[Federal Register Volume 85, Number 229 (Friday, November 27, 2020)]
[Rules and Regulations]
[Pages 75860-75874]
[FR Doc No: 2020-23994]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R08-OAR-2015-0463; FRL-10015-75-Region 8]

Approval and Promulgation of Air Quality Implementation Plans;
Utah; Regional Haze State and Federal Implementation Plans

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: The Environmental Protection Agency (EPA) is finalizing
approval of State Implementation Plan (SIP) revisions submitted by the
State of Utah on July 3, 2019, as supplemented on December 3, 2019, to
satisfy certain regional haze requirements for the regional haze
program's first implementation period (Utah SIP revisions). The EPA is
approving the Utah SIP revision that provides an alternative to best
available retrofit technology (BART) controls for nitrogen oxides
(NOX) at the PacifiCorp Hunter and Huntington power plants.
The EPA finds that the NOX BART Alternative for Hunter and
Huntington achieves greater reasonable progress toward natural
visibility conditions than BART, in accordance with the requirements of
the Clean Air Act (CAA) and the EPA's Regional Haze Rule. In
conjunction with this approval, we are withdrawing the Federal
Implementation Plan (FIP) that addresses NOX BART for the
Hunter and Huntington power plants that EPA promulgated in 2016. The
EPA is also approving Utah's December 3, 2019 SIP supplement that
requires reporting of all deviations from compliance with the
applicable requirements under particulate matter (PM) BART and the
NOX BART Alternative, including the emission limits for
Hunter and Huntington. The EPA is taking these actions pursuant to
sections 110 and 169A of the CAA.

DATES: This rule is effective on December 28, 2020.

ADDRESSES: The EPA has established a docket for this action under
Docket ID No. EPA-R08-OAR-2015-0463. All documents in the docket are
listed on the https://www.regulations.gov website. 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, is not placed on the
website and will be publicly available only in hard copy form. Publicly
available docket materials are available through https://www.regulations.gov, or please call or email the person identified in
the FOR FURTHER INFORMATION CONTACT section for additional availability
information.

FOR FURTHER INFORMATION CONTACT: Aaron Worstell, Air and Radiation
Division, EPA, Region 8, Mailcode 8ARD-IO, 1595 Wynkoop Street, Denver,
Colorado 80202-1129,<PHONE_NUMBER><EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION:
    Throughout this document wherever ``we,'' ``us,'' or ``our'' is
used, we mean the EPA.

Table of Contents

I. Proposed Action and the EPA's Conclusion
II. Public Comments and EPA Responses
    A. Legal Issues
    B. BART Alternative Requirements
    C. BART Alternative ``Greater Reasonable Progress''
Determination
III. The EPA's Final Action
    A. 2019 Utah Regional Haze SIP Revisions
    B. FIP Withdrawal
    C. Clean Air Act Section 110(l)
IV. Incorporation by Reference
V. Statutory and Executive Order Reviews
    A. Executive Order 12866: Regulatory Planning and Review and
Executive Order 13563: Improving Regulation and Regulatory Review
    B. Executive Order 13771: Reducing Regulations and Controlling
Regulatory Costs
    C. Paperwork Reduction Act
    D. Regulatory Flexibility Act
    E. Unfunded Mandates Reform Act (UMRA)
    F. Executive Order 13132: Federalism
    G. Executive Order 13175: Consultation and Coordination with
Indian Tribal Governments
    H. Executive Order 13045: Protection of Children from
Environmental Health Risks and Safety Risks
    I. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use
    J. National Technology Transfer and Advancement Act
    K. Executive Order 12898: Federal Actions To Address
Environmental Justice in Minority Populations and Low-Income
Populations
    L. Determination Under Section Clean Air Act Section 307(d)
    M. Congressional Review Act (CRA)
    N. Judicial Review

I. Proposed Action and the EPA's Conclusion

    On July 5, 2016, the EPA promulgated a final rule titled
``Approval, Disapproval, and Promulgation of Air Quality Implementation
Plans; Partial Approval and Partial Disapproval of Air Quality
Implementation Plans and Federal Implementation Plan; Utah; Revisions
to Regional Haze State Implementation Plan; Federal Implementation Plan
for Regional Haze,'' which approved, in part, a regional haze SIP
revision submitted by the State of Utah on June 4, 2015.\1\ In the July
2016 final rule, the EPA also disapproved, in part, the Utah regional
haze SIP submission, including the NOX BART Alternative
(also ``BART Alternative'' or ``Alternative'') for Hunter Units 1 and 2
and Huntington Units 1 and 2, which are BART units as explained in more
detail below. The BART Alternative relied on sulfur dioxide
(SO2), NOX, and PM emission reductions from the
2015 closure of PacifiCorp's Carbon power plant, as well as
NOX reductions achieved through combustion control upgrades
at Hunter Units 1, 2 and 3 and Huntington Units 1 and 2, which were
installed in 2006-2014 (Hunter Unit 3 is not a BART unit). The
combustion control upgrades for Hunter Units 1 and 2 and Huntington
Units 1 and 2 include an Alstom TSF 2000TM low-
NOX firing system and two elevations of separated overfire
air (SOFA). The combustion upgrades for Hunter Unit 3 include upgraded
low-NOX burners (LNB) and overfire air (OFA). Concurrent
with disapproving the NOX BART Alternative, EPA promulgated
a FIP in the July 2016 final rule that imposed a NOX BART
emission limit of 0.07 lb/MMBtu (30-day rolling average) for each of
the four BART units based on the emission reductions achievable through
the installation and operation of selective-catalytic reduction (SCR)
plus upgraded combustion controls.
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    \1\ 81 FR 43894 (July 5, 2016).
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    On July 3, 2019, Utah submitted a revised SIP that, based on new
technical information and a different regulatory test, seeks to
demonstrate that the previously submitted NOX BART
Alternative achieves greater reasonable progress than BART. The SIP
revision also includes amendments to Utah's SO2 milestone
reporting requirements under the SO2 Backstop Trading
Program pursuant to 40 CFR 51.309 such that SO2 emission
reductions resulting from the closure of the Carbon plant are not
counted under both the SO2 Backstop Trading Program and the
NOX BART Alternative. On January 22, 2020, the EPA proposed
to approve the State's July 3, 2019 SIP revision based on this new
information.\2\ Specifically, we

proposed to incorporate the following into Utah's SIP:
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    \2\ 85 FR 3558 (Jan. 22, 2020).
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     A NOX emission limit of 0.26 lb/MMBtu (30-day
rolling average) each for Hunter Units 1 and 2 and Huntington Units 1
and 2.
     A NOX emission limit of 0.34 lb/MMBtu (30-day
rolling average) for Hunter Unit 3.
     A requirement to permanently close and cease operation of
the Carbon power plant by August 15, 2015.
     The associated amendments to the SO2 milestone
reporting requirements.
    Because approval of the NOX BART Alternative satisfies
Utah's BART obligation for Hunter Units 1 and 2 and Huntington Units 1
and 2, we also proposed to withdraw the FIP for NOX BART at
these units. In particular, we proposed to find that the NOX
BART Alternative would achieve greater reasonable progress towards
natural visibility conditions than would be achieved through the
installation and operation of BART at Hunter Units 1 and 2 and
Huntington Units 1 and 2 under EPA's 2016 FIP.
    The EPA also proposed to approve a December 3, 2019 SIP supplement
to the July 3, 2019 SIP revision that includes monitoring,
recordkeeping, and reporting (MRR) requirements for the units subject
to the NOX BART Alternative and PM BART. The supplement also
includes amendments that require each source to submit a report of any
deviation from applicable emission limits and operating practices,
including deviations attributable to upset conditions, the probable
cause of such deviations, and any corrective actions or preventive
measures taken.
    Finally, contingent on our approval of these two SIP revisions, we
proposed to find that Utah's SIP fully satisfies the requirements of
section 309 of the Regional Haze Rule and that, therefore, the State
has fully complied with the requirements for reasonable progress,
including BART, for the first implementation period.
    EPA requested comment on its proposed approval of Utah's regional
haze SIP elements related to the NOX BART Alternative under
40 CFR 51.309(d)(4)(vii) and 51.308(e)(2) and (3), as well as the MRR
elements for the units subject to that BART Alternative and to PM BART.
EPA previously approved Utah's regional haze SIP as meeting all other
requirements of 40 CFR 51.309,\3\ and we neither reopened nor requested
comment on previously approved elements.
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    \3\ See 77 FR 74355 (Dec. 14, 2012); 81 FR 43894 (July 5, 2016).
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    The EPA conducted a public hearing for our proposed action in
Price, Utah on February 12, 2020. Our public comment period closed on
March 23, 2020.
    Our January 2020 proposed rule provided background on the
requirements of the CAA and EPA's Regional Haze Rule, a summary of Utah
regional haze SIP submittals and related EPA actions, and the EPA's
rationale for its proposed action. That background information and
rationale will not be restated here. For the reasons stated in the
proposed rule, this document, and in the accompanying Response to
Comments (RTC) document, the EPA concludes that Utah's NOX
BART Alternative achieves greater reasonable progress under 40 CFR
51.308(e)(2) and (3).

II. Public Comments and EPA Responses

    We received both written and oral comments at the public hearings
we held in Price, Utah. We also received comments through the internet
and mail. The full text of comments received from these commenters is
included in the publicly posted docket associated with this action at
https://www.regulations.gov. Our RTC document, which is also included
in the docket associated with this action, provides detailed responses
to all significant comments received except for those addressed
below.\4\ Our RTC document is organized similarly to the structure
presented in this section. Therefore, if additional information is
desired concerning how we addressed a particular comment, the reader
should refer to the appropriate section in our RTC document.
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    \4\ Most commenter citations and footnotes are excluded from
this document.
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    PacifiCorp, conservation organizations (HEAL Utah, Sierra Club,
National Parks Conservation Association, Utah Physicians for a Healthy
Environment, and Natural Resources Defense Council), Edison Electric
Institute, Ute Mountain Ute Tribe, and Salt Lake City's Capitol Hill
Action Group submitted detailed written comments. Many general comments
were made at the public hearing.

A. Legal Issues

    Comment summary: Some commenters argued that the modeling
assumptions used for comparing the BART Benchmark (the controls
required by the 2016 FIP) \5\ to the NOX BART Alternative
overstated emissions for non-BART units in the BART Benchmark scenario.
Specifically, the commenters argued that emissions for the Carbon plant
should have reflected compliance with the Mercury and Air Toxics
Standards (MATS) rule, which was required by April 15, 2015. According
to the commenters, compliance with MATS would have resulted in a
greater than 50 percent reduction in SO2 emissions at Carbon
Units 1 and 2 compared to its historical emissions. Additionally, the
commenters argued that emissions from Hunter Unit 3 in the BART
Benchmark scenario should have reflected combustion controls installed
in 2007. The modeling instead assumed that under this scenario, the
Carbon plant and Hunter Unit 3 would emit pollutants consistent with
the 2001-2003 baseline.\6\ The commenters argued that such assumption
overstates the emissions from these sources that would have occurred
under the BART Benchmark and thus understates the visibility benefits
that would occur under the BART Benchmark.
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    \5\ As described above, in the July 2016 FIP, EPA determined
that NOX BART for each of the four BART units constituted
an emission limit of 0.07 lb/MMBtu (30-day rolling average) based on
the emission reductions achievable through the installation and
operation of SCR plus upgraded combustion controls. Utah's July 2019
SIP submittal thus refers to the BART Benchmark controls as the
``EPA FIP,'' as do many of the commenters. While the controls
represented by the BART Benchmark and EPA's 2016 FIP are indeed the
same, the relevant comparison for this action is between the BART
Benchmark and the NOX BART Alternative. 40 CFR
51.308(e)(2); see also 85 FR 3572. We therefore refer to the 2016
FIP as the BART Benchmark as appropriate in this document, the
preamble to the proposed rule, and the RTC document.
    \6\ See 85 FR 3568.
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    Response: Utah's modeling of emissions at Carbon and Hunter Unit 3
under the NOX BART Alternative and the BART Benchmark is
reasonable and authorized under the EPA's regulations for BART
alternatives. In particular, assuming continued emissions from sources
that would not be subject to BART controls in the BART Benchmark
scenario, when such emissions would be eliminated under the BART
Alternative, is simply a necessary analytical step for making a proper
comparison of the two scenarios to determine which achieves ``greater
reasonable progress.'' \7\ This is authorized by the Regional Haze
Rule, and it is consistent with the EPA's prior regulatory actions, EPA
guidance, and case law.
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    \7\ 40 CFR 51.308(e).

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    First, Hunter Unit 3 and the Carbon Units are not BART sources.\8\
Accordingly, reductions from these sources should not be included in
determining emissions reductions from the BART Benchmark under 40 CFR
51.308(e)(2)(i)(C). Hunter Unit 3 and the Carbon Units are covered by
Utah's BART Alternative, however, and thus emissions reductions from
these sources properly are attributed to the BART Alternative under 40
CFR 51.308(e)(2)(i)(D). Were the EPA to include these same emission
reductions in the BART Benchmark scenario, even though there would have
been no enforceable obligation that they occur under that scenario, a
proper comparison of the relative degree of visibility improvement
between the two scenarios would not be possible.
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    \8\ See 85 FR 3559; 81 FR 43895; Utah Air Quality Board, ``Utah
State Implementation Plan Section XX,'' June 24, 2019, pages 28-29.
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    Furthermore, Utah properly applied a 2001-2003 baseline to
calculate emissions reductions under both scenarios. Pursuant to 40 CFR
51.308(e)(2)(iv), a state's SIP must demonstrate that emissions
reductions resulting from an alternative measure will be surplus to
those reductions resulting from measures adopted to meet requirements
of the CAA ``as of the baseline date of the SIP.'' In promulgating the
Regional Haze Rule in 1999, we explained that the ``baseline date of
the SIP'' in this context means ``the date of the emissions inventories
on which the SIP relies,'' \9\ which is defined as 2002 for regional
haze purposes.\10\ Any measure adopted after 2002 is accordingly
``surplus'' under 40 CFR 51.308(e)(2)(iv). Indeed, in 2002, the EPA
designated the baseline date of all regional haze SIPs as 2002.\11\ The
EPA explained that ``[p]rogress in improving visibility is tracked from
baseline conditions (established using air quality monitoring for the
2000-2004 period). If 2002 is used as the base year for planning
purposes, then States can take credit for emission reductions that are
achieved before the 2007-2008 SIP due date.'' \12\
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    \9\ 64 FR 35714, 35742 (July 1, 1999).
    \10\ 70 FR 39104, 39143 (July 6, 2005).
    \11\ See Memorandum dated November 18, 2002, from Lydia Wegman
and Peter Tsirigotis, Subject: ``2002 Base Year Emission Inventory
SIP Planning: 8-hr Ozone, PM2.5, and Regional Haze
Programs.''
    \12\ Id. at 3. The first regional haze SIPs were due December
17, 2007. See 40 CFR 51.308(b).
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    In other words, for purposes of calculating emissions reductions
from BART alternatives, states assume a baseline of 2002 emissions and
may take credit for emissions reductions after that date, even if those
reductions occur as a result of, or to comply with, other CAA
requirements, so long those requirements occur after that baseline.
Thus, Utah's modeling properly credited emissions reductions from
Carbon's 2015 shutdown and Hunter 3's 2007 controls towards the BART
Alternative. Furthermore, in order to properly compare the BART
Benchmark to the NOX BART Alternative under 51.308(e)(2) to
determine if the Alternative achieves greater reasonable progress,
common sense dictates that the EPA must compare emissions reductions
under each scenario from the same baseline year. Thus, Utah's modeling
also properly included Carbon and Hunter 3's emissions from the 2001-
2003 baseline period (i.e., not including any reductions from MATS
compliance or 2007 controls) under the BART Benchmark because Carbon
and Hunter 3 are not BART sources.
    This approach is supported by case law.\13\ In Yazzie v. EPA, the
United States Court of Appeals for the Ninth Circuit reviewed and
upheld EPA's FIP, which included a BART alternative instead of
BART.\14\ The petitioners argued that the EPA inconsistently credited
the BART alternative, but not the BART benchmark, for emissions
reductions from controls voluntarily installed in 2009-2011 for
purposes of comparing the two.\15\ Like here, the EPA used a 2001-2003
baseline from which to calculate emissions reductions under both
scenarios for purposes of the comparison.\16\ The Ninth Circuit deemed
this approach reasonable under 40 CFR 51.308(e)(3).\17\ Likewise,
Utah's approach here with respect to Hunter 3 and Carbon is reasonable.
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    \13\ See Utility Air Regulatory Group v. EPA, 885 F.3d. 714
(D.C. Cir. 2018); Yazzie v. EPA, 851 F.3d 960 (9th Cir. 2017).
    \14\ 851 F.3d at 975.
    \15\ 851 F.3d at 974.
    \16\ Id.
    \17\ See id.
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    Commenters additionally argue that the State cannot take credit for
the portion of the reductions from the Carbon shutdown that would have
happened anyway had Carbon remained in operation but in compliance with
the MATS rule. However, as the D.C. Circuit has recognized, EPA's
regulations allow for BART alternatives even when the reductions are
due to compliance with another CAA requirement. In UARG v. EPA, the
United States Court of Appeals for the District of Columbia Circuit
reviewed and upheld the EPA's rule finding that emission reductions
attributable to the 2011 Cross-State Air Pollution Rule (CSAPR)--
implemented under the ``good neighbor'' provision of the Act, CAA
section 110(a)(2)(D)(i)(I)--may be treated as a BART alternative. The
petitioners there argued that the EPA should not have compared BART on
its own (i.e., without CSAPR in place) to the BART alternative on its
own (i.e., CSAPR without BART in place), but should have instead
compared BART plus CSAPR to CSAPR, because CSAPR (like the MATS rule
here), was implemented under a separate provision of the CAA and would
go into effect regardless of BART.\18\ The D.C. Circuit rejected the
petitioners' argument as effectively requiring more of BART
alternatives than the EPA's rule requires. The court explained that
under the Regional Haze Rule, the EPA properly compares BART without
the alternative or other CAA requirements to the alternative without
BART.\19\ Underlying that holding is the fact that EPA's regulations
authorize BART alternatives to take advantage of emission reductions
achieved to meet some other CAA requirement so long as they are surplus
to requirements as of the baseline.\20\ Thus, as in UARG, the EPA here
properly compared the BART Benchmark without MATS compliance at Carbon
to the NOX BART Alternative.
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    \18\ UARG, 885 F.3d at 720.
    \19\ See id.
    \20\ See 40 CFR 51.308(e)(2)(i)(C), (e)(2)(iv). See also UARG,
885 F.3d at 719, 720 (finding challenge to EPA's BART alternative
regulations to be time-barred).
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    This approach is also consistent with other EPA actions. See, e.g.,
79 FR 39322, 39325 (July 10, 2014) (approving Connecticut's use of
emissions reductions from post-2002 regulations as surplus that could
be credited to its BART alternative); 77 FR 34218, 34219 (June 11,
2012) (approving Indiana's credit to its BART alternative for
reductions from a non-BART source); 78 FR 57487, 57489-91 (Sept. 19,
2013) (approving Massachusetts' comparison of the BART benchmark and
the BART alternative from a common 2002 baseline, and approving the
state's use of emissions reductions from post-2002 regulations as
surplus that could be credited to its BART alternative); 79 FR 33438,
33441-42 (June 11, 2014) (approving Washington's credit to its BART
alternative for reductions achieved through controls installed post-
2002 in order to meet other CAA requirements).
    In sum, in this final action approving Utah's NOX BART
Alternative, the EPA finds that Utah properly compared the BART
Benchmark to the BART Alternative, using its modeling of the emissions
reductions of each without the other from the 2001-2003 baseline
period, consistent with the Regional

Haze Rule, its regulatory history, EPA guidance, and case law.
    Comment summary: Some commenters argued that there are three legal
flaws with Utah's treatment of SO2 emissions reductions from
the Carbon plant shutdown. As explained in the preamble to the proposed
rule, Utah's SIP revision continues to report historical emissions for
the Carbon plant in annual milestone reports for the SO2
Backstop Trading Program to ensure that SO2 emissions
reductions from the Carbon shutdown are not double-counted towards the
NOX BART Alternative and the SO2 Backstop Trading
Program. First, the commenters argued that the approach violates 40 CFR
51.309(d)(4)(iii)'s requirement that reporting under the SO2
Backstop Trading Program include ``actual'' emissions. Second, the
commenters argued that the approach violates 40 CFR 51.309(d)(4)(i),
which requires that participating states use the same compliance
methodology during the first two years of the Program. Finally, the
commenters argued that removing Carbon from the SO2 Backstop
Trading Program would undermine and potentially nullify the EPA's
approval of that Program because the Program's inclusion of sources
like Carbon was an underpinning of the EPA's approval.
    Response: The EPA disagrees with this comment and the incorporated
2016 comments by the National Park Service. First, 40 CFR
51.309(d)(4)(iii)'s requirement that SIPs include provisions requiring
``annual reporting of actual stationary source SO2
emissions'' must be read in context with the following sentence that
such ``data must be sufficient to determine annually whether the
milestone for each year through 2018 is achieved.'' \21\ The provision
goes on to require that the participating states submit the data to the
EPA and the regional planning organization and that the data be kept
for at least 10 years. Thus, read in context, Sec.  51.309(d)(4)(iii)
plainly is meant to require reporting that allows a determination of
whether the milestones have been met.\22\ Utah's approach to reporting
Carbon's emissions under the SO2 Backstop Trading Program
serves this purpose because Utah will overstate actual emissions under
the Program. This conservative approach ensures that the reported data
are sufficient to determine whether the SO2 milestone is
achieved and is therefore consistent with and achieves the purpose of
the provision, and the EPA finds it approvable.
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    \21\ 40 CFR 51.309(d)(4)(iii).
    \22\ See 64 FR 35751-52 (``Section 51.309(d)(4) requires
monitoring and reporting of stationary source emissions of
SO2 in order to assess compliance with these milestones
during the period 2003 to 2018.'').
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    As explained in the proposal, the participating states first
achieved the 2018 milestone (the most stringent milestone) in 2011 when
Carbon was fully operational. Between 2011 and Carbon's shutdown in
2015, emissions continued to stay below the 2018 milestone and
decreased significantly each year. The most recent milestone report,
for 2016, demonstrates that SO2 emissions were 36 percent
lower than the 2018 milestone.\23\ At its highest reported
SO2 emissions level, Carbon's emissions made up only 10
percent of the participating states' three-year average SO2
emissions (reported in 2014).\24\ Thus, even with the additional
emissions from Carbon, the participating states can easily achieve the
2018 milestone, and overstating Utah's emissions for purposes of the
SO2 Backstop Trading Program will not impair any
determination of compliance with the milestones.
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    \23\ 85 FR 3570.
    \24\ Id. at Table 6.
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    Second, Utah's approach does not violate 40 CFR 51.309(d)(4)(i). As
an initial matter, the commenters selectively quote the provision. The
complete sentence reads, ``[d]uring the first two years of the program,
compliance with the milestone may be measured by a methodology of the
States' choosing, so long as all States in the program use the same
methodology.'' \25\ The SO2 Backstop Trading Program was
approved in 2012, which is more than two years ago.\26\ Thus, this
sentence is no longer applicable.
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    \25\ 40 CFR 51.309(d)(4)(i) (emphasis added).
    \26\ See 77 FR 73926 (Dec. 12, 2012).
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    Instead, after the first two years of the Program, Sec.
51.309(d)(4)(i) requires that participating states measure compliance
by comparing ``a three-year rolling average of actual emissions with a
rolling average of the emissions milestones for the same three years.''
Utah's SIP revision remains consistent with this methodology. Under
this methodology, each state reports its own emissions.\27\ As
explained above, using this methodology, the participating states
achieved the 2018 milestone in 2011, and emissions are currently 36
percent below the 2018 milestone.\28\ Accordingly, Wyoming and New
Mexico are not prejudiced by Utah's continued reporting of the Carbon
emissions, nor do they have any reason to amend their SIPs to account
for Carbon's emissions. Indeed, the EPA approved a similar SIP revision
for units in Wyoming in 2019.\29\ Utah's approach is consistent with
Sec.  51.309(d)(4)(i) and with the other states' methodologies.
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    \27\ See Utah Admin. Code R307-250-9(8); WY Rules and
Regulations 020.0002.14 Sec.  2(h)(viii); New Mexico Admin. Code
<IP_ADDRESS>(O) and <IP_ADDRESS>(H) (all requiring quarterly and
annual reports).
    \28\ 85 FR 3570 (Table 6).
    \29\ See 84 FR 22711, 22712, 22715 (May 20, 2019) (requiring
Basin Electric to use inflated emission rates to calculate and
report emissions from two units for the SO2 Backstop
Trading Program to ensure SO2 emissions are not double
counted for the SO2 Program and the BART alternative).
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    Finally, Utah's approach does not undermine or nullify the EPA's
approval of the SO2 Backstop Trading Program. In approving
the Program as better than BART, the EPA relied on the fact that the
Program, including the 2018 SO2 emissions milestone, covered
63 non-BART sources, including Carbon.\30\ It hardly undermines the
EPA's approval that one of the sources that was included in the Program
has now shut down. The Program was designed to encourage sources to
reduce emissions so that the emissions milestones were and are never
exceeded.\31\ In any case, Utah has not removed Carbon from the
Program, but rather has decided to continue counting its emissions at
historical levels towards the 2018 milestone, even though the source is
now actually emitting at zero. That is, emissions from Carbon remain
covered by the SO2 Backstop Trading Program. Even accounting
for Carbon's historical emissions, the participating states'
SO2 emissions are far below the 2018 milestone and there is
no indication that the 2018 milestone will ever be exceeded such that
emissions under the Program would exceed projected emissions under
BART, thereby rendering the Program less effective than BART.
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    \30\ 77 FR 30953, 30965 (May 24, 2012).
    \31\ 77 FR 74360. Participating states must continue to meet the
2018 milestone until the Program is replaced with an EPA-approved
SIP revision. See also 40 CFR 51.309(d)(4)(vi)(A).
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    Even it if was the case that Utah had removed Carbon from the
SO2 Backstop Trading Program, however, the inclusion of non-
BART units like Carbon was just one of several reasons the EPA deemed
the Program better than BART. Additional reasons included: (1) The
trading program discouraged emissions from new sources more effectively
than under BART; (2) the trading program included an aggregate cap on
emissions, which decreased emissions more effectively than BART; and
(3) the trading program encouraged earlier reductions than under
BART.\32\ The Tenth Circuit upheld the EPA's considerations as ``a
reasonable basis for

the EPA's approval of the 309 program.'' \33\ Accordingly, Utah's
continued accounting of the Carbon emissions in the SO2
Backstop Trading Program, which arguably affects just one part of the
EPA's rationale in a proportionally minor way (1/63), cannot possibly
undermine or nullify the EPA's approval.
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    \32\ See 77 FR 30965; 77 FR 73927.
    \33\ WildEarth Guardians v. EPA, 770 F.3d 919, 935 (10th Cir.
2014).
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    Finally, as noted above, Carbon has not been removed from the
Program as the commenters contend. Rather, as explained above, Carbon's
emissions continue to be included in the inventory of annual emissions
notwithstanding the fact that it is shut down.\34\ Thus, SO2
emissions remain capped at the 2018 milestone, including Carbon's
emissions. To the extent it may become necessary, future SO2
reductions would have to come from other sources in order to allow the
participating states to continue to meet the 2018 milestone.
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    \34\ See 85 FR 3574.
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    Comment summary: Some commenters assert that the EPA may not
approve the NOX BART Alternative because the NOX
BART Alternative would allow increased emissions limits and visibility
impairment without offsetting increased emissions elsewhere in Utah's
SIP in violation of CAA section 110(l), 42 U.S.C. 7410(l). The
commenters argue that case law supports an interpretation of CAA
section 110(l) that prevents implementation plan revisions that would
increase overall air pollution limits or worsen air quality. The
commenters argue that the EPA's approval of the NOX BART
Alternative and withdrawal of the FIP would violate CAA section 110(l)
for two specific reasons. First, the commenters assert that the
NOX BART Alternative would increase emissions limits and
resulting NOX pollution compared to the FIP. They argue that
the EPA's proposed analysis and conclusion that increased
NOX emissions will not interfere with applicable CAA
requirements is ``woefully insufficient to support compliance with
section 110(l).'' Second, the commenters assert that Utah's treatment
of the SO2 emissions reductions from the Carbon plant, which
continues to report Carbon's emissions under the SO2
Backstop Trading Program so that they can be credited to the
NOX BART Alternative, violates CAA section 110(l). The
commenters argue that such treatment eliminates an applicable
requirement under the CAA that results in an increase in overall
allowed emissions.
    Response: The EPA disagrees with these comments. CAA section 110(l)
states in relevant part: ``The Administrator shall not approve a
revision of a plan if the revision would interfere with any applicable
requirement concerning attainment and reasonable further progress (as
defined in section 7501 of this title), and any other applicable
requirement of this chapter.'' \35\ CAA section 110(l) applies to all
requirements of the CAA and to all areas of the country, whether
attainment, nonattainment, unclassifiable or maintenance for one or
more of the six criteria pollutants. EPA interprets section 110(l) as
applying to all National Ambient Air Quality Standards (NAAQS) that are
in effect, including those for which SIP submissions have not been
made.\36\ However, the level of rigor needed for any CAA section 110(l)
demonstration will vary depending on the nature and circumstances of
the revision.
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    \35\ 42 U.S.C. 7410(l).
    \36\ In general, a section 110(l) demonstration should address
all pollutants whose emissions and/or ambient concentrations would
change as a result of a plan revision. Here, commenters allege that
emissions and/or ambient concentrations of NOX and
SO2 would change as a result of this plan revision.
---------------------------------------------------------------------------

    There are two possible paths for satisfying CAA section 110(l).
First, a state may demonstrate through an air quality analysis that the
revision will not interfere with attainment of the NAAQS, reasonable
further progress, or any other applicable requirements. Second, a state
may substitute equivalent emissions reductions to compensate for any
change to a plan to ensure actual emissions to the air are not
increased and thus preserve status quo air quality.\37\ The second
approach may be used, for example, where no attainment demonstrations
are available to guide an analysis of whether the SIP revision would
interfere with attainment of the NAAQS. However, nothing in the statute
requires a state to rely on substitute emission reductions or alters
the basic proposition that section 110(l) can be satisfied by an air
quality analysis demonstrating that a plan revision will not interfere
with any applicable requirement concerning attainment and reasonable
further progress, or any other applicable CAA requirement. As explained
in greater detail below, in this case, the EPA has concluded based on
an air quality analysis that the revision will not interfere with
attainment of the NAAQS or any other applicable CAA requirement and is
not relying on substitute emission reductions.
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    \37\ ``Equivalent'' emissions reductions are reductions that are
equal to or greater than those reductions achieved by the control
measure approved into the plan. To show that compensating emissions
reductions are equivalent, adequate justification must be provided.
The compensating, equivalent reductions should represent actual
emissions reductions achieved in a contemporaneous time frame to the
change of the existing control measure in order to preserve the
status quo air quality. If the status quo is preserved,
noninterference is demonstrated. In addition to being
contemporaneous, the equivalent emissions reductions should also be
permanent, enforceable, quantifiable, and surplus.
---------------------------------------------------------------------------

    Before addressing comments regarding the EPA's analysis, however,
we address the commenters' suggestion that CAA section 110(l) per se
prohibits approval of any SIP revision that allows an increase in
emissions or weakens requirements relative to the existing
implementation plan.\38\ Such an interpretation is not supported by the
statutory language or case law. First, the plain language of the
provision does not prohibit every SIP revision that allows an increase
in emissions or weakens the existing plan's requirements. Rather, the
language prohibits EPA approval of such a SIP revision if it would
interfere with attainment of the NAAQS, reasonable further progress, or
any other applicable requirement of the CAA.\39\ Thus, the language
focuses on interference rather than on emissions increases or changed
requirements.
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    \38\ While the EPA acknowledges that this action will allow for
greater NOX emissions than the 2016 FIP, the EPA does not
concede that this action weakens regional haze requirements or
allows increased visibility impairment. Instead, as is explained in
the preamble to the proposed rule, this document, and in the EPA's
response to comments, Utah's NOX BART Alternative will
achieve greater reasonable progress through combined NOX,
SO2, and PM reductions and therefore results in a
stronger regional haze requirement than the existing plan. See,
e.g., 85 FR 3566 (Table 3), 3569, 3573.
    \39\ See 42 U.S.C. 7410(l).
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    Second, courts have upheld EPA's interpretation that the relevant
inquiry under CAA section 110(l) is not whether the SIP revision allows
an increase in emissions or weakens requirements, but whether there has
been a demonstration that the SIP revision would interfere with the
NAAQS, reasonable further progress, or any other applicable CAA
requirement.
    For example, in Kentucky Resources Council v. EPA, the petitioners
argued that a new attainment demonstration, which was not due for years
after action on the SIP revision, was required in order to show
noninterference under CAA section 110(l). Instead, the examination in
that case was based on whether the area, which was designated as a
nonattainment area for the relevant NAAQS, would have more difficulty
attaining and maintaining the NAAQS with the SIP revision (i.e.,
whether the SIP revision would interfere with

attainment and maintenance of the NAAQS). In upholding the EPA's
interpretation and examination, the U.S. Court of Appeals for the Sixth
Circuit explained, ``Congress did not intend that the EPA reject each
and every SIP revision that presents some remote possibility for
interference. Thus, where EPA does not find that a SIP revision would
interfere with attainment, approval of the revision does no violence to
the statute.'' \40\ The Sixth Circuit further explained that, ``[i]n
rejecting [a] strict interpretation in favor of one that allows
[states] more flexibility, the EPA does service to a fundamental
premise underlying the Clean Air Act scheme, which is that the states
have the primary responsibility for ensuring that the NAAQS are met.''
\41\ Likewise, the U.S. Court of Appeals for the Eleventh Circuit
upheld the EPA's interpretation stating, ``[w]e agree that where
interference is not demonstrated, approval of the state's SIP revision
appropriately respects the state's choice to achieve air quality
standards with `whatever mix of emission limitations it deems best
suited to its particular situation.' '' \42\
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    \40\ 467 F.3d 986, 994 (6th Cir. 2006).
    \41\ Id. at 996.
    \42\ Alabama Environmental Council v. EPA, 711 F.3d 1277, 1293
(11th Cir. 2013) (quoting Train v. NRDC, Inc., 421 U.S. 60, 79
(1975)). See also Indiana v. EPA, 796 F.3d 803, 811 (7th Cir. 2015)
(``When deciding whether to approve Illinois's SIP revision, EPA was
required to determine whether the revision would, going forward,
interfere with attainment.'') (emphasis in original); Galveston-
Houston Ass'n for Smog Prevention v. EPA, 289 Fed. Appx. 745, 754
(5th Cir. 2008) (``[C]hanges to a SIP, either dropping measures or
reducing measurement requirements, are not by themselves sufficient
to prove interference. Rather, one must show that the substitute
measures are not at least equivalent to the previous measures in
achieving attainment.'').
---------------------------------------------------------------------------

    The commenters misconstrue other cases. In El Comite Para El
Bienestar de Earlimart v. EPA and WildEarth Guardians v. EPA, the U.S.
Court of Appeals for the Ninth Circuit dismissed petitioners' CAA
section 110(l) challenges without addressing what is required to show
that a SIP revision violates CAA section 110(l).\43\ And contrary to
the commenters' assertion, neither Indiana v. EPA nor Kentucky
Resources Council v. EPA stand for the proposition that the EPA must
require substitute emissions reductions when a SIP revision increases
emissions so that overall net emissions do not increase. In those
cases, the U.S. Courts of Appeal for the Sixth and Seventh Circuits
simply held that the EPA reasonably concluded that CAA section 110(l)
was not violated when substitute emissions reductions were included in
the SIP revisions at issue.\44\ But as explained above, the EPA has
previously identified two options for demonstrating noninterference
under CAA section 110(l): (1) Substitution of one measure by another
with equivalent or greater emissions reductions/air quality benefit;
and (2) an air quality analysis showing that removing the measure will
not interfere with other applicable requirements (i.e., without a
substitute measure).\45\ Here the SIP submission did not include
substitute measures and the EPA chose to evaluate the air quality
impact of the proposed revision. As we explain below, the EPA's air
quality analysis shows that the Utah SIP revisions will not interfere
with attainment of the NAAQS, reasonable further progress, or any other
CAA requirement.
---------------------------------------------------------------------------

    \43\ See El Comite Para El Bienestar de Earlimart v. EPA, 786
F.3d 688, 696-97 (9th Cir. 2015); WildEarth Guardians v. EPA, 759
F.3d 1064, 1074 (9th Cir. 2014).
    \44\ See Kentucky Resources Council, 467 F.3d at 995-96;
Indiana, 796 F.3d at 812-13.
    \45\ See Indiana, 796 F.3d at 806.
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    Importantly, the statute does not require any ``specific
methodology'' for air quality analyses under CAA section 110(l).\46\ In
general, the level of rigor needed for any CAA section 110(l)
demonstration will vary depending on the nature of the revision, its
potential impact on emissions and air quality, and the air quality in
the affected areas.
---------------------------------------------------------------------------

    \46\ Kentucky Resources Council, 467 F.3d at 995.
---------------------------------------------------------------------------

    In the proposed rule, the EPA proposed to find that the SIP
revisions satisfy section 110(l). The document explained how the
proposed SIP revisions and associated FIP withdrawal will comply with
and thus could not be said to interfere with applicable regional haze
requirements and general implementation plan requirements such as
enforceability. The proposal also addressed potential interference with
requirements concerning attainment and reasonable further progress,
stating that the Utah SIP revisions will allow for greater
NOX emissions at the four subject-to-BART units as compared
to the 2016 FIP (which is currently judicially stayed). The proposal
went on to explain that the change in these emissions compared to the
FIP, however, is not anticipated to interfere with any applicable
requirements under the CAA. We explained that the geographic area where
the BART units are located is not part of a nonattainment area for any
NAAQS. Furthermore, we explained that the approved portions of the
PM2.5 attainment demonstrations and clean data
determinations (CDD) for the Salt Lake City, Provo, and Logan, UT-ID
nonattainment areas (NAAs) do not rely on the installation of SCR at
Hunter or Huntington to achieve attainment of the NAAQS. Similarly, we
explained that the EPA recently approved Utah's PM10
redesignation requests and maintenance plans for Salt Lake County, Utah
County, and Ogden City NAAs.\47\ These PM10 redesignation
requests and maintenance plans do not rely on the installation of SCR
at Hunter or Huntington to achieve attainment of the NAAQS. Finally, we
explained that there are no other approved attainment demonstrations in
other areas of the State or outside of the State that rely on the
installation of SCR at Hunter or Huntington to achieve attainment of
any of the NAAQS.\48\
---------------------------------------------------------------------------

    \47\ The PM10 redesignations for Salt Lake County,
Utah County, and Ogden City nonattainment areas revised 40 CFR
81.345 to signify that these areas are in attainment. Utah
demonstrated maintenance of the PM10 standard to 2035
through the maintenance plans.
    \48\ 85 FR 3574.
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    The commenters contend that the EPA's air quality analysis is
inadequate but did not provide any evidence that Utah's SIP revisions
will interfere with any specific applicable requirement under the CAA.
Here, for the reasons explained below, the EPA now confirms the
proposed conclusions from the CAA section 110(l) analysis in the
proposal.
    First, the geographic area where the Hunter and Huntington Units
are located is not part of a nonattainment area for any NAAQS. Also,
monitors in the geographic area do not currently show exceedances of
the ozone NAAQS.\49\
---------------------------------------------------------------------------

    \49\ EPA, ``Air Quality System Preliminary Design Value
Report,'' October 7, 2020.
---------------------------------------------------------------------------

    Second, since the publication of the proposal on January 22, 2020,
the PM10 areas for Salt Lake County, Utah County, and Ogden
City were redesignated as attaining the PM10 NAAQS.\50\ The
areas continue to attain the PM10 NAAQS based on the most
recent official ambient data (2017-2019).\51\ This means that these
areas attained the NAAQS at current emission levels, i.e., the emission
levels allowed by the NOX controls installed at Hunter and
Huntington between 2006 and 2014 and which will be maintained under
Utah's NOX BART Alternative. Because the FIP was judicially
stayed and the NOX emission controls required by the FIP
(SCRs) were never installed, current emissions levels do not reflect
emission levels that would have been achieved if the FIP had been
implemented. In other words, the EPA's approval of the Utah
NOX BART Alternative will not cause an increase in
NOX emissions at Hunter

or Huntington compared to current conditions. Therefore, the SIP
approval will not interfere with already-achieved NAAQS attainment for
PM10, and there is no evidence, including none provided by
the commenters, to suggest that PM10 areas for Salt Lake
County, Utah County, and Ogden City will not continue to attain the
NAAQS following our approval of the SIP and concurrent withdrawal of
the FIP.
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    \50\ 85 FR 10989 (Feb. 26, 2020).
    \51\ EPA, ``Air Quality System Preliminary Design Value
Report,'' September 15, 2020.
---------------------------------------------------------------------------

    Third, the Northern Wasatch Front, Southern Wasatch Front, and
Uinta Basin ozone non-attainment areas were designated nonattainment
for the 2015 ozone NAAQS on August 3, 2018.\52\ As part of the 2018
ozone designation process, the EPA conducted a meteorological Hybrid
Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) analysis to
determine whether sources near the monitors violating the NAAQS
contribute to the Northern and Southern Wasatch Front ozone non-
attainment areas. Evaluation of such meteorological data helps to
assess the fate and transport of emissions contributing to ozone
concentrations and to identify areas potentially contributing to the
monitored violations. Results of the HYSPLIT analysis for the Northern
and Southern Wasatch Front ozone nonattainment areas show that back
trajectories rarely originated or passed through Carbon and Emery
counties on high ozone days in the Wasatch Front (where Hunter and
Huntington are located).\53\ Instead, the HYSPLIT analysis indicates
that emissions originating within Davis and Salt Lake Counties, the
southern portion of Weber County, the northern portion of Utah County,
and the eastern portion of Tooele County primarily contribute to
monitor violations.\54\ Furthermore, the monitors in the Southern
Wasatch Front ozone nonattainment area (closest to the BART sources)
are currently attaining the ozone standard using 2017-2019 and
preliminary 2018-2020 data.\55\
---------------------------------------------------------------------------

    \52\ 83 FR 25776, 25836 (June 4, 2018). At that time, the ozone
monitors located closest to the two power plants, in Carbon County,
did not violate the 2015 ozone standard. EPA, ``Utah: Northern
Wasatch Front, Southern Wasatch Front, and Uinta Basin Intended Area
Designations for the 2015 Ozone National Ambient Air Quality
Standards Technical Support Document (TSD),'' page 6 (``Utah 2015
Ozone TSD''). Also found in docket EPA-HQ-OAR-2017-0548; posted
January 5, 2018.
    \53\ Utah 2015 Ozone TSD, pages 18-25.
    \54\ Id. at 25.
    \55\ EPA, ``Air Quality System Preliminary Design Value
Report,'' October 7, 2020.
---------------------------------------------------------------------------

    For the Uinta Basin non-attainment area, the EPA has determined
that ozone production is a highly localized phenomenon. The Uinta Basin
is a winter ozone area, where violating ozone concentrations are
dependent on stagnant winter conditions associated with strong
temperature inversions. During the ozone designations process, the EPA
used the latest data and information available to the agency (and to
the states and tribes through the Ozone Designations Mapping Tool and
the EPA Ozone Designations Guidance and Data web page),\56\ to evaluate
emissions and air quality data and other information for counties in
the Uinta Basin. The EPA determined that the stagnant winter conditions
associated with strong temperature inversions limit the influence of
areas outside of the topographic Uinta Basin.\57\ Thus, at the time of
the 2018 designation, the EPA determined that sources in surrounding
counties (like Hunter and Huntington) do not contribute to the
violating area because of these unique geographic features and the
associated winter temperature inversion meteorology.
---------------------------------------------------------------------------

    \56\ The EPA's Ozone Designations Guidance and Data web page can
be found at https://www.epa.gov/ozone-designations/ozone-designations-guidance-and-data.
    \57\ Utah 2015 Ozone TSD, pages 29, 30.
---------------------------------------------------------------------------

    Fourth, the Salt Lake City, Provo, and Logan, Utah-Idaho (UT-ID)
PM2.5 nonattainment areas were designated nonattainment for
the 2006 24-hour PM2.5 NAAQS on November 13, 2009.\58\ On
October 19, 2018, the EPA finalized a determination of attainment for
the Logan, UT-ID PM2.5 nonattainment area.\59\ Based on the
most recent 3 years of valid data at that time (2015-2017), the Logan,
UT-ID nonattainment area attained the 2006 primary and secondary 24-
hour PM2.5 NAAQS by the attainment date of December 31,
2017. Likewise, on June 8, 2020, the EPA proposed a determination of
attainment, based on the most recent 3 years of valid data (2017-2019),
that the Salt Lake City and Provo nonattainment areas attained the 2006
primary and secondary 24-hour PM2.5 NAAQS by the attainment
date of December 31, 2019.\60\ On January 13, 2020, Utah submitted
redesignation requests for the Logan, UT-ID, Salt Lake City, and Provo
PM2.5 nonattainment areas and the EPA is actively reviewing
this submittal for future action.
---------------------------------------------------------------------------

    \58\ 74 FR 58688 (Nov. 13, 2009).
    \59\ 83 FR 52983 (Oct. 19, 2018). A nonattainment area may be
issued a determination of attainment by the EPA only if monitored
data demonstrate that air quality has improved enough that the NAAQS
is now being achieved. These determinations are based upon complete,
quality-assured data gathered at established state and local air
monitoring stations and national air monitoring stations in the
nonattainment area and must include a notice and comment rulemaking
by the EPA determining that the area is attaining the relevant
standard. Although a determination of attainment is not equivalent
to a redesignation in 40 CFR part 81, a determination of attainment
shows that monitored air quality no longer violates the NAAQS.
    \60\ 85 FR 35033 (June 8, 2020).
---------------------------------------------------------------------------

    Because the Logan, UT-ID PM2.5 nonattainment area is now
attaining the PM2.5 NAAQS and we proposed to find that the
Salt Lake City and Provo PM2.5 nonattainment areas are also
now attaining the PM2.5 NAAQS at current emission levels,
which would not increase upon approval of Utah's SIP revisions, the SIP
approval will not interfere with NAAQS attainment for PM2.5.
Additionally, there is no evidence, including none provided by the
commenters, to suggest that these areas will not continue to attain the
NAAQS following our approval of the SIP and concurrent withdrawal of
the FIP.
    Fifth, contrary to the commenters' argument, the EPA demonstrated
that the SIP approval will not interfere with the CAA's BART
requirements, including the SO2 Backstop Trading Program. As
explained elsewhere in this document, Utah's amendments to the
SO2 Backstop Trading Program do not alter the applicable
2018 SO2 milestone or the sources covered by the Program,
and thus maintain compliance with the Program and the Regional Haze
Rule. The SIP amendments to Utah's SO2 milestone reporting
requirements under the SO2 Backstop Trading Program are
merely an accounting exercise to ensure that emission reductions
resulting from the Carbon plant's closure are not credited towards both
the SO2 Backstop Trading Program and the NOX BART
Alternative. The SIP amendments further do not result in an actual
increase in emissions.
    In summary, we find that Utah's SIP revisions will not interfere
with attainment of the NAAQS, reasonable further progress, or other CAA
requirements because: (1) The geographic area where the Hunter and
Huntington Units are located is not part of a nonattainment area for
any NAAQS; (2) the recently redesignated former PM10
nonattainment areas in Salt Lake County, Utah County, and Ogden City
are attaining the PM10 NAAQS at current emission levels,
which would remain unchanged with approval of Utah's SIP revisions; (3)
we determined in 2018 that the Hunter and Huntington power plants do
not contribute to the Northern Wasatch Front and Southern Wasatch Front
ozone non-attainment areas, and that the Uinta Basin non-attainment
area is a highly localized phenomenon and sources in surrounding
counties, including the Hunter and Huntington power plants, do not
contribute to the violating area; (4) the Logan, UT-ID PM2.5
nonattainment area is attaining the

PM2.5 NAAQS, and we proposed to find that the Salt Lake City
and Provo PM2.5 nonattainment areas are also attaining the
PM2.5 NAAQS, all at current emission levels that would not
increase under Utah's SIP revisions; and (5) the Utah SIP revisions
properly account for SO2 emissions in accordance with
applicable requirements. Furthermore, the commenters provided no
analysis or information to indicate otherwise. Thus, we confirm our
position in the proposed rule that Utah's SIP revisions are not
anticipated to interfere with applicable requirements of the CAA and
therefore CAA section 110(l) does not prohibit approval of this SIP and
concurrent withdrawal of the FIP.

B. BART Alternative Requirements

    Comment summary: Some commenters asserted that because the EPA's
proposed rule would result in a significantly different distribution of
emissions from BART, it fails to show ``greater reasonable progress''
under 40 CFR 51.308(e)(3) than the EPA's previously issued FIP.
Specifically, the commenters assert that when alleged technical
deficiencies including those in the CAMx dispersion modeling are
corrected, the EPA is unable to prove ``greater reasonable progress''
because visibility will decline in one or more Class I areas and there
is not an overall improvement in visibility over all affected Class I
areas.
    Response: We disagree with this comment. The three plants (Hunter,
Huntington, and Carbon) are all located within 40 miles of each other
in Central Utah and are therefore similarly situated to the affected
Class I areas. But Utah chose to use CAMx dispersion modeling to assess
whether the NOX BART Alternative achieves greater reasonable
progress for the worst and best 20 percent of days (i.e., the two-prong
test). This is the regulatory test required under Sec.  51.308(e)(3) if
the distribution of emissions were substantially different.\61\ Thus,
the question of emissions distribution is not pertinent to the EPA's
approval of Utah's NOX BART Alternative. Any influence that
the respective geographic relationship of the emission reductions from
BART and the NOX BART Alternative have on visibility impacts
at the Class I areas is resolved by the CAMx modeling.
---------------------------------------------------------------------------

    \61\ See 40 CFR 51.308(e)(3).
---------------------------------------------------------------------------

    We respond to specific comments related to alleged technical
deficiencies in the modeling in more detail below and in the RTC
document. We find that the CAMx modeling used for the greater
reasonable progress demonstration was performed consistent with EPA
guidance and that the model performance was similar to applications of
the CAMx model that the EPA and states have used in previous actions
for regional haze.\62\ The CAMx modeling results showed that the
NOX BART Alternative met the requirements of the greater
reasonable progress two-prong test, i.e., visibility does not decline
in any Class I area under the BART Alternative relative to the Baseline
on both the 20% best and 20% worst days, and the average visibility
improvement across all affected Class I areas is greater under the BART
Alternative than under the BART Benchmark.\63\
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    \62\ Previous actions that relied on CAMx modeling include the
Cross-State Air Pollution Rule (CSAPR) (76 FR 48208 (Aug. 8, 2011));
the FIP revision for Laramie River Station in Wyoming (84 FR 22711
(May 20, 2019)); and the SIP revision for Coronado Generating
Station in Arizona (82 FR 46903 (Oct. 10, 2017)).
    \63\ See 85 FR 3573.
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C. BART Alternative ``Greater Reasonable Progress'' Determination

    Comment summary: Some commenters asserted that the CAMx modeling
supporting the Utah NOX BART Alternative is flawed because
it continues to assume that the installation and operation of SCR on
Hunter Units 1 and 2 and Huntington Units 1 and 2 would achieve a
NOX emission rate of 0.07 lb/MMBtu on a 30-day rolling
average, as approved by the EPA four years ago in its FIP. The
commenters contend that there are several electric generating units
(EGUs) that have achieved NOX emission rates of 0.04 lb/
MMBtu or lower on an annual average basis. The commenters further
contend that the EPA recently adopted a BART alternative for the
Laramie River Station in Wyoming and acknowledged that a 0.04 lb/MMBtu
NOX emission rate would be achieved with SCR on an annual
average basis under a 0.06 lb/MMBtu NOX limit applicable on
a 30-day average basis.
    The commenters further assert that while the Hunter and Huntington
BART units have been achieving 0.19-0.20 lb/MMBtu NOX rates
on an annual average basis in the last two years, these units should be
able to readily achieve a 0.04 lb/MMBtu annual average NOX
rate with SCR. The commenters contend that such a NOX rate
equates to a 74-80% NOX removal efficiency across the SCR,
and SCR systems are routinely designed to achieve 90% NOX
removal. The commenters therefore argue that it is improper to judge
the Utah BART Alternative against a BART Benchmark that utilizes
obsolete emissions information and that the EPA should not have assumed
a controlled annual average NOX rate any higher than 0.04
lb/MMBtu for the Hunter and Huntington Units in BART modeling.
    Response: We disagree with this comment. By way of background, the
EPA's FIP used an assumed emission rate of 0.05 lb/MMBtu on an annual
basis, but required compliance with a 0.07 lb/MMBtu, 30-day rolling
average limit.\64\ The commenters here contend that EPA should have
used a lower annual limit, which would in turn lower the 30-day rolling
average limit, for purposes of the BART Benchmark. As an initial
matter, emission limits associated with BART do not need to meet the
lowest emission rate achieved with that technology at any coal-fired
power plant. The Regional Haze Rule provides that ``[t]he determination
of BART must be based on an analysis of the best system of continuous
emission control technology available and associated emission
reductions achievable for each BART-eligible source that is subject to
BART.'' \65\
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    \64\ 81 FR 43903.
    \65\ 40 CFR 51.308(e)(1)(ii)(A).
---------------------------------------------------------------------------

    Additionally, the BART Guidelines state that: ``[i]n assessing the
capability of the control alternative, latitude exists to consider
special circumstances pertinent to the specific source under review, or
regarding the prior application of the control alternative,'' \66\ and
that ``[t]o complete the BART process, you must establish enforceable
emission limits that reflect the BART requirements.'' \67\ The five
factor BART analysis described in the Guidelines is a case-by-case
analysis that considers site-specific factors in assessing the best
technology for continuous emission controls. After a technology is
determined as BART, the BART Guidelines require establishment of an
emission limit that reflects the BART requirements, but does not
specify that the emission limit must represent the maximum level of
control achieved by the technology selected as BART.
---------------------------------------------------------------------------

    \66\ 40 CFR part 51, appendix Y, section IV.D.3.
    \67\ 40 CFR part 51, appendix Y, section V.
---------------------------------------------------------------------------

    While the BART Guidelines and the Regional Haze Rule do not
preclude selection of the maximum level of control achieved by a given
technology as BART, the emission limit must be set to reflect BART
which in turn must be determined based on a consideration and weighing
of the five statutory BART factors. Therefore, limits set in other BART
determinations, Best Available Control Technology during Prevention of
Significant Deterioration review, or emission rates achieved from the
operation of individual facilities under

an emissions trading program (e.g., CSAPR) may provide important
information, but should not be construed to automatically represent the
most appropriate BART limit for a given technology.
    Additionally, while the commenters cite actual annual emission
rates found in the EPA's Air Markets Program Database (AMPD) to support
their claim that an annual emission rate of 0.04 lb/MMBtu is achievable
with SCR, a more thorough review of the data supports the EPA's
conclusion that an annual emission rate no lower than 0.05 lb/MMBtu is
representative of what can be achieved when retrofitting SCR to an
existing boiler. Of the 155 coal-fired EGUs equipped with SCR operating
in 2019 with actual annual emission rates below 0.10 lb/MMBtu, 135
(87.1%) had actual annual emissions greater than 0.05 lb/MMBtu, 18
(11.6%) had actual annual emissions greater than 0.04 lb/MMBtu and less
than or equal to 0.05 lb/MMbtu, and only 2 (1.3%) had actual annual
emissions less than or equal 0.04 lb/MMBtu.\68\ The figure in our RTC
document shows the number of coal-fired EGUs equipped with SCR by
actual annual emission range in increments of 0.01 lb/MMbtu.
Notwithstanding the site-specific nature of SCR retrofits, these data
support the conclusion that an annual emission rate of 0.05 lb/MMBtu is
appropriate for the Utah BART units, and confirm that the assumption is
relatively conservative because the majority of EGUs equipped with SCR
have actual annual emission rates that are higher.
---------------------------------------------------------------------------

    \68\ See spreadsheet titled ``SCR Actual Annual Emissions by
Range.xlsx'' in the docket. Note that AMPD query returned a total of
265 coal-fired EGUs equipped with SCR operating in 2019. However,
many of these units had actual annual emission rates well in excess
of what would be anticipated with an SCR when operated on a year-
round basis. For that reason, the EPA eliminated all units with an
actual annual emission rate in excess of 0.10 lb/MMBtu from
consideration, leaving 155 units.
---------------------------------------------------------------------------

    Moreover, the lowest emission rates found in the AMPD database may
not be indicative of what can be expected at the Utah BART units for a
number of reasons. As noted above, the site-specific characteristic of
each SCR installation must be taken into account when determining the
anticipated actual annual emission rate. For example, the commenter
lists Dry Fork Unit 1 in Wyoming among units that are achieving an
actual annual emission rate of 0.04 lb/MMBtu.\69\ However, construction
on Dry Fork Unit 1 began in 2007 and SCR was integrated into the
original design, and not installed as a retrofit as would be the case
with the Utah BART units.
---------------------------------------------------------------------------

    \69\ AMPD data for 2019 show actual annual emissions of 0.0432
lb/MMBtu, above 0.04 lb/MMBtu.
---------------------------------------------------------------------------

    Our use of an anticipated actual annual emission rate with SCR of
0.05 lb/MMBtu here is also consistent with our 2016 FIP.\70\ The EPA is
unaware of, and the commenters have not cited, any advancements in SCR
retrofit technology that have occurred since our July 2016 final rule.
Accordingly, we have no reason to conclude that the assumptions we made
at that time regarding SCR performance are now obsolete.
---------------------------------------------------------------------------

    \70\ 81 FR 2034.
---------------------------------------------------------------------------

    Finally, the commenters have incorrectly assumed that a 90% control
efficiency can be achieved in all SCR applications regardless of the
input NOX emission rate or other parameters. In our July
2016 final rule, the EPA used an actual annual average emission rate
for LNB/SOFA (i.e., pre-SCR) at the Utah BART units of 0.20 lb/MMBtu to
0.22 lb/MMBtu.\71\ A 90% reduction with SCR from these emission rates
would yield annual emission rates of 0.020 lb/MMBtu to 0.022lb/MMBtu.
As can be seen from the AMPD data discussed above, no EGU has achieved
this level of control with SCR. Thus, because this level of control has
not been achieved in practice, it is not a realistic expectation for
the Utah BART units.
---------------------------------------------------------------------------

    \71\ See 81 FR 43903, Tables 2 through 5.
---------------------------------------------------------------------------

    Comment summary: Some commenters criticized the selection of Class
I areas for inclusion in the CAMx modeling domain. The commenters
asserted that the modeling included Class I areas beyond 300 kilometers
from the Carbon, Hunter, and Huntington power plants, and afforded
equal weight to areas near and distant from the pollution sources even
though there is higher confidence in the CAMx modeling at sites within
300 kilometers of the sources. The commenters further asserted that
PacifiCorp included certain areas (e.g. San Pedro Parks Wilderness Area
(New Mexico)) farther than 500km from the sources, while apparently
omitting others a similar distance away (e.g. Craters of the Moon in
Idaho; Jarbidge in Nevada; Yellowstone, Grand Teton, Washakie,
Fitzpatrick, and Bridger in Wyoming; Petrified Forest and Sycamore
Canyon in Arizona; and Rocky Mountain, Eagles Nest, Rawah, and Great
Sand Dunes in Colorado, among others). The commenters also stated that
while Utah appeared to give undue weight to visibility benefits at
certain distant Class I areas, Utah gave zero weight (and did not even
analyze) visibility impacts at similarly distant sites. The commenters
therefore argue that the assessed Class I areas were selected in an
arbitrary manner, and that the analysis does not account for visibility
impacts ``over all affected Class I areas,'' as required by the
Regional Haze Rule.\72\ The commenters argue that if corrected, the
alleged errors may flip the outcome of Utah's analysis; i.e., if the
Class I areas outside of 300 kilometers from the power plants are
omitted, the modeling fails to demonstrate that the average visibility
benefit of the BART Alternative will be greater than the 2016 FIP (BART
Benchmark).
---------------------------------------------------------------------------

    \72\ 40 CFR 51.308(e)(3)(ii).
---------------------------------------------------------------------------

    Response: The EPA disagrees with this comment. The draft modeling
protocol prepared by PacifiCorp included a rectangular modeling domain
that included all of the Class I areas within a distance of 300 km of
the Hunter and Huntington Units that had been considered in previous
CALPUFF modeling applications for these BART sources. The EPA reviewed
the proposed modeling domain and recommended that the boundaries of the
domain be extended farther east, north, and south to include terrain
features that could affect the transport of pollutants from the BART
sources.\73\ PacifiCorp agreed to extend the size of the domain as
requested by the EPA. Thus, for example, the domain was extended
farther north to include the Uinta mountain range in northern Utah, and
the domain was extended farther east such that the relevant Class I
areas were fully included in the model domain and were not located
close to the boundary of the domain. Because of the possibility of
modeling artifacts at domain boundaries,\74\ the EPA believed that the
larger model domain was technically more defensible. The motivation for
expanding the size of the model domain was to provide more accurate
model results, not to include more Class I areas. However, given that
additional Class I areas were included within the domain, the EPA
determined that it was appropriate to consider visibility benefits at
all Class I areas for which model results were available. The EPA
determined that it would have been arbitrary to include some Class I
areas

but not to include other nearby Class I areas for which modeling
results were available. The additional Class I areas (Mount Zirkel
Wilderness Area [WA], Maroon Bells/Snowmass WA, West Elk WA, La Garita
WA, Weminuche WA, and San Pedro Parks WA) are located close to and
within the same air basins as the other Class I areas previously
included in the CALPUFF modeling. While there are other Class I areas
located within 500 km of the sources, prevailing wind patterns and
terrain features make it less likely that emissions from Hunter and
Huntington would impact those areas, and the EPA did not find that it
was reasonable to recommend further expansion of the model domain to
include these Class I areas. In addition, the calculation of the
average difference between BART and the BART Alternative is most
influenced by the Class I areas closest to and most impacted by Hunter,
Huntington and Carbon. Therefore, small modeled impacts at additional
distant Class I areas would likely have little or no impact on the
average impact across all affected Class I areas.
---------------------------------------------------------------------------

    \73\ Email dated September 20, 2017, from Aaron Worstell (EPA)
to Jay Baker (UDAQ), Subject: Updated invitation: Utah Regional Haze
CAMx Model Review, docket ID EPA-R08-OAR-2015-0463-0228.
    \74\ For example, if emissions plumes near the model domain
boundaries are transported out of the model domain, those emissions
are permanently lost to the model, even if meteorological
recirculation patterns might cause those emissions to re-enter the
domain. Selecting a large model domain reduces the possibility that
emissions plumes will be transported out of the model domain.
---------------------------------------------------------------------------

    We also disagree with the comment that there is higher confidence
in the CAMx modeling at sites within 300 kilometers of the sources.
Higher confidence in modeling for sites within 300 kilometers is a
feature of the CALPUFF model. For example, the Interagency Workgroup on
Air Quality Modeling report recommended the ``use of CALPUFF for
transport distances of order 200 km and less. Use of CALPUFF for
characterizing transport beyond 200 to 300 km should be done cautiously
with an awareness of the likely problems involved.'' \75\ The CAMx
model is not subject to this limitation because it was developed and
has been widely used and evaluated for applications at distances much
greater than 300 kilometers, including modeling and regulatory analyses
for interstate transport of ozone and PM2.5. Photochemical
grid models such as CAMx are recommended by the EPA in Appendix W \76\
for long range transport modeling for secondary pollutants, including
regional haze.
---------------------------------------------------------------------------

    \75\ EPA, ``Interagency Workgroup on Air Quality Modeling
(IWAQM) Phase 2 Summary Report and Recommendations for Modeling Long
Range Transport Impacts,'' December 1998, pages 18 and D-11.
    \76\ 40 CFR part 51, appendix W.
---------------------------------------------------------------------------

    Comment summary: Some commenters asserted that the CAMx modeling
cannot support the NOX BART Alternative because it employs
the wrong metric for comparison. Specifically, the commenters argue
that instead of using ``the worst and best 20 percent of days'' to
demonstrate greater reasonable progress under 40 CFR 51.308(e)(3), Utah
should have substituted an analysis for the 20% of days in a calendar
year ``with the highest amount of anthropogenic visibility impairment''
under the EPA's 2017 revisions to the Regional Haze Rule. The
commenters argue that without such modeling, the EPA cannot demonstrate
in accordance with the regional haze requirements that the BART
Alternative would result in greater reasonable progress than BART as
determined in the EPA's FIP (BART Benchmark), and the BART Alternative
is not approvable.
    Response: We disagree that the CAMx modeling relied on in Utah's
SIP submittal employs the wrong metric for comparison of the BART
Benchmark and NOX BART Alternative. First, as explained
elsewhere in the preamble to the proposed rule, the RTC document, and
this document, Utah submitted its NOX BART Alternative, and
the EPA proposed to approve it, under the two-prong test in 40 CFR
51.308(e)(3)(i) and (ii). The two-prong test requires that ``the State
must conduct dispersion modeling to determine differences in visibility
between BART and the [alternative] for each impacted Class I area, for
the worst and best 20 percent of days.'' \77\ The 2017 revisions to the
Regional Haze Rule discussed by the commenter did not change 40 CFR
51.308(e)(3).\78\ Indeed, Sec.  51.308(e)(3) is a BART provision
applicable to the first regional haze planning period, and the EPA
explicitly did not make any changes to the Regional Haze Rule's BART
provisions in the 2017 revisions.\79\ Because Utah's SIP revisions are
intended to satisfy first planning period BART requirements,\80\ the
CAMx modeling properly employed the haziest days metric rather than the
new ``most impaired days'' metric.
---------------------------------------------------------------------------

    \77\ 40 CFR 51.308(e)(3) (emphasis added).
    \78\ See 82 FR 3078, 3124 (Jan. 10, 2017).
    \79\ See 81 FR 26942, 26947 (May 4, 2016) (``States undertook
the BART determination process during the first implementation
period. The BART requirement was a one-time requirement . . . .
Consequently, we are not proposing any changes to the BART
provisions in this rulemaking.'').
    \80\ See 85 FR 3575.
---------------------------------------------------------------------------

    Comment summary: Commenters assert that the most fundamental
technical deficiency in the CAMx modeling is the emissions information
used by Utah for the ``typical year'' scenario (also called the 2011
reference case). Commenters assert that the EPA provided no explanation
as to why the 2011 reference case was modeled with the 2001-2003
baseline period emissions at Carbon, Hunter and Huntington. Commenters
note that in the interval between the baseline period and the typical
year, PacifiCorp installed significant emissions control improvements
at both Hunter and Huntington, which resulted in substantial
SO2 reductions.
    Commenters assert that the Hunter and Huntington emission controls
are important because the associated impact of such controls on
visibility conditions in Class I areas in Utah and neighboring states
already would be reflected in the 2009-2013 five-year average
Interagency Monitoring of Protected Visual Environments (IMPROVE) data
used in the CAMx modeling. Commenters claim that by using the 2001-2003
baseline emissions to describe the Hunter and Huntington plants for the
2011 reference year, the post-2003 SO2 reductions at Hunter
and Huntington are essentially double counted. Commenters conclude that
Utah's approach to typical year emissions for the Hunter, Huntington
and Carbon power plants presents a fundamental error with the CAMx
modeling and the resulting implication is that the modeling results
cannot be used to support Utah's conclusion that the Utah
NOX BART Alternative would result in greater visibility
improvement compared to the EPA FIP (BART Benchmark).
    Response: We disagree with this comment. As an initial matter, the
commenters have not explained how the emissions data used in the 2011
Typical Year scenario results in a faulty outcome to the two-prong
regulatory analysis required under 40 CFR 51.308(e)(3). Indeed, the
modeling was appropriately designed to assess each prong in a
reasonable and technically defensible way.\81\
---------------------------------------------------------------------------

    \81\ See AECOM, ``Photochemical Modeling Protocol to Assess
Visibility Impacts for PacifiCorp Power Plants Located in Utah,''
January 2018.
---------------------------------------------------------------------------

    As we explained in the proposed rule, CAMx was configured to
simulate four modeling scenarios: the 2011 Typical Year, the 2025
Baseline, the BART Benchmark, and the Utah NOX BART
Alternative. The 2011 Typical Year scenario includes emissions for
Carbon, Hunter and Huntington at 2001-2003 levels, while all other
sources remain at 2011 levels. The annual NOX and
SO2 emissions modeled for each of these scenarios are shown
in Table 1 below.

                                               Table 1--Annual NOX and SO2 Emissions by Modeling Scenario
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                   2011  Typical year          2025  Baseline         2025  BART benchmark        2025  Utah NOX BART
                                               ------------------------------------------------------------------------------         alternative
                 Plant                    Unit                                                                               ---------------------------
                                                 NOX  (tpy)   SO2  (tpy)   NOX  (tpy)   SO2  (tpy)   NOX  (tpy)   SO2  (tpy)   NOX  (tpy)    SO2  (tpy)

--------------------------------------------------------------------------------------------------------------------------------------------------------
Carbon.................................      1        1,312        2,286        1,312        2,286        1,312        2,286             0             0
                                             2        1,977        3,528        1,977        3,528        1,977        3,528             0             0
Hunter.................................      1        6,380        2,535        6,380        2,535          796        1,153         3,166         1,153
                                             2        6,092        2,531        6,092        2,531          798        1,408         3,028         1,408
                                             3        6,530        1,204        6,530        1,204        6,530        1,230         4,490         1,230
Huntington.............................      1        5,944        2,380        5,944        2,380          793        1,254         3,147         1,254
                                             2        5,817       12,308        5,816       12,308          753        1,201         3,366         1,201
--------------------------------------------------------------------------------------------------------------------------------------------------------

    The modeling relied on the 2011 emissions data because a robust,
well-evaluated modeling platform was available only for 2011 and was
not available for any other year.
    The 2025 Baseline modeling scenario, which is based on the 2011
Typical Year scenario with emissions projected to 2025, also uses 2001-
2003 emissions for PacifiCorp's units in order to reflect only those
controls that were in place at those units in the baseline period
(i.e., pre-regional haze measures).\82\ This allows for a
straightforward comparison of the effects of the BART Benchmark versus
the Utah NOX BART Alternative relative to the 2025 Baseline
(i.e., relative to conditions without any regional haze measures
applied to the Utah BART sources). Because measures included in the
BART Alternative were installed starting in 2006, using emissions from
a later year to represent the baseline would not accurately reflect the
impacts of each of the two scenarios. While Utah could have chosen to
use different years to represent baseline emissions from Hunter,
Huntington, and Carbon, it chose to use a consistent period for these
Units that is also consistent with the baseline period of the regional
haze SIP, and we find this to be a reasonable approach.\83\
---------------------------------------------------------------------------

    \82\ Utah Regional Haze State Implementation Plan, Staff Review
of Recommended Alternative to BART for NOX, May 28, 2019,
page 13.
    \83\ Contrary to the commenters' claim, EPA explained this
approach in the proposed rule. 85 FR 3572.
---------------------------------------------------------------------------

    The 2011 Typical Year and the 2025 Baseline scenarios were used in
the development of relative response factors (RRFs) that were applied
to publicly available IMPROVE monitoring data in order to predict
future visibility conditions in 2025 for the BART Benchmark and the
NOX BART Alternative scenarios. The BART Benchmark and BART
Alternative results were then both compared to the 2025 Baseline
scenario and to each other to determine whether the BART Alternative
passes the two-prong test in Sec.  51.308(e)(3).
    The BART Benchmark scenario includes 2001-2003 Carbon and Hunter 3
emissions, because Carbon and Hunter 3 are not BART sources. But the
BART Benchmark reflects predicted NOX emissions reductions
from the installation of SCR controls on Hunter and Huntington Units 1
and 2 because those controls were required by EPA's 2016 FIP. The BART
Benchmark scenario also includes SO2 emissions from Hunter
and Huntington from 2014-2016 in order to match the BART Alternative
scenario, which as explained below, is important for the comparison in
Sec.  51.308(e)(3)(ii). The BART Alternative scenario includes
emissions from Hunter and Huntington from 2014-2016 to reflect all
emissions controls required by the Alternative, and zero emissions from
Carbon because the Alternative requires Carbon's 2015 shutdown. As
described below, these modeling scenarios allow an accurate comparison
between the BART Benchmark and the Utah NOX BART Alternative
under the two-prong test in Sec.  51.308(e)(3).
    The first step (prong 1) of the two-prong test requires a
demonstration that the BART alternative does not result in a decline in
visibility at any Class I area relative to a baseline.\84\ The record
clearly establishes that there is no decline in visibility under the
NOX BART Alternative when visibility impacts of the
NOX BART Alternative are compared to the 2025 Baseline
scenario.\85\ As we explained in the proposed rule under prong 1, while
the post-2003 SO2 reductions from Hunter and Huntington
increase the apparent overall visibility benefit of the BART
Alternative relative to the Baseline, there would not be an anticipated
decline in visibility relative to the Baseline in the absence of those
SO2 reductions from Hunter and Huntington because the BART
Alternative would still result in overall NOX,
SO2, and PM emissions decreases compared to the
Baseline.\86\
---------------------------------------------------------------------------

    \84\ 40 CFR 51.308(e)(3)(i).
    \85\ See 85 FR 3568-69, 3573, and Tables 4 and 5 (column D).
    \86\ Id. at 3573.
---------------------------------------------------------------------------

    At the second step of the (e)(3) test (prong 2), the state must
establish that there is ``an overall improvement in visibility,
determined by comparing the average differences between BART and the
alternative.'' \87\ Thus, the purpose of the modeling at this step is
to allow for a comparison between two control scenarios--the BART
benchmark and the BART alternative--relative to a baseline. It is not
critical that the baseline itself be entirely representative of what
might be expected to happen in 2025 so long as the emissions and
meteorological data used in the modeling allow for the comparison
between the BART benchmark and BART alternative. As noted above, the
commenters have not demonstrated that the 2025 Baseline scenario here
does not serve that purpose.
---------------------------------------------------------------------------

    \87\ 40 CFR 51.308(e)(3)(ii).
---------------------------------------------------------------------------

    As we explained in the proposed rule, the relative to the 2025
Baseline, the BART Benchmark and BART Alternative include actual
SO2 reductions from Hunter and Huntington that occurred
after the 2001-2003 baseline due to scrubber upgrades. Thus, the CAMx
modeling results for the BART Benchmark and BART Alternative shown in
Tables 4 and 5 of the proposed rule reflect these SO2
reductions. The treatment of these SO2 reductions in the
modeling does not affect the determination of greater reasonable
progress under the two-prong test. Under prong 2, because the
SO2 reductions from Hunter and Huntington are equal under
the BART Alternative and BART Benchmark, they do not advantage either
control scenario.\88\
---------------------------------------------------------------------------

    \88\ 85 FR 3572-73.
---------------------------------------------------------------------------

    In other words, even if the CAMx modeling counts Huntington and

Hunter as creating an additional visibility improvement in the BART
Benchmark and NOX BART Alternative scenarios relative to the
2025 Baseline scenario, this artifact of the data is present for both
the BART Benchmark and BART Alternative scenarios. Thus, it does not
have a meaningful effect on the comparison in relative improvement in
visibility between those scenarios. The modeling does not, and need
not, purport to establish actual, absolute improvements in visibility
under the two scenarios; it simply needs to allow for a comparison
between the scenarios. In order to pass the second prong under Sec.
51.308(e)(3), a BART alternative must show an overall average
improvement in visibility over the BART benchmark. Here, Utah's
NOX BART Alternative demonstrated an overall average
improvement over the BART benchmark of 0.00494 deciviews across all
Class I areas on the 20 percent best days and 0.00058 deciviews on the
20 percent worst days.\89\ Thus, Utah's NOX BART Alternative
passes the second prong of 40 CFR 51.308(e)(3).
---------------------------------------------------------------------------

    \89\ Id. at 3569.
---------------------------------------------------------------------------

    In sum, there is no merit to commenters' assertion that the data
used in the CAMx modeling cannot be used to support Utah's conclusion
that the Utah NOX BART Alternative would result in greater
visibility improvement compared to the EPA FIP (BART Benchmark) under
the two-prong test in Sec.  51.308(e)(3).

III. The EPA's Final Action

    For the reasons stated in the preamble to the proposed rule, in the
RTC document, and in this document, we are fully approving the SIP
revisions submitted by the State of Utah on July 3, 2019, as
supplemented on December 3, 2019.

A. 2019 Utah Regional Haze SIP Revisions

    We are approving these aspects of the 2019 Utah RH SIP revisions:
     NOX BART Alternative, including NOX
emission reductions from Hunter Units 1, 2 and 3 and Huntington Units 1
and 2, and SO2, NOX and PM emission reductions
from Carbon Units 1 and 2.
     A NOX emission limit of 0.26 lb/MMBtu (30-day
rolling average) each for Hunter Units 1 and 2 and Huntington Units 1
and 2.
     A NOX emission limit of 0.34 lb/MMBtu (30-day
rolling average) for Hunter Unit 3.
     A requirement to permanently close and cease operation of
the Carbon power plant by August 15, 2015.
     The associated amendments to the SO2 milestone
reporting requirements.
     MRR requirements for units subject to the NOX
BART Alternative and the PM BART emission limits.
    We also note that the regulatory text amendments contained in this
document include incorporation of additional parts of SIP section XX
(XX.B-C and XX.E-N) and section XXIII, which were not addressed in the
proposed action or in this final action. The EPA approved these SIP
sections as meeting the requirements of the CAA and applicable
regulations in previous actions; \90\ however, we inadvertently did not
incorporate all approved sections in 40 CFR 52.2320(e). We are
remedying this oversight and reorganizing 40 CFR 52.2320(e) to better
reflect the structure of Utah's SIP submissions here. We did not reopen
these previously approved SIP sections in this rulemaking.
---------------------------------------------------------------------------

    \90\ 73 FR 16543 (Mar. 28, 2008); 77 FR 74355 (Dec. 14, 2012);
78 FR 4072 (Jan. 18, 2013); 81 FR 43894 (July 5, 2016).
---------------------------------------------------------------------------

    Finally, consistent with our approval of Utah's July 2019 and
December 2019 SIP submissions, we find that Utah's SIP fully satisfies
the requirements of section 309 of the Regional Haze Rule and therefore
the State has fully complied with the requirements for reasonable
progress, including BART, for the first implementation period.

B. FIP Withdrawal

    Because we find that Utah's July 2019 and December 2019 SIP
submissions satisfy the NOX BART and MRR requirements
currently addressed by the EPA's 2016 FIP, we are also withdrawing in
whole the Utah Regional Haze FIP at 40 CFR 52.2336 that imposes
NOX BART requirements on Hunter Units 1 and 2 and Huntington
Units 1 and 2.

C. Clean Air Act Section 110(l)

    As we explain in detail in section II.A of this document and in the
RTC document that accompanies this action, we find that our approval of
the 2019 Utah SIP revisions and concurrent withdrawal of the
corresponding the FIP is consistent with CAA section 110(l), 42 U.S.C.
7410(l).

IV. Incorporation by Reference

    In this document, the EPA is finalizing regulatory text that
includes incorporation by reference. In accordance with the
requirements of 1 CFR 51.5, the EPA is finalizing the incorporation by
reference of the SIP amendments described in section III.A of this
preamble and set forth below. The EPA has made, and will continue to
make, these materials generally available through https://www.regulations.gov (refer to docket EPA-R08-OAR-2015-0463) and at the
EPA Region 8 Office (please contact the person identified in the FOR
FURTHER INFORMATION CONTACT section of this preamble for more
information).
    Therefore, these materials have been approved by the EPA for
inclusion in the SIP, have been incorporated by reference by the EPA
into that plan, are fully federally enforceable under sections 110 and
113 of the CAA as of the effective date of the final rulemaking of the
EPA's approval, and will be incorporated by reference by the Director
of the Federal Register in the next update to the SIP compilation.\91\
---------------------------------------------------------------------------

    \91\ 62 FR 27968 (May 22, 1997).
---------------------------------------------------------------------------

V. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review and Executive
Order 13563: Improving Regulation and Regulatory Review

    This action is not a ``significant regulatory action'' under the
terms of Executive Order 12866 \92\ and was therefore not submitted to
the Office of Management and Budget (OMB) for review. This final rule
applies to three facilities in the State of Utah. It is therefore not a
rule of general applicability.
---------------------------------------------------------------------------

    \92\ 58 FR 51735, 51738 (Oct. 4, 1993).
---------------------------------------------------------------------------

B. Executive Order 13771: Reducing Regulations and Controlling
Regulatory Costs

    This action is not an Executive Order 13771 regulatory action
because it is not significant under Executive Order 12866 for the
reasons stated in section V.A above. Instead, it is a Rule of
Particular Applicability that is exempted under Executive Order 12866.

C. Paperwork Reduction Act

    This action does not impose an information collection burden under
the PRA. Because this rule revises regional haze reporting requirements
for three facilities, the PRA does not apply.

D. Regulatory Flexibility Act

    I certify that this action will not have a significant economic
impact on a substantial number of small entities under the RFA. This
action will not impose any requirements on small entities. This rule
does not impose any requirements or create impacts on small

entities as no small entities are subject to the requirements of this
rule.\93\
---------------------------------------------------------------------------

    \93\ See 13 CFR 121.201, Sector 22, Subsector 221.
---------------------------------------------------------------------------

E. Unfunded Mandates Reform Act (UMRA)

    This action does not contain an unfunded mandate of $100 million or
more as described in UMRA, 2 U.S.C. 1531-1538, and does not
significantly or uniquely affect small governments.

F. Executive Order 13132: Federalism

    This action does not have federalism implications. It will not have
substantial direct effects on the states, on the relationship between
the National Government and the states, or on the distribution of power
and responsibilities among the various levels of government.

G. Executive Order 13175: Consultation and Coordination With Indian
Tribal Governments

    This action does not have tribal implications as specified in
Executive Order 13175. It will not have substantial direct effects on
tribal governments. Thus, Executive Order 13175 does not apply to this
action.
    In comments on the proposed rule, the Ute Mountain Ute Tribe
requested consultation. In response, the EPA offered consultation, but
the Ute Mountain Ute Tribe later waived the opportunity for
consultation.

H. Executive Order 13045: Protection of Children From Environmental
Health Risks and Safety Risks

    This action is not subject to Executive Order 13045.\94\ The EPA
interprets Executive Order 13045 as applying only to those regulatory
actions that concern environmental health or safety risks that the EPA
has reason to believe may disproportionately affect children, per the
definition of ``covered regulatory action'' in section 2-202 of the
Executive order. This action is not subject to Executive Order 13045
because it does not concern an environmental health risk or safety
risk.
---------------------------------------------------------------------------

    \94\ 62 FR 19885 (Apr. 23, 1997).
---------------------------------------------------------------------------

I. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use

    This action is not subject to Executive Order 13211 \95\ because it
is not a significant regulatory action under Executive Order 12866.
---------------------------------------------------------------------------

    \95\ 66 FR 28355 (May 22, 2001).
---------------------------------------------------------------------------

J. National Technology Transfer and Advancement (NTTAA)

    This rulemaking does not involve technical standards.

K. Executive Order 12898: Federal Actions To Address Environmental
Justice in Minority Populations and Low-Income Populations

    The EPA believes that this action does not have disproportionately
high and adverse human health or environmental effects on minority
populations, low-income populations and/or indigenous peoples, as
specified in Executive Order 12898 (59 FR 7629, February 16, 1994).
    The documentation for this decision is contained in EPA's EJ
analysis. The EPA's Guidance on Considering Environmental Justice
During the Development of Regulatory Actions \96\ is the Agency's guide
for determining when environmental justice should be considered when
developing regulations. In support of this guidance, the EPA used
EJSCREEN \97\ to identify areas of potential environmental justice (EJ)
concerns associated with this rulemaking. A 300-kilometer radius zone
of impact was used in the EJSCREEN analysis consistent with other
regional haze actions. The results do not identify any areas of
potential EJ concerns.\98\ Moreover as explained in the preamble to the
final rule and in response to comments, the Utah Regional Haze SIP, as
revised by this action, will ensure a significant reduction in
emissions compared to regional haze baseline levels (2002). Finally,
the EPA's analysis under CAA section 110(l) shows that this action will
not interfere with any applicable requirement concerning attainment and
reasonable further progress or any other applicable CAA requirements.
Thus, this final action will not create a disproportionately high and
adverse effect on minority, low-income, and/or indigenous/tribal
populations.
---------------------------------------------------------------------------

    \96\ https://www.epa.gov/sites/production/files/2015-06/documents/considering-ej-in-rulemaking-guide-final.pdf
    \97\ EJSCREEN: Environmental Justice Screening and Mapping Tool
is available at https://www.epa.gov/ejscreen.
    \98\ Results in the EJSCREEN Report for the Hunter and
Huntington Power Plants show percentiles of less than 80 for all EJ
Indexes evaluated. See EJSCREEN Report in the docket.
---------------------------------------------------------------------------

    The availability of regulations.gov to submit written comments and
a public hearing in Price, Utah provided meaningful opportunities for
public participation in the proposed rulemaking. The EPA considered
input received during the public comment period regarding environmental
justice considerations.

L. Determination Under Section Clean Air Act Section 307(d)

    Pursuant to CAA sections 307(d)(1)(B) and 307(d)(1)(V), the
Administrator determines that this action is subject to the provisions
of section 307(d). CAA section 307(d)(1)(B) provides that section
307(d) applies to, among other things, ``the promulgation or revision
of an implementation plan by the Administrator under [CAA section
110(c)].'' \99\ Under section 307(d)(1)(V), the provisions of section
307(d) also apply to ``such other actions as the Administrator may
determine.'' \100\ To the extent the approval of Utah's SIP submittals
is not expressly identified under section 307(d), the Administrator
hereby determines that section 307(d) applies to this aspect of this
action. The agency has complied with the procedural requirements of CAA
section 307(d) during the course of this rulemaking.
---------------------------------------------------------------------------

    \99\ 42 U.S.C. 7607(d)(1)(B).
    \100\ 42 U.S.C. 7607(d)(1)(V).
---------------------------------------------------------------------------

M. Congressional Review Act (CRA)

    This rule is exempt from the CRA because it is a rule of particular
applicability that only applies to three named facilities.

N. Judicial Review

    Under section 307(b)(1) of the CAA, petitions for judicial review
of this action must be filed in the United States Court of Appeals for
the appropriate circuit by January 26, 2021. Filing a petition for
reconsideration by the Administrator of this final rule does not affect
the finality of this action for purposes of judicial review nor does it
extend the time within which a petition for judicial review may be
filed and shall not postpone the effectiveness of such rule or action.
This action may not be challenged later in proceedings to enforce its
requirements. See CAA section 307(b)(2).

List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Incorporation by
reference, Intergovernmental relations, Nitrogen dioxide, Particulate
matter, Sulfur oxides.

Andrew Wheeler,
Administrator.

    For the reasons set forth in the preamble, 40 CFR part 52 is to be
amended as follows:

PART 52--APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS

0
1. The authority citation for part 52 continues to read as follows:

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

Subpart TT--Utah

0
2. In Sec.  52.2320:
0
a. The table in paragraph (c) is amended by revising the entries
``R307-110-17,'' ``R307-110-28,'' and ``R307-150-03''.
0
b. The table in paragraph (e) is amended by:
0
i. Adding the entries ``Section IX.H.21. General Requirements: Control
Measures for Area and Point Sources, Emission Limits and Operating
Practices, Regional Haze Requirements'' and ``Section IX.H.22. Source
Specific Emission Limitations: Regional Haze Requirements, Best
Available Retrofit Technology'' in numerical order.
0
ii. Removing from under the center heading ``XVII. Visibility
Protection'' the entries ``Progress Report for Utah's State
Implementation Plan for Regional Haze,'' ``Section XX.D.6. Best
Available Retrofit Technology (BART) Assessment for NOX and
PM,'' and ``Section XX.G. Long-Term Strategy for Fire Programs.''
0
iii. Adding the center heading ``XX. Regional Haze'' and the entries
``Section XX.A. Executive Summary'', ``Section XX.B. Background on the
Regional Haze Rule'', ``Section XX.C. Long-Term Strategy for the Clean-
Air Corridor'', ``Section XX.D. Long-Term Strategy for Stationary
Sources'', ``Section XX.E. Sulfur Dioxide Milestones and Backstop
Trading Program'', ``Section XX.F. Long-Term Strategy for Mobile
Sources'', ``Section XX.G. Long-Term Strategy for Fire Programs'',
``Section XX.H. Assessment of Emissions from Paved and Unpaved Road
Dust'', ``Section XX.I. Pollution Prevention and Renewable Energy
Programs'', ``Section XX.J. Other GCVTC Recommendations'', ``Section
XX.K. Projection of Visibility Improvement Anticipated from Long-Term
Strategy'', ``Section XX.L. Periodic Implementation Plan Revisions'',
``Section XX.M. State Planning/Interstate Coordination and Tribal
Implementation'', ``Section XX.N. Enforceable Commitments for the Utah
Regional Haze SIP'', and ``Progress Report for Utah's State
Implementation Plan for Regional Haze'' in numerical order and after
the entry ``Section XXIII. Interstate Transport''.
    The revisions and additions read as follows:

Sec.  52.2320  Identification of plan.

* * * * *
    (c) * * *

----------------------------------------------------------------------------------------------------------------
                                                        State       Final rule citation,
         Rule No.                 Rule title       effective date           date                 Comments
----------------------------------------------------------------------------------------------------------------

                                                  * * * * * * *
----------------------------------------------------------------------------------------------------------------
                            R307-110. General Requirements: State Implementation Plan
----------------------------------------------------------------------------------------------------------------

                                                  * * * * * * *
R307-110-17...............  Section IX. Control        11/25/2019  [INSERT Federal        ......................
                             Measures for Area                      Register CITATION]
                             and Point Sources,                     11/27/2020.
                             Part H, Emission
                             Limits.

                                                  * * * * * * *
R307-110-28...............  Section XX. Regional        8/15/2019  [INSERT Federal        ......................
                             Haze.                                  Register CITATION]
                                                                    11/27/2020.

                                                  * * * * * * *
----------------------------------------------------------------------------------------------------------------
                                         R307-150. Emission Inventories
----------------------------------------------------------------------------------------------------------------

                                                  * * * * * * *
R307-150-03...............  Applicability........       6/25/2019  [INSERT Federal        ......................
                                                                    Register CITATION]
                                                                    11/27/2020.

                                                  * * * * * * *
----------------------------------------------------------------------------------------------------------------

* * * * *
    (e) * * *

----------------------------------------------------------------------------------------------------------------
                                               State
               Rule title                 effective date   Final rule citation, date           Comments
----------------------------------------------------------------------------------------------------------------

                                                  * * * * * * *
----------------------------------------------------------------------------------------------------------------
                                 IX. Control Measures for Area and Point Sources
----------------------------------------------------------------------------------------------------------------

                                                  * * * * * * *
Section IX.H.21. General Requirements:        11/25/2019  [INSERT Federal Register    ..........................
 Control Measures for Area and Point                       CITATION] 11/27/2020.
 Sources, Emission Limits and Operating
 Practices, Regional Haze Requirements.
Section IX.H.22. Source Specific              11/25/2019  [INSERT Federal Register    ..........................
 Emission Limitations: Regional Haze                       CITATION] 11/27/2020.
 Requirements, Best Available Retrofit
 Technology.

                                                  * * * * * * *
----------------------------------------------------------------------------------------------------------------
                                                XX. Regional Haze
----------------------------------------------------------------------------------------------------------------
Section XX.A. Executive Summary.........       8/15/2019  [INSERT Federal Register    ..........................
                                                           CITATION] 11/27/2020.
Section XX.B. Background on the Regional       8/15/2019  [INSERT Federal Register    ..........................
 Haze Rule.                                                CITATION] 11/27/2020.
Section XX.C. Long-Term Strategy for the       8/15/2019  [INSERT Federal Register    ..........................
 Clean-Air Corridor.                                       CITATION] 11/27/2020.
Section XX.D. Long-Term Strategy for           8/15/2019  [INSERT Federal Register    ..........................
 Stationary Sources.                                       CITATION] 11/27/2020.
Section XX.E. Sulfur Dioxide Milestones        8/15/2019  [INSERT Federal Register    ..........................
 and Backstop Trading Program.                             CITATION] 11/27/2020.
Section XX.F. Long-Term Strategy for           8/15/2019  [INSERT Federal Register    ..........................
 Mobile Sources.                                           CITATION] 11/27/2020.
Section XX.G. Long-Term Strategy for            4/7/2011  [INSERT Federal Register    ..........................
 Fire Programs.                                            CITATION] 11/27/2020.
Section XX.H. Assessment of Emissions          8/15/2019  [INSERT Federal Register    ..........................
 from Paved and Unpaved Road Dust.                         CITATION] 11/27/2020.
Section XX.I. Pollution Prevention and         8/15/2019  [INSERT Federal Register    ..........................
 Renewable Energy Programs.                                CITATION] 11/27/2020.
Section XX.J. Other GCVTC                      8/15/2019  [INSERT Federal Register    ..........................
 Recommendations.                                          CITATION] 11/27/2020.
Section XX.K. Projection of Visibility         8/15/2019  [INSERT Federal Register    ..........................
 Improvement Anticipated from Long-Term                    CITATION] 11/27/2020.
 Strategy.
Section XX.L. Periodic Implementation          8/15/2019  [INSERT Federal Register    ..........................
 Plan Revisions.                                           CITATION] 11/27/2020.
Section XX.M. State Planning/Interstate        8/15/2019  [INSERT Federal Register    ..........................
 Coordination and Tribal Implementation.                   CITATION] 11/27/2020.
Section XX.N. Enforceable Commitments          8/15/2019  [INSERT Federal Register    ..........................
 for the Utah Regional Haze SIP.                           CITATION] 11/27/2020.
Progress Report for Utah's State                2/4/2016  85 FR 64050, 10/9/2020....  ..........................
 Implementation Plan for Regional Haze.

                                                  * * * * * * *
----------------------------------------------------------------------------------------------------------------

Sec.  52.2336   [Removed and Reserved]

0
3. Remove and reserve Sec.  52.2336.

[FR Doc. 2020-23994 Filed 11-25-20; 8:45 am]
BILLING CODE 6560-50-P