[Federal Register Volume 87, Number 233 (Tuesday, December 6, 2022)]
[Proposed Rules]
[Pages 74577-74588]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-26504]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Parts 52 and 81
[EPA-R08-OAR-2021-0003; FRL-10454-01-R8]
Approval and Promulgation of Implementation Plans; Montana; Libby
1997 Annual PM2.5 Limited Maintenance Plan and Redesignation Request
AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed rule.
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SUMMARY: The Environmental Protection Agency (EPA or the Agency) is
proposing to take three separate but related actions. First, EPA is
proposing to determine that the Libby fine particulate matter
(PM2.5) nonattainment area (Libby Area) is attaining the
1997 annual PM2.5 national ambient air quality standards
(NAAQS or standard) based on 2014-2021 data. The Agency is also
proposing to approve Montana's plan for maintaining the 1997 annual
PM2.5 NAAQS (limited maintenance plan) and to redesignate
the Libby Area to attainment for the 1997 annual PM2.5
NAAQS, submitted by the State of Montana on June 24, 2020.
DATES: Written comments must be received on or before January 5, 2023.
ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R08-
OAR-2021-0003, to the Federal Rulemaking Portal at https://www.regulations.gov. Follow the online instructions for submitting
comments. Once submitted, comments cannot be edited or removed from
www.regulations.gov. EPA may publish any comment received to its public
docket. Do not submit electronically any information you consider to be
Confidential Business Information (CBI) or other information whose
disclosure is restricted by statute. Multimedia submissions (audio,
video, etc.) must be accompanied by a written comment. The written
comment is considered the official comment and should include
discussion of all points you wish to make. EPA will generally not
consider comments or comment contents located outside of the primary
submission (i.e., on the web, cloud, or other file sharing system). For
additional submission methods, the full EPA public comment policy,
information about CBI or multimedia submissions, and general guidance
on making effective comments, please visit http://www2.epa.gov/dockets/commenting-epa-dockets.
Docket: All documents in the docket are listed in the
www.regulations.gov index. Although listed in the index, some
information is not publicly available, e.g., CBI or other information
whose disclosure is restricted by statute. Certain other material, such
as copyrighted material, will be publicly available only in hard copy.
Publicly available docket materials are available electronically in
www.regulations.gov. To reduce the risk of COVID-19 transmission, for
this action we do not plan to offer hard copy review of the docket.
Please email or call the person listed in the FOR FURTHER INFORMATION
CONTACT section if you need to make alternative arrangements for access
to the docket.
FOR FURTHER INFORMATION CONTACT: Amrita Singh, Air and Radiation
Division, U.S. Environmental Protection Agency (EPA), Region 8, Mail
Code ARD-QP, 1595 Wynkoop Street, Denver, Colorado 80202-1129,
telephone number: (303) 312-6103, email address: [email protected].
SUPPLEMENTARY INFORMATION: Throughout this document wherever ``we,''
``us,'' or ``our'' is used, we mean EPA.
Table of Contents
I. What are the actions EPA is proposing to take?
[[Page 74578]]
II. What is the background for EPA's proposed actions?
A. The PM2.5 NAAQS
B. Designation of PM2.5 NAAQS Nonattainment Areas
C. PM2.5 NAAQS Nonattainment Area Planning
Requirements
D. Limited Maintenance Plans
III. Why is EPA proposing these actions?
IV. What is EPA's analysis of the request?
A. Has the State met all applicable requirements under section
110 and part D of the Clean Air Act (CAA) and have those
requirements been fully approved? (CAA sections 107(d)(3)(E)(ii) and
(v))
B. Has the State demonstrated that air quality improvement is
due to permanent and enforceable reductions?
C. Does the area have a fully approved maintenance plan pursuant
to section 175A of the CAA?
D. Transportation and General Conformity
V. What are the effects of EPA's proposed actions?
VI. Proposed Actions
VII. Statutory and Executive Order Reviews
I. What are the actions EPA is proposing to take?
EPA is proposing to take the following separate but related
actions: (1) to determine that the Libby Area is attaining the 1997
annual PM2.5 NAAQS based on 2014-2021 data; (2) to approve
Montana's plan for maintaining the 1997 annual PM2.5 NAAQS
(limited maintenance plan); and (3) to redesignate the Libby Area to
attainment for the 1997 annual PM2.5 NAAQS.
Libby, Montana is a small rural community located in Lincoln County
in the northwestern part of the State. Libby sits in the narrow,
triangular Kootenai valley at an elevation of 2,100 feet. The Libby
Area is dominated by three major mountain ranges that limit the air-
shed: (1) the Rocky Mountain and Flathead Ranges on the eastern
boundary; (2) the Purcell Range, which roughly bisects the area from
north to south; and (3) the Selkirk and Cabinet Ranges on the western
boundary. Most of the area surrounding Libby, Montana is national
forest land managed by the U.S. Forest Service.
These proposed actions are summarized and described in greater
detail throughout this proposed rulemaking. EPA's 1997 annual
PM2.5 nonattainment designation for the Libby Area triggered
an obligation for Montana to develop a nonattainment state
implementation plan (SIP) revision addressing certain Clean Air Act
(CAA) requirements under title I, part D, subpart 1 (hereinafter
``Subpart 1'') and title I, part D, subpart 4 (hereinafter ``Subpart
4''). Subpart 1 contains the general requirements for nonattainment
areas for criteria pollutants, including requirements to develop a SIP
that provides for the implementation of reasonably available control
measures (RACM) under section 172(c)(1), reasonable further progress
(RFP), includes base-year and attainment-year emissions inventories,
and for the implementation of contingency measures. As discussed in
greater detail later in this document, Subpart 4 contains specific
planning and scheduling requirements for coarse particulate matter
(PM10) nonattainment areas, including requirements for new
source review (NSR), RACM (under CAA section 189(a)(1)(C)), and RFP.
EPA's longstanding general guidance interpreting the 1990 CAA
Amendments, known as the General Preamble, EPA discussed the
relationship of Subpart 1 and Subpart 4 SIP requirements and pointed
out that Subpart 1 requirements were to an extent ``subsumed by, or
integrally related to, the more specific PM-10 requirements.'' See 57
FR 13538 (April 16, 1992). In addition, under the United States Court
of Appeals for the District of Columbia Circuit's (D.C. Circuit's)
January 4, 2013, decision in Natural Resources Defense Council (NRDC)
v. EPA, 706 F.3d 428 (D.C. Cir. 2013), Subpart 4 requirements apply to
PM2.5 nonattainment areas.\1\
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\1\ In explaining its decision, the Court reasoned that the
plain meaning of the CAA requires implementation of the 1997
PM2.5 NAAQS under Subpart 4 because PM2.5
particles fall within the statutory definition of PM10
and are thus subject to the same statutory requirements. EPA
finalized its interpretation of Subpart 4 requirements as applied to
the PM2.5 NAAQS in its final rule entitled ``Fine
Particulate Matter National Ambient Air Quality Standards: State
Implementation Plan Requirements; Final Rule'' (81 FR 58010, August
24, 2016).
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On June 2, 2014 (79 FR 31566), EPA published a rule entitled
``Identification of Nonattainment Classification and Deadlines for
Submission of State Implementation Plan (SIP) Provisions for the 1997
Fine Particle (PM2.5) National Ambient Air Quality Standard
(NAAQS) and 2006 PM2.5 NAAQS'' (``Classification and
Deadlines Rule''). In that rule, the Agency responded to the D.C.
Circuit's January 2013 decision by identifying all PM2.5
nonattainment areas for the 1997 and 2006 PM2.5 NAAQS as
``Moderate'' nonattainment areas under Subpart 4, and by establishing a
new SIP submission date of December 31, 2014, for Moderate area
attainment plans and for any additional attainment-related or
nonattainment new source review plans necessary for areas to comply
with the requirements applicable under Subpart 4. Id. at 31567-70.
EPA is proposing to determine that the Libby Area is attaining the
1997 annual PM2.5 NAAQS based on recent air quality data.
EPA is also proposing to approve Montana's limited maintenance plan
(LMP) for the Libby Area as meeting the requirements of section 175A of
the CAA.
EPA also proposes to determine that the Libby Area has met the
requirements for redesignation under section 107(d)(3)(E) of the CAA.
This proposed rulemaking is in response to Montana's June 24, 2020
redesignation request and associated SIP submission that address the
requirements described in section 107(d)(3)(E) of the CAA for the
redesignation of the Libby Area from nonattainment to attainment for
the 1997 annual PM2.5 NAAQS.\2\
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\2\ See Libby Area SIP submission, available in the docket for
this proposed rulemaking.
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II. What is the background for EPA's proposed actions?
A. The PM2.5 NAAQS
Particulate matter includes particles with diameters that are
generally 2.5 microns or smaller (PM2.5) and particles with
diameters that are generally 10 microns or smaller (PM10).
PM2.5 contributes to effects that are harmful to human
health and the environment, including premature mortality, aggravation
of respiratory and cardiovascular disease, decreased lung function,
visibility impairment, and damage to vegetation and ecosystems.
Individuals particularly sensitive to PM2.5 exposure include
older adults, people with heart and lung disease, and children. See 78
FR 3086 at 3088 (January 15, 2013). PM2.5 can be emitted
directly into the atmosphere as a solid or liquid particle (``primary
PM2.5'' or ``direct PM2.5'') or can be formed in
the atmosphere (``secondary PM2.5'') as a result of various
chemical reactions among precursor pollutants such as nitrogen oxides
(NOX), sulfur oxides (SOX), volatile organic
compounds (VOCs), and ammonia (NH3).\3\
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\3\ EPA, Air Quality Criteria for Particulate Matter, No. EPA/
600/P-99/002aF and EPA/600/P-99/002bF, October 2004.
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Under section 109 of the CAA, EPA has established national ambient
air quality standards for certain pervasive air pollutants (referred to
as ``criteria pollutants'') and conducts periodic reviews of the NAAQS
to determine whether they should be revised or whether new NAAQS should
be established. EPA sets the NAAQS for criteria pollutants at levels
required to protect public health and welfare.\4\
[[Page 74579]]
PM2.5 is one of the ambient pollutants for which EPA has
established health-based standards.
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\4\ For a given air pollutant, ``primary'' national ambient air
quality standards are those determined by EPA as requisite to
protect the public health. ``Secondary'' standards are those
determined by EPA as requisite to protect the public welfare from
any known or anticipated adverse effects associated with the
presence of such air pollutant in the ambient air. CAA section
109(b).
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On July 18, 1997 (62 FR 38652), EPA revised the NAAQS for
particulate matter to add new standards for PM2.5. The
Agency established primary and secondary annual and 24-hour standards
for PM2.5. The annual standard was set at 15.0 micrograms
per meter cubed ([micro]g/m\3\) based on a 3-year average of annual
mean PM2.5 concentrations, and the 24-hour (daily) standard
was set at 65 [micro]g/m\3\ based on the 3-year average of the annual
98th percentile values of 24-hour PM2.5 concentrations at
each population-oriented monitor within an area.\5\
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\5\ The primary and secondary standards were set at the same
level for both the 24-hour and the annual PM2.5
standards.
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On October 17, 2006 (71 FR 61144), EPA retained the annual average
NAAQS at 15.0 [micro]g/m\3\ but revised the level of the 24-hour
PM2.5 NAAQS to 35 [micro]g/m\3\ based on a 3-year average of
the annual 98th percentile values of 24-hour concentrations.\6\
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\6\ Under EPA regulations at 40 CFR part 50, the primary and
secondary 2006 24-hour PM2.5 NAAQS are attained when the
annual arithmetic mean concentration, as determined in accordance
with 40 CFR part 50, appendix N, is less than or equal to 35
[micro]g/m\3\ at all relevant monitoring sites in the subject area,
averaged over a 3-year period.
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On December 14, 2012, EPA promulgated the 2012 PM2.5
NAAQS, including a revision of the annual standard to 12.0 [micro]g/
m\3\ based on a 3-year average of annual mean PM2.5
concentrations. The Agency maintained the 24-hour standard of 35
[micro]g/m\3\ based on a 3-year average of the 98th percentile of 24-
hour concentrations. See 78 FR 3086 (January 15, 2013).
B. Designation of PM2.5 NAAQS Nonattainment Areas
Following promulgation of a new or revised NAAQS, EPA is required
by CAA section 107(d) to designate areas throughout the nation as
attaining or not attaining the NAAQS. On January 5, 2005 (70 FR 944),
EPA published area designations for the 1997 PM2.5 NAAQS
based on air quality data for the calendar years 2001-2003. In that
rulemaking, EPA designated Libby, Montana as nonattainment for the 1997
annual PM2.5 NAAQS. These designations became effective on
April 5, 2005.
On March 17, 2011 (76 FR 14584), EPA approved Montana's attainment
plan which included an attainment demonstration, an analysis of
reasonable available control technology/reasonable available control
measure (RACT/RACM), base-year and projection year inventories, and
contingency measures for the 1997 PM2.5 NAAQS for the Libby
Area. On July 14, 2015 (80 FR 40911), EPA finalized its determination
that the Libby Area attained the 1997 annual PM2.5 NAAQS by
the Area's statutory attainment date of December 31, 2011. This
determination was based upon quality-assured and certified ambient air
monitoring data for the 2007-2009 monitoring period that demonstrated
that the Libby Area attained the 1997 annual PM2.5 NAAQS by
the attainment date. In the same rulemaking, EPA also issued a clean
data determination under the Agency's Clean Data Policy \7\ based upon
quality-assured and certified ambient air monitoring data that
demonstrated the Libby Area continued to attain the 1997 annual
PM2.5 NAAQS based on 2012-2014 monitoring data.\8\
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\7\ See e.g., 70 FR 71612 (November 29, 2005) and 72 FR 20586
(April 25, 2007).
\8\ See 71 FR 19935 (April 14, 2015) that addresses the final
clean data determination and a final determination of attainment by
the attainment date for the Libby nonattainment area. As part of its
clean data determination submission to EPA, Montana submitted the
clean data determination to address the national ambient air
requirements under Subpart 4.
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On July 29, 2016, EPA issued a rule entitled ``Fine Particulate
Matter National Ambient Air Quality Standards: State Implementation
Plan Requirements'' (``PM2.5 SIP Requirements Rule''). See
81 FR 58010 (August 24, 2016). This rule clarifies how states should
meet the statutory SIP requirements that apply to areas designated
nonattainment for any PM2.5 NAAQS under Subparts 1 and 4. It
does so by establishing regulatory requirements and by providing
guidance that is applicable to areas that are currently designated
nonattainment for existing PM2.5 NAAQS and areas that are
designated nonattainment for any PM2.5 NAAQS in the future.
In addition, the rule responds to the D.C. Circuit's remand of the 1997
PM2.5 Implementation Rules. As a result, the requirements of
the rule also govern future actions associated with states' ongoing
implementation efforts for the 1997 and 2006 PM2.5 NAAQS. In
the PM2.5 SIP Requirements Rule, EPA revoked the 1997
primary annual PM2.5 NAAQS in areas that had always been
attainment for that NAAQS, and in areas that had been designated as
nonattainment but that were redesignated to attainment before October
24, 2016, the PM2.5 SIP Requirements Rule effective date.
See 81 FR 58010 (August 24, 2016).
In the August 24, 2016 final rule, EPA also finalized a provision
to revoke the 1997 primary annual PM2.5 NAAQS in areas
redesignated to attainment after October 24, 2016, on the effective
date of an area's redesignation. See 40 CFR 50.13(d). If this proposal
is finalized, the 1997 primary annual PM2.5 NAAQS will be
revoked for the Libby Area on the effective date of the redesignation.
Beginning on that date, the Area will no longer be subject to
transportation or general conformity requirements for the 1997 annual
PM2.5 NAAQS due to revocation of the primary NAAQS. See 81
FR 58125-6. If redesignated, the Libby Area will be required to
implement the maintenance plan requirements under section 175A for the
1997 annual PM2.5 NAAQS, and the prevention of significant
deterioration (PSD) program for the 1997 annual PM2.5 NAAQS.
Once approved, the maintenance plan can only be revised if the revision
meets the requirements of CAA section 110(l) and, if applicable, CAA
section 193. As described in the PM2.5 SIP Requirements
Rule, those 1997 annual PM2.5 maintenance areas with a
revoked NAAQS are no longer required to submit a second 10-year
maintenance plan for the 1997 annual PM2.5 NAAQS. See 81 FR
58144.
C. PM2.5 NAAQS Nonattainment Area Planning Requirements
The CAA establishes the requirements for redesignation of an area
from nonattainment to attainment. Specifically, section 107(d)(3)(E)
allows for redesignation of areas from nonattainment to attainment
provided that the following criteria are met:
(1) The Administrator has determined that the area has attained the
applicable NAAQS;
(2) The Administrator has fully approved the applicable SIP for the
area under section 110(k) of the CAA;
(3) The Administrator has determined that the improvement in air
quality is due to permanent and enforceable reductions in emissions;
(4) The Administrator has fully approved a maintenance plan for the
area as meeting the requirements of section 175A of the CAA; and
(5) The state containing the area has met all requirements
applicable to the area under section 110 and part D of the CAA.
Section 110 of the CAA identifies a comprehensive list of elements
that SIPs must include, and part D establishes the SIP requirements for
nonattainment areas. The generally applicable nonattainment SIP
requirements are found in part D, subpart 1, and the particulate
matter-specific SIP
[[Page 74580]]
requirements are found in part D, subpart 4.
On April 16, 1992 (57 FR 13498), EPA provided guidance on
redesignation in the General Preamble for the Implementation of Title I
of the CAA Amendments of 1990, and the Agency supplemented this
guidance on April 28, 1992 (57 FR 18070). EPA has provided further
guidance on processing redesignation requests in the following
documents:
1. ``Procedures for Processing Requests to Redesignate Areas to
Attainment,'' Memorandum from John Calcagni, Director, Air Quality
Management Division, September 4, 1992 (hereinafter referred to as
the ``Calcagni Memorandum'');
2. ``State Implementation Plan (SIP) Actions Submitted in
Response to Clean Air Act (CAA) Deadlines,'' Memorandum from John
Calcagni, Director, Air Quality Management Division, October 28,
1992; and
3. ``Part D New Source Review (Part D NSR) Requirements for
Areas Requesting Redesignation to Attainment,'' Memorandum from Mary
D. Nichols, Assistant Administrator for Air and Radiation, October
14, 1994 (hereinafter referred to as the ``Nichols Memorandum'').
D. Limited Maintenance Plans
CAA section 175A(a) requires that nonattainment areas seeking
redesignation to attainment submit ``a revision of the applicable state
implementation plan to provide for the maintenance of the [NAAQS] for
such air pollutant in the area concerned for at least 10 years after
the redesignation.'' EPA explained in the Calcagni Memorandum that
states may meet this requirement to ``provide for the maintenance of
the NAAQS'' by using projected emissions inventories or air quality
modeling showing continued maintenance until the end of the relevant
maintenance period. See Calcagni Memorandum at 9-11. EPA clarified in
three subsequent guidance memos that certain areas could meet the CAA
section 175A requirement to provide for maintenance by demonstrating
that the area's design value was well below the NAAQS and that the
historical stability of the area's air quality levels showed that the
area was unlikely to violate the NAAQS in the future.\9\ The Agency
refers to this streamlined demonstration of maintenance as a limited
maintenance plan.
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\9\ See ``Limited Maintenance Plan Option for Nonclassifiable
Ozone Nonattainment Areas'' from Sally L. Shaver, Office of Air
Quality Planning and Standards (OAQPS), dated November 16, 1994;
``Limited Maintenance Plan Option for Nonclassifiable CO
Nonattainment Areas'' from Joseph Paisie, OAQPS, dated October 6,
1995; Copies of these guidance memoranda can be found in the docket
for this proposed rulemaking.
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EPA has interpreted CAA section 175A as permitting this option
because section 175A does not define how areas may demonstrate
maintenance, and in EPA's experience with implementing the various
NAAQS, areas that qualify for an LMP and have approved LMPs, have
rarely, if ever, experienced subsequent violations of the NAAQS. As
noted in the LMP guidance memoranda, states seeking an LMP must still
submit the other maintenance plan elements outlined in the Calcagni
Memorandum, including an attainment emissions inventory, provisions for
the continued operation of the ambient air quality monitoring network,
verification of continued attainment, and a contingency plan in the
event of a future violation of the NAAQS. Moreover, states seeking to
do an LMP must still submit a CAA section 175A maintenance plan as a
revision to the SIP, with all attendant notice and comment procedures.
While the LMP guidance memoranda were originally written with respect
to certain NAAQS,\10\ EPA has extended the LMP interpretation of
section 175A to other NAAQS and pollutants not specifically covered by
the previous guidance memos.\11\
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\10\ The prior memos addressed unclassifiable areas under the 1-
hour ozone NAAQS, nonattainment areas for the PM10 NAAQS,
and nonattainment areas for the carbon monoxide NAAQS.
\11\ See, e.g., 79 FR 41900 (July 18, 2014) (approval of second
ten-year LMP for Grant County 1971 sulfur dioxide maintenance area).
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To determine the LMP eligibility criteria for the Libby Area, EPA
is interpreting the requirements as described in the 2001 memorandum
from Lydia Wegman \12\ regarding LMPs for PM10 areas as
applying to PM2.5. This memorandum states that one way for a
PM10 area to qualify for an LMP is to show that the area's
average design value (ADV) (based upon the most recent 5 years of
monitoring data) is at or below the critical design value (CDV). The
memorandum defines the CDV as an indicator of the likelihood of future
violations of the NAAQS in an area given the area's current ADV and its
historical variability and provides a means for calculating the CDV for
an area (or monitoring site) (Attachment A of the 2001 Wegman
Memorandum). The CDV is the highest average design value an area could
have before it may experience a future violation of the NAAQS with a
certain probability--in the case of the Wegman Memorandum, a
probability of 1 in 10. Therefore, if an area's current ADV is less
than the area's CDV, that area has a less than 1 in 10 chances of
violating the NAAQS in the future. As noted in Attachment A of the
Wegman Memorandum, the CDV calculation was designed to apply for any
NAAQS pollutant and is not specific to PM10. Montana
employed this methodology to demonstrate that the Libby Area is
eligible for an LMP and that the plan therefore provides for
maintenance of the NAAQS for 10 years following redesignation. We agree
that the State's demonstration meets the requirements of CAA section
175A and shows that the Area will continue to maintain the annual
PM2.5 NAAQS following redesignation through 2031. In its SIP
submission, Montana used a site-specific CDV calculated with
PM2.5 data from the one ambient design value monitor in the
Libby Area.
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\12\ ``Limited Maintenance Plan Option for Moderate
PM10 Nonattainment Areas'' from Lydia Wegman, OAQPS,
dated August 9, 2001 (hereinafter referred to as the ``Wegman
Memorandum''). A copy of this guidance memorandum can be found in
the docket for this proposed rulemaking.
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The 2001 Wegman Memorandum also provided that an LMP was
appropriate only for those PM10 areas that were expecting
limited growth of on-road motor vehicle emissions (including fugitive
dust), and therefore included a motor vehicle regional emissions
analysis demonstration that states seeking a PM10 LMP should
perform (Attachment B to the Wegman Memorandum). According to the
Wegman Memorandum, the demonstration should show that the ADV remains
below the margin of safety provided for in the memorandum, even after
the growth of on-road motor vehicle emissions is considered. This
proposed rulemaking uses the site-specific CDV instead of the margin of
safety described in the Wegman Memorandum for this analysis as EPA has
not recommended a margin of safety for the 1997 annual PM2.5
NAAQS.
III. Why is EPA proposing these actions?
On June 24, 2020, the State of Montana requested that EPA
redesignate the Libby Area to attainment for the 1997 annual
PM2.5 NAAQS and submitted an associated SIP revision
containing an LMP. EPA's evaluation of the plan and air quality data
indicates that the Libby Area meets the requirements for redesignation
set forth in section 107(d)(3)(E) of the CAA, including that the LMP
fulfills the maintenance plan requirements under section 175A of the
CAA. As a result of these findings, EPA is proposing to take the
separate but related actions to approve the LMP and redesignate the
[[Page 74581]]
Libby Area from nonattainment to attainment.
IV. What is EPA's analysis of the request?
To redesignate an area from nonattainment to attainment, the CAA
requires EPA to determine that the area has attained the applicable
NAAQS (CAA section 107(d)(3)(E)(i)). The criteria for determining if an
area is attaining the 1997 annual PM2.5 NAAQS is set out in
40 CFR 50.13 and 40 CFR part 50, appendix N. The 1997 annual
PM2.5 primary and secondary standards are met when the
annual design value \13\ at each eligible monitoring site within the
area is less than or equal to 15.0 [micro]g/m\3\.
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\13\ The Annual PM2.5 NAAQS design value is the 3-
year average of PM2.5 annual mean mass concentrations.
These annual means are calculated as the weighted arithmetic mean of
the four quarters of valid data at the site and the annual means are
only considered valid when they meet data completeness requirements
detailed in 40 CFR 50.13. Once three valid annual means are
available, they can be averaged together to determine the annual
design value for that site.
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Based on data from 2007-2009, EPA determined that the Libby Area
attained the 1997 annual PM2.5 standard by December 31,
2011, well before its attainment date of July 14, 2015.\14\ In
addition, EPA issued a final clean data determination under the Clean
Data Policy that the Libby Area was attaining the 1997 annual
PM2.5 NAAQS, based on quality-assured and certified ambient
air quality data for the 2012-2014 monitoring period. The Libby Area
has continued to attain the 1997 annual PM2.5 NAAQS since
EPA's earlier determinations that the Area attained the NAAQS.
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\14\ See 80 FR 40911.
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The Libby Area has one State and Local Air Monitoring Station
(SLAMS) monitor operated by the Montana Department of Environmental
Quality (MDEQ). This monitor (Air Quality System (AQS) Site ID 30-53-
0018) has complete data for 2014-2021, which is the period of data
utilized for this proposed redesignation.\15\
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\15\ The criteria for determining if an area is attaining the
1997 Annual PM2.5 NAAQS are set out in the 40 CFR 50.13
and 40 CFR part 50, appendix N. Three years of valid annual means
are required to produce a valid annual standard design value. A year
meets data completeness requirements when at least 75 percent of the
scheduled sampling days for each quarter have valid data.
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Table 1 summarizes the annual mean PM2.5 data collected
from 2014-2021 for the Libby Area.\16\ Table 2 shows the annual design
values for 2016-2021. The data presented in the tables were calculated
from all data available in AQS, including those data flagged by the
State of Montana as potentially influenced by exceptional events. EPA
deems these data valid as they are complete and have been certified by
MDEQ.
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\16\ The annual averages in Table 1 are calculated by averaging
the four quarters of data.
\17\ Annual mean concentration is the averaging of four complete
quarters of data for each year. See 40 CFR part 50, appendix N.
\18\ The Annual PM2.5 NAAQS design value is the 3-
year average of PM2.5 annual mean mass concentrations.
See 40 CFR 50.13.
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None of the annual design values from 2016-2021 from the Libby Area
monitoring site exceed the 1997 annual PM2.5 NAAQS of 15.0
[micro]g/m\3\, and as such, EPA proposes to determine that the Libby
Area has attained the 1997 annual PM2.5 NAAQS, and therefore
meets the requirement of CAA section 107(d)(3)(E)(i).
Table 1--PM2.5 One-Year Annual Mean Concentrations \17\
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Year: 2014 2015 2016 2017 2018 2019 2020 2021
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Concentration ([micro]g/m\3\)... 9.3 14.9 9.8 14.3 14.6 11.4 13.8 14.6
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Table 2--PM2.5 Annual Design Value \18\
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3-Year Period: 2014-2016 2015-2017 2016-2018 2017-2019 2018-2020 2019-2021
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Design Value ([micro]g/m\3\) 11.4 13.0 12.9 13.4 13.3 13.3
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A. Has the State met all applicable requirements under section 110 and
part D of the Clean Air Act (CAA) and have those requirements been
fully approved? (CAA sections 107(d)(3)(E)(ii) and (v))
Sections 107 (d)(3)(E)(ii) and (v) require EPA to determine that
the area has a fully approved applicable SIP under section 110(k) that
meets all the basic applicable requirements under section 110 and part
D for purposes for redesignation. The following is a summary of how
Montana meets these requirements.
1. CAA Section 110 Requirements
Section 110(a)(2) of title I of the CAA delineates the general
requirements for a SIP, which include enforceable emissions limitations
and other control measures, means or techniques, provisions for the
establishment and operation of appropriate devices necessary to collect
data on ambient air quality, and programs to enforce limitations. The
general SIP elements and requirements set forth in CAA section
110(a)(2) include, but are not limited to the following:
Submittal of a SIP that has been adopted by the state
after reasonable public notice and hearing;
Provisions for establishment and operation of appropriate
procedures needed to monitor ambient air quality;
Implementation of a source permit program;
Provisions for the implementation of part C requirements
(PSD);
Provisions for the implementation of part D requirements
for NSR permit programs;
Provisions for air pollution modeling; and
Provisions for public and local air agency participation
in planning and emission control rule development.
CAA section 110(a)(2)(D) requires that SIPs contain certain
measures to prevent sources in a state from significantly contributing
to air quality problems in another state; the portion of a state's SIP
that include these measures is known as an interstate transport SIP.
However, these CAA section 110(a)(2)(D) requirements apply to a state
and are not linked with a particular nonattainment area's designation
and classification in that state. The interstate transport SIP
submittal requirements, where applicable, continue to apply to a state
regardless of the designation of any one area in the state. Thus, EPA
has determined that these requirements are not applicable requirements
for purposes of redesignation. Instead, EPA has determined that the
requirements
[[Page 74582]]
linked with a particular nonattainment area's designation and
classifications are the relevant measures, i.e., the requirements that
must be met, for EPA to redesignate an area.
In addition, EPA has determined that the other CAA section
110(a)(2) elements not connected with nonattainment plan submissions
and not linked with an area's attainment status are not applicable
requirements for purposes of redesignation because the area will still
be subject to these requirements after it is redesignated. EPA
concludes that the CAA section 110(a)(2) and part D requirements, which
are linked with a particular area's designation and classification, are
the relevant measures to evaluate in reviewing a redesignation request,
and that section 110(a)(2) elements not linked to the area's
nonattainment status are not applicable for purposes of redesignation.
EPA has applied this interpretation consistently in many
redesignations.\19\
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\19\ See, e.g., 81 FR 4420 (July 17, 2006) (final redesignation
for the Sullivan County, Tennessee area); 79 FR 43655 (July 28,
2014) (final redesignation for Bellefontaine, Ohio lead
nonattainment area); 61 FR 53174-53176 (October 10, 1996) and 62 FR
24826 (May 7 1997) (proposed and final redesignation of Reading,
Pennsylvania ozone nonattainment area); 61 FR 20458 (May 7 1996)
(final redesignation for Cleveland-Akron-Lorain, Ohio ozone
nonattainment area); 60 FR 62748 (December 7, 1995) (final
redesignation of Tampa, Florida ozone nonattainment area); See also
65 FR 37879, 37890, (June 19, 2000) (discussing this issue in final
redesignation of Cincinnati, Ohio 1-hour ozone nonattainment area);
and 66 FR 50399 (October 19, 2001) (final redesignation of
Pittsburg, Pennsylvania 1-hour ozone nonattainment area).
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EPA's review of the Montana SIP shows that the State has satisfied
the general SIP requirements under section 110(a)(2) of the CAA, to the
extent they are applicable for the purposes of redesignation. Moreover,
EPA has previously approved provisions of Montana's SIP as
demonstrating compliance with the CAA section 110(a)(2) requirements
for the 1997 annual PM2.5 NAAQS. See 78 FR 45864 (July 30,
2013). Therefore, EPA proposes to determine that MDEQ has met all
general SIP requirements for the Libby Area that are applicable for
purposes of redesignation under section 110 of the CAA.
2. Part D Requirements
Subparts 1 and 4 of part D, title 1 of the CAA contain air quality
planning requirements for PM2.5 nonattainment areas. Subpart
1 contains general requirements for all nonattainment areas of any
pollutant, including PM2.5, governed by a NAAQS. Subpart 1
requirements include, among other things, provisions for RACM, RFP,
emissions inventories, contingency measures, transportation conformity
and general conformity. Subpart 4 contains specific planning and
scheduling requirements for PM2.5 nonattainment areas.
Sections 189(a), (c), (e) requirements apply specifically to Moderate
PM2.5 nonattainment areas and include an approved permit
program for construction of new and modified major stationary sources,
provisions for RACM, an attainment demonstration, quantitative
milestones demonstrating RFP toward attainment by the applicable
attainment date, and provisions to ensure that the control requirements
applicable to major stationary sources of PM2.5 precursors,
except where the Administrator has determined that such sources do not
contribute significantly to PM2.5 levels that exceed the
NAAQS in the area.
We address the applicability of these requirements to this action
in the following sections.
3. Subpart 1, Section 172 Requirements
Section 172(c) contains general requirements for nonattainment area
plan provisions. A thorough discussion of these requirements may be
found in the General Preamble. See 57 FR 13538 (April 16, 1992). EPA's
longstanding interpretation is that certain planning requirements
designed to get a nonattainment area to attainment of the NAAQS are not
``applicable'' for purposes of CAA section 107(d)(3)(E)(ii) and (v) and
therefore need not be approved into the SIP before EPA can redesignate
the area. In the General Preamble, EPA set forth its interpretation of
applicable requirements for purposes of evaluating redesignation
requests when an area is attaining the standard. See 57 FR 13564. EPA
noted that requirements for RFP and other measures designed to provide
for an area's attainment do not apply in evaluating redesignation
because those nonattainment planning requirements ``have no meaning''
for an area that is attaining the standard. Id. This interpretation is
also set forth in the Calcagni Memorandum.
EPA's understanding of CAA section 172 also forms its basis on its
Clean Data Policy. Under the Clean Data Policy, EPA promulgates a
determination of attainment, published in the Federal Register, which
is subject to notice-and-comment rulemaking, and this determination
formally suspends a state's obligation to submit most of the attainment
planning requirements that would otherwise apply, including an
attainment demonstration and planning SIPs to provide for RFP, RACM,
and contingency measures under CAA section 179(c)(9). The Clean Data
Policy has been codified in regulations regarding the implementation of
the ozone and PM2.5 NAAQS. See e.g., 70 FR 71612 (November
29, 2005) and 72 FR 20586 (April 25, 2007).
Because the Libby Area is attaining the 1997 annual
PM2.5 NAAQS, the attainment planning obligations in CAA
section 172, including the requirement to submit an attainment
demonstration and RACM (172(c)(1)), RFP (172(c)(2)), and contingency
measures (172(c)(9)) are not considered ``applicable'' requirements for
redesignation purposes under CAA section 107(d)(3)(E)(ii) and (v). In
any case, Montana submitted these elements as part of the Moderate SIP
requirements on March 26, 2008, and EPA approved them on March 17,
2011.\20\
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\20\ See 76 FR 14584.
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Section 172(c)(3) of the CAA requires a comprehensive, accurate,
current inventory of actual emissions from all sources of relevant
pollutant(s) in nonattainment areas. EPA's March 17, 2011 approval of
Montana's March 26, 2008 SIP submission included a 2005 base-year
emissions inventory for the Libby Area. Montana also included an
emissions inventory for calendar year 2014 with the June 24, 2020 SIP
submittal of the LMP for the Libby Area. The 2001 Wegman Memorandum
states that an attainment inventory should represent emissions during
the same 5-year period associated with the air quality data used to
determine that the area meets the requirements of the LMP option. In
addition, EPA reviewed an updated 2017 emissions inventory \21\ in its
analysis for the Libby PM2.5 LMP.
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\21\ Available in the docket for this proposed rulemaking.
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Section 172(c)(4) requires the identification and quantification of
allowable emissions for major new and modified stationary sources in an
area, and section 172(c)(5) and 189(a)(1)(A) requires source permits
for the construction and operation of new and modified major stationary
sources anywhere in the nonattainment area. EPA approved the current
Montana NSR program for PM2.5 on July 18, 1995. See 60 FR
36715. Having a fully approved nonattainment NSR program is not an
applicable requirement for this action; nonetheless we have approved
the State's program.\22\
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\22\ A detailed rationale for this view is described in the
memorandum from Mary Nichols, Assistant Administrative for Air and
Radiation, dated October 14, 1994, entitled, ``Part D New Source
Review Requirements for Areas Requesting Redesignation to
Attainment.''
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Section 172(c)(7) requires the SIP meet the applicable provisions
of CAA
[[Page 74583]]
section 110(a)(2). EPA believes Montana's June 24, 2020 SIP submission
pertaining to the Libby Area meets the requirements of section
110(a)(2).
4. Subpart 1, Section 176 Conformity Requirements
Section 176(c) of the CAA requires states to establish the criteria
and procedures to ensure that federally supported or funded projects
conform to the air quality planning goals in the applicable SIP. The
requirement to determine conformity applies to transportation plans,
programs and projects that are developed, funded, or approved under
title 23 of the United States Code (U.S.C.) and the Federal Transit Act
(transportation conformity) as well as to other federally supported or
funded projects (general conformity). State transportation conformity
SIP revisions must be consistent with federal conformity regulations
relating to consultation, enforcement, and enforceability that EPA
promulgated pursuant to its authority under the CAA.
Although EPA interprets the conformity SIP requirements \23\ as not
applying for purposes of evaluating the redesignation request under
section 107(d)(3) \24\ we note that Montana has an approved conformity
SIP. See 66 FR 48561 (September 21, 2001).
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\23\ CAA section 176(c)(4)(E) requires states to submit
revisions to their SIPs to reflect certain federal criteria and
procedures for determining transportation conformity.
\24\ EPA believes that this interpretation is reasonable because
state conformity rules are still required after redesignation and
federal conformity rules apply where states rules have not been
approved. See Wall v. EPA, 265 F.3d 426 (6th Cir., 2001) (upholding
this interpretation); 60 FR 62748 (December 7, 1995).
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5. Subpart 4 Requirements
As discussed in Section I of this document, in NRDC v. EPA, the
D.C. Circuit held that EPA should have implemented the 1997
PM2.5 annual NAAQS pursuant to the particulate matter-
specific provisions of Subpart 4. On remand, EPA identified all areas
designated nonattainment for either the 1997 or the 2006
PM2.5 NAAQS, including the Libby Area, as Moderate
nonattainment for purposes of Subpart 4 in the Classifications and
Deadlines Rule. Moderate nonattainment areas are subject to the
requirements of CAA sections 189(a), (c), and (e), including: (1) an
approved permit program for construction of new and modified major
stationary sources (section 189(a)(1)(A)); (2) an attainment
demonstration, (section 189(a)(1)(B)); (3) provisions for RACM (section
189(a)(1)(C)); (4) quantitative milestones demonstrating RFP toward
attainment by the applicable attainment date (section 189(c)); and (5)
precursor control (section 189(e)).
With respect to the specific attainment planning requirements under
Subpart 4,\25\ EPA applies the same interpretation that it applies to
attainment planning requirements under Subpart 1 or any other
pollutant-specific subparts. That is, under its long-standing
interpretation of the CAA, where an area is already attaining the
standard, EPA does not consider those attainment planning requirements
to be applicable for purposes of evaluating a request for
redesignation, that is, CAA section 107(d)(3)(E)(ii) or (v), because
requirements that are designed to help an area achieve attainment no
longer have meaning where an area is already meeting the standard. EPA
is therefore proposing to determine that the specific attainment
planning requirements under Subpart 4 are not applicable for evaluating
Montana's redesignation request.
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\25\ These planning requirements include the attainment
demonstration, qualitative milestone requirements, and RACM
analysis.
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CAA section 189(e) provides that control requirements for major
stationary sources of direct PM10 (including
PM2.5) shall also apply to particulate matter precursors
from those sources, except where EPA determines that major stationary
sources of such precursors do not contribute significantly to
PM10 levels that exceed the standard in the area. The CAA
does not explicitly address whether it would be appropriate to include
a potential exemption from precursor controls for all source categories
under certain circumstances. In implementing Subpart 4 with regard to
controlling PM10, EPA permitted states to determine that a
precursor was ``insignificant'' where the state could show in its
attainment plan that it would expeditiously attain without adoption of
emission reduction measures aimed at that precursor. This approach was
upheld in the Association of Irritated Residents v. EPA, 423 F.3d 989
(9th Cir. 2005) and extended to PM2.5 implementation in the
PM2.5 SIP Requirements Rule. A state may develop its
attainment plan and adopt RACM that target only those precursors that
are necessary to control for purposes of timely attainment. See 81 FR
58010 at 58020 (August 24, 2016).
For the Libby Area, a precursor exemption analysis under section
189(e) and EPA's implementing regulations is not an applicable
requirement that needs to be fully approved in the context of a
redesignation under CAA section 107(d)(3)(E)(ii) since the Area is
already in attainment which demonstrates that precursors contribution
is insignificant. Therefore, measures aimed at the precursors are not
needed.
As discussed previously in this document, for areas that are
attaining the standard, EPA does not interpret attainment planning
requirements of Subparts 1 and 4 to be applicable requirements for
purposes of redesignating an area to attainment. On July 14, 2015, EPA
approved that the Libby Area had attained the 1997 annual
PM2.5 NAAQS by the Area's statutory attainment date. The
Libby Area has expeditiously attained the 1997 annual PM2.5
NAAQS, and therefore, no additional controls of any pollutant,
including any PM2.5 precursor, are necessary to bring it
into attainment. In section V of this document, we find that the Libby
Area continues to attain the NAAQS. EPA has determined that the Libby
Area has attained the standard due to permanent and enforceable
emissions reductions. Further, as set forth in section IV.C of this
document, we believe that the Libby PM2.5 LMP demonstrates
continued maintenance of the 1997 annual PM2.5 NAAQS
standard through 2031 which also demonstrates that the PM2.5
precursors are insignificant. Taken together, these factors support our
conclusion that PM2.5 precursors are adequately
controllable.
B. Has the state demonstrated that air quality improvement is due to
permanent and enforceable reductions?
In order to approve a redesignation from nonattainment to
attainment, section 107(d)(3)(E)(iii) of the CAA requires EPA to
determine that the improvement in air quality is due to emission
reductions that are permanent and enforceable, and that the improvement
results from the implementation of the applicable SIP and applicable
federal air pollution control regulations and other permanent and
enforceable regulations. Under this criterion, a state must be able to
reasonably attribute the improvement in air quality to emissions
reductions that are permanent and enforceable. Attainment resulting
from temporary reductions in emission rates (e.g., reduced production
or shutdown due to temporary adverse economic conditions) or unusually
favorable meteorology would not qualify as an air quality improvement
due to permanent and enforceable emission reductions. See Calcagni
Memorandum at 4. In its demonstration that improvements in air quality
are reasonably attributable to emissions reductions that are permanent
[[Page 74584]]
and enforceable, Montana evaluated several factors: \26\ the
composition of PM2.5 in the nonattainment area; control
measures that have been implemented since the area was redesignated to
nonattainment; changes to the emissions inventory over time; and
meteorological and economic trends. In its evaluation, Montana
identified two fugitive area sources contributing to PM2.5
concentrations in the nonattainment area: wood combustion and tailpipe
emissions. Eighty-two percent of the PM2.5 concentrations
during the baseline study year of 2005 was attributed to wood
combustion. Wood combustion impacts represented both residential and
small commercial space heating, and outdoor burns. The State identified
emission reductions from only the wood combustion category in the
attainment plan; the plan did not take credit for reductions from
mobile source tailpipe emissions due to federal tailpipe standards or
fleet turnover.
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\26\ See Montana's attainment plan for the Libby Area, approved
on March 17, 2011 (76 FR 14584).
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In its approved Moderate nonattainment plan, Montana adopted
permanent and enforceable rules from the Lincoln County Air Pollution
Control Program. This program includes rules that reduce
PM2.5 impacts in the nonattainment area resulting in
attainment of PM2.5 NAAQS.\27\ The air pollution control
rules in Chapter 1, Subchapters 1 through 4 of the Lincoln County Air
Pollution Control Program, address solid fuel burning devices, re-
entrained road dust control, and outdoor burning regulations. These
rules are part of the Lincoln County Health Department's Health and
Environmental Rules in Chapter 1. The rules contain the following
subchapters, all designed to help Lincoln County attain the
PM2.5 NAAQS:
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\27\ See Section 1.3 in the Libby Area SIP submission. Available
in the docket for this proposed rulemaking.
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Subchapter 1--(75.1.100-106)--General Provisions;
Subchapter 2--(75.1.200-206,208)--Solid Fuel Burning
Device Regulations;
Subchapter 3--(75.1.301-308)--Dust Control Regulations;
and
Subchapter 4--(75.1.401-408)--Outdoor Burning Regulations.
The regulations in Lincoln County's Subchapter 2 require that solid
fuel burning devices be permitted by the Lincoln County Environmental
Health Department. The regulations restrict the material allowed for
combustion and prohibit visible emissions greater than 20 percent
opacity. Lincoln County will call Air Pollution Alerts \28\ when
particulate matter concentrations are more than 80 percent of the 24-
hour standard and at that time, solid fuel burning devices are not
allowed to operate unless the device has received an exemption. A
provision allows exempt devices to be operated during an alert, but
only with an opacity of 10 percent or less.
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\28\ See 75.1.206, Lincoln County Air Pollution Control Program.
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Although re-entrained road dust is not an identified emission
source category, Subchapter 3 of the Lincoln County rules address re-
entrained dust from roads, parking lots and commercial lots by
requiring dust abatement and control. These road dust regulations apply
within the regulated road sanding and sweeping district as defined in
the regulation. Vehicular operations within the district are only
allowed on paved surfaces within the district. To control ice on the
roads, liquid de-icing agents and de-icing salts should be used.
Sanding material is not allowed unless the Lincoln County Environmental
Health Department declares an emergency and then only sanding material
that meets specific durability, abrasion, and fine concentrations are
allowed. Roads are to be maintained using a schedule of prioritized
street sweeping and flushing to remove carry-on or applied materials.
Commercial operations shall also implement measures to prevent
depositing material on yards/lots, suppress dust, and clean adjoining
roadways.
Lincoln County's Subchapter 4 addresses outdoor burning and
restricts non-essential outdoor burning, promoting alternative disposal
methods and recycling, and setting standards to minimize emissions when
outdoor burning is necessary. These rules apply to both the air
pollution control district which is the same area as the Libby
nonattainment area, and the Impact Zone L, which extends beyond the
nonattainment area. The rules specify which materials and activities
are prohibited for outdoor burning. Residential outdoor burning is only
allowed in the month of April while management burns are allowed from
April through October. Burning outside these months requires additional
approval from the Lincoln County Health Department. Burners must obtain
a burn permit from the Department and may only conduct their burn if
meteorological conditions have good air dispersion characteristics, as
determined by the Department.
Montana has determined that most of the emissions reductions from
the wood combustion source category are attributed to the Lincoln
County residential wood combustion rules. These rules control
residential and small commercial wood combustion used for space heating
through a wood stove permit program. The rules restrict the
installation and operation of wood stoves to times with good air
quality dispersion. Lincoln County also has outdoor open burning rules
that require burns to be permitted and approved to ensure the burns
occur during favorable meteorological conditions.
Montana evaluated emissions from residential wood burning
contributing to PM2.5 in Libby, Montana. Table 2.3 in the
June 24, 2020 Libby Area SIP submission displays the 2005 actual annual
emissions, which are considered the annual baseline emissions for
Libby. Additionally, the table shows the annual emissions from the 2014
National Emissions Inventory (NEI). As shown in the Table 2.3,
emissions for residential wood burning in 2014 have decreased more than
85 percent compared to the baseline emissions in 2005. The total
emissions for area source categories for 2014 total emissions have
decreased more than 62 percent compared to the 2005 baseline emissions.
In addition, Montana has adopted permitting requirements for major
stationary sources or major modifications located in the nonattainment
areas including Libby, Montana. They are located in the Administrative
Rules of Montana (ARM) 17.8.901 through 17.8.906. These rules require
all new sources or modifications to use the lowest achievable emission
rate (LAER). Sources must obtain emission reduction offsets in tons per
year (tpy) which provide a positive net air quality benefit in the
nonattainment area using a one to one offset and must be from the same
source or another emissions source within the same nonattainment area.
There must be demonstrated improvement to the PM2.5
nonattainment with permanent, quantifiable, and federally enforceable
reductions. A reduction of actual emissions, not potential emissions,
must occur before a new source can be permitted to operate.
In addition, Montana has a federally enforceable permitting program
for minor sources in ARM, Title 17 Chapter 8, Subpart 7 that addresses
PM2.5 emissions. These rules require sources that emit 25
tpy or more of PM2.5 to ensure the nonattainment area is not
negatively affected. Beginning in May 2019, Montana began requiring
registration of all sized asphalt plants, concrete plants, mineral
crushers, and
[[Page 74585]]
mineral screens. The registration program establishes conservative
operational restrictions on these portable sources to prevent
degradation of the air quality in nonattainment areas and elsewhere.
Not only has air quality in the Libby Area benefited from the local
district and State rules discussed previously, but the Area has also
benefitted from emission reductions from federal measures including
federal tailpipe standards and the Federal Motor Vehicle Control
Program. Federal tailpipe standards were designed to reduce vehicle
emissions, including PM2.5. The previous control plan did
not take credit for the PM2.5 reductions resulting from
lower federal vehicle emissions standards and vehicle fleet turnover in
the nonattainment area. The federal tailpipe standards and vehicle
turnover will continue to reduce future impacts and meet the
requirements of the 1990 CAA Amendments. The Federal Motor Vehicle
Control Program controls tailpipe emissions and evaporative emission
standards for new vehicles. Tailpipe impacts were less than one percent
of the Libby Area during the 2005 baseline year.\29\ The
PM2.5 impact reductions are supported by lower fleet vehicle
fleet emissions as fleet turnover continues.
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\29\ See Table 2.3 in the Libby Area SIP submission. Available
in the docket for this proposed rulemaking.
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Based upon the previously listed actions by Montana in the
submitted maintenance plan, EPA finds that the improvement in air
quality in the Libby Area is the result of permanent and enforceable
emissions reductions from a combination of EPA-approved local and State
control measures and federal control measures. As such, we believe the
criterion for redesignation set forth in CAA section 107(d)(3)(E)(iii)
is satisfied.
C. Does the Area have a fully approved maintenance plan pursuant to
section 175A of the CAA?
For redesignating a nonattainment area to attainment, the CAA
requires EPA to determine that the area has a fully approved
maintenance plan pursuant to section 175A of the CAA (CAA section
107(d)(3)(E)(iv)). In conjunction with its request to redesignate the
Libby Area to attainment for the 1997 annual PM2.5 NAAQS,
Montana submitted a SIP revision to provide for the maintenance of the
1997 annual PM2.5 NAAQS for at least 10 years after the
effective date of redesignation to attainment. EPA believes that this
maintenance plan meets the requirements for approval under section 175A
of the CAA for the reasons discussed in this section.
Section 175A of the CAA sets forth the elements of a maintenance
plan for areas seeking redesignation from nonattainment to attainment.
Under section 175A, the plan must demonstrate continued attainment of
the applicable NAAQS for at least 10 years after the Administrator
approves a redesignation to attainment. Because the 1997 primary annual
PM2.5 NAAQS will be revoked for the Libby Area if it is
redesignated to attainment, Montana is not required to submit a second
10-year maintenance plan for the 1997 primary annual PM2.5
NAAQS. See 81 FR 58010, 58144. To address the possibility of future
NAAQS violations, the maintenance plan must contain such contingency
measures, as EPA deems necessary, to assure prompt correction of any
future 1997 annual PM2.5 NAAQS violations. The Calcagni
Memorandum provides further guidance on the content of a maintenance
plan, explaining that a maintenance plan should address five
requirements: the attainment emissions inventory; maintenance
demonstration; monitoring; verification of continued attainment; and a
contingency plan. As is discussed here, EPA finds that Montana's
maintenance plan includes all the necessary components and is thus
proposing to approve it as a revision to the Montana SIP.
1. Attainment Emissions Inventory
As discussed previously, EPA is proposing to determine that the
Libby Area is attaining the 1997 annual PM2.5 NAAQS based on
a monitoring data for the time period from 2014-2021. Montana selected
2014 as the attainment emission inventory year. The attainment
inventory identifies the level of emissions in the Area that is
sufficient to attain the 1997 annual PM2.5 NAAQS. Montana
began development of the attainment inventory by first generating a
baseline emissions inventory for the Libby Area. Montana selected 2005
as the base year for developing a comprehensive emissions inventory for
direct PM2.5 and the PM2.5 precursors
SO2, NOX, VOCs, and ammonia. See 76 FR 14584
(March 17, 2011). The Wegman Memorandum states that an attainment
inventory should represent emissions during the same 5-year period
associated with the air quality data used to determine that the area
meets the applicability requirements of the LMP option. The Libby LMP,
provided in Montana's June 24, 2020 SIP submission, includes an
emission inventory from 2014, representative of the 2014-2021 time
period which served as the 5-year period relied upon in limited
maintenance plans as meeting the air quality data requirements of the
Wegman Memorandum.\30\
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\30\ The emissions inventory included in the Libby Area SIP
submission is the 2014 NEI. The NEI is a composite of data from many
different sources, with PM data coming primarily from EPA models as
well as from state, tribal, and local air quality management
agencies. Different data sources use different data collection
methods, and many of the emissions data are based on estimates
rather than actual measurements. EPA considers the 2014 NEI
representative of the period from 2014-2021 because Montana provided
comparable vehicle miles traveled (VMT) data in their submission.
See Libby Area SIP submission, Appendix A, Montana Department of
Transportation Future VMT Projections, p. A-1 in docket for this
proposed rulemaking.
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2. Maintenance Demonstration
Montana's SIP submission for the Libby Area employs the CDV method
laid out in the 2001 Wegman Memorandum to demonstrate that the Area is
eligible for an LMP. As noted previously, the CDV calculation from the
Wegman Memorandum represents the highest design value an area could
have before it would violate the NAAQS given a 1 in 10 probability--
that is, if the area's current ADV (based on the most recent five years
of data) is less than the CDV, there is a less than 1 in 10
probabilities that the area will violate in the future. The State's
submission calculates the ADV as 10.9 [micro]g/m\3\ and calculates the
site-specific CDV as 14.1 [micro]g/m\3\ using the Libby Area monitor
data from 2014-2018. Therefore, the State's submission showed the Libby
ADV is less than the CDV, but because of the time that has elapsed
since the State's submission, EPA has also analyzed more recent data
that are available in AQS and have been certified by the MDEQ.
To calculate the ADV we averaged the most recent five design values
for the PM2.5 annual standard. Since each design value is
calculated by averaging three years of valid annual means, the average
of the last five design values includes data from the most recent 7-
year period (2014-2021). Table 3 presents the most recent annual
PM2.5 NAAQS design values for 2017-2021 and presents the
resulting ADV of 13.2 [micro]g/m\3\.
To calculate the CDV we use the most recent five years of design
values and their variability with the equation presented in the Wegman
Memorandum (Table 3). The resulting site-specific CDV is calculated to
be 14.6 [micro]g/m\3\ (Table 5). Therefore, the ADV (13.2 [micro]g/
m\3\) falls below the site-specific CDV of
[[Page 74586]]
14.6 [micro]g/m\3\ and thus meets the first criterion for LMP
eligibility.\31\
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\31\ See Libby PM2.5 CDV Calculations in docket for
this proposed rulemaking.
Table 3--Annual PM2.5 NAAQS Design Values ([micro]g/m\3\) \32\
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Average of most recent
2017 Design value (2015- 2018 Design value (2016- 2019 Design value (2017- 2020 Design value (2018- 2021 Design value 3-year design values
2017) * 2018) * 2019) * 2020) * (2019-2021) * (ADV)
--------------------------------------------------------------------------------------------------------------------------------------------------------
13.0 12.9 13.4 13.3 13.3 13.2
--------------------------------------------------------------------------------------------------------------------------------------------------------
Table 4--Eligibility Calculation Equations
------------------------------------------------------------------------
------------------------------------------------------------------------
Critical Design Value.................. CDV = NAAQS/(1 + (tc x CV))
Coefficient of Variation............... CV = [sigma]/ADV
Projected DV due to Motor Vehicle Projected DV = ADV + (VMTpi x
Growth over 10 years. DVmv)]
------------------------------------------------------------------------
ADV = Average of 3-year design values.
DV = Design value.
DVmv = motor vehicle design value based on on-road mobile portion of the
attainment year inventory.
NAAQS = Applicable standard (15 [mu]g/m\3\).
[sigma] = standard deviation of design values.
tc = Critical t-value (based on the one-tail student's t-distribution,
at a significance level of 0.10).
VMTpi = Projected percent increase in vehicle miles traveled (VMT) over
the next 10 years.
Table 5--Calculation of the CDV Using 2017-2021 Design Values
------------------------------------------------------------------------
------------------------------------------------------------------------
NAAQS.................................. 15.0 [mu]g/m\3\
Tc..................................... 1.533
ADV (2017-2021)........................ 13.2 [mu]g/m\3\
[Sigma]................................ 0.2168 [mu]g/m\3\
CV..................................... 0.0164
CDV = [NAAQS/(1 + tc x CV)]............ 14.6 [mu]g/m\3\
------------------------------------------------------------------------
In addition to having an ADV that is at or below the site-specific
CDV, the 2001 Wegman Memorandum also provides a methodology for
calculating a margin of safety factor based on expected growth in
mobile source emissions. The memo lays out in Attachment B a motor
vehicle regional emissions analysis test, which is designed to account
for an area's expected change in vehicle miles traveled, to determine
whether increased emissions from on-road mobile sources could, in the
next 10 years, increase concentrations in the area and threaten the
assumption of maintenance that underlies LMP policy. In its June 24,
2020 SIP submission, Montana employed the motor vehicle regional
emissions analysis test outlined in Attachment B of the Wegman
Memorandum to demonstrate that the Libby Area's expected growth in
mobile source emissions would not threaten maintenance of the NAAQS.
Using data from 2014-2018 the State calculated that due to growth in
mobile source emissions the ADV may increase from 10.9 [micro]g/m\3\ to
11.1 [micro]g/m\3\ in the next 10 years, but that 11.1 [micro]g/m\3\ is
still below the margin of safety as defined by the site-specific CDV
(14.1 [micro]g/m\3\). EPA has also examined more recent data to confirm
that even with updated information, the test continues to show that
anticipated growth in mobile source emissions should not interfere with
the Libby Area's maintenance of the 1997 annual PM2.5 NAAQS.
Using design values from 2017-2021, we calculated that due to expected
growth in mobile source emissions, the ADV may increase from 13.2
[micro]g/m\3\ to 13.5 [micro]g/m\3\ in the next 10 years, but that 13.5
[micro]g/m\3\ is still below the margin of safety as defined by the
site-specific CDV (14.6 [micro]g/m\3\). For the calculations used to
determine how the Libby Area passed the motor vehicle regional analysis
test, see Table 6.\33\
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\32\ In Table 3, (years)* is referring to what data was included
in the calculation for each 3-year design value.
\33\ See Memo to File, Libby MT Motor Vehicle Regional Emission
Analysis in docket for this proposed rulemaking.
Table 6--Motor Vehicle Regional Emissions Analysis Test Calculations
------------------------------------------------------------------------
------------------------------------------------------------------------
ADV (2017-2021)........................ 13.2 [micro]g/m\3\
VMTpi.................................. 11.56%
DVmv................................... 2.5 [micro]g/m\3\
Calculated [ADV + (VMTpi x DVmv)]...... 13.5 [micro]g/m\3\
------------------------------------------------------------------------
The 2001 Wegman Memorandum also indicates that once a state has an
approved LMP, the state will be expected to determine, on an annual
basis, that the LMP criteria are still being met. If the state
determines that the LMP criteria are not being met, it should take
action to reduce PM2.5 concentrations enough to requalify
for the LMP. One possible approach a state could take is to implement
contingency measures. For a description of contingency provisions
included in the Libby LMP, see section 3.6 of Montana's June 24, 2020
SIP submission.
Although the State flagged some PM2.5 values as
potentially affected by exceptional events, such as wildfire
[[Page 74587]]
smoke, this action utilizes all quality-assured monitoring data from
Libby. A 2019 memo from Richard Wayland and Anna Wood regarding
additional methods, determinations, and analyses to modify air quality
data beyond exceptional events,\34\ indicates that monitoring data
could qualify for exclusion for use in calculating air quality design
values in support of a NAAQS LMP submission and any subsequent yearly
design value calculations for areas with approved LMPs. The memorandum
states that such data exclusion requests will be treated in a manner
analogous to the treatment of exceedance data under the Exceptional
Events Rule (EER). Since the Libby Area qualifies for the LMP option
without the removal of any demonstrated values, the flagged data have
no regulatory significance and therefore the demonstrated values are
included in the calculations and remain in AQS. Additional information
on the EER can be found in 40 CFR 50.14 and 40 CFR 51.930.
---------------------------------------------------------------------------
\34\ See the memorandum from Richard Wayland, Director of Air
Quality Assessment Division and Anna Marie Wood, Director of Air
Quality Policy Division, dated April 4, 2019, entitled, ``Additional
Methods, Determinations, and Analyses to Modify Air Quality Data
Beyond Exceptional Events.''
---------------------------------------------------------------------------
Pursuant to the Wegman Memorandum, the State's approved maintenance
plan should include an emissions inventory (attainment inventory) which
can be used to demonstrate attainment of the NAAQS. The inventory
should represent emissions during the same 5-year period associated
with air quality data used to determine whether the area meets the
applicability requirements of the LMP option. The state should review
its inventory every three years to ensure emissions growth is
incorporated in the attainment inventory, if necessary. In this
instance, Montana completed an attainment year inventory for 2014 for
the Libby Area. EPA has reviewed the 2014 emissions inventories and
determined that they are appropriate for this plan.
3. Monitoring Network
The PM2.5 monitoring network for the Libby Area has been
developed and maintained in accordance with federal siting and design
criteria in 40 CFR part 58, appendices D and E and in consultation with
EPA Region 8. In section 3.5 of the Libby LMP, located within Montana's
June 24, 2020 SIP submission, Montana states that it will continue to
operate its monitoring network to meet EPA requirements at 40 CFR part
58 and identify any issues or adjustments via the annual Ambient Air
Monitoring Network Plan or formal communication. EPA approved Montana's
2021 monitoring plan on November 16, 2021.\35\
---------------------------------------------------------------------------
\35\ See MT AMNP Approval Letter 2021 in docket for the proposed
rulemaking.
---------------------------------------------------------------------------
4. Verification of Continued Attainment
Montana, through MDEQ, has the legal authority to enforce and
implement the requirements of the Libby LMP. This includes the
authority to adopt, implement, and enforce any subsequent emissions
control contingency measures determined to be necessary to correct
future PM2.5 attainment problems.
In demonstrating maintenance, continued attainment of the NAAQS can
be verified through operation of an appropriate air quality monitoring
network. The Calcagni Memorandum (p.11) states that the maintenance
plan should contain provisions for continued operation of air quality
monitors that will provide such verification. As discussed in section V
of this document, PM2.5 is currently monitored by MDEQ
within the Libby Area. In section 3.5 of Montana's submitted
maintenance plan, MDEQ intends to maintain an appropriate
PM2.5 monitoring network and review monitoring and emissions
data through the maintenance period.
MDEQ will track the progress of the maintenance plan by performing
future reviews of triennial emission inventories for the Libby Area as
required in the Air Emissions Reporting Rule (AERR). Emissions
information will be compared to the attainment year to assure continued
compliance with the annual PM2.5 standard.
5. Contingency Provisions
Section 175A(d) of the CAA requires that the maintenance plan
contains contingency provisions to assure that the state will promptly
correct any violation of the relevant PM2.5 NAAQS that may
occur after the redesignation of the area to attainment. Such
provisions must include a requirement that the state will implement all
measures with respect to the control of the air pollutant concerned
that were contained in the SIP for the area before redesignation of the
area as an attainment area. EPA's redesignation guidance notes that the
state is not required to have fully adopted contingency measures that
will take effect without further action by the state. As such, the
contingency plan should ensure that the state has the capacity to adopt
the contingency measures expediently if the need were triggered.
Therefore, the primary elements of this contingency plan involve the
tracking and triggering mechanisms to determine when contingency
measures would be necessary and a process for implementing appropriate
control measures.
Montana will continue to monitor and analyze PM2.5
concentrations to determine continued maintenance of the relevant
PM2.5 NAAQS. In accordance with 40 CFR part 58, MDEQ will
continue to operate the Libby monitor (Site ID 30-053-0018).
If the State determines the Libby Area has exceeded the 1997 annual
PM2.5 NAAQS, the triggering of the contingency plan does not
automatically require a revision of the SIP, nor is the Area
necessarily redesignated once again to nonattainment. Instead, MDEQ
will have an appropriate timeframe to correct the violation with
implementation of one or more adopted contingency measures. If
violations continue to occur, additional contingency measures may need
to be adopted until the violations are corrected.
Montana has adopted a contingency provision to address future
PM2.5 air quality problems. The contingency provisions in
the Libby PM2.5 LMP are contained in section 3.6. of
Montana's June 24, 2020, SIP submission. MDEQ identifies the following
steps if a violation occurs, and the State triggers the contingency
plan:
1. Within 12 months of an exceedance notification, MDEQ and the
local government in the Libby Area will commence an analysis to review
information about historical exceedances of the standard, the
meteorological conditions related to recent exceedance(s), most recent
growth, and emissions, and if the possibility of an exceptional event
occurred. MDEQ will develop appropriate contingency measure(s) to
correct the violation of the PM2.5 standard.
2. Under the 2016 revisions to the Treatment of Data Influenced by
Exceptional Events Rule (81 FR 68216), MDEQ will confer with EPA Region
8 regarding whether any flagged exceptional events would meet the
criteria of a regulatory decision, and if so, a determination would be
made on whether to move forward with producing a demonstration and if
that would trigger contingency measures.
3. If MDEQ and the local government in the Libby Area finds locally
adopted control measures to be inadequate, MDEQ and the local
government will adopt state-enforceable measures as deemed necessary by
MDEQ to prevent additional exceedances or violations.
[[Page 74588]]
Measures to be considered include implementation of Libby's Contingency
Rules 75.1.208 and 75.1.307, as spelled out in Montana's Libby
PM2.5 attainment plan, the use of deciphers, additional
street cleaning, etc.
Upon our review, we find that the contingency provisions of the
Libby PM2.5 LMP satisfy the pertinent requirements of
section 175A of the CAA.
D. Transportation and General Conformity
The requirements for transportation and general conformity are
found in CAA section 176(c). Conformity to the SIP means that
transportation-related actions (transportation conformity) and other
federal actions (general conformity) will not cause or contribute to
any new violation of any standard in any area, increase the frequency
or severity of any existing violation of any standard in any area or
delay timely attainment of any standard or any required interim
emission reductions or other milestones in any area (CAA section
176(c)(1)(B)).
As discussed in section II.B, if the proposal is finalized, the
1997 primary annual PM2.5 NAAQS will be revoked in the Libby
Area on the effective date of the redesignation. Beginning on that
date, the Area will no longer be subject to transportation conformity
or general conformity requirements for the 1997 annual PM2.5
NAAQS due to the revocation of the 1997 primary annual PM2.5
NAAQS. See 81 FR 58125-6.
V. What are the effects of EPA's proposed actions?
EPA's proposed actions establish the basis upon which EPA may take
final action on the issues being proposed for approval. Approval of
Montana's redesignation request would change the legal designation of
Lincoln County for the 1997 annual PM2.5 NAAQS, found at 40
CFR part 81, from nonattainment to attainment. The limited maintenance
plan includes contingency measures to remedy any future violations of
the 1997 annual PM2.5 NAAQS and procedures for evaluation of
potential violations.
VI. Proposed Actions
EPA is proposing to: (1) determine that the Libby Area is attaining
the 1997 annual PM2.5 NAAQS based on 2014-2021 data; (2)
approve Montana's plan for maintaining the 1997 annual PM2.5
NAAQS (limited maintenance plan); and (3) redesignate the Libby Area to
attainment for the 1997 annual PM2.5 NAAQS. If finalized,
approval of the redesignation request would change the official
designation of Lincoln County for the 1997 annual PM2.5
NAAQS, found at 40 CFR part 81 from nonattainment to attainment, as
found at 40 CFR part 81.
VII. Statutory and Executive Order Reviews
Under the CAA, redesignation of an area to attainment and the
accompanying approval of a maintenance plan are actions that affect the
status of a geographical area and do not impose any additional
regulatory requirements on sources beyond those imposed by state law. A
redesignation to attainment does not in and of itself create any new
requirements, but rather results in the applicability of requirements
contained in the CAA for areas that have been redesignated to
attainment. Moreover, the Administrator is required to approve a SIP
submission that complies with the provisions of the Act and applicable
federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in
reviewing SIP submissions, EPA's role is to approve state choices,
provided that they meet the criteria of the CAA. Accordingly, this
action merely proposes to approve state law as meeting federal
requirements and does not impose additional requirements beyond those
imposed by state law. For these reasons, this proposed action:
Is not a ``significant regulatory action'' subject to
review by the Office of Management and Budget under Executive Orders
12866 (58 FR 51735, October 4, 1993) and 13563 (76 FR 3821, January 21,
2011);
Does not impose an information collection burden under the
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
Is certified as not having a significant economic impact
on a substantial number of small entities under the Regulatory
Flexibility Act (5 U.S.C. 601 et seq.);
Does not contain any unfunded mandate or significantly or
uniquely affect small governments, as described in the Unfunded
Mandates Reform Act of 1995 (Public Law 104-4);
Does not have Federalism implications as specified in
Executive Order 13132 (64 FR 43255, August 10, 1999);
Is not an economically significant regulatory action based
on health or safety risks subject to Executive Order 13045 (62 FR
19885, April 23, 1997);
Is not a significant regulatory action subject to
Executive Order 13211 (66 FR 28355, May 22, 2001);
Is not subject to requirements of section 12(d) of the
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272
note) because application of those requirements would be inconsistent
with the CAA; and
Executive Order 12898 (59 FR 7629, February 16, 1994,
directs federal agencies, to the greatest extent practicable and
permitted by law, to make environmental justice part of their mission
by identifying and addressing, as appropriate disproportionately high
and adverse human health or environmental effects of their program,
policies, and activities on minority populations (people of color/
Indigenous people) and low-income populations.
In addition, the SIP is not approved to apply on any Indian
reservation land or in any other area where EPA or an Indian tribe has
demonstrated that a tribe has jurisdiction. In those areas of Indian
country, the proposed rule does not have tribal implications and will
not impose substantial direct costs on tribal governments or preempt
tribal law as specified by Executive Order 13175 (65 FR 67249, November
9, 2000).
List of Subjects
40 CFR Part 52
Environmental protection, Air pollution control, Carbon monoxide,
Greenhouse gases, Incorporation by reference, Intergovernmental
relations, Lead, Nitrogen dioxide, Ozone, Particulate matter, Reporting
and recordkeeping requirements, Sulfur oxides, Volatile organic
compounds.
40 CFR Part 81
Environmental protection, Air pollution control, National parks,
and Wilderness areas.
Authority: 42 U.S.C. 7401 et seq.
Dated: December 1, 2022.
KC Becker,
Regional Administrator, Region 8.
[FR Doc. 2022-26504 Filed 12-5-22; 8:45 am]
BILLING CODE 6560-50-P