
[Federal Register Volume 82, Number 80 (Thursday, April 27, 2017)]
[Proposed Rules]
[Pages 19333-19347]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2017-08543]


=======================================================================
-----------------------------------------------------------------------

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.

-----------------------------------------------------------------------

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that have either been superseded by previously approved revisions to 
the Arizona SIP or would be superseded by final approval of the SIP 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 viswanathan.krishna@epa.gov. 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

[[Page 19334]]

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, (520) 999-7880 or 
viswanathan.krishna@epa.gov.

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\
---------------------------------------------------------------------------

    \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.''
---------------------------------------------------------------------------

     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 Viswanathan.krishna@epa.gov 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

[[Page 19335]]

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\
---------------------------------------------------------------------------

    \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).
---------------------------------------------------------------------------

    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.
---------------------------------------------------------------------------

    \11\ 77 FR 72512 (December 5, 2012).
---------------------------------------------------------------------------

    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\
---------------------------------------------------------------------------

    \12\ Id.
---------------------------------------------------------------------------

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.
---------------------------------------------------------------------------

    \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).
---------------------------------------------------------------------------

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.
---------------------------------------------------------------------------

    \15\ 81 FR 21735 (April 13, 2016).
---------------------------------------------------------------------------

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.
---------------------------------------------------------------------------

    \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.
---------------------------------------------------------------------------

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

[[Page 19336]]

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.
---------------------------------------------------------------------------

    \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
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                       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)
--------------------------------------------------------------------------------------------------------------------------------------------------------
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
                                   ---------------------------------------------------------------------------------------------------------------------
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
--------------------------------------------------------------------------------------------------------------------------------------------------------
\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\
---------------------------------------------------------------------------

    \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.
---------------------------------------------------------------------------

    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\
---------------------------------------------------------------------------

    \20\ 40 CFR 51.308(e)(2)(i).
---------------------------------------------------------------------------

     A requirement that all necessary emissions reductions take 
place during the period of the first long-term strategy for regional 
haze.\21\
---------------------------------------------------------------------------

    \21\ 40 CFR 51.308(e)(2)(iii).
---------------------------------------------------------------------------

     A demonstration that the emissions reductions resulting 
from the alternative measure will be surplus to those reductions 
resulting from measures

[[Page 19337]]

adopted to meet requirements of the CAA as of the baseline date of the 
SIP.\22\
---------------------------------------------------------------------------

    \22\ 40 CFR 51.308(e)(2)(iv).
---------------------------------------------------------------------------

    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\
---------------------------------------------------------------------------

    \23\ 40 CFR 51.308(e)(2)(i)(C).
---------------------------------------------------------------------------

     an analysis of projected emissions reductions achievable 
through the BART alternative \24\
---------------------------------------------------------------------------

    \24\ 40 CFR 51.308(e)(2)(i)(D).
---------------------------------------------------------------------------

     a determination that the alternative achieves greater 
reasonable progress than would be achieved through the installation and 
operation of BART \25\
---------------------------------------------------------------------------

    \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\
---------------------------------------------------------------------------

    \26\ 81 FR 21735 (April 13, 2016).
---------------------------------------------------------------------------

    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
----------------------------------------------------------------------------------------------------------------
                                                                  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
----------------------------------------------------------------------------------------------------------------

    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.
---------------------------------------------------------------------------

    \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]
----------------------------------------------------------------------------------------------------------------
              Operating strategies                      NOX             SO2            PM10            Total
----------------------------------------------------------------------------------------------------------------
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
----------------------------------------------------------------------------------------------------------------

    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.
---------------------------------------------------------------------------

    \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.'')

---------------------------------------------------------------------------

[[Page 19338]]

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
----------------------------------------------------------------------------------------------------------------
              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

[[Page 19339]]

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).

[[Page 19340]]



                    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

[[Page 19341]]

 
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,

[[Page 19342]]

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

[[Page 19343]]

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

[[Page 19344]]

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.

[[Page 19345]]

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

[[Page 19346]]

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.


[[Page 19347]]

* * * * *
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


