[Federal Register Volume 87, Number 11 (Tuesday, January 18, 2022)]
[Proposed Rules]
[Pages 2571-2587]
[FR Doc No: 2022-00777]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R08-OAR-2020-0441; FRL-9443-01-R8]

Disapproval of Air Quality Implementation Plans; Wyoming;
Proposed Revisions to Regional Haze State Implementation Plan

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to
disapprove a State Implementation Plan (SIP) revision submitted by the
State of Wyoming on May 14, 2020, and supplemented in September and
October 2020, addressing regional haze (``Wyoming's 2020 SIP
revision''). Wyoming's 2020 SIP revision reverses the State's 2011
decision that emission limits consistent with the installation of
selective catalytic reduction (SCR) for the Jim Bridger power plant,
Units 1 and 2, are necessary to make reasonable progress under the
State's long-term strategy for the first regional haze planning period.
The SIP revision contains a source-specific nitrogen oxide
(NOX) reasonable progress analysis and determination that
currently installed controls (low-NOX burners with separated
overfire air (LNB/SOFA)) are sufficient for reasonable progress during
the first planning period for Jim Bridger Units 1 and 2, and that the
emission limits associated with the installation of SCR are no longer
necessary. The SIP revision also contains plant-wide monthly and annual
NOX and sulfur dioxide (SO2) emission limits for
the Jim Bridger power plant, Units 1-4. EPA is proposing to disapprove
this SIP revision in full. The agency is proposing this action pursuant
to sections 110 and 169A of the Clean Air Act (CAA).

DATES: Comments: Written comments must be received on or before
February 17, 2022.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R08-
OAR-2020-0441, to the Federal Rulemaking Portal: 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://www.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: Jaslyn Dobrahner, Air and Radiation
Division, EPA, Region 8, Mailcode 8P-ARD, 1595 Wynkoop Street, Denver,
Colorado, 80202-1129, telephone number:<PHONE_NUMBER>, email address:
[email protected].

SUPPLEMENTARY INFORMATION: Throughout this document wherever ``we,''
``us,'' or ``our'' is used, we mean EPA.

I. What Action is EPA Proposing?
II. Background
    A. Requirements of the Clean Air Act and EPA's Regional Haze
Rule
    B. Best Available Retrofit Technology
    C. Long-Term Strategy and Reasonable Progress Requirements
    D. Consultation with Federal Land Managers
III. Wyoming's Regional Haze SIP Revisions
    A. Background
    B. May 14, 2020 Submittal
    C. Summary of Wyoming's Reasonable Progress Reassessment
     1. Costs of Compliance
     2. Time Necessary for Compliance
     3. Energy and Non-Air Quality Environmental Impacts of
Compliance
     4. Remaining Useful Life
     5. Visibility Improvement
     6. Reasonable Progress Demonstration
    D. Summary of Wyoming's Plant-Wide Monthly and Annual
NOX and SO2 Emission Limits for Jim Bridger
IV. EPA's Evaluation and Proposed Disapproval of Wyoming's Regional
Haze SIP Revisions
    A. Basis for Proposed Disapproval
    B. EPA's Proposed Disapproval of Wyoming's Reasonable Progress
Determination for Jim Bridger Units 1 and 2
    1. Basis of Our Proposed Disapproval
    a. Costs of Compliance
    b. Visibility Improvement
    c. Other Factors
    d. Summary of EPA's Evaluation of Wyoming's Reasonable Progress
Demonstration
    C. Plant-Wide Monthly and Annual NOX and
SO2 Emission Limits for Jim Bridger Units 1-4
    D. Clean Air Act Section 110(l)
    E. Consultation With Federal Land Managers
V. Summary of EPA's Proposed Action
VI. Statutory and Executive Order Reviews

I. What action is EPA proposing?

    On January 30, 2014, EPA promulgated a final rule titled,
``Approval, Disapproval and Promulgation of Implementation Plans; State
of Wyoming; Regional Haze State Implementation Plan; Federal
Implementation Plan for Regional Haze,'' approving in part a regional
haze SIP revision submitted by the State of Wyoming on January 12, 2011
(2014 final rule).\1\ In the 2014 final rule, EPA approved Wyoming's
NOX best available retrofit technology (BART) emission
limits of 0.26 lb/MMBtu (30-day rolling average) for Jim Bridger Units
1-4, as well as the State's decision to include in its long-term
strategy NOX reasonable progress emission limits of 0.07 lb/
MMBtu (30-day rolling average) for the same units, among other
actions.\2\
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    \1\ 79 FR 5032 (January 30, 2014).
    \2\ The BART determination compliance date for all units was
March 4, 2019. Reasonable progress determination compliance dates
for each include: Unit 1 = December 31, 2022; Unit 2 = December 31,
2021; Unit 3 = December 31, 2015; and Unit 4 = December 31, 2016.
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    Wyoming submitted its 2020 SIP revision on May 14, 2020.\3\ The SIP
revision contains amendments to Chapters 7 and 8 of Wyoming's regional
haze SIP narrative and would incorporate certain conditions of Wyoming
air quality permit #P0025809 into the SIP.\4\ Together, the amendments
provide a source-specific NOX reasonable progress analysis
and determination for Jim Bridger Units 1 and 2, remove the
NOX reasonable progress emission limits currently required
for Jim Bridger Units 1 and 2, and add plant-wide monthly and annual
NOX and SO2 emission limits for Jim Bridger Units
1-4.\5\
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    \3\ At the request of EPA, Wyoming supplemented the original SIP
submittal with additional documentation on September 8, 2020, and
October 6, 2020.
    \4\ State of Wyoming, ``Addressing Regional Haze Visibility
Protection For The Mandatory Federal Class I Areas Required Under 40
CFR 51.309,'' Revised May 14, 2020 (``Wyoming 2020 SIP Revision'').
    \5\ Wyoming's SIP revision refers to these limits as ``voluntary
visibility enhancing emission limits.'' They represent a separate
SIP component from Wyoming's source-specific reasonable progress
analysis and determination. The limits were voluntarily proposed by
PacifiCorp to reduce regional haze causing pollutants. Wyoming 2020
SIP Revision at 8-9.
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    EPA is proposing to disapprove this SIP revision in full. Our
proposed disapproval is based on the following: (1) The reasonable
cost-effectiveness of the existing reasonable progress control
requirements for Jim Bridger Units 1 and 2 (emission limits consistent
with the installation of SCR); (2) the appreciable visibility
improvement estimated to result from compliance with the existing
control requirements; and (3) the fact that the State previously
determined that the costs of those control requirements were reasonable
and that they are necessary to satisfy the statutory requirements, and
has not provided any new information that would support a revised
determination that the requirements are now unreasonable. In fact, the
updated cost information provided by Wyoming indicates that SCR for
these units is even more cost-effective than the State estimated in
2011 and EPA estimated in its 2014 final rule, while the estimated
visibility benefits remain the same as estimated in the 2014 final
rule.
    Based on our proposed conclusions in section IV.B in this document,
we propose to find that removing the SCR requirement would interfere
with the regional haze requirements of the CAA, specifically, with the
requirement that SIPs contain the emission limits, schedules of
compliance, and other measures that are necessary to make reasonable
progress toward the national visibility goal. That is, approving
Wyoming's removal of the SCR requirement would be inconsistent with the
statutory requirement that Wyoming's SIP contain the measures necessary
to make reasonable progress toward the national visibility goal.
Furthermore, EPA cannot propose to approve Wyoming's plant-wide
NOX and SO2 emission limits while proposing to
disapprove the elimination of the SCR requirements for Units 1 and 2,
because such a partial approval would render the SIP more stringent
than the State intended. Regardless, as discussed in section IV.C, the
installation of SCR on Units 1 and 2 is estimated to reduce
NOX by at least 3,000 tons per year (tpy) based on current
utilization. EPA believes it is reasonable to conclude that the plant-
wide NOX and SO2 emission limits that Wyoming has
required in lieu of the existing control requirements would not provide
similar or greater emissions reductions or visibility improvement
compared to two additional SCRs, as claimed by the State.

II. Background

A. Requirements of the Clean Air Act and EPA's Regional Haze Rule

    In section 169A of the CAA, Congress created a program for
protecting visibility in national parks and wilderness areas. This
section of the

CAA establishes ``as a national goal the prevention of any future, and
the remedying of any existing, impairment of visibility in mandatory
Class I Federal areas which impairment results from manmade air
pollution.'' \6\
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    \6\ 42 U.S.C. 7491(a). Areas designated as mandatory Class I
Federal areas consist of national parks exceeding 6,000 acres,
wilderness areas and national memorial parks exceeding 5,000 acres,
and all international parks that were in existence on August 7,
1977. 42 U.S.C. 7472(a). In accordance with section 169A of the CAA,
EPA, in consultation with the Department of Interior, promulgated a
list of 156 areas where visibility is identified as an important
value. 44 FR 69122 (November 30, 1979). The extent of a mandatory
Class I area includes subsequent changes in boundaries, such as park
expansions. 42 U.S.C. 7472(a). Although states and tribes may
designate as Class I additional areas whose visibility they consider
to be an important value, the requirements of the visibility program
set forth in section 169A of the CAA apply only to ``mandatory Class
I Federal areas.'' Each mandatory Class I Federal area is the
responsibility of a ``Federal Land Manager.'' 42 U.S.C. 7602(i).
When we use the term ``Class I area'' in this action, we mean a
``mandatory Class I Federal area.''
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    EPA promulgated a rule to address regional haze on July 1, 1999.\7\
The Regional Haze Rule revised the existing visibility regulations \8\
to integrate provisions addressing regional haze and established a
comprehensive visibility protection program for Class I areas. The
requirements for regional haze, found at 40 CFR 51.308 and 40 CFR
51.309, are included in EPA's visibility protection regulations at 40
CFR 51.300 through 40 CFR 51.309.\9\
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    \7\ 64 FR 35714, 35714 (July 1, 1999) (codified at 40 CFR part
51, subpart P).
    \8\ EPA had previously promulgated regulations to address
visibility impairment in Class I areas that is ``reasonably
attributable'' to a single source or small group of sources, i.e.,
reasonably attributable visibility impairment (RAVI). 45 FR 80084,
80084 (December 2, 1980).
    \9\ EPA revised the Regional Haze Rule on January 10, 2017. 82
FR 3078 (January 10, 2017). Under the revised Regional Haze Rule,
the requirements in 40 CFR 51.308(d) and (e) apply to first
implementation period SIP submissions and 40 CFR 51.308(f) applies
to submissions for the second and subsequent implementation periods.
82 FR 3087; see also 81 FR 26942, 26952 (May 4, 2016).
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    The CAA requires each state to develop a SIP to meet various air
quality requirements, including protection of visibility.\10\ Regional
haze SIPs must assure reasonable progress toward the national goal of
preventing future and remedying existing manmade visibility impairment
in Class I areas. A state must submit its SIP and SIP revisions to EPA
for approval.\11\ Once approved, a SIP is enforceable by EPA and
citizens under the CAA; that is, the SIP is federally enforceable.
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    \10\ See 42 U.S.C. 7410(a), 7491, and 7492; CAA sections 110(a),
169A, and 169B.
    \11\ 42 U.S.C. 7491(b)(2); 7410.
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B. Best Available Retrofit Technology

    Section 169A(b)(2) of the CAA requires SIPs to contain such
measures as may be necessary to make reasonable progress toward meeting
the national visibility goal. Section 169(b)(2)(A) specifies that one
such requirement is for certain categories of existing major stationary
sources built between 1962 and 1977 to procure, install, and operate
BART as determined by the states through their SIPs. Under the Regional
Haze Rule, states (or EPA, in the case of a Federal implementation plan
(FIP)) are directed to make BART determinations for such ``BART-
eligible'' sources--typically larger, often uncontrolled, and older
stationary sources--that may reasonably be anticipated to cause or
contribute to any visibility impairment in a Class I area.\12\ Rather
than requiring source-specific BART controls, states also have the
flexibility to adopt an emissions trading program or other alternative
program as long as the alternative will achieve greater reasonable
progress toward natural visibility conditions than BART.\13\
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    \12\ 40 CFR 51.308(e). EPA designed the Guidelines for BART
Determinations Under the Regional Haze Rule (Guidelines) ``to help
States and others (1) identify those sources that must comply with
the BART requirement, and (2) determine the level of control
technology that represents BART for each source.'' 40 CFR part 51,
appendix Y, I.A. Section II of the Guidelines describes the four
steps to identify BART sources, and Section III explains how to
identify BART sources (i.e., sources that are ``subject to BART'').
    \13\ 40 CFR 51.308(e)(2). WildEarth Guardians v. EPA, 770 F.3d
919, 934 (10th Cir. 2014).
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    One such ``BART alternative'' is included in 40 CFR 51.309, and is
an option for nine states termed the ``Transport Region States,'' which
include Arizona, California, Colorado, Idaho, Nevada, New Mexico,
Oregon, Utah, and Wyoming. Transport Region States can adopt regional
haze strategies based on recommendations from the Grand Canyon
Visibility Transport Commission (GCVTC) for protecting visibility in
the 16 Class I areas on the Colorado Plateau.\14\
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    \14\ The Colorado Plateau is a high, semi-arid tableland in
southeast Utah, northern Arizona, northwest New Mexico, and western
Colorado. The 16 mandatory Class I areas are the Grand Canyon
National Park, Mount Baldy Wilderness, Petrified Forest National
Park, Sycamore Canyon Wilderness, Black Canyon of the Gunnison
National Park Wilderness, Flat Tops Wilderness, Maroon Bells
Wilderness, Mesa Verde National Park, Weminuche Wilderness, West Elk
Wilderness, San Pedro Park Wilderness, Arches National Park, Bryce
Canyon National Park, Canyonlands National Park, Capital Reef
National Park, and Zion National Park.
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    As part of its overall plan for making reasonable progress toward
the national visibility goal for those 16 Class I areas, the GCVTC
submitted a program to EPA, known as the Western SO2
Backstop Trading Program, containing annual SO2 emissions
reduction milestones and detailed provisions for a backstop trading
program to be implemented automatically if states' measures fail to
achieve the SO2 milestones. EPA approved the Backstop
Trading Program as a BART alternative for SO2 emissions.\15\
Transport Region States' SIPs must also contain BART requirements for
stationary-source emissions of NOX and particulate
matter.\16\
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    \15\ 64 FR 35714 (July 1, 1999); 68 FR 33764 (June 5, 2003).
    \16\ 40 CFR 51.309(d)(4)(vi).
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C. Long-Term Strategy and Reasonable Progress Requirements

    In addition to the BART requirements, the CAA's visibility
protection provisions also require that states' regional haze SIPs
contain a ``long-term (ten to fifteen years) strategy for making
reasonable progress toward meeting the national goal. . . .'' \17\ The
long-term strategy must address regional haze visibility impairment for
each mandatory Class I area within the state and each mandatory Class I
area located outside the state that may be affected by emissions from
the state. It must include the enforceable emission limitations,
compliance schedules, and other measures necessary to achieve the
reasonable progress goals.\18\ The reasonable progress goals, in turn,
are calculated for each Class I area based on the control measures
states have selected for sources by applying the four statutory
``reasonable progress'' factors, which are ``the costs of compliance,
the time necessary for compliance, the energy and non-air quality
environmental impacts of compliance, and the remaining useful life of
any existing source subject to such requirement.'' \19\ That is, states
consider the four reasonable progress factors, and certain other
factors listed in Sec.  51.308(d)(3) of the Regional Haze Rule, to
determine what controls must be included in the long-term strategy.
Those controls are represented in the long-term strategy, i.e., the
SIP, as emission limits, schedules of compliance, and other measures.
The reasonable progress goals are the predicted visibility outcome of
implementing the long-term strategy in addition to ongoing pollution
control programs stemming from other CAA requirements.
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    \17\ 42 U.S.C. 7491(b)(2)(B).
    \18\ See 42 U.S.C. 7491(b)(2); 40 CFR 51.308(d)(3).
    \19\ 42 U.S.C. 7491(g)(1); 40 CFR 51.308(d)(1)(i)(A).
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    Unlike BART determinations, which are required only for the first
regional haze planning period SIPs,\20\ states are

required to submit updates to their long-term strategies, including new
reasonable progress analyses and reasonable progress goals, in the form
of SIP revisions on July 31, 2021, and at specific intervals
thereafter.\21\ In addition, each state must periodically submit a
report to EPA at five-year intervals beginning five years after the
submission of the initial regional haze SIP, evaluating the state's
progress toward meeting the reasonable progress goals for each Class I
area within the state.\22\
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    \20\ Under the Regional Haze Rule, SIPs are due for each
regional haze planning period, or implementation period. The terms
``planning period'' and ``implementation period'' are used
interchangeably in this document.
    \21\ 40 CFR 51.308(f). The 2021 deadline was originally in 2018;
EPA revised this deadline in 2017. 82 FR 3078 (January 10, 2017);
see also 40 CFR 51.308(f). Following the 2021 SIP revision deadline,
the next SIP revision is due in 2028. 40 CFR 51.308(f).
    \22\ 40 CFR 51.308(g); 51.309(d)(10).
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    By meeting all the requirements of 40 CFR 51.309, including but not
limited to the section 309-specific BART requirements, a Transport
Region State can be deemed to be making reasonable progress toward the
national goal for the first implementation period for the 16 Class I
areas on the Colorado Plateau.\23\ For stationary sources, the section
309 requirements include any necessary long-term strategies for
reasonable progress for particulate matter (PM) and NOX
emissions.\24\ Additionally, the State of Wyoming includes several non-
Colorado Plateau Class I areas, and thus was also required to submit a
long-term strategy for those Class I areas.\25\
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    \23\ 40 CFR 51.309(a).
    \24\ 40 CFR 51.309(d)(4)(vii).
    \25\ 79 FR 5199.
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D. Consultation With Federal Land Managers

    The Regional Haze Rule requires that a state consult with Federal
Land Managers (FLMs) before adopting and submitting a required SIP
submittal or revision. Further, a state must include a summary of the
FLMs' conclusions and recommendations in its notice to the public,\26\
as well as include in its submission to EPA a description of how it
addressed any comments provided by the FLMs.\27\
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    \26\ 42 U.S.C. 7491(d).
    \27\ 40 CFR 51.308(i).
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III. Wyoming's Regional Haze SIP Revisions

A. Background

    The Jim Bridger power plant is in Sweetwater County, Wyoming, and
is owned in part and operated by PacifiCorp. The power plant is
composed of four 530 megawatt (MW) tangentially fired boilers burning
pulverized coal for a total net generating capacity of 2,120 MW.
Wyoming determined that all four units are subject to BART.\28\
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    \28\ 77 FR 33022, 33030, 33035 (June 4, 2012).
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    Wyoming submitted a SIP on January 12, 2011, that addressed
regional haze requirements under 40 CFR 51.309 for the first regional
haze planning period. The State's regional haze SIP determined that
NOX BART for Jim Bridger Units 1-4 was new LNB/SOFA.
Compliance with the BART emission limits was required by March 4, 2019,
for all four Jim Bridger units.\29\ The State also determined that
emission limits consistent with the installation of SCR were necessary
to satisfy the reasonable progress (not BART) requirements. Wyoming's
SIP required compliance with these emission limits by December 31,
2022, December 31, 2021, December 31, 2015, and December 31, 2016, for
Units 1-4, respectively.\30\ The State indicated that the delayed
timeline for installing SCR was based on the large number of retrofits
that PacifiCorp was undertaking or helping to finance at power plants
in Wyoming, Utah, Colorado, and Arizona.\31\
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    \29\ 79 FR 5221. Installation of new LNB with SOFA (LNB/SOFA)
corresponds to a NOX emission limit of 0.26 lb/MMBtu (30-
day rolling average).
    \30\ Id. Installation and operation of SCR corresponds to a
NOX emission limit of 0.07 lb/MMBtu (30-day rolling
average).
    \31\ 77 FR 33053; see also State of Wyoming, ``Addressing
Regional Haze Visibility Protection For The Mandatory Federal Class
I Areas Required Under 40 CFR 51.309,'' January 7, 2011, at 102.
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    In June 2012, we proposed to find the State's BART determination
for Jim Bridger Units 1 and 2 unreasonable. We explained that the cost-
effectiveness values for LNB/SOFA + SCR were reasonable and within the
range that Wyoming had determined to be reasonable for other BART
sources. We further explained that the associated visibility
improvement and NOX emissions reductions were significant.
Because the State's compliance date for installing SCR was beyond the
five years allowed by the statute for BART sources, we proposed to
disapprove the State's BART determination and proposed a FIP requiring
a NOX emission limit consistent with the installation of SCR
with a compliance deadline of no later than five years after EPA took
final action.\32\
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    \32\ 77 FR 33053.
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    Alternatively, EPA proposed to conclude that while BART for all
four Jim Bridger units was LNB/SOFA + SCR when the units were
considered individually, i.e., without regard to other units in the
PacifiCorp system, when considering all PacifiCorp's units with their
additional retrofit obligations, BART was LNB/SOFA + SCR on Units 3 and
4 and LNB + OFA on Units 1 and 2. EPA explained that, based on claims
by the State and PacifiCorp, costs, considered broadly across all four
units as well as for units in other states, could be unreasonable for
PacifiCorp to incur within five years of EPA's final action. EPA then
proposed in the alternative to approve Wyoming's BART and reasonable
progress determinations for Units 1 and 2, the latter of which would
require an SCR emission limit by December 31, 2021, for Unit 2, and
December 31, 2022, for Unit 1. EPA noted that the Agency believed it
``may be reasonable and feasible for [SCR] to be completed somewhat
earlier'' but that, given the context, it ``may be appropriate to give
considerable deference to the State's conclusions about what controls
are reasonable and when they should be implemented.'' \33\
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    \33\ 77 FR 33054.
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    In 2013, EPA issued another proposal after the Agency conducted its
own cost analyses and visibility modeling. As in 2012, EPA proposed two
options in the alternative. In proposing to approve the State's BART
and reasonable progress determinations for Jim Bridger Units 1 and 2,
EPA again cited the fact that PacifiCorp may be required to install
several additional retrofits at units in Wyoming and in other states
and proposed to give deference to the State under the
circumstances.\34\
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    \34\ 78 FR 34738, 34755-56 (June 10, 2013). However, of the
twenty retrofit actions referenced in EPA's 2013 proposal,
PacifiCorp has installed only two SCRs in Wyoming and three SCRs and
one SNCR in Colorado to date.
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    In the alternative, EPA again proposed in 2013 to determine that
BART for Jim Bridger Units 1 and 2 is LNB/SOFA + SCR and is required
within five years of EPA's final action. EPA explained that the cost-
effectiveness values for installing SCR were reasonable and the
visibility improvement at the most impacted Class I area was
significant. EPA further explained that the cost estimates were within
the range that Wyoming in its SIP and EPA in other SIP and FIP actions
have considered reasonable in the BART context.\35\
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    \35\ 78 FR 34780.
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    After considering comments received on the 2012 and 2013 proposals,
in the 2014 final rule, EPA finalized approval of Wyoming's
determination that BART for Jim Bridger Units 1 and 2 was LNB/SOFA and
that SCR should be required for reasonable progress as part of the
State's long-term strategy by 2021 and 2022. EPA explained that the
updated source-wide visibility improvement associated with the
installation of LNB/SOFA + SCR would be significant (1.25-

1.5 deciviews) with unit-specific visibility benefits for Units 1 and 2
at 0.27-0.37 deciviews at the most impacted Class I area (Bridger),
respectively. We explained that ``[t]he fact that Jim Bridger Station
affects a number of other Class I areas [(in addition to Bridger)],
which would also see appreciable visibility improvement with the
installation of LNB/SOFA + SCR, also weighs in favor of selecting this
option as BART.'' \36\ We also found that the updated average cost-
effectiveness of LNB/SOFA + SCR at $2,635 and $3,403/ton for Units 1
and 2, respectively, was in line with what we had found to be
acceptable in other determinations,\37\ in addition to finding that the
incremental cost-effectiveness of $7,447 and $8,968/ton for Units 1 and
2, respectively, was on the high end of what we had found to be
reasonable in other determinations.\38\ However, EPA ultimately
concluded that, ``while we believe that these costs and visibility
improvements could potentially justify LNB/SOFA + SCR as BART, because
this is a close call and because the State has chosen to require SCR as
a reasonable progress control, we believe deference to the State is
appropriate in this instance.'' \39\ We thus finalized the State's
determination to require LNB/SOFA as BART controls with a corresponding
emission limit of 0.26 lb/MMBtu by March 4, 2019, for Jim Bridger Units
1 and 2, and the State's determination to require SCR as part of the
State's long-term strategy necessary to achieve reasonable progress
with a corresponding emission limit of 0.07 lb/MMBtu (30-day rolling
average) by 2022 and 2021 for Jim Bridger Units 1 and 2,
respectively.\40\
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    \36\ 79 FR 5048.
    \37\ 79 FR 5040, 5048. Note that the text at 79 FR 5048
misstates the average cost-effectiveness for LNB/SOFA + SCR at Units
1 and 2. The correct figures are stated in Table 5 and 6 at 79 FR
5040. Note that for Jim Bridger Units 3 and 4, we disagreed with
Wyoming's conclusion that BART was not LNB/SOFA + SCR, but we
nonetheless approved the State's BART and reasonable progress
determinations of 0.26 lb/MMBtu (30-day rolling average) and 0.07
lb/MMBtu (30-day rolling average), respectively, because the
compliance deadlines for SCR were all within the statutory timeframe
for BART. 77 FR 33035-36; 79 FR 5046, 5221.
    \38\ 79 FR 5048.
    \39\ Id.
    \40\ 79 FR 5048-49.
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B. May 14, 2020 Submittal

    Notwithstanding the State's 2011 determination to require the
installation of SCR as being necessary for reasonable progress in the
State's long-term strategy for Jim Bridger 1 and 2 in 2021 and 2022,
and the deference EPA afforded the State's determination in the 2014
final rule (instead of requiring SCR as BART controls within five years
of EPA's action), on May 14, 2020, Wyoming submitted a SIP revision for
the purpose of amending the State's regional haze SIP and removing the
SCR requirement for Jim Bridger Units 1 and 2.\41\ Wyoming stated that
``[d]ue to the significant costs of installing SCR on Units 1 and 2,
and the potential impact of those costs to PacifiCorp's customers,
PacifiCorp reassessed its compliance with the Regional Haze Rule and
developed an alternative regional haze compliance strategy . . . .''
\42\
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    \41\ Letter dated May 12, 2020, from Todd Parfitt, Director,
Wyoming Department of Environmental Quality, to Gregory Sopkin,
Regional Administrator, EPA Region 8, Subject: State Implementation
Plant Approval Request--Regional Haze 309(g) SIP revision for
PacifiCorp Jim Bridger Power Plant.
    \42\ Wyoming 2020 SIP Revision at 3.
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    The State's 2020 SIP revision contains a source-specific,
NOX-only reasonable progress analysis and determination for
Jim Bridger Units 1 and 2, as well as plant-wide annual and monthly
NOX and SO2 emission limits for Jim Bridger Units
1-4. Specifically, the amendments provide a source-specific reasonable
progress four-factor analysis and consideration of visibility benefits
for Jim Bridger Units 1 and 2 to demonstrate that the current LNB/SOFA
NOX BART controls also satisfy the reasonable progress
requirements for those units for the first planning period. The SIP
revision thereby would remove the existing reasonable progress
requirement for Jim Bridger Units 1 and 2 to comply with emission
limits of 0.07 lb/MMBtu in 2021 and 2022 (Table 1).

                  Table 1--Existing and Proposed NOX Emission Limits for Jim Bridger Units 1-4
----------------------------------------------------------------------------------------------------------------
                                                                               Existing NOX       Proposed NOX
                                                         Existing NOX BART      reasonable         reasonable
                                                           emission limit   progress emission  progress emission
                          Unit                            (30-day rolling     limit (30-day      limit (30-day
                                                            average; lb/     rolling average;   rolling average;
                                                             MMBtu) \1\       lb/MMBtu) \2\        lb/MMBtu)
----------------------------------------------------------------------------------------------------------------
1......................................................               0.26               0.07               0.26
2......................................................               0.26               0.07               0.26
3......................................................               0.26               0.07            \3\ N/A
4......................................................               0.26               0.07            \3\ N/A
----------------------------------------------------------------------------------------------------------------
\1\ Compliance date is March 4, 2019; no changes to the NOX BART emission limits are proposed.
\2\ Compliance dates for each is: Unit 1 = December 31, 2022; Unit 2 = December 31, 2021; Unit 3 = December 31,
  2015; and Unit 4 = December 31, 2016.
\3\ No change to existing NOX reasonable progress emission limit of 0.07 lb/MMBtu (30-day rolling average).

    In addition, Wyoming's 2020 SIP revision would add federally
enforceable month-by-month plant-wide NOX and SO2
emission limits across all four Jim Bridger units, as well as an
enforceable annual plant-wide NOX and SO2
emissions cap of 17,500 tpy, effective January 1, 2022 (Table 2). The
plant-wide monthly and annual emission limits for Jim Bridger Units 1-4
are already State-enforceable through Wyoming air quality permit
#P0025809. The final permit was issued on May 5, 2020.\43\
---------------------------------------------------------------------------

    \43\ Letter dated May 5, 2020, from Nancy E. Vehr,
Administrator, Air Quality Division, Wyoming Department of
Environmental Quality, to James Owens, Director, Environmental
Services, PacifiCorp, Subject: Permit #P0025809 (Permit #0025809).

   Table 2--Enforceable Monthly Plant-Wide Block NOX and SO2 Emission
       Limits for Jim Bridger Units 1-4, Effective January 1, 2022
------------------------------------------------------------------------
                                     Total units 1-4    Total units 1-4
                                       NOX emission       SO2 emission
               Month                  limit (monthly     limit (monthly
                                      average basis)     average basis)
                                        (lb/hour)          (lb/hour)
------------------------------------------------------------------------
January...........................              2,050              2,100
February..........................              2,050              2,100
March.............................              2,050              2,100
April.............................              2,050              2,100
May...............................              2,200              2,100
June..............................              2,500              2,100
July..............................              2,500              2,100
August............................              2,500              2,100
September.........................              2,500              2,100
October...........................              2,300              2,100
November..........................              2,030              2,100
December..........................              2,050              2,100
------------------------------------------------------------------------

C. Summary of Wyoming's Reasonable Progress Reassessment

    Pursuant to CAA section 169A(g)(1) and 40 CFR 51.308(d)(1)(i)(A),
in determining the measures necessary to make reasonable progress, a
state must take into account the following four factors and demonstrate
how they were taken into consideration in making a reasonable progress
determination:
     Costs of Compliance;
     Time Necessary for Compliance;
     Energy and Non-Air Quality Environmental Impacts of
Compliance; and
     Remaining Useful Life of Any Potentially Affected Sources.
    In order to conduct a source-specific reasonable progress
assessment for Jim Bridger Units 1 and 2, the State took into
consideration the four required factors and also included visibility
improvement as an additional factor in its reasonable progress
analysis.\44\ Wyoming relied on information provided by PacifiCorp and
EPA for evaluating potential reasonable progress NOX
emissions controls--LNB/SOFA, LNB/SOFA + selective non-catalytic
reduction (SNCR), and LNB/SOFA + SCR--at Jim Bridger.\45\
---------------------------------------------------------------------------

    \44\ The visibility benefit of an emissions reduction measure is
not listed as a required factor, but neither the CAA nor the
Regional Haze Rule prohibits a state from considering visibility
benefits when it determines what emissions control measures are
required for a source to make reasonable progress at a Class I area.
Therefore, a state may consider the visibility benefits of potential
control measures when determining what is necessary to make
reasonable progress.
    \45\ Wyoming 2020 SIP Revision at 3; see also PacifiCorp, Jim
Bridger Power Plant Reasonable Progress Determination to Support
PacifiCorp's Reasonable Progress Reassessment (PacifiCorp
Reassessment), February 2019.
---------------------------------------------------------------------------

1. Costs of Compliance
    For the source-specific reasonable progress analysis associated
with this action, Wyoming relied on cost information provided by
PacifiCorp. PacifiCorp used NOX emission rates for LNB/SOFA
of 0.187 lb/MMBtu and 0.192 lb/MMBtu (annual average) reflective of the
actual emissions rate (2013-2015) for Units 1 and 2, respectively. The
anticipated NOX emission rate for LNB/SOFA + SNCR was
assumed to be 0.15 lb/MMBtu (annual) for both Units 1 and 2. The
NOX emission rate for LNB/SOFA + SCR was assumed to be 0.05
lb/MMBtu (annual), which corresponds to the 0.07 lb/MMBtu LNB/SOFA +
SCR NOX 30-day rolling average emission limits for Units 1
and 2 that EPA approved in the 2014 final rule.
    Wyoming's source-specific reasonable progress analysis for Units 1
and 2 based capital costs and annual operating and maintenance (O&M)
costs on the actual costs incurred to install and operate SCR
technology on Jim Bridger Units 3 and 4, as well as the actual costs to
install LNB/SOFA on Units 1 and 2 (Table 3). Capital costs for SNCR
technology were estimated based on recent similarly sized projects
(Table 3).\46\
---------------------------------------------------------------------------

    \46\ Wyoming 2020 SIP Revision, PacifiCorp, Corrected JB RP
Reassessment NOX Comparison Tables, October 6, 2020.

Table 3--PacifiCorp's Total Capital and O&M Costs for the Jim Bridger Units 1 and 2 Reasonable Progress Analysis
----------------------------------------------------------------------------------------------------------------
                                                   Total installed capital costs     Total O&M costs ($/year)
                                                                ($)              -------------------------------
             NOX control technology              --------------------------------
                                                      Unit 1          Unit 2          Unit 1          Unit 2
----------------------------------------------------------------------------------------------------------------
LNB/SOFA........................................      $8,410,000      $7,986,000  ..............  ..............
SNCR............................................      15,538,000      15,538,000       2,954,000       3,158,000
SCR.............................................     140,428,000     140,428,000       2,580,000       2,527,000
----------------------------------------------------------------------------------------------------------------

    PacifiCorp annualized capital costs using the capital recovery
factor (CRF) approach described in EPA's Control Cost Manual using 20-
year and 30-year amortization periods for SNCR and SCR,
respectively.\47\ Total annual costs were calculated as the sum of the
annualized capital costs and total O&M costs. The cost-effectiveness of
each NOX control technology was calculated on a dollar-per-
ton of pollutant removed basis by dividing the total annual costs by
the reduction in annual NOX emissions associated with each
NOX emissions control technology (i.e., LNB/SOFA, LNB/SOFA +
SNCR, LNB/SOFA + SCR). Similarly, PacifiCorp calculated the incremental
cost-effectiveness of each NOX control technology on a
dollar-per-ton of pollutant removed basis by dividing the difference of
the total annual costs (of one control technology compared to that of
the next most stringent control technology) by the difference in the
reduction in annual NOX emissions (of the two control
technologies).
---------------------------------------------------------------------------

    \47\ EPA, ``Control Cost Manual,'' Section 4, Chapter 1, April
25, 2019, page 1-53-54, and Chapter 2, June 2019, page 80, available
at https://www.epa.gov/economic-and-cost-analysis-air-pollution-regulations/cost-reports-and-guidance-air-pollution (last visited
December 2021).
---------------------------------------------------------------------------

    The summary of cost-effectiveness figures for Wyoming's reasonable
progress analysis for Jim Bridger Units 1 and 2 is shown in Table 4.
Baseline NOX emissions (2001-2003) are 8,432 tpy and 7,575
tpy for Units 1 and 2, respectively.
---------------------------------------------------------------------------

    \48\ Wyoming 2020 SIP Revision, PacifiCorp, Corrected JB RP
Reassessment NOX Comparison Tables, October 6, 2020.

        Table 4--Summary of Jim Bridger Units 1 and 2 NOX Revised Reasonable Progress Cost Analysis \48\
----------------------------------------------------------------------------------------------------------------
                                NOX emissions                                                      Incremental
                                  rate (lb/       Emissions     Annualized cost   Average cost-       cost-
    NOX control technology     MMBtu; annual)  reduction (tpy)      ($/year)      effectiveness   effectiveness
                                                                                ($/ton)         ($/ton)
----------------------------------------------------------------------------------------------------------------
                                                     Unit 1
----------------------------------------------------------------------------------------------------------------
LNB/SOFA.....................       \1\ 0.187  4,414..........  $794,000.......            $180  ...............
LNB/SOFA + SNCR..............        \2\ 0.15  5,209..........  5,215,000......           1,001  5,560
LNB/SOFA + SCR...............            0.05  7,358..........  14,692,000.....           1,997  4,410
----------------------------------------------------------------------------------------------------------------
                                                     Unit 2
----------------------------------------------------------------------------------------------------------------
LNB/SOFA.....................       \1\ 0.192  3,649..........  754,000........             207  ...............
LNB/SOFA + SNCR..............        \2\ 0.15  4,508..........  5,379,000......           1,193  5,385
LNB/SOFA + SCR...............            0.05  6,552..........  14,599,000.....           2,228  4,510
----------------------------------------------------------------------------------------------------------------
\1\ lb/MMBtu, annual average.
\2\ lb/MMBtu, annual. The controlled NOX emission rate with SNCR was assumed to be 0.15 lb./MMBtu, which
  corresponds with a reduction of approximately 20 percent.

    Wyoming also summarized the total estimated capital costs and
annual costs combined for Units 1 and 2 for the installation of SCR and
SNCR, in addition to the LNB/SOFA NOX emissions controls
already installed, for the revised reasonable progress analysis (Table
5).
---------------------------------------------------------------------------

    \49\ Wyoming 2020 SIP Revision at 5.

 Table 5--Total Capital and Annual Costs for Jim Bridger Units 1 and 2 Revised Reasonable Progress Analysis \49\
----------------------------------------------------------------------------------------------------------------
                                                                      Control      Capital costs   Annual costs
                     NOX control technology                       efficiency (%)        ($)          ($/year)
----------------------------------------------------------------------------------------------------------------
LNB/SOFA........................................................              53     $16,396,000      $1,548,000
LNB/SOFA + SNCR.................................................              63      47,472,000      10,594,000
LNB/SOFA + SCR..................................................              87     297,252,000      29,291,000
----------------------------------------------------------------------------------------------------------------

    Although Jim Bridger Units 3 and 4 are not included in the
reasonable progress analysis, Wyoming noted that the total capital cost
for LNB/SOFA + SCR installation on Units 3 and 4, which are already
installed, was $310,959,000. Ultimately, Wyoming concluded that the
installation of SCR on Jim Bridger Units 1 and 2 would cost ``hundreds
of millions more'' than the costs already incurred for LNB/SOFA
NOX emissions controls while SNCR would cost ``tens of
millions more'' than the costs already incurred for LNB/SOFA
NOX emissions controls.\50\
---------------------------------------------------------------------------

    \50\ Id.
---------------------------------------------------------------------------

2. Time Necessary for Compliance
    As stated previously, the SIP approved by EPA on January 30, 2014,
requires an emission limit of 0.07 lb/MMBtu associated with the
installation of LNB/SOFA + SCR on Jim Bridger Unit 1 by December 31,
2022, and on Unit 2 by December 31, 2021. Wyoming stated in the 2020
SIP revision that if SNCR installation was required, the compliance
timelines would match the SCR timeline. The current LNB/SOFA
NOX emissions controls were installed in 2010 and 2005 for
Units 1 and 2, respectively.\51\
---------------------------------------------------------------------------

    \51\ Id. at 6.
---------------------------------------------------------------------------

3. Energy and Non-Air Quality Environmental Impacts of Compliance
    The State identified that SCR control technology would periodically
produce solid waste when the catalyst is changed. Additionally, Wyoming
stated that SCR control technology would require the storage and use of
ammonia, while SNCR would require the storage

and use of urea. With respect to energy use, the State estimated that
SNCR would require 6 times the energy required by the current
NOX control technology (LNB/SOFA), and SCR would require 150
times the energy required by LNB/SOFA. Wyoming further stated that SCR
would require the use of an additional 10.4 megawatts of energy.
Wyoming did not anticipate any additional negative non-air
environmental impacts associated with the current LNB/SOFA
NOX emissions controls.\52\
---------------------------------------------------------------------------

    \52\ Id. at 6.
---------------------------------------------------------------------------

4. Remaining Useful Life
    For this evaluation, Wyoming stated that the expected life of the
source is less than the expected life of the emissions control
technology, which is 30 years for SCR and 20 years for SNCR. However,
Wyoming did not provide an enforceable shutdown date that would ensure
that the expected life of the source would in fact be reduced.\53\
Therefore, notwithstanding the State's expectation of a shortened
remaining useful life for the source, it used the full 30-year and 20-
year periods for SCR and SNCR, respectively, in its analyses.
---------------------------------------------------------------------------

    \53\ Id. at 4.
---------------------------------------------------------------------------

5. Visibility Improvement
    Although visibility improvement is not one of the four statutory
factors for reasonable progress, Wyoming elected to include visibility
improvement in the reasonable progress analysis for Jim Bridger Units 1
and 2. Wyoming did not complete new visibility modeling for the
reasonable progress analysis and determination. Instead, the State
relied upon EPA's CALPUFF modeling results contained in the 2014 final
rule to assess the visibility impacts of the NOX emissions
control technologies evaluated, i.e., for LNB/SOFA, LNB/SOFA + SNCR,
LNB/SOFA + SCR.\54\ In our 2014 final rule, we evaluated the CALPUFF
visibility modeling of the Jim Bridger power plant for the most
impacted Class I area, Bridger Wilderness (Table 6).\55\
---------------------------------------------------------------------------

    \54\ See id. at 7. In the 2014 final rule, EPA addressed
comments on the visibility improvement modeling by developing a new
protocol that makes several improvements in the modeling, including
the latest regulatory version of the CALPUFF model at the time of
the rule (version 5.8), the use of an improved method to assess the
effects of pollutants on light scattering and visibility impairment
(Method 8), the use of background ammonia concentrations based on
monitoring data and regulatory default concentrations for the area,
and the use of an ammonia-limiting correction to treat sources with
multiple units. We used two sets of background ammonia
concentrations based on representative monthly varying ammonia
concentrations and default concentrations for forested areas.
    \55\ 79 FR 5048.

          Table 6--Summary of Jim Bridger Power Plant NOX Visibility Analysis in EPA's 2014 Final Rule
----------------------------------------------------------------------------------------------------------------
                                                         Visibility Improvement (deciviews) \1\ (modeled results
                                                             using an ammonia background based on a monitored
                                                           monthly varying concentration/modeled results using
                      Jim Bridger                             IWAQM default 0.5 ppb background ammonia) \3\
                                                        --------------------------------------------------------
                                                              LNB/SOFA       LNB/SOFA + SNCR     LNB/SOFA + SCR
----------------------------------------------------------------------------------------------------------------
Unit 1.................................................          0.17/0.23          0.20/0.27          0.27/0.37
Unit 2.................................................          0.16/0.21          0.19/0.25          0.27/0.36
Unit 3.................................................          0.14/0.19          0.17/0.23          0.26/0.35
Unit 4.................................................          0.25/0.23          0.30/0.28          0.45/0.42
                                                        --------------------------------------------------------
    Total \2\..........................................          0.72/0.86          0.86/1.03           1.25/1.5
----------------------------------------------------------------------------------------------------------------
\1\ For most impacted Class I area, Bridger Wilderness.
\2\ The total visibility improvement was estimated as the sum of the visibility improvement from each unit.
\3\ EPA, Air Quality Modeling Protocol; Wyoming Regional Haze Implementation Plan, January 2014.

    The State noted that EPA determined in 2014 that the unit-specific
visibility benefits for LNB/SOFA + SCR installation on Units 1 and 2
were ``modest'' at 0.27 to 0.37 deciviews. In addition, the State noted
that the incremental visibility improvement, as determined by EPA, of
LNB/SOFA + SCR over LNB/SOFA, was 0.10 to 0.14 deciviews for Unit 1 and
0.11 to 0.15 deciviews for Unit 2. The State further noted that
incremental improvement of LNB/SOFA + SNCR over LNB/SOFA was smaller at
between 0.03-0.04 deciviews for both Units 1 and 2.\56\
---------------------------------------------------------------------------

    \56\ Wyoming 2020 SIP Revision at 7.
---------------------------------------------------------------------------

    In addition to comparing the visibility impacts associated with
each NOX emissions control technology, Wyoming also pointed
to PacifiCorp's estimated NOX emissions reductions. The
State asserted that the current LNB/SOFA NOX emissions
controls already have reduced NOX emissions from the 2001-
2003 baseline by a combined 8,063 tpy for Units 1 and 2. The
installation of SCR would reduce NOX emissions from the
2001-2003 baseline by an additional 5,848 tpy (Units 1 and 2 combined),
while the installation of SNCR would reduce NOX emissions
from the baseline by an additional 1,655 tpy.\57\
---------------------------------------------------------------------------

    \57\ Id.
---------------------------------------------------------------------------

    According to the State, in spite of the additional NOX
emissions reductions achievable through each NOX control
technology, EPA's 2014 modeling demonstrates that the installation of
SCR on Units 1 and 2 would result in only modest incremental visibility
benefits of 0.10-0.15 deciviews (per unit) when compared to current
LNB/SOFA NOX emissions controls on Units 1 and 2. The State
concluded that these visibility improvements are not significant enough
to outweigh the substantial cost of installing SCR. Instead, Wyoming
concluded that relying on the current NOX emissions controls
(LNB/SOFA) is the reasonable choice for Jim Bridger Units 1 and 2.\58\
---------------------------------------------------------------------------

    \58\ Id. at 7-8.
---------------------------------------------------------------------------

6. Reasonable Progress Demonstration

    After considering each of the four reasonable progress factors,
states must demonstrate how those factors, and visibility improvement
if included in the analysis, were taken into consideration in making a
reasonable progress determination.\59\ Thus, after consideration of the
four factors, along with an evaluation of the modeled visibility
impacts at the most impacted Class I area (Bridger Wilderness), Wyoming
determined that no additional controls beyond BART are necessary for
Jim Bridger Units 1 and 2 under the reasonable progress provisions for
the first regional haze planning period. Wyoming determined that,
``[w]hile SCR installation on Units 1 & 2 could be expected to be more
efficient in controlling NOX emission than either SNCR
installation or relying on Current Unit 1-2 NOX Controls
[(LNB/SOFA)], the estimated capital costs, annual costs, and cost-
effectiveness are far higher for SCR and SNCR, compared with little
modeled visibility benefit.'' \60\ In addition, the State explained
that SCR will produce solid waste every time the catalyst must be
replaced and will have higher electricity requirements. The State
further explained that the current NOX controls are already
in use and do not require additional time for compliance.\61\
---------------------------------------------------------------------------

    \59\ 40 CFR 51.308(d)(1)(i)(A).
    \60\ Wyoming 2020 SIP Revision at 7.
    \61\ Id.
---------------------------------------------------------------------------

    Wyoming stated that its reasonable progress determination for Jim
Bridger Units 1 and 2 is consistent with several similar EPA decisions
where EPA rejected SNCR and SCR because the cost-effectiveness values
associated with the control measures were significantly higher and/or
the NOX emissions reductions achieved were not that much
more than combustion controls (LNB) alone.\62\ Furthermore, Wyoming
stated that it considers the costs that PacifiCorp has already incurred
on NOX emissions control technology at the Jim Bridger power
plant and the associated improvement in visibility to be sufficient for
reasonable progress.\63\
---------------------------------------------------------------------------

    \62\ Id. at 7, 8 (citing 77 FR 24794 (April 25, 2012), 77 FR
11879 (February 28, 2012), 77 FR 18052 (March 26, 2012), 77 FR 23988
(April 20, 2012), 83 FR 62204 (November 30, 2018), 80 FR 18944
(April 8, 2015), 77 FR 21896 (April 12, 2012)).
    \63\ Id. at 7.
---------------------------------------------------------------------------

    In summary, Wyoming concluded that the reasonable progress analysis
demonstrates that the current NOX emissions controls (LNB/
SOFA) on Units 1 and 2, including the current NOX emission
limits of 0.26 lb/MMBtu (30-day rolling average), which apply to each
unit, constitute NOX reasonable progress for Jim Bridger
Units 1 and 2. Therefore, Wyoming's 2020 SIP revision would remove the
emission limits of 0.07 lb/MMBtu (30-day rolling average) associated
with the installation of SCR at Jim Bridger Units 1 and 2 as part of
the State's long-term strategy to achieve reasonable progress at
several Class I areas for the first planning period.\64\
---------------------------------------------------------------------------

    \64\ Id. at 8.
---------------------------------------------------------------------------

D. Summary of Wyoming's Plant-Wide Monthly and Annual NOX and SO2
Emission Limits for Jim Bridger

    In addition to concluding that emission limits consistent with LNB/
SOFA are sufficient for reasonable progress for Jim Bridger Units 1 and
2, the State asserted that PacifiCorp's plant-wide monthly and annual
NOX and SO2 emission limits for Jim Bridger Units
1-4 strengthen and support the reasonable progress determination for
Jim Bridger Units 1 and 2. Specifically, the State quoted EPA's 2007
Reasonable Progress Goals Guidance (2007 Guidance), which provides that
States ``have flexibility in how to take into consideration [the]
statutory factors and any other factors [the state has] determined to
be relevant,'' \65\ in claiming that PacifiCorp's monthly plant-wide
NOX and SO2 emission limits (shown in Table 2)
and the annual plant-wide NOX and SO2 emissions
cap of 17,500 tpy are relevant in Wyoming's revised reasonable progress
analysis and determination. The State pointed to a number of factors to
describe how the plant-wide monthly and annual NOX and
SO2 emission limits bolster the revised reasonable progress
analysis. These include what the State asserted are greater modeled
visibility improvement, lower costs, and fewer overall energy and
environmental impacts than the installation of SCR and SNCR on Units 1
and 2.\66\
---------------------------------------------------------------------------

    \65\ Wyoming 2020 SIP Revision at 8-9 (quoting EPA's ``Guidance
for Setting Reasonable Progress Goals Under the Regional Haze
Program,'' June 1, 2007 (2007 Guidance)).
    \66\ Wyoming 2020 SIP Revision at 8-12.
---------------------------------------------------------------------------

    Wyoming relied on CALPUFF visibility modeling conducted by
PacifiCorp to evaluate visibility improvement associated with the
plant-wide monthly and annual NOX and SO2
emission limits compared to LNB/SOFA + SCR and LNB/SOFA + SNCR.\67\ The
CALPUFF modeling report used the following three metrics to evaluate
the results:
---------------------------------------------------------------------------

    \67\ Wyoming chose the CALPUFF visibility model because it was
the same model used to analyze the existing reasonable progress
requirements (79 FR 5039). See Wyoming 2020 SIP Revision at 11.
---------------------------------------------------------------------------

     The 98th percentile modeled delta-deciview, averaged over
the 3 years modeled and applied to each Class I area individually;
     The number of modeled days (summed over the 3 years
modeled) with a plant-wide impact above 0.5 delta-deciview, applied to
each Class I area individually; and
     The number of modeled days (summed over the 3 years
modeled) with a plant-wide impact above 1.0 delta-deciview, applied to
each Class I area individually.
    Under all three metrics, Wyoming asserted that the updated CALPUFF
modeling results demonstrate that the plant-wide monthly and annual
NOX and SO2 emission limits resulted in greater
visibility improvement than SCR and SNCR.\68\
---------------------------------------------------------------------------

    \68\ Id. at 11-12.
---------------------------------------------------------------------------

    With respect to the 98th percentile metric, the State asserted that
the visibility impacts for the Jim Bridger power plant under the SCR,
SNCR, and plant-wide monthly and annual NOX and
SO2 emission limits scenarios are 0.760, 0.930, and 0.653
deciviews, respectively.\69\ Wyoming further asserted that the number
of CALPUFF-modeled days resulting in a plant-wide visibility impact
above 0.5 delta-deciviews over a three-year period under the SCR, SNCR,
and plant-wide monthly and annual NOX and SO2
emission limits scenarios are 475, 597, and 371 days, respectively.
Finally, with respect to the number of CALPUFF-modeled days resulting
in a plant-wide visibility impact above 1.0 delta-deciview over a
three-year period under the SCR, SNCR, and plant-wide monthly and
annual NOX and SO2 emission limits scenarios are
127, 195, and 108 days, respectively, according to the State.\70\
---------------------------------------------------------------------------

    \69\ Averaged across all impacted Class I areas, including
Bridger Wilderness, Fitzpatrick Wilderness, Grand Teton National
Park, Mt. Zirkel Wilderness, Rocky Mountain National Park, Rawah
Wilderness, Teton Wilderness, Washakie Wilderness, and Yellowstone
National Park. PacifiCorp Reassessment at 15.
    \70\ Id. at 11-12.
---------------------------------------------------------------------------

    According to Wyoming, installation of SCR and SNCR on Units 1 and 2
will result in the reduction of NOX emissions of 5,848 and
1,655 tpy respectively, relative to ``current operating potential.''
``Current operating potential,'' as defined in PacifiCorp's technical
analysis, is based on a combination of recent emission rates with
plant-wide heat input (i.e., utilization) from the 2001-2003
period.\71\ Implementation of the plant-wide monthly and annual
NOX and SO2 emission limits will result in the
reduction of NOX and SO2

emissions of 6,056 tpy relative to a baseline of 2001-2003 utilization.
In addition to reductions in NOX and SO2
emissions, Wyoming stated that the plant-wide emission limits will
reduce all emissions from the Jim Bridger power plant, including PM,
mercury (Hg), greenhouse gases (GHG), carbon monoxide (CO), carbon
dioxide (CO2), and sulfuric acid
(H2SO4), as well as reduce coal consumption, coal
combustion residual production and disposal, and raw water
consumption.\72\
---------------------------------------------------------------------------

    \71\ See PacifiCorp Reassessment, Attachment 1 at 21.
    \72\ Id. at 9-10.
---------------------------------------------------------------------------

    To compare cost-effectiveness estimates, the State relied on
PacifiCorp's analysis using total tons of SO2 and
NOX reduced from ``current operating potential'' under the
assumption that the pollutants would have equivalent visibility impacts
(Table 7).

 Table 7--PacifiCorp's Summary of Jim Bridger Units 1-4, Cost Analysis for SCR, SNCR, and Plant-Wide Monthly and
                                       Annual NOX and SO2 Emission Limits
----------------------------------------------------------------------------------------------------------------
                                                                                Cost-
              Jim Bridger                  Control technology      Capital cost     Annualized     effectiveness
                                                                        ($)        cost ($/year)      ($/ton)
----------------------------------------------------------------------------------------------------------------
Units 1-2.............................  SCR.....................     280,856,000      27,743,000           4,744
Units 1-2.............................  SNCR....................      31,076,000       9,046,000           5,469
Units 1-4.............................  Monthly and Annual Plant-      4,659,000       2,115,000             349
                                         Wide Emission Limits.
----------------------------------------------------------------------------------------------------------------

    Wyoming also asserted that the plant-wide monthly and annual
NOX and SO2 emission limits are more cost-
effective than SCR or SNCR. Furthermore, Wyoming claimed that even if
all three emissions control measures are compared on a NOX-
only basis (excluding SO2), the plant-wide monthly and
annual NOX and SO2 emission limits remain the
most cost-effective option.\73\
---------------------------------------------------------------------------

    \73\ Id. at 9-10.
---------------------------------------------------------------------------

    In addition to the asserted visibility and cost benefits associated
with the plant-wide monthly and annual NOX and
SO2 emission limits, Wyoming compared the energy and non-air
quality environmental impacts of compliance. First, Wyoming contended
that, as compared to the use of SCR, the plant-wide monthly and annual
NOX and SO2 emission limits would allow
approximately 10.4 megawatts of electrical energy required by SCR for
Units 1 and 2 to be instead directed to the electrical grid to power
approximately 8,761 average homes. Second, Wyoming asserted that the
installation of SCR controls on Units 1 and 2 would not restrict the
capacity factor of these units (e.g., the annual heat output), so these
units could operate with a potential average annual capacity factor of
100 percent. In contrast, Wyoming explained that implementation of the
plant-wide monthly and annual NOX and SO2
emission limits would limit the capacity of all four units and
effectively limit annual boiler heat input, thereby also providing a
reduction in the consumption of natural resources (i.e., water and
coal). Third, Wyoming asserted that the installation of SCR at Units 1
and 2 would result in additional storage and use of ammonia and create
more coal combustion residuals. Likewise, the installation of SNCR on
Units 1 and 2 would result in additional storage and use of urea and
would also create more coal combustion residuals compared to the plant-
wide monthly and annual NOX and SO2 emission
limits. Finally, Wyoming asserted that the plant-wide monthly and
annual NOX and SO2 emission limits provide the
entire facility the flexibility to ``load follow'' or accommodate
intermittent influx of renewable energy into the western power grid,
which has larger scale environmental impacts in Wyoming and across the
West.\74\
---------------------------------------------------------------------------

    \74\ Id. at 10-11.
---------------------------------------------------------------------------

IV. EPA's Evaluation and Proposed Disapproval of Wyoming's Regional
Haze SIP Revisions

A. Basis for Proposed Disapproval

    Although states have discretion under the Regional Haze Rule to
balance the four statutory factors in making control determinations for
sources, their analyses must be both reasoned and moored to the
statutory requirement to make reasonable progress toward the national
visibility goal.\75\ The Regional Haze Rule provides that, ``in
determining whether the State's goal for visibility improvement
provides for reasonable progress toward natural visibility conditions,
the Administrator will evaluate'' the state's demonstration under 40
CFR 51.308(d)(1)(i) and (ii).\76\ Thus, our regulations and the CAA
require that we review the reasonableness of the State's reasonable
progress determination in light of the goal of achieving natural
visibility conditions. This approach is also inherent in our role as
the administrative agency empowered to review and approve SIPs. In this
SIP review action, EPA is not only authorized, but required to exercise
independent technical judgement in evaluating the adequacy of the
State's regional haze SIP, including its reasonable progress
determinations.\77\
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    \75\ Cf. Arizona v. EPA, 815 F.3d 519, 531 (9th Cir. 2016)
(While states have discretion to balance the five BART factors, they
must also adhere to certain requirements when conducting BART
analyses. EPA may not approve BART determinations that are based on
analyses that are unreasoned or unmoored to the statutory
provisions.) (citing N. Dakota v. EPA, 730 F.3d 750, 761 (8th Cir.
2013)).
    \76\ 40 CFR 51.308(d)(1)(iii).
    \77\ 42 U.S.C. 7410(a)(2)(J), (l), (k)(3); 7491(a)(1),
(b)(2)(B); Oklahoma v. EPA, 723 F.3d 1201 (10th Cir. 2013).
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    For the reasons described in section IV.B. below, EPA proposes to
disapprove Wyoming's regional haze SIP revision. Our proposed action is
based on an evaluation of Wyoming's 2020 SIP revision under the
regional haze requirements at 40 CFR 51.300-51.309 and CAA section
169A. The revisions were also evaluated against the general SIP
requirements contained in CAA section 110 and our regulations
applicable to this action. Additionally, EPA is not reopening, and thus
not accepting comment on, EPA's 2014 approval of Wyoming's BART
determinations for Jim Bridger Units 1-4 or EPA's 2014 approval of the
emission limits Wyoming required as reasonable progress controls for
Jim Bridger Units 3 and 4. Any comments on these issues will be deemed
beyond the scope of this action.

B. EPA's Proposed Disapproval of Wyoming's Reasonable Progress
Determination for Jim Bridger Units 1 and 2

    We are proposing to disapprove Wyoming's regional haze SIP revision
for the NOX reasonable progress determination for Jim
Bridger Units 1 and 2.
    In our analysis of the Wyoming 2020 SIP revision, we evaluated
Wyoming's reasonable progress determination for Jim Bridger Units 1 and
2 under 40 CFR 51.308(d)(1)(i)(A). Under this requirement, a state must
consider the following four factors and include a demonstration of how
they were taken into consideration in making a reasonable progress
determination:
     Costs of Compliance;
     Time Necessary for Compliance;
     Energy and Non-Air Quality Environmental Impacts of
Compliance; and
     Remaining Useful Life of Any Potentially Affected Sources.
    The State has discretion to reasonably weigh these four factors,
along with visibility improvement if it so chooses, to determine what
controls are necessary to include in the long-term strategy for a
specific source. States exercise this discretion within the context of
the statutory requirement to make reasonable progress toward the
national visibility goal.\78\
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    \78\ 42 U.S.C. 7491(a)(1), (b)(2)(B); 40 CFR 51.308(d)(1)(iii).
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1. Basis of Our Proposed Disapproval
    We are proposing to find that Wyoming's 2020 SIP revision does not
provide a reasonable basis for reversing the State's 2011 determination
of what reasonable progress controls are necessary for Jim Bridger
Units 1 and 2 for the first planning period. Our proposed disapproval
is based on the following: (1) The reasonable cost-effectiveness of the
existing control requirements for Jim Bridger Units 1 and 2 (emission
limits consistent with the installation of SCR); (2) the appreciable
visibility improvement estimated to result from compliance with the
existing reasonable progress control requirements; and (3) the fact
that the State previously determined that the costs of those control
requirements were reasonable and that they are necessary to satisfy the
statutory requirements, and has not provided any new information that
would support a revised determination that the existing control
requirements are now unreasonable. Because the State has not provided
adequate justification for reversing its 2011 determination, removing
the existing emission limits reflecting LNB/SOFA + SCR from the SIP
would be inconsistent with the requirement that SIPs contain the
measures necessary to make reasonable progress toward the national
visibility goal. We therefore propose to disapprove the State's 2020
SIP revision.
    As an initial matter, we propose to find that the State reasonably
characterized the four factors required in a reasonable progress
analysis, including the costs of compliance, the time necessary for
compliance, energy and non-air quality environmental impacts of
compliance, and the remaining useful life of any potentially affected
sources. In addition, we agree with the State that, although visibility
improvement is not one of the four factors required by CAA section
169A(g)(1) and 40 CFR 51.308(d)(1)(i)(A), visibility improvement (along
with the statutory factors) can be considered to determine what control
measures are necessary to make reasonable progress.\79\
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    \79\ See 77 FR 57864, 57899 (September 18, 2012), 79 FR 9318,
9353-54 (February 18, 2014), 81 FR 296, 309-310 (January 5, 2016).
See also 2007 Guidance at page 5-1.
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    We are also specifically proposing to find that Wyoming's revised
cost calculation is appropriate, including: (1) The use of actual
annual average (2013-2015) NOX emissions rates for LNB/SOFA;
(2) the use of NOX emissions rates of 0.15 and 0.05 lb/MMBtu
(annual) for LNB/SOFA + SNCR and LNB/SOFA + SCR, respectively; (3) the
use of amortization periods of 20, 20, and 30 years for LNB/SOFA, SNCR
and SCR, respectively; (4) the use of actual costs for the installation
and operation of SCR taken from those incurred for Units 3 and 4; and
(5) the use of a baseline of 2001-2003 emissions to analyze cost and
visibility associated with LNB/SOFA, LNB/SOFA + SNCR, and LNB/SOFA +
SCR.
    However, as explained previously, notwithstanding our proposed
finding that Wyoming reasonably characterized relevant information
under each of the four statutory factors, we are proposing to find that
the State did not reasonably consider that information in reaching its
revised reasonable progress determination.
    Of the four reasonable progress factors and the optional visibility
improvement factor, the State placed significant emphasis on the costs
of compliance in its analysis of controls for Jim Bridger Units 1 and
2. Consistent with the State's analysis, we afford this factor similar
significance in our evaluation here. We are also evaluating the
visibility improvement information that Wyoming considered in the SIP
revision, as well as the other three factors--remaining useful life,
time necessary for compliance, and energy and non-air environmental
impacts. After a consideration of all five of these factors, we propose
to conclude that the State's determination that the installation of SCR
is not necessary for reasonable progress is unreasonable.
a. Costs of Compliance
    In order to evaluate Wyoming's 2020 SIP revision with respect to
the cost of compliance, we first evaluate Wyoming's characterization of
the costs using the updated Control Cost Manual. Next, we evaluate the
reasonableness of the costs associated with the installation of SCR on
Units 1 and 2 with respect to average and incremental cost-
effectiveness and the State's explanation for why requiring SCR on
Units 1 and 2 is unreasonable.
    The revised NOX control cost estimates in Wyoming's 2020
SIP revision are based on the current version of the Control Cost
Manual, which has been revised since our 2014 final rule. As updated,
the Control Cost Manual includes a 30-year equipment life for SCR.\80\
The change in equipment life estimate from 20 to 30 years for SCR
affects annual cost estimates, as well as average cost-effectiveness
and incremental cost-effectiveness estimates. We propose to find
Wyoming's use of the updated Control Cost Manual appropriate.
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    \80\ EPA, ``Control Cost Manual,'' Section 4, Chapter 2, June
2019, page 80, available at https://www.epa.gov/economic-and-cost-analysis-air-pollution-regulations/cost-reports-and-guidance-air-pollution (last visited December 2021).
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    In the 2020 SIP revision, Wyoming provided updated capital costs,
annual costs, and average and incremental cost-effectiveness figures
for SNCR, SCR, and the plant-wide annual and monthly limits.\81\ The
2007 Guidance instructs that states should evaluate both average and
incremental costs according to the Control Cost Manual to maintain and
improve consistency.\82\ These figures take into account capital and
annual costs and allow states and EPA to compare costs of controls
industry wide. EPA's guidance further cautions against

considering in isolation the capital costs of a control option, as
large or small capital costs alone are not dispositive of the
reasonableness of a potential control.\83\ Thus, we deem the average
and incremental cost-effectiveness figures most relevant to our
consideration of Wyoming's revised cost analysis.
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    \81\ Wyoming 2020 SIP Revision at 4-5.
    \82\ 2007 Guidance at page 5-1, 2 (referring to the BART
Guidelines and Control Cost Manual). See also 40 CFR part 51,
appendix Y, IV.D.4.b (``For purposes of air pollutant analysis,
`effectiveness' is measured in terms of tons of pollutant emissions
removed, and `cost' is measured in terms of annualized control
costs. We recommend two types of cost-effectiveness calculations--
average cost effectiveness, and incremental cost effectiveness.'').
    \83\ See 40 CFR part 51, appendix Y, IV.D.4.g.
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    In the revised cost analysis for the 2020 SIP revision, Wyoming's
cost estimates show an average cost-effectiveness for LNB/SOFA + SCR
for Units 1 and 2 of $1,997 and $2,228 per ton of NOX
removed, respectively.\84\ Wyoming's cost estimates also show an
incremental cost-effectiveness for LNB/SOFA + SCR for Units 1 and 2 of
$4,410 and $4,510 per ton of NOX removed, respectively,
relative to the next-most-stringent control (LNB/SOFA + SNCR).\85\
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    \84\ See Table 4 in this document. Because we are finding the
most stringent control technology (SCR) reasonable, and because
Wyoming did not request that we evaluate other control technologies,
we are not evaluating additional control technologies. See 40 CFR
part 51, appendix Y, IV.D.1.9.
    \85\ See Table 4 in this document.
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    Based on the State's estimates, the costs of the existing control
requirements (LNB/SOFA + SCR) are eminently reasonable. Indeed, in
2011, the State deemed reasonable an average cost-effectiveness of
$2,258 per ton of NOX removed (LNB/SOFA + SCR) and
incremental cost-effectiveness of $5,721 per ton of NOX
removed (LNB/SOFA + SCR) for each unit when it required SCRs as
reasonable progress controls.\86\ Similarly, EPA concluded in our 2014
final rule that our revised average cost-effectiveness figures for LNB/
SOFA + SCR for Units 1 and 2 of $2,635 and $3,403 per ton and our
revised incremental cost-effectiveness figures for LNB/SOFA + SCR for
Units 1 and 2 of $7,447 and $8,968 were reasonable.\87\
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    \86\ 77 FR 33053.
    \87\ 79 FR 5048.
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    Relatedly, in our 2014 final rule, we required through a Federal
implementation plan an emission limit consistent with the installation
of new LNB/OFA + SCR at four other units in Wyoming with higher cost-
effectiveness figures: LNB/OFA + SCR at Laramie River Station Units 1,
2, and 3 had an average cost-effectiveness of $4,461, $4,424, and
$4,375 per ton and incremental cost-effectiveness of $5,449, $5,871,
and $5,667 per ton, respectively,\88\ and LNB/OFA + SCR at Wyodak had
an average cost-effectiveness of $4,036 per ton and incremental cost-
effectiveness of $6,233 per ton.\89\
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    \88\ 79 FR 5039-40. The NOX emission limit for Units
1, 2, and 3 were revised (through settlement) on May 20, 2019, to
0.06 lb/MMBtu by July 1, 2019, 0.15 lb/MMBtu by December 31, 2018,
and 0.15 lb/MMBtu by December 31, 2018, respectively. 84 FR 22711
(May 20, 2019).
    \89\ 79 FR 5044. The NOX emission limit at Wyodak is
subject to ongoing litigation and settlement discussions.
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    Thus, the revised average cost-effectiveness and incremental cost-
effectiveness for installing SCR on Jim Bridger Units 1 and 2 in
Wyoming's 2020 SIP revision are even lower than what Wyoming determined
were reasonable for the same units in 2011. And the revised cost-
effectiveness figures are even lower than what EPA in 2014 determined
were reasonable for Jim Bridger Units 1 and 2 and for four other units
addressed in the 2014 final rule.\90\
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    \90\ The examples cited by Wyoming in the 2020 SIP revision do
not establish that the revised cost-effectiveness figures for Jim
Bridger Units 1 and 2 are unreasonable. Indeed, the average cost-
effectiveness figures in the examples are higher than or similar to
Wyoming's revised cost estimates. See 80 FR 18944, 18975 (April 8,
2015) (proposed rule stating that LNB/SOFA + SCR average ($3,552 and
$2,749 per ton) and incremental ($6,717 and $5,736 per ton) cost-
effectiveness figures were ``within the range of what we consider to
be cost-effective'' for BART but incremental visibility improvement
of 0.069 deciviews at a single Class I area is ``relatively small''
in light of incremental cost-effectiveness figures); 77 FR 21896,
21901 (April 12, 2012) (proposed rule stating that LNB/OFA + SCR
average cost-effectiveness figures of $2,110, $1,967, and $2,183 and
incremental cost-effectiveness figures of $4,534, $4,330, and $2,756
were not cost prohibitive or sufficiently large to warrant
eliminating SCR from consideration as BART).
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    In 2014, EPA ultimately deferred to Wyoming's BART and reasonable
progress determinations for Jim Bridger, even though the available
information suggested that SCR was reasonable as BART, given the
State's commitment to require SCR as reasonable progress controls. But
here, the State submitted a SIP revision that does not warrant such
deference. Specifically, the cost associated with installing and
operating the currently required controls on Jim Bridger Units 1 and 2
has not increased beyond what the State determined in 2011 was
reasonable. Wyoming has asserted only that not requiring emission
limits reflecting SCR for Units 1 and 2 will be less costly than
requiring them and the amount that PacifiCorp has spent to date on
NOX control technology at Jim Bridger is sufficient for
reasonable progress. Neither of these justifications offers a
compelling basis for removing the existing control requirements, as
both were expected and acknowledged at the time of Wyoming's 2011
decision to require the controls. Additionally, we note again that the
expected fleetwide installations of SCRs that PacifiCorp had previously
anticipated have not come to pass.\91\ Regardless, in 2011, Wyoming
determined the costs the source would incur were reasonable and that
emission limits reflecting LNB/SOFA + SCR are necessary to meet the
statutory requirements. The State has offered no reasonable explanation
for its reversal, i.e., for why the revised, even lower cost-
effectiveness estimates for SCR are now unreasonable such that an
emission limit associated with SCR is no longer necessary to meet the
requirement to make reasonable progress.
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    \91\ See supra note 37.
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    In summary, we disagree with Wyoming that the cost analysis
strongly favors removing the existing SCR-based requirement \92\ for
the following reasons: (1) The average cost-effectiveness and
incremental cost-effectiveness for installing SCR on Units 1 and 2 in
Wyoming's 2020 SIP revision are even lower than what Wyoming determined
were reasonable in 2011 and lower than what we found to be reasonable
for the installation of LNB/SOFA + SCR in similar instances in 2014;
(2) the State has offered no reasonable explanation for why the
revised, lower cost-effectiveness estimates for SCR are now
unreasonable; and (3) Wyoming has not provided any new information that
would support a revised determination that the costs of the existing
control requirements are now unreasonable.
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    \92\ Wyoming 2020 SIP Revision at 5.
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b. Visibility Improvement
    For Jim Bridger, the projected visibility improvements associated
with the installation of LNB/SOFA and SCR are between 0.27-0.37 and
0.27-0.36 deciviews for Units 1 and 2, respectively, at the most
impacted Class I area, Bridger Wilderness (Table 6). Additionally, the
installation of SCR at Units 1 and 2 would result in visibility
improvement at numerous other Class I areas.\93\
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    \93\ For Jim Bridger Unit 1, using monthly varying ammonia
concentrations, model visibility improvements with LNB/OFA + SCR
were 0.37 deciviews at Bridger; 0.26 deciviews at Fitzpatrick; 0.29
deciviews at Mt Zirkel; 0.35 deciviews at Rawah; 0.36 deciviews at
Rocky Mountain; 0.17 deciviews at Grand Teton; 0.14 deciviews at
Teton; 0.19 deciviews at Washakie; and 0.15 deciviews at
Yellowstone. For Jim Bridger Unit 1, using a constant 0.5 ppb
ammonia concentration, model visibility improvements with LNB/OFA/
SCR were: 0.37 deciviews at Bridger; 0.26 deciviews at Fitzpatrick;
0.29 deciviews at Mt Zirkel; 0.35 deciviews at Rawah; 0.36 deciviews
at Rocky Mountain; 0.17 deciviews at Grand Teton; 0.14 deciviews at
Teton; 0.19 deciviews at Washakie; and 0.15 deciviews at
Yellowstone. For Jim Bridger Unit 2, using monthly varying ammonia
concentrations, model visibility improvements with LNB/OFA/SCR were:
0.36 deciviews at Bridger; 0.26 deciviews at Fitzpatrick; 0.28
deciviews at Mt Zirkel; 0.35 deciviews at Rawah; 0.36 deciviews at
Rocky Mountain; 0.16 deciviews at Grand Teton; 0.14 deciviews at
Teton; 0.19 deciviews at Washakie; and 0.14 deciviews at
Yellowstone. For Jim Bridger Unit 2, using a constant 0.5 ppb
ammonia concentration, model visibility improvements with LNB/OFA/
SCR were: 0.36 deciviews at Bridger; 0.26 deciviews at Fitzpatrick;
0.28 deciviews at Mt Zirkel; 0.35 deciviews at Rawah; 0.36 deciviews
at Rocky Mountain; 0.16 deciviews at Grand Teton; 0.14 deciviews at
Teton; 0.19 deciviews at Washakie; and 0.14 deciviews at
Yellowstone. 79 FR 5041.

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    As an initial matter, Wyoming mischaracterizes our 2014 final rule
in its 2020 SIP revision when it asserts that EPA ``determined that the
unit-specific visibility benefits for LNB/SOFA + SCR installation on
Units 1 and 2 were `modest' (0.27 to 0.37 deciviews).'' \94\ In the
2014 final rule, EPA stated that the visibility improvement associated
with the installation of SCR is ``significant on a source-wide basis
(1.25 to 1.5 deciviews),'' while ``[t]he unit-specific benefits for
Units 1 and 2 are somewhat more modest (0.27-0.37 deciviews).'' \95\
That is to say, the unit-specific benefits were relatively less than
the benefits for the entire source, which will always be the case.
Thus, we did not characterize the visibility improvement associated
with the installation of SCR at Jim Bridger Units 1 and 2 as merely
``modest,'' and we do not agree with Wyoming's characterization of the
associated visibility improvement as such now. The fact remains that
the installation of SCR at Jim Bridger Units 1 and 2 would yield
appreciable visibility improvement at a reasonable cost.
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    \94\ Wyoming 2020 SIP Revision at 7.
    \95\ 79 FR 5048 (emphasis added).
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    States choosing to consider visibility benefits as an optional
additional factor should not use visibility to summarily dismiss cost-
effective potential controls. This is because the CAA does not
explicitly list visibility as a factor that must be considered in
reasonable progress determinations.\96\ In this case, Wyoming is
rejecting additional controls at Units 1 and 2, regardless of whether
they are cost-effective, because ``installation of SCR on Units 1 & 2
would result in only modest incremental visibility benefits of .10 to
.15 deciviews (per unit) when compared to LNB/SOFA on Units 1 and 2.''
This is a generally inappropriate basis on which to make reasonable
progress determinations for sources. Furthermore, because Units 1 and 2
already have been controlled under BART, additional controls would be
expected to make relatively smaller contributions to visibility
improvement as a proportion of total impairment. This does not mean,
however, that such sources need not be controlled in order to achieve
the national visibility goal.\97\ To the contrary, the evaluation and
control of BART sources such as Jim Bridger Units 1 and 2 under the
reasonable progress requirements will be necessary to achieve the
national goal of the prevention of any future, and the remedying of any
existing manmade impairment of visibility in Class I areas.\98\
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    \96\ Compare 42 U.S.C. 7491(g)(2) (including visibility as a
factor in BART determinations) with id. 7491(g)(1) (visibility not
included as an explicit factor in reasonable progress
determinations); see also EPA, ``Clarifications Regarding Regional
Haze State Implementation Plans for the Second Implementation
Period,'' July 8, 2021 (``July 2021 Clarifications Memo'') at 12-13,
available at https://www.epa.gov/system/files/documents/2021-07/clarifications-regarding-regional-haze-state-implementation-plans-for-the-second-implementation-period.pdf; 82 FR 3078, 3093 (January
10, 2017) (because regional haze is caused by emissions from
numerous sources, in order to address it, states may not abandon
controls they already have determined are reasonable based on the
four statutory factors on the basis that impact on visibility
conditions is subjectively assessed as not ``meaningful'').
    \97\ See id.; see also 40 CFR 51.308(e)(5) (after a state has
met BART requirements, BART-eligible sources are subject to
reasonable progress requirements in the same manner as other
sources).
    \98\ As with Wyoming's cost-effectiveness examples, Wyoming's
visibility examples do not support Wyoming's conclusions regarding
visibility improvement. Each is an example of a proposed BART
determination that does not address the fact that, in many
instances, reasonable progress controls naturally yield relatively
smaller visibility improvement over already-installed BART controls.
Thus, the fact that we proposed to reject controls of a certain
cost-effectiveness and visibility improvement for BART does not
necessitate rejecting similar controls for reasonable progress. See
77 FR 24794, 24818 (April 25, 2012) (proposed rule stating that SCR
is cost-effective for BART at $5,358 per ton but visibility
improvement at the most impacted Class I area of 0.254 deciviews and
cumulative visibility improvement at seven Class I areas of 0.273
deciviews are small and thus EPA proposed to approve determination
that BART is not SCR); 77 FR 11879, 11891 (February 28, 2012)
(proposed rule stating that EPA proposed to agree with state
determination that certain controls for a refinery were not BART due
to high costs (unavailable) and small visibility gains (0.045 to
0.16 deciview range)); 77 FR 18052, 18066 (March 26, 2012) (proposed
rule stating that EPA proposed to agree with the state's
determination that SCR was not BART given high cost-effectiveness
($9,900 and $15,290 per ton) and low visibility improvement (under
0.2 deciviews)); 77 FR 23988, 24013 (April 20, 2012) (proposed rule
stating that SO2 BART controls were cost-effective when
values ranged from $1400 to $4800 per ton but visibility improvement
ranges of 0.033 and 0.18 were ``relatively small'').
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    Finally, in Wyoming's 2020 SIP revision, the visibility improvement
remains unchanged from our 2014 final rule, and the State has provided
no new visibility information to support a revised NOX
reasonable progress determination that the existing control
requirements are now unreasonable. In summary, we disagree with
Wyoming's assertion that the visibility benefits are not sufficiently
meaningful to warrant cost-effective controls.
c. Other Factors
    Relevant to energy and non-air quality environmental impacts, the
State noted that SCR will produce solid waste when the catalyst is
replaced periodically, and that requiring SCR will require
significantly more electricity than LNB/SOFA. EPA's 2007 Guidance
provides that to the extent energy and non-air quality environmental
impacts of compliance are quantifiable, they should be included in the
engineering analysis supporting the cost of compliance estimates.\99\
PacifiCorp did so in the revised cost analysis for the 2020 SIP
revision. As explained elsewhere in this document, even with the energy
and non-air environmental costs incorporated into the cost analysis,
the cost-effectiveness of SCR remains reasonable.
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    \99\ 2007 Guidance at 5-2 and 5-3.
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    Additionally, the 2007 Guidance points to EPA's BART Guidelines,
which provide, among other things, that (1) the fact that a control
technology uses energy in and of itself does not disqualify that
technology, and (2) the fact that a control technology creates waste
that must be disposed of does not necessarily argue against selection
of that technology, especially if the control has been applied to
similar facilities elsewhere and the waste is similar to those other
applications.\100\ Wyoming has merely pointed out that the existing
controls on Units 1 and 2 (LNB/SOFA) require less electricity to
operate than SNCR or SCR and that SCR requires periodic catalyst
replacement. The State has not demonstrated that the anticipated energy
expenditure or waste that would be generated at Units 1 and 2 would be
any different from the numerous other units for which states or EPA
have required SCR. Indeed, Wyoming has already determined that energy
and non-air environmental impacts did not disqualify SCR from being a
reasonable control technology for two units at the same facility, i.e.,
at Jim Bridger Units 3 and 4.\101\ Based on EPA's long-standing
guidance and the fact that the State has not provided any evidence to
support a conclusion that the energy and non-air environmental impacts
of SCR at Units 1 and 2 are unreasonable, we disagree that these
factors support a conclusion that SCR is not the reasonable choice of
control.
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    \100\ 2007 Guidance at 5-2 and 5-3; 40 CFR part 51, appendix Y,
IV.D.4.h-i.
    \101\ Additionally, in its 2011 SIP submission Wyoming did not
identify any energy or non-air quality environmental impacts that
would preclude selection of any of the controls evaluated for Jim
Bridger, including LNB/SOFA + SCR. See 78 FR 34753.

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    With respect to remaining useful life, as stated above, Wyoming did
not provide an enforceable shutdown date that would ensure that the
expected life of Jim Bridger Units 1 and 2 would be less than the
expected life of the control technology. Thus, Wyoming appropriately
used the Control Cost Manual remaining useful life for SCR of 30 years
in the cost analysis.
    With respect to time necessary for compliance, Wyoming noted that
the LNB/SOFA are already in use and thus, in contrast to SCR and SNCR,
do not need any additional time for compliance. The deadline for Jim
Bridger Units 1 and 2 to comply with the existing control requirements
reflecting installation and operation of SCR by December 31, 2022 and
December 31, 2021, respectively has existed in the SIP since 2014. We
thus do not believe it is reasonable for the State to consider the time
necessary for compliance as weighing in favor of not requiring SCRs as
reasonable progress controls.
d. Summary of EPA's Evaluation of Wyoming's Reasonable Progress
Demonstration
    In summary, we propose to disapprove Wyoming's reasonable progress
demonstration concluding that the NOX emission limits
associated with LNB/SOFA controls are the reasonable choice for Jim
Bridger Units 1 and 2. We base our proposed disapproval on the
following: (1) The reasonable average cost-effectiveness and
incremental cost-effectiveness of the existing control requirements for
Jim Bridger Units 1 and 2; (2) the appreciable visibility improvement
estimated to result from compliance with the existing reasonable
progress control requirements; (3) the fact that the State previously
determined that the costs of those control requirements were reasonable
given the visibility benefits, and thus necessary to satisfy the
statutory requirements, and has not provided any new information that
would support a revised determination that the existing control
requirements are now unreasonable. Ultimately, we propose to find that
because the State failed to justify its conclusion that the existing
SCR requirements should be removed such that no further controls beyond
BART are required for Jim Bridger Units 1 and 2, we cannot reasonably
approve Wyoming's 2020 SIP revision. Because removing the existing SCR
requirements would be inconsistent with the statutory requirement that
SIPs contain the measures necessary to make reasonable progress, we are
proposing to disapprove Wyoming's 2020 SIP revision.

C. Plant-Wide Monthly and Annual NOX and SO2 Emission Limits for Jim
Bridger Units 1-4

    Wyoming's SIP revision includes ``an alternative regional haze
compliance strategy for the Jim Bridger Power Plant'' \102\ that
Wyoming considered as supplemental information to its revised four-
factor reasonable progress analysis and determination. Wyoming asserts
that the alternative regional haze compliance strategy's plant-wide
monthly and annual NOX and SO2 emission limits
are designed to reduce regional haze and create numerous other
environmental benefits toward achieving natural visibility conditions
at its Class I areas.\103\
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    \102\ Letter from Todd Parfitt, Director, Wyoming Department of
Environmental Quality, to Gregory Sopkin, Regional Administrator,
USEPA Region 8, Subject: State Implementation Plan Approval
Request--Regional Haze 309(g) SIP Revision for PacifiCorp Jim
Bridger Power Plant (May 12, 2020). See also Wyoming 2020 SIP
Revision at 3.
    \103\ Wyoming 2020 SIP Revision at 9.
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    The 2020 SIP revision provides that the State ``considered it
appropriate to re-balance and reconsider its [reasonable progress/long-
term strategy] determination and complete a four factor reasonable
progress analysis on a NOX-only basis.'' \104\ Our proposed
disapproval of Wyoming's reasonable progress determination for Jim
Bridger Units 1 and 2 is thus based solely on the source-specific
NOX reasonable progress analysis, as this analysis and
resulting determination were intended to replace the State's previous
NOX-only determination. However, we are also proposing to
find that we cannot approve, and are therefore proposing to disapprove,
the plant-wide emission limits, which rely on a comparative analysis
that includes both NOX and SO2 emissions
reductions.
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    \104\ Id. at 3.
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    EPA is proposing to disapprove the plant-wide monthly
NOX and SO2 emission limits because we cannot
render a SIP more stringent than intended by the state through a
partial SIP approval.\105\ While Wyoming has discretion to consider
these limits,\106\ it is our understanding that Wyoming intended to
adopt and make enforceable the plant-wide monthly and annual
NOX and SO2 emission limits, as proposed by
PacifiCorp, in lieu of the required emission limits associated with the
installation of SCR on Units 1 and 2 and not in addition to the
required emission limits associated with the installation of SCR.\107\
That is, we understand that Wyoming did not intend to implement the
plant-wide monthly and annual NOX and SO2
emission limits together with SCR on Jim Bridger Units 1 and 2.
Implementing a NOX emission limit consistent with the
installation of SCR together with plant-wide monthly and annual
NOX and SO2 emission limits would effectively
increase the stringency of the SIP beyond what was intended in the
Wyoming 2020 SIP revision.\108\ Thus, because EPA cannot render
Wyoming's SIP more stringent than intended by the State through a
partial SIP approval, and because we are proposing to disapprove
Wyoming's revised NOX reasonable progress determination as
unreasonable, we are also proposing to extend our disapproval to the
State's plant-wide monthly and annual NOX and SO2
emission limits. Wyoming may choose to submit the plant-wide monthly
and annual NOX and SO2 emission limits to EPA in
a stand-alone SIP submittal if the State would like to incorporate
these emission limits into its SIP independent of the revised
NOX reasonable progress analysis and determination for Jim
Bridger Units 1 and 2 contained in the 2020 SIP revision. For example,
some form of plant-wide mass limits could serve as a SIP strengthening
measure.
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    \105\ Bethlehem Steel Corp. v. Gorsuch, 742 F.2d 1028, 1036 (7th
Cir. 1984).
    \106\ As stated above, Wyoming has discretion to evaluate
factors (beyond the four factors) that it considers relevant in
formulating its long-term strategy, 2007 Guidance at page 5-1, so
long as it does so reasonably and in a manner consistent with the
statute and other applicable requirements. 42 U.S.C. 7491(b)(2)(B);
40 CFR 51.308(d)(1)(iii).
    \107\ Wyoming 2020 SIP Revision at 9, 10, and 12.
    \108\ Implementation of NOX limits consistent with
installing SCRs on Units 1 and 2, combined with the plant-wide
monthly SO2 limits would likely result in some
SO2 reductions (from the monthly plant-wide limits) plus
additional NOX reductions (from meeting the 0.07 lb/MMBtu
limits on Units 1 and 2) that are beyond what was intended in the
SIP revision.
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    In addition to the legal basis for proposing to disapprove the
plant-wide monthly and annual NOX and SO2
emission limits, we also note two additional considerations. These
considerations relate to Wyoming and PacifiCorp's quantitative analyses
in support of the plant-wide limits, which assume that Jim Bridger is
still operating at historical (2001-2003) levels. Although we are not
relying on these considerations as the basis of our proposed
disapproval, we provide them here for completeness.
    First, Wyoming analyzed the plant-wide limits assuming Jim
Bridger's emissions are consistent with the plant's ``current operating
potential.'' \109\ As explained above, PacifiCorp's analysis defines
``current operating potential'' as

a combination of recent emission rates with plant-wide heat input
(i.e., utilization) from the 2001-2003 period. Thus, the majority of
the emissions reductions that Wyoming credited to the plant-wide limits
\110\ would be realized only if Jim Bridger was utilized at levels
consistent with the 2001-2003 period. However, recent utilization of
the plant, based on the 2017-2020 period, has been much lower.\111\ EPA
examined emissions and operations data from the 2017 to 2020 period
because it reflects (1) full operation of the SCRs on Units 3 and 4
that were installed in 2015 and 2016, respectively, (2) earlier
SO2 scrubber upgrades on all four units, and (3) recent
trends in plant operations, as hours of operation and heat input. To
the extent Wyoming's demonstration relies on historical (2001-2003)
utilization to show that the plant-wide monthly and annual
NOX and SO2 emission limits achieve greater
emissions reductions (and therefore greater visibility improvement)
than SCRs on Units 1 and 2,\112\ neither the CAA nor the Regional Haze
Rule provide a basis for such reliance.\113\
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    \109\ Wyoming 2020 SIP Revision at 9.
    \110\ See Wyoming 2020 SIP Revision at 9 (plant-wide emission
limits would result in combined NOX and SO2
reduction of 6,056 tons/year).
    \111\ Compare PacifiCorp Reassessment, Attachment 1 at 21
(providing 2001-2003 average heat input used as baseline for cost-
effectiveness analysis) with EPA Calculations for Wyoming 2020 SIP
Revision (January 7, 2022) (Tab 1).
    \112\ See, e.g., Wyoming 2020 SIP Revision at 9 (PacifiCorp's
comparative analysis of the existing control requirements and plant-
wide emission limits indicates the limits ``produce better modeled
visibility and greater environmental benefits than installation of
SCR or SNCR'').
    \113\ Unlike the BART program, which includes an extensive
regulatory framework under which states can rely on such historical
emissions and utilization data to demonstrate that a BART
alternative achieves greater reasonable progress than BART, neither
the CAA nor the Regional Haze Rule contain a similar framework for
reasonable progress. Compare 40 CFR 51.308(e)(2) and (3) with
(d)(1)(i)(A) and (d)(3).
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    Second (and relatedly), based on recent (2017-2020) operation of
the plant, we believe it is reasonable to conclude that the plant-wide
monthly and annual NOX and SO2 emission limits
would not actually achieve similar or greater emissions reductions and
visibility improvement compared to the installation of SCR on Units 1
and 2 as Wyoming contends.
    Wyoming claims that the plant-wide limits will produce greater
visibility improvement compared to the installation of two additional
SCRs on Units 1 and 2. However, the CALPUFF visibility modeling inputs,
and therefore visibility modeling results, are premised on assumptions
about Jim Bridger's baseline utilization and emissions. Again, Wyoming
analyzed the plant-wide emission limits assuming Jim Bridger's
emissions were consistent with its plant-wide heat input from the 2001-
2003 period. That is, the modeling analysis assumes heat input from a
historical period that does not correspond to how the facility is
currently operated.\114\ The plant-wide 2017-2020 average utilization
is approximately 29 percent below 2001-2003 average levels.\115\ Based
on the assumption of plant-wide heat input from the 2001-2003 period,
the analysis of the plant-wide limits by PacifiCorp and Wyoming
estimates a reduction of 5,049 tpy of SO2 and 1,007 tpy of
NOX. Had the quantitative analysis been based on Jim
Bridger's current utilization, it would have shown that the plant-wide
limits would actually achieve far fewer emissions reductions going
forward.\116\ For example, the proposed annual plant-wide
SO2 + NOX emission limit is 17,500 tpy. However,
in the 2017-2020 period, plant-wide annual SO2 +
NOX emissions have ranged from 14,823 to 16,004 tpy.\117\
Therefore, Jim Bridger is already operating well below the proposed
annual plant-wide SO2 + NOX emission limits.
Consequently, any annual SO2 and NOX reductions
based on the source's actual current operations would be much smaller
than estimated from the analysis of a potential historical operation
basis.
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    \114\ PacifiCorp Reassessment at 7. The PacifiCorp Reassessment
also references annual heat input values that were not disclosed to
EPA due to confidential forecasted capacity factors (see Attachment
3B to Attachment 1). Therefore, some assumptions are unknown and
impossible to replicate.
    \115\ Compare PacifiCorp Reassessment, Attachment 1 at 21
(providing 2001-2003 average heat input used as baseline for cost-
effectiveness analysis) with EPA Calculations for Wyoming 2020 SIP
Revision (January 7, 2022) (Tab 1).
    \116\ Wyoming and PacifiCorp used the 2001-2003 period as the
baseline for the revised cost estimates in the Wyoming 2020 SIP
Revision's NOX-only four-factor analysis for Jim Bridger
Units 1 and 2. EPA believes this is a reasonable approach given the
circumstances, particularly that the purpose was to compare the
costs of different controls against a common baseline and that the
cost and visibility figures relied on for that analysis were
originally calculated for BART purposes. In contrast, EPA
understands the purpose of the quantitative analysis accompanying
the plant-wide monthly and annual NOX and SO2
emission limits was to determine whether they will result in greater
prospective emissions reductions and visibility improvement than
SCR. See, e.g., Wyoming 2020 SIP Revision at 12 (``In addition,
PacifiCorp's visibility enhancing proposal to limit overall
operations at all four Jim Bridger Units adds support to Wyoming's
reasonable progress revision, and ensures that visibility
improvements greater than SCR installation will be achieved for the
State of Wyoming.''). In this context, using a historical
utilization baseline that does not reflect current or likely future
plant operation obfuscates the assessment of future potential
emissions reductions.
    \117\ EPA Calculations for Wyoming 2020 SIP Revision (January 7,
2022) (Tab 1). Data based on the information obtained from EPA's
Clean Air Markets Division (CAMD) database, available at: https://ampd.epa.gov/ampd/.
---------------------------------------------------------------------------

    Due to the complicated nature of the proposed monthly limits and a
lack of complete information,\118\ EPA could not complete a full
evaluation of the impact of the monthly limits on emissions and
emissions reductions. However, based on the information available to
EPA, it appears that while the proposed additional plant-wide monthly
SO2 and NOX limits may restrict SO2
emissions (and to a lesser extent NOX emissions) in some
months, the facility's recent operation has been emitting at levels
similar to the proposed monthly limits.\119\ Thus, the plant-wide
annual and monthly limits appear to result in few actual emissions
reductions based on Jim Bridger's recent operation.
---------------------------------------------------------------------------

    \118\ See supra note 114.
    \119\ EPA Calculations for Wyoming 2020 SIP Revision (January 7,
2022) (Tabs 3 and 4).
---------------------------------------------------------------------------

    In contrast, installation of two additional SCRs on Units 1 and 2
will provide significant and certain additional NOX
emissions reductions under any operating scenario compared to either
recent operation or potential historical operation. With the current
SIP emission limits of 0.07 lb/MMBtu (30-day rolling average) for Units
1 and 2, additional SCRs on those two units would reduce annual
NOX emissions by at least 3,000 tpy relative to the 2017-
2020 period (based on actual calendar month operation over that time
period).\120\ Because the more recent data reflect the facility as it
operates today (including emissions controls and limits that PacifiCorp
and Wyoming assumed in the analysis of plant-wide limits), we believe
it presents a reasonable set of operating conditions from which to
evaluate which scenario would achieve greater combined NOX
and SO2 emissions reductions in future years. Furthermore,
neither PacifiCorp nor Wyoming included any information that would
indicate increased operation in the future.
---------------------------------------------------------------------------

    \120\ Id. at Tab 2.
---------------------------------------------------------------------------

    In conclusion, unlike the plant-wide NOX and
SO2 emission limits, installation of two additional SCRs
provides significant NOX reductions of at least 3,000 tpy.
Based on the information we have before us, we believe it is reasonable
to conclude that the proposed plant-wide annual and monthly limits
would not provide similar or greater emissions reductions or visibility
improvement compared to the installation of two additional SCRs. This
is especially true in comparison to recent operation of the Jim Bridger
plant in the 2017 to 2020 period.

D. Clean Air Act Section 110(l)

    Under CAA section 110(l), the EPA cannot approve a plan revision
``if the revision would interfere with any applicable requirement
concerning attainment and reasonable further progress (as defined in
section 7501 of this title), or any other applicable requirement of
this chapter.'' \121\ Wyoming states that the 2020 SIP revision will
not interfere with reasonable further progress or other applicable
requirements because there are no areas in Wyoming that are currently
designated nonattainment for NOX or particulate matter, and
that with the reductions anticipated from the plant-wide annual and
monthly limits, the SIP revision will not interfere with attainment or
maintenance of the National Ambient Air Quality Standards (NAAQS).\122\
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    \121\ 43 U.S.C. 7410(l). Note that ``reasonable further
progress'' as used in CAA section 110(l) is a reference to that term
as defined in section 301(a) (i.e., 42 U.S.C. 7501(a)), and as such
means reductions required to attain the National Ambient Air Quality
Standards (NAAQS) set for criteria pollutants under section 109.
This term as used in section 110(l) (and defined in section 301(a))
is not synonymous with ``reasonable progress'' as that term is used
in the regional haze program. Instead, section 110(l) provides that
EPA cannot approve plan revisions that interfere with regional haze
requirements (including reasonable progress requirements) insofar as
they are ``other applicable requirement[s]'' of the CAA.
    \122\ Wyoming 2020 SIP Revision at 13. We note, however, that
NOX is not a criteria pollutant itself but instead
represents a group of highly reactive gases that includes the
criteria pollutant nitrogen dioxide (NO2).
---------------------------------------------------------------------------

    As an initial matter, we note that Wyoming's evaluation pursuant to
CAA section 110(l) is overly narrow and does not address all relevant
NAAQS-related considerations. Additionally, CAA section 110(l) applies
to all requirements of the CAA, not just the attainment and maintenance
of the NAAQS. The previous sections of this document explain how the
State failed to justify its conclusion that the existing SCR
requirements should be removed such that no further controls beyond
BART are necessary for Jim Bridger Units 1 and 2 for reasonable
progress in the first planning period. Based on our proposed
conclusions in section IV.B in this document, we propose to find that
removing the SCR requirement would interfere with the regional haze
requirements of the CAA, specifically, with the requirement that SIPs
contain the emission limits, schedules of compliance, and other
measures that are necessary to make reasonable progress toward the
national visibility goal. Accordingly, we propose to disapprove the
Wyoming 2020 SIP revision under CAA section 110(l) in addition to the
basis stated in section IV.B above.

E. Consultation With Federal Land Managers

    Under 40 CFR 51.308(i)(2), Wyoming was obligated to provide the
FLMs with an opportunity for consultation in development of the State's
proposed SIP revision no less than sixty days prior to the associated
public hearing or public comment opportunity. On March 29, 2019, the
State of Wyoming informed the FLMs of the State's draft proposed
regional haze SIP revision for the Jim Bridger power plant. In doing
so, the State provided the FLMs with a copy of the draft regional haze
SIP revision and provided the FLMs with sixty days to provide comments
as well as the opportunity to discuss the draft SIP during a phone call
on May 21, 2019.\123\ The State did not receive any comments from the
FLMs. Therefore, we propose to find that Wyoming met its obligations
for consultation in development of the Wyoming 2020 SIP revision.
---------------------------------------------------------------------------

    \123\ Amber Potts, Wyoming Department of Environmental Quality,
Record of State of Wyoming, PacifiCorp, and Federal Land Manager
Consultation Meeting for the Proposed Updates to the Regional Haze
(Round 1) SIP Concerning the Jim Bridger Facility, May 21, 2019. See
also Wyoming Department of Environmental Quality, FLM Consultation
Meeting Slides.
---------------------------------------------------------------------------

V. Summary of EPA's Proposed Action

    In this action, EPA is proposing to disapprove the Wyoming 2020 SIP
revision (as submitted in May 2020 and supplemented in September and
October 2020), which includes amendments to Chapters 7.3.6 and 8 of
Wyoming's regional haze SIP narrative, Addressing Regional Haze
Visibility Protection For The Mandatory Federal Class I Areas Required
Under 40 CFR 51.309, that contain a source-specific NOX
reasonable progress analysis and revised determination for Jim Bridger
Units 1 and 2. EPA is also proposing to disapprove the plant-wide
monthly and annual NOX and SO2 emission limits
for Jim Bridger Units 1-4. Because we are proposing to disapprove the
State's proposed revisions to its existing SIP requirements, we are not
proposing to change any regulatory text, including text in 40 CFR
52.2620 or 40 CFR 52.2636.

VI. Statutory and Executive Order Reviews

    Under the CAA, 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 requirements of the CAA. As explained
above, Wyoming's SIP submission does not meet the requirements of the
CAA. Accordingly, this action merely proposes to disapprove state law
as not meeting Federal requirements and does not impose additional
requirements beyond those imposed by state law. For that reason, this
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 (Pub. L. 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
     Does not provide EPA with the discretionary authority to
address, as appropriate, disproportionate human health or environmental
effects, using practicable and legally permissible methods, under
Executive Order 12898 (59 FR 7629, February 16, 1994).
    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 in 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.

    Authority: 42 U.S.C. 7401 et seq.

    Dated: January 11, 2022.
KC Becker,
Regional Administrator, Region 8.
[FR Doc. 2022-00777 Filed 1-14-22; 8:45 am]
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