[Federal Register Volume 82, Number 80 (Thursday, April 27, 2017)]
[Proposed Rules]
[Pages 19333-19347]
[FR Doc No: 2017-08543]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R09-OAR-2017-0092; FRL-9961-98-Region 9]

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

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to
approve a source-specific revision to the Arizona state implementation
plan (SIP) that provides an alternative to Best Available Retrofit
Technology (BART) for the Coronado Generating Station (``Coronado''),
owned and operated by the Salt River Project Agricultural Improvement
and Power District. The EPA proposes to find that the BART alternative
for Coronado would provide greater reasonable progress toward natural
visibility conditions than BART, in accordance with the requirements of
the Clean Air Act and the EPA's Regional Haze Rule. In conjunction with
this proposed approval, we propose to withdraw those portions of the
federal implementation plan (FIP) that address BART for Coronado. We
also propose to codify the removal of those portions of the Arizona SIP
that have either been superseded by previously approved revisions to
the Arizona SIP or would be superseded by final approval of the SIP
revision for Coronado.

DATES: Written comments must be submitted on or before June 12, 2017.
Requests for public hearing must be received on or before May 12, 2017.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R09-
OAR-0092 at http://www.regulations.gov, or via email to Krishna
Viswanathan at<EMAIL_ADDRESS>For comments submitted at
Regulations.gov, follow the online instructions for submitting
comments. Once submitted, comments cannot be removed or edited from
Regulations.gov. For either manner

of submission, the EPA may publish any comment received to its public
docket. Do not submit electronically any information you consider to be
Confidential Business Information (CBI) or other information whose
disclosure is restricted by statute. Multimedia submissions (audio,
video, etc.) must be accompanied by a written comment. The written
comment is considered the official comment and should include
discussion of all points you wish to make. The EPA will generally not
consider comments or comment contents located outside of the primary
submission (i.e. on the web, cloud, or other file sharing system). For
additional submission methods, please contact the person identified in
the FOR FURTHER INFORMATION CONTACT section. For the full EPA public
comment policy, information about CBI or multimedia submissions, and
general guidance on making effective comments, please visit http://www2.epa.gov/dockets/commenting-epa-dockets.

FOR FURTHER INFORMATION CONTACT: Krishna Viswanathan, EPA, Region IX,
Air Division, Air Planning Office,<PHONE_NUMBER> or
<EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION: Throughout this document, ``we,'' ``us,''
and ``our'' refer to the EPA.

Table of Contents

I. General Information
II. Background
III. The Coronado SIP Revision
IV. The EPA's Proposed Action
V. Environmental Justice Considerations
VI. Incorporation by Reference
VII. Statutory and Executive Order Reviews

I. General Information

A. Definitions

    For the purpose of this document, we are giving meaning to certain
words or initials as follows:
     The initials AAC mean or refer to the Arizona
Administrative Code.
     The initials ADEQ mean or refer to the Arizona Department
of Environmental Quality.
     The words Arizona and State mean the State of Arizona.
     The word Coronado refers to the Coronado Generating
Station.
     The initials BART mean or refer to Best Available Retrofit
Technology.
     The initials BOD mean or refer to boiler operating day.
     The term Class I area refers to a mandatory Class I
Federal area.\1\
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    \1\ Although states and tribes may designate as Class I
additional areas which they consider to have visibility as an
important value, the requirements of the visibility program set
forth in section 169A of the CAA apply only to mandatory Class I
Federal areas. When we use the term ``Class I area'' in this action,
we mean a ``mandatory Class I Federal area.''
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     The initials CAA mean or refer to the Clean Air Act.
     The initials CBI mean or refer to Confidential Business
Information.
     The words EPA, we, us, or our mean or refer to the United
States Environmental Protection Agency.
     The initials FIP mean or refer to federal implementation
plan.
     The initials LNB mean or refer to low-NOX
burners.
     The initials MACT mean or refer to Maximum Available
Control Technology.
     The initials lb/MMBtu mean or refer to pounds per million
British thermal units.
     The initials NAAQS mean or refer to National Ambient Air
Quality Standards.
     The initials NSPS mean or refer to Standards of
Performance for New Stationary Sources.
     The initials NOX mean or refer to nitrogen oxides.
     The initials OFA mean or refer to over fire air.
     The initials PM mean or refer to particulate patter, which
is inclusive of PM10 (particulate matter less than or equal
to 10 micrometers) and PM2.5 (particulate matter less than
or equal to 2.5 micrometers).
     The initials SCR mean or refer to selective catalytic
reduction.
     The initials SIP mean or refer to state implementation
plan.
     The initials SO2 mean or refer to sulfur dioxide.
     The initials SRP mean or refer to the Salt River Project
Agricultural Improvement and Power District.

B. Docket

    The proposed action relies on documents, information, and data that
are listed in the index on http://www.regulations.gov under docket
number EPA-R09-OAR-2017-0092. Although listed in the index, some
information is not publicly available (e.g., CBI). Certain other
material, such as copyrighted material, is publicly available only in
hard copy form. Publicly available docket materials are available
either electronically at http://www.regulations.gov or in hard copy at
the Air Planning Office of the Air Division, AIR-2, EPA Region IX, 75
Hawthorne Street, San Francisco, CA 94105. The EPA requests that you
contact the individual listed in the FOR FURTHER INFORMATION CONTACT
section to view the hard copy of the docket. You may view the hard copy
of the docket Monday through Friday, 9-5:00 PDT, excluding federal
holidays.

C. Public Hearings

    If anyone contacts the EPA by May 12, 2017 requesting to speak at a
public hearing, the EPA will schedule a public hearing and announce the
hearing in the Federal Register. Contact Krishna Viswanathan at (520)
999-7880 or<EMAIL_ADDRESS>to request a hearing or to find
out if a hearing will be held.

II. Background

A. Summary of Statutory and Regulatory Requirements

    Congress created a program for protecting visibility in the
nation's national parks and wilderness areas in 1977 by adding section
169A to the CAA. This section of the CAA establishes as a national goal
the ``prevention of any future, and the remedying of any existing,
impairment of visibility in mandatory class I Federal areas which
impairment results from man-made air pollution.'' \2\ It also directs
states to evaluate the use of retrofit controls at certain larger,
often uncontrolled, older stationary sources in order to address
visibility impacts from these sources. Specifically, section
169A(b)(2)(A) of the CAA requires states to revise their SIPs to
contain such measures as may be necessary to make reasonable progress
towards the national visibility goal, including a requirement that
certain categories of existing major stationary sources built between
1962 and 1977 procure, install, and operate BART controls. These
sources are referred to as ``BART-eligible'' sources.\3\ In the 1990
CAA Amendments, Congress amended the visibility provisions in the CAA
to focus attention on the problem of regional haze, which is visibility
impairment produced by a multitude of sources and activities located
across a broad geographic area.\4\ We promulgated the initial Regional
Haze Rule in 1999 \5\ and updated it in 2017.\6\ The CAA and the
Regional Haze Rule require states to develop and implement SIPs to
ensure reasonable progress toward improving visibility in mandatory
class I Federal areas \7\ by reducing emissions that cause

or contribute to regional haze.\8\ Under the Regional Haze Rule, states
are directed to conduct BART determinations and establish emissions
limitations for BART-eligible sources that may be anticipated to cause
or contribute to any visibility impairment in a Class I area.\9\ In
lieu of requiring source-specific BART controls, states also have the
flexibility to adopt alternative measures, as long as the alternative
provides greater reasonable progress towards natural visibility
conditions than BART (i.e., the alternative must be ``better than
BART'').\10\
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    \2\ See CAA section 169B, 42 U.S.C. 7492.
    \3\ 40 CFR 51.301.
    \4\ See CAA section 169B, 42 U.S.C. 7492.
    \5\ 64 FR 35714 (July 1, 1999).
    \6\ 82 FR 3078 (January 10, 2017).
    \7\ Areas designated as mandatory Class I federal areas consist
of national parks exceeding 6000 acres, wilderness areas, and
national memorial parks exceeding 5000 acres, and all international
parks that were in existence on August 7, 1977. 42 U.S.C. 7472(a).
    \8\ See generally 40 CFR 51.308.
    \9\ 40 CFR 51.308(e).
    \10\ 40 CFR 51.308(e)(2) and (3).
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    In addition to the visibility protection requirements of the CAA
and the Regional Haze Rule, SIP revisions concerning regional haze are
also subject to the general requirements of CAA section 110. In
particular, they are subject to the requirement in CAA section 110(1)
that SIP revisions must not ``interfere with any applicable requirement
concerning attainment and reasonable further progress (as defined in
[CAA Sec.  171]), or any other applicable requirement of [the CAA],''
as well as the requirement in CAA section 110(a)(2)(A) that SIPs must
include enforceable emission limits.

B. History of FIP BART Determination

1. 2011 Arizona Regional Haze SIP and 2012 Arizona Regional Haze FIP
    The Arizona Department of Environmental Quality (ADEQ) submitted a
Regional Haze SIP (``Arizona Regional Haze SIP'') to the EPA on
February 28, 2011. The Arizona Regional Haze SIP included BART
determinations for nitrogen oxides (NOX), particulate matter
less than or equal to 10 micrometers (PM10), and sulfur
dioxide (SO2) for Units 1 and 2 at Coronado. In a final rule
published on December 5, 2012, the EPA approved ADEQ's BART
determinations for PM10 and SO2, but disapproved
ADEQ's determination for NOX at Coronado.\11\ We also found
that the SIP lacked the requisite compliance schedules and requirements
for equipment maintenance and operation, including monitoring,
recordkeeping, and reporting requirements for BART for all pollutants.
At the same time, we promulgated a FIP that included a plant-wide
NOX BART emission limit for Coronado of 0.065 pounds per
million British thermal units (lb/MMBtu) based on a 30-boiler-
operating-day (BOD) rolling average, which Salt River Project
Agricultural Improvement and Power District (SRP) could meet by adding
a low-load temperature control to its existing selective catalytic
reduction (SCR) system on Unit 2 and installing an SCR system including
a low-load temperature control system on Unit 1. The FIP also included
compliance deadlines and requirements for equipment maintenance and
operation, including monitoring, recordkeeping, and reporting, to
ensure the enforceability of the BART limits for SO2,
PM10, and NOX.
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    \11\ 77 FR 72512 (December 5, 2012).
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    In addition, the FIP included two requirements that applied to all
affected sources, including Coronado. First, we promulgated a work
practice standard that requires that pollution control equipment be
designed and capable of operating properly to minimize emissions during
all expected operating conditions. Second, we incorporated by reference
into the FIP certain provisions of the Arizona Adminsitrative Code
(AAC) that establish an affirmative defense for excess emissions due to
malfunctions. Please refer to the final rule published on December 5,
2012, for further information on the BART determinations and related
FIP requirements.\12\
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    \12\ Id.
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2. Petition for Reconsideration and Stay of Regional Haze FIP
    The EPA received a petition from SRP on February 4, 2013,
requesting partial reconsideration and an administrative stay of the
final rule under section 307(d)(7)(B) of the CAA and section 705 of the
Administrative Procedure Act.\13\ EPA Region 9 sent a letter on April
9, 2013, to representatives of SRP granting partial reconsideration of
the final rule for the Arizona Regional Haze FIP.\14\ In particular,
the EPA stated that we were granting reconsideration of the compliance
methodology for NOX emissions from Units 1 and 2 at Coronado
and that we would issue a notice of proposed rulemaking seeking comment
on an alternative compliance methodology. We also noted that, because
we initially proposed different NOX emission limits for the
two units, we would seek comment on the appropriate emission limit for
each of the units.
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    \13\ Petition of Salt River Project Agricultural Improvement and
Power District for Partial Reconsideration and Stay of EPA's Final
Rule: ``Approval, Disapproval and Promulgation of Air Quality
Implementation Plans; Arizona; Regional Haze State and Federal
Implementation Plans'' (February 4, 2013).
    \14\ Letters from Jared Blumenfeld, EPA, to Norman W. Fichthorn
and Aaron Flynn, Hunton and Williams (April 9, 2013).
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3. FIP Revision for Coronado
    In response to the petition from SRP, we issued a final FIP
revision on April 13, 2016, replacing the plant-wide compliance method
with a unit-specific compliance method for determining compliance with
the BART emission limits for NOX from Units 1 and 2 at
Coronado (``2016 BART Reconsideration'').\15\ While the plant-wide
limit for NOX emissions from Units 1 and 2 was previously
established as 0.065 lb/MMBtu, through this FIP revision we set a unit-
specific limit of 0.065 lb/MMBtu for Unit 1 and 0.080 lb/MMBtu for Unit
2, to be met by December 5, 2017. We also revised the work practice
standard that applied to Coronado and removed the affirmative defense
for malfunctions that was included in the FIP for Coronado.
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    \15\ 81 FR 21735 (April 13, 2016).
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4. Arizona Regional Haze SIP Revision for Coronado Generating Station
    On December 15, 2016, ADEQ submitted a revision to the Arizona
Regional Haze SIP (``Coronado SIP Revision'') that provides an
alternative to BART for Coronado (``Coronado BART Alternative'').\16\
The Coronado SIP Revision is the subject of this proposal.
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    \16\ Letter from Timothy S. Franquist, Director Air Quality
Division, ADEQ, to Alexis Strauss, Action Regional Administrator,
EPA Region 9 (December 15, 2016). The Coronado SIP Revision includes
both the original version of the revision (dated July 19, 2016) that
was proposed by ADEQ for public comment, and an addendum
(``Addendum'' dated November 10, 2016), in addition to various
supporting materials. The Addendum documents changes to the Coronado
BART Alternative since ADEQ's July 19, 2016 proposal. Unless
otherwise specified, references in this document to the Coronado SIP
Revision include both of these documents, as well as the other
materials included in ADEQ's submittal.
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III. The Coronado SIP Revision

A. Summary of the Coronado SIP Revision

    The Coronado SIP Revision and BART Alternative consists of an
interim operating strategy (``Interim Strategy''), which would be in
effect from December 5, 2017 to December 31, 2025, and a final
operating strategy (``Final Strategy''), which would take effect on
January 1, 2026. The requirements associated with the Interim and Final
Strategies are shown in Table 1 and summarized briefly below.
1. Final Strategy
    The Final Strategy in the Coronado SIP Revision requires
installation of SCR on Unit 1 (``SCR Option'') or the

permanent cessation of operation of Unit 1 (``Shutdown Option'') no
later than December 31, 2025. SRP is required to notify ADEQ and the
EPA of its selection by December 31, 2022. The Final Strategy includes
two additional features: A SO2 emission limit of 0.060 lb/
MMBtu, calculated on a 30-BOD rolling average, which applies to Unit 2
(as well as Unit 1 if it continues operating), and an annual plant-wide
SO2 emissions cap of either 1,970 tons per year (tpy) if
both units continue operating or 1,080 tpy if Unit 1 shuts down.
2. Interim Strategy
    The Interim Strategy includes three different operating options
(designated IS2, IS3, and IS4), each of which requires a period of
seasonal curtailment (i.e., temporary closure) for Unit 1. Each year,
SRP must select and implement one of the three options, based on the
NOX emissions performance of Unit 1 and the SO2
emissions performance of Units 1 and 2 in that year. In particular, by
October 21 of each year, SRP must notify ADEQ and the EPA of its chosen
option for that calendar year (and for January of the following year)
and demonstrate that its NOX and SO2 emissions
for that year (up to the date of the notification) have not already
exceeded the limits associated with that option.\17\ SRP then must
comply with those limits for the remainder of the year (and for January
of the following year) and curtail operation of Unit 1 for the time
period required under that option.\18\ In addition, under each option,
the facility must comply with an annual plant-wide SO2
emissions cap of 1,970 tpy effective in each year beginning in 2018.
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    \17\ See Coronado SIP Revision, Appendix B, Permit No. 64169 as
amended by Significant Revision to operating permit No. 63088
(December 14, 2016), Attachment E, condition D.1.
    \18\ As indicated in Table 1, the first curtailment and last
curtailment periods would be shorter than the periods in between.
Under all three interim strategies, the first curtailment period
would begin December 5, 2017. Under all three interim strategies,
the last curtailment period would end December 31, 2025.

                           Table 1--Summary of Coronado BART Alternative Compared With 2014 Baseline and BART Control Strategy
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                                       Unit 1 (lb/MMBtu) (30-BOD       Unit 2 (lb/MMBtu) (30-BOD
                                               average)                        average)              Annual plant-
         Control strategy          ----------------------------------------------------------------  wide SO2 cap         Unit 1 curtailment period
                                          NOX             SO2             NOX             SO2            (tpy)
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2014 Baseline \a\.................           0.320           0.080           0.080           0.080             N/A  N/A
BART Control Strategy \b\.........           0.065           0.080           0.080           0.080             N/A  N/A
Interim Strategy: \c\
    IS2...........................           0.320           0.060           0.080           0.060           1,970  October 21-January 31
    IS3...........................           0.320           0.050           0.080           0.050           1,970  November 21-January 20
    IS4...........................           0.310           0.060           0.080           0.060           1,970  November 21-January 20
                                   ---------------------------------------------------------------------------------------------------------------------
Interim Strategy Timeline.........                                       Notification date: October 21 of each year
                                                                       Operates December 5, 2017 to December 31, 2025
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Final Strategy:
    SCR Installation..............           0.065           0.060           0.080           0.060           1,970  N/A
    Shutdown......................             N/A             N/A           0.080           0.060           1,080  N/A
                                   ---------------------------------------------------------------------------------------------------------------------
Final Strategy Timeline...........                                          Notification date: December 31, 2022
                                                                    Shutdown or install & operate SCR: December 31, 2025
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\a\ This scenario reflects the requirements of a 2008 consent decree (CD) between the United States and SRP, which include new wet flue gas
  desulfurization (FGD) and Low NOX burners (LNB) with over fire air (OFA) on both units, and SCR on Unit 2. See United States v. Salt River Project
  Agricultural Improvement and Power District, Civil Action No. 2:08-cv-1479-JAT (D. Ariz.) (August 12, 2008).
\b\ 2016 EPA BART Reconsideration for NOX and 2010 ADEQ BART for SO2.
\c\ See Addendum, Page 3, Table 1.

    ADEQ incorporated the revised emission limits, as well as
associated compliance deadlines and monitoring, recordkeeping, and
reporting requirements, as a permit revision to Coronado's existing
Operating Permit, which was submitted as part of the Coronado SIP
Revision (``Coronado Permit Revision'').\19\
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    \19\ Coronado SIP Revision, Appendix B, Permit No. 64169 as
amended by Significant Revision to operating permit No. 63088
(December 14, 2016). The provisions implementing the BART
Alternative are incorporated in Attachment E to the permit.
Attachment E will become effective under State law on the date of
the EPA's final action to approve Attachment E into the Arizona SIP
and rescind the provisions of the Arizona Regional Haze FIP that
apply to Coronado. Id. Attachment E, section I.A.
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    The Coronado SIP Revision also includes ADEQ's determination that
the Coronado BART Alternative is ``better than BART,'' based on a
demonstration that it fulfills the requirements of 40 CFR 51.308(e)(2)
for a BART alternative. More information regarding ADEQ's analysis is
set forth below, along with the EPA's evaluation of the analysis.

B. The EPA's Evaluation of the Coronado BART Alternative.

    The Regional Haze Rule requires that a SIP revision establishing a
BART alternative include three elements, which are listed below. We
have evaluated the Coronado BART Alternative with respect to each of
the following elements:
     A demonstration that the emissions trading program or
other alternative measure will achieve greater reasonable progress than
would have resulted from the installation and operation of BART at all
sources subject to BART in the State and covered by the alternative
program.\20\
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    \20\ 40 CFR 51.308(e)(2)(i).
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     A requirement that all necessary emissions reductions take
place during the period of the first long-term strategy for regional
haze.\21\
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    \21\ 40 CFR 51.308(e)(2)(iii).
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     A demonstration that the emissions reductions resulting
from the 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.\22\
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    \22\ 40 CFR 51.308(e)(2)(iv).
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    1. Demonstration that the alternative measure will achieve greater
reasonable progress.
    Pursuant to 40 CFR 51.308(e)(2)(i), ADEQ must demonstrate that the
alternative measure will achieve greater reasonable progress than would
have resulted from the installation and operation of BART at all
sources subject to BART in the State and covered by the alternative
program. For a source-specific BART alternative, the critical elements
of this demonstration are:

     An analysis of BART and associated emission reductions
\23\
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    \23\ 40 CFR 51.308(e)(2)(i)(C).
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     an analysis of projected emissions reductions achievable
through the BART alternative \24\
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    \24\ 40 CFR 51.308(e)(2)(i)(D).
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     a determination that the alternative achieves greater
reasonable progress than would be achieved through the installation and
operation of BART \25\
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    \25\ 40 CFR 51.308(e)(2)(i)(E).

    We summarize ADEQ's submittal with respect to each of these
elements and provide our evaluation of the submittal below.
a. Analysis of BART and Associated Emission Reductions
    Pursuant to 40 CFR 51.308(e)(2)(i)(C), the SIP must include an
analysis of BART and associated emission reductions at Units 1 and 2.
As noted above, ADEQ's BART analyses and determinations for Units 1 and
2 were included in the Arizona Regional Haze SIP. We approved ADEQ's
BART determinations for PM10 and SO2, but
disapproved ADEQ's BART determination for NOX and conducted
our own BART analysis and determination for NOX BART in the
Arizona Regional Haze FIP. We later revised the NOX emission
limits for Units 1 and 2 in the 2016 BART Reconsideration.\26\
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    \26\ 81 FR 21735 (April 13, 2016).
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    In the Coronado SIP Revision, ADEQ compared the BART Alternative
both to ADEQ's original BART determinations and to the EPA's BART
determinations in the 2016 BART Reconsideration. For purposes of our
evaluation, we consider BART for Coronado to consist of a combination
of (1) ADEQ's BART determinations for PM10 and
SO2, which were approved into the applicable SIP, and (2)
the EPA's BART determination for NOX in the 2016 BART
Reconsideration (collectively the ``Coronado BART Control Strategy'').
The emission limits comprising the Coronado BART Control Strategy are
summarized in Table 2.

                             Table 2--Coronado BART Control Strategy Emission Limits
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                                                                  Emission limits  (lb/MMBtu, averaged over a 30
                                                                              boiler-operating-days)
                              Unit                               -----------------------------------------------
                                                                        NOX            PM10             SO2
----------------------------------------------------------------------------------------------------------------
Unit 1..........................................................           0.065           0.030           0.080
Unit 2..........................................................           0.080           0.030           0.080
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    In the Technical Support Document (TSD) included with the Coronado
SIP Revision,\27\ ADEQ calculated estimated annual emission reductions
achievable with BART by comparing expected annual emissions under the
Coronado BART Control Strategy with 2014 emissions (``2014
Baseline'').\28\ The results of these calculations are summarized in
Table 3. As BART for PM10 and SO2 reflected
existing controls, no emissions reductions of PM10 and
SO2 are expected to result from BART, but significant
reductions of NOX are expected to result from implementation
of BART.
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    \27\ Coronado SIP Revision (July 19, 2016), Appendix A,
``Technical Support Document for Regional Haze State Implementation
Plan Revision for the Salt River Project Coronado Generating
Station.''
    \28\ Id. section 4. As noted above, the 2014 Baseline emissions
reflects the requirements of the 2008 CD between the United States
and SRP, including new FGD and LNB with OFA on both units, and SCR
on Unit 2.

             Table 3--Summary of Emission Reductions Achievable With Coronado BART Control Strategy
                                                      [tpy]
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              Operating strategies                      NOX             SO2            PM10            Total
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2014 Baseline Emissions.........................           6,506           2,651             994          10,151
Coronado BART Control Strategy Emissions........           2,410           2,651             994           6,055
Emission Reductions.............................           4,096               0               0           4,096
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    We propose to find that ADEQ has met the requirement for an
analysis of BART and associated emission reductions achievable at
Coronado under 40 CFR 51.308(e)(2)(i)(C). We note that the Regional
Haze Rule does not specify what baseline year should be used for
calculating emission reductions under 40 CFR 51.308(e)(2)(i)(C).\29\
However, because the purpose of calculating emission reductions
achievable with BART is to compare these reductions to those achievable
through the BART alternative,\30\ it is important that a consistent
baseline be used for both sets of calculations. In this instance,
Arizona used the 2014 Baseline for both purposes, so we find that its
approach was reasonable.
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    \29\ As explained below, the baseline date for regional haze
SIPs is 2002 and, pursuant to 40 CFR 51.308(e)(2)(iv), the emissions
reductions resulting from the alternative measure must be surplus to
those reductions required as of 2002. However, this provision does
not determine what baseline should be used for purposes of
calculating emission reductions achievable under 40 CFR
51.308(e)(2)(i)(C).
    \30\ See, e.g., 71 FR 60612, 60615 (October 13, 2006)(``Today's
final rule revises section 51.308(e)(2) to make clear that the
emissions reductions that could be achieved through implementation
of the BART provisions at section 51.308(e)(1) serve as the
benchmark against which States can compare an alternative
program.'')

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b. Analysis of Projected Emissions Reductions Achievable Through the
BART Alternative
    In the Coronado SIP Revision TSD, ADEQ calculated emissions
reductions achievable under the Interim Strategy by comparing estimated
annual emissions under the Interim Strategy with 2014 Baseline
emissions. In the Addendum to the Coronado SIP Revision, ADEQ also
provided a summary of estimated annual emissions under the Final
Strategy compared to 2014 Baseline emissions. The resulting emission
reductions are shown in Table 4.

               Table 4--Summary of Emission Reductions Achievable With Coronado BART Alternative a
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              Operating strategies                      NOX             SO2             PM             Total
----------------------------------------------------------------------------------------------------------------
Interim Strategy 2 (IS2) \b\
    2014 Baseline Emissions.....................           6,506           2,651             994          10,151
    Interim Strategy IS2 Emissions..............           5,053            2002             858            7913
    Emission Reductions.........................           1,453             649             136           2,238
Interim Strategy 3 (IS3)
    2014 Baseline Emissions.....................           6,506           2,651             994          10,151
    Interim Strategy IS3 Emissions..............           5,667           1,526             915           8,108
    Emission Reductions.........................             839           1,125              79           2,043
Interim Strategy 4 (IS4)
    2014 Baseline Emissions.....................           6,506           2,651             994          10,151
    Interim Strategy IS4 Emissions..............           5,533           1,831             915           8,279
    Emission Reductions.........................             973             820              79           1,872
Final Strategy (SCR Option) \c\
    2014 Baseline Emissions.....................           6,506           2,651             994          10,151
    Final Strategy--SCR Option..................           2,410           1,970             994           5,374
    Emission Reductions.........................           4,096             681               0           4,777
Final Strategy (Shutdown Option) \d\
    2014 Baseline Emissions.....................           6,506           2,651             994          10,151
    Final Strategy--Shutdown Option.............           1,366           1,080             512           2,958
    Emission Reductions.........................           5,140           1,571             482           7,193
----------------------------------------------------------------------------------------------------------------
\a\ ADEQ assumed all scenarios would have the same average heat input rate and same percentage of the annualized
  utilization factor without curtailment. For the interim strategies, ADEQ adjusted the utilization factors to
  reflect the corresponding amount of Unit 1 curtailment required for each option. Since these are adjustments
  to the annual utilization rate for each year, they account for interim strategies that cross calendar years.
\b\ Detailed emission calculations for the 2014 Baseline and Interim Strategy can be found in Tables 2, 3, and 4
  of the Coronado Regional Haze SIP TSD (July 19, 2016).
\c\ See, Coronado SIP Revision Addendum, Table 2 (November 19, 2016).
\d\ Id.

    We propose to find that ADEQ has met the requirement for an
analysis of the projected emissions reductions achievable through the
alternative measure under 40 CFR 51.308(e)(2)(i)(D). As explained in
the previous section, Arizona appropriately used the 2014 Baseline for
calculating emissions reductions achievable with the Coronado BART
Strategy and emissions reductions achievable with the Coronado BART
Alternative.
c. Determination That the Alternative Achieves Greater Reasonable
Progress Than Would Be Achieved Through the Installation and Operation
of BART
    Pursuant to 40 CFR 51.308(e)(2)(i)(E), the State must provide a
determination under 40 CFR 51.308(e)(3) or otherwise based on the clear
weight of evidence that the alternative achieves greater reasonable
progress than BART. Two different tests for determining whether the
alternative achieves greater reasonable progress than BART are outlined
in 40 CFR 51.308(e)(3). If the distribution of emissions is not
substantially different than under BART, and the alternative measure
results in greater emission reductions, then the alternative measure
may be deemed to achieve greater reasonable progress. If the
distribution of emissions is significantly different, then the State
must conduct dispersion modeling to determine differences in visibility
between BART and the trading program for each impacted Class I area for
the worst and best 20 percent days. The modeling would demonstrate
``greater reasonable progress'' if both of the following two criteria
are met: (1) Visibility does not decline in any Class I area; and (2)
there is an overall improvement in visibility, determined by comparing
the average differences between BART and the alternative over all
affected Class I areas. This modeling test is sometimes referred to as
the ``two-prong test.''
    In the Coronado SIP Revision, ADEQ separately analyzed the three
options under the Interim Strategy and the Final Strategy under 40 CFR
51.308(e)(3).\31\
---------------------------------------------------------------------------

    \31\ ADEQ also included a ``Supplemental Analysis of IMPROVE
Monitoring Data'' that it considered relevant to the determination
of whether the Coronado BART Alternative is better than BART. See
Coronado SIP Revision (July 19, 2016) pages 9-10. However, because
the State made a demonstration under 40 CFR 51.308(e)(3), rather
than a ``clear weight of evidence'' demonstration under 40 CFR
51.308(e)(2)(i)(E), these monitoring data are not directly relevant
and we have not considered them in our evaluation of the SIP.
---------------------------------------------------------------------------

i. BART Alternative Interim Strategy
    ADEQ determined that the Interim Strategy will not necessarily
achieve greater emissions reductions than the BART Control Strategy
because, while each option under the Interim Strategy will result in
greater reductions in SO2 and PM10 than the BART
Control Strategy, each option will also result in higher NOX
emissions. Therefore, ADEQ relied on the results of air quality
modeling (using the Comprehensive Air Quality Model with Extensions
(``CAMx'') model) performed by SRP's contractor, Ramboll Environ, to
demonstrate that the Interim Strategy would result in ``greater
reasonable progress'' under the two-prong test in 40 CFR
51.308(e)(3).\32\ CAMx has a scientifically current treatment of
chemistry to simulate the transformation of emissions into visibility-
impairing particles of species such as ammonium nitrate and ammonium
sulfate, and is often employed in large-scale modeling when

many sources of pollution and/or long transport distances are involved.
Photochemical grid models like CAMx include all emissions sources and
have realistic representations of formation, transport, and removal
processes of the particulate matter that causes visibility degradation.
---------------------------------------------------------------------------

    \32\ Coronado SIP Revision (July 19, 2016), pages 6-8.
---------------------------------------------------------------------------

    The Coronado modeling followed a modeling protocol \33\ that was
reviewed by the EPA. The starting point for the modeling was modeling
done as part of the Western Regional Air Partnership's West-side
Jumpstart Air Quality Modeling Study (``WestJump''), which used a 2008
meteorology and emissions base case, and covered the entire western
United States.\34\ For the Coronado modeling work, Ramboll Environ
reduced the modeling domain to an area within 300 kilometers of the
facility and carried out a new model performance evaluation. The
initial and boundary conditions for this domain were taken from
WestJump modeling of sources for the entire western United States. For
the two-prong test, an existing projected 2020 emissions database was
used to estimate emissions of sources in Arizona (other than Coronado)
and New Mexico. The 2020 emissions case is likely to be more
representative of air quality conditions when the Coronado BART Control
Strategy is implemented than the 2008 database. In the 2020 modeling,
the Coronado emissions were set to appropriate levels for the 2014
Baseline, the Coronado BART Control Strategy, and the various Interim
Strategy options, as shown in Table 5. Emission factors for Coronado
for the modeling are identical to the emissions limits for the Coronado
BART Alternative described in Table 1, except that the Interim Strategy
in the Coronado SIP revision includes a more stringent SO2
emission limit of 0.060 lb/MMBtu for IS2 compared to the modeled value
of 0.070 lb/MMBtu. In addition, the modeling does not reflect the
plant-wide SO2 emissions cap of 1,970 tpy included in the
Coronado SIP revision.
---------------------------------------------------------------------------

    \33\ ``Draft Modeling Plan for Conducting Better-than-BART
Analysis for the Coronado Generating Station using a Photochemical
Grid Model--Revision#1'', 06-35855A, Prepared for Salt River
Project, Ramboll Environ US Corporation (August 2015).
    \34\ https://www.wrapair2.org/WestJumpAQMS.aspx.

 Table 5--Emission Factors for SO2 and NOX and Curtailment Periods Used To Model the 2014 Baseline, Coronado BART Control Strategy, and Interim Strategy
                                                                       at Coronado
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                   Unit 1 (lb/MMBtu)               Unit 2 (lb/MMBtu)
             Control strategy              ----------------------------------------------------------------          Unit 1  curtailment period
                                                  NOX             SO2             NOX             SO2
--------------------------------------------------------------------------------------------------------------------------------------------------------
2014 Baseline.............................           0.320           0.080           0.080           0.080  N/A
Coronado BART Control Strategy............           0.065           0.080           0.080           0.080  N/A
Interim Strategy:
    IS2...................................           0.320       \b\ 0.070           0.080       \b\ 0.070  October 21-January 31
    IS3...................................           0.320           0.050           0.080           0.050  November 21-January 20
    IS4...................................           0.310           0.060           0.080           0.060  November 21-January 20
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ As noted above, this scenario reflects 2008 CD controls, which include new wet FGD and LNB with OFA on both units, and SCR on Unit 2.
\b\ Although these emission factors were used for modeling, the final SIP submission adopted a lower SO2 emission limit for IS2 for both Units 1 and 2
  of 0.060 lb/MMBtu.

    The CAMx-modeled concentrations for sulfate, nitrate, and other
chemical species were tracked for Coronado using the CAMx Particulate
Source Apportionment Technology (PSAT) Probing Tool, so that the
concentrations and visibility impacts due to Coronado could be
separated out from those due to the total of all modeled sources. PSAT
provides air quality contributions from the emissions of Coronado in a
single step and avoids the extra work needed in the simple subtraction
approach, which would require additional modeling runs (with and
without Coronado emissions) and a subtraction step to estimate the air
quality contributions of Coronado emissions.
    Ramboll Environ computed visibility impairment due to Coronado
using the Interagency Monitoring of Protected Visual Environments
(IMPROVE) equation,\35\ following a procedure recommended by the
Federal Land Managers.\36\ Ramboll Environ then subtracted the deciview
(dv) \37\ visibility impairment due to natural background
concentrations from the deciview impairment due to the sum of Coronado
and natural background concentrations. This difference gives the
visibility impact or ``delta deciviews'' solely due to Coronado. Thus,
although the CAMx modeled concentrations realistically reflect the
interactions of all sources, the Coronado visibility impacts were
assessed relative to natural conditions, similar to the procedure
followed in BART assessments.\38\
---------------------------------------------------------------------------

    \35\ IMPROVE refers to a monitoring network and also to the
equation used to convert monitored concentrations to visbility
impacts. ``Revised IMPROVE Algorithm for Estimating Light Extinction
from Particle Speciation Data'', IMPROVE technical subcommittee for
algorithm review, January 2006, http://vista.cira.colostate.edu/Improve/gray-literature/.
    \36\ Federal Land Managers' Air Quality Related Values Work
Group (FLAG), Phase I Report--Revised, National Park Service, 2010
    \37\ The Regional Haze Rule establishes the deciview as the
principal metric for measuring visibility. This visibility metric
expresses uniform changes in haziness in terms of common increments
across the entire range of visibility conditions, from pristine to
extremely hazy conditions. Visibility expressed in deciviews is
determined by using air quality measured or modeled concentrations
to estimate light extinction using the IMPROVE, and then
transforming the value of light extinction to deciviews using the
logarithm function.
    \38\ See 40 CFR part 51, appendix Y section IV.D.5 (``Calculate
the model results for each receptor as the change in deciviews
compared against natural visibility conditions.'')
---------------------------------------------------------------------------

    For the first prong of the modeling test, Ramboll Environ computed
the difference between the delta deciviews for each Interim Strategy
option and the delta deciviews for the 2014 Baseline for each Class I
area. Ramboll Environ then averaged these differences over the best 20
percent of days, the worst 20 percent of days, and for the full year.
The results are shown in Table 6 and Table 7. Based on these results,
ADEQ concluded that that the Interim Strategy will result in improved
visibility at all affected Class I areas compared with baseline
conditions on the worst and best 20 percent of days and therefore meets
the first prong of the modeling test in 40 CFR 51.308(e)(3).

                    Table 6--Prong 1 Test--Delta Deciview Differences of Visibility Conditions Between Baseline and Interim Strategy
                                                              [Baseline--Interim Strategy]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                            Average best 20% Days            Average worst 20% Days               Annual average
                     Class I area                     --------------------------------------------------------------------------------------------------
                                                          IS2        IS3        IS4        IS2        IS3        IS4        IS2        IS3        IS4
--------------------------------------------------------------------------------------------------------------------------------------------------------
Bandalier NM.........................................     0.0021     0.0021     0.0020     0.0043     0.0050     0.0043     0.0017     0.0024     0.0019
Bosque...............................................     0.0012     0.0016     0.0015     0.0011     0.0015     0.0013     0.0015     0.0023     0.0018
Chiricahua NM........................................     0.0010     0.0014     0.0012     0.0001     0.0004     0.0003     0.0005     0.0009     0.0007
Chiricahua Wild......................................     0.0011     0.0016     0.0014     0.0001     0.0004     0.0003     0.0006     0.0009     0.0007
Galiuro Wild.........................................     0.0012     0.0016     0.0013     0.0001     0.0004     0.0003     0.0004     0.0007     0.0006
Gila Wild............................................     0.0040     0.0044     0.0040     0.0002     0.0007     0.0005     0.0023     0.0030     0.0025
Grand Canyon NP......................................    0.00002     0.0001    0.00004     0.0003     0.0006     0.0004     0.0009     0.0012     0.0009
Mazatzal Wild........................................     0.0032     0.0025     0.0028     0.0003     0.0008     0.0006     0.0008     0.0010     0.0008
Mesa Verde NP........................................     0.0003     0.0004     0.0004     0.0015     0.0015     0.0011     0.0018     0.0022     0.0017
Mount Baldy Wild.....................................     0.0072     0.0069     0.0070     0.0033     0.0024     0.0017     0.0039     0.0042     0.0035
Petrified Forest NP..................................     0.0021     0.0021     0.0020     0.0027     0.0034     0.0031     0.0078     0.0080     0.0068
Pine Mountain Wild...................................     0.0023     0.0021     0.0023     0.0002     0.0007     0.0004     0.0008     0.0011     0.0009
Saguro NP............................................     0.0004     0.0010     0.0007     0.0002     0.0003     0.0002     0.0004     0.0006     0.0004
San Pedro Parks Wild.................................     0.0023     0.0022     0.0021     0.0040     0.0031     0.0025     0.0024     0.0032     0.0026
Sierra Ancha \a\ Wild................................  .........  .........  .........  .........  .........  .........     0.0015     0.0017     0.0014
Superstition Wild....................................     0.0058     0.0067     0.0060     0.0005     0.0004     0.0003     0.0012     0.0015     0.0013
Sycamore Canyon Wild.................................     0.0003     0.0008     0.0004     0.0006     0.0008     0.0006     0.0007     0.0013     0.0009
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ The IMPROVE visibility database has missing data for some key dates, so best and worst 20 percent of days could not be estimated for the Sierra
  Ancha area.

   Table 7--Minimum Delta Deciview Differences Among Affected Class I Areas Between Interim Strategy and Baseline at Class I Areas (Baseline--Interim
                                                                       Strategy) a
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                               Average best 20% days          Average worst 20% days              Annual average
               Interim operating strategy                -----------------------------------------------------------------------------------------------
                                                           Absolute (dv)   Relative (%)    Absolute (dv)   Relative (%)    Absolute (dv)   Relative (%)
--------------------------------------------------------------------------------------------------------------------------------------------------------
IS2.....................................................         0.00002            3.65          0.0001            7.30          0.0004           13.75
IS3.....................................................         0.00010           11.55          0.0003           13.67          0.0006           18.73
IS4.....................................................         0.00004            6.06          0.0002            9.86          0.0004           15.36
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Coronado SIP Revision (July 19, 2016), Table 2. The selection of the Class I area with the minimum value (least incremental benefit from the
  Alternative Strategy compared to BART) was based on the absolute deciview levels. The relative difference for that Class I area is shown for
  informational purposes also.

    For the second prong of the modeling test, Ramboll Environ computed
the difference between the delta deciviews for each Interim Strategy
option and the delta deciviews for the Coronado BART Control Strategy.
Ramboll Environ then compared the average differences between the
Coronado BART Control Strategy and the Interim Strategy over all
affected Class I areas to ensure that there is an overall improvement
in visibility. Based on these modeling results, as shown in Table 8,
ADEQ concluded that the Interim Strategy also meets this prong, as
these results indicate that the Interim Strategy would result in
improved visibility, on average, across all Class I Areas, compared
with the Coronado BART Control Strategy on the worst and best 20
percent of days.\39\
---------------------------------------------------------------------------

    \39\ Although not required under 40 CFR 51.308(e)(3), SRP and
ADEQ included annual average modeling results, which also show a
greater improvement in visibility on average across all affected
Class I areas under the Interim Strategy.

         Table 8--Prong 2 Test--Delta Deciview Differences of Visibility Conditions Between Coronado BART Control Strategy and Interim Strategy
                                                               [BART-Interim Strategy] \a\
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                            Average best 20% days            Average worst 20% days               Annual average
                     Class I area                     --------------------------------------------------------------------------------------------------
                                                          IS2        IS3        IS4        IS2        IS3        IS4        IS2        IS3        IS4
--------------------------------------------------------------------------------------------------------------------------------------------------------
Bandalier NM.........................................     0.0009     0.0009     0.0008     0.0011     0.0018     0.0011    -0.0001     0.0005     0.0001
Bosque...............................................     0.0001     0.0005     0.0003     0.0001     0.0006     0.0004    -0.0003     0.0004    -0.0001
Chiricahua NM........................................    -0.0011    -0.0007    -0.0009     0.0000     0.0002     0.0001    -0.0002     0.0001    -0.0001
Chiricahua Wild......................................    -0.0011    -0.0006    -0.0009     0.0000     0.0003     0.0001    -0.0002     0.0002    -0.0001
Galiuro Wild.........................................     0.0003     0.0006     0.0004    -0.0001     0.0002     0.0000    -0.0001     0.0002     0.0000
Gila Wild............................................     0.0009     0.0013     0.0009    -0.0001     0.0003     0.0001    -0.0004     0.0003    -0.0002
Grand Canyon NP......................................    -0.0001    -0.0001    -0.0001    -0.0003     0.0000    -0.0001     0.0003     0.0007     0.0004
Mazatzal Wild........................................    -0.0009    -0.0015    -0.0012    -0.0004     0.0002    -0.0001    -0.0001     0.0001    -0.0001
Mesa Verde NP........................................     0.0001     0.0002     0.0002     0.0008     0.0008     0.0003     0.0011     0.0016     0.0010
Mount Baldy Wild.....................................     0.0034     0.0030     0.0032    -0.0003    -0.0012    -0.0018    -0.0012    -0.0008    -0.0016
Petrified Forest NP..................................     0.0015     0.0015     0.0013    -0.0004     0.0004     0.0000     0.0018     0.0020     0.0008
Pine Mountain Wild...................................    -0.0007    -0.0009    -0.0007     0.0000     0.0004     0.0002     0.0001     0.0003     0.0001
Saguro NP............................................    -0.0003     0.0003     0.0000     0.0000     0.0002     0.0001     0.0000     0.0003     0.0001

San Pedro Parks Wild.................................     0.0003     0.0002     0.0002     0.0013     0.0004    -0.0002    -0.0003     0.0005    -0.0001
Sierra Ancha Wild \b\................................  .........  .........  .........  .........  .........  .........     0.0003     0.0005     0.0002
Superstition Wild....................................     0.0018     0.0027     0.0020    -0.0001    -0.0001    -0.0003     0.0003     0.0006     0.0003
Sycamore Canyon Wild.................................    -0.0013    -0.0008    -0.0012     0.0001     0.0003     0.0001     0.0002     0.0007     0.0004
    Average..........................................     0.0002     0.0004     0.0003     0.0001     0.0003    0.00001     0.0001     0.0005     0.0001
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Coronado SIP Revision TSD Table 18.
\b\ The IMPROVE visibility database has missing data for some key dates, so best and worst 20% of days could not be estimated for the Sierra Ancha area.

    We have reviewed the modeling analysis performed by Ramboll Environ
and submitted by ADEQ and find that it supports ADEQ's determination
that the Interim Strategy would achieve greater reasonable progress
than BART under 40 CFR 51.308(e)(3). In particular, we have evaluated
the Coronado modeling to confirm that, even though the numerical
differences between the scenarios under the two-prong test are small,
the results represent real visibility differences and not just the
result of numerical artifacts or ``noise'' in the model results. As
noted above, the modeling used the CAMx PSAT Probing Tool to track
concentrations for sulfate, nitrate, and other chemical species in
order to separate out visibility impacts due to Coronado from those of
other modeled sources. This PSAT-based approach helps to avoids
numerical artifacts in the model results, as compared to the simple
subtraction approach, and thus provides assurance that the relatively
small numerical values in the modeled differences represent real
visibility differences.
    In response to a request from the EPA, ADEQ submitted an additional
analysis performed by Ramboll Environ to demonstrate that the modeled
numerical differences represent real visibility improvements and are
not just numerical artifacts.\40\ This analysis presented spatial plots
of the modeled numerical differences in delta deciviews, for days on
which Coronado had the highest delta-deciview impacts at Superstition
Wilderness and Mount Baldy Wilderness, the Class I areas for which
Coronado had the highest delta deciview impacts on the best and worst
20 percent of days, respectively. There were plots for deciviews
computed using all pollutant species, with separate plots for sulfate
and nitrate individually, the chemical products of SO2 and
NOX precursor emissions, respectively. The plots display
differences for each grid square of the modeling domain, color-coded by
the magnitude of the delta deciview difference. If the differences
between the modeled control scenarios were merely numerical artifacts
or ``noise,'' they would manifest as random dots of different colors on
these plots. Instead, the plots show smoothly changing areas of color,
as would be expected in the real atmosphere as conditions vary
continuously over the area. In most cases there is a clearly
distuiguishable ``plume'' from Coronado, representing the improvement
from the Interim Strategy relative to the Coronado BART Control
Strategy at locations where Coronado has an impact.
---------------------------------------------------------------------------

    \40\ Coronado SIP Revision, Appendix D.5 Responsiveness Summary,
Appendix A: Memorandum SRP Submitted to ADEQ Regarding Numerical
Noise Issues Associated with CAMx Modeling: ``To address the EPA
comment regarding whether the CGS Better-than-BART CAMx analysis is
influenced by numerical `noise', Memorandum from Lynsey Parker and
Ralph Morris, Ramboll Environ, September 22, 2016.
---------------------------------------------------------------------------

    The only plot that shows numerical noise is for a day when an
Interim Strategy option and the Coronado BART Control Strategy had the
same emissions. For such days, modeled differences would be expected to
be zero, except for the effect of numerical noise. This one plot shows
some random variation in color in some locations, and also shows that
the range of variation is very small, one millionth (10-6)
of a deciview or less, which suggests that the maximum numerical
artifact is approximately 10-6 dv. The smallest deciview
difference seen in the prong 2 test was 0.00001 (10-5)
dv,\41\ which is ten times as large as the estimated 10-6 dv
maximum numerical artifact. This analysis provides additional evidence
that the two test prong results are not just the result of model
``noise,'' but rather indicate actual visibility improvement under the
Interim Strategy compared to the Coronado BART Control Strategy and no
degradation relative to Baseline.
---------------------------------------------------------------------------

    \41\ See Table 8, average across all Class I areas for average
worst 20% days under IS4.
---------------------------------------------------------------------------

    We also note that the modeling demonstration was done with a higher
emission rate for SO2 for both Units 1 and 2 for scenario
IS2 and without the facility-wide SO2 emissions cap that was
included in the final SIP revision. When these restrictions on
SO2 emissions are considered, they will result in additional
improvements in visibility under the Interim Strategy, as compared with
the modeling results.
    Finally, we note that 40 CFR 51.308(e)(3) does not specify a
minimum delta deciview difference between the modeled scenarios that
must be achieved in order for a BART alternative to be deemed to
achieve greater reasonable progress than BART. Rather, it allows for a
straight numerical test, regardless of the magnitude of the computed
differences. Accordingly, given that the modeling results submitted by
ADEQ show that the Interim Strategy will result in improved visibility
at all affected Class I areas compared with 2014 Baseline Emissions
(prong 1) and will result in improved visibility, on average, across
all Class I areas, compared with the Coronado BART Control Strategy
(prong 2), we propose to find that ADEQ has demonstrated that the
Interim Strategy will achieve greater reasonable progress than BART
under the two-prong modeling test in 40 CFR 51.308(e)(3).
ii. BART Alternative Final Strategy
    With respect to the Final Strategy, ADEQ did not conduct modeling
but did provide a summary of expected emissions under the Final
Strategy, as compared with the Coronado BART Control Strategy, as shown
in Table 9. ADEQ explained that emissions of NOX and
PM10 would be equivalent under the SCR Option and the
Coronado BART Control Strategy, but emissions of SO2 would
be lower under the Final Strategy than under the Coronado BART Control
Strategy. \42\ The Shutdown Option would result in greater emission
reductions for all three visibility-impairing pollutants (i.e.,
SO2, NOX,

and PM) compared with the Coronado BART Control Strategy.
---------------------------------------------------------------------------

    \42\ Addendum to the Coronado SIP Revision, page 5, section
3.1.2.

                    Table 9--Estimated Emissions for NOX, PM, and SO2 Under the Coronado BART Control Strategy and the Final Strategy
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                        SO2                             NOX                             PM
                                                         -----------------------------------------------------------------------------------------------
                                                                             Combined                        Combined                        Combined
             Scenario                       Unit              Annual       emissions of       Annual       emissions of       Annual       emissions of
                                                             emissions      unit 1 and       emissions      unit 1 and       emissions      unit 1 and
                                                               (tpy)       unit 2 (tpy)        (tpy)       unit 2 (tpy)        (tpy)       unit 2 (tpy)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Coronado BART Control Strategy....  Unit 1..............           1,285           2,651           1,044           2,410             482             994
                                    Unit 2..............           1,366                           1,366                             512
Final Strategy--SCR...............  Unit 1..............             964       \a\ 1,970           1,044           2,410             482             994
                                    Unit 2..............           1,025                           1,366                             512
Final Strategy--Shutdown..........  Unit 1..............               0       \a\ 1,080               0           1,366               0             512
                                    Unit 2..............           1,025                           1,366                             512
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ annual emission cap.

    The emission reductions associated with the Final Strategy will
occur after 2018, which, as explained below, is the deadline for
achieving all necessary emissions reduction under a BART alternative.
Therefore, the Final Strategy by itself clearly would not meet the
requirements for a BART alternative. Nevertheless, in order to ensure
that the Coronado BART Alternative as a whole will result in greater
reasonable progress than BART, we have considered whether the Final
Strategy, once it is implemented, will provide for ongoing visibility
improvement, as compared with the BART Control Strategy. In particular,
we have evaluated whether the Final Strategy meets both criteria of the
greater-emissions-reduction test under 40 CFR 51.308(e)(3), i.e., that
the distribution of emissions under the alternative measure is not
substantially different than under BART and that the alternative
measure results in greater emission reductions than BART. Because all
emissions under both the Coronado BART Control Strategy and the Final
Strategy are from Coronado, it is clear that the distribution of
emissions is not substantially different under the two strategies.
Furthermore, because both the SCR Option and the Shutdown Option would
provide for an aggregate reduction in visibility-impairing pollutants
and no increases in any single pollutant, as compared with the Coronado
BART Control Strategy, we conclude that the Final Strategy will result
in greater emission reductions than the Coronado BART Control Strategy.
Therefore, we propose to find that implementation of the Final Strategy
will ensure that the Coronado BART Alternative will continue to achieve
greater reasonable progress than the BART Control Strategy after 2025.
    In summary, we propose to find that ADEQ has demonstrated that the
Interim Strategy will achieve greater reasonable progress than the
Coronado BART Control Strategy through 2025 and that the Final Strategy
will ensure greater reasonable progress after 2025. Therefore, we
propose to find that ADEQ properly determined under 40 CFR
51.308(e)(2)(i)(E) that the Coronado BART Alternative will achieve
greater reasonable progress than would be achieved through the
installation and operation of BART at Coronado.
    2. Requirement that all necessary emission reductions take place
during period of first long-term strategy.
    Pursuant to 40 CFR 51.308(e)(2)(iii), the State must ensure that
all necessary emission reductions take place during the period of the
first long-term strategy for regional haze, i.e., by December 31, 2018.
The Regional Haze Rule further provides that, to meet this requirement,
the State must provide a detailed description of the alternative
measure, including schedules for implementation, the emission
reductions required by the program, all necessary administrative and
technical procedures for implementing the program, rules for accounting
and monitoring emissions, and procedures for enforcement.\43\
---------------------------------------------------------------------------

    \43\ 40 CFR 51.308(e)(2)(iii).
---------------------------------------------------------------------------

    As noted above, the Coronado SIP Revision incorporates the Coronado
Permit Revision, which includes conditions implementing both the
Interim and Final Strategies. In addition to the emission limitations
for NOX, PM10, and SO2 listed in Table
1 above, the Coronado Permit Revision includes compliance dates,
operation and maintenance requirements, and monitoring, recordkeeping,
and reporting requirements.
    The compliance date for the Interim Strategy in the Coronado Permit
Revision is December 5, 2017. Accordingly, the Coronado SIP Revision
ensures that all emission reductions associated with the Interim
Strategy will occur by December 31, 2018 and, as explained before,
those emissions reductions by themselves are sufficient to ensure
greater reasonable progress under the two-prong modeling test under 40
CFR 51.308(e)(3). While the compliance dates for the Final Strategy in
the Coronado Permit Revision are later than December 31, 2018, the
Final Strategy and its associated emission reductions are not necessary
to demonstrate that the Coronado BART Alternative will achieve greater
reasonable progress than BART during the period of the first long-term
strategy. Rather, as stated before, the Final Strategy and its
associated emissions reductions will ensure that the Coronado BART
Alternative will continue to achieve greater reasonable progress than
the BART Control Strategy after 2025. Therefore, we propose to find
that the Coronado SIP Revision will ensure that all necessary emission
reductions take place during the period of the first long-term strategy
and therefore meets the requirements of 40 CFR 51.308(e)(2)(iii).
    3. Demonstration that emissions reductions from alternative measure
will be surplus.
    Pursuant to 40 CFR 51.308(e)(2)(iv), the SIP must demonstrate that
the emissions reductions resulting from the 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. The
baseline date for regional haze

SIPs is 2002.\44\ As noted by ADEQ, all of the emission reductions
required by the Coronado BART Alternative are surplus to reductions
resulting from measures applicable to Coronado as of 2002.\45\
Therefore, we propose to find that the Coronado BART Alternative
complies with 40 CFR 51.308(e)(2)(iv).
---------------------------------------------------------------------------

    \44\ See Memorandum from Lydia Wegman and Peter Tsirigotis, 2002
Base Year Emission Inventory SIP Planning: 8-hr Ozone,
PM2.5, and Regional Haze Programs, November 8, 2002.
https://www3.epa.gov/ttn/naaqs/aqmguide/collection/cp2/20021118_wegman_2002_base_year_emission_sip_planning.pdf.
    \45\ Id., page 9, section 2.3.5.
---------------------------------------------------------------------------

    In sum, we propose to find that the Coronado BART Alternative meets
all of the applicable requirements of 40 CFR 51.308(e)(2).

C. The EPA's Evaluation of Other Applicable Requirements

1. Enforceable Emission Limits
    CAA section 110(a)(2)(A) requires SIPs to include enforceable
emissions limitations as necessary or appropriate to meet the
applicable requirements of the CAA. In order to be considered
enforceable, emission limits must include associated monitoring,
recordkeeping, and reporting requirements. In addition, the CAA and the
EPA's implementing regulations expressly require SIPs to include
regulatory requirements related to monitoring, recordkeeping, and
reporting for applicable emissions limitations.\46\ We have reviewed
the Coronado Permit Revision and found that it includes the appropriate
NOX, SO2, and PM10 emission limits for
the BART Alternative, as well as the associated monitoring,
recordkeeping, and reporting requirements.\47\ Therefore, we propose to
find that the Coronado SIP Revision meets the requirements of the CAA
and the EPA's implementing regulations for enforceable emission
limitations.
---------------------------------------------------------------------------

    \46\ See, e.g., CAA section 110(a)(2)(F) and 40 CFR 51.212(c).
    \47\ The spreadsheet titled ``FIP Requirement comparison.xlsx''
in the docket for this action compares the requirements for Coronado
in the Arizona Regional Haze FIP and the parallel requirements in
the Coronado Permit Revision.
---------------------------------------------------------------------------

2. Non-Interference With Applicable Requirements
    The CAA requires that any revision to an implementation plan shall
not be approved by the Administrator if the revision would interfere
with any applicable requirement concerning attainment and reasonable
further progress (RFP) or any other applicable requirement of the
CAA.\48\ The EPA has promulgated health-based standards, known as the
national ambient air quality standards (NAAQS), for six common
pollutants: PM, ozone, carbon monoxide (CO), SO2, nitrogen
dioxide (NO2), and lead (Pb). Using a process that considers
air quality data and other factors, the EPA designates an area as
``nonattainment'' if the area does not meet the NAAQS or contributes to
violations of a NAAQS in a nearby area. RFP, as defined in section 171
of the CAA, is related to attainment of the NAAQS and means annual
incremental reductions in emissions of the relevant air pollutant(s)
for the purpose of ensuring timely attainment of the applicable NAAQS.
---------------------------------------------------------------------------

    \48\ CAA Section 110(l), 42 U.S.C. 7410(l).
---------------------------------------------------------------------------

    The Coronado SIP Revision includes a demonstration of ``non-
interference'' under CAA section 110(l).\49\ In particular, ADEQ
considered whether the Coronado SIP Revision would interfere with any
applicable requirement concerning attainment or RFP, or any other
applicable requirement of the CAA. A summary of ADEQ's analysis and our
evaluation of that analysis follows.
---------------------------------------------------------------------------

    \49\ Coronado SIP Revision (July 19, 2016) pages 10-15 and
Addendum pages 6-7.
---------------------------------------------------------------------------

a. Demonstration of Non-Interference With NAAQS Attainment and RFP
Requirements
    ADEQ noted that Coronado is located near St. Johns, Arizona in
Apache County, which is designated as ``in attainment,''
``unclassifiable/attainment,'' or ``unclassifiable'' for the following
NAAQS: CO, Pb, NO2, ozone (2008 NAAQS), PM2.5
(1997, 2006, and 2012 NAAQS), PM10, and SO2 (1971
NAAQS). ADEQ also noted that it has recommended an attainment/
unclassifiable designation for this area for the 2010 SO2
NAAQS, but the area has not yet been designated. The state has also
recommended an attainment/unclassifiable designation as part of the
ongoing designations process for the 2015 ozone NAAQS, but the area
does not have a final designation.\50\ ADEQ's demonstration of non-
interference with attainment focused on the NAAQS for PM2.5,
PM10, SO2, NO2, and ozone because
ambient levels of these pollutants are affected by emissions of
PM10, SO2, and/or NOX, which are the
pollutants of concern from Coronado.
---------------------------------------------------------------------------

    \50\ Coronado SIP Revision (July 19, 2016), Table 5, page 12.
ADEQ has also recommended that Apache County be designated as
attainment/unclassifiable for the 2015 ozone NAAQS. See Letter from
Douglas Ducey, Arizona, to Alexis Strauss, EPA (September 27, 2016).
---------------------------------------------------------------------------

    With repect to the PM2.5 and PM10 NAAQS, ADEQ
noted that the curtailment periods under the Interim Strategy would
result in additional PM2.5 and PM10 reductions
beyond those currently required in the Arizona Regional Haze SIP. With
respect to the Final Strategy, ADEQ explained that, while the Shutdown
Option would significantly reduce facility-wide PM emissions compared
to the Coronado BART Control Strategy, the SCR Option would result in
increases in emissions of sulfuric acid mist
(H2SO4) and thus emissions of PM10 and
primary PM2.5 once the SCR is installed. Nonetheless, citing
the TSD for the Coronado Permit Revision, ADEQ explained that ``the
dispersion modeling analysis indicates that these emissions increases
will comply with the NAAQS for PM10 and PM2.5''
and that ``both options would achieve significant emission reductions
of SO2 and NOX . . . , which is an effective
strategy for reducing secondary PM2.5 formation.'' Given
that no nonattainment or maintenance SIPs rely on emission reductions
at Coronado to ensure continued attainment of the PM10 and
PM2.5 NAAQS, ADEQ concluded that the Coronado BART
Alternative will not result in any interference with attainment or
maintenance of the PM10 and PM2.5 NAAQS or with
RFP requirements for these NAAQS.
    We concur with ADEQ's demonstration of non-interference with the
PM10 and PM2.5 NAAQS attainment, maintenance, and
RFP requirements. The area where Coronado is located is designated
unclassifiable/attainment or unclassifiable for each of the
PM10 and PM2.5 NAAQS, so there are no
nonattainment or maintenance SIPs or FIPs that rely on emission
reductions at Coronado to ensure attainment of the PM10 and
PM2.5 NAAQS. Under the Interim Strategy and the Shutdown
Option of the Final Strategy, the Coronado BART Alternative will result
in greater reductions of PM10 and PM2.5 than
would otherwise be required under the applicable implementation plan
for Arizona (including both the PM10 emission limits for
Coronado in the approved Arizona Regional Haze SIP and the associated
monitoring, recordkeeping and reporting requirements in the Arizona
Regional Haze FIP). While the SCR Option under the Final Strategy would
allow for a small increase (compared to existing SIP and FIP
requirements) in emissions of PM10 and primary
PM2.5 when the SCR is installed, we find that ADEQ has
demonstrated that these increases will not result in any interference
with attainment or maintenance of the PM10 and
PM2.5 NAAQS or with RFP requirements for these NAAQS.
    With respect to the SO2 NAAQS, ADEQ determined that all
options under

the Interim Strategy and the Final Strategy would result in
SO2 emissions that are equal to or lower than allowed under
the Arizona Regional Haze SIP. Given that no nonattainment or
maintenance SIPs rely on emission reductions at Coronado to ensure
continued attainment of the SO2 NAAQS, ADEQ concluded that
the Coronado BART Alternative will not result in any interference with
attainment or maintenance of the SO2 NAAQS or with RFP
requirements.
    We concur with ADEQ's demonstration of non-interference with the
SO2 NAAQS attainment, maintenance, and RFP requirements. The
area where Coronado is located has not yet been designated under the
2010 SO2 NAAQS, so there are no nonattainment or maintenance
SIPs or FIPs that rely on emission reductions at Coronado to ensure
attainment of the SO2 NAAQS. Furthermore, during both the
Interim Strategy and the Final Strategy, implementation of the Coronado
BART Alternative will result in greater SO2 reductions than
would otherwise be required under the applicable implementation plan
for Arizona (including both the SO2 emission limits for
Coronado in the approved Arizona Regional Haze SIP and the associated
monitoring, recordkeeping and reporting requirements in the Arizona
Regional Haze FIP). Therefore, it is clear that the implementation of
the Coronado BART Alternative will not result in any interference with
attainment or maintenance of the SO2 NAAQS or with RFP
requirements for the SO2 NAAQS.
    With respect to the NO2 and ozone NAAQS, ADEQ noted that
both the Interim Strategy and the Final Strategy would require
additional NOX reductions beyond those required in the
Arizona Regional Haze SIP, but that the Interim Strategy would require
fewer NOX reductions than the Arizona Regional Haze FIP.
Nonetheless, ADEQ explained that Apache County does not rely on the
Arizona Regional Haze FIP to ensure continued attainment of the
NO2 and ozone NAAQS or to meet any RFP requirements and that
facility-wide emissions of NOX at Coronado will continue to
be reduced under the Coronado BART Alternative compared to current
levels. Therefore, ADEQ concluded that the BART Alternative will not
result in any interference with attainment or maintenance of the
NO2 or ozone NAAQS or with RFP requirements for these NAAQS.
    We concur with ADEQ's demonstration of non-interference with the
NO2 and ozone NAAQS attainment, maintenance, and RFP
requirements. Coronado is located in an area that is designated
unclassifiable/attainment for the NO2 NAAQS and the 2008
ozone NAAQS and has not yet been designated for the 2015 ozone NAAQS,
so there are no nonattainment or maintenance SIPs or FIPs that rely on
emission limitations at Coronado to satisfy any attainment or RFP
requirements for ozone or NO2. Acordingly, while the
Coronado SIP Revision requires fewer NOX reductions than the
Arizona Regional Haze FIP between December 5, 2017 and December 31,
2025, these additional reductions are not necessary for purposes of
attainment and maintenance of the NAAQS or for RFP.
    In summary, because the Coronado SIP Revision will require
equivalent or lower emissions of NOX, PM and SO2
for all future years, compared to the emission levels currently allowed
under the applicable implementation plan (including both the Arizona
Regional Haze SIP and the Arizona Regional Haze FIP), in an area that
is designated in attainment, unclassifiable/attainment, or
unclassifiable, or has not yet been designated for all NAAQS, we
propose to find that the Coronado SIP Revision would not interfere with
any applicable requirements concerning attainment or RFP.
b. Demonstration of Non-Interference With Other CAA Requirements
    ADEQ explained that the following ``other applicable requirements''
are potentially relevant to the Coronado SIP Revision:

 Regional Haze under sections 169A and 169B of the CAA
 Prevention of Significant Deterioration (PSD)
 Maximum Achievable Control Technology (MACT) for Air Toxics
 New Source Performance Standards (NSPS)

    With respect to PSD, ADEQ referred to the TSD for the Coronado
Permit Revision,\51\ which provides ADEQ's best available control
technology determination for H2SO4,
PM10, and PM2.5, as well as NAAQS and PSD
increment modeling for PM10 and PM2.5. We concur
with ADEQ that the documentation for the Coronado Permit Revision
establishes that the Coronado SIP Revision would not interefere with
the PSD requirements of the CAA. Furthermore, implementation of the
Coronado BART Alternative would not affect compliance with the
applicable MACT or NSPS requirements. Therefore, we propose to find
that the Coronado SIP Revision would not interfere with these
requirements.
---------------------------------------------------------------------------

    \51\ Coronado Permit Revision, Appendix C.
---------------------------------------------------------------------------

    With respect to Regional Haze requirements, ADEQ noted that during
implementation of both the Interim Strategy and the Final Strategy, the
Coronado BART Alternative will result in greater reasonable progress
towards natural visibility conditions than the Coronado BART Control
Strategy. For the reasons explained above, we agree that ADEQ has
demonstrated that the Coronado BART Alternative would result in greater
reasonable progress than the Coronado BART Control Strategy. Therefore,
we propose to find that the Coronado SIP Revision would not interfere
with the visibility protection requirements of the CAA.
    Finally, although not expressly addressed by the State in its
submittal, we have considered whether the curtailment requirements
under the Interim Strategy in the Coronado SIP Revision would
interefere with the requirements of CAA section 123 concerning
dispersion techniques. Section 123 provides that the degree of emission
limitation required by a SIP may not be affected by ``any other
dispersion technique,'' which is defined to include ``intermittent or
supplemental control of air pollutants varying with atmospheric
conditions.'' \52\ The EPA's implementing regulations for CAA section
123 define ``intermittent control system'' as ``a dispersion technique
which varies the rate at which pollutants are emitted to the atmosphere
according to meteorological conditions and/or ambient concentrations of
the pollutant, in order to prevent ground-level concentrations in
excess of applicable ambient air quality standards.'' \53\ The
curtailment periods in the Interim Strategy do not allow for varied
emission rates according to meteorological conditions and/or ambient
concentrations of the pollutant. Rather, the curtailment period for
each year is selected based on recent and expected emission control
performance, regardless of meteorological conditions and ambient
pollutant concentrations. In addition, the curtailment periods are not
intended to prevent violations of ambient air quality standards.
Therefore, we propose to find the curtailment requirements comply with
CAA Section 123.
---------------------------------------------------------------------------

    \52\ 42 U.S.C. 7423(a) and (b).
    \53\ 40 CFR 51.100(nn).
---------------------------------------------------------------------------

    In summary, we propose to find that that the Coronado SIP Revision
would not interfere with any applicable requirements of the CAA.

IV. The EPA's Proposed Action

    For the reasons described above, the EPA proposes to approve the
Coronado SIP Revision into the Arizona SIP. Because this approval would
fill the gap in the Arizona Regional Haze SIP left by the EPA's prior
partial disapproval with respect to Coronado, we also propose to
withdraw the provisions of the Arizona Regional Haze FIP that apply to
Coronado. Finally, we are proposing revisions to 40 CFR part 52 to
codify the removal of those portions of the Arizona Regional Haze SIP
that have either been superseded by previously approved revisions to
the Arizona SIP or would be superseded by final approval of the
Coronado SIP Revision.

V. Environmental Justice Considerations

    As explained above, the Coronado SIP Revision will result in
reduced emissions of both SO2 and PM10 compared
to the existing Arizona Regional Haze SIP and FIP requirements. While
the Coronado SIP Revision will result in fewer NOX
reductions than the Arizona Regional Haze FIP would have required
between 2018 and 2025, it will ensure that NOX emissions
remain at or below current levels until 2025, after which it will
require NOX emissions reductions equivalent to or greater
than would have been required under the Arizona Regional Haze FIP.
Furthermore, Coronado is located in area that is designated attainment,
unclassifiable/attainment, or unclassifiable, or has not yet been
designated for each of the current NAAQS. Therefore, the EPA believes
that this action will not have potential disproportionately high and
adverse human health or environmental effects on minority, low-income,
or indigenous populations.

VI. Incorporation by Reference

    In this rule, the EPA is proposing to include in a final EPA rule
regulatory text that includes incorporation by reference. In accordance
with requirements of 1 CFR 51.5, the EPA is proposing to incorporate by
reference the state permit provisions described in the proposed
amendments to 40 CFR part 52 set forth below. The EPA has made, and
will continue to make, this document available electronically through
www.regulations.gov and in hard copy at U.S. Environmental Protection
Agency, Region IX, AIR-2, 75 Hawthorne Street, San Francisco, CA,
94105-3901.

VII. Statutory and Executive Order Reviews

    Additional information about these statutes and Executive Orders
can be found at http://www2.epa.gov/laws-regulations/laws-and-executive-orders.

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 and was
therefore not submitted to the Office of Management and Budget (OMB)
for review. This rule applies to only a single facility and is
therefore not a rule of general applicability.

B. Paperwork Reduction Act (PRA)

    This action does not impose an information collection burden under
the PRA. This rule applies to only a single facility. Therefore, its
recordkeeping and reporting provisions do not constitute a ``collection
of information'' as defined under 44 U.S.C. 3502(3) and 5 CFR
1320.3(c).

C. Regulatory Flexibility Act (RFA)

    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. Firms
primarily engaged in the generation, transmission, and/or distribution
of electric energy for sale are small if, including affiliates, the
total electric output for the preceding fiscal year did not exceed 4
million megawatt hours. The owner of facility affected by this rule,
SRP, exceeds this threshold.

D. 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.

E. 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.

F. 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
any Indian tribes, on the relationship between the federal government
and Indian tribes, or on the distribution of power and responsibilities
between the federal government and Indian tribes. Thus, Executive Order
13175 does not apply to this action.

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

    The EPA interprets Executive Order 13045 as applying only to those
regulatory actions that concern 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.

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

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

I. National Technology Transfer and Advancement Act

    This rulemaking does not involve technical standards. The EPA is
not revising any technical standards or imposing any new technical
standards in this action.

J. 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 section V above.

K. Determination Under Section 307(d)

    Pursuant to CAA section 307(d)(1)(B), the EPA proposes to determine
that this action is subject to the provisions of section 307(d).
Section 307(d) establishes procedural requirements specific to certain
rulemaking actions under the CAA. Pursuant to CAA section 307(d)(1)(B),
the withdrawal of the provisions of the Arizona Regional Haze FIP that
apply to Coronado is subject to the requirements of CAA section 307(d),
as it constitutes a revision to a FIP under CAA section 110(c).
Furthermore, CAA section

307(d)(1)(V) provides that the provisions of section 307(d) apply to
``such other actions as the Administrator may determine.'' The EPA
proposes that the provisions of 307(d) apply to the EPA's action on the
Coronado SIP revision.

List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Carbon monoxide,
Incorporation by reference, Intergovernmental relations, Lead, Nitrogen
dioxide, Ozone, Particulate matter, Reporting and recordkeeping
requirements, Sulfur dioxide, Visibility.

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

    Dated: April 20, 2017.
Alexis Strauss,
Acting Regional Administrator, EPA Region IX.

    For the reasons set forth in the preamble, the EPA proposes to
amend 40 CFR part 52 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 D--Arizona

0
2. Section 52.120 is amended by:
0
a. Adding in paragraph (d), under the table heading ``EPA-Approved
Source-Specific Requirements'' an entry for ``Coronado Generating
Station'' after the entry for ``Cholla Power Plant;''
0
b. Adding in paragraph (e), under the table heading ``Table 1-EPA-
Approved Non-Regulatory and Quasi-Regulatory Measures'' an entry for
``Arizona State Implementation Plan Revision to the Arizona Regional
Haze Plan for the Salt River Project Coronado Generating Station,
excluding Appendix B'' after the entry for ``Arizona State
Implementation Plan Revision to the Arizona Regional Haze Plan for
Arizona Public Service Cholla Generating Station''.
    The additions read as follows:

Sec.  52.120  Identification of plan.

* * * * *
    (d) * * *

                                    EPA-Approved Source Specific Requirements
----------------------------------------------------------------------------------------------------------------
         Name of source             Order/permit No.       Effective date   EPA approval date     Explanation
----------------------------------------------------------------------------------------------------------------
                                   Arizona Department of Environmental Quality
----------------------------------------------------------------------------------------------------------------

----------------------------------------------------------------------------------------------------------------
                                                  * * * * * * *
Coronado Generating Station....  Permit #64169 (as       December 14, 2016  [Insert date of    Permit issued by
                                  amended by                                 publication of     Arizona
                                  Significant Revision                       final rule],       Department of
                                  #63088) Cover Page                         [insert Federal    Environmental
                                  and Attachment ``E'':                      Register           Quality.
                                  BART Alternatives.                         citation of        Submitted on
                                                                             final rule].       December 15,
                                                                                2016.

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

* * * * *
    (e) * * *

                       Table 1--EPA-Approved Non-Regulatory and Quasi-Regulatory Measures
       [Excluding certain resolutions and statutes, which are listed in tables 2 and 3, respectively] \1\
----------------------------------------------------------------------------------------------------------------
                                      Applicable
                                     geographic or
      Name of SIP provision          nonattainment      State submittal   EPA approval  date      Explanation
                                    area or  title/          date
                                        subject
----------------------------------------------------------------------------------------------------------------
                         The State of Arizona Air Pollution Control Implementation Plan
----------------------------------------------------------------------------------------------------------------
    Clean Air Act Section 110(a)(2) State Implementation Plan Elements (Excluding Part D Elements and Plans)
----------------------------------------------------------------------------------------------------------------

----------------------------------------------------------------------------------------------------------------
                                                  * * * * * * *
Arizona State Implementation      Source-Specific...  December 15, 2016.  [Insert date of     BART Alternative
 Plan Revision to the Arizona                                              publication of      for Coronado
 Regional Haze Plan for the Salt                                           final rule],        Generating
 River Project Coronado                                                    [Insert Federal     Station adopted
 Generating Station, excluding                                             Register citation   December 14,
 Appendix B.                                                               of final rule].     2016.

                                                  * * * * * * *
----------------------------------------------------------------------------------------------------------------
\1\ Table 1 is divided into three parts: Clean Air Act Section 110(a)(2) State Implementation Plan Elements
  (excluding Part D Elements and Plans), Part D Elements and Plans (other than for the Metropolitan Phoenix or
  Tucson Areas), and Part D Elements and Plans for the Metropolitan Phoenix and Tucson Areas.

* * * * *
0
3. Section 52.145 is amended by:
0
a. Removing and reserving paragraph (e)(1).
0
b. Removing paragraphs (e)(2)(iii) through (vi).
0
c. Removing and reserving paragraph (f).

[FR Doc. 2017-08543 Filed 4-26-17; 8:45 am]
 BILLING CODE 6560-50-P