastewaters or nonwastewaters.
For K178 waste (chloride-ilmenite nonexempt nonwastewaters from the
production of titanium dioxide), our data indicate that the waste is
typically generated as a nonwastewater. We did not identify any
wastewater forms of these wastes and therefore do not anticipate that
alternative management for wastewaters is required. We found that the
wastes are currently land disposed. We estimated that approximately
7,300 tons per year (derived from public information since data on
amounts of treatment solids are confidential as reported in Sec. 3007
Survey) may require alternative treatment. In our assessment, we
assumed that facilities can segregate wastestreams and separately
manage the newly-proposed hazardous waste. Although the generation
quantity (and therefore, the quantity requiring treatment) may be
higher due to the derived from rule, we expect that available treatment
capacity still exists.
As discussed earlier for K178 treatment standards, we are proposing
that numerical treatment standards be applied to K178 wastes. We
anticipate that commercially available incineration, followed by
stabilization if
[[Page 55771]]
necessary, or high temperature metals recovery if applicable, can be
used to meet these treatment standards. We also propose the technology
standard of combustion (CMBST) as an alternative compliance option for
hazardous organic constituents in the K178 wastes. The units treating
the waste by using CMBST will be subject to certain standards, and
facilities will need to meet treatment standards for all regulated
metal constituents prior to disposal, as discussed in the earlier
section on K178 treatment standards. We assume that facilities would
achieve treatment standards using incineration, stabilization, or both.
The quantity of commercially available combustion capacity for sludge
and solid is a minimum of 300,000 tons per year and the quantity of
commercially available stabilization capacity is at least eight million
tons per year based on 1995 Biennial Report.
We have identified that there exist facilities managing K178 waste
in surface impoundments (i.e., in wastewater treatment systems that
contain land based units). If the waste is managed in unretrofitted
impoundments,\62\ it would thus be land disposed in a prohibited
manner. These impoundments can be retrofitted, closed or replaced with
tank systems. If the impoundment continues to be used to manage K178
waste, the unit will be subject to Subtitle C requirements. In
addition, any hazardous wastes managed in the affected impoundment
after the effective date of today's rule are subject to land disposal
prohibitions.\63\ However, facilities may continue to manage newly
listed K178 in surface impoundments, provided they are in compliance
with the appropriate standards for impoundments (40 CFR Parts 264 and
265 subpart K) and the special rules regarding surface impoundments (40
CFR 268.14). EPA notes that those provisions require basic groundwater
monitoring (40 CFR Parts 264 and 265 Subpart F), management, and
recordkeeping, but (in keeping with RCRA section 3005(j)(6)(A)) are
afforded up to 48 months to retrofit to meet minimum technological
requirements.
---------------------------------------------------------------------------
\62\ A unretrofitted impoundment is one not satisfying the
minimum technology requirements (MTR) specified in sections 3004(o)
and 3005(j)(11).
\63\ See RCRA Sec. 3004(m)(1) ``Simultaneously with the
promulgation of regulations under subsection (d), (e), (f), or (g)
prohibiting one or more methods of land disposal of a particular
hazardous waste * * * promulgate regulations specifying those levels
or methods of treatment * * *''
---------------------------------------------------------------------------
Based on the foregoing, we expect that sufficient capacity to treat
the proposed K178 hazardous wastes that would require treatment.
Therefore, we are proposing not to grant a capacity variance for
wastewater and nonwastewater forms of K178.
With respect to the revisions to the F039 and UTS lists, as
discussed earlier in the section on K178 treatment standards, we are
proposing to add manganese to the list of regulated constituents in
F039 (Sec. 268.40) and the UTS table (Sec. 268.48). We have estimated
what portion of the F039 or characteristic wastes (which require
treatment of underlying hazardous constituents to UTS levels) may be
required to meet these new treatment standards. We request comments on
the estimates, the appropriate means of treatment (if necessary), and
the sufficiency of available treatment capacity for the affected wastes
by the addition of manganese to the F039 and UTS lists.
When changing the treatment requirements for wastes already subject
to LDR (including F039 and characteristic wastes), EPA no longer has
authority to use RCRA Sec. 3004(h)(2) to grant a capacity variance to
these wastes. However, EPA is guided by the overall objective of
section 3004(h), namely that treatment standards which best accomplish
the goal of RCRA Sec. 3004(m) (to minimize threats posed by land
disposal) should take effect as soon as possible, consistent with
availability of treatment capacity.
We expect that only a limited quantity of hazardous waste leachate
may be generated from the disposal of newly-listed K176, K177, and K178
wastes (due to the small number of generators) and added to the
generation of leachates from other multiple restricted hazardous wastes
already subject to LDR.
For the amount of characteristic wastes or leachates generated from
those previously regulated hazardous wastes that would be subject only
to the new treatment standards for manganese, we evaluated the universe
of wastes that might be impacted by revisions to the lists of regulated
constituents for F039 and UTS based on limited information. Based on
1997 Biennial Report data and some assumptions of waste compositions
and their potential for land disposal, we were able to estimate the
potential need for additional treatment. For example, we estimated an
upper bound of 70,000 tons per year of nonwastewaters mixed with other
waste codes, the F039 leachate from which would be potentially impacted
by the revision to the F039 treatment standards. In a similar fashion,
we estimated that no more than 520,000 tons per year of characteristic
nonwastewaters potentially might be affected by the proposed changes
(i.e., the addition of manganese to the F039 and UTS lists).
These upper bound estimates are most likely very overstated since
only a portion of each estimated waste volume may contain manganese at
concentrations above the proposed level specified in the UTS table and
the F039 list. The estimates assume that manganese is present at levels
above the proposed treatment standards in all of these wastes and
require alternative treatment, when it is likely that this may be true
in only a small sets of the cases. Furthermore, EPA does not anticipate
that waste volumes subject to treatment for F039 or characteristic
wastes would significantly increase because waste generators already
are required to comply with the treatment requirements for other metals
that may be present in the wastes. The volumes of wastes for which
additional treatment is needed solely due to the addition of manganese
to the F039 and UTS lists are therefore expected to be very small. See
the Capacity Background Document for detailed analysis.
However, even though our volume estimates are highly conservative
and overstated, we find that there still would be no shortage of
treatment capacity. Based on data submittals in the mid-1990's and the
1997 Biennial Report, EPA has estimated that approximately 37 million
tons per year of commercial wastewater treatment capacity are
available, and well over one million tons per year of liquid, sludge,
and solid commercial combustion capacity are available. Also, as
discussed earlier in this section, there exist several million tons of
available stabilization capacity. These are well above the quantities
of F039 or characteristic wastes potentially requiring treatment for
manganese even under the conservative screening assumptions described
above. Therefore, we are proposing a decision not to delay the
effective date for adding manganese to the lists of constituents for
F039 and UTS.
We request comment on its proposed decision not to delay the
effective date for adding manganese to the lists of constituents for
F039 and UTS. We request data on the annual generation volumes and
characteristics of wastes potentially affected by the proposed changes
to UTS and F039 in wastewater and nonwastewater forms (if any), and the
current and planned management practices for the wastes, waste
mixtures, and treatment residuals. We also request data on the current
treatment or recovery capacity capable of treating the affected wastes.
[[Page 55772]]
Further, for soil and debris contaminated with the newly listed
wastes (K176, K177, and K178), we believe that the vast majority of
contaminated soil and debris contaminated with these wastes will be
managed on-site and therefore will not require substantial commercial
treatment capacity. Therefore, we are not proposing to grant a national
capacity variance for hazardous soil and debris contaminated with these
wastes covered under this proposal. Based on the 1999 RCRA Sec. 3007
Survey followed by record sampling and site visits, there are no data
showing the newly listed wastes managed by underground injection wells.
Also, based on the 1999 RCRA Sec. 3007 Survey followed by record
sampling and site visits, there are no data showing mixed radioactive
wastes associated with the proposed listings. EPA is proposing to not
grant a national capacity variance for underground injected wastes,
mixed radioactive wastes, or soil and debris contaminated with these
mixed radioactive wastes, if such wastes are generated.
Therefore, we propose that LDR treatment standards for the affected
wastes covered under today's rule thus become effective when the
listing determinations become effective--the earliest possible date
(see RCRA section 3004(h)(1)--land disposal prohibitions must take
effect immediately when there is sufficient protective treatment
capacity for the waste available). However, we may need to revise
capacity analyses or capacity variance decisions if final listing
determinations are changed or if we receive data and information to
warrant any revision.
Finally, we request comments on the estimated quantities requiring
alternative treatment and information on characteristics of the
affected wastes, management practices for these wastes, and available
treatment, recovery or disposal capacity for the wastes. We also
request comments concerning alternative management for any of these
wastes managed in surface impoundments, including new piping or tank
systems, and the length of time required for such activities. In
addition, we solicit comments on our decision not to grant a national
capacity variance or delay the effective date for any of the affected
wastes. We will consider all available data and information provided
during the public comment period and revise our capacity analysis
accordingly in making the final capacity determinations. Please note,
the ultimate volumes of wastes estimated to require alternative or
additional commercial treatment may change if the final listing
determinations change. Should this occur, we will revise the capacity
analysis accordingly.
V. Compliance Dates
We seek comment on the proposed decisions in this section.
A. Notification
Under the RCRA Section 3010 any person generating, transporting, or
managing a hazardous waste must notify EPA (or an authorized state) of
its activities. Section 3010(a) allows us to waive, under certain
circumstances, the notification requirement under Section 3010 of RCRA.
If these hazardous waste listings are promulgated, we propose to waive
the notification requirement as unnecessary for persons already
identified within the hazardous waste management universe (i.e.,
persons who have an EPA identification number under 40 CFR 262.12). We
do not propose to waive the notification requirement for waste handlers
who have neither notified us that they may manage hazardous wastes nor
received an EPA identification number. Such individuals will have to
provide notification under RCRA Section 3010.
B. Interim Status and Permitted Facilities
Because HSWA requirements are applicable in authorized states at
the same time as in unauthorized states, we will regulate the newly
identified wastes listed under HSWA until states are authorized to
regulate these wastes. Thus, once this regulation becomes effective as
a final rule, we will apply Federal regulations to these wastes and to
their management in both authorized and unauthorized states.
VI. State Authority
A. Applicability of Rule in Authorized States
Under Section 3006 of RCRA, we may authorize qualified states to
administer and enforce the RCRA program within the state. (See 40 CFR
Part 271 for the standards and requirements for authorization.)
Following authorization, we retain enforcement authority under Sections
3007, 3008, 3013, and 7003 of RCRA, although authorized states have
primary enforcement responsibility.
Before the Hazardous and Solid Waste Amendments of 1984 (HSWA)
amended RCRA, a state with final authorization administered its
hazardous waste program entirely in lieu of the Federal program in that
state. The Federal requirements no longer applied in the authorized
state, and we could not issue permits for any facilities located in the
state with permitting authorization. When new, more stringent Federal
requirements were promulgated or enacted, the state was obligated to
enact equivalent authority within specified time-frames. New Federal
requirements did not take effect in an authorized state until the state
adopted the requirements as state law.
By contrast, under Section 3006(g) of RCRA, 42 U.S.C. 6926(g), new
requirements and prohibitions imposed by the HSWA (including the
hazardous waste listings in this proposal) take effect in authorized
states at the same time that they take effect in non-authorized states.
EPA is directed to implement those requirements and prohibitions in
authorized states, including the issuance of permits, until the state
is granted authorization to do so. While states must still adopt HSWA-
related provisions as state law to retain final authorization, the
Federal HSWA requirements apply in authorized states in the interim.
B. Effect on State Authorizations
Because this proposal (with the exception of the actions proposed
under CERCLA authority) will be promulgated pursuant to the HSWA, a
state submitting a program modification is able to apply to receive
either interim or final authorization under Section 3006(g)(2) or
3006(b), respectively, on the basis of requirements that are
substantially equivalent or equivalent to EPA's requirements. The
procedures and schedule for state program modifications under 3006(b)
are described in 40 CFR 271.21. It should be noted that all HSWA
interim authorizations are currently scheduled to expire on January 1,
2003 (see 57 FR 60129, February 18, 1992).
Section 271.21(e)(2) of EPA's state authorization regulations (40
CFR Part 271) requires that states with final authorization modify
their programs to reflect federal program changes and submit the
modifications to EPA for approval. The deadline by which the states
must modify their programs to adopt this proposed regulation, if it is
adopted as a final rule, will be determined by the date of promulgation
of a final rule in accordance with 40 CFR 271.21(e)(2). If the proposal
is adopted as a final rule, Table 1 at 40 CFR 271.1 will be amended
accordingly. Once we approve the modification, the state requirements
become RCRA Subtitle C requirements.
States with authorized RCRA programs already may have regulations
similar to those in this proposed rule. These state regulations have
not been assessed against the Federal regulations being proposed to
determine whether they meet the tests for authorization.
[[Page 55773]]
Thus, a state would not be authorized to implement these regulations as
RCRA requirements until state program modifications are submitted to
EPA and approved, pursuant to 40 CFR 271.21. Of course, States with
existing regulations that are more stringent than or broader in scope
than current Federal regulations may continue to administer and enforce
their regulations as a matter of state law.
It should be noted that authorized states are required to modify
their programs only when EPA promulgates Federal standards that are
more stringent or broader in scope than existing Federal standards.
Section 3009 of RCRA allows states to impose standards more stringent
than those in the Federal program. For those Federal program changes
that are less stringent or reduce the scope of the Federal program,
states are not required to modify their programs. See 40 CFR 271.1(I).
This proposed rule, if finalized, is neither less stringent than nor a
reduction in the scope or the current Federal program, and, therefore,
states would be required to modify their programs to retain
authorization to implement and enforce these regulations.
VII. Designation of Inorganic Chemical Wastes under the
Comprehensive Environmental Response, Compensation, and Liability
Act (CERCLA)
All hazardous wastes listed under RCRA and codified in 40 CFR
261.31 through 261.33, as well as any solid waste that is not excluded
from regulation as a hazardous waste under 40 CFR 261.4(b) and that
exhibits one or more of the characteristics of a RCRA hazardous waste
(as defined in 40 CFR 261.21 through 261.24), are hazardous substances
under the Comprehensive Environmental Response, Compensation, and
Liability Act of 1980 (CERCLA), as amended (see CERCLA Section
101(14)(C)). CERCLA hazardous substances are listed in Table 302.4 at
40 CFR 302.4 along with their reportable quantities (RQs). If a
hazardous substance is released in an amount that equals or exceeds its
RQ, the release must be reported immediately to the National Response
Center (NRC) pursuant to CERCLA Section 103.
A. Reporting Requirements
Under CERCLA Section 103(a), the person in charge of a vessel or
facility from which a hazardous substance has been released in a
quantity that is equal to or exceeds its RQ must immediately notify the
NRC as soon as that person has knowledge of the release. The toll-free
telephone number of the NRC is 1-800-424-8802; in the Washington, DC,
metropolitan area, the number is (202) 267-2675. In addition to this
reporting requirement under CERCLA, Section 304 of the Emergency
Planning and Community Right-to-Know Act of 1986 (EPCRA) requires
owners or operators of certain facilities to report releases of
extremely hazardous substances and CERCLA hazardous substances to State
and local authorities. Immediately after the release of an RQ or more
of an extremely hazardous substance or a CERCLA hazardous substance,
EPCRA Section 304 notification must be given to the community emergency
coordinator of the local emergency planning committee for any area
likely to be affected by the release, and to the State emergency
response commission of any State likely to be affected by the release.
Under Section 102(b) of CERCLA, all hazardous substances (as
defined by CERCLA Section 101(14)) have a statutory RQ of one pound,
unless and until the RQ is adjusted by regulation. In today's proposed
rule, we propose: (1) to list the following three wastestreams as RCRA
hazardous wastes; (2) to designate these wastestreams as CERCLA
hazardous substances, and (3) to adjust the one-pound statutory RQs for
two of these wastestreams. The proposed wastestreams are as follows:
K176 Baghouse filters from the production of antimony oxide
K177 Slag from the production of antimony oxide that is disposed of
or speculatively accumulated
K178 Nonwastewaters from the production of titanium dioxide by the
chloride-ilmenite process. [This listing does not apply to chloride
process waste solids from titanium tetrachloride production exempt
under 40 CFR 261.4(b)(7).]
B. Basis for Proposed RQ Adjustment
Our methodology for adjusting the RQs of individual hazardous
substances begins with an evaluation of the intrinsic physical,
chemical, and toxicological properties of each hazardous substance. The
intrinsic properties examined--called ``primary criteria''--are aquatic
toxicity, mammalian toxicity (oral, dermal, and inhalation),
ignitability, reactivity, chronic toxicity, and potential
carcinogenicity.
Generally, for each intrinsic property, we rank the hazardous
substance on a five-tier scale, associating a specific range of values
on each scale with an RQ value of 1, 10, 100, 1,000, or 5,000 pounds.
Based on the various primary criteria, the hazardous substance may
receive several tentative RQ values. The lowest of the tentative RQs
becomes the ``primary criteria RQ'' for that substance.
After the primary criteria RQ is assigned, the substance is
evaluated further for its susceptibility to certain degradative
processes, which are used as secondary RQ adjustment criteria. These
natural degradative processes are biodegradation, hydrolysis, and
photolysis (BHP). If a hazardous substance, when released into the
environment, degrades relatively rapidly to a less hazardous form by
one or more of the BHP processes, its primary criteria RQ is generally
raised one level. Conversely, if a hazardous substance degrades to a
more hazardous product after its release, the original substance is
assigned an RQ equal to the RQ for the more hazardous substance, which
may be one or more levels lower than the RQ for the original substance.
The standard methodology used to adjust the RQs for RCRA hazardous
wastestreams differs from the methodology applied to individual
hazardous substances. The procedure for assigning RQs to RCRA
wastestreams is based on an analysis of the hazardous constituents of
the wastestreams. The constituents of each RCRA hazardous wastestream
are identified in 40 CFR part 261, Appendix VII. We determine an RQ for
each constituent within the wastestream and establish the lowest RQ
value of these constituents as the adjusted RQ for the wastestream.
In today's proposed rule, we propose to assign a one-pound adjusted
RQ to the K176 wastestream and 5,000 pounds to the K177 wastestream.
The proposed adjusted RQs for both of these wastestreams are based on
the lowest RQ value of the constituents present in each wastestream,
are presented in Table VII-1 below. We seek comment our proposed
adjustments to the RQ values for these wastes. We are not adjusting the
RQ for K178 at this time because we have not yet developed a ``waste
constituent RQ'' for manganese, one of the constituents of concern in
this waste.
[[Page 55774]]
Table VII-1.--Proposed Adjusted RQs for Wastestreams K176, K177, and
K178
------------------------------------------------------------------------
Wastestream
Wastestream Wastestream constituent Wastestream
constituent RQ (lb.) RQ (lb.)
------------------------------------------------------------------------
K176......................... arsenic........ 1 1
lead........... 10 ...........
K177......................... antimony....... 5,000 5,000
------------------------------------------------------------------------
VIII. Administrative Assessments
A. Executive Order 12866
Under Executive Order 12866, [58 FR 51,735 (October 4, 1993)] the
Agency must determine whether the regulatory action is ``significant''
and therefore subject to OMB review and the requirements of the
Executive Order. The Order defines ``significant regulatory action'' as
one that is likely to result in a rule that may: (1) Have an annual
effect on the economy of $100 million or more or adversely affect in a
material way the economy, a sector of the economy, productivity,
competition, jobs, the environment, public health or safety, or State,
local, or tribal governments or communities; (2) create a serious
inconsistency or otherwise interfere with an action taken or planned by
another agency; (3) materially alter the budgetary impact of
entitlements, grants, user fees, or loan programs or the rights and
obligations of recipients thereof; or (4) raise novel, legal or policy
issues arising out of legal mandates, the President's priorities, or
the principles set forth in the Executive Order.
The Agency estimated the costs of today's proposed rule to
determine if it is a significant regulation as defined by the Executive
Order. The analysis considered compliance costs and economic impacts
for inorganic chemical producers affected by this rule. We estimate the
total cost of the rule to be $3 million annually. This analysis
suggests that this rule is not economically significant according to
the definition in E.O. 12866. The Office of Management and Budget has
deemed this rule to be significant for novel policy reasons and has
reviewed this rule.
Detailed discussions of the methodology used for estimating the
costs, economic impacts and the benefits attributable to today's
proposed rule for listing hazardous wastes from inorganic chemical
production, followed by a presentation of the cost, economic impact and
benefit results, may be found in the background document: ``Economic
Analysis of the Proposed Rule For Listing Hazardous Waste From
Inorganic Chemical Production,'' which was placed in the docket for
today's proposed rule. We seek comment on the methodology used, the
projected economic impacts, and the benefits assumed for the proposed
listings.
1. Methodology Section
To estimate the cost, economic impacts to potentially affected
firms and benefits to society from this proposed rulemaking, We
evaluated Sec. 3007 Survey responses from inorganic chemical producers,
firm financial reports, and chemical production data. The Agency has
developed model facilities that represent composite information about
inorganic chemical producers at both the facility and firm level. We
also evaluated two scenarios. The first scenario evaluates the cost of
listing all wastes that we propose to list in today's proposal. The
second scenario includes not only wastes that EPA has proposed to list
but also any waste that has exceeded risk screens (or other screening
criteria) and had quantitative risk assessment completed. Analysis of
these scenarios allows the public to understand what costs would have
resulted from this rule making if all of the quantitative risk
assessments involving fate and transport modeling had shown risk to
human health.
To estimate the incremental cost of this rule making, we reviewed
baseline management practices and costs of potentially affected firms.
Where more than one baseline management method was used (e.g. municipal
incineration and landfilling), we either modeled more than one form of
baseline management or selected the least expensive form of baseline
management (which would overestimate rather than underestimate the cost
of the rule).
The Agency has modeled the most likely post-regulatory scenario
resulting from the listing (e.g., disposal in a Subtitle C hazardous
waste landfill, recycling) and estimated the cost of complying with it.
The difference between the baseline management cost and the post-
regulatory cost is the incremental cost of the rulemaking.
To estimate the economic impact of today's proposed rulemaking, we
compared the incremental cost of the rulemaking with model firm sales
and either net profit or product value. The Agency has also considered
the ability of potentially affected firms to pass compliance costs on
in the form of higher prices.
To estimate the benefits of today's proposal, we evaluated risk
assessment results and as well as a qualitative assessment of benefits
including natural resource protection of groundwater.
2. Results
a. Volume Results. Data reviewed by the Agency indicates that there
are 9 inorganic chemical producers potentially affected by today's
proposed rule. The data report that these firms generated 700,000 tons
of inorganic chemical production waste annually that are potentially
affected by today's proposed rule and modeled under Scenario 1. Data
also indicate that there are 26 inorganic chemical producers who have
generated wastes that are either being listed because they exhibit a
characteristic or have been evaluated for quantitative risk assessment
involving fate and transport modeling by the Agency to evaluate their
potential effect on human health and the environment. These wastes are
being modeled under Scenario 2.
b. Cost Results. For today's proposed rule, we estimate the total
annual incremental costs from today's proposal to be $ 2.5 million for
all facilities. Sectors costs are summarized in Table 2.
[[Page 55775]]
Table VIII-1.--Estimated Incremental Cost By Inorganic Chemical Sector
----------------------------------------------------------------------------------------------------------------
Estimated incremental annual costs $ 000s (1999 $) Number of affected
----------------------------------------------------- facilities
Sector -------------------------
Scenario 1 Scenario 2 Scenario 1 Scenario 2
----------------------------------------------------------------------------------------------------------------
Antimony Oxide................... 1.6 (recycling), 35 1.6 (recycling), 35 3 3
(disposal). (disposal).
Hydrogen Cyanide................. ......................... 215..................... 3 5
Sodium Chlorate.................. ......................... 225..................... 0 5
Sodium Phosphate................. ......................... 76...................... 0 4
Titanium Dioxide................. 2900..................... 6500.................... 3 9
Total........................ 2937..................... 7051.................... 9 26
------------------------------------------------------------------------------
----------------------------------------------------------------------------------------------------------------
c. Economic Impact Results. To estimate potential economic impacts
resulting from today's proposed rule, we used first order economic
impacts measures such as the estimated incremental costs of today's
proposed rule as a percentage of both affected firms' sales and
estimated profits \64\. We applied these measures to affected inorganic
chemical producers. For affected inorganic chemical producers in the
antimony oxide and sodium chlorate sectors, we estimated the costs to
be less than 3 percent of a typical firm's sales and less than 2
percent of a firm's estimated profits. For affected inorganic chemical
producers in the hydrogen cyanide sector, we estimated the cost to be
less than 1 percent of a typical firm's sales and estimated profits.
More detailed information on this estimate can be found in the economic
analysis placed into today's docket.
---------------------------------------------------------------------------
\64\ Because profit information is often either unavailable or
more variable from year to year than sales measures, the Agency has
chose to use a profit surrogate in completing the economic impact
analysis of this proposal. According to Dun and Bradstreet's
Industry Norms and Key Business Indicators (1995) the average net
after tax profit for inorganic chemical producers in the 2819 SIC
code was 6.3 percent. This percentage is applied to reported sales
of affected firms in order to estimate their profits.
---------------------------------------------------------------------------
d. Benefits Assessment. EPA has not conducted a quantitative
assessment of actual benefits from this proposed rule. Because today's
proposed rule results in new hazardous waste management requirements
for K176, K177, and K178 wastes, the Agency believes that there may be
a reduction in releases of hazardous constituents to the environment.
B. Regulatory Flexibility Act (RFA), as amended by the Small Business
Regulatory Enforcement Fairness Act of 1996 (SBREFA), 5 USC 601 et.
seq.
The RFA generally requires an agency to prepare a regulatory
flexibility analysis of any rule subject to notice and comment
rulemaking requirements under the Administrative Procedures Act or any
other statute unless the agency certifies that the rule will not have a
significant economic impact on a substantial number of small entities.
Small entities include small businesses, small organizations, and small
governmental jurisdictions.
For purposes of assessing the impacts of today's rule on small
entities, a small entity is defined as: (1) A small business that has
fewer than 1000 or 100 employees per firm depending upon the SIC code
the firm primarily classified in \65\; (2) a small governmental
jurisdiction that is a government of a city, county, town, school
district or special district with a population of less than 50,000; and
(3) a small organization that is any not-for-profit enterprise which is
independently owned and operated and is not dominant in its field.
---------------------------------------------------------------------------
\65\ The Small Business Administration has classified firms in
the manufacturing sector (SIC Codes 20-39) and wholesale trade
sector (SIC Codes 50-51) as small businesses within the sector based
on the number of employees per firm. See Small Business Size
Standards, 61 FR 3280, 3289 (January 31, 1996). Thus, to determine
if a inorganic chemical producer is a small business, the primary
SIC code of the firm would have to be determined. The small entities
in today's rulemaking are in two SIC codes: (1) 2812 Alkalies and
Chlorine, size standard 1000 employees and (2) 5082 Construction and
Mining (except Petroleum) Machinery and Equipment size standard 100
employees.
---------------------------------------------------------------------------
After considering the economic impacts of today's proposed rule on
small entities, I certify that this action will not have a significant
economic impact on a substantial number of small entities.
There are two potentially affected inorganic producing firms that
constitute small entities. These firms are located in the antimony
oxide sector. We have determined that these two firms would under this
proposal incur costs of less than 1 percent of both the firm's sales
and estimated profits under one scenario analyzed for the wastes in
this sector. We continue to be interested in the potential impacts of
the proposed rule on small entities and welcome comments on issues
related to such impacts.
C. Paperwork Reduction Act
The information collection requirements in this proposed rule have
been submitted for approval to the Office of Management and Budget
(OMB) under the Paperwork Reduction Act, 44 U.S.C. 3501 et seq. An
Information Collection Request (ICR) document has been prepared (ICR
No. 1968.01) and a copy may be obtained from Sandy Farmer by mail at
Collection Strategies Division; U.S. Environmental Protection Agency
(2822); 1200 Pennsylvania Ave., NW, Washington, DC 20460,by email at
[email protected], or by calling (202) 260-2740. A copy may
also be downloaded off the internet at http://www.epa.gov/icr.
This rule is proposed under the authority of sections 3001(e)(2)
and 3001(b)(1) of the Hazardous and Solid Waste Amendments (HSWA) of
1984. The effect of listing the wastes described earlier will be to
subject industry to management and treatment standards under the
Resource Conservation and Recovery Act (RCRA).
This proposed rule does not contain any new information collection
requirements, nor does it propose to modify any existing information
collection requirements. As a result, this proposed rule represents
only an incremental increase in burden for generators and subsequent
handlers of the newly listed wastes in complying with existing RCRA
information collection requirements.
The total annual respondent burden and cost for all existing
paperwork associated with this proposed rule presented here represents
the incremental increase in paperwork burden under six existing
Information Collection Requests (ICRs). We estimate the total annual
respondent burden for
[[Page 55776]]
all information collection activities to be approximately 417 hours, at
an annual cost of approximately $19,916.
Comments are requested on the Agency's need for this information,
the accuracy of the provided burden estimates, and any suggested
methods for minimizing respondent burden, including through the use of
automated collection techniques. Send comments on the ICR to the
Director, Collection Strategies Division; U.S. Environmental Protection
Agency (2822); 1200 Pennsylvania Ave., NW, Washington, DC 20460; and to
the Office of Information and Regulatory Affairs, Office of Management
and Budget, 725 17th St., N.W., Washington, DC 20503, marked
``Attention: Desk Officer for EPA.'' Include the ICR number in any
correspondence. Since OMB is required to make a decision concerning the
ICR between 30 and 60 days after September 14, 2000, a comment to OMB
is best assured of having its full effect if OMB receives it by October
16, 2000. The proposed rule will respond to any OMB or public comments
on the information collection requirements contained in this proposal.
D. Unfunded Mandates Reform Act
Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), Public
Law 104-4, establishes requirements for Federal agencies to assess the
effects of their regulatory actions on State, local, and tribal
governments and the private sector. Under section 202 of the UMRA, EPA
generally must prepare a written statement, including a cost-benefit
analysis, for proposed and final rules with ``Federal mandates'' that
may result in expenditures to State, local, and tribal governments, in
the aggregate, or to the private sector, of $100 million or more in any
one year. Before promulgating an EPA rule for which a written statement
is needed, section 205 of the UMRA generally requires EPA to identify
and consider a reasonable number of regulatory alternatives and adopt
the least costly, most cost-effective or least burdensome alternative
that achieves the objectives of the rule. The provisions of section 205
do not apply when they are inconsistent with applicable law. Moreover,
section 205 allows EPA to adopt an alternative other than the least
costly, most cost-effective or least burdensome alternative if the
Administrator publishes with the proposed rule an explanation why that
alternative was not adopted. Before EPA establishes any regulatory
requirements that may significantly or uniquely affect small
governments, including tribal governments, it must have developed under
section 203 of the UMRA a small government agency plan. The plan must
provide for notifying potentially affected small governments, enabling
officials of affected small governments to have meaningful and timely
input in the development of EPA regulatory proposals with significant
Federal intergovernmental mandates, and informing, educating, and
advising small governments on compliance with the regulatory
requirements.
Today's rule contains no Federal mandates (under the regulatory
provisions of Title II of the UMRA) for State, local, or tribal
governments or the private sector. The rule would not impose any
federal intergovernmental mandate because it imposes no enforceable
duty upon state, tribal or local governments. States, tribes and local
governments would have no compliance costs under this rule. It is
expected that states will adopt similar rules, and submit those rules
for inclusion in their authorized RCRA programs, but they have no
legally enforceable duty to do so. For the same reasons, we determined
that this rule contains no regulatory requirements that might
significantly or uniquely affect small governments. We have fulfilled
the requirement for analysis under the Unfunded Mandates Reform Act.
E. Executive Order 12898: Environmental Justice
EPA is committed to addressing environmental justice concerns and
is assuming a leadership role in environmental justice initiatives to
enhance environmental quality for all populations in the United States.
The Agency's goals are to ensure that no segment of the population,
regardless of race, color, national origin, or income bears
disproportionately high and adverse human health or environmental
impacts as a result of EPA's policies, programs, and activities, and
that all people live in safe and healthful environments. In response to
Executive Order 12898 and to concerns voiced by many groups outside the
Agency, EPA's Office of Solid Waste and Emergency Response formed an
Environmental Justice Task Force to analyze the array of environmental
justice issues specific to waste programs and to develop an overall
strategy to identify and address these issues (OSWER Directive No.
9200.3-17).
Today's proposed rule covers wastes from inorganic chemical
production. It is not certain whether the environmental problems
addressed by this rule could disproportionately affect minority or low-
income communities. Today's proposed rule is intended to reduce risks
of hazardous wastes as proposed, and to benefit all populations. As
such, this rule is not expected to cause any disproportionately high
and adverse impacts to minority or low-income communities versus non-
minority or affluent communities.
In making hazardous waste listing determinations, we base our
evaluations of potential risk from the generation and management of
solid wastes on an analysis of potential individual risk. In conducting
risk evaluations, our goal is to estimate potential risk to any
population of potentially exposed individuals (e.g., home gardeners,
adult farmers, children of farmers, anglers) located in the vicinity of
any generator or facility handling a waste. Therefore, we are not
putting poor, rural, or minority populations at any disadvantage with
regard to our evaluation of risk or with regard to how the Agency makes
its proposed hazardous waste listing determinations.
In proposing today to list wastes as hazardous (i.e., filter
baghouses and low antimony slags from antimony oxide production that
are discarded, nonexempt nonwastewater from the titanium dioxide
chloride-ilmenite process,), all populations potentially exposed to
these wastes or potentially exposed to releases of the hazardous
constituents in the wastes will benefit from the proposed listing
determination. In addition, listing determinations take effect at the
national level. The wastes proposed to be listed as hazardous will be
hazardous regardless of where they are generated and regardless of
where they may be managed. Although the Agency understands that the
proposed listing determinations, if finalized, may affect where these
wastes are managed in the future (in that hazardous wastes must be
managed at subtitle C facilities), the Agency's decision to list these
wastes as hazardous is independent of any decisions regarding the
location of waste generators and the siting of waste management
facilities.
Similarly, in cases where the Agency is proposing not list a solid
waste as hazardous because the waste does not meet the criteria for
being identified as a hazardous waste, these decisions are based upon
an evaluation of potential individual risks located in proximity to any
facility handling the waste. Therefore, any population living
proximately to a facility that produces a solid waste that the Agency
has proposed not to list would not be adversely affected either because
the waste is already being managed as a hazardous waste in the Subtitle
C system or because the solid waste does not pose a sufficient risk to
the local population. We encourage all
[[Page 55777]]
stakeholders including members of the environmental justice community
and members of the regulated community to provide comments or further
information related to potential environmental justice concerns or
impacts, including information and data on facilities that have
evaluated potential ecological and human health impacts (taking into
account subsistence patterns and sensitive populations) to minority or
low-income communities.
F. Executive Order 13045: Protection of Children From Environmental
Health Risks and Safety Risks
Executive Order 13045, ``Protection of Children from Environmental
Health Risks and Safety Risks'' (62 FR 19885, April 23, 1997), applies
to any rule that: (1) is determined to be ``economically significant''
as defined under Executive Order 12866, and (2) concerns an
environmental health or safety risk that EPA has reason to believe may
have a disproportionate effect on children. If the regulatory action
meets both criteria, the Agency must evaluate the environmental health
or safety effects of the planned rule on children, and explain why the
planned regulation is preferable to other potentially effective and
reasonably feasible alternatives considered by the Agency. This
proposed rule is not subject to the Executive Order because it is not
economically significant as defined in E.O. 12866, and because the
Agency does not have reason to believe the environmental health or
safety risks addressed by this action present a disproportionate risk
to children.
The topic of environmental threats to children's health is growing
in regulatory importance as scientists, policy makers, and village
leaders continue to recognize the extent to which children are
particularly vulnerable to environmental hazards. Recent EPA actions
have been in the forefront of addressing environmental threats to the
health and safety of children. Today's proposed rule further reflects
our commitment to mitigating environmental threats to children.
A few significant physiological characteristics are largely
responsible for children's increased susceptibility to environmental
hazards. First, children eat proportionately more food, drink
proportionately more fluids, and breathe more air per pound of body
weight than do adults. As a result, children potentially experience
greater levels of exposure to environmental threats than do adults.
Second, because children's bodies are still in the process of
development, their immune systems, neurological systems, and other
immature organs can be more easily and considerably affected by
environmental hazards.
Today's proposed rule is intended to avoid releases of hazardous
constituents to the environment at levels that will cause unacceptable
risks. We considered risks to children in our risk assessment. The more
appropriate and safer management practices proposed in this rule are
projected to reduce risks to children potentially exposed to the
constituents of concern. The public is invited to submit or identify
peer-reviewed studies and data, of which the agency may not be aware,
that assess results of early life exposure to the proposed hazardous
constituents from wastes from inorganic chemical production proposed
for listing in today's rulemaking.
G. Executive Order 13084: Consultation and Coordination With Indian
Tribal Governments
Under Executive Order 13084, EPA may not issue a regulation that is
not required by statute, that significantly or uniquely affects the
communities of Indian tribal governments, and that imposes substantial
direct compliance costs on those communities, unless the Federal
government provides the funds necessary to pay the direct compliance
costs incurred by the tribal governments, or EPA consults with those
governments. If EPA complies by consulting, Executive Order 13084
requires EPA to provide to the Office of Management and Budget, in a
separately identified section of the preamble to the rule, a
description of the extent of EPA's prior consultation with
representatives of affected tribal governments, a summary of the nature
of their concerns, and a statement supporting the need to issue the
regulation. In addition, Executive Order 13084 requires EPA to develop
an effective process permitting elected officials and other
representatives of Indian tribal governments ``to provide meaningful
and timely input in the development of regulatory policies on matters
that significantly or uniquely affect their communities.''
For the reasons described above, today's proposed rule does not
create a mandate on State, local or tribal governments, nor does it
impose any enforceable duties on these entities. Accordingly, the
requirements of section 3(b) of Executive Order 13084 do not apply to
this rule.
H. Executive Order 13132--Federalism
Executive Order 13132, entitled ``Federalism'' (64 FR 43255, August
10, 1999), requires EPA to develop an accountable process to ensure
``meaningful and timely input by State and local officials in the
development of regulatory policies that have federalism implications.''
``Policies that have federalism implications'' is defined in the
Executive Order to include regulations that have ``substantial direct
effects on the States, on the relationship between the national
government and the States, or on the distribution of power and
responsibilities among the various levels of government.''
Under Section 6 of Executive Order 13132, EPA may not issue a
regulation that has federalism implications, that imposes substantial
direct compliance costs, and that is not required by statute, unless
the Federal government provides the funds necessary to pay the direct
compliance costs incurred by State and local governments, or EPA
consults with State and local officials early in the process of
developing the proposed regulation. EPA also may not issue a regulation
that has federalism implications and that preempts State law, unless
the Agency consults with State and local officials early in the process
of developing the proposed regulation.
Section 4 of the Executive Order contains additional requirements
for rules that preempt State or local law, even if those rules do not
have federalism implications (i.e., the rules will not have substantial
direct effects on the States, on the relationship between the national
government and the states, or on the distribution of power and
responsibilities among the various levels of government). Those
requirements include providing all affected State and local officials
notice and an opportunity for appropriate participation in the
development of the regulation. If the preemption is not based on
express or implied statutory authority, EPA also must consult, to the
extent practicable, with appropriate State and local officials
regarding the conflict between State law and Federally protected
interests within the agency's area of regulatory responsibility.
This proposed rule does not have federalism implications. It will
not have substantial direct effects on the States, on the relationship
between the national government and the States, or on the distribution
of power and responsibilities among the various levels of government,
as specified in Executive Order 13132. This proposed rule directly
affects primarily inorganic chemical producers. There are no State and
local government bodies that incur direct compliance costs by this
rulemaking. State and local government
[[Page 55778]]
implementation expenditures are expected to be less than $500,000 in
any one year.\66\ Thus, the requirements of section 6 of the Executive
Order do not apply to this rule.
---------------------------------------------------------------------------
\66\ For more information, please refer to Appendix C of the
background document ``Economic Analysis of the Proposed Rule For
Listing Hazardous Waste From Inorganic Chemical Production,'' which
was placed in the docket for today's proposed rule.
---------------------------------------------------------------------------
This proposed rule would preempt State and local law that is less
stringent for these inorganic chemical production wastes as hazardous
wastes. Under the Resource Conservation and Recovery Act (RCRA), 42
U.S.C. 6901 to 6992k, the relationship between the States and the
national government with respect to hazardous waste management is
established for authorized State hazardous waste programs, 42 U.S.C.
6926 (3006), and retention of State authority, 42 U.S.C. 6929 (3009).
Under section 3009 of RCRA, States and their political subdivisions may
not impose requirements less stringent for hazardous waste management
than the national government. By publishing and inviting comment on
this proposed rule, we hereby provide State and local officials notice
and an opportunity for appropriate participation. Thus, we have
complied with the requirements of section 4 of the Executive Order.
I. National Technology Transfer and Advancement Act
Section 12(d) of the National Technology Transfer and Advancement
Act of 1995 (``NTTAA''), Public Law 104-113, section 12(d) (15 U.S.C.
272 note) directs EPA to use voluntary consensus standards in its
regulatory activities, unless to do so would be inconsistent with
applicable law or otherwise impractical. Voluntary consensus standards
are technical standards (e.g., materials specifications, test methods,
sampling procedures, and business practices) that are developed or
adopted by voluntary consensus standards bodies. The NTTAA directs EPA
to provide Congress, through OMB, explanations when the Agency decides
not to use available and applicable voluntary consensus standards. This
proposed rulemaking involves technical standards. EPA proposes to use
Toxicity Characteristic Leaching Procedure (TCLP) for treatment
standards for associated with hazardous metal constituents in wastes
proposed for listing in today's proposal. The TCLP is the standard test
method used to evaluate the toxicity characteristic for the definition
of hazardous waste (see 40 CFR 261.24) and treatment standards for
metal constituents under the Land Disposal Restrictions (see 40 CFR
268.40 and 268.48.). The Agency has used the TCLP in completing its
treatment standards for the same hazardous metal constituents across a
range of listed and characteristic hazardous wastes. The performance
level for leachability is based on the Best Commercially-Available
Demonstrated Technology (BDAT). The use of the TCLP for the same
constituents assures uniformity and consistency in the treatment of
hazardous waste in fulfillment of the Congressional Mandate to minimize
long-term threats to human health or the environment. 42 U.S.C.
6924(m). The use of any voluntary consensus standard would be
impractical with applicable law because it would require a different
leaching method than is currently used to determine hazardous
characteristics. The use of different chemical methods to assess
hazardousness of the waste and compliance with treatment standards
would create disparate results between hazardous waste identification
and effective treatment of land disposed hazardous wastes. We have not,
therefore, used any voluntary consensus standards. EPA welcomes
comments on this aspect of the proposed rulemaking and, specifically,
invites the public to identify potentially-applicable voluntary
consensus standards and to explain why such standards should be used in
this regulation. EPA has also issued an advanced notice of proposed
rulemaking for the Land Disposal Restriction program (65 FR 37932, June
19, 2000) that has included discussion on the effectiveness of
stabilization on metals in hazardous wastes.
List of Subjects
40 CFR Part 148
Environmental protection, Administrative practice and procedure,
Hazardous waste, Reporting and recordkeeping requirements, Water
supply.
40 CFR Part 261
Environmental protection, Hazardous materials, Waste treatment and
disposal, Recycling.
40 CFR Part 268
Environmental protection, Hazardous materials, Waste management,
Reporting and recordkeeping requirements, Land Disposal Restrictions,
Treatment Standards.
40 CFR Part 271
Environmental protection, Administrative practice and procedure,
Confidential business information, Hazardous material transportation,
Hazardous waste, Indians-lands, Intergovernmental relations, Penalties,
Reporting and recordkeeping requirements, Water pollution control,
Water supply.
40 CFR Part 302
Environmental protection, Air pollution control, Chemicals,
Emergency Planning and Community Right-to-Know Act, Extremely hazardous
substances, Hazardous chemicals, Hazardous materials, Hazardous
materials transportation, Hazardous substances, Hazardous wastes,
Intergovernmental relations, Natural resources, Reporting and
recordkeeping requirements, Superfund, Waste treatment and disposal,
Water pollution control, Water supply.
Dated: August 30, 2000.
Carol M. Browner,
Administrator.
For the reasons set forth in the preamble, title 40, chapter I of
the Code of Federal Regulations is proposed to be amended as follows:
PART 148--HAZARDOUS WASTE INJECTION RESTRICTIONS
1. The authority citation for Part 148 continues to read as
follows:
Authority: Secs. 3004, Resource Conservation and Recovery Act,
42 U.S.C. 6901 et seq.
2. Section 148.18 is amended by adding paragraphs (l) and (m) to
read as follows:
Sec. 148.19 Waste-specific prohibitions newly listed and identified
wastes.
* * * * *
(l) Effective [date six months after publication of final rule],
the wastes specified in 40 CFR 261.32 as EPA Hazardous Waste Numbers
K176, K177, and K178 are prohibited from underground injection.
(m) The requirements of paragraphs (a) through (l) of this section
do not apply:
(1) If the wastes meet or are treated to meet the applicable
standards specified in subpart D of part 268 of this chapter; or
(2) If an exemption from a prohibition has been granted in response
to a petition under subpart C of this part; or
(3) During the period of extension of the applicable effective
date, if an extension has been granted under Sec. 148.4.
PART 261--IDENTIFICATION AND LISTING OF HAZARDOUS WASTE
3. The authority citation for Part 261 continues to read as
follows:
Authority: 42 U.S.C. 6905, 6912(a), 6921, 6922, 6924(y), and
6938.
[[Page 55779]]
4. Section 261.4 is amended by revising paragraph (b)(15) to read
as follows:
Sec. 261.4 Exclusions.
* * * * *
(b) * * *
(15) Leachate or gas condensate collected from landfills where
certain solid wastes have been disposed, provided that:
(i) The solid wastes disposed would meet one or more of the listing
descriptions for Hazardous Waste Codes K169, K170, K171, K172, K174,
K175, K176, K177, and K178, if these wastes had been generated after
the effective date of the listing;
(ii) The solid wastes described in paragraph (b)(15)(i) of this
section were disposed prior to the effective date of the listing:
(iii) The leachate or gas condensate do not exhibit any
characteristic of hazardous waste nor are derived from any other listed
hazardous waste;
(iv) Discharge of the leachate or gas condensate, including
leachate or gas condensate transferred from the landfill to a POTW by
truck, rail, or dedicated pipe, is subject to regulation under Sections
307(b) or 402 of the Clean Water Act.
(v) After February 13, 2001, leachate or gas condensate derived
from K169-K172 will no longer be exempt if it is stored or managed in a
surface impoundment prior to discharge. After [date 24 months after
publication date of the final rule], leachate or gas condensate derived
from K176, K177, and K178 will no longer be exempt if it is stored or
managed in a surface impoundment prior to discharge. There is one
exception: if the surface impoundment is used to temporarily store
leachate or gas condensate in response to an emergency situation (e.g.,
shutdown of wastewater treatment system), provided the impoundment has
a double liner, and provided the leachate or gas condensate is removed
from the impoundment and continues to be managed in compliance with the
conditions of paragraph (b)(15)(v) after the emergency ends.
* * * * *
5. In Sec. 261.32, the table is amended by adding in alphanumeric
order (by the first column) the following wastestreams to the subgroup
``Inorganic Chemicals'' to read as follows:
Sec. 261.32 Hazardous waste from specific sources.
* * * * *
----------------------------------------------------------------------------------------------------------------
Hazardous
Industry and EPA hazardous waste No. Hazardous waste code
----------------------------------------------------------------------------------------------------------------
* * * * * *
*
Inorganic chemicals:
* * * * * *
*
K176...................................... Baghouse filters from the production of antimony oxide (E)
K177...................................... Slag from the production of antimony oxide that is (T)
disposed of or speculatively accumulated.
K178..................................... Nonwastewaters from the production of titanium (T)
dioxide by the chloride-ilmenite process. [This
listing does not apply to chloride process waste
solids from titanium tetrachloride production exempt
under section 261.4(b)(7)].
* * * * * *
*
----------------------------------------------------------------------------------------------------------------
* * * * *
6. Appendix VII to Part 261 is amended by adding the following
wastestreams in alphanumeric order (by the first column) to read as
follows:
Appendix VII to Part 261--Basis for Listing Hazardous Waste
------------------------------------------------------------------------
Hazardous constituents for
EPA hazardous waste No. which listed
------------------------------------------------------------------------
* * * * *
K176................................. Arsenic, lead.
K177................................. Antimony.
K178................................. Manganese, thallium.
------------------------------------------------------------------------
* * * * *
7. Appendix VIII to Part 261 is amended by adding in alphabetical
sequence of common name the following entries:
Appendix VIII to Part 261--Hazardous Constituents
----------------------------------------------------------------------------------------------------------------
Chemical
Common name Chemical abstracts name abstracts Hazardous
No. waste No.
----------------------------------------------------------------------------------------------------------------
* * * * * *
*
Manganese................................... Same................................ 7439-96-5 ............
* * * * * *
*
----------------------------------------------------------------------------------------------------------------
PART 268--LAND DISPOSAL RESTRICTIONS
8. The authority citation for Part 268 continues to read as
follows:
Authority: 42 U.S.C. 6905, 6912(a), 6921, and 6924.
Subpart C--Prohibitions on Land Disposal
9. Section 268.36 is added to read as follows:
[[Page 55780]]
Sec. 268.36 Waste specific prohibitions--inorganic chemical wastes.
(a) Effective [date six months from date of publication of final
rule], the wastes specified in 40 CFR Part 261 as EPA Hazardous Wastes
Numbers K176, K177, and K178, and soil and debris contaminated with
these wastes, radioactive wastes mixed with these wastes, and soil and
debris contaminated with radioactive wastes mixed with these wastes are
prohibited from land disposal.
(b) The requirements of paragraph (a) of this section do not apply
if:
(1) The wastes meet the applicable treatment standards specified in
Subpart D of this Part;
(2) Persons have been granted an exemption from a prohibition
pursuant to a petition under Sec. 268.6, with respect to those wastes
and units covered by the petition;
(3) The wastes meet the applicable treatment standards established
pursuant to a petition granted under Sec. 268.44;
(4) Hazardous debris has met the treatment standards in Sec. 268.40
or the alternative treatment standards in Sec. 268.45; or
(5) Persons have been granted an extension to the effective date of
a prohibition pursuant to Sec. 268.5, with respect to these wastes
covered by the extension.
(c) To determine whether a hazardous waste identified in this
section exceeds the applicable treatment standards specified in
Sec. 268.40, the initial generator must test a sample of the waste
extract or the entire waste, depending on whether the treatment
standards are expressed as concentrations in the waste extract or the
waste, or the generator may use knowledge of the waste. If the waste
contains regulated constituents in excess of the applicable Subpart D
levels, the waste is prohibited from land disposal, and all
requirements of Part 268 are applicable, except as otherwise specified.
10. In Sec. 268.40, the Table is amended by adding in alphanumeric
order new entries for K176, K177, and K178 to read as follows:
Sec. 268.40 Applicability of treatment standards.
* * * * *
Treatment Standards for Hazardous Wastes
[Note: NA means not applicable]
--------------------------------------------------------------------------------------------------------------------------------------------------------
Regulated hazardous constituent Wastewaters Nonwastewaters
Waste description and -----------------------------------------------------------------------------------------------------------
Waste code treatment/regulatory Concentration in mg/kg5 unless
subcategory 1 Common name CAS 2 number Concentration in mg/L3, or noted as ``mg/L TCLP'', or
technology code 4 technology code
--------------------------------------------------------------------------------------------------------------------------------------------------------
* * * * * * *
K176............... Baghouse filters from Antimony.............. 7440-36-0 1.9............................. 1.15 mg/L TCLP
the production of Arsenic............... 7440-38-2 1.4............................. 5.0 mg/L TCLP
antimony oxide.
Cadmium............... 7440-43-9 0.69............................ 0.11 mg/L TCLP
Lead.................. 7439-92-1 0.69............................ 0.75 mg/L TCLP
Mercury............... 7439-97-6 0.15............................ 0.025 mg/L TCLP
K177............... Slag from the Antimony.............. 7440-36-0 1.9............................. 1.15 mg/L TCLP
production of Arsenic............... 7440-38-2 1.4............................. 5.0 mg/L TCLP
antimony oxide that Lead.................. 7439-92-1 0.60............................ 0.75 mg/L TCLP
is disposed of or
speculatively
accumulated.
K178............... Nonwastewaters from 1,2,3,4,6,7,8- 35822-39-4 0.000035 or CMBST11............. 0.0025 or CMBST11
the production of Heptachlorodibenzo-p- 67562-39-4 0.000035 or CMBST11............. 0.0025 or CMBST11
titanium dioxide by dioxin (1,2,3,4,6,7,8- 0.0025 or CMBST11
the chloride-ilmenite HpCDD).
process. [This 1,2,3,4,6,7,8-
listing does not Heptachlorodibenzofur
apply to chloride an (1,2,3,4,6,7,8-
process waste solids HpCDF).
from titanium
tetrachloride
production exempt
under section
261.4(b)(7).].
1,2,3,4,7,8,9- 55673-89-7 0.000035 or CMBST11............. 0.0025 or CMBST11
Heptachlorodibenzofur
an (1,2,3,4,7,8,9-
HpCDF).
HxCDDs (All 34465-46-8 0.000063 or CMBST11............. 0.001 or CMBST11
Hexachlorodibenzo-p-
dioxins).
HxCDFs (All 55684-94-1 0.000063 or CMBST11............. 0.001 or CMBST11
Hexachlorodibenzofura
ns).
1,2,3,4,6,7,8,9- 3268-87-9 0.000063 or CMBST11............. 0.005 or CMBST11
Octachlorodibenzo-p-
dioxin (OCDD).
1,2,3,4,6,7,8,9- 39001-02-0 0.000063 or CMBST11............. 0.005 or CMBST11
Octachlorodibenzofura
n (OCDF).
PeCDDs (All 36088-22-9 0.000063 or CMBST11............. 0.001 or CMBST11
Pentachlorodibenzo-p-
dioxins).
PeCDFs (All 30402-15-4 0.000035 or CMBST11............. 0.001 or CMBST11
Pentachlorodibenzofur
ans).
TCDDs (All 41903-57-5 0.000063 or CMBST11............. 0.001 or CMBST11
tetrachlorodibenzo-p-
dioxins).
TCDFs (All 55722-27-5 0.000063 or CMBST11............. 0.001 or CMBST11
tetrachlorodibenzofur
ans).
[[Page 55781]]
Manganese............. 7439-96-5 17.1............................ 3.6 mg/L TCLP
Thallium.............. 7440-28-0 1.4............................. 0.20 mg/L TCLP
* * * * * * *
--------------------------------------------------------------------------------------------------------------------------------------------------------
* * * * * * *
FOOTNOTES TO TREATMENT STANDARD TABLE 268.40
1 The waste descriptions provided in this table do not replace waste descriptions in 40 CFR part 261. Descriptions of Treatment/Regulatory
Subcategories are provided, as needed, to distinguish between applicability of different standards.
2 CAS means Chemical Abstract Services. When the waste code and/or regulated constituents are described as a combination of a chemical with its salts
and/or esters, the CAS number is given for the parent compound only.
3 Concentration standards for wastewaters are expressed in mg/L and are based on analysis of composite samples.
4 All treatment standards expressed as a Technology Code or combination of Technology Codes are explained in detail in 40 CFR 268.42 Table 1--Technology
Codes and Descriptions of Technology-Based Standards.
5 Except for Metals (EP or TCLP) and Cyanides (Total and Amenable) the nonwastewater treatment standards expressed as a concentration were established,
in part, based upon incineration in units operated in accordance with the technical requirements of 40 CFR part 264, Subpart O or 40 CFR part 265,
Subpart O, or based upon combustion in fuel substitution units operating in accordance with applicable technical requirements. A facility may comply
with these treatment standards according to provisions in 40 CFR 268.40(d). All concentration standards for nonwastewaters are based on analysis of
grab samples.
* * * * * * *
11 For these wastes, the definition of CMBST is limited to: (1) combustion units operating under 40 CFR 266, (2) combustion units permitted under 40 CFR
part 264, Subpart O, or (3) combustion units operating under 40 CFR 265, Subpart O, which have obtained a determination of equivalent treatment under
268.42(b).
11. In Sec. 268.48, the Table is amended by adding in alphabetical
order under the heading of ``Inorganic Constituents'' a new entry to
read as follows: (The footnotes are republished without change.)
Sec. 268.48 Universal treatment standards.
* * * * *
Universal Treatment Standards
[Note: NA means not applicable]
----------------------------------------------------------------------------------------------------------------
Wastewater Nonwastewater
standard standard
-------------------------------------
Regulated Constituent common name CAS \1\ number Concentration in mg/
Concentration kg \3\ unless noted
in mg/l \2\ as ``mg/l TCLP'
----------------------------------------------------------------------------------------------------------------
* * * * * *
*
Inorganic Constituents
* * * * * *
*
Manganese 7439-96-5 17.1 3.6 mg/l TCLP
* * * * * *
*
----------------------------------------------------------------------------------------------------------------
* * * * * * *
\1\ CAS means Chemical Abstract Services. When the waste code and/or regulated constituents are described as a
combination of a chemical with its salts and/or esters, the CAS number is given for the parent compound only.
\2\ Concentration standards for wastewaters are expressed in mg/L and are based on analysis of composite
samples.
\3\ Except for Metals (EP or TCLP) and Cyanides (Total and Amenable) the nonwastewater treatment standards
expressed as a concentration were established, in part, based upon incineration in units operated in
accordance with the technical requirements of 40 CFR Part 264, Subpart O, or Part 265, Subpart O, or based
upon combustion in fuel substitution units operating in accordance with applicable technical requirements. A
facility may comply with these treatment standards according to provisions in 40 CFR 268.40(d). All
concentration standards for nonwastewaters are based on analysis of grab samples.
* * * * *
PART 271--REQUIREMENTS FOR AUTHORIZATION OF STATE HAZARDOUS WASTE
PROGRAMS
12. The authority citation for Part 271 continues to read as
follows:
Authority: 42 U.S.C. 6905, 6912(a), and 6926.
13. Section 271.1(j) is amended by adding the following entries to
Table 1 and Table 2 in chronological order by date of publication to
read as follows.
Sec. 271.1 Purpose and scope.
* * * * *
(j) * * *
[[Page 55782]]
TABLE 1.--Regulations Implementing the Hazardous and Solid Waste
Amendments of 1984
------------------------------------------------------------------------
Title of Federal Register
Promulgation date regulation reference Effective date
------------------------------------------------------------------------
* * * *
* * *
[insert date of Listing of [insert Federal [insert
signature of Hazardous Wastes Register page effective date
final rule] K176, K177, and numbers] of final rule]
K178
* * * *
* * *
------------------------------------------------------------------------
Table 2.--Self-Implementing Provisions of the Solid Waste Amendments of
1984
------------------------------------------------------------------------
Self-implementing Federal Register
Effective date provision RCRA citation reference
------------------------------------------------------------------------
* * * *
* * *
[effective date Prohibition on 3004(g)(4)(C) [date of
of final rule]. land disposal of and 3004(m). publication of
K176, K177, and final rule] [FR
K178 wastes, and page numbers].
prohibition on
land disposal of
radioactive
waste mixed with
K176, K177, and
K178 wastes,
including soil
and debris.
* * * *
* * *
------------------------------------------------------------------------
PART 302--DESIGNATION, REPORTABLE QUANTITIES, AND NOTIFICATION
14. The authority citation for Part 302 continues to read as
follows:
Authority: 42 U.S.C. 9602, 9603, and 9604; 33 U.S.C. 1321 and
1361.
15. In Sec. 302.4, Table 302.4 is amended by adding the following
new entries in alphanumeric order at the end of the table to read as
follows:
Sec. 302.4 Designation of hazardous substances
* * * * *
Table 302.4.--List of Hazardous Substances and Reportable Quantities
[Note: All Comments/Notes Are Located at the End of This Table]
----------------------------------------------------------------------------------------------------------------
Statutory Final RQ
Regulatory -----------------------------------------------------------
Hazardous substance CASRN synonyms RCRA Waste Pounds
RQ Code Number Category (Kg)
--------------------------------------------------------------------------------------------------------
* * * * * *
*
K176........................ .......... .......... *1 4 K176 X 1 (0.454)
Baghouse filters from the
production of antimony
oxide.
K177........................ .......... .......... *1 4 K177 X 5,000
(2,270)
Slag from the production of
antimony oxide.
K178........................ .......... .......... *1 4 K178 X #
Nonwastewaters from the
production of titanium
dioxide by the chloride-
ilmenite process. [This
listing does not apply to
chloride process waste
solids from titanium
tetrachloride production
exempt under section
261.4(b)(7).] .............
----------------------------------------------------------------------------------------------------------------
Indicates the statutory source as defined by 1, 2, 3, and 4 below.
* * * * * *
*
4-Indicates that the statutory source for designation of this hazardous substance under CERCLA is RCRA Section
3001.
1* Indicates that the 1-pound RQ is a CERCLA statutory RQ.
# The Agency may adjust the statutory RQ for this hazardous substance in a future rulemaking; until then the
statutory RQ applies.
* * * * * *
*
[FR Doc. 00-22810 Filed 9-13-00; 8:45 am]
BILLING CODE 6560-50-U