[Federal Register Volume 65, Number 69 (Monday, April 10, 2000)]
[Proposed Rules]
[Pages 19046-19150]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-8155]
[[Page 19045]]
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Part II
Environmental Protection Agency
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40 CFR Parts 141 and 142
National Primary Drinking Water Regulations: Long Term 1 Enhanced
Surface Water Treatment and Filter Backwash Rule; Proposed Rule
Federal Register / Vol. 65, No. 69 / Monday, April 10, 2000 /
Proposed Rules
[[Page 19046]]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Parts 141 and 142
[WH-FRL-6570-5]
RIN 2040-AD18
National Primary Drinking Water Regulations: Long Term 1 Enhanced
Surface Water Treatment and Filter Backwash Rule
AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed rule.
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SUMMARY: In this document, EPA is proposing the Long Term 1 Enhanced
Surface Water Treatment and Filter Backwash Rule (LT1FBR). The purposes
of the LT1FBR are to: Improve control of microbial pathogens in
drinking water, including Cryptosporidium, for public water systems
(PWSs) serving fewer than 10,000 people; prevent increases in microbial
risk while PWSs serving fewer than 10,000 people control for
disinfection byproducts, and; require certain PWSs to institute changes
to the return of recycle flows within the treatment process to reduce
the effects of recycle on compromising microbial control. Today's
proposal addresses two statutory requirements of the 1996 Safe Drinking
Water Act (SDWA) Amendments. First, it addresses the statutory
requirement to establish a Long Term Final Enhanced Surface Water
Treatment Rule (LTESWTR) for PWSs that serve under 10,000 people.
Second, it addresses the statutory requirement to promulgate a
regulation which ``governs'' the recycle of filter backwash within the
treatment process of public utilities.
Today's proposed LT1FBR contains 5 key provisions for surface water
and ground water under the direct influence of surface water (GWUDI)
systems serving fewer than 10,000 people: A treatment technique
requiring a 2-log (99 percent) Cryptosporidium removal requirement;
strengthened combined filter effluent turbidity performance standards
and new individual filter turbidity provisions; disinfection benchmark
provisions to assure continued microbial protection is provided while
facilities take the necessary steps to comply with new disinfection
byproduct standards; inclusion of Cryptosporidium in the definition of
GWUDI and in the watershed control requirements for unfiltered public
water systems; and requirements for covers on new finished water
reservoirs.
Today's proposed LT1FBR contains three key provisions for all
conventional and direct filtration systems which recycle and use
surface water or GWUDI: A provision requiring recycle flows to be
introduced prior to the point of primary coagulant addition; a
requirement for systems meeting criteria to perform a one-time self
assessment of their recycle practice and consult with their primacy
agency to address and correct high risk recycle operations; and a
requirement for direct filtration systems to provide information to the
State on their current recycle practice.
The Agency believes implementing the provisions contained in
today's proposal will improve public health protection in two
fundamental ways. First, the provisions will reduce the level of
Cryptosporidium in filtered finished drinking water supplies through
improvements in filtration and recycle practice resulting in a reduced
likelihood of outbreaks of cryptosporidiosis. Second, the filtration
provisions are expected to increase the level of protection from
exposure to other pathogens (i.e. Giardia or other waterborne bacterial
or viral pathogens). It is also important to note that while today's
proposed rule contains new provisions which in some cases strengthen or
modify requirements of the 1989 Surface Water Treatment Rule, each
public water system must continue to comply with the current rules
while new microbial and disinfectants/disinfection byproducts rules are
being developed. In conjunction with the Maximum Contaminant Level Goal
(MCLG) established in the Interim Enhanced Surface Water Treatment
Rule, the Agency developed a treatment technique in lieu of a Maximum
Contaminant Level (MCL) for Cryptosporidium because it is not
economically and technologically feasible to accurately ascertain the
level of Cryptosporidium using current analytical methods.
DATES: The Agency requests comments on today's proposal. Comments must
be received or post-marked by midnight June 9, 2000. Comments received
after this date may not be considered in decision making on the
proposed rule.
ADDRESSES: Send written comments on today's proposed rule to the LT1FBR
Comment Clerk: Water Docket MC 410, W-99-10, Environmental Protection
Agency 401 M Street, S.W., Washington, DC 20460. Please submit an
original and three copies of comments and enclosures (including
references).
Those who comment and want EPA to acknowledge receipt of their
comments must enclose a self-addressed stamped envelope. No facsimiles
(faxes) will be accepted. Comments may also be submitted electronically
to [email protected]. For additional information on submitting
electronic comments see Supplementary Information Section.
Public comments on today's proposal, other major supporting
documents, and a copy of the index to the public docket for this
rulemaking are available for review at EPA's Office of Water Docket:
401 M Street, SW., Rm. EB57, Washington, DC 20460 from 9:00 a.m. to
4:00 p.m., Eastern Time, Monday through Friday, excluding legal
holidays. For access to docket materials or to schedule an appointment
please call (202) 260-3027.
FOR FURTHER INFORMATION CONTACT: Technical inquiries on the rule should
be directed to Jeffery Robichaud at 401 M Street, SW., MC4607,
Washington, DC 20460 or (202) 260-2568. For general information contact
the Safe Drinking Water Hotline, Telephone (800) 426-4791. The Safe
Drinking Water Hotline is open Monday through Friday, excluding federal
holidays, from 9:00 a.m. to 5:30 p.m. Eastern Time.
SUPPLEMENTARY INFORMATION: Entities potentially regulated by the LT1FBR
are public water systems (PWSs) that use surface water or ground water
under the direct influence of surface water (GWUDI). The recycle
control provisions are applicable to all PWSs using surface water or
GWUDI, regardless of the population served. All other provisions of the
LT1FBR are only applicable to PWSs serving under 10,000 people.
Regulated categories and entities include:
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Category Examples of regulated entities
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Industry..................... Public Water Systems that use surface
water or ground water under the direct
influence of surface water.
State, Local, Tribal or Public Water Systems that use surface
Federal Governments. water or ground water under the direct
influence of surface water.
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[[Page 19047]]
This table is not intended to be exhaustive, but rather provides a
guide for readers regarding entities likely to be regulated by the
LT1FBR. This table lists the types of entities that EPA is now aware
could potentially be regulated by this rule. Other types of entities
not listed in this table could also be regulated. To determine whether
your facility is regulated by this action, you should carefully examine
the definition of public water system in Sec. 141.3 of the Code of
Federal Regulations and applicability criteria in Secs. 141.76 and
141.501 of today's proposal. If you have questions regarding the
applicability of the LT1FBR to a particular entity, consult the person
listed in the preceding section entitled FOR FURTHER INFORMATION
CONTACT.
Submitting Comments
Send an original and three copies of your comments and enclosures
(including references) to W-99-10 Comment Clerk, Water Docket (MC4101),
USEPA, 401 M Street, SW., Washington, D.C. 20460. Comments must be
received or post-marked by midnight June 9, 2000. Note that the Agency
is not soliciting comment on, nor will it respond to, comments on
previously published regulatory language that is included in this
document to ease the reader's understanding of the proposed language.
To ensure that EPA can read, understand and therefore properly
respond to comments, the Agency would prefer that commenters cite,
where possible, the paragraph(s) or sections in the proposed rule or
supporting documents to which each comment refers. Commenters should
use a separate paragraph for each issue discussed.
Electronic Comments
Comments may also be submitted electronically to [email protected]. Electronic comments must be submitted as an
ASCII, WP5.1, WP6.1 or WP8 file avoiding the use of special characters
and form of encryption. Electronic comments must be identified by the
docket number W-99-10. Comments and data will also be accepted on disks
in WP 5.1, 6.1, 8 or ASCII file format. Electronic comments on this
document may be filed online at many Federal Depository Libraries.
The record for this rulemaking has been established under docket
number W-99-10, and includes supporting documentation as well as
printed, paper versions of electronic comments. The record is available
for inspection from 9 a.m. to 4 p.m., Monday through Friday, excluding
legal holidays at the Water Docket, EB 57, USEPA Headquarters, 401 M
Street, SW., Washington, D.C. For access to docket materials, please
call (202) 260-3027 to schedule an appointment.
List of Abbreviations Used in This Document
ASCE American Society of Civil Engineers
ASDWA Association of State Drinking Water Administrators
ASTM American Society for Testing Materials
AWWA American Water Works Association
AWWARF American Water Works Association Research Foundation
deg.C Degrees Centigrade
CCP Composite Correction Program
CDC Centers for Disease Control
CFE Combined Filter Effluent
CFR Code of Federal Regulations
COI Cost of Illness
CPE Comprehensive Performance Evaluation
CT The Residual Concentration of Disinfectant (mg/L) Multiplied by the
Contact Time (in minutes)
CTA Comprehensive Technical Assistance
CWSS Community Water System Survey
DBPs Disinfection Byproducts
DBPR Disinfectants/Disinfection Byproducts Rule
ESWTR Enhanced Surface Water Treatment Rule
FACA Federal Advisory Committee Act
GAC Granular Activated Carbon
GAO Government Accounting Office
GWUDI Ground Water Under the Direct Influence of Surface Water
HAA5 Haloacetic acids (Monochloroacetic, Dichloroacetic,
Trichloroacetic, Monobromoacetic and Dibromoacetic Acids)
HPC Heterotropic Plate Count
hrs Hours
ICR Information Collection Rule
IESWTR Interim Enhanced Surface Water Treatment Rule
IFA Immunofluorescence Assay
Log Inactivation Logarithm of (No/NT)
Log Logarithm (common, base 10)
LTESWTR Long Term Enhanced Surface Water Treatment Rule
LT1FBR Long Term 1 Enhanced Surface Water Treatment and Filter
Backwash Rule
MCL Maximum Contaminant Level
MCLG Maximum Contaminant Level Goal
MGD Million Gallons per Day
M-DBP Microbial and Disinfectants/Disinfection Byproducts
MPA Microscopic Particulate Analysis
NODA Notice of Data Availability
NPDWR National Primary Drinking Water Regulation
NT The Concentration of Surviving Microorganisms at Time T
NTTAA National Technology Transfer and Advancement Act
NTU Nephelometric Turbidity Unit
PE Performance Evaluation
PWS Public Water System
Reg. Neg. Regulatory Negotiation
RIA Regulatory Impact Analysis
RFA Regulatory Flexibility Act
RSD Relative Standard Deviation
SAB Science Advisory Board
SDWA Safe Drinking Water Act
SWTR Surface Water Treatment Rule
TC Total Coliforms
TCR Total Coliform Rule
TTHM Total Trihalomethanes
TWG Technical Work Group
TWS Transient Non-Community Water System
UMRA Unfunded Mandates Reform Act
URCIS Unregulated Contaminant Information System
x log removal Reduction to 1/10\x\ of original concentration
Table of Contents
I. Introduction and Background
A. Statutory Requirements and Legal Authority
B. Existing Regulations and Stakeholder Involvement
1. 1979 Total Trihalomethane Rule
2. Total Coliform Rule
3. Surface Water Treatment Rule
4. Information Collection Rule
5. Interim Enhanced Surface Water Treatment Rule
6. Stage 1 Disinfectants and Disinfection Byproduct Rule
7. Stakeholder Involvement
II. Public Health Risk
A. Introduction
B. Health Effects of Cryptosporidiosis and Sources and Transmission
of Cryptosporidium
C. Waterborne Disease Outbreaks In the United States
D. Source Water Occurrence Studies
E. Filter Backwash and Other Process Streams: Occurrence and Impact
Studies
F. Summary and Conclusions
III. Baseline Information-Systems Potentially Affected By Today's
Proposed Rule
IV. Discussion of Proposed LT1FBR Requirements
A. Enhanced Filtration Requirements
1. Two Log Cryptosporidium Removal Requirement
a. Two Log Removal
i. Overview and Purpose
ii. Data
iii. Proposed Requirements
iv. Request for Comments
2. Turbidity Requirements
a. Combined Filter Effluent
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i. Overview and Purpose
ii. Data
iii. Proposed Requirements
iv. Request for Comments
b. Individual Filter Turbidity
i. Overview and Purpose
ii. Data
iii. Proposed Requirements
iv. Request for Comments
B. Disinfection Benchmarking Requirements
1. Applicability Monitoring
a. Overview and Purpose
b. Data
c. Proposed Requirements
d. Request for Comment
2. Disinfection Profiling
a. Overview and Purpose
b. Data
c. Proposed Requirements
d. Request for Comments
3. Disinfection Benchmarking
a. Overview and Purpose
b. Data
c. Proposed Requirements
d. Request for Comments
C. Additional Requirements
1. Inclusion of Cryptosporidium In Definition of GWUDI
a. Overview and Purpose
b. Data
c. Proposed Requirements
d. Request for Comments
2. Inclusion of Cryptosporidium Watershed Requirements for
Unfiltered Systems
a. Overview and Purpose
b. Data
c. Proposed Requirements
d. Request for Comments
3. Requirements for Covering New Reservoirs
a. Overview and Purpose
b. Data
c. Proposed Requirements
d. Request for Comments
D. Recycle Provisions for Public Water Systems Employing Rapid
Granular Filtration Using Surface Water and GWUDI as a Source
1. Treatment Processes that Commonly Recycle and Recycle Flow
Occurrence Data
a. Treatment Processes that Commonly Recycle
i. Conventional Treatment Plants
ii. Direct Filtration Plants
iii. Softening Plants
iv. Contact Clarification Plants
v. Package Plants
vi. Summary of Recycle Disposal Options
b. Recycle Flow Occurrence Data
i. Untreated Spent Filter Backwash Water
ii. Gravity Settled Spent Filter Backwash Water
iii. Combined Gravity Thickener Supernatant
iv. Gravity Thickener Supernatant from Sedimentation Solids
v. Mechanical Dewatering Device Liquids
2. National Recycle Practices
a. Information Collection Rule
i. Recycle Practice
b. Recycle FAX Survey
i. Recycle practice
ii. Options to recycle
iii. Conclusions
3. Recycle Provisions for PWSs Employing Rapid Granular
Filtration Using Surface Water or Ground Water Under the Direct
Influence of Surface Water Influence of Surface Water
a. Return Select Recycle Streams Prior to the Point of Primary
Coagulant Addition
i. Overview and Purpose
ii. Data
iii. Proposed Requirements
iv. Request for Comments
b. Recycle Requirements for Systems Practicing Direct Recycle
and Meeting Specific Criteria
i. Overview and Purpose
ii. Data
iii. Proposed Requirements
iv. Request for Comments
c. Requirements for Direct Filtration Plants that Recycle Using
Surface Water or GWUDI
i. Overview and Purpose
ii. Data
iii. Proposed Requirements
iv. Request for Comments
d. Request for Additional Comment
V. State Implementation and Compliance Schedules
A. Special State Primacy Requirements
B. State Recordkeeping Requirements
C. State Reporting Requirements
D. Interim Primacy
E. Compliance Deadlines
VI. Economic Analysis
A. Overview
B. Quantifiable and Non-Quantifiable Costs
1. Total Annual Costs
2. Annual Costs of Rule Provisions
3. Non Quantifiable Costs
C. Quantifiable and Non-Quantifiable Health Benefits
1. Quantified Health Benefits
2. Non-Quantified Health and Non-Health Related Benefits
a. Recycle Provisions
b. Issues Associated with Unquantified Benefits
D. Incremental Costs and Benefits
E. Impacts on Households
F. Benefits From the Reduction of Co-Occurring Contaminants
G. Risk Increases From Other Contaminants
H. Other Factors: Uncertainty in Risk, Benefits, and Cost Estimates
I. Benefit Cost Determination
J. Request for Comment
VII. Other Requirements
A. Regulatory Flexibility Act
1. Today's Proposed Rule
2. Use of Alternative Definition
3. Background and Analysis
a. Number of Small Entities Affected
b. Recordkeeping and Reporting
c. Interaction with Other Federal Rules
d. Significant Alternatives
i. Turbidity Provisions
ii. Disinfection Benchmarking Applicability Monitoring
Provisions
iii. Recycling Provisions
e. Other Comments
B. Paperwork Reduction Act
C. Unfunded Mandates Reform Act
1. Summary of UMRA requirements
2. Written Statement for Rules With Federal Mandates of $100
Million or More
a. Authorizing Legislation
b. Cost Benefit Analysis
c. Estimates of Future Compliance Costs and Disproportionate
Budgetary Effects
d. Macro-economic Effects
e. Summary of EPA's Consultation with State, Local, and Tribal
Governments and Their Concerns
f. Regulatory Alternatives Considered
g. Selection of the Least Costly, Most-Cost Effective or Least
Burdensome Alternative That Achieves the Objectives of the Rule
3. Impacts on Small Governments
D. National Technology Transfer and Advancement Act
E. Executive Order 12866: Regulatory Planning and Review
F. Executive Order 12898: Environmental Justice
G. Executive Order 13045: Protection of Children from Environmental
Health Risks and Safety Risks
H. Consultations with the Science Advisory Board, National Drinking
Water Advisory Council, and the Secretary of Health and Human
Services
I. Executive Order 13132: Executive Orders on Federalism
J. Executive Order 13084: Consultation and Coordination With Indian
Tribal Governments
K. Likely Effect of Compliance with the LT1FBR on the Technical,
Financial, and Managerial Capacity of Public Water Systems
L. Plain Language
VIII. Public Comment Procedures
A. Deadlines for Comment
B. Where to Send Comment
C. Guidelines for Commenting
IX. References
I. Introduction and Background
A. Statutory Requirements and Legal Authority
The Safe Drinking Water Act (SDWA or the Act), as amended in 1986,
requires U.S. Environmental Protection Agency (EPA) to publish a
maximum contaminant level goal (MCLG) for each contaminant which, in
the judgement of the EPA Administrator, ``may have any adverse effect
on the health of persons and which is known or anticipated to occur in
public water systems' (Section 1412(b)(3)(A)). MCLGs are to be set at a
level at which ``no known or anticipated adverse effect on the health
of persons occur and which allows an adequate margin of safety''
(Section 1412(b)(4)).
The Act was again amended in August 1996, resulting in the
renumbering and augmentation of certain sections with additional
statutory language. New sections were added establishing new drinking
water requirements. These modifications are outlined below.
The Act requires EPA to publish a National Primary Drinking Water
Regulation (NPDWR) that specifies
[[Page 19049]]
either a maximum contaminant level (MCL) or treatment technique
(Sections 1401(1) and 1412(a)(3)) at the same time it publishes an
MCLG, which is a non-enforceable health goal. EPA is authorized to
promulgate a NPDWR ``that requires the use of a treatment technique in
lieu of establishing an MCL,'' if the Agency finds that ``it is not
economically or technologically feasible to ascertain the level of the
contaminant.'' EPA's general authority to set MCLGs and NPDWRs applies
to contaminants that may ``have an adverse effect on the health of
persons,'' that are ``known to occur or there is a substantial
likelihood that the contaminant will occur in public water systems with
a frequency and at levels of public health concern,'' and for which
``in the sole judgement of the Administrator, regulation of such
contaminant presents a meaningful opportunity for health risk reduction
for persons served by public water systems'' (SDWA Section
1412(b)(1)(A)).
The 1996 amendments, also require EPA, when proposing a NPDWR that
includes an MCL or treatment technique, to publish and seek public
comment on an analysis of health risk reduction and cost impacts. EPA
is required to take into consideration the effects of contaminants upon
sensitive subpopulations (i.e., infants, children, pregnant women, the
elderly, and individuals with a history of serious illness), and other
relevant factors (Section 1412(b)(3)(C)).
The amendments established a number of regulatory deadlines,
including schedules for a Stage 1 Disinfection Byproduct Rule (DBPR),
an Interim Enhanced Surface Water Treatment Rule (IESWTR), a Long Term
Final Enhanced Surface Water Treatment Rule (LTESWTR), and a Stage 2
DBPR (Section 1412(b)(2)(C)). To provide additional time for systems
serving fewer than 10,000 people to comply with the IESWTR provisions
and also ensure these systems implement Stage 1 DBPR and the IESWTR
provisions simultaneously, the Agency split the IESWTR into two rules:
the IESWR and the LT1ESWTR. The Act as amended also requires EPA to
promulgate regulations to ``govern'' the recycle of filter backwash
within the treatment process of public utilities (Section 1412(b)(14)).
Under 1412(b)(4)(E)(ii), EPA must develop a Small System Technology
List for the LT1FBR. The filtration technologies listed in the Small
System Compliance Technology List for the Surface Water Treatment Rule
and Total Coliform Rule (EPA-815-R-98-001, September 1998) are also the
technologies which would achieve compliance with the provisions of the
LT1FBR. EPA will develop a separate list for the LT1FBR as new
technologies become available.
Although the Act permits small system variances for compliance with
a requirement of a national primary drinking water regulation which
specifies a maximum contaminant level or treatment technique, Section
1415(e)(6)(B) of SDWA, excludes variances for any national primary
drinking water regulation for a microbial contaminant or an indicator
or treatment technique for a microbial contaminant. LT1FBR requires
treatment techniques to control Cryptosporidium (a microbial
contaminant), and as such systems governed by the LT1FBR are ineligible
for variances.
Finally, as part of the 1996 SDWA Amendments, recordkeeping
requirements were modified to apply to every person who is subject to a
requirement of this title or who is a grantee (Section 1445(a)(1)(A)).
Such persons are required to establish and maintain such records, make
such reports, conduct such monitoring, and provide such information as
the Administrator may reasonably require by regulation.
B. Existing Regulations and Stakeholder Involvement
1. 1979 Total Trihalomethane Rule
In November 1979 (44 FR 68624) (EPA, 1979) EPA set an interim MCL
for total trihalomethanes (TTHM--the sum of chloroform, bromoform,
bromodichloromethane, dibromochloromethane) of 0.10 mg/l as an annual
average. Compliance is defined on the basis of a running annual average
of quarterly averages for four samples taken in the distribution
system. The value for each sample is the sum of the measured
concentrations of chloroform, bromodichloromethane,
dibromochloromethane and bromoform.
The interim TTHM standard applies to community water systems using
surface water and/or ground water serving at least 10,000 people that
add a disinfectant to the drinking water during any part of the
treatment process. At their discretion, States may extend coverage to
smaller PWSs; however, most States have not exercised this option. The
Stage 1 DBPR (as discussed later) contains updated TTHM requirements.
2. Total Coliform Rule
The Total Coliform Rule (TCR) (54 FR 27544, June 29, 1989) (EPA,
1989a) applies to all public water systems. The TCR sets compliance
with the Maximum Contaminant Level (MCL) for total coliforms (TC) as
follows. For systems that collect 40 or more samples per month, no more
than 5 percent of the samples may be TC-positive; for those that
collect fewer than 40 samples, no more than one sample may be TC-
positive. If a system has a TC-positive sample, it must test that
sample for the presence of fecal coliforms or E. coli. The system must
also collect a set of repeat samples, and analyze for TC (and fecal
coliform or E. coli within 24 hours of the first TC-positive sample).
In addition, any fecal coliform-positive repeat sample, E-coli.-
positive repeat sample, or any total-coliform-positive repeat sample
following a fecal coliform-positive or E-coli-positive routine sample
constitutes an acute violation of the MCL for total coliforms. If a
system exceeds the MCL, it must notify the public using mandatory
language developed by the EPA. The required monitoring frequency for a
system depends on the number of people served and ranges from 480
samples per month for the largest systems to once annually for the
smallest systems. All systems must have a written plan identifying
where samples are to be collected.
The TCR also requires an on-site inspection (referred to as a
sanitary survey) every 5 years for each system that collects fewer than
five samples per month. This requirement is extended to every 10 years
for non-community systems using only protected and disinfected ground
water.
3. Surface Water Treatment Rule
Under the Surface Water Treatment Rule (SWTR) (54 FR 27486, June
29, 1989) (EPA, 1989b), EPA set maximum contaminant level goals of zero
for Giardia lamblia, viruses, and Legionella and promulgated regulatory
requirements for all PWSs using surface water sources or ground water
sources under the direct influence of surface water. The SWTR includes
treatment technique requirements for filtered and unfiltered systems
that are intended to protect against the adverse health effects of
exposure to Giardia lamblia, viruses, and Legionella, as well as many
other pathogenic organisms. Briefly, those requirements include (1)
Requirements for maintenance of a disinfectant residual in the
distribution system; (2) removal and/or inactivation of 3 log (99.9
percent) for Giardia and 4 log (99.99 percent) for viruses; (3)
combined filter effluent turbidity performance standard of 5
nephelometric turbidity units (NTU) as a maximum and 0.5 NTU
[[Page 19050]]
at the 95th percentile monthly, based on 4-hour monitoring for
treatment plants using conventional treatment or direct filtration
(with separate standards for other filtration technologies); and (4)
watershed protection and other requirements for unfiltered systems.
Systems seeking to avoid filtration were required to meet avoidance
criteria and obtain avoidance determination by December 30, 1991,
otherwise filtration must have been provided by June 29, 1993. For
systems properly avoiding filtration, later failures to meet avoidance
criteria triggered a requirement that filtration be provided within 18
months.
4. Information Collection Rule
The Information Collection Rule (ICR), which was promulgated on May
14, 1996 (61 FR 24354) (EPA, 1996) applied to large public water
systems serving populations of 100,000 or more. A more limited set of
ICR requirements pertain to ground water systems serving between 50,000
and 100,000 people. About 300 PWSs operating 500 treatment plants were
involved with the extensive ICR data collection. Under the ICR, these
PWSs monitored for water quality factors affecting disinfection
byproduct (DBP) formation and DBPs within the treatment plant and in
the distribution system on a monthly basis for 18 months. In addition,
PWSs were required to provide treatment train schematics, operating
data and source water occurrence data for bacteria, viruses, and
protozoa. Finally, a subset of PWSs performed treatment studies, using
either granular activated carbon (GAC) or membrane processes, to
evaluate DBP precursor removal and control of DBPs. Monitoring for
treatment study applicability began in September 1996. The remaining
occurrence monitoring began in July 1997 and concluded in December
1998.
The purpose of the ICR was to collect occurrence and treatment
information to help evaluate the need for possible changes to the
current microbial requirements and existing microbial treatment
practices, and to help evaluate the need for future regulation of
disinfectants and disinfection byproducts (DBPs). The ICR will provide
EPA with additional information on the national occurrence in drinking
water of (1) chemical byproducts that form when disinfectants used for
microbial control react with naturally occurring compounds already
present in source water; and (2) disease-causing microorganisms,
including Cryptosporidium, Giardia, and viruses. Analysis of ICR data
is not expected to be completed in the time frame necessary for
inclusion in the LT1FBR, however if the data is available and has been
quality controlled and peer reviewed during the necessary time frame,
EPA will consider the datat as it refines its analysis for the final
rule.
The ICR also required PWSs to provide engineering data on how they
currently control for such contaminants. The ICR monthly sampling data
will also provide information on the quality of the recycle waters via
monthly monitoring (for 18 months) of pH, alkalinity, turbidity,
temperature, calcium and total hardness, TOC, UV254,
bromide, ammonia, and disinfectant residual (if disinfectant is used).
This data will provide some indication of the treatability of the
water, the extent to which contaminant concentration effects may occur,
and the potential for contribution to DBP formation. However, sampling
to determine the occurrence of pathogens in recycle waters was not
performed.
5. Interim Enhanced Surface Water Treatment Rule
Public water systems serving 10,000 or more people that use surface
water or ground water under the direct influence of surface water
(GWUDI) are required to comply with the IESWTR (63 FR 69477, December
16, 1998) (EPA, 1998a) by December of 2001. The purposes of the IESWTR
are to improve control of microbial pathogens, specifically the
protozoan Cryptosporidium, and address risk trade-offs between
pathogens and disinfection byproducts. Key provisions established by
the rule include: a Maximum Contaminant Level Goal (MCLG) of zero for
Cryptosporidium; 2-log (99 percent) Cryptosporidium removal
requirements for systems that filter; strengthened combined filter
effluent turbidity performance standards of 1.0 NTU as a maximum and
0.3 NTU at the 95th percentile monthly, based on 4-hour monitoring for
treatment plants using conventional treatment or direct filtration;
requirements for individual filter turbidity monitoring; disinfection
benchmark provisions to assess the level of microbial protection
provided as facilities take the necessary steps to comply with new
disinfection byproduct standards; inclusion of Cryptosporidium in the
definition of GWUDI and in the watershed control requirements for
unfiltered public water systems; requirements for covers on new
finished water reservoirs; and sanitary surveys for all surface water
systems regardless of size.
6. Stage 1 Disinfectants and Disinfection Byproduct Rule
The Stage 1 DBPR applies to all PWSs that are community water
systems (CWSs) or nontransient noncommunity water systems (NTNCWs) that
treat their water with a chemical disinfectant for either primary or
residual treatment. In addition, certain requirements for chlorine
dioxide apply to transient noncommunity water systems (TNCWSs). The
Stage 1 DBPR (EPA, 1998c) was published at the same time as the IESWTR
(63 FR 69477, December 16, 1998) (EPA, 1998a). Surface water and GWUDI
systems serving at least 10,000 persons are required to comply with the
Stage 1 Disinfectants and Disinfection Byproducts Rule by December
2001. Ground water systems and surface water and GWUDI systems serving
fewer than 10,000 must comply with the Stage 1 Disinfectants and
Disinfection Byproducts Rule by December 2003.
The Stage 1 DBPR finalizes maximum residual disinfectant level
goals (MRDLGs) for chlorine, chloramines, and chlorine dioxide; MCLGs
for four trihalomethanes (chloroform, bromodichloromethane,
dibromochloromethane, and bromoform), two haloacetic acids
(dichloroacetic acid and trichloroacetic acid), bromate, and chlorite;
and NPDWRs for three disinfectants (chlorine, chloramines, and chlorine
dioxide), two groups of organic disinfection byproducts TTHMs and HAA5
and two inorganic disinfection byproducts, chlorite and bromate. The
NPDWRs consist of maximum residual disinfectant levels (MRDLs) or
maximum contaminant levels (MCLs) or treatment techniques for these
disinfectants and their byproducts. The NPDWRs also include monitoring,
reporting, and public notification requirements for these compounds.
The Stage 1 DBPR includes the best available technologies (BATs) upon
which the MRDLs and MCLs are based. EPA believes the implementation of
the Stage 1 DBPR will reduce the levels of disinfectants and
disinfection byproducts in drinking water supplies. The Agency believes
the rule will provide public health protection for an additional 20
million households that were not previously covered by drinking water
rules for disinfection byproducts.
7. Stakeholder Involvement
EPA conducted two stakeholder meetings to solicit feedback and
information from the regulated community and other concerned
stakeholders on issues relating to
[[Page 19051]]
today's proposed rule. The first meeting was held July 22 and 23, 1998
in Lakewood, Colorado. EPA presented potential regulatory components
for the LT1FBR. Breakout sessions with stakeholders were held to
generate feedback on the regulatory provisions being considered and to
solicit feedback on next steps for rule development and stakeholder
involvement. Additionally, information was presented summarizing
ongoing research and data gathering activities regarding the recycle of
filter backwash. The presentations generated useful discussion and
provided substantial feedback to EPA regarding technical issues,
stakeholder concerns, and possible regulatory options (EPA 1999k). The
second stakeholder meeting was held in Dallas, Texas on March 3 and 4,
1999. EPA presented new analyses, summaries of current research, and
revised regulatory options and data collected since the July
stakeholder meeting. Regional perspectives on turbidity and
disinfection benchmarking components were also discussed with
presentations from EPA Region VI and the Texas Natural Resources
Conservation Commission. Four break-out sessions were extremely useful
and generated a wide range of information, issues, and technical input
from a diverse group of stakeholders (EPA 1999j).
The Agency utilized the feedback received during these two
stakeholder meetings in developing today's proposed rule. EPA also
mailed a draft version of the preamble for today's proposed rule to the
attendees of these meetings. Several of the options which are presented
today represent modifications suggested by stakeholders.
II. Public Health Risk
The purpose of this section is to discuss the health risk
associated with pathogens, particularly Cryptosporidium, in surface
waters and GWUDI. More detailed information about such pathogens and
other contaminants of concern may be found in an EPA criteria document
for Giardia (EPA 1998d), three EPA criteria documents for viruses (EPA,
1985; 1999a; 1999b), the Cryptosporidium and Giardia Occurrence
Assessment for the Interim Enhanced Surface Water Treatment Rule (EPA,
1998b) and the LT1FBR Occurrence and Assessment Document (EPA 1999c).
EPA requests comment on today's proposed rule, the information
supporting the proposal, and the potential impact of proposed
regulatory provisions on public health risk.
A. Introduction
In 1990, EPA's Science Advisory Board (SAB), an independent panel
of experts established by Congress, cited drinking water contamination
as one of the most important environmental risks and indicated that
disease-causing microbial contaminants (i.e., bacteria, protozoa and
viruses) are probably the greatest remaining health risk management
challenge for drinking water suppliers (EPA/SAB, 1990). Information on
the number of waterborne disease outbreaks from the U.S. Centers for
Disease Control and Prevention (CDC) underscores this concern. CDC
indicates that, between 1980 and 1996, 401 waterborne disease outbreaks
were reported, with over 750,000 associated cases of disease. During
this period, a number of agents were implicated as the cause, including
protozoa, viruses and bacteria.
Waterborne disease caused by Cryptosporidium is of particular
concern, as it is difficult to inactivate Cryptosporidium oocysts with
standard disinfection practices (unlike pathogens such as viruses and
bacteria), and there is currently no therapeutic treatment for
cryptosporidiosis (unlike giardiasis). Because Cryptosporidium is not
generally inactivated in systems using standard disinfection practices,
the control of Cryptosporidium is dependent on physical removal
processes (e.g., filtration).
The filter effluent turbidity limits specified under the SWTR were
created to remove large parasite cysts such as Giardia and did not
specifically control for smaller Cryptosporidium oocysts. In addition,
filter backwash water recycling practices such as adding recycled water
to the treatment train after primary coagulant addition may overwhelm
the plant and harm efforts to control Giardia lamblia, Cryptosporidium,
and emerging pathogens. Despite filtration and disinfection,
Cryptosporidium oocysts have been found in filtered drinking water
(LeChevallier, et al., 1991a; EPA, 1999c), and many of the individuals
affected by waterborne disease outbreaks caused by Cryptosporidium were
served by filtered surface water supplies (Solo-Gabriele and
Neumeister, 1996). Surface water systems that filter and disinfect may
still be vulnerable to Cryptosporidium, depending on the source water
quality and treatment effectiveness. EPA believes that today's
proposal, however, will ensure that drinking water treatment is
operating efficiently to control Cryptosporidium (see Sections IV.A and
IV.D) and other microbiological contaminants of concern (e.g.,
Giardia).
In order to assess the public health risk associated with
consumption of surface water or GWUDI from PWSs, EPA has evaluated
information and conducted analysis in four important areas discussed in
the following paragraphs. These areas are: (1) The health effects of
cryptosporidiosis; (2) cryptosporidiosis waterborne disease outbreak
data; (3) Cryptosporidium occurrence data from raw surface water, raw
GWUDI, finished water, and recycle stream studies; and (4) an
assessment of the current baseline surface water treatment required by
existing regulations.
B. Health Effects of Cryptosporidiosis and Sources and Transmission of
Cryptosporidium
Waterborne diseases are usually acute (i.e., sudden onset and
typically lasting a short time in healthy people), and most waterborne
pathogens cause gastrointestinal illness, with diarrhea, abdominal
discomfort, nausea, vomiting, and/or other symptoms. Some waterborne
pathogens cause or are associated with more serious disorders such as
hepatitis, gastric cancer, peptic ulcers, myocarditis, swollen lymph
glands, meningitis, encephalitis, and many other diseases.
Cryptosporidiosis is a protozoal infection that usually causes 7-14
days of diarrhea with possibly a low-grade fever, nausea, and abdominal
cramps in healthy individuals (Juranek, 1995). Unlike giardiasis for
which effective antibiotic therapy is available, an antibiotic
treatment for cryptosporidiosis does not exist (Framm and Soave, 1997).
There are several species of Cryptosporidium which have been
identified, including C. baileyi and C. meleagridis (bird host); C.
muris (mouse host); C. nasorum (fish host), C. parvum (mammalian host),
and C. serpentis (snake host). Cryptosporidium parvum was first
recognized as a human pathogen in 1976 (Juranek, 1995). Recently, both
the human and cattle types of C. parvum have been found in healthy
individuals, and these types, C. felis, and a dog type have been found
in immunocompromised individuals (Pieniazek et al., 1999). Transmission
of cryptosporidiosis often occurs through the ingestion of infective
Cryptosporidium oocysts from feces-contaminated food or water, but may
also result from direct or indirect contact with infected persons or
mammals (Casemore, 1990; Cordell and Addiss, 1994). Dupont, et. al.,
1995, found through a human feeding study that a low dose of C. parvum
is
[[Page 19052]]
sufficient to cause infection in healthy adults (Dupont et. al., 1995).
Animal agriculture as a nonpoint source of C. parvum has been
implicated as the source of contamination for the 1993 outbreak in
Milwaukee, Wisconsin, the largest outbreak of waterborne disease in the
history of the United States (Walker et al., 1998). Other sources of C.
parvum include discharges from municipal wastewater treatment
facilities and drainage from slaughterhouses. In addition, rainfall
appears to increase the concentration of Cryptosporidium in surface
water, documented in a study by Atherholt, et al. (1998).
There is evidence that an immune response to Cryptosporidium
exists, but the degree and duration of this immunity is not well
characterized (Fayer and Ungar, 1986). Recent work conducted by
Chappell, et al. (1999) indicates that individuals with evidence of
prior exposure to Cryptosporidium parvum have demonstrated immunity to
low doses of oocysts (approximately 500 oocysts). The investigators
found the 50 percent infectious dose for previously exposed individuals
(possessing a pre-existing blood serum antibody) to be 1,880 oocysts
compared to 132 oocysts for individuals without prior exposure, and
individuals with prior exposure who became infected shed fewer oocysts.
Because of this type of immune response, symptomatic infection in
communities exposed to chronic low levels of oocysts will primarily be
observed in newcomers (e.g., visitors, young children) (Frost et al.,
1997; Okhuysen et al., 1998).
Sensitive populations are more likely to become infected and ill,
and gastrointestinal illness among this population may be chronic.
These sensitive populations include children, especially the very
young; the elderly; pregnant women; and the immunocompromised (Gerba et
al., 1996; Fayer and Ungar, 1986; EPA 1998e). This sensitive segment
represents almost 20 percent of the population in the U.S. (Gerba et
al., 1996). EPA is particularly concerned about the exposure of
severely immunocompromised persons to Cryptosporidium in drinking
water, because the severity and duration of illness is often greater in
immunocompromised persons than in healthy individuals, and it may be
fatal among this population. For instance, a follow-up study of the
1993 Milwaukee, Wisconsin, waterborne disease outbreak reported that at
least 50 Cryptosporidium-associated deaths occurred among the severely
immunocompromised (Hoxie et al., 1997).
Cases of illness from cryptosporidiosis were rarely reported until
1982, when the disease became prevalent due to the AIDS epidemic
(Current, 1983). As laboratory diagnostic techniques improved during
subsequent years, outbreaks among immunocompetent persons were
recognized as well. Over the last several years there have been a
number of documented waterborne cryptosporidiosis outbreaks in the
U.S., United Kingdom, Canada and other countries (Rose, 1997, Craun et
al., 1998).
C. Waterborne Disease Outbreaks in the United States
The occurrence of outbreaks of waterborne gastrointestinal
infections, including cryptosporidiosis, may be much greater than
suggested by reported surveillance data (Craun and Calderon 1996). The
CDC-EPA, and the Council of State and Territorial Epidemiologists have
maintained a collaborative surveillance program for collection and
periodic reporting of data on waterborne disease outbreaks since 1971.
The CDC database and biennial CDC-EPA surveillance summaries include
data reported voluntarily by the States on the incidence and prevalence
of waterborne illnesses. However, the following information
demonstrates why the reported surveillance data may under-report actual
outbreaks.
The U.S. National Research Council strongly suggests that the
number of identified and reported outbreaks in the CDC database (both
for surface and ground waters) represents a small percentage of actual
waterborne disease outbreaks National Research Council, 1997; Bennett
et al., 1987). In practice, most waterborne outbreaks in community
water systems are not recognized until a sizable proportion of the
population is ill (Perz et al.)
Healthy adults with cryptosporidiosis may not suffer severe
symptoms from the disease; therefore, infected individuals may not seek
medical assistance, and their cases are subsequently not reported. Even
if infected individuals consult a physician, Cryptosporidium may not be
identified by routine diagnostic tests for gastroenteritis and,
therefore, tends to be under-reported in the general population
(Juranek 1995). Such obstacles to outbreak reporting indicate that the
incidence of disease and outbreaks of cryptosporidiosis may be much
higher than officially reported by the CDC.
The CDC database is based upon responses to a voluntary and
confidential survey that is completed by State and local public health
officials. CDC defines a waterborne disease outbreak as occurring when
at least two persons experience a similar illness after ingesting water
(Kramer et al., 1996). Cryptosporidiosis water system outbreak data
from the CDC database appear in Table II.1 and Table II.2.
Table II.1 illustrates the reported number of waterborne disease
outbreaks in U.S. community, noncommunity, and individual drinking
water systems between 1971 and 1996. According to the CDC-EPA database,
a total of 652 outbreaks and 572,829 cases of illnesses were reported
between 1971 and 1996 (see Table II-1). The total number of outbreaks
reported includes outbreaks resulting from protozoan contamination,
virus contamination, bacterial contamination, chemical contamination,
and unknown factors.
Table II.1.--Comparison of Outbreaks and Outbreak-Related Illnesses From Ground Water and Surface Water for the
Period 1971-1996 \1\
----------------------------------------------------------------------------------------------------------------
Cases of \2\ Outbreaks in
Water source Total outbreaks illnesses Outbreaks in CWSs NCWSs
--------------------------------------------\2\-----------------------------------------------------------------
Ground............................ 371 (57%)......... 90,815 (16%)...... 113 258
Surface........................... 223 (34%)......... 471,375 (82%)..... 148 43
Other............................. 58 (9%)........... 10,639 (2%)....... 30 19
[[Page 19053]]
All Systems \3\................... 652 (100%)........ 572,829 (100%).... 291 320
----------------------------------------------------------------------------------------------------------------
\1\ Craun and Calderon, 1994, CDC, 1998.
\2\ Includes outbreaks in CWSs + NCWSs + Private wells.
Epidemiological investigations of outbreaks in populations served
by filtered systems have shown that treatment deficiencies have
resulted in the plants' failure to remove contamination from the water.
Sometimes operational deficiencies have been discovered only during
post-outbreak investigations. Rose (1997) identified the following
types of environmental and operating conditions commonly present in
filtered surface water systems at the time cryptosporidiosis outbreaks
have occurred:
Improperly-installed, -operated, -maintained, or -
interpreted monitoring
Equipment (e.g., turbidimeters);
Inoperable flocculators, chemical injectors, or filters;
Inadequate personnel response to failures of primary
monitoring equipment;
Filter backwash recycle;
High concentrations of oocysts in source water with no
mitigative barrier;
Flushing of oocysts (by heavy rain or snow melt) from land
surfaces upstream of the plant intakes; and
Altered or suboptimal filtration during periods of high
turbidity, with turbidity spikes detected in finished water.
From 1984 to 1994, there have been 19 reported outbreaks of
cryptosporidiosis in the U.S. (Craun et al., 1998). As mentioned
previously, C. parvum was not identified as a human pathogen until
1976. Furthermore, cryptosporidiosis outbreaks were not reported in the
U.S. prior to 1984. Ten of these cryptosporidiosis outbreaks have been
documented in CWSs, NCWSs, and a private water system (Moore et al.,
1993; Kramer et al., 1996; Levy et al., 1998; ; Craun et al., 1998).
The remaining nine outbreaks were associated with recreational
activities (Craun et al., 1998). The cryptosporidiosis outbreaks in
U.S. drinking water systems are presented in Table II.2.
Table II.2.--Cryptosporidiosis Outbreaks in U.S. Drinking Water Systems
--------------------------------------------------------------------------------------------------------------------------------------------------------
Location and CWS, Cases of illness
Year NCWS, or private (estimated) Source water Treatment Suspected cause
--------------------------------------------------------------------------------------------------------------------------------------------------------
1984............................... Braun Station, TX, CWS 117 (2,000)........... Well................. Chlorination......... Sewage-contaminated
well.
1987............................... Carrollton, GA, CWS... (13,000).............. River................ Conventional Treatment
filtration/ deficiencies.
chlorination;
inadequate
backwashing of some
filters.
1991............................... Berks County, PA, NCWS (551)................. Well................. Chlorination......... Ground water under
the influence of
surface water.
1992............................... Medford (Jackson (3,000; combined total Spring/River......... Chlorination/package Source not
County), OR, CWS. for Jackson County filtration plant. identified.
and Talent, below).
1992............................... Talent, OR, CWS....... see Medford, OR....... Spring/River......... Chlorination/package Treatment
filtration plant. deficiencies.
1993............................... Milwaukee, WI, CWS.... (403,000)............. Lake................. Conventional High source water
filtration. contamination and
treatment
deficiencies.
1993............................... Yakima, WA, private... 7..................... Well................. N/A.................. Ground water under
the influence of
surface water.
1993............................... Cook County, MN, NCWS. 27.................... Lake................. Filtered, chlorinated Possible sewage
backflow from toilet/
septic tank.
1994............................... Clark County, NV, CWS. 103; many confirmed River/Lake........... Prechlorination, Source not
for cryptosporidiosis filtration and post- identified.
were HIV positive. filtration
chlorination.
1994............................... Walla Walla, WA, CWS.. 134................... Well................. None reported........ Sewage contamination.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Craun, et al., 1998.
[[Page 19054]]
Six of the ten cryptosporidiosis outbreaks reported in Table II.2
originated from surface water or possibly GWUDI supplied by public
drinking water systems serving fewer than 10,000 persons. The first
outbreak (117 known cases, 2,000 estimated cases of illness), in Braun
Station, Texas in 1984, was caused by sewage leaking into a ground
water well suspected to be under the influence of surface water. A
second outbreak in Pennsylvania in 1991 (551 estimated cases of
illness), occurred at a well also under the influence of surface water.
The third and fourth (multi-episodic) outbreaks took place in Jackson
County, Oregon in 1992 (3,000 estimated cases of illness) and were
linked to treatment deficiencies in the Talent, OR surface water
system. A fifth outbreak (27 cases of illness) in Minnesota, in 1993,
occurred at a resort supplied by lake water. Finally, a sixth outbreak
(134 cases of illness) in Washington in 1994, occurred due to sewage-
contaminated wells at a CWS.
Three of the ten outbreaks (Carollton, GA (1987); Talent, OR
(1992); Milwaukee, WI (1993)) were caused by water supplied by water
treatment plants where the recycle of filter backwash was implicated as
a possible cause of the outbreak. In total, the nine outbreaks which
have taken place in PWSs have caused an estimated 419,939 cases of
illness. These outbreaks illustrate that when treatment in place is not
operating optimally or when source water is highly contaminated,
Cryptosporidium may enter the finished drinking water and infect
drinking water consumers, ultimately resulting in waterborne disease
outbreaks.
D. Source Water Occurrence Studies
Cryptosporidium is common in the environment (Rose, 1988;
LeChevallier et al., 1991b). Runoff from unprotected watersheds allows
the transport of these microorganisms from sources of oocysts (e.g.,
untreated wastewater, agricultural runoff) to water bodies used as
intake sites for drinking water treatment plants. If treatment operates
inefficiently, oocysts may enter the finished water at levels of public
health concern. A particular public health challenge is that simply
increasing existing disinfection levels above those most commonly
practiced for standard disinfectants (i.e., chlorine or chloramines) in
the U.S. today does not appear to be an effective strategy for
controlling Cryptosporidium.
Cryptosporidium oocysts have been detected in wastewater, pristine
surface water, surface water receiving agricultural runoff or
contaminated by sewage, ground water under the direct influence of
surface water (GWUDI), water for recreational use, and drinking water
(Rose 1997, Soave 1995). Over 25 environmental surveys have reported
Cryptosporidium source water occurrence data from surface water or
GWUDI (presented in Tables II.3 and II.4), which typically involved the
collection of a few water samples from a number of sampling locations
having different characteristics (e.g., polluted vs. pristine; lakes or
reservoirs vs. rivers). Results are presented as oocysts per 100
liters, unless otherwise marked.
Each of the studies cited in Tables II.3 and II.4 presents
Cryptosporidium source water occurrence information, including (where
possible): (1) The number of samples collected; (2) the number of
samples positive; and (3) both the means and ranges for the
concentrations of Cryptosporidium detected (where available). However,
the immunofluorescence assay (IFA) method and other Cryptosporidium
detection methods are inaccurate and lack adequate precision. Current
methods do not indicate the species of Cryptosporidium identified or
whether the oocysts detected are viable or infectious (Frey et al.,
1997). The methods for detecting Cryptosporidium were modeled from
Giardia methods, therefore recovery of Cryptosporidium is deficient
primarily because Cryptosporidium oocysts are more difficult to capture
due to their size (Cryptosporidium oocysts are 4-
6m; Giardia cysts are 8-
12m). In addition, it is a challenge to
recover Cryptosporidium oocysts from the filters when they are
concentrated, due to the adhesive character of the organisms. Other
potential limitations to the protozoan detection methods include: (1)
Filters used to concentrate the water samples are easily clogged by
debris from the water sample; (2) interference occurs between debris or
particulates that fluoresce due to cross reactivity of antibodies,
which results in false positive identifications; (3) it is difficult to
view the structure of oocysts on the membrane filter or slide,
resulting in false negative determinations; and (4) most methods
require an advanced level of skill to be performed accurately.
Despite these limitations, the occurrence information generated
from these studies demonstrates that Cryptosporidium occurs in source
waters. The source waters for which EPA has compiled information
include rivers, reservoirs, lakes, streams, raw water intakes, springs,
wells under the influence of surface water and infiltration galleries.
The most comprehensive study in scope and national representation
(LeChevallier and Norton, 1995) will be described in further detail
following Tables II.3 and II.4.
Table II.3.--Summary of Surface Water Survey and Monitoring Data for Cryptosporidium Oocysts
--------------------------------------------------------------------------------------------------------------------------------------------------------
Samples
Number of positive for Range of oocyst conc.
Sample source samples (n) Cryptosporidium (oocysts/100L) Mean (oocysts/100L) Reference
(percent)a
--------------------------------------------------------------------------------------------------------------------------------------------------------
Rivers............................... 25 100 200-11,200.................. 2510........................ Ongerth and Stibbs
1987.
River................................ 6 100 200-580,000................. 192,000(a).................. Madore et al. 1987.
Reservoirs/rivers (polluted)......... 6 100 19-300...................... 99(a)....................... Rose 1988.
Reservoir (pristine)................. 6 83 1-13........................ 2(a)........................ Rose 1988.
Impacted river....................... 11 100 200-11,200b................. 2,500(g).................... Rose et al. 1988ab.
Lake................................. 20 71 0-2200...................... 58(g)....................... Rose et al. 1988bb.
Stream............................... 19 74 0-24,000.................... 109(g)...................... Rose et al. 1988bb
Raw water............................ 85 87 7-48,400.................... 270(g) detectable........... LeChevallier et al.
1991c.
River (pristine)..................... 59 32 NR.......................... 29(g)....................... Rose et al. 1991.
River (polluted)..................... 38 74 0.1-4,400b.................. 66(g)....................... Rose et al. 1991.
Lake/reservoir (pristine)............ 34 53 NR.......................... 9.3(g)...................... Rose et al. 1991.
Lake/reservoir (polluted)............ 24 58 0.1-380b.................... 103(g)...................... Rose et al. 1991.
[[Page 19055]]
River (all samples).................. 36 97 15-45 (pristine) 1000-6,350 20 (pristine) 1,830 Hansen and Ongerth
(agricultural). (agricultural). 1991.
Protected drinking water supply 6 81 15-42....................... 24(g)....................... Hansen and Ongerth
(subset of all). 1991.
Pristine river, forestry area (subset 6 100 46-697...................... 162(g)...................... Hansen and Ongerth
of all). 1991.
River below rural community in 6 100 54-360...................... 107(g)...................... Hansen and Ongerth
forested area (subset of all). 1991.
River below dairy farming 6 100 330-6,350................... 1,072(g).................... Hansen and Ongerth
agricultural activities (subset of 1991.
all).
Reservoirs........................... 56 45 NR.......................... NR.......................... Consonery et al. 1992.
Streams.............................. 33 48 NR.......................... NR.......................... Consonery et al. 1992.
Rivers............................... 37 51 NR.......................... NR.......................... Consonery et al. 1992.
Site 1--River source (high turbidity) 10 100 82-7,190.................... 480......................... LeChevallier and Norton
1992.
Site 2--River source (moderate 10 70 42-510...................... 250......................... LeChevallier and Norton
turbidity). 1992.
Site 3--Reservoir source (low 10 70 77-870...................... 250......................... LeChevallier and Norton
turbidity). 1992.
Lakes................................ 179 6 0-2,240..................... 3.3 (median)................ Archer et al. 1995.
Streams.............................. 210 6 0-2,000..................... 7 (median).................. Archer et al. 1995.
Finished water....................... 262 13 0.29-57..................... 33 (detectable)............. LeChevallier and Norton
1995.
River/lake........................... 262 52 6.5-6,510................... 240 (detectable)............ LeChevallier and Norton
1995.
River/lake........................... 147 20 30-980...................... 200......................... LeChevallier et al.
1995.
River 1.............................. 15 73 0-2,230..................... 188 (a) all samples 43 (g) States et al. 1995.
detected.
River 2.............................. 15 80 0-1,470..................... 147 (a) all samples 61 (g) States et al. 1995.
detected.
Dairy farm stream.................... 13 77 0-1,110..................... 126 (a) all samples 55 (g) States et al. 1995.
detected.
Reservoir inlets..................... 60 5 0.7-24...................... 1.9(g) 1.6 (median)......... LeChevallier et al.
1997b.
Reservoir outlets.................... 60 12 1.2-107..................... 6.1(g) 60 (median).......... LeChevallier et al.
1997b.
River (polluted)..................... 72 40 20-280...................... 24(g)....................... LeChevallier et al.
1997a.
Source water......................... NR 24 1-5,390c.................... 740(a)c 71(g)c.............. Swertfeger et al. 1997.
First flush (storm event)............ 20 35 0-41,700.................... NR.......................... Stewart et al. 1997.
Grab (non-storm event)............... 21 19 0-650....................... NR.......................... Stewart et al. 1997.
River 1.............................. 24 63 0-1,470..................... 58(g)....................... States et al. 1997.
Stream by dairy farm................. 22 82 0-2,300..................... 42(g)....................... States et al. 1997.
River 2 (at plant intake)............ 24 63 0-2,200..................... 31(g)....................... States et al. 1997.
Reservoirs (unfiltered system)....... NR 37-52d 15-43 (maxima)d............. 0.8-1.4d.................... Okun et al. 1997.
Raw water intakes.................... 148 25 0.04-18..................... 0.3......................... Consonery et al. 1997.
Raw water intakes (rural)............ NR NR 40-400...................... NR.......................... Swiger et al. 1999.
Raw Water............................ 100 plants 77 0.5-117..................... 3(g)........................ McTigue, et al. 1998.
DE River, Winter..................... 18 NR NR.......................... 70 per 500L(g).............. Atherholt, et al. 1998.
DE River, Spring..................... 18 NR NR.......................... 100 per 500L(g)............. Atherholt, et al. 1998.
DE River, Summer..................... 18 NR NR.......................... 30 per 500L(g).............. Atherholt, et al. 1998.
DE River, Fall....................... 18 NR NR.......................... 20 per 500L(g).............. Atherholt, et al. 1998.
--------------------------------------------------------------------------------------------------------------------------------------------------------
a Rounded to nearest percent.
b As cited in Lisle and Rose 1995.
c Based on presumptive oocyst count
d Combined monitoring results for multiple sites in large urban water supply.
e As cited in States et al. 1997.
(a) = arithmetic average.
(g) = geometric average.
NR = not reported, NA = not applicable.
[[Page 19056]]
Table II.4.--Summary of U.S. GWUDI Monitoring Data for Cryptosporidium Oocysts
--------------------------------------------------------------------------------------------------------------------------------------------------------
Samples positive for
Sample source Number of samples (n) Cryptosporidium Range of positive Mean (oocysts/ 100L) a Reference
oocysts (percent) values (oocysts/100L)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Well.............................. 17 (6 wells).......... (1 sample)............ .085L NA Archer et al. 1995.
Ground water sources (all 199 sites\b\.......... 11\b\................. 0.002-0.45d NR Hancock et al. 1998.
categories).
Vertical wells (subcategory of 149 sites\b\.......... 5\b\.................. NR NR Hancock et al. 1998.
above ground water sources).
Springs (subcategory of above 35 sites\b\........... 20\b\................. NR NR Hancock et al. 1998.
ground water sources).
Infiltration galleries 4 sites\b\............ 50\b\................. NR NR Hancock et al. 1998.
(subcategory of above ground
water sources).
Horizontal wells (subcategory of 11 sites\b\........... 45\b\................ NR NR Hancock et al. 1998.
above ground water sources).
Ground water...................... 17.................... 41.2.................. NR NR Rosen et al., 1996.
Ground water...................... 18.................... 5.6................... .13 .13 Rose et al. 1991.
Springs........................... 7 (4 springs)......... 57\b\................ 0.25-10 4 Rose et al. 1991.
Wells............................. 5 sites............... 100................... 0.26-3 0.9 SAIC, 1997 c
Vertical well Lemont Well #4 6..................... 66.7.................. NR NR Lee, 1993.
(Center Co., PA, Aug. 1992).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Geometric mean reported unless otherwise indicated.
\b\ Data are presented as the percentage of positive sites.
\c\ Data included are confirmed positive samples not reported in Hancock, 1998.
NA = not applicable.
NR = not reported.
The LeChevallier and Norton (1995) study collected the most samples
and repeat samples from the largest number of surface water plants
nationally. LeChevallier and Norton conducted the study to determine
the level of Cryptosporidium in surface water supplies and plant
effluent water. In total, surface water sources for 72 treatment plants
in 15 States and 2 Canadian provinces were sampled. Sixty-seven surface
water locations were examined. The generated data set covered a two-
year monitoring period (March, 1991 to January, 1993) which was
combined with a previous set of data (October, 1988 to June, 1990)
collected from most of the same set of systems to create a database
containing five samples (IFA) per site or more for 94 percent of the 67
systems sampled. Cryptosporidium oocysts were detected in 135 (51.5
percent) of the 262 raw water samples collected between March 1991 and
January 1993, while 87 percent of the 85 samples were positive during
the survey period from October, 1988 to June, 1990. The geometric mean
of detectable Cryptosporidium was 240 oocysts/100L, with a range from
6.5 to 6510 oocysts/100L. When the 1991-1993 results (n=262) were
combined with the previous results (n=85), Cryptosporidium was detected
in 60.2 percent of the samples. The authors hypothesize the origin of
the decrease in detections in the second round of sampling to be most
probably linked to fluctuating or declining source water concentrations
of Cryptosporidium oocysts from the first reporting period to the
second.
LeChevallier and Norton (1995) also detected Cryptosporidium
oocysts in 35 of 262 plant effluent samples (13.4 percent) analyzed
between 1991 and 1993. When detected, the oocyst levels averaged 3.3
oocysts/100 L (range = 0.29 to 57 oocysts/100 L). A summary of
occurrence data for all samples in filtered effluents for the years
1988 to 1993 showed that 32 of the water treatment plants (45 percent)
were consistently negative for Cryptosporidium; 24 plants (34 percent)
were positive once; and 15 plants (21 percent) were positive for
Cryptosporidium two or more times between 1988 to 1993. Forty-four of
the plants (62 percent) were positive for Giardia, Cryptosporidium, or
both at one time or another (LeChevallier and Norton 1995).
The oocyst recoveries and densities reported by LeChevallier and
Norton (1995) are comparable to the results of another survey of
treated, untreated, protected (pristine) and feces-contaminated
(polluted) water supplies (Rose et al. 1991). Six of thirty-six samples
(17 percent) taken from potable drinking water were positive for
Cryptosporidium, and concentrations in these waters ranged from .5 to
1.7 oocysts/100L. In addition, a total of 188 surface water samples
were analyzed from rivers, lakes, or springs in 17 States. The majority
of surface water samples were obtained from Arizona, California, and
Utah (126 samples in all), with others from eastern States (28
samples), northwestern States (14 samples), southern States (13
samples), midwestern States (6 samples), and Hawaii (1 sample).
Arithmetic average oocyst concentrations ranged from less than 1 to
4,400 oocysts/100 L, depending on the type of water analyzed.
Cryptosporidium oocysts were found in 55 percent of the surface water
samples at an average concentration of 43 oocysts/100 L.
The LeChevallier and Norton (1995) study collected the most samples
and repeat samples from the most surface water plants on a national
level. Therefore, the data from this study were analyzed by EPA (EPA,
1998n) to generate a distribution of source water occurrence, presented
in Table II.5.
Table II.5.--Baseline Expected National Source Water Cryptosporidium
Distributions
------------------------------------------------------------------------
Source water
Percentile concentration
(oocysts/100L)
------------------------------------------------------------------------
25.................................................... 103
50.................................................... 231
75.................................................... 516
90.................................................... 1064
95.................................................... 1641
Mean.............................................. 470
Standard Deviation................................ 841
------------------------------------------------------------------------
Although limited by the small number of samples per site (one to
sixteen samples; most sites were sampled five times), the mean
concentration at the 69
[[Page 19057]]
sites from the eastern and central U.S. seems to be represented by a
lognormal distribution.
In addition to the source water data, several studies have detected
Cryptosporidium oocysts in finished water. The results of these studies
have been compiled in Table II.6.
Table II.6.--Summary of U.S. Finished Water Monitoring Data for Cryptosporidium Oocysts
--------------------------------------------------------------------------------------------------------------------------------------------------------
Samples
Number of positive for Range of oocyst conc.
Sample source samples (n) Cryptosporidium (oocysts/100L) Mean (oocysts/100L) Reference
(percent)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Filtered water........................ 82 27 0.1-48.................... 1.5...................... LeChevallier et al.
1991a.
Finished water (unfiltered)........... 6 33 0.1-1.7................... 0.2...................... LeChevallier et al.
1992.
Finished water........................ 262 13 0.29-57................... 33 (detectable).......... LeChevallier and Norton
1995.
Finished water (clearwell)............ 14 14 NR........................ NR....................... Consonery et al. 1992.
Finished water (filter effluents)..... 118 26 NR........................ NR....................... Consonery et al. 1992.
Site 1--Filter effluent............... 10 70 1-4....................... NR....................... LeChevallier and Norton
1992.
Site 2--Filter effluent............... 10 10 0.5....................... NA....................... LeChevallier and Norton
1992.
Site 3--Filter effluent............... 10 10 2......................... NA....................... LeChevallier and Norton
1992.
Finished water........................ 1,237 7 NR........................ NR....................... Rosen et al. 1996.
Filtered (non-storm event)............ 87 10 0-420..................... NR....................... Stewart et al. 1997a.
Finished water........................ 24 **8 0-0.6..................... 0.5 (g).................. States et al. 1997.
***13
Finished water........................ 155 2.5 0.02-0.8.................. 0.2...................... Consonery et al. 1997.
Finished water........................ 100 15 0.04-0.08................. 0.08 (g)................. McTigue, et al. 1998.
--------------------------------------------------------------------------------------------------------------------------------------------------------
*Plants
**Confirmed
***Presumed
These studies show that despite some treatment in place,
Cryptosporidium may still pass through the treatment plant and into
finished water.
In general, oocysts are detected more frequently and in higher
concentrations in rivers and streams than in lakes and reservoirs
(LeChevallier et al., 1991b; Rose et al., 1988a,b). Madore et al.
(1987) found high concentrations of oocysts in a river affected by
agricultural runoff (5800 oocysts/L). Such concentrations are
especially significant if the contaminant removal process (e.g.,
sedimentation, filtration) of the treatment plant is not operating
effectively. Oocysts may pass through to the finished water, as
LeChevallier and Norton (1995) and several other researchers also
found, and infect drinking water consumers.
E. Filter Backwash and Other Process Streams: Occurrence and Impact
Studies
Pathogenic microorganisms are removed during the sedimentation and/
or filtration processes in a water treatment plant. Recycle streams
generated during treatment, such as spent filter backwash water,
sedimentation basin sludge, or thickener supernatant are often returned
to the treatment train. These recycle streams, therefore, may contain
high concentrations of pathogens, including chlorine-resistant
Cryptosporidium oocysts. Recycle can degrade the treatment process,
especially when entering the treatment train after the rapid mix stage,
by causing a chemical imbalance, hydraulic surge and potentially
overwhelming the plant's filtration capacity with a large concentration
of pathogens. High oocyst concentrations found in recycle waters can
increase the risk of pathogens passing through the treatment plant into
finished water.
AWWA has compiled issue papers on each of the following recycle
streams: Spent filter backwash water, sedimentation basin solids,
combined thickener supernatant, ion-exchange regenerate, membrane
concentrate, lagoon decant, mechanical dewatering device concentrate,
monofill leachate, sludge drying bed leachate, and small-volume streams
(e.g., floor, roof, lab drains) (Environmental Engineering &
Technology, 1999). In addition, EPA compiled existing occurrence data
on Cryptosporidium in recycle streams. Through these efforts,
Cryptosporidium occurrence data has been found for three types of
recycle streams: Spent filter backwash water, sedimentation basin
solids, and thickener supernatant.
Nine studies have reported the occurrence of Cryptosporidium for
these process streams. Each study's scope and results are presented in
Table II.7, and brief narratives on each major study follow the table.
Note that the results of the studies, if not presented in the published
report as oocysts/100L, have been converted into oocysts/100L.
Table II.7.--Cryptosporidium Occurrence in Filter Backwash and Other Recycle Streams
--------------------------------------------------------------------------------------------------------------------------------------------------------
Number of treatment
Name/location of study Number of samples (n) Type of sample Cyst/oocyst concentration plants sampled Reference
--------------------------------------------------------------------------------------------------------------------------------------------------------
Drinking water treatment 2.................... backflush waters from sample 1: 26,000 oocysts/ 2................... Rose et al. 1986.
facilities. rapid sand filters. gal (calc. as 686,900
oocysts/100L).
sample 2: 92,000 oocysts/
gal (calc as 2,430,600
oocysts/100L)
[[Page 19058]]
Thames, U.K.,..................... not reported......... backwash water from Over 1,000,000 oocysts/ 1................... Colbourne 1989.
rapid sand filter. 100L in backwash water on
2/19/89.
100,000 oocysts/100L in
supernatant from
settlement tanks during
the next few days
Potable water supplies in 17 not reported......... filter backwash from 217 oocysts/ 100 L not reported........ Rose et al. 1991.
States. rapid sand filters (geometric mean).
(10 to 40 L sample
vol.).
Name/location not reported........ not reported......... raw water............ 7 to 108 oocysts/100L..... not reported........ LeChevallier et al.
initial backwash detected at levels 57 to not reported........ 1991c.
water. 61 times higher than in
the raw water.
Bangor Water Treatment Plant (PA). Round 1: 1 (8-hour raw water............ 902 oocysts/100L. 141 oocysts/100L. 1 Cornwell and Lee
composite). filter backwash...... 1993.
supernatant recycle 6
oocysts/100L.
Round 2: 1 (8-hour composite)..... raw water............ 140 oocysts/100L..... 850 oocysts/100L. 750 oocysts/100L. 1 Cornwell and Lee
filter backwash...... 1993.
supernatant recycle..
Moshannon Valley Water Treatment Round 1: 1 (8-hour raw water............ 16,613 oocysts/100L. 82 oocysts/100L. 2,642 oocysts/100L.
Plant. composite). spent backwash....... 1 Cornwell and Lee
supernatant recycle.. 1993.
sludge 13 oocysts/
100L.
Round 2: 1 (8-hour raw water............ 20 oocysts/100L........... 420 oocysts/100L. 1 Cornwell and Lee
composite). supernatant recycle.. 1993.
Plant ``C''....................... 11 samples using 39 samples using backwash water from rapid continuous flow: cartridge filters:
continuous flow cartridge filters. sand filters; samples range 1 to 69 ranges 0.8 to 252/
centrifugation;. collected from oocysts/100 L; 8 of 100 L; 33 of 39
sedimentation basins 11 samples positive. samples positive 1
during sedimentation Karanis et al.
phase of backwash water 1996.
at depths of 1, 2, 3, and
3.3 m.
Pittsburgh Drinking Water 24 (two years of filter backwash...... 328 oocysts/ 100 L non-detect-13,158 States et al. 1997.
Treatment Plant. monthly samples). (geometric mean); (38 oocysts/100L. 1
percent occurrence rate).
``Plant Number 3''................ not reported......... raw water............ 140 oocysts/100L.......... 850 oocysts/100L. not reported
spent backwash....... Cornwell 1997.
``Plant C'' (see Karanis, et al., 12................... raw water............ avg. 23.2 oocysts/100L avg. 22.1 oocysts/ 1 Karanis et al
1996). 50................... backwash water from (max. 109 oocysts/100L) 100L (max. 257 1998.
rapid sand filters. in 8 of 12 samples. oocysts/100L) in 41
of 50 samples
``Plant A''....................... 1.................... rapid sand filter 150 oocysts/100L..........
(sample taken 10
min. after start of
backwashing).
--------------------------------------------------------------------------------------------------------------------------------------------------------
The occurrence data available and reported are primarily for raw
and recycle stream water. If filter backwash enters the treatment train
as a slug load and disrupts the treatment process, it is possible its
effects would not be readily seen in the finished water until several
minutes or hours after returning the filter to service. In addition,
the poor recovery efficiencies of the IFA Cryptosporidium detection
method complicate measurements in dilute finished effluent waters.
As shown in Table II.7, the concentrations of oocysts in backwash
water and other recycle streams are greater than the concentrations
generally found in raw water. For example, four studies (Cornwell and
Lee, 1993; States et al., 1997; Rose et al., 1986; and Colbourne, 1989)
have reported Cryptosporidium oocyst concentrations in filter backwash
water exceeding 10,000 oocysts/100L. Such concentrations illustrate
that the treatment plant has been removing oocysts from the influent
water during the sedimentation and/or filtration processes. As
expected, the oocysts have concentrated on the filters and/or in the
sedimentation basin sludge. Therefore, the recycling of such process
streams (e.g., filter backwash, thickener supernatant, sedimentation
basin
[[Page 19059]]
sludge) re-introduces high concentrations of oocysts to the drinking
water treatment train.
Recycle can potentially return a significant number of oocysts to
the treatment plant in a short amount of time, particularly if the
recycle is returned to the treatment process without prior treatment,
equalization, or some other type of hydraulic detention. In addition,
Di Giovanni, et al. (1999) presented data indicating that viable
oocysts have been detected in filter backwash samples using a cell
culture/polymerase chain reaction (PCR) method. Cell culture is a test
of the viability/infectivity of the oocysts, while PCR identified the
cells infected by C. parvum. Although recovery by IFA was poor (6 to 8
percent for backwash samples), 9 filter backwash recycle samples were
found to contain viable and infectious oocysts, and the infectious
agent was determined to be more than 98 percent similar in structure to
C. parvum. Should filter backwash recycle disrupt normal treatment
operations or should treatment not function efficiently due to other
deficiencies, high concentrations of potentially viable, infectious
oocysts may pass through the plant into finished drinking water. The
recycle stream occurrence studies presented in Table II.7 are described
in further detail in the following sections.
Thames, U.K. Water Utilities Experience with Cryptosporidium, Colbourne
(1989)
In response to a cryptosporidiosis outbreak reported in February of
1989, Thames Water undertook an investigation of pathogen
concentrations within the Farmoor conventional treatment plant's
treatment train, finished and raw waters. The investigation occurred
over a two month period, from February to April 1989 and included
sampling of settled filter backwash, the supernatant from spent filter
backwash, raw water, and water sampled at the end of various Thames
distribution points.
On February 19, 1989 at the start of the outbreak investigation, a
concentration of approximately 1,000,000 oocysts/100L was detected in
the filter backwash water. During the first few days of the following
investigation, the supernatant of the settled backwash water contained
approximately 100,000 oocysts/100L. At the peak of the outbreak, thirty
percent of Thames' distribution system samples were positive for
oocysts, and ranged in concentration from 0.2 to 7700 oocysts/100L. Raw
reservoir water contained oocyst concentrations ranging from .2 to 1400
oocysts/100L. After washing the filters twice in 24 hours, no oocysts
were found in the settled backwash waters. Thames, U.K. Water Utilities
determined that a storm causing intense precipitation and runoff
resulted in elevated levels of oocysts in the source water which led to
the high concentrations of oocysts entering the plant and subsequently
deposited on the filters and recycled as filter backwash.
Survey of Potable Water Supplies for Cryptosporidium and Giardia, Rose,
et al., 1991
In this survey, Rose, et al., collected 257 samples from 17 States
from 1985 to 1988. The samples were collected on cartridge filters and
analyzed using variations of the IFA method. The reported percent
recovery for the method was 29 to 58 percent. Filter backwash samples
were a subset of the 257, 10 to 40 L samples were collected from rapid
sand filters.
Rose, et al. reported the geometric mean of the backwash samples at
217 Cryptosporidium oocysts/100L. This was the highest reported average
Cryptosporidium concentration of any of the water types tested, which
included polluted and pristine surface and ground water sources,
drinking water sources in addition to filter backwash recycle water.
Giardia and Cryptosporidium in Water Supplies, LeChevallier, et al.
(1991c)
LeChevallier et al. conducted a study to determine ``whether
compliance with the SWTR would ensure control of Giardia in potable
water supplies.'' Raw water and plant effluent samples were collected
from 66 surface water treatment plants in 14 States and one Canadian
province, although only selected sites were tested for Cryptosporidium
oocysts in filter backwash and settled backwash water.
In the analysis of pathogen concentrations in the raw water and
filter backwash water of the water treatment process, LeChevallier et
al. (1991c) found very high oocyst levels in backwash water of
utilities that had low raw water parasite concentrations. The pathogens
were detected using a combined IFA method that the authors developed.
Cryptosporidium levels in the initial backwash water were 57 to 61
times higher than in the raw water supplies. Raw water samples were
found to contain from 7 to 108 oocysts/100L. LeChevallier et al.
(1991c) also noted that when Cryptosporidium were detected in plant
effluent samples (12 of 13 times), the organisms were also observed in
the backwash samples. The study concluded that the consistency of these
results shows that accumulation of parasites in the treatment filters
(and subsequent release in the filter backwash recycle water) could be
related to subsequent passage through treatment barriers.
Recycle Stream Effects on Water Treatment, Cornwell and Lee (1993,
1994)
The results described in Cornwell and Lee's 1993 American Water
Works Association Research Foundation Report and 1994 Journal of the
American Water Works Association article on the Bangor and Moshannon
Valley, PA water treatment plants are consistent with the results of
States et al. (1997). In total, Cornwell and Lee investigated eight
water treatment plants, examining treatment efficiencies including
several recycle streams and their impacts, and reporting a range of
pathogen and other water quality data. All of the pathogen testing was
conducted using the EPA IFA method refined by LeChevallier, et al.
(1991c).
Cornwell and Lee (1993) conducted two rounds of sampling at both
the Bangor and Moshannon plants, sampling the different recycle and
treatment streams as eight-hour composites. They detected
Cryptosporidium concentrations of over 16,500 Cryptosporidium oocysts/
100L in the backwash water at an adsorption clarifier plant (Moshannon
Valley) and over 850 Cryptosporidium oocysts/100L in backwash water
from a direct filtration plant (Bangor). The parasite levels in the
backwash samples were significantly higher than concentrations found in
the raw source water, which contained Cryptosporidium oocyst
concentrations of 13-20 oocysts/100L at the Moshannon Valley plant and
6-140 oocysts/100L at the Bangor plant.
In addition, Cornwell and Lee determined oocyst concentrations for
two other recycle streams, combined thickener supernatant and
sedimentation basin solids. The supernatant pathogen concentrations
were reported at 141 Cryptosporidium oocysts/100L at the Bangor plant,
and levels were reported at 82 to 420 oocysts/100L for the Moshannon
plant in Rounds 1 and 2 of sampling, respectively. The sedimentation
basin sludge was reported at 2,642 Cryptosporidium oocysts/100L in the
clarifier sludge from the Moshannon Valley plant.
[[Page 19060]]
Giardia and Cryptosporidium in Backwash Water from Rapid Sand Filters
Used for Drinking Water, Karanis et al. (1996) and Distribution and
Removal of Giardia and Cryptosporidium in Water Supplies in Germany
Karanis, et al. (1998)
Karanis et al. (1996 and 1998) conducted a four-year research study
(samples collected from July, 1993-December, 1995) on the efficiency of
Cryptosporidium removal by six different surface water treatment plants
from Germany, all of which treat by conventional filtration. The method
used was an IFA method dubbed the ``EPA method'', developed by
Jakubowski and Ericksen, 1979.
Karanis et al. (1996) detected Cryptosporidium in 82 percent of the
samples of backwash water from rapid sand filters of a water treatment
plant (``Plant C'') supplied by small rivers. Eight out of 12 raw water
samples tested were positive for Cryptosporidium (range of 0.8 to 109
oocysts/100L). Backwash water samples collected by continuous flow
centrifugation were positive for Cryptosporidium in 8 of 11 samples
(range of 1 to 69/100L). Of 39 samples collected using cartridge
filters, 33 were positive for Cryptosporidium (range of 0.8 to 252/
100L). The authors called attention to the high detection rate of
Cryptosporidium in the backwash waters (82 percent) of Plant C and to
the fact that the supernatant following sedimentation was not free from
cysts and oocysts (Karanis et al. 1996).
In the 1998 publication, Karanis et al. compiled the data from the
1996 study with more backwash occurrence data collected from another
treatment plant (``Plant A''). The filter backwash of Plant A was
sampled 10 minutes after the start of backwashing, and the backwash
water was found to contain 150 Cryptosporidium oocysts/100L.
Protozoa in River Water: Sources, Occurrence, and Treatment, States, et
al. (1997)
Over a two year period (July, 1994-June, 1996), States et al.
sampled monthly for Cryptosporidium in the raw, settled, filtered and
filter backwash water at the Pittsburgh Drinking Water Treatment Plant,
in order to gauge the efficiency of pathogen removal at the plant.
States et al. identified several sources contributing oocysts to the
influent water, including sewage plant effluent, combined sewer
overflows, dairy farm streams, and recycling of backwash water. All
pathogen sampling was conducted with the IFA method.
Cryptosporidium occurred in the raw Allegheny river water supplying
the plant with a geometric mean of 31 oocysts/100L in 63 percent of
samples collected, and ranged from non-detect to 2,333 oocysts/100L
(see Table II.3 for source water information). Of the filter backwash
samples, a geometric mean of 328 oocysts/100L was found at an
occurrence rate of 38 percent of samples, with a range from non-detect
to 13,158 oocysts/100L. The fact that the mean concentration of
Cryptosporidium oocysts in backwash water can be substantially higher
than the oocyst concentration in untreated river water suggests that
recycling untreated filter backwash water can be a significant source
of this parasite to water within the treatment process.
F. Summary and Conclusions
Cryptosporidiosis is a disease without a therapeutic cure, and its
causative agent, Cryptosporidium, is resistant to chlorine
disinfection. Cryptosporidium has been known to cause severe illness,
especially in immunocompromised individuals, and can be fatal. Several
waterborne cryptosporidiosis outbreaks have been reported, and it is
likely that others have occurred but have gone unreported.
Cryptosporidium has been detected in a wide range of source waters,
documented in over 30 studies from the literature, and it has been
found at levels of concern in filter backwash water and other recycle
streams.
One of the key regulations EPA has developed and implemented to
counter pathogens in drinking water is the SWTR (54 FR 27486, June 19,
1989). The SWTR requires that surface water systems have sufficient
treatment to reduce the source water concentration of Giardia and
viruses by at least 99.9 percent (3 log) and 99.99 percent (4 log),
respectively. A shortcoming of the SWTR, however, is that the rule does
not specifically control for Cryptosporidium. The first report of a
recognized waterborne outbreak caused by Cryptosporidium was published
during the development of the SWTR (D'Antonio et al. 1985).
In 1998, the Agency finalized the IESWTR that enhances the
microbial pathogen protection provided by the SWTR for systems serving
10,000 or more persons. The IESWTR includes an MCLG of zero for
Cryptosporidium and requires a minimum 2-log (99 percent) removal of
Cryptosporidium, linked to enhanced combined filter effluent and
individual filter turbidity control provisions.
Several provisions of today's proposed rule, the LT1FBR, are
designed to address the concerns covered by the IESWTR, improving
control of Cryptosporidium and other microbial contaminants, for the
portion of the public served by small PWSs (i.e., serving less than
10,000 persons). The LT1FBR also addresses the concern that for all
PWSs that practice recycling, Cryptosporidium (and other emerging
pathogens resistant to standard disinfection practice) are reintroduced
to the treatment process of PWSs by the recycle of spent filter
backwash water, solids treatment residuals, and other process streams.
Insufficient treatment practices have been cited as the cause of
several reported waterborne disease outbreaks (Rose, 1997). Rose (1997)
also found that a reduction in turbidity is indicative of a more
efficient filtration process. Therefore, the turbidity and filter
monitoring requirements of today's proposed LT1FBR will ensure that the
removal process necessary to protect the public from cryptosporidiosis
is operating properly, and the recycle stream provisions will ensure
that the treatment process is not disrupted or operating inefficiently.
The LT1FBR requirements that address the potential for Cryptosporidium
to enter the finished drinking water supply will be described in more
detail in the following sections.
III. Baseline Information-Systems Potentially Affected By Today's
Proposed Rule
EPA utilized the 1997 state-verified version of the Safe Drinking
Water Information System (SDWIS) to develop the total universe of
systems which utilize surface water or groundwater under the direct
influence (GWUDI) as sources. This universe consists of 11,593 systems
serving fewer than 10,000 persons, and 2,096 systems serving 10,000 or
more persons. Given this initial baseline, the Agency developed
estimates of the number of systems which would be affected by
components of today's proposed rule by utilizing three primary sources:
Safe Drinking Water Information Systems; Community Water Supply Survey;
and Water: Stats. A brief overview of each of the data sources is
described in the following paragraphs.
Safe Drinking Water Information System (SDWIS)
SDWIS contains information about PWSs including violations of EPA's
regulations for safe drinking water. Pertinent information in this
database includes system name and ID, population served, geographic
location,
[[Page 19061]]
type of source water, and type of treatment (if provided).
Community Water System Survey (CWSS)
EPA conducted the 1995 CWSS to obtain data to support its
development and evaluation of drinking water regulations. The survey
consisted of a stratified random sample of 3,700 water systems
nationwide (surface water and groundwater). The survey asked 24
operational and 13 financial questions.
Water:/Stats (WaterStats)
WaterStats is an in-depth database of water utility information
compiled by the American Water Works Association. The database consists
of 898 utilities of all sizes and provides a variety of data including
treatment information.
Information regarding estimates of the number of systems which may
potentially be affected by specific components of today's proposed rule
can be found in the discussion of each proposed rule component in
Section IV.
IV. Discussion of Proposed LT1FBR Requirements
A. Enhanced Filtration Requirements
As discussed earlier in this preamble, one of the key objectives of
today's proposed rule is ensuring that an adequate level of public
health protection is maintained in order to minimize the risk
associated with Cryptosporidium. While the current SWTR provides
protection from viruses and Giardia, it does not specifically address
Cryptosporidium, which has been linked to outbreaks resulting in over
420,000 cases of gastrointestinal illness in the 1990s (403,000
associated with the Milwaukee outbreak). Because of Cryptosporidium's
resistance to disinfection practices currently in place at small
systems throughout the country, the Agency believes enhanced filtration
requirements are necessary to improve control of this microbial
pathogen.
In the IESWTR, the Agency utilized an approach consisting of three
major components to address Cryptosporidium at plants serving
populations of 10,000 or more. The first component required systems to
achieve a 2 log removal of Cryptosporidium. The second component
consisted of strengthened turbidity requirements for combined filter
effluent. The third component required individual filter turbidity
monitoring.
In today's proposed rule addressing systems serving fewer than
10,000 persons, the Agency is utilizing the same framework. Where
appropriate, EPA has evaluated additional options in an effort to
alleviate burden on small systems while still maintaining a comparable
level of public health protection.
The following sections describe the overview and purpose of each of
the rule components, relevant data utilized during development, the
requirements of today's proposed rule (including consideration of
additional options where appropriate), and a request for comment
regarding each component.
1. Two Log Cryptosporidium Removal Requirement
a. Two Log Removal
i. Overview and Purpose
The 1998 IESWTR (63 FR 69477, December 16, 1998) establishes an
MCLG of zero for Cryptosporidium in order to adequately protect public
health. In conjunction with the MCLG, the IESWTR also established a
treatment technique requiring 2 log Cryptosporidium removal for all
surface water and GWUDI systems which filter and serve populations of
10,000 or more people, because it was not economically and
technologically feasible to accurately ascertain the level of
Cryptosporidium using current analytical methods. The Agency believes
it is appropriate and necessary to extend this treatment technique of 2
log Cryptosporidium removal requirement to systems serving fewer than
10,000 people.
ii. Data
As detailed later in this section, EPA believes that the data and
principles supporting requirements established for systems serving
populations of 10,000 or more are also applicable to systems serving
populations fewer than 10,000. The following section provides
information and data regarding: (1) the estimated number of small
systems subject to the proposed 2 log Cryptosporidium removal
requirement; and (2) Cryptosporidium removal using various filtration
technologies.
Estimate of the Number of Systems Subject to 2 log Cryptosporidium
Removal Requirement
Using the baseline described in Section III of today's proposed
rule, the Agency applied percentages of surface water and GWUDI systems
which filter (taken from the 1995 CWSS) in order to develop an estimate
of the number of systems which filter and serve fewer than 10,000
persons. This resulted in an estimated 9,133 surface water and GWUDI
systems that filter which may be subject to the proposed removal
requirement. Table IV.1 provides this estimate broken down by system
size and type.
Table IV.1.--Estimate of Systems Subject to 2 Log Cryptosporidium Removal Requirement a
----------------------------------------------------------------------------------------------------------------
Population served
System type -----------------------------------------------------------------------------
100 101-500 501-1K b 1K-3.3K b 3.3K-10K b Total #Sys.
----------------------------------------------------------------------------------------------------------------
Community......................... 888 1453 950 2022 1591 6903
Non Community..................... 1099 374 78 64 35 1649
NTNC.............................. 214 204 82 64 17 581
-----------------------------------------------------------------------------
Total....................... 2201 2031 1110 2150 1643 b 9134b
----------------------------------------------------------------------------------------------------------------
a Numbers may not add due to rounding
b K = thousands
Cryptosporidium Removal Using Conventional and Direct Filtration
During development of the LT1FBR, the Agency reviewed the results
of several studies that demonstrated the ability of conventional and
direct filtration systems to achieve 2 log removal of Cryptosporidium
at well operated plants achieving low turbidity levels. Table IV.2
provides key information from these studies. A brief description of
each study follows the table.
[[Page 19062]]
Table IV.2.--Conventional and Direct Filtration Removal Studies
----------------------------------------------------------------------------------------------------------------
Type of treatment Log removal Experimental design Researcher
----------------------------------------------------------------------------------------------------------------
Conventional..................... Cryptosporidium 4.2-5.2.. Pilot plants............ Patania et al. 1995
Giardia 4.1-5.1.......... Pilot plants............ Patania et al. 1995
Cryptosporidium 1.9-4.0.. Pilot-scale plants...... Nieminski/Ongerth 1995
Giardia 2.2-3.9.......... Pilot-scale plants...... Nieminski/Ongerth 1995
Cryptosporidium 1.9-2.8.. Full-scale plants....... Nieminski/Ongerth 1995
Giardia 2.8-3.7.......... Full-scale plants....... Nieminski/Ongerth 1995
Cryptosporidium 2.3-2.5.. Full-scale plants....... LeChevallier and Norton
1992
Giardia 2.2-2.8.......... Full-scale plants....... ........................
Cryptosporidium 2-3...... Pilot plants............ LeChevallier and Norton
1992
Giardia and Crypto 1.5-2. Full-scale plant Foundation for Water
(operation considered Research, Britain 1994
not optimized).
Cryptosporidium 4.1-5.2.. Pilot Plant (optimal Kelley et al. 1995
treatment).
Cryptosporidum .2-1.7.... Pilot Plant (suboptimal Dugan et al. 1999
treatment). Dugan et al. 1999
Direct filtration................ Cryptosporidium 2.7-3.1.. Pilot plants............ Ongerth/Pecaroro 1995
Giardia 3.1-3.5.......... Pilot plants............ Ongerth/Pecaroro 1995
Cryptosporidium 2.7-5.9.. Pilot plants............ Patania et al. 1995
Giardia 3.4-5.0.......... Pilot plants............ Patania et al. 1995
Cryptosporidium 1.3-3.8.. Pilot plants............ Nieminski/Ongerth 1995
Giardia 2.9-4.0.......... Pilot plants............ Nieminski/Ongerth 1995
Cryptosporidium 2-3...... Pilot plants............ West et al. 1994
Rapid Granular Filtration (alone) Cryptosporidium 2.3-4.9.. Pilot plant............. Swertfeger et al., 1998
Giardia 2.7-5.4.......... ........................ ........................
----------------------------------------------------------------------------------------------------------------
Patania, Nancy L, et al. 1995
This study consisted of four pilot studies which evaluated
treatment variables for their impact on Cryptosporidium and Giardia
removal efficiencies. Raw water turbidities in the study ranged between
0.2 and 13 NTU. When treatment conditions were optimized for turbidity
and particle removal at four different sites, Cryptosporidium removal
ranged from 2.7 to 5.9 log and Giardia removal ranged from 3.4 to 5.1
log during stable filter operation. The median turbidity removal was
1.4 log, whereas the median particle removal was 2 log. Median oocyst
and cyst removal was 4.2 log. A filter effluent turbidity of 0.1 NTU or
less resulted in the most effective cyst removal, up to 1 log greater
than when filter effluent turbidities were greater than 0.1 NTU (within
the 0.1 to 0.3 NTU range). Cryptosporidium removal rates of less than
2.0 log occurred at the end of the filtration cycle.
Nieminski, Eva C. and Ongerth, Jerry E. 1995
This 2-year study evaluated Giardia and Cryptosporidium cyst
removal through direct and conventional filtration. The source water of
the full scale plant had turbidities typically between 2.5 and 11 NTU
with a maximum of 28 NTU. The source water of the pilot plant typically
had turbidities of 4 NTU with a maximum of 23 NTU. For the pilot plant
achieving filtered water turbidities between 0.1-0.2 NTU,
Cryptosporidium removals averaged 3.0 log for conventional treatment
and 3.0 log for direct filtration, while the respective Giardia
removals averaged 3.4 log and 3.3 log. For the full scale plant
achieving similar filtered water turbidities, Cryptosporidium removal
averaged 2.25 log for conventional treatment and 2.8 log for direct
filtration, while the respective Giardia removals averaged 3.3 log for
conventional treatment and 3.9 log for direct filtration. Differences
in performance between direct filtration and conventional treatment by
the full scale plant were attributed to differences in source water
quality during the filter runs.
Ongerth, Jerry E. and Pecaroro, J.P. 1995
A 1 gallon per minute (gpm) pilot scale water filtration plant was
used to measure removal efficiencies of Cryptosporidium and Giardia
using very low turbidity source waters (0.35 to 0.58 NTU). With optimal
coagulation, 3 log removal for both pathogens were obtained. In one
test run, where coagulation was intentionally sub-optimal, the removals
were only 1.5 log for Cryptosporidium and 1.3 log for Giardia. This
demonstrates the importance of proper coagulation for cyst removal even
though the effluent turbidity was less than 0.5 NTU.
LeChevallier, Mark W. and Norton, William D. 1992
The purpose of this study was to evaluate the relationships among
Giardia, Cryptosporidium, turbidity, and particle counts in raw water
and filtered water effluent samples at three different systems. Source
water turbidities ranged from less than 1 to 120 NTU. Removals of
Giardia and Cryptosporidium (2.2 to 2.8 log) were slightly less than
those reported by other researchers, possibly because full scale plants
were studied under less ideal conditions than the pilot plants. The
participating treatment plants operated within varying stages of
treatment optimization. The median removal achieved was 2.5 log for
Cryptosporidium and Giardia.
LeChevallier, Mark W.; Norton, William D.; and Lee, Raymond G. 1991b
This study evaluated removal efficiencies for Giardia and
Cryptosporidium in 66 surface water treatment plants in 14 States and 1
Canadian province. Most of the utilities achieved between 2 and 2.5 log
removals for both Giardia and Cryptosporidium. When no oocysts were
detected in the finished water, occurrence levels were assumed at the
detection limit for calculating removal efficiencies.
Foundation for Water Research 1994
This study evaluated Cryptosporidium removal efficiencies for
several treatment processes (including conventional filtration) using a
pilot plant and bench-scale testing. Raw water turbidity ranged from 1
to 30 NTU. Cryptosporidium oocyst removal was between 2 and 3 log using
conventional filtration. Investigators
[[Page 19063]]
concluded that any measure which reduced filter effluent turbidity
should reduce risk from Cryptosporidium, and also showed the importance
of selecting proper coagulants, dosages, and treatment pH. In addition
to turbidity, increased color and dissolved metal ion coagulant
concentration in the effluent are indicators of reduced efficiency of
coagulation/flocculation and possible reduced oocysts removal
efficiency.
Kelley, M.B. et al. 1995
This study evaluated two U.S. Army installation drinking water
treatment systems for the removal of Giardia and Cryptosporidium.
Protozoa removal was between 1.5 and 2 log. The authors speculated that
this low Cryptosporidium removal efficiency occurred because the
coagulation process was not optimized, although the finished water
turbidity was less than 0.5 NTU.
West, Thomas; et al. 1994
This study evaluated the removal efficiency of Cryptosporidium
through direct filtration using anthracite mono-media at filtration
rates of 6 and 14 gpm/sq.ft. Raw water turbidity ranged from 0.3 to 0.7
NTU. Removal efficiencies for Cryptosporidium at both filtration rates
were 2 log during filter ripening (despite turbidity exceeding 0.2
NTU), and 2 to 3 log for the stable filter run. Log removal declined
significantly during particle breakthrough. When effluent turbidity was
less than 0.1 NTU, removal typically exceeded 2 log. Log removals of
Cryptosporidium generally exceeded that for particle removal.
Swertfeger et al., 1998
The Cincinnati Water Works conducted a 13 month pilot study to
determine the optimum filtration media and depth of the media to
replace media at its surface water treatment plant. The study
investigated cyst and oocyst removal through filtration alone
(excluding chemical addition, mixing, or sedimentation) and examined
sand media, dual media, and deep dual media. Cyst and oocyst removal by
each of the media designs was > 2.5 log by filtration alone.
Dugan et al., 1999
EPA conducted pilot scale experiments to assess the ability of
conventional treatment to control Cryptosporidium oocysts under steady
state conditions. The work was performed with a pilot plant designed to
minimize flow rates and the number of oocysts required for spiking.
With proper coagulation control, the conventional treatment process
achieved at least 2 log removal of Cryptosporidium. In all cases where
2 log removal was not achieved, the plant also did not comply with the
IESWTR filter effluent turbidity requirements.
All of the studies described above indicate that rapid granular
filtration, when operated under appropriate coagulation conditions and
optimized to achieve a filtered water turbidity level of less than 0.3
NTU, should achieve at least 2 log of Cryptosporidium removal. Removal
rates vary widely, up to almost 6 log, depending upon water matrix
conditions, filtered water turbidity effluent levels, and where and
when removal efficiencies are measured within the filtration cycle. The
highest log pathogen removal rates occurred in those pilot plants and
systems which achieved very low finished water turbidities (less than
0.1 NTU). Other key points related to the studies include:
As turbidity performance improves for treatment of a
particular water, there tends to be greater removal of Cryptosporidium.
Pilot plant study data in particular indicate high
likelihood of achieving at least 2 log removal when plant operation is
optimized to achieve low turbidity levels. Moreover, pilot studies
represented in Table IV.2.a tend to be for low-turbidity waters, which
are considered to be the most difficult to treat regarding particulate
removal and associated protozoan removal.
Because high removal rates were demonstrated in pilot
studies using lower-turbidity source waters, it is likely that similar
or higher removal rates can be achieved for higher-turbidity source
waters.
Determining Cryptosporidium removal in full-scale plants
can be difficult due to the fact that data includes many non-detects in
the finished water. In these cases, finished water concentration levels
are assigned at the detection limit and are likely to result in over-
estimation of oocysts in the finished water. This tends to under-
estimate removal levels.
Another factor that contributes to differences among the
data is that some of the full-scale plant data comes from plants that
are not optimized, but meet existing SWTR requirements. In such cases,
oocyst removal may be less than 2 log. In those studies that indicate
that full-scale plants are achieving greater than 2 log removal
(LeChevallier studies in particular), the following characteristics
pertain:
--Substantial numbers of filtered water measurements resulted in oocyst
detections;
--Source water turbidity tended to be relatively high compared to some
of the other studies; and
--A significant percentage of these systems were also achieving low
filtered water turbidities, substantially less than 0.5 NTU.
Removal of Cryptosporidium can vary significantly in the
course of the filtration cycle (i.e., at the start-up and end of filter
operations versus the stable period of operation).
Cryptosporidium Removal Using Slow Sand and Diatomaceous Earth
Filtration
During development of the IESWTR, the Agency also evaluated several
studies which demonstrated that slow sand and diatomaceous earth
filtration were capable of achieving at least 2 log removal of
Cryptosporidium. Table IV.3 provides key information from these
studies. A brief description of each study follows the table.
Table IV.3.--Slow Sand and Diatomaceous Earth Filtration Removal Studies
----------------------------------------------------------------------------------------------------------------
Type of treatment Log removal Experimental design Researcher
----------------------------------------------------------------------------------------------------------------
Slow-sand filtration............. Giardia & Cryptosporidium Pilot plant at 4.5 to Shuler and Ghosh 1991.
> 3. 16.5 deg.C.. imms et. al. 1995.
Cryptosporidium 4.5...... Full-scale plant........
Diatomaceous earth filtration.... Giardia & Cryptosporidium Pilot plant,............ Shuler et. al. 1990.
> 3. Bench scale............. Ongerth & Hutton, 1997.
Cryptosporidium 3.3-6.68.
----------------------------------------------------------------------------------------------------------------
Shuler and Ghosh 1991
This pilot study was conducted to evaluate the ability of slow sand
filters to remove Giardia, Cryptosporidium, coliforms, and turbidity.
The pilot study was conducted at Pennsylvania State University using a
raw water source with a turbidity ranging from 0.2-0.4 NTU. Influent
concentration of
[[Page 19064]]
Cryptosporidium oocysts during the pilot study ranged from 1,300 to
13,000 oocysts/gallon. Oocyst removal was shown to be greater than 4
log.
Timms et al 1995
This pilot study was conducted to evaluate the efficiency of slow
sand filters at removing Cryptosporidium. A pilot plant was constructed
of 1.13 m\2\ in area and 0.5 m in depth with a filtration rate of 0.3m/
h. The filter was run for 4-5 weeks before the experiment to ensure
proper operation. Cryptosporidium oocysts were spiked to a
concentration of 4,000/L. Results of the study indicated a 4.5 log
removal of Cryptosporidium oocysts.
Shuler et al 1990
In this study, diatomaceous earth (DE) filtration was evaluated for
removal of Giardia, Cryptosporidium, turbidity and coliform bacteria.
The study used a 0.1m\2\ pilot scale DE filter with three grades of
diatomaceous earth (A, B, and C). The raw water turbidity varied
between 0.1 and 1 NTU. Filter runs ranged from 2 days to 34 days. A
greater than 3 log removal of Cryptosporidium was demonstrated in the 9
filter runs which made up the study.
Ongerth and Hutton, 1997
Bench scale studies were used to define basic characteristics of DE
filtration as a function of DE grade and filtration rate. Three grades
of DE were used in the tests. Cryptosporidium removal was measured by
applying river water seeded with Cryptosporidium to Walton test
filters. Tests were run for filtration rates of 1 and 2 gpm/sq ft. Each
run was replicated 3 times. Approximately 6 logs reduction in the
concentration of Cryptosporidium oocysts was expected under normal
operating conditions.
Cryptosporidium Removal Using Alternative Filtration Technologies
EPA recognizes that systems serving fewer than 10,000 individuals
employ a variety of filtration technologies other than those previously
discussed. EPA collected information regarding several other popular
treatment techniques in an effort to verify that these treatments were
also technically capable of achieving a 2 log removal of
Cryptosporidium. A brief discussion of these alternative technologies
follows along with studies demonstrating effective Cryptosporidium
removals.
Membrane Filtration
Membrane filtration (Reverse Osmosis, Nanofiltration,
Ultrafiltration, and Microfiltration) relies upon pore size in order to
remove particles from water. Membranes possess a pore size smaller than
that of a Cryptosporidium oocyst, enabling them to achieve effective
log removals. The smaller the pore size, the more effective the rate of
removal. Typical pore sizes for each of the four types of membrane
filtration are shown below:
Microfiltration--1-0.1 microns (m)
Ultrafiltration--0.1-.01 (m)
Nanofiltration--.01-.001 (m)
Reverse Osmosis--.001 (m)
Bag Filtration
Bag filters are non-rigid, disposable, fabric filters where water
flows from inside of the bag to the outside of the bag. One or more
filter bags are contained within a pressure vessel designed to
facilitate rapid change of the filter bags when the filtration capacity
has been used up. Bag filters do not generally employ any chemical
coagulation. The pore sizes in the filter bags designed for protozoa
removal generally are small enough to remove protozoan cysts and
oocysts but large enough that bacteria, viruses and fine colloidal
clays would pass through. Bag filter studies have shown a significant
range of results in the removal of Cryptosporidium oocysts (0.33-3.2
log). (Goodrich, 1995)
Cartridge Filtration
Cartridge filtration also relies on physical screening to remove
particles from water. Typical cartridge filters are pressure filters
with glass, fiber or ceramic membranes, or strings wrapped around a
filter element housed in a pressure vessel (USEPA, 1997a).
The Agency evaluated several studies which demonstrate the ability
of various alternative filtration technologies to achieve 2 log removal
of Cryptosporidium ( in several studies 2 log removal of 4-5
(m) microspheres were used as a surrogate for
Cryptosporidium). These studies demonstrate that 2 log removal was
consistently achievable in all but bag filters. Table IV.4 provides key
information from these studies. A brief description of each study
follows:
Table IV.4.--Alternative Filtration Removal Studies
----------------------------------------------------------------------------------------------------------------
Type of treatment Log removal Experimental design Researcher
----------------------------------------------------------------------------------------------------------------
Microfiltration.................. Cryptosporidium 4.2-4.9 Bench Scale............. Jacangelo et al. 1997.
log.
Giardia 4.6-5.2 log...... ........................
Cryptosporidium 6.0--7.0 Pilot Plant............. ........................
log.
Cryptosporidium 4.3--5.0 Pilot Plant............. Drozd & Schartzbrod,
log. 1997.
Cryptosporidium 7.0-7.7 Bench Scale............. Hirata & Hashimoto,
log. 1998.
Microspheres 3.57-3.71 Full Scale.............. Goodrich et al. 1995.
log.
Ultrafiltration.................. Cryptosporidium 4.4--4.9 Bench Scale............. Jacangelo et al. 1997.
log.
Giardia 4.7-5.2 log...... ........................
Cryptosporidium 5.73-5.89 Bench Scale............. Collins et al. 1996.
log.
Giardia 5.75-5.85 log.... ........................
Cryptosporidium 7.1-7.4 Bench Scale............. Hirata & Hashimoto,
log. 1998.
Cryptosporidium 3.5 log.. pilot Plant............. Lykins et al. 1994.
Microspheres 3-4 log.....
Reverse Osmosis.................. Cryptosporidium > 5.7 log Pilot Scale............. Adham et al. 1998
Giardia > 5.7 log........
Hybrid Membrane.................. Microspheres 4.18 log.... Bench Scale............. Goodrich et al. 1995
Bag Filtration................... Microspheres .33-3.2 log. Pilot Plant............. Goodrich et al. 1995
Cartridge filtration............. Microspheres 3.52-3.68 Pilot Plant............. Goodrich et al. 1995
log. Bench Scale............. Land, 1998.
Particles (5-15 um) > 2
log.
----------------------------------------------------------------------------------------------------------------
[[Page 19065]]
Jacangelo et al., 1997
Bench scale and pilot plant tests were conducted with
microfiltration and ultrafiltration filters (using six different
membranes) in order to evaluate microorganism removal. Bench scale
studies were conducted under worst case operating conditions (direct
flow filtration at the maximum recommended transmembrane pressure using
deionized water slightly buffered at pH 7). Log removal ranged from 4.7
to 5.2 log removal. Pilot plant results ranged from 6.0-7.0 log removal
during worst-case operating conditions (i.e., direct filtration
immediately after backwashing at the maximum recommended operating
transmembrane pressure).
Drozd and Schartzbrod, 1997
A pilot plant system was established to evaluate the removal of
Cryptosporidium using crossflow microfiltration (.2 m
porosity). Results demonstrated Cryptosporidium log removals of 4.3 to
greater than 5.5 with a corresponding mean filtrate turbidity of 0.25
NTU.
Collins et. al., 1996
This study consisted of bench scale testing of Cryptosporidium and
Giardia log removals using an ultrafiltration system. Log removal of
Cryptosporidium ranged from 5.73 to 5.89 log, while removal of Giardia
ranged from 5.75 to 5.85 log.
Hirata & Hashimoto, 1998
Pilot scale testing using microfiltration (nominal pore size of .25
m) and ultrafiltration (nominal cut-off molecular weight (MW)
13,000 daltons) was conducted to determine Cryptosporidium oocyst
removal. Results conducted on the ultrafiltration units ranged from 7.1
to 7.5 logs of Cryptosporidium removal. Results of the microfiltration
studies yielded log removals from 7.0 to 7.7 log.
Lykins et al., [1994]
An ultrafiltration system was evaluated for the removal of
Cryptosporidium oocysts at the USEPA Test and Evaluation Facility in
Cincinnati, Ohio. The filter run was just over 48 hours. A 3.5 log
removal of Cryptosporidium oocysts was observed. Additionally, twenty-
four experiments were performed using 4.5 m polystyrene
microspheres as a surrogate for Cryptosporidium because of a similar
particle distribution. Log removal of microspheres ranged from 3 to 4
log.
Adham et al., 1998
This study was conducted to evaluate monitoring methods for
membrane integrity. In addition to other activities, microbial
challenge tests were conducted on reverse osmosis (RO) membranes to
both determine log removals and evaluate system integrity. Log removal
of Cryptosporidium and Giardia was >5.7 log in uncompromised
conditions, and > 4.5 log in compromised conditions.
Goodrich et al., 1995
This study was conducted to evaluate removal efficiencies of three
different bag filtration systems. Average filter pore size of the
filters was 1 m while surface area ranged from 35 to 47 sq ft.
Bags were operated at 25, 50 and 100 percent of their maximum flow rate
while spiked with 4.5 m polystyrene microspheres (beads) as a
surrogate for Cryptosporidium. Bead removal ranged from .33 to 3.2 log
removal.
Goodrich et al 1995.
This study evaluated a cartridge filter with a 2 m rating
and 200 square feet of surface area for removal efficiency of
Cryptosporidium sized particles. The filter was challenge tested with
4.5 m polystyrene microspheres as a surrogate for
Cryptosporidium. Flow was set at 25 gpm with 50 psi at the inlet.
Results from two runs under the same conditions exhibited log removals
of 3.52 and 3.68.
Land, 1998
An alternative technology demonstration test was conducted to
evaluate the ability of a cartridge filter to achieve 2 log removal of
particles in the 5 to 15 m range. The cartridge achieved at
least 2 log removal of the 5 to 25 m particles 95 percent of
the time up to a 20 psi pressure differential. The filter achieved at
least 2 log removal of 5 to 15 m particles up to 30-psi
pressure differential.
While the studies above note that alternative filtration
technologies have demonstrated in the lab the capability to achieve a 2
log removal of Cryptosporidium, the Agency believes that the
proprietary nature of these technologies necessitates a more rigorous
technology-specific determination be made. Given this issue, the Agency
believes that its Environmental Technology Verification (ETV) Program
can be utilized to verify the performance of innovative technologies.
Managed by EPA's Office of Research and Development, ETV was created to
substantially accelerate the entrance of new environmental technologies
into the domestic and international marketplace. ETV consists of 12
pilot programs, one of which focuses on drinking water. The program
contains a protocol for physical removal of microbiological and
particulate contaminants, including test plans for bag and cartridge
filters and membrane filters (NSF, 1999). These protocols can be
utilized to determine whether a specific alternative technology can
effectively achieve a 2 log removal of Cryptosporidium, and under what
parameters that technology must be operated to ensure consistent levels
of removal. Additional information on the ETV program can be found on
the Agency's website at http://www.epa.gov/etv.
iii. Proposed Requirements
Today's proposed rule establishes a requirement for 2 log removal
of Cryptosporidium for surface water and GWUDI systems serving fewer
than 10,000 people that are required to filter under the SWTR.
Compliance with the combined filter effluent turbidity requirements, as
described later, ensures compliance with the 2 log removal requirement.
The requirement for a 2 log removal of Cryptosporidium applies between
a point where the raw water is not subject to recontamination by
surface water runoff and a point downstream before or at the first
customer.
iv. Request for Comments
EPA requests comment on the 2 log removal requirement as discussed.
The Agency is also soliciting public comment and data on the ability of
alternative filtration technologies to achieve 2 log Cryptosporidium
removal.
2. Turbidity Requirements
a. Combined Filter Effluent
i. Overview and Purpose
In order to address concern with Cryptosporidium, EPA has analyzed
log removal performance by well operated plants (as described in the
previous section) as well as filter performance among small systems to
develop an appropriate treatment technique requirement that assures an
increased level of Cryptosporidium removal. In evaluating combined
filter performance requirements, EPA considered the strengthened
turbidity provisions within the IESWTR and evaluated whether these were
appropriate for small systems as well.
ii. Data
In an effort to evaluate combined filter effluent (CFE)
requirements, EPA collected data in several areas to
[[Page 19066]]
supplement existing data, and address situations unique to smaller
systems. This data includes:
An estimate of the number of systems subject to the
proposed strengthened turbidity requirements;
Current turbidity levels at systems throughout the U.S.
serving populations fewer than 10,000;
The ability of package plants to meet strengthened
turbidity standards; and
The correlation between meeting CFE requirements and
achieving 2 log removal of Cryptosporidium.
Estimate of the Number of Systems Subject to Strengthened CFE Turbidity
Standards
Using the estimate of 9,134 systems which filter and serve fewer
than 10,000 persons (as described in Section IV.A.1 of today's
proposal), the Agency used the information contained within the CWSS
database to estimate the number of systems which utilized specific
types of filtration. The data was segregated based on the type of
filtration utilized and the population size of the system. Percentages
were derived for each of the following types of filtration:
Conventional and Direct Filtration;
Slow Sand Filtration;
Diatomaceous Earth Filtration; and
Alternative Filtration Technologies.
The percentages were applied to the estimate discussed in Section
IV.A.1 of today's proposal for each of the respective population
categories. Based on this analysis, the Agency estimates 5,896
conventional and direct filtration systems will be subject to the
strengthened combined filter effluent turbidity standards. EPA
estimates 1,756 systems utilize slow sand or diatomaceous earth
filtration, and must continue to meet turbidity standards set forth in
the SWTR. The remaining 1,482 systems are estimated to use alternative
filtration technologies and will be required to meet turbidity
standards as set forth by the State upon analysis of a 2 log
Cryptosporidium demonstration conducted by the system.
Current Turbidity Levels
EPA has developed a data set which summarizes the historical
turbidity performance of various filtration plants serving populations
fewer than 10,000 (EPA, 1999d). The data set represents those systems
that were in compliance with the turbidity requirements of the SWTR
during all months being analyzed. The data set consists of 167 plants
from 15 States. Table IV.5 provides information regarding the number of
plants from each State. The data set includes plants representing each
of the five population groups utilized in the CWSS (25-100, 101-500,
501-1,000, 1,001-3,300, and 3,301-10,000). The Agency has also received
an additional data set from the State of California (EPA, 2000). This
data has not been included in the assessments described below. The
California data demonstrates similar results to the larger data set
discussed below.
Table IV.5.--Summary of LT1FBR Turbidity Data Set
------------------------------------------------------------------------
Number of
State Plants
------------------------------------------------------------------------
Alabama.................................................... 1
California................................................. 1
Colorado................................................... 16
Illinois................................................... 13
Kansas..................................................... 20
Louisiana.................................................. 6
Minnesota.................................................. 3
Montana.................................................... 2
North Carolina............................................. 16
Ohio....................................................... 4
Pennsylvania............................................... 27
South Carolina............................................. 16
Texas...................................................... 23
Washington................................................. 17
West Virginia.............................................. 2
------------
Total.................................................. 167
------------------------------------------------------------------------
(EPA, 1999d)
This data was evaluated to assess the national impact of modifying
existing turbidity requirements. The current performance of plants was
assessed with respect to the number of months in which selected 95th
percentile and maximum turbidity levels were met. The data show that
approximately 88 percent of systems are also currently meeting the new
requirements of a maximum turbidity limit of 1 NTU (Figure IV.1). With
respect to the 95th percentile turbidity limit, roughly 46 percent of
these systems are currently meeting the new requirement of 0.3 NTU
(Figure IV.2) while approximately 70 percent meet this requirement 9
months out of the year. Estimates for systems needing to make changes
to meet a turbidity performance limit of 0.3 NTU were based on the
ability of systems currently to meet a 0.2 NTU. This assumption was
intended to take into account a utility's concern with possible
turbidity measurement error and to reflect the expectation that a
number of utilities will attempt to achieve finished water turbidity
levels below the regulatory performance level to assure compliance.
As depicted in Figure IV.1 and IV.2, the tighter turbidity
performance standards for combined filter effluent in today's proposed
rule reflect the actual, current performance many systems already
achieve nationally. Revising the turbidity criteria effectively ensures
that these systems continue to perform at their current level while
also improving performance of a substantial number of systems that
currently meet existing SWTR criteria, but operate at turbidity levels
higher than proposed in today's rule.
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[[Page 19067]]
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[[Page 19069]]
Package Plants
During development of today's proposed rule, some stakeholders
expressed concern regarding the ability of ``package plants'' to meet
the proposed requirements. EPA evaluated these systems by gathering
data from around the country. The information affirms the Agency's
belief that package plants can and currently do meet the turbidity
limits in today's proposed rule.
Package plants combine the processes of rapid mixing, flocculation,
sedimentation and filtration (rapid sand, mixed or dual media filters)
into a single package system. Package Filtration Plants are
preconstructed, skid mounted and transported virtually assembled to the
site. The use of tube settlers, plate settlers, or adsorption
clarifiers in some Package Filtration Plants results in a compact size
and more treatment capacity.
Package Filtration Plants are appropriate for treating water of a
fairly consistent quality with low to moderate turbidity. Effective
treatment of source waters containing high levels of or extreme
variability in turbidity levels requires skilled operators and close
operational attention. High turbidity or excessive color in the source
water could require chemical dosages above the manufacturer's
recommendations for the particular plant. Excessive turbidity levels
may require presedimentation or a larger capacity plant. Specific
design criteria of a typical package plant and operating and
maintenance requirements can vary, but an example schematic is depicted
in Figure IV.3.
[[Page 19070]]
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[[Page 19071]]
The Agency believes that historic data show that package plants
have a comparable ability to meet turbidity requirements as
conventional or direct filtration systems.
A 1987 report of pilot testing using a trailer-mounted package
plant system to treat raw water from Clear Lake in Lakeport, California
demonstrates the ability of such systems to achieve low turbidity
requirements. The raw water contained moderate to high turbidity (18 to
103 NTU). Finished water turbidities ranged from 0.07 to 0.11 NTU (EPA,
1987). Two previous studies (USEPA, 1980a,b and Cambell et al., 1995)
also illustrate the ability of package systems throughout the country
to meet historic turbidity performance criteria. These studies are
described briefly:
Package Water Treatment Plant Performance Evaluation (USEPA, 1980a,b)
The Agency conducted a study of package water treatment systems
which encompassed 36 plants in Kentucky, West Virginia, and Tennessee.
Results from that study showed that the plants could provide water that
met the existing turbidity limits established under the National
Interim Primary Drinking Water Standards. Of the 31 plants at which
turbidity measurements were made, 23 (75 percent) were found to be
meeting existing standards. Of the 8 which did not meet requirements,
one did not use chemical coagulants, and 6 operated less than four
hours per day. (USEPA, 1980a, b)
Package Plants for Small Systems: A Field Study (Cambell et al, 1995)
This 1992 project evaluated the application of package plant
technology to small communities across the U.S. The project team
visited 48 facilities across the U.S. Of the 29 surface water and GWUDI
systems, 21 (72 percent) had grab turbidity samples less than 0.5 NTU,
the 95 percent limit which became effective in June of 1993. Twelve
systems (41 percent) had values less than today's proposed 0.3 NTU 95
percent turbidity limit. (Cambell et al., 1995) It should be noted that
today's rule requires compliance with turbidity limits based on 4 hour
measurments.
The Agency recently evaluated Filter Plant Performance Evaluations
(FPPEs) conducted by the State of Pennsylvania, in an effort to
quantify the comparative abilities of package plants and conventional
filtration systems to meet the required turbidity limits. The data set
consisted of 100 FPPEs conducted at systems serving populations fewer
than 10,000 (PADEP, 1999). Thirty-seven FPPEs were conducted at
traditional conventional filtration systems while 37 were conducted at
package plants or ``pre-engineered'' systems. The remaining 26 systems
utilized other filtration technologies.
The FPPEs provided a rating of either acceptable or unacceptable as
determined by the evaluation team. This rating was based on an
assessment of the capability of individual unit processes to
continuously provide an effective barrier to the passage of
microorganisms. Specific performance goals were utilized to evaluate
the performance of the system including the consistent ability to
produce a finished water turbidity of less than 0.1 NTU, which is lower
than the combined filter effluent turbidity requirement in today's
proposed rule. Seventy-three percent of the traditional conventional
filtration systems were rated acceptable and 89 percent of the package
plants were rated acceptable.
The Agency also evaluated historic turbidity data graphs contained
within each FPPE to provide a comparison of the ability of package
plants and conventional systems to meet the 1 NTU max and 0.3 NTU 95
percent requirements that are contained in today's proposed rule.
Sixty-seven percent of the conventional systems would meet today's
proposed requirements while 74 percent of package systems in the data
set would meet today's proposed requirements. The Agency believes that,
when viewed alongside the aforementioned studies (USEPA, 1980a,b and
Cambell et al., 1995), it is apparent that package systems have the
ability to achieve more stringent turbidity limits.
Correlation Between CFE Requirements and 2-log Cryptosporidium Removal
Recent pilot scale experiments performed by the Agency assessed the
ability of conventional treatment to control Cryptosporidium under
steady state conditions. The work was performed with a pilot plant that
was designed to minimize flow rates and as a result the number of
oocyst required for continuous spiking. (Dugan et al. 1999)
Viable oocysts were fed into the plant influent at a concentration
of 106/L for 36 to 60 hours. The removals of oocysts and the
surrogate parameters turbidity, total particle counts and aerobic
endospores were measured through sedimentation and filtration. There
was a positive correlation between the log removals of oocysts and all
surrogate parameters through the coagulation and settling process. With
proper coagulation control, the conventional treatment process achieved
the 2 log total Cryptosporidium removal required by the IESWTR. In all
cases where 2 log total removal was not achieved, the plant also did
not comply with the IESWTR's CFE turbidity requirements. Table IV.6
provides information on Cryptosporidium removals from this study.
Table IV.6.--Log Removal of Oocysts (Dugan et al. 1999)
------------------------------------------------------------------------
Log removal
Run crypto Exceeds CFE requirements
------------------------------------------------------------------------
1................................ 4.5 No.
2................................ 5.2 No.
3................................ 1.6 Yes, average CFE 2.1
NTU.
4................................ 1.7 Yes, only 88% CFE under
0.3 NTU.
5................................ 4.1 No.
6................................ 5.1 No.
7................................ 0.2 Yes, average CFE 0.5
NTU.
8................................ 0.5 Yes, only 83% CFE under
0.3 NTU.
9................................ 5.1 No.
10............................... 4.8 No.
------------------------------------------------------------------------
[[Page 19072]]
iii. Proposed Requirements
Today's proposed rule establishes combined filter effluent
turbidity requirements which apply to all surface water and GWUDI
systems which filter and serve populations fewer than 10,000. For
conventional and direct filtration systems, the turbidity level of
representative samples of a system's combined filter effluent water
must be less than or equal to 0.3 NTU in at least 95 percent of the
measurements taken each month. The turbidity level of representative
samples of a system's filtered water must not exceed 1 NTU at any time.
For membrane filtration, (microfiltration, ultrafiltration,
nanofiltration, and reverse osmosis) the Agency is proposing to require
that the turbidity level of representative samples of a system's
combined filter effluent water must be less than or equal to 0.3 NTU in
at least 95 percent of the measurements taken each month. The turbidity
level of representative samples of a system's filtered water must not
exceed 1 NTU at any time. EPA included turbidity limits for membrane
systems to allow such systems the ability to opt out of a possible
costly demonstration of the ability to remove Cryptosporidium. The
studies displayed previously in Table IV.4, demonstrate the ability of
these technologies to achieve log-removals in excess of 2 log. In lieu
of these turbidity limits, a public water system which utilizes
membrane filtration may demonstrate to the State for purposes of
membrane approval (using pilot plant studies or other means) that
membrane filtration in combination with disinfection treatment
consistently achieves 3 log removal and/or inactivation of Giardia
lamblia cysts, 4 log removal and/or inactivation of viruses, and 2 log
removal of Cryptosporidium oocysts. For each approval, the State will
set turbidity performance requirements that the system must meet at
least 95 percent of the time and that the system may not exceed at any
time at a level that consistently achieves 3 log removal and/or
inactivation of Giardia lamblia cysts, 4 log removal and/or
inactivation of viruses, and 2 log removal of Cryptosporidium oocysts.
Systems utilizing slow sand or diatomaceous earth filtration must
continue to meet the combined filter effluent limits established for
these technologies under the SWTR (found in Sec. 141.73 (b) and (c)).
Namely, the turbidity level of representative samples of a system's
filtered water must be less than or equal to 1 NTU in at least 95
percent of the measurements taken each month and the turbidity level of
representative samples of a system's filtered water must at no time
exceed 5 NTU.
For all other alternative filtration technologies (those other than
conventional, direct, slow sand, diatomaceous earth, or membrane),
public water systems must demonstrate to the State for purposes of
approval (using pilot plant studies or other means), that the
alternative filtration technology in combination with disinfection
treatment, consistently achieves 3 log removal and/or inactivation of
Giardia lamblia cysts, 4 log removal and/or inactivation of viruses,
and 2 log removal of Cryptosporidium oocysts. For each approval, the
State will set turbidity performance requirements that the system must
meet at least 95 percent of the time and that the system may not exceed
at any time at a level that consistently achieves 3 log removal and/or
inactivation of Giardia lamblia cysts, 4 log removal and/or
inactivation of viruses, and 2 log removal of Cryptosporidium oocysts.
iv. Request for Comments
EPA solicits comment on the proposal to require systems to meet the
proposed combined filter effluent turbidity requirements. Additionally,
EPA solicits comment on the following:
The ability of package plants and/or other unique
conventional and/or direct systems to meet the combined filter effluent
requirements;
Microbial attachment to particulate material or inert
substances in water systems may have the effect of providing
``shelter'' to microbes by reducing their exposure to disinfectants
(USEPA, 1999e). While inactivation of Cryptosporidium is not a
consideration of this rule, should maximum combined filter effluent
limits for slow sand and diatomaceous earth filtration systems be
lowered to 1 or 2 NTU and/or 95th percentile requirements lowered to
0.3 NTU to minimize the ability of turbidity particles to ``shelter''
Cryptosporidium oocysts?
Systems which practice enhanced coagulation may produce
higher turbidity effluent because of the process. Should such systems
be allowed to apply to the State for alternative exceedance levels
similar to the provisions contained in the rule for systems which
practice lime softening?
Issues specific to small systems regarding the proposed
combined filter effluent requirements;
Establishment of turbidity limits for alternative
filtration technologies;
Allowance of a demonstration to establish site specific
limits in lieu of generic turbidity limits, including components of
such demonstration; and
The number of small membrane systems employed throughout
the country.
The Agency also requests comment on establishment of turbidity
limits for membrane systems. While integrity of membranes provides the
clearest understanding of the effectiveness of membranes, turbidity has
been utilized as an indicator of performance (and corresponding
Cryptosporidium log removal) for all filtration technologies. EPA
solicits comment on modifying the requirements for membrane filters to
meet integrity testing, as approved by the State and with a frequency
approved by the State.
b. Individual Filter Turbidity
i. Overview and Purpose
During development of the IESWTR, it was recognized that
performance of individual filters within a plant were of paramount
importance to producing low-turbidity water. Two important concepts
regarding individual filters were discussed. First, it was recognized
that poor performance (and potential pathogen breakthrough) of one
filter could be masked by optimal performance in other filters, with no
discernable rise in combined filter effluent turbidity. Second, it was
noted that individual filters are susceptible to turbidity spikes (of
short duration) which would not be captured by four-hour combined
filter effluent measurements. To address the shortcomings associated
with individual filters, EPA established individual filter monitoring
requirements in the IESWTR. For the reasons discussed below, the Agency
believes it appropriate and necessary to extend individual filter
monitoring requirements to systems serving populations fewer than
10,000 in the LT1FBR.
ii. Data
EPA believes that the support and underlying principles regarding
the IESWTR individual filter monitoring requirements are also
applicable for the LT1FBR. The Agency has estimated that 5,897
conventional and direct filtration systems will be subject to today's
proposed individual filter turbidity requirements. Information
regarding this estimate is found in Section IV.A.2.a of today's
proposal. The Agency has analyzed information regarding turbidity
spikes and filter masking which are presented next.
[[Page 19073]]
Turbidity Spikes
During a turbidity spike, significant amounts of particulate matter
(including Cryptosporidium oocysts, if present) may pass through the
filter. Various factors affect the duration and amplitude of filter
spikes, including sudden changes to the flow rate through the filter,
treatment of the filter backwash water, filter-to-waste capability, and
site-specific water quality conditions. Recent experiments have suggest
that surging has a significant effect on rapid sand filtration
performance (Glasgow and Wheatley, 1998). An example filter profile
depicting turbidity spikes is shown in Figure IV.4.
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Studies considered by both EPA and the M-DBP Advisory Committee
noted that the greatest potential for a peak in turbidity (and thus,
pathogen breakthrough) is near the beginning of the filter run after
filter backwash or start up of operation (Amirtharajah, 1988; Bucklin,
et al. 1988; Cleasby, 1990; and Hall and Croll, 1996). This phenomenon
is depicted in Figure IV.4. Turbidity spikes also may occur for a
variety of other reasons. These include:
Outages or maintenance activities at processes within the
treatment train;
Coagulant feed pump or equipment failure;
Filters being run at significantly higher loading rates
than approved;
Disruption in filter media;
Excessive or insufficient coagulant dosage; and
Hydraulic surges due to pump changes or other filters
being brought on/off-line.
A recent study was completed which evaluated particle removal by
filtration throughout the country. While the emphasis of this study was
particle counting and removal, fifty-two of the 100 plants surveyed
were also surveyed for turbidity with on-line turbidimeters. While all
of the plants were able to meet 0.5 NTU 95 percent of the time, it was
noted that there was a significant occurrence of spikes during the
filter runs. These were determined to be a major source of raising the
95th percentile value for most of the filter runs. (McTigue et al.
1998)
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Masking of Filter Performance
Combined Filter Effluent monitoring can mask poor performance of
individual filters which may allow passage of particulates (including
Cryptosporidium oocysts). One poorly performing filter, can be
effectively ``masked'' by other well operated filters because water
from each of the filters is combined before an effluent turbidity
measurement is taken. The following example illustrates this
phenomenon.
The fictitious City of ``Smithville'' (depicted in Figure IV.6)
operates a conventional filtration plant with four rapid granular
filters as shown below. Filter number 1 has significant problems
because the depth and placement of the media are contributing to
elevated turbidities. Filters 2, 3, and 4 do not have these problems
and are operating properly.
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Turbidity measurements taken at the clearwell indicate 0.3 NTU.
Filter 4 produces water with a turbidity of 0.08 NTU, Filter 3 a
turbidity of 0.2 NTU, Filter 2 a turbidity of 0.1 NTU, and Filter 1 a
turbidity of 0.9 NTU. Each filter contributes an equal proportion of
water, but each is operating at different turbidity levels which
contributes to the combined filter effluent of 0.32 NTU.
([0.08+0.2+0.1+0.9]4 = 0.32 NTU)
As discussed previously in Section IV.2.a, the Agency believes that
a system must meet 0.3 NTU 95 percent of the time an appropriate
treatment technique requirement that assures an increased level of
Cryptosporidium removal. While the fictitious system described above
would barely meet the required CFE turbidity, it is entirely possible
that they would not be achieving an overall 2 log removal of
Cryptosporidium with one filter achieving considerably less than 2-log
removal. This issue highlights the importance of understanding the
performance of individual filters relative to overall plant
performance.
iii. Proposed Requirements
Today's proposed rule establishes an individual filter turbidity
requirement which applies to all surface water and GWUDI systems using
filtration and which serve populations fewer than 10,000 and utilize
direct or conventional filtration. In developing this requirement, the
Agency evaluated several alternatives (A, B and C) in an attempt to
reduce the burden faced by small systems while still providing: (1) A
comparable level of public health protection as that afforded to
systems serving 10,000 or more people and (2) an early-warning tool
systems can use to detect and correct problems with filters.
Alternative A
The first alternative considered by the Agency was requiring direct
and conventional filtration systems serving populations fewer than
10,000 to meet the same requirements as established for systems serving
10,000 or more people. This alternative would require that all
conventional and direct filtration systems must conduct continuous
monitoring of turbidity (one turbidity measurement every 15 minutes)
for each individual filter. Systems must provide an exceptions report
to the State as part of the existing combined filter effluent reporting
process for any of the following circumstances:
(1) Any individual filter with a turbidity level greater than 1.0
NTU based on two consecutive measurements fifteen minutes apart;
(2) Any individual filter with a turbidity greater than 0.5 NTU at
the end of the first four hours of filter operation based on two
consecutive measurements fifteen minutes apart;
(3) Any individual filter with turbidity levels greater than 1.0
NTU based on two consecutive measurements fifteen minutes apart at any
time in each of three consecutive months (the system must, in addition
to filing an exceptions report, conduct a self-assessment of the
filter); and
(4) Any individual filter with turbidity levels greater than 2.0
NTU based on two consecutive measurements fifteen minutes apart at any
time in each of two consecutive months (the system must file an
exceptions report and must arrange for a comprehensive performance
evaluation (CPE) to be conducted by the State or a third party approved
by the State).
Under the first two circumstances identified, a system must produce
a filter profile if no obvious reason for the abnormal filter
performance can be identified.
Alternative B
The second alternative considered by the Agency represents a slight
modification from the individual filter monitoring requirements of
large systems. The 0.5 NTU exceptions report trigger would be omitted
in an effort to reduce the burden associated with daily data
evaluation. Additionally, the filter profile requirement would be
removed. Requirement language was slightly modified in an effort to
simplify the requirement for small system operators. This alternative
would still require that all conventional and direct filtration systems
conduct continuous monitoring (one turbidity measurement every 15
minutes) for each individual filter, but includes the following three
requirements:
(1) A system must provide an exceptions report to the State as part
of the existing combined effluent reporting process if any individual
filter turbidity measurement exceeds 1.0 NTU (unless the system can
show that the next reading is less than 1.0 NTU);
(2) If a system is required to submit an exceptions report for the
same filter in three consecutive months, the system must conduct a
self-assessment of the filter.
(3) If a system is required to submit an exceptions report for the
same filter in two consecutive months which contains an exceedance of
2.0 NTU by the same filter, the system must arrange for a CPE to be
conducted by the State or a third party approved by the State.
Alternative C
The third alternative considered by the Agency would include new
triggers for reporting and follow-up action in an effort to reduce the
daily burden associated with data review. This alternative would still
require that all conventional and direct filtration systems must
conduct continuous monitoring (one turbidity measurement every 15
minutes) for each individual filter, but would include the following
three requirements:
(1) A system must provide an exceptions report to the State as part
of the existing combined effluent reporting process if filter samples
exceed 0.5 NTU in at least 5 percent of the measurements taken each
month and/or any individual filter measurement exceeds 2.0 NTU (unless
the system can show that the following reading was 2.0 NTU).
(2) If a system is required to submit an exceptions report for the
same filter in three consecutive months the system must conduct a self-
assessment of the filter.
(3) If a system is required to submit an exceptions report for the
same filter in two consecutive months which contains an exceedance of
2.0 NTU by the same filter, the system must arrange for a CPE to be
conducted by the State or a third party approved by the State.
For all three alternatives the requirements regarding self
assessments and CPEs are the same. If a CPE is required, the system
must arrange for the State or a third party approved by the State to
conduct the CPE no later than 30 days following the exceedance. The CPE
must be completed and submitted to the State no later than 90 days
following the exceedance which triggered the CPE. If a self-assessment
is required it must take place within 14 days of the exceedance and the
system must report to the State that the self-assessment was conducted.
The self assessment must consist of at least the following components:
assessment of filter performance;
development of a filter profile;
identification and prioritization of factors limiting
filter performance;
assessment of the applicability of corrections; and
preparation of a filter self assessment report.
In considering each of the above alternatives, the Agency attempted
to reduce the burden faced by small systems. Each of the three
alternatives was judged to provide levels of public health protection
comparable to those in the IESWTR for large systems. Alternative A,
because it contains the
[[Page 19085]]
same requirements as IESWTR, was expected to afford the same level of
public health protection. Alternative B, (which removes the four-hour
0.5 NTU trigger and the filter profile requirement) was expected to
afford comparable health protection because the core components which
provide the overwhelming majority of the public health protection
(monitoring frequency, trigger which requires follow-up action, and the
follow-up actions) are the same as the IESWTR. Alternative C was
expected to provide comparable health protection because follow-up
action is the same as under the IESWTR and a 0.5 NTU 95percent
percentile trigger was expected to identify the same systems which the
triggers established under the IESWTR would identify. All three were
also considered useful diagnostic tools for small systems to evaluate
the performance of filters and correct problems before follow-up action
was necessary. The first alternative was viewed as significantly more
challenging to implement and burdensome for smaller systems due to the
amount of required daily data review. This evaluation was also echoed
by small entity representatives during the Agency's SBREFA process as
well as stakeholders at each of the public meetings held to discuss
issues related to today's proposed rule. While Alternative C reduced
burden associated with daily data review, it would institute a very
different trigger for small systems than established by the IESWTR for
large systems. This was viewed as problematic by several stakeholders
who stressed the importance of maintaining similar requirements in
order to limit transactional costs and additional State burden.
Therefore, the Agency is proposing Alternative B as described above,
which allows operators to expend less time to evaluate their turbidity
data. Alternative B maintains a comparable level of public health
protection as those afforded large systems, reduces much of the burden
associated with daily data collection and review (removing the
requirement to conduct a filter profile allows systems to review data
once a week instead of daily if they so choose), yet still serves as a
self-diagnostic tool for operators and provides the mechanism for State
follow-up when significant performance problems exist.
iv. Request for Comments
The individual filter monitoring provisions represent a challenging
opportunity to provide systems with a useful tool for assessing filters
and correcting problems before State intervention is necessary or
combined filter turbidity is affected and treatment technique
violations occur. The Agency is actively seeking comment on this
provision. Because of the complexity of this provision, specific
requests for comment have been broken down into five distinct areas.
Comments on the Alternatives
EPA requests comment on today's proposed individual filter
requirement and each of the alternatives as well as additional
alternatives for this provision such as establishing a different
frequency for individual filter monitoring (e.g., 60 minute or 30
minute increments). The Agency also seeks comment or information on:
Tools and or guidance which would be useful and necessary
in order to educate operators on how to comply with individual filter
provisions and perform any necessary calculations;
Data correlating individual filter performance relative to
combined filter effluent;
Contributing factors to turbidity spikes associated with
reduced filter performance;
Practices which contribute to poor individual filter
performance and filter spikes; and
Any additional concerns with individual filter
performance.
Modifications to the Alternatives
The Agency also seeks comment on a variety of proposed
modifications to the individual filter monitoring alternatives
discussed which could be incorporated in order to better address the
concerns and realities of small surface water systems. These
modifications include:
Modification of the alternatives to include a provision
which would require systems which do not staff the plant during all
hours of operation, to utilize an alarm/phone system to alert off-site
operators of significantly elevated turbidity levels and poor
individual filter performance;
A modification to allow conventional and direct filtration
systems with either 2-3 or less filters to sample combined filter
effluent continuously (every 15 minutes) in lieu of monitoring
individual filter turbidity. This modification would reduce the data
collection/analysis burden for the smallest systems while not
compromising the level of public health protection;
A modification to lengthen the period of time (120 days or
a period of time established by the State but not to exceed 120 days)
for completion of the CPE and/or a modification to lengthen the
requirement that a CPE must be conducted no later than 60 or 90 days
following the exceedance; and
A modification to require systems to notify the State
within 24 hours of triggering the CPE or IFA. This would inform States
sooner so they can begin to work with systems to address performance of
filters and conduct CPEs and IFAs as necessary.
Establishment of Subcategories
The Agency is also evaluating the need to establish subcategories
in the final rule for individual filter monitoring/reporting. EPA is
currently considering these three categories:
1. Systems serving populations of 3,300 or more persons;
2. Systems with more than 2 filters, but less than 3,300 persons;
and
3. Systems with 2 or fewer filters serving populations fewer than
3,300 persons.
Individual filter monitoring requirements would also be based on
these subcategories. Systems serving 3,300 or greater would be required
to meet the same individual turbidity requirements as the IESWTR
(Alternative A as described above). Systems serving fewer than 3,300
but using more than 2 filters would be required to meet a modified
version of the IESWTR individual filter requirements (Alternative B as
described above). Systems serving fewer than 3,300 and using 2 or fewer
filters would continue to monitor and report only combined filter
effluent turbidity at an increased frequency (once every 15 minutes, 30
minutes, or one hour).
Input and or comment on cut-offs for subcategories and how to apply
subcategories to Alternatives is requested. The Agency would also like
to take comment on additional strategies to tailor individual filter
monitoring for the smallest systems while continuing to maintain an
adequate level of public health protection. Such possible strategies
include:
Since small systems are often understaffed one approach
would require those systems utilizing only two or fewer filters to
utilize, maintain, and continually operate an alarm/phone system during
all hours of operation, which alert off-site operators of significantly
elevated turbidity levels and poor individual filter performance and/or
automatically shuts the system down if turbidity levels exceed a
specified performance level. This modification would be in addition to
the proposed requirements.
Establishing a more general modification which would
require systems which do not staff the plant during all hours of
operation to utilize
[[Page 19086]]
an alarm/phone system to alert off-site operators of significantly
elevated turbidity levels and poor individual filter performance, and/
or to automatically shut the system down if turbidity levels exceed a
specified performance level.
If systems with 2 or fewer filters is allowed to sample
combined filter effluent in lieu of individual filter effluent with a
frequency of a reading every hour and combined filter effluent
turbidity exceeds 0.5 NTU, should the system be required to take grab
samples of individual filter turbidity for all filters every 15 minutes
until the results of those samples are lower than 0.5 NTU?
Reliability
Maintaining reliable performance at systems using filtration
requires that the filters be examined at intervals to determine if
problems are developing. This can mean that a filter must go off-line
for replacement or upgrades of media, underdrains, backwash lines etc.
In order to provide adequate public health protection at small systems,
the lack of duplicate units can be a problem. EPA is considering
requiring any system with only one filter to install an additional
filter. The schedule would be set by the primacy agency, but the filter
would have to be installed no later than 6 years after promulgation.
EPA is requesting comment on this potential requirement.
Data Gathering Recordkeeping and Reporting
The Agency is evaluating data gathering/reporting requirements for
systems. A system collecting data at a frequency of once every 15
minutes, (and operating) 24 hours a day, would record approximately
2800 data points for each filter throughout the course of the month.
Although the smallest systems in operation today routinely operate on
the average of 4 to 12 hours a day (resulting in 480 to 1400 data
points per filter), these systems do not typically use sophisticated
data recording systems such as SCADAs. The lack of modern equipment at
small systems may result in difficulty with retrieving and analyzing
data for reporting purposes. While the Agency intends to issue guidance
targeted at aiding these systems with the data gathering requirements,
EPA is also seeking feedback on a modification to the frequency of data
gathering required under each of the aforementioned options.
Specifically, the Agency would like to request comment on modifying the
frequency for systems serving fewer than 3,300 to continuous monitoring
on a 30 or 60 minute basis. EPA also requests comment on the
availability and practicality of data systems that would allow small
systems, State inspectors, and technical assistance providers to use
individual filter turbidity data to improve performance, perform filter
analysis, conduct individual filter self assessments, etc. The Agency
is interested in specific practical combinations of data recorders,
charts, hand written recordings from turbidimeters, that would
accomplish this.
Failure of Continuous Turbidity Monitoring
Under today's proposed rule, the Agency requires that if there is a
failure in the continuous turbidity monitoring equipment, the system
must conduct grab sampling every four hours in lieu of continuous
monitoring until the turbidimeter is back on-line. A system has five
working days to resume continuous monitoring before a violation is
incurred. EPA would like to solicit comment on modifying this component
to require systems to take grab samples at an increased frequency,
specifically every 30 minutes, 1 hour, or 2 hours.
B. Disinfection Benchmarking Requirements
Small systems will be required to comply with the Stage 1
Disinfection Byproduct Rule (Stage 1 DBPR) in the first calendar
quarter of 2004. The Stage 1 DBPR set Maximum Contaminant Levels (MCLs)
for Total Trihalomethanes (chloroform, bromodichloromethane,
chlorodibromomethane, and bromoform), and five Haloacetic Acids (i.e.,
the sum of the concentrations of mono-, di-, and trichloroacetic acids
and mono- and dibromoacetic acids.) The LT1FBR follows the principles
set forth in earlier FACA negotiations, i.e., that existing microbial
protection must not be significantly reduced or undercut as a result of
systems taking the necessary steps to comply with the MCL's for TTHM
and HAA5 set forth in Stage 1 DBPR. The disinfection benchmarking
requirements are designed to ensure that risk from one contaminant is
not increased while risk from another contaminant is decreased.
The Stage 1 DBPR was promulgated because disinfectants such as
chlorine can react with natural organic and inorganic matter in source
water and distribution systems to form disinfection byproducts (DBPs).
Results from toxicology studies have shown several DBPs (e.g.,
bromodichloromethane, bromoform, chloroform, dichloroacetic acid, and
bromate) to potentially cause cancer in laboratory animals. Other DBPs
(e.g., certain haloacetic acids) have been shown to cause adverse
reproductive or developmental effects in laboratory animals. Concern
about these health effects may cause public water utilities to consider
altering their disinfection practices to minimize health risks to
consumers.
A fundamental principle, therefore, of the 1992-1993 regulatory
negotiation reflected in the 1994 proposal for the IESWTR was that new
standards for control of DBPs must not result in significant increases
in microbial risk. This principle was also one of the underlying
premises of the 1997 M-DBP Advisory Committee's deliberations, i.e.,
that existing microbial protection must not be significantly reduced or
undercut as a result of systems taking the necessary steps to comply
with the MCL's for TTHM and HAA5 set forth in Stage 1 DBPR. The
Advisory Committee reached agreement on the use of microbial profiling
and benchmarking as a process by which a PWS and the State, working
together, could assure that there would be no significant reduction in
microbial protection as the result of modifying disinfection practices
in order to comply with Stage 1 DBPR.
The process established under the IESWTR has three components: (1)
Applicability Monitoring; (2) Disinfection Profiling; and (3)
Disinfection Benchmarking. These components have the following three
goals respectively: (1) determine which systems have annual average
TTHM and HAA5 levels close enough to the MCL (e.g., 80 percent of the
MCL) that they may need to consider altering their disinfection
practices to comply with Stage 1 DBPR; (2) those systems that have TTHM
and HAA5 levels of at least 80 percent of the MCLs must develop a
baseline of current microbial inactivation over the period of 1 year;
and (3) determine the benchmark, or the month with the lowest average
level of microbial inactivation, which becomes the critical period for
that year.
The aforementioned components were applied to systems serving
10,000 or more people in the IESWTR and were carried out sequentially.
In response to concerns about early implementation (any requirement
which would require action prior to 2 years after the promulgation date
of the rule), the Agency is considering modifying the IESWTR approach
for small systems, as described in the following section. Additionally,
the specific provisions have been modified to take into account
[[Page 19087]]
specific needs of small systems. EPA's goal in developing these
requirements is to recognize the specific needs of small system and
States, while providing small systems with a useful means of ensuring
that existing microbial protection must not be significantly reduced or
undercut as a result of systems taking the necessary steps to comply
with the MCL's for TTHM and HAA5 set forth in Stage 1 DBPR.
The description of the disinfection benchmarking components of
today's proposed rule will be broken into the three segments: (1)
Applicability Monitoring; (2) Disinfection Profiling; and (3)
Disinfection Benchmarking. Each section will provide an overview and
purpose, data, a description of the proposed requirements, and request
for comment.
1. Applicability Monitoring
a. Overview and Purpose
The purpose of the TTHM and HAA5 applicability monitoring is to
serve as an indicator for systems that are likely to consider making
changes to their disinfection practices in order to comply with the
Stage 1 DBPR. TTHM samples which equal or exceed 0.064 mg/L and/or HAA5
samples equal or exceed 0.048 mg/L (80 percent of their respective
MCLs) represent DBP levels of concern. Systems with TTHM or HAA5 levels
exceeding 80 percent of the respective MCLs may consider changing their
disinfection practice in order to comply with the Stage 1 DBPR.
b. Data
In 1987, EPA established monitoring requirements for 51 unregulated
synthetic organic chemicals. Subsequently, an additional 113
unregulated contaminants were added to the monitoring requirements.
Information on TTHMs has become available from the first round of
monitoring conducted by systems serving fewer than 10,000 people.
Preliminary analysis of the data from the Unregulated Contaminant
Information System (URCIS, Data) suggest that roughly 12 percent of
systems serving fewer than 10,000 would exceed 64 /L or 80
percent of the MCL for TTHM (Table IV.7). This number is presented only
as an indicator, as it represents samples taken at the entrance to
distribution systems. In general, TTHMs and HAA5s tend to increase with
time as water travels through the distribution system. The Stage 1
Disinfection Byproducts Rule estimated 20 percent of systems serving
fewer than 10,000 would exceed 80 percent of the MCLs for either TTHMs
or HAA5s or both. EPA is working to improve the knowledge of TTHM and
HAA5 formation kinetics in the distribution systems for systems serving
fewer than 10,000 people. EPA is currently developing a model to
predict the formation of TTHM and HAA5 in the distribution system based
on operational measurements. This model is not yet available. In order
to develop a better estimate of the percent of small systems that would
be triggered into the profiling requirements (i.e., develop a profile
of microbial inactivation over a period of 1 year) EPA is considering
the following method:
Use URCIS data to show how many systems serving 10,000 or
more people have TTHM levels at or above 0.064 mg/L;
Compare those values to the data received from the
Information Collection Rule for TTHM average values taken at
representative points in the distribution system;
Determine the mathematical factor by which the two values
differ; and
Apply that factor to the URCIS data for systems serving
fewer than 10,000 people to estimate the percent of those systems that
would have TTHM values at or above 0.064mg/L as an average of values
taken at representative points in the distribution system.
Table IV.7.--TTHM Levels at Small Surface Systems
[Data from Unregulated Contaminant Database, 1987-92 \1\]
------------------------------------------------------------------------
Number of
systems w/
ave. TTHM Maximum
Total level of
System size (population served) number of 64 g/L (80 (g/
% of MCL) L)
------------------------------------------------------------------------
500............................. 74 0 (0%) 56
501-1,000....................... 44 6 (13.6%) 222
1,001-3,300..................... 114 12 (10.5%) 172
3,301-10,000.................... 116 25 (21.6%) 279
---------------------------------------
Total....................... 348 43 (12.4%) 279
------------------------------------------------------------------------
\1\ In Unregulated Contaminant Database (1987-1992), there are ten
States (i.e., CA, DE, IN, MD, MI, MO, NC, NY, PR, WV). However, only
eight of them can be identified with the data of both population and
TTHM for systems serving fewer than 10,000 people (See next page).
The Agency requests comment on this approach to estimating TTHM
levels in the distribution system based on TTHM levels at the entry
point to the distribution system. The Agency also requests comment on
the relationship of HAA5 formation relative to TTHM formation in the
distribution system. Specifically, is there data to support the
hypothesis that HAA5s do not peak at the same point in the distribution
system as TTHMs?
The Agency also received two full years of TTHM data for seventy-
four systems in the State of Missouri (Missouri, 1998). This data
consisted of quarterly TTHM data, which was converted into an annual
average. The data (presented in Table IV.8) demonstrates a very
different picture than that displayed by the URCIS data described
above. In 1996, 88 percent of the systems exceeded 64 g/L,
while in 1997, 85 percent exceeded 64 g/L. Figure IV.7
graphically displays this data set.
[[Page 19088]]
Table IV.8.--TTHM Levels at Small Surface Systems in the State of
Missouri
[State of Missouri, 1996, 1997]
------------------------------------------------------------------------
Number of
systems w/
ave. TTHM Maximum
Total Level of
Year number of 64 g/L (80 (g/
percent of L)
MCL)
------------------------------------------------------------------------
1996............................ 74 65 (88%) 276
1997............................ 75 64 (85%) 251
All years....................... 149 129 (87%) 276
------------------------------------------------------------------------
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There are several potential reasons for the differences between the
data shown in Tables IV.7 and IV.8. Data in Table IV.7 contains zero
values which may be indicative of no sample being taken rather than a
sample with a value of zero. Additionally, data shown in IV.8 was
collected within the distribution system, while data in Table IV.7 was
taken at the entry point to the distribution system. The data
collection method used in collecting the data
[[Page 19090]]
shown in Table IV.8 is similar to the methodology required under the
Stage 1 DBPR.
c. Proposed Requirements
EPA considered four alternatives for systems to use TTHM and HAA5
data to determine which systems whether they would be required to
develop a disinfection profile. In today's proposed rule, EPA is
proposing Alternative 4.
Alternative 1
The IESWTR required that systems monitor for TTHMs at four points
in the distribution system each quarter. At least one of those samples
must be taken at a point which represents the maximum residence time of
the water in the system. The remaining three must be taken at
representative locations in the distribution system, taking into
account number of persons served, different sources of water and
different treatment methods employed. The results of all analyses per
quarter are averaged and reported to the State.
EPA considered applying this alternative to systems serving fewer
than 10,000 people and requested input from small system operators and
other interested parties, including the public. Based on the feedback
EPA received, two other alternatives were developed for consideration
(listed as Alternatives 2 and 3).
Alternative 2
EPA considered requiring systems serving fewer than 10,000 people
to monitor for TTHM and HAA5 at the point of maximum residence time
according to the following schedule:
No less than once per quarter per treatment plant operated
for systems serving populations between 500 and 10,000 persons; and no
less than once per year per treatment plant during the month of warmest
water temperature for systems serving populations less than 500. If
systems wish to take additional samples, however, they would be
permitted to do so.
Systems may consult with States and elect not to perform
TTHM and HAA5 monitoring and proceed directly with the development of a
disinfection profile.
This alternative provides an applicability monitoring frequency
identical to the DBP monitoring frequency under the Stage 1 DBPR that
systems will have to comply with in 2004. In addition, it allows
systems the flexibility to skip TTHM and HAA5 monitoring completely,
pending State approval, and begin profiling immediately.
Alternative 3
EPA considered requiring all systems serving fewer than 10,000
people to monitor once per year per system during the month of warmest
water temperature of 2002 and at the point of maximum residence time.
During the SBREFA process and during stakeholder meetings, EPA
received some positive comments regarding Alternative 3 as the least
burdensome approach. Other stakeholders, however, pointed out that
Alternative 3 does not allow systems to measure seasonal variation as
is done in Alternative 2 for systems serving populations between 500
and 10,000. Several stakeholders agreed that despite the costs, the
information obtained from applicability monitoring will be useful. EPA
agrees that it is valuable to systems to monitor and understand the
seasonal variation in TTHM and HAA5 values, however, EPA has determined
that requiring a full year of monitoring may place an excessive burden
on both States and systems. In order to complete a full year of
monitoring and another full year of disinfection data gathering,
systems would have to start TTHM and HAA5 monitoring January of 2002.
Under SDWA, States have two years to develop their own regulations
as part of their primacy requirements, EPA recognized that requiring
Applicability Monitoring during this period would pose a burden on
States. In response to these concerns, the Agency developed a new
alternative, described in the following paragraph.
Alternative 4
Applicability Monitoring is optional and not a requirement under
today's proposed rule. If a system has TTHM and HAA5 data taken during
the month of warmest water temperature (from 1998-2002) and taken at
the point of maximum residence time, they may submit this data to the
State prior to [DATE 2 YEARS AFTER PUBLICATION OF FINAL RULE]. If the
data shows TTHM and HAA5 levels less than 80 percent of the MCLs, the
system does not have to develop a disinfection profile. If the data
shows TTHM and HAA5 levels at or above 80 percent of the MCLs, the
system would be required to develop a disinfection profile in 2003 as
described later in section IV.B.2. If the system does not have, or does
not gather TTHM and HAA5 data during the month of warmest water
temperature and at the point of maximum residence time in the
distribution system as described, then the system would automatically
be required to develop a disinfection profile starting January 1 of
2003. This option still provides systems with the necessary tools for
assessing potential changes to their disinfection practice, (i.e. the
generation of the profile), while not forcing States to pass their
primacy regulations, contact all small systems within their
jurisdiction, and set up TTHM and HAA5 monitoring all within the first
year after promulgation of this rule. Systems will still be able to
ensure public health protection by having the disinfection profile when
monitoring under Stage 1 DBPR takes effect. It should be noted that EPA
estimates the cost for applicability monitoring (as described in
Alternative 4) and disinfection profiling (as described in Alternative
3 in Section IV.B.2.c of this preamble) are roughly equivalent. EPA
anticipates that systems with known low levels of TOC may opt to
conduct the applicability monitoring while the remaining systems will
develop a disinfection profile.
d. Request for Comment
EPA requests comment on the proposed requirement, other
alternatives listed, or other alternatives that have not yet been
raised for consideration. The Agency also requests comment on
approaches for determining the percent of systems that would be
affected by this requirement. Specifically:
With respect to Alternative 4, the Agency requests comment
on approaches for determining the percent of systems that might
demonstrate TTHM and HAA5 levels less than 80 percent of their
respective MCLs and would therefore not develop a disinfection profile.
The Agency requests additional information (similar to the
State of Missouri data discussed previously) on the current levels of
TTHM and HAA5s in the distribution systems of systems serving fewer
than 10,000 people.
The Agency requests comment on developing a TTHM and HAA5
monitoring scheme during the winter months as opposed to the current
monitoring scheme based on the highest TTHM/HAA5 formation potential
during the month of warmest water temperature. If a relationship can be
established, and shown to be consistent through geographical
variations, EPA would consider modifying an alternative so that
applicability monitoring would occur during the 1st quarter of 2003.
The Agency requests comment on modifying Alternative 3, to
require systems to begin monitor for TTHMs and HAA5s during the warmest
water temperature month of 2003. The results of this monitoring would
be used to
[[Page 19091]]
determine whether a system would need to develop a disinfection profile
during 2004. This option is closer in structure and timing to the
IESWTR and has been included for comment. It should be noted, however,
that postponing the disinfection profile until 2004 would prevent
systems from having inactivation data prior to their compliance date
with the Stage 1 DBPR, possibly compromising simultaneous compliance.
2. Disinfection Profiling
a. Overview and Purpose
The disinfection profile is a graphical representation showing how
disinfection varies at a given plant over time. The profile gives the
plant operator an idea of how seasonal changes in water quality and
water demand can have a direct effect on the level of disinfection the
plant is achieving.
The strategy of disinfection profiling and benchmarking stemmed
from data provided to the EPA and M-DBP Advisory Committee by PWSs and
reviewed by stakeholders. The microbial inactivation data (expressed as
logs of Giardia lamblia inactivation) used by the M-DBP Advisory
Committee demonstrated high variability. Inactivation varied by several
log on a day-to-day basis at any particular treatment plant and by as
much as tens of logs over a year due to changes in water temperature,
flow rate (and, consequently, contact time), seasonal changes in
residual disinfectant, pH, and disinfectant demand and, consequently,
disinfectant residual. There were also differences between years at
individual plants. To address these variations, M-DBP stakeholders
developed the procedure of profiling inactivation levels at an
individual plant over a period of at least one year, and then
establishing a benchmark of minimum inactivation as a way to
characterize disinfection practice. This approach makes it possible for
a plant that may need to change its disinfection practice in order to
meet DBP MCLs to determine the impact the change would have on its
current level of disinfection or inactivation and, thereby, to assure
that there is no significant increase in microbial risk. In order to
develop the profile, a system must measure four parameters (EPA is
assuming most small systems use chlorine as their disinfection agent,
and these requirements are based on this assumption):
(1) Disinfectant residual concentration (C, in mg/L) before or at
the first customer and just prior to each additional point of
disinfectant addition;
(2) Contact time (T, in minutes) during peak flow conditions;
(3) Water temperature ( deg.C); and
(4) pH.
Systems convert this operational data to a number representing log
inactivation values for Giardia by using tables provided by EPA.
Systems graph this information over time to develop a profile of their
microbial inactivation. EPA will prepare guidance specifically
developed for small systems to assist in the development of the
disinfection profile. Several spreadsheets and simple programs are
currently available to aid in calculating microbial inactivation and
the Agency intends to make such spreadsheets available in guidance.
b. Data
Figure IV.8a depicts a hypothetical disinfection profile showing
seasonal variation in microbial inactivation.
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[[Page 19093]]
c. Proposed Requirements
EPA considered four alternatives for requiring systems to develop
the disinfection profile.
Alternative 1
The IESWTR requires systems serving 10,000 or more persons to
measure the four parameters described above and develop a profile of
microbial inactivation on a daily basis. EPA considered extending this
requirement to systems serving fewer than 10,000 persons and requested
input from small system operators and other interested stakeholders
including the public. EPA received feedback that this requirement would
place too heavy of a burden on the small system operator for at least
two reasons:
Small system operators are not present at the plant every
day; and
Small systems often have only one operator at a plant who
is responsible for all aspects of maintenance, monitoring and
operation.
Alternative 2
EPA also considered not requiring the disinfection profile at all.
After consideration of the feedback of small system operators and other
interested stakeholders, however, EPA believes that there is a strong
benefit in the plant operator knowing the level of microbial
inactivation, and that the principles developed during the regulation
negotiation and Federal Advisory Committee prior to promulgation of the
IESWTR could be applied to small systems for the purpose of public
health protection. Recognizing the potential burdens the profiling
procedures placed on small systems, EPA considered two additional
alternatives.
Alternative 3
EPA considered requiring all systems serving fewer than 10,000
persons, to develop a disinfection profile based on weekly measurements
for one year during or prior to 2003. A system with TTHM and HAA5
levels less than 80 percent of the MCLs (based on either required or
optional monitoring as described in section IV.B.1) would not be
required to conduct disinfection profiling. EPA believes this
alternative would save the operator time (in comparison to Alternative
1), and still provide information on seasonal variation over the period
of one year.
Alternative 4
Finally, EPA considered a monitoring requirement only during a one
month critical monitoring period to be determined by the State. In
general, colder temperatures reduce disinfection efficiency. For
systems in warmer climates, or climates that do not change very much
during the course of the year, the State would identify other critical
periods or conditions. This alternative reduces the number of times the
operator has to calculate the microbial inactivation.
EPA considered all of the above alternatives, and in today's
proposed rule, EPA is proposing Alternative 3. First, this alternative
does not require systems to begin monitoring before States have two
years to develop their regulations as part of primacy requirements.
Given early implementation concerns, the timing of this alternative
appears to be the most appropriate in balancing early implementation
issues with the need for systems to prepare for implementation of the
Stage 1 DBPR and ensuring adequate and effective microbial protection.
Second, it allows systems and States which have been proactive in
conducting applicability monitoring to reduce costs for those systems
which can demonstrate low TTHM and HAA5 levels. Third, this alternative
allows systems and States the opportunity to understand seasonal
variability in microbial disinfection. Finally, this alternative takes
into account the flexibility needed by the smallest systems while
maintaining comparable levels of public health protection with the
larger systems.
Request for Comments
EPA requests comment on this proposed requirement as well as
Alternatives 1,2, and 4. The Agency also requests comment on a possible
modification to Alternatives 1, 3 and 4. Under this modification,
systems serving populations fewer than 500 would have the opportunity
to apply to the State to perform the weekly inactivation calculation
(although data weekly data collection would still be required). If the
system decided to make a change in disinfection practice, then the
State would assist the system with the development of the disinfection
profile.
The Agency also requests comment on a modification to Alternative 3
which would require systems to develop a disinfection profile in 2004
only if Applicability Monitoring conducted in 2003 indicated TTHM and
HAA5 levels of 80 percent or greater of the MCL. This modification
would be coupled with the applicability monitoring modification
discussed in the previous section.
3. Disinfection Benchmarking
a. Overview and Purpose
The DBPR requires systems to meet lower MCLs for a number of
disinfection byproducts. In order to meet these requirements, many
systems will require changes to their current disinfection practices.
In order to ensure that current microbial inactivation does not fall
below those levels required for adequate Giardia and virus inactivation
as required by the SWTR, a disinfection benchmark is necessary. A
disinfection benchmark represents the lowest average monthly Giardia
inactivation level achieved by a system. Using this benchmark States
and systems can begin to understand the current inactivation achieved
at the system, and estimate how changes to disinfection practices will
affect inactivation.
b. Data
Based on the hypothetical disinfection profile depicted in Figure
IV.8a, the benchmark, or critical period, is the lowest level of
inactivation achieved by the system over the course of the year. Figure
IV.8b shows that this benchmark (denoted by the dotted line) takes
place in December for the hypothetical system.
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c. Proposed Requirements
If a system that is required to produce a disinfection profile
decides to make a significant change in disinfection practice after the
profile is developed, it must consult with the State and receive
approval before implementing such a change. Significant changes in
disinfection practice are defined as: (1) moving the point of
disinfection (other than routine seasonal changes already approved by
the State); (2) changing the type of disinfectant; (3) changing the
disinfection process; or (4) making other modifications designated as
significant by the State. Supporting materials for such consultation
with the State must include a description of the proposed change, the
disinfection profile developed under today's proposed rule for Giardia
lamblia (and, if necessary, viruses for systems using ozone or
chloramines), and an analysis of how the proposed change might affect
the current level of Giardia inactivation. In addition, the State is
required to review disinfection profiles as part of its periodic
sanitary survey.
A log inactivation benchmark is calculated as follows:
(1) Calculate the average log inactivation for either each calendar
month, or critical monitoring period (depending on final rule
requirement for the profiling provisions).
(2) Determine the calendar month with the lowest average log
inactivation; or lowest inactivation level within the critical
monitoring period.
(3) The lowest average month, or lowest level during the critical
monitoring period becomes the critical measurement for that year.
(4) If acceptable data from multiple years are available, the
average of critical periods for each year becomes the benchmark.
(5) If only one year of data is available, the critical period
(lowest monthly average inactivation level) for that year is the
benchmark.
d. Request for Comments
EPA has included a requirement that State approval be obtained
prior to making a significant change to disinfection practice. EPA
requests comment on whether the rule should require State approval or
whether only state consultation is necessary.
EPA also requests comment on providing systems serving fewer than
500 the option to provide raw data to the State, and allowing the State
to determine the benchmark.
C. Additional Requirements
1. Inclusion of Cryptosporidium in definition of GWUDI
a. Overview and Purpose
Groundwater sources are found to be under the direct influence of
surface water (GWUDI) if they exhibit specific traits. The SWTR defined
ground waters containing Giardia lamblia as GWUDI. One such trait is
the presence of protozoa such as Giardia which migrate from surface
water to groundwater. The IESWTR expanded the SWTR's definition of
GWUDI to include the presence of Cryptosporidium. The Agency believes
it appropriate and necessary to extend this modification of the
definition of GWUDI to systems serving fewer than 10,000 persons.
b. Data
The Agency issued guidance on the Microscopic Particulate Analysis
(MPA) in October 1992 as the Consensus Method for Determining
Groundwater Under the Direct Influence of Surface Water Using
Microscopic Particulate Analysis (EPA, 1992). Additional guidance for
making GWUDI determinations is also available (USEPA, 1994a,b). Since
1990, States have acquired substantial experience in making GWUDI
determinations and have documented their approaches (Massachusetts
Department of Environmental Protection, 1993; Maryland, 1993; Sonoma
County Water Agency, 1991). Guidance on existing practices undertaken
by States in response to the SWTR may also be found in the State
Sanitary Survey Resource Directory, jointly published in December 1995
by EPA and the Association of State Drinking Water Administrators (EPA/
ASDWA). AWWARF has also published guidance (Wilson et al., 1996).
Most recently, Hancock et al. (1997) used the MPA test to study the
occurrence of Giardia and Cryptosporidium in the subsurface. They found
that, in a study of 383 ground water samples, the presence of Giardia
correlated with the presence of Cryptosporidium. The presence of both
pathogens correlated with the amount of sample examined, but not with
the month of sampling. There was a correlation between source depth and
occurrence of Giardia but not Cryptosporidium. The investigators also
found no correlation between the distance of the ground water source
from adjacent surface water and the occurrence of either Giardia or
Cryptosporidium. However, they did find a correlation between distance
from a surface water source and generalized MPA risk ratings of high
(high represents an MPA score of 20 or greater), medium or low, but no
correlation was found with the specific numerical values that are
calculated by the MPA scoring system. An additional two reports (SAIC
1997a and 1997b) provide data on wells with Giardia cyst and
Cryptosporidium oocyst recovery and concurrent MPA analysis.
c. Proposed Requirements
In today's proposed rule, EPA is modifying the definition of GWUDI
to include Cryptosporidium for systems serving fewer than 10,000
persons.
Under the SWTR, States were required to determine whether systems
using ground water were using ground water under the direct influence
of surface water (GWUDI). State determinations were required to be
completed by June 29, 1994 for CWSs and by June 29, 1999 for NCWSs. EPA
does not believe that it is necessary to make a new determination of
GWUDI for this rule based on the addition of Cryptosporidium to the
definition of ``ground water under the direct influence of surface
water''. While a new determination is not required, States may elect to
conduct a new analysis based on such factors as a new land use pattern
(conversion to dairy farming, addition of septic tanks).
EPA does not believe that a new determination is necessary because
the current screening methods appear to adequately address the
possibility of Cryptosporidium in the ground water.
d. Request for Comments
The Agency requests comment on the proposal to modify the
definition of GWUDI to include Cryptosporidium for systems serving
fewer than 10,000 persons.
2. Inclusion of Cryptosporidium Watershed Requirements for Unfiltered
Systems
a. Overview and Purpose
Existing SWTR requirements for unfiltered surface water and GWUDI
systems require these systems to minimize the potential for source
water contamination by Giardia lamblia and viruses. Because
Cryptosporidium has proven resistant to levels of disinfection
currently practiced at systems throughout the country, the Agency felt
it imperative to include Cryptosporidium in the watershed control
provisions wherever Giardia lamblia is mentioned. The IESWTR therefore,
modified existing watershed regulatory requirements for unfiltered
systems to include the control of
[[Page 19096]]
Cryptosporidium. The Agency believes it appropriate and necessary to
extend this requirement to systems serving fewer than 10,000 persons.
It should be noted that today's proposed requirements do not
replace requirements established for unfiltered systems under the SWTR.
Systems must continue to maintain compliance with the requirements of
the SWTR for avoidance of filtration. If an unfiltered system fails any
of the avoidance criteria, that system must install filtration within
18 months, regardless of future compliance with avoidance criteria.
EPA anticipates that in the planned Long Term 2 Enhanced Surface
Water Treatment rule, the Agency will reevaluate treatment requirements
necessary to manage risks posed by Cryptosporidium and other microbial
pathogens in both filtered and unfiltered surface water systems. In
conducting this reevaluation, EPA will utilize the results of several
large surveys, including the Information Collection Rule (ICR) and ICR
Supplemental Surveys, to more fully characterize the occurrence of
waterborne pathogens, as well as watershed and water quality parameters
which might serve as indicators of pathogen risk level. The LT2ESWTR
will also incorporate the results of ongoing research on removal and
inactivation efficiencies of treatment processes, as well as studies of
pathogen health effects and disease transmission. Promulgation of the
LT2ESWTR is currently scheduled for May, 2002.
b. Data
Watershed control requirements were initially established in 1989
(54 FR 27496, June 29, 1989) (EPA, 1989b), as one of a number of
preconditions that a public water system using surface water must meet
to avoid filtration. The SWTR specifies the conditions under which a
system can avoid filtration (40 CFR 141.71). These conditions include
good source water quality, as measured by concentrations of coliforms
and turbidity; disinfection requirements; watershed control; periodic
on-site inspections; the absence of waterborne disease outbreaks; and
compliance with the Total Coliform Rule and the MCL for TTHMs. The
watershed control program under the SWTR must include a
characterization of the watershed hydrology characteristics, land
ownership, and activities which may have an adverse effect on source
water quality, and must minimize the potential for source water
contamination by Giardia lamblia and viruses.
The SWTR Guidance Manual (EPA, 1991a) identifies both natural and
human-caused sources of contamination to be controlled. These sources
include wild animal populations, wastewater treatment plants, grazing
animals, feedlots, and recreational activities. The SWTR Guidance
Manual recommends that grazing and sewage discharges not be permitted
within the watershed of unfiltered systems, but indicates that these
activities may be permissible on a case-by-case basis where there is a
long detention time and a high degree of dilution between the point of
activity and the water intake. Although there are no specific
monitoring requirements in the watershed protection program, the non-
filtering utility is required to develop State-approved techniques to
eliminate or minimize the impact of identified point and non-point
sources of pathogenic contamination. The guidance already suggests
identifying sources of microbial contamination, other than Giardia,
transmitted by animals, and points out specifically that
Cryptosporidium may be present if there is grazing in the watershed.
c. Proposed Requirements
In today's proposed rule, EPA is extending the existing watershed
control regulatory requirements for unfiltered systems serving fewer
than 10,000 people to include the control of Cryptosporidium.
Cryptosporidium will be included in the watershed control provisions
for these systems wherever Giardia lamblia is mentioned.
Specifically, the public water system must maintain a watershed
control program which minimizes the potential for contamination by
Giardia lamblia, and Cryptosporidium oocysts and viruses in the water.
The State must determine whether the watershed control program is
adequate to meet this goal. The adequacy of a program to limit
potential contamination by Giardia lamblia cysts, Cryptosporidium
oocysts and viruses must be based on: The comprehensiveness of the
watershed review; the effectiveness of the system's program to monitor
and control detrimental activities occurring in the watershed; and the
extent to which the water system has maximized land ownership and/or
controlled land use within the watershed.
It should be noted that unfiltered systems must continue to
maintain compliance with the requirements of the SWTR for avoidance of
filtration. If an unfiltered system fails any of the avoidance
criteria, that system must install filtration within 18 months,
regardless of future compliance with avoidance criteria.
d. Request for Comments
EPA requests comment on the inclusion of these requirements for
unfiltered systems serving fewer than 10,000 people.
3. Requirements for Covering New Reservoirs
a. Overview and Purpose
Open finished water reservoirs, holding tanks, and storage tanks
are utilized by public water systems throughout the country. Because
these reservoirs are open to the environment and outside influences,
they can be subject to the reintroduction of contaminants which the
treatment plant was designed to remove. The IESWTR contains a
requirement that all newly constructed finished water reservoirs,
holding tanks, and storage tanks be covered. The Agency believes it
appropriate and necessary to extend this requirement to systems serving
fewer than 10,000 people.
b. Data
Existing EPA guidelines recommend that all finished water
reservoirs and storage tanks be covered (EPA, 1991b). The American
Water Works Association (AWWA) also has issued a policy statement
strongly supporting the covering of reservoirs that store potable water
(AWWA, 1993). In addition, a survey of nine States was conducted in the
summer of 1996 (Montgomery Watson, 1996). The States which were
surveyed included several in the West (Oregon, Washington, California,
Idaho, Arizona, and Utah), two States in the East known to have water
systems with open reservoirs (New York and New Jersey), and one
midwestern State (Wisconsin). Seven of the nine States which were
surveyed require by direct rule that all new finished water reservoirs
and tanks be covered.
Under the IESWTR, systems serving populations of 10,000 or greater
were prohibited from constructing uncovered finished water reservoirs
after February 16, 1999. The Agency developed an Uncovered Finished
Water Reservoirs Guidance Manual (USEPA, 1999f) which provides a basic
understanding of the potential sources of external contamination in
uncovered finished water reservoirs. It also provides guidance to water
treatment operators for evaluating and maintaining water quality in
reservoirs. The document discusses:
Existing regulations and policies pertaining to uncovered
reservoirs;
Development of a reservoir management plan;
[[Page 19097]]
Potential sources of water quality degradation and
contamination;
Operation and maintenance of reservoirs to maintain water
quality; and
Mitigating potential water quality degradation.
As discussed in the 1997 IESWTR NODA (EPA, 1997b), when a finished
water reservoir is open to the atmosphere it may be subject to some of
the environmental factors that surface water is subject to, depending
upon site-specific characteristics and the extent of protection
provided. Potential sources of contamination to uncovered reservoirs
and tanks include airborne chemicals, surface water runoff, animal
carcasses, animal or bird droppings and growth of algae and other
aquatic organisms due to sunlight that results in biomass (Bailey and
Lippy, 1978). In addition, uncovered reservoirs may be subject to
contamination by persons tossing items into the reservoir or illegal
swimming (Pluntze 1974; Erb, 1989). Increases in algal cells,
heterotrophic plate count (HPC) bacteria, turbidity, color, particle
counts, biomass and decreases in chlorine residuals have been reported
(Pluntze, 1974, AWWA Committee Report, 1983, Silverman et al., 1983,
LeChevallier et al. 1997a).
Small mammals, birds, fish, and the growth of algae may contribute
to the microbial degradation of an open finished water reservoir
(Graczyk et al., 1996a; Geldreich, 1990; Fayer and Ungar, 1986;). In
one study, sea gulls contaminated a 10 million gallon reservoir and
increased bacteriological growth, and in another study waterfowl were
found to elevate coliform levels in small recreational lakes by twenty
times their normal levels (Morra, 1979). Algal growth increases the
biomass in the reservoir, which reduces dissolved oxygen and thereby
increases the release of iron, manganese, and nutrients from the
sediments. This, in turn, supports more growth (Cooke and Carlson,
1989). In addition, algae can cause drinking water taste and odor
problems as well as impact water treatment processes. A 1997 study
conducted by the City of Seattle (Seattle Public Utilities, 1997)
evaluated nutrient loadings by three groups of birds at Seattle's open
reservoirs. Table IV.9 indicated the amount of soluble nutrient
loadings estimated over the course of the year. It shows that bird
feces may contribute nutrient loadings that can enhance algal growth in
the reservoir.
Table IV.9.--1997 Nutrient Loadings by Bird Groups in Seattle's Open Reservoirs
--------------------------------------------------------------------------------------------------------------------------------------------------------
Geese Gulls Ducks Overall
---------------------------------------------------------------------------------------
Reservoir Nitr. kg/ Phos. kg/ Nitr. kg/ Phos. kg/ Nitr. kg/ Phos. kg/ Total kg/ Conc. (mg/
yr yr yr yr yr yr yr L)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Beacon Hill*.................................................... 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Bitter Lake..................................................... 0.82 0.24 0.01 0.00 0.06 0.02 1.15 14.09
Green Lake...................................................... 1.78 0.52 0.03 0.01 0.53 0.16 3.04 16.05
Lake Forest..................................................... 2.23 0.65 0.36 0.11 0.07 0.02 3.43 15.09
Lincoln......................................................... 0.00 0.00 0.24 0.07 0.01 0.00 0.31 3.96
Maple Leaf...................................................... 2.16 0.63 0.13 0.04 0.35 0.10 3.42 15.43
Myrtle.......................................................... 0.00 0.00 0.08 0.02 0.01 0.00 0.12 4.35
Volunteer....................................................... 0.00 0.00 0.01 0.00 0.01 0.00 0.03 0.42
West Seattle.................................................... 0.40 0.12 0.38 0.11 0.02 0.01 1.03 4
--------------------------------------------------------------------------------------------------------------------------------------------------------
c. Proposed Requirements
In today's proposed rule EPA is requiring surface water and GWUDI
systems that serve fewer than 10,000 people to cover all new
reservoirs, holding tanks or other storage facilities for finished
water for which construction begins 60 days after the publication of
the final rule in the Federal Register. Today's proposed rule does not
apply these requirements to existing uncovered finished water
reservoirs.
d. Request for Comments
EPA solicits comments regarding the requirement to require that all
new reservoirs, holding tanks and storage facilities for finished water
be covered.
D. Recycle Provisions for Public Water Systems Employing Rapid Granular
Filtration Using Surface Water and GWUDI as a Source
Section 1412(b)(14) of the 1996 SDWA Amendments requires EPA to
promulgate a regulation to govern the recycle of filter backwash within
the treatment process of public water systems. The Agency is concerned
that the recycle of spent filter backwash and other recycle streams may
introduce additional Cryptosporidium oocysts to the treatment process.
Adding oocysts to the treatment process may increase the risk oocysts
will occur in finished water supplies and threaten public health. The
Agency is further concerned because Cryptosporidium is not inactivated
by standard disinfection practice, an important treatment barrier
employed to control microbial pathogens. Oocysts returned to the plant
by recycle flow therefore remain a threat to pass through filters into
the finished water.
The Agency engaged in three primary information gathering
activities to investigate the potential risk posed by returning recycle
flows that may contain Cryptosporidium to the treatment process. First,
the Agency performed a broad literature search to gather research
papers and information on the occurrence of Cryptosporidium and organic
and inorganic materials in recycle flows. The literature search also
sought information regarding the potential impact recycle may have on
plant treatment efficiency. Second, the Agency worked with AWWA,
AWWSCo., and Cincinnati Water Works to develop twelve issue papers on
commonly generated recycle flows (Environmental Engineering and
Technology, Inc.,1999). These papers are summarized in the next
section. Information from EPA's literature search was incorporated into
the issue papers. Third, the Agency presented preliminary data and
potential regulatory components to stakeholders, and solicited
feedback, at public meetings in Denver, Colorado, and Dallas, Texas.
EPA also received valuable input from representatives of small water
systems through the SBREFA process.
Through the above activities, the Agency has identified four
primary concerns regarding the recycle of spent filter backwash and
other recycle streams within the treatment process of PWSs. The first
concern is that some recycle flows contain Cryptosporidium oocysts,
frequently at higher concentrations than plant source waters. Recycling
these flows may increase the number of oocysts entering the plant and
the number of oocysts reaching the filters. Loading more oocysts to the
[[Page 19098]]
filters could increase finished water oocyst concentrations. The second
concern regards the location in the treatment process recycle flow is
returned. The return of recycle at the point of primary coagulant
addition or downstream of it may disrupt treatment chemistry by
introducing residual coagulant or other treatment chemicals to the
process stream and thereby lower plant treatment efficiency. Also,
recycle flow returned to the clarification process may not achieve
sufficient residence time for oocysts in the recycle flow to be
removed, or it may create hydraulic currents that lower the unit's
overall oocyst removal efficiency. The third concern regards direct
filtration plants. Direct filtration plants do not employ clarification
in their primary treatment process to remove suspended solids and
oocysts; all oocyst removal is achieved by the filters. If the recycle
flow is not treated before being returned to the plant, all of the
oocysts captured by a filter during a filter run will be returned to
the plant and again loaded to the filters. This may lead to ever
increasing levels of oocysts being applied to the filters and could
increase the concentration of oocysts in finished water. Therefore, it
is important for direct filtration plants to provide adequate recycle
flow treatment to remove oocysts and protect the integrity of the
filters and finished water quality. Finally, the fourth concern is that
the direct recycle of spent filter backwash without first providing
treatment, equalization, or some form of hydraulic detention for the
recycle flow, may cause plants to exceed State-approved operating
capacity during recycle events. This can cause clarification and filter
loading rates to be exceeded, which may lower overall oocyst removal
provided by the plant and increase finished water oocyst
concentrations.
EPA has particular concerns regarding the direct recycle of spent
filter backwash water as it is produced (i.e., recycle flow is not
retained in an equalization basin, treatment unit, or other hydraulic
detention unit prior to reintroduction to the main treatment process)
for the following reasons:
(1) Direct recycle may cause operating rates for clarification and
filtration to be exceeded, which may lower overall Cryptosporidium
removal;
(2) Direct recycle may hydraulically upset some plants, lowering
overall plant treatment performance, and;
(3) Clarification and filtration operating rates may be exceeded at
precisely the time recycle flow may be returning large numbers of
oocysts to the treatment process.
The impact of direct recycle practice to smaller plants with few
filters is of greatest concern because return of recycle flow can
double or triple plant influent flow, which may hydraulically overload
the plant and reduce oocyst removal.
Since standard disinfection practice does not inactivate
Cryptosporidium, its control is entirely dependent on physical removal
processes. The Agency is concerned that direct recycle may cause some
plants to exceed operating capacity and thus lower their physical
removal capabilities. This can increase the risk of oocysts entering
the finished water and lead to an increased risk to public health.
The limited data (Cornwell and Lee, 1993) EPA has identified
regarding plants with existing equalization and/or treatment indicates
they may be at no greater risk of hydraulic upset or degradation of
oocyst removal performance than non-recycle plants. Given current data
limitations, it is reasonable to assume the presence and utilization of
adequate recycle flow equalization and/or treatment processes will
alleviate the potential for hydraulic disruptions and the impairment of
treatment performance. Data suggesting otherwise is currently
unavailable.
The potential for recycle to return significant numbers of oocysts
to the treatment train does provide a general basis for concern
regarding the impact of recycle practice to finished water quality.
However, the Agency does not currently believe data warrants a national
regulation requiring all recycle plants to provide recycle flow
equalization or treatment for the following reasons:
(1) Data correlating oocyst occurrence in recycle streams to
increased oocyst occurrence in finished water is unavailable;
(2) Data regarding the response of full-scale plants to recycle
events is limited;
(3) Data is not available to determine the level of recycle flow
equalization or treatment full-scale systems may need, if any, to
control the risk of oocysts entering finished water, and;
(4) Whether and the extent to which oocyst occurrence in source
water influences the necessary level of recycle treatment and
equalization is unknown.
The Agency believes requiring plants that may be at greater risk
due to recycle, such as direct recycle plants and direct filtration
plants, to characterize their recycle practice and provide data to the
State for its review provides a cost effective opportunity to increase
public health protection and supply a measure of safety to finished
drinking water supplies. EPA believes that today's proposal will
address potentially higher risk recycle situations that may threaten
the performance of some systems, and will do so by allowing State
drinking water programs to consider site-specific treatment conditions
and needs. The Agency believes these recycle provisions are needed to
protect plant performance, the quality of finished water supplies, and
to provide an additional measure of public health protection.
1. Treatment Processes That Commonly Recycle and Recycle Flow
Occurrence Data
a. Treatment Processes That Commonly Recycle
The purpose of this section is to provide general background on
common treatment plant processes, fundamental plant operations, and the
origin of plant recycle streams. Detailed information on the specific
recycle flows these processes generate are presented after this
background discussion. Four general types of water treatment processes,
conventional filtration, direct filtration, softening, and contact
clarification, are discussed. Although there are numerous variations of
these four treatment processes, only the most basic configurations are
discussed here. The operation of package plants and options to
returning recycle to the treatment process are also summarized.
i. Conventional Treatment Plants
Conventional water filtration plants are defined by the use of four
essential unit processes: Rapid mix, coagulation/flocculation,
sedimentation, and filtration. Sedimentation employs gravity settling
to remove floc and particles. Particles not removed by sedimentation
may be removed by the filters. Periodically, accumulated solids must be
removed from the sedimentation unit. These solids, termed
``residuals,'' are currently disposed to sanitary sewer, treated with
gravity thickening, or some other process prior to returning them to
plant headworks or other locations in the treatment train.
Clarification processes other than sedimentation may also be used, and
they also produce process residuals.
Clarification sludge may be processed on-site if the plant is
equipped with solids treatment facilities. Commonly employed treatment
processes include thickeners, dewatering equipment (e.g., plate and
frame presses, belt filter presses, or centrifuges), and lagoons. Each
of these processes produces residual water streams that are currently
returned to the treatment process at the
[[Page 19099]]
headworks or other locations prior to filtration. The volume of
residuals produced by clarification depends upon the amount of solids
present in the raw water, the dose and type of coagulant applied, and
the concentration of solids in the treated water stream.
The one residual stream associated with filtration, spent filter
backwash water, is produced during periodic backwashing events
performed to remove accumulated solids from the filter. Spent filter
backwash is frequently returned to the treatment process at the head of
the plant, other locations prior to the filters, or disposed of to
sanitary sewer or surface water. Some plants have the capability to
send the filtrate produced during the filter ripening period to plant
headworks, a raw water reservoir, or to a sanitary sewer or surface
water rather than to the clear well as finished water. This practice,
referred to as ``filter-to-waste'' is used to prevent solids, which
pass through the filter more easily during the ripening period, from
entering the finished water.
Filter backwash operations can differ significantly from plant to
plant. The main variables are the time between backwashes (length of
filter run), the rate of backwash flow, the duration of the backwash
cycle, and the backwashing method. The time between filter backwashes
is generally a function of either run time, headloss, or solids
breakthrough. Both headloss and solids breakthrough can be dependent
upon the quality of the sedimentation effluent. Regardless of the
variable driving backwash frequency, the interval between backwashes
typically vary from 24 to 72 hours. Recommended backwash frequency is
every 24-48 hours (ASCE/AWWA, 1998).
There are a number of different methods that can be used to
backwash a filter. These include: Upflow water only, upflow water with
surface wash, and air/water backwash. Air/water backwash systems
typically use 30-50 percent less water than the other two methods. The
filter backwash flow rate can vary, depending on media type, water
temperature, and backwash method, but generally has a maximum of 15-23
gpm/ft\2\ (air/water backwash may have a lower maximum rate of 6-7 gpm/
ft\2\). A number of different backwash sequences are employed, but a
typical backwash consists of a low rate wash (6-7 gpm/ft\2\ for several
minutes), followed by a high rate wash (15-23 gpm/ft\2\ for 5-15
minutes), which is then followed by a final low rate wash (6-7 gpm/
ft\2\ for several additional minutes). Some treatment plants only use a
high rate wash for 15 to 30 minutes. Backwash rates are significantly
higher than filtration rates, which vary from 1 to 8 gpm/ft\2\.
ii. Direct Filtration Plants
The direct filtration process is similar to conventional treatment,
except the clarification process is not present. Direct filtration
plants produce the same filter residual as conventional filtration
plants, namely filter backwash, and may also generate a filter-to-waste
flow. Direct filtration plants do not produce clarification residuals
because clarification is not employed. Filter backwash may be either
recycled to the head of the plant or discharged to surface waters or a
sanitary sewer. Although direct filtration plants generally treat
source waters that have low concentrations of suspended material, the
solids loading to the filters may be higher than at conventional plants
because solids are not removed in a clarification process prior to
filtration. If spent filter backwash is not treated to remove solids
prior to recycle, solids loading onto the filters will continue to
increase over time, as an exit from the treatment process is
unavailable. Filter run length may be shorter in some direct filtration
plants relative to conventional plants because the solids loading to
the filters may be higher due to the lack of a clarification process.
The concentration of solids in the source water is a key variable in
filter run length.
iii. Softening Plants
Softening plants utilize the same basic treatment processes as
conventional treatment plants. Softening plants remove hardness
(calcium and magnesium ions) through precipitation, followed by solids
removal. Many softening plants employ a two-stage process, which
consists of a rapid mix-flocculation-sedimentation sequence, in series,
followed by filtration. Others use a single stage process, resembling
conventional treatment plants. Precipitation of the calcium and
magnesium ions is accomplished through the addition of lime (calcium
hydroxide), with or without soda ash (sodium carbonate), which reacts
with the calcium and magnesium ions in the raw water to form calcium
carbonate and magnesium hydroxide. The precipitation of the calcium
carbonate can be improved by recirculating some of the calcium
carbonate sludge into the rapid mix unit because the additional solids
provide nucleation points for the precipitation of calcium and
magnesium. Without this recirculation, additional hydraulic detention
time in the flocculation and sedimentation basins may be required to
prevent excessive scale deposits in the plant clearwell or in the
distribution system.
A softening plant generally has the same residual streams as a
conventional plant: Filter backwash, sedimentation solids, and
thickener supernatant and dewatering liquids. A filter-to-waste flow
may also be generated. These residual streams are either disposed or
recycled within the plant. A portion of the sedimentation basin solids
are commonly recycled as the sedimentation basin solids contain
significant quantities of precipitated calcium carbonate, recycle of
these solids reduces the required chemical dose. Solids are generally
recycled into the rapid mix chamber to maximize their effectiveness.
iv. Contact Clarification Plants
In the contact clarification process, the flocculation and
clarification (and often the rapid mix) processes are combined in one
unit, an upflow solids contactor or contact clarifier. Contact
clarifiers are employed in both softening and non-softening processes.
Raw water flows into the contact clarifier at the top of the central
compartment, where chemical addition and rapid mix occurs. The water
then flows underneath a skirt and into the outer sedimentation zone
where solid separation occurs. A large portion of previously settled
solids from the sedimentation zone is circulated to the mixing zone to
enhance flocculation. The remainder of the solids are disposed to
prevent their accumulation. Circulation and disposal of accumulated
solids allows clarifier loading rates to be 10 to 20 times greater than
loading rates for conventional sedimentation basins. Solids
recirculation rates are generally different for softening and turbidity
removal applications, with rates of up to 12 times the raw water flow
for softening processes and up to 8 times the raw water flow for non-
softening processes (ASCE/AWWA, 1998). Following clarification, treated
water from the contactor is then filtered.
The residual streams from contact clarification plants are similar
to those for conventional filtration plants. They include filter
backwash, clarification solids, thickener supernatant, and dewatering
liquids. The key operational consideration for these types of systems
is the maintenance of a high concentration of solids within the skirt
to allow high loading rates while maintaining adequate solids removal.
Solids recirculation (e.g., recycle) helps contact clarification
processes maintain the necessary solids concentration.
[[Page 19100]]
Softening plants may also generate filter to waste flow.
v. Package Plants
Package plants are typically used to produce between a few thousand
to 1 million gallons of water per day. Package plants can employ a
conventional treatment train, as well as proprietary unit processes.
Package plants typically include the same processes found in large
plants, including coagulation, flocculation, clarification and
filtration. The potential recycle streams are also comparable. The
recycle of filter backwash may occur, however, the typical package
plant may not be designed to convey process streams back into the plant
as recycle.
vi. Summary of Recycle Disposal Options
Two recycle disposal options available to some plants are direct
discharge to sanitary sewers or discharge to surface waters. Discharge
of recycle waters to the municipal sewer system may occur when the
treatment plant and Publicly Owned Treatment Works (POTW) are under the
same authority or when the plant has access to a sanitary sewer and a
POTW agrees to accept its discharge.
There may be a fee associated with discharge to a sanitary sewer
system, and the total fee may vary with the volume of backwash effluent
discharged as well as the amount of solids in the effluent (Cornwell
and Lee, 1994). In addition to the fee requirement, discharging into
the sewer system may require the plant to equalize the effluent prior
to discharging to the POTW. The equalization process requires holding
the effluent in tanks and gradually releasing it into the sanitary
sewer system. The fee associated with sanitary sewer discharge may
influence whether a plant recycles to the treatment process or
discharges to a sanitary sewer.
Another option to recycle within the treatment process is the
direct discharge of recycle flow to surface waters, such as creeks,
streams, rivers, and reservoirs. Direct discharge is a relatively
common method of disposal for water treatment plant flows. A National
Pollutant Discharge Elimination System (NPDES) permit requires that
certain water quality conditions be met prior to the discharge of
effluent into surface waters. Treatment of the effluent prior to
discharge may be required. The cost of effluent treatment may influence
whether plants recycle within the treatment process or discharge to
surface water.
b. Recycle Flow Occurrence Data
EPA has not regulated recycle flows in previous rulemakings. The
1996 SDWA Amendments have lead the Agency to perform an examination of
recycle flow occurrence data for the first time. EPA discovered through
its literature search and its work with AWWA, AWWSCo., and Cincinnati
Water Works to develop the issue papers, that the amount of recycle
stream occurrence data available is very limited, particularly for
Cryptosporidium, the primary focus of this regulation. This may be
because Cryptosporidium was identified as a contaminant of concern
relatively recently and because currently available oocyst detection
methods have limitations.
Twelve issue papers were developed to compile information on
several commonly produced recycle streams. Each individual paper
summarizes how the recycle stream is generated, the typical volume
generated, characterizes the occurrence of various recycle stream
constituents to the extent data allows, (i.e., occurrence of
Cryptosporidium and inorganic and organic material), and briefly
discusses potential impacts of recycling the stream. The discussion of
potential impacts is usually brief, due to overall data limitations and
particularly due to a lack of data on Cryptosporidium occurrence. The
12 recycle streams examined include:
untreated spent filter backwash water
gravity settled spent filter backwash water
combined gravity thickener supernatant (spent filter
backwash and clarification process solids)
gravity thickener supernatant from sedimentation basin
solids
mechanical dewatering device concentrate
untreated basin solids
lagoon decant
sludge drying bed leachate
monofill leachate membrane concentrate
ion exchange regenerate
minor streams
A total of 112 references were used to complete the issue papers,
and AWWSCo. and Cincinnati Water Works performed sampling of non-
microbial recycle stream constituents to supplement occurrence
information.
Cryptosporidium occurrence data was only identified for five
recycle streams, namely: untreated spent filter backwash water, gravity
settled spent filter backwash water, untreated sedimentation basin
solids, combined thickener supernatant, and sludge drying bed leachate.
Oocysts may occur in the other recycle streams as well, but published
occurrence data was not identified. The issue papers and supporting
literature indicate data does not exist to correlate oocyst occurrence
in recycle streams to the occurrence of oocysts in finished water.
However, the issue papers did identify data showing that oocysts occur
in recycle streams, often at concentrations higher than that of the
source water.
Cryptosporidium is not the only constituent of recycle waters.
Other common constituents are manganese, iron, aluminum, disinfection
byproducts, organic carbon, Giardia lamblia and particles. EPA does not
currently have data to indicate these constituents occur in recycle
streams at levels which threaten treatment plant performance, finished
water quality, or public health. Additionally, current regulations may
largely control any minor risk these constituents may present. For
example, organic matter in recycle flow may form disinfection
byproducts in the presence of oxidants. The Stage 1 DBPR, which
requires monitoring for disinfection byproducts, will identify systems
experiencing disinfection byproduct occurrence above or near applicable
MCLs through distribution system monitoring. Additionally, Secondary
Maximum Contaminant Levels (SMCLs) have been promulgated to control
occurrence of aluminum, iron, and manganese at levels of .05-.2 mg/l,
.3 mg/l, and .05 mg/l, respectively. Particle levels are controlled by
effluent turbidity standards and Giardia lamblia is controlled through
a combination of disinfection and filtration requirements. EPA believes
existing regulations control these recycle stream constituents.
Therefore, their control is not a primary goal of today's proposal.
Additionally, detailed discussion of these constituents is not provided
in the below summary of the issue papers because: (1) control of
Cryptosporidium is the focus of the recycle provisions, and; (2)
concentrations of inorganic and organic materials reported in the issue
papers are for recycle streams, not finished water occurrence. The
recycle stream concentrations will be significantly diluted by mixing
with source water.
The occurrence of recycle flow constituents other than
Cryptosporidium is not discussed in today's preamble for the above
reasons. The following discussion of recycle stream occurrence data
covers only untreated spent filter backwash water, gravity settled
spent filter backwash water, combined gravity thickener
[[Page 19101]]
supernatant (a combination of spent filter backwash and clarification
process solids), gravity thickener supernatant from clarification
process solids, and mechanical dewatering device liquids. These five
recycle streams are discussed in detail because they are most likely to
present a threat to treatment plant performance or finished water
quality when recycled. For example, treated and untreated spent filter
backwash water and thickener supernatant are the only two recycle
streams of sufficient volume to cause plants to exceed their operating
capacity during recycle events. The five recycle streams discussed
below are also most likely to contain Cryptosporidium.
Copies of all the issue papers are available for public review in
the Office of Water docket for this rulemaking. Portions of the
following recycle stream descriptions use excerpts from the issue
papers.
i. Untreated Spent Filter Backwash Water
Water treatment plants that employ rapid granular filtration (e.g.,
conventional, softening, direct filtration, contact clarification)
generate spent filter backwash water. The backwash water is generated
when water is forced through the filter, counter-current to the flow
direction during treatment operations, to dislodge and remove
accumulated particles and pathogens residing in the filter media.
Backwash rates are typically five to eight times the process rate, and
are used to clean the filter at the end of a filter run, which is
generally 24 to 72 hours in length. Backwash operations usually last
from 10 to 25 minutes. The flow rate and duration of backwashing are
the primary factors that determine the volume of backwash water
produced. Once the backwashing process is complete, the backwash water
and entrained solids are either disposed of to a sanitary sewer,
discharged to a surface water, or returned to the treatment process.
Plants currently return spent filter backwash to the treatment process
at a variety of locations, usually between plant headworks and
clarification. Data regarding common recycle return locations is
discussed in the next section of this preamble.
Spent filter backwash can be returned to the treatment process
directly as it is produced, be detained in an equalization basin, or
passed through a treatment process, such as clarification, prior to
being returned to the plant. On a daily basis, spent filter backwash
can range from 2 to 10 percent of plant production. Spent filter
backwash is usually produced on an intermittent basis, but large plants
with numerous filters may produce it continuously. At small and mid-
size plants, large volume, short duration flows of spent filter
backwash are usually produced. This may cause some plants, particularly
smaller plants that recycle directly without flow equalization or
treatment, to exceed their operating capacity or to experience
hydraulic disruptions, both of which may negatively impact treatment
efficiency and oocyst removal.
The concentrations of Cryptosporidium reported in the untreated
spent filter backwash issue paper ranges from non-detect to a
concentration of 18,421 oocysts per 100 L. This range is not amenable
to formal statistical analysis, but rather provides a summary of
minimum and maximum oocyst concentrations reported in available
literature. Although a few studies report isolated data points of
greater than 10,000 oocysts/100L for filter backwash water (Rose et
al., 1989; Cornwell and Lee, 1993; Colbourne, 1989), occurrence studies
that collected the largest number of samples reported mean filter
backwash oocyst occurrence concentrations of a few hundred oocysts per
100L (States et al., 1997; Karanis et al., 1996). The high
concentration of oocysts found in some spent filter backwash samples is
cause for concern, because oocysts are not inactivated by standard
disinfection practice. They remain a threat to pass through the plant
into the finished water if they are returned to the treatment process.
However, current oocyst detection methods do not allow the occurrence
of oocysts in spent filter backwash water to be correlated to finished
water oocyst concentrations for a range of plant types, source water
qualities, and recycle practices. Today's proposal does not require the
installation of recycle equalization or treatment for spent filter
backwash water on a national basis due to these data limitations.
The Agency is concerned that certain recycle practices, such as
returning spent filter backwash to locations other than prior to the
point of primary coagulant addition, or hydraulically overloading the
plant with recycle flow so it exceeds its State approved operating
capacity, may present risk to finished water quality and public health.
Exceeding plant operating capacity during recycle events may cause
greater risk to finished water quality, because plant performance is
potentially being lowered at precisely the time oocysts are returned to
the plant in the recycle flow. To address this concern, today's
proposal requires that certain direct recycle plants that recycle spent
filter backwash water and/or thickener supernatant to perform a self
assessment of their recycle practice and report the results to the
State. The self assessment requirements are discussed in detail later
in this preamble.
ii. Gravity Settled Spent Filter Backwash Water
Gravity settled spent filter backwash water is generated by the
same filter backwash process and is produced in the same volume as
untreated spent filter backwash water. The difference between the two
streams is that the former is treated by gravity settling prior to its
return to the primary treatment process. Sedimentation treatment is
usually accomplished by retaining the spent filter backwash water in a
treatment unit for a period of time to allow suspended solids
(including oocysts) to settle to the bottom of the basin. Polymer may
be used to improve process efficiency. The water that leaves the basin
is gravity settled spent filter backwash water. Removing solids from
the spent filter backwash causes only a minor reduction in volume as
the solids content of the untreated stream is low, usually below 1
percent.
Providing gravity settling for spent filter backwash is
advantageous for two reasons. First, the sedimentation process detains
the spent filter backwash in treatment basins for a period of hours,
which lowers the possibility a large recycle volume will be returned to
the plant in a short amount of time and cause the plant operating
capacity to be exceeded. Second, treating the spent filter backwash
flow can remove Cryptosporidium oocysts from the flow, which will
reduce the number of oocysts returned to the plant.
Limited data show that sedimentation can effectively remove
oocysts. Cornwell and Lee (1993) conducted limited sampling of spent
filter backwash water at two plants prior to and after sedimentation
treatment. The first facility practiced direct filtration and was
sampled twice. The Cryptosporidium concentrations into and out of the
sedimentation basin treating spent filter backwash were 900/100L and
140/100L, respectively, for the first sampling and 850/100L in the
influent and 750/100L in the effluent for the second sampling. At the
second plant a sludge settling pond received both sedimentation basin
sludge and spent filter backwash, and the spent filter backwash oocyst
concentration was 16,500/100L, and the treated recycle water
concentration was 420/100L. In a study by Karanis (1996),
Cryptosporidium was regularly detected in settled backwash waters. Of
the 50
[[Page 19102]]
samples collected, 82 percent tested positive for Cryptosporidium. The
mean value for Cryptosporidium was 22 oocysts/100L.
Sedimentation treatment can remove oocysts from spent filter
backwash, but data indicate oocysts remain in gravity settled spent
filter backwash water even after treatment. The Agency believes that
sedimentation treatment for spent filter backwash waters is capable of
removing oocysts and improving the quality of the water prior to
recycle. However, given current data limitations, the Agency does not
believe it is possible to specify, in a national regulation, the
conditions (e.g., source water oocyst concentrations, primary treatment
train performance, concentration of oocysts in spent filter backwash,
ability of sedimentation to remove oocysts under a range of conditions)
under which sedimentation treatment of spent filter backwash water may
be appropriate. This decision is best made by State programs to allow
consideration of site-specific conditions and treatment needs.
iii. Combined Gravity Thickener Supernatant
Combined gravity thickener supernatant is derived from the
treatment of filter backwash water and sedimentation basin solids in
gravity thickener units. These two flows may not reside in the
thickener at the same time or in equal volumes, depending on plant
operations. The volume of thickener supernatant generated at a water
treatment plant is a function of the type of flows it treats, the
solids content of the influent stream, and the method of thickener
operation. Regardless of whether a continuous or a batch process is
used, a number of factors, including residuals production (a function
of plant production, raw water suspended solids, and coagulant dose),
volume of spent filter backwash water produced, and the level of
treatment provided to thickener influent streams, directly affect the
quantity of thickener supernatant produced.
The flow entering the thickener is primarily spent filter backwash
water. Sedimentation basin solids is the second largest flow. Flow from
dewatering devices, which is generated by the dewatering of residuals,
may comprise a minor volume entering the thickener. Combined thickeners
will have an influent that may be eighty-percent spent filter backwash
or more by volume. About eighty-percent of the solids entering the
thickener will be from the sedimentation basin sludge, as spent filter
backwash water has a comparatively low solids concentration.
A recent FAX survey (AWWA, 1998) identified more than 300 water
treatment plants in the United States with production capacities
ranging from less than 2 mgd to greater than 50 mgd that recycle spent
filter backwash water. Many of the survey respondents indicated that
they recycle more than just spent filter backwash water. Based on the
survey and published literature, thickener supernatant is probably the
second largest and second most frequently recycled stream at water
treatment facilities after spent filter backwash.
Data summarized in the issue paper showed that thickener
supernatant quality varies widely, due in large part because the type
and quality of recycle streams entering thickeners varies over time and
from plant to plant. The turbidity, total suspended solids, and
particle counts of thickener effluent are directly impacted by the
quality of water loaded onto the thickener, thickener design, and
thickener operation (e.g., residence time, use of polymer).
Data on the occurrence of Cryptosporidium was limited to two
samples, with oocyst occurrence ranging from 82 to 420 oocysts per 100
L. Data is too limited, and practice varies too widely, to draw
conclusions on the impact recycle of this flow may have on plant
performance. However, given that the contents of the thickener have
been treated and the amount of flow produced by gravity thickeners is
relatively modest, it may be feasible to recycle the flow in a manner
that minimizes adverse impact. Additionally, treatment plant personnel
have a vested interest in optimizing thickener operation to minimize
sludge dewatering and handling costs; optimization of thickener
operation is likely to assist oocyst removal. However, additional data
is needed to characterize the occurrence of Cryptosporidium and the
potential impact recycle of combined thickener supernatant may have on
finished water quality.
iv. Gravity Thickener Supernatant from Sedimentation Solids
Gravity settled sedimentation basin solids are sedimentation basin
solids that have undergone settling to allow solid sludge components to
settle to the bottom of a gravity thickener. The supernatant from the
thickener is a potential recycle flow. The tank bottom is sloped to
enhance solids thickening and collection and removal of settled solids
is accomplished with a bottom scraper mechanism. If the supernatant is
recycled, it can be returned to the plant continuously or
intermittently, depending on whether the thickener is operated in batch
mode. Thickeners may receive and treat both spent filter backwash water
and sedimentation basin solids. For purposes of this discussion, and
the data presented in the issue paper, the gravity thickener is only
receiving sedimentation basin solids.
The volume of treated sedimentation basin solids supernatant
generated is dependent on the amount of sludge produced in the
sedimentation basin, the solids content of the sludge, and method of
thickener operation. Sludge production is a function of plant
production, raw water suspended solids, coagulant type, and coagulant
dose. The quantity of sedimentation basin sludge supernatant is
approximately 75 to 90 percent of the original volume of sedimentation
basin sludge produced.
There is a very limited amount of data on the quality of thickener
supernatant produced by gravity settling of only sedimentation basin
solids (i.e., spent filter backwash and other flows are not added to
the thickener), and no data was identified regarding the concentration
of Cryptosporidium that occur in the supernatant. As is the case with
combined gravity thickener supernatant, it is difficult to determine
what impact, if any, the return of the supernatant may have on plant
operations and finished water quality due to limited data. Additional
data is necessary to determine the concentration of oocysts in this
recycle stream, and to characterize the impact its recycle may have to
plant performance.
v. Mechanical Dewatering Device Liquids
Water treatment plant residuals (usually thickened sludge) are
usually dewatered prior to disposal to remove water and reduce volume.
Two common mechanical dewatering devices used to separate solids from
water are the belt filter press, which compresses the residuals between
two continuous porous belts stretched over a series of rollers, and the
centrifuge, which applies a strong centrifugal force to separate solids
from water. The plate and frame press is another dewatering device that
contains a series of filter plates, supported and contained in a
structured frame, which separate sludge solids from water using a
positive pressure differential as the driving force. Water removed from
the solids with a belt filter press is called filtrate, from a filter
press it is called pressate, and the water separated from the residuals
with a centrifuge is referred to as centrate.
[[Page 19103]]
These streams will be collectively referred to as ``dewatering liquid''
for the following discussion.
The volume of dewatering liquid produced depends primarily on the
volume and solids content of the thickened residuals fed to the
mechanical dewatering device. Plants that produce small sludge volumes,
and hence a low volume of thickener residuals, will process fewer
residuals in the mechanical dewatering device and hence produce a
smaller volume of dewatering liquid than a plant producing a large
volume of solids, all else being equal. Since residuals are often
thickened (typically to about 2 percent solids) prior to dewatering,
the volume of the dewatering device feed stream is significantly lower
than the volume of sedimentation basin residuals generated. If the
sedimentation basin sludge flow is assumed to be 0.6 percent of plant
production, then dewatering device flow may be approximately 0.1 to 0.2
percent of plant flow. Generally these streams are mixed in with other
recycle streams prior to being returned to the plant. Mechanical
dewatering devices may be operated intermittently, after a suitable
volume of residuals have been produced for dewatering. The production
of dewatering liquid and its recycle may not be a continuous process.
Data on the constituents in dewatering liquid were found in three
references, one on belt filter press liquids, one on plate and frame
pressate, and one on centrifuge centrate. Data on the occurrence of
Cryptosporidium was not identified. Given the small, intermittent flow
produced by mechanical dewatering devices, recycle flows from them are
unlikely to cause plants to exceed operating capacity. However, it is
possible that dewatering device liquid contains Cryptosporidium because
it derived from solids likely to hold a large numbers of oocysts.
Additional data is necessary to determine the concentration of oocysts
in this recycle stream, and to characterize any impact its recycle may
have to plant performance.
2. National Recycle Practices
a. Information Collection Rule
Public water systems affected by the ICR were required to report
whether recycle is practiced and sample washwater (i.e., recycle flow)
between the washwater treatment plant (if one existed) and the point at
which recycle is added to the process train. Sampling of plant recycle
flow was required prior to blending with the process train. Monthly
samples were required for pH, alkalinity, turbidity, temperature,
calcium and total hardness, TOC, UV254, bromide, ammonia,
and disinfectant residual if disinfectant was used. Systems were also
required to measure recycle flow at the time of sampling, the twenty
four hour average flow prior to sampling, and report whether treatment
of the recycle was provided and, if so, the type of treatment.
Reportable treatment types were plain sedimentation, coagulation and
sedimentation, filtration, disinfection, or a description of an
alternative treatment type. Plants were also required to submit a plant
schematic to identify sampling locations. EPA used the sampling
schematics and other reported information to compile a database of
national recycle practice.
i. Recycle Practice
The Agency developed a database from the ICR sampling schematics
and other reported information. Table IV.10 summarizes the plants in
the database. Of the 502 plants in the database at the time the
analysis was performed, 362 used rapid granular filtration.
Table IV.10.--Recycle Practice at ICR Plants
------------------------------------------------------------------------
Plant classification Number
------------------------------------------------------------------------
All ICR plants................................................. 502
Filtration plants \a\.......................................... 362
Filtration plants recycling \b\................................ 226
Filtration plants treating recycle............................. 148
Recycle plants serving 100,000...................... 168
Recycle plants serving 100,000................................. 58
------------------------------------------------------------------------
\a\ Defined as conventional, lime softening, other softening, and direct
filtration plants.
\b\ Plants report existence of a recycle stream, not its origin.
These plants are classified as conventional, lime softening, other
softening, and direct filtration. The remaining 140 plants in the
database do not employ rapid granular filtration capability and
generally provide disinfection for ground water. Of the 362 filtration
plants in the database, 226 (62.4 percent) reported recycling to the
treatment process. Seventy-four percent of the plants that recycle
serve populations greater than 100,000 and 26 percent serve populations
below 100,000. Figure IV.9 shows the distribution of plants by
treatment type and Figure IV.10 shows the distribution of plants by
population served. Table IV.11 shows that 88 percent of ICR recycle
plants use surface water. An additional one percent use GWUDI and
another one percent use a combination of ground water and surface
water. Therefore, 90 percent of ICR recycle plants use a source water
that could contain Cryptosporidium.
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Table IV.11.--Source Water Use by ICR Recycle Plants
------------------------------------------------------------------------
Percent of
Source water type Number of recycle
plants plants
------------------------------------------------------------------------
Total number of recycle plants................ 226 100
Surface Water................................. 199 88
Ground water under the influence.............. 3 1
Ground water and surface water................ 2 1
Ground water only............................. 22 10
------------------------------------------------------------------------
Table IV.12 shows that 65 percent of ICR recycle plants report
providing treatment for the recycle flow. The percentage of plants
providing treatment is the same for the subsets of plants serving
greater than and less than 100,000 people. Sedimentation is the most
widely reported treatment method, as 77 percent of plants providing
treatment employ it. The database does not provide information on the
solids removal efficiency of the sedimentation units. All direct
filtration plants practicing recycle reported providing treatment for
the recycle flow.
Table IV.12.--Treatment of Recycle at ICR Plants \1\
------------------------------------------------------------------------
Number of Percentage of
ICR recycling plants plants recycle plants
------------------------------------------------------------------------
Number of recycle plants................ 226 100
Practice recycle treatment.............. 147 65
Use sedimentation....................... 114 77
Use sedimentation/coagulation........... 14 10
Use two or more treatments.............. 14 10
Other treatment......................... 5 3
------------------------------------------------------------------------
\1\ Disinfection not counted as treatment because it does not inactivate
Cryptosporidium.
Table IV.13 indicates that 75 percent of ICR recycle plants return
recycle prior to rapid mix. Fifteen percent return it prior to
sedimentation, and ten percent of plants return it prior to filtration.
These percentages hold for the subsets of plants serving greater than
and less than 100,000 people. The data indicate that introducing
recycle prior to rapid mix may be a common practice. EPA believes that
introducing recycle flow prior to the point of primary coagulant
addition, is the best recycle return location because it limits the
possibility residual treatment chemicals in the recycle flow will
disrupt treatment chemistry.
Table IV.13.--Recycle Return Point
------------------------------------------------------------------------
Number of percent of
Point of recycle return plants plants
------------------------------------------------------------------------
Number of recycle plants................ \1\224 100
Prior to point of primary coagulant 169 75
addition...............................
Prior to sedimentation.................. 34 15
Prior to filtration..................... 21 10
------------------------------------------------------------------------
\1\ Recycle return point could not be determined for two plants.
The data provides the following conclusions regarding the recycle
practice of ICR plants: (1) The recycle of spent filter backwash and
other process streams is a common practice; (2) the great majority of
recycle plants in the database use filtration and surface water
sources; (3) a majority of plants in the database that recycle provide
treatment for recycle flow, and; (4) a large majority of plants in the
database that recycle (approximately 3 out of 4) recycle prior to the
point of primary coagulant addition.
b. Recycle FAX Survey
The AWWA sent a FAX survey (AWWA, 1998) to its membership in June
1998 to gather information on recycle practices. Plants were not
targeted based on source water type, the type of treatment process
employed, or any other factor. The survey was sent to the broad
membership to increase the number of responses. Responses indicating a
plant recycled spent filter backwash or other flows were compiled to
create a database. The resulting database included 335 plants. The
database does not contain information from respondents who reported
recycle was not practiced. Data from some of the FAX survey respondents
also populates the ICR database. Plants in the database are well
distributed geographically and represent a broad range of plant sizes
as measured by capacity. Figure IV.11 shows plant distribution by
capacity and Figure IV.12 by geographic location. The following
discussion of FAX survey data is divided into two sections. The first
discusses national recycle practice and the second discusses options
for recycle disposal in lieu of returning recycle to the treatment
process.
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i. Recycle practice
Data summarized in Table IV.14 show that 78 percent of plants in
the database rely on a surface water as their source. The percentage of
plants using source water influenced by a surface water (which may
contain Cryptosporidium) could be higher because the data do not report
whether wells were pure ground water or GWUDI.
Table IV.14.--Source Water Used by FAX Survey Plants
------------------------------------------------------------------------
Percent
Source water type of
plants
------------------------------------------------------------------------
Surface Water................................................. 78
River......................................................... 27
Reservoir..................................................... 28
Lake.......................................................... 16
Other......................................................... 7
Well \1\...................................................... 22
------------------------------------------------------------------------
\1\ Wells sources not defined as either ground water or ground water
under the direct influence of surface water.
Table IV.15 shows that a wide variety of treatment process types
are included in the data, with conventional filtration (rapid mix,
coagulation, sedimentation, filtration) representing over half of the
plants submitting data. Upflow clarification is the second most common
treatment process reported. Ten percent of plants in the database use
direct filtration. Only four percent of plants do not use rapid
granular filtration.
Table IV.15.--Treatment Trains of FAX Survey Plants
------------------------------------------------------------------------
Percent
Treatment process type of plants
\1\
------------------------------------------------------------------------
Rapid mix, coagulation, filtration........................... 51
Upflow clarifier............................................. 21
Softening.................................................... 14
Direct filtration............................................ 10
Other........................................................ 4
------------------------------------------------------------------------
\1\ 96 percent of plant in the database provide filtration.
Table IV.16 indicates that a vast majority of plants recycle prior
to the point of primary coagulant addition. Only six percent of plants
returned recycle in the sedimentation basin or just prior to
filtration.
Table IV.16.--Recycle Return Point of FAX Survey Plants
------------------------------------------------------------------------
Percent
Return point of
plants
------------------------------------------------------------------------
Prior to point of primary coagulant addition.................. 83
Pre-sedimentation (e.g., rapid mix)........................... 11
Sedimentation basin........................................... 4
Before filtration............................................. 2
------------------------------------------------------------------------
Table IV.17 shows that the majority of plants in the database
provide some type of treatment for the recycle flow prior to its
reintroduction to the treatment process. Approximately 70 percent of
plants reported providing treatment, with sedimentation being employed
by over half of these plants. Equalization, defined as a treatment
technology by the survey, is practiced by 20 percent of plants in the
database. Fourteen percent of plants reported using both sedimentation
and equalization.
Table IV.17.--Recycle Treatment at FAX Survey Plants
------------------------------------------------------------------------
Percent
Treatment type of
plants
------------------------------------------------------------------------
No treatment.................................................. 30
Treatment..................................................... 70
Sedimentation................................................. 54
Equalization.................................................. 20
Sedimentation and equalization................................ 14
Lagoon........................................................ 5
Others........................................................ 7
------------------------------------------------------------------------
Table IV.18 summarizes recycle treatment practice and frequency of
direct recycle based on population served. The table illustrates that,
for plants supplying data, treatment of recycle with sedimentation is
provided more frequently as plant service population deceases. Plants
serving populations of less than 10,000 recycle directly (27.5 percent)
less frequently than plants serving populations greater than 100,000
(50 percent). The data indicate that a majority of small plants in the
database may have installed equalization or sedimentation treatment to
protect treatment process integrity from recycle induced hydraulic
disruption. All direct filtration plants in the FAX survey provide
recycle treatment or equalization.
Table IV.18.--Recycle Practice Based on Population Served \1\
----------------------------------------------------------------------------------------------------------------
Recycle practice
Population served ------------------------------------------------------------
#Plants Equalization Sedimentation Direct recycle
----------------------------------------------------------------------------------------------------------------
10,000............................................. 43 9% (n=4) 67% (n=29) 23% (n=10)
10,000-50,000...................................... 79 10% (n=8) 57% (n=45) 33% (n=26)
50,000-100,000..................................... 35 17% (n=6) 54% (n=19) 29% (n=10)
100,000............................................ 65 35% (n=23) 23% (n=15) 42% (n=27)
----------------------------------------------------------------------------------------------------------------
\1\ Based on 222 surface water plants suppling all necessary data to make determination.
FAX survey data support the following conclusions regarding the
recycle practice of plants supplying data: (1) The recycle of spent
filter backwash and other process streams is a common practice; (2) the
majority of recycle plants use surface water as their source and are
thereby at risk from Cryptosporidium; (3) a large majority of plants
providing data recycle prior to the point of primary coagulant
addition, and; (4) a majority of plants supplying data provide
treatment for recycle waters prior to reintroducing them to the
treatment plant. The FAX survey provides an informative snapshot of
national recycle practices due to the number of recycle plants it
includes, the geographic distribution of respondents, and the good
representation of plants serving populations of less than 10,000
people.
ii. Options to recycle.
The FAX survey asked whether feasible alternatives to recycle are
available (i.e., NPDES surface water discharge permit, pretreatment
permit for discharge to POTW) and the importance of recycle to
optimizing treatment performance and meeting production requirements.
Responses to these questions is summarized in Table IV.19.
Table IV.19 shows that approximately 20 percent of respondents
could not obtain either an NPDES surface water discharge permit or a
pretreatment permit for discharge to a POTW. Approximately 90 percent
of respondents stated that recycle flow is not important to meet
typical demand.
[[Page 19110]]
Twenty-four percent of all respondents stated that returning recycle to
the treatment process is important for optimal operation. ``Optimal
operation'' was not defined by the survey and respondents may have
considered not changing current plant operation (e.g., not changing
current recycle practice) an aspect of optimal treatment, rather than
addressing whether recycle practice is important for the plant to
produce the highest quality finished water.
Table IV.19.--Options to Recycle as Reported by FAX Survey Plants \1\
------------------------------------------------------------------------
Percent Percent Percent
Question Yes No Unknown
------------------------------------------------------------------------
Able to obtain NPDES surface discharge 41% 37% 22%
permit?............................... (n=131) (n=120) (n=70)
Able to obtain pretreatment permit for 43% 42% 15%
POTW discharge?....................... (n=137) (n=136) (n=48)
Can obtain either an NPDES or a POTW 60% 19.5% 20.5%
discharge permit?..................... (n=192) (n=63) (n=66)
Is recycle important to meet peak 14% 80% 6%
demand?............................... (n=44) (n=257) (n=20)
Is recycle important to meet typical 9% 85% 6%
demand?............................... (n=28) (n=272) (n=21)
Is recycle important to optimal 24% 70% 6%
operation? (All plants in survey)..... (n=75) (n=225) (n=21)
Is recycle important to optimal 13% 83% 4%
operation? \2\ (softening plants only) (n=3) (n=19) (n=1)
------------------------------------------------------------------------
\1\ Number of plants varies from question to question due to different
response rates.
\2\ Optimal operation not defined by survey. May include overall plant
operation rather than importance of recycle to producing highest
possible quality finished water.
iii. Conclusions
The ICR and FAX survey data are complimentary, as the ICR data
supplies a wealth of data regarding recycle practices at large capacity
plants, while the FAX Survey provides data on recycle practices over a
range of plant capacities. Taken together, the two data sets provide a
good picture of current recycle practice. The data indicate that
recycle is a common practice for plants sampled. Approximately half of
the respondents providing data return recycle flow to the treatment
process and 70 percent provide some type of recycle treatment.
Sedimentation and equalization are the two most commonly employed
treatment technologies for plants supplying data. Approximately 80
percent of plants sampled return recycle prior to the point of primary
coagulant addition. Examining the recycle practices of plants in the
ICR and FAX survey data show that small plants (i.e., fewer than 10,000
people served) are more than twice as likely as large plants (i.e.,
greater than 100,000 people served) to provide sedimentation for
recycle treatment (58 versus 26 percent).
The FAX survey responses show that approximately half of plants
providing data have an option to recycle return, whether it be an NPDES
surface water discharge permit or discharge to a POTW. Eighty-five
percent of respondents stated that recycle flow is not important to
meet peak demand. Less than a quarter of respondents have monitored
pathogen concentrations in backwash water and fewer than half have any
monitoring data to characterize the quality of the backwash water.
3. Recycle Provisions for PWSs Employing Rapid Granular Filtration
Using Surface Water or Ground Water Under the Direct Influence of
Surface Water
a. Return Select Recycle Streams Prior to the Point of Primary
Coagulant Addition
i. Overview and Purpose
Today's proposal requires that systems employing rapid granular
filtration and using surface water or GWUDI as a source return filter
backwash, thickener supernatant, and liquids from dewatering processes
to the primary treatment process prior to the point of primary
coagulant addition. The goal of this provision is to protect the
integrity of chemical treatment and ensure these recycle streams are
passed through as many physical removal processes as possible to
provide maximum opportunity for removal of Cryptosporidium oocysts from
the recycle flow. Since Cryptosporidium is resistant to standard
disinfection practice, it is important that chemical treatment be
optimized to protect treatment plant efficiency and that all available
physical removal processes be employed to remove it.
Today's proposal requires these flows be returned prior to the
point of primary coagulant addition because these streams are either of
sufficient volume to cause hydraulic disruption within the treatment
process when recycled and/or are likely to contain Cryptosporidium
oocysts. Minor recycle streams, such as lab sample lines, pump packing
water, and infrequent process overflows are not likely to threaten
plants' hydraulic stability or contain appreciable numbers of oocysts.
Treatment plant types that need to return recycle to a location
other than prior to the point of primary coagulant addition to maintain
optimal treatment performance (optimal performance as indicated by
finished water or intra-plant turbidity levels), plants that are
designed to employ recycle flow as an intrinsic component of their
operations, plants with very low influent turbidity levels that may
need alternative recycle locations to obtain satisfactory suspended
solids removal, or other types of plants constrained by unique
treatment considerations, may apply to the State to recycle at an
alternative location under today's proposal. Once approved by the
State, plants may recycle to the specified location.
ii. Data
Data from the ICR and FAX Survey indicate that 75 and 78 percent of
plants, respectively, return recycle prior to the point of primary
coagulant addition. The ``point of primary coagulant addition'' was
defined in both analyses as the return of recycle prior to the rapid
mix unit. The FAX Survey data indicate that 77 percent of plants
serving under 10,000 people recycle prior to the point of primary
coagulant
[[Page 19111]]
addition. It also showed that 78 percent percent of all plants in the
database return recycle there, which suggests that plants serving
smaller populations may return recycle prior to the point of primary
coagulant addition as frequently as plants serving larger populations.
Other common recycle return locations are the rapid mix unit, between
rapid mix and clarification, or into the clarification unit itself.
The Agency does not believe filter backwash, thickeners
supernatant, or liquids from dewatering processes should be recycled at
the point of primary coagulant addition or after it for three reasons:
(1) Addition of these recycle streams, which can contain residual
coagulant and other treatment chemicals, after the location of primary
coagulant addition, may render the chemical dose applied less
effective, potentially harming the efficiency of subsequent treatment
processes;
(2) Introduction of recycle into the flocculation unit or
clarification unit may create hydraulic currents that exacerbate or
create short circuiting, and;
(3) Recycle introduced into the clarification process may not
experience sufficient residence time for adequate solids removal to
occur.
The Agency is concerned that plants may not adjust chemical dosage
during recycle events to account for: (1) The presence of a potentially
significant amount of residual treatment chemical in recycle flow and
changes in recycle flow quality, and; (2) potentially large
fluctuations in plant influent flow during recycle events. EPA is
concerned that changes in influent water quality and flow are not
monitored on an instantaneous basis during recycle events. Since the
chemistry of the recycle flow and source water may differ
significantly, it is important plants mix source and recycle water to
establish a uniform chemistry prior to applying treatment chemical so
the dose is appropriate for the mixture. Additionally, wide fluctuation
in plant influent flow during recycle events may cause chemical over-or
under-dosing, which can lower overall oocyst removal efficiency. In an
article concerning optimization of filtration performance, Lytle and
Fox (1996) state, ``The capability to instantaneously monitor treatment
processes and rapidly and effectively respond to raw and filter
effluent quality changes are important factors in consistently
producing low turbidity water.'' Logdson (1987) further states, ``For a
plant to be operated properly, the total flow rate has to be known on
an instantaneous basis or by volumetric measurement.'' EPA believes it
is important plants diligently monitor the appropriateness of chemical
dosing at all times, but particularly during recycle events, and strive
for real-time chemical dose and influent flow management to optimize
plant oocyst removal.
Pilot-scale research conducted by Patania et al. (1995) to examine
the optimization of filtration found that chemical pretreatment was the
most important variable determining oocyst removal by filtration.
Edzwald and Kelley (1998) performed pilot-scale work to determine the
ability of sedimentation, DAF, and filtration to remove Cryptosporidium
and found that coagulation is critical to effective Cryptosporidium
control by clarification and filtration. Bellamy et al. (1993) stated
that the most important factor in plant performance is the use of
optimal chemical dosages. Coagulation was recognized as the single most
important step in the process of water clarification by Conley (1965).
Ten pilot scale runs performed by Dugan et al. (1999) showed that
coagulation has a large influence on the log removal of Cryptosporidium
achieved by sedimentation. The importance of proper coagulation to
filter performance was noted by Robeck et al. (1964) in pilot and full-
scale work that showed proper coagulation is more important to the
production of safe water than the filtration rate used. Results of
direct filtration pilot studies, summarized by Trussell et al. (1980),
showed that ``effective coagulant is absolutely necessary if good
effluent qualities are to be consistently produced.''
Given the critical role proper chemical dosing plays in maintaining
effective clarification and filtration processes, the Agency believes
it is prudent and necessary to minimize the possibility recycle of
spent filter backwash, thickener supernatant, and dewatering liquids
will render chemical dosages applied during recycle events inaccurate,
due to the presence of residual chemical or variations in influent
flow, by requiring they be returned prior to the point of primary
coagulant addition.
Finally, a fundamental tenet of water treatment is multiple
treatment barriers should be provided to prevent microbial pathogens
from entering finished water. To achieve this, conventional plants rely
on coagulation, flocculation, clarification, and filtration as
preventive microbial barriers. The Agency believes it is important that
recycle waters be passed through each of these treatment processes to
maximize the probability disinfection resistant oocysts will be removed
in the plant and not enter the finished water supply.
iii. Proposed Requirements
Today's proposal requires that rapid granular filtration plants
using surface water or GWUDI as a source return filter backwash,
thickener supernatant, and liquids from dewatering processes prior to
the point of primary coagulant addition. Plants that require an
alternative recycle return location to maintain optimal finished water
quality (as indicated by finished water or intra-plant turbidity
levels), plants that are designed to employ recycle flow as an
intrinsic component of the treatment process, or plants with unique
treatment requirements or processes may apply to the State to return
recycle flows to an alternative location. Plants may utilize this
alternative location once granted by the State. EPA will develop
detailed guidance and make it available to States and PWSs.
Softening systems may recycle process solids, but not spent filter
backwash, thickener supernatant, or liquids from dewatering processes,
at the point of lime addition immediately preceding the softening
process to improve treatment efficiency. Literature establishes that
return of process solids to point of lime addition decreases production
of nuclei, increases the rate of crystallization, and increases crystal
size, all of which enhance settling and process integrity (Randtke,
1999; Snoeyink and Jenkins, 1980). Contact clarification systems may
recycle process solids, but not spent filter backwash, thickener
supernatant, or liquids from dewatering processes, directly into the
contactor to improve treatment efficiency.
iv. Request for Comments
EPA requests comment on the proposed requirements. The Agency also
requests comment on the following aspects of this provision:
(1) What regulatory options are available to ensure direct recycle
plants practice real-time chemical dose and influent flow management?
Should flow-paced coagulant feed be required at direct recycle plants
to minimize potential harmful impacts of recycle? What regulatory
requirements may be applicable to ensure the integrity of the
coagulation process?
(2) What treatment processes or treatment configurations may need
an alternative recycle location to maintain optimal treatment?
(3) What alternative recycle locations are appropriate for such
treatment configurations and what location may be inappropriate?
[[Page 19112]]
(4) Are there other reasons, beyond maintaining optimal treatment
efficiency, to justify granting alternate recycle locations to plants?
What are they?
(5) What criteria, operating practices, or other parameters should
be evaluated to determine whether an alternative recycle return
location should be granted?
(6) Does recycling at the point of primary coagulant addition,
instead of prior to it, provide assurance that an appropriate dose of
treatment chemicals will be consistently applied during recycle events?
Is it necessary to mix the recycle and raw water prior to chemical
addition to ensure a consistent water chemistry for chemical dosing?
(7) Are there circumstances where it would be appropriate to allow
systems to recycle at the point of primary coagulant addition?
b. Recycle Requirements for Systems Practicing Direct Recycle and
Meeting Specific Criteria
i. Overview and Purpose
Today's proposal requires that self assessments be performed at
conventional filtration plants meeting all of the following criteria
and the results of the self assessment reported to the State. The
criteria are:
(1) Use of surface water or GWUDI as a source;
(2) Employ of 20 or fewer filters to meet production requirements
during the highest production month in the 12 month period prior to
LT1FBR's compliance date, and;
(3) Recycle spent filter backwash or thickener supernatant directly
to the treatment process (i.e., recycle flow is returned within the
treatment process of a PWS without first passing the recycle flow
through a treatment process designed to remove solids, a raw water
storage reservoir, or some other structure with a volume equal to or
greater than the volume of spent filter backwash water produced by one
filter backwash event.)
The goal of the self assessment is to identify those direct recycle
plants that exceed their State approved operating capacity, on an
instantaneous basis, during recycle events. Plants are required to
submit a monitoring plan to the State prior to conducting the month
long self assessment monitoring. Results of self assessment monitoring
must be reported to the State. The State is required to determine, by
reviewing the self assessment, whether the plant's current recycle
practice should be modified to protect plant performance and provide an
additional measure of public health protection. The State is required
to report its determination for each plant performing a self assessment
to EPA and briefly summarize the reason(s) supporting each
determination.
EPA selected the three aforementioned criteria to identify plants
required to perform a self assessment for the following reasons. First,
surface or GWUDI source waters may contain Cryptosporidium. Second, the
hydraulic impact of recycle to plants typically employing more than 20
filters to meet production requirements should be dampened because
plant influent flow is of significantly greater magnitude than the flow
produced by a backwash event. Third, plants that practice direct
recycle of filter backwash and/or thickener supernatant may exceed
their operating capacity during recycle events due to the large volume
of these streams.
ii. Data
Plants that recycle filter backwash and thickener supernatant,
directly, without recycle flow equalization or treatment, may exceed
their operating capacity during recycle events. Table IV.20 illustrates
the magnitude by which direct recycle plants may exceed their operating
capacity during recycle events. For purposes of the table, operating
capacity is assumed to be either plant design flow or average flow (see
example below). The values in the table are conservative, as they are
likely to over predict the factor by which direct recycle plants will
exceed operating capacity during recycle events. This conservatism is
due to the assumed filter backwash rate of 15 gpm/ft\2\ and the assumed
backwash duration of 15 minutes, the minimum backwash rate and duration
recommended by the Great Lakes-Upper Mississippi River Board of State
and Provincial Public Health and Environmental Managers (1997). Design
and average flow values assumed for plant operating capacity were
developed from equations presented in EPA's baseline handbook (1999g).
For purposes of this example, plant design and average flow are assumed
to equal State approved operating capacity to illustrate the potential
for plants to exceed operating capacity during recycle events. Relevant
equations and example calculations are shown below.
Example
(1) Design to average ratios:
design flow .25 mgd; ratio design flow : average flow = 3.2:1
design flow > .25 mgd to 1 mgd; ratio design flow : average flow =
2.8:1
design flow > 1 mgd to 10 mgd; ration design flow : average flow =
2.4:1
design flow > 10 mgd; ratio design flow : average flow = 2.0:1
(2) Maximum filter size: 700 sq./ft\2\ (EPA, 1998a)
(3) Backwash volume calculation:
Filter area (ft\2\) x 15 gpm/ft\2\ x 15 minutes = volume of one
backwash
(4) Design and average capacity exceedence factors:
(Backwash flow + design (or average) flow) design flow =
exceedence factor
(5) Percent Influent that is recycle:
Backwash flow (Backwash flow + design (or average flow)) =
percent of influent that is backwash
(6) Design flow = State approved operating flow
Table IV.20.--Impact of Direct Recycle
----------------------------------------------------------------------------------------------------------------
Factor Factor
design Percent design Percent
Backwash flow is influent flow is influent
Area of Volume of return exceeded that is exceeded that is
Design Number one one flow (15 Design Average by recycle by recycle
flow of filter backwash minute flow flow during (at during (at
(MGD) filters (sq. ft) (gallons) return; (gpm) (gpm) recycle design recycle average
gpm) (at flow) (at flow)
design (percent) average (percent)
flow) flow)
----------------------------------------------------------------------------------------------------------------
.033 2 5 1,125 75 23 7 4.3 77 3.6 91
.669 4 50 11,250 750 465 166 2.6 62 2.0 82
2.02 6 100 22,500 1,500 1,403 584 2.1 52 1.5 72
8.8 8 320 72,000 4,800 6,111 2,546 1.8 44 1.2 65
14.5 10 425 95,625 6,375 10,069 5,135 1.6 39 1.1 55
42.44 18 700 157,500 10,500 29,472 14,736 1.4 26 .86 42
56.23 24 700 157,500 10,500 39,048 19,524 1.3 21 .77 35
----------------------------------------------------------------------------------------------------------------
[[Page 19113]]
The purpose of Table IV.20 is to illustrate the impact direct
recycle can have on plant hydraulic loading and the factor by which
plant operating capacity can be exceeded during recycle events. As
shown in Table IV.20, a plant with two filters would process influent
at over three times its operating capacity during a recycle event. Even
if the plant reduced or eliminated its raw water influent flow for the
duration of the event, the remaining filter would be subject to a
loading rate that exceeds its operating capacity, which could harm
finished water quality.
The amount of sedimentation basin or clarification process storage
available during recycle events will have an impact on the hydraulic
loading to the filters and the performance of the sedimentation or
clarification process. The actual increase to filter loading rates may
be less than predicted in Table IV.20 due to site-specific conditions.
However, the potential for direct recycle plants to exceed operating
capacity is cause for concern because oocyst removal can be
compromised. The Agency believes 20 filters is an appropriate number
for specifying which plants are required to perform a self assessment
due to the results in Table IV.20 and the above considerations.
The importance of maintaining proper plant hydraulics has been
acknowledged, notably by Logdson (1987) who wrote, ``Both the quantity
and quality of filtered water can be affected by plant hydraulics.
Maximum hydraulic capacity is an obvious limitation. The adverse
influences of rate of flow and flow patterns on water quality may not
be so obvious, but they can be important.'' Fulton (1987) recognized
that short circuiting can diminish the performance of settling basins,
cause overloading of filters, and increase breakthrough of turbidity.
Other publications (Cleasby, 1990) recognize that settled water quality
deteriorates when the surface loading rate of sedimentation basins is
increased. Direct recycle practice can give rise to short circuiting,
cause plant operating capacity to be exceeded, and increase surface
loading rates, all of which can be detrimental to Cryptosporidium
removal.
Direct recycle practice can abruptly increase filter loading rates,
which has been shown to lower filter performance. Cleasby et al. (1963)
performed experimental runs with three pilot plant filters by
increasing the filtration rate ten, twenty-five, and fifty-percent over
various time periods and monitoring the passage of a target material
during the rate increase. Conclusions drawn from the experiments were:
(1) Disturbance in filtration rate can cause filters to pass
previously deposited material and the amount of material passed is
dependent on the magnitude of the rate disturbance;
(2) More rapid disturbances cause more material to be flushed
through the filter;
(3) The amount of material flushed through the filter is
independent, or very nearly independent of disturbance's duration, and;
(4) The amount of material flushed through the filter following a
disturbance is dependent on the type of material being filtered.
Pilot scale work was recently performed by Glasgow and Wheatley
(1998) to investigate whether surges affect filtrate quality. Effluent
turbidity and headloss within the filter media were monitored for two
pilot filter columns that were surged at different magnitudes. The
results were compared to control runs through the same pilot columns to
determine the effect of the surge. Results indicated that surging may
significantly affect full scale filter performance. Additional work is
needed to confirm these results.
Recent pilot scale work by McTigue et al. (1998) examined the
impact of doubling the filter loading instantaneously and gradually
(over an 80 minute period) on pilot filters that had been in operation
for a period of time or were ``dirty.'' The experiments showed that
Cryptosporidium removal achieved by the filters was lowered by changes
in filtration rate regardless of whether loading rate was increased
instantaneously or gradually. In the experiment, filter loading rates
of 2 gpm/ft\2\ and 4 gpm/ft\2\ were doubled in six separate test runs
to determine whether oocysts removal was affected. Results showed that
log removal of oocysts was reduced by approximately 1.5 to 2.0 logs for
when filter loading rates of 2 gpm/ft\2\ and 4 gpm/ft\2\ were either
instantaneously and gradually doubled. The report states, ``These data
clearly demonstrate that any change in filter loading rate on a filter
that is dirty presents a risk for breakthrough of Giardia and
Cryptosporidium to the finished water, should these organisms be
present in the filter.'' Effluent turbidity values remained low during
increases in filter loading rates but particle count concentrations
immediately increased with increases in loading rate. This may indicate
that turbidity is not a good indicator of oocyst passage by dirty
filters during filtration rate increases.
Results of three other pilot runs from the study showed that log
removal of oocysts did not change when the influent oocyst
concentration varied and all other treatment conditions were held
constant. A four log removal of oocysts was obtained for all three runs
despite influent oocyst concentrations of 4,610/L, 688/L, and 26/L. The
report states, ``This finding indicates that the risk for passage of
large numbers of cysts to the finished water is greater when a water
treatment plant receives a highly concentrated slug of cysts at its
intake.'' The Agency believes this is an interesting conclusion, even
though it is based on a limited number of pilot runs. If further pilot
and full-scale work verifies this finding, it indicates that log
removal of oocysts does not increase as more oocysts are loaded to
plant. Recycle of flows containing oocysts would therefore increase the
number of oocysts present in finished water, relative to the number of
oocysts that would occur were recycle not practiced, because plant
treatment efficiency would not increase to remove the additional
oocysts returned by recycle.
In summary, the Agency is concerned that direct recycle of spent
filter backwash, thickener supernatant, and liquids from dewatering
process may increase the risk of oocyst occurrence in finished water
for the following reasons:
(1) Sampling has established that oocysts occur in finished water
supplies (see Table II.6 of this preamble);
(2) Data show that oocysts occur in recycle streams;
(3) Literature indicates that hydraulically overloading the
sedimentation process, as may happen during direct recycle events, can
harm sedimentation performance;
(4) Literature indicates increasing or abruptly changing filtration
rates can lead to more material passing through filters, and;
(5) Recent pilot scale work by McTigue et al. (1998) and Glasgow
and Wheatley (1998) indicates that filter performance can be harmed by
surges and changes to filtration rate.
The Agency encourages the States to closely examine recycle self
assessments performed by direct recycle plants to determine whether
direct recycle poses an unacceptable risk to finished water quality and
public health and needs to be modified due to the considerations cited
above.
Finally, EPA realizes that State programs may use different
methodologies to set plant operating capacity. States may also apply
safety factors of different magnitudes when determining operating
capacity. The Agency does not believe it is
[[Page 19114]]
appropriate to erode any safety factor or margin of safety States
provide when setting operating capacity. Safety factors are provided
for a reason: to provide a margin of safety to public health protection
efforts. The integrity and magnitude of a safety factor should be
maintained, as it is in and of itself integral to adequate public
health protection. The fact a safety factor is applied when plant
operating capacity is set is not a justification, a priori, for
allowing plants to operate above said operating capacity during recycle
events.
EPA also acknowledges that States may use different methodologies
to set plant operating capacity. The Agency is confident that the State
programs, its partners in public health protection, set plant capacity
to provide necessary level of public health protection. The fact that
some State programs may set plant operating capacities with different
methodologies likely reflects geographical conditions and public
expectations unique to certain States and sections of the country. EPA
believes methodologies employed by the States results in establishment
of operating capacities necessary to protect public health, meet
regulatory requirements, and satisfy unique treatment needs and
considerations where they exist.
iii. Proposed Requirements
Self assessments must be performed at plants meeting all of the
following criteria and the results of the self assessment reported to
the State:
(1) Use surface water or GWUDI as a source and employ conventional
rapid granular filtration treatment;
(2) Employ of 20 or fewer filters to meet production requirements
during the highest production month in the 12 month period prior to
LT1FBR's compliance date, and;
(3) Recycle spent filter backwash or thickener supernatant directly
to the treatment process (i.e., recycle flow is returned within the
treatment process of a PWS without first passing the recycle flow
through a treatment process designed to remove solids, a raw water
storage reservoir, or some other structure with a volume equal to or
greater than the volume of spent filter backwash water produced by one
filter backwash event).
Systems are required to develop and submit a recycle self
assessment monitoring plan to the State no later than three months
after the rule's compliance date for each plant the requirements are
applicable to. At a minimum, the monitoring plan must identify the
month during which monitoring will be conducted, contain a schematic
identifying the location of raw and recycle flow monitoring devices,
describe the type of flow monitoring devices to be used, and describe
how data from the raw and recycle flow monitoring devices will be
simultaneously retrieved and recorded.
The self assessment of recycle practices shall consist of the
following five steps:
(1) From historical records, identify the month in the calendar
year preceding LT1FBR's effective date with the highest water
production.
(2) Perform the monitoring described below in the twelve month
period following submission of the monitoring plan to the State.
(3) For each day of the month identified in (1), separately monitor
source water influent flow and recycle flow before their confluence
during one filter backwash recycle event per day, at three minute
intervals during the duration of the event. Monitoring must be
performed between 7:00 a.m. and 8:00 p.m. Systems that do not have a
filter backwash recycle event every day between 7:00 am and 8:00 p.m.
must monitor one filter backwash recycle event per day, any three days
of the week, for each week during the month of monitoring, between 7:00
a.m. and 8:00 p.m. Record the time filter backwash was initiated, the
influent and recycle flow at three minute intervals during the duration
of the event, and the time the filter backwash recycle event ended.
Record the number of filters in use when the filter backwash recycle
event is monitored.
(4) Calculate the arithmetic average of all influent and recycle
flow values taken at three minute intervals in (3). Sum the arithmetic
average calculated for raw water influent and recycle flows. Record
this value and the date the monitoring was performed. This value is
referred to as event flow.
(5) After monitoring is complete, order the event flow values in
increasing order, from lowest to highest, and identify the monitoring
events in which plant operating capacity is exceeded.
Systems are required to submit a self assessment report to the
State within one month of completing the self assessment monitoring. At
a minimum, the report must provide the following information:
(1) All source and recycle flow measurements taken and the dates
they were taken. For all events monitored, report the times the filter
backwash recycle event was initiated, the flow measurements taken at
three minute intervals, and the time the filter backwash recycle event
ended. Report the number of filters in use when the backwash recycle
event is monitored.
(2) All data and calculations performed to determine whether the
plant exceeded its operating capacity. Report the number of event flows
that exceed State approved operating capacity.
(3) A plant schematic showing the origin of all recycle flows, the
hydraulic conveyance used to transport them, and their final
destination in the plant.
(4) A list of all the recycle flows and the frequency at which they
are returned to the plant.
(5) Average and maximum backwash flow through the filters and the
average and maximum duration of backwash events in minutes, for each
monitoring event, and;
(6) Typical filter run length, number of filters typically
employed, and a written summary of how filter run length is determined
(preset run time, headloss, turbidity level).
EPA is proposing that the State review all self assessments
submitted by PWSs and report to the Agency the below information as it
applies to individual plants:
(1) A finding that modifications to recycle practice are necessary,
followed by a brief description of the required change and a summary of
the reason(s) the change is required, or;
(2) A finding that changes to recycle practice are not necessary
and a brief description of the reason(s) this determination was made.
The Agency also considered requiring all recycle plants without
existing recycle flow equalization or treatment to install recycle flow
equalization. As summarized in Table IV.21, several recommendations for
recycle equalization and treatment have been provided. However, these
recommendations are based on theoretical calculations and/or limited
pilot-scale data that has not been verified by full-scale plant
performance data. The Agency currently believes insufficient data is
available to determine whether recycle flow equalization is necessary
to protect finished water quality, and, if it is, the level of
equalization required to provide protection to finished water supplies
for a wide variety of source water qualities, treatment process types,
and levels of treatment effectiveness. The Agency does not believe it
is appropriate at this time to propose a national recycle flow
equalization requirement for the following reasons:
(1) Data on the occurrence of oocysts in recycle streams, and their
impact to
[[Page 19115]]
finished water quality upon recycle, is very limited;
(2) Data that establishes the magnitude of hydraulic disruption
caused by direct recycle events for a variety of plant types, designs,
and operational practices has not been identified; without this data,
it is not possible to quantify how much treatment efficiency is reduced
by the hydraulic disruption and the number of oocysts in the recycle
flow that will enter the finished water due to the disruption. Without
this information, it is not possible to specify the level of
equalization necessary to control hydraulic disruption for a variety of
plant configurations and operational practices with any degree of
certainty and cost effectiveness, and;
(3) A uniform, national equalization standard may not be
appropriate because it would not allow consideration of site-specific
factors such as plant treatment efficiency, loading capacity of
clarification and filtration units, source water quality, and other
site-specific factors that influence the level of equalization a plant
may need to control recycle event induced hydraulic disruption.
EPA believes some plants can realize substantial benefit by
installing recycle flow equalization and will review data to determine
the need for an equalization requirement when it becomes available. The
Agency requests that commenters submit the following pilot or full-
scale data to assist its effort to conduct a thorough analysis of
equalization based upon the best available science:
(1) Data on the magnitude of hydraulic disruption caused by recycle
events and its affect on finished water turbidity and particle count
levels;
(2) Data that correlate hydraulic disruption to increased oocyst
concentration in finished water, and;
(3) Any other data commenters believe that may be appropriate to
analyze the need for equalization, and;
(4) Whether the regulation should require States to specify
modifications to recycle practice, for all plants that exceed operating
capacity during monitoring, to ensure said plants' remain below their
State approved operating capacity during recycle events.
Table IV.21--Recommended Equalization Percentages
----------------------------------------------------------------------------------------------------------------
Is recycle treatment
Source of recommendation a Equalization Percentage recommended?
----------------------------------------------------------------------------------------------------------------
Recommended Standards for Water Works. Great Lakes-- 10%....................... No.
Upper Mississippi River Board of State and
Provincial Public Health and Environmental
Managers. 1997. Albany: Health Education Services.
Removal of Cryptosporidium Oocysts by Water 10%....................... Yes. Turbidity less than 5.0
Treatment Process. Foundation for Water Research NTU or residual of 10mg/L
Limited, United Kingdom (1994). suspended solids in treated
recycle flow.
Recycle Stream Effects on Water Treatment. Use equalized, continuous Use proper waste stream
Cornwell, D., and R. Lee. 1993. Denver: AWWARF. recycle. treatment prior to recycle.
----------------------------------------------------------------------------------------------------------------
a See the reference list at the end of the preamble for complete citations.
Finally, the Agency considered requiring conventional filtration
plants that recycle within the treatment process to provide
sedimentation or more advanced recycle treatment and concluded a
national treatment requirement is inappropriate at this time due data
deficiencies. The Agency believes the following data is necessary to
determine whether recycle flow treatment is necessary to protect public
health and the requisite level of treatment:
(1) Significant amounts of additional data on the occurrence of
oocysts for a complete range of recycle streams generated by a wide
variety of source water qualities, treatment plant types, plant
operational and recycle practices, and plant treatment efficiencies;
(2) Data that correlates recycle stream oocyst occurrence to
finished water occurrence;
(3) Additional data on the ability of full-scale sedimentation
basins to remove oocysts during normal operation and during recycle
events. The Agency has identified only three full-scale studies, States
et al. (1995), Baudin and Laine (1998), and Kelly et al. (1995), that
allow quantification of oocyst removal by sedimentation basins. Pilot
scale work, such as Edzwald and Kelley (1998) and Dugan et al. (1999)
is also available, but the number of studies is not extensive. The
removal achieved by sedimentation and other clarification processes is
critical for determining the number of oocysts loaded to the filters,
the likely concentration of oocysts in various recycle streams, and the
impact recycle may have on intra-plant oocyst concentrations. Good
oocyst removal in the clarification process will remove a large
percentage of oocysts from recycle and source water flows before they
reach the filters. The amount of removal provided by primary
clarification therefore has a large influence on the level of recycle
flow treatment that may be needed to mitigate risk to finished water
quality. Given that data on oocyst removal by sedimentation and other
clarification processes is very limited, the Agency does not believe it
is possible to assess the need for recycle treatment and specify a
minimum treatment level that is meaningful for a wide variety of plant
types and recycle practices;
(4) Data regarding the ability of DAF and other clarification
processes to remove oocysts from recycle flow is very limited. This
data is important, because the Agency anticipates plants may respond to
any recycle treatment requirement by using DAF to treat recycle flow
because of the advantages it provides relative to sedimentation.
However, EPA has only identified four studies, Hall et al. (1995),
Plummer et al. (1995), Edzwald and Kelley (1998), and Alvarez et al.
(1999), that determined the ability of DAF to remove oocysts from
source water. One study, by Grubb et al. (1997), addresses the ability
of DAF to treat filter backwash waters has been identified, but
sampling for oocyst removal was not performed, although turbidity and
color removal were monitored and good results obtained. Additional data
is needed to characterize the ability of DAF to remove oocysts from
recycle flow before it can be used to meet any recycle treatment
requirement;
(5) Full-scale data on the ability of sedimentation and other
clarification processes to remove oocysts from recycle streams before
they are returned to the plant is very limited. EPA has identified two
studies, one by Cornwell and Lee (1993) and a study by Karanis et al.
(1998) that provide data regarding
[[Page 19116]]
sedimentation's ability to remove oocysts from recycle flows.
Additional information is needed to establish lower and upper bounds on
the oocyst removal sedimentation can achieve; without this data, it is
difficult to specify a feasible level of oocyst removal in a recycle
flow treatment requirement;
(6) Microfiltration and ultrafiltration membranes appear to be very
reliable at removing Cryptosporidium from source waters (Jacangelo et
al., 1995). However, the Agency has identified limited data regarding
the ability of membranes to effectively treat recycle flow, and
treatment of backwash with membranes may not be appropriate at all
locations (Thompson et al., 1995) due to incompatibility between
membrane filter material and residual treatment chemical(s) in the
backwash water. Additional information regarding the ability of
microfiltration and ultrafiltration membranes to treat recycle flow is
necessary to comprehensively evaluate their applicability, and;
(7) EPA is not aware of a surrogate, including turbidity, particle
counts, or any other common and easy to measure parameter, that can
serve as an indicator of the log removal of Cryptosporidium recycle
flow treatment units achieve. The Agency does not believe it is
economically or technically feasible to directly monitor oocyst removal
by treatment units. Without an accurate, easy to measure surrogate for
Cryptosporidium removal, the Agency does not believe it is possible to
ascertain the level of treatment recycle flow treatment units achieve
during routine operations.
Given the above limiting factors, the Agency does not believe it is
prudent to establish a national recycle flow treatment requirement
until additional data becomes available. EPA requests the following
data be submitted:
(1) Data regarding intra-plant and recycle stream occurrence of
oocysts;
(2) Information on the ability of individual treatment units of the
primary treatment train to remove oocysts during normal, hydraulically
challenged, and suboptimal chemical dose operations;
(3) Data on the ability of sedimentation and other clarification
processes to remove oocysts from a wide range of recycle streams;
(4) Data on the compatibility of specific ultrafiltration and
microfiltration membrane materials with residual chemicals that occur
in recycle streams and data regarding the performance of these membrane
materials at full and pilot scale, and;
(5) Information on potential surrogates that can be easily measured
and can accurately establish the log removal of oocysts removed by
recycle flow treatment processes.
iv. Request for Comments
EPA requests comment on the proposed requirements. The Agency also
requests comment on the following:
(1) What other parameters could be monitored or what other overall
monitoring schemes could be employed to assess whether a plant is
exceeding its operating capacity?
(2) What data should the plant report to the State as part of its
self assessment, beyond the monitoring data and other information
listed above?
(3) Is monitoring during the highest flow month appropriate? Is
monitoring during additional months necessary? Is daily monitoring
necessary or would less frequent monitoring during the month be
sufficient?
(4) Should systems be required to monitor and report turbidity
measurements from a representative filter taken immediately preceding
and after recycle events monitored during the self assessment to help
characterize the impact of recycle on plant performance?
(5) Is limiting the self assessment to plants with 20 or less
filters appropriate? Should the number of filters be less or greater
than 20? What is the appropriate number of filters?
(6) Should systems be required to monitor sedimentation overflow
rates or clarification loading rates while the recycle flow monitoring
is performed?
(7) EPA requests comment on criteria that may identify recycle
plants that could receive substantial benefit from implementing recycle
equalization or treatment as a standard practice.
(8) What type and amount of data is required to determine whether
recycle flow equalization would provide a benefit to finished water
quality? What methodology could be used to determine an appropriate
recycle flow equalization percentage, and how relevant are turbidity
and particle counts, at various locations in a plant, to assessing an
appropriate equalization percentage for a single plant or a plant type?
d. Requirements for Direct Filtration Plants that Recycle Using Surface
Water or GWUDI
i. Overview and Purpose
Today's proposal requires direct filtration plants that recycle to
report to the State whether flow equalization or treatment is provided
for recycle flow prior to its return to the treatment process. The
purpose of today's proposed requirement is to assess whether the
existing recycle practice of direct filtration plants addresses
potential risks. The Agency believes that direct filtration plants need
to remove oocysts from recycle flow prior to reintroducing it to the
treatment process.
ii. Data
Twenty-three direct filtration plants that used surface water
responded to the FAX Survey (AWWA, 1998). In the FAX survey, plants
could report whether they provide recycle flow equalization,
sedimentation, or some other type of treatment. Of the respondents, 21
reported providing treatment for the recycle flow and two plants
reported providing only equalization. In the ICR database, there were
23 direct filtration plants and fourteen of them recycled to the
treatment process. All fourteen plants provide recycle treatment. It is
not possible to determine the level of oocyst removal FAX survey and
ICR plants achieve with available data.
The treatment train of a direct filtration plant does not have a
clarification process to remove Cryptosporidium before they reach the
filters; all oocyst removal is achieved by the filters. If recycle flow
treatment is not provided, all of the oocysts captured in the filters
will be returned to the treatment process in the recycle flow. Because
a primary clarification process is not present to remove recycled
oocysts, they are caught in a closed ``loop'' from which the only exit
is passage through the filters into the distribution system. The Agency
believes direct filtration plants should provide solids removal
treatment for recycle flows to limit the number of oocysts returned to
the treatment plant.
iii. Proposed Requirements
EPA is proposing that PWSs using direct filtration that recycle to
the treatment process and utilize surface water or GWUDI as a source
report data to the State that describes their current recycle practice.
Plants should report the following information to the State:
(1) Whether recycle flow treatment or equalization is in place;
(2) The type of treatment provided for the recycle flow;
(3) If equalization, sedimentation, or some type of clarification
process is used, the following information should be provided: a)
physical dimensions of the unit (length, width, (or circumference)
depth,) sufficient to allow calculation of volume and the
[[Page 19117]]
type, typical dose, and frequency with which treatment chemicals are
used;
(4) The minimum and maximum hydraulic loading the treatment unit
experiences, and;
(5) Maximum backwash rate, duration, typical filter run length, and
the number of filters at the plant.
The State should use the above information to determine which
plants need to modify recycle practice to provide additional public
health protection. States are required to report to EPA whether they
required individual direct filtration plants to modify recycle practice
and provide a brief explanation of the reason(s) for the decision.
The Agency also considered requiring that all direct filtration
plants provide a specific level of treatment for the recycle flow.
However, data necessary to determine the appropriate level of treatment
is unavailable. Specifically, the following data is needed:
(1) Data on the on the occurrence of oocysts in the spent filter
backwash of direct filtration plants. Direct filtration plants
generally use higher quality source water than conventional plants
(AWWA, 1990) and it would be inaccurate to use spent filter backwash
occurrence data from conventional plants to assess the level of
treatment direct recycle plants may need;
(2) Data regarding the ability of sedimentation and other
clarification processes to remove oocysts from recycle flows is needed
to determine what may be a feasible level of treatment. This data need
was treated to a detailed discussion in the previous section of the
preamble;
(3) An easy to measure and accurate surrogate for oocyst removal is
currently unavailable; without such a surrogate, it is not feasible to
monitor the performance of recycle treatment units, and;
(4) Data on the applicability of microfiltration and
ultrafiltration for treating spent filter backwash produced by direct
filtration plants. This data need was discussed in detail in the
previous section.
Given the lack of oocyst occurrence data for direct filtration
recycle streams, and limited knowledge of the level of treatment
clarification processes can achieve, the Agency does not currently
believe it is possible to identify a treatment standard for direct
filtration plants.
iv. Request for Comments
EPA requests comment on the proposed requirements. The Agency also
requests comment on the following:
(1) Whether direct filtration plants should be required to provide
treatment for recycle flows;
(2) The level of treatment direct filtration plants should achieve;
(3) Data that establishes turbidity, particle counting, or some
other surrogate as an appropriate indicator of oocyst removal achieved
by recycle treatment units, and;
(4) Data on the ability of clarification processes to remove
oocysts and criteria that can be used to determine the applicability of
specific membrane materials for treatment of spent filter backwash
produced by direct filtration plants.
d. Request for Additional Comment
EPA requests comment on the following:
(1) Should the recycle of untreated clarification sludges be
allowed to continue, or should the Agency ban this practice? What
affect would a ban have on the operation of specific plant types, such
as softening plants?
(2) Is it appropriate to apply regulatory requirements to the
combined recycle flow rather than stipulating requirements for
individual recycle flows? Which flows should be regulated individually
and why?
V. State Implementation and Compliance Schedules
This section describes the regulations and other procedures and
policies States have to adopt, or have in place, to implement today's
proposed rule. States must continue to meet all other conditions of
primacy in 40 CFR part 142.
Section 1413 of the SDWA establishes requirements that a State or
eligible Indian tribe must meet to maintain primary enforcement
responsibility (primacy) for its public water systems. These include:
(1) Adopting drinking water regulations that are no less stringent than
Federal NPDWRs in effect under sections 1412(a) and 1412(b) of the Act,
(2) adopting and implementing adequate procedures for enforcement, (3)
keeping records and making reports available on activities that EPA
requires by regulation, (4) issuing variances and exemptions (if
allowed by the State) under conditions no less stringent than allowed
by sections 1415 and 1416, and (5) adopting and being capable of
implementing an adequate plan for the provision of safe drinking water
under emergency situations.
40 CFR part 142 sets out the specific program implementation
requirements for States to obtain primacy for the public water supply
supervision program, as authorized under section 1413 of the Act. In
addition to adopting the basic primacy requirements, States may be
required to adopt special primacy provisions pertaining to a specific
regulation. These regulation-specific provisions may be necessary where
implementation of the NPDWR involves activities beyond those in the
generic rule. States are required by 40 CFR 142.12 to include these
regulation-specific provisions in an application for approval of their
program revisions. These State primacy requirements apply to today's
proposed rule, along with the special primacy requirements discussed
below.
To implement today's proposed rule, States are required to adopt
revisions to Sec. 141.2--definitions; Sec. 141.32--public notification;
Sec. 141.70--general requirements; Sec. 141.73--filtration;
Sec. 141.76--recycle; Sec. 141.153--content of the reports;
Sec. 141.170--general requirements; Sec. 142.14--records kept by
States; Sec. 142.16--special primacy requirements; and a new subpart T,
consisting of Sec. 141.500 to Sec. 141.571.
A. Special State Primacy Requirements
In addition to adopting drinking water regulations at least as
stringent as the Federal regulations listed above, EPA requires that
States adopt certain additional provisions related to this regulation
to have their program revision application approved by EPA. This
information advises the regulated community of State requirements and
helps EPA in its oversight of State programs. States which require
without exception subpart H systems (all public water systems using a
surface water source or a ground water source under the direct
influence of surface water) to provide filtration, need not demonstrate
that the State program has provisions that apply to systems which do
not provide filtration treatment. However, such States must provide the
text of the State statutes or regulations which specifies that public
water systems using a source water must provide filtration.
EPA is currently developing, with stakeholders input, several
guidance documents to aid the States and water systems in implementing
today's proposed rule. This includes guidance for the following topics:
Disinfection benchmarking and profiling, Turbidity, and Filter Backwash
and Recycling. EPA will also work with States to develop a State
implementation guidance manual.
To ensure that the State program includes all the elements
necessary for a complete enforcement program, the State's application
must include the
[[Page 19118]]
following in order to obtain EPA's approval for implementing this rule:
(1) Adoption of the promulgated LT1FBR.
(2) Description of the procedures the State will use to determine
the adequacy of changes in disinfection process by systems required to
profile and benchmark under Sec. 142.16(h)(2)(ii) and how the State
will consult with PWSs to approve modifications to disinfection
practice.
(3) Description of existing or adoption of appropriate rules or
other authority under Sec. 142.16(h)(1) to require systems to
participate in a Comprehensive Technical Assistance (CTA) activity, and
the performance improvement phase of the Composite Correction Program
(CCP).
(4) Description of how the State will approve a method to calculate
the logs of inactivation for viruses for a system that uses either
chloramines or ozone for primary disinfection.
(5) For filtration technologies other than conventional filtration
treatment, direct filtration, slow sand filtration or diatomaceous
earth filtration, a description of how the State will determine under
Sec. 142.16(h)(2)(iii), that a public water system may use a filtration
technology if the PWS demonstrates to the State, using pilot plant
studies or other means, that the alternative filtration technology, in
combination with the disinfection treatment that meets the requirements
of Subpart T of this title, consistently achieves 99.9 percent removal
and/or inactivation of Giardia lamblia cysts and 99.99 percent removal
and/or inactivation of viruses, and 99 percent removal of
Cryptosporidium oocysts; and a description of how, for the system that
makes this demonstration, the State will set turbidity performance
requirements that the system must meet 95 percent of the time and that
the system may not exceed at any time a level that consistently
achieves 99.9 percent removal and/or inactivation of Giardia lamblia
cysts, 99.99 percent removal and/or inactivation of viruses, and 99
percent removal of Cryptosporidium oocysts.
(6) Description of the criteria the State will use under
Sec. 142.16(b)(2)(vi) to determine whether public water systems
completing self assessments under Sec. 141.76 (c) are required to
modify recycle practice and the criteria that will be used to specify
modifications to recycle practice.
(7) Description of the criteria the State will use under
Sec. 142.16(b)(2)(vii) to determine whether direct filtration systems
reporting data under Sec. 141.76 (d) are required to change recycle
practice and the criteria that will be used to specify changes to
recycle practice.
(8) The application must describe the criteria the State will use
under Sec. 142.16(b)(2)(viii) to determine whether public water systems
applying for a waiver to return recycle to a location other than prior
to the point of primary coagulant addition, will be granted the waiver
for an alternative recycle location.
B. State Recordkeeping Requirements
Today's rule includes changes to the existing record-keeping
provisions to implement the requirements in today's proposed rule.
States must maintain records of the following: (1) Turbidity
measurements must be kept for not less than one year;
(2) disinfectant residual measurements and other parameters
necessary to document disinfection effectiveness must be kept for not
less than one year; (3) decisions made on a system-by-system basis and
case-by-case basis under provisions of part 141, subpart H or subpart P
or subpart T; (4) records of systems consulting with the State
concerning a modification of disinfection practice (including the
status of the consultation);
(5) records of decisions that a system using alternative filtration
technologies can consistently achieve a 99 percent removal of
Cryptosporidium oocysts as well as the required levels of removal and/
or inactivation of Giardia and viruses for systems using alternative
filtration technologies, including State-set enforceable turbidity
limits for each system. A copy of the decision must be kept until the
decision is reversed or revised and the State must provide a copy of
the decision to the system, and; (6) records of systems required to do
filter self-assessments, CPE or CCP. These decision records must be
kept for 40 years (as currently required by Sec. 142.14 for other State
decision records) or until a subsequent determination is made,
whichever is shorter.
C. State Reporting Requirements
Currently States must report to EPA information under 40 CFR 142.15
regarding violations, variances and exemptions, enforcement actions and
general operations of State public water supply programs. Today's
proposal requires States to report a list of direct recycle plants
performing self assessments, whether the State required these systems
to modify recycle practice, and the reason(s)modifications were or were
not required and a list of direct filtration plants performing self
assessments, whether the State required these systems to modify recycle
practice, and the reason(s) modifications were or were not required
D. Interim Primacy
On April 28, 1998, EPA amended its State primacy regulations at 40
CFR 142.12 (63 FR 23362) (EPA 1998i) to incorporate the new process
identified in the 1996 SDWA amendments for granting primary enforcement
authority to States while their applications to modify their primacy
programs are under review. The new process grants interim primary
enforcement authority for a new or revised regulation during the period
in which EPA is making a determination with regard to primacy for that
new or revised regulation. This interim enforcement authority begins on
the date of the primacy application submission or the effective date of
the new or revised State regulation, whichever is later, and ends when
EPA makes a proposed determination. However, this interim primacy
authority is only available to a State that has primacy for every
existing national primary drinking water regulation in effect when the
new regulation is promulgated.
As a result, States that have primacy for every existing NPDWR
already in effect may obtain interim primacy for this rule, beginning
on the date that the State submits its final application for primacy
for this rule to EPA, or the effective date of its revised regulations,
whichever is later. Interim primacy is available for the following
rules:
Stage 1 Disinfectants and Disinfection Byproducts Rule
(December 16, 1998)(EPA,1998c)
Interim Enhanced Surface Water Treatment Rule (EPA,1998a)
Consumer Confidence Report Rule (EPA, 1998f)
Variances and Exemptions Rule (EPA, 1998g)
Drinking Water Contaminant Candidate List (EPA, 1998h)
Revisions to State Primacy Requirements (EPA,1998i)
Public Notification Rule (EPA, 1999i)
In addition, a State which wishes to obtain interim primacy for
future NPDWRs must obtain primacy for this rule. After the effective
date of the final rule, any State that does not have primacy for this
rule cannot obtain interim primacy for future rules.
E. Compliance Deadlines
Section 1412(b)(10) of SDWA provides that drinking water rules
become effective 36 months after promulgation unless the Administrator
[[Page 19119]]
determines that an earlier time is practicable. The Administrator may
also extend the effective date by an additional 24 months if capital
improvements are necessary. The Agency believes the three year
effective date is appropriate for all of the provisions in today's
notice except for those provisions that address the return of recycle
flows. The Agency believes providing a five year compliance period for
systems making modifications to recycle practice is appropriate and
warranted under 1412(b)(10). To effectively modify recycle practice,
capital improvements, such as installing additional equipment and/or
constructing new facilities, will likely be required. Specific examples
of potential capital improvements are installing new piping and pumps
to convey recycle flow prior to the point of primary coagulant addition
and constructing equalization basins or recycle flow treatment
facilities. A limited number of systems may be able to make operational
modifications, per the State's determination, that will effectively
address potential risks. However, the Agency believes the great
majority of systems required to either relocate their recycle return
location or modify recycle practice as directed by the State will need
to perform capital improvements. The capital improvement process is
lengthy; systems will need to engage in preliminary planning
activities, consult with State and local officials, develop engineering
and construction designs, obtain financing, and construct the
facilities. The Agency believes the widespread need that systems making
modifications to recycle practice will have for capital improvements
warrants the additional 24 months for compliance purposes. The Agency
solicits comment on the appropriateness of providing an additional two
years for compliance with the recycle provisions. EPA seeks comment on
extending the compliance deadline an extra two years because systems
are expected to make capital improvements to address recycle practice.
EPA also seeks comment on a similar two year extension to comply with
the turbidity provisions of today's proposed rule.
II. Economic Analysis
This section summarizes the Health Risk Reduction and Cost Analysis
in support of the Long Term 1 Enhanced Surface Water Treatment and
Filter Backwash Rule (LT1FBR) as required by Section 1412(b)(3)(C) of
the 1996 Amendments to the SDWA. In addition, under Executive Order
12866, Regulatory Planning and Review, EPA must estimate the costs and
benefits of LT1FBR in a Regulatory Impact Analysis (RIA) and submit the
analysis to the Office of Management and Budget (OMB) in conjunction
with publication of the proposed rule. EPA has prepared an RIA to
comply with the requirements of this Order and the SDWA Health Risk
Reduction and Cost Analysis (EPA, 1999h). The RIA has been published on
the Agency's web site, and can be found at http://www.epa.gov/safewater. The RIA can also be found in the docket for this rulemaking.
The goal of the following section is to provide an analysis of the
costs, benefits, and other impacts of the proposed rule to support
future decisions regarding the development of the LT1FBR.
A. Overview
The analysis for this rule examines the costs and benefits for five
rule provisions: filter effluent turbidity, applicability monitoring,
disinfection benchmark profiling, uncovered finish water reservoirs,
and recycle. Several options were considered for each provision. Costs
were estimated for three individual turbidity options, three profiling
options, and three applicability monitoring options. In addition, costs
were estimated for four different recycle options. All four recycle
options require spent filter backwash, thickener supernatant, and
liquids from dewatering be returned to the treatment process prior to
the point of primary coagulant addition. The extent of modifications to
recycle practice varies among the rule options.
The value of health benefits from the turbidity provision was
estimated for the preferred option. The benefits from the other rule
provisions are described qualitatively. Several non-health benefits
from this rule were also considered by EPA but were not monetized. The
non-health benefits of this rule include: avoided outbreak response
costs and possibly reduced uncertainty and averting behavior costs. By
adding the non-monetized benefits with those that are monetized, the
overall benefits of these rule options increase beyond the dollar
values reported.
Additional analysis was conducted by EPA to look at the incremental
impacts of the various rule options, impacts on households, benefits
from reductions in co-occurring contaminants, and possible increases in
risk from other contaminants. Finally, the Agency evaluated the
uncertainty regarding the risk, benefits, and cost estimates.
B. Quantifiable and Non-Quantifiable Costs
In estimating the costs of each rule option, the Agency considered
impacts on public water systems and on States (including territories
and EPA implementation in non-primacy States). The LT1FBR will result
in increased costs to public water systems for improved turbidity
treatment, applicability monitoring, disinfection benchmarking,
covering new finished water reservoirs and modification to recycle
practice. States will also face implementation costs. Most of the
provisions of this rule, except the recycle provision, apply to systems
using surface water or ground water under the direct influence of
surface water that serve less than 10,000 people. The recycle
provisions, however, apply to all surface water systems that recycle
filter backwash, thickener supernatant, or liquids from dewatering.
1. Total Annual Costs
EPA estimates that the annualized cost of the preferred
alternatives for the proposed rule will be $97.5 million. This estimate
includes capital costs for treatment changes and start-up labor costs
for monitoring and reporting activities that have been annualized
assuming a 7% discount rate and a 20-year amortization period. Other
cost estimates reported in this section also use these same
amortization assumptions. The estimated cost of the preferred
alternatives also includes annual operating and maintenance costs for
treatment changes and annual labor for turbidity monitoring activities.
The turbidity provisions (including treatment changes, monitoring,
and exceptions reporting) account for 70% ($68.6million annually) of
total costs and the recycling provisions (i.e., recycle to headworks,
self assessment, and direct filtration) account for 25% ($24.5 million
annually) of total costs. Utility expenditures for all provisions equal
almost 93% ($90.2 million annually) of total costs; State expenditures
make up the other 7% ($6.7 million annually).
To reduce the potential cost to small systems, EPA developed and
evaluated the cost implications of several regulatory alternatives for
four of the proposed LT1FBR provisions: individual filter turbidity
monitoring, applicability monitoring, disinfection benchmark profiling,
and recycle. Many of these alternatives reduce the labor burden on
small systems relative to what it would be if the proposed rule used
the same requirements as IESWTR. The total national costs previously
[[Page 19120]]
discussed only included the costs of the preferred alternatives. The
following section will describe the cost estimates for each provision
and discuss the cost of other alternatives that were considered.
2. Annual Costs of Rule Provisions
The national estimate of annual utility costs for the proposed
turbidity provisions is based on estimates of system-level costs for
the various provisions of the rule and estimates of the number of
systems expected to incur each type of cost. The following paragraphs
describe the cost estimates for each of the rule provisions.
Turbidity Provision Costs
The turbidity provisions are estimated to cost $69.0 million
annually. This cost is associated with three primary activities that
result from this provision: treatment changes, monitoring, and
exceptions reporting.
The treatment costs associated with meeting the revised turbidity
standard of 0.3 NTU or less are the main costs associated with the
turbidity provision. EPA estimates that 2,406 systems will modify their
turbidity treatment in response to this rule. These costs are estimated
to be $52.2 million annually. O&M expenditures account for 59% of
annual costs and the remain 41% percent is annualized capital costs.
In addition to the turbidity treatment costs, turbidity monitoring
costs apply to all small surface water or GWUDI systems using
conventional or direct filtration methods. There are an estimated 5,896
systems that fall under this criteria. EPA estimated the costs to
utilities for three turbidity monitoring alternatives. Alternative B,
the preferred alternative, excludes the exceptions report for an
individual filter exceeding 0.5 NTU in two consecutive measurements,
enabling systems to shift from daily to weekly analysis and review of
the monitoring data. The annualized individual filter turbidity cost to
public water systems for this preferred option is approximately $10.1
million. In contrast, under the IESWTR monitoring requirements of
Alternative A, small systems would expend $63.3 million annually for
turbidity monitoring. Alternative C, which only requires monthly
analysis is estimated to cost $5.6 million annually. The total state
turbidity start-up and monitoring annual costs are $4.98 million
annually and is assumed to be the same for all of the three
alternatives.
In addition to the turbidity treatment and monitoring costs,
individual filter turbidity exceptions are estimated to cost utilities
$120 thousand annually for the preferred option. State costs will be
approximately $1.17 million. This cost includes the annual exception
reports and annual individual filter self assessment costs. Costs are
slightly higher for the other two alternative individual filter
turbidity monitoring options because they result in increased number of
exception reports.
Disinfection Benchmarking Costs
Disinfection benchmarking involves three components: profiling,
applicability monitoring, and benchmarking. Four options were costed
for applicability monitoring. Alternative 3, which uses the critical
monitoring period, is estimated to cost less than $0.4 million
annually. This is substantially lower than the $6.0 million estimated
for Alternative 1, which has the same requirements as IESWTR.
Alternative 2 requires sampling once per quarter for 4 quarters for
systems serving 501-10,000, but allows systems under 500 to sample once
during the critical monitoring period. This option has an annualized
cost of $1.1 million. The preferred option, Alternative 4, makes it
optional to sample during the critical monitoring period and is
estimated to cost $0.04 million annualized.
Three options were considered for disinfection profiling and
benchmarking. They differed in the frequency and duration of data
collection. The preferred alternative, Alternative 2, requires weekly
monitoring for one year and is estimated to have an annualized cost of
$0.8 million. In comparison, Alternative 1 which requires daily data
collection for one year, has an annualized cost of approximately $1.3
million. The final option, Alternative 3, requires daily monitoring for
1 month and has an estimated annualized cost of $0.5 million.
State disinfection benchmarking annualized costs are estimated to
be $0.4 million. This estimate includes start-up, compliance tracking/
recordkeeping, and benchmark related costs.
Covered Finished Water Reservoir Provision Costs
The proposed LT1FBR requires that new systems cover all finished
water reservoirs, holding tanks, or other storage facilities for
finished water. Historical construction rates suggest that new
reservoirs over the next 20 years will roughly equal to five percent of
the existing number of systems. Assuming then that 580 new uncovered
finished water reservoirs would be built in the next 20 years, total
annual costs, including annualized capital costs and one year of O&M
costs are expected to be $2.6 million for this provision using a 7%
discount rate. This estimate is calculated from a projected
construction rate of new reservoirs and unit cost assumptions for
covering new finished water reservoirs.
Recycle Provision Cost
EPA considered four different regulatory options for recycle. Each
of the four options requires spent filter backwash, thickener
supernatant, and liquids from dewatering be returned prior to the point
of primary coagulant addition. Alternative 1, is estimated to result in
an annualized cost of $16.7 million. Of the total costs of this
alternative, State start-up and review costs for this alternative are
only $20 to $30 thousand annually.
Alternative 2, the preferred option, further requires that
conventional rapid granular filtration plants using surface water or
GWUDI perform a self assessment if they recycle spent filter backwash
and thickener supernatant, employ 20 or less filters, and practice
direct recycle (treatment for the recycle flow or equalization in a
basin that has a volume equal to the volume of spent filter backwash
produced by a single filter backwash event is not provided). The
results of the self assessment are reported to the State, and it
specifies whether modifications to recycle practice are necessary. PWSs
are required to implement the modification specified by the State.
Under Alternative 2, direct filtration plants are required to submit
data to the State on current recycle practice, and the State specifies
whether changes to recycle practice are required. The total annualized
cost of Alternative 2 is $17.4 to $24.5 million. $0.4 to $5.9 million
of the total annualized cost is for the direct recycle component, $0.1
to $1.7 million is for the direct filtration component, and the
remaining cost is for the requirement to return recycle prior to the
point of primary coagulant addition. Of the total costs of this
alternative, State start-up, review, and self assessment costs for this
alternative is only $115 thousand annually.
Alternative 3 contain the same requirements for direct filtration
plants and also requires the three recycle flows mentioned above be
returned prior to the point of primary coagulant addition. Direct
recycle plants are required to install equalization basins with a
volume equal to or greater than the volume produced by two filter
backwash events. The annualized cost of Alternative 3 is $55.0 to $56.7
million. Of this range, $38.1 million of
[[Page 19121]]
the annualized cost is directly associated with requiring direct
recycle plants to install equalization, and $0.1 to $1.7 million is
associated with the direct filtration component. State start-up and
self assessment costs for this alternative is $95 thousand annually.
Alternative 4 requires the three recycle flows mentioned above be
returned prior to the point of primary coagulant addition and also
requires that all systems that recycle (conventional and direct
systems) install sedimentation basins for recycle flow treatment.
Systems may also install recycle flow treatment technologies that
provide treatment capability equivalent or superior to sedimentation.
For cost estimation purposes, sedimentation basins with tube settlers
and polymer addition where used. The Agency approximated the annualized
costs of this option to be $151.8 million. The sedimentation basin
treatment requirement for conventional and direct filtration plants is
88% ($133.3 million) of the total annualized cost of Alternative 4.
State start-up and self assessment costs for this alternative is $100
thousand annually.
3. Non-Quantifiable Costs
Although EPA has estimated the cost of all the rule's components on
drinking water systems and States, there are some costs that the Agency
did not quantify. These non-quantifiable costs result from
uncertainties surrounding rule assumptions and from modeling
assumptions. For example, EPA did not estimate a cost for systems to
acquire land if they needed to build a treatment facility or
significantly expand their current facility. This was not costed
because many systems will be able to construct new treatment facilities
on land already owned by the utility. In addition, if the cost of land
was prohibitive, a system may choose another lower cost alternative
such as connecting to another source. A cost for systems choosing this
alternative is unquantified in our analysis.
C. Quantifiable and Non-Quantifiable Health Benefits
The primary benefits of today's proposed rule come from reductions
in the risks of microbial illness from drinking water. In particular,
LT1FBR focuses on reducing the risk associated with disinfection
resistant pathogens, such as Cryptosporidium. Exposure to other
pathogenic protozoa, such as Giardia, or other waterborne bacteria,
viral pathogens, and other emerging pathogens are likely to be reduced
by the provisions of this rule as well but are not quantified. In
addition, LT1FBR produces nonquantifiable benefits associated with the
risk reductions that result from the recycle provision, uncovered
reservoirs provision, including Cryptosporidium in GWUDI definition,
and including Cryptosporidium in watershed requirements for unfiltered
systems.
1. Quantified Health Benefits
a. Turbidity Provisions
The quantification of benefits from this rule is focused solely on
reductions in the risk of cryptosporidiosis. Cryptosporidiosis is an
infection caused by Cryptosporidium which is an acute, self-limiting
illness lasting 7 to 14 days with symptoms that include diarrhea,
abdominal cramping, nausea, vomiting and fever (Juranek, 1995). The
cost of illness avoided of cryptosporidiosis is estimated to have a
mean of $2,016 (Harrington et al., 1985; USEPA 1999h)
The benefits of the turbidity provisions of LT1FBR come from
improvements in filtration performance at water systems. The benefits
analysis attempts to take into account some of the uncertainties in the
analysis by estimating benefits under two different current treatment
and three improved removal assumptions. The benefits analysis also used
Monte Carlo simulations to derive a distribution of estimates, rather
than a single point estimate.
The benefits analysis focused on estimating changes in incidence of
cryptosporidiosis that would result from the rule. The analysis
included estimating the baseline (pre-LT1FBR) level of exposure from
Cryptosporidium in drinking water, reductions in such exposure
resulting from treatment changes to comply with the LT1FBR, and
resultant reductions of risk.
Baseline levels of Cryptosporidium in finished water were estimated
by assuming national source water occurrence distribution (based on
data by LeChevallier and Norton, 1995) and a national distribution of
Cryptosporidium removal by treatment.
In the LT1FBR RIA, the following two assumptions were made
regarding the current Cryptosporidium oocyst performance to estimate
finished water Cryptosporidium concentrations. First, based on
treatment removal efficiency data presented in the 1997 IEWSTR, EPA
assumed a national distribution of physical removal efficiencies with a
mean of 2.0 logs and a standard deviation of 0.63 logs.
Because the finished water concentrations of oocysts represent the
baseline against which improved removal from the LT1FBR is compared,
variations in the log removal assumption could have considerable impact
on the risk assessment. Second, to evaluate the impact of the removal
assumptions on the baseline and resulting improvements, an alternative
mean log removal/inactivation assumption of 2.5 logs and a standard
deviation of 0.63 logs was also used to calculate finished
water concentrations of Cryptosporidium.
For each of the two baseline assumptions, EPA assumed that a
certain number of plants would show low, mid or high improved removal,
depending upon factors such as water matrix conditions, filtered water
turbidity effluent levels, and coagulant treatment conditions. As a
result, the RIA considers six scenarios that encompass the range of
endemic health damages avoided based on the rule.
The finished water Cryptosporidium distributions that would result
from additional log removal with the turbidity provisions, were derived
assuming that additional log removal was dependent on current removal,
i.e., that sites currently operating at the highest filtered water
turbidity levels would show the largest improvements or high improved
removal assumption (e.g., plants now failing to meet a 0.4 NTU limit
would show greater removal improvements than plants now meeting a 0.3
NTU limit).
Table VI.1 indicates estimated annual benefits associated with
implementing the LT1FBR. The benefits analysis quantitatively examines
endemic health damages avoided based on the LT1FBR for each of the six
scenarios mentioned above. For each of these scenarios, EPA calculated
the mean of the distribution of the number of illnesses avoided. The
10th and 90th percentiles imply that there is a 10 percent chance that
the estimated value could be as low as the 10th percentile and there is
a 10 percent chance that the estimated value could be as high as the
90th percentile. EPA's Office of Water has evaluated drinking water
consumption data from USDA's 1994-1996 Continuing Survey of Food
Intakes by Individuals (CSFII) Study. EPA's analysis of the CSFII Study
resulted in a daily water ingestion lognormally distributed with a mean
of 1.2 liters per person (EPA, 2000a). The risk and benefit analysis
contained within the RIA reflects this distribution.
[[Page 19122]]
Table VI.1.--Number and Value of Illnesses Avoided Annually From Turbidity Provisions a
[Dollar amounts in billions]
----------------------------------------------------------------------------------------------------------------
Daily Drinking Water Ingestion
and Baseline Cryptosporidium Log-
Removal Assumptions (Mean = 1.2
Improved Log-Removal Assumption Liters per person)
---------------------------------
2.0 log 2.5 log
----------------------------------------------------------------------------------------------------------------
Illnesses Avoided with Low Improved Cryptosporidium Removal Assumption:
Mean...................................................................... 62,800.0 22,800.0
10th Percentile........................................................... 0.0 0.0
90th Percentile........................................................... 152,000.0 43,900.0
COI Avoided with Low Improved Cryptosporidium Removal Assumption:
Mean...................................................................... $150.3 $53.9
10th Percentile........................................................... $0.0 $0.0
90th Percentile........................................................... $288.2 $81.4
Illnesses Avoided with Mid Improved Cryptosporidium Removal Assumption:
Mean...................................................................... 77,500.0 27,900.0
10th Percentile........................................................... 0.0 .00
90th Percentile........................................................... 184,000.0 52,900.0
COI Avoided with Mid Improved Cryptosporidium Removal Assumption:
Mean...................................................................... $185.3 $66.2
10th Percentile........................................................... $0.0 $0.0
90th Percentile........................................................... $350.9 $98.8
Illnesses Avoided with High Improved Cryptosporidium Removal Assumption:
Mean...................................................................... 83,600.0 30,000.0
10th Percentile........................................................... 0.0 0.0
90th Percentile........................................................... 196,000.0 56,500.0
COI Avoided with High Improved Cryptosporidium Removal Assumption:
Mean...................................................................... $199.5 $71.1
10th Percentile........................................................... $0.0 $0.0
90th Percentile........................................................... $376.7 $105.8
----------------------------------------------------------------------------------------------------------------
a All values presented are in January 1999 dollars.
According to the RIA performed for the LT1FBR published today, the
rule is estimated to reduce the mean annual number of illnesses caused
by Cryptosporidium in water systems with improved filtration
performance by 22,800 to 83,600 cases depending upon which of the six
baseline and improved Cryptosporidium removal assumptions was used, and
assuming the 1.2 liter drinking water consumption distribution. Based
on these values, the mean estimated annual benefits of reducing the
illnesses ranges from $54 million to $200 million per year. The RIA
also indicated that the rule could result in a mean reduction of 3 to
10 fatalities each year, depending upon the varied baseline and
improved removal assumptions. Using a mean value of $5.7 million per
statistical life saved, reducing these fatalities could produce
benefits in the range of $16.0 million to $60 million.
Combining the value of illnesses and mortalities avoided, the total
benefits range from $70 million to $260 million assuming a 1.2 liter
drinking water consumption distribution.
b. Sensitivity Analysis for Recycle Provisions
Available literature research demonstrates that increased hydraulic
loading or disruptive hydraulic currents, such as may be experienced
when plants exceed State-approved operating capacity or when recycle is
returned directly into the sedimentation basin, can disrupt filter
(Cleasby, 1963; Glasgow and Wheatley, 1998; McTigue et al, 1998) and
sedimentation (Fulton, 1987; Logsdon, 1987; Cleasby, 1990) performance.
However, the literature does not quantify the extent to which
performance can be lowered and, more specifically, does not quantify
the log reduction in Cryptosporidium removal that may be experienced
during direct recycle events.
In the absence of quantified log reduction data, the Agency
performed a sensitivity analysis to estimate a range of potential
benefit provided by the recycle provisions. The analysis assumes a
baseline Cryptosporidium log removal value of 2.0. The analysis
estimates the effect of recycle by reducing the average baseline log
removal by a range of values (reduction ranged from 0.05 to 0.50 log)
to account for the reduction in removal performance plants may
experience if they exceed State-approved operating capacity or return
recycle to the sedimentation basin. The installation of equalization to
eliminate exceedence of State-approved operating capacity or moving the
recycle return location from the sedimentation basin to prior to the
point of primary coagulant addition will result in the health benefit.
The benefit estimate is conservative, because it does not account for
the fact that recycle returns additional oocysts to the plant.
Benefits are estimated by assuming that the installation of
equalization or moving the recycle return point prior to the point of
primary coagulant addition will return the plant to the baseline
Cryptosporidium removal of 2.0 log. The difference between the number
of illnesses that result from the baseline situation and the reduced
performance is used to calculate the monetary benefit. The benefit is
compared to the cost of returning recycle prior to the point of primary
coagulant additional and the cost of installing equalization for two
service populations. Service populations of 1,900 persons, which
represents a plant serving fewer than 10,000 people, and a service
population of 25,108, which represents a plant serving greater than
10,000 people, are used. Results are summarized in Tables IV.2 and IV.3
below.
[[Page 19123]]
Table IV.2.--Benefit for Service Population of 1,900
----------------------------------------------------------------------------------------------------------------
Benefit a for Cost a of
Log removal reduction population of Cost a of installing
1,900 moving recycle equalization
-------------------------------------------------------------------------------------return---------------------
0.05......................................................... $1,400 $5,200 $25,200
0.50......................................................... 30,700 5,200 25,200
----------------------------------------------------------------------------------------------------------------
a Cost and benefit are annualized with a 7% capital cost over 20 years.
Table IV.3.--Benefit Range for Service Population of 25,108
----------------------------------------------------------------------------------------------------------------
Benefit a for Cost a of
Log removal reduction population of Cost a of installing
25,108 moving recycle rqualization
-------------------------------------------------------------------------------------return---------------------
0.05......................................................... $18,700 $18,700 $57,200
0.50......................................................... 405,800 18,700 57,200
----------------------------------------------------------------------------------------------------------------
a Cost and benefit are annualized with a 7% capital cost over 20 years.
Although literature research does not quantify the log reduction
caused by specific recycle practices, the results of the sensitivity
analysis show that the benefit a plant serving 25,108 people would
realize by improving its baseline performance to 2.0 logs would range
from $18,700 to $405,800. $27,256 Benefits would range from $1,400 to
$30,700 for a plant serving 1,900. This benefit range supports the
Agency's determination that unquantified benefits will justify costs.
The determination is discussed in the Benefit Cost Determination
section.
2. Non-Quantified Health and Non-Health Related Benefits
a. Recycle Provisions
The benefits associated with the filter backwash provision are
unquantified because of data limitations. Specifically, there is a lack
of treatment performance data to accurately model the oocysts removal
achieved by individual full-scale treatment processes and the impact
recycle may have on treatment unit performance and finished water
quality. Additional data on the ability of unit processes
(sedimentation, DAF, contact clarification, filtration) to remove
oocysts from source and recycle flows, the extent to which recycle may
generate hydraulic surge within plants and lower the performance of
individual treatment processes, data on the potential for recycle to
threaten the integrity of chemical treatment, and additional
information on the occurrence of oocysts in recycle streams are all
needed before an impact model can be calibrated and used as a
predictive tool.
However, available data demonstrate that oocysts occur in recycle
streams, often at concentrations higher than found in source water, and
returning recycle streams to the plant will increase intra-plant oocyst
concentrations. Data also shows that oocysts frequently occur in the
finished water of treatment plants that are not operating under
stressed conditions. Engineering literature also shows that proper
coagulation and the maintenance of balanced hydraulic conditions within
the plant (i.e., not exceeding State approved sedimentation/
clarification and filtration operating rates) are important to protect
the integrity of the entire treatment process. Some recycle practices,
such as direct recycle, can potentially upset coagulation and the
proper hydraulic operation of sedimentation/clarification and
filtration processes. The benefits of the recycle provisions are
derived from protecting the coagulation process and the hydraulic
performance of sedimentation/clarification and filtration processes.
Today's recycle provisions reduce the risk posed by recycle and
provided additional public health protection in the following ways:
(1) Returning spent filter backwash, thickener supernatant, and
liquids from dewatering into, or downstream of, the point of primary
coagulant addition may disrupt treatment chemistry by introducing
residual coagulant or other treatment chemicals to the process stream.
The wide variation in plant influent flow can also result in chemical
over-or under-dosing if chemical dosage is not adjusted to account for
flow variation. Returning the above flows prior to the point of primary
coagulant addition will help protect the integrity of coagulation and
protect the performance of downstream unit processes, such as
clarification and filtration, that require proper coagulation be
conducted to maintain proper performance. This will provide an
additional measure of public health protection.
(2) The direct recycle of spent filter backwash without first
providing treatment, equalization, or some form of hydraulic detention
for the flow, may cause plants to exceed State-approved operating
capacity during recycle events. This may lead to lower overall oocyst
removal performance due to the hydraulic overload unit processes (i.e.,
clarification and filtration) experience and increase finished water
oocyst concentrations. The self assessment provision in today's rule
will help the States identify direct recycle systems that may
experience this problem so modifications to recycle practice can be
made to protect public health.
(3) Direct filtration plants do not employ a sedimentation basin in
their primary treatment process to remove solids and oocysts; all
oocyst removal is achieved by the filters. If treatment for the recycle
flow is not provided prior to its return to the plant, all of the
oocysts captured by a filter during a filter run will be returned to
the plant and again loaded to the filters. This may lead to ever
increasing levels of oocysts being applied to the filters and could
increase the concentration of oocysts in finished water. Today's
provision for direct recycle systems will help States identify those
systems that are not obtaining sufficient oocyst removal from the
recycle flow. Public health protection will be increased when systems
implement modifications to recycle practice specified by the State.
The goal of the recycle provisions is to reduce the potential for
oocysts getting into the finished water and causing cases of
cryptosporidiosis. Other disinfection resistant pathogens may also be
removed more efficiently due to implementation of these provisions.
[[Page 19124]]
b. Issues Associated With Unquantified Benefits
The monetized benefits from filter performance improvements are
likely not to fully capture all the benefits of the turbidity
provisions. EPA monetized the benefits from reductions in
cryptosporidiosis by using cost-of-illness (COI) estimates. This may
underestimate the actual benefits of these reductions because COI
estimates do not include pain and suffering. In general, the COI
approach is considered a lower bound estimate of willingness-to-pay
(WTP) to avoid illnesses. EPA requests comment on the use of an
appropriate WTP study to calculate the benefits of this rule.
Several non-health benefits from this rule were also considered by
EPA but were not monetized. The non-health benefits of this rule
include avoided outbreak response costs and possibly reduced
uncertainty and averting behavior costs. By adding the non-monetized
benefits with those that are monetized, the overall benefits of this
rule would increase beyond the dollar values reported.
D. Incremental Costs and Benefits
EPA evaluated the incremental or marginal costs of today's proposed
turbidity option by analyzing various turbidity limits, 0.3 NTU, 0.2
NTU, and 0.1 NTU. For each turbidity limit, EPA developed assumptions
about which process changes systems might implement to meet the
turbidity level and how many systems would adopt each change. The
comparison of total compliance cost estimates show that costs are
expected to increase significantly across turbidity limits. The total
cost of a 0.1 NTU limit, $404.6 million, is almost eight times higher
than the cost of the 0.3 NTU limit, which is $52.2 million. Similarly,
the total cost of the 0.2 NTU limit, $134.1 million, is more than twice
as great as the 0.3 NTU cost.
Analytical limitations in the estimation of the benefits of LT1FBR
prevent the Agency from quantitatively describing the incremental
benefits of alternatives. The Agency requests comment on how to analyze
and the appropriateness of analyzing incremental benefits and costs for
treatment techniques that address microbial contaminants.
E. Impacts on Households
The cost impact of LT1FBR at the household level was also assessed.
Household costs are a way to represent water system treatment costs as
costs to the system's customers. As expected, costs per household
increase as system size decreases. Costs to households are higher for
households served by smaller systems than larger systems for two
reasons. First, smaller systems serve far fewer households than larger
systems, and consequently, each household must bear a greater
percentage share of capital and O&M costs. Second, filter backwash
recycling may pose a greater risk because the flow of water from filter
backwash recycling is a larger portion of the total water flow in
smaller systems. This greater risk potential in small systems makes it
more likely that some form of recycle treatment might be needed.
The average (mean) annual cost for the turbidity, benchmarking, and
covered finished water provision per household is $8.66. For almost 86
percent of the 6.6 million households affected by these provisions, the
per-household costs are $10 per year or less, and costs of $120 per
year (i.e., $10 per month) or less for approximately 99 percent of the
households. Costs exceeding $500 per household occur only for the
smallest size category, and the number of affected households represent
about 34 of the smallest systems. The highest per-household cost
estimate is $2,177. This extreme estimate, however, is an artifact of
the way the system cost distribution was generated. It is unlikely that
any small system will incur annual costs of this magnitude because less
costly options are available.
The average household cost for the recycle provisions is $1.80 per
year for households that are served by systems that recycle. The cost
per household is less than $10 per year for almost 99% of 12.9 million
households potentially affected by the proposed rule. The cost per
household exceeds $120 per year for less than 1800 households and it
exceeds $500 per year for approximately 100 households. The maximum
cost of $1,238 per year would only be incurred if a direct filtration
system that serves less than 100 customers installed a sedimentation
basin for backwash treatment.
There are approximately 1.5 million households served by small
drinking water systems that may be affected by the recycling provisions
in addition to the turbidity, benchmarking, and covered finished water
provisions. The expected aggregate annual cost to these households can
be approximated by the sum of the expected cost for each distribution,
which is $10.45 per year.
The assumptions and structure of this analysis tend to overestimate
the highest costs. To face the highest household costs, a system would
have to implement all, or almost all, of the treatment activities.
These systems, however, might seek less costly alternatives, such as
connecting into a larger regional water system.
F. Benefits From the Reduction of Co-Occurring Contaminants
If a system chooses to install treatment, it may choose a
technology that would also address other drinking water contaminants.
For example, some membrane technologies installed to remove bacteria or
viruses can reduce or eliminate many other drinking water contaminants
including arsenic.
The technologies used to reduce individual filter turbidities have
the potential to reduce concentrations of other pollutants as well.
Reduction in turbidity that result from today's proposed rule are aimed
at reducing Cryptosporidium by physical removal. It is reasonable to
assume that similar microbial contaminants will also be reduced as a
result of improvements in turbidity removal. Health risks from Giardia
lamblia and emerging disinfection resistant pathogens, such as
microsporidia, Toxoplasma, and Cyclospora, are also likely to be
reduced as a result of improvements in turbidity removal and recycle
practices. The frequency and extent that LT1FBR would reduce risk from
other contaminants has not been quantitatively evaluated because of the
Agency's lack of data on the removal efficiencies of various
technologies for emerging pathogens and the lack of co-occurrence data
for microbial pathogens and other contaminants from drink water
systems.
G. Risk Increases From Other Contaminants
It is unlikely that LT1FBR will result in any increased risk from
other contaminants. Improvements in plant turbidity performance will
not result in any increases in risk. In addition, the benchmarking and
profiling provisions were designed to minimize the potential reductions
in microbial disinfection in order to lower disinfection byproduct
levels to comply with the Stage 1 Disinfection Byproducts Rule.
Furthermore, the filter backwash provision does not potentially
increase the risk from other contaminants.
H. Other Factors: Uncertainty in Risk, Benefits, and Cost Estimates
There is uncertainty in the baseline number of systems, the risk
calculation, and the cost estimates. Many of these uncertainties are
discussed in more detail in previous sections of today's proposal.
[[Page 19125]]
First, the baseline number of systems is uncertain because of data
limitation problems in SDWIS. For example, some systems use both ground
and surface water but because of other regulatory requirements are
labeled in SDWIS as surface water. Therefore, EPA does not have a
reliable estimate of how many of these mixed systems exist. The SDWIS
data on non-community water systems does not have a consistent
reporting convention for population served. Some states may report the
population served over the course of a year, while others may report
the population served on an average day. Also, SDWIS does not require
states to provide information on current filtration practices and, in
some cases, it may overestimate the daily population served. For
example, a park may report the population served yearly instead of
daily. EPA is looking at new approaches to address these issues and
both are discussed below in request for comment.
Second, there are several important sources of uncertainty that
enter the benefits assessment. They include the following:
Occurrence of Cryptosporidium oocysts in source waters
Baseline occurrence of Cryptosporidium oocysts in finished
waters
Reduction of Cryptosporidium oocysts due to improved
treatment, including filtration and disinfection
Viability of Cryptosporidium oocysts after treatment
Infectivity of Cryptosporidium
Incidence of infections (including impact of under
reporting)
Characterization of the risk Willingness-to-pay to reduce
risk and avoid costs.
The baseline water system treatment efficiency for the
removal of Cryptosporidium is uncertain. Turbidity measurements have
been used as a means of estimating removal treatment efficiency (i.e.
log removal). In addition to the baseline treatment efficiency
estimates, improvements in treatment efficiency for Cryptosporidium
removal that result from this rule are uncertain.
The benefit analysis incorporates all of the uncertainties
associated with the benefits assessment in either the Monte Carlo
simulations or the assumption of two baselines--2.0 log removal and 2.5
log removal. The results in table VI.1 show that benefits are more
sensitive to the baseline log removal assumptions than the range of low
to high improved removal assumptions. Third, some costs of today's
proposed rule are uncertain because of the diverse nature of the
modifications that may be made to address turbidity limits. Cost
analysis uncertainties are primarily caused by assumptions made about
how many systems will be affected by various provisions and how they
will likely respond. Capital and O&M expenditures account for a
majority of total costs. EPA derived these costs for a ``model'' system
in each size category using engineering models, best professional
judgement, and existing cost and technology documents. Costs for
systems affected by the proposed rule could be higher or lower, which
would affect total costs. Also, the filter backwash provision's
flexibility for States to assess plants' need to modify recycle
practices leads to some uncertainty in the estimates of how many plants
will have to potentially install some form of recycle equalization or
treatment. These uncertainties could either under or overestimate the
costs of the rule.
I. Benefit Cost Determination
The Agency has determined that the benefits of the LT1FBR justify
the costs. EPA made this determination for both the LT1 and the FBR
portions of the rule separately as described below.
The Agency has determined that the benefits of the LT1 provisions
justify their costs on a quantitative basis. The LT1 provisions include
enhanced filtration, disinfection benchmarking and other non-recycle
related provisions. The quantified benefits of $70 million to $259.4
million annually exceed the costs of $73 million at the seven percent
cost of capital over a substantial portion of the range of benefits. In
addition, the non-quantified benefits include avoided outbreak response
costs and possibly reduced uncertainty and averting behavior costs.
The Agency has determined that the benefits of the recycle
provisions (FBR) justify their cost on a qualitative basis. The recycle
provisions will reduce the potential for certain recycle practices to
lower or upset treatment plant performance during recycle events; the
provisions will therefore help prevent Cryptosporidium oocysts from
entering finished drinking water supplies and will increase public
health protection.
The Agency strongly believes that returning Cryptosporidium to the
treatment process in recycle flows, if performed improperly, can create
additional public health risk. The Agency holds this belief for three
reasons. First, returning recycle flow directly to the plant, without
equalization or treatment, can cause large variations in the influent
flow magnitude and influent water quality. If chemical dosing is not
adjusted to reflect this, less than optimal chemical dosing can occur,
which may lower the performance of sedimentation and filtration.
Returning recycle flows prior to the point of primary coagulant
addition will help diminish the risk of less than optimal chemical
dosing and diminished sedimentation and filtration performance. Second,
exceeding State-approved operating capacity, which is likely to occur
if recycle equalization or treatment is not in place, can hydraulically
overload plants and diminish the ability of individual unit processes
to remove Cryptosporidium. Exceeding approved operating capacity
violates fundamental engineering principles and water treatment
objectives. States set limits on plant operating capacity and loading
rates for individual unit processes to ensure treatment plants and
individual treatment processes are operated to within their
capabilities so that necessary levels of public health protection are
provided. Third, returning recycle flows directly into flocculation or
sedimentation basins, which can generate disruptive hydraulic currents,
may lower the performance of these units and increase the risk of
Cryptosporidium in finished water supplies.
The recycle provisions in today's proposal are designed to address
those recycle practices that are inconsistent with fundamental
engineering and water treatment principles. The objective of the
provisions is to eliminate practices that are counter to common sense,
sound engineering judgement, and that create additional and preventable
risk to public health. EPA believes the public health protection
benefit provided by the recycle provisions justifies their cost because
they are based upon sound engineering principles and are designed to
eliminate recycle practices that are very likely to create additional
public health risk.
J. Request for Comment
Pursuant to Section 3142(b)(3)(C), the Agency requests comment on
all aspects of the rule's economic impact analysis. Specifically, EPA
seeks input into the following two issues.
NTNC and TNC Flow Estimates
As part of the total cost estimates for LT1FBR, EPA estimated the
cost of the rule on NTNC and TNC water systems by using flow models.
However, these flow models were developed to estimate flows only for
CWS and they may not accurately represent the much smaller flows
generally found in NTNC and TNC systems. The effect of the overestimate
in flow would be to inflate
[[Page 19126]]
the cost of the rule for these systems. The Agency requests comment on
an alternative flow analysis for NTNC and TNC water systems described
below.
Instead of using the population served to determine the average
flow for use in the rule's cost calculations, this alternative approach
would re-categorize NTNC and TNC water systems based on service type
(e.g., restaurants or parks). Service type would be obtained from SDWIS
data. However, service type data is not always available because it is
a voluntary SDWIS data field. Where unavailable, the service type would
be assigned based on statistical analysis. Estimates of service type
design flows would be obtained from engineering design manuals and best
professional judgement if no design manual specifications exist.
In addition, each service type category would also have
corresponding rates for average population served and average water
consumption. These would be used to determine contaminant exposure
which is used in the benefit determination. For example, schools and
churches would be two separate service type categories. They each would
have their own corresponding average design flow, average population
served (rather than the population as reported in SDWIS), and average
water consumption rates. These elements could be used to estimate a
rule's benefits and costs for the average church and the average
school.
Mixed Systems
Current regulations require that all systems that use any amount of
surface water as a source be categorized as surface water systems. This
classification applies even if the majority of water in a system is
from a ground water source. Therefore, SDWIS does not provide the
Agency with information to identify how many mixed systems exist. This
information would help the Agency to better understand regulatory
impacts.
EPA is investigating ways to identify how many mixed systems exist
and how many mix their ground and surface water sources at the same
entry point or at separate entry points within the same distribution
systems. For example, a system may have several plants/entry points
that feed the same distribution system. One of these entry points may
mix and treat surface water with ground water prior to its entry into
the distribution system. Another entry point might use ground water
exclusively for its source while a different entry point would
exclusively use surface water. However, all three entry points would
supply the same system classified in SDWIS as surface water.
One method EPA could use to address this issue would be to analyze
CWSS data then extrapolate this information to SDWIS to obtain a
national estimate of mixed systems. CWSS data, from approximately 1,900
systems, details sources of supply at the level of the entry point to
the distribution system and further subdivides flow by source type. The
Agency is considering this national estimate of mixed systems to
regroup surface water systems for certain impact analyses when
regulations only impact one type of source. For example, surface water
systems that get more than fifty percent of their flow from ground
water would be counted as a ground water system in the regulatory
impact analysis for this rule. The Agency requests comment on this
methodology and its applicability for use in regulatory impact
analysis.
VII. Other Requirements
A. Regulatory Flexibility Act (RFA), as amended by the Small Business
Regulatory Enforcement Fairness Act of 1996 (SBREFA), 5 USC 601 et seq.
1. Background
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 Procedure 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.
2. Use of Alternative Definition
The RFA provides default definitions for each type of small entity.
It also authorizes an agency to use alternative definitions for each
category of small entity, ``which are appropriate to the activities of
the agency'' after proposing the alternative definition(s) in the
Federal Register and taking comment. 5 U.S.C. secs. 601(3)-(5). In
addition to the above, to establish an alternative small business
definition, agencies must consult with SBA's Chief Counsel for
Advocacy.
EPA is proposing the LT1FBR which contains provisions which apply
to small PWSs serving fewer than 10,000 persons. This is the cut-off
level specified by Congress in the 1996 Amendments to the Safe Drinking
Water Act for small system flexibility provisions. Because this
definition does not correspond to the definitions of ``small'' for
small businesses, governments, and non-profit organizations, EPA
requested comment on an alternative definition of ``small entity'' in
the preamble to the proposed Consumer Confidence Report (CCR)
regulation (63 FR 7620, February 13, 1998). Comments showed that
stakeholders support the proposed alternative definition. EPA also
consulted with the SBA Office of Advocacy on the definition as it
relates to small business analysis. In the preamble to the final CCR
regulation (63 FR 4511, August 19, 1998). EPA stated its intent to
establish this alternative definition for regulatory flexibility
assessments under the RFA for all drinking water regulations and has
thus used it in this proposed rulemaking.
In accordance with Section 603 of the RFA, EPA prepared an initial
regulatory flexibility analysis (IRFA) that examines the impact of the
proposed rule on small entities along with regulatory alternatives that
could reduce that impact. The IRFA is available for review in the
docket and is summarized below.
3. Initial Regulatory Flexibility Analysis
As part of the 1996 amendments to the Safe Drinking Water Act
(SDWA), Congress required the U.S. Environmental Protection Agency
(EPA) to develop a Long Term Stage 1 Enhanced Surface Water Treatment
Rule (LT1ESWTR) under Section 1412(b)(2)(C) which focuses on surface
water drinking water systems that serve fewer than 10,000 persons.
Congress also required EPA to develop a companion Filter Backwash
Recycle Rule (FBRR) under Section 1412(b)(14) which will require that
all surface water public water systems, regardless of size, meet new
requirements governing the recycle of filter backwash within the
drinking water treatment process. The goal of both the LT1ESWTR and the
related FBRR is to provide additional protection from disease-causing
microbial pathogens for community and non-community public water
systems (PWSs) utilizing surface water.
For purposes of assessing the impacts of today's rule on small
entities, small entity is defined by systems serving fewer than 10,000
people. The small entities directly regulated by this proposed rule are
surface water and systems using ground water under the direct influence
of surface water (GWUDI), using filtration and serving fewer than
10,000 people. We have determined that the final rule would result in
approximately 2,400 systems needing capital improvement to meet the
turbidity requirements, approximately 3,360 systems would need to
significantly change their
[[Page 19127]]
disinfection practices, and approximately 790 systems would need to
make capital improvements to change the location of return of their
filter backwash recycle stream. A discussion of the impacts on small
entities is described in more detail in chapters six and seven of the
Regulatory Impact Analysis of the LT1FBR (EPA, 1999).
The following recordkeeping and reporting burdens were projected in
the IRFA:
Turbidity Monitoring and Reporting Costs
Utility monitoring activities at the plant level include data
collection, data review, data reporting and monthly reporting to the
State. The labor burden hours for data collection and review were
calculated under the assumption that plants are using on-line
monitoring, in the form of a SCADA or other automated data collection
system. The data collection process requires that a plant engineer
gather and organize turbidimeter readings from the SCADA output and
enter them into either a spreadsheet or a log once per 8-hour shift
(three times per day).
After data retrieval, the turbidity data from each turbidimeter
will be reviewed by a plant engineer once per 8-hour shift (three times
per day) to ensure that the filters are functioning properly and are
not displaying erratic or exceptional patterns. A monthly summary data
report would be prepared. This task involves the review of daily
spreadsheets and the compilation of a summary report. It is assumed to
take one employee 8 hours per month to prepare. Recordkeeping is
expected to take 5 hours per month. Recordkeeping entails organizing
daily monitoring spreadsheets and monthly summary reports.
Plant-level data will also be reviewed monthly at the system level
to ensure that each plant in a system is in compliance with the rule. A
system-level manager or technical worker will review the daily
monitoring spreadsheets and monthly summary reports that are generated
at the plant level. This task is estimated to take about 4 hours per
month. Once the plant-level data have been reviewed, the system manager
or technical worker will also compile a monthly system summary report.
These reports are estimated to take 4 hours each month to prepare.
Disinfection Benchmarking Monitoring and Reporting Costs
It is assumed that all Subpart H systems currently collect the
daily inactivation data required to generate a disinfection profile, in
either an electronic or paper format, and therefore would not incur
additional data collection expenses due to microbial profiling. Costs
per plant are divided into costs per plant using paper data, costs per
plant using mainframe data and costs per plant using PC data. Plants
with paper data were assumed to represent half of the number of plants
needing benchmarking, while plants with mainframe and plants with PC
data each represent a quarter.
Filter Backwash Monitoring and Reporting Costs
The proposed requirements are as follows: All subpart H systems,
regardless of size, that use conventional rapid granular filtration,
and that return spent filter backwash, thickener supernatant, or
liquids from dewatering process to submit a schematic diagram to the
State showing their intended changes to move the return location above
the point of primary coagulant addition.
All subpart H systems, regardless of size, that use conventional
rapid granular filtration and employ 20 or fewer filters during the
highest production month and that use direct recycling, to perform a
self assessment of their recycle practice and report the results to the
State.
All subpart H systems, regardless of system size that use direct
filtration must submit a report of their recycling practices to the
State. The State would then determine whether changes in recycling
practices were warranted.
EPA believes that the skill level required for compliance with all
of the above recordkeeping, reporting and other compliance activities
are similar or equivalent to the skill level required to pass the first
level of operator certification required by most States.
Relevant Federal Rules
EPA has issued a Stage 1 Disinfectants/Disinfection Byproducts Rule
(DBPR) along with an Interim Enhanced Surface Water Treatment Rule
(IESWTR) in December 1998, as required by the Safe Drinking Water Act
Amendments of 1996. EPA proposed these rules in July 1994. The Stage 1
DBPR includes a THM MCL of 0.080 mg/L (reduced from the existing THM
MCL of 0.10 mg/L established in 1979) and an MCL of 0.060 mg/L for five
haloacetic acids (another group of chlorination) as well as MCLs for
chlorite (1.0 mg/L) and bromate (0.010 mg/L) byproducts. The Stage 1
DBPR also finalized MRDLs for chlorine (4 mg/L as Cl2),
chloramine (4 mg/L as Cl2) and chlorine dioxide (0.8 mg/L as
ClO2).
In addition, the Stage 1 DBPR includes requirements for enhanced
coagulation to reduce the concentration of TOC in the water and thereby
reduce DBP formation potential. The IESWTR was proposed to improve
control of microbial pathogens and to control potential risk trade-offs
related to the need to meet lower DBP levels under the Stage 1 DBPR.
None of these regulations duplicate, overlap or conflict with this
proposed rule.
Significant Alternatives
As a result of consultations during the SBREFA process, and public
meetings held subsequently, EPA has developed several alternative
options to those presented in the IRFA, and has selected preferred
alternatives for each of the turbidity, disinfection benchmarking and
filter backwash recycle provisions. These alternatives were developed
based on feedback from small system operators and trade associations
and are designed to protect public health, while minimizing the burden
to small systems. In summary, the proposed turbidity requirements are
structured to require recordkeeping once a week as opposed to daily
which was written in the IRFA; the proposed disinfection profile
requirements are structured to be taken once per week, as opposed to
daily which was written in the IRFA; and the filter backwash
requirements have been scaled back significantly from those included in
the IRFA, i.e. a ban on recycle is no longer being considered, nor are
several treatment techniques now being considered that were in the IRFA
prior to discussions with stakeholders. The provisions being proposed
are: systems that recycle will be required to return recycle flows
prior to the rapid mix unit; direct recycle systems will need to
perform a self assessment to determine whether capacity is exceeded
during recycle events, and States will determine whether recycle
practices need to be changed based on the self-assessment; and direct
filtration systems will need to report their recycle practices to the
State, which will determine whether changes to recycle practices are
required.
4. Small Entity Outreach and Small Business Advocacy Review Panel
As required by section 609(b) of the RFA, as amended by SBREFA, EPA
also conducted outreach to small entities and convened a Small Business
Advocacy Review Panel to obtain advice and recommendations of
representatives of the small entities that potentially would be subject
to the rule's
[[Page 19128]]
requirements. The SBAR Panel produced two final reports; one for the
LT1 provisions and the other for the filter backwash provisions.
Although the LT1 and filter backwash provisions have since been
combined into the same rule, the projected economic impact of the
provisions have not significantly changed, and the relevance of SERs'
comments has not been affected.
The Agency invited 24 SERs to participate in the SBREFA process,
and 16 agreed to participate. The SERs were provided with background
information on the Safe Drinking Water Act and the LT1FBR in
preparation for a teleconference on April 28, 1998. This information
package included data on options as well as preliminary unit costs for
treatment enhancements under consideration. Eight SERs provided
comments on these materials.
On August 25, 1998, EPA's Small Business Advocacy Chair person
convened the Panel under section 609(b) of the Regulatory Flexibility
Act as amended by the Small Business Regulatory Enforcement Fairness
Act (SBREFA). In addition to its chairperson, the Panel consisted of
the Director of the Standards and Risk Management Division of the
Office of Ground Water and Drinking Water within EPA's Office of Water,
the Administrator of the Office of Information and Regulatory Affairs
within the Office of Management and Budget, and the Chief Counsel for
Advocacy of the Small Business Administration. The SBAR Panels reports,
Final Report of the SBREFA Small Business Advocacy Review Panel on
EPA's Planned Proposed Rule: Long Term 1 Enhanced Surface Water
Treatment (EPA, 1998k) and the Final Report of the SBREFA Small
Business Advocacy Review Panel on EPA's Planned Proposed Rule: Filter
Backwash Recycling (EPA, 1998l), contain the SERs comments on the
components of the LT1FBR.
The SERs were provided with additional information on potential
costs related to LT1FBR regulatory options during teleconferences on
September 22 and 25, 1998. Nine SERs provided additional comments
during the September 22 teleconference, four SERs provided additional
comments during the September 25 teleconference, and three SERs
provided written comment on these materials.
In general, the SERs that were consulted on the LT1FBR were
concerned about the impact of the proposed rule on small water systems
(because of their small staff and limited budgets), small systems'
ability to acquire the technical and financial capability to implement
requirements, and maintaining flexibility to tailor requirements to the
needs and limitations of small systems. Consistent with the RFA/SBREFA
requirements, the Panel evaluated the assembled materials and small-
entity comments on issues related to the elements of the IRFA. The
background information provided to the SBAR Panel and the SERs are
available for review in the water docket. A copy of the Panel report is
also included in the docket for this proposed rule. The Panel's
recommendations to address the SERs concerns are described next.
a. Number of Small Entities Affected
When the IRFA was prepared, EPA initially estimated that there were
5,165 small public water systems that use surface water or GWUDI. A
more detailed discussion of the impact of the proposed rule and the
number of entities affected is found in Section VI. None of the
commenters questioned the information provided by EPA on the number and
types of small entities which may be impacted by the LT1FBR. This
information is based upon the national Safe Drinking Water Information
System (SDWIS) database, which contains data on all public water
systems in the country. The Panel believed this was a reasonable data
source to characterize the number and types of systems impacted by the
proposed rule.
b. Recordkeeping and Reporting
The Panel noted that some small systems are operated by a sole,
part time operator with many duties beyond operating and maintaining
the drinking water treatment system and that several components of the
proposed rule may require significant additional operator time to
implement. These included disinfection profiling, individual filter
monitoring, and ensuring that short-term turbidity spikes are corrected
quickly.
One SER stated that assumptions can be made that small systems will
have to add an additional person to comply with the monitoring and
recordkeeping portions of the rule. Another SER commented that the most
viable and economical option would be to use circuit riders (a trained
operator who travels between plants) to fill staffing needs, but the
LT1FBR would increase the amount of time that a circuit rider would be
required to spend at each plant. An additional option recommended by
several SERs to reduce monitoring burden and cost was to allow the use
of one on-line turbidimeter to measure several filters. This would
entail less frequent monitoring of each filter but might still be
adequate to ensure that individual filter performance is maintained.
The proposed LT1FBR takes into consideration the recordkeeping and
reporting concerns identified by the Panel and the SERs. For example,
initially the Agency considered requiring systems to develop a profile
of individual filter performance. Based on concerns from the SERs this
requirement was eliminated. In addition, the Agency initially
considered requiring operators to record pH, temperature, residual
chlorine and peak hourly flow every day. This requirement has been
scaled back to once per week to meet difficulties faced by small system
operators. Finally, in today's proposed rule the Agency is requesting
comment on a modification to allow one on-line turbidimeter instead of
several to be used at the smallest size systems (systems serving fewer
than 100 people).
c. Interaction With Other Federal Rules
The Panel noted that the LT1FBR and Stage 1 DBP rules will affect
small systems virtually simultaneously and that the Agency should
analyze the net impact of these rules and consider regulatory options
that would minimize the impact on small systems.
One SER commented that any added responsibility or workload due to
regulations will have to be absorbed by him and his staff. He noted
that many systems, including his own, are losing staff through
attrition and are unable to hire replacements. The SER stated that he
hoped the Panel was aware of the volume of rules and regulations to
which small systems are currently subject. As an example, the SER
stated that he had spent a week's time collecting samples for the
mandated tests of the Lead and Copper rule. He noted that the sampling
had delayed important maintenance to his system by over a month.
The Agency considered these comments when developing the
requirements of today's proposed rule, and developed the alternatives
with the realization that small systems will be required to implement
several rules in a short time frame. In today's proposed rule, the
preferred options attempt to minimize the impact on small systems by
reducing the amount of monitoring and the amount of operator's time
necessary to collect and analyze data. For example, under the IESWTR,
large systems are required to monitor disinfection byproducts for 1
year to determine whether or not they must develop a disinfection
profile (based on
[[Page 19129]]
daily measurements of operating conditions). In response to SERs
concerns, the Agency is proposing to eliminate the requirement for
disinfection byproduct monitoring all together. Under the proposed
requirements, all systems would develop a disinfection profile based on
weekly measurements of operating parameters for 1 year. Overall, this
will save small system operators both time and money. The proposed rule
also requests comment on several additional strategies for reducing
impacts.
d. Significant Alternatives
During the SBAR panel several alternatives were discussed with the
Panel and SERs. These alternatives and the Panel's recommendations are
discussed next.
i. Turbidity Provisions
During the SBAR Panel, the Agency presented the IESWTR turbidity
provisions as appropriate components for the LT1FBR. The Panel noted
that one SER commented that it was a fair assumption that turbidity up
to 1 NTU maximum and 0.3 NTU in 95% of all monthly samples is a good
indicator of two log removal of Cryptosporidium, but stressed the need
to allow operators adequate time to respond to exceedances in automated
systems. They were referring to the fact the small system operators are
often away from the plant performing other duties, and cannot respond
immediately if the turbidity levels exceed a predetermined level. The
Panel recommended that EPA consider this limitation when developing
reporting and recordkeeping requirements.
The Panel also noted that another SER agreed that lowered turbidity
level is a good indicator of overall plant performance but thought the
0.3 NTU limit for the 95th percentile reading was too low in light of
studies which appear to show variability and inaccuracies in low level
turbidity measurements. This SER referenced specific data suggesting
that current equipment used to measure turbidity levels below the 0.3
NTU may nonetheless give readings above 0.3 which would put the system
out of compliance. EPA has evaluated this issue in the context of the
1997 IESWTR FACA negotiations and believes that readings below the 0.3
NTU are reliable. Moreover, EPA notes that the SERs' concern was based
on raw performance evaluation data that had not been fully analyzed.
Finally, the Panel recognized that several SERs supported
individual filter monitoring, provided there was flexibility for short
duration turbidity spikes. Other SERs, however, noted that the
assumption that individual filter monitoring was necessary was
unreasonable. The Panel recommended that EPA consider the likelihood
and significance of short duration spikes (i.e., during the first 15-30
minutes of filter operation) when evaluating the frequency of
individual filter monitoring and reporting requirements and the number
and types of exceedances that will trigger requirements for
Comprehensive Performance Evaluations (CPEs). The Panel also noted the
concern expressed by several SERs that individual filter monitoring may
not be practical or feasible in all situations.
The Agency has structured today's proposed rule with an emphasis on
providing flexibility for small systems. The individual filter
provisions have been tailored to be easier to understand and implement
and require less data analysis. For example, the operator can look at
monitoring data once per week under this rule, as opposed to having to
review turbidity data every day as the larger systems are required to
do. The proposed rule also requests comment on several modifications to
provide additional flexibility to small systems.
ii. Disinfection Benchmarking: Applicability Monitoring Provisions
None of the SERs commented specifically on the applicability
monitoring provisions which are designed to identify systems that may
consider cutting back on their disinfection doses in order to avoid
problems with disinfection byproducts formation. The Panel noted,
however, that burden on small systems might be reduced if alternative
applicability monitoring provisions were adopted. In consideration of
the Panel's suggestions, the Agency first considered limiting the
applicability monitoring, and has now eliminated this requirement from
the proposal. It is optional, however, for systems who believe their
disinfection byproduct levels are below 80% of the MCL--as required
under the Stage 1 DBPR.
The Panel noted SER comments that monitoring and computing Giardia
lamblia inactivation on a daily basis for a year would place a heavy
burden on operators that may only staff the plant for a few hours per
day. The Panel therefore recommended that EPA consider alternative
profiling strategies which ensure adequate public health protection,
but will minimize monitoring and recordkeeping requirements for small
system operators.
The Agency considered several alternatives to the profile
development strategies, and decided to propose that systems perform the
necessary monitoring and record the results once per week, instead of
every day as the larger systems are required to do. This will
significantly reduce burden and costs for small systems.
iii. Recycling Provisions
During the SBAR Panel, the Agency proposed several alternatives for
consideration in the LT1FBR including a ban on recycle, a requirement
to return recycle flow to the head of the plant, recycle flow
equalization, and recycle flow treatment. The Panel noted the concern
of the SERs regarding a ban on the recycle of filter backwash water.
These concerns included the expense of filter backwash disposal and the
economic and operational concerns of western and southwestern drinking
water systems which depend on recycled flow to maintain adequate
supply. The Panel strongly recommended that EPA explore alternatives to
an outright ban on the recycle of filter backwash and other recycle
flows.
The Panel noted that SERs supported a requirement that all recycled
water be reintroduced at the head of the plant. This was considered an
element of sound engineering practice. The Panel recommended that EPA
consider including such a requirement in the proposed rule, and
investigate whether there are small systems for which such a
requirement would present a significant financial and operational
burden.
The Panel noted that SERs agreed with the appropriateness of flow
equalization for filter backwash. The Panel supported the concept of
flow equalization as a means to minimize hydraulic surges that may be
caused by recycle and the reintroduction of a large number of
Cryptosporidium oocysts or other pathogenic contaminants to the plant
in a brief period of time. The Panel noted that there are various ways
of achieving flow equalization and suggested that specific requirements
remain flexible.
The Panel noted the concerns of SERs regarding installation of
treatment, solely for the purpose of treating filter backwash water
and/or recycle streams may be costly and potentially prohibitive for
small systems. The Agency addressed this concern by allowing the States
to determine whether recycle flow equalization or treatment is
necessary based on the results of the self assessment prepared by the
system rather than requiring universal flow equalization or treatment.
This will allow site-specific
[[Page 19130]]
factors to be considered and help minimize cost and burden.
e. Other Comments
The Panel also noted the concern of several SERs that flexibility
be provided in the compliance schedule of the rule. SERs noted the
technical and financial limitations that some small systems will have
to address, the significant learning curve for operators with limited
experience, and the need to continue providing uninterrupted service as
reasons why additional compliance time may be needed for small systems.
The panel encouraged EPA to keep these limitations in mind in
developing the proposed rule and provide as much compliance flexibility
to small systems as is allowable under the SDWA. We invite comments on
all aspects of the proposal and its impacts on small entities.
The Agency structured the timing of the LT1ESWTR provisions
specifically to follow the promulgation of the IESWTR. Since the IESWTR
served as a template for the establishment of the LT1ESWTR provisions,
the Agency decided that small systems would have an advantage by giving
them an opportunity to see what was in the rule, and how it was
implemented by larger systems.
Under SDWA, systems have 3 years to comply with the requirements of
the final rule. If capital improvements are necessary for a particular
PWS, a State may allow the system up to an additional 2 years to comply
with the regulation. The Agency is developing guidance manuals to
assist the compliance efforts of small entities.
B. 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 by EPA
(ICR No. 1928.01) and a copy may be obtained from Sandy Farmer by mail
at OP Regulatory Information Division; U.S. Environmental Protection
Agency (2137); 401 M St., S.W.; 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. For
technical information about the collection contact Jini Mohanty by
calling (202) 260-6415.
The information collected as a result of this rule will allow the
States and EPA to determine appropriate requirements for specific
systems, in some cases, and to evaluate compliance with the rule. For
the first three years after the effective date (six years after
promulgation) of the LT1FBR, the major information requirements are (1)
monitor filter performance and submit any exceedances of turbidity
requirements (i.e. exceptions reports) to the State; (2) develop a 1
month recycle monitoring plan and submit both plan and results to the
State; (3) submit flow monitoring plan and results to the State; and
(4) report data on current recycle treatment (self assessment) to the
State. The information collection requirements in Part 141, for
systems, and Part 142, for States are mandatory. The information
collected is not confidential.
Burden means the total time, effort, or financial resources
expended by persons to generate, maintain, retain, or disclose or
provide information to or for a Federal Agency. This includes the time
needed to review instructions; develop, acquire, install, and utilize
technology and systems for the purposes of collecting, validating, and
verifying information, processing and maintaining information, and
disclosing and providing information; adjust the existing ways to
comply with any previously applicable instructions and requirements;
train personnel to be able to respond to a collection of information;
search data sources; complete and review the collection of information;
and transmit or otherwise disclose the information.
The preliminary estimate of aggregate annual average burden hours
for LT1FBR is 311,486. Annual average aggregate cost estimate is
$10,826,919 for labor, $2,713,815 for capital, and $1,898,595 for
operation and maintenance including lab costs which is a purchase of
service. The burden hours per response is 18.9. The frequency of
response (average responses per respondent) is 2.7 annually. The
estimated number of likely respondents is 6,019 (the product of burden
hours per response, frequency, and respondents does not total the
annual average burden hours due to rounding). Most of the regulatory
provisions discussed in this notice entail new reporting and
recordkeeping requirements for States, Tribes, and members of the
regulated public. An Agency may not conduct or sponsor, and a person is
not required to respond to a collection of information unless it
displays a currently valid OMB control number. The OMB control numbers
for EPA's regulations are listed in 40 CFR Part 9 and 48 CFR Chapter
15.
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, OP Regulatory Information Division; U.S. Environmental
Protection Agency (2137); 401 M St., S.W.; 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 April 10, 2000, a comment to OMB is
best assured of having its full effect if OMB receives it by May 10,
2000. The final rule will respond to any OMB or public comments on the
information collection requirements contained in this proposal.
C. Unfunded Mandates Reform Act
1. Summary of UMRA requirements
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 UMRA section 202, 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 by 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 final 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 notification to
potentially affected small governments, enabling officials of
[[Page 19131]]
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.
2. Written Statement for Rules With Federal Mandates of $100 Million or
More
EPA has determined that this rule does not contain a Federal
mandate that may result in expenditures of $100 million or more for the
State, local and Tribal governments, in the aggregate, or the private
sector in any one year. Thus today's rule is not subject to the
requirements of sections 202 and 205 of the UMRA. Nevertheless, since
the estimate of annual impact is close to $100 million under certain
assumptions EPA has prepared a written statement, which is summarized
below, even though one is not required. A more detailed description of
this analysis is presented in EPA's Regulatory Impact Analysis of the
LT1FBR (EPA, 1999h) which is available for public review in the Office
of Water docket under docket number W-99-10. The document is available
for inspection from 9 a.m. to 4 p.m., Monday through Friday, excluding
legal holidays. The docket is located in room EB 57, USEPA
Headquarters, 401 M St. SW, Washington, D.C. 20460. For access to
docket materials, please call (202) 260-3027 to schedule an
appointment.
a. Authorizing Legislation
Today's rule is proposed pursuant to Section 1412 (b)(2)(C) and
1412(b)(14) of the SDWA. Section 1412 (b)(2)(C) directs EPA to
establish a series of regulations including an interim and final
enhanced surface water treatment rule. Section 1412(b)(14) directs EPA
to promulgate a regulation to govern the recycling of filter backwash
water. EPA intends to finalize the LT1FBR in the year 2000 to allow
systems to consider the dual impact of this rule and the Stage 1 DBP
rule on their capital investment decisions.
b. Cost Benefit Analysis
Section VI of this preamble discusses the cost and benefits
associated with the LT1FBR. Also, the EPA's Regulatory Impact Analysis
of the LT1FBR (EPA, 1999h) contains a detailed cost benefit analysis.
Today's proposal is expected to have a total annualized cost of
approximately $ 97.5 million using a 7 percent discount rate. At a 3
percent discount rate the annualized costs drop to $87.6 million. The
national cost estimate includes cost for all of the rule's major
provisions including turbidity monitoring, disinfection benchmarking
monitoring, disinfection profiling, covered finished storage, and
recycling. The majority of the costs for this rule will be incurred by
the public sector. A more detailed discussion of these costs is located
in Section VI of this preamble.
In addition, the regulatory impact analysis includes both monetized
benefits and descriptions of unquantified benefits for improvements to
public health and safety the rule will achieve. Because of scientific
uncertainty regarding LT1FBR's exposure and risk assessment, the Agency
has used Monte Carlo methods and sensitivity analysis to assess the
quantified benefits of today's rule. The monetary analysis was based
upon quantification of the number of cryptosporidiosis illnesses
avoided due to improved particulate removal that results from the
turbidity provisions. The Agency was not able to monetize the benefits
from the other rule provisions such as disinfection benchmarking and
covered finished storage. The monetized annual benefits of today's rule
range from $70.1 million to $259.4 million depending on the baseline
and removal assumptions. Better management of recycle streams required
by the proposal also result in nonquantifiable health risk reductions
from disinfection resistant pathogens. The rule may also decrease
illness caused by Giardia and other emerging disinfection resistant
pathogens, further increasing the benefits.
Several non-health benefits from this rule were also identified by
EPA but were not monetized. The non-health benefits of this rule
include outbreak response costs avoided, and possibly reduced
uncertainty and averting behavior costs. By adding the non-monetized
benefits with those that are monetized, the overall benefits of this
rule increase beyond the dollar values reported.
Various Federal programs exist to provide financial assistance to
State, local, and Tribal governments in complying with this rule. The
Federal government provides funding to States that have primary
enforcement responsibility for their drinking water programs through
the Public Water Systems Supervision Grants program. Additional funding
is available from other programs administered either by EPA, or other
Federal Agencies. These include EPA's Drinking Water State Revolving
Fund (DWSRF), U.S. Department of Agriculture's Rural Utilities' Loan
and Grant Program, and Housing and Urban Development's Community
Development Block Grant Program.
For example, SDWA authorizes the Administrator of the EPA to award
capitalization grants to States, which in turn can provide low cost
loans and other types of assistance to eligible public water systems.
The DWSRF helps public water systems finance the cost of infrastructure
necessary to achieve or maintain compliance with SDWA requirements.
Each State has considerable flexibility to design its program and to
direct funding toward the most pressing compliance and public health
protection needs. States may also, on a matching basis, use up to ten
percent of their DWSRF allotments each fiscal year to run the State
drinking water program.
Furthermore, a State can use the financial resources of the DWSRF
to assist small systems. In fact, a minimum of 15% of a State's DWSRF
grant must be used to provide infrastructure loans to small systems.
Two percent of the State's grant may be used to provide technical
assistance to small systems. For small systems that are disadvantaged,
up to 30% of a State's DWSRF may be used for increased loan subsidies.
Under the DWSRF, Tribes have a separate set-aside which they can use.
In addition to the DWSRF, money is available from the Department of
Agriculture's Rural Utility Service (RUS) and Housing and Urban
Development's Community Block Grant (CDBG) program. RUS provides loans,
guaranteed loans, and grants to improve, repair, or construct water
supply and distribution systems in rural areas and towns up to 10,000
people. In fiscal year 1997, the RUS had over $1.3 billion in available
funds. Also, three sources of funding exist under the CDBG program to
finance building and improvements of public faculties such as water
systems. The three sources of funding include: (1) Direct grants to
communities with populations over 200,000; (2) direct grants to States,
which they in turn award to smaller communities, rural areas, and
colonias in Arizona, California, New Mexico, and Texas; and (3) direct
grants to US. Territories and Trusts. The CDBG budget for fiscal year
1997 totaled over $4 billion dollars.
c. Estimates of Future Compliance Costs and Disproportionate Budgetary
Effects
To meet the UMRA requirement in section 202, EPA analyzed future
compliance costs and possible disproportionate budgetary effects. The
Agency believes that the cost estimates, indicated previously and
discussed in
[[Page 19132]]
more detail in Section VI of this preamble, accurately characterize
future compliance costs.
In analyzing the disproportionate impacts, EPA considered four
measures:
(1) The impacts of small versus large systems and the impacts
within the five small system size categories;
(2) The costs to public versus private water systems;
(3) The costs to households, and;
(4) The distribution of costs across States.
First, small systems will experience a greater impact than large
systems under LT1FBR because large systems are subject only to the
recycle provisions. The Interim Enhanced Surface Water Treatment Rule
(IESWTR) promulgated turbidity, benchmarking, and covered finished
storage provisions for large systems in December, 1998. However, small
systems have realized cost savings over time due to their exclusion
from the IESWTR. Also, some provisions in the LT1FBR have been modified
so they would not be as burdensome for small systems. Further
information on these changes can be found in section VII.A.3.of this
proposal.
The second measure of impact is the relative total cost to
privately owned water systems compared to the incurred by publicly
owned water systems. A majority of the systems are publicly owned (60
percent of the total). As a result, publicly owned systems will incur a
larger share of the total costs of the rule.
The third measure, household costs, is described in further detail
in VI.E of this preamble. The fourth measure, distribution of costs
across States, is described in greater detail in the RIA for today's
proposed rule (EPA, 1999h). There is nothing to suggest that costs to
individual systems would vary significantly from State to State, but as
expected, the States with the greatest number of systems experience the
greatest costs.
d. Macro-Economic Effects
As required under UMRA Section 202, EPA is required to estimate the
potential macro-economic effects of the regulation. These types of
effects include those on productivity, economic growth, full
employment, creation of productive jobs, and international
competitiveness. Macro-economic effects tend to be measurable in
nationwide econometric models only if the economic impact of the
regulation reaches 0.25 percent to 0.5 percent of Gross Domestic
Product (GDP). In 1998, real GDP was $7,552 billion. This proposal
would have to cost at least $18 billion to have a measurable effect. A
regulation of less cost is unlikely to have any measurable effect
unless it is highly focused on a particular geographic region or
economic sector. The macro-economic effects on the national economy
from LT1FBR should not have a measurable effect because the total
annual cost of the preferred option is approximately $ 97.5 million per
year (at a seven percent discount rate). The costs are not expected to
be highly focused on a particular geographic region or sector.
e. Summary of EPA's Consultation with State, Local, and Tribal
Governments and Their Concerns
Consistent with the intergovernmental consultation provisions of
section 204 of UMRA EPA has already initiated consultation with the
governmental entities affected by this rule.
EPA began outreach efforts to develop the LT1FBR in the summer of
1998. Two public stakeholder meetings, which were announced in the
Federal Register, were held on July 22-23, 1998, in Lakewood, Colorado,
and on March 3-4, 1999, in Dallas, Texas. In addition to these
meetings, EPA has held several formal and informal meetings with
stakeholders including the Association of State Drinking Water
Administrators. A summary of each meeting and attendees is available in
the public docket for this rule. EPA also convened a Small Business
Advocacy Review (SBAR) Panel in accordance with the Regulatory
Flexibility Act (RFA), as amended by the Small Business Regulatory
Enforcement Fairness Act (SBREFA) to address small entity concerns
including those of small local governments. The SBAR Panel allows small
regulated entities to provide input to EPA early in the regulatory
development process. In early June, 1999, EPA mailed an informal draft
of the LT1FBR preamble to the approximately 100 stakeholders who
attended one of the public stakeholder meetings. Members of trade
associations and the SBREFA Panel also received the draft preamble. EPA
received valuable comments and stakeholder input from 15 State
representatives, trade associations, environmental interest groups, and
individual stakeholders. The majority of concerns dealt with reducing
burden on small systems and maintaining flexibility. After receipt of
comments, EPA made every effort to make modifications to address these
concerns.
To inform and involve Tribal governments in the rulemaking process,
EPA presented the LT1FBR at three venues: the 16th Annual Consumer
Conference of the National Indian Health Board, the annual conference
of the National Tribal Environmental Council, and the OGWDW/Inter
Tribal Council of Arizona, Inc. tribal consultation meeting. Over 900
attendees representing tribes from across the country attended the
National Indian Health Board's Consumer Conference and over 100 tribes
were represented at the annual conference of the National Tribal
Environmental Council. At both conferences, an OGWDW representative
conducted two workshops on EPA's drinking water program and upcoming
regulations, including the LT1FBR.
At the OGWDW/Inter Tribal Council of Arizona meeting,
representatives from 15 tribes participated. The presentation materials
and meeting summary were sent to over 500 tribes and tribal
organizations. Additionally, EPA contacted each of our 12 Native
American Drinking Water State Revolving Fund Advisors to invite them,
and representatives of their organizations to the stakeholder meetings
described previously. A list of tribal representatives contacted can be
found in the docket for this rule.
The primary concern expressed by State, local and Tribal
governments is the difficulty the smallest systems will encounter in
adequately staffing drinking water treatment facilities to perform the
monitoring and reporting associated with the new requirements. Today's
proposal attempts to minimize the monitoring and reporting burden to
the greatest extent feasible and still accomplish the rule's objective
of protecting public health. The Agency believes the monitoring and
reporting requirements are necessary to ensure consumers served by
small systems receive the same level of public health protection as
consumers served by large systems. Summaries of the meetings have been
included in the public docket for this rulemaking.
f. Regulatory Alternatives Considered
As required under Section 205 of the UMRA, EPA considered several
regulatory alternatives for individual filter monitoring and
disinfection benchmarking, as well as several alternative strategies
for addressing recycle practices. A detailed discussion of these
alternatives can be found in Section IV and also in the RIA for today's
proposed rule (EPA, 1999h). Today's proposal also seeks comment on
several regulatory alternatives that EPA will consider for the final
rule.
[[Page 19133]]
g. Selection of the Least Costly, Most-Cost Effective or Least
Burdensome Alternative That Achieves the Objectives of the Rule
As discussed previously, EPA has considered and requested comment
on various regulatory options that would reduce Cryptosporidium
occurrence in the finished water of surface water systems. The Agency
believes that the preferred option for turbidity performance,
disinfection benchmarking, and recycle management are the most cost
effective combination of options to achieve the rule's objective; the
reduction of illness and death from Cryptosporidium occurrence in the
finished water of PWSs using surface water. The Agency will carefully
review comments on the proposal and assess suggested changes to the
requirements.
3. Impacts on Small Governments
In developing this proposal, EPA consulted with small governments
to address impacts of regulatory requirements in the rule that might
significantly or uniquely affect small governments. As discussed
previously, a variety of stakeholders, including small governments,
were provided the opportunity for timely and meaningful participation
in the regulatory development process through the SBREFA panel, public
stakeholder and Tribal meetings. EPA used these processes to notify
potentially affected small governments of regulatory requirements being
considered and provided officials of affected small governments with an
opportunity to have meaningful and timely input to the regulatory
development process.
In addition, EPA will educate, inform, and advise small systems,
including those run by small governments, about LT1FBR requirements.
One of the most important components of this outreach effort will be
the Small Entity Compliance Guide, required by the Small Business
Regulatory Enforcement Fairness Act of 1996. This plain-English guide
will explain what actions a small entity must take to comply with the
rule. Also, the Agency is developing fact sheets that concisely
describe various aspects and requirements of the LT1FBR and detailed
guidance manuals to assist the compliance effort of PWSs and small
government entities.
D. National Technology Transfer and Advancement Act
Section 12(d) of the National Technology Transfer and Advancement
Act of 1995 (NTAA), Public Law No. 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, business practices) that are developed or adopted
by voluntary consensus standards bodies. The NTAA directs EPA to
provide Congress, through the Office of Management and Budget,
explanations when the Agency decides not to use available and
applicable voluntary consensus standards.
Today's rule requires the use of previously approved technical
standards for the measurement of turbidity. In previous rulemakings,
EPA approved three methods for measuring turbidity in drinking water.
These can be found in 40 CFR, Part 141.74 (a). Turbidity is a method-
defined parameter and therefore modifications to any of the three
approved methods requires prior EPA approval. One of the approved
methods was published by the Standard Methods Committee of American
Public Health Association, the American Water Works Association, and
the Water Environment Federation, the latter being a voluntary
consensus standard body. That method, Method 2130B (APHA, 1995), is
published in Standard Methods for the Examination of Water and
Wastewater (19th ed.). Standard Methods is a widely used reference
which has been peer-reviewed by the scientific community. In addition
to this voluntary consensus standard, EPA approved two additional
methods for the measurement of turbidity. One is the Great Lakes
Instrument Method 2, which can be used as an alternate test procedure
for the measurement of turbidity (Great Lakes Instruments, 1992).
Second, the Agency approved revised EPA Method 180.1 for turbidity
measurement in August 1993 in Methods for the Determination of
Inorganic Substances in Environmental Samples (EPA-600/R-93-100) (EPA,
1993).
In 1994, EPA reviewed and rejected an additional technical
standard, a voluntary consensus standard, for the measurement of
turbidity, the ISO 7027 standard, an analytical method which measures
turbidity at a higher wavelength than the approved test measurement
standards. ISO 7027 measures turbidity using either 90 deg. scattered
or transmitted light depending on the turbidity concentration
evaluated. Although instruments conforming to ISO 7027 specifications
are similar to the GLI instrument, only the GLI instrument uses pulsed,
multiple detectors to simultaneously read both 90 deg. scattered and
transmitted light. EPA has no data upon which to evaluate whether the
separate 90 deg. scattered or transmitted light measurement
evaluations, according to the ISO 7027 method, would produce results
that are equivalent to results produced using GLI Method 2, Standard
Method 2130B (APHA, 1995), or EPA Method 180.1 (EPA, 1993).
Today's proposed rule also requires continuous individual filter
monitoring for turbidity and requires PWSs to calibrate the individual
turbidimeter according to the turbidimeter manufacturer's instructions.
These calibration instructions may constitute technical standards as
that term is defined in the NTTAA. EPA has looked for voluntary
consensus standards with regard to calibration of turbidimeters. The
American Society for Testing and Materials (ASTM) is developing such
voluntary consensus standards, however, there do not appear to be any
voluntary consensus standards available at this time. 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 plans to implement in the future a performance-based
measurement system (PBMS) that would allow the option of using either
performance criteria or reference methods in its drinking water
regulatory programs. The Agency is currently determining the specific
steps necessary to implement PBMS in its programs and preparing an
implementation plan. Final decisions have not yet been made concerning
the implementation of PBMS in water programs. However, EPA is currently
evaluating what relevant performance characteristics should be
specified for monitoring methods used in the water programs under a
PBMS approach to ensure adequate data quality. EPA would then specify
performance requirements in its regulations to ensure that any method
used for determination of a regulated analyte is at least equivalent to
the performance achieved by other currently approved methods.
Once EPA has made its final determinations regarding implementation
of PBMS in programs under the Safe Drinking Water Act, EPA would
incorporate specific provisions of PBMS into its regulations, which may
include specification of the performance characteristics for
measurement of regulated contaminants in the drinking water program
regulations.
[[Page 19134]]
E. Executive Order 12866: Regulatory Planning and Review
Under Executive Order 12866, (58 FR 51735 (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, 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 entitlement, 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.
Pursuant to the terms of Executive Order 12866, it has been
determined that this rule is a ``significant regulatory action.'' As
such, this action was submitted to OMB for review. Changes made in
response to OMB suggestions or recommendations will be documented in
the public record.
F. Executive Order 12898: Environmental Justice
Executive Order 12898 establishes a Federal policy for
incorporating environmental justice into Federal agency missions by
directing agencies to identify and address disproportionately high and
adverse human health or environmental effects of its programs,
policies, and activities on minority and low-income populations. The
Agency has considered environmental justice related issues concerning
the potential impacts of this action and consulted with minority and
low-income stakeholders.
This preamble has discussed many times how the IESWTR served as a
template for the development of the LT1FBR. As such, the Agency also
built on the efforts conducted during the IESWTRs development to comply
with E.O. 12898. On March 12, 1998, the Agency held a stakeholder
meeting to address various components of pending drinking water
regulations and how they may impact sensitive sub-populations, minority
populations, and low-income populations. Topics discussed included
treatment techniques, costs and benefits, data quality, health effects,
and the regulatory process. Participants included national, State,
tribal, municipal, and individual stakeholders. EPA conducted the
meetings by video conference call between eleven cities. This meeting
was a continuation of stakeholder meetings that started in 1995 to
obtain input on the Agency's Drinking Water Programs. The major
objectives for the March 12, 1998 meeting were:
(1) Solicit ideas from stakeholders on known issues concerning
current drinking water regulatory efforts;
(2) Identify key issues of concern to stakeholders, and;
(3) Receive suggestions from stakeholders concerning ways to
increase representation of communities in OGWDW regulatory efforts.
In addition, EPA developed a plain-English guide specifically for
this meeting to assist stakeholders in understanding the multiple and
sometimes complex issues surrounding drinking water regulation.
The LT1FBR applies to community water systems, non-transient non-
community water systems, and transient non-community water systems that
use surface water or ground water under the direct influence (GWUDI) as
their source water for PWSs serving less than 10,000 people. The
recycle provisions apply to all conventional and direct surface water
or GWUDI systems regardless of size.
EPA believes this rule will provide equal health protection for all
minority and low-income populations served by systems regulated under
this rule from exposure to microbial contamination. These requirements
will also be consistent with the protection already afforded to people
being served by systems with larger population bases.
G. 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 E.O. 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.
While this proposed rule is not subject to the Executive Order
because it is not economically significant as defined by E.O. 12866, we
nonetheless have reason to believe that the environmental health or
safety risk addressed by this action may have a disproportionate effect
on children. Accordingly, EPA evaluated available data on the health
effect of Cryptosporidium on children. The results of this evaluation
are contained in Section II.B of this preamble and in the LT1FBR RIA
(EPA, 1999h). A copy of the RIA and supporting documents is available
for public review in the Office of Water docket at 401 M St. SW,
Washington, D.C.
The risk of illness and death due to cryptosporidiosis depends on
several factors, including the age, nutrition, exposure, and the immune
status of the individual. Information on mortality from diarrhea shows
the greatest risk of mortality occurring among the very young and
elderly (Gerba et al., 1996). Specifically, young children are a
vulnerable population subject to infectious diarrhea caused by
Cryptosporidium (CDC 1994). Cryptosporidiosis is prevalent worldwide,
and its occurrence is higher in children than in adults (Fayer and
Ungar, 1986).
Cryptosporidiosis appears to be more prevalent in populations that
may not have established immunity against the disease and may be in
greater contact with environmentally contaminated surfaces, such as
infants (DuPont, et al., 1995). Once a child is infected it may spread
the disease to other children or family members. Evidence of such
secondary transmission of cryptosporidiosis from children to household
and other close contacts has been found in many outbreak investigations
(Casemore, 1990; Cordell et al., 1997; Frost et al., 1997). Chapell et
al., 1999, found that prior exposure to Cryptosporidium through the
ingestion of a low oocyst dose provides protection from infection and
illness. However, it is not known whether this immunity is life-long or
temporary. Data also indicate that either mothers confer short term
immunity to their children or that babies have reduced exposure to
Cryptosporidium, resulting in a decreased incidence of infection during
the first year of life. For example, in a survey of over 30,000 stool
sample analyses from different UK patients, the 1-5 year age group
suffered a much higher infection rate than individuals less than one
year of age. For children under one year of age, those older than
[[Page 19135]]
six months of age showed a higher rate of infection than individuals
aged fewer than six months (Casemore, 1990).
EPA has not been able to quantify the differential health effects
for children as a result of Cryptosporidium-contaminated drinking
water. However, the result of the LT1FBR will be a reduction in the
risk of illness for the entire population, including children.
Furthermore, the available anecdotal evidence indicates that children
may be more vulnerable to cryptosporidiosis than the rest of the
population. The LT1FBR would, therefore, result in greater risk
reduction for children than for the general population.
The public is invited to submit or identify peer-reviewed studies
and data, of which EPA may not be aware, that assessed results of early
life exposure to Cryptosporidium.
H. Consultations with the Science Advisory Board, National Drinking
Water Advisory Council, and the Secretary of Health and Human Services
In accordance with section 1412 (d) and (e) of the SDWA, the Agency
will consult with the National Drinking Water Advisory Council (NDWAC)
and the Secretary of Health and Human Services and request comment from
the Science Advisory Board on the proposed LT1FBR.
I. Executive Order 13132: Executive Orders on 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.
If EPA complies by consulting, Executive Order 13132 requires EPA
to provide to the Office of Management and Budget (OMB), in a
separately identified section of the preamble to the final rule, a
federalism summary impact statement (FSIS). The FSIS must include a
description of the extent of EPA's prior consultation with State and
local officials, a summary of the nature of their concerns and the
agency's position supporting the need to issue the regulation, and a
statement of the extent to which the concerns of State and local
officials have been met. Also, when EPA transmits a draft final rule
with federalism implications to OMB for review pursuant to Executive
Order 12866, EPA must include a certification from the agency's
Federalism Official stating that EPA has met the requirements of
Executive Order 13132 in a meaningful and timely manner.
EPA has concluded that this proposed rule may have federalism
implications since it may impose substantial direct compliance costs on
local governments, and the Federal government will not provide the
funds necessary to pay those cost. Accordingly, EPA provides the
following FSIS as required by section 6(b) of Executive Order 13132.
As discussed further in section VII.C.2.e, EPA met with a variety
of State and local representatives, who provided meaningful and timely
input in the development of the proposed rule. Summaries of the
meetings have been included in the public record for this proposed
rulemaking. EPA consulted extensively with State, local, and tribal
governments. For example, two public stakeholder meetings were held on
July 22-23, 1998, in Lakewood, Colorado, and on March 3-4, 1999, in
Dallas, Texas. Several key issues were raised by stakeholders regarding
the LT1 provisions, many of which were related to reducing burden and
maintaining flexibility. The Office of Water was able to significantly
reduce burden and increase flexibility by tailoring requirements to
reduce monitoring, reporting, and recordkeeping requirements faced by
small systems. These modifications and others aided in lowering the
cost of the LT1FBR by $87 million (from $184.5 million to $97.5
million). It should be noted that this rule is important because it
will reduce the level of Cryptosporidium in filtered finished drinking
water supplies through improvements in filtration and recycle practices
resulting in a reduced likelihood of outbreaks of cryptosporidiosis.
The rule is also expected to increase the level of protection from
exposure to other pathogens (i.e., Giardia and other waterborne
bacterial or viral pathogens). Because consultation on this proposed
rule occurred before the November 2, 1999 effective date of Executive
Order 13132, EPA will initiate discussions with State and local elected
officials regarding the implications of this rule during the public
comment period.
J. 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.''
EPA has concluded that this rule may significantly or unique affect
the communities of Indian tribal governments. It may also impose
substantial direct compliance costs on such communities. The Federal
government will not provide the funds necessary to pay all the direct
costs incurred by the Tribal governments in complying with the rule. In
developing this rule, EPA consulted with representatives of Tribal
governments pursuant to UMRA and Executive Order 13084. EPA held
extensive meetings that provided Indian Tribal governments the
opportunity for meaningful and timely input in the development of the
proposed rule. Summaries of the meetings have been included in the
public docket for this rulemaking. EPA's consultation, the nature of
the government's concerns, and the position supporting the need for
[[Page 19136]]
this rule are discussed in Section VII.C.2.e, which addresses
compliance with UMRA.
K. Likely Effect of Compliance with the LT1FBR on the Technical,
Financial, and Managerial Capacity of Public Water Systems
Section 1420(d)(3) of the SDWA as amended requires that, in
promulgating a NPDWR, the Administrator shall include an analysis of
the likely effect of compliance with the regulation on the technical,
financial, and managerial capacity of public water systems. This
analysis can be found in the LT1FBR RIA (EPA, 1999h).
Overall water system capacity is defined in EPA guidance (EPA,
1998j) as the ability to plan for, achieve, and maintain compliance
with applicable drinking water standards. Capacity has three
components: technical, managerial, and financial.
Technical capacity is the physical and operational ability of a
water system to meet SDWA requirements. Technical capacity refers to
the physical infrastructure of the water system, including the adequacy
of source water and the adequacy of treatment, storage, and
distribution infrastructure. It also refers to the ability of system
personnel to adequately operate and maintain the system and to
otherwise implement requisite technical knowledge. A water system's
technical capacity can be determined by examining key issues and
questions, including:
Source water adequacy. Does the system have a reliable
source of drinking water? Is the source of generally good quality and
adequately protected?
Infrastructure adequacy. Can the system provide water that
meets SDWA standards? What is the condition of its infrastructure,
including well(s) or source water intakes, treatment, storage, and
distribution? What is the infrastructure's life expectancy? Does the
system have a capital improvement plan?
Technical knowledge and implementation. Is the system's
operator certified? Does the operator have sufficient technical
knowledge of applicable standards? Can the operator effectively
implement this technical knowledge? Does the operator understand the
system's technical and operational characteristics? Does the system
have an effective operation and maintenance program?
Managerial capacity is the ability of a water system to conduct its
affairs to achieve and maintain compliance with SDWA requirements.
Managerial capacity refers to the system's institutional and
administrative capabilities. Managerial capacity can be assessed
through key issues and questions, including:
Ownership accountability. Are the system owner(s) clearly
identified? Can they be held accountable for the system?
Staffing and organization. Are the system operator(s) and
manager(s) clearly identified? Is the system properly organized and
staffed? Do personnel understand the management aspects of regulatory
requirements and system operations? Do they have adequate expertise to
manage water system operations? Do personnel have the necessary
licenses and certifications?
Effective external linkages. Does the system interact well
with customers, regulators, and other entities? Is the system aware of
available external resources, such as technical and financial
assistance?
Financial capacity is a water system's ability to acquire and
manage sufficient financial resources to allow the system to achieve
and maintain compliance with SDWA requirements. Financial capacity can
be assessed through key issues and questions, including:
Revenue sufficiency. Do revenues cover costs? Are water
rates and charges adequate to cover the cost of water?
Credit worthiness. Is the system financially healthy? Does
it have access to capital through public or private sources?
Fiscal management and controls. Are adequate books and
records maintained? Are appropriate budgeting, accounting, and
financial planning methods used? Does the system manage its revenues
effectively?
Systems not making significant modifications to the treatment
process to meet LT1FBR requirements are not expected to require
significantly increased technical, financial, or managerial capacity.
L. Plain Language
Executive Order 12866 and the President's memorandum of June 1,
1998, require each agency to write its rules in plain language. We
invite your comments on how to make this proposed rule easier to
understand. For example: Have we organized the material to suit your
needs? Are the requirements in the rule clearly stated? Does the rule
contain technical language or jargon that is not clear? Would a
different format (grouping and order of sections, use of headings,
paragraphing) make the rule easier to understand? Would shorter
sections make the final rule easier to understand? Could we improve
clarity by adding tables, lists, or diagrams? What else could we do to
make the rule easier to understand?
VIII. Public Comment Procedures
EPA invites you to provide your views on this proposal, approaches
we have not considered, the potential impacts of the various options
(including possible unintended consequences), and any data or
information that you would like the Agency to consider. Many of the
sections within today's proposed rule contain ``Request for Comment''
portions which the Agency is also interested in receiving comment on.
A. Deadlines for Comment
Send your comments on or before June 9, 2000. Comments received
after this date may not be considered in decision making on the
proposed rule. Again, comments must be received or post-marked by
midnight June 9, 2000.
B. Where To Send Comment
Send an original and 3 copies of your comments and enclosures
(including references) to W-99-10 Comment Clerk, Water Docket (MC4101),
USEPA, 401 M, Washington, D.C. 20460. Comments may also be submitted
electronically to [email protected]. Electronic comments must
be submitted as an ASCII, WP5.1, WP6.1 or WP8 file avoiding the use of
special characters and form of encryption. Electronic comments must be
identified by the docket number W-99-10. Comments and data will also be
accepted on disks in WP 5.1, 6.1, 8 or ASCII file format. Electronic
comments on this notice may be filed online at many Federal Depository
Libraries. Those who comment and want EPA to acknowledge receipt of
their comments must enclose a self-addressed stamped envelope. No
facsimiles (faxes) will be accepted. Comments may also be submitted
electronically to [email protected].
C. Guidelines for Commenting
To ensure that EPA can read, understand and therefore properly
respond to comments, the Agency would prefer that commenters cite,
where possible, the paragraph(s) or sections in the notice or
supporting documents to which each comment refers. Commenters should
use a separate paragraph for each issue discussed. Note that the Agency
is not soliciting comment on, nor will it respond to, comments on
previously published regulatory language that is included in this
notice to ease the reader's understanding of proposed language. You may
find the following
[[Page 19137]]
suggestions helpful for preparing your comments:
1. Explain your views as clearly as possible.
2. Describe any assumptions that you used.
3. Provide solid technical information and/or data to support your
views.
4. If you estimate potential burden or costs, explain how you
arrived at the estimate.
5. Indicate what you support, as well as what you disagree with.
6. Provide specific examples to illustrate your concerns.
7. Make sure to submit your comments by the deadline in this
proposed rule.
8. At the beginning of your comments (e.g., as part of the
``Subject'' heading), be sure to properly identify the document you are
commenting on. You can do this by providing the docket control number
assigned to the proposed rule, along with the name, date, and Federal
Register citation.
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List of Subjects
40 CFR Part 141
Environmental protection, Chemicals, Indians-lands,
Intergovernmental relations, Radiation protection, Reporting and
recordkeeping requirements, Water supply.
40 CFR Part 142
Environmental protection, Administrative practice and procedure,
Chemicals, Indians-lands, Radiation protection, Reporting and
recordkeeping requirements, Water supply.
Dated: March 27, 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 141--NATIONAL PRIMARY DRINKING WATER REGULATIONS
3. The authority citation for part 141 continues to read as
follows:
Authority: 42 U.S.C. 300f, 300g-1, 300g-2, 300g-3, 300g-4, 300g-
5, 300g-6, 300j-4, 300j-9, and 300j-11.
4. Section 141.2 is amended by revising the definition of ``Ground
water under the direct influence of surface water'' and ``Disinfection
profile'' and adding the following definitions in alphabetical order to
read as follows:
Sec. 141.2 Definitions.
* * * * *
Direct recycle is the return of recycle flow within the treatment
process of a public water system without first passing the recycle flow
through a treatment process designed to remove solids, a raw water
storage reservoir, or some other structure with a volume equal to or
greater than the volume of spent filter backwash water produced by one
filter backwash event.
* * * * *
Disinfection profile is a summary of Giardia lamblia inactivation
through the treatment plant, from the point of disinfectant application
to the first customer. The procedure for developing a disinfection
profile is contained in Sec. 141.172 (Disinfection profiling and
benchmarking) in subpart P and Secs. 141.530-141.536 (Disinfection
profile) in subpart T of this part.
* * * * *
Equalization is the detention of recycle flow in a structure with a
volume equal to or greater than the volume of spent filter backwash
produced by one filter backwash event.
* * * * *
Ground water under the direct influence of surface water (GWUDI)
means any water beneath the surface of the ground with significant
occurrence of insects or other macroorganisms, algae, or large-diameter
pathogens such as Giardia lamblia or Cryptosporidium, or significant
and relatively rapid shifts in water characteristics such as turbidity,
temperature, conductivity, or pH which closely correlate to
climatological or surface water conditions. Direct influence must be
determined for individual sources in accordance with criteria
established by the State. The State determination of direct influence
may be based on site-specific measurements of water quality and/or
documentation of well construction characteristics and geology with
field evaluation.
* * * * *
Membrane Filtration means any filtration process using tubular or
spiral wound elements that exhibits the ability to mechanically
separate water from other ions and solids by creating a pressure
differential and flow across a membrane with an absolute pore size 1
micron.
* * * * *
Operating capacity is the maximum finished water production rate
approved by the State drinking water program.
* * * * *
Recycle is the return of any water, solid, or semisolid generated
by plant treatment processes, operational processes, maintenance
processes, and residuals treatment processes into a PWS's primary
treatment processes.
* * * * *
5. Section 141.32 is amended by revising paragraph (e)(10) to read
as follows:
Sec. 141.32 Public notification.
* * * * *
(e) * * *
(10) Microbiological contaminants (for use when there is a
violation of the treatment technique requirements for filtration and
disinfection in subpart H, subpart P, or subpart T of this part). The
United States Environmental Protection Agency (EPA) sets drinking water
standards and has determined that the presence of microbiological
contaminants are a health concern at certain levels of exposure. If
water is inadequately treated, microbiological contaminants in that
water may cause disease. Disease symptoms may include diarrhea, cramps,
nausea, and possibly jaundice, and any associated headaches and
fatigue. These symptoms, however, are not just associated with disease-
causing organisms in drinking water, but also may be caused by a number
of factors other than your drinking water. EPA has set enforceable
requirements for treating drinking water to reduce the risk of these
adverse health effects. Treatment such as filtering and disinfecting
the water removes or destroys microbiological contaminants. Drinking
water which is treated to meet EPA requirements is associated with
little to none of this risk and should be considered safe.
* * * * *
6. Section 141.70 is amended by revising paragraph (b)(2) and
adding paragraph (e) to read as follows:
Sec. 141.70 General requirements.
* * * * *
(b) * * *
(2) It meets the filtration requirements in Sec. 141.73, the
disinfection
[[Page 19142]]
requirements in Sec. 141.72(b) and the recycle requirements in
Sec. 141.76.
* * * * *
(e) Additional requirements for systems serving fewer than 10,000
people. In addition to complying with requirements in this subpart,
systems serving fewer than 10,000 people must also comply with the
requirements in subpart T of this part.
7. Section 141.73 is amended by adding paragraph (a)(4) and
revising paragraph (d) to read as follows:
Sec. 141.73 Filtration.
* * * * *
(a) * * *
(4) Beginning [DATE 36 MONTHS AFTER DATE OF PUBLICATION OF FINAL
RULE IN THE FEDERAL REGISTER], systems serving fewer than 10,000 people
must meet the turbidity requirements in Secs. 141.550 through 141.553.
* * * * *
(d) Other filtration technologies. A public water system may use a
filtration technology not listed in paragraphs (a) through (c) of this
section if it demonstrates to the State, using pilot plant studies or
other means, that the alternative filtration technology, in combination
with disinfection treatment that meets the requirements of
Sec. 141.72(b), consistently achieves 99.9 percent removal and/or
inactivation of Giardia lamblia cysts and 99.99 percent removal and/or
inactivation of viruses. For a system that makes this demonstration,
the requirements of paragraph (b) of this section apply. Beginning
December 17, 2001, systems serving at least 10,000 people must meet the
requirements for other filtration technologies in paragraph (b) of this
section. Beginning [DATE 36 MONTHS AFTER DATE OF PUBLICATION OF FINAL
RULE IN THE FEDERAL REGISTER], systems serving fewer than 10,000 people
must meet the requirements for treatment technologies in Secs. 141.550
through141.553.
8. Subpart H is amended by adding a new Sec. 141.76 to subpart H to
read as follows:
Sec. 141.76 Recycle Provisions.
(a) Public water systems employing conventional filtration or
direct filtration that use surface water or ground water under the
direct influence of surface water and recycle within the treatment
process must meet all applicable requirements of this section.
Requirements are summarized in the following table.
Recycle Provisions for subpart H Systems
------------------------------------------------------------------------
You are required to meet the
If you are a . . . requirements in . . .
------------------------------------------------------------------------
(1) subpart H public water system Sec. 141.76 (b).
employing conventional or direct
filtration returning spent filter
backwash, thickener supernatant, or
liquids from dewatering processes
concurrent with or downstream of the
point of primary coagulant addition.
(2) Plant that is part of a subpart H Sec. 141.76 (c).
public water system, employ conventional
filtration treatment, practice direct
recycle, employ 20 or fewer filters to
meet production requirements during the
highest production month in the 12 month
period [date 60 months after publication
of final rule], and recycle spent filter
backwash or thickener supernatant to the
treatment process.
(3) subpart H public water system Sec. 141.76 (d).
practicing direct filtration and
recycling to the treatment process.
------------------------------------------------------------------------
(b) Recycle return location. All subpart H systems employing
conventional filtration or direct filtration and returning spent filter
backwash, thickener supernatant, or liquids from dewatering processes
at or after the point of primary coagulant addition must return these
recycle flows prior to the point of primary coagulant addition by [DATE
60 MONTHS AFTER DATE OF PUBLICATION OF FINAL RULE IN THE FEDERAL
REGISTER]. The system must apply to the State for approval of the
change in recycle location before the system implements it.
(1) All subpart H systems employing conventional filtration or
direct filtration, returning spent filter backwash, thickener
supernatant, or liquids from dewatering processes at or after the point
of primary coagulant addition must submit a plant schematic to the
State by [DATE 42 MONTHS AFTER DATE OF PUBLICATION OF FINAL RULE IN THE
FEDERAL REGISTER] showing the current recycle return location(s) for
the recycle stream(s) and the new return location that will be used to
establish compliance. The system must keep the plant schematic on file
for review during sanitary surveys.
(2) Softening systems may recycle process solids at the point of
lime addition preceding the softening process to improve treatment
efficiency. Process solids may not be returned prior to the point of
lime addition. Softening systems shall not return spent filter
backwash, thickener supernatant, or liquids from dewatering processes
to a location other than prior to the point of primary coagulant
addition unless an alternate location is granted by the State.
(3) Contact clarification systems may recycle process solids
directly into the contactor. Contact clarification systems shall not
return spent filter backwash, thickener supernatant, or liquids from
dewatering processes to a location other than prior to the point of
primary coagulant addition unless an alternate location is granted by
the State.
(4) Systems may apply to the State to return spent filter backwash,
thickener supernatant, or liquids from dewatering processes to an
alternate location other than prior to the point of primary coagulant
addition.
(c) Plants that are part of subpart H public water systems that
employ conventional rapid granular filtration, practice direct recycle,
employ 20 or fewer filters to meet production requirements during the
highest production month in the 12 month period prior to [DATE 60
MONTHS AFTER PUBLICATION OF FINAL RULE IN THE Federal Register], and
recycle spent filter backwash or thickener supernatant to the primary
treatment process shall complete a recycle self assessment, as
stipulated in paragraphs(c)(1) and (c)(2) by [Date 51 Months After Date
of Publication of Final Rule in the Federal Register]. Systems required
to perform the self assessment shall:
(1) Submit a recycle self assessment monitoring plan to the State
no later than [Date 39 Months After Date of Publication of Final Rule
in the Federal Register]. At a minimum, the monitoring plan must
identify the highest water production month during
[[Page 19143]]
which monitoring will be conducted, contain a schematic identifying the
location of raw and recycle flow monitoring devices, describe the type
of flow monitoring devices to be used, identify the system's State
approved operating capacity, and describe how data from the raw and
recycle flow monitoring devices will be simultaneously retrieved and
recorded.
(2) Implement the following recycle self assessment monitoring and
analysis steps:
(i) Steps for Implementation of Recycle Self Assessment:
(A) Identify the highest water production month during the 12 month
period preceding [Date 36 Months After Date of Publication of Final
Rule in the Federal Register].
(B) Perform the monitoring described in paragraph (c)(2)(i)(C) of
this section during the 12 month period after submission of the
monitoring plan to the State. The twelve month period must begin no
later than [Date 39 Months After Date of Publication of Final Rule in
the Federal Register].
(C) For each day of the month identified in paragraph (c)(2)(i)(A)
of this section, separately monitor source water influent flow and
recycle flow before their confluence during one filter backwash recycle
event per day, at three minute intervals during the duration of the
event. Monitoring must be performed between 7:00 a.m. and 8:00 p.m.
Systems that do not have a filter backwash recycle event every day
between 7:00 am and 8:00 p.m. must monitor one filter backwash recycle
event per day, any three days of the week, for each week during the
month of monitoring, between 7:00 a.m. and 8:00 p.m. Record the time
filter backwash was initiated, the influent and recycle flow at three
minute intervals during the duration of the event, and the time the
filter backwash recycle event ended. Record the number of filters in
use when the filter backwash recycle event is monitored.
(D) Calculate the arithmetic average of all influent and recycle
flow values taken at three minute intervals in paragraph (c)(2)(i)(c)
of this section. Sum the arithmetic average calculated for raw water
influent and recycle flows. Record this value and the date the
monitoring was performed. This value is referred to as event flow.
(E) After the month of monitoring is complete, order the event
flows in a list of increasing order, from lowest to highest. Highlight
the event flows that exceed State approved operating capacity and then
sum the number of event flows highlighted.
(ii) [Reserved]
(3) Subpart H systems performing recycle self assessments are
required to report the results of the self assessment and supporting
documentation to the State within one month of completing raw water
influent and recycle flow monitoring. The report must be submitted no
later than [DATE 52 MONTHS AFTER DATE OF PUBLICATION OF FINAL RULE IN
THE FEDERAL REGISTER]. If the State determines the self assessment is
incomplete or inaccurate, it may require the system to correct
deficiencies or perform an additional self assessment. At a minimum,
the report must contain the following information:
(i) Minimum Information Included in Recycle Assessment Report to
State:
(A) All source and recycle flow measurements taken and the dates
they were taken. For all events monitored, report the times the filter
backwash recycle event was initiated, the flow measurements taken at
three minute intervals, and the time the filter backwash recycle event
ended. Report the number of filters in use when the backwash recycle
event is monitored.
(B) All data used and calculations performed to determine whether
the system exceeded operating capacity during monitored recycle events
and the number of event flow values that exceeded State approved
operating capacity.
(C) A plant schematic showing the origin of all recycle flows, the
hydraulic conveyance used to transport them, and their final
destination in the plant.
(D) A list of all the recycle flows and the frequency at which they
are returned to the plant's primary treatment process.
(E) Average and maximum backwash flow rate through the filters and
the average and maximum duration of the filter backwash process, in
minutes.
(F) Typical filter run length and a written summary of how filter
run length is determined (preset run time, headloss, turbidity
breakthrough, etc.).
(ii) [Reserved]
(4) All subpart H systems performing self assessments are required
to modify their recycle practice in accordance with the State
determination by [DATE 60 MONTHS AFTER DATE OF PUBLICATION OF FINAL
RULE IN THE FEDERAL REGISTER] and keep a copy of the self assessment
report submitted to the State on file for review during sanitary
surveys.
(d) Subpart H public water systems practicing direct filtration and
recycling to the primary treatment process are required to submit data
to the State on their current recycle treatment no later than [DATE 42
MONTHS AFTER DATE OF PUBLICATION OF FINAL RULE IN THE FEDERAL
REGISTER.]
(1) Direct filtration systems submitting data to the State shall
report the following information, at a minimum:
(i) Data Submitted to States by Direct Filtration Systems:
(A) A plant schematic showing the origin of all recycle flows, the
hydraulic conveyance used to transport them, and their final
destination in the plant.
(B) The number of filters used at the plant to meet average daily
production requirements and average and maximum backwash flow rate
through the filter and the average and maximum duration of the filter
backwash process, in minutes.
(C) Whether recycle flow treatment or equalization is in place.
(D) The type of treatment provided for the recycle flow.
(E) For recycle equalization and treatment units: data on the
physical dimensions of the unit (length, width (or circumference),
depth,) sufficient to allow calculation of volume; typical and maximum
hydraulic loading rate; type of treatment chemicals used and average
dose and frequency of use, and frequency at which solids are removed
from the unit, if applicable.
(ii) [Reserved]
(2) All direct filtration systems submitting data to the State are
required to modify their recycle practice in accordance with the State
determination no later than [DATE 60 MONTHS AFTER DATE OF PUBLICATION
OF FINAL RULE IN THE FEDERAL REGISTER] and keep a copy of the report
submitted to the State on file for review during sanitary surveys.
9. Section 141.153 is amended by revising the first sentence of
paragraph (d)(4)(v)(C) to read as follows:
Sec. 141.153 Content of the reports.
* * * * *
(d) * * *
(4) * * *
(v) * * *
(C) When it is reported pursuant to Sec. 141.73 or Sec. 141.173 or
Sec. 141.551: the highest single measurement and the lowest monthly
percentage of samples meeting the turbidity limits specified in
Sec. 141.73 or Sec. 141.173, or Sec. 141.551 for the filtration
technology being used. * * *
* * * * *
10. The heading to Subpart P is revised as follows:
Subpart P--Enhanced Filtration and Disinfection-Systems Serving
10,000 or More People
* * * * *
[[Page 19144]]
11. Section 141.170 is amended by adding paragraph (d) to read as
follows:
Sec. 141.170 General requirements.
* * * * *
(d) Subpart H systems that did not conduct applicability monitoring
under Sec. 141.172 because they served fewer than 10,000 persons when
such monitoring was required but serve more than 10,000 persons prior
to [DATE 36 MONTHS AFTER DATE OF PUBLICATION OF FINAL RULE IN THE
FEDERAL REGISTER] must comply with Secs. 141.170, 141.171, 141.173,
141.174, and 141.175. These systems must also consult with the State to
establish a disinfection benchmark. A system that decides to make a
significant change to its disinfection practice, as described in
Sec. 141.172(c)(1)(i) through (iv) must consult with the State prior to
making such change.
* * * * *
12. Part 141 is amended by adding a new subpart T to read as
follows:
Subpart T--Enhanced Filtration and Disinfection--Systems Serving
Fewer than 10,000 People
Sec.
General Requirements
141.500 General requirements.
141.501 Who is subject to the requirements of subpart T?
141.502 When must my system comply with these requirements?
141.503 What does subpart T require?
Finished Water Reservoirs
141.510 Is my system subject to the new finished water reservoir
requirements?
141.511 What is required of new finished water reservoirs?
Additional Watershed Control Requirements
141.520 Is my system subject to the updated watershed control
requirements?
141.521 What updated watershed control requirements must my system
comply with?
141.522 How does the State determine whether my system's watershed
control requirements are adequate?
Disinfection Profile
141.530 Who must develop a Disinfection Profile and what is a
Disinfection Profile?
141.531 How does my system demonstrate TTHM and HAA5 levels below
0.064 mg/l and 0.048 mg/l respectively?
141.532 How does my system develop a Disinfection Profile and when
must it begin?
141.533 What measurements must my system collect to calculate a
Disinfection Profile?
141.534 How does my system use these measurements to calculate an
inactivation ratio?
141.535 How does my system develop a Disinfection Profile if we
use chloramines, ozone, or chlorine dioxide for primary
disinfection?
141.536 If my system has developed an inactivation ratio; what
must we do now?
Disinfection Benchmark
141.540 Who has to develop a Disinfection Benchmark?
141.541 What are significant changes to disinfection practice?
141.542 How is the Disinfection Benchmark calculated?
141.543 What if my system uses chloramines or ozone for primary
disinfection?
141.544 What must my system do if considering a significant change
to disinfection practices?
Combined Filter Effluent Requirements
141.550 Is my system required to meet subpart T combined filter
effluent turbidity limits?
141.551 What strengthened combined filter effluent turbidity
limits must my system meet?
141.552 If my system consists of ``alternative filtration'' and is
required to conduct a demonstration, what is required of my system
and how does the State establish my turbidity limits?
141.553 If my system practices lime softening, is there any
special provision regarding my combined filter effluent?
Individual Filter Turbidity Requirements
141.560 Is my system subject to individual filter turbidity
requirements?
141.561 What happens if my turbidity monitoring equipment fails?
141.562 What follow-up action is my system required to take based
on turbidity monitoring of individual filters?
141.563 My system practices lime softening. Is there any special
provision regarding my individual filter turbidity monitoring?
Reporting and Recordkeeping Requirements
142.570 What does subpart T require that my system report to the
State?
142.571 What records does subpart T require my system to keep?
Subpart T--Enhanced Filtration and Disinfection--Systems Serving Fewer
Than 10,000 People
General Requirements
Sec. 141.500 General requirements.
The requirements of subpart T constitute national primary drinking
water regulations. These regulations establish requirements for
filtration and disinfection that are in addition to criteria under
which filtration and disinfection are required under subpart H of this
part. The regulations in this subpart establish or extend treatment
technique requirements in lieu of maximum contaminant levels for the
following contaminants: Giardia lamblia, viruses, heterotrophic plate
count bacteria, Legionella, Cryptosporidium and turbidity. The
treatment technique requirements consist of installing and properly
operating water treatment processes which reliably achieve:
(a) At least 99 percent (2 log) removal of Cryptosporidium between
a point where the raw water is not subject to recontamination by
surface water runoff and a point downstream before or at the first
customer for filtered systems, or Cryptosporidium control under the
watershed control plan for unfiltered systems.
(b) Compliance with the profiling and benchmark requirements in
Secs. 141.530 through 141.544.
Sec. 141.501 Who is subject to the requirements of subpart T?
You are subject to these requirements if your system:
(a) Is a public water system;
(b) Uses surface water or GWUDI as a source; and
(c) Serves fewer than 10,000 persons annually.
Sec. 141.502 When must my system comply with these requirements?
You must comply with these requirements beginning [DATE 36 MONTHS
AFTER DATE OF PUBLICATION OF FINAL RULE IN THE FEDERAL REGISTER] except
where otherwise noted.
Sec. 141.503 What does subpart T require?
There are six requirements of this subpart which your system may
need to comply with. These requirements are discussed in detail later
in this subpart. They are:
(a) Any finished water reservoir for which construction begins on
or after [DATE 60 DAYS AFTER DATE OF PUBLICATION OF FINAL RULE IN THE
FEDERAL REGISTER] must be covered;
(b) Unfiltered systems must comply with updated watershed control
requirements;
(c) All systems subject to the requirements of this subpart must
develop a disinfection profile;
(d) All systems subject to the requirements of this subpart that
are considering a significant change to their disinfection practice
must develop a disinfection benchmark and receive State approval before
changing their disinfection practice;
(e) Filtered systems must comply with specific combined filter
effluent turbidity limits and monitoring and reporting requirements;
and
(f) Filtered systems using conventional or direct filtration must
[[Page 19145]]
comply with individual filter turbidity limits and monitoring and
reporting requirements.
Finished Water Reservoirs
Sec. 141.510 Is my system subject to the new finished water reservoir
requirements?
All subpart H systems which serve populations fewer than 10,000 are
subject to this requirement.
Sec. 141.511 What is required for new finished water reservoirs?
If your system initiates construction of a finished water reservoir
after [DATE 60 DAYS AFTER DATE OF PUBLICATION OF FINAL RULE IN THE
FEDERAL REGISTER the reservoir must be covered. Finished water
reservoirs constructed prior to [DATE 60 DAYS AFTER DATE OF PUBLICATION
OF FINAL RULE IN THE FEDERAL REGISTER are not subject to this
requirement.
Additional Watershed Control Requirements
Sec. 141.520 Is my system subject to the updated watershed control
requirements?
If you are a subpart H system serving fewer than 10,000 persons
which does not provide filtration, you must continue to comply with all
of the watershed control requirements in Sec. 141.71, as well as the
additional watershed control requirements in Sec. 141.521.
Sec. 141.521 What additional watershed control requirements must my
system comply with?
Your system must also maintain the existing watershed control
program to minimize the potential for contamination by Cryptosporidium
oocysts in the source water. Your system's watershed control program
must, for Cryptosporidium:
(a) Identify watershed characteristics and activities which may
have an adverse effect on source water quality; and
(b) Monitor the occurrence of activities which may have an adverse
effect on source water quality.
Sec. 141.522 How does the State determine whether my system's
watershed control requirements are adequate?
During an onsite inspection conducted under the provisions of
Sec. 141.71(b)(3), the State must determine whether your watershed
control program is adequate to limit potential contamination by
Cryptosporidium oocysts. The adequacy of the program must be based on
the comprehensiveness of the watershed review; the effectiveness of
your program to monitor and control detrimental activities occurring in
the watershed; and the extent to which your system has maximized land
ownership and/or controlled land use within the watershed.
Disinfection Profile
Sec. 141.530 Who must develop a Disinfection Profile and what is a
Disinfection Profile?
All subpart H community and non-transient non-community water
systems which serve fewer than 10,000 persons must develop a
disinfection profile. A disinfection profile is a graphical
representation of your system's level of Giardia lamblia or virus
inactivation measured during the course of a year. Your system must
develop a disinfection profile unless you can demonstrate to the State
that your TTHM and HAA5 levels are less than 0.064 mg/l and 0.048 mg/l
respectively, prior to January 7, 2003.
Sec. 141.531 How does my system demonstrate TTHM and HAA5 levels below
0.064 mg/l and 0.048 mg/l respectively?
In order to demonstrate that your TTHM and HAA5 levels are below
0.064 mg/L and 0.048 mg/L, respectively your system must have collected
one TTHM and one HAA5 sample taken between 1998-2002. Samples must have
been collected during the month with the warmest water temperature, at
the point of maximum residence time in your distribution system which
indicate TTHM levels below 0.064 mg/l and HAA5 levels below 0.048 mg/L.
By January 7, 2003, you must submit a copy of the results to the State
along with a letter indicating your intention to forgo development of a
disinfection profile because of the results of the sampling. This
letter, along with a copy of your TTHM and HAA5 sample lab results must
be kept on file for review by the State during a sanitary survey. If
the data you have collected is either equal to or exceeds either 0.064
mg/l for TTHM and/or 0.048 mg/l for HAA5s, you must develop a
disinfection profile.
Sec. 141.532 How does my system develop a Disinfection Profile and
when must it begin?
A disinfection profile consists of three steps:
(a) First, your system must collect measurements for several
treatment parameters from the plant as discussed in Sec. 141.533. Your
system must begin this monitoring no later than January 7, 2003.
(b) Second, your system must use these measurements to calculate
inactivation ratios as discussed in Secs. 141.534 and 141.535; and
(c) Third, your system must use these inactivation ratios to
develop a disinfection profile as discussed in Sec. 141.536.
Sec. 141.533 What measurements must my system collect to calculate a
Disinfection Profile?
Your system must monitor the parameters necessary to determine the
total inactivation ratio using analytical methods in Sec. 141.74 (a),
once per week on the same calendar day each week as follows:
(a) The temperature of the disinfected water must be measured at
each residual disinfectant concentration sampling point during peak
hourly flow;
(b) If the system uses chlorine, the pH of the disinfected water
must be measured at each chlorine residual disinfectant concentration
sampling point during peak hourly flow;
(c) The disinfectant contact time(s) (``T'') must be determined
during peak hourly flow; and
(d) The residual disinfectant concentration(s) (``C'') of the water
before or at the first customer and prior to each additional point of
disinfection must be measured during peak hourly flow.
Sec. 141.534 How does my system use these measurements to calculate an
inactivation ratio?
Calculate the total inactivation ratio as follows, and multiply the
value by 3.0 to determine log inactivation of Giardia lamblia:
------------------------------------------------------------------------
If a system... The system must determine...
------------------------------------------------------------------------
(a) Uses only one point of disinfectant (1) One inactivation ratio
application. (CTcalc/CT99.9) before or at
the first customer during peak
hourly flow, or
[[Page 19146]]
(2) Successive CTcalc/CT99.9
values, representing
sequential inactivation
ratios, between the point of
disinfectant application and a
point before or at the first
customer during peak hourly
flow. Under this alternative,
the system must calculate the
total inactivation ratio by
determining (CTcalc/CT99.9)
for each sequence and then
adding the (CTcalc/CT99.9)
values together to determine
( (CTcalc/CT99.9)).
You may use a spreadsheet that
calculates CT and/or contains
the necessary inactivation
tables.
(b) Uses more than one point of (1) The CTcalc/CT99.9 value of
disinfectant application before the each disinfection segment
first customer. immediately prior to the next
point of disinfectant
application, or for the final
segment, before or at the
first customer, during peak
hourly flow using the
procedure described in the
above paragraph.
------------------------------------------------------------------------
Sec. 141.535 How does my system develop a Disinfection Profile if we
use chloramines, ozone, or chlorine dioxide for primary disinfection?
If your system uses either chloramines, ozone or chlorine dioxide
for primary disinfection, you must also calculate the logs of
inactivation for viruses. You must develop an additional disinfection
profile for viruses using a method approved by the State.
Sec. 141.536 If my system has developed an inactivation ratio, what
must we do now?
Each inactivation ratio serves as a data point in your disinfection
profile. Your system will have obtained 52 measurements (one for every
week of the year). This will allow your system and the State the
opportunity to evaluate how microbial inactivation varied over the
course of the year by looking at all 52 measurements (your Disinfection
Profile). Your system must retain the Disinfection Profile data in
graphic form, as a spreadsheet, or in some other format acceptable to
the State for review as part of sanitary surveys conducted by the
State. Your system will need to use this data to calculate a benchmark
if considering changes to disinfection practices.
Disinfection Benchmark
Sec. 141.540 Who has to develop a Disinfection Benchmark?
If you are a subpart H system required to develop a disinfection
profile under Secs. 141.530 through 141.536, your system must develop a
Disinfection Benchmark if you decide to make a significant change to
disinfection practice. State approval must be obtained before you can
implement a significant disinfection practice change.
Sec. 141.541 What are significant changes to disinfection practice?
Significant changes to disinfection practice are:
(a) Changes to the point of disinfection;
(b) Changes to the disinfectant(s) used in the treatment plant;
(c) Changes to the disinfection process; or
(d) Any other modification identified by the State.
Sec. 141.542 How is the Disinfection Benchmark Calculated?
If your system is making a significant change to its disinfection
practice, it must calculate a disinfection benchmark using the
following procedure:
(a) To calculate a disinfection benchmark a system must perform the
following steps:
Step 1: Using the data your system collected to develop the
Disinfection Profile, determine the average Giardia lamblia
inactivation for each calender month by dividing the sum of all Giardia
lamblia inactivations for that month by the number of values calculated
for that month.
Step 2: Determine the lowest monthly average value out of the
twelve values. This value becomes the disinfection benchmark.
(b) [Reserved]
Sec. 141.543 What if my system uses chloramines or ozone for primary
disinfection?
If your system uses chloramines, ozone or chlorinated dioxide for
primary disinfection your system must calculate the disinfection
benchmark from the data your system collected for viruses to develop
the disinfection profile in addition to the Giardia lamblia
disinfection benchmark calculated under Sec. 141.542. The disinfection
benchmark must be calculated as described in Sec. 141.542.
Sec. 141.544 What must my system do if considering a significant
change to disinfection practices?
If your system is considering a significant change to the
disinfection practice, it must complete a disinfection benchmark(s) as
described in Secs. 141.542 and 141.543 and provide the benchmark(s) to
your State. Your system may only make a significant disinfection
practice change after receiving State approval. The following
information must be submitted to the State as part of their review and
approval process:
(a) A description of the proposed change;
(b) The disinfection profile for Giardia lamblia (and, if
necessary, viruses) and disinfection benchmark;
(c) An analysis of how the proposed change will affect the current
levels of disinfection; and
(d) Additional information requested by the State.
Combined Filter Effluent Requirements
Sec. 141.550 Is my system required to meet subpart T combined filter
effluent turbidity limits?
All subpart H systems which serve populations fewer than 10,000,
and are required to filter, must meet combined filter effluent
requirements. Unless your system consists of slow sand or diatomaceous
earth filtration, you are required to meet the combined filter effluent
turbidity limits in Sec. 141.551. If your system uses slow sand or
diatomaceous earth filtration you must continue to meet the combined
filter effluent turbidity limits in Sec. 141.73.
Sec. 141.551 What strengthened combined filter effluent turbidity
limits must my system meet?
Your system must meet two strengthened combined filter effluent
turbidity limits.
(a) The first combined filter effluent turbidity limit is a ``95th
percentile'' turbidity limit which your system must meet in at least 95
percent of the turbidity measurements taken each month. Measurements
must continue to be taken as described in Sec. 141.74(a) and (c). The
following table describes the required limits for specific filtration
technologies.
[[Page 19147]]
------------------------------------------------------------------------
Your 95th percentile turbidity
If your system consists of . . . value is . . .
------------------------------------------------------------------------
(1) Conventional filtration or direct 0.3 NTU.
filtration.
(2) Membrane filtration................ 0.3 NTU or a value determined
by the State (not to exceed 1
NTU) based on a demonstration
conducted by the system as
described in Sec. 141.552.
(3) All other ``alternative'' A value determined by the State
filtration. (not to exceed 1 NTU) based on
the demonstration described in
Sec. 141.552.
------------------------------------------------------------------------
(b) The second combined filter effluent turbidity limit is a
``maximum'' turbidity limit which your system may at no time exceed
during the month. Measurements must continue to be taken as described
in Sec. 141.74(a) and (c). The following table describes the required
limits for specific filtration technologies.
------------------------------------------------------------------------
Your maximum turbidity value is
If your system consists of . . . . . .
------------------------------------------------------------------------
(1) Conventional filtration or direct 1 NTU.
filtration.
(2) Membrane filtration................ 1 NTU or a value determined by
the State (not to exceed 5
NTU) based on a demonstration
conducted by the system as
described in Sec. 141.552.
(3) All other ``alternative'' A value determined by the State
filtration. (not to exceed 5 NTU) based on
the demonstration as described
in Sec. 141.552.
------------------------------------------------------------------------
Sec. 141.552 If my system consists of ``alternative filtration'' and
is required to conduct a demonstration, What is required of my system
and how does the State establish my turbidity limits?
(a) If your system is required to conduct a demonstration (see
tables in Sec. 141.551), your system must demonstrate to the State,
using pilot plant studies or other means, that your system's
filtration, in combination with disinfection treatment, consistently
achieves:
(1) 99.9 percent removal and/or inactivation of Giardia lamblia
cysts;
(2) 99.99 percent removal and/or inactivation of viruses; and
(3) 99 percent removal of Cryptosporidium oocysts.
(b) If the State approves your demonstration, it will set turbidity
performance requirements that your system must meet:
(1) At least 95 percent of the time (not to exceed 1 NTU); and
(2) That your system must not exceed at any time (not to exceed 5
NTU).
Sec. 141.553 If my system practices lime softening, is there any
special provision regarding my combined filter effluent?
If your system practices lime softening, you may acidify
representative combined filter effluent turbidity samples prior to
analysis using a protocol approved by the State.
Individual Filter Turbidity Requirements
Sec. 141.560 Is my system subject to individual filter turbidity
requirements?
If your system is a subpart H system serving fewer than 10,000
people and utilizing conventional filtration or direct filtration, you
must conduct continuous monitoring of turbidity for each individual
filter at your system. The following requirements apply to individual
filter turbidity monitoring:
(a) Monitoring must be conducted using an approved method in
Sec. 141.74(a);
(b) Calibration of turbidimeters must be conducted using procedures
specified by the manufacturer;
(c) Results of individual filter turbidity monitoring must be
recorded every 15 minutes;
(d) Monthly reporting must be completed according Sec. 141.570; and
(e) Records must be maintained according to Sec. 141.571.
Sec. 141.561 What happens if my system's turbidity monitoring
equipment fails?
If there is a failure in the continuous turbidity monitoring
equipment, the system must conduct grab sampling every four hours in
lieu of continuous monitoring until the turbidimeter is back on-line. A
system has five working days to resume continuous monitoring before a
violation is incurred.
Sec. 141.562 What follow-up action is my system required to take based
on turbidity monitoring of individual filters?
Follow-up action is required according to the following tables:
------------------------------------------------------------------------
If the turbidity of an individual
filter exceeds... The system must...
------------------------------------------------------------------------
(a) If the turbidity of an individual Submit an exceptions report to
filter exceeds 1.0 NTU (in two the State by the 10th of the
consecutive recordings). month which includes the
filter number(s),
corresponding date(s), and the
turbidity value(s) which
exceeded 1.0 NTU.
------------------------------------------------------------------------
------------------------------------------------------------------------
If an exceptions report is submitted
for the same filter... The system must...
------------------------------------------------------------------------
(b) If an exceptions report is Conduct a self-assessment of
submitted for the same filter three the filter within 14 days of
months in a row. the exceedance and report that
the self assessment was
conducted by the 10th of the
following month. The self
assessment must consist of at
least the following
components: Assessment of
filter performance;
development of a filter
profile; identification and
prioritization of factors
limiting filter performance;
assessment of the
applicability of corrections;
and preparation of a filter
self-assessment report.
[[Page 19148]]
(c) If an exceptions report is (1) Arrange to have a
submitted for the same filter two comprehensive performance
months in a row and both months evaluation (CPE) conducted by
contain exceedances of 2.0 NTU (in 2 the State or a third party
consecutive recordings). approved by the State no later
than 30 days following the
exceedance and have the
evaluation completed and
submitted to the State no
later than 90 days following
the exceedance, Unless--
(2) A CPE has been completed by
the State or a third party
approved by the State within
the 12 prior months or the
system and State are jointly
participating in an ongoing
Comprehensive Technical
Assistance (CTA) project at
the system.
------------------------------------------------------------------------
Sec. 141.563 My system practices lime softening. Is there any special
provision regarding my individual filter turbidity monitoring?
If your system utilizes lime softening, you may apply to the State
for alternative turbidity exceedance levels for the levels specified in
the table in Sec. 141.562. You must be able to demonstrate to the State
that higher turbidity levels in individual filters are due to lime
carryover only, and not due to degraded filter performance.
Reporting and Recordkeeping Requirements
Sec. 141.570 What does subpart T require that my system report to the
State?
This subpart T requires your system to report several items to the
State. The following table describes the items which must be reported
and the frequency of reporting. Your system is required to report the
information described below, if it is subject to the specific
requirement shown in the first column.
----------------------------------------------------------------------------------------------------------------
Corresponding requirement Description of information to report Frequency
----------------------------------------------------------------------------------------------------------------
(a) Combined Filter Effluent (1)The total number of filtered water By the 10th of the
Requirements. turbidity measurements taken during the following month.
month.
-----------------------------------------------------------------------
(2) The number and percentage of filtered By the 10th of the
water turbidity measurements taken during following month.
the month which are greater than your
system's required 95th percentile limit.
-----------------------------------------------------------------------
(3) The date and value of any turbidity (i) Within 24 hours of
measurements taken during the month which exceedance and
exceed the maximum turbidity value for
your filtration system.
(ii) By the 10th of the
following month.
-----------------------------------------------------------------------
(b) Individual Filter Turbidity (1) That your system conducted individual By the 10th of the
Requirements. filter turbidity monitoring during the following month.
month.
-----------------------------------------------------------------------
(2) The filter number(s), corresponding By the 10th of the
date(s), and the turbidity value(s) which following month only if--
exceeded 1.0 NTU during the month..
(ii) 2 consecutive values
exceeded 1.0 NTU.
-----------------------------------------------------------------------
(3) That a self assessment was conducted (i) By the 10th of the
within 14 days of the date it was following month (or 14
triggered. days after the self
assessment was triggered
only if the self
assessment was triggered
during the last four days
of the month) only if--
(ii) A self-assessment is
required.
-----------------------------------------------------------------------
(4) That a CPE is required and the date (i) By the 10th of the
that it was triggered. following month only if--
(ii) A CPE is required.
-----------------------------------------------------------------------
(5) Copy of completed CPE report.......... Within 90 days after the
CPE was triggered.
-----------------------------------------------------------------------
(c) Disinfection Profiling.............. (1) Results of applicability monitoring No later than January 7,
which show TTHM levels 0.064 mg/l and 2003.
HAA5 levels 0.048 mg/l. (Only if your
system wishes to forgo profiling) or that
your system has begun disinfection
profiling.
-----------------------------------------------------------------------
(d) Disinfection Benchmarking........... (1) A description of the proposed change Anytime your system is
in disinfection, your system's considering a significant
disinfection profile for Giardia lamblia change to its
(and, if necessary, viruses) and disinfection practice.
disinfection benchmark, and an analysis
of how the proposed change will affect
the current levels of disinfection.
----------------------------------------------------------------------------------------------------------------
[[Page 19149]]
Sec. 141.571 What records does subpart T require my system to keep?
Your system must keep several types of records based on the
requirements of subpart T. The following table describes the necessary
records, the length of time these records must be kept, and for which
requirement the records pertain. Your system is required to maintain
records described in this table, if it is subject to the specific
requirement shown in the first column. For example, if your system uses
slow sand filtration, you would not be required to keep individual
filter turbidity records:
----------------------------------------------------------------------------------------------------------------
Duration of time records
Corresponding requirement Description of necessary records must be kept
----------------------------------------------------------------------------------------------------------------
(a) Individual Filter Turbidity Results of individual filter monitoring... At least 3 years.
Requirements.
-----------------------------------------------------------------------
(b) Disinfection Profiling.............. Results of Profile (including raw data and Indefinitely.
analysis).
-----------------------------------------------------------------------
(c) Disinfection Benchmarking........... Benchmark (including raw data and Indefinitely.
analysis).
-----------------------------------------------------------------------
(d) Covered Reservoirs.................. Date of construction for all uncovered Indefinitely.
finished water reservoirs utilized by
your system.
----------------------------------------------------------------------------------------------------------------
PART 142--NATIONAL PRIMARY DRINKING WATER REGULATIONS IMPLEMENTATION
13. The authority citation for Part 142 continues to read as
follows:
Authority: 42 U.S.C. 300f, 300g-1, 300g-2, 300g-3, 300g-4, 300g-
5, 300g-6, 300j-4, 300j-9, and 300j-11.
14. Section 142.14 is amended by revising paragraphs (a)(3),
(a)(4)(i), (a)(4)(ii) introductory text, and (a)(7) to read as follows:
Sec. 142.14 Records kept by States.
(a)* * *
(3) Records of turbidity measurements must be kept for not less
than one year. The information retained must be set forth in a form
which makes possible comparison with the limits specified in
Secs. 141.71, 141.73, 141.173 and 141.175, 141.550-141.553 and 141.560-
141.563 of this chapter. Until June 29, 1993, for any public water
system which is providing filtration treatment and until December 30,
1991, for any public water system not providing filtration treatment
and not required by the State to provide filtration treatment, records
kept must be set forth in a form which makes possible comparison with
the limits contained in Sec. 141.13 of this chapter.
* * * * *
(4)(i) Records of disinfectant residual measurements and other
parameters necessary to document disinfection effectiveness in
accordance with Secs. 141.72 and 141.74 of this chapter and the
reporting requirements of Secs. 141.75, 141.175, and 141.570, of this
chapter must be kept for not less than one year.
(ii) Records of decisions made on a system-by-system and case-by-
case basis under provisions of part 141, subpart H, subpart P, or
subpart T of this chapter, must be made in writing and kept at the
State.
* * * * *
(7) Any decisions made pursuant to the provisions of part 141,
subpart P or subpart T of this chapter.
(i) Records of systems consulting with the State concerning a
modification to disinfection practice under Secs. 141.172(c),
141.170(d), and 141.544 of this chapter, including the status of the
consultation or approval.
(ii) Records of decisions that a system using alternative
filtration technologies, as allowed under Secs. 141.173(b) and
Sec. 141.552 of this chapter, can consistently achieve a 99.9 percent
removal and/or inactivation of Giardia lamblia cysts, 99.99 percent
removal and/or inactivation of viruses, and 99 percent removal of
Cryptosporidium oocysts. The decisions must include State-set
enforceable turbidity limits for each system. A copy of the decision
must be kept until the decision is reversed or revised. The State must
provide a copy of the decision to the system.
(iii) Records of systems required to do filter self-assessment,
CPE, or CCP under the requirements of Sec. 141.175 and Sec. 141.562 of
this chapter.
* * * * *
15. Section 142.15 is amended by adding paragraphs (c)(6) and
(c)(7) and (c)(8).
Sec. 142.15 Reports by States.
* * * * *
(c) * * *
(6) Recycle return location. A list of all systems moving the
recycle return location prior to the point of primary coagulant
addition. The list must also contain all the systems the State granted
alternate recycle locations, describe the alternative recycle return
location, and briefly discuss the reason(s) the alternate recycle
location was granted and is due [DATE 60 MONTHS AFTER DATE OF
PUBLICATION OF FINAL RULE IN THE FEDERAL REGISTER].
(7) Self assessment determination. A list of all systems performing
self assessments must be reported to EPA. The list must state whether
individual plants exceeded State approved operating capacity during
self assessment monitoring and whether the State required modification
to recycle practice. A brief description of the modification to recycle
practice required at each plant must be provided. If a plant exceeded
State approved operating capacity, and the State did not require
modification of recycle practice, the State must provide a brief
explanation for this decision. Self assessment results must be reported
no later than [DATE 54 MONTHS AFTER DATE OF PUBLICATION OF FINAL RULE
IN THE FEDERAL REGISTER].
(8) Direct filtration determination. A list of all direct
filtration systems recycling within the treatment process must be
submitted to EPA. The list must state which systems were required to
modify recycle practice and briefly describe the modification and the
reason it was required. It must also identify systems not required to
modify recycle practice and provide a brief description of the reason
modification to recycle practice was not required. The list must be
submitted no later than [DATE 54 MONTHS AFTER DATE OF PUBLICATION OF
FINAL RULE IN THE FEDERAL REGISTER].
* * * * *
16. Section 142.16 is amended by adding paragraph (b)(2)(v),
(b)(2)(vi), and (b)(2)(vii) and (i) to read as follows:
Sec. 142.16 Special primacy requirements.
* * * * *
(b) * * *
(2) * * *
(v) The application must describe the criteria the State will use
to determine alternate recycle locations for public water systems
applying to return spent filter backwash, thickener supernatant,
[[Page 19150]]
or liquids from dewatering to an alternate location other than prior to
the point of primary coagulant addition.
(vi) The application must describe the criteria the State will use
to determine whether public water systems completing self assessments
are required to modify recycle practice and the criteria that will be
used to specify modifications to recycle practice.
(vii) The application must describe the criteria the State will use
to determine whether direct filtration systems are required to change
recycle practice and the criteria that will be used to specify changes
to recycle practice.
* * * * *
(i) Requirements for States to adopt 40 CFR part 141, subpart T
Enhanced Filtration and Disinfection. In addition to the general
primacy requirements enumerated elsewhere in this part, including the
requirement that State provisions are no less stringent than the
federal requirements, an application for approval of a State program
revision that adopts 40 CFR part 141, subpart T Enhanced Filtration and
Disinfection, must contain the information specified in this paragraph:
(1) Enforceable requirements. States must have rules or other
authority to require systems to participate in a Comprehensive
Technical Assistance (CTA) activity, the performance improvement phase
of the Composite Correction Program (CCP). The State shall determine
whether a CTA must be conducted based on results of a CPE which
indicate the potential for improved performance, and a finding by the
State that the system is able to receive and implement technical
assistance provided through the CTA. A CPE is a thorough review and
analysis of a system's performance-based capabilities and associated
administrative, operation and maintenance practices. It is conducted to
identify factors that may be adversely impacting a plant's capability
to achieve compliance. During the CTA phase, the system must identify
and systematically address factors limiting performance. The CTA is a
combination of utilizing CPE results as a basis for follow-up,
implementing process control priority-setting techniques and
maintaining long-term involvement to systematically train staff and
administrators.
(2) State practices or procedures. (i) Section 141.536 of this
chapter--How the State will approve a method to calculate the logs of
inactivation for viruses for a system that uses either chloramines or
ozone for primary disinfection.
(ii) Section 141.544 of this chapter--How the State will approve
modifications to disinfection practice.
(iii) Section 141.552 of this chapter--For filtration technologies
other than conventional filtration treatment, direct filtration, slow
sand filtration, diatomaceous earth filtration, or membrane filtration,
how the State will determine that a public water system may use a
filtration technology if the PWS demonstrates to the State, using pilot
plant studies or other means, that the alternative filtration
technology (or membrane filtration), in combination with disinfection
treatment that meets the requirements of Sec. 141.72(b) of this
chapter, consistently achieves 99.9 percent removal and/or inactivation
of Giardia lamblia cysts and 99.99 percent removal and/or inactivation
of viruses, and 99 percent removal of Cryptosporidium oocysts. For a
system that makes this demonstration, how the State will set turbidity
performance requirements that the system must meet 95 percent of the
time and that the system may not exceed at any time at a level that
consistently achieves 99.9 percent removal and/or inactivation of
Giardia lamblia cysts, 99.99 percent removal and/or inactivation of
viruses, and 99 percent removal of Cryptosporidium oocysts.
[FR Doc. 00-8155 Filed 4-7-00; 8:45 am]
BILLING CODE 6560-50-P