[Federal Register Volume 75, Number 202 (Wednesday, October 20, 2010)]
[Rules and Regulations]
[Pages 64864-64907]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2010-25132]
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Part III
Environmental Protection Agency
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40 CFR Parts 51 and 52
Prevention of Significant Deterioration (PSD) for Particulate Matter
Less Than 2.5 Micrometers (PM2.5)--Increments, Significant
Impact Levels (SILs) and Significant Monitoring Concentration (SMC);
Final Rule
Federal Register / Vol. 75 , No. 202 / Wednesday, October 20, 2010 /
Rules and Regulations
[[Page 64864]]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Parts 51 and 52
[EPA-HQ-OAR-2006-0605; FRL-9210-9]
RIN 2060-AO24
Prevention of Significant Deterioration (PSD) for Particulate
Matter Less Than 2.5 Micrometers (PM2.5)--Increments,
Significant Impact Levels (SILs) and Significant Monitoring
Concentration (SMC)
AGENCY: Environmental Protection Agency (EPA).
ACTION: Final rule.
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SUMMARY: The EPA is amending the requirements for particulate matter
less than 2.5 micrometers (PM2.5) under the Prevention of
Significant Deterioration (PSD) program by adding maximum allowable
increases in ambient pollutant concentrations (``increments'') and two
screening tools, known as the Significant Impact Levels (SILs) and a
Significant Monitoring Concentration (SMC) for PM2.5. The
SILs for PM2.5 are also being added to two other New Source
Review (NSR) rules that regulate the construction and modification of
any major stationary source locating in an attainment or unclassifiable
area, where the source's emissions may cause or contribute to a
violation of the national ambient air quality standards (NAAQS).
DATES: This final rule is effective on December 20, 2010.
ADDRESSES: The EPA has established a docket for this action under
Docket ID No. EPA-HQ-OAR-2006-0605. All documents in the docket are
listed on the http://www.regulations.gov Web Site. Although listed in
the index, some information may not be publicly available, e.g.,
Confidential Business Information (CBI) or other information whose
disclosure is restricted by statute. Certain other material, such as
copyrighted material, is not placed on the Internet and will be
publicly available only in hard copy form. Publicly available docket
materials are available either electronically through http://www.regulations.gov or in hard copy at the Air Docket, EPA/DC, EPA
West, Room 3334, 1301 Constitution Avenue, Northwest, Washington, DC.
The Public Reading Room is open from 8:30 a.m. to 4:30 p.m., Monday
through Friday, excluding legal holidays. The telephone number for the
Public Reading Room is (202) 566-1744, and the telephone number for the
Air Docket is (202) 566-1742.
FOR FURTHER INFORMATION CONTACT: Mr. Dan deRoeck, Air Quality Policy
Division, Office of Air Quality Planning and Standards (C504-03), U.S.
Environmental Protection Agency, Research Triangle Park, North Carolina
27711, telephone number: (919) 541-5593, facsimile number: (919) 541-
5509, e-mail address: [email protected].
SUPPLEMENTARY INFORMATION: The information in this Supplementary
Information section of this preamble is organized as follows:
I. General Information
A. Does this action apply to me?
B. Where can I get a copy of this document and other related
information?
II. Purpose
III. Overview of Final PM2.5 PSD Regulations
A. Increments
B. Significant Impact Levels
C. Significant Monitoring Concentration
IV. Background
A. PSD Program
B. History of Particulate Matter (PM) NAAQS
1. Total Suspended Particulate (TSP) and PM10 NAAQS
2. PM2.5 NAAQS
3. Revised PM2.5 and PM10 NAAQS
C. Implementation of NSR for PM2.5
D. Increments Under the PSD Program
E. Historical Approaches for Developing Increments
1. Congressional Enactment of Increments for PM and
SO2
2. EPA's Promulgation of Increments for NO2 and
PM10
a. Increments for NO2 Using the ``Contingent Safe
Harbor'' Approach Under Section 166(a) of the Act
b. Increments for PM10 Using ``Equivalent
Substitution'' Approach Under Section 166(f) of the Act
V. Final Action on PM2.5 Increments
A. Decision To Establish PM2.5 Increments Using
``Contingent Safe Harbor Approach'' Under Section 166(a)
B. Rationale for the Applicability of Section 166(a)
C. EPA's Interpretation of the Requirements Under Sections
166(a)-(d) of the Act
1. Regulations as a Whole Should Fulfill Statutory Requirements
2. Contingent Safe Harbor Approach
3. The Statutory Factors Applicable Under Section 166(c)
4. Balancing the Factors Applicable Under Section 166(c)
5. Authority for States To Adopt Alternatives to Increments
D. Framework for Pollutant-Specific PSD Regulations for
PM2.5
1. Increment System
2. Area Classifications
3. Permitting Procedures
4. AQRV Review by Federal Land Manager (FLM) and Reviewing
Authority
5. Additional Impacts Analysis
6. Installation of BACT
E. Final PM2.5 Increments
1. Identification of Safe Harbor Increments
2. Data Used by EPA for the Evaluation of the Safe Harbor
Increments for PM2.5
3. Scope of Effects Considered
4. Evaluation of the Health and Welfare Effects of
PM2.5
a. Health Effects
b. Welfare Effects
5. Fundamental Elements of Increments
6. Evaluation of the Safe Harbor Increments
7. Compliance Determinations for the PM2.5 Increments
a. Modeling Compliance With PM2.5 Increments
b. Condensable PM
c. PM2.5 Precursors
F. Final Action on Trigger and Baseline Dates for
PM2.5 Increments
G. Definition of ``Baseline Area'' for PM2.5
H. No Final Action With Respect to the Proposed Revocation of
PM10 Annual Increments
I. Other Comments on Increments
VI. Final Action on PM2.5 SILs
A. EPA's Determination on SILs for PM2.5
B. Response to Comments Concerning the SILs
1. Legal Basis for SILs
2. Levels of the SILs
a. Class I SILs
b. Class II and III SILs
3. Relationship Between SILs and AQRVs
4. Form of the SILs
5. SILs for Other Pollutants
VII. Final Action on the PM2.5 SMC
A. EPA's Determination on the PM2.5 SMC
B. Response to Comments Concerning the SMC
1. Legal Issues
2. Level of the SMC
C. Correction of Cross Reference in PSD Ambient Monitoring
Requirements
VIII. Dates Associated With Implementation of the Final Rule
A. Effective Date of the Final Rule
1. State PSD Programs
2. Federal PSD Program
B. Transition Period
C. SILs and SMC for PM2.5
IX. Other Regulatory Changes
X. Statutory and Executive Order Reviews
A. Executive Order 12866--Regulatory Planning and Review
B. Paperwork Reduction Act
C. Regulatory Flexibility Act
D. Unfunded Mandates Reform Act
E. Executive Order 13132--Federalism
F. Executive Order 13175--Consultation and Coordination With
Indian Tribal Governments
G. Executive Order 13045--Protection of Children From
Environmental Health and Safety Risks
H. Executive Order 13211--Actions That Significantly Affect
Energy Supply, Distribution, or Use
I. National Technology Transfer and Advancement Act
J. Executive Order 12898--Federal Actions To Address
Environmental Justice in Minority Populations and Low-Income
Populations
K. Congressional Review Act
XI. Judicial Review
XII. Statutory Authority
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I. General Information
A. Does this action apply to me?
Entities affected by this rule include sources in all industry
groups. The majority of sources potentially affected are expected to be
in the following groups:
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Industry group NAICS \a\
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Electric services................................. 221111, 221112, 221113, 221119, 221121, 221122
Petroleum refining................................ 32411
Industrial inorganic chemicals.................... 325181, 32512, 325131, 325182, 211112, 325998, 331311,
325188
Industrial organic chemicals...................... 32511, 325132, 325192, 325188, 325193, 32512, 325199
Miscellaneous chemical products................... 32552, 32592, 32591, 325182, 32551
Natural gas liquids............................... 211112
Natural gas transport............................. 48621, 22121
Pulp and paper mills.............................. 32211, 322121, 322122, 32213
Paper mills....................................... 322121, 322122
Automobile manufacturing.......................... 336111, 336112, 336712, 336211, 336992, 336322, 336312,
33633, 33634, 33635, 336399, 336212, 336213
Pharmaceuticals................................... 325411, 325412, 325413, 325414
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\a\ North American Industry Classification System.
Entities affected by this rule also include State and local
permitting authorities, and tribal authorities that implement these
regulations.
B. Where can I get a copy of this document and other related
information?
In addition to being available in the docket, an electronic copy of
this final rule will also be available on the World Wide Web. Following
signature by the EPA Administrator, a copy of this final rule will be
posted in the regulations and standards section of our NSR home page
located at http://www.epa.gov/nsr.
II. Purpose
The purpose of this rulemaking is to finalize certain program
provisions under the regulations to prevent significant deterioration
of air quality due to emissions of PM2.5 (i.e., under the
PM2.5 PSD regulations). This final rule supplements the
final implementation rule for PM2.5, known as the Clean Air
Fine Particle Implementation Rule (CAFPIR) that we promulgated on April
25, 2007 (72 FR 20586), and the PM2.5 NSR Implementation
Rule that we promulgated on May 16, 2008 (73 FR 28321). Together, these
three rules encompass the elements necessary for implementation of a
PM2.5 program in any area. This final rule is important
because it establishes increments, SILs, and an SMC for
PM2.5 to facilitate ambient air quality monitoring and
modeling under the PSD regulations for areas designated attainment or
unclassifiable for PM2.5.
III. Overview of Final PM2.5 PSD Regulations
A. Increments
This rulemaking establishes increments for PM2.5
pursuant to the legal authority contained in section 166(a) of the
Clean Air Act (CAA or Act) for pollutants for which NAAQS are
promulgated after 1977. The final PM2.5 increments were
identified as Option 1 in the 2007 Notice of Proposed Rulemaking (NPRM)
for this action, and are as follows:
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NAAQS Increments ([mu]g/m\3\)
Averaging period ([mu]g/ --------------------------------------
m\3\) Class I Class II Class III
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Annual...................................................... 15 1 4 8
24-hour..................................................... 35 2 9 18
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As discussed in more detail in sections V.F and VIII, the
increments for PM2.5 will become applicable on October 20,
2011 in order to comply with section 166(b) of the Act (providing that
regulations under section 166(a) ``shall become effective one year
after the date of promulgation'').
This final rule does not revoke the annual increments for
particulate matter less than 10 micrometers (PM10) as
proposed under Option 1 in the 2007 NPRM. Thus, we are retaining the
24-hour and annual PM10 increments in addition to adding
PM2.5 increments. This outcome is discussed in greater
detail in section V.H of this preamble.
B. Significant Impact Levels
This rule establishes SILs for PM2.5 for evaluating the
impact a proposed new source or modification may have on the NAAQS and
PSD increments for PM2.5. The SILs for PM2.5 were
developed by scaling the existing PM10 SILs using a
PM2.5-to-PM10 NAAQS ratio. The final SILs were
identified as Option 3 in the 2007 NPRM, and are as follows:
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SILs ([mu]g/m\3\)
Averaging period --------------------------------------
Class I Class II Class III
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Annual........................... 0.06 0.3 0.3
24-hour.......................... 0.07 1.2 1.2
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These values will be added to the State implementation plan (SIP)
provisions for PSD at 40 CFR 51.166 (as an optional screening tool) and
the Federal PSD program at 40 CFR 52.21, as well as under the
preconstruction review permit requirements at 40 CFR 51.165(b) and part
51, Appendix S. See a more detailed discussion of the SILs, as well as
the relevant comments and our responses to them, in section VI of this
preamble. The SILs for PM2.5 are incorporated into the
Federal PSD program as well as into the regulations for State-
implemented PSD programs, although they are regarded as optional for
State programs. The effective date for implementing the SILs under the
Federal PSD program is the effective date of this final rule. See
section VIII of this preamble for further discussion of the effective
date.
C. Significant Monitoring Concentration
This final rule establishes the SMC for PM2.5 as 4
[mu]g/m\3\ PM2.5 (24-hour average). This value has been
developed pursuant to proposed Option 1; however, it should be noted
that the value being established in this final rule is lower than the
proposed value of 10 [mu]g/m\3\ that was originally developed under
Option 1. A more detailed discussion of the proposed SMC is presented
in section VII of this preamble, describing the rationale for altering
the proposed SMC, and the relevant comments on the proposed SMC and our
responses to them. The SMC for PM2.5 is incorporated into
the Federal PSD program as well as into the regulations for State-
implemented PSD programs, although they are regarded as optional for
State programs. As with the SILs for PM2.5, the effective
date for implementing the SMC under the Federal PSD program is the
effective date of this final rule. See section VIII of this preamble
for further discussion of the effective date.
IV. Background
A. PSD Program
The NSR provisions of the Act are a combination of air quality
planning and air pollution control technology program requirements for
new and modified stationary sources of air pollution. In brief, section
109 of the Act requires us to promulgate primary NAAQS to protect
public health and secondary NAAQS to protect public welfare. Once we
have set these standards, states must develop, adopt, and submit to us
for approval SIPs that contain emission limitations and other control
measures to attain and maintain the NAAQS and to meet the other
requirements of section 110(a) of the Act. Part C of title I of the Act
contains the requirements for a component of the major NSR program
known as the PSD program. This program sets forth procedures for the
preconstruction review and permitting of new and modified major
stationary sources of air pollution locating in areas meeting the NAAQS
(``attainment'' areas) and areas for which there is insufficient
information to classify an area as either attainment or nonattainment
(``unclassifiable'' areas). Most states have SIP-approved
preconstruction permit (major NSR) programs. The Federal PSD program at
40 CFR 52.21 applies in some states that lack a SIP-approved permit
program, and in Indian country.\1\ The applicability of the PSD program
to a major stationary source must be determined in advance of
construction and is a pollutant-specific determination. Once a major
source is determined to be subject to the PSD program (PSD source),
among other requirements, it must undertake a series of analyses to
demonstrate that it will use the best available control technology
(BACT) and will not cause or contribute to a violation of any NAAQS or
increment. For the latter demonstration, the PSD regulations generally
require sources to submit for review and approval a source impact
analysis and an air quality analysis.
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\1\ We have delegated our authority to some states to implement
the Federal PSD program. The EPA remains the reviewing authority in
non-delegated states lacking SIP-approved programs and in Indian
country.
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The source impact analysis is primarily a modeling analysis
designed to show that the allowable emissions increase from the
proposed project, in conjunction with other emissions increases from
existing sources, will not result in a violation of either the NAAQS or
increments. In cases where the source's emissions may adversely affect
an area classified as a Class I area, additional review is conducted to
protect the increments and special attributes of such an area defined
as ``air quality related values'' (AQRVs).
The air quality analysis must assess the ambient air quality in the
area that the proposed project would affect. For this analysis, the
owner or operator of the proposed project must submit as part of a
complete permit application air quality monitoring data that represent
the air quality in the area affected by the proposed source for the 1-
year period preceding receipt of the application. Where data may
already exist to represent existing air quality, it may be used by the
applicant; otherwise, the source owner or operator is responsible for
the installation and operation of monitors to collect the necessary
data.
Historically, EPA has allowed the use of several types of screening
tools to facilitate implementation of the preconstruction review
process to reduce the permit applicant's burden and streamline the
permitting process for de minimis circumstances. These tools include a
significant emissions rate (SER), SILs, and a SMC. The SER, defined in
tons per year (tpy) for each regulated pollutant, is used to determine
whether the emissions increase from any proposed source or modification
can be excluded from review on the grounds that the increase of any
particular pollutant is de minimis. An emission increase for a
particular pollutant that is greater than the SER defined in the NSR
regulations for that pollutant is considered to be a significant
increase.
The SIL, expressed as an ambient pollutant concentration
(micrograms per cubic meter ([mu]g/m \3\)), is used to determine
whether the ambient impact of a particular pollutant (once it is
determined to be emitted in significant amounts) is significant enough
to warrant a complete source impact analysis involving modeling the
collective impacts of the proposed project and emissions from other
existing sources.
The PSD regulations generally require each PSD applicant to collect
1 year of continuous air quality monitoring data for any pollutant
determined to be subject to preconstruction review as part of complete
PSD permit application. Using the SMC as a screening tool, expressed as
an ambient pollutant concentration ([mu]g/m\3\), sources may be able to
demonstrate that the modeled air
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quality impact of emissions from the new source or modification, or the
existing air quality level in the area where the source would
construct, is less than the SMC, i.e., de minimis, and may be allowed
to forego the preconstruction monitoring requirement for a particular
pollutant at the discretion of the reviewing authority.\2\ See 40 CFR
51.166(i)(5) and 52.21(i)(5).
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\2\ The basic monitoring exemption provision is part of the
original monitoring requirements adopted in the 1980 PSD rulemaking.
45 FR 52676, 52710, August 7, 1980.
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When the reviewing authority reaches a preliminary decision to
authorize construction of a proposed major new source or major
modification, it must provide notice of the preliminary decision and an
opportunity for comment by the general public, industry, and other
persons that may be affected by the emissions of the proposed major
source or major modification. After considering these comments, the
reviewing authority may issue a final determination on the construction
permit in accordance with the PSD regulations.
B. History of Particulate Matter (PM) NAAQS
1. Total Suspended Particulate (TSP) and PM10 NAAQS
The EPA initially established NAAQS for PM in 1971, measured by the
TSP indicator. Based on the size of the particles collected by the
``high-volume sampler,'' which at that time was the reference method
for determining ambient concentrations, TSP included all PM up to a
nominal size of 25 to 45 micrometers. We established both annual and
24-hour NAAQS for TSP.
On July 1, 1987, we revised the NAAQS for PM and changed the
indicator from TSP to PM10; the latter indicator includes
particles with a mean aerodynamic diameter less than or equal to 10
micrometers. The PM10 particles are the subset of inhalable
particles small enough to penetrate to the thoracic region (including
the tracheobronchial and alveolar regions) of the respiratory tract
(referred to as thoracic particles). We established annual and 24-hour
NAAQS for PM10, and revoked the NAAQS for TSP. (52 FR
24634).
2. PM2.5 NAAQS
On July 18, 1997, we again revised the NAAQS for PM in several
respects. While we determined that the NAAQS should continue to focus
on particles less than or equal to 10 micrometers in diameter, we also
determined that the fine and coarse fractions of PM10 should
be considered separately. We established new annual and 24-hour NAAQS
using PM2.5 (referring to particles with a nominal mean
aerodynamic diameter less than or equal to 2.5 micrometers) as the
indicator for fine particles. The 1997 NAAQS rule also modified the
PM10 NAAQS for the purpose of regulating the coarse fraction
of PM10 (referred to as thoracic coarse particles or coarse-
fraction particles; generally including particles with a nominal mean
aerodynamic diameter greater than 2.5 micrometers and less than or
equal to 10 micrometers, or PM10-2.5); however, this part of
the rulemaking was vacated during subsequent litigation, leaving the
pre-existing 1987 PM10 NAAQS in place (62 FR 38652).
3. Revised PM2.5 and PM10 NAAQS
On October 17, 2006, we promulgated revisions to the NAAQS for
PM2.5 and PM10 with an effective date of December
18, 2006 (71 FR 61144). We lowered the 24-hour NAAQS for
PM2.5 from 65 [micro]g/m\3\ to 35 [micro]g/m\3\, and
retained the existing annual PM2.5 NAAQS of 15 [micro]g/
m\3\. In addition, we retained the existing PM10 24-hour
NAAQS of 150 [micro]g/m\3\, and revoked the annual PM10
NAAQS (set at 50 [micro]g/m\3\).
C. Implementation of NSR for PM2.5
After we established new annual and 24-hour NAAQS based on
PM2.5 as the indicator for fine particles in July 1997, we
issued a guidance document titled ``Interim Implementation for the New
Source Review Requirements for PM2.5,'' John S. Seitz,
Director, Office of Air Quality Planning and Standards, EPA, October
23, 1997. As noted in that guidance, section 165 of the Act implies
that certain PSD requirements become effective for a new NAAQS upon the
effective date of the NAAQS. Section 165(a)(1) of the Act provides that
no new or modified major source may be constructed without a PSD permit
that meets all of the section 165(a) requirements with respect to the
regulated pollutant. Moreover, section 165(a)(3) provides that the
emissions from any such source may not cause or contribute to a
violation of any increment or NAAQS. Also, section 165(a)(4) requires
BACT for each pollutant subject to PSD regulation. The 1997 guidance
stated that sources would be allowed to use implementation of a
PM10 program as a surrogate for meeting PM2.5 NSR
requirements until certain difficulties were resolved. These
difficulties included the lack of necessary tools to calculate the
emissions of PM2.5 and related precursors, the lack of
adequate modeling techniques to project ambient impacts, and the lack
of PM2.5 monitoring sites.
On April 5, 2005, we issued a guidance document entitled
``Implementation of New Source Review Requirements in PM-2.5
Nonattainment Areas,'' Stephen D. Page, Director, Office of Air Quality
Planning and Standards, EPA. This memorandum provided guidance on the
implementation of the nonattainment major NSR provisions in
PM2.5 nonattainment areas in the interim period between the
effective date of the PM2.5 NAAQS designations (April 5,
2005) and when we promulgate regulations to implement nonattainment
major NSR for the PM2.5 NAAQS. In addition to affirming the
continued use of the John S. Seitz guidance memo in PM2.5
attainment areas, this memo recommended that, until we promulgated the
PM2.5 major NSR regulations, states should use a
PM10 nonattainment major NSR program as a surrogate to
address the requirements of nonattainment major NSR for the
PM2.5 NAAQS.
On November 1, 2005, we proposed a rule to implement the
PM2.5 NAAQS, including proposed revisions to the NSR
program. For those states with EPA-approved PSD programs, we proposed
to continue the 1997 NSR guidance to use PM10 as a surrogate
for PM2.5, but only during the SIP development period. We
also indicated in that proposal that we would be developing increments,
SILs, and an SMC in a separate rulemaking, i.e., this final rule. Since
there was an interim surrogate NSR program in place, i.e., the
PM10 Surrogate Policy, EPA decided to first promulgate the
non-NSR part of the implementation rule (including attainment
demonstrations, designations, control measures, etc.). This rule was
promulgated as the CAFPIR on April 25, 2007 (72 FR 20586).
The NSR part of the implementation rule was issued separately as a
final rule on May 16, 2008 (73 FR 28321), and included sets of NSR
regulations for both attainment (PSD) and nonattainment areas
(nonattainment NSR) for PM2.5. In the May 16, 2008 rule we
added one of the important screening tools--the SER--for
PM2.5. The SER for PM2.5 is defined as an
emissions rate of 10 tpy for direct PM2.5 emissions. We also
listed sulfur dioxide (SO2) and nitrogen oxides
(NOX) as precursors of ambient PM2.5 and defined
``significant'' as 40 tpy or more of either precursor pollutant. States
were allowed up to 3 years from the date of publication in the Federal
Register to
[[Page 64868]]
revise their SIPs and submit their revised NSR programs to EPA for
approval.
D. Increments Under the PSD Program
Under section 165(a)(3) of the Act, a PSD permit applicant must
demonstrate that emissions from the proposed construction and operation
of a facility ``will not cause, or contribute to, air pollution in
excess of any (A) maximum allowable increase or maximum allowable
concentration for any pollutant * * *.'' The ``maximum allowable
increase'' of an air pollutant that is allowed to occur above the
applicable baseline concentration for that pollutant is known as the
PSD increment. By establishing the maximum allowable level of ambient
pollutant concentration increase in a particular area, an increment
defines ``significant deterioration'' of air quality in that area.
For PSD baseline purposes, a baseline area for a particular
pollutant emitted from a source includes the attainment or
unclassifiable area in which the source is located, as well as any
other attainment or unclassifiable area in which the source's emissions
of that pollutant are projected (by air quality modeling) to result in
a significant ambient pollutant increase. See, e.g., 40 CFR
52.21(b)(15)(i). Once the baseline area is established, subsequent PSD
sources locating in that area need to consider that a portion of the
available increment may have already been consumed by previous
emissions increases.
In general, the submittal date of the first complete PSD permit
application in a particular area is the operative ``baseline date.''
\3\ On or before the date of the first complete PSD application,
emissions generally are considered to be part of the baseline
concentration, except for certain emissions from major stationary
sources, as explained in the following discussion of baseline dates.
Most emissions increases that occur after the baseline date will be
counted toward the amount of increment consumed. Similarly, emissions
decreases after the baseline date restore or expand the amount of
increment that is available.
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\3\ Baseline dates are pollutant specific. That is, a complete
PSD application establishes the baseline date only for those
regulated NSR pollutants that are projected to be emitted in
significant amounts (as defined in the regulations) by the
applicant's new source or modification. Thus, an area may have
different baseline dates for different pollutants.
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In practice, three dates related to the PSD baseline concept are
important in understanding how to calculate the amount of increment
consumed-- (1) Trigger date; (2) major source baseline date; and (3)
minor source baseline date. The first relevant date is the trigger
date. The trigger date, as the name implies, triggers the overall
increment consumption process nationwide. Specifically, this is a fixed
date, which must occur before the minor source baseline date can be
established for the pollutant-specific increment in a particular
attainment area. See, 40 CFR 51.166(b)(14)(ii) and 52.21(b)(14)(ii).
For PM (regulated as TSP) and SO2, Congress defined the
applicable trigger date as August 7, 1977--the date of the 1977
amendments to the Act when the original statutory increments were
established by Congress. For nitrogen dioxide (NO2), we
selected the trigger date as February 8, 1988--the date on which we
proposed increments for NO2. See 53 FR 40656, 40658; October
17, 1988. In this final rule, as described later, we are establishing a
separate trigger date for purposes of implementing the PM2.5
increments. See section V.F of this preamble for additional discussion
of the trigger date for PM2.5.
The two remaining dates--``minor source baseline date'' and ``major
source baseline date''--as described later, are necessary to properly
account for the emissions that are to be counted toward the amount of
increment consumed following the national trigger date, in accordance
with the statutory definition of ``baseline concentration'' in section
169(4) of the Act. The statutory definition provides that the baseline
concentration of a pollutant for a particular baseline area is
generally the air quality at the time of the first application for a
PSD permit in the area. Consequently, any increases in actual emissions
occurring after that date (with some possible exceptions that we will
discuss later) would be considered to consume the applicable PSD
increment. However, the statutory definition in section 169(4) also
provides that ``[e]missions of sulfur oxides and particulate matter
from any major emitting facility on which construction commenced after
January 6, 1975, shall not be included in the baseline and shall be
counted in pollutant concentrations established under this part.''
To make this distinction between the date when emissions resulting
from the construction at a major stationary source consume the
increment and the date when emissions changes in general (i.e., from
both major and minor sources) begin to consume the increment, we
established the terms ``major source baseline date'' and ``minor source
baseline date,'' respectively. See 40 CFR 51.166(b)(14) and
52.21(b)(14). Accordingly, the ``major source baseline date,'' which
precedes the trigger date, is the date after which actual emissions
increases associated with construction at any major stationary source
consume the PSD increment. In accordance with the statutory definition
of ``baseline concentration,'' the PSD regulations define a fixed date
to represent the major source baseline date for each pollutant for
which an increment exists. Congress defined the major source baseline
date for the statutory increments for PM and SO2 as January
6, 1975. For the NO2 increments, which we promulgated in
1988 under our authority to establish an increment system under section
166(a) of the Act, the major source baseline date we selected was
February 8, 1988--the date on which we proposed increments for
NO2. 53 FR 40656. In both instances, the major source
baseline date for the individual increments was set as a date which
preceded the date on which the regulations pertaining to those
increments were issued. In this final rule, as described later, we are
establishing a separate major source baseline date for implementing the
PM2.5 increments. See section V.F of this preamble for
further discussion of the major source baseline date for
PM2.5.
The ``minor source baseline date'' is the earliest date after the
trigger date on which a source or modification submits the first
complete application for a PSD permit in a particular area. After the
minor source baseline date, any increase in actual emissions (from both
major and minor sources) consumes the PSD increment for that area.
Once the minor source baseline date is established, the new
emissions increase from that major source consumes a portion of the
increment in that area, as do any subsequent actual emissions increases
that occur from any new or existing source in the area. When the
maximum pollutant concentration increase defined by the increment has
been reached, additional PSD permits cannot be issued until sufficient
amounts of the increment are ``freed up'' via emissions reductions that
may occur voluntarily, (e.g., via source shutdowns) or by mandatory
control requirements imposed by the reviewing authority. Moreover, the
air quality in a region cannot deteriorate to a level in excess of the
applicable NAAQS, even if all the increment in the area has not been
consumed. Therefore, new or modified sources located in areas where the
air pollutant concentrations are near the level allowed by the NAAQS
may not have full use of the amount of
[[Page 64869]]
pollutant concentration increase allowed by the increment.
Under EPA guidance, the actual increment analysis that a proposed
new or modified source undergoing PSD review must complete depends on
the area impacted by the source's new emissions. We have provided
approved air quality models and guidelines for sources to use to
project the air quality impact of each pollutant (over each averaging
period) for which an increment analysis must be done.\4\ In addition,
we established SILs for each pollutant under the permit requirements
applicable to new and modified major stationary sources locating in
attainment areas that would cause or contribute to a violation of any
NAAQS. See 40 CFR 51.165(b) and part 51, Appendix S, section III.A.
These SILs have also been used for implementing the PSD program to
identify levels below which the source's modeled impact of a particular
pollutant is regarded as de minimis. In this final rule, we are
establishing SILs (24-hour and annual) for PM2.5 that are
being added to the aforementioned regulations containing SILs for other
pollutants, as well as to the PSD regulations in 40 CFR 51.166 and
52.21. See further discussion of the SILs for PM2.5 in
section VI of this preamble.
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\4\ See EPA's ``Guideline on Air Quality Models'' at 40 CFR part
51, Appendix W.
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In the event that a source's modeled impacts of a particular
pollutant are below the applicable SIL at all ambient air locations
modeled, i.e., de minimis everywhere, EPA's policy for PSD provides
that no further modeling analysis is required for that pollutant. Our
longstanding policy under the PSD program is that when a preliminary
screening analysis based on the SIL is sufficient to demonstrate that
the source's emissions throughout the area modeled will not cause or
contribute to a violation of the increment, there is no need for a
comprehensive source impact analysis involving a cumulative evaluation
of the emissions from the proposed source and other sources affecting
the area.
Within the impact area of a source subject to PSD, that is, the
area within which the proposed project's emissions increase does have a
significant impact, increment consumption is calculated using the
source's proposed emissions increase, along with other actual emissions
increases or decreases of the particular pollutant from any sources in
the area, which have occurred since the minor source baseline date
established for that area. In addition, the emissions increases or
decreases from any major source that has commenced construction since
the major source baseline date (which precedes the minor source
baseline date) will consume or expand increment. Thus, an emissions
inventory of sources whose emissions, in whole or in part, of a
particular pollutant consume or expand the available increment in the
area must be compiled. The inventory of increment-consuming emissions
includes not only sources located directly in the impact area, but
sources outside the impact area that affect the air quality for the
particular pollutant within the impact area.
The inventory of increment-consuming emissions includes emissions
from increment-affecting sources at two separate time periods--the
baseline date and the current period of time. For each source that was
in existence on the relevant baseline date (major source or minor
source), the inventory includes the source's actual emissions on the
baseline date and its current actual emissions. The change in emissions
over these time periods represents the emissions that consume increment
(or, if emissions have gone down, expand the available increment). For
sources constructed since the relevant baseline date, all their current
actual emissions consume increment and are included in the inventory.
When the inventory of increment-consuming emissions has been
compiled, computer modeling is used to determine the change in ambient
concentration that will result from these emissions when combined with
the proposed emissions increase from the new major source or major
modification that is undergoing PSD review. The modeling has generally
been guided by the ``Guideline on Air Quality Models'' (40 CFR part 51,
Appendix W), which includes provisions on air quality models and the
meteorological data input into these models. The model output
(expressed as a change in concentration) for each relevant averaging
period is then compared to the corresponding allowable PSD increment.
E. Historical Approaches for Developing Increments
1. Congressional Enactment of Increments for PM and SO2
Congress established the first increments defining significant
deterioration of air quality in the 1977 Amendments to the Act. These
amendments, among other things, added part C to title I, setting out
the requirements for PSD. In section 163, Congress included numerical
increments for PM and SO2 for Class I, II, and III areas.
The three area classes are part of the increment system originally
established by Congress. Congress designated Class I areas (including
certain national parks and wilderness areas) as areas of special
national concern, where the need to prevent deterioration of air
quality is the greatest. Consequently, the allowable level of
incremental change is the smallest relative to the other area classes,
i.e., most stringent, in Class I areas. The increments of Class II
areas are larger than those of Class I areas and allow for a moderate
degree of emissions growth. For future redesignation purposes, Congress
defined a ``Class III'' classification to allow the redesignation of
any existing Class II area for which a State may desire to promote a
higher level of industrial development (and emissions growth). Thus,
Class III areas are allowed to have the greatest amount of pollutant
increase of the three area classes while still achieving the NAAQS. To
date, there have been no redesignations made to establish a Class III
area.
In establishing these PSD increments, Congress used the then-
existing NAAQS for those pollutants as the benchmark for determining
what constitutes ``significant deterioration.'' Congress established
the increments for PM as a percentage of the then-existing PM NAAQS. At
the time the Act was amended in 1977, the NAAQS for PM were expressed
in terms of ambient concentrations of TSP. Thus, EPA interpreted the
statutory increments for PM using the same ambient TSP ``indicator.''
2. EPA's Promulgation of Increments for NO2 and
PM10
Congress also provided authority for EPA to promulgate additional
increments and to update the original PM increments created by statute.
The EPA has promulgated two regulations pursuant to this authority.
a. Increments for NO2 Using the ``Contingent Safe Harbor''
Approach Under Section 166(a) of the Act
Based on section 166(a) of the Act, on October 17, 1988, EPA
promulgated increments for NO2 to prevent significant
deterioration of air quality due to emissions of NOX (53 FR
40656). The EPA based these increments on percentages of the NAAQS in
the same way that Congress derived the statutory increments for PM and
SO2. Those NO2 increments were challenged in 1988
by the Environmental Defense Fund (EDF) when EDF filed suit in the U.S.
Court of
[[Page 64870]]
Appeals for the District of Columbia Circuit against the Administrator
(Environmental Defense Fund, Inc. v. Reilly, No. 88-1882). The EDF
successfully argued that we failed to sufficiently consider certain
provisions in section 166 of the Act. The court remanded the case to
EPA ``to develop an interpretation of section 166 that considers both
subsections (c) and (d), and if necessary to take new evidence and
modify the regulations.'' See Environmental Defense Fund v. EPA, 898
F.2d 183, 190 (D.C. Cir. 1990) (EDF v. EPA). Section 166(c) of the Act
requires the PSD regulations to, among other things, meet the goals and
purposes set forth in sections 101 and 160 of the Act. Section 166(d)
requires these regulations be at least as effective as the increments
established for PM (in the form of TSP) and SO2 in section
163 of the Act. The court considered the NO2 increment
values determined using the percentage-of-NAAQS approach as ``safe
harbor'' increments which met the requirements of section 166(d) of the
Act. However, the court also determined that EPA's reliance on such
increment levels was contingent upon our completing the analyses
required under section 166(c), which provided that the final increment
values must address the goals of sections 101 and 160 of the Act to
protect public health and welfare, parks, and AQRVs \5\ and to insure
economic growth.
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\5\ The term ``air quality related values'' is not defined in
the Act, but the legislative history provides language saying that
``The term `air quality related values' of Federal lands designated
as Class I includes the fundamental purposes for which such lands
have been established and preserved by the Congress and the
responsible Federal agency. For example, under the 1916 Organic Act
to establish the National Park Service (16 U.S.C. 1), the purpose of
such national park lands `is to conserve the scenery and the natural
and historic objects and the wildlife therein and to provide for the
enjoyment of the same in such manner and by such means as will leave
them unimpaired for the enjoyment of future generations.' '' S. Rep.
No. 95-127 at 36 (1977).
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In response to the court's decision, we proposed rulemaking on
increments for NO2 on February 23, 2005 (70 FR 8880) and
finalized the rule on October 12, 2005 (70 FR 59582). In the final
rule, we established our policy on how to interpret and apply the
requirements of sections 166(c) and (d) of the Act. In accordance with
the court ruling, we conducted further analyses (considering the health
and welfare effects of NOX) and concluded that the existing
NO2 increments were adequate to fulfill the requirements of
section 166(c). See 70 FR 59586 for our detailed analysis of how
pollutant regulations satisfy the requirements of section 166 of the
Act. Hence, we retained the existing NO2 increments along
with other parts of the existing framework of pollutant-specific
NO2 increment regulations. We also amended the PSD
regulations under 40 CFR 51.166 to make it clear that states may seek
EPA approval of SIPs that utilize a different approach than EPA used to
establish these NO2 increments. To receive our approval of
an alternative program, a State must demonstrate that its program
satisfies the requirements of sections 166(c) and 166(d) of the Act and
prevents significant deterioration of air quality from emissions of
NOX.\6\
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\6\ Under the 2005 NOX regulation, states can adopt
measures other than increments as long as they can demonstrate that
the measures selected comply with the same criteria and goals of
sections 166(c) and (d) of the Act that must be met for increments.
---------------------------------------------------------------------------
b. Increments for PM10 Using ``Equivalent Substitution''
Approach Under Section 166(f) of the Act
On October 5, 1989, we proposed PM10 increments. See 54
FR 41218. Although section 163 did not expressly define the existing
statutory increments for PM in terms of a specific indicator, EPA
reasoned that Congress' knowledge that TSP was the indicator for the PM
NAAQS, and that the TSP standards were the starting point for the
increments levels when the increments were established in 1977, meant
that TSP was also the appropriate measure for the PM increments in
section 163. As a consequence, EPA believed that the statutory PM
increments could not simply be administratively redefined as
PM10 increments, retaining the same numerical values,
following the revision of the PM NAAQS. Rather, we stated our belief
that with the promulgation of the PM10 NAAQS, EPA had both
the responsibility and the authority under sections 166 and 301 of the
Act to promulgate new increments for PM to be measured in terms of
PM10. We further concluded that promulgating PM10
increments to replace, rather than supplement, the statutory TSP
increments under section 163 represented the most sensible approach for
preventing significant deterioration with respect to PM. See 54 FR
41220-41221.
We promulgated PM10 increments to replace the then-
existing TSP increments on June 3, 1993 (58 FR 31622). In the interim
between proposal and promulgation, Congress enacted the 1990 CAA
Amendments. As part of these amendments, Congress amended section 166
to add a new section 166(f). This section specifically authorized EPA
to substitute PM10 increments for the existing section 163
PM increments based on TSP, provided that the substituted increments
are ``of equal stringency in effect'' as the section 163 increments.
Thus, we were able to replace the TSP increments under section 163
of the Act using PM10 increments based directly on the newly
enacted authority under section 166(f) of the Act. In the
PM10 rule, we maintained the existing baseline dates and
baseline areas for PM that had been previously established using the
TSP indicator. Also, as proposed, we promulgated PM10
increments based on an approach we called the ``equivalent to statutory
increments'' approach. Under this approach, we used the original TSP
increments as a benchmark for calculating the PM10
increments, thereby retaining roughly the same limitations on future
deterioration of air quality as was allowed under the TSP increments.
In using this approach, we considered the historical consumption of
TSP increment by a sample population of permitted PSD sources, and then
determined the PM10 increments for each area classification
and averaging time that would provide approximately the same percentage
of PM10 increment consumption, on average, by the same
population of sources. Then, all future calculations of increment
consumption after the PM10 implementation date would be
based on PM10 emissions. See 58 FR 31622 and 31625.
V. Final Action on PM2.5 Increments
In this section of the preamble, we will summarize the
considerations that went into our proposed action and describe the
final action being taken regarding new regulations for preventing
significant deterioration of PM2.5 air quality--including
PM2.5 increments (sections V.A through V.E, baseline dates
and other permit requirements for PM2.5 (section V.F),
baseline areas for PM2.5 (section V.G), and PM10
increments (section V.H).
A. Decision To Establish PM2.5 Increments Using ``Contingent
Safe Harbor Approach'' Under Section 166(a)
The EPA's 2007 NPRM contained three options for developing
numerical PM2.5 increments. Option 1 used the authority of
section 166(a) of the Act to establish increments for PM2.5
as a new pollutant for which NAAQS were established after August 7,
1977, and established 24-hour and annual PM2.5 increments
(Class I, II, and III) based on the ``contingent safe harbor''
approach. Options 2 and 3 used the contingent safe harbor approach
under section 166(a) to only develop 24-hour PM2.5
increments (Class I, II, and III), while using the ``equivalent
substitution''
[[Page 64871]]
approach under section 166(f) of the Act to develop annual
PM2.5 increments. Each of these options is discussed in
detail in the 2007 NPRM. 72 FR 54123-54138. In addition, significant
comments on each of the three options, and our responses to them, are
provided in this section V of this preamble.
In this final rule, after considering the available information and
comments from interested parties, EPA has decided to select Option 1
and establish increments for PM2.5 using the ``contingent
safe harbor'' approach in accordance with the authority provided in
section 166(a) of the Act.
This final rule establishes increments for PM2.5 at the
following levels:
----------------------------------------------------------------------------------------------------------------
NAAQS Increments ([micro]g/m\3\)
Averaging period ([micro]g/ --------------------------------------
m\3\) Class I Class II Class III
----------------------------------------------------------------------------------------------------------------
Annual...................................................... 15 1 4 8
24-hour..................................................... 35 2 9 18
----------------------------------------------------------------------------------------------------------------
B. Rationale for the Applicability of Section 166(a)
In the 2007 NPRM, we expressed our belief that it is permissible to
interpret section 166(a) to apply to PM2.5. Section 166(a)
requires EPA to develop regulations to prevent the significant
deterioration of air quality due to emissions of certain named
pollutants, and to develop such regulations for any pollutants for
which NAAQS are subsequently promulgated. Although EPA has generally
characterized the NAAQS for PM2.5 as a NAAQS for a new
indicator of PM, EPA did not replace the PM10 NAAQS with the
NAAQS for PM2.5 when the latter NAAQS were promulgated in
1997. Rather, EPA retained the annual and 24-hour PM10 NAAQS
(retaining PM10 as an indicator of coarse particulate
matter), and established new annual and 24-hour NAAQS for
PM2.5 as if PM2.5 was a new pollutant, even
though EPA had already developed air quality criteria for PM generally.
Thus, for purposes of section 166(a), the promulgation of a NAAQS for
PM2.5 established a NAAQS for an additional pollutant after
1977.
Nine commenters supported our proposed Option 1, although only
three of these explicitly expressed support for the use of section
166(a) authority to promulgate PM2.5 increments. Ten other
commenters specifically opposed the use of section 166(a) authority
and/or supported the use of section 166(f) authority (on which the
annual increments under Options 2A and 2B were based).
One of the commenters who explicitly agreed with our proposed use
of section 166(a) authority stated that it is the only option that is
legally available. This commenter asserted that section 166(a) plainly
applies to PM2.5 because PM2.5 is a pollutant for
which NAAQS were promulgated after August 7, 1977. This commenter held
that EPA's rulemaking duty under section 166(a) is not confined to
``new pollutants,'' but is triggered by post-1977 NAAQS promulgations,
regardless of whether for new or previously regulated pollutants. On
the other hand, this commenter noted that by its terms, section 166(f)
is limited to authorizing the adoption of PM10 increments as
a substitute for the statutory TSP increments and does not provide for
substitution of PM2.5 increments for TSP or PM10
increments.
The opposing commenters did not believe that section 166(a)
provides a legal basis for EPA to promulgate PM2.5
increments. One of these commenters stated that section 166(a) can only
be used for a new pollutant, and PM2.5 is not a new
pollutant.
Another commenter who opposed the use of section 166(a) authority
argued that nothing in section 166(a) of the Act can be interpreted to
allow it to be used as the basis of increments when EPA revises an
existing NAAQS. The commenter explained that, on its face, section
166(a) can only be interpreted to apply to pollutants other than PM and
SO2 since increments for these pollutants were enacted by
Congress in section 163 of the Act. The commenter added that it can be
argued that Congress intended to have section 166(a) apply to the four
other pollutants specifically listed there.
This commenter found unpersuasive our argument that we are not
``substituting'' increments (as section 166(f) requires for
PM10) but rather adding PM2.5 increments to the
existing PM10 increments, and that only section 166(a)
allows such an approach (72 FR 54121). The commenter asserted that if
EPA had defined a coarse fraction to the particulate matter standards,
then that fraction, together with the PM2.5 standards, would
form the set of ``substituted'' new standards for the existing
PM10 standards, and, thus, the increments.
The commenter also disagreed with EPA's argument that it can treat
PM2.5 as a new pollutant under section 166(a) of the Act
since it has been demonstrated that sub-PM2.5 particles have
distinctly different health and welfare effects than the other forms of
PM (i.e., coarse or PM10). The commenter indicated that just
as EPA replaced the TSP standards by PM10 as a better
indicator of health effects, ongoing research has led to establishment
of the PM2.5 standards as a better indicator of certain
health effects, and it is the natural outcome of such research that has
enabled EPA to separate the effect of total particulate matter into two
fractions with distinct effects. The commenter added that given that
the definition of particulate matter includes a vast conglomeration of
solids and liquids, the finding of differing effects should not come as
a surprise. The commenter explained that as is the case of different
pollutants having similar effects that are, nonetheless, treated as
separate pollutants, the same concept should apply to a range or
fraction of particulate matter found to have different effects in
establishing it as another indicator and not a different pollutant.
The commenter did not disagree with the specific numerical
increments proposed by EPA under Option 1, but did have concerns with
the potential consequences of the section 166(a) approach. The
commenter's primary concern was the proposal to allow states to
substitute other measures in the place of uniform national increments
for PM2.5. (This is discussed further in section V.C.5 of
this preamble.) Another commenter also expressed this concern.
Another commenter who opposed the section 166(a) approach believes
that the legal and congressional history regarding the establishment of
PM increments shows that Congress added section 166(f) to the Act based
on the conviction that without it, EPA had no authority to revise the
PM increments for PM10 (citing and quoting from S. Rep. No.
228, 101st Cong., 2nd Sess. 75 (1990), reprinted in 1990 U.S.C.C.A.N.
3385, 3461). The commenter concluded that EPA did not have authority in
1987 under section 166(a) to adopt PM10 increments, and does
not have authority now under section 166(a) to adopt PM2.5
increments.
We read section 166(a) to authorize EPA to promulgate pollutant-
specific PSD regulations meeting the
[[Page 64872]]
requirements of sections 166(c) and 166(d) for any pollutant for which
EPA promulgates a NAAQS after 1977. Most of the pollutants identified
in section 166(a) (NOX, photochemical oxidants, carbon
monoxide) are pollutants for which EPA had established NAAQS in 1977
when Congress adopted section 166 of the Act. There was no need for
Congress to list other criteria pollutants, SO2 and PM, in
section 166(a) because Congress had already established increments for
these pollutants in section 163 of the Act. In addition to requiring
regulations for the enumerated pollutants, we conclude that under
section 166 of the Act Congress intended to authorize EPA to establish
additional pollutant-specific PSD regulations, potentially containing
increments, for any additional pollutants for which EPA promulgated a
NAAQS under section 109 of the Act. Furthermore, because the Act refers
to pollutants for which EPA promulgates NAAQS after 1977, and does not
use the phrase ``additional pollutants,'' section 166(a) provides
authority for EPA to promulgate new increments after revising an
existing NAAQS (including NAAQS first promulgated before 1977), when we
find that such action is appropriate.
Moreover, any new increments developed pursuant to section 166(a)
have no effect on existing increments, as there is no indication
therein that an existing increment should be revoked or replaced when
additional increments are promulgated. This was the situation following
the promulgation of new NAAQS for PM in 1987 when EPA replaced the old
NAAQS based on TSP with new ones based on PM10. Had Congress
not added new section 166(f) in 1990, increments for PM10
could have been developed pursuant to section 166(a) of the Act, but
such increments would have had no effect on the original statutory
increments for PM (based on TSP). Consequently, seeing no basis for
retaining the original increments, Congress added section 166(f) which
explicitly provides for the replacement of the existing increments with
PM10 increments.
One commenter asserted that if EPA establishes increments for
PM2.5 under the authority of section 166(a) on the basis
that PM2.5 is a new pollutant, then it must also establish
PM10 increments under section 166(a) because (according to
the commenter's analysis) PM10 is also a new pollutant. In
the same analysis, the commenter concluded that EPA must adopt new
measures to prevent significant deterioration from coarse PM based on
section 166(a).
In this final rule, EPA is not setting or amending any increments
for PM10 or otherwise taking action with respect to
PM10 increments. The preexisting annual and 24-hour
increments for PM10 are being retained. See section V.H.
Similarly, EPA is not taking any action with respect to coarse PM in
this rule. For these reasons, the commenter's arguments on what
authority must be used to set increments for PM10 and/or
coarse PM, and that EPA has some obligation to take action with respect
to coarse PM, are not on point for this rule. Thus, no substantive
response to this comment is needed. Nevertheless, as mentioned earlier,
Congress provided explicit authority under section 166(f) of the Act to
address increments for PM10, because it intended for such
increments to be substitute increments for the original statutory
increments for PM measured as TSP. Thus, the PM10 increments
legally supersede the original statutory increments for PM. Had the
PM10 increments been developed under section 166(a), which
prior to the 1990 Act Amendments was the only authority available for
developing new increments, then the original statutory PM increments
would have remained in effect in addition to the PM10
increments.
One commenter expressed general objections to EPA's legal rationale
for the PM2.5 increments proposal, asserting that we failed
to expressly state and support our legal authority for the
PM2.5 increments, offering two possible sources of authority
(``contingent safe harbor,'' ``equivalent substitution,'' or possibly a
combination of the two) but never stating our legal position with
clarity. The commenter agreed with EPA's assessment that the
PM2.5 increments should and must fulfill the legal
requirements of the Act (72 FR 54121), and added that it is the
government's burden of proof to establish its legal authority for
action. The commenter stated that it would be arbitrary and capricious
to promulgate these regulations for which EPA has not stated legal
authority.
We do not disagree that the 2007 NPRM described two different legal
authorities for the two different options for establishing increments,
but we disagree that these discussions did not clearly present the
alternative legal bases that the Agency was considering for taking
action in this rule. In particular, we clearly described our legal
authority for developing the 24-hour and annual PM2.5
increments under section 166(a) of the Act, which is the basis on which
we are taking final action in this rule.\7\ First, we expressly stated
that Option 1 was based on the statutory authority of section 166(a) of
the Act. See 72 FR 54123 (Under the first option, ``we would use the
authority of section 166(a) of the Act to develop new increments for
PM2.5''). Second, we provided a discussion of this authority
both in general (see 72 FR 54118-54119 and 54120-54123), and how it
would be applied to establish increments for PM2.5 (see 72
FR 54119-120 and 54123-136).
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\7\ We also believe that we sufficiently described how section
166(f) might provide alternative authority for establishing
increments for PM2.5 (see, e.g., 72 FR 54120-54121), but
will not address that in detail here because the increments in this
rule are not based on section 166(f) authority.
---------------------------------------------------------------------------
We now believe that section 166(a) provides the most
straightforward approach for developing increments for a pollutant or
pollutant indicator for which no increments have yet been established.
Our position is also consistent with the comments we received which
supported the delay in implementation of the PM2.5
increments, opposed the potential for two sets of definitions for
``major source baseline date'' and ``trigger date'' for the
PM2.5 increment system, and highlighted the complexities
involved with having to establish and maintain two sets of emissions
inventories for the 24-hour and annual PM2.5 increments.
(See further description of relevant comments in section VIII of this
section.)
C. EPA's Interpretation of the Requirements Under Sections 166(a)-(d)
of the Act
In section 166(a) of the Act, Congress directed EPA to develop
pollutant-specific regulations to prevent significant deterioration of
air quality. Congress further specified that such regulations meet
specific requirements set forth in sections 166(c) and 166(d) of the
Act. We stated in the 2007 NPRM that because we believed that section
166(a) could be applied to the development of increments for
PM2.5, we would follow the interpretation of sections
166(a)-(d) that the Agency adopted in its most recent NO2
increments rule. 70 FR 59582, October 12, 2005. That particular
interpretation and application was upheld in Environmental Defense v.
EPA, 489 F.3d 1320 (D.C. Cir. 2007).
The EPA's interpretation of these provisions is grounded on five
principles and conclusions. First, we read section 166 of the Act to
direct EPA to conduct a holistic analysis that considers how a complete
system of regulations will collectively satisfy the
[[Page 64873]]
applicable criteria, rather than evaluating one individual part of a
regulatory scheme in isolation. Second, we use a ``contingent safe
harbor'' approach which calls for EPA to first determine an increment
that is at least as effective as the increments in section 163 of the
Act, as required under section 166(d) and then to conduct further
analysis to determine if additional measures are necessary to fulfill
the requirements of section 166(c). Third, we interpret section 166(c)
of the Act to identify eight statutory factors that EPA must apply when
promulgating pollutant-specific regulations to prevent significant
deterioration of air quality. Fourth, where these factors are at odds
with each other, we interpret the statute to require EPA to use its
judgment to balance the conflicting factors. Fifth, we recognize that
the requirements of section 166 may be satisfied by adopting other
measures besides an increment and that EPA may allow states to
demonstrate that alternatives to increments contained in a SIP meet the
requirements of sections 166(c) and 166(d). Below is a brief discussion
of each of these five principles and conclusions. A more detailed
description of each of these is contained in the 2007 NPRM at 72 FR
54121-54123.
1. Regulations as a Whole Should Fulfill Statutory Requirements
Section 166(a) of the Act directs EPA to develop pollutant-specific
regulations to prevent the significant deterioration of air quality.
Sections 166(c) and 166(d) provide detail on the contents of those
regulations, but do not necessarily require the same type of increment
system Congress created in section 163 of the Act. The EPA interprets
section 166 to require that the entire system of PSD regulations (the
framework and details, as described in section V.D of this preamble)
for a particular pollutant must, as a whole, satisfy the criteria in
sections 166(c) and 166(d) of the Act.
2. Contingent Safe Harbor Approach
Section 166(c) of the Act describes the kinds of measures to be
contained in the regulations to prevent significant deterioration of
air quality called for in section 166(a) and specifies that these
regulations are to ``fulfill the goals and purposes'' set forth in
sections 160 and 101 of the Act. Section 166(d) of the Act directs EPA
to ``fulfill such goals and purposes'' by providing ``specific measures
at least as effective as the increments established in section 163 * *
*.'' Thus, EPA reads section 166(d) to require that the Agency identify
``safe harbor'' pollutant-specific PSD regulations adopted under
section 166.
The EPA reads section 166(c) to require that the Agency conduct
further review to determine whether, based on the criteria in section
166(c), EPA's pollutant-specific PSD regulations under section 166
should contain measures that are different from the ``safe harbor''
identified under section 166(d). The EPA construes section 166(d) to
require that the measures be ``at least as effective'' as the statutory
increments set forth in section 163.
To apply the ``contingent safe harbor'' approach for
PM2.5, we first identified ``safe harbor'' increments for
each area classification (Class I, II, or III), using: (1) Equivalent
percentages of the NAAQS as the percentages used for developing the
statutory increments; (2) the same pollutant as the NAAQS, i.e.,
PM2.5, and (3) the same time (averaging) periods as were
used for the PM2.5 NAAQS. We concluded that this approach
would ensure that the increments would be ``at least as effective as
the increments established in section 163,'' as required by section
166(d). Second, EPA conducted further review to determine whether the
``safe harbor'' increments, in conjunction with existing elements of
the PSD program or additional measures proposed under section 166 to
augment the increments, sufficiently fulfill the criteria in subsection
(c) of section 166.
In this review, we weighed and balanced the criteria set forth in
subsection (c) (and, as provided in subsection (c), the incorporated
goals and purposes of the Act in section 101 and the PSD program in
section 160) to determine whether additional measures might be needed
to satisfy the criteria in subsection (c). See section V.E.6 of this
preamble for further discussion of our evaluation, comments on the
evaluation, and our response to them.
3. The Statutory Factors Applicable Under Section 166(c)
The EPA interprets section 166(c) of the Act to establish eight
factors to be considered in the development of PSD regulations for the
pollutants covered by this provision. These eight factors included the
three criteria stated in section 166(c) and the five goals and purposes
identified in section 160 of the Act (which, as noted below, also cover
the goals and purposes set forth in section 101). The three stated
criteria in section 166(c) indicate that PSD regulations for specific
pollutants should provide: (1) Specific numerical measures for
evaluating permit applications; (2) a framework for stimulating
improved control technology, and (3) protection of air quality values.
The five goals and purposes in section 160 are incorporated into the
analysis by virtue of the fourth criterion in section 166(c), which
directs that EPA's pollutant-specific PSD regulations ``fulfill the
goals and purposes'' set forth in sections 160 and 101 of the Act. We
construed the term ``fulfill the goals and purposes,'' as used in
section 166(c), to mean that EPA should apply the goals and purposes
listed in section 160 as factors applicable to pollutant-specific PSD
regulations established under section 166. The Agency's view is that
PSD measures that satisfy the specific goals and purposes of section
160 also satisfy the more general purposes and goals identified in
section 101 of the Act. See 72 FR 54122.
One commenter disagreed with our interpretation that the goals and
purposes of section 160 also satisfy all of those in section 101. This
commenter asserted that although there is some overlap between the two
sections, they are not identical. As an example, the commenter noted
that section 101 expressly states that a primary goal of the Act is to
promote pollution prevention--a goal not stated in section 160. The
commenter asserted that, although the proposed increments would limit
some pollution increases, there was no provision in the proposal that
would require or promote pollution prevention.
We disagree with the commenter and continue to believe that
measures that satisfy the specific goals and purposes of section 160
also satisfy the more general purposes and goals identified in section
101 of the Act. As we stated in the 2005 NO2 increment
rulemaking, the overall goals and purposes of the Act listed in
sections 101(b) and 101(c) are general goals regarding protecting and
enhancing the nation's air resources and controlling and preventing
pollution. Because these broad goals are given more specific meaning in
section 160, EPA does not believe it is necessary to consider them in
detail when evaluating whether PSD regulations satisfy the criteria in
section 166(c). 70 FR 59587 FN 3.
Regarding pollution prevention specifically, we believe that this
general goal is encompassed in, and given more specific meaning by,
sections 160(1), 160(2), and 160(4) of the Act. These sections spell
out the specific purposes under the PSD program for the general section
101 goals of controlling and preventing pollution. We believe that any
requirement to limit or reduce emissions serves to promote pollution
prevention, which is often the most cost
[[Page 64874]]
effective means of lowering pollutant emissions.
In addition to citing the purposes set out in section 160, section
166(c) includes the criterion that pollutant-specific PSD regulations
should provide a framework for stimulating improved control technology.
As discussed subsequently in sections V.D.1 and V.D.6 of this preamble,
we believe that this criterion is fulfilled by the system of increments
for PM2.5 and by the requirement for PSD permittees to apply
BACT to minimize PM2.5 emissions. In stimulating improved
control technology generally, these elements of the PSD program also
promote pollution prevention. As noted previously, pollution prevention
is often the most cost effective means of control, particularly for new
sources and new process lines at existing sources. In addition, because
BACT is a case-by-case determination that considers cost and collateral
environmental impacts, pollution prevention, where technically
feasible, often fairs well in BACT analyses because it is typically
free from the negative environmental impacts that result from the use
of add-on air pollution control devices.
4. Balancing the Factors Applicable Under Section 166(c)
While the eight factors in section 166(c) are generally
complementary, there are circumstances where some of the objectives may
be in conflict with each other. In these situations, some degree of
balance or accommodation is inherent in the requirement to establish
regulations that satisfy all of these factors. As first discussed in
our 2005 NO2 increments rulemaking (70 FR 59582 at 59587),
we believe this balancing test derives primarily from the third goal
and purpose set forth in section 160: To insure economic growth
consistent with the preservation of existing clean air resources. A
more detailed discussion of how the balancing of factors should be
interpreted is contained in the 2007 NPRM at 72 FR 54122-54123.
One commenter claimed that EPA ``incorrectly and repeatedly
asserts'' that a goal of section 160 of the Act is to insure economic
growth. The commenter claimed that neither section 160 nor section 101
of the Act uses language to support a goal of promoting or maximizing
opportunities for economic growth. Instead, the commenter asserted that
both sections state only that any growth that does occur must be
consistent with protection of air quality. The commenter concluded that
``EPA's notion that the need to satisfy the other requirements of
Section 166 and other goals and purposes in Sections 101 and 160 can
never preclude additional emissions from economic growth unlawfully
elevates such growth over all other statutory factors.''
The language in section 160(3) provides that one of the purposes of
the PSD program is ``to insure that economic growth will occur in a
manner consistent with the preservation of existing clean air
resources.'' The commenter suggests that this language can only be read
as if the statutory phrase ``economic growth'' actually said ``any
economic growth that does occur'' such that section 160(3) says ``to
insure that any economic growth that does occur will occur in a manner
consistent with the preservation of existing clean air resources.'' We
disagree; the phrasing used by Congress is ``to insure that economic
growth will occur.'' Thus, we believe the plain language of the statute
supports EPA's reading that section 160(3) requires a balancing of the
goals of (1) economic growth and (2) preservation of existing clean air
resources. At a minimum, if the language were to be considered
ambiguous enough to allow the commenter's reading, then the Agency's
interpretation is also a reasonable reading of the statutory language.
5. Authority for States To Adopt Alternatives to Increments
While section 166 of the Act authorizes EPA to promulgate
increments for pollutants listed under section 166(a), we have also
interpreted the section to allow states to employ approaches other than
increments to prevent significant deterioration of air quality, so long
as such an approach otherwise meets the requirements of sections 166(c)
and 166(d). This interpretation was explained in the 2005
NO2 increment rulemaking (70 FR 59611-59612), in which we
amended the PSD regulations at 40 CFR 51.166 by adding new paragraph
(c)(2) to codify this statutory authority. Under the existing provision
in 40 CFR 51.166(c)(2), states may seek EPA approval of SIPs that use
an alternative approach to increments if the State can demonstrate that
the alternative program satisfies the requirements of sections 166(c)
and 166(d). However, the current language at paragraph (c)(2) states
the authority for states to adopt alternative measures only with
respect to increments for NO2. To clarify our interpretation
that the authority to adopt alternative measures covers any pollutant
listed in section 166(a), we are revising 40 CFR 51.166(c)(2) to make
it inclusive to all applicable pollutants rather than just
NO2.
Two commenters supported our proposal to revise paragraph (c)(2) to
include PM2.5, while four State/local agency commenters
expressed opposition. An environmental commenter agreed that the Act
allows for other approaches, but believes that such approaches must be
in addition to the national increments. Specifically, this commenter
stated that ``although EPA can provide for states to adopt approaches
in addition to increments in order to fulfill the statutory purposes,
the agency must make clear that states cannot adopt approaches that are
less protective that the national increments.'' This commenter further
stated that ``to the extent that EPA is suggesting that it can allow
states to adopt PSD programs that do not include the minimum Federal
increments, that position is contrary to the statute.''
As in the 2005 NO2 increment rulemaking, we are
codifying the basic principle that states can seek to use alternative
measures without defining any specific type of alternative program that
would be approved or otherwise creating standards beyond the
requirements of sections 166(c) and 166(d). Instead, we plan to make
determinations on a case-by-case basis when a State submits a specific
alternative approach for EPA to approve as part of a SIP. In making
those determinations, we will address the specific alternative measures
as states propose them to the Agency in light of the requirements of
sections 166(c) and 166(d), including whether the alternative program
is ``at least as effective as the increments established in section
163,'' as required in section 166(d).
The four State/local agency commenters opposing the revision to 40
CFR 51.166(c)(2) expressed the importance of using uniform national
increments for PM2.5. One commenter argued that a nationally
inconsistent approach to PM2.5 in attainment areas could
result in a patchwork of State PSD regulations--and the exact kinds of
economic repercussions that Congress wished to avoid. The same
commenter argued that varying increment-equivalent measures could also
result in an uneven playing field for industry and could exacerbate
difficulties between states experiencing transport problems.
Another opposing commenter was concerned that allowing states to
adopt alternatives to increments would likely lead to a ``mish-mash''
of State approaches which defeats the intention of Congress that there
be uniformity in PSD rules to avoid economic
[[Page 64875]]
dissimilarities from State to State that could allow interstate
competition for industry based upon which State offers the best (least
expensive) environmental compliance regulations. Another commenter
objected to allowing the use of alternatives to increments by stating
that such alternative allowances undermine the desired national
consistency, and EPA has failed to even identify any Act programs which
would benefit from this approach.
While we acknowledge the potential problems identified by the
commenters associated with allowing states to adopt alternative
approaches to the numerical increments that we are establishing, we
also note that section 166(d) expressly gives EPA some latitude in
promulgating regulations that will be at least as effective as the
increments in section 163, by stating that such regulations ``may
contain air quality increments, emission density requirements, or other
measures.'' Thus, EPA is authorized to provide that states may consider
alternatives to the increments established in this rule. That said, the
statutory authority is not a blank check for states to do as they
please, but enables states to consider options that may provide a
meaningful way for them to manage their air resources within the
framework allowed by the statutory PSD requirements.
D. Framework for Pollutant-Specific PSD Regulations for PM2.5
In the 2007 NPRM, we proposed to apply the same basic framework for
pollutant-specific PSD regulations for PM2.5 that we used in
our 2005 NO2 increments regulations. Specifically, we
proposed adopting an increment and area classification system for
PM2.5 and applying the statutory AQRV review process to
PM2.5 as well. We also indicated that while some of the
factors applicable under section 166(c) are fulfilled by using this
type of framework for pollutant-specific PSD regulations under section
166(a) of the Act, this framework of regulations also needs to satisfy
the other applicable factors. Thus, the details of our regulations
(such as the characteristics of the increments themselves) are
important, and we evaluated the effectiveness of the framework in
conjunction with more detailed elements of our regulations. As
discussed in the following subsections, we believe our obligations
under section 166(c) of the Act are satisfied when the PSD regulations
collectively satisfy the factors applicable under 166(c) of the Act.
1. Increment System
An increment-based program satisfies the requirements under 166(c)
to provide ``specific numerical measures against which permit
applications may be evaluated.'' An increment is the maximum allowable
level of ambient pollutant concentration increase that is allowed to
occur above the applicable baseline concentration in a particular area.
As such, an increment defines ``significant deterioration.''
Establishing an increment system for PM2.5 will fulfill two
of the factors applicable under section 166(c): (1) Providing specific
numerical measures to evaluate permit applications, and (2) stimulating
improved control technology.
First, under section 165(a)(3) of the Act, a permit applicant must
demonstrate that emissions from the proposed construction and operation
of a facility ``will not cause, or contribute to, air pollution in
excess of any (A) maximum allowable increase or maximum allowable
concentration for any pollutant * * *.'' Once the baseline date
associated with the application for the first new major stationary
source or major modification in an area is established, the new
emissions from that source consume a portion of the increment in that
area, as do any subsequent emissions increases that occur from any
source in the area. When the maximum pollutant concentration increase
defined by the increment has been reached, additional PSD permits
cannot be issued until sufficient amounts of the increment are ``freed
up'' via emissions reductions that may be required by the reviewing
authority. Thus, an increment is a quantitative value that establishes
a ``maximum allowable increase'' for a particular pollutant. It
functions, therefore, as a specific numerical measure that can be used
to evaluate whether an applicant's proposed project will cause or
contribute to air pollution in excess of allowable levels.
Increments also satisfy the second factor in section 166(c) by
providing ``a framework for stimulating improved control technology.''
Increments establish an incentive to apply improved control
technologies in order to avoid violating the increment and to ``free
up'' available increment to promote continued economic growth. These
control technologies may become the basis of BACT determinations
elsewhere, as the technologies become more commonplace and the costs
tend to decline.
One commenter stated that, although increments may encourage the
use of existing control technologies, EPA has not cited any evidence
that increments actually stimulate the development of improved
technologies. Moreover, the commenter asserted that even if increments
provide the incentive asserted by EPA, any encouragement of improved
control technology is wholly incidental and hardly amounts to a
``framework'' whose purpose is to stimulate such technology.
We continue to believe that the total program, encompassing
increments and BACT, does provide an appropriate framework to stimulate
BACT in such a way that it is not simply ``wholly incidental,'' as the
commenter claims. The fact that economic growth in an area must occur
within a defined amount of allowable air quality deterioration should
logically lead to the application of improved pollution control
technology as the amount of deterioration increases, and should not be
regarded as an incidental consequence. As stated in the 2007 NPRM,
Congress envisioned that the increments they originally established
would serve as an incentive: ``The incremental ceiling should serve as
an incentive to technology, as a potential source may wish to push the
frontiers of technology in a particular case to obtain greater
productive capacity with the limits of the increments.'' S. Rep. 95-127
at 18, 30 (3 LH at 1392, 1404). We, too, believe that as the available
increment in an area becomes smaller, and as states try to preserve
some of the remaining increments for future growth, it will be
necessary to require sources to install more stringent controls in that
area. Such levels of control ultimately must be considered in
subsequent BACT evaluations in other PSD areas throughout the country.
Admittedly, the increasing stringency of control technologies over
time, as observed in EPA's BACT/Lowest Achievable Emission Rate (LAER)
Clearinghouse, supports but cannot in itself conclusively demonstrate
that the PSD program has already stimulated development of improved
control technology; there are undoubtedly a number of factors that
could cause such trends. Nevertheless, even the need to require a more
stringent BACT determination in only a few PSD areas (due to dwindling
increment availability) necessitates consideration of that level of
control for all other PSD sources wherever they may decide to locate.
In any event, while the commenter generally questions the effectiveness
of the increments as an incentive for tightening BACT, they provided no
evidence that more stringent BACT is not related to the
[[Page 64876]]
increment system established as an integral part of the PSD program.
2. Area Classifications
In this final rule, EPA is establishing the same three-tiered area
classification system for PM2.5 that is applicable to the
increments for NO2 and other pollutants under the PSD
program and the Act. Accordingly, areas that are currently Class I for
other pollutants will also be Class I for PM2.5 and all
other areas will be Class II for PM2.5 unless we redesignate
the area based on a request by a State or tribe pursuant to the process
in section 164 of the Act and EPA's regulations at 40 CFR 51.166(g) and
52.21(g).
As explained earlier in section IV.E.1, Class I areas are areas
where very clean air is most desirable. In contrast, Class III areas
are designed as those areas in which a State wishes to permit the
highest relative level of industrial development, and thus allow the
largest incremental increase in pollution. Areas that are not
especially sensitive and where states have not provided for a higher
level of industrial growth are classified as Class II. When Congress
established this three-tiered scheme for SO2 and PM, it
intended that Class II areas be subject to an increment that allows
``moderately large increases over existing pollution.'' H.R. Rep. 95-
294, 4 LH at 2609.
Establishing increments at different levels for each of the three
area classifications helps to fulfill two of the factors applicable
under section 166(c) of the Act. First, establishing the smallest
increments in Class I areas helps fulfill EPA's obligation to establish
regulations that ``preserve, protect, and enhance the air quality'' in
parks and special areas. Class I areas are primarily the kinds of parks
and special areas covered by section 160(2) of the Act. Second, by
providing for two additional area classifications with increment levels
that are higher but still protective, the area classification system
helps satisfy the goal in section 160(3) of the Act that EPA ``insure
that economic growth will occur in a manner consistent with
preservation of clean air resources.'' In those areas where clean air
resources may not require as much protection, more growth is allowed.
By employing an intermediate level (Class II areas) and higher level
(Class III areas), this classification scheme helps ensure that growth
can occur where it is needed (Class III areas) without putting as much
pressure on existing clean air resources in other areas where some
growth is still desired (Class II areas).
By requesting that EPA redesignate an existing Class II area to
Class III, states may accommodate economic growth and air quality in
areas where the Class II increment is too small to allow the siting of
new or modified sources. The procedures specified by the Act for such a
redesignation require a commitment by the State government to create
such an area, extensive public review, local government participation
in the SIP area redesignation process, and a finding that the
redesignation will not result in the applicable increment being
exceeded in a nearby Class I or Class II area. See sections 164(a) and
(b) of the Act. (No State has yet requested a Class III redesignation.)
The EPA believes that the three-tiered classification system has
allowed for economic growth, consistent with the preservation of clean
air resources.
However, an area classification system alone may not completely
satisfy the factors applicable under section 166(c) of the Act. The
increment that is employed for each class of area is also relevant to
an evaluation of whether the area classification system achieves the
goals of the PSD program. We briefly discuss the characteristics of
increments in section V.E.5.
One commenter took issue with our assessment of the two factors
that we believe a classification system helps to fulfill. As discussed
previously in section V.C.4, the commenter asserted that EPA has
unlawfully interpreted section 160(3) of the Act to elevate economic
growth over all other statutory factors. As explained in greater detail
in section V.C.4, we disagree that our interpretation elevates economic
growth over other factors, and believe that the plain language of the
statute supports EPA's reading that section 160(3) requires a balancing
of the goals of (1) economic growth and (2) preservation of existing
clean air resources.
The commenter also stated that EPA has failed to demonstrate that
the classification system and safe harbor increments, in combination
with the other elements of the regulatory framework, will ``preserve,
protect, and enhance the air quality'' in parks and special areas as
required under section 160(2) of the Act. These comments and our
response to them are found in section V.E.6 of this preamble where we
discuss our evaluation of the safe harbor increments.
3. Permitting Procedures
Two of the factors applicable under section 166(c) are fulfilled by
the case-by-case permit review procedures that are built into our
existing PSD regulations. The framework of our existing PSD regulations
employs the preconstruction permitting system and procedures required
under section 165 of the Act. These requirements are generally
reflected in 40 CFR 51.166 and 52.21 of EPA's PSD regulations. These
permitting and review procedures, which apply to construction of new
major sources and to major modifications, fulfill the goals set forth
in sections 160(4) and 160(5) of the Act. These goals require that PSD
programs in one State not interfere with the PSD programs in other
states and that PSD programs assure that any decision to permit
increased air pollution is made after careful evaluation and public
participation in the decision-making process. For the same reasons
discussed in our proposal for the pollutant-specific NO2
increments regulations (70 FR 8896, February 23, 2005), we believe
these factors are also fulfilled for PM2.5 by employing the
permit review procedures.
4. AQRV Review by Federal Land Manager and Reviewing Authority
In this final rule, we apply the existing requirements to evaluate
impacts on AQRVs in Class I areas (see existing 40 CFR 51.166(p) and
52.21(p)) to PM2.5. The existing requirements for an AQRV
review, which Congress applied to SO2 and TSP, provide
Federal land managers (FLMs) with the responsibility to review source
impacts on site-specific AQRVs in Class I areas and to bring any
alleged adverse impacts to the attention of the reviewing authority.
Under an increment approach, we consider this review to be an
additional measure that helps satisfy the factors in sections 166(c)
and 160(2) which require EPA's pollutant-specific PSD regulations to
protect (1) air quality values, and (2) parks and other special areas,
respectively.
Two State/local agency commenters supported our proposal to apply
the requirements to evaluate impacts on AQRV in Class I areas to
PM2.5 review. However, one commenter indicated that FLM
review does not and cannot assure the prevention of all significant
PM2.5-related deterioration because it applies only to the
construction or modification of very large stationary sources (e.g.,
factories and power plants) affecting Class I areas. This commenter
pointed out that Class I areas do not include Bureau of Land Management
wilderness and wilderness study areas (encompassing more than 15
million acres), 341 of the nation's 390 national park units (only 49
national parks are Class I), and many U.S. Forest Service lands
(including a number of wilderness areas). The commenter added that FLM
[[Page 64877]]
review does not help to fulfill section 160(2)'s goal of preserving and
protecting air quality in ``other areas of special national or regional
natural, recreational, scenic, or historic value,'' such as State and
local parks, wildlife refuges, recreation areas, lakes, and historic
areas, none of which are Class I areas. In addition, the commenter
noted that FLM review does not apply to emissions increases from
sources of PM2.5 and precursor pollution other than major
stationary sources, such as motor vehicles and non-major industrial
sources (which are sources that emit substantial amounts of
PM2.5 and precursors). Alabama Power v. Costle, 636 F.2d
323, 362 (D.C. Cir. 1979) (Alabama Power) (expressly recognizing that
``[s]ignificant deterioration may occur due to increased emissions from
unregulated minor sources.'').
The commenter also asserted that FLM review is of limited reach
even where it does apply. Under the current PSD regulations, a State
must consider an FLM's objections and must justify its decision in
writing when it disagrees with those objections, but the State can
still issue a PSD permit over those objections unless emissions are
predicted to cause an exceedance of the applicable increment. The
commenter believes that, given these limitations, EPA cannot plausibly
claim that the existing provision for FLM review ensures the
preservation, protection, and enhancement of air quality for parks and
natural areas throughout the nation as required by section 160(2) of
the Act.
In our rulemakings addressing PSD for NOX, EPA extended
the AQRV review procedures set forth in 40 CFR 51.166(p) and 52.21(p)
to cover NO2. These AQRV review procedures were established
based on section 165(d) of the Act, and they were originally applied
only in the context of the statutory increments for PM and
SO2. However, because they also address many of the factors
applicable under section 166(c) of the Act, EPA also applied them to
NOX through regulation. In this final rule, we are amending
the existing PSD regulations to extend, as proposed, the AQRV review
procedures to include PM2.5 by explicitly including
PM2.5 in the regulatory text that now simply references
``particulate matter.'' See new 40 CFR 51.166(p)(4) and 52.21(p)(5).
Section 165(d) creates a scheme in which the FLM and reviewing
authority must review the impacts of a proposed new or modified
source's emissions on AQRVs. The Act assigns to the FLM an
``affirmative responsibility'' to protect the AQRVs in Class I areas.
This is in notable contrast to the reviewing authority's responsibility
for protecting the increments--including Class I increments. The FLM
may object to or concur in the issuance of a PSD permit based on the
impact, or lack thereof, that new emissions may have on any affected
AQRV that the FLM has identified and for which information is available
to the general public. If the proposed source's emissions are shown not
to cause or contribute to a violation of a Class I increment, the FLM
may still prevent issuance of the permit by demonstrating to the
satisfaction of the reviewing authority that the source or modification
will have an adverse impact on AQRVs. Section 165(d)(2)(C). On the
other hand, if the proposed source is shown to cause or contribute to a
violation of a Class I increment, the reviewing authority (State or
EPA) shall not issue the permit unless the owner or operator
demonstrates to the satisfaction of the FLM that there will be no
adverse impact on AQRVs.\8\ Thus, the showing of compliance with the
increment determines whether the FLM or the permit applicant has the
burden of satisfactorily demonstrating whether or not the proposed
source's emissions would have an adverse impact on AQRVs.\9\ In any
event, the FLM plays an important and material role by raising these
issues for consideration by the reviewing authority, which in the
majority of cases will be the State.
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\8\ Even if such a waiver of the Class I increment is allowed
upon a finding of no adverse impact, the source must comply with
such emissions limitations as may be necessary to ensure that
alternative increments specified in the rules for SO2 or
PM are not exceeded. The alternative increments are generally at the
level of the Class II increments, with the lone exception being a
more restrictive 3-hour increment for SO2. Section
165(d)(2)(C)(iv). The EPA made this provision applicable to the PSD
provisions for NOX at the level of the NO2
Class II increment (53 FR 3704; 53 FR 40656) and substituted the
PM10 Class II increments for the statutory alternative PM
increments, which were based on TSP (58 FR 31622). This final rule
expands this provision to include the PM2.5 Class II
increments as well. See 40 CFR 51.166(p)(4) and 52.21(p)(5).
\9\ In response to concerns that Class I increment would hinder
growth in areas surrounding the Class I area, Congress established
Class I increments as a means of determining where the burden of
proof should lie for a demonstration of adverse effects on AQRVs.
See Senate Debate, June 8, 1977 (3 LH at 725).
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Extending the AQRV review procedures of the PSD regulations to
PM2.5 helps to provide protection with respect to potential
adverse effects from PM2.5 for parks and special areas
(which are generally the Class I areas subject to this review) not
afforded by the increment system alone. As discussed later, we believe
the factors applicable under section 166(c) of the Act can be fulfilled
when the review of AQRVs is applied in conjunction with increments and
other aspects of our PSD regulations. In those cases where the
increment is not violated and the reviewing authority agrees that a
proposed project will adversely affect AQRVs, the parks and other
special areas will be protected by denying issuance of the permit or by
requiring the applicant to modify the project to alleviate the adverse
impact.
We read the legislative history to show that Congress intended the
AQRV review provisions of section 165(d) to provide a special layer of
protection, beyond that provided by increments. The Senate committee
report stated the following:
A second test of protection is provided in specified Federal
land areas (Class I areas), such as national parks and wilderness
areas; these areas are also subjected to a review process based on
the effect of pollution on the area's air quality related values.''
S. Rep. 95-127, at 17, 4 LH at 1401.
As we stated in the NO2 increment rule, we believe the
term ``air quality values'' should be given the same meaning as ``air
quality related values.'' Legislative history indicates that the term
``air quality value'' was used interchangeably with the term ``air
quality related value'' (AQRV) regarding Class I lands.\10\
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\10\ See S. Rep. 95-127, at 12, reprinted at 3 LH at 1386, 1410
(describing the goal of protecting ``air quality values'' in
``Federal lands--such as national parks and wilderness areas and
international parks,'' and in the next paragraph and subsequent text
using the term ``air quality related values'' to describe the same
goal); id. at 35, 36 (``The bill charges the Federal land manager
and the supervisor with a positive role to protect air quality
values associated with the land areas under the jurisdiction of the
[FLM]'' and then describing the statutory term as ``air quality
related values''). H.R. Report 95-564 at 532 (describing duty of
Administrator to consider ``air quality values'' of the tribal and
State lands in resolving an appeal of a tribal or State
redesignation, which is described in the final bill as ``air quality
related values'').
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The commenter is correct that the FLM (or AQRV) review applies only
to Class I areas, and not to other ``special'' areas such as the
numerous State and local parks and some other areas that could be seen
as being covered by the protective purposes of section 160(2) of the
Act. This level of coverage by FLM review to protect AQRVs was
established by Congress when it enacted the PSD program, including the
purposes set out in section 160(2). Thus, we conclude that Congress
believed that the special areas not designated as Class I areas were
properly addressed by the other elements of the PSD program. As
discussed further in the next section, one such element is the
requirement for sources to conduct an ``additional impacts analysis,''
which includes an
[[Page 64878]]
analysis of the impacts on visibility, soils, and vegetation of the
proposed source and associated growth, regardless of the classification
of the area impacted by the source. Note also that states have the
option under the Act of designating additional areas as Class I areas
and providing for AQRV review for these State Class I areas if they
believe that there are areas within their borders that merit such
protection.
The commenter is not correct in saying that the review to protect
AQRVs does not apply to emissions increases from sources other than
major stationary sources. While it is generally true that a major
stationary source may trigger the analysis as part of the required PSD
review for new major stationary sources and major modifications where
such source's emissions increase may affect a Class I area, the review
itself includes the impacts on an AQRV of other emissions in the area,
including emissions from non-major sources. In addition, states may
adopt requirements in their State implementation plans to require
certain minor sources seeking a permit to undergo an AQRV analysis if
they choose to do so.
We agree with the commenter that the AQRV review has certain
limitations in that a State can, under some circumstances, issue a PSD
permit over the objection of the FLM. Here again, Congress enabled this
outcome when it provided that a permit would not be issued when the FLM
demonstrates ``to the satisfaction of the State'' that the source will
have an adverse impact on AQRVs in a Class I area. Section
165(d)(2)(C)(ii). We read this provision to reflect Congress's judgment
on the appropriate balance between State and FLM discretion in the
reach of AQRV review. That said, when a reviewing authority declines to
follow a determination of adverse impact by the FLM, the reviewing
authority is expected to provide a rational basis for doing so, and a
reviewing authority's rejection of an FLM's finding may not be
arbitrary and capricious. As stated by EPA's Environmental Appeals
Board in In the Matter of: Hadson Power 14--Buena Vista, 4 E.A.D. 258,
1992 WL 345661 (October 5, 1992)(in Section II.A):
States do not have unfettered discretion to reject an FLM's
adverse impact determination. If a State determines that an FLM has
not satisfactorily demonstrated an adverse impact on AQRVs from the
proposed facility, the State must provide a ``rational basis'' for
such a conclusion, ``given the FLMs' affirmative responsibility and
expertise regarding the Class I areas within their jurisdiction.''
50 FR 28549, July 12, 1985. Arbitrary and capricious rejections of
adverse impact determinations are not sustainable. (citations
omitted).
In sum, the commenter correctly enumerated some of the limitations
of the AQRV review under the Act. However, such review is only one
element of the full PSD program, which must be evaluated against the
statutory requirements in their entirety. We continue to believe, as
previously stated, that under an increment approach, FLM review for
AQRV impacts is an additional measure that helps satisfy the factors in
sections 166(c) and 160(2) of the Act (which require EPA's pollutant-
specific PSD regulations to protect (1) air quality values, and (2)
parks and other special areas, respectively) in balance with the other
statutory factors. We add that the AQRV review requirements of the
existing regulations mirror these requirements in the Act, which
reflect Congress' judgment of how AQRV review should properly be used
to promote the purposes of the program as set out in section 160 of the
Act.
5. Additional Impacts Analysis
The ``additional impacts analysis'' requirements set forth in our
part 51 and 52 PSD regulations also help fulfill the criteria and goals
and purposes in sections 166(c) and 160. The additional impacts
analysis involves a case-by-case review of potential harm to
visibility, soils, and vegetation in Class II and III areas that could
occur from the construction or modification of a PSD source.
Sections 51.166(o)(1) and 52.21(o)(1) of the PSD regulations
require that a permit provide the following analysis:
An analysis of the impairment to visibility, soils and vegetation
that would occur as a result of the source or modification and
general commercial, residential, industrial and other growth
associated with the source or modification. The owner or operator
need not provide an analysis of the impact on vegetation having no
significant commercial or recreational value.
This requirement was based on section 165(e)(3)(B) of the Act,
which provides that EPA establish regulations that require ``an
analysis of the ambient air quality, climate and meteorology, terrain,
soils and vegetation, and visibility at the site of the proposed major
emitting facility and in the area potentially affected by emissions
from such facility * * *.''
As mentioned in the previous section, one commenter argued that the
provisions for protection of Class I areas are of no help in fulfilling
the goal set forth in section 160(2) of the Act to preserve and protect
air quality in the countless ``other areas of special national or
regional natural, recreational, scenic, or historic value'' such as
State and local parks, wildlife refuges, recreation areas, lakes and
historic areas, none of which were originally defined by Congress as
Class I areas.
We acknowledge that the special provisions for protecting Class I
areas are not applicable for protecting areas that are not designated
as ``Class I.'' However, we believe that the ``additional impacts
analysis'' provisions are especially helpful for satisfying the
requirements of section 166(c) in Class II and Class III areas,
including the types of areas described by the commenter, that are not
Class I areas but are worthy of special protection beyond what might be
provided by the NAAQS and increments. 40 CFR 51.166(o) and 52.21(o).
These areas are not subject to the special AQRV review that applies
only in Class I areas. While the additional impacts analysis is not as
intensive a review as the AQRV analysis required in Class I areas, the
requirement to consider impairments to visibility, soils, and
vegetation through the additional impacts analysis contributes to
satisfying the factors applicable under section 166(c) of the Act in
all areas, including Class II and Class III areas.
6. Installation of BACT
The requirement that new sources and modified sources subject to
PSD apply BACT is an additional measure that helps to satisfy the
factors in sections 166(c), 160(1), and 160(2) of the Act. This
requirement, based on section 165(a)(4) of the Act, is already included
in EPA's PSD regulations for all pollutants generally and thus, in the
2007 NPRM we considered it to be a part of the regulatory framework for
the Agency's pollutant-specific regulations for PM2.5. 40
CFR 51.166(j) and 52.21(j). Our existing regulations define ``best
available control technology'' as ``an emission limitation * * * based
on the maximum degree of reduction for each pollutant subject to
regulation under the Act * * * which the Administrator, on a case-by-
case basis, taking into account energy, environmental, and economic
impacts and other costs, determines is achievable for such source
through application of production processes or available methods,
systems, and techniques * * *.'' 40 CFR 51.166(b)(12) and 52.21(b)(12).
This pollutant control technology requirement, in practice, has
required significant reductions in the pollutant emissions increases
from new and modified sources while also stimulating the on-going
improvement of control
[[Page 64879]]
technology. The control of PM2.5 emissions through the
application of BACT helps to protect air quality values, public health
and welfare, and parks and other special areas.
E. Final PM2.5 Increments
Based on our evaluation of the effects of PM2.5 and a
balancing of the criteria in section 166(c) of the Act (and the
incorporated goals and purposes of the Act contained in section 101 and
the statutory PSD program in section 160 of the Act), EPA has concluded
that the ``safe harbor'' increments for PM2.5 (which satisfy
section 166(d) of the Act) are sufficient to fulfill the criteria in
section 166(c) when combined with the other measures described earlier
that we apply to PM2.5. Since several of the eight factors
applicable under section 166(c) are satisfied by adopting the framework
and other measures described earlier, our development of these
increments for PM2.5 was guided by the four remaining
factors that may not be fully satisfied by the framework and other
measures: (1) Protecting AQRVs; (2) protecting the public health and
welfare from reasonably-anticipated adverse effects; (3) protecting the
air quality in parks and special areas, and (4) insuring economic
growth.\11\ In accordance with the ``contingent safe harbor'' approach,
to determine the specific characteristics of the proposed increments,
we first established safe harbor increments representing the level of
effectiveness necessary to satisfy the ``at least as effective as''
requirement in section 166(d) of the Act and then conducted further
analysis to determine if additional measures are necessary to fulfill
the requirements of section 166(c).
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\11\ We have paraphrased these factors here and in other
sections to facilitate the explanation of our reasoning. However, we
recognize, as we did in our regulation for NOX, that the
statutory language is broader than the shorthand we use here for
convenience.
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1. Identification of Safe Harbor Increments
Using the percentage-of-NAAQS approach under proposed Option 1, as
explained in section V.C.2 of this preamble, we derived the following
safe harbor increments for PM2.5:
----------------------------------------------------------------------------------------------------------------
NAAQS Increments ([micro]g/m\3\)
Averaging period ([micro]g/ --------------------------------------
m\3\) Class I Class II Class III
----------------------------------------------------------------------------------------------------------------
Annual...................................................... 15 1 4 8
24-hour..................................................... 35 2 9 18
----------------------------------------------------------------------------------------------------------------
The table shows PM2.5 NAAQS levels (primary and
secondary NAAQS) at 15 [micro]g/m\3\ for the annual averaging time and
35 [micro]g/m\3\ for the 24-hour averaging time. See 40 CFR 50.7. From
these NAAQS levels, we calculated the safe harbor increments based on
the same percentages that were used by Congress to establish the
original PM increments (measured as TSP) in section 163 of the Act,
i.e., 6.6 percent of the NAAQS for Class I areas, 25 percent of the
NAAQS for Class II areas, and 50 percent of the NAAQS for Class III
areas. We have concluded that increments with these characteristics are
sufficient to satisfy the requirement in section 166(d) that we adopt
increments (or other PSD regulations) that are ``at least as effective
as'' the increments established in section 163 of the Act. See EDF v.
EPA, 898 F.2d at 188, 190.
Nine commenters supported proposed Option 1, either explicitly or
implicitly supporting our method of calculating the safe harbor
increments used to develop increments for PM2.5. One of
these commenters, while agreeing with the safe harbor increment
approach under Option 1, disagreed with our analysis of the adequacy of
the safe harbor increments, as discussed in other sections of this
preamble. One commenter who opposed Option 1 (based on the belief that
section 166(a) of the Act is not the appropriate basis for
PM2.5 increments) nevertheless supported the percentage-of-
NAAQS approach for developing PM2.5 increments under the
statutory authority at section 166(f).
A commenter who opposed our proposal to calculate increments using
percentages of the NAAQS argued that this approach for setting the
PM2.5 increments is not scientifically supported. This
commenter indicated that basing the PM2.5 increments on the
same percentage of the NAAQS that were used to set PM10
increments based on the TSP NAAQS ignores the relationship between
PM10 and PM2.5 emissions, which may be much
different than the relationship between TSP and PM10
emissions. The commenter argued that, because the ratio of
PM2.5 to PM10 emissions is 0.8, it appears that
using the percentages proposed by EPA would indirectly restrict
PM10/TSP emissions and air quality impacts to proportionally
lower levels than the PM10 increments in order to avoid
exceeding the PM2.5 increments. The commenter conceded that
using the 0.8 factor to set PM2.5 increments may seem too
high, but asserted that using the safe harbor approach would set
increments for PM2.5 that are too low.
We conclude that the commenter is mistaken in saying that the
PM2.5 increments use the same percentage of the NAAQS that
were used to set the PM10 NAAQS. We adopted the
PM10 increments using the ``equivalent substitution''
approach set forth under section 166(f) of the Act. Under that
approach, rather than calculating the PM10 increments as
specific percentages of the PM10 NAAQS (using the same
percentages that Congress used for setting the statutory increments for
PM and SO2), EPA determined the levels of the
PM10 increments that could represent an equivalent amount of
increment consumed, as if the TSP increments were still in effect. See
58 FR 31622, June 3, 1993, at 31626-31627. Nevertheless, the commenter
is correct that, in cases where the ratio of PM2.5 to
PM10 emissions is 0.8 for an individual source, the source
may have to reduce its PM10 emissions more than would
otherwise be necessary to meet the PM10 increments in order
to control its PM2.5 emissions sufficiently to meet the safe
harbor PM2.5 increments.\12\ This is because the safe harbor
PM2.5 increments are less than 80 percent of the
PM10 increments. For example, the Class II 24-hour
PM2.5 safe harbor increment (9 [micro]g/m\3\) is only 30
percent of the corresponding PM10 increment (30 [micro]g/
m\3\).
---------------------------------------------------------------------------
\12\ Note that the PM10 increment may still be more
limiting in areas where much of that increment has already been
consumed.
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The underlying reason that the safe harbor PM2.5
increments are so much less than the PM10 increments is that
the PM2.5 NAAQS are much less than the PM10
NAAQS.\13\ This is the result of the evolution in our knowledge about
the health and welfare effects of PM, in particular the effects of the
fine PM
[[Page 64880]]
represented by PM2.5. We believe that it is fitting for
PM2.5 increments to reflect our greater knowledge about
PM2.5 effects (as embodied in the NAAQS), rather than to
simply maintain the control level required by the PM10
increments as suggested by the commenter. If this results in
PM2.5 increments that are more limiting than PM10
increments, we believe that this outcome is appropriate in light of our
statutory requirement to prevent significant deterioration of air
quality as it relates to PM2.5.
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\13\ The 24-hour PM2.5 NAAQS (35 [micro]g/m\3\) is
about 23 percent of the 24-hour PM10 NAAQS (150 [micro]g/
m\3\).
---------------------------------------------------------------------------
2. Data Used by EPA for the Evaluation of the Safe Harbor Increments
for PM2.5
We evaluated whether measures other than the safe harbor increments
are necessary by analyzing primarily the scientific and technical
information on the health and welfare effects of PM2.5
contained in the June 2005 OAQPS Staff Paper which accompanied the last
full review of the PM NAAQS completed in 2006.\14\
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\14\ The review completed in 2006 updated the previous review,
which began in 1994 and resulted in revised standards for PM in
1997.
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Section 166(a) of the Act provides that EPA establish pollutant-
specific PSD regulations, such as increments, after the establishment
of a NAAQS for the applicable pollutants. The Act provides that EPA
will promulgate new PSD regulations under section 166, including new
increments if appropriate, within 2 years from the promulgation of any
NAAQS after 1977. Within that time frame, the health and welfare
information used for the setting of the NAAQS would also be ``current''
for purposes of establishing pollutant-specific PSD regulations. We
believe this timing reflects congressional intent that EPA consider the
same body of information concerning a pollutant's health and welfare
effects when it promulgates the NAAQS and subsequent PSD increments (or
other measures) defining significant air quality deterioration for the
same pollutant. However, when we used that same information as the
basis for our proposed pollutant-specific PSD regulations, we evaluated
that information under the legal criteria in section 166 of the Act
rather than the criteria in section 109 applicable to the promulgation
of NAAQS. See EDF v. EPA, 898 F.2d at 190.
At the time of our proposal of PM2.5 increments, we had
just completed a review of the PM2.5 NAAQS. Thus, the
information used in the NAAQS review was current and timely for
purposes of establishing pollutant-specific PSD regulations for
PM2.5. On October 17, 2006, based primarily on considerable
new data on the air quality and human health effects for
PM2.5 directly, EPA revised the primary and secondary NAAQS
to provide increased protection of public health and welfare by
retaining the level of the annual standard and tightening the level of
the 24-hour standard from 65 to 35 [mu]g/m\3\ while retaining the 24-
hour PM10 NAAQS and revoking the annual PM10
NAAQS. The information contained in both the 2004 Criteria Document and
2005 Staff Paper that was used for the latest review of the PM NAAQS
was also considered for the purpose of evaluating the PM2.5
increments that we have established in this final rule.
The 2004 Criteria Document and 2005 Staff Paper are the products of
a rigorous process that is followed to validate and interpret the
available scientific and technical information, and provided the basis
for recommending the PM2.5 NAAQS. In accordance with the
Act, the NAAQS process begins with the development of ``air quality
criteria'' under section 108 for air pollutants that ``may reasonably
be anticipated to endanger public health or welfare'' and that come
from ``numerous or diverse'' sources. Section 108(a)(1). For each NAAQS
review, the Administrator must appoint ``an independent scientific
review committee composed of seven members of the National Academy of
Sciences, one physician, and one person representing State air
pollution control agencies,'' known as the Clean Air Scientific
Advisory Committee (CASAC). Section 109(d)(2)(A). The CASAC is charged
with recommending revisions to the criteria document and NAAQS, and
advising the Administrator on several issues, including areas in which
additional knowledge is required to appraise the adequacy and basis of
existing, new, or revised NAAQS. Section 109(d)(2)(B),(C).
``Air quality criteria'' must reflect the latest scientific
knowledge on ``all identifiable effects on public health or welfare''
that may result from a pollutant presence in the ambient air. Section
108(a)(2). The scientific assessments constituting air quality criteria
generally take the form of a ``criteria document,'' a rigorous review
of all pertinent scientific studies and related information. The EPA
also develops a ``staff paper'' to ``bridge the gap'' between the
scientific review and the judgments the Administrator must make to set
standards. See Natural Resources Defense Council v. EPA (``NRDC ''),
902 F.2d 962, 967 (D.C. Cir. 1990). Both documents undergo extensive
scientific peer review as well as public notice and comment. See, e.g.,
62 FR 386542.
3. Scope of Effects Considered
The effects of ambient PM2.5 concentrations may include
effects from secondarily-formed PM2.5. Thus, when we
analyzed the data in this rulemaking, we evaluated the health and
welfare effects of both direct PM2.5 and secondarily-formed
PM2.5 that may result from the transformation of other
pollutants such as SO2 and NOX. This was
consistent with the approach we described for addressing these effects
in the review of our pollutant-specific NO2 increments
regulations. 70 FR 59590.
4. Evaluation of the Health and Welfare Effects of PM2.5
Airborne PM is not a specific chemical entity, but rather is a
mixture of liquid and solid particles from different sources and of
different sizes, compositions, and properties. Particle size
distributions show that atmospheric particles exist in two classes:
Fine particles and coarse particles. The indicator for fine particles
is PM2.5, which represents that population of particles that
is mostly less than 2.5 micrometers in size. The indicator for thoracic
coarse particles is ``PM10-2.5,'' which represents particles
sized between 2.5 and 10 micrometers. In the last two reviews of the PM
NAAQS, EPA concluded that these two indicators, because of their
different sources, composition, and formation processes, should be
treated as separate subclasses of PM pollution for purposes of setting
ambient air quality standards.
Fine PM is derived directly from combustion material that has
volatilized and then condensed to form primary PM or from precursor
gases, such as SO2 and NOX, reacting in the
atmosphere to form secondary PM. Major components of fine particles are
sulfates, strong acid, ammonium nitrate, organic compounds, trace
elements (including metals), elemental carbon, and water. Primary and
secondary fine particles have long lifetimes in the atmosphere (days to
weeks) and travel long distances (hundreds to thousands of kilometers).
They tend to be uniformly distributed over urban areas and larger
regions, especially in the eastern United States. As a result, they are
not easily traced back to their individual sources.
a. Health Effects
The EPA reported important progress since the last PM NAAQS review
in advancing our understanding of potential mechanisms by which ambient
PM2.5, alone and in combination with other pollutants, is
causally linked to a
[[Page 64881]]
number of key health effects. The more extensive and stronger body of
evidence used by EPA to study the health effects of PM2.5 in
our latest review identified a broader range of effects than those
previously documented, involving premature mortality and indices of
morbidity (including respiratory hospital admissions and emergency room
visits, school absences, work loss days, restricted activity days,
effects on lung function and symptoms, morphological changes, and
altered host defense mechanisms) associated with both long-term and
short-term exposure to PM2.5. A more detailed discussion of
the health effects associated with PM2.5 is contained in the
2007 NPRM. 72 FR 54127-54128. In addition, an overview of the
scientific and technical evidence considered in the 2004 Criteria
Document and 2005 Staff Paper can be found in our proposed rule for
revising the NAAQS for PM (71 FR 2619, January 17, 2006).
b. Welfare Effects
Ambient PM alone, and in combination with other pollutants, can
have a variety of effects on public welfare. While visibility
impairment is the most noticeable effect of fine particles present in
the atmosphere, both fine and coarse particles can have other
significant welfare-related effects, including effects on vegetation
and ecosystems, materials (e.g., soiling and corrosion), and climate
change processes.
In reaching our decision in 2006 to revise the suite of PM
secondary standards, EPA factored in several key conclusions from the
scientific and technical information contained in the 2004 Criteria
Document and 2005 Staff Paper. These conclusions included the
following: (1) PM-related visibility impairment is principally related
to fine particle levels, and most directly related to instantaneous
levels of visual air quality associated with short-term averaging
periods; (2) PM2.5 concentrations can be used as a general
surrogate for visibility impairment in urban areas; (3) any secondary
NAAQS for visibility protection should be considered in conjunction
with the regional haze program as a means of achieving appropriate
levels of protection against PM-related visibility impairment in urban,
non-urban, and Class I areas nationwide; (4) the available evidence is
not sufficient to support distinct secondary standards for fine or
coarse particles for any non-visibility related welfare effects; and
(5) the secondary standards should be considered in conjunction with
protection afforded by other programs intended to address various
aspects of air pollution effects on ecosystems and vegetation, such as
the acid deposition program and other regional approaches to reducing
pollutants linked to nitrate or acidic deposition.
In this rulemaking, EPA has reviewed the scientific and technical
information concerning welfare related effects considered in the 2004
Criteria Document and 2005 Staff Paper to determine whether there is
any basis for modifying the safe harbor increments developed for
PM2.5 to satisfy the criteria under sections 166(c) and 160
of the Act. Our review included information on visibility impairment,
and effects on vegetation and other ecosystem components, materials and
soiling, and climate changes. A detailed discussion of the various
welfare effects we considered for evaluating the safe harbor increments
for PM2.5 is contained in the 2007 NPRM. 72 FR 54128-54133.
5. Fundamental Elements of Increments
As we have previously noted, under the model established in the Act
and prior EPA regulations, the function of an increment is not like
that of the NAAQS in that an increment is not intended to set a uniform
ambient pollutant concentration ``ceiling'' across the United States.
See 70 FR 59600. Instead, while both increments and NAAQS generally
serve to limit ambient air pollution levels, increments are designed to
allow a uniform amount of pollutant concentration increase for each
area in the United States having a particular classification, i.e.,
Class I, II, or III. The amount of the allowable increase is measured
against a baseline air quality level that is typically different for
each particular area.\15\ Because the baseline air quality level varies
from one location to another, and is not established for a particular
area until a source proposing to construct in that area submits a
complete PSD permit application, it is not possible to determine what
the maximum ambient pollutant concentration attainable will be for a
given area (to be used to determine the protection afforded by an
increment against potential adverse environmental effects) until the
specific baseline air quality level is known.
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\15\ It should be noted, however, that an increment does not
allow air pollution levels in an area to increase beyond the ambient
concentration of a pollutant that would exceed the level allowed by
the NAAQS.
---------------------------------------------------------------------------
For the reasons described in our NO2 increments rule,
our objective is to establish uniform increments, consistent with the
increments for SO2 and PM originally established by
Congress, that allow the same level of deterioration for each area of
the country having the same classification. 70 FR 59601. It is
important to understand that increments are not intended to reduce
ambient concentrations of an air pollutant below existing baseline
levels in each area, but rather to define a level of allowable increase
in pollutant concentrations above baseline levels, and to identify the
level at which ``significant'' deterioration occurs for each area, in
accordance with its specific classification. 70 FR 59600.
6. Evaluation of the Safe Harbor Increments
As indicated earlier (in section V.E.2 of this preamble), mindful
of the considerations made about the fundamental characteristics of the
increments, we reviewed the scientific and technical evidence available
for the 2005 review of the NAAQS for PM in order to determine whether,
and to what extent, the ``safe harbor'' increments might need to be
modified in order to protect air quality values, health and welfare,
and parks while insuring economic growth consistent with the
preservation of clean air resources in accordance with sections 166(c)
and 160 of the Act. As we did in our evaluation of the safe harbor
NO2 increments (70 FR 59603-59606), we relied on an approach
that evaluates how protective the safe harbor PM2.5
increments are by comparing the marginal pollutant concentration
increases allowed by the safe harbor increment levels against the
pollutant concentrations at which various environmental responses
occur.
We analyzed the available evidence from both a quantitative and
qualitative perspective to reach a decision about whether we should
modify the contingent safe harbor PM2.5 increments and
whether we have sufficient information to select a specific alternative
level, averaging time, or pollutant indicator for the increments. As a
result of our analysis, we proposed to conclude that it was not
necessary to modify the safe harbor increments to protect human health,
address non-visibility welfare effects, or further protect visibility.
This analysis is described in detail in the 2007 NPRM.
After considering the comments on our evaluation of the safe harbor
increments and the conclusions we reached in the 2007 NPRM (summarized
in the following paragraphs), we continue to believe that the safe
harbor increments for PM2.5 (which satisfy section 166(d) of
the Act) are sufficient to fulfill the criteria in section 166(c) of
the Act (and the incorporated goals and purposes of the Act in section
101 and the PSD program in section 160) when
[[Page 64882]]
combined with the other measures described earlier that we apply to
PM2.5. Consequently, this final rule establishes the
PM2.5 increments at the level of the proposed safe harbor
increments.
An environmental group submitted extensive comments arguing that
the PM2.5 safe harbor increments are not sufficient to meet
the Act's requirements for PSD and that our analysis was inadequate,
and two other commenters submitted more narrowly targeted comments in
this area. A summary of the major comments, along with our responses,
follows. A more detailed treatment of the comments can be found in the
Response to Comments document for this rulemaking, which is available
in the rulemaking docket.\16\
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\16\ Docket No. EPA-HQ-OAR-2006-0605 can be accessed on line at
http://www.regulations.gov.
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The environmental group commenter stated that EPA has not complied
with section 166(c) of the Act because the Agency has not made a
finding or demonstrated that the PM2.5 PSD rules will (as
required by section 160(2) of the Act) preserve, protect, and enhance
the air quality in parks and special areas. The commenter asserted that
EPA offered only vague assertions that the proposed increments would
``satisfy'' the statutory factors and that they, along with other
programs, would ``help'' to fulfill the statutory purposes. The
commenter went on to argue that EPA sought to excuse its failure to
show fulfillment of the statutory purposes by asserting that it cannot
develop a uniform, quantitative, dose-response relationship between
fine particle levels and certain ecosystem impacts (citing 72 FR
54134), but that, even if true, such a claim does not excuse the agency
from satisfying its statutory duty under section 166(c).
We conclude that the 2007 NPRM demonstrated that the safe harbor
increments, in combination with the other aspects of the regulatory
framework, fulfill the statutory requirements despite the scientific
uncertainties. We reiterate that finding today. The fact that we did
not, in the 2007 NPRM, explicitly state this as a finding does not
diminish the demonstration made there and reiterated in this preamble.
The environmental group commenter believes that the relationship
between PM2.5 and adverse effects can be quantified to a
greater extent than stated by EPA. Regarding acid rain and other
adverse ecological impacts, the commenter asserted that critical loads
can be established as a way of quantifying and limiting the
PM2.5 contribution to degradation, and noted that critical
loads are now used by authorities in Europe, have been endorsed by
leading North American scientists, and have been used by Federal land
management agencies. To comply with section 166(c), the commenter
believes that EPA must establish a mechanism to supplement the
nationally uniform increments with additional measures, including a
requirement to establish area-specific critical loads or equally
protective limits, where necessary to protect and enhance air quality
in specific parks and natural areas.
With regard to the critical load concept, we agree conceptually
with the commenter that critical loads could be used to supplement the
existing increments, especially as a means of protecting the known
sensitive ecosystems within Class I areas. While we disagree that the
critical loads concept can be used as an effective replacement to
increments for limiting air quality degradation, we believe that the
concept offers considerable promise in helping to protect sensitive
receptors in specific Class I areas. However, we do not believe that it
would be appropriate at this time to establish a requirement for area-
specific critical loads under the PSD program. In our 2005 PSD rule for
NO2 increments, we indicated that states could propose using
information on critical loads as part of their approach for managing
air quality in their individual SIP-approved PSD programs, but
sufficient information was not yet available for EPA to incorporate the
use of critical loads into the national PSD program. See 70 FR 59613.
The concept of critical loads is useful for estimating how much
pollution a particular ecosystem can experience on a prolonged basis
without showing adverse effects. In addition to addressing the
opportunity for using critical loads under its NO2 increment
rule, EPA has addressed the concept of critical loads in the last
review of the PM NAAQS and currently in the secondary NO2/
SO2 NAAQS review.\17\ To date in the United States, critical
loads have had their primary application in the area of atmospheric
deposition of sulfur (S) and nitrogen (N). In the last review of the PM
NAAQS, EPA found that ambient PM was contributing to the total load of
pollutants entering the U.S. ecosystem annually. However, the review
also concluded that there were ``insufficient data for the vast
majority of U.S. ecosystems that differentiate the PM contribution to
total N [nitrate] or S [sulfate] deposition to allow for practical
application of this approach as a basis for developing national
standards to protect sensitive U.S. ecosystems from adverse effects
related to PM deposition.'' The 2005 Staff Paper for the PM NAAQS, in
reaching this conclusion, addressed various important factors,
including (1) the lack of a long-term, historic database of annual
speciated PM deposition rates to establish relationships between PM
deposition and ecosystem responses; (2) uncertainty in predicting the
amount of PM deposited to sensitive receptors from measured
concentrations of PM in the ambient air; and (3) the unique nature of
each ecosystem and the current inability to extrapolate with confidence
any effect from one ecosystem to another. The 2005 Staff Paper
recommended that EPA give serious attention to the critical load
concept and recommended the collection of data from a ``greater variety
of ecosystems over longer time scales to determine how ecosystems
respond to different loading rates over time.'' 2005 Staff Paper at
page 7-19.
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\17\ In the 2005 OAQPS Staff Paper reviewing the NAAQS for PM,
EPA cited the following accepted definition of ``critical load'':
``quantitative estimate of an exposure to one or more pollutants
below which significant harmful effects on specified sensitive
elements of the environment do not occur according to present
knowledge.'' See page 6-45.
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The review of the secondary NAAQS for NOX and sulfur
oxides (SOX), which is currently underway, is evaluating
ecological effects due to the atmospheric deposition of NOX
and SOX. The two main targeted effects are acidification and
nutrient enrichment in both aquatic and terrestrial ecosystems. This
review is attempting to use critical loads to evaluate the impact of
current depositional loads and alternative loads in several case study
areas. However, as mentioned earlier, the estimation of ecosystem
critical loads expressed in terms of PM requires long-term ecosystem-
level data on speciated PM deposition rates for which an adequate
database is currently lacking for most sites in the United States.
The environmental group commenter also asserted that the safe
harbor increments would allow PM2.5 air quality to
deteriorate to the level of the NAAQS in many locations. According to
the commenter's analysis, at 55 percent of the locations with
PM2.5 monitors that were not already exceeding the
PM2.5 NAAQS, 24-hour PM2.5 concentrations would
be allowed to increase up to the level of the NAAQS. In addition, the
analysis showed that for 84 percent of locations not already exceeding
the NAAQS, the 24-hour PM2.5 concentrations would be allowed
to increase to a level of 30 [mu]g/
[[Page 64883]]
m\3\ or more. The commenter believes that allowing such levels would
not be protective of public health, given that we stated in the 2007
NPRM that we had previously found that PM2.5 concentrations
less than a range of 30-35 [mu]g/m\3\ (24-hour average) were protective
of public health (citing 72 FR 54128).
The environmental group commenter's analysis showed similar results
for the proposed annual PM2.5 increments. The commenter
asserted that PM2.5 concentrations would be allowed to
increase up to the level of the annual NAAQS in 55 percent of the
locations that are currently in attainment, and that 87 percent of
these sites would be allowed PM2.5 concentrations of 12
[mu]g/m\3\ or higher. Again, the commenter believes that allowing
annual concentrations at or above 12 [mu]g/m\3\ would not be protective
of public health, based on our statement in the 2007 NPRM that we had
previously found that PM2.5 concentrations less than a range
of 12-15 [mu]g/m\3\ (annual average) were protective of public health
(citing 72 FR 54128).
We do not believe that increments must be set at levels that ensure
that the full amount of increment will be available in all locations.
The statutory provisions in the PSD program have always been clear that
a source must demonstrate that it will comply with both the NAAQS and
increments for any pollutant. Consistent with congressional intent, the
PSD program does not allow a source to violate the NAAQS just because
its emissions will not cause the increments to be exceeded. If the
increments were to be developed in such a way that all areas, taking
into account current ambient air quality status, would be able to
utilize the full amount of increment, then the increment levels would
have to be unnecessarily stringent in areas that are substantially
cleaner than levels allowed by the NAAQS.
Congress recognized that all areas of the country might not be able
to utilize the full amount of increment when they provided provisions
within the Act requiring that both the NAAQS and increments must
continue to be met at all times. In areas where the full amount of
increment is not available due to levels of pollution approaching the
NAAQS, states may need to require emissions reductions at existing
sources to accommodate the desired amount of economic growth. Hence, we
do not believe it is reasonable to unduly restrict economic growth in
cleaner areas by setting more restrictive increments to help maintain
air quality levels below the NAAQS in areas which are currently only
marginally attainment.
In addition, we disagree with the commenter's assertion that the
increments will not protect public health. In setting the
PM2.5 NAAQS at 35 [mu]g/m\3\ (24-hour) and 15 [mu]g/m\3\
(annual), EPA concluded that these levels protect public health with an
adequate margin of safety. Regardless of the level at which the
increments are set, no source is permitted to cause the NAAQS to be
exceeded. That is, as noted previously, the upper bound on the
permissible concentration of PM2.5 is determined by the
increment or the NAAQS, whichever is more restrictive in each
particular case. Thus, the entire framework of the PM2.5
regulations, including the safe harbor increments, is protective of
public health. In asserting otherwise, the commenter has misconstrued
our statements in this regard.
In the 2007 NPRM section on the health effects of PM2.5
(72 FR 54127-54128), we discussed the fact that we considered setting
the 24-hour NAAQS in the range of 30 to 35 [mu]g/m\3\ and the annual
NAAQS in the range of 12 to 15 [mu]g/m\3\. However, we concluded in
setting the NAAQS that 35 [mu]g/m\3\ (24-hour) and 15 [mu]g/m\3\
(annual) are protective of public health with an adequate margin of
safety. We did not say, nor do we believe, that PM2.5
concentrations must be below 30 [mu]g/m\3\ (24-hour average) or 12
[mu]g/m\3\ (annual average) to protect public health.
The environmental group commenter believes that there is a
quantifiable relationship between visibility impairment and
PM2.5 levels, citing the 2007 NPRM discussion (72 FR 54135)
as well as the most recent Criteria Document and Staff Paper for
PM2.5. The commenter pointed out that in the 2007 NPRM (72
FR 54135), EPA observed that the proposed Class II short-term safe
harbor increment of 9 [mu]g/m\3\, if combined with the estimated daily
background levels in most areas (i.e., 10 [mu]g/m\3\), would be below
the minimum values recommended in the 2005 Staff Paper for the
secondary short-term standard for PM2.5 (which was 20 [mu]g/
m\3\). Rather than supporting the adequacy of 9 [mu]g/m\3\ as an
increment level to protect visibility, the commenter believes that this
shows that the safe harbor increment is inadequate because consumption
of an increment of 9 [mu]g/m\3\ combined with background levels alone
would cause an area to reach within 1 [mu]g/m\3\ of the staff-
recommended value of 20 [mu]g/m\3\. The commenter added that most areas
would have PM2.5 pollution from motor vehicles and
stationary sources in concentrations substantially greater than
background levels, easily placing these areas above 20 [mu]g/m\3\
(citing the 2005 Staff Paper at 2-77).
The environmental group commenter went on to assert that the safe
harbor PM2.5 increments will not be sufficient to protect
visibility in parks and other natural areas. In the 2007 NPRM, we
stated that a 24-hour average PM2.5 concentration of 20
[mu]g/m\3\ correlates to a visual range of approximately 25 to 35
kilometers. 72 FR 54129. The commenter asserted that this visual range
distance falls far short of what the National Park Service considers to
be good visibility for national parks, adding that the National Park
Service has stated that visibility used to be 90 miles (145 km) on
average in eastern parks, and 140 miles (225 km), on average in western
parks.\18\ The commenter stated that the safe harbor increments would
allow parks and other natural areas to experience PM2.5
pollution that is correlated with a 25-35 km visual range.
---------------------------------------------------------------------------
\18\ The commenter cited http://www.nps.gov/shen/naturescience/visibility_and_haze.htm for historic visibility in national parks.
---------------------------------------------------------------------------
The visibility impairment issue is more complex than suggested by
the environmental group commenter. In addition to predicting what the
maximum ambient change in air quality is for a particular area, a
visibility impairment assessment considers such things as the
frequency, magnitude, and duration of visibility impacts in order to
conclude that an adverse impact will occur.
In addition, the environmental group commenter misconstrued the
illustration we included in the 2007 NPRM. We noted that the lowest
level we considered as a secondary PM2.5 NAAQS was 20 [mu]g/
m\3\, which was considered to address visibility issues in urban areas.
We also noted that in most areas, the estimated 98th percentile of
daily background concentrations is less than 10 [mu]g/m\3\. In adding
the Class II safe harbor increment (9 [mu]g/m\3\) to the 98th
percentile of background levels, we were simply showing that even in
the worst case, the combination of the safe harbor increment and
background PM2.5 would not exceed the most stringent level
we considered for the secondary PM2.5 NAAQS. The commenter
presented this rough, worst-case calculation as if it represented the
typical situation that would result from the safe harbor increments. In
addition, the environmental group commenter's statements do not apply
to parks and special areas that are classified as Class
[[Page 64884]]
I areas because the safe harbor increments for such areas are much
lower.
Another commenter stated that the proposed 24-hour Class I
increment (2 [mu]g/m\3\) would not be protective of AQRVs, particularly
visibility. This commenter noted that the National Park Service uses a
5 percent change in light extinction from estimated natural conditions
as the threshold for ``adverse impacts'' to Class I visibility. The
commenter indicated that depending on the constituents of the ambient
PM2.5 and the humidity, a concentration of 2 [mu]g/m\3\ in a
typical Class I area would result in a change in light extinction
ranging from 13 to 80 percent in the Western United States and from 8
to 50 percent in the Eastern United States and, therefore, would likely
constitute ``adverse impacts'' to Class I visibility. While
acknowledging that the FLM may still determine that the visibility in
the Class I area is adversely affected by an increase in concentration
that is less than the increment, this commenter pointed out that we
stated in the 2007 NPRM that ``generally speaking an increment should
not be so large that it routinely results in substantially more
pollution in Class I areas than is generally acceptable under the AQRV
approach'' (citing 72 FR 54135). The commenter concluded that the
proposed 24-hour PM2.5 increment does not meet this test and
recommended that EPA set a lower PM2.5 24-hour increment.
This commenter appears to have identified a worst-case scenario in
terms of increment concentrations, and although we agree with the
visibility impacts related to those concentrations discussed in the
comment, we do not believe the proposed increment level compromises the
protection of visibility or other AQRVs. Although the ``AQRV test''
uses 5 percent light extinction as a screening threshold, the
determination of adverse impact is made on a case-by-case basis taking
into account the geographic extent, intensity, duration, frequency, and
time of visibility impairment and how these factors correlate with
visitation to the Class I area. The suggestion that the 5 percent
threshold is routinely exceeded by PSD sources or that an absolute
worst-case scenario is occurring to the geographic extent, intensity,
duration, and frequency that would warrant an adverse impact
determination is unsupported, especially considering the relatively few
adverse impact determinations that have been made in the past. It is,
however, important to note that the AQRV analysis is independent of the
PSD increment analysis; whether or not the increment is projected to be
exceeded does not determine the need for an AQRV analysis. The
determination that a facility does or does not cause an adverse impact
on a Class I area is not solely contingent upon the PSD increment, so
we do not believe that lowering the proposed increment is necessarily
more protective of the AQRV.
With respect to these two commenters' concerns about visibility
protection, we continue to believe that the increments cannot be
expected to be the sole means of protecting various welfare concerns.
In the 2007 NPRM, we stated that ``visibility protection in Class I
areas is more adequately provided by the AQRV process.'' Congress
defined AQRVs to specifically include visibility and left it for the
FLMs to define other special attributes of Class I areas that warranted
special protection. We also noted that Congress has established several
visibility programs that target emissions reductions to achieve desired
visibility benefits. See 72 FR 54135. Collectively, these protective
programs, along with the totality of the PSD program, offer an
effective means of addressing unique local problems that cannot be
addressed solely by uniform national increments.
However, the environmental group commenter asserted that these
other programs will not fulfill the statutory purposes. As discussed
previously in sections V.D.4 and 5, the commenter does not believe that
FLM review in the AQRV process and the air quality impacts analysis
required by section 165(a) of the Act are adequate. We disagree; see
sections V.D.4 and 5 for more detail on the comments and our responses.
The environmental group commenter also noted that we cited the
regional haze program as a justification for adopting less protective
PSD rules (referring to 72 FR 54135), but the commenter pointed out
that the haze program applies only to Class I areas and does not apply
at all to the majority of the nation, which is Class II. The commenter
further noted that we stated in the 2007 NPRM that ``some State and
local governments have also developed programs to improve visual air
quality in specific urban areas'' (citing 72 FR 54135), and pointed out
that we gave no specific information on such programs, nor any
information about the visibility protection that they provide beyond
that provided by the proposed increments. The commenter asked that we
identify the specific State and local programs, and that we specify how
much visibility protection such programs are providing.
The commenter is correct that the regional haze program directly
addresses only Class I areas. As we have discussed before, these are
the areas that Congress defined as deserving of the most protection
under PSD, including the visibility protection provisions in subpart 2
of title I, part C of the Act, which is the statutory basis for the
regional haze program. While Class I areas are the target for the
regional haze program, we believe that many areas of the nation will
receive collateral visibility benefits from this program. As emissions
of the pollutants that cause regional haze are reduced, many areas in
the paths of transport will benefit. In addition, as discussed
previously in section V.D.5 of this preamble, PSD applicants must
prepare an analysis of ``other impacts,'' including visibility impacts,
in areas other than Class I areas.
Regarding State and local visibility programs, in the 2005 Staff
Paper EPA described several existing programs to improve visual air
quality in urban areas. These programs were located in Denver, CO;
Phoenix, AZ; and Lake Tahoe, CA. Also, the states of California and
Vermont have each established standards to protect visibility. See the
2005 Staff Paper, pages 6-17 through 6-23.
The environmental group commenter cited the 2007 NPRM (72 FR 54135)
where we said that the use of ``distinct PM increments for visibility
protection is not the most effective means of addressing the visibility
problem.'' The commenter believes that this claim is based on false
premises, including the idea (discussed previously) that other programs
effectively protect visibility nationwide, and the idea that the only
option is a ``distinct'' PM increment for visibility protection. As to
the latter, the commenter stated that EPA can strengthen the safe
harbor increment to ensure visibility protection and need not adopt a
separate ``visibility'' increment. In addition, the commenter asserted
that EPA has ignored the statutory mandate that the PSD rules fulfill
the statutory goals and purposes, and that we cannot shirk that
statutory duty merely because we claim some other type of action would
be ``more effective.''
We continue to believe that Class I area visibility protection
under the PSD program is appropriately addressed via the AQRV process.
As mentioned previously, Congress explicitly included ``visibility'' as
an AQRV for which FLMs would have an affirmative responsibility to
protect in Class I areas under their jurisdictions. Where the FLM
successfully demonstrates that there
[[Page 64885]]
would be an adverse impact on the AQRV (e.g., visibility), a State
cannot issue a PSD permit, even when the source's emissions do not
violate the PM2.5 increments. In addition, we continue to
believe that the analysis of other impacts, including visibility, in
non-Class I areas is the appropriate means of addressing visibility
protection in these areas, as envisioned by Congress when it enacted
the PSD provisions of the Act.
As a result, we do not believe it is necessary to create a distinct
increment (e.g., with a different averaging period) or to lower the
safe harbor increments to protect visibility in urban, non-urban, or
Class I areas across the United States. We reach this conclusion in
proper consideration of the other, more direct approaches being used to
address visibility problems in the United States. The primary such
approach, the regional haze program, is within the PSD framework for
PM2.5. Note that part C of title I of the Act, ``Prevention
of Significant Deterioration of Air Quality,'' includes subpart 2,
which is the statutory basis for the regional haze program. Regarding
our consideration of other State and local visibility protection
measures that are outside the PSD framework, we do not believe it is
reasonable to disregard these area-specific measures that focus on the
preferences of individual communities where a uniform national
increment for visibility protection generally cannot.
The environmental group commenter also stated that the proposed PSD
rules fail to ensure fulfillment of the ``enhancement goal'' set out in
the Act. The commenter noted that section 101(a) states as the Act's
first purpose: ``to protect and enhance the quality of the Nation's air
resources,'' while section 160(2) states that the purpose of the PSD
program is to ``preserve, protect, and enhance'' air quality in parks
and other special areas. The commenter asserted that the proposed rule
did not address these enhancement requirements or explain how the
proposed increments would fulfill those requirements.
This same issue was raised in the 2005 PSD rule affirming the
NO2 increments. At that time we expressed our belief that
the goal to enhance air quality in national parks and wilderness areas
is implemented through the regional haze program while the PSD program
focuses on preserving and protecting air quality in these areas.
However, when a PSD increment violation is identified, we agree that
EPA may require a State to revise its SIP to correct the violation. See
40 CFR 51.166(a)(3). Otherwise, we do not interpret these PSD
provisions to authorize us to direct states in their SIPs to achieve
reductions in emissions from existing sources for PSD purposes.
We recognized at that time, and continue to believe, that the
growth management goals of PSD may also be fulfilled when the states
adopt controls on existing sources that would reduce emissions and
allow growth from new sources and major modifications to existing
sources without causing significant deterioration. Under the increment
approach, we have interpreted the PSD rules to allow states to require
reductions from existing sources in order to expand the allowable
increments and, thereby, allow for more growth under the PSD program.
However, we have never required states to do so because, in the absence
of an increment violation, we do not believe section 166 and other
provisions in part C of title I of the Act give us the legal authority
to mandate such reductions for PSD purposes.
Another commenter stated that the PM2.5 increments
should be twice the recommended levels because scientific studies do
not support the need for such low levels for protection of health and
welfare. The commenter believes that increments at the proposed levels
would jeopardize the goal of providing opportunities for economic
growth. The commenter expressed concern over EPA's use of epidemiologic
studies and questioned the ability of such studies to provide a
reliable evaluation of health risks. The commenter claimed that
epidemiologic studies are capable of finding association between a
substance or exposure and a health effect but rarely capable of
determining if there is causation, while toxicological studies using
randomized trials are specifically designed to determine causation. The
commenter added that other factors providing evidence for causation
include dose-response relationships, consistency, and repeatability of
studies, which the commenter said are not present in the studies cited
by EPA. The commenter specifically referred to two studies,
acknowledged by EPA to show no evidence of a dose-response relationship
gradient between PM2.5 and specific health related effects.
We disagree with the commenter's recommendation that the increments
should be twice the proposed (and final) levels. The scientific studies
to which the commenter referred pertain to studies that EPA used to
determine the health-based NAAQS for PM2.5, and we do not
believe it is relevant to this rule to respond to comments related to
the setting of the NAAQS. The NAAQS are designed to protect public
health and welfare; increments then are intended to insure that air
quality in clean areas is not allowed to deteriorate significantly, and
the PSD regulations insure that any such deterioration does not lead to
air pollution levels that exceed the levels defined by the NAAQS.
As discussed previously, we are finalizing this rulemaking using
the safe harbor approach under section 166(a) of the Act. Using this
approach, we calculated the ``safe harbor'' increments as percentages
of the NAAQS comparable to the percentages that Congress used to
establish the original statutory increments for PM and SO2.
These values represent the level of effectiveness necessary to satisfy
section 166(d) of the Act, and could be tightened if necessary based on
further analysis to determine if additional measures are necessary to
fulfill the requirements of section 166(c) of the Act. Thus, under this
approach and on this record, we do not conclude that it is appropriate
to finalize increments at levels any less stringent than the safe
harbor increments, as the commenter recommends.
7. Compliance Determinations for the PM2.5 Increments
a. Modeling Compliance With PM2.5 Increments
Section 163(a) of the Act provides that ``In the case of any
maximum allowable increase * * * for a pollutant based on
concentrations permitted under the national ambient air quality
standards for any period other than an annual period, such regulations
shall permit such maximum allowable increase to be exceeded during one
such period per year [emphasis added].'' Accordingly, the existing PSD
rules allow one exceedance per year of each short-term increment
defined by the rules. See 40 CFR 51.166(c) and 52.21(c). With the
addition of the PM2.5 increments to the list of maximum
allowable concentrations in the PSD rules, the existing provision
allowing one exceedance per year applies equally to the 24-hour
PM2.5 increments as well. Thus, when modeling increment
compliance, the highest value of the second-highest modeled increase in
estimated PM2.5 concentrations at each model receptor for
the 24-hour averaging time should be less than or equal to the maximum
allowable increase for PM2.5. For the annual increments, the
modeled annual averages should not exceed the annual maximum allowable
increase for PM2.5. See EPA's ``Guideline on Air Quality
Models'' at 40 CFR part 51 appendix W, section 10.2.3.3.
[[Page 64886]]
We did not expressly state in the 2007 NPRM the implications of
adding PM2.5 increments to the existing list of increments
in 40 CFR 51.166(c) and 52.21(c) of the PSD regulations. Nevertheless,
it should have been clear at the time that, in the absence of
alternative language for PM2.5, the existing provision
allowing one exceedance for the short-term increments would apply to
the increments for PM2.5 along with the increments already
listed. We did not receive any comments either supporting or opposing
these methods for determining compliance with the PM2.5
increments.
We recognize that the above approach for determining compliance
with the 24-hour PM2.5 increments differs from the approach
contained in guidance that we provided in a March 23, 2010 memo titled
``Modeling Procedures for Demonstrating Compliance with
PM2.5 NAAQS,'' which sets forth a procedure designed to
demonstrate compliance with a statistically based standard that is met
when the 98th percentile 24-hour concentration is less than or equal to
35 ug/m3. A similar dichotomy exists for the 24-hour
PM10 increments and NAAQS, where compliance with the 24-hour
PM10 NAAQS is based on an expected exceedance form of the
standard.
b. Condensable PM
Initially, the EPA will not require PSD applicants under the
Federal PSD program to consider condensable PM in emissions
calculations to determine whether a proposed project is subject to the
PSD requirements. In addition, we will not require the condensable
portion to be considered in the required PM2.5 air quality
analyses. In our May 2008 PM2.5 NSR Implementation Rule, we
announced that we would not require that states address condensable PM
in establishing enforceable emissions limits for either PM10
or PM2.5 in NSR permits until the completion of a transition
period. Further, we indicated that the transition period would end
January 1, 2011 unless EPA advanced the date through the rulemaking
process. We also indicated that such rulemaking would involve the
assessment and possible revision of test methods for measuring
condensable emissions and taking comment on an earlier closing date for
the transition period in the NSR program if we are on track to meet our
expectations to complete the test methods rule much earlier than
January 1, 2011.\19\ In addition, states that have developed the
necessary tools are not precluded from acting to include condensable PM
emissions in NSR permit actions prior to the end of the transition
period, especially if it is required in an applicable SIP. See 73 FR
28334-28336.
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\19\ We proposed test methods for measuring PM10 and
PM2.5, including condensable PM emissions, from
stationary sources on March 25, 2009 (74 FR 12970). In the same
notice, we sought comments on whether to end the NSR transition
period for condensable PM earlier than January 1, 2011. We
anticipate publication of a final rule announcing our decision on
the NSR transition period in July 2010.
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c. PM2.5 Precursors
In the 2007 NPRM, we proposed to add SILs for PM2.5 to
the PSD regulations at 40 CFR 51.166 and 52.21. (The SILs are described
more fully in section VI of this preamble.) Accompanying these SILs, we
proposed to add a new paragraph to the regulations explaining that the
requirements for a source impact analysis for PM2.5 would be
considered to be satisfied, without further air quality modeling, if it
were to be shown that the increase in direct PM2.5 emissions
from the source or modification will cause air quality impacts less
than the prescribed SILs for PM2.5. The reasoning at the
time was that state-of-the-art modeling would not be available to
adequately account for secondary PM2.5 impacts resulting
from emissions of precursors of PM2.5, e.g., SO2
and NOX. Nevertheless, the existing PSD rules currently
define potential precursors of PM2.5. Based on the proposed
language, the required compliance demonstration for the
PM2.5 NAAQS and the PM2.5 increments (when
promulgated) would be limited by regulation to an analysis of direct
PM2.5 emissions, and would not include consideration of
emissions of PM2.5 precursors for comparing the modeled
source impacts to the prescribed SILs for PM2.5.
The impacts of PM2.5 precursors on ambient
concentrations of PM2.5 cannot be determined from the
dispersion models that EPA has currently approved for modeling
individual PSD sources. Such models are not designed to consider
chemical transformations that occur in the atmosphere after the
precursor emissions have been released from the source. Consideration
of these transformations is necessary to be able to add precursor
impacts into the total modeled ambient PM2.5 concentrations
for comparison to the SILs for PM2.5.
The technical tools needed to complete a comprehensive analysis of
all emissions that contribute to ambient concentrations of
PM2.5 are only in the developmental stage; nevertheless, we
believe that it would be inappropriate to restrict the regulatory
language in such a way that future regulatory amendments would be
required to enable the inclusion of precursor impacts in the
PM2.5 analysis as the necessary technical tools become
available. Estimating techniques are being developed that will be able
to be applied to the PM2.5 analysis in the near future,
which could not be required if the regulatory language precluded them.
We acknowledge the concerns that have been expressed by some commenters
about the shortcomings of not considering the impacts of
PM2.5 precursors under the PM2.5 air quality
analyses. Accordingly, we believe that the new provision for applying
the SILs for PM2.5 to the required analyses for the NAAQS
and increments should not be self-limiting by specifying the use of
only direct PM2.5 emissions. Instead, the new provision
contained in this final rule provides that the test will be based on
whether ``the emissions increase * * * would cause * * * air quality
impacts less than [the PM2.5 SILs].'' See new 40 CFR
51.166(k)(2) and 52.21(k)(2). We believe that it would be more
effective to rely on interim policy and guidance as appropriate to help
determine the best methods available to make the required assessment of
source impacts on ambient PM2.5 resulting from any
emissions.
F. Final Action on Trigger and Baseline Dates for PM2.5 Increments
In the 2007 NPRM, we proposed as part of Option 1 to require the
implementation of the PM2.5 increment system (annual and 24-
hour increments) with new baseline areas, baseline dates, and trigger
date. Specifically, we proposed that the major source baseline date and
trigger date, both fixed dates, would be defined as the effective date
of the final rule and would reflect a date 1 year from the date of
promulgation, in accordance with section 166(b) of the Act. In
contrast, under Option 2 (both 2A and 2B), we proposed to establish new
baseline dates for the 24-hour PM2.5 increments, but to
retain the existing baseline areas and dates for the annual
PM2.5 increments because the annual increments would be
equivalent substitutes for the existing annual PM10
increments.
In light of the then-current and expected trends in
PM2.5 concentrations, our judgment was that starting with
new baseline dates on or after the effective date of this rule would
make the PSD increments for PM2.5 more protective. We
proposed that any emissions reductions occurring prior to the effective
date of this rule would lower
[[Page 64887]]
the baseline concentration rather than be used for expanding the
PM2.5 increment. If a retroactive baseline date were to
apply, emissions reductions occurring prior to the effective date of
this rule would serve to expand the available increments, enabling more
new pollution than would otherwise be allowed to occur.
We also expressed our belief that starting with different baseline
dates to implement increments for PM2.5 would be appropriate
because Option 1 treats PM2.5 essentially as a ``new''
pollutant for purposes of PSD and section 166 of the Act. We continue
to believe that establishing a new baseline also overcomes significant
implementation concerns that would otherwise exist if the existing PM
baseline were maintained. In particular, if we were to require sources
and reviewing authorities to conduct PM2.5 increment
analyses based on the minor source baseline dates previously
established years or even decades ago under the TSP or PM10
program, they would have to attempt to recreate the PM2.5
emissions inventory as of the minor source baseline date in order to
determine the baseline PM2.5 concentration for the area. For
early minor source baseline dates in particular (e.g., 1976 in some
areas of the United States), establishing the emissions inventory for
PM2.5 would be extremely difficult, cumbersome, and
potentially inaccurate because historic emissions inventories did not
include PM2.5 emissions. For all of these reasons, we
proposed Option 1 as our preferred option and requested comment on this
contingent safe harbor approach for annual and 24-hour PM2.5
increments under Option 1.
Under Option 1, we proposed that the PM2.5 increments
would be subjected to a 1-year delay consistent with the procedures
under section 166(b) of the Act, which provides in general that these
rules ``shall become effective one year after the date of
promulgation.'' Alternatively, we sought comment on a 60-day delay as
part of our proposal under Option 1. In the proposal we requested
comment on the argument that, while the Act includes a 1-year
implementation delay for new increments, the same provision calls for
EPA to promulgate new increments within 2 years of the promulgation of
the NAAQS. Given that these PM2.5 increments are being
promulgated more than 2 years after promulgation of the NAAQS, we
expressed our belief that the overall congressional intent reflected in
section 166 of the Act could possibly be met by setting the effective
date of the PM2.5 increments earlier than the ``one year
after the date of promulgation'' provided in section 166(b) of the Act.
Twelve commenters supported our proposal under Option 1 to
establish new trigger and baseline dates for PM2.5,
regardless of the particular increment option that they otherwise
supported. These commenters generally saw new dates as being the best
approach because of various problems that would result from retaining
existing trigger and baseline dates. Some commenters claimed that it
would be technically difficult to try to reconstruct old inventories to
determine the amount of PM2.5 emitted by sources in the
past.
One commenter stated that establishing PM2.5 increment
inventories using existing PM10 baseline dates would be
``extremely difficult, cumbersome, and necessarily inaccurate and
unreliable as historic emissions did not speciate PM2.5
emissions.'' A State/local agency commenter said that it would be
``virtually impossible for States to calculate the PM2.5
component of previously consumed PM10 increments because
data on the fine and coarse fractions of source emissions are largely
unavailable.''
Yet another commenter claimed that ``resurrecting PM2.5
inventories based on the PM10 baseline dates would be
insurmountable.'' Similar comments were echoed by several commenters
who supported the use of legal authority set forth in section 166(f)
(``equivalent substitution'' approach) for developing the numerical
values for the PM2.5 increments. One of these commenters
stated that he did not ``believe the establishment of new baseline
dates for PM2.5 would abandon past cases of increment
consumption for PM10, because the 24-hour PM10
increments would still be in effect * * *.''
One commenter suggested that ``EPA establish the trigger date as of
the date when it officially established the non-attainment and
attainment areas for PM2.5; that is, April 5, 2005.'' The
commenter explained that this approach is consistent with the PSD
regulations from their inception and partially mitigates EPA's delays
in implementing the PSD program for PM2.5. The commenter
believes ``that States should be required to use the baseline areas
previously established for their PSD program, unless the process for
redefining these areas strictly follow procedures in the PSD
regulations and EPA policy.'' The commenter claimed, ``this will
minimize any inconsistent applications of the regulations for
PM2.5.''
One commenter noted that our proposed PM2.5 increments
were very low and ``facilities may find themselves immediately out of
compliance with the PM2.5 increments upon promulgation of
the rule, based on a January 1975 or 1977 baseline date.''
One commenter indicated that the historic TSP/PM10
baseline dates should be retained. This commenter favored the
equivalent substitution approach under section 166(f) and, consistent
with that approach, retention of the existing baseline dates.
Having considered all the comments, we believe that the most
reasonable approach for addressing the relevant dates associated with
the PM2.5 increments is to start anew with the baseline date
concept. As already mentioned, the commenters have identified
difficulties that would occur if the PM2.5 emissions
inventory for increment analyses had to be created for an earlier
period of time, and the existence of these difficulties supports the
approach under Option 1 to establish new dates for implementing the
PM2.5 increments. Also, these new baseline dates for
PM2.5 increments will not undo the current protection
provided by the existing increments for PM because we are not revoking
the 24-hour or annual PM10 increments under this new rule.
Accordingly, this final rule establishes independent PM2.5
increments using a ``trigger date'' and ``major source baseline date''
that are separate from the dates defined for the PM10
increments. Consequently, new minor source baseline dates and the
corresponding baseline areas will be used for the annual and 24-hour
PM2.5 increments, and will be established when a source
applies for a PSD permit any time on or after the new trigger date for
PM2.5. (See also the discussion about changes to the
definition of ``baseline area'' in section V.G of this preamble.)
The ``major source baseline date'' for PM2.5 is being
set as October 20, 2010--the date of publication of this final rule.
The setting of this date differs from previous major source baseline
dates which were set as the date of publication of the proposed rule,
but is similar to the major source baseline date set for the other
increments in that the date precedes the effective date for
implementing the increments, and thereby requires that certain major
source emissions increases that occur before the trigger date
retroactively count toward the amount of increment consumed.
The ``trigger date'' is being set at October 20, 2011, which is 1
year after the date of promulgation of this final rule. We are using
this approach to define the date on which the PM2.5
increments become effective as 1 year
[[Page 64888]]
from the date of publication, consistent with the 1-year delay required
under section 166(b) of the Act. This date for the ``trigger date''
separates the applicability date of the PM2.5 increments
from the effective date of this final rule in general, but also ensures
that the ``minor source baseline date'' for PM2.5 for any
particular PM2.5 attainment or unclassifiable area cannot be
established until after the increments become effective in this final
rule. The implementation of these dates as part of the PM2.5
increment system is discussed in greater detail in section VIII of this
preamble.
We recognize that some may still have a concern about our decision
to set the major source baseline date as the date of publication of
this final rule in light of the fact that the PM2.5 NAAQS
have been in place since 1997; however, we believe that the selection
of possible earlier dates would require states to retroactively
establish PM2.5 emissions inventories for increment analyses
during a period when sources were generally not required to conduct
PM2.5 air quality analyses. Hence, given the lack of
information, and considering the technical difficulties in doing so, we
do not believe that it would be appropriate to require states and
sources to retroactively account for PM2.5 increment
consumption by setting the major source baseline date at an earlier
date than the date we have selected.
G. Definition of ``Baseline Area'' for PM2.5
No changes were proposed with respect to the definition of
``baseline area'' for PM2.5 increments. One commenter,
however, noted that fact in claiming that we did not adequately account
for significant impacts of PM2.5 for purposes of defining
the ``baseline area'' for the PM2.5 increments. Under the
existing regulations, the establishment of a baseline area for any PSD
increment results from the submittal of the first complete PSD
application, and is based on both the location of the proposed source
and the impact of the source's emissions on the area. In accordance
with the definition, the attainment or unclassifiable area in which the
proposed source would construct is always part of the baseline area in
which the minor source baseline date is established and the increment
analysis is conducted. In addition, the definition provides that any
surrounding attainment or unclassifiable area in which the proposed
source's impact is greater than 1 [mu]g/m\3\, annual average, would
also become part of the baseline area, assuming the area had not
already been established as a baseline area by a previous application
for a PSD permit. See 40 CFR 51.166(b)(15) and 52.21(b)(15).
As explained in the preamble for the 1980 PSD regulations, EPA
selected an impact of 1 [mu]g/m\3\, annual average, for the definition
of ``baseline area'' because that value was considered the level of
significance for both SO2 and PM when the definition was
originally established.\20\ There was no mandate at that time that a 1
[mu]g/m\3\ impact be used to determine the baseline area for increments
for other pollutants; however, the use of a 1 [mu]g/m\3\ impact in the
definition of ``baseline area'' was not changed when EPA developed
increments for NO2 in 1988 because EPA also defined
``significant'' for NO2 using the same annual average
concentration of 1 [mu]g/m\3\. The EPA has determined, however, that
``significant'' for PM2.5 ambient impacts should be
considered to occur at a lower concentration than 1 [mu]g/m\3\.
Elsewhere in this preamble, we have indicated that the SIL for
PM2.5 in this final rule is 0.3 [mu]g/m\3\, annual average.
Consequently, although no change to the definition of ``baseline area''
was proposed in this rule, we believe it is necessary and appropriate
to define in this final rule a level of significance of 0.3 [mu]g/m\3\,
annual average, for establishing a new baseline area for purposes of
PM2.5 increments. See revised 40 CFR 51.166(b)(15)(i) and
52.21(b)(15)(i).
---------------------------------------------------------------------------
\20\ ``A source will be considered to impact an area if it has
an impact of 1 [mu]g/m\3\ or more of SO2 or PM on an
annual basis. This figure has been selected because it corresponds
to levels of significance used in previous Agency determinations for
SO2 and PM. 45 FR 52716.
---------------------------------------------------------------------------
Had we established the SIL at 1 [mu]g/m\3\, annual average, as
proposed under Option 1 for SILs, then the definition of ``baseline
area'' would not need to be revised. However, the revised definition in
this final rule is consistent with our decision to establish a SIL of
0.3 [mu]g/m\3\, annual average, for PM2.5. We consider this
action to be a logical outgrowth of our decision to establish a SIL for
PM2.5 and the comment concerning the effect of that action
on the definition of ``baseline area.'' Thus, we believe that our
failure to initially propose this change to the definition of
``baseline area,'' based on the possibility of selecting Option 3 for
defining the SIL for PM2.5, does not warrant a reproposal.
H. No Final Action With Respect to the Proposed Revocation of PM10
Annual Increments
In the 2007 NPRM, we proposed to either revoke or replace the
annual increments (Class I, II, and III) for PM10 to conform
to the earlier revocation of the annual PM10 NAAQS. We
proposed to revoke the annual increments, based on the same technical
evidence that led us to revoke the annual PM10 NAAQS, if we
decided to use Option 1 for adopting PM2.5 increments, and
discussed our authority and rationale for doing so. 72 FR 54136.
As an alternative, under Options 2A and 2B we proposed to replace
the existing annual PM10 increments with equivalent
substitute PM2.5 increments using the authority under
section 166(f) of the Act. After further analysis and consideration of
the comments on this issue, we have decided not to take any final
action on our proposal to revoke the existing increments for
PM10 as part of this rulemaking. The effect of not taking
final action with respect to the PM10 annual increments is
to leave those increments in place and unchanged.
Three commenters agreed with EPA's proposal to ``adopt the 24-hour
and annual PM2.5 increments and to revoke the annual
PM10 increments.'' One commenter stated, ``counting and
tracking increment is confusing enough without adding the confusion of
potentially overlapping PM standards.'' The commenter noted that the
``cleanest approach is to establish a single new PM2.5
increment and work from there.'' The commenter suggested that EPA first
``develop a coarse fraction increment, once EPA establishes coarse PM
NAAQS.'' The commenter added that the removal of the PM10
annual increment is supported by the removal of the ``health based
standard for annual PM10.''
One of the commenters agreed, ``it makes no sense for EPA's
regulations to contain an annual increment for PM10 even
though an annual PM10 NAAQS no longer exists.'' The
commenter added, ``EPA is without authority under Section 166(f) to
retain the PM10 annual increment if it adopts a
PM2.5 annual increment.'' This commenter explained, ``EPA is
compelled by law to eliminate the PM10 annual increment.''
We agree with this commenter that section 166(f) is a
``substitution'' approach; however, as we stated in our 2007 NPRM, we
expressed some concern about using section 166(f) to substitute
PM2.5 increments for PM10 increments. In fact,
some commenters challenged our authority under section 166(f) to
replace the PM10 increments. In our response to the
following comments, we address the legal issues that we believe prevent
us from simply revoking the PM10 increments.
[[Page 64889]]
One environmental commenter claimed, ``the agency has no authority
to repeal an existing PM10 increment without at the same
time restoring the corresponding TSP increment.'' The commenter noted,
``Congress established the TSP increments by statute and gave EPA no
authority to revoke them,'' and ``instead, Congress gave EPA only
limited authority to substitute PM10 increments for TSP
increments under the conditions specified in Section 166(f).'' The
commenter explained, ``EPA cannot revoke the annual PM10
increments, either by ``replacing'' them with PM2.5
increments or otherwise, unless EPA at the same time restores the
annual TSP increment.'' The commenter noted, ``retention of the
PM10 annual increment is also entirely compatible with the
statutory purposes, notwithstanding EPA's revocation of the annual
PM10 NAAQS.'' The commenter further noted the following
examples/evidence that retention of the annual PM10
increments is important to achieving the goals of the Act's PSD
provisions:
``While EPA attributes the visibility impairing impacts of
PM pollution primarily to elevated short term fine particle
concentrations, EPA recognizes that PM10 plays a significant
role in the other welfare related impacts of PM pollution.'' 72 FR
54136.
``EPA also states that the most significant PM-related
ecosystem-level effects result from long term cumulative deposition * *
* that exceeds the natural buffering or storage capacity of the
ecosystem and/or affects the nutrient status of the ecosystem.'' 72 FR
54131.
Five State/local agency commenters opposed the revocation of
PM10 annual increments ``until EPA makes a determination on
a PM-coarse NAAQS'' and/or ``establishes equivalent increments for PM-
coarse.'' One of these commenters added, ``it is prudent to maintain
the PM10 increments until EPA makes a determination on the
health and environmental effects of the coarse fraction of PM.'' The
commenter claimed that, ``if EPA retains the annual PM10
increments'' ``then the determination of PM2.5 increments
can complement the continuation of PM10 increment
determinations without any discontinuities or unwanted degradation
concerns.''
Another one of these commenters stated, ``the basis for dismissing
the annual PM10 NAAQS by the substitution of fine particle
NAAQS to address certain health and welfare effects does not provide a
basis for dismissing a PSD increment which is meant to stop significant
degradation of air quality.'' The commenter noted, ``as refinements are
made to estimation of fine particle emissions or in instances where
these are deemed not to be a major component of particulate emissions,
the PM10 annual increment could prevent long term
deterioration of air quality associated with the coarse component.''
One State/local agency commenter noted, ``EPA also proposes to
replace the PM10 annual increment with the corresponding
PM2.5 increment under the Section 166(f) options 2A and 2B
as well, but does not provide a substantive basis for such an action.''
The commenter does ``not see the tension noted by EPA between Sections
166(a) and (f) with respect to reaching a holistic solution if EPA
views PM2.5 as a new indicator of PM, as we believe it
can.'' The commenter explained, ``under this approach, if EPA
determines that coarse particle levels are necessary to protect the
public from certain exposures not addressed by PM2.5, then
it will be appropriate for EPA to define complementary increments for
coarse particulates as another indicator of PM.'' The commenter also
asserted that the 24-hour increments for PM2.5 must be based
on section 166(f) authority, but believes that the PM2.5
increment need not replace the PM10 increment for this
averaging period.
One commenter requested that EPA ``keep the PM10 PSD
program (especially the increments) in place until the full
PM2.5 program is adopted and in place.''
One commenter ``does not support revoking the annual
PM10 increments,'' because the commenter feels that ``there
are too many uncertainties regarding PM2.5.'' The commenter
provided the following example: ``The program has been dragging for
years, analytical methods are not formulated, the NSR part of the
implementation rule has not issued, condensables are not yet included,
and the impact of precursors has not been definitively explored.'' The
commenter explained that ``under these conditions, nothing concerning
PM10 should be revoked until the reasons for doing so are
clearly understood and the overall impact on ensuring clean air and the
public health and welfare have been fully explored.'' The commenter
suggested, ``PM10 increments and NAAQS should remain in
effect until these issues have been resolved to the satisfaction of the
Administrator.'' This commenter believed that Options 2A and 2B must be
based entirely on section 166(f) of the Act, but that the presence of
increments for both PM10 and PM2.5 can be
supported under this section because the two sets of increments
complement each other. The commenter indicated that the problem will be
resolved when sufficient data are available to revoke the
PM10 NAAQS and increments and/or PM10 is replaced
by PM10-2.5.
One State/local agency association commenter recommended that ``EPA
can and should continue both the 24-hour and annual average
PM10 PSD increment program until PM10-2.5
standards are promulgated.'' The commenter explained that ``EPA has the
discretion to accomplish this under CAA Sec. 166(f)'' and ``at a
minimum, the agency should continue the 24-hour PM10
increments in conjunction with the continuation of the 24-hour
PM10 NAAQS.''
As stated previously, in this rule we are taking no final action on
our proposal to revoke the annual PM10 increments even
though the annual PM10 NAAQS has been revoked. Based on
comments and our own legal analysis of the PM10 increments,
we have concluded that there is a strong legal basis for not revoking
the annual increments at this time. The PM10 increments were
promulgated on June 3, 1993 (58 FR 31622) as replacement increments for
the then existing statutory increments for PM measured as TSP. The fact
that EPA promulgated the PM10 increments as ``equivalent''
replacements for the TSP increments under the authority of section
166(f) of the Act is important in that EPA does not have authority to
simply remove the TSP increments that were explicitly defined within
the PSD program requirements in the Act. Accordingly, we believe that
the annual TSP increments would be restored by default should we decide
to revoke the annual PM10 increments as proposed. However,
even if the original annual TSP increments were not restored, there is
no basis for automatically revoking the annual PM10
increments simply because we have revoked the annual PM10
NAAQS, because annual increments are not contingent upon the existence
of annual NAAQS. This is clear from the court's decision in the earlier
NO2 increment litigation stating that increments for a
particular pollutant do not necessarily need to match the averaging
periods that have been established for NAAQS for the same pollutant.
EDF v. EPA, at 189-190 (``* * * the `goals and purposes' of the PSD
program, set forth in Sec. 160, are not identical to the criteria on
which the ambient standards are based.'').
I. Other Comments on Increments
Ten commenters (including State/local agencies and industry
commenters) supported section 166(f) of the Act as the basis for
PM2.5 increments. These commenters typically
[[Page 64890]]
voiced the belief that when Congress enacted section 166(f), it
authorized EPA to update PM increments when another indicator was
defined, and that section 166(f) allows EPA to continue do so as long
as these increments are of equal stringency to the prior increments.
Some of these commenters believe that section 166(f) is the only
legitimate approach under the Act, while others indicated simply that
it is preferable to section 166(a). Some of the commenters believe that
section 166(f) authority can be used to add PM2.5 increments
to the existing PM10 increments. Others believe that
PM2.5 increments finalized under section 166(f) must fully
replace the existing PM10 increments, and recommended doing
so.
For the reasons discussed previously in this preamble, EPA has
decided to finalize the PM2.5 increments under the authority
of section 166(a) of the Act. With respect to the potential creation of
PM2.5 increments under section 166(f) (as discussed in the
2007 NPRM at 72 FR 54120-54121), we have not reached any final
conclusion as to whether that approach is authorized by the statute,
but believe that such an approach raises significant legal issues.
Because the Agency is not relying on section 166(f) in this rulemaking,
we do not address these issues in this preamble, though some additional
discussion is included in the Response to Comments document for this
rule.
One industry association that supported the Option 1 approach based
on section 166(a) authority also acknowledged that EPA is authorized to
use the Option 2 approach based on section 166(f) authority. An
industry commenter indicated that 2007 NPRM's arguments regarding the
alternative legal authorities under section 166(a) and (f) were not
compelling; the commenter recommended setting the PM2.5
increments at the levels proposed as Option 2B because they would have
the lowest economic impact.
As noted previously, we have decided to finalize Option 1 based on
section 166(a) authority because we believe that provision provides the
clearest statutory authority for purposes of developing increments
based on PM2.5. We would point out, however, that any
conclusion as to which option would yield increments that ``have the
lowest economic impact'' must include a consideration of not only the
levels of the increments but also the associated baseline dates that
define when emissions changes must be considered to affect the amount
of increment consumed. Under Options 2 and 3, the PM2.5
increments would be regarded as replacement increments for the
PM10 increments and, as such, would include amounts of
increment (based upon the PM2.5 component) already consumed
under the existing PM10 increment system. Thus, portions of
the substitute PM2.5 increments could have already been
consumed by previous PSD sources that emit PM. If, in fact, a portion
of the PM2.5 increments had already been consumed by the
prior PM10 increment consumption process, than there would
be a basis to conclude that less additional economic growth would be
allowed under a set of replacement PM2.5 increments as
compared to PM2.5 increments based on separate, independent
baseline dates.
One industry commenter suggested that EPA develop geographic area-
specific increments (and SILs and SMCs) that take local conditions into
account. The commenter pointed out that PM2.5 levels in PSD
areas proximate to international borders may be elevated by sources
outside the legal and practical control of the United States and State
authorities. The commenter also noted that PM2.5 levels may
be elevated by natural conditions, such as drought, fires, geologic
formations (sandy or fine-grained surface features), high winds, etc.,
leading to excessively dusty ambient conditions over which the local
area has no control. The commenter indicated that local area baselines
must reflect these PM emissions, though they are not reflected in the
local area's emissions inventory. The commenter urged EPA not to
penalize such PSD areas by imposing uniform national PSD increments (or
SILs or SMCs) where the conditions of concern are not capable of
control.
As previously discussed, this final rule establishes an area
classification system with prescribed, uniform PM2.5
increments for each class. We do not believe that it is necessary to
develop different increments (or SILs or SMC) for different areas of
the country. Emissions from natural conditions such as those described
by the commenter would not consume increment due to their natural and
temporary nature. In addition, if a State wishes to disregard new
emissions from sources outside the United States, the State's PSD
program may provide that such emissions do not consume increment (see
40 CFR 51.166(f)(1)(iv)).
VI. Final Action on PM2.5 SILs
A. EPA's Determination on SILs for PM2.5
It is EPA's longstanding policy to allow the use of the SILs as de
minimis thresholds under the NSR programs at 40 CFR 51.165(b) and part
51, Appendix S, to determine whether the predicted ambient impact
resulting from the emissions increase at a proposed major new
stationary source or modification is considered to cause or contribute
to a violation of the NAAQS. We have also allowed the SILs under the
PSD program to determine: (1) When a proposed source's ambient impacts
warrant a comprehensive (cumulative) source impact analysis; (2) the
size of the impact area within which the air quality analysis is
completed, and (3) whether the emissions increase from a proposed new
major stationary source or major modification is considered to cause or
contribute to a violation of any NAAQS.
We proposed three separate options for setting SILs for
PM2.5. The first option relied upon the same approach we
proposed for PM10 in the 1996 NSR Reform proposal. This set
included Class I SILs set at 4 percent of the Class I PM2.5
increments. For class II and III areas, we proposed to codify the SIL
values that already existed for PM10, i.e., 1.0 [mu]g/m\3\
(annual) and 5.0 [mu]g/m\3\ (24-hour). Options 2 and 3 relied on
scaling the PM10 SILs, as codified in 40 CFR 51.165(b), by a
particular ratio. Specifically, for Option 2, the multiplier was the
emissions ratio of PM2.5 to PM10 for point
sources in the 1999 NEI; for Option 3 the multiplier was the ratio of
the PM2.5 NAAQS to the PM10 NAAQS. The resulting
SILs were proposed as follows:
----------------------------------------------------------------------------------------------------------------
Proposed SILs ([mu]g/m\3\)
-----------------------------------------------------
Option Class I Class II Class III
-----------------------------------------------------
Annual 24-hr Annual 24-hr Annual 24-hr
----------------------------------------------------------------------------------------------------------------
1......................................................... 0.04 0.08 1.0 5.0 1.0 5.0
2......................................................... 0.16 0.24 0.8 4.0 0.8 4.0
3......................................................... 0.06 0.07 0.3 1.2 0.3 1.2
----------------------------------------------------------------------------------------------------------------
[[Page 64891]]
We have decided to finalize the PM2.5 SILs proposed
under Option 3. As explained earlier, these values will be used in the
Federal PSD preconstruction review process consistent with our
proposal. See 72 FR 54138-41 and 54143.
States are not required to adopt SILs in their NSR or PSD programs;
the analyses for PM2.5 required by each applicable
regulation can be carried out without using a SIL.\21\ Therefore, we do
not intend for any specific deadlines to apply under the regulations at
40 CFR 51.165(b), 51.166, or part 51, Appendix S for states to submit
SILs for PM2.5, should they choose to do so, as part of
their revisions to incorporate the final rules for PM2.5
into SIPs. Nonetheless, we believe that the availability of SILs as a
screening tool greatly improves PSD program implementation by
streamlining the permit process and reducing labor hours necessary to
submit and review a complete permit application where the projected
impact of the proposed source is de minimis in the relevant area. For
these reasons, we are including the PM2.5 SILs in the
Federal PSD regulations at 40 CFR 52.21 to screen proposed projects
concerning the need for a cumulative source impact analysis for
PM2.5.
---------------------------------------------------------------------------
\21\ We note that, under the 2007 NPRM, we proposed that the
SILs for PM2.5 would not be treated as a minimum program
element for State PSD programs; however, the proposed regulatory
language at 40 CFR 51.166(k)(2) incorrectly stated the ``the plan
shall provide that,'' which would indicate that the use of the SILs
for PM2.5 was required in the State plan. This final rule
corrects this error.
---------------------------------------------------------------------------
B. Response to Comments Concerning the SILs
The primary purpose of the SILs is to identify a level of ambient
impact that is sufficiently low relative to the NAAQS or increments
that such impact can be considered trivial or de minimis. Hence, the
EPA considers a source whose individual impact falls below a SIL to
have a de minimis impact on air quality concentrations that already
exist. Accordingly, a source that demonstrates that the projected
ambient impact of its proposed emissions increase does not exceed the
SIL for that pollutant at a location where a NAAQS or increment
violation occurs is not considered to cause or contribute to that
violation. In the same way, a source with a proposed emissions increase
of a particular pollutant that will have a significant impact at some
locations is not required to model at distances beyond the point where
the impact of its proposed emissions is below the SILs for that
pollutant. When a proposed source's impact by itself is not considered
to be ``significant,'' EPA has long maintained that any further effort
on the part of the applicant to complete a cumulative source impact
analysis involving other source impacts would only yield information of
trivial or no value with respect to the required evaluation of the
proposed source or modification.
While some commenters opposed all of the proposed options for
PM2.5 SILs, most commenters generally supported the use of a
SIL as a screening tool for PM2.5 air quality analyses.
Commenters who supported one of the proposed options for the SILs were
divided as to their support of a particular approach for selecting the
SIL value, with each option receiving some support. Commenters also
tended to agree that the SILs should not be used for determining
significant impacts on AQRVs in Class I areas.
Those commenters supporting the concept of the SILs, yet opposing
all proposed options, believed that all options yielded SILs that were
too low. Another commenter, an environmental group, presented extensive
legal and policy arguments against the SILs concept in general. Some of
the significant comments and our responses to them are addressed
herein, while others are covered in the Response to Comments document
which we have placed in the docket for this rulemaking.
1. Legal Basis for SILs
One commenter opposed all three proposed options on both legal and
policy grounds claiming that EPA has no legal authority to promulgate
SILs and that the de minimis doctrine endorsed by the court does not
apply to increment analyses, where Congress has expressly directed that
the letter of the law applies in all circumstances, as it has in this
case. (The commenter's policy concerns about SILs are discussed later
in this section of this preamble.) The commenter stated that ``Congress
codified increments in section 163 of the Act, directing that SIPs
contain measures assuring that the increments shall not be exceeded.''
According to the commenter, ``The Act plainly provides that no major
source may be constructed unless it meets this requirement, and may not
contribute to an exceedance `for any pollutant in any area.' '' The
commenter further stated that ``the de minimis doctrine is inapplicable
because it applies only where the regulations will yield a gain that is
demonstrably trivial or zero.''
We disagree with this commenter's claim that there is no legal
basis for SILs. As stated in the 2007 NPRM, the concept of a SIL is
grounded on the de minimis principles described by the court in Alabama
Power at 323, 360. In this case reviewing EPA's 1978 PSD regulations,
the court recognized that ``there is likely a basis for an implication
of de minimis authority to provide exemption when the burdens of
regulation yield a gain of trivial or no value.'' Alabama Power at 360.
See the 2007 NPRM for more on how we have applied the de minimis
principle in the past. See also, Sur Contra La Contaminacion v. EPA,
202 F.3d 443, 448-49 (1st Cir. 2000) (upholding EPA's use of SILs to
allow permit applicant to avoid full impact analysis.)
2. Levels of the SILs
Several commenters opposed all three proposed options on the
grounds that all yielded levels of SILs that are too low. One of these
commenters argued that the proposed SILs ``imply a level of monitoring
and modeling sophistication that is currently absent in our regulatory
scheme.'' This commenter recommended that EPA ``rethink the level of
the proposed SILs and select concentrations less likely to be within
the level of error inherent in current monitoring and modeling
methods.''
We disagree with these commenters' concerns about all the proposed
SILs being too low. While we did not select the Option 1 levels, the
Class II and III SILs for PM2.5 under that option were the
same ambient concentration levels that are used for the SILs for the
other criteria pollutants under 40 CFR 51.165(b), and those existing
SILs values are associated with NAAQS that are considerably higher than
the NAAQS for PM2.5. Clearly, it would have been
inappropriate to select Class II and III SILs for PM2.5 that
represent relatively higher values than the existing SIL values for
other pollutants in light of the more stringent NAAQS levels that exist
for PM2.5. We also disagree that the SILs should be
consistent with current monitoring capabilities for PM2.5.
The SILs are a screening tool used in comparison with modeled
predictions--not monitored concentrations--of PM2.5.
Monitoring accuracy is not a relevant concern in predicting with air
quality dispersion models the concentrations of a pollutant that a
source will cause if its construction and operation are allowed to
occur.
Two commenters expressed concern about national de minimis values.
One stated that ``the idea that a single national number can define
`trivial' is flawed, given that even very small impact can be of great
significance in an area that is close to an increment or NAAQS.'' The
other commenter
[[Page 64892]]
recommended that EPA ``develop geographic area-specific * * * levels
that take local conditions into account.'' This commenter reasoned that
some PSD areas ``should not be `penalized' by a single, national PSD
increment, significant impact levels and significant monitoring level,
where the conditions of concern are not capable of control.''
With regard to the first of these commenters, our longstanding
policy has been that when a source has a de minimis impact on an
existing air quality problem, that source should not necessarily be
required to bear the burden of addressing its small contribution to a
problem caused primarily by other sources. However, notwithstanding the
existence of a SIL, permitting authorities should determine when it may
be appropriate to conclude that even a de minimis impact will ``cause
or contribute'' to an air quality problem and to seek remedial action
from the proposed new source or modification.
We do not agree with the second of these comments concerning the
development of regional SILs based on a concern that some amounts of
PM2.5 in a particular area are ``not capable of control.''
The PM2.5 SILs define a threshold level for determining
whether a predicted ambient impact by a proposed major stationary
source or major modification of PM2.5 needs to undergo a
more thorough analysis of the PM2.5 NAAQS or increments.
This value is not directly affected by the total amounts of
PM2.5 that may exist in an area or by what causes the
existing PM2.5 concentrations, rather by the impact of a
single source relative to the levels of the NAAQS and increments that
must be protected. Therefore, we do not see why the SILs should be
influenced by the geographic area of concern, or how different levels
of SILs for the same pollutant and averaging period would be necessary.
With regard to the commenters that supported at least one of the
proposed SILs options, they generally did not prefer the entire suite
of SILs (Class I, II, and III SILs) from a single option, but instead
supported parts of different options, primarily divided by drawing a
distinction between the Class I SILs and the SILs for Class II and III
areas. Consistent with the way that commenters addressed the Class I,
II, and III SILs, we will address the comments separately herein as
well.
a. Class I SILs
Support and opposition for the proposed PM2.5 SILs for
Class I areas was fairly evenly divided. The PM2.5 SILs for
Class I areas proposed under Option 2 received the support of some
commenters, but also received an equal amount of opposition. Option 1,
which yielded the lowest (most restrictive) values for the Class I area
SILs for PM2.5 (annual and 24-hour averages), was supported
by some commenters, including a Federal agency that serves as a FLM for
Federal Class I areas under the PSD program, but was equally opposed.
Finally, comments supporting the Class I SILs proposed under Option 3
(from which we derived the values included in the final rules) were
matched by comments that opposed the Class I SILs under Option 3.
One commenter opposing the Option 3 SILs for Class I areas said
that the values ``appear to be unrealistically low and, if selected,
would point to the need for EPA to conduct an economic impact
analysis.'' We disagree that adopting the Option 3 SILs for Class I
areas (and Class II and III areas) will result in economic impacts
significant enough to warrant an economic impact analysis. Under the
Paperwork Reduction Act, EPA is required to analyze, and receive
approval from the Office of Management and Budget (OMB) for, the
recordkeeping and reporting burden imposed by its regulations (referred
to as the ``Information Collection Request'' or ``ICR'' for the
regulation). For the PSD program, this includes the burden associated
with the entire permitting process, including any required modeling
analyses. In our analysis for this rulemaking, we have concluded that
the number of PSD permits issued annually will be unchanged (at an
estimated 274 per year), while the total burden across all PSD permit
applicants of adding PM2.5 analyses will increase by a total
of approximately 29,000 hours per year at a cost of approximately $2.8
million per year. This total annual impact on industry is a small
fraction of the threshold ($100 million per year) that is considered
``significant'' under Executive Order 12866 (Regulatory Planning and
Review) and the Unfunded Mandates Reform Act. See sections X.B and X.D
of this preamble for more on the Paperwork Reduction Act and the
Unfunded Mandates Reform Act, respectively. Our analysis of the
recordkeeping and reporting burden of this rulemaking can be found in
the docket for this ICR.\22\
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\22\ See ``Information Collection Request (ICR) for the
Prevention of Significant Deterioration for PM2.5-
Increments, Significant Impact Levels and Significant Monitoring
Concentration,'' Docket No. EPA-HQ-OAR-2007-0628.
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Another commenter stated that the use of a NAAQS-based ratio under
Option 3 for the proposed SILs does not ``translate back to the
emissions point level when comparing PM10 and
PM2.5.'' This commenter continued, ``this is an invalid
method of proceeding because EPA has not shown that there is a
correlation between the NAAQS and direct PM2.5 since there
is no accounting for precursors and EPA does not have a quantifiable
sense of the portion of PM2.5 that is condensable for
various industries.''
We disagree with the commenter's concern that the use of NAAQS-
based ratios is an invalid method for developing the PM2.5
SILs. The purpose of using the NAAQS ratio with the PM10
SILs to develop PM2.5 SILs is to establish values that have
a comparable relationship between ambient concentrations of
PM10 and PM2.5 and their respective NAAQS levels.
Whether a particular ambient concentration of PM2.5 results
from direct PM2.5 emissions or from precursor emissions is
not relevant to this particular approach. The PM2.5 SILs in
this final rule are intended to be compared to the ambient
concentrations of PM2.5 that are predicted by modeling the
emissions of a proposed new project. Ambient concentrations of
PM2.5 can be the result of direct PM2.5
emissions, which may include condensable particulate matter, as well as
precursor emissions, e.g., SO2 and NOX.
We note that the 2007 NPRM included proposed regulatory language
providing that demonstrations of whether the air quality impact of a
major new source or modification would be less than the
PM2.5 SILs be based on direct PM2.5 emissions
from the proposed project. The intent of this was to recognize the
technical limitations associated with modeling precursor emissions to
predict ambient PM2.5 impacts. However, in this final rule
we have removed that limitation by removing the reference to ``direct''
PM2.5 emissions.
One commenter, who did not support any of the proposed SILs
options, was especially critical of the Class I SILs for
PM2.5 under Option 1, stating that multiplying the proposed
PM2.5 increment by 4 percent is without legal or practical
merit. The commenter stated that just because ``4 percent may have been
a reasonable multiplier to use in establishing a significant emission
rate threshold does not mean that the multiplier should be used for a
completely different regulatory purpose.'' The commenter added that if
the PM2.5 SILs for Class I areas under Option 1 were
codified, emissions from even the most well-controlled coal-fired
electric generating station located as far away as 300 km from a Class
I area could well exceed the threshold.
[[Page 64893]]
In contrast, the Federal agency commenter supporting the
PM2.5 SILs for Class I areas under Option 1 explained that
they analyzed the effectiveness of the three sets of proposed SILs by
modeling four different coal-fired power plant scenarios using an EPA-
approved long-range transport model. The modeled plants included a
large 1,500 megawatt (MW) facility, a moderate-sized 500 MW facility,
and two medium 800 MW facilities. Based on this modeling analysis, the
commenter concluded that the proposed levels of the Class I 24-hour
SILs based on Option 1 and Option 3 are ``more appropriately protective
of the proposed Class I PM2.5 increment and impacts to
visibility than the level obtained under Option 2.'' This commenter
supported the consistency of using 4 percent of the Class I increments
that was used by EPA in proposing Class I SILs for SO2,
NOX, and PM10 in 1996.
We chose the Class I SILs under Option 3 because we believe that
this option yields the most appropriate combination of SILs for all
area classifications. Whether a particular source will have a
significant impact on an area is determined to some extent by the
amount of its emissions, but also by other factors such as the height
of release, pollutant transport distance, terrain features, and
meteorological factors. Thus, we did not select SILs values to address
a certain size source or the degree of control of that source, but the
ambient impact of that source relative to the NAAQS and increments that
will result from the source's emissions. While the annual Class I SIL
under Option 3 represents a level that is somewhat greater than 4
percent of the PM2.5 annual increment for Class I areas, it
is sufficiently close (as derived from a ratio of the PM2.5
NAAQS to the PM10 NAAQS) so as to provide a reasonable
threshold for defining de minimis for purposes of conducting a Class I
increment analysis. We had proposed the use of 4 percent of the
existing Class I increments to develop SILs for pollutants in the 1996
NSR Reform proposal; however, that particular component of the proposal
was never finalized. See 61 FR 38250 beginning at 38291. We will
further discuss our rationale for selecting the SILs under Option 3 in
the discussion which follows for the Class II and III SILs.
b. Class II and III SILs
While many commenters tended to favor Option 2 with regard to the
proposed Class I increments, they tended clearly to support Option 1
for defining Class II and III SILs for PM2.5. These
particular SILs for PM2.5 were proposed so as to be equal to
the existing Class II and III SILs for the existing pollutants. In all,
six commenters supported Option 1. One of these commenters stated that
Option 1 SILs for Class II and III areas are ``sufficiently stringent
and fully consistent with the de minimis justification for SILs.'' The
commenter added that ``when conducting an air quality impact analysis *
* * most applicants assume all coarse PM10 to be
PM2.5.'' The commenter claimed that this assumption is
conservative and ``overestimates the amount of fine particles being
emitted and renders the effective SIL thresholds for PM2.5
lower than those written into the regulations.''
We strongly disagree that the SILs proposed under Option 1 as
applied to PM2.5 are sufficiently stringent. The application
of such values as SILs for PM2.5 would result in ambient
concentrations of PM2.5 that consume a much larger portion
of both the PM2.5 NAAQS and increments than either of the
other two options proposed for PM2.5 in light of the
correspondingly more stringent levels of the PM2.5 NAAQS and
increments than those for the other pollutants. We believe that of the
3 options proposed, the PM2.5 SILs based on Option 3
represent values that are more closely aligned percentage-wise with the
SILs that have been or are being used for other forms of PM when
compared to their respective NAAQS and increments.
We also disagree with the commenter's suggestion that the
development of the SILs for PM2.5, or any other pollutant,
should in any way be influenced by the possibility that some sources
may use conservative techniques for estimating a source's emissions
rate. Such conservative techniques may be needed to the extent that
technical issues associated with the determination of PM2.5
emissions are identified, and can certainly be used at any time as a
simplified methodology for estimating PM2.5 emissions. But
when such an overly conservative approach fails to yield de minimis
results, the source may find it necessary to rely upon more accurate
techniques for determining the amount of PM2.5 that the
source will emit.
Finally, one commenter, objecting to all of the proposed SILs,
stated that EPA must assure that SILs are truly de minimis and must
also include limitations on the use of SILs as necessary to prevent air
quality from significantly deteriorating. We acknowledge that we did
not conduct any new modeling or other types of analyses of the proposed
SILs in order to explicitly show that the final PM2.5 SILs
values in this final rule are de minimis. Instead, we have relied on
past actions regarding the setting of de minimis levels to illustrate
that the PM2.5 values selected via Option 3 represent values
that are as stringent as the previous levels that have been established
to define de minimis for PM10 and TSP. See 45 FR 52706-708
(using modeling and representative data).
Using the 24-hour and annual NAAQS ratios of PM2.5 to
PM10, and multiplying them by the corresponding existing
PM10 SILs, we conclude that the PM2.5 SILs define
de minimis for the PM2.5 NAAQS in the same way as the
PM10 SILs do for PM10 NAAQS. Using the increments
as a basis for comparison provides further support for our conclusion.
The annual and 24-hour PM2.5 SILs represent about 7.5 and 13
percent of the annual and 24-hour PM2.5 increments,
respectively. By comparison, the annual and 24-hour PM10
SILs represent about 5 and 17 percent of the annual and 24-hour
PM10 increments, respectively. We believe the
PM2.5 SILs fall into a comparable relative range with the
PM10 SILs and can be considered de minimis.
In EPA's 1980 final rule for PSD, EPA adopted SERs for the
pollutants then subject to regulation under the PSD requirements. The
SER adopted for PM (then measured as TSP) was 25 tpy, which represented
an emissions rate for which EPA modeled impacts that represented about
4 percent of the TSP 24-hour NAAQS and about 28 percent of the 24-hour
TSP increment. Thus, EPA considered it acceptable under the de minimis
assessment for PM that a source of particulate matter capable of
consuming around 28 percent of the applicable 24-hour TSP increment
could be exempted from the requirements to complete a comprehensive
source impact analysis for the PM NAAQS and increments. 45 FR 52708.
In looking at the amount of increment that could be consumed by a
source that is ultimately exempted from having to complete a
comprehensive modeling analysis, it should be pointed out that the
maximum modeled concentration typically occurs in a relatively limited
area, as compared to the entire modeling domain. In particular, for the
short-term averaging periods, such as the 24-hour averaging period,
modeled concentrations across the modeled area generally show that
ground level impacts are reduced significantly from the peak value as
the pollutant travels a relatively short distance from the source, so
that the peak modeled
[[Page 64894]]
concentrations represent the source's impact at only a relatively few
receptors within the modeled area. In addition, it is important to note
that the temporal and spatial conditions which lead to a maximum impact
by one source are seldom the same for other sources, such that maximum
impacts of individual sources do not typically occur at the same
location or at the same time.
Thus, in an area where several sources can demonstrate that their
modeled impacts are de minimis, it generally should not be assumed that
their individual maximum (albeit de minimis) impacts on the increment
are additive. For example, four sources with de minimis
PM2.5 impacts, each consuming 12 percent of the 24-hour
PM2.5 increment, would not necessarily consume 48% of the
24-hour increment. Increment consumption is determined by the
cumulative impact of source emissions on each individual receptor or
modeling point in the area of impact within the baseline area defined
for the affected PSD sources.
The preamble for the 1980 final rule for PSD included a description
of a modeling analysis that EPA conducted to illustrate that a number
of major sources each making a de minimis emissions increase for
SO2 could locate in an area (in that case, the Dayton area)
and not cause a violation of either the applicable SO2
increment or NAAQS. In that particular case, the modeling indicated
that the maximum aggregate increment consumption for 37 sources
emitting 40 tpy of SO2 (the de minimis emissions rate for
SO2) would have a cumulative impact at any location of less
than 1.5 [mu]g/m\3\ on a 24-hour basis--well below the NAAQS and
increments for SO2. 45 FR 52708.
With regard to the commenter's recommendation that we place
limitations on the use of SILs, we earlier provided an example of when
it might be appropriate to require a modified source to mitigate its
contribution to a violation of a NAAQS or increment even when the
predicted ambient impact of the proposed emissions increase would
result in what is normally considered to be de minimis. In addition, we
have historically cautioned states that the use of a SIL may not be
appropriate when a substantial portion of any NAAQS or increment is
known to be consumed. We have indicated elsewhere in this preamble that
states are not required to adopt the SILs for PM2.5 in this
final rule. At their discretion they may choose not to rely on SILs to
screen applicants or they may establish more stringent values.
Finally, it should be noted that while a source having only de
minimis impacts may not be required to complete a comprehensive source
impact analysis, the emissions from such sources are still considered
to consume increment and would be counted as part of the next increment
analysis required to be completed by a PSD applicant in that same area,
or by the State under a periodic increment review.
3. Relationship Between SILs and AQRVs
While commenters generally supported EPA's position that the SILs
should not be used in any way to determine effects of emissions
increases on the AQRVs in a Class I area, two commenters urged that the
de minimis concentration be used for analyzing Class I area impacts
under certain circumstances. That is, they believed that the SILs
should be used to determine the need for a Class I area air quality
analysis when an FLM has not identified a specific AQRV related to the
pollutant under evaluation or obtained ambient monitoring data to
confirm that predicted concentrations from air dispersion models are
representative of actual AQRV impacts in the Class I area. The
commenters claimed that without this flexibility, applicants would be
required to conduct complex and extensive Class I air dispersion
modeling without any clear objective, and regulatory agencies would
have to review the modeling with limited information to determine if
the emissions could cause an ``adverse'' impact or if potentially
costly controls should be required.
These commenters appear to be suggesting that an FLM may needlessly
call for an analysis of a particular Class I area, involving ``complex
and extensive Class I area dispersion modeling'' despite the fact that
no AQRV has been identified for that Class I area. We agree that a
Class I analysis in the absence of any known AQRVs would be unnecessary
because any demonstration of an adverse impact must be made with
respect to a pollutant adversely affecting an AQRV. We believe,
however, that such analyses would be avoided under the procedures set
forth in section 165(d)(2)(C) of the Act which require that a notice be
filed alleging that a proposed source may cause or contribute to
adverse effects, and identifying the adverse impact. Insofar as the FLM
must also demonstrate ``to the satisfaction of the State that emissions
from such facility will have an adverse impact on the air quality
related values,'' it would be difficult to require the source to
undertake any kind of detailed analysis in the absence of an AQRV on
which such adverse impacts must be demonstrated. Thus, we have
concluded that it is not necessary to use the SILs as a safeguard
against unnecessary Class I area analyses. Instead, we believe that the
need for a Class I analysis, other than the required analysis of the
NAAQS and Class I increments (for both of which the SILs are intended
to be used), should be based on the potential for adverse effects on an
AQRV that the FLM has identified and believes could be affected by a
pollutant that would be emitted by the proposed project.
4. Form of the SILs
One commenter stated that ``the Proposal does not indicate how the
proposed PM2.5 SILs are to be interpreted.'' This commenter
believed that ``the form of the SILs should be consistent with the form
of the PM2.5 NAAQS'' adding that ``the current
PM2.5 NAAQS requires that compliance with the 24-hour and
annual standards be determined using 3-year averaging.'' Specifically,
``The annual standard is calculated based upon the 3-year average of
annual mean PM2.5 concentrations, and the 24-hour standard
is based on the 3-year average of the 98th percentile (or highest-8th
high value) of 24-hour concentrations.''
In a March 23, 2010 EPA memorandum titled ``Modeling Procedures for
Demonstrating Compliance with PM2.5 NAAQS,'' we provided
guidance for using the SILs in conjunction with the 24-hour and annual
PM2.5 NAAQS, which takes into account the statistical form
of the NAAQS. Following promulgation of the PM2.5 increments
in this final rule, we intend to provide guidance for interpreting the
SILs for their use with the 24-hour and annual PM2.5
increments as well.
5. SILs for Other Pollutants
In proposing Option 1, we noted that many who commented on the 1996
NSR Reform proposal supported this approach and believed that the
proposed PM10 SIL values would serve as appropriate de
minimis values. In fact, we are aware that many states have been using
these proposed SILs for PM10 as screening tools since 1996
or earlier.
Regarding the proposed Class I SILs under Option 1, we expressed
our belief that where a proposed source consumes less than 4 percent of
the Class I increment, the source's impact is sufficiently low so as
not to warrant requiring the source to carry out a detailed analysis of
the combined effects of the proposed source and all other increment-
consuming emissions in the
[[Page 64895]]
area. 72 FR 54140. We previously used a similar rationale to establish
the SERs for PSD applicability purposes, concluding in part that
emissions rates that resulted in ambient impacts less than 4 percent of
the 24-hour standards for PM and SO2 were sufficiently small
so as to be considered de minimis. 45 FR 52707-8.
The original SIL values of 1.0 and 5.0 [mu]g/m\3\ for TSP and
PM10 were interpreted by EPA as representing the minimum
amount of ambient impact that is significant. This formed the basis for
the proposed Option 1 PM2.5 SIL values of 1.0 and 5.0 [mu]g/
m\3\ for the annual and 24-hour averaging periods for Class II and III
areas.
The SILs currently appear in EPA's regulations at 40 CFR 51.165(b).
That particular NSR regulation provides that states must include a
preconstruction review permit program for any new major stationary
source or major modification that proposes to locate in an attainment
or unclassifiable area and would cause or contribute to a violation of
the NAAQS. These values, added to 40 CFR 51.165(b) on July 1, 1987,
have previously been referred to as ``significant ambient impact
concentrations'' and are used to enable a source to determine whether
its emissions would cause or contribute to a NAAQS violation at ``any
locality that does not or would not meet the applicable national
standard.'' 52 FR 24672, April 2, 1985, at 24688.
In 1985, when EPA proposed to add ``significant ambient impact
levels'' for PM10, we also indicated that for PSD purposes
the requirements under section 51.165(b) \23\ ``would be applied to all
applicable PSD requirements.'' The EPA has since applied these values
in other analogous circumstances under the PSD program. Based on EPA
interpretations and guidance, SILs have also been widely used in the
PSD program as a screening tool for determining when a new major source
or major modification that wishes to locate in an attainment or
unclassifiable area must conduct a more extensive air quality analysis
to demonstrate that it will not cause or contribute to a violation of
the NAAQS or PSD increment in the attainment or unclassifiable area.
The SILs are also used to define the extent of the Significant Impact
Area where, using air dispersion models and ambient monitoring data, a
cumulative source impact analysis accounting for emissions changes from
affected sources is performed.\24\ See the 2007 NPRM for additional
information on the history of EPA's guidance related to SILs (72 FR
54138-39).
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\23\ In 1985, the requirements now contained in 40 CFR 51.165(b)
were contained in 40 CFR 51.18(k), which was later part of a major
restructuring of the part 51 SIP requirements.
\24\ In the case of a NAAQS compliance analysis, all sources in
the area are considered to contribute to the air quality levels; for
increments, however, ``all'' refers only to those sources whose
emissions, in whole or in part, consume PSD increment for a
particular pollutant.
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In the 1996 NSR Reform proposal, we proposed to add the SILs for
PM10 and other pollutants already contained in 40 CFR
51.165(b)(2) directly into the PSD regulations at 40 CFR 51.166 and
52.21. Because the SILs in 40 CFR 51.165(b) did not include thresholds
for Class I areas, we proposed to set Class I SILs at the level of 4
percent of the respective Class I increments. Thus, for
PM10, the proposed Class I SILs were 0.2 [mu]g/m\3\ (annual)
and 0.3 [mu]g/m\3\ (24-hour), and the proposed Class II and III SILs
were 1.0 [micro]g/m\3\ (annual) and 5.0 [mu]g/m\3\ (24-hour). The EPA
has not yet taken final action on the 1996 proposal on SILs for
pollutants other than PM2.5; therefore, we rely upon our
longstanding policy to use those values, as codified in 40 CFR
51.165(b)(2), for PSD permitting.
VII. Final Action on the PM2.5 SMC
A. EPA's Determination on the PM2.5 SMC
As with the increments and SILs for PM2.5, we proposed
three different options for establishing an SMC for PM2.5.
The first option, referred to as the ``lowest detectable
concentration'' approach, relied on the method we used in 1980 to
develop the SMCs for the pollutants then subject to PSD. This
particular method focused on development of the SMC value based on the
current capability of providing a meaningful measure of the pollutants.
See relevant discussion later in this section and at 45 FR 52710.
Options 2 and 3, called the ``PM2.5 to PM10
emissions ratio'' and the ``PM2.5 to PM10 NAAQS
ratio,'' respectively, used the SMC for PM10 as the base for
multiplying the emissions and NAAQS ratios to derive an SMC for
PM2.5. See 72 FR 54141. The three proposed options yielded
the following numerical levels for the SMC:
Option 1: 10 [mu]g/m\3\, (24-hour average);
Option 2: 8.0 [mu]g/m\3\ (24-hour average); and
Option 3: 2.3 [mu]g/m\3\ (24-hour average).
We are taking final action on the SMC for PM2.5 using
the ``lowest detectable concentration'' approach (Option 1). However,
we have determined that the SMC value that is calculated under this
methodology is lower than the proposed value of 10 [micro]g/m\3\ to
reflect ``current capability'' with respect to the measurement and
collection of ambient PM2.5 concentrations. The result of
such revised calculation is that the SMC value in this final rule is
different from (more stringent than) the proposed level. The revised
value is 4 [micro]g/m\3\ (24-hour average). Our basis for the revised
calculation and the resulting lower value is described in greater
detail later in this section.
The EPA and its delegated reviewing authorities will use the
PM2.5 SMC to determine when it may be appropriate to exempt
a proposed new major stationary source or major modification from the
ambient monitoring data requirements under the PSD rules. Similarly,
states with EPA-approved PSD programs that adopt the SMC for
PM2.5 may use the SMC, once it is part of an approved SIP,
to determine when it may be appropriate to exempt a particular major
stationary source or major modification from the monitoring
requirements under their State PSD programs (see 40 CFR 51.166(i)(5)).
B. Response to Comments Concerning the SMC
1. Legal Issues
Under the Act and EPA regulations, an applicant for a PSD permit is
required to gather preconstruction monitoring data in certain
circumstances. Section 165(a)(7) of the Act calls for ``such monitoring
as may be necessary to determine the effect which emissions from any
such facility may have, or is having, on air quality in any areas which
may be affected by emissions from such source.'' In addition, section
165(e) of the Act requires an analysis of the air quality in areas
affected by a proposed major facility or major modification and calls
for gathering 1 year of monitoring data unless the reviewing authority
determines that a complete and adequate analysis may be accomplished in
a shorter period. These requirements are codified in EPA's PSD
regulations at 40 CFR 51.166(m) and 52.21(m).
In 1980, EPA adopted regulations that included pollutant-specific
SMCs as a screening tool for sources to determine whether they should
conduct site-specific preconstruction ambient monitoring.\25\ We
explained our
[[Page 64896]]
position that it was appropriate to exempt sources from preconstruction
monitoring requirements for a pollutant if the source could demonstrate
that its ambient air impact was less than a value known as the
Significant Monitoring Concentration or SMC. At the time the SMCs were
adopted, EPA described them as ``air quality concentration de minimis
level[s] for each pollutant [that were available] for the purpose of
providing a possible exemption from monitoring requirements.'' 45 FR
52676, 52707 (August 7, 1980). The EPA explained that it believed there
was ``little to be gained from preconstruction monitoring'' where a
source could show that its projected impact of a pollutant within the
affected area was below the de minimis concentration for that
pollutant. 45 FR at 52710.
---------------------------------------------------------------------------
\25\ The provision for the monitoring exemption was originally
promulgated at 40 CFR 51.24(i)(8) and 52.21(i)(8); it should be
noted, however, that this provision is now found at 40 CFR
51.166(i)(5) and 52.21(i)(5).
---------------------------------------------------------------------------
One commenter opposed our proposed establishment of any SMC for
PM2.5, claiming that SMCs in general are contrary to the
Act. The commenter stated that ``in Section 165(e) Congress mandated a
full year of continuous air quality monitoring for each major source
subject to the PSD program.'' With this in mind, the commenter
indicated that there are no exceptions, other than the limited
statutory provisions, discussed above, which allow for less than a
year's worth of monitoring based on a determination that a complete and
adequate analysis of such purposes may be accomplished in a shorter
period. The commenter then argued that ``the allowance for a `shorter
period' hardly amounts to authority to waive monitoring entirely, which
is what EPA's SMC proposal would do.''
As with the SMCs adopted by EPA in 1980, the SMCs that we proposed
for PM2.5 are supported by the de minimis doctrine set forth
in the Alabama Power opinion. Like the other pollutants for which EPA
has promulgated SMCs, EPA believes there is little to be gained from
preconstruction monitoring of PM2.5 concentrations that
cannot be accurately measured.
Therefore, in developing the three proposed options for an SMC, EPA
sought to use methods that would identify levels representing a de
minimis or insignificant impact on PM2.5 ambient air quality
that makes the collection of additional monitoring data extraneous.
2. Level of the SMC
As indicated earlier, the SMC for PM2.5 in this final
rule is 4 [mu]g/m\3\, 24-hour average. This value may be used by
permitting authorities to determine when they may exempt a proposed
major stationary source or major modification for PM2.5 from
the air quality monitoring requirements for PM2.5 under 40
CFR 51.166. The EPA and its delegated State/local programs will also
use this new value under the Federal PSD program at 40 CFR 52.21.
We proposed three options for developing the SMC for
PM2.5; each option yielded a different concentration value.
In choosing between the three options, EPA proposed to select the
option that reflected the degree of ambient impact on PM2.5
concentrations that could be considered truly de minimis and used to
justify exempting a source from the requirement to gather 1 year of
ambient monitoring data for PM2.5. Ultimately, we have
selected the ``lowest detectable concentration'' approach (Option 1)
that relies directly upon ambient monitoring measurement sensitivity
and precision. That is, if either the predicted source impact or
estimated existing air quality in an area is below a concentration that
can be accurately measured, then it would not be reasonable to require
a source to attempt to collect such ambient data.
In 1980, EPA determined the SMCs based on the then current
capability of providing a meaningful measure of ambient pollutant
concentrations. The EPA promulgated values that represented five times
the lowest detectable concentration in ambient air that could be
measured by the instruments available for monitoring the pollutants. 45
FR 52710. The factor of ``five'' took into account the measurement
errors associated with the monitoring of these low pollutant levels or
small incremental changes in concentration. These measurement errors
were said to arise from various sources, such as sample collection,
analytical measurement, calibration, and interferences. See May 20,
1980 EPA memorandum from Rehme, K. A., to Warren Peters, contained in
the docket for this rulemaking. Accordingly, in the 2007 NPRM for
PM2.5, we voiced our belief that this was a reasonable
approach, since it was also used for PM10 and TSP. 72 FR
54141.
Eight commenters expressed support for the SMC based on Option 1,
albeit at the higher level as originally proposed. In some cases, it is
not clear whether these commenters supported the particular approach
(i.e., an SMC linked to the lowest detectable level) or the fact that
the calculated value was simply the highest value of the values
proposed under the three options. Clearly, some of the commenters
indicated their support for the approach because it is consistent with
the approach used for setting the original SMCs in 1980. Two commenters
opposed Option 1 because it resulted in an SMC value that was too high.
These latter commenters noted that the SMC derived via Option 1 (10
[micro]g/m\3\, 24-hour average) was greater than the proposed 24-hour
PM2.5 increment for Class II areas and argued that such an
outcome is inappropriate. We believe that this important concern is
adequately addressed by the level of the SMC for PM2.5 that
is established in this rulemaking.
Several commenters supported the levels derived from either Option
2 or Option 3, but were concerned that the justification for choosing
either of these values would need to be further explained. Some of
these commenters were specifically concerned about the use of a 0.8
PM2.5-to-PM10 emissions ratio which, they argued,
relied on inventory data that did not adequately address all sources
that would likely affect ambient concentrations of PM2.5 in
an area.
We conclude that Option 1 is the appropriate option for defining
the SMC for PM2.5. The ability to accurately measure ambient
PM2.5 concentrations is not related to a ratio of
PM2.5 to PM10 either directly in terms of
emissions or as expressed by the respective NAAQS, which were used to
define the SMC for PM2.5 under Options 2 and 3,
respectively. Our original concern was that, while Option 1 linked the
SMC directly to the concept of a minimum detectable concentration (in
order to identify de minimis monitoring circumstances), the value
originally derived from that approach in the 2007 NPRM was high in
relationship to the concentrations of PM2.5 defined by the
existing NAAQS and increments for PM2.5.
In considering the use of Option 1 for developing the SMC in the
final rules, however, we recognized after publication of the proposed
rule that it was necessary to re-examine the assumptions that we relied
upon in 1980 to develop the numerical values for the original SMCs so
that we could most accurately reflect current monitoring techniques for
PM2.5. Our re-examination for this final rule utilized the
most current information concerning the physical capabilities of the
PM2.5 Federal Reference Method Samplers, and addresses
uncertainties introduced to the measurement of PM2.5 due to
variability in the mechanical performance of the PM2.5
samplers and the micro-gravimetric analytical balances that weigh
filter samples.
The minimum detection limit (MDL) of 2 [micro]g/m\3\, originally
used in 1980 for the SMC for PM and promulgated for PM2.5 in
1997 (see 40 CFR part 50, Appendix L, section 3.1), has been
[[Page 64897]]
reaffirmed by 9 years of field blank data collected by EPA through the
PM2.5 Performance Evaluation Program. However, we found that
new data exist to ``indicate a conservative estimate of the aggregate
uncertainty factor is no greater that `2' at the concentration equal to
the MDL of 2 [micro]g/m\3\.'' \26\ Accordingly, the lowering of the
uncertainty factor from ``five'' to ``two'' under Option 1 yields an
SMC of 4 [micro]g/m\3\ PM2.5, 24-hour average, rather than
the proposed concentration of 10 [micro]g/m\3\.
---------------------------------------------------------------------------
\26\ This information is contained in a March 12, 2009 internal
EPA memorandum from Dennis Crumpler to Raj Rao, titled ``PSD
Monitoring De Minimis Concentration for PM2.5,'' which
has been placed in the docket for this rulemaking.
---------------------------------------------------------------------------
We conclude that the modified level of 4 [micro]g/m\3\
PM2.5, 24-hour average, for the SMC under Option 1, based
upon a more current understanding of monitoring precision for PM,
especially fine PM, addresses commenter support for the use of a method
that is consistent with the way other SMCs were developed and most
directly reflects monitoring capability for the pollutant of concern,
while at the same time responding to the concern of other commenters
that a value in the lower range of proposed SMC values is most
reasonable considering the levels of the NAAQS and increments for
PM2.5.
C. Correction of Cross Reference in PSD Ambient Monitoring Requirements
In the 2007 NPRM, we proposed to take final action to correct a
cross reference contained in paragraph (i) of the part 51 and 52 PSD
regulations. Specifically, at the time of the proposal, paragraphs (ii)
and (iii) in 40 CFR 51.166(i)(5), and paragraph (ii) in 40 CFR
52.21(i)(5), each referred to concentrations listed in paragraph
(i)(8)(i) of both regulations. However, there is no paragraph (i)(8)(i)
in existing 40 CFR 51.166, and no concentration values are contained in
existing section (i)(8)(i) of 40 CFR 52.21. The cross reference in
these provisions was intended to reference the SMCs in paragraph
(i)(5)(i) of the two PSD regulations, but EPA failed to make this
change when the paragraphs were renumbered in an earlier rulemaking. We
did not receive any comments concerning this proposed corrective
action. We made the necessary correction as part of the May 16, 2008
final PM2.5 NSR Implementation Rule (see 73 FR 28348 and
28349); therefore it is not necessary to take any further action in
this final rule with regard to the proposed correction.
VIII. Dates Associated With Implementation of the Final Rule
This section describes the key dates that we have established for
implementing the final rule. In the 2007 NPRM, we indicated that
different dates appeared to be appropriate for implementing the
PM2.5 increments, each date depending on the legal authority
that we relied upon to promulgate it. We described and took comment on
some alternative effective dates for increments, as well. In addition,
we discussed and took comment on potential implementation dates for the
SILs and SMC components of the proposed rule, which we indicated were
not subject to the same statutory considerations as the increments.
We received a number of comments on the different proposed dates.
We carefully considered these comments in selecting the dates described
below for the final rule. Some of the significant comments and our
responses to those comments are provided below. The remaining comments
and our responses are contained in the Response to Comments document
included in the docket for this rulemaking.
A. Effective Date of the Final Rule
In the 2007 NPRM, we took comment on the effective date of the
final rule by presenting the different options available for
implementing the PM2.5 increments. Under Option 1 for
developing the increments, we stated that section 166(b) of the Act
specifies that increments promulgated pursuant to section 166(a) are to
become effective 1 year following their promulgation. In contrast,
there is no such 1-year delay or any other date prescribed for
increments promulgated in accordance with section 166(f) of the Act,
upon which we based Options 2 and 3 for the annual PM2.5
increments. Thus, increments promulgated under Option 1, which relies
on the procedural provisions of section 166(b) of the Act, would
normally be subject to a 1-year delay in implementation, while
increments promulgated under either Option 2 or 3, relying on section
166(f) of the Act, could follow a 30- or 60-day effective date, typical
of the effective date for most new rules in general. In either case,
our consideration of the effective date for the PM2.5
increments assumed that the selected date would also be the effective
date of the final rule.
In the 2007 NPRM, we took comment on some alternative approaches to
establishing the effective date for PM2.5 increments.
Specifically, while proposing a 1-year effective date under Option 1,
we requested comment on whether we could promulgate these increments
under section 166(a) of the Act with an effective date of only 60 days.
See 72 FR 54142.
Nine commenters supported our proposal to establish the effective
date of the part 51 and 52 PSD regulations for PM2.5 as 1
year from the date of publication. Alternatively, two commenters
encouraged us to apply the 60-day effective date, while three other
commenters supported other effective dates, as described in this
section.
Seven industry and industry association commenters supported our
proposal to make the final rule for PM2.5 increments
effective 1 year after promulgation. Most of these commenters cited the
additional time necessary to develop the needed PM2.5
inventories needed for implementation of the PM2.5 PSD
program. Two of the commenters urged EPA to allow State programs
sufficient time to adopt increments, particularly if condensable
particulate matter is included in the increment and its analysis. These
commenters stated that the Federal rule should not be effective for 1
year. (They also stated that states should have 3 years for the
associated SIP revisions.) These same commenters added that this delay
would provide time for sources that have permits in the pipeline or are
just about to submit an application to be able to complete the
permitting process without undue delay. One of the commenters
specifically voiced support for Option 1 for the effective date of the
final rule (1 year) and Option 2B for the period granted for SIP
revisions (3 years). This commenter also explained that this additional
time may give the Agency time to promulgate better measurement methods
for sources of condensable particulate matter.
Another of these commenters noted that, at the time of the
proposal, the NSR portion of the CAFPIR had not yet been promulgated,
and that states would need time to incorporate that rule as well as the
requirements of the proposal into their SIPs. This commenter added that
making the PM2.5 increments effective before states and
sources have had a reasonable opportunity to begin, let alone complete,
the SIP process for the two related rulemakings would unnecessarily
complicate an already-complex regulatory process.
In contrast, the two commenters supporting the shorter effective
date encouraged us to apply the 60-day period for the effective date
under whatever option is finalized. One of these commenters urged us to
take measures to expedite the
[[Page 64898]]
implementation of the PM2.5 final rule and suggested that we
choose the shortest of the proposed effective dates which are allowed
under any of the applicable regulations. This commenter indicated that
in light of the excessive delay in the implementation of the
PM2.5 PSD program since the NAAQS were promulgated, the 60-
day effective date should be applied under EPA's preferred option.
In light of our decision to promulgate PM2.5 increments
under the authority of section 166(a) of the Act (proposed Option 1),
we are faced with the decision as to how to most effectively implement
the long-awaited PM2.5 increments, recognizing that the Act
provides for a 1-year implementation delay. We have concluded that it
is most appropriate to follow the plain language of the Act which calls
for a 1-year effective date for implementing increments developed under
section 166(a) of the Act. We agree with the commenters who suggested
that a shortened implementation delay was desirable because of the
substantial delay in the promulgation of measures to prevent
significant air quality deterioration with respect to PM2.5.
Nevertheless, we believe it would be inappropriate in this action to
disregard the statutory language which plainly calls for a 1-year
delay. Accordingly, we are setting the effective date of the
PM2.5 increments at 1 year from the date of promulgation of
this final rule, consistent with the 1-year delay required under
section 166(b) of the Act. We are doing this by setting the ``trigger
date'' for PM2.5 as October 20, 2011. See new 40 CFR
51.166(b)(14)(i)(c) and (ii)(c), and new 40 CFR 52.21(b)(14)(i)(c) and
(ii)(c). At the same time, we are establishing an effective date for
the other provisions, i.e., the SILs and SMC for PM2.5, in
this final rule as December 20, 2010. This will enable the
implementation of these key elements of this rule under the Federal PSD
program as soon as possible.
1. State PSD Programs
In this final rule, we are establishing the final PM2.5
increments as minimum program elements for all State PSD programs.
Accordingly, states must submit for EPA's approval revised SIPs that
incorporate the final PM2.5 increments or alternative
measures that can be demonstrated to EPA's satisfaction to provide an
equivalent level of protection as the PM2.5 increments. In
accordance with section 166(b) of the Act, we are requiring states to
submit revised implementation plans to EPA for approval within 21
months of promulgation, that is, by July 20, 2012. Section 166(b) also
specifies that we must approve or disapprove these revisions within 25
months of promulgation (4 months from the statutory deadline for SIP
submittal). We regard these statutory deadlines as maximum allowed
timeframes for action. Moreover, we do not believe that the Act
restricts our ability to approve SIP revisions requested by a State at
any time before these deadlines. In this final rule, we are amending
the regulatory provisions at 40 CFR 51.166(a)(6)(i) to articulate the
deadline set forth by the statute for the SIP submittals involving the
PM2.5 increments pursuant to section 166(a) of the Act.
It is very unlikely that states will be able to revise their SIPs
and submit them to EPA for approval prior to the applicability date of
the PM2.5 increments in this final rule, which is October
20, 2011. Therefore, there is likely to be a period of time after
October 20, 2010 when State laws will not require PSD applicants
otherwise subject to PSD for PM2.5 to complete an increment
analysis for the PM2.5 increments, even though the
PM2.5 increments, major source baseline date, and trigger
date have been established as a result of this final rule. Similarly,
it is not clear whether states will have the authority to consider such
applicants as having triggered the minor source baseline date during
this interim period before their revised PSD rules containing the
PM2.5 increments and relevant baseline dates become
effective.
The EPA does not intend to prescribe the implementation timeline
for State programs; rather, each State will need to determine how
increment consumption and the setting of the minor source baseline date
for PM2.5 will occur under its own PSD program.
Nevertheless, regardless of when a State begins to require
PM2.5 increment analyses and how it chooses to set the
PM2.5 minor source baseline date, the emissions from sources
subject to PSD for PM2.5 on which construction commenced
after October 20, 2010 (the major source baseline date) will consume
PM2.5 increment and must be included in increment analyses
occurring after the minor source baseline date is established for an
area under the State's revised PSD program.
2. Federal PSD Program
The Federal PSD regulations under 40 CFR 52.21 apply where states
do not have approved PSD programs and in Indian lands. In such cases,
either EPA implements the PSD program or the State will implement it
under authority granted by EPA through a delegation agreement.
We proposed to begin implementing the Federal PSD program for
PM2.5 on the effective date of the final rule, i.e., either
1 year from the date of publication in the Federal Register or 60 days
from date of publication, if we developed the PM2.5
increments pursuant to proposed Option 1. Alternatively, we requested
comment on whether we should delay implementation of the Federal PSD
program until 25 months after promulgation, which is the latest date by
which EPA is required to approve State SIP revisions. This is the same
approach we took in 1988 to implement the then new NO2
increments. See 53 FR 40658. We did not propose the 24-month delay for
the PM2.5 increments because of the significant delay that
has already occurred between the time we promulgated the
PM2.5 NAAQS and the time the PM2.5 increment
rulemaking would be finalized. However, we sought comment on this
alternative approach because we recognized that it might not be
equitable to begin implementation of the new program requirements in
those few areas where the Federal program applies before the majority
of states are required to implement the program.
Two commenters urged EPA to hold off implementation of State
programs administered under the Federal PSD program in order to provide
a uniform and consistent national approach. One State agency supported
implementing the Federal PSD program with a delayed effective date of 1
year after the effective date of the final rule instead of 60 days.
We have decided to begin implementing the revised Federal PSD
program as set out previously in our introductory discussion of this
issue in section VIII.A. That is, the revised regulations at 40 CFR
52.21 will become effective in 60 days, on December 20, 2010. This will
allow EPA or the delegated State agency to begin using the SILs and SMC
for PM2.5 on that date, as described in section VIII.C of
this preamble. However, the date established in the regulations for the
trigger date will ensure that the PM2.5 increments do not
become effective for 1 year, consistent with section 166(b) of the Act,
and that the minor source baseline date cannot be established until the
PM2.5 increments become effective. However, PSD sources
subject to PM2.5 that receive their PSD permit after the
date of publication of this final rule will be considered to consume
PM2.5 increments by virtue of the fact that they will
commence construction after the major source baseline date for
PM2.5, which is the date of publication of this final rule.
[[Page 64899]]
Thus, sources in an area subject to the Federal PSD program for
PM2.5 will be able to use the SILs and SMC as screening
tools for the required PM2.5 NAAQS compliance demonstration,
but in most cases will not be required to submit a PM2.5
increment analysis as part of a complete PSD permit application for a
Federal PSD permit unless the application is submitted on or after
October 20, 2011. On or after that date, when an applicant submits a
complete PSD permit application that is required to address
PM2.5 under the Federal PSD program, that first application
will establish the minor source baseline date for PM2.5 in
the applicable attainment or unclassifiable area.
As with the State PSD program requirements, prior to the
establishment of the minor source baseline date in an area, emissions
increases from minor sources in the area will be counted toward the
baseline concentration, rather than to the PM2.5 increment.
As described earlier, the emissions from major stationary sources that
commence construction after the major source baseline date, regardless
of the date on which their PSD application is submitted, must be
counted toward consumption of the PM2.5 increments. While
these sources will not be required to submit an increment analysis for
PM2.5 as part of their complete application as long as they
receive their PSD permit before the trigger date for PM2.5
(see discussion that follows in section VIII.B), the emissions
increases resulting from the permitting of these sources ultimately
must be counted toward the PM2.5 increments when the first
PSD permit application submitted after the trigger date establishes the
minor source baseline date for the area of concern, and in all
subsequent PM2.5 increment analyses for that area.
B. Transition Period
In the 2007 NPRM, we proposed a transition period to clarify when
PSD permit applications must contain an increment analysis
demonstrating compliance with the PM2.5 increments following
the date the PM2.5 increments become effective in any State
or Federal PSD program. Specifically, we proposed to establish a
grandfathering provision to allow complete applications submitted
before the increment effective date, but for which the permit had not
yet been issued by the effective date, to continue being processed
using the PM10 Surrogate Policy to satisfy the requirement
to demonstrate compliance with the new PM2.5 requirements.
The grandfathering provision for PM2.5 was originally
proposed in the 2007 NPRM at 40 CFR 51.166(i)(10) and 40 CFR
52.21(i)(11) for State and Federal PSD programs, respectively. See 72
FR 54149 and 54154.
Three commenters supported the proposed grandfathering provision
for sources that submitted a complete application before the effective
date of the applicable PSD rules. Another commenter felt that it was
reasonable to allow states a choice between using PM10 or
PM2.5 increments during a transition period including SIP
approval, where applicable.
During the time since the proposal of this rule in 2007, we have
reconsidered the need for the proposed transition period in the Federal
PSD program to effectively implement the PM2.5 increments.
In light of the importance of preventing significant deterioration of
PM2.5 air quality and the amount of time that has passed
since the initial promulgation of the PM2.5 NAAQS, we do not
believe that further delay is warranted. We expect that most permits
issued after October 20, 2011 will be from sources that submitted their
PSD applications after the major source baseline date for
PM2.5, which is defined as the date of publication of this
final rule, so that they will be increment-consuming sources.
Therefore, when these sources apply for their PSD permits, they will
have had significant advance notice of when the PM2.5
increments will become effective, i.e., 1 year from the date of
publication of this final rule. The review and permitting of permit
applications submitted prior to the publication date of this final rule
should generally be completed prior to the effective date of
PM2.5 increments and thus effectively have a transition
period of 1 year to complete processing.
Thus, we are requiring each source that receives its PSD permit
after the effective date of the PM2.5 increments, regardless
of when the application was submitted, to provide a demonstration that
the source's proposed emissions increase, along with other increment-
consuming emissions, will not cause or contribute to a violation of the
PM2.5 increments.
Under this final rule, sources applying for a PSD permit under the
Federal PSD program after the major source baseline date for
PM2.5 (i.e., after the date of publication of this final
rule), but before the PM2.5 increments become effective
(i.e., the date 1 year after publication of this final rule), will be
considered to consume PM2.5 increment. While EPA will not
require any such source to include a PM2.5 increment
analysis as part of its initial PSD application, an increment analysis
ultimately will be required before the permit may be issued if the date
of issuance will occur after the trigger date, when the
PM2.5 increments become effective under the Federal PSD
program.
Finally, for the same reasons that we are not adopting the proposed
transition period that would have exempted PSD applicants with pending
permit applications from demonstrating compliance with the
PM2.5 increment requirements under the Federal PSD program,
we have decided not to provide an option for states to apply a
transition period under 40 CFR 51.166. We believe it is appropriate for
all increment-consuming sources subject to PM2.5 to
demonstrate compliance with the PM2.5 increments when the
required permit is issued after the PM2.5 increments become
effective in the State's PSD regulations.
C. SILs and SMC for PM2.5
In the 2007 NPRM, we explained our position that SILs and SMCs are
not minimum required elements of an approvable SIP. While these de
minimis values are widely considered to be useful components for
implementing the PSD program, they are not absolutely necessary for the
states to implement their PSD programs. That is, states can satisfy the
statutory requirements for a PSD program by requiring each PSD
applicant to submit air quality monitoring data and to conduct a
comprehensive air quality impacts analysis for PM2.5 without
using de minimis thresholds to exempt certain sources from such
requirements. Because the de minimis values for PM2.5 (and
other pollutants) are not mandatory elements, we proposed not to
establish specific deadlines for submitting revisions to incorporate
the specific values for PM2.5 into SIPs.
One State/local commenter agreed that the SILs and SMCs should not
be a required element of the PSD SIP. Another State/local commenter
agreed with our proposal, but stated that EPA has the authority to
include SILs and SMCs as minimum program requirements per the opinion
set forth in Alabama Power. This commenter added that the EPA
Environmental Appeals Board has affirmed EPA's interpretation of the
Act to allow EPA to evaluate the significance of a source's impact when
determining whether the source's emissions would ``cause or
contribute'' to a NAAQS or increments violation under section 165(a)(3)
of the Act.
Two commenters disagreed with our proposed position and argued that
SILs and SMCs should be mandatory elements of a State PSD program. One
[[Page 64900]]
of these commenters argued that the requirement to model without the
use of screening models with SILs and SMCs is so unreasonable that EPA
must require that states adopt the SILs and SMCs to meet the Purpose
clause of the Act, which requires a balancing of environmental and
economic considerations. The other opposing commenter stated that the
increments, SILs, and SMCs need to be adopted as a single regulatory
approach because the SILs and SMCs define when additional work is
needed to ensure that PSD requirements, such as maintaining adequate
increment, are met. This commenter added that there is no reason for
sources to be placed in the position of conducting expensive modeling
that can delay a project when it is unnecessary from an air quality
perspective.
We agree that the SILs and SMCs used as de minimis thresholds for
the various pollutants are useful tools that enable permitting
authorities and PSD applicants to screen out ``insignificant''
activities; however, the fact remains that these values are not
required by the Act as part of an approvable SIP program. We believe
that most states are likely to adopt the SILs and SMCs because of the
useful purpose they serve regardless of our position that the values
are not mandatory. Alternatively, states may develop more stringent
values if they desire to do so. In any case, states are not under any
SIP-related deadline for revising their PSD programs to add these
screening tools.
Using the SILs for PM2.5, when a proposed major new
source or major modification of PM2.5 predicts (via air
quality modeling) an impact less than the PM2.5 de minimis
value, the proposed source or modification is not considered to have a
significant air quality impact and would not need to complete a
cumulative impact analysis involving an analysis of other sources in
the area. Also, a source with a de minimis ambient impact would not be
considered to cause or contribute to a violation of either the
PM2.5 NAAQS or increments.
The PM2.5 SILs will become effective under the Federal
PSD program on the effective date of this final rule, that is, on
December 20, 2010, when either EPA, or a State acting under a
delegation of EPA's authority, implements the revised PSD permitting
requirements for PM2.5 pursuant to 40 CFR 52.21. The SILs
will be for use initially with the compliance demonstration for the
PM2.5 NAAQS, and later for the PM2.5 increment
analysis, under the Federal PSD program. We emphasize, however, that
the PM2.5 SILs are not intended to be used as part of the
determination of adverse impacts on AQRVs for PM2.5 in Class
I areas.
Similarly, we intend to use the PM2.5 SMC (4 [mu]g/
m3, 24-hour average) as a screening tool in the Federal PSD
permit program beginning on December 20, 2010. Accordingly, when either
the modeled PM2.5 impact of, or the existing ambient air
quality within the area of, the proposed new major source or major
modification is less than the PM2.5 SMC, the reviewing
authority may exempt the source or modification from the monitoring
data requirements for PM2.5 under 40 CFR 52.21(m).
IX. Other Regulatory Changes
The Act provides that the PSD regulations apply to areas designated
as ``attainment'' or ``unclassifiable'' as defined by the Act. When the
original regulations were written, the Act provisions for designating
areas as either ``attainment'' or ``unclassifiable'' were contained in
sections 107(d)(1)(D) and (E), respectively. In 1990, Congress revised
section 107 and changed the relevant paragraphs defining ``attainment''
and ``unclassifiable'' areas to sections 107(d)(1)(A)(ii) and (iii),
respectively. In accordance with these statutory changes, we are
correcting the references to the statutory classifications contained in
the existing PSD rules to match the revised paragraphs in the Act. See
revised 40 CFR 51.166(b)(14)(iii)(a) and (15)(i) and (ii), and 40 CFR
52.21(b)(14)(iii)(a) and (15)(i) and (ii).
In adding the SILs for PM2.5 in this final rule, we
restructured paragraph (k) (``Source impact analysis'') in the existing
PSD regulations at 40 CFR 51.166 and 52.21. Under the restructuring of
paragraph (k), old paragraph (k)(2) is now paragraph (k)(1)(ii). To
accommodate this restructuring change, we are also revising
grandfathering provisions that are contained in existing paragraphs
(i)(8) and (i)(9) at 40 CFR 51.166, and paragraphs (i)(9) and (i)(10)
at 40 CFR 52.21, which contained references to requirements contained
in paragraph (k)(2). As revised, the grandfathering provisions now
reference new paragraph (k)(1)(ii).
X. Statutory and Executive Order Reviews
A. Executive Order 12866--Regulatory Planning and Review
Under Executive Order 12866 (58 FR 51735, October 4, 1993), this
action is a ``significant regulatory action'' because it raises novel
legal or policy issues arising out of legal mandates, the President's
priorities, or the principle set forth in the Executive Order.
Accordingly, EPA submitted this action to OMB for review under
Executive Order 12866 and any changes made in response to OMB
recommendations have been documented in the docket for this action.
B. Paperwork Reduction Act
The information collection requirements in this rule have been
submitted for approval to the OMB under the Paperwork Reduction Act, 44
U.S.C. 3501 et seq. The information collection requirements are not
enforceable until OMB approves them.
Pursuant to title I, part C, of the Act, the PSD program requires
the owner or operator to obtain a permit prior to either constructing a
new major stationary source of air pollutants or making a major
modification to an existing major stationary source. The information
collection for sources under PSD results from the requirement for
owners or operators to submit applications for NSR permits. In some
cases, sources must conduct preconstruction monitoring to determine the
existing ambient air quality. For reviewing authorities, the
information collection results from the requirement to process permit
applications and issue permits, and to transmit associated information
to EPA. The EPA oversees the PSD program, and the information collected
by sources and reviewing authorities is used to ensure that the program
is properly implemented.
The final rule will increase the PSD permitting burden for owners
and operators of major stationary sources of PM2.5 emissions
by adding PM2.5 increments to the list of existing
increments for which air quality impact analyses must be carried out to
track the amount of increment consumed by the proposed source and other
sources in the area. Over the 3-year period covered by the ICR, we
estimate an average annual burden totaling about 29,000 hours and $2.8
million for all industry entities that will be affected by the final
rule. For the same reasons, we also expect the final rule (when fully
implemented) to increase burden for the State and local authorities
reviewing PSD permit applications. In addition, there will be
additional burden for State and local agencies to revise their SIPs to
incorporate the proposed changes. Over the 3-year period covered by the
ICR, we estimate that the average annual burden for all State and local
reviewing authorities will total about 7,500 hours and $581,000. Burden
is defined at 5 CFR 1320.3(b).
[[Page 64901]]
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 in 40 CFR are listed in 40 CFR part 9. When this ICR is
approved by OMB, the Agency will publish a technical amendment to 40
CFR part 9 in the Federal Register to display the OMB control number
for the approved information collection requirements contained in this
final rule.
C. Regulatory Flexibility Act
The Regulatory Flexibility Act (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.
For purposes of assessing the impacts of this rule on small
entities, ``small entity'' is defined as: (1) A small business as
defined by the Small Business Administration's regulations at 13 CFR
121.201; (2) a small governmental jurisdiction that is a government of
a city, county, town, school district or special district with a
population of less than 50,000; and (3) a small organization that is
any not-for-profit enterprise which is independently owned and operated
and is not dominant in its field.
After considering the economic impacts of this final rule on small
entities, I certify that this action will not have a significant
economic impact on a substantial number of small entities. This final
rule will not impose any requirements on small entities because small
entities are not subject to the requirements of this rule.
D. Unfunded Mandates Reform Act
This action contains no Federal mandates under the provisions of
Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), 2 U.S.C.
1531-1538 for State, local, or tribal governments or the private
sector. The action imposes no enforceable duty on any State, local or
tribal governments or the private sector. The final rules adds only a
relatively small number of new requirements to the existing permit
requirements already in place under the PSD program, since states are
currently implementing a PM10 surrogate program pursuant to
EPA guidance. Thus, this action is not subject to the requirements of
sections 202 or 205 of UMRA.
This rule is also not subject to the requirements of section 203 of
UMRA because it contains no regulatory requirements that might
significantly or uniquely affect small governments. The final rule
applies only to new major stationary sources and to major modifications
at existing major stationary sources.
E. Executive Order 13132--Federalism
This final rule does not have federalism implications. It will not
have substantial direct effects on the states, on the relationship
between the national government and the states, or on the distribution
of power and responsibilities among the various levels of government,
as specified in Executive Order 13132. The final rule makes relatively
minor changes to the established PSD program, simply making it possible
for states to implement PSD for PM2.5 instead of relying on
PM10 as a surrogate. Thus, Executive Order 13132 does not
apply to this rule. In the spirit of Executive Order 13132, and
consistent with EPA policy to promote communications between EPA and
State and local governments, EPA specifically solicited comment on the
proposed rule from State and local officials.
F. Executive Order 13175--Consultation and Coordination With Indian
Tribal Governments
This action does not have tribal implications, as specified in
Executive Order 13175 (65 FR 67249, November 9, 2000). The final rule
provides the elements to implement a PM2.5 PSD program in
attainment areas. The Act provides for states to develop plans to
regulate emissions of air pollutants within their jurisdictions. The
Tribal Air Rule (TAR) under the Act gives tribes the opportunity to
develop and implement Act programs to attain and maintain the
PM2.5 NAAQS, but leaves to the discretion of the tribes the
decision of whether to develop these programs and which programs, or
appropriate elements of a program, they will adopt. Thus, Executive
Order 13175 does not apply to this action.
The EPA did reach out to national tribal organizations in 2006 to
provide a forum for tribal professionals to provide input to the
rulemaking. However, not much participation or input was received.
G. Executive Order 13045--Protection of Children From Environmental
Health and Safety Risks
This action is not subject to Executive Order 13045 (62 FR 19885,
April 23, 1997) because it is not economically significant as defined
in Executive Order 12866, and because the Agency does not believe the
environmental health or safety risks addressed by this action present a
disproportionate risk to children. One of the basic requirements of the
PSD program is that new and modified major sources must demonstrate
that any new emissions do not cause or contribute to air quality in
violation of the NAAQS.
H. Executive Order 13211--Actions That Significantly Affect Energy
Supply, Distribution, or Use
This action is not a ``significant energy action'' as defined in
Executive Order 13211 (66 FR 28355, May 22, 2001) because it is not
likely to have a significant adverse effect on the supply,
distribution, or use of energy. Further, we have concluded that this
rule is not likely to have any adverse energy effects.
I. National Technology Transfer and Advancement Act
Section 12(d) of the National Technology Transfer and Advancement
Act of 1995 (NTTAA), Public Law 104-113, 12(d) (15 U.S.C. 272 note)
directs EPA to use voluntary consensus standards in its regulatory
activities unless to do so would be inconsistent with applicable law or
otherwise impractical. Voluntary consensus standards are technical
standards (e.g., materials specifications, test methods, sampling
procedures, and business practices) that are developed or adopted by
voluntary consensus standards bodies. The NTTAA directs EPA to provide
Congress, through OMB, explanations when the Agency decides not to use
available and applicable voluntary consensus standards.
This action does not involve technical standards. Therefore, EPA
did not consider the use of any voluntary consensus standards.
J. Executive Order 12898--Federal Actions To Address Environmental
Justice in Minority Populations and Low-Income Populations
Executive Order 12898 (59 FR 7629, Feb. 16, 1994) establishes
Federal executive policy on environmental justice. Its main provision
directs Federal agencies, to the greatest extent practicable and
permitted by law, to make environmental justice part of their mission
by identifying and addressing,
[[Page 64902]]
as appropriate, disproportionately high and adverse human health or
environmental effects of their programs, policies, and activities on
minority populations and low-income populations in the United States.
The EPA has determined that this final rule will not have
disproportionately high and adverse human health or environmental
effects on minority or low-income populations because it does not
affect the level of protection provided to human health or the
environment. This final rule will provide regulatory certainty for
implementing the preconstruction NSR permitting program for
PM2.5. However, the requirements are similar to the existing
requirements of the PM10 program and hence do not impact the
human health or environmental effects.
K. Congressional Review Act
The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the
Small Business Regulatory Enforcement Fairness Act of 1996, generally
provides that before a rule may take effect, the agency promulgating
the rule must submit a rule report, which includes a copy of the rule,
to each House of the Congress and to the Comptroller General of the
United States. The EPA will submit a report containing this rule and
other required information to the U.S. Senate, the U.S. House of
Representatives, and the Comptroller General of the United States prior
to publication of the rule in the Federal Register. A major rule cannot
take effect until 60 days after it is published in the Federal
Register. This action is not a ``major rule'' as defined by 5 U.S.C.
804(2). Nevertheless, this rule needs to be reviewed for the
PM2.5 increments being promulgated herein so that they can
be scrutinized by Congress as intended under section 166(b) of the Act.
Even though the PM2.5 increments will not become applicable
for 1 year, the final rule will become effective 60 days from the date
of publication, that is, on December 20, 2010, for the screening tools
(SILs and SMC) being established in this rule.
XI. Judicial Review
Under section 307(b)(1) of the Act, petitions for judicial review
of this action must be filed in the United States Court of Appeals for
the District of Columbia Circuit by December 20, 2010. Any such
judicial review is limited to only those objections that are raised
with reasonable specificity in timely comments. Filing a petition for
reconsideration by the Administrator of this final rule does not affect
the finality of this rule for the purposes of judicial review nor does
it extend the time within which a petition for judicial review may be
filed, and shall not postpone the effectiveness of such rule or action.
Under section 307(b)(2) of the Act, the requirements of this final
action may not be challenged later in civil or criminal proceedings
brought by us to enforce these requirements.
XII. Statutory Authority
The statutory authority for this final action is provided by
sections 101, 160, 163, 165, 166, 301, and 307(d) of the Act as amended
(42 U.S.C. 7401, 7470, 7473, 7475, 7476, 7601, and 7607(d)).
List of Subjects
40 CFR Part 51
Administrative practices and procedures, Air pollution control,
Environmental protection, Intergovernmental relations.
40 CFR Part 52
Administrative practices and procedures, Air pollution control,
Environmental protection, Intergovernmental relations.
Dated: September 30, 2010.
Lisa P. Jackson,
Administrator.
0
For the reasons set out in the preamble, title 40, chapter I of the
Code of Federal Regulations is amended as follows:
PART 51--[AMENDED]
0
1. The authority citation for part 51 continues to read as follows:
Authority: 23 U.S.C. 101; 42 U.S.C. 7401-7671q.
Subpart I--[Amended]
0
2. Section 51.165 is amended by revising the table in paragraph (b)(2)
to read as follows:
Sec. 51.165 Permit requirements.
* * * * *
(b) * * *
(2) * * *
----------------------------------------------------------------------------------------------------------------
Averaging time (hours)
Pollutant Annual -----------------------------------------------------------------
24 8 3 1
----------------------------------------------------------------------------------------------------------------
SO2.......................... 1.0 [mu]g/m3 5 [mu]g/m3 ............... 25 [mu]g/m3
PM10......................... 1.0 [mu]g/m3 5 [mu]g/m3 ............... ...............
PM2.5........................ 0.3 [mu]g/m3 1.2 [mu]g/m3 ............... ...............
NO2.......................... 1.0 [mu]g/m3
CO........................... ............... ............... 0.5 mg/m3 ............... 2 mg/m3
----------------------------------------------------------------------------------------------------------------
* * * * *
0
3. Section 51.166 is amended as follows:
0
a. By revising paragraph (a)(6)(i);
0
b. By revising paragraph (b)(14)(i)(a);
0
c. By removing the period at the end of paragraph (b)(14)(i)(b) and
adding ``; and'' in its place;
0
d. By adding paragraph (b)(14)(i)(c);
0
e. By revising paragraph (b)(14)(ii)(a);
0
f. By removing the period at the end of paragraph (b)(14)(ii)(b) and
adding ``; and'' in its place;
0
g. By adding paragraph (b)(14)(ii)(c);
0
h. By revising paragraph (b)(14)(iii)(a);
0
i. By revising paragraph (b)(15)(i) and paragraph (b)(15)(ii)
introductory text;
0
j. By revising the table in paragraph (c)(1);
0
k. By revising paragraph (c)(2);
0
l. By revising paragraph (i)(5)(i)(c);
0
m. By redesignating existing paragraphs (i)(5)(i)(d) through (j) as
paragraphs (i)(5)(i)(e) through (k);
0
n. By adding new paragraph (i)(5)(i)(d);
0
o. By removing ``(k)(2)'' from paragraph (i)(8) and adding
``(k)(1)(ii)'' in its place;
0
p. By removing in two places ``(k)(2)'' from paragraph (i)(9) and
adding ``(k)(1)(ii)'' in those places;
0
q. By revising paragraph (k);
0
r. By removing the words ``particulate matter'' in the last sentence of
paragraph (p)(4) introductory text and adding in their place
``PM2.5, PM10''; and
0
s. By revising the table in paragraph (p)(4).
Sec. 51.166 Prevention of significant deterioration of air quality.
(a) * * *
(6) * * *
[[Page 64903]]
(i) Any State required to revise its implementation plan by reason
of an amendment to this section, with the exception of amendments to
add new maximum allowable increases or other measures pursuant to
section 166(a) of the Act, shall adopt and submit such plan revision to
the Administrator for approval no later than 3 years after such
amendment is published in the Federal Register. With regard to a
revision to an implementation plan by reason of an amendment to
paragraph (c) of this section to add maximum allowable increases or
other measures, the State shall submit such plan revision to the
Administrator for approval within 21 months after such amendment is
published in the Federal Register.
* * * * *
(b) * * *
(14)(i) * * *
(a) In the case of PM10 and sulfur dioxide, January 6,
1975;
* * * * *
(c) In the case of PM2.5, October 20, 2010.
(ii) * * *
(a) In the case of PM10 and sulfur dioxide, August 7,
1977;
* * * * *
(c) In the case of PM2.5, October 20, 2011.
(iii) * * *
(a) The area in which the proposed source or modification would
construct is designated as attainment or unclassifiable under section
107(d)(1)(A)(ii) or (iii) of the Act for the pollutant on the date of
its complete application under 40 CFR 52.21 or under regulations
approved pursuant to 40 CFR 51.166; and
* * * * *
(15)(i) Baseline area means any intrastate area (and every part
thereof) designated as attainment or unclassifiable under section
107(d)(1)(A)(ii) or (iii) of the Act in which the major source or major
modification establishing the minor source baseline date would
construct or would have an air quality impact for the pollutant for
which the baseline date is established, as follows: Equal to or greater
than 1 [micro]g/m\3\ (annual average) for SO2,
NO2, or PM10; or equal or greater than 0.3
[micro]g/m\3\ (annual average) for PM2.5.
(ii) Area redesignations under section 107(d)(1)(A)(ii) or (iii) of
the Act cannot intersect or be smaller than the area of impact of any
major stationary source or major modification which:
* * * * *
(c) * * *
(1) * * *
------------------------------------------------------------------------
Maximum
allowable
increase
Pollutant (micrograms
per cubic
meter)
------------------------------------------------------------------------
Class I Area
------------------------------------------------------------------------
PM2.5:
Annual arithmetic mean.............................. 1
24-hr maximum....................................... 2
PM10:
Annual arithmetic mean.............................. 4
24-hr maximum....................................... 8
Sulfur dioxide:
Annual arithmetic mean.............................. 2
24-hr maximum....................................... 5
3-hr maximum........................................ 25
Nitrogen dioxide:
Annual arithmetic mean.............................. 2.5
------------------------------------------------------------------------
Class II Area
------------------------------------------------------------------------
PM2.5:
Annual arithmetic mean.............................. 4
24-hr maximum....................................... 9
PM10:
Annual arithmetic mean.............................. 17
24-hr maximum....................................... 30
Sulfur dioxide:
Annual arithmetic mean.............................. 20
24-hr maximum....................................... 91
3-hr maximum........................................ 512
Nitrogen dioxide:
Annual arithmetic mean.............................. 25
------------------------------------------------------------------------
Class III Area
------------------------------------------------------------------------
PM2.5:
Annual arithmetic mean.............................. 8
24-hr maximum....................................... 18
PM10:
Annual arithmetic mean.............................. 34
24-hr maximum....................................... 60
Sulfur dioxide:
Annual arithmetic mean.............................. 40
24-hr maximum....................................... 182
3-hr maximum........................................ 700
Nitrogen dioxide:
[[Page 64904]]
Annual arithmetic mean.............................. 50
------------------------------------------------------------------------
* * * * *
(2) Where the State can demonstrate that it has alternative
measures in its plan other than maximum allowable increases as defined
under paragraph (c)(1) of this section, that satisfy the requirements
in sections 166(c) and 166(d) of the Clean Air Act for a regulated NSR
pollutant for which the Administrator has established maximum allowable
increases pursuant to section 166(a) of the Act, the requirements for
maximum allowable increases for that pollutant under paragraph (c)(1)
of this section shall not apply upon approval of the plan by the
Administrator. The following regulated NSR pollutants are eligible for
such treatment:
(i) Nitrogen dioxide.
(ii) PM2.5.
* * * * *
(i) * * *
(5) * * *
(i) * * *
(c) PM2.5-4 [mu]g/m\3\, 24-hour average;
(d) PM10-10 [mu]g/m\3\, 24-hour average;
* * * * *
(k) Source impact analysis--(1) Required demonstration. The plan
shall provide that the owner or operator of the proposed source or
modification shall demonstrate that allowable emission increases from
the proposed source or modification, in conjunction with all other
applicable emissions increases or reduction (including secondary
emissions), would not cause or contribute to air pollution in violation
of:
(i) Any national ambient air quality standard in any air quality
control region; or
(ii) Any applicable maximum allowable increase over the baseline
concentration in any area.
(2) Significant impact levels. The plan may provide that, for
purposes of PM2.5, the demonstration required in paragraph
(k)(1) of this section is deemed to have been made if the emissions
increase from the new stationary source alone or from the modification
alone would cause, in all areas, air quality impacts less than the
following amounts:
----------------------------------------------------------------------------------------------------------------
Pollutant Averaging time Class I area Class II area Class III area
----------------------------------------------------------------------------------------------------------------
PM2.5........................... Annual............. 0.06 [mu]g/m\3\ 0.3 [mu]g/m\3\ 0.3 [mu]g/m\3\
24-hour............ 0.07 [mu]g/m\3\ 1.2 [mu]g/m\3\ 1.2 [mu]g/m\3\
----------------------------------------------------------------------------------------------------------------
* * * * *
(p) * * *
(4) * * *
------------------------------------------------------------------------
Maximum
allowable
increase
Pollutant (micrograms
per cubic
meter)
------------------------------------------------------------------------
PM2.5:
Annual arithmetic mean.............................. 4
24-hr maximum....................................... 9
PM10:
Annual arithmetic mean.............................. 17
24-hr maximum....................................... 30
Sulfur dioxide:
Annual arithmetic mean.............................. 20
24-hr maximum....................................... 91
3-hr maximum........................................ 325
Nitrogen dioxide:
Annual arithmetic mean.............................. 25
------------------------------------------------------------------------
* * * * *
0
4. Appendix S to part 51 is amended by revising the table in section
III.A to read as follows:
Appendix S to Part 51--Emission Offset Interpretative Ruling
* * * * *
III. * * *
A. * * *
----------------------------------------------------------------------------------------------------------------
Averaging time (hours)
Pollutant Annual -----------------------------------------------------------------
24 8 3 1
----------------------------------------------------------------------------------------------------------------
SO2.......................... 1.0 [mu]g/m\3\ 5 [mu]g/m\3\ ............... 25 [mu]g/m\3\
PM10......................... 1.0 [mu]g/m\3\ 5 [mu]g/m\3\ ............... ............. ...............
[[Page 64905]]
PM2.5........................ 0.3 [mu]g/m\3\ 1.2 [mu]g/m\3\ ............... ............. ...............
NO2.......................... 1.0 [mu]g/m\3\ ............... ............... ............. ...............
CO........................... ............... ............... 0.5 mg/m\3\ ............. 2 mg/m\3\
----------------------------------------------------------------------------------------------------------------
* * * * *
PART 52--[AMENDED]
0
1. The authority citation for part 52 continues to read as follows:
Authority: 42 U.S.C. 7401, et seq.
Subpart A--[Amended]
0
2. Section 52.21 is amended as follows:
0
a. By revising paragraph (b)(14)(i)(a);
0
b. By removing the period at the end of paragraph (b)(14)(i)(b) and
adding ``; and'' in its place;
0
c. By adding paragraph (b)(14)(i)(c);
0
d. By revising paragraph (b)(14)(ii)(a);
0
e. By removing the period at the end of paragraph (b)(14)(ii)(b) and
adding ``; and'' in its place;
0
f. By adding paragraph (b)(14)(ii)(c);
0
g. By revising paragraph (b)(14)(iii)(a);
0
h. By revising paragraph (b)(15)(i) and paragraph (b)(15)(ii)
introductory text;
0
i. By revising the table in paragraph (c);
0
j. By revising paragraph (i)(5)(i);
0
k. By removing ``(k)(2)'' from paragraph (i)(9) and adding
``(k)(1)(ii)'' in its place;
0
l. By removing in two places ``(k)(2)'' from paragraph (i)(10) and
adding ``(k)(1)(ii)'' in those places;
0
m. By revising paragraph (k);
0
n. By removing the words ``particulate matter'' in the last sentence of
paragraph (p)(5) introductory text and adding in their place
``PM2.5, PM10''; and
0
o. By revising the table in paragraph (p)(5).
Sec. 52.21 Prevention of significant deterioration of air quality.
* * * * *
(b) * * *
(14)(i) * * *
(a) In the case of PM10 and sulfur dioxide, January 6,
1975;
* * * * *
(c) In the case of PM2.5, October 20, 2010.
(ii) * * *
(a) In the case of PM10 and sulfur dioxide, August 7,
1977;
* * * * *
(c) In the case of PM2.5, October 20, 2011.
(iii) * * *
(a) The area in which the proposed source or modification would
construct is designated as attainment or unclassifiable under section
107(d)(1)(A)(ii) or (iii) of the Act for the pollutant on the date of
its complete application under 40 CFR 52.21 or under regulations
approved pursuant to 40 CFR 51.166; and
* * * * *
(15)(i) Baseline area means any intrastate area (and every part
thereof) designated as attainment or unclassifiable under section
107(d)(1)(A)(ii) or (iii) of the Act in which the major source or major
modification establishing the minor source baseline date would
construct or would have an air quality impact for the pollutant for
which the baseline date is established, as follows: equal to or greater
than 1 [micro]g/m\3\ (annual average) for SO2,
NO2, or PM10; or equal or greater than 0.3
[micro]g/m\3\ (annual average) for PM2.5.
(ii) Area redesignations under section 107(d)(1)(A)(ii) or (iii) of
the Act cannot intersect or be smaller than the area of impact of any
major stationary source or major modification which:
* * * * *
(c) * * *
------------------------------------------------------------------------
Maximum
allowable
increase
Pollutant (micrograms
per cubic
meter)
------------------------------------------------------------------------
Class I Area
------------------------------------------------------------------------
PM2.5:
Annual arithmetic mean.............................. 1
24-hr maximum....................................... 2
PM10:
Annual arithmetic mean.............................. 4
24-hr maximum....................................... 8
Sulfur dioxide:
Annual arithmetic mean.............................. 2
24-hr maximum....................................... 5
3-hr maximum........................................ 25
Nitrogen dioxide:
Annual arithmetic mean.............................. 2.5
------------------------------------------------------------------------
Class II Area
------------------------------------------------------------------------
PM2.5:
Annual arithmetic mean.............................. 4
24-hr maximum....................................... 9
PM10:
Annual arithmetic mean.............................. 17
24-hr maximum....................................... 30
Sulfur dioxide:
Annual arithmetic mean.............................. 20
[[Page 64906]]
24-hr maximum....................................... 91
3-hr maximum........................................ 512
Nitrogen dioxide:
Annual arithmetic mean.............................. 25
------------------------------------------------------------------------
Class III Area
------------------------------------------------------------------------
PM2.5:
Annual arithmetic mean.............................. 8
24-hr maximum....................................... 18
PM10:
Annual arithmetic mean.............................. 34
24-hr maximum....................................... 60
Sulfur dioxide:
Annual arithmetic mean.............................. 40
24-hr maximum....................................... 182
3-hr maximum........................................ 700
Nitrogen dioxide:
Annual arithmetic mean.............................. 50
------------------------------------------------------------------------
* * * * *
(i) * * *
(5) * * *
(i) The emissions increase of the pollutant from the new source or
the net emissions increase of the pollutant from the modification would
cause, in any area, air quality impacts less than the following
amounts:
(a) Carbon monoxide--575 [mu]g/m\3\, 8-hour average;
(b) Nitrogen dioxide--14 [mu]g/m\3\, annual average;
(c) PM2.5--4 [mu]g/m\3\, 24-hour average;
(d) PM10--10 [mu]g/m\3\, 24-hour average;
(e) Sulfur dioxide--13 [mu]g/m\3\, 24-hour average;
(f) Ozone;
(g) Lead--0.1 [mu]g/m\3\, 3-month average;
(h) Fluorides--0.25 [mu]g/m\3\, 24-hour average;
(i) Total reduced sulfur--10 [mu]g/m\3\, 1-hour average;
(j) Hydrogen sulfide--0.2 [mu]g/m\3\, 1-hour average;
(k) Reduced sulfur compounds-- 10 [mu]g/m\3\, 1-hour average; or
Note to paragraph (c)(50)(i)(f):
No de minimis air quality level is provided for ozone. However,
any net emissions increase of 100 tons per year or more of volatile
organic compounds or nitrogen oxides subject to PSD would be
required to perform an ambient impact analysis, including the
gathering of ambient air quality data.
* * * * *
(k) Source impact analysis--(1) Required demonstration. The owner
or operator of the proposed source or modification shall demonstrate
that allowable emission increases from the proposed source or
modification, in conjunction with all other applicable emissions
increases or reductions (including secondary emissions), would not
cause or contribute to air pollution in violation of:
(i) Any national ambient air quality standard in any air quality
control region; or
(ii) Any applicable maximum allowable increase over the baseline
concentration in any area.
(2) Significant impact levels. For purposes of PM2.5,
the demonstration required in paragraph (k)(1) of this section is
deemed to have been made if the emissions increase from the new
stationary source alone or from the modification alone would cause, in
all areas, air quality impacts less than the following amounts:
----------------------------------------------------------------------------------------------------------------
Pollutant Averaging time Class I area Class II area Class III area
----------------------------------------------------------------------------------------------------------------
PM2.5.......................... Annual............ 0.06 [mu]g/m\3\ 0.3 [mu]g/m\3\ 0.3 [mu]g/m\3\
24-hour........... 0.07 [mu]g/m\3\ 1.2 [mu]g/m\3\ 1.2 [mu]g/m\3\
----------------------------------------------------------------------------------------------------------------
* * * * *
(p) * * *
[[Page 64907]]
(5) * * *
------------------------------------------------------------------------
Maximum
allowable
increase
Pollutant (micrograms
per cubic
meter)
------------------------------------------------------------------------
PM2.5:
Annual arithmetic mean.............................. 4
24-hr maximum....................................... 9
PM10:
Annual arithmetic mean.............................. 17
24-hr maximum....................................... 30
Sulfur dioxide:
Annual arithmetic mean.............................. 20
24-hr maximum....................................... 91
3-hr maximum........................................ 325
Nitrogen dioxide:
Annual arithmetic mean.............................. 25
------------------------------------------------------------------------
* * * * *
[FR Doc. 2010-25132 Filed 10-19-10; 8:45 am]
BILLING CODE 6560-50-P