Document ID: EPA-R08-OAR-2015-0463-0182
Agency: epa
Document Type: Rule
Title: Air Quality State Implementation Plans; Approvals and Promulgations: Utah; Revisions to Regional Haze State Implementation Plan; Federal Implementation Plan for Regional Haze
Posted Date: 2016-07-05T04:00Z

[Federal Register Volume 81, Number 128 (Tuesday, July 5, 2016)]
[Rules and Regulations]
[Pages 43893-43925]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2016-14645]

[[Page 43893]]

Vol. 81

Tuesday,

No. 128

July 5, 2016

Part IV

 Environmental Protection Agency

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40 CFR Part 52

 Approval, Disapproval and Promulgation of Air Quality Implementation 
Plans; Partial Approval and Partial Disapproval of Air Quality 
Implementation Plans and Federal Implementation Plan; Utah; Revisions 
To Regional Haze State Implementation Plan; Federal Implementation Plan 
for Regional Haze; Final Rule

  Federal Register / Vol. 81 , No. 128 / Tuesday, July 5, 2016 / Rules 
and Regulations  

[[Page 43894]]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R08-OAR-2015-0463; FRL-9947-42-Region 8]

Approval, Disapproval and Promulgation of Air Quality 
Implementation Plans; Partial Approval and Partial Disapproval of Air 
Quality Implementation Plans and Federal Implementation Plan; Utah; 
Revisions to Regional Haze State Implementation Plan; Federal 
Implementation Plan for Regional Haze

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: The Environmental Protection Agency (EPA) is partially 
approving and partially disapproving a State Implementation Plan (SIP) 
revision submitted by the State of Utah on June 4, 2015 to implement 
the regional haze program pursuant to section 169A of the Clean Air Act 
(CAA or Act). The State's SIP revisions would establish an alternative 
to best available retrofit technology (BART) controls that would 
otherwise be required to control nitrogen oxides (NOX) at 
PacifiCorp's Hunter and Huntington power plants. The June 2015 SIP 
revision also includes BART determinations for particulate matter with 
an aerodynamic diameter of less than 10 micrometers (PM10) 
at these power plants and provisions for making the NOX and 
PM10 BART emission limits federally enforceable. The CAA 
requires states to prevent any future and remedy any existing man-made 
impairment of visibility in national parks and wilderness areas 
designated as Class I areas. Air emissions from the four electric 
generating units (EGUs) at the two plants affected by this action cause 
or contribute to visibility impairment at nine Class I areas including 
Grand Canyon, Arches, Black Canyon, Bryce Canyon, Canyonlands, Capitol 
Reef, Mesa Verde and Zion National Parks and Flat Tops Wilderness Area. 
The EPA is finalizing the option in our January 14, 2016 co-proposal to 
partially approve and partially disapprove the June 2015 SIP revision 
and is promulgating a Federal Implementation Plan (FIP) to address the 
deficiencies identified in our proposed partial disapproval of Utah's 
regional haze SIP. The EPA is not taking any final action on a related 
October 20, 2015 SIP revision. The State retains its authority to 
submit a revised state plan consistent with CAA and Regional Haze Rule 
(RHR) requirements. An approvable SIP submission will result in the 
modification or withdrawal of the FIP.

DATES: This final rule is effective August 4, 2016.

ADDRESSES: EPA has established a docket for this action under Docket ID 
No. EPA-R08-OAR-2015-0463. All documents in the docket are listed on 
the www.regulations.gov Web site. Publicly available docket materials 
are available either electronically through www.regulations.gov, or in 
hard copy at the Air Program, Environmental Protection Agency (EPA), 
Region 8, 1595 Wynkoop Street, Denver, Colorado 80202-1129. EPA 
requests that if, at all possible, 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, 8 a.m. to 4 p.m., excluding federal holidays.

FOR FURTHER INFORMATION CONTACT: Gail Fallon, Air Program, EPA, Region 
8, Mailcode 8P-AR, 1595 Wynkoop Street, Denver, Colorado, 80202-1129, 
(303) 312-6281, Fallon.Gail@epa.gov.

SUPPLEMENTARY INFORMATION: 

 Table of Contents

I. Introduction
    A. Our Co-Proposals
    1. Summary of Proposed Full Approval of the SIP
    2. Summary of Proposed Partial Approval and Partial Disapproval 
of the SIP and Proposal of a FIP
    B. Summary of the Basis for Our Final Decision
    1. NOX BART
    a. Regulatory Framework for BART Alternatives
    b. Utah's ``Greater Reasonable Progress Than BART'' Metrics
    c. EPA's Evaluation of Utah's ``Greater Reasonable Progress than 
BART'' Analysis
    i. Annual Emissions Comparison of All Visibility-Impairing 
Pollutants
    ii. Improvement in Number of Days with Significant Visibility 
Impairment
    iii. 98th Percentile Modeling Impact (dv)
    iv. Annual Average Modeling Impact (dv)
    v. 90th Percentile Modeling Impact (dv)
    vi. Timing of the Emissions Reductions
    vii. Monitoring Data at the Class I Areas (IMPROVE Network)
    viii. Energy and Non-Air Quality Benefits
    ix. Cost
    x. EPA's Evaluation of the State's Conclusions
    d. Remaining BART Alternative Criteria
    e. Monitoring, Recordkeeping and Reporting for Utah's BART 
Alternative
    f. Basis for Our NOX BART Determinations and FIP
    2. PM10 BART
    3. Enforceable Commitment SIP
II. Summary and Analysis of Major Issues Raised by Commenters
    A. General Comments
    B. EPA Authority and State Discretion
    C. Reasonableness Standard
    D. Compliance With 40 CFR 51.308
    E. Overarching Comments on BART Alternative Demonstration
    F. Cost of Controls
    G. Comparison With Other Regional Haze Actions
    H. CALPUFF Modeling
    I. Consideration of Existing Controls
    J. PM10 BART
    K. Environmental Justice
III. Final Action
    A. Final Partial Approval
    B. Final Partial Disapproval and Federal Implementation Plan
    C. No Action
IV. Incorporation by Reference
V. Statutory and Executive Order Reviews
    A. Executive Order 12866: Regulatory Planning and Review and 
Executive Order 13563: Improving Regulation and Regulatory Review
    B. Paperwork Reduction Act
    C. Regulatory Flexibility Act
    D. Unfunded Mandates Reform Act (UMRA)
    E. Executive Order 13132: Federalism
    F. Executive Order 13175: Consultation and Coordination With 
Indian Tribal Governments
    G. Executive Order 13045: Protection of Children From 
Environmental Health Risks and Safety Risks
    H. Executive Order 13211: Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution, or Use
    I. National Technology Transfer and Advancement Act
    J. Executive Order 12898: Federal Actions To Address 
Environmental Justice in Minority Populations and Low-Income 
Populations
    K. Congressional Review Act
    L. Judicial Review

I. Introduction

    The purpose of federal and state regional haze plans is to achieve 
the national goal, declared by Congress, of restoring and protecting 
visibility at 156 federal Class I areas across the United States, most 
of which are national parks and wilderness areas with scenic vistas 
enjoyed by the American public. The national goal, as described in CAA 
section 169A, is the prevention of any future, and the remedying of any 
existing, impairment of visibility in mandatory Class I federal areas 
where such impairment results from man-made air pollution. States are 
required to submit SIPs that, among other things, ensure reasonable 
progress toward the national goal of remedying anthropogenic visibility 
impairment in federal Class I areas. Arizona, Colorado, and Utah have a 
wealth of such areas that are impacted by the Hunter and Huntington 
power plants, including Grand Canyon, Arches, Black Canyon,

[[Page 43895]]

Bryce Canyon, Canyonlands, Capitol Reef, Mesa Verde and Zion National 
Parks and Flat Tops Wilderness Area. The four units at the two power 
plants that are subject to the CAA BART requirements are large sources 
of NOX,\1\ and the NOX emissions from these 
plants affect visibility \2\ at some of the countries' most beloved 
Class I areas that are visited by millions of Americans. The CAA 
requires that such sources install and operate controls to limit 
visibility impairing pollutants; in this instance there are very cost-
effective controls available for these units, which will operate for 
many years into the future.
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    \1\ Annual average NOX emissions in tons per year for 
each of the four BART units for the period 2001-2003 were as 
follows: Hunter Unit 1 [6,380 tons/yr], Hunter Unit 2 [6,092 tons/
yr], Huntington Unit 1 [5,944 tons/yr], Huntington Unit 2 [5,816 
tons/yr].
    \2\ Refer to Tables 6 and 7 for visibility impacts.
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    We proposed action on Utah's June 4, 2015 and October 20, 2015 
regional haze SIP submittals addressing NOX and 
PM10 BART requirements on January 14, 2016.\3\ The EPA 
conducted a public hearing for our proposed action in Salt Lake City, 
Utah on January 26, 2016. Our public comment period closed on March 14, 
2016.
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    \3\ 81 FR 2004 (Jan. 14, 2016).
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    In this action, we are partially approving and partially 
disapproving the SIP submittal submitted by Utah on June 4, 2015, and 
taking no action on the State's October 20, 2015 SIP submittal. These 
submittals include actions intended to satisfy the State's obligations 
for the regional haze program's first planning period, including the 
obligation to submit a SIP containing emission limitations representing 
BART for NOX and PM for each of the four subject-to-BART 
sources of visibility-impairing emissions. We are also promulgating a 
FIP to address the deficiencies we have identified in the portions of 
the SIP submittal that we are disapproving.
    Utah's SIP submittal was to address the BART requirements for 
NOX in part through reliance on a BART alternative program 
under 40 CFR 51.308(e)(2), which allows a state to implement such a 
BART alternative when the clear weight of the evidence demonstrates 
that it achieves greater reasonable progress than BART.\4\ 
Specifically, rather than installing and operating BART controls for 
its four subject-to-BART electric generating units (EGUs), Utah's SIP 
submittal relied on an alternative program, which included the 
following: (1) The installation of upgraded combustion controls between 
2006 and 2014 at the four BART units plus an additional EGU at 
PacifiCorp's Hunter plant; and (2) the shutdown of the Carbon plant, a 
non-BART source, to meet the BART requirements for emissions of 
NOX. To meet its PM BART requirements, Utah's SIP submittal 
included the most stringent control technology at each of the four 
subject-to-BART EGUs. We provided a detailed explanation of the 
contents of Utah's June and October 2015 submittals along with an 
overview of earlier Utah regional haze submittals and EPA's actions on 
these earlier submittals in sections IV and III.E, respectively, of our 
proposed rule.\5\
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    \4\ For purposes of comparing the proposed BART Alternative to 
BART, Utah used most stringent NOX control technology to 
represent BART, which is referred to as the BART Benchmark.
    \5\ 81 FR 2004, 2012-2020 (Jan. 14, 2016).
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    EPA takes very seriously a decision to disapprove any state plan. 
Our intention is to approve a state's exercise of discretion if it can 
be supported. However, to approve a state plan EPA must be able to find 
that the plan is consistent with the requirements of the CAA and EPA's 
regulations. Although these are largely fact-based decisions, we focus 
strongly on consistently applying the regional haze requirements across 
this national program. After carefully considering the comments on our 
proposal, we determined that there is only one permissible outcome. 
Therefore, for the reasons described in our proposal and in this 
action, we find that the State's NOX BART Alternative for 
the power plants is not consistent with the applicable statutory and 
regulatory requirements. As a result, EPA has determined that final 
disapproval is the only path that is consistent with the Act.
    Although we are promulgating a federal plan, the State retains its 
authority to submit a revised state plan consistent with CAA and 
Regional Haze Rule requirements. If we determine that the SIP revision 
is approvable, regardless of whether or not its terms match those of 
our final FIP, we would propose to approve such a SIP revision. An 
approvable SIP submission will result in the modification or withdrawal 
of the FIP.\6\
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    \6\ Additionally, as discussed later in section I.B.3, at this 
time we not taking action on the State's October 20, 2015 
enforceable commitment SIP submittal.
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A. Our Co-Proposals

    When we reviewed the Utah regional haze SIP, we noted that some of 
the metrics the State included in its weight-of-evidence analysis 
presented to support the NOX BART Alternative appear to 
support a conclusion that the BART Alternative achieves greater 
reasonable progress than BART (i.e., selective catalytic reduction 
(SCR) technology at the four BART units at Hunter and Huntington). 
However, we also noted that several other metrics in the State's 
analyses did not appear to support a conclusion that the BART 
Alternative achieves greater reasonable progress. The collection of 
information before EPA at the time of proposal presented a close call 
for us to decide whether to approve or disapprove the State's BART 
Alternative. Therefore, to allow all interested parties an opportunity 
to comment on either approach, we proposed and solicited comment on two 
possible conclusions and courses of action: (1) The State's submittal 
for NOX BART meets the test under 40 CFR 51.308(e)(2)(i)(E) 
and we approve the BART Alternative; or (2) the State's submittal falls 
short of meeting this test and we disapprove the BART Alternative and 
promulgate a FIP for NOX BART. We requested comment on all 
aspects of each proposal.
1. Summary of Proposed Full Approval of the SIP
    In one option of our co-proposal, we proposed to approve the 
following aspects of the State's June 4, 2015 SIP submittal:
     NOX BART Alternative, including: NOX 
emission reductions from Hunter Units 1, 2, and 3; Huntington Units 1 
and 2; and Carbon Units 1 and 2; and sulfur dioxide (SO2) 
and PM10 emission reductions from Carbon Units 1 and 2.
     BART determinations and emission limits for 
PM10 at Hunter Units 1 and 2 and Huntington Units 1 and 2.
     Monitoring, recordkeeping, and reporting requirements for 
units subject to the BART Alternative and the PM10 emission 
limits.
    We also proposed to approve these elements of the State's October 
20, 2015 SIP submittal:
     Enforceable commitments to revise SIP Section XX.D.3.c and 
State rule R307-150 by March 2018 to clarify emission inventory 
requirements for tracking compliance with the SO2 milestone 
and properly accounting for the SO2 emission reductions due 
to the closure of the Carbon plant.
2. Summary of Proposed Partial Approval and Partial Disapproval of the 
SIP and Proposal of a FIP
    In the other option of our co-proposal, we proposed to approve 
these elements of the State's June 4, 2015 SIP submittal:
     BART determinations and emission limits for 
PM10 at Hunter Units 1 and 2 and Huntington Units 1 and 2.

[[Page 43896]]

     Monitoring, recordkeeping, and reporting requirements for 
units subject to the PM10 emission limits.
    We proposed to disapprove these aspects of the State's June 4, 2015 
SIP submittal:
     NOX BART Alternative, including NOX 
emission reductions from Hunter Units 1, 2, and 3; Huntington Units 1 
and 2; and Carbon Units 1 and 2; and SO2 and PM10 
emission reductions from Carbon Units 1 and 2.
    We proposed to disapprove the State's October 20, 2015 SIP 
submittal.
    We proposed promulgation of a FIP to address the deficiencies in 
the Utah regional haze SIPs that were identified in the proposed 
action. The proposed FIP included the following elements:
     NOX BART determinations and emission limits for 
Hunter Units 1 and 2 and Huntington Units 1 and 2.
     Monitoring, recordkeeping, and reporting requirements for 
NOX at Hunter Units 1 and 2, and Huntington Units 1 and 2.

B. Summary of the Basis for Our Final Decision

    Based upon comments we received on our proposed action and our 
evaluation of both the State's submittals and those comments, in this 
final action we are partially approving and partially disapproving 
Utah's regional haze SIP submitted on June 4, 2015, and we are taking 
no action on Utah's regional haze SIP submitted on October 20, 2015. We 
are promulgating a FIP to address the deficiencies we have identified 
in the portions of the SIP that we are disapproving. Later we present a 
summary of the major points of our final decision regarding the Utah 
regional haze SIP submittal that we are acting on today in which we 
summarize which parts of the Utah regional haze SIP submittal we are 
approving and disapproving and which parts are cured by our FIP.
1. NOX BART
    As discussed in depth elsewhere in this document and in our 
separate Response to Comment (RTC) document, we considered the record 
before us and comments on both of our co-proposals, and have determined 
that the evidence does not clearly demonstrate that Utah's BART 
Alternative makes greater reasonable progress than BART; that is, we 
have determined that the State's Alternative is not clearly better than 
BART. Therefore, we are disapproving the BART Alternative contained in 
Utah's June 4, 2015 submittal and promulgating a FIP to satisfy the 
regional haze program's NOX BART requirements.
    In our co-proposal, to ensure our final decision was based on the 
best and most currently available data and information, we asked if 
interested parties had additional information in a number of areas, 
including: (1) Analysis related to the modeled visibility benefits of 
the BART Alternative compared to BART; and (2) other BART alternatives 
or BART control technology options related to what we proposed and that 
could be finalized as our FIP. We also asked if interested parties had 
additional information or comments on the proposed timeline of 
compliance.\7\ We explained that any supplemental information we 
received could lead us to adopt final SIP and/or FIP regulations that 
differ somewhat from the co-proposals presented in our proposed rule 
regarding the BART Alternative, BART control technology option or 
emission limits, or impact other proposed regulatory provisions.\8\ We 
did not receive any modeling analysis related to the benefits of the 
BART Alternative compared to BART or any suggestions for consideration 
of other BART alternatives or BART control technology options. However, 
we did receive extensive comments on our two possible evaluations of 
Utah's BART Alternative. As a result of these comments, we have revised 
some of the aspects of our evaluations of the State's BART Alternative 
metrics. Based on the revisions to our evaluations of the State's 
metrics, we have reassessed our co-proposed actions on the State's BART 
Alternative and determined that it does not demonstrate greater 
reasonable progress than BART. We provide our reassessment of the 
State's weight-of-evidence metrics in this section, and provide 
additional detail in our RTC document.
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    \7\ 81 FR 2004, 2007, Jan. 14, 2016.
    \8\ Id.
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a. Regulatory Framework for BART Alternatives
    To demonstrate that a BART alternative measure achieves greater 
reasonable progress than the BART requirements, EPA evaluates a SIP 
submittal to determine whether it demonstrates that the alternative 
will achieve greater reasonable progress toward natural visibility 
conditions than BART under 40 CFR 51.308(e)(3) or otherwise based on 
the clear weight of evidence.\9\ The BART Alternative rule requires 
that the alternative program must ``clearly'' be better than BART, 
which we have explained is ``when there is confidence that the 
difference in visibility impacts between BART and the alternative 
scenarios are expected to be large enough'' \10\ to ensure that that 
the alternative is, in fact, better. Therefore, as part of our 
evaluation of Utah's SIP we evaluated whether the differences in 
visibility impacts between BART and the State's BART Alternative are 
``large enough'' to satisfy the clear weight-of-evidence requirement. 
The State of Utah opted to develop its SIP under the clear weight-of-
evidence standard, and provided its analysis in the ``Greater 
Reasonable Progress than BART'' section of the SIP submittal.\11\ As 
explained in our BART Alternative rule, the clear weight-of-evidence 
test follows these steps: \12\
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    \9\ 40 CFR 51.308(e)(2)(i)(E).
    \10\ 71 FR 60622 (``In showing that an alternative program is 
better than BART and when there is confidence that the difference in 
visibility impacts between BART and the alternative scenarios are 
expected to be large enough, a weight of evidence comparison may be 
warranted in making the comparison.'' (emphasis added)).
    \11\ This section of the State's SIP submittal presents the BART 
Alternative rule regulatory requirements, including EPA's 
description that the clear weight of evidence standard uses 
information to inform a decision while recognizing the relative 
strengths and weaknesses of that information. The Utah SIP Section 
XX that was submitted to EPA, was adopted by the Air Quality Board 
on June 3, 2015, and included the proposed provisions to address the 
NOX BART requirements. Footnote 4 in that Section of the 
SIP referenced the State's greater reasonable progress 
demonstration. The document referenced in the footnote was titled 
``Staff Review 2008 PM BART Determination and Recommended 
Alternative to BART for NOX, Utah Division of Air 
Quality, May 13, 2015'' (``Utah Staff Review Report'' at 11).
    \12\ 71 FR 60612, 60622 (Oct. 13, 2006). As we explained in 
adding to our final RHR the ``clear weight of the evidence'' 
standard, `` `[w]eight of evidence' demonstrations attempt to make 
use of all available information and data which can inform a 
decision while recognizing the relative strengths and weaknesses of 
that information in arriving at the soundest decision possible. 
Factors which can be used in a weight of evidence determination in 
this context may include, but not be limited to, future projected 
emissions levels under the program as compared to under BART, future 
projected visibility conditions under the two scenarios, the 
geographic distribution of sources likely to reduce or increase 
emissions under the program as compared to BART sources, monitoring 
data and emissions inventories, and sensitivity analyses of any 
models used. This array of information and other relevant data may 
be of sufficient quality to inform the comparison of visibility 
impacts between BART and the alternative program. In showing that an 
alternative program is better than BART and when there is confidence 
that the difference in visibility impacts between BART and the 
alternative scenarios are expected to be large enough, a weight of 
evidence comparison may be warranted in making the comparison. The 
EPA will carefully consider the evidence before us in evaluating any 
[state implementation plans] submitted by States employing such an 
approach.'' Id.
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    (1) Use information and data that can inform the decision. Collect 
information that can be used to assess whether the proposed alternative 
measure will achieve greater reasonable progress than BART. The 
information is used to

[[Page 43897]]

evaluate whether the visibility improvements at the Class I areas will 
be better under the alternative than under BART. Such information may 
include, but is not limited to, future projected emissions levels under 
the BART alternative as compared to under the BART benchmark; future 
projected visibility conditions under the two scenarios; the geographic 
distribution of sources likely to reduce or increase emissions under 
the program as compared to BART sources; monitoring data and emissions 
inventories; and sensitivity analyses of any models used.
    (2) Recognize the relative strengths and weaknesses of the 
information. Evaluate the information and recognize the relative 
strengths and weaknesses of the metrics used. This process involves 
assigning weights to each piece of information that indicate the degree 
to which it supports a finding that the alternative program will 
achieve greater visibility benefits. Such a weighing system might find 
that: (i) The information clearly shows the alternative will achieve 
greater reasonable progress than BART; (ii) the information supports 
the alternative in some way, but not clearly; or (iii) the information 
does not support the alternative.
    (3) Carefully consider all the information to reach a conclusion. 
Collectively consider the weights assigned to the individual pieces of 
information and consider the total weight of all the information to 
determine whether the proposed BART alternative will clearly provide 
for greater reasonable progress than BART at the impacted Class I 
areas.
    Additionally, in this document, we occasionally point to the BART 
Guidelines for authority on the analysis of BART alternatives (e.g., 
consideration of 98th percentile CALPUFF modeling).\13\ We acknowledge 
that the BART Guidelines are not mandatory for the evaluation of BART 
alternatives and the Guidelines do not directly address this 
subject.\14\ However, our rules at 40 CFR 51.309 and the preamble for 
the provisions governing alternatives to source-specific BART 
determinations \15\ do not provide guidance on visibility modeling. We 
rely on the BART Guidelines here and in other actions involving BART 
alternatives because they provide a reasonable and consistent approach 
regarding visibility modeling, as well as other aspects of a BART 
alternative, conducted as part of a weight-of-evidence analysis.
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    \13\ We also referred to the BART Guidelines as authority in our 
proposal.
    \14\ The BART Guidelines are mandatory in this action regarding 
both the State's determinations of the BART Benchmark pursuant to 40 
CFR 51.308(e)(2)(i)(C) and EPA's BART determinations in the FIP 
pursuant to 40 CFR 51.308(e)(1)(ii)(B).
    \15\ 71 FR 60612, October 13, 2006.
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b. Utah's ``Greater Reasonable Progress Than BART'' Metrics
    The State collected and evaluated information ``from a number of 
different metrics . . . to compare the two scenarios.'' \16\ These nine 
metrics included: (1) Annual emissions of visibility-impairing 
pollutants; (2) improvement in the number of days with significant 
visibility impairment derived from CALPUFF modeling results; (3) 98th 
percentile modeling impact (deciview [dv]) results derived from CALPUFF 
modeling; (4) annual average impact (dv) derived from CALPUFF modeling 
results; (5) 90th percentile impact (dv) results derived from CALPUFF 
modeling; (6) timing of emissions reductions; (7) results from IMPROVE 
monitoring data; (8) energy and non-air quality benefits; and (9) 
costs. The State considered the information from these metrics and 
concluded that the weight-of-evidence shows that its alternative 
program will provide greater reasonable progress than BART.\17\
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    \16\ Utah Staff Review Report at 12.
    \17\ Id. at 27 and Utah's SIP, Section XX, Regional Haze (June 
3, 2015) (``2015 SIP'').
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c. EPA's Evaluation of Utah's ``Greater Reasonable Progress Than BART'' 
Analysis
    We evaluated the information for each of the nine metrics in the 
State's SIP submittal,\18\ as well as additional information submitted 
by commenters. As part of this evaluation, we assessed the relevance 
and strength of each metric, that is, we assigned each metric a 
weight.\19\ After determining if, and the extent to which, the 
information the State relied upon was ``of sufficient quality to inform 
the comparison of visibility impacts between BART and the alternative 
program,'' \20\ we assessed the metrics collectively to determine 
whether the relevant evidence, considered as a whole, clearly 
demonstrated that the alternative program achieves greater visibility 
benefits.
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    \18\ Utah Staff Review Report at pp. 13-29.
    \19\ As discussed in this section, Utah did not assign a weight 
to each metric.
    \20\ 71 FR 60612, 60622.
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    Our initial review considered whether each of the nine metrics met 
the threshold regulatory requirement that information considered in a 
weight-of-evidence analysis be relevant to an assessment of visibility 
impacts. We find the State included two metrics, (1) energy and non-air 
quality impacts and (2) cost, that are inconsistent with the greater 
reasonable progress analysis in the RHR because the metrics do not 
evaluate visibility benefits at the nine Class I areas impacted by the 
State's sources. Therefore, as discussed in detail later in sections 
I.B.1.c.viii and I.B.1.c.ix, we did not give this information any 
weight in our evaluation of whether the State has demonstrated that its 
BART Alternative achieves greater reasonable progress than BART.
    Additionally, the State included information on the aggregate 
annual emissions of all three visibility-impairing pollutants emitted 
by the sources. However, in this particular instance the aggregate 
emissions data do not provide information on the likely visibility 
impacts of the State's alternative program as compared to BART. 
Therefore, as discussed in detail later in section I.B.1.c.i, we found 
that this information was inconclusive and does not weigh either in 
favor of or against the BART Alternative.
    Next, we evaluated how the State recognized the strengths and 
weakness of the remaining six metrics. The State placed each metric in 
one of two categories: The information from the metric supported the 
BART Alternative, or it did not. The State determined that five of the 
metrics supported the BART Alternative \21\ and one metric, the 98th 
percentile CALPUFF modeling results, did not support the BART 
Alternative.\22\ However, contrary to the requirement to weigh the 
evidence,\23\ which Utah's SIP acknowledged is part of the weight-of-
evidence standard,\24\ the SIP submittal did not assess the relative 
strengths and weaknesses of the metrics; that is, it did not explain 
the weight that the State assigned to each of the metrics it found 
supported the BART Alternative. In evaluating the SIP submittal, we 
assessed the relative strengths and weakness of each of the State's 
metrics to determine whether it was reasonable for the State simply to 
categorize the metrics into the two categories (the metric supported 
the BART Alternative or did not support the Alternative). In

[[Page 43898]]

addition to information in the submittal, we considered suggestions on 
the amount of ``weight'' that should be given to each of the metrics 
that were provided by commenters on our proposal, including the 
State.\25\ As a result of our evaluation, we find that the State's 
assessment of the metrics was inadequate because it did not recognize 
the relative strengths and weaknesses of the metrics on an individual 
basis. We also find that a proper recognition of the relative strengths 
and weaknesses, including the consideration that some metrics are more 
meaningful than others, shows that the BART Alternative does not 
achieve greater reasonable progress than BART.
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    \21\ See Utah Staff Review Report at p. 27 (listing factors the 
State suggested to support the BART Alternative in the ``Summary of 
Weight of Evidence'' section).
    \22\ As discussed elsewhere, EPA disagrees with the State's 
evaluation of the 98th percentile metric.
    \23\ 40 CFR 51.308(e)(2)(i)(E).
    \24\ Utah Staff Review Report at 11 (the BART alternative 
regulatory provisions and EPA's description of the weight-of-
evidence standard, including that a demonstration recognize the 
strengths and weaknesses of the information in arriving at the 
soundest decision possible, citing 71 FR 60612, 60622).
    \25\ The State's Comment letter suggested the ``weight'' for 
several of the metrics.
---------------------------------------------------------------------------

    We evaluated each of the State's nine metrics and included: (1) An 
assessment of whether we agree as a factual matter with the State's 
conclusion; and (2) the weight we would give to each metric. Our 
evaluation below includes the two metrics that we find contain 
information that is not relevant, and the one to which we did not 
assign any weight.
i. Annual Emissions Comparison of All Visibility-Impairing Pollutants
    The State's regional haze SIP submittal determined that the 
combined emissions of three key visibility-impairing pollutants will be 
lower under the BART Alternative scenario and that this supported the 
weight-of-evidence determination that the BART Alternative will provide 
greater reasonable progress than BART.26 27 We 
proposed to find that, since Utah's BART Alternative provides greater 
emission reductions for two pollutants (SO2 and 
PM10), but that NOX emissions would be greater under the 
BART Alternative, it is not appropriate to combine all three pollutants 
in the annual emissions comparison test to support the BART 
Alternative. Therefore, we further proposed to find that the annual 
emissions comparison of all three pollutants does not show that the 
BART Alternative is better than the BART Benchmark.\28\
---------------------------------------------------------------------------

    \26\ 2015 SIP at 25, and Utah Staff Review Report at 27.
    \27\ EPA derived the following emissions reductions for the BART 
Alternative from the Utah Staff Review Report at 10, by subtracting 
the total annual emissions for the BART Alternative from the total 
annual emissions for the BART Benchmark for each of the visibility-
pairing pollutants: SO2 8,005 tpy, PM10 573 
tpy, and NOX-5,721 tpy (NOX is negative 
because NOX emissions increase under the BART 
Alternative). This information is also provided in Table 4 of our 
proposed rule. (81 FR 2004, 2016.)
    \28\ 81 FR 2004, 2029.
---------------------------------------------------------------------------

    As a result of the comments received on our co-proposal, we have 
further assessed the State's evidence for this metric and while we have 
clarified our assessment, we have not changed our overall proposed 
findings. Although emissions of two visibility-impairing pollutants are 
less under the BART Alternative, emissions of one of the pollutants 
would be greater. Due to differences in visibility impacts and complex 
interactions between pollutants, it is not possible to discern the 
overall visibility impacts of the aggregate emission reductions in this 
case without modeling; as discussed elsewhere, we disagree with 
comments to the contrary. Therefore, while we consider that aggregate 
emission reductions is a relevant concept because it relates to 
visibility impacts, in this particular case we continue to find that it 
is not appropriate to combine all three pollutants in the annual 
emission comparison test. We thus find that this metric is inconclusive 
and does not weigh either in favor of or against the BART Alternative.
ii. Improvement in Number of Days With Significant Visibility 
Impairment
    In its regional haze SIP submittal, Utah provided modeling results 
comparing the number of days with significant visibility impairment 
relative to natural visibility under the BART Alternative scenario to 
the number of days under the BART Benchmark. The State presented this 
information for two different thresholds of visibility impairment: 1.0 
dv of impairment compared to natural visibility, and 0.5 dv of 
impairment. The State determined that the BART Alternative leads to an 
average of six fewer days per year with a visibility impact greater 
than 1.0 dv per year and 58 fewer days per year with a visibility 
impact greater than 0.5 dv at the nine Class I areas.\29\ Utah also 
provided information in its submittal regarding the number of days with 
visibility improvement relative to baseline visibility (visibility 
conditions in 2001-2003) using a range of deciview thresholds (0.5 to 
5.0 dv improvement compared to baseline visibility conditions).\30\
---------------------------------------------------------------------------

    \29\ EPA unintentionally created some confusion with regard to 
this metric in our proposed rule by expressing this information as 
the total number of days with visibility impairment greater than 1.0 
and 0.5 dv in Tables 7 and 8, 81 FR 2004, 2017, based on modeling 
results presented in SIP TSD Ch. 6, Summary of Visibility Modeling. 
The State did not highlight these particular modeling results in 
this manner in its Utah Staff Review Report; rather, the State 
expressed this metric only as the average number of days per year 
over the three years modeled. We considered these modeling results, 
and as discussed in our RTC document, find that the results 
marginally support the Alternative.
    \30\ See Utah Staff Review Report, pp. 19-22, and Ch. 6, Summary 
of Visibility Modeling, and 2015 SIP at 25.
---------------------------------------------------------------------------

    In EPA's review, we considered this metric in our evaluation of the 
State's weight-of-evidence analysis because the improvement in the 
number of days with significant visibility impairment relates to 
assessing the frequency and duration of visibility impacts. It is 
relevant to look at the results for the Class I areas individually 
because visibility impacts are location specific. The results for the 
average number of days with impacts over 1.0 dv show that seven of the 
nine Class I areas had the same result or were within one day of having 
the same result under both the BART Alternative and Benchmark. In the 
context of an entire year, a difference of one day is not particularly 
significant. Therefore, we find that the results from the average 
number of days with visibility impacts over the 1.0 dv threshold do not 
show the BART Alternative is better. We observe that the results for 
the average number of days with impacts over 0.5 dv show that the BART 
Alternative is better at five of nine Class I areas, and at four Class 
I areas the Alternative results in the same number of days with impacts 
greater than 0.5 dv as the Benchmark or is within two days of the same 
result (favoring the BART Alternative at each of the four where there 
is a two-day difference). Therefore, we find that the results from the 
0.5 dv threshold show that the BART Alternative is marginally better.
iii. 98th Percentile Modeling Impact (dv)
    In its regional haze SIP, the State determined that while the 98th 
percentile modeling impact showed greater reasonable progress under the 
BART Benchmark,\31\ several considerations led to the State's 
conclusion that this metric does not give a complete picture of the 
visibility improvements that will be seen by visitors to Class I 
areas.\32\ Therefore, the State's summary of the weight-of-evidence did 
not include the results from the 98th percentile modeling impact.\33\ 
We assessed the State's evidence for this metric and proposed to find 
that on the whole, when using this method, the results from the BART 
Benchmark are slightly better on average across all years and nine 
Class I areas

[[Page 43899]]

(0.14 dv average difference). Also, this metric shows greater 
visibility improvement at five of nine Class I areas for the BART 
Benchmark. We proposed to find, consistent with the State's evaluation, 
that this metric favors the BART Benchmark and does not show that the 
BART Alternative is better.\34\
---------------------------------------------------------------------------

    \31\ Utah Staff Review Report at 24.
    \32\ Id. at 25.
    \33\ See id. at 27 (``Summary of Weight of Evidence'' section 
does not include 98th percentile modeling impact results).
    \34\ 81 FR 2004, 2030.
---------------------------------------------------------------------------

    As a result of the comments received on our co-proposal, we have 
further assessed the State's evidence for this metric and while we have 
clarified our assessment, we have not changed our overall proposed 
finding. We considered this metric in our evaluation of the State's 
weight-of-evidence analysis because the 98th percentile modeling 
results relate to assessing visibility impacts. We have considered all 
information, and consistent with the Agency's approach to assessing 
visibility benefits in both BART determinations and other 
determinations of ``greater reasonable progress'' using the CALPUFF 
model, have given most weight to the visibility impacts based on the 
98th percentile air quality modeling results.\35\
---------------------------------------------------------------------------

    \35\ See 81 FR 2004, 2021; 40 CFR part 51, appendix Y, section 
IV.D.5; 70 FR 39104, 39129 (July 6, 2005). See, e.g., 78 FR 79344 
(Dec. 30, 2012) (proposed rule, FIP for Tesoro Refining and Intalco 
Refinery BART Alternatives); 79 FR 33438 (June 11, 2014) (final 
rule, FIP for Tesoro Refining and Intalco Refinery BART 
Alternatives); 79 FR 56322, 56328 (Sept. 19, 2014) (proposed 
approval of Arizona Apache BART Alternative); 80 FR 19220 (Apr. 10, 
2015) (final approval of Arizona Apache BART Alternative). We 
provide examples of use of the 98th modeling results for BART 
determinations in the RTC.
---------------------------------------------------------------------------

iv. Annual Average Modeling Impact (dv)
    The State's regional haze SIP submittal stated that the average 
deciview impact metric shows the benefit from the BART Alternative will 
be achieved day in and day out in the Class I areas.\36\ This metric 
shows greater average visibility improvement at five of nine Class I 
areas for the BART Alternative.
---------------------------------------------------------------------------

    \36\ Utah Staff Review Report at 23.
---------------------------------------------------------------------------

    We assessed the State's evidence for this metric and proposed to 
find that the BART Alternative is only marginally better than the BART 
Benchmark based on the difference in overall averages between the two 
scenarios of 0.009 dv and that it shows less or equal visibility 
improvement than BART at four of the nine Class I areas. Therefore, we 
proposed to find that the information from the annual average metric 
does not support a conclusion that the BART Alternative achieves 
greater reasonable progress than the BART Benchmark.\37\
---------------------------------------------------------------------------

    \37\ 81 FR 2004, 2030.
---------------------------------------------------------------------------

    As a result of the comments received on our co-proposal, we have 
further assessed the State's evidence for this metric and we have 
clarified our assessment and finding about the State's evaluation. We 
considered this metric in our evaluation of the State's weight-of-
evidence analysis because the annual average modeling results relate to 
assessing visibility impacts. Importantly, we find that the annual 
average metric is less relevant than the 98th percentile because it 
does not provide information on visibility benefits on the days most 
impacted by the sources, which has been the focus of prior BART 
determinations \38\ and other determinations of ``greater reasonable 
progress'' that relied on CALPUFF modeling.\39\ Averaging the modeling 
results over an entire year dilutes the emission controls' (and BART 
Alternative emission reductions) potential visibility benefits and is 
inconsistent with the basis of the CALPUFF modeling approach used by 
the State. Additionally, the annual average visibility impact metric 
does not show greater visibility improvements than the Alternative at 
four of the nine affected Class I areas, and the average difference 
between BART and the Alternative across all nine of these areas is 
relatively small (0.009 dv). For these reasons, we find that the annual 
average impact metric in Utah's weight-of-evidence analysis only 
marginally supports the BART Alternative.
---------------------------------------------------------------------------

    \38\ 40 CFR part 51, appendix Y, section IV.D.5; 70 FR 39104, 
39129 (July 6, 2005). We provide examples of use of this information 
for BART determinations in the RTC.
    \39\ See, e.g., 78 FR 79344, 79355 (Dec. 30, 2013) (proposed 
rule, FIP for Tesoro Refining and Intalco Refinery BART Alternatives 
in Washington), 79 FR 56322, 56328 (Sept. 19, 2014) (proposed 
approval of Arizona Apache BART Alternative).
---------------------------------------------------------------------------

v. 90th Percentile Modeling Impact (dv)
    The State's regional haze SIP submittal determined that the CALPUFF 
modeling results from the 90th percentile deciview impact show that the 
BART Alternative will provide greater improvement.\40\ We assessed the 
State's evidence for this metric and proposed to find that although 
there was greater visibility improvement at seven of nine Class I areas 
for the BART Alternative, it was questionable if the BART Alternative 
was better based on the difference in the two scenarios of 0.006 dv. We 
therefore proposed to find that it is questionable whether the 90th 
percentile supports a conclusion that the BART Alternative achieves 
greater reasonable progress.\41\
---------------------------------------------------------------------------

    \40\ Utah Staff Review Report at 23-24, and 2015 SIP at 25.
    \41\ 81 FR 2004, 2030.
---------------------------------------------------------------------------

    As the result of the comments received on our co-proposal, we have 
further assessed the State's evidence for this metric and have 
clarified our assessment and finding. EPA has never used the CALPUFF 
90th percentile results in other RH decisions, and we disapproved the 
use of the 90th percentile results for subject-to-BART modeling.\42\ 
Here, though, we find it is appropriate to consider the CALPUFF 90th 
percentile results in evaluating the State's weight-of-evidence 
analysis because this metric provides some additional information about 
visibility benefits. However, we note that the 90th percentile metric 
excludes more than a month's worth of visibility data, which 
significantly dilutes the overall visibility results achieved from 
potential control options, and is therefore less relevant than the 98th 
percentile. Furthermore, while the 98th percentile day reflects 
visibility benefits on the days on which the sources have the largest 
impacts, the State has not indicated that the 90th percentile day has 
any particular significance other than to provide an additional metric 
to consider. We also acknowledge that the difference between BART and 
the BART Alternative using the 90th percentile is relatively small 
(0.006 dv). Additionally, we disagree with commenters that suggested 
the 90th percentile metric is similar to the 20% worst day metric; the 
90th percentile relates to a single value, the 110th highest impact day 
across three years for the scenario considered (i.e., BART Alternative 
or BART Benchmark), whereas the 20% worst days metric describes 
visibility impacts from all sources on the average of the 20% worst 
visibility days. Therefore, while we considered the results from the 
90th percentile to evaluate the State's weight-of-evidence analysis, we 
placed a very small amount of weight on this metric, and therefore find 
that this metric only marginally supports the BART Alternative.
---------------------------------------------------------------------------

    \42\ In our North Dakota final action we explained that EPA 
addressed the appropriate interpretation of CALPUFF modeling results 
in the BART Guidelines within the context of subject-to-BART 
modeling and we rejected the use of the 90th percentile because it 
would be inconsistent with the Act. We explained that the use of the 
90th percentile value would effectively allow visibility effects 
that are predicted to occur at the level of the threshold (or 
higher) on 36 or 37 days a year. 70 FR 39121.
---------------------------------------------------------------------------

vi. Timing of the Emissions Reductions
    The State's regional haze SIP submittal included statements in the 
greater reasonable progress than BART analysis that the NOX 
reductions from Huntington Units 1 and 2 and Hunter

[[Page 43900]]

Units 2 and 3 occurred earlier than was required by the rule, providing 
corresponding early and ongoing visibility improvement under the 
Alternative as compared to the BART Benchmark, citing to WildEarth 
Guardians v. EPA. 770 F.3d 919, 938 (10th Cir. 2014).\43\
---------------------------------------------------------------------------

    \43\ Utah Staff Review Report at 11, 27 (``The NOX 
reductions at Huntington 1 and 2 and Hunter 2 and 3 occurred between 
2006 and 2011, earlier than was required by the rule, providing an 
early and on-going visibility improvement'' and offering in footnote 
14 that ``[the] U.S. Circuit Court of Appeals for the 10th Circuit 
explicitly acknowledged that the consideration of early reductions 
was proper as part of a qualitative or clear weight of evidence 
approach to determining greater reasonable progress.'' (citing 
WildEarth Guardians v. EPA, 770 F.3d 919, 938 (10th Cir. 2014)). EPA 
agrees that it is appropriate to consider the timing of emission 
reductions for the Utah BART Alternative.
---------------------------------------------------------------------------

    The State further asserted that the timing of emission reductions 
provided support for the weight-of-evidence determination that the BART 
Alternative will provide greater reasonable progress than BART. We 
assessed the State's evidence for this metric and recognized that the 
reductions from the BART Alternative would occur before the BART 
Benchmark because the controls at the Hunter and Huntington facilities 
have been achieving significant NOX reductions since the 
time of their installation between 2006 and 2014.\44\
---------------------------------------------------------------------------

    \44\ 81 FR 2004, 2030.
---------------------------------------------------------------------------

    As a result of the comments received on our co-proposal, we have 
further assessed the State's evidence for this metric. We considered 
the State's early emission reduction statement in our evaluation of the 
State's weight-of-evidence analysis because the reductions relate to 
assessing visibility impacts. We note that the State's weight-of-
evidence analysis presents and considers only the early timing of 
emission reductions from the Hunter and Huntington units at which 
controls were installed before 2014.\45\
---------------------------------------------------------------------------

    \45\ Utah Staff Review Report at 11.
---------------------------------------------------------------------------

    We find that the timing of emissions reductions metric, which 
considers the early reductions from Hunter Units 2 and 3 and Huntington 
Units 1 and 2, supports a finding that the BART Alternative is better 
than BART.
vii. Monitoring Data at the Class I Areas (IMPROVE Network)
    The State's regional haze SIP submittal determined that the BART 
Alternative provides greater reductions of SO2 \46\ and that 
SO2 is the most significant anthropogenic pollutant 
affecting Class I Areas that impacts visibility year-round, including 
throughout the high visitation seasons at the National Parks in spring, 
summer, and fall.\47\ The State thus concluded, working from 
assumptions regarding sulfate and nitrate formation based on historical 
trend data,\48\ that the BART Alternative will provide greater 
reasonable progress than BART.
---------------------------------------------------------------------------

    \46\ Id. at 27.
    \47\ Id. at 27.
    \48\ Id. at 12-19.
---------------------------------------------------------------------------

    We assessed the State's evidence for this metric and proposed to 
concur with one of the State's findings. We proposed to find that 
visibility benefits associated with NOX reductions are much 
more likely to occur in the winter months because this is when aerosol 
thermodynamics favors nitrate formation, while SO2 emissions 
reductions should provide visibility benefits in all seasons. We also 
proposed to find that, as concluded by the Grand Canyon Visibility 
Transport Commission (GCVTC), and supported by the IMPROVE monitoring 
data presented by Utah, anthropogenic visibility impairment on the 
Colorado Plateau is dominated by sulfates. Therefore, we proposed to 
concur with Utah's statement that sulfate is the largest contributor to 
visibility impairment at the affected Class I areas.
    We proposed to disagree with the State's findings related to park 
visitation. While we explained that the BART Guidelines do mention 
visitation as something that can inform a control decision, EPA 
proposed to place little weight on the State's correlation of emissions 
reductions and park visitation because nothing in the CAA suggests that 
visitors during busy time periods are entitled to experience better 
visibility than visitors during off-peak periods.
    As the result of the comments received on our co-proposal, we have 
further assessed the State's evidence for this metric and while we have 
clarified our assessment, our overall findings remain the same. We 
considered this metric in our evaluation of the State's weight-of-
evidence analysis because the monitoring data relate to assessing 
visibility impacts. We conducted an analysis of 2013 and 2014 IMPROVE 
monitoring data for Canyonlands, the most impacted Class I area,\49\ 
considering seasonal averages and the 20% best and worst days.\50\ Our 
analysis confirms that sulfate is a large contributor to light 
extinction year round and that nitrate contributions are highest in the 
winter season. Nonetheless, overall nitrate extinction at the affected 
areas is significant, particularly on the 20% worst days. We have taken 
the strength of the modeling results for winter months into 
consideration; however, contrary to the State's and other's suggestions 
that visibility improvements during seasons of peak Class I area 
visitation should carry more weight, we evaluate the visibility impacts 
for an entire year, regardless of the season. Therefore, we decided to 
place little weight on this metric and find that the monitoring data 
analysis metric in Utah's weight-of-evidence analysis only marginally 
shows the BART Alternative is better than the BART Benchmark.
---------------------------------------------------------------------------

    \49\ Canyonlands was the most impacted Class I area in the 
State's BART Alternative modeling that assessed the visibility 
impacts from all three power plants (i.e., Hunter, Huntington, and 
Carbon), as well as most impacted in EPA's modeling assessing the 
visibility impacts for the BART Benchmark for Hunter and Huntington.
    \50\ See spreadsheet entitled, EPA Analysis of 2013 and 2014 
IMPROVE Monitoring Data for Canyonlands, in the docket. More 
detailed information regarding this analysis is available in section 
II.E of this document and in our RTC document.
---------------------------------------------------------------------------

viii. Energy and Non-Air Quality Benefits
    The State's regional haze SIP submittal indicated in its weight-of-
evidence assessment that the BART Alternative would avoid the energy 
penalty associated with operating the SCR units, i.e., the controls 
assumed under the BART Benchmark. The State also cited non-air quality 
benefits of its Alternative, including lower fly ash production and 
reduced water usage associated with the shutdown of Carbon. However, 
the State's ``Summary of the Weight of Evidence,'' which presented a 
summary and short evaluation of each of the metrics, did not reference 
this assessment.\51\
---------------------------------------------------------------------------

    \51\ Utah Staff Review Report at 27.
---------------------------------------------------------------------------

    We assessed the State's evidence for this metric and proposed to 
find that because the benefits do not have direct bearing on whether 
the BART Alternative achieves greater reasonable progress, it is not 
material to our action whether we agree or disagree with Utah's 
assessment that the Alternative would reduce energy and non-air quality 
impacts relative to BART.
    As a result of the comments received on our co-proposal, we have 
further assessed the State's evidence for this metric; however, we have 
decided not to alter our proposed finding. The purpose of a weight-of-
evidence analysis is to determine whether a BART Alternative would 
achieve greater reasonable progress, which is measured in terms of 
visibility improvement.\52\ Thus, only metrics that are indicative of 
improvements in visibility are relevant in a weight-of-evidence 
analysis. Energy

[[Page 43901]]

and non-air quality impacts do not provide relevant information on the 
relative visibility benefit of a BART Alternative as compared to BART. 
We, therefore, did not assign this metric any weight in our evaluation 
of the State's weight-of-evidence conclusion.
---------------------------------------------------------------------------

    \52\ 40 CFR 51.308(d)(1), (e)(2)(i)(E).
---------------------------------------------------------------------------

ix. Cost
    The State's regional haze SIP indicated in its weight-of-evidence 
assessment that, although the State had not officially determined the 
cost of BART, it is clear that the BART Alternative would have 
significant capital cost savings to PacifiCorp and its customers. The 
submittal noted that the Carbon Plant has already been closed and the 
cost to ratepayers of replacing the power generated by that facility 
have already occurred. However, the State's ``Summary of the Weight of 
Evidence,'' which presented a summary and short evaluation of each of 
the metrics, did not reference the cost comparison.\53\
---------------------------------------------------------------------------

    \53\ Utah Staff Review Report at 27.
---------------------------------------------------------------------------

    We assessed the State's evidence for this metric and proposed to 
find that because the described cost difference does not have a direct 
bearing on whether the BART Alternative achieves greater reasonable 
progress, it is not material to our action whether we agree or disagree 
with Utah's conclusion that the BART Alternative would have a lower 
cost impact to PacifiCorp than the BART Benchmark (i.e., costs provided 
by PacifiCorp in its BART analyses of August 5, 2014, SIP TSD Chapter 
2).
    As a result of the comments received on our co-proposal, we have 
further assessed the State's evidence for this metric; however, we have 
decided not to alter our proposed finding. The purpose of a weight-of-
evidence analysis is to determine whether a BART Alternative would 
achieve greater reasonable progress, which is measured in terms of 
visibility improvement.\54\ The difference in the capital costs between 
BART and the BART Alternative does not provide information relevant to 
the scenarios' relative visibility benefits.\55\ We therefore did not 
assign this metric any weight in our evaluation of the State's weight-
of-evidence conclusion.
---------------------------------------------------------------------------

    \54\ 40 CFR 51.308(d)(1), (e)(2)(i)(E).
    \55\ We also note that, consistent with our statements in the 
BART Guidelines, the capital cost of controls would not be a 
relevant consideration because it does not take into account the 
degree of visibility improvement associated with those controls. 40 
CFR part 51, appendix Y, section IV.D.4.g. Therefore, even if we did 
consider cost as relevant in a weight-of-evidence analysis, which we 
do not, the capital cost of controls would not be the appropriate 
metric.
---------------------------------------------------------------------------

x. EPA's Evaluation of the State's Conclusions
    The State's regional haze SIP submittal suggested that eight of the 
nine metrics considered by Utah support the BART Alternative, finding 
that one metric, the 98th percentile CALPUFF modeling metric did not 
support its BART Alternative. As explained earlier in this section, 
evidence in the SIP and from commenters demonstrates that four of these 
metrics have documented weaknesses and only marginally support the BART 
Alternative: Improvement in the number of days with significant 
visibility impairment predicted by modeling (analyzed using different 
thresholds); the annual average visibility impacts predicted by 
modeling; monitoring data trends collected at the Class I areas; and 
the 90th percentile impacts predicted by modeling. Additionally, while 
the timing of emission reductions metric does favor the State's BART 
Alternative, the emission reductions at issue are only a portion of the 
overall emission reductions claimed under the Alternative. The timing 
of these emission reductions does not alter our conclusion that, on 
balance, the Alternative has not been shown to result in greater 
visibility benefits than would BART. Finally, we did not assign any 
weight to three metrics in our evaluation of the State's weight-of-
evidence analysis because we determined that the metrics for energy and 
non-air quality and cost considerations are not related to visibility 
and have no bearing on whether the BART Alternative achieves greater 
reasonable progress than the BART Benchmark, and that information from 
the annual emissions comparison of all visibility-impairing pollutants 
metric was inconclusive.
    When we weighed the State's metrics (excluding the energy and non-
air quality and cost metrics) that evaluate visibility collectively, 
considering the strengths and weaknesses of each metric and the 
magnitude of the differences in visibility benefit between BART and the 
Alternative, we find that it was not reasonable for the State to 
determine that the clear weight of the evidence favors the BART 
Alternative for the following reasons. We find that the State's 
characterization of the 98th percentile modeling results, the one 
metric that did not support its BART Alternative, was contrary to EPA's 
established interpretation of and reliance on that metric. The 98th 
percentile CALPUFF modeling metric takes into account peak visibility 
impacts and carries the most weight. The 98th percentile visibility 
impact is a key metric recommended by the BART Guidelines and EPA has 
relied on this metric in evaluating prior regional haze actions that 
have included BART alternatives.\56\ Furthermore, two factors which 
marginally support the BART Alternative (annual average modeled impact 
and 90th percentile modeled impact) are given little weight because 
they are considered to be less relevant metrics and show very small 
differences between the BART Alternative and the BART Benchmark, while 
another factor which marginally supports the BART Alternative (results 
from IMPROVE monitoring data) is also given little weight because of 
the need to consider visibility impacts during all times of the year, 
not just during peak visitation periods. Another factor which 
marginally supports the BART Alternative (improvement in number of days 
with significant visibility impairment) is given little weight because 
even though the BART Alternative is favored using a 0.5 dv threshold, 
the 1.0 dv threshold does not show that the BART Alternative is better. 
In addition, although a portion of the emission reductions under the 
Alternative were achieved prior to 2014, this does not diminish our 
fundamental finding that the quantity of reductions available under the 
Alternative would not result in greater visibility improvements than 
the emission reductions under BART. Therefore, the visibility metrics 
that favor the BART Alternative neither individually nor collectively 
clearly demonstrate that the BART Alternative will achieve greater 
reasonable progress at the nine Class I areas when weighed against 
visibility benefits predicted by the 98th percentile modeling results 
under BART.
---------------------------------------------------------------------------

    \56\ See, e.g., 78 FR 79344 (Dec. 30, 2012) (proposed rule, FIP 
for Tesoro Refining and Intalco Refinery BART Alternatives); 79 FR 
33438 (June 11, 2014) (final rule, FIP for Tesoro Refining and 
Intalco Refinery BART Alternatives); 79 FR 56322, 56328 (Sept. 19, 
2014) (proposed approval of Arizona Apache BART Alternative); 80 FR 
19220 (Apr. 10, 2015) (final approval of Arizona Apache BART 
Alternative).
---------------------------------------------------------------------------

    In summary, we have relied on the standards contained in the RHR 
and the authority that Congress granted us to review SIPs to determine 
whether the State's SIP submittal complies with the minimum statutory 
and regulatory requirements. In determining SIP adequacy, we must 
exercise our judgment and expertise regarding complex technical issues, 
and it is entirely appropriate that we do so. Courts have recognized 
this necessity and deferred to our exercise of

[[Page 43902]]

discretion when reviewing SIPs.\57\ We thus review a state's SIP 
submittal with the understanding that the state's discretion in 
developing an alternative measure ``is subject to the condition that it 
must be reasonably exercised and that its decision is supported by 
adequate documents of its analysis.'' \58\ In the present 
circumstance--as discussed in more detail in the proposed action and 
this final action--EPA was not able to find that the weight-of-evidence 
analysis satisfied the relevant regulatory requirements. Specifically, 
we find:
---------------------------------------------------------------------------

    \57\ See, e.g., Connecticut Fund for the Env't., Inc. v. EPA, 
696 F.2d 169 (2d Cir. 1982); Michigan Dep't. of Envtl. Quality v. 
Browner, 230 F.3d 181 (6th Cir. 2000); Montana Sulphur & Chem. Co. 
v. EPA, 2012 U.S. App. LEXIS 1056 (9th Cir. Jan. 19, 2012).
    \58\ 71 FR 60612, 60621 (Oct. 13, 2006).
---------------------------------------------------------------------------

    (1) The State's assessment of the metrics it found to support its 
BART Alternative was inadequate because it did not evaluate the 
relative strengths and weaknesses of the visibility metrics on an 
individual basis;
    (2) The State did not consider the 98th percentile CALPUFF modeling 
metric, which did not support its BART Alternative, in a manner 
consistent with EPA's established interpretation of and reliance on 
that metric;
    (3) The State's assessment of the metric that considered aggregate 
annual emissions of visibility-impairing pollutants was contrary to 
EPA's established interpretation of and reliance on that metric;
    (4) The State's assessment relied on two metrics that are not 
consistent with the ``greater reasonable progress'' analysis because 
they are not related to visibility (energy and non-air quality and cost 
considerations);
    (5) The State did not satisfy the requirement that it assess the 
collective weight of its evidence in a reasonable and adequately 
supported manner; and
    (6) The SIP submittal lacked an explanation of why the information 
from all the metrics demonstrated that the difference in visibility 
impacts between BART and the Alternative was large enough to 
``clearly'' demonstrate that the BART Alternative would achieve greater 
reasonable progress than BART.\59\
---------------------------------------------------------------------------

    \59\ The State's assessment of the overall weight of evidence 
states only that ``[t]he weight of evidence shows that the 
alternative will provide greater reasonable progress than BART.'' 
Utah Staff Review Report at 27.
---------------------------------------------------------------------------

    Based on this evaluation, we find that, on balance, the evidence 
does not show that the Alternative clearly achieves greater visibility 
benefits than BART. Thus, the State has not satisfied the regulatory 
requirement in 40 CFR 51.308(e)(2) that a state's submittal of a BART 
alternative include a ``determination . . . based on the clear weight 
of evidence that the . . . alternative measure achieve greater 
reasonable progress than would be achieved through the installation and 
operation of BART at the covered sources.'' Therefore, we are 
disapproving the State's NOX BART Alternative contained in 
its June 4, 2015 SIP submittal, including the NOX emission 
limits for Hunter Units 1, 2, and 3; and the NOX emission 
limits for Huntington Units 1 and 2; and the requirements for permanent 
closure of Carbon Units 1 and 2.\60\
---------------------------------------------------------------------------

    \60\ We are disapproving SIP Sections IX.H.21, subsection (c), 
IX.H.22, subsections:.a.iii-iii., b.ii. and c. We are also 
disapproving SIP Section XX,D subsections: 6.a. (the provisions in 
the ``Regional Haze Rule BART Requirements'' that cover the 
NOX alternative measure); 6.c. (``BART for 
NOX, '' including footnote 4 that references the State's 
Analysis in a separate document); 6.d. (the provisions in the ``BART 
Summary'' that cover NOX and SO2 emissions, 
including the references to use of approval orders and permitted 
limits to establish the emission limits, the statement that ``the 
four EGUs also met the presumptive emission rates for both 
NOX and SO2 established in Appendix Y 
independently of the alternative programs'', and references in Table 
5 to ``Permitted'' (and the NOX and SO2 limits 
in that column), ``Hunter 3'', all provisions in the ``Presumptive 
BART Rates'' column NOX and SO2 emissions); 
6.e. (the provisions in ``Schedule for Installation of Controls'' as 
the dates refer to emissions for sources that are in the proposed 
BART Alternative; and the discussion immediately following Table 6 
that presents information about the emission limits also appearing 
in State-issued permits). Additional discussion appears in our RTC 
document.
---------------------------------------------------------------------------

d. Remaining BART Alternative Criteria
    The RHR establishes a number of additional regulatory criteria to 
be included in any demonstration that an alternative will provide for 
greater reasonable progress than BART. These criteria are set out at 40 
CFR 51.308(e)(2)(i)(A)-(D) and (e)(2)(iii)-(v). In both co-proposals, 
we proposed to find that Utah's SIP submittal addressing the BART 
Alternative met these requirements.\61\ We received adverse and 
supportive comments on our proposed finding that the State had met 
these remaining requirements. We respond to these comments in our RTC 
document.
---------------------------------------------------------------------------

    \61\ 81 FR at 2021, 2025-26, 2027-28, 2032
---------------------------------------------------------------------------

    Having carefully considered the comments received, we have 
concluded that the State's SIP submittal generally met most of these 
requirements, as explained in our RTC document. As a result, our 
partial disapproval of the State's SIP submittal is based on our 
assessment that Utah failed to demonstrate based on the weight of 
evidence that the BART Alternative would provide for greater reasonable 
progress and not on any deficiencies in the state's demonstration that 
it had met the additional regulatory criteria in 40 CFR 51.308(e)(2).
e. Monitoring, Recordkeeping and Reporting for Utah's BART Alternative
    Section IV.B.3 of Utah's June 2015 regional haze SIP included 
enforceable measures and monitoring, recordkeeping and reporting 
requirements for the Utah BART Alternative and the State's 
PM10 BART determinations. In our co-proposal we proposed to 
disapprove (in other words, to not make federally enforceable as part 
of the SIP) the monitoring, recordkeeping and reporting requirements 
located in SIP Sections IX.H.22 associated with the BART Alternative. 
This includes SIP Section IX.H.22, subsections a.ii, a.iii, b.ii, and 
c.i.\62\
---------------------------------------------------------------------------

    \62\ As explained later, our co-proposal proposed to approve or 
conditionally approve the remainder of the monitoring, recordkeeping 
and reporting requirements associated with Utah's PM10 
BART determinations.
---------------------------------------------------------------------------

    While we did not receive any comments on this element of Utah's 
regional haze SIP submittal in our co-proposal, the monitoring, 
recordkeeping, and reporting provisions in the submittal are linked 
directly to the emission limitations under the Alternative, which we 
are disapproving.\63\ Our partial disapproval of the State's SIP 
submittal is based on our assessment that Utah failed to demonstrate 
based on the weight of evidence that the BART Alternative would provide 
for greater reasonable progress and not on any deficiencies in the 
State's demonstration that it had met the monitoring, recordkeeping, 
and reporting requirements under the RHR.
---------------------------------------------------------------------------

    \63\ However, we note that we are proposing conditional approval 
of the following regulations in Section IX.H.21(e), as discussed in 
section I.B.2.
---------------------------------------------------------------------------

f. Basis for Our NOX BART Determinations and FIP
    Based upon comments we received on our proposed FIP, we revised our 
analysis of the cost of installing and operating NOX BART 
controls at the four subject-to-BART EGUs. In particular, and as 
discussed at length in our RTC document, we revised the costs in 
response to comments from PacifiCorp that we incorrectly re-designed 
the SCR reactors. Having carefully considered the comments received, we 
concluded it was unnecessary to revise our analysis of visibility 
improvement or the other statutory BART factors. Our proposed action 
contains a full description of the five step BART analysis, the five 
BART factors, and our proposed BART determination. Because we have 
revised

[[Page 43903]]

our cost analysis, we provide updated tables containing the results of 
the cost analyses, including the summary tables that also show the 
visibility improvements associated with the controls under 
consideration (which we did not revise). Following these tables, we 
provide our final BART determination. Because the Hunter and Huntington 
BART units are similar, our reasoning for the final BART determination 
applies to all four units. Table 1 shows the NOX BART 
control technologies, associated cost, emission reductions, and the 
BART emission limitation for each source that is subject to the FIP. 
The costs in Table 1 reflect EPA's revised cost analysis. Please note 
that the cost-effectiveness values for SCR with low-NOX 
burners and separated overfire air (SCR + LNB/SOFA) were computed using 
an assumed emission rate of 0.05 lb/MMBtu on an annual basis, but for 
compliance purposes the NOX emission limit for each unit is 
0.07 lb/MMBtu, 30-day rolling average.

  Table 1--Emission Limits, Costs, and Cost Effectiveness for LNBs/SOFA With SCR for the Sources Subject to the
                                                       FIP
----------------------------------------------------------------------------------------------------------------
                                                   NOX Emission
                                                    limit--lb/                         Total       Average cost-
             Source                Technology *   MMBtu  (30-day   Total capital    annualized     effectiveness
                                                      rolling        cost  ($)       cost  ($)        ($/ton)
                                                     average)
----------------------------------------------------------------------------------------------------------------
Hunter Unit 1...................  SCR + LNB/SOFA            0.07         $130.6M          $14.8M          $2,697
Hunter Unit 2...................  SCR + LNB/SOFA            0.07          128.5M           14.5M           2,774
Huntington Unit 1...............  SCR + LNB/SOFA            0.07          128.3M           14.6M           2,871
Huntington Unit 2...............  SCR + LNB/SOFA            0.07          130.0M           14.7M           2,928
----------------------------------------------------------------------------------------------------------------
* The technology listed is the technology evaluated as BART, but sources can choose to use another technology or
  combination of technologies to meet established limits.

    Tables 2 and 3 provide summaries of EPA's NOX BART 
analysis of all feasible control options for Hunter Units 1 and 2, 
including the costs of compliance and visibility impacts. Please refer 
to our discussion in section I.B.1.f in regard to how we selected BART 
from among these control options.

                                            Table 2--Summary of EPA's Hunter Unit 1 NOX BART Impacts Analysis
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                          Annual                   Total                                                     Visibility impacts *
                                         emission    Emission     annual     Average cost      Incremental cost     ------------------------------------
            Control option              rate  (lb/   reduction     costs    effectiveness   effectiveness  ($/ton)   Improvement  Days > 0.5  Days > 1.0
                                          MMBtu)       (tpy)    (million$)      ($/ton)                                  (dv)         dv          dv
--------------------------------------------------------------------------------------------------------------------------------------------------------
LNB with SOFA.........................        0.21       3,042       $1.2M          $382   ........................        0.846    330 (29)    218 (22)
LNB with SOFA and SNCR................        0.16       3,735        3.8M         1,016   3,796...................        1.041    322 (37)    202 (38)
LNB with SOFA and SCR.................        0.05       5,500       14.8M         2,697   6,255 (compared to LNB          1.545    311 (48)    188 (52)
                                                                                            with SOFA and SNCR)
                                                                                            5,561 (compared to LNB
                                                                                            with SOFA).
--------------------------------------------------------------------------------------------------------------------------------------------------------
* At the most impacted Class I area, Canyonlands National Park. The improvement in days over 0.5 and 1.0 dv provided by the control option relative to
  the baseline is presented in parentheses. See Table H.9. Air Quality Modeling Protocol: Utah Regional Haze Federal Implementation Plan, US EPA Region
  8 (Nov. 2015); Docket Id. EPA-R08-OAR-2015-0463-0012.

                                            Table 3--Summary of EPA's Hunter Unit 2 NOX BART Impacts Analysis
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                          Annual                   Total                                                     Visibility impacts *
                                         emission    Emission     annual     Average cost      Incremental cost     ------------------------------------
            Control option              rate  (lb/   reduction     costs    effectiveness   effectiveness  ($/ton)   Improvement  Days > 0.5  Days > 1.0
                                          MMBtu)       (tpy)    (million$)      ($/ton)                                  (dv)         dv          dv
--------------------------------------------------------------------------------------------------------------------------------------------------------
LNB with SOFA.........................        0.20       2,902       $0.9M          $298   ........................        0.658    336 (23)    221 (19)
LNB with SOFA and SNCR................        0.16       3,562        3.5M           968   3,913...................        0.822    331 (28)    218 (22)
LNB with SOFA and SCR.................        0.05       5,230       14.5M         2,774   6,632 (compared to LNB          1.250    317 (42)    198 (42)
                                                                                            with SOFA and SNCR)
                                                                                            5,861 (compared to LNB
                                                                                            with SOFA).
--------------------------------------------------------------------------------------------------------------------------------------------------------
* At the most impacted Class I area, Canyonlands National Park. The improvement in days over 0.5 and 1.0 dv provided by the control option relative to
  the baseline is presented in parentheses. See Table H.10. Air Quality Modeling Protocol: Utah Regional Haze Federal Implementation Plan, US EPA Region
  8 (Nov. 2015); Docket Id. EPA-R08-OAR-2015-0463-0012.

    Tables 4 and 5 provide summaries of EPA's NOX BART 
analysis of all feasible control options for Huntington Units 1 and 2, 
including the costs of compliance and visibility impacts.

[[Page 43904]]

                                          Table 4--Summary of EPA's Huntington Unit 1 NOX BART Impacts Analysis
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                          Annual                   Total                                                     Visibility impacts *
                                         emission    Emission     annual     Average cost      Incremental cost     ------------------------------------
            Control option              rate  (lb/   reduction     costs    effectiveness   effectiveness  ($/ton)   Improvement  Days > 0.5  Days > 1.0
                                          MMBtu)       (tpy)    (million$)      ($/ton)                                  (dv)         dv          dv
--------------------------------------------------------------------------------------------------------------------------------------------------------
LNB with SOFA.........................        0.22       2,440       $0.8M          $332   ........................        0.851    249 (28)    153 (22)
LNB with SOFA and SNCR................        0.17       3,185        3.5M          1098   3,609...................        1.113    244 (33)    143 (32)
LNB with SOFA and SCR.................        0.05       5,092       14.6M         2,871   5,830 (compared to LNB          1.881    210 (67)    117 (58)
                                                                                            with SOFA and SNCR)
                                                                                            5,206 (compared to LNB
                                                                                            with SOFA).
--------------------------------------------------------------------------------------------------------------------------------------------------------
* At the most impacted Class I area, Canyonlands National Park. The improvement in days over 0.5 and 1.0 dv provided by the control option relative to
  the baseline is presented in parentheses. See Table H.11. Air Quality Modeling Protocol: Utah Regional Haze Federal Implementation Plan, US EPA Region
  8 (Nov. 2015); Docket Id. EPA-R08-OAR-2015-0463-0012.

                                          Table 5--Summary of EPA's Huntington Unit 2 NOX BART Impacts Analysis
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                          Annual                   Total                                                     Visibility impacts *
                                         emission    Emission     annual     Average cost      Incremental cost     ------------------------------------
            Control option              rate  (lb/   reduction     costs    effectiveness   effectiveness  ($/ton)   Improvement  Days > 0.5  Days > 1.0
                                          MMBtu)       (tpy)    (million$)      ($/ton)                                  (dv)         dv          dv
--------------------------------------------------------------------------------------------------------------------------------------------------------
LNB with SOFA.........................        0.21       2,576       $0.9M          $365   ........................        0.776    254 (23)    153 (22)
LNB with SOFA and SNCR................        0.17       3,264        3.5M         1,075   3,730...................        1.016    244 (33)    149 (26)
LNB with SOFA and SCR.................        0.05       5,023       14.7M         2,928   6,368 (compared to LNB          1.657    220 (57)    126 (49)
                                                                                            with SOFA and SNCR)
                                                                                            5,626 (compared to LNB
                                                                                            with SOFA).
--------------------------------------------------------------------------------------------------------------------------------------------------------
* At the most impacted Class I area, Canyonlands National Park. The improvement in days over 0.5 and 1.0 dv provided by the control option relative to
  the baseline is presented in parentheses. See Table H.12. Air Quality Modeling Protocol: Utah Regional Haze Federal Implementation Plan, US EPA Region
  8 (Nov. 2015); Docket Id. EPA-R08-OAR-2015-0463-0012.

    In our final BART determinations, we have taken into consideration 
all five of the statutory factors required by the CAA: Costs of 
compliance, energy and non-air quality environmental impacts of 
compliance, any existing pollution control technology in use at the 
source, remaining useful life of the source, and degree of improvement 
in visibility which may reasonably be anticipated to result from the 
use of such technology.
    We received some comments on our proposed consideration of 
remaining useful life and energy and non-air quality environmental 
impacts. However, we have not changed our evaluation from the proposal 
of the energy and non-air quality environmental impacts of compliance 
and the remaining useful lives of the sources. We find that the 
remaining useful life of the Hunter and Huntington units of at least 
twenty years is considerable and does not require us to revise our 
amortization period for the costs of controls. We also find that the 
energy and non-air quality environmental impacts of the various control 
options do not significantly favor one option over another. Please see 
the proposal action and our RTC document for details.
    We also received comments on our proposed consideration of existing 
pollution control technology in use at the source, in this case LNB/
SOFA at all four BART units. For reasons explained later in the 
preamble and in our RTC document, we continue to use a baseline period 
for emissions (2001-2003) that predates the installation of LNB/SOFA at 
the four BART units. We have considered the existing LNB/SOFA in 
several other ways. First, we considered them in selecting the control 
options to analyze for BART. Second, we considered them in determining 
the impacts of the control options, both by taking the LNB/SOFA into 
account in determining the proper NOX rates for the post-
combustion control options (selective non-catalytic reduction (SNCR) 
and SCR), and in computing the incremental cost-effectiveness values in 
the tables earlier. We also consider the existing LNB/SOFA in our 
discussion of incremental visibility benefits later. As explained later 
in the preamble and in our RTC document, this is a reasonable approach 
and consistent with other actions.
    We now discuss the remaining factors, the costs of compliance and 
the degree of visibility improvement, and how we are weighing them in 
determining BART. At this point in time, EPA and the states have made a 
number of BART determinations for large coal-fired EGUs. EPA is taking 
into account the BART decisions made in other states to help frame our 
assessment of the cost and visibility benefits of control options in 
this action.\64\ Specifically, we have compared the average cost-
effectiveness, incremental cost-effectiveness, visibility improvement, 
and incremental visibility improvement for the selected BART controls, 
SCR + LNB/SOFA, with BART determinations for coal-fired EGUs where the 
EPA and states have based those determinations on the same or similar 
metrics.
---------------------------------------------------------------------------

    \64\ As discussed in our proposal action, in the context of 
reasonable progress determinations, a comparison with another 
reasonable progress determination has been upheld by the Ninth 
Circuit Court of Appeals as a rational explanation for that 
determination. Nat'l Parks Conserv. Ass'n v. U.S. EPA, 788 F.3d 
1134, 1148-49 (9th Cir. 2014).
---------------------------------------------------------------------------

    The most comparable determination is in EPA's final action on 
Wyoming's regional haze SIP, in which EPA promulgated a FIP for three 
units at Laramie River Station and determined NOX BART to be 
SCR + LNB/SOFA for the three units.\65\ On a per-unit basis, the 
visibility improvement at the most impacted Class I area from this 
control option ranged from 0.52 to 0.57 dv, and across all three units 
the sum of the improvement was 1.62 dv.\66\ Thus, applying this control 
option to all three units of Laramie River Station was estimated to 
have a visibility benefit

[[Page 43905]]

about the same as applying the same control option to just one of the 
Hunter and Huntington BART units (the visibility benefits in today's 
action at the most impacted Class I area range from 1.25 dv at Hunter 
Unit 2 to 1.881 dv at Huntington Unit 1). The visibility benefits of 
SCR + LNB/SOFA at Hunter or Huntington as a whole (2.948 dv for Hunter, 
3.848 dv for Huntington) are significantly greater than at Laramie 
River Station.
---------------------------------------------------------------------------

    \65\ 79 FR 5032, 5047 (Jan. 30, 2014).
    \66\ As explained in our proposal, the BART Guidelines require 
consideration of the visibility improvement from the use of BART 
controls applied to the collection of emissions units that make up 
the BART source. Although this requires consideration of the 
visibility improvement from BART applied to the subject-to-BART 
source as a whole, states (and EPA) may also include the visibility 
benefits on a per unit basis as well in their evaluation of the BART 
factors. In this action we have considered both the per-unit 
visibility benefits as well as the source-wide visibility benefits. 
The source-wide visibility benefits of our selected BART control, 
SCR + LNB/SOFA, at all nine impacted Class I areas are presented and 
discussed later.
---------------------------------------------------------------------------

    The average cost-effectiveness for SCR + LNB/SOFA at Laramie River 
Station ranged from $4,375/ton to $4,461/ton, considerably higher than 
the corresponding values of $2,697/ton to $2,928/ton for the Hunter and 
Huntington BART units. The incremental cost-effectiveness for SCR + 
LNB/SOFA at Laramie River Station as compared to SNCR + LNB/SOFA ranged 
from $5,449 to $5,871/ton, which is generally in line with the 
corresponding values for the Hunter and Huntington BART units, $5,830/
ton to $6,632/ton. Finally, the incremental visibility improvement for 
SCR + LNB/SOFA at the most impacted Class I area as compared to SNCR + 
LNB/SOFA for Laramie River Station was significant (0.25 dv to 0.29 
dv), but is even more so for the Hunter and Huntington BART units 
(0.428 dv at Hunter Unit 2 to 0.748 dv at Huntington Unit 1). Thus, the 
selection of SCR + LNB/SOFA at the Hunter and Huntington BART units is 
very much in line with the selection of SCR + LNB/SOFA at Laramie River 
Station. This is particularly true given that Laramie River Station 
impacts four Class I areas, while the Hunter and Huntington BART units 
impact nine Class I areas.
    In the same Wyoming action, our BART determinations for Dave 
Johnston Units 3 and 4 also provide a useful comparison. At Unit 3, we 
selected SCR + LNB/OFA as BART based on an assumed 20-year remaining 
useful life. Under that assumption, the average cost-effectiveness and 
incremental cost-effectiveness (as compared to SNCR + LNB/OFA) were 
$2,635/ton and $7,583/ton, respectively. We found these costs 
reasonable in light of a 0.51 dv improvement and a 0.12 dv incremental 
improvement at the most impacted Class I area. The average cost-
effectiveness of SCR + LNB/SOFA at the Hunter and Huntington BART 
units, $2,697/ton to $2,928/ton, is comparable, while the incremental 
cost-effectiveness of SCR + LNB/SOFA at the Hunter and Huntington BART 
units, $5,830/ton to $6,830/ton, is less than at Dave Johnston Unit 3. 
On the other hand, the visibility benefit and incremental visibility 
benefit of SCR + LNB/SOFA at the Hunter and Huntington BART units is 
considerably higher than that at Dave Johnston Unit 3, and the Hunter 
and Huntington BART units impact nine Class I areas as compared to five 
for Dave Johnston Unit 3. Thus, the selection of SCR + LNB/SOFA for the 
Hunter and Huntington BART units is very much in line with our BART 
determination for Dave Johnston Unit 3 (assuming a remaining useful 
life of 20 years).
    In the Wyoming action, at the request of PacifiCorp we also 
analyzed an alternative compliance scenario for Dave Johnston Unit 3 
that assumed a shutdown in 2027 and correspondingly a 9-year remaining 
useful life. As explained in the BART Guidelines, for BART units with a 
relatively short remaining useful life--in other words, less than the 
time period used for amortizing costs, which in this case was 20 
years--the shorter time period can be used to amortize costs instead. 
Effectively, this increases the cost-effectiveness values; in the case 
of Dave Johnston Unit 3, the average and incremental cost-effectiveness 
of SCR + LNB/OFA increased to $3,742/ton and $11,781/ton, respectively. 
Considering these values against the visibility benefits, we found that 
the incremental cost-effectiveness of SCR + LNB/OFA in this instance 
was not reasonable. Of course, for the Hunter and Huntington BART units 
the incremental cost-effectiveness is much lower than this scenario and 
in line with the previous scenario assuming a 20-year remaining useful 
life, for which we selected SCR + LNB/OFA as BART. Similarly, for Dave 
Johnston Unit 4, as for the 9-year remaining useful life scenario for 
Unit 3, we rejected SCR + LNB/OFA due to a high incremental cost-
effectiveness of $13,312. This is again consistent with our 
determination here, given the much lower incremental cost-effectiveness 
numbers for SCR + LNB/SOFA at the Hunter and Huntington BART units.
    There are other BART determinations in which SCR has been selected 
as BART (either alone or in conjunction with LNB and SOFA) based on 
similar metrics, although those determinations may not have explicitly 
discussed incremental cost-effectiveness and incremental visibility 
benefits on a per-unit basis. First, the State of Colorado selected, 
and the EPA approved, SCR as NOX BART for Public Service 
Company's Hayden Station, Units 1 and 2.\67\ Hayden Units 1 and 2 were 
equipped with first generation LNB and over-fire air (OFA) installed in 
1999 as the result of a consent decree to address other CAA 
requirements.\68\ In its BART determination, Colorado considered these 
existing controls as given and included them in the baseline emissions, 
which is consistent with our approach here: Colorado included the 
Hayden combustion controls in the baseline because they were not 
installed for a proposed BART determination but for other CAA purposes. 
In contrast, we do not include the combustion controls at Hunter and 
Huntington because they were installed pursuant to a proposed BART 
determination.\69\
---------------------------------------------------------------------------

    \67\ 77 FR 18069 (Mar. 26, 2012) (proposal); 77 FR 76871 (Dec. 
31, 2012) (final).
    \68\ Colorado Department of Health and Environment, Air 
Pollution Control Division, Technical Review Document, Renewal/
Modification of Operating Permit 96OPRO132, Public Service Company--
Hayden Station, Colorado, at 2 (2007-2008).
    \69\ We respond later in this action and in our RTC document 
about comments that this comparison should not be used because the 
baseline for Hayden included the existing controls.
---------------------------------------------------------------------------

    Colorado analyzed as feasible controls upgraded LNB, SNCR, and SCR. 
Based on an average cost-effectiveness of $3,385/ton and $4,064/ton, 
incremental cost-effectiveness (as compared with SNCR + the existing 
LNB/OFA) of $5,326/ton and $7,331/ton, and visibility improvement of 
1.12 dv and 0.85 dv at the most impacted Class I area, respectively, 
Colorado selected SCR (added to the existing LNB/OFA) as BART for Units 
1 and 2. The average cost-effectiveness of SCR + LNB/SOFA at the Hunter 
and Huntington BART units, $2,697/ton to $2,928/ton, compares favorably 
with the average cost-effectiveness of SCR at the Hayden units, and the 
incremental cost-effectiveness of SCR + LNB/SOFA at the Hunter and 
Huntington BART units, $5,830/ton to $6,632/ton, is generally in line 
with the incremental cost-effectiveness of SCR at the Hayden units. The 
visibility improvement from SCR + LNB/SOFA at the most impacted Class I 
area for the Hunter and Huntington BART units, from 1.25 dv to 1.881 
dv, compares favorably with the Hayden units. While Colorado appears to 
have not considered the incremental visibility benefits, these are also 
favorable for our selection of SCR + LNB/SOFA: 0.428 dv to 0.768 at the 
Hunter and Huntington units, as compared to 0.37 dv and 0.43 dv at 
Hayden Units 1 and 2, respectively. We also note that Hayden Station 
impacts eleven Class I areas, slightly more than Hunter and Huntington; 
however for six of those areas the impacts from Hayden Station are less 
than the impacts from Hunter and Huntington at the least

[[Page 43906]]

impacted Class I area, Zion National Park.\70\
---------------------------------------------------------------------------

    \70\ See BART CALPUFF Class I Federal Area Individual Source 
Attribution Visibility Impairment Modeling Analysis for Public 
Service Company of Colorado Hayden Station Units 1 and 2, Colorado 
Department of Public Health, at 48 (Nov. 1, 2005).
---------------------------------------------------------------------------

    Another comparable determination can be found in EPA's FIP for 
Arizona Public Service's Cholla Power Plant, Units 2, 3, and 4, in 
which EPA determined that NOX BART was SCR for all three 
units.\71\ Similar to Colorado's determination for Hayden, EPA included 
the existing controls, LNB and OFA, in the baseline for the three 
units.\72\ EPA estimated average cost-effectiveness values for SCR (as 
added to the existing LNB/OFA) of $3,114/ton, $3,472/ton, and $3,395/
ton; and incremental cost-effectiveness values (as compared to SNCR + 
LNB/OFA) of $3,257/ton, $3,811/ton, and $3,661/ton, respectively, for 
Units 2, 3, and 4. EPA's modeling showed a source-wide visibility 
improvement for SCR of 1.34 dv at the most impacted Class I area. In 
comparison, the source-wide visibility improvements at the most 
impacted Class I area for Hunter and Huntington from SCR + LNB/SOFA are 
much larger: 2.948 dv and 3.848 dv, respectively. While the average 
cost-effectiveness values at Cholla are somewhat higher than those for 
the Hunter and Huntington BART units, the incremental cost-
effectiveness of SCR at the Hunter and Huntington BART units is 
considerably higher, at $5,830/ton to $6,632/ton. Despite that 
disparity in incremental cost-effectiveness, this comparison still 
supports selection of SCR + LNB/SOFA for the Hunter and Huntington BART 
units, given the much greater magnitude of the visibility benefits and 
the fact that our other comparisons show the incremental cost-
effectiveness of SCR + LNB/SOFA is still reasonable. Finally, Cholla 
Power Plant does impact somewhat more Class I areas, thirteen as 
opposed to nine for Hunter and Huntington; however, were we to sum the 
baseline impacts of Hunter and Huntington, they would be greater than 
those for Cholla.
---------------------------------------------------------------------------

    \71\ 77 FR 42834 (July 20, 2012) (proposal); 77 FR 72512, 72514-
15 (Dec. 5, 2012) (final).
    \72\ In response to a comment about the use of this baseline, 
EPA explained that the three Cholla units had installed LNB/OFA and 
switched to a new source of coal with a much higher potential for 
NOX emissions. Thus, the LNB/OFA had not been installed 
pursuant to a proposed state BART determination; instead they appear 
to have been installed to accommodate the use of the new coal. This 
is again distinguishable from the situation for Hunter and 
Huntington.
---------------------------------------------------------------------------

    Based on these comparisons to Laramie River Station, Hayden 
Station, Dave Johnston Units 3 and 4, and Cholla Power Plant Units 2, 
3, and 4, the selection of LNB and SOFA with SCR as BART for the Hunter 
and Huntington BART units is fully justified.\73\ For these four units, 
LNB and SOFA with SCR is very cost-effective, at $2,697/ton to $2,928/
ton on an average basis (counting the costs and emission reductions 
from the combination of the three control technology elements), and at 
$5,830/ton to $6,632/ton on an incremental basis compared to LNB with 
SOFA and SNCR. Compared to LNB with SOFA, the incremental cost 
effectiveness of LNB and SOFA with SCR ranges from $5,206/ton to 
$5,861/ton, which is in line with the incremental cost effectiveness 
that supported the selection of LNB with SOFA and SCR for Laramie River 
Station. For the Hunter and Huntington BART units, LNB and SOFA with 
SCR provides substantial visibility benefits at several Class I areas 
that are similar in magnitude to those from Laramie River Station. For 
example, the visibility improvement from that control option installed 
on a single unit is 1.342 dv at Arches National Park, 1.545 dv at 
Canyonlands National Park, and 1.113 at Capitol Reef National Park. 
These comparisons show that costs are justified in light of the 
substantial visibility benefits, both total and incremental. In 
addition, for each unit, SCR + LNB/SOFA provides a significant 
improvement in the number of days over 0.5 dv as compared to the 
baseline (ranging from 42 days improvement at Hunter Unit 2 to 67 days 
improvement at Huntington Unit 1).
---------------------------------------------------------------------------

    \73\ As explained later and in our RTC document, we reject the 
comparisons to BART determinations in Montana, Florida, and 
Nebraska.
---------------------------------------------------------------------------

    As mentioned earlier, the BART Guidelines require consideration of 
the visibility improvement from the use of BART controls applied to the 
collection of emissions units that make up the BART source. Tables 6 
and 7 summarize the source-wide visibility improvements from the 
installation of SCR + LNB/SOFA at both BART units at Hunter and both 
BART units at Huntington, as well as the visibility improvements from 
the installation of SCR + LNB/SOFA at the other impacted Class I areas.

                                     Table 6--Summary of Source-Wide Visibility Impacts and Improvements for Hunter
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                    Baseline visibility impacts            BART (SCR + LNB/SOFA) Impacts  (Improvements
                                                         ------------------------------------------------       over baseline shown in parentheses)
                      Class I area                                                                       -----------------------------------------------
                                                           Impacts  (dv)   Days > 0.5 dv   Days > 1.0 dv   Impacts  (dv)   Days > 0.5 dv   Days > 1.0 dv
--------------------------------------------------------------------------------------------------------------------------------------------------------
Arches National Park (NP)...............................           4.601             293             170    1.981 (2.62)       158 (135)         71 (99)
Black Canyon NP.........................................           1.097              68              22   0.481 (0.616)         14 (54)          1 (21)
Bryce Canyon NP.........................................           1.833              42              22   0.811 (1.022)         20 (22)          6 (16)
Canyonlands NP..........................................           5.356             359             240   2.408 (2.948)       223 (136)       111 (129)
Capitol Reef NP.........................................           4.606             175             118   2.171 (2.435)        114 (61)         55 (63)
Flat Tops Wilderness....................................           1.281              77              31   0.537 (0.744)         22 (55)          1 (30)
Grand Canyon NP.........................................           1.891              49              32   0.730 (1.161)         25 (24)          9 (23)
Mesa Verde NP...........................................           1.327              82              32   0.514 (0.813)         21 (61)          4 (28)
Zion NP.................................................           0.963              29              14   0.369 (0.594)         10 (19)          4 (10)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: The baseline impacts are the combined impacts from all three units at Hunter, while the BART source is comprised of only units 1 and 2. EPA's
  evaluation of visibility under BART relies only on the visibility benefits associated with controls on the two BART units.

[[Page 43907]]

                                   Table 7--Summary of Source-Wide Visibility Impacts and Improvements for Huntington
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                    Baseline visibility impacts             BART (SCR + LNB/SOFA) impacts (improvements
                                                         ------------------------------------------------              shown in parentheses)
                      Class I area                                                                       -----------------------------------------------
                                                           Impacts (dv)    Days > 0.5 dv   Days > 1.0 dv   Impacts (dv)    Days > 0.5 dv   Days > 1.0 dv
--------------------------------------------------------------------------------------------------------------------------------------------------------
Arches NP...............................................           3.887             237             146   0.848 (3.039)        67 (170)        18 (128)
Black Canyon NP.........................................           0.773              45              16   0.196 (0.577)          1 (44)          0 (16)
Bryce Canyon NP.........................................           1.221              36              19   0.326 (0.895)          4 (32)          0 (19)
Canyonlands NP..........................................           5.130             277             175   1.282 (3.848)        89 (188)        31 (144)
Capitol Reef NP.........................................           3.389             131              91   0.986 (2.403)         42 (89)          9 (82)
Flat Tops Wilderness....................................           0.926              64              17   0.216 (0.710)          2 (62)          0 (17)
Grand Canyon NP.........................................           1.107              40              19   0.190 (0.806)          4 (36)          0 (19)
Mesa Verde NP...........................................           1.115              63              22   0.261 (0.854)          0 (63)          0 (22)
Zion NP.................................................           0.820              21              11   0.211 (0.609)          3 (18)          0 (11)
--------------------------------------------------------------------------------------------------------------------------------------------------------

    As can be seen from these tables, the baseline visibility impacts 
in dv at all nine Class I areas are large: Even at the least impacted 
Class I area, Zion National Park, Hunter and Huntington are each above 
the 0.5 dv threshold for contributing to visibility impairment. For 
Hunter, at the three most impacted Class I national park areas, Arches, 
Canyonlands and Capitol Reef, the baseline visibility impacts range 
from 4.601 dv to 5.356 dv. At these three Class I areas, the number of 
days with impacts over 0.5 dv and 1.0 dv range from 175 to 359, and 
from 118 to 240, respectively. The visibility benefits of BART (SCR + 
LNB/SOFA) at the three Class I areas are correspondingly large, ranging 
from 2.435 dv to 2.948 dv. The improvement in the number of days over 
0.5 dv and 1.0 dv at these three Class I areas are large as well, 
ranging from an improvement of 61 to 136 days in the number of days 
over 0.5 dv and 63 to 129 days in the number of days over 1.0 dv. Even 
at the least impacted Class I area, Zion National Park, the visibility 
benefits of BART are significant, 0.594 dv, and 19 and 10 days in the 
number of days over 0.5 dv and 1.0 dv, respectively. Consideration of 
these source-wide visibility benefits confirms that SCR + LNB/SOFA at 
Hunter is fully justified in light of its reasonable costs.
    For Huntington, at the three most impacted Class I national park 
areas, Arches, Canyonlands and Capitol Reef, the baseline visibility 
impacts range from 3.389 dv to 5.130 dv. At these three Class I areas, 
the number of days with impacts over 0.5 dv and 1.0 dv range from 131 
to 271, and from 91 to 175, respectively. The visibility benefits of 
BART (SCR + LNB/SOFA) at the three Class I areas are correspondingly 
large, ranging from 2.063 dv to 3.538 dv. The improvement in the number 
of days with impacts from Huntington over 0.5 dv and 1.0 dv at these 
three Class I areas are similar to those of Hunter. Huntington has 89 
fewer days with impacts over 0.5 dv at Capitol Reef, 170 fewer days 
with such impacts at Archers, and 188 fewer days at Canyonlands. The 
number of days Huntington has impacts over 1.0 dv at these areas falls 
by 82 to 144 days. Even at the least impacted Class I area, Zion 
National Park, the visibility benefits of BART are significant. BART is 
projected to result in a 0.609 dv improvement at Zion the number of 
days with impacts over 0.5 dv and 1.0 dv fall by 18 and 11 days, 
respectively. Consideration of these source-wide visibility benefits 
confirms that SCR + LNB/SOFA at Huntington, as at Hunter, is fully 
justified in light of its reasonable costs.
    Accordingly, for the Hunter and Huntington BART units, we find that 
BART for NOX is SCR + LNB/SOFA, represented by an emission 
limitation of 0.07 lb/MMBtu (30-day rolling average). The BART emission 
limitation of 0.07 lb/MMBtu allows for a sufficient margin of 
compliance for a 30-day rolling average limit that would apply at all 
times, including startup, shutdown, and malfunction.\74\ We are also 
finalizing our proposed monitoring, recordkeeping, and reporting 
requirements in our regulatory text for 40 CFR 52.2336; these 
requirements will ensure that the BART emission limitation is 
enforceable.
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    \74\ Emission limits such as BART are required to be met on a 
continuous basis. See 70 FR 39104, 39172 (July 6, 2005) (stating 
that emissions limits including BART are to be met on a ``continuous 
basis'' in the BART Guidelines, section V); 42 U.S.C. 7602(k) 
(noting that emission limits are to be on ``a continuous basis'').
---------------------------------------------------------------------------

    Under 40 CFR 51.308(e)(1)(iv), ``each source subject to BART [is] 
required to install and operate BART as expeditiously as practicable, 
but in no event later than five years after approval of the 
implementation plan revision.'' In light of the considerable effort 
involved to retrofit SCR, we determine that five years is as 
expeditiously as practicable. Therefore, the compliance deadline for 
the BART requirements will be five years from the date our final FIP 
becomes effective.
2. PM10 BART
    We are finalizing our proposed approval of Utah's PM10 
BART determinations for Hunter Units 1 and 2 and Huntington Units 1 and 
2. We have determined that Utah's PM10 BART determinations, 
emission limitations, and associated monitoring, recordkeeping and 
reporting for Hunter Units 1 and 2 and Huntington Units 1 and 2 meet 
the requirements of 40 CFR 51.309(d)(4)(vii) and the linked BART 
requirements in 40 CFR 51.308(e)(1).\75\ We are approving SIP Section 
IX, Part H.21 subsections a through d and f (related to applicability, 
definitions, recordkeeping, and stack testing), and conditionally 
approving Subsection e (emission limitations shall apply at all times). 
We are approving SIP Section IX, Part H.22 subsections a.i and b.i. We 
considered and rejected comments on the validity of the State's BART 
analyses for PM10 and the State's emission limitation of 
0.015 lb/MMBtu on a 30-day rolling basis for the Hunter and Huntington 
BART units. For PM10 reporting, we are finalizing our 
proposed conditional approval of this element in accordance with CAA 
section 110(k)(4), based on Utah's commitment to submit specific 
measures to address the reporting requirement.\76\ Utah's letter 
commits to adopt and submit rule language that would require sources to 
report any deviation from the requirements of the regional haze SIP 
provisions, which would include the PM10 emission 
limitations. The specific language is

[[Page 43908]]

detailed in Utah's commitment letter. We did not receive any adverse 
comments on our conditional approval of the recordkeeping requirements 
for the PM10 emission limitations.
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    \75\ As discussed elsewhere, while we are approving the 
PM10 emission limits in SIP Section IX, Part H.21, we are 
not approving into the SIP the ``approval orders'' (i.e., State-
issued permits) that are referenced in SIP Section XX.D.6.d at 25 
and 29).
    \76\ Letter from Department of Environmental Quality, State of 
Utah to EPA, DAQP-120-15 (Dec. 10, 2015).
---------------------------------------------------------------------------

    Pursuant to CAA section 110(k)(4), the State has one year from the 
date of this action to adopt and submit the necessary SIP revisions for 
SIP Section IX.H.21.e. If the State does not meet its commitment within 
the one year period, the conditional approval is treated as a 
disapproval. EPA finds that the necessary SIP revisions meet EPA's 
criteria for conditional approvals,\77\ as the revisions appear to 
involve a limited amount of technical work, are anticipated to be non-
controversial, and can reasonably be accomplished within the length of 
time for the State's adoption process.
---------------------------------------------------------------------------

    \77\ See Memorandum from John Calcagni to EPA Regional 
Directors. ``Processing of State Implementation Plan (SIP) 
Submittals'' (July 1992), available at http://www3.epa.gov/ttn/oarpg/t1/memoranda/siproc.pdf.
---------------------------------------------------------------------------

3. Enforceable Commitment SIP
    We are taking no action on Utah's enforceable commitment SIP, 
submitted on October 20, 2015. In its enforceable commitment SIP 
submittal, the State resolved to address double counting certain 
emissions reductions from the Carbon power plant closure under both the 
Utah BART Alternative and the SO2 backstop trading program 
under 40 CFR 51.309. As we explained in our proposal, we interpret our 
authority to enable us to approve enforceable commitment SIPs under 
section 110(a)(2)(A) of the Act and other applicable sections as 
relevant (for our NOX BART action, this is section 169A). 
However, since we are not approving the State's NOX BART 
Alternative SIP submittal, which included emissions reductions from the 
Carbon power plant, there is no need for the elements of the 
enforceable commitment SIP. Additionally, because we are not taking 
action on the enforceable commitment SIP package submitted on October 
20, 2015 we are not responding to comments on that SIP in this action.

II. Summary and Analysis of Major Issues Raised by Commenters

    We received both written and oral comments at the public hearings 
we held in Salt Lake City. We also received comments by the Internet 
and mail. The full text of comments received from these commenters is 
included in the publicly posted docket associated with this action at 
www.regulations.gov. Our RTC document, which is also included in the 
docket associated with this action, provides detailed responses to all 
significant comments received. In total, we received approximately 
4,900 pages of significant comments. Later we provide a summary of the 
more significant comments received and a summary of our responses to 
them. Our RTC document is organized similarly to the structure 
presented in this section (e.g., Cost of Controls, BART Alternative 
CALPUFF Modeling, etc.). Therefore, if additional information is 
desired concerning how we addressed a particular comment, the reader 
should refer to the appropriate section in our RTC document.
    PacifiCorp, conservation organizations (HEAL Utah, National Parks 
Conservation Association, and Sierra Club) and the National Parks 
Service (NPS) submitted detailed comments that include new cost and 
visibility modeling information.\78\ Several government, tourism and 
industry organizations also submitted comments. Many general comments 
were made at the public hearing. We received approximately 400 comments 
through email and the www.regulations.gov Web site. We also received 
approximately 70,000 mass mailer comments from private citizens.
---------------------------------------------------------------------------

    \78\ On May 19, 2015, PacifiCorp submitted late comments. These 
comments are included in the docket for this action and we address 
them in our RTC document.
---------------------------------------------------------------------------

A. General Comments

    Comment: Several commenters expressed concern over the 
accommodations provided at the public hearing. Several commented on the 
large number of attendees, and how this made it difficult for them to 
make their comments as well as hear those who were speaking. Commenters 
noted that many attendees were intimidated by the size of the hearing 
and by some of the other attendees, and suggested that many attendees 
left the hearing without commenting on the issues. There was concern 
that these departures may have led to an imbalance in opinions 
presented. Some commenters noted that some of the attendees at the 
hearing were not being cordial with the others and were unkind to those 
who expressed different opinions. Several commenters made requests for 
additional hearings, suggesting that additional hearings be located 
closer to the affected Class I areas and at locations that could 
accommodate a larger number of attendees.
    Response: Several commenters expressed their dissatisfaction with 
EPA's public hearing arrangements. As required by section 307(d)(5) of 
the CAA the EPA provided an opportunity for the public to submit 
written comments and voice concerns at the public hearing. In arranging 
the logistics for the public hearing, EPA's intent was to provide an 
opportunity for all members of the public to voice their opinions about 
the proposed rulemaking. The Salt Lake City library was chosen as the 
public hearing site because: (1) The library had reasonable 
accommodations to hold approximately 100 attendees; (2) the library was 
centrally located, and would be convenient for many members of the 
public to access; and (3) the library did not require a fee. The size 
of the venue was consistent with other hearings the EPA has conducted 
across the country.\79\ Based on these considerations, the EPA had no 
reason to believe the venue could not accommodate the anticipated level 
of public participation or that it would not fulfill the purposes of 
and the Act's requirements for the hearing.
---------------------------------------------------------------------------

    \79\ Examples include: (1) The public hearing on FIP proposal on 
May 1, 2012 at the Lewis and Clark Library in Helena, MT; (2) the 
public hearing on FIP proposal on July 27, 2013 at the Laramie 
County Library in Cheyenne, WY; and (3) the public hearing on FIP 
proposal on October 13-14, 2011 at the North Dakota Department of 
Health Training Center in Bismarck, ND.
---------------------------------------------------------------------------

    While the number of individuals attending the public hearing 
exceeded what we anticipated, we made adjustments throughout the day to 
accommodate the large numbers. For example, the library staff worked 
with us and set up broadcast speakers in the hallway so that those in 
the hallway could hear what was said during the hearing. The EPA could 
not allow the meeting room used for the public hearing to exceed its 
capacity limit in order to comply with the library's policies to comply 
with the fire code occupancy requirements. In response to the unkind 
statements made by some participants, the Hearing Officer reminded the 
crowd that the purpose of the meeting was to allow people to testify 
comfortably without being intimidated, and that people causing 
distractions would be asked to leave. In fact, some attendees who were 
causing distractions were asked to leave. Additionally, even though the 
turnout was larger than expected, EPA scheduled the opportunity for the 
public to speak based on their arrival time (with those arriving first, 
first allowed to speak); and the EPA accommodated all the potential 
speakers at the end of the scheduled hearing time, by extending the 
hearing until everyone who was present at that time and wanted to speak 
had done so. As a result the hearing was extended by approximately 20 
minutes.

[[Page 43909]]

    The EPA determined that additional hearings were unnecessary, 
because the written comment period continued for approximately seven 
weeks after the public hearing, allowing for additional comments to be 
submitted. As explained in the proposed rule,\80\ in addition to the 
public hearing, the EPA accepted written comments provided those 
comments were received on or before March 14, 2016. Therefore, while 
some of the members of the public may have left before they had an 
opportunity to speak at the hearing, they still had the opportunity to 
submit their comments either online or via mail to EPA for 
approximately seven weeks after the public hearing, as demonstrated in 
81 FR 2004. The EPA gives just as much consideration to comments we 
receive in writing as we do to those we receive at public hearings.
---------------------------------------------------------------------------

    \80\ 81 FR 2004 (Jan. 14, 2016).
---------------------------------------------------------------------------

B. EPA Authority and State Discretion

    Comment: The State of Utah commented that EPA should approve its 
BART Alternative because it meets all of the current requirements of 
the CAA and the RHR found at 40 CFR 51.300 through 51.309. EPA is 
obligated to approve a SIP that meets all of the applicable 
requirements of the CAA. See 42 U.S.C. 7410(k)(3) (``In the case of any 
submittal on which the Administrator is required to act under paragraph 
(2), the Administrator shall approve such submittal as a whole if it 
meets all of the applicable requirements of this chapter.''). The 
Section 308 regulation grants states full discretion as to whether to 
adopt the BART Alternative. In the current proposed rule, EPA also 
acknowledges a state's discretion in approving alternative measures: 
Finally, in . . . responding to concerns regarding ``impermissibly 
vague'' language in Sec.  51.308(e)(3) that would allow a State to 
``approve alternative measure that are less protective than BART,'' we 
explained that ``[t]he State's discretion in this area is subject to 
the condition that it must be reasonably exercised and that its 
decision be supported by adequate documentation of its analyses.'' 81 
FR 2004, 2012 (quoting 71 FR 60612, 60621 (Oct. 13, 2006)). Therefore, 
the alternative measure is within the state's discretion, as long as it 
is adequately supported.
    Response: We agree that states have discretion to adopt BART 
alternatives; however, as the commenter explains, the state's 
discretion is subject to a number of requirements, including that it be 
reasonably exercised and adequately supported and that the state's 
Alternative clearly provides greater reasonable progress than BART. The 
CAA requires that states submit SIPs that contain such measures as may 
be necessary to make reasonable progress toward achieving natural 
visibility conditions, including the BART requirements. As EPA 
explained when promulgating the regional haze regulations, ``[t]he 
overarching requirement of the visibility protection provisions of 
section 169A is to make reasonable progress toward the national goal of 
eliminating visibility impairment. If greater reasonable progress can 
be made through an approach that does not require source specific 
application of BART, EPA believes that approach would comport with this 
statutory goal.'' \81\ States have the opportunity to adopt alternative 
measures in lieu of BART where the agency reasonably concludes that 
more reasonable progress will thereby be attained toward the national 
visibility goal.\82\ We explained these requirements in our co-proposal 
as follows: ``[a]s described in our 2006 revisions to the RHR, 
concerning BART alternatives, `[t]he State's discretion in this area is 
subject to the condition that it must be reasonably exercised and that 
its decisions be supported by adequate documentation of its analyses.' 
''\83\
---------------------------------------------------------------------------

    \81\ 64 FR 35714, 35739 (July 1, 1999).
    \82\ Id. (emphasis added).
    \83\ 81 FR 2004, 2006 (Jan. 6, 2016) (citing 71 FR 60612, 60621 
(Oct. 13, 2006)).
---------------------------------------------------------------------------

    While states have discretion to decide whether to adopt a BART 
alternative in a SIP, such discretion does not extend to the authority 
to adopt SIPs that will not ensure reasonable progress toward the 
national visibility goal of preventing any future and remedying of any 
existing visibility impairment in Class I areas. Such an interpretation 
is also inconsistent with the legislative history, which stresses the 
importance of the ``national goal'' \84\ of clear air quality in Class 
I areas and ``preventing impairment of visibility,'' noting that ``the 
millions of Americans who travel thousands of miles each year to visit 
Yosemite or the Grand Canyon or the North Cascades will find little 
enjoyment if . . . upon reaching the Grand Canyon it is difficult if 
not impossible to see across the great chasm.'' \85\
---------------------------------------------------------------------------

    \84\ 42 U.S.C. 7491(a)(1).
    \85\ H.R. Rep. No. 95-294, at 137 (1977).
---------------------------------------------------------------------------

    Thus, we do not agree that Congress assigned states full discretion 
in developing SIPs, because it is not clear how EPA's limited role 
under such a scenario would assure attainment of the national goal or 
imposition of the [better than] BART requirements where a state's BART 
alternative demonstration does not demonstrate that the alternative 
achieves greater reasonable progress. In view of the statutory 
requirements, it is logical that EPA would evaluate the reasonableness 
of the State's BART Alternative analysis in light of the purpose of the 
regional haze program.
    As detailed in the sections in our co-proposal and based on our 
evaluation and findings as detailed in Section I.B.1 of this document 
and in our RTC document, we determined that, on balance, the evidence 
does not show that the Alternative clearly achieves greater visibility 
benefits than BART. Because the State's BART Alternative is not 
approvable, we are obligated to disapprove it, develop BART analyses, 
and then arrive at our own BART determinations for the four EGUs that 
are subject-to-BART.
    Furthermore, this is a SIP review action, and we believe that EPA 
is not only authorized, but required to exercise independent technical 
judgment in evaluating the adequacy of the State's regional haze SIP, 
including its BART Alternative analyses, just as EPA must exercise such 
judgment in evaluating other SIPs. In evaluating other SIPs, EPA is 
constantly exercising judgment about SIP adequacy, not just to meet and 
maintain the NAAQS, but also to meet other requirements that do not 
have a numeric value. In this case, Congress did not establish a 
specific numeric value by which to measure visibility improvement; 
instead, it established a reasonable progress standard and required 
that EPA assure that such progress be achieved via implementation, 
inter alia, of the Act's BART requirement. Here, we are exercising 
judgment within the parameters laid out in the CAA and our regulations.
    Our evaluation of the State's BART Alternative is presented in 
section I.B.1 and in our RTC document.
    Comment: The State commented that EPA mistakenly imposes additional 
inapplicable requirements in its evaluation of Utah's regional haze 
SIP. Greater reasonable progress under Section 308(e)(2) can be 
demonstrated using either one of two methods: (1) Greater emission 
reductions than under BART (Section 308(e)(3)); or (2) the weight-of-
evidence test, consisting of a number of requirements that the state 
weighs to conclude which option achieves greater reasonable progress 
(section 308(e)(2)). See 40 CFR 51.308(e)(2) and (3). The state has 
discretion to choose one method over the other. See WildEarth Guardians 
v. E.P.A., 770 F.3d 919, 935-37 (10th Cir.

[[Page 43910]]

2014). The Tenth Circuit characterized the former approach as 
``quantitative'' and the latter as ``qualitative,'' ultimately ruling 
that EPA can properly rely on qualitative factors in applying the 
``weight-of-evidence test.'' See id. at 934-35 (EPA's choice of 
qualitative standard was ``permissible under the EPA's interpretation 
of its regulations.'').
    Utah submitted its BART Alternative under Section 308(e)(2), 
purposefully electing to make its determination that the alternative 
program achieves greater reasonable progress under the ``weight-of-
evidence'' test. EPA analyzed Utah's BART Alternative in both co-
proposals under the section 308(e)(3) ``greater emissions reductions 
test'' in addition to the ``weight-of-evidence'' analysis. See 81 FR 
2004, 2021, 2028. EPA proposed that Utah's BART Alternative does not 
result in greater emission reductions because ``the total 
NOX emissions are greater under the BART Alternative than 
the BART Benchmark,'' even though ``in the aggregate there are fewer 
SO2 and PM10 emissions for the BART Alternative . 
. . .'' Id. at 2028. EPA erroneously imposed Section 308(e)(3) 
requirements on Utah's BART Alternative in addition to the Section 
308(e)(2) weight-of-evidence test. EPA must withdraw its analysis of 
Utah's BART Alternative under the greater emissions reductions test 
because, as Utah clearly explained, the State never intended its data 
to satisfy this test.
    Response: We agree in part and disagree in part with this comment. 
In developing a BART Alternative SIP, we agree that a state has the 
discretion to choose between the ``greater emission reduction'' test 
(section 308(e)(3)) and the ``weight-of-evidence'' test (section 
308(e)(2)). Utah's comments clarify that they elected the weight-of-
evidence test, and so we clarify and modify our evaluation of the 
State's SIP submittal. We therefore clarify that we are not 
disapproving the SIP under the elements of the section 308(e)(3) test 
as we had proposed.\86\
---------------------------------------------------------------------------

    \86\ 81 FR 2004, 2028 (``Therefore, we propose to disapprove 
Section XX.D.6.c. of the Utah SIP under the test in 40 CFR 
51.308(e)(3).'').
---------------------------------------------------------------------------

    The State's submittal, however, asserted that the BART Alternative 
is better than BART based in part on the metric that compared annual 
emissions of the three visibility impairing pollutants in the 
aggregate. There is no requirement in section 308(e)(2) for the State 
to compare annual emissions of visibility pollutants in the aggregate. 
Rather, as we explained in our proposal, we have addressed this issue 
under section 308(e)(3); our interpretation under that provision also 
applies under section 308(e)(2). Specifically, if under section 
308(e)(2) a state compares annual emissions of visibility in the 
aggregate to determine whether a BART alternative ``results in greater 
emission reductions,'' we examine whether each of the visibility 
causing pollutants is less under the alternative. For the reasons 
explained in our proposal and in section I.B.1.c.i of this document, we 
have not approved a BART alternative where one or more of the specific 
pollutants under the BART alternative is greater than it would be under 
the BART benchmark.\87\
---------------------------------------------------------------------------

    \87\ EPA's interpretation of the requirement under 40 CFR 
51.308(e)(3) that the alternative measure ``results in greater 
emission reductions'' has been that the emission reduction 
comparisons are pollutant specific. We have applied this 
interpretation in evaluating BART alternatives and we have not 
looked at a total emissions profile that combines emissions of 
multiple pollutants to determine whether a BART benchmark or a BART 
alternative is ``better,'' except where every visibility impairing 
pollutant is reduced by a greater amount under the BART alternative. 
See 79 FR 9318, 9335 (Feb. 18, 2014) (proposed approval of Arizona 
BART Alternative for Sundt Unit 4); 79 FR 52420 (Sept. 3, 2014) 
(final approval of Arizona BART Alternative for Sundt Unit 4); 77 FR 
18052, 18073-75 (Mar. 26, 2012) (proposed approval of Colorado BART 
Alternative, no modeling required where the 40 CFR 51.308(e)(3) test 
was met); 77 FR 76871 (Dec. 31, 2012) (final approval of Colorado 
BART Alternative). EPA has not relied on a total emissions profile 
that combines emissions of multiple pollutants together to determine 
that either BART or a BART alternative is ``better,'' because 
visibility modeling is the most appropriate method to assess the 
overall improvements in visibility impacts from control scenarios 
where reductions of multiple pollutants are considered, except where 
every visibility impairing pollutant is reduced by a greater amount 
under the alternative. As we have explained, ``[e]ach of the five 
pollutants which cause or contribute to visibility impairment has a 
different impact on light extinction for a given particle mass, 
making it therefore extremely difficult to judge the equivalence of 
interpollutant trades in a manner that would be technically 
credible, yet convenient to implement in the timeframe needed for 
transactions to be efficient. This analysis is further complicated 
by the fact that the visibility impact that each pollutant can have 
varies with humidity, so that control of different pollutants can 
have markedly different effects on visibility in different 
geographic areas and at different times of the year.'' See 64 FR 
35714, 35743(July 1, 1999). As other Agency actions on BART 
alternatives have explained, modeling assesses ``both pollutants' 
chemical aerosol formation mechanisms and impacts on visibility,'' 
(see 78 FR 79344, 79355; Dec. 30, 2013) which allows evaluation of 
the ``relative visibility impacts from the atmospheric formation of 
visibility impairing aerosols of sulfate and nitrate.'' See 79 FR 
33438, 33440 (June 11, 2014).
---------------------------------------------------------------------------

    Therefore, as we did in our proposal, it is reasonable to apply our 
interpretation of the section 308(e)(3) ``greater emission reductions'' 
element under section 308(e)(2) as well, because the same concerns 
regarding the relationship between reductions of multiple pollutants 
and visibility improvements are also relevant in the weight-of-evidence 
context.
    Comment: PacifiCorp asserted that EPA is not empowered under the 
CAA to require compliance with both the SIP proposal and the FIP 
proposal. As a practical matter, that is precisely what EPA proposes to 
do to the extent it approves the FIP proposal. This is because 
PacifiCorp already has implemented the SIP proposal as required by Utah 
law. If EPA were to select the FIP proposal, it would do so knowing 
\88\ that PacifiCorp would be required to implement both the SIP 
proposal and the FIP proposal. Nothing in CAA or regional haze rules 
allows EPA to require such a result when the proposed action itself 
states that EPA ``intends to finalize only one proposal.'' See 81 FR 
2004, 2006.
---------------------------------------------------------------------------

    \88\ EPA is well aware that the Utah SIP, as it has been 
implemented over time, became binding state law in regard to the 
Utah BART Units and ultimately the other units covered by the BART 
Alternative. This makes it particularly egregious that, even though 
EPA knew that PacifiCorp was required to expend hundreds of millions 
of dollars to fully implement the BART Alternative under state law, 
EPA said nothing about its intention to issue a competing co-
proposal until after PacifiCorp had completed all of the emission 
reductions required under the Utah SIP. See Letter from Carl Daly to 
Bryce Bird, Re. EPA Region 8 Comments on Utah's February 2015 Draft 
Regional Haze SIP Revision, at 1 (May 1, 2015) (commenting on the 
then-proposed Utah SIP including the BART Alternative). This 
secretive approach by EPA also caught the Utah Division of Air 
Quality off guard as explained in their oral comments during the 
January 26, 2016 hearing: ``Throughout the SIP development process, 
we worked as regulatory partners, closely and extensively with EPA 
staff to ensure that Utah's Alternative to BART SIP revision met all 
the requirements of the Clean Air Act and was approvable by EPA. The 
EPA should approve the option that Utah developed while in close 
consultation with EPA and not the option that Utah was not even 
aware was being prepared or under consideration until it was 
proposed in the Federal Register.''
---------------------------------------------------------------------------

    For all of the reasons stated earlier, EPA should approve the Utah 
SIP as stated in the SIP proposal, and should reject the FIP proposal. 
What EPA cannot do, and indeed is not empowered under the CAA to 
require, is compliance with both the SIP proposal and the FIP proposal.
    Response: We disagree with this comment. As explained elsewhere, 
the CAA requires that states submit SIPs that contain such measures as 
may be necessary to make reasonable progress toward achieving natural 
visibility conditions, including the BART requirements. EPA is acting 
under its authority pursuant to the CAA in disapproving portions of the 
SIP submittal and promulgating the FIP. We have the duty to ensure that 
regional haze SIP submittals meet the requirements of the Act and the 
RHR.\89\ While states have the opportunity to adopt alternative 
measures in lieu of

[[Page 43911]]

BART, their discretion in this area is subject to the condition that it 
must be reasonably exercised and that their decisions be supported by 
adequate documentation of its analyses.
---------------------------------------------------------------------------

    \89\ See CAA sections 169A and 110(k)(3).
---------------------------------------------------------------------------

    Therefore, we do not agree that we are prohibited from identifying 
deficiencies in the Utah SIP submittal after the State rulemaking 
process is complete, and the commenter cites nothing in the Act to the 
contrary. While a state may adopt regulations that are effective as a 
matter of state law before EPA goes through its rulemaking process to 
evaluate the proposed SIP elements, those state rules are not federally 
enforceable because any SIP submittal ``shall not be treated as meeting 
the requirements of this chapter until the Administrator approves the 
entire plan revision as complying with the applicable requirements.'' 
42 U.S.C. 7410(k)(3). The State's and EPA's roles in this process were 
understood in PacifiCorp statements. For example, in response to a 
question provided during rebuttal testimony that asked whether the 
regional haze rules are final, the Company explained that the 2011 Utah 
and Wyoming SIP submittals ``are final insofar as state action is 
considered'' and recognized that ``these submittals have not yet been 
approved by the Environmental Protection Agency.'' \90\
---------------------------------------------------------------------------

    \90\ Rebuttal Testimony of Cathy S. Woolums, at 26. (June 30, 
2011). (Available in the docket at https://www.regulations.gov/#!documentDetail;D=EPA-R08-OAR-2015-0463-0167).
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    The commenter suggests that measures in Utah's SIP submittal became 
``binding state law in regard to the Utah BART Units'' and ``the other 
units covered by the BART Alternative'' prior to EPA's final action. 
The commenter merely suggests there are state law provisions but does 
not provide citations to any state law specific provisions.\91\ It 
appears, however, that the commenter may be referring to measures 
established pursuant to the State's permit process. If this is, indeed, 
what the commenter is referring to, both the CAA and our regulations 
require that emission limits be established pursuant to a BART or BART 
alternative determination, and be contained in an EPA-approved SIP.\92\ 
The fact that Utah chose to use its permit process to establish 
emission limits for its BART sources before EPA completed its review of 
the State's SIP submittal has no bearing on EPA's authority and 
obligation to conduct this review and to approve or, if necessary, 
disapprove the State's submittal.
---------------------------------------------------------------------------

    \91\ Utah's Effective rule explains that ``[w]hile Utah has 
chosen to meet the NOX BART requirement through 
alternative measures . . . the enforceable emission limits for both 
NOX and SO2 established in the approval orders 
and in the SIP for the four EGUs also met the presumptive emission 
rates for both NOX and SO2 established in 
Appendix Y independently of the alternative program.'' Effective 
Rule at page E-12, Section XX, p. 168 (adopted by the Board on June 
3, 2015), available in the docket at https://www.regulations.gov/#!documentDetail;D=EPA-R08-OAR-2015-0463-0002. The presumptive 
emission limits in the BART Guidelines are rebuttable. The 
presumptive emission limits apply to power plants with a total 
generating capacity of 750 MW or greater insofar as these sources 
are required to adopt emission limits at least as stringent as the 
presumptive limits, unless after considering the five statutory 
factors, the State determines that the presumptive emission limits 
are not appropriate.
    \92\ Congress required EPA to promulgate regulations to assure 
``reasonable progress'' toward meeting the national goal and 
compliance with section 169A. The regulations require the submission 
of regional haze SIPs for states with Class I areas within their 
borders and states whose emissions ``may reasonably be anticipated 
to cause or contribute to any impairment of visibility'' in a Class 
I area outside their borders. 42 U.S.C. 7491(b)(2), 7491(e)(2). All 
SIPs must include ``enforceable emission limitations and other 
control measures, means, or techniques . . . as well as schedules 
and timetables for compliance, as may be necessary or appropriate to 
meet the applicable requirements of [the Act].'' CAA section 
110(a)(2)(A). Regional haze SIPs must include emission limits, 
compliance schedules, and other measures ``as may be necessary to 
make reasonable progress toward meeting the national goal.'' 42 
U.S.C. 7491(b)(2).
---------------------------------------------------------------------------

    Finally, EPA's comment letter on the State's proposed SIP clearly 
explained that ``we will only come to a final conclusion regarding the 
regional haze program for Utah when we take action on the program 
through our own public notice-and-comment rulemaking.'' \93\ Our letter 
further explained to the State that, ``we are working towards meeting 
our legal obligations that have resulted from our January 2013 partial 
disapproval action for Utah's May 2011 regional haze SIP.'' EPA comment 
letters are intended to help improve any SIP revision that is under 
development, but they do not constitute agency action on that SIP 
revision or constitute any assurance of positive action on that 
revision upon submission and review. Instead and always, EPA has to 
formally discharge its responsibilities to review any SIP submittal. 
Moreover, the CAA does not require EPA to participate in state 
proceedings related to a state's SIP submission, nor does it preclude 
EPA from carrying out its statutory duty to disapprove an inadequate 
SIP if EPA does not voice concerns during state proceedings. The CAA 
requires EPA to issue a FIP when states have not met their obligations 
under the CAA. Therefore, EPA is promulgating this FIP to fill the 
regulatory gap created by the partial disapproval of Utah's SIP 
submittals. Despite the existence of a FIP, the State retains its 
authority to submit future regional haze SIPs consistent with CAA and 
RHR requirements; we do not discount the possibility of a future, 
approvable SIP submission that results in the modification or 
withdrawal of the FIP.
---------------------------------------------------------------------------

    \93\ Letter from Carl Daly to Bryce Bird, Re. EPA Region 8 
Comments on Utah's February 2015 Draft Regional Haze SIP Revision, 
at 1 (May 1, 2015). (Available in the docket at https://www.regulations.gov/#!documentDetail;D=EPA-R08-OAR-2015-0463-0160).
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C. Reasonableness Standard

    Comment: One commenter asserted that EPA arbitrarily and 
capriciously applies two inappropriate standards to the Utah SIP 
proposal. The commenter stated that, in an attempt to replace Utah's 
determination with its own, EPA imposes a ``Reasonableness Standard'' 
without concluding the Utah SIP contains data or methodological flaws--
the limited circumstances under which courts have upheld use of this 
standard--and also imposes a ``Complexity of Evaluation'' standard 
which finds no support in the CAA or applicable regulations.
    The commenter also asserted that EPA is prohibited from imposing 
additional requirements upon its approval/disapproval of a SIP that do 
not qualify as ``applicable requirements.'' EPA is not correct in its 
attempt in the proposed action to impose additional requirements on its 
evaluation of the BART Alternative and Utah SIP that are different than 
the applicable BART alternative requirements.
    1. Reasonableness Standard -EPA asserts that Utah ``has several 
options for making the greater reasonable progress determination [and 
it] elected to use two separate approaches.'' \94\ See 81 FR at 2006. 
EPA further states that it will evaluate both of those approaches in 
deciding whether to approve the Utah SIP. EPA then makes the blanket 
assertion that ``the State's discretion in this area is subject to the 
condition that it must be reasonably exercised and that its decisions 
be supported by adequate documentation of its analysis.'' 
(``Reasonableness Standard.'') See 81 FR at 2006. Although the use of 
words like ``reasonable'' and ``adequate'' have common sense appeal in 
the abstract, EPA may not apply this standard in a way that allows EPA 
to discard the state's discretion and instead impose EPA's own will.
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    \94\ As explained below [referring to PacifiCorp's comment 
document], EPA is simply wrong in concluding that Utah used two 
separate approaches to demonstrate greater reasonable progress. 
Therefore, EPA's stated basis for imposing the Reasonableness 
Standard does not support EPA's effort to do so.
---------------------------------------------------------------------------

    In addition, the present circumstances regarding the SIP proposal 
are far different than those circumstances in

[[Page 43912]]

which courts have upheld EPA's use of a similar Reasonableness Standard 
in other regional haze settings. For example, in North Dakota v. EPA, 
730 F.3d 750, 760 (8th Cir. 2013), the court allowed EPA's use of the 
Reasonableness Standard under those circumstances where the state's 
BART determination contained ``data flaws that led to an overestimated 
costs of compliance.'' Also, Oklahoma v. EPA, 723 F. 3d 1201, 1212 
(10th Cir. 2013) reached a similar conclusion based on ``methodological 
flaws.''
    In the case of the SIP proposal, however, EPA proposes to approve 
the BART Alternative based on compliance with the applicable BART 
alternative requirements \95\ and without also concluding that the BART 
Alternative contains ``data flaws'' or ``methodological flaws.'' 
Therefore, the factual bases for allowing EPA to apply a Reasonableness 
Standard do not exist in regard to the BART Alternative and EPA should 
not attempt to apply such a standard here--particularly as a basis for 
rejecting the BART Alternative.\96\
---------------------------------------------------------------------------

    \95\ See generally 81 FR 2004, 2021-26.
    \96\ This is not to say that EPA lacks any role in reviewing and 
approving the Utah SIP. Indeed, the latest court to weigh in on 
EPA's review authority makes clear that ``Congress intended that 
EPA, not the states alone, ultimately ensure that state 
determinations as to regional haze comply with the [Clean Air] Act. 
. ..'' Arizona ex rel. Darwin v. EPA, Nos. 13-70366, 13-70410, 2016 
U.S. App. LEXIS 3196, at *19-20 (9th Cir. Feb. 24, 2016). Although 
PacifiCorp agrees that EPA has a role to play in making sure the 
Utah SIP complies with the CAA and applicable requirements, it also 
notes that EPA must do so in a way that does not undermine the role 
of states like Utah to which ``Section 169A [of the CAA] gives. . 
.substantial responsibility in determining appropriate BART [and 
BART Alternative] controls.'' The court goes on to make clear that 
``EPA may not disapprove reasonable state determinations that comply 
with the relevant statutory and regulatory requirements.'' Id. at 
*22. Such is the case with the Utah SIP.
---------------------------------------------------------------------------

    2. Complexity of Evaluation Standard--EPA also is wrong in its 
attempt to count among applicable requirements the unsupported 
conclusion that the ``complexity of our evaluation'' somehow 
necessitates EPA soliciting comments not only on the SIP proposal, but 
also on the competing FIP proposal. See 81 FR 2006.\97\ Even taking at 
face value the assertion that analyzing the Utah SIP is 
``complicated,'' that alone does not require EPA to evaluate the Utah 
SIP differently than any other regional haze SIP, nor does it justify 
EPA in presenting dueling co-proposals.\98\ In other words, EPA has 
simply conjured up this new ``complexity'' requirement \99\ out of thin 
air in an attempt to support its offering of the competing FIP 
proposal. EPA is acting arbitrarily and without legal authority by 
seeking comment on the FIP proposal based on what EPA calls the 
``complexity of our evaluation'' and for this reason EPA should 
withdraw the FIP proposal and approve the SIP proposal as proposed.
---------------------------------------------------------------------------

    \97\ EPA attempts to further support this contrived 
``complexity'' requirement by repeatedly stating that such a 
requirement exists, as if repetition alone somehow can bring an 
imaginary requirement into existence (i.e., ``In light of the 
variety of metrics Utah used, this is a complicated analysis. . . 
;'' ``The complexity of our evaluation leads us to propose and 
solicit comments on two conclusions and two courses of action . . . 
;'' ``Given the complexities in evaluating these co-proposals, EPA 
wants to ensure that our final decision is based on the best and 
most currently available data and information, and is taken with the 
fullest possible consideration of public input.'') See 81 FR 2004, 
2006.
    \98\ The Tenth Circuit Court of Appeals, which considered 
whether EPA's approval of a BART Alternative for SO2 
emissions was appropriate, did not conclude that EPA's analysis of 
the alternative program was, by its nature, more complicated than a 
BART analysis. See generally WildEarth Guardians v. EPA, 770 F.3d 
919 (10th Cir. 2014).
    \99\ EPA further attempts to justify its rationale for 
considering the FIP proposal by asserting, as explained in footnote 
3, the need to ``ensure that our final decision is based on the best 
and most currently available data and information, and is taken with 
the fullest possible consideration of public input.'' EPA already is 
charged with ensuring that any final decision is based on the best 
current data and information available. See 71 FR 60612, 60622 (Oct. 
13, 2006) (final rule on revisions to provisions governing 
alternative source-specific BART determinations); see also 5 U.S.C. 
706(2). EPA already is required to make a decision based on the 
fullest possible consideration of public input. See 5 U.S.C. 553(c). 
Re-stating these fundamental principles does not allow EPA to 
bootstrap itself into also considering a competing coproposal (the 
FIP proposal) when the SIP proposal already meets all Applicable 
BART Alternative Requirements as EPA itself has proposed to 
conclude. Arizona ex rel. Darwin at *22 (stating that ``EPA may not 
second-guess reasoned, legally compliant state decisions'') 
(internal citations and quotations omitted).
---------------------------------------------------------------------------

    Response: We disagree with most of these comments. First, we 
disagree that we have used a ``reasonableness standard'' in a manner 
that is inconsistent with our prior actions or as a way to limit the 
State's discretion. As discussed elsewhere, EPA has a duty to review 
Utah's regional haze SIP, including its BART Alternative, for 
compliance with the applicable requirements of the CAA and the RHR. 
Based on our review of the SIP, we proposed to determine that certain 
elements of Utah's regional haze SIP met the applicable requirements, 
and we proposed to approve those elements. However, for the reasons 
explained in detail in our proposed action and elsewhere in this 
document, we have concluded that, with regard to other elements, the 
State did not exercise its discretion in a reasonable manner, i.e., in 
a manner consistent with the requirements and goals of the CAA and RHR. 
Based on these findings, we are required to partially disapprove Utah's 
regional haze SIP submittal.
    As discussed in detail elsewhere, the CAA provides EPA with the 
authority to review and reject an inadequate regional haze SIP 
submittal. Oklahoma v. EPA, 723 F.3d 1201, 1207-08 (10th Cir. 2013) 
(EPA may not approve a submittal that does not adhere to applicable 
statutory and regulatory requirements). Contrary to the commenter's 
assertions, our analysis and decision here is entirely consistent with 
the North Dakota and Oklahoma decisions. The RHR requires a state to 
demonstrate that its BART alternative achieves greater reasonable 
progress than BART, 40 CFR 51.308(e)(2), and Utah chose to make this 
demonstration using a weight-of-evidence analysis. In our review, EPA 
found a number of flaws in this analysis. Based on this evaluation and 
findings as detailed in Section I.B.1 of this document and in our RTC 
document, we determined that, on balance, the evidence does not show 
that the Alternative clearly achieves greater visibility benefits than 
BART.
    Second, we disagree with the assertions regarding creation of a new 
complexity standard. The commenter misunderstands and misconstrues our 
proposed action. We did not create a new complexity standard, rather we 
explained that we were considering complex information and that it was 
a close call for EPA to decide whether the evidence presented by the 
State clearly demonstrated that the BART Alternative would achieve 
greater reasonable progress than BART (the complexity of our evaluation 
leads us to propose and solicit comment on two conclusions and courses 
of action because several of the metrics appear to support the State's 
analyses, while others do not appear to support the Alternative).\100\ 
Contrary to the commenter's assertions, we merely explained that the 
information in the State's SIP submittal was complex; we did not create 
a new standard by which to evaluate SIP submittals. Our proposed action 
clearly explained that some metrics appeared to support approval, while 
others metrics appeared to support a disapproval.
---------------------------------------------------------------------------

    \100\ 81 FR 2004, 2006 (Jan. 14, 2016) (emphasis added).
---------------------------------------------------------------------------

    Therefore, given that EPA's evaluation of the information before us 
presented a close call, and in order to provide a fair and meaningful 
process for all members of the public, we used the co-proposal 
approach. This approach provided an opportunity for the public to 
comment on both potential courses of action, i.e., approval or 
disapproval of the State's BART Alternative. Recognizing the

[[Page 43913]]

information before the Agency was possibly susceptible to both 
interpretations, our two proposed conclusions and courses of action 
were as follows: ``(1) The State's submittal meets the test above and 
we approve the BART Alternative; or (2) the State's submittal falls 
short of meeting this test and we disapprove the BART Alternative and 
promulgate a FIP for NOX BART.''
    We exercised our rulemaking discretion and structured the action 
using the co-proposal approach so that our action would enable all 
interested parties to have the opportunity to provide meaningful and 
timely comment on either or both approaches. In structuring the action 
in this way, the interested public had notice of the proposals under 
consideration and whether they had interests at stake. This balanced 
approach was fair in that it provided all interested parties with the 
options EPA contemplated in taking final action, as well as providing 
an opportunity to comment on the full range of potential actions. The 
commenter cites to no CAA provision that restricts EPA's authority to 
present co-proposals. EPA often provides alternative approaches for 
final Agency action in our SIP rulemaking proposals, as we did here. 
Additionally, even assuming that EPA's proposed action on the Utah 
regional haze SIPs articulated new ``complexity'' grounds for 
evaluating a regional haze SIP, the proposed action provided the public 
with the opportunity to comment. As evidenced by the commenter's 
submission, the commenter had the opportunity to provide input on this 
purported new standard to evaluating the Utah regional haze SIP and to 
identify any concerns associated with the statements at issue. 
Therefore, even if we had created a new complexity standard, which we 
did not, it would have been properly proposed and applied in this 
instance.
    As explained above, the EPA proposal identified several weaknesses 
and flaws in the State's SIP submittal in the proposed rulemaking,\101\ 
and as explained in this final action, other commenters have made us 
aware of additional weaknesses and uncertainties in the SIP 
submittal.\102\ Therefore, EPA is finalizing our co-proposal to 
disapprove the BART Alternative and promulgate a FIP for NOX 
BART, which this commenter recognizes EPA has a role and authority to 
do.
---------------------------------------------------------------------------

    \101\ Our proposal evaluated the State's use of the information 
from the metrics and identified weaknesses and flaws, for example: 
(1) The State's characterization of the 98th percentile modeling 
results that did not support its BART Alternative, was inconsistent 
with EPA's interpretation of and reliance on that metric; (2) the 
comparison of the results from the total annual emissions reductions 
was inconsistent with how we have interpreted our regulations; (3) 
the results from the modeling for the number of days the Alternative 
provided significant visibility impairment showed mixed results, 
with some results favoring the Alternative, while other results did 
not support the Alternative; (4) the annual average metric only 
marginally supported the Alternative, and showed less or equal 
visibility at four of nine Class I areas; and (5) the energy and 
non-air quality and cost metrics do not have a direct bearing on 
whether the Alternative achieves greater reasonable progress.
    \102\ Our RTC document provides details on the additional 
weaknesses and uncertainties that commenters brought to our 
attention.
---------------------------------------------------------------------------

    Furthermore, as explained elsewhere, we appreciate and clarify in 
this final action that the State did not intend to have its BART 
Alternative evaluated under both the 40 CFR 51.308(e)(2) and section 
308(e)(3) tests. We, therefore, based our final action on our 
evaluation of the State's submittal under Sec.  51.308(e)(2)'s weight-
of-evidence test.
    Finally, regarding the commenter's cross-reference to comments 
dated August 26, 2013, we explained in our final action in the Wyoming 
regional haze rulemaking that we disagreed with the comments in that 
context and we continue to disagree here.\103\
---------------------------------------------------------------------------

    \103\ ``As explained in our proposed rulemaking for section 
51.309(d)(4)(viii), we explained that the provision `is intended to 
clarify that if EPA determines that the SO2 emission 
reductions milestones and backstop trading program submitted in the 
section 51.309 SIP makes greater reasonable progress than BART for 
SO2, this will not constitute a determination that BART 
for PM or NOX is satisfied for any sources which would 
otherwise be subject to BART for those pollutants' (emphasis added). 
70 FR 44169 (Aug. 1, 2005). EPA does not interpret this rule to mean 
that there are different BART requirements for section 308 and 309 
regional haze SIPs. EPA's rulemaking made no finding that BART 
determinations conducted for a state submitting a SIP under section 
51.309 should be conducted any differently than a state submitting a 
FIP under only section 308. The use of the word `necessary' in 
section 51.309(d)(4)(viii) was to explain that some states may have 
BART NOX emission limitations, while others may not. As 
already explained elsewhere in proposal and our response to other 
comments, Wyoming did not conduct a proper evaluation of the five 
statutory factors, as required by 40 CFR 51.308(e)(1)(ii)(A) and 
section 169A(g) of the CAA.
    EPA also disagrees with the commenter's assertion that a BART 
submission is discretionary. 40 CFR 51.309(d)(4)(viii) is clear in 
that the implementation plan `must' contain BART requirements. The 
proposed rulemaking explained that the provision that provides that 
`[a]ny such BART provisions may be submitted pursuant to either 
Section 51.308(e)(1) or 51.308(e)(2),' was included to `allow States 
the flexibility to address these BART provisions either on a source-
by-source basis under Section 51.308(e)(1), or through an 
alternative strategy under Section 51.308(e)(2).' 70 FR 44169 (Aug. 
1, 2005).
    Moreover, EPA's proposal made clear that `[i]n limited 
circumstances, it may be possible for a State to demonstrate that an 
alternative program which controls only emissions from 
SO2 could achieve greater visibility improvement than 
application of source-specific BART controls on emissions of 
SO2, NOX and/or PM. We nevertheless believe 
that such a showing will be quite difficult to make in most 
geographic areas, given that controls on SO2 emissions 
alone in most cases will result in increased formation of ammonium 
nitrate particles.' 70 FR 44169 (Aug. 1, 2005). Wyoming's RH SIP 
does not include a demonstration that the backstop SO[2] trading 
program under Section 51.309 achieves greater visibility improvement 
than application of source-specific PM BART controls. Therefore, 
Wyoming's Section 51.309 SIP does not provide the adequate level of 
visibility improvement to meet the BART requirements
    With respect to the relationship of BART and requirements for 
reasonable progress under 40 CFR 51.308, EPA interprets the 
reasonable progress requirements to apply to BART sources. As 
explained in our guidance, due to the similarity of the BART and 
reasonable progress factors, states may reasonably rely on their 
BART determinations to show reasonable progress for those sources 
for the first planning period. However, BART is an independent 
requirement of the statute and the RHR. We have disapproved certain 
BART determinations by Wyoming not due to a failure to make 
reasonable progress, but due to a failure to consider the BART 
factors appropriately.'' 79 FR 5032, 5098, 5099 (Jan. 30, 2014).
---------------------------------------------------------------------------

D. Compliance With 40 CFR 51.308

    Comment: Two commenters noted that EPA's FIP proposal is 
unnecessary because EPA already found Utah is making the required 
``reasonable progress.'' The goal of the RH program is to make 
``reasonable progress'' towards the statute's national visibility goal. 
Accordingly, EPA promulgated regulations ``to assure . . . reasonable 
progress toward meeting'' the national visibility goal, section 
7491(b)(2), and mandated that EPA's regulations contain ``such emission 
limits, schedules of compliance and other measures as may be 
necessary'' to assure such progress towards meeting that goal, 
``including'' a requirement that states make BART determinations. Id. 
As EPA has stated, ``BART is one component of long term strategies to 
make reasonable progress.'' Regional Haze Regulations and Guidelines, 
70 FR 39137.
    Because BART's purpose is to make reasonable progress, EPA adopted 
regulations exempting states from making BART determinations if they 
can show that other measures for large stationary sources will achieve 
greater reasonable progress. 40 CFR 51.308(e)(2) (2012). EPA defended 
those regulations in court by arguing that BART is one of a number of 
``emission limits, schedules of compliance and other measures'' that 
``must'' be included in a SIP ```as may be necessary to make reasonable 
progress toward national visibility goals.' '' Ctr. for Energy and 
Econ. Dev. v. EPA, 398 F.3d 653, 659-60 (D.C. Cir. 2005) (confirming 
BART is but one measure for achieving ``reasonable progress''); Cent. 
Arizona Water Conservation Dist. v. EPA, 990 F.2d 1531, 1534 (9th Cir. 
1993) (same). If an alternative can better achieve those

[[Page 43914]]

goals, EPA has stated that BART would not be ``necessary to make 
reasonable progress.'' Id. The court agreed with EPA's analysis, 
although it overturned EPA on other grounds. Id. As the court said, 
``the focus of the Clean Air Act was to achieve `actual progress and 
improvement in visibility,' 42 U.S.C. 7492(b), not to anoint BART the 
mandatory vehicle of choice.'' Id. at 660.
    As EPA recognizes, in some circumstances no BART controls may be 
necessary to make reasonable progress. It follows that in other 
circumstances, depending on a state's reasonable- progress goals and 
expected non-BART emission reductions, BART controls of varying 
stringency may be necessary. Consistent with this goal, EPA has 
approved Utah's ``reasonable progress'' determination for its RH SIP in 
its entirety. See ``Approval, Disapproval and Promulgation of State 
Implementation Plans; State of Utah; Regional Haze Rule Requirements 
for Mandatory Class I Areas Under 40 CFR 51.309,'' published at 77 FR 
74355, 74367-68 (Dec. 14, 2012). EPA found that ``the State met all 
reasonable progress requirements for the Class I areas,'' including by 
implication any required NOX BART limits. In fact, EPA 
stated that Utah's 2008 RH SIP, including BART controls identified in 
that 2008 RH SIP, would result in ``a significant decrease in 
stationary source NOX and SO2 emissions.'' Id. 
EPA further found that the NOX BART controls adopted by Utah 
for the Hunter and Huntington EGUs at issue would decrease 
NOX emissions by ``6,200 tons [annually] between 2002 and 
2018.'' Id. Therefore, EPA acknowledged that Utah's NOX BART 
limits and controls are all that are required to achieve ``reasonable 
progress,'' and no further NOX BART requirements should be 
imposed by EPA through its FIP proposal.
    Thus, EPA cannot validly judge a state's BART determination outside 
of its reasonable progress context. Owasso Indep. Sch. Dist. No. I-011 
v. Falvo, 534 U.S. 426, 434 (2002) (``the words of a statute must be 
read in their context and with a view to their place in the overall 
statutory scheme.'').
    Response: EPA disagrees with these comments. The commenters appear 
to be asserting that, since EPA approved Utah's 2011 SIP submission as 
meeting the reasonable progress requirements of 40 CFR 51.309 with 
regard to SO2, no further controls are necessary to meet the 
RHR's requirements for NOX and PM. However, this assertion 
ignores our statements in the BART Alternatives rulemaking that an EPA 
determination that a backstop trading program satisfies a state's 
reasonable progress obligations for SO2 under 40 CFR 51.309 
does not satisfy that state's obligation to address NOX and 
PM requirements under 40 CFR 51.308(e)(1) or (2). In this rulemaking, 
EPA proposed amendments to the stationary source NOX and PM 
provisions within Sec.  51.309 precisely in order to ``clarify that if 
EPA determines that the SO2 emission reductions milestones 
and backstop trading program in the Sec.  51.309 SIPs makes greater 
reasonable progress than BART for SO2, this will not 
constitute a determination that BART for PM or NOX is 
satisfied for any sources which would otherwise be subject to BART for 
those pollutants.'' \104\ The final rulemaking reinforced that a 
reasonable progress determination for SO2 under Sec.  
51.309's backstop trading program does not satisfy the emission 
reductions requirements for non-SO2 pollutants.\105\
---------------------------------------------------------------------------

    \104\ 70 FR 44154, 44169 (Aug. 1, 2005) (emphasis added).
    \105\ 71 FR 60612, 60626 (Oct. 13, 2006).
---------------------------------------------------------------------------

    We also took this position in another recent regional haze action, 
in which we found that the state's approved SO2 alternative 
under Sec.  51.309 did ``not provide the adequate level of visibility 
improvement to meet the [non-SO2] BART requirements.'' \106\ 
We then reiterated that ``BART is an independent requirement of the 
statute and the RHR.'' \107\ Our statements in both the national and 
regional contexts make it clear that a reasonable progress 
determination for an SO2 backstop trading program under 
Sec.  51.309 does not relieve a state of its obligation to satisfy 
NOX and PM BART. EPA thus can judge a state's BART 
determination outside the reasonable progress context, as they are 
independent requirements.
---------------------------------------------------------------------------

    \106\ 79 FR 5032, 5099 (Jan. 30, 2014) (final partial approval/
partial disapproval of Wyoming regional haze SIP submission).
    \107\ Id.
---------------------------------------------------------------------------

    The commenters' claim that EPA's approval of Utah's Sec.  51.309 
program in our December 2012 final action means that the State met its 
reasonable progress requirements ``in its entirety'' is thus clearly 
incorrect. In that action we determined that the State met the 
requirements of Sec.  51.309 and therefore satisfied its reasonable 
progress obligation with regard to the particular pollutants covered in 
the State's alternative, i.e., SO2. This determination has 
no bearing on the State's independent NOX and PM 
obligations. To comply with the RHR, the state must still address any 
BART obligations for pollutants not included in the BART alternative 
analysis and therefore not covered by the ``better than BART'' 
determination.
    EPA similarly disagrees that it acknowledged that the 
NOX controls in Utah's 2011 SIP submission are all that are 
required to achieve reasonable progress and that EPA should therefore 
not require further NOX BART requirements. As explained 
earlier, EPA's determination that Utah's 2011 submission satisfied 
reasonable progress requirements does not constitute implicit 
evaluation and action on Utah's NOX and PM SIP submittal as 
meeting the BART requirements. Furthermore, the commenter overlooks 
EPA's explicit disapproval of Utah's NOX and PM BART 
determinations in our December 2012 partial approval/disapproval.\108\ 
EPA's disapproval of Utah's NOX and PM control 
determinations necessarily precludes finding that these same controls 
are all that are required to satisfy the RHR's requirements. EPA is 
thus required to promulgate a NOX BART FIP, which we are now 
doing. Commenters also take EPA's statements regarding the quantity of 
anticipated NOX reductions from Utah's rejected BART 
determination out of context. These statements were offered as reasons 
why Utah satisfied the RHR's requirement to address impacts on Class I 
areas in other states by achieving previously agreed upon emission 
reductions, which is a separate consideration from whether the State 
has satisfied its independent NOX and PM BART obligations.
---------------------------------------------------------------------------

    \108\ 77 FR 74355, 74357 (Dec. 14, 2012).
---------------------------------------------------------------------------

    EPA also disagrees that the statements in the cited cases have any 
bearing on this action. In Center for Energy and Economic Development 
v. EPA (CEED),\109\ the issue was whether EPA's BART alternative 
provisions in Sec.  51.309 were consistent with CAA section 169A(b)(2) 
given that they used a methodology for establishing the BART benchmark 
that the D.C. Circuit had previously vacated in American Corn Growers 
Ass'n v. EPA.\110\ As part of its challenge to EPA's BART alternative 
provisions, CEED argued that section 169A(b)(2) requires all states' 
SIPs to include BART, meaning EPA could not allow BART alternatives in 
place of source-specific BART. EPA argued that section 169A(b)(2) 
allows either BART or an alternative to BART submitted pursuant to 
Sec.  51.309 if that alternative would achieve greater reasonable 
progress than BART, i.e., if the alternative is ``better than BART.'' 
The statements the commenter cites express EPA's view on the narrow 
issue of whether and when we may allow states to substitute an 
SO2 trading program for

[[Page 43915]]

source-specific BART under Sec.  51.309. Because these statements 
address only the relationship between BART and BART alternatives for 
SO2 under Sec.  51.309; they have no bearing on whether we 
believe a state's submission of an SO2 trading program 
satisfies its independent obligation to address NOX and PM, 
as these obligations were not at issue in this case.
---------------------------------------------------------------------------

    \109\ 398 F.3d 653 (D.C. Cir. 2005).
    \110\ 291 F.3d 1 (D.C. Cir. 2002).
---------------------------------------------------------------------------

    In our December 14, 2012 action we approved Utah's BART Alternative 
for SO2 under 40 CFR 51.309, finding that it achieved 
greater reasonable progress than SO2 BART. As explained 
earlier, this determination has no bearing on Utah's outstanding 
NOX and PM BART obligations. We, therefore, disagree that 
today's action to address these obligations is unnecessary.
    Comment: Several commenters asserted that Utah's BART Alternative 
does not achieve greater reasonable progress based on the ``clear 
weight-of-evidence.'' Utah's Regional Haze SIP also must be rejected 
under 40 CFR 51.308(e)(2)(i)(E) because it does not achieve ``greater 
reasonable progress'' based on the ``clear weight-of-evidence.'' \111\
---------------------------------------------------------------------------

    \111\ 40 CFR 51.308(e)(2)(i)(E).
---------------------------------------------------------------------------

    At the outset, Utah's proposed reliance on the ``clear weight-of-
evidence'' test is improper. In promulgating regulations allowing for 
the test, 40 CFR 51.308(e)(2)(i)(E), offered the following example of 
when the test might be appropriate: ``(1) The alternative program 
achieves emissions reductions that are within the range believed 
achievable from source-by-source BART at affected sources, (2) the 
program imposes a firm cap on emissions that represents meaningful 
reductions from current levels and, in contrast to BART, would prevent 
emissions growth from new sources, and (3) the State is unable to 
perform a sufficiently robust assessment of the programs using the two 
pronged visibility test due to technical or data limitations.'' \112\ 
None of those conditions are met here. Most importantly, Utah's BART 
Alternative does not drive any meaningful reductions from ``current 
levels'' and does not prevent emissions growth from new sources, and 
Utah is not hindered by any technical or data limitations preventing a 
sufficiently robust visibility assessment. EPA further noted that ``a 
weight-of-evidence comparison may be warranted'' ``when there is 
confidence that the difference in visibility impacts between BART and 
the alternative scenarios are expected to be large enough.'' \113\ 
Here, as EPA correctly observed, even Utah's flawed modeling 
demonstrated the superiority of BART using the most relevant visibility 
metric and only minimal benefits of the BART Alternative compared with 
BART using other metrics.
---------------------------------------------------------------------------

    \112\ 71 FR 60612, 60621 (Oct. 13, 2006).
    \113\ Id. at 60622.
---------------------------------------------------------------------------

    Several commenters also raised concerns regarding emission shifting 
from the power plants covered by the SIP to existing sources that are 
not included in this SIP. They suggested that due to the nature of the 
electrical generation market, with the adjustments to the overall 
system to add capacity elsewhere to accommodate the Carbon power plant 
shutdown (and perhaps also to accommodate the emission limit reductions 
at the Hunter and Huntington power plants), those shifts in capacity 
could result in increases in emissions at power plants outside the BART 
Alternative. The commenters further suggested that if those emission 
increases had been considered in the State's weight-of-evidence 
analysis, the BART Alternative may not provide greater reasonable 
progress than BART if the emission reductions assessment under the 
Alternative are not permanent and were to shift to other power plants. 
As an example, one of the commenters provided an analysis for a Utah 
power plant (not covered by the BART Alternative) that based on its 
proximity to the nine Class I areas analyzed under the BART 
Alternative, if emission increases were to occur at that plant the 
increases could impact visibility impairment at the Class I areas. 
Other commenters expressed concern that the lost capacity from the BART 
Alternative sources could shift to new sources, and explained that the 
emissions from new sources are not evaluated in the State's weight-of-
evidence analysis. One commenter suggested that this Alternative 
appears to be more like a ``trading'' program and that other 
regulations apply. One commenter expressed concern that a non-BART 
source is included in the BART Alternative, and further, that not all 
the sources in the State that are part of this source category are 
included.
    Response: We agree in part and disagree in part with these 
comments. First, as explained elsewhere, we agree with the commenter 
that the State's analysis for the BART Alternative does not show that 
the Alternative clearly achieves greater visibility benefits than BART. 
Second, the four examples cited by the commenter from our RHR preamble 
were examples, rather than an exclusive list of circumstances under 
which a state may use a weight-of-evidence analysis. Therefore, the 
State was not required to fall into one of these categories in order to 
select the weight-of-evidence approach to support its BART Alternative. 
Third, we disagree that emission reductions must occur from current 
levels, because, consistent with the RHR, the baseline date for 
regional haze SIPs is 2002.\114\
---------------------------------------------------------------------------

    \114\ 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 18, 2002).
---------------------------------------------------------------------------

    Next we respond to the commenters' concerns about potential 
shifting of production and emissions from the sources in the BART 
Alternative to sources outside the BART Alternative. We acknowledge 
that the State's BART Alternative has the following characteristics: 
(1) It includes all the BART sources in the State; (2) it accounts for 
emission reductions from a non-BART source; and (3) it includes some, 
but not all, sources in the source category within the State. The RHR 
provides that BART alternative programs may include non-BART 
sources.\115\ We disagree with commenters that suggested the RHR 
trading requirements apply to the Utah BART Alternative.\116\ The RHR 
trading provisions apply to SIPs that establish a cap on total 
emissions from sources that are subject to the BART program, and 
further require the owners and operators of the sources to hold 
allowances to purchase, sell, and transfer allowances. Utah's SIP 
contains rate-based emission limits on the sources that are subject to 
the BART Alternative and therefore does not include a cap on emissions 
or trading provisions. Therefore, the Utah SIP does not contain the 
elements of a trading program as described in the RHR, which include 
provisions to prevent significant emission shifting.\117\
---------------------------------------------------------------------------

    \115\ The preamble to the RHR provides for inclusion of BART and 
non-BART sources in a BART alternative. 64 FR 35714, 35743 (July 1, 
1999).
    \116\ 40 CFR 51.308(e)(2)(E)(v) (containing requirements for a 
state to demonstrate that a trading program prevent any significant, 
potential shifting within the state of production and emissions from 
the sources in the program to sources outside the program).
    \117\ Id.
---------------------------------------------------------------------------

    Although the State's SIP explained that the Carbon power plant had 
already closed and electricity generated from the Carbon power plant 
has been replaced (and the associated costs already have been absorbed 
by Utah rate payers and those in other states served by 
PacifiCorp),\118\ the SIP submittal neither identified what electrical 
generating facilities increased capacity

[[Page 43916]]

to accommodate the Carbon shut down, nor did it provide an analysis of 
whether the capacity replacement resulted in increases in visibility 
impairing pollutants. Furthermore, in addition to seeking and receiving 
authorization to recover costs associated with retirement of the Carbon 
plant, the Company also received authorization from state utility 
commissions to recover additional costs, including ``installation of 
equipment necessary to ensure voltage stability, along with various 
communications upgrades and protection and control equipment.'' \119\ 
It is unclear whether the activities associated with these additional 
costs resulted in capacity and emissions shifting and increased 
visibility impairment at the affected Class I areas. Therefore, while 
the record before us indicates that capacity has shifted, it is unclear 
how the shift was accommodated, and whether there are any emission 
increases and associated visibility impairment.\120\
---------------------------------------------------------------------------

    \118\ Utah Staff Review Report at 27.
    \119\ The Application of Rocky Mountain Power for Approval of a 
General Rate Increase, No. 20000-446-ER-14, Wyoming Public Service 
Commission, (Jan. 23, 2015) (Findings of Fact, Conclusions of Law, 
Decision and Order Nunc Pro Tunc) (Available in docket at https://www.regulations.gov/#!documentDetail;D=EPA-R08-OAR-2015-0463-0167). 
An order from the Idaho Public Commission also discussed the impacts 
from Carbon's retirement on the transmission system and noted that 
``[t]he Company states that retiring Carbon may pose a complication 
with potential transmission system impacts.'' See The Application of 
PacifiCorp DBD DBA Rocky Mountain Power, Case No. PAC-E-12-08, Order 
No. 32701, at 1, Idaho Public Utilities Commission (Dec. 27, 2012) 
(Available in the docket at https://www.regulations.gov/#!documentDetail;D=EPA-R08-OAR-2015-0463-0167).
    \120\ Utah's BART Alternative has the characteristics of an 
``open market'' program where some, but not all, sources in a source 
category are covered by the SIP measure. EPA Guidance, ``Improving 
Air Quality with Economic Incentive Programs,'' at 48, 96, 112-118, 
EPA-452/R-01-001 (Jan. 2001), available at https://www3.epa.gov/ttn/caaa/t1/memoranda/eipfin.pdf); 77 FR 11928 (Feb. 28, 2012); 77 FR 
46952 (Aug. 7, 2012).
---------------------------------------------------------------------------

    It is therefore unclear whether the shift in capacity as a result 
of the Carbon plant retirement results in increased emissions and 
visibility impairment at the affected Class I areas. Because the record 
lacks information on these questions, we agree with the commenters that 
there is additional uncertainty as to whether the BART Alternative is 
better than BART.

E. Overarching Comments on BART Alternative Demonstration

    Comment: The State of Utah commented that EPA should approve the 
option that Utah developed in close consultation with EPA and not the 
option that Utah was not even aware was being prepared or under 
consideration until it was signed by the Regional Administrator. Utah 
worked closely and in good faith with the EPA and the FLMs to evaluate 
and implement the appropriate controls for improving visibility. Up to 
the point of the current proposal, the EPA has indicated to Utah that 
the alternative to BART approach and analysis were acceptable. During 
the RH SIP development process, Utah and EPA worked as regulatory 
partners--Utah working closely and extensively with EPA's staff to 
ensure that Utah's BART Alternative was approvable. EPA's concurrence 
with Utah's RH SIP proposal is also supported by EPA's comments 
submitted during the state rulemaking public comment period on the 
current revision of the Utah's RH SIP. EPA did not point to any 
substantive flaws in Utah's RH SIP, but only requested minor 
clarifications and revisions in its 3-page comment letter.
    Response: While we agree that EPA worked in close consultation with 
Utah on the BART Alternative within the limitations of what the State 
and PacifiCorp were willing to offer in the plan, EPA is not required 
to approve the option developed by Utah. As stated elsewhere in this 
document, EPA's comment letter on the State's proposed SIP explicitly 
explained the following: ``[p]lease note that we will only come to a 
final conclusion regarding the regional haze program for Utah when we 
take action on the program through our own public notice-and-comment 
rulemaking.'' \121\ Our May 1, 2015 letter further explained to the 
State that, ``[i]n addition, we wish to inform you that we are working 
towards meeting our legal obligations that have resulted from our 
January 2013 partial disapproval action for Utah's May 2011 regional 
haze SIP.'' \122\ EPA's assistance to states and our comment letters 
are intended to be helpful to the improvement of any SIP revision that 
is under development, but they do not constitute agency action on that 
SIP revision or constitute any assurance of positive action on that 
revision upon submission and review.
---------------------------------------------------------------------------

    \121\ Letter from Carl Daly to Bryce Bird, Re. EPA Region 8 
Comments on Utah's February 2015 Draft Regional Haze SIP Revision, 
at 1 (May 1, 2015). (Available in the docket at https://www.regulations.gov/#!documentDetail;D=EPA-R08-OAR-2015-0463-0160).
    \122\ Id.
---------------------------------------------------------------------------

    Additionally, the State's efforts to involve the FLMs did not 
adequately meet the requirements for FLM consultation in developing 
plan revisions. The State could have satisfied the consultation 
requirements by providing more time for FLM review so that the FLMs 
would have received the full number of 60 days for their review. 
However, in developing the co-proposals, consulting with the FLMs, and 
by taking this final action, EPA has considered the FLMs' concerns.
    Comment: Several commenters asserted that both Utah and EPA imply 
that nitrate formation in non-winter months is not significant,\123\ or 
that NOX reductions will not meaningfully reduce nitrates in 
non-winter months.\124\ Both are untrue. Based on IMPROVE data, light 
extinction attributable to ammonium nitrate in non-winter months is 
roughly 20% of that attributable to ammonium sulfate. Despite the 
preferential formation of ammonium sulfate year round and higher 
ammonium nitrate formation in winter months, it is clear that 
significant levels of ammonium nitrate also form in non-winter months, 
and that these are likely to be lowered by reductions in NOX 
emissions. Furthermore, while EPA notes that wintertime conditions 
favor nitrate formation (versus non-winter),\125\ this is accounted for 
in modeling and cannot be used to discount those results.
---------------------------------------------------------------------------

    \123\ Utah Staff Review Report at 17, Exhibit 15. Winter months 
in this context are December, January, and February.
    \124\ 81 FR 2004, 2023 (EPA says that based on a computational 
model, ``We propose to find that visibility benefits associated with 
NOX reductions are much more likely to occur in the 
winter months because this is when aerosol thermodynamics favors 
nitrate formation'').
    \125\ Id.
---------------------------------------------------------------------------

    Response: We partially agree with the comment. While EPA did not 
suggest that nitrate in non-winter months is not significant, IMPROVE 
monitoring data do show that nitrate light extinction is highest in 
winter and substantially smaller in the other seasons. For example, in 
2014, the most recent year of IMPROVE data available at the Canyonlands 
monitor, nitrate contributed an average of 31% of total light 
extinction in December to February compared to an average of 5% of 
total light extinction from March to November. In 2013, nitrate 
contributed an average of 45% of total light extinction in December to 
February compared to an average of 7.5% of total light extinction from 
March to November. By contrast, sulfate light extinction is relatively 
constant across the four seasons.\126\
---------------------------------------------------------------------------

    \126\ See EPA spreadsheet entitled, Canyonlands IMPROVE 
Monitoring Data for 2013 and 2014 (Available in the in the docket).
---------------------------------------------------------------------------

    Nonetheless, overall nitrate extinction at the affected areas is 
significant, particularly on the 20% worst days. For example, at 
Canyonlands on the 20% worst days, nitrate contributed 33% and 17% of 
total extinction in 2013 and

[[Page 43917]]

2014, respectively. Given the focus of the reasonable progress 
provisions of the RHR on the 20% worst days, we consider the monitoring 
data for these days to be more informative than seasonal trends in 
monitoring data.
    We also agree with the commenter that the modeling performed by 
Utah and EPA accounts for the fact that wintertime conditions favor 
nitrate formation (versus non-winter). In particular, the CALPUFF 
modeling performed by Utah and EPA both show that, while there will be 
some benefits from NOX controls outside of the winter 
season, the largest benefits in nitrate reductions occur in winter 
months.\127\ We have taken the strength of the modeling results for 
winter months into consideration; however, contrary to suggestions that 
visibility improvements during seasons of peak Class I area visitation 
should carry more weight, we have evaluated the visibility impacts 
throughout the entire year, regardless of the season and have given the 
most weight to those times when the sources in question have the 
largest impacts. In particular, as explained elsewhere in this document 
and our RTC document, we have given greater weight to the 98th 
percentile CALPUFF metric, which captures these highest impact days.
---------------------------------------------------------------------------

    \127\ Both Utah and EPA CALPUFF modeling results can be viewed 
in or obtained from the EPA Region 8 offices by contacting the 
individual listed in the FOR FURTHER INFORMATION CONTACT section of 
this document.
---------------------------------------------------------------------------

F. Cost of Controls

    Comment: Several commenters submitted comments regarding the costs 
to install SCR at the Hunter and Huntington BART EGUs. PacifiCorp 
submitted a technical report developed by its consultant, Sargent & 
Lundy, which criticized numerous aspects of EPA's cost analysis 
developed by our contractor, Andover Technology Partners (ATP), 
including catalyst volume, SCR design, project and process contingency 
costs, and others. The conservation organizations' consultant reviewed 
PacifiCorp's cost analyses from 2012 and 2014 and provided comments 
about the validity of PacifiCorp's analyses. The National Park Service 
supported EPA's cost estimates in the proposed rule and indicated the 
estimates show that both the combined cost of LNB and SOFA plus SCR 
(SCR + LNB/SOFA) and the incremental cost of adding SCR to LNB/SOFA are 
cost-effective and represent BART. The conservation organizations also 
supported EPA's cost estimates in the proposed rule.
    Response: EPA has provided a revised cost analysis to support our 
final rulemaking. We again used Andover Technology Partners (ATP) for 
conducting the analysis. We have carefully reviewed the analysis and 
determined that it appropriately estimates the costs to install SCR at 
Hunter and Huntington. Of particular note is that in our revised cost 
analysis, EPA has accepted both the catalyst volume and SCR design 
suggested by Sargent & Lundy. However, we continue to reject process 
and project contingency costs and other costs that are double counted, 
not permissible under the CCM, or are otherwise not justified. The 
final Andover report and spreadsheet provide further details regarding 
how each of these costs was addressed in the revised analysis 
supporting this rulemaking.\128\ Also, in our RTC document, we have 
addressed the specific comments concerning the capital costs that 
Sargent & Lundy alleges that Andover incorrectly excluded from its 
analysis, as well as all other comments regarding our cost estimates.
---------------------------------------------------------------------------

    \128\ Andover Technology Partners, Cost of NOX BART Controls on 
Utah EGUs to: EC/R Inc. (May 13, 2016). Andover Technology Partners 
is a subcontractor to EC/R Incorporated.
---------------------------------------------------------------------------

    We concur with the National Park Service's and conservation 
organizations' supportive comments regarding the cost effectiveness of 
SNCR and SCR. In addition, the revised cost effectiveness estimates 
that we prepared to support this final rule, when considered along with 
the other five BART factors, continue to support selection of SCR + 
LNB/SOFA as BART.
    The conservation organizations' comments pertain to the costs that 
PacifiCorp submitted to the Utah Department of Air Quality, and which 
Utah included in its SIP submittal to EPA. However, EPA developed 
separate costs to support our FIP, and has updated those costs in 
support of our final action. Our RTC document contains additional 
detail concerning our consideration of these comments.

G. Comparison With Other Regional Haze Actions

    Comment: Two commenters agreed with the comparisons we provided in 
our proposed rule to other BART determinations that EPA used to support 
our proposed FIP. One commenter disagreed with the comparisons. These 
comparisons included Cholla,\129\ Hayden,\130\ and Laramie River 
Station.\131\ The commenter who disagreed asserted that different 
methodologies were involved in all three cases and that EPA failed to 
provide comparisons to other actions that did not support the FIP. The 
commenter provided additional examples from EPA actions in Florida, 
Montana, and Nebraska that they asserted do not support EPA's Utah FIP 
decision.
---------------------------------------------------------------------------

    \129\ 77 FR 42834 (July 20, 2012) (proposal); 77 FR 72512, 
72514-15 (Dec. 5, 2012) (final).
    \130\ 77 FR 18069 (Mar. 26, 2012) (proposal); 77 FR 76871 (Dec. 
31, 2012) (final).
    \131\ 79 FR 5032, 5099 (Jan. 30, 2014) (final partial approval/
partial disapproval of Wyoming regional haze SIP submission).
---------------------------------------------------------------------------

    Response: We continue to find that the Cholla, Hayden and Laramie 
River Station comparisons are among the best to use considering the 
specifics of our Utah action. The commenter who disagreed with these 
comparisons did not show that it would make a significant difference to 
use precisely the same methodology in each of the determinations that 
EPA chose to rely on. Furthermore, we disagree that the methodology 
involved in the BART analyses necessarily must be precisely the same 
for each BART determination in order to use the determinations for 
comparison purposes. For example, a state may choose to use a slightly 
different methodology to analyze the BART factors and select BART, 
which is acceptable so long as the methodology is reasonable and 
consistent with the statute, RHR, and BART Guidelines. For details, 
please see the RTC document.
    We also disagree that the cited BART determinations in Montana, 
Florida, and Nebraska are useful comparisons or show that our BART 
determination here is unreasonable. First, with respect to the Florida 
action, the cited NOX BART determination at FPL's Manatee 
Plant involved two 800 MW oil and natural-gas fired steam turbines. 77 
FR 73369, 73377 (Dec. 10, 2012) (proposal). As the two units were 
equipped with FGR, overfire air systems, staged combustion, LNB, and 
reburn, SCR was the only available additional control option 
identified. The total annualized cost of SCR at the two units would be 
$31 million, from which the state computed a dollar-per-deciview cost 
of $66 million/dv. Id. at 73377. Using these figures, the total (i.e. 
source wide) visibility improvements at the most impacted Class I area, 
Chassahowitzka NWA, would be 0.47 dv, which is considerably below the 
source-wide visibility improvement for SCR + LNB/SOFA at Hunter and 
Huntington of 2.948 dv and 3.848 dv, respectively.\132\

[[Page 43918]]

In addition, the Manatee Plant impacted only one other Class I area, 
Everglades NP, at nearly twice the distance of Chassahowitzka NWA. In 
comparison, Hunter and Huntington significantly impact nine Class I 
areas. Furthermore, the Manatee Plant received a permit to increase 
natural gas utilization from 5,670 MMBtu/hr to 8,650 MMBtu/hr, which 
would displace the use of oil and provide additional NOX 
reductions. All of these must be considered when examining the state's 
conclusion that SCR would not be cost-effective for these units, which 
was primarily based on the dollar-per-deciview cost of $66 million/dv 
and not on the raw cost-effectiveness number of $3,776/ton. While we 
are not basing our BART determinations on the dollar-per-deciview 
metric, for purposes of comparison to Manatee, the dollar-per-deciview 
cost for Hunter and Huntington would be considerably less than at 
Manatee, about $23.7 million/dv and $15.8 million/dv, respectively, at 
the most impacted Class I area, and as mentioned earlier Hunter and 
Huntington impact many more Class I areas than Manatee.
---------------------------------------------------------------------------

    \132\ See also our response to comments on existing controls and 
the baseline, in which we look at the cost and visibility benefits 
at Hunter and Huntington of SCR apart from the LNB/SOFA, to show 
that even if we agreed with this commenter that the baseline should 
reflect the installation of LNB/SOFA--which we do not--the selection 
of SCR as BART would still be reasonable. The numbers used there 
also compare favorably with Manatee.
---------------------------------------------------------------------------

    With respect to the Montana action, EPA stated for PPL Colstrip 
Units 1 and 2, ``we estimated the incremental cost effectiveness of SCR 
+ SOFA (over SNCR + SOFA) to [be] $5,770/ton and $5,887/ton, 
respectively. Given these costs, we continue to find that SCR + SOFA is 
not justified by the visibility improvement that would be provided.'' 
77 FR 57864, 57889 (Sept. 18, 2012) (emphasis added). The commenter 
omits the emphasized language. The visibility improvements for the 
various NOX control options for Colstrip Units 1 and 2 can 
be seen in our proposal action and in general are much lower than those 
for Hunter and Huntington. See 77 FR 23988, 24026-27, 24034-35 (Apr. 
20, 2012). In particular, at Colstrip Unit 1, the visibility 
improvements from SCR + SOFA at the five impacted Class I areas (which 
is less than the nine impacted by Hunter and Huntington) ranged from 
0.081 to 0.404 dv. At Colstrip Unit 2, the visibility improvements from 
SCR + SOFA at the same class I areas ranged from 0.091 dv to 0.423 dv. 
These values are all much less than for the Hunter and Huntington BART 
units. In any case, our NOX BART determinations for Colstrip 
Units 1 and 2 were vacated by the Ninth Circuit Court of Appeals. Nat'l 
Parks Conserv. Ass'n v. U.S. EPA, 788 F.3d 1134 (9th Cir. 2014).\133\ 
Finally, commenter's citation to the Nebraska proposal is fully 
addressed by our response to a similar comment on our Wyoming regional 
haze action. 79 FR 5032, 5178 (Jan. 30, 2014). Please refer to our RTC 
document for additional discussion of our comparisons to other BART 
determinations.
---------------------------------------------------------------------------

    \133\ The same commenter notes that the Wyoming and Arizona BART 
determinations we used for comparison purposes are currently under 
litigation; however the commenter fails to note that the Montana 
BART determination they propose for comparison was actually 
litigated and vacated. With respect to the pending litigation over 
the Wyoming and Arizona BART determinations, there are other BART 
determinations such as Colorado's Hayden Station that are 
comparable, support our selection of SCR + LNB/SOFA, and are not 
under litigation.
---------------------------------------------------------------------------

H. CALPUFF Modeling

    Comment: We received many comments related to both EPA's modeling 
for the FIP and Utah's modeling for the BART Alternative. In 
particular, PacifiCorp and its consultant asserted that EPA failed to 
account for the margin of error in the CALPUFF model and other material 
limitations of CALPUFF. PacifiCorp also asserted that we should have 
used CALPUFF version 6.42 in our FIP analysis instead of version 5.8.4. 
We partially respond to these comments here. Our full responses are 
contained in our RTC document.
    Response: We do not agree with the commenter's criticism of the use 
of CALPUFF. In promulgating the 2005 BART Guidelines, we responded to 
comments concerning the limitations and appropriateness of using 
CALPUFF. In 2005 we explained that CALPUFF is the only EPA-approved 
model for use in estimating single source pollutant concentrations 
resulting from the long range transport of primary pollutants. In 
addition, it can also be used for other purposes such as visibility 
assessments to account for the chemical transformations of 
SO2 and NOX. As explained earlier, simulating the 
effect of precursor pollutant emissions on PM2.5 
concentrations requires air quality modeling that not only addresses 
transport and diffusion, but also chemical transformations. CALPUFF 
incorporates algorithms for predicting both. At a minimum, CALPUFF can 
be used to estimate the relative impacts of BART-eligible sources. We 
are confident that CALPUFF distinguishes, comparatively, the relative 
contributions from sources such that the differences in source 
configurations, sizes, emission rates, and visibility impacts are well-
reflected in the model results.\134\
---------------------------------------------------------------------------

    \134\ 70 FR 39122 (Jul. 6, 2005) (emphasis added).
---------------------------------------------------------------------------

    EPA also recognized the uncertainty in the CALPUFF modeling results 
when EPA made the decision (in the final BART Guidelines) to recommend 
that states use the 98th percentile visibility impairment rather than 
the highest daily impact value. We made the decision to consider the 
98th percentile primarily because the chemistry modules in the CALPUFF 
model are simplified and likely to provide conservative (higher) 
results for peak impacts. Since CALPUFF's simplified chemistry could 
lead to model over predictions, EPA recommended the use of the 98th 
percentile to avoid giving undue weight to the extreme tail of the 
distribution.\135\ Therefore, in recognizing some of the limitations of 
the CALPUFF model, we determined that use of the maximum modeled impact 
may be overly conservative and recommended the use of the 98th 
percentile value. While recognizing the limitations of the CALPUFF 
model in the BART Guidelines preamble, EPA concluded that, for the 
specific purposes of the RHR's BART provisions, CALPUFF is sufficiently 
reliable to inform the decision making process.\136\
---------------------------------------------------------------------------

    \135\ ``Most important, the simplified chemistry in the model 
tends to magnify the actual visibility effects of that source. 
Because of these features and the uncertainties associated with the 
model, we believe it is appropriate to use the 98th percentile--a 
more robust approach that does not give undue weight to the extreme 
tail of the distribution.'' 70 FR 39104, 39121 (Jul. 6, 2005).
    \136\ 70 FR 39123 (Jul. 6, 2005).
---------------------------------------------------------------------------

    It is further worth noting that the CALPUFF model can both predict 
higher and lower visibility impacts compared to a photochemical grid 
model. For example, the 2012 ENVIRON report on Comparison of Single-
Source Air Quality Assessment Techniques for Ozone, PM2.5, other 
criteria pollutants and AQRVs found that CALPUFF's predictions of the 
highest 24-hr nitrate and sulfate concentrations were lower than those 
predicted by the CAMx photochemical grid model in some areas within the 
modeling domain.\137\ Thus, while there is some uncertainty in the 
absolute visibility impacts and benefits due to the model and some of 
the simplifications and assumptions used in the BART Guidelines 
modeling approach, the relative level of impact has been a reliable 
assessment of the degree of visibility impacts and benefit from 
controls. Any uncertainties in meteorological conditions that govern 
the transport and diffusion of pollutants are less important in 
comparing impacts between two control scenarios, since the

[[Page 43919]]

same effects will be included in both the base and the control scenario 
model simulations.
---------------------------------------------------------------------------

    \137\ Comparison of Single-Source Air Quality Assessment 
Techniques for Ozone, PM2.5, other Criteria Pollutants 
and AQRVs, ENVIRON, September 2012.
---------------------------------------------------------------------------

    We also do not agree with the commenter's calculation of a ``margin 
of error'' for CALPUFF. The notion of a calculated ``margin of error'' 
is not part of any modeling guidance and has no legal or regulatory 
basis or applicability here. In addition, the commenter's suggestion 
that a 2012 report titled ``Documentation of the Evaluation of CALPUFF 
and Other Long Range Transport Models Using Tracer Field Experiment 
Data'', EPA-454/R-12-003 (ENVIRON Report) establishes a standard 
``margin of error'' for CALPUFF is unfounded. The ENVIRON Report 
illustrated how well various types of modeling systems are able to 
capture regional transport. It does not provide any information about 
the accuracy of any models for predicting secondary PM2.5 or 
visibility, nor does it indicate that the quantitative performance 
results provided are a presumptive globally applicable ``margin of 
error.'' Rather, these results are simply a way to compare various 
modeling systems in terms of performance for skill in long range 
transport. Thus, we do not agree that the ENVIRON Report provides a 
presumptive margin of error that can be applied to the modeling results 
in Utah's SIP or EPA's FIP.
    With regard to Utah's use of CALPUFF in its SIP revision 
specifically, we note that the State was not required to use CALPUFF 
for purposes of its BART Alternative Demonstration under 40 CFR 
51.308(e)(2)(i). Utah or PacifiCorp could have used other EPA-approved 
models with more advanced chemistry and dispersion techniques to 
support the BART Alternative demonstration but chose not to do so.
    With regard to our use of CALPUFF for purposes of the FIP modeling, 
as explained in more detail in our RTC document, the legal deadline for 
challenging EPA's recommendation to use CALPUFF in BART analyses has 
passed. Furthermore, although the EPA proposed revisions to 40 CFR part 
51, appendix W, Guideline on Air Quality Models (``Guideline'') in 
2015, these proposed changes to the Guideline do not affect our 
recommendation in the 2005 BART Guidelines to use CALPUFF in the BART 
determination process.\138\ Rather, as explained in the preamble to the 
proposed Guideline revisions, we consider it appropriate to continue 
using CALPUFF for BART determinations, given that the vast majority of 
BART determinations have been made using CALPUFF.\139\
---------------------------------------------------------------------------

    \138\ 80 FR 45340, 45350 (July 29, 2015).
    \139\ Id.
---------------------------------------------------------------------------

    In particular, for our FIP modeling, we used the current EPA-
approved version of CALPUFF (Version 5.8.4, Level 130731). We disagree 
with the commenters that a new CALPUFF version should be used for the 
BART determinations. We relied on version 5.8 of CALPUFF because it is 
the version approved by EPA through a public notice-and-comment 
rulemaking, in accordance with the Guidelines (40 CFR part 51, appendix 
W, section 6.2.1.e). Later versions of CALPUFF are not approved by EPA 
for regulatory purposes, and we do not agree that the changes made to 
this most recent version of CALPUFF were simple model updates to 
address bugs. A full evaluation of a new model such as CALPUFF version 
6.4 is needed before it should be used for regulatory purposes as 
errors that are not immediately apparent can be introduced along with 
new model features.
    In response to comments, EPA performed additional modeling analysis 
to assess the combined benefit of SCR when applied to each of the two 
BART units at the Hunter facility. We did the same for the Huntington 
facility. These modeling results are shown in Tables 6 and 7 earlier in 
this document. Otherwise, we did not receive any comments that 
convinced us to alter our CALPUFF modeling analysis, and the comments 
we received do not justify a change in our BART determinations or our 
evaluation of the State's BART Alternative. We discuss these and other 
modeling comments in detail in our RTC document.

I. Consideration of Existing Controls

    Comment: Several commenters asserted that EPA did not properly take 
into account the existing pollution control technology in use at the 
Hunter and Huntington BART units, as required by CAA section 169A(g)(2) 
and the BART Guidelines. Two of these commenters alleged that EPA was 
required to consider updated combustion controls, which were installed 
to comply with Utah's regional haze SIP. The commenters said EPA 
improperly used 2001-2003 emissions data to establish the baseline 
emissions for the Utah BART Units and that this is neither realistic 
nor provides the anticipated emissions as required by the BART 
Guidelines. The commenters asserted that had EPA relied on more recent 
emissions data, which reflect the NOX reductions achieved by 
some of these newly installed controls, the cost-effectiveness values 
for SCR would have been higher, while the visibility improvement 
associated with SCR would have been lower.
    Commenters pointed to an 8th Circuit court decision on EPA's final 
action on the North Dakota regional haze SIP where the Court found that 
EPA had failed to properly consider the existing pollution control 
technology at the Coal Creek Station. Commenters also asserted that in 
other EPA regional haze actions, EPA had adjusted baseline emissions to 
account for recently installed controls, such as EPA's final actions on 
the Arizona and Colorado regional haze SIPs, and settlement agreement 
with EPA Region 8 for the Deseret Bonanza plant. This commenter argued 
that because EPA had adjusted baseline emissions for some Arizona and 
Colorado EGUs to account for controls recently installed to satisfy 
consent decrees obligations or CAA requirements unrelated to regional 
haze, EPA was required to do so for Utah's EGUs as well.
    Two final commenters submitted supportive comments regarding the 
need for using a standard baseline period to provide for greater 
national consistency. One of these commenters noted examples where EPA 
has evaluated NOX BART based on a baseline period from 
before the installation of the pollution controls, for the Navajo 
regional haze plan and the Wyoming regional haze plan.
    Response: We disagree with comments that EPA failed to consider or 
unreasonably considered the existing pollution control technology at 
the Hunter and Huntington BART units. One of the statutory factors EPA 
is to consider for BART is ``any existing pollution control technology 
in use at the source.'' 42 U.S.C. 7491(g)(2). The CAA and the BART 
Guidelines do not specify how states or EPA must ``take into 
consideration'' this factor. Nor did the Eighth Circuit Court of 
Appeals specify how existing controls must be taken into account; 
instead it only examined the meaning of the word ``any,'' holding that 
EPA misinterpreted the term. North Dakota v. U.S. EPA, 730 F.3d 750, 
762-64 (8th Cir. 2013). The Court did not examine the meaning of the 
phrase ``take into consideration.'' See id. As the statute is silent on 
how to take into consideration existing controls, under Chevron U.S.A. 
v. NRDC, 467 U.S. 837, 843-44 (1984), this silence creates a gap for 
EPA to fill. As next summarized and detailed in our RTC document, we 
are reasonably considering existing controls in several ways.

[[Page 43920]]

    First, the BART Guidelines state that existing pollution control 
technology in use at the source affects the availability of control 
options and their impacts. 40 CFR part 51, appendix Y, at IV.A. The 
Guidelines go on to explain that ``[f]or emission units subject to a 
BART review, there will often be control measures or devices already in 
place. For such emission units, it is important to include control 
options that involve improvements to existing controls and not to limit 
the control options only to those measures that involve a complete 
replacement of control devices.'' 40 CFR part 51, appendix Y, at 
IV.D.1.6. We have followed this recommendation. We find that the 
existing combustion controls, LNB/SOFA, cannot be reasonably upgraded, 
and we are not considering a control option that involves their 
complete replacement. The post-combustion control options, SNCR and 
SCR, by their nature can operate independently of combustion controls 
and without changes to the combustion controls, another way in which we 
considered the existing controls when evaluating SNCR and SCR.
    Consistent with the Guidelines' statement that existing pollution 
control equipment in use at the source affects the impacts of the 
control options, we used the sources' current NOX emission 
rates when we evaluated the size, design, and reagent/catalyst cost of 
SNCR and SCR. For example, in the case of Hunter Unit 1, we did not use 
the baseline emission rate of 0.40 lb/MMBtu, but rather the current 
emission rate of 0.21 lb/MMBtu that appropriately reflects the 
installation of LNB/SOFA. Due to the lower NOX emission 
rate, the size of the SNCR and SCR systems and the amount of reagent/
catalyst necessary to operate them are lower than if we had simply 
assumed the baseline emission rate. This is a reasonable way in which 
to consider existing pollution control technology.
    As discussed in our Wyoming action and in additional detail in our 
RTC document for this action, baseline emissions should be ``a 
realistic depiction of anticipated annual emissions'' before the 
installation of BART. 40 CFR part 51, appendix Y, at IV.D.4.d. Because 
the LNB/OFA were installed pursuant to Utah's proposed BART 
determination, we used the period 2001-2003, prior to the installation 
of LNB/OFA at the Hunter and Huntington BART units, for baseline 
emissions, which in turn we used to evaluate the cost-effectiveness and 
visibility of control options. As a result, the existing LNB/OFA were 
not included in the baseline. According to the commenter, this skewed 
EPA's analysis.
    We disagree. Because we have also considered the existing controls 
in our final BART determination by examining the cost-effectiveness and 
visibility benefit of SNCR and SCR relative to the existing LNB/SOFA as 
well as in tandem with LNB/SOFA, we have avoided any possibility that 
exclusion of the LNB/OFA from the baseline could result in an 
unreasonable BART selection. The cost-effectiveness values of SCR and 
SNCR relative to the existing LNB/SOFA are presented in the per-unit 
tables for Hunter and Huntington (Tables 2-5) under ``Incremental cost-
effectiveness.'' In other words, the cost-effectiveness value for SCR 
alone (assuming the existing LNB/SOFA) is essentially the same as the 
incremental cost-effectiveness of SCR + LNB/SOFA as compared to LNB/
SOFA that is presented in the tables. As can be seen, the incremental 
cost-effectiveness values of SCR + LNB/SOFA relative to LNB/SOFA are, 
for all four units, somewhat lower than the incremental cost-
effectiveness of SCR relative to SNCR. As explained in the section 
giving the rationale for our final action, we find the incremental 
cost-effectiveness of SCR to be reasonable relative to SNCR; therefore 
it is also reasonable relative to the existing LNB/SOFA.
    Another way to make the same point is to, for the sake of argument, 
accept (which we do not) commenter's position that the baseline should 
reflect the LNB/SOFA. In that case, the values in the tables for the 
incremental cost-effectiveness of SCR + LNB/SOFA relative to LNB/SOFA 
can serve as a proxy for the average cost-effectiveness of SCR 
(assuming LNB/SOFA in the baseline). As shown by our comparisons, the 
incremental cost-effectiveness of SCR + LNB/SOFA is generally 
reasonable given the visibility benefits. This in turn shows that, even 
accepting for the sake of argument that LNB/SOFA should be reflected in 
the baseline, the average cost-effectiveness of SCR remains reasonable. 
Similar considerations apply to the incremental visibility benefits of 
SCR + LNB/SOFA relative to LNB/SOFA, which can be used as a proxy for 
the visibility benefits of SCR alone assuming that LNB/SOFA are 
reflected in the baseline. As shown by our comparisons, the incremental 
visibility benefits of SCR + LNB/SOFA relative to SNCR + LNB/SOFA are 
substantial and justify the costs of SCR. Since the incremental 
visibility benefits of SCR + LNB/SOFA relative to LNB/SOFA are 
necessarily larger than the incremental benefits relative to SNCR + 
LNB/SOFA, the incremental visibility benefits of SCR + LNB/SOFA 
relative to LNB/SOFA will also justify the costs of SCR. This in turn 
shows that even if we accepted the commenter's position--which we do 
not--the visibility benefits of SCR would justify its selection. For 
our detailed responses, please see our RTC document.
    Finally, we acknowledge the supportive comments from two commenters 
on this issue and agree with many of the points that were made, for 
reasons explained elsewhere in this document and in our RTC document.

J. PM10 BART

    Comment: We received several minor comments on Utah's 
PM10 BART determinations. One commenter in particular 
asserted that Utah underestimated the control effectiveness of 
baghouses, which should be able to achieve a limit of 0.010 lb/MMBtu or 
even lower.
    Response: EPA agrees that baghouses have very high PM control 
efficiency capabilities. However, due to the low contribution of direct 
PM emissions from point sources such as Hunter Units 1 and 2 and 
Huntington Units 1 and 2 \140\ to visibility impairment and, 
consequently, the low anticipated visibility benefits from small PM 
reductions, lowering the emission limit to 0.010 is unlikely to result 
in any meaningful visibility improvement. We agree with Utah that the 
existing PM10 emission limit adopted for these sources in 
Section IX, Part H.22 of Utah's SIP satisfies BART for these units. We 
are finalizing our approval of Utah's PM10 BART 
determination at Hunter Units 1 and 2 and Huntington Units 1 and 2. We 
find that an emission limit of 0.015 lb/MMBtu represents what can be 
continuously achieved with a properly operated baghouse on these units. 
The fabric filters (i.e., baghouses) at Hunter and Huntington are all 
new since they were installed after 2008. Recent PSD BACT limits for 
coal-fired EGUs with new baghouses have typically ranged from 0.01 to 
0.015 lb/MMBtu using Method 5.
---------------------------------------------------------------------------

    \140\ See Western Regional Air Partnership Regional Haze Rule 
Reasonable Progress Summary Report, Air Resource Specialist, Inc., 
State and Class I Area Summaries, Appendix p. 6-29, Table 6.13-19 
(June 28, 2013). Available in the docket and at http://www.wrapair2.org/RHRPR.aspx.
---------------------------------------------------------------------------

    In addition, we note that the latest revision to the EGU New Source 
Performance Standards (NSPS) requires modified units to meet a PM limit 
of 0.015 lb/MMBtu.\141\ Also, the EGU MATS rule set a PM emissions 
standard

[[Page 43921]]

of 0.03 lb/MMBtu as MACT for existing EGUs, and the BART Guidelines 
provide that, ``unless there are new technologies subsequent to the 
MACT standards which would lead to cost-effective increases in the 
level of control, you may rely on the MACT standards for purposes of 
BART.'' \142\ Therefore, we are finalizing our proposed approval of 
Utah's BART determination for PM10 at Hunter Units 1 and 2 
and Huntington Units 1 and 2.
---------------------------------------------------------------------------

    \141\ 77 FR 9450 (Feb. 16, 2012) (codified at 40 CFR 60.42Da).
    \142\ 40 CFR part 51, appendix Y, section IV.C. While the 
Supreme Court reversed the D.C. Circuit's judgment on the MATS rule, 
the Supreme Court did so based on EPA's approach to the 
``appropriate and necessary'' finding, not EPA's determination of 
MACT for EGUs. Michigan v. EPA, 135 S. Ct. 2699 (2015).
---------------------------------------------------------------------------

K. Environmental Justice

    Comment: One commenter requested that EPA's FIP address any 
disproportionately high and adverse human health, economic, and 
environmental impacts on minority and low-income communities in Utah 
due to the regional haze plan. The commenter noted that this may be 
accomplished consistent with federal Executive Order 12898, which 
establishes environmental justice policy. The commenter also noted that 
societal costs such as general public health costs associated with poor 
air quality should be considered in the environmental justice analysis.
    Response: In making a final determination in this case, EPA 
considered Executive Order 12898, which establishes federal executive 
policy on environmental justice. This Executive Order directs federal 
agencies, to the greatest extent practicable and permitted by law, to 
make environmental justice part of their mission by identifying and 
addressing, as appropriate, disproportionately high and adverse human 
health or environmental effects of their programs, policies, and 
activities on minority populations and low-income populations in the 
United States. EPA has determined that this final rule will not have 
disproportionately high and adverse human health or environmental 
effects on minority or low-income populations. The installation of SCR 
at the two facilities will ensure greater emissions reductions of 
NOX resulting in overall increases in the level of 
environmental protection for all affected populations.
    EPA disagrees with the comment that societal costs such as general 
public health costs associated with poor air quality should be 
considered in the environmental justice analysis for this action. As 
addressed elsewhere in our RTC document, neither section 169A of the 
CAA, nor the BART Guidelines, require the BART analysis to include or 
quantify benefits to health, as health impacts are appropriately 
addressed under other CAA programs. Moreover, an analysis of societal 
costs is unlikely to alter the impact relating to environmental justice 
concerns because the final rule will result in greater protection for 
all affected populations as a result of the installation of the most 
stringent control technology available for NOX.

III. Final Action

    For the reasons discussed more fully in sections I and II and 
detailed in our proposal and its accompanying supporting materials, in 
this action, we are partially approving and partially disapproving 
revisions to the Utah SIP submitted by the State of Utah on June 4, 
2015. We are taking no action on the Utah SIP submittal of October 20, 
2015.
    Section 110(k)(3) of the Act addresses the situation in which an 
entire submittal, or a separable portion of a submittal, meets all 
applicable requirements of the Act. In the case where a separable 
portion of the submittal meets all the applicable requirements, partial 
approval may be used to approve that part of the submittal and 
disapprove the remainder. Since the portions of the regional haze SIP 
submittal we are approving are separable from the portions we are 
disapproving as explained earlier, each approved PM10 BART 
determination for a particular pollutant for a given source will have 
an enforceable date of five years from the date of EPA's approval.
    Under section 110(k)(4) of the Act, EPA may approve a submittal 
based on a commitment of the State to adopt specific enforceable 
measures no later than one year after the date of approval of the 
submittal. We are conditionally approving the State's recordkeeping 
requirements for the PM BART emission limitations based on Utah's 
commitment to adopt and submit certain measures to address the 
deficiencies in the recordkeeping requirements. If the State fails to 
adopt and submit these measures within one year of this action, our 
conditional approval will be treated as a disapproval.
    Under section 110(c)(1)(B) of the Act, within two years of 
disapproving a required submittal in whole or in part, EPA must 
promulgate a FIP to address the deficiencies, unless the State corrects 
the deficiencies through a submittal and EPA approves the submittal 
before we promulgate a FIP. As a result of our prior disapproval of 
Utah's PM and NOX BART submittals in 2012, there was a 
pending obligation for EPA to promulgate a FIP for PM and 
NOX BART. In this action, we are promulgating a FIP for 
NOX BART. Because we are approving Utah's revised PM BART 
submittal, which corrects the previous deficiencies in the original PM 
BART submittal, there is no longer an obligation for EPA to promulgate 
a FIP for PM BART. Thus, EPA has discharged its FIP obligations with 
respect to PM and NOX BART for the State of Utah.

A. Final Partial Approval

    1. We are approving these elements of the State's SIP submittals, 
which rely on elements from prior approvals: \143\
---------------------------------------------------------------------------

    \143\ As necessary for our approval, we are filling gaps in the 
2015 Utah regional haze RH SIP submittals with the following 
already-approved sections from the 2011 Utah RH SIP: Section XX.B.8, 
Figures 1 and 2, Affected Class I Areas, pp. 8-9; Section XX.D.6.b, 
Table 3, BART-Eligible Sources in Utah, p. 21; Section. XX.D.6.c, 
Sources Subject to BART, pp. 21-23.
---------------------------------------------------------------------------

     BART determinations and emission limits for 
PM10 at Hunter Units 1 and 2 and Huntington Units 1 and 2.
     Monitoring, recordkeeping, and reporting requirements for 
units subject to the PM10 emission limits, including 
conditional approval of the recordkeeping requirements for the 
PM10 emission limits.

B. Final Partial Disapproval and Federal Implementation Plan

    1. We are disapproving these aspects of the State's June 4, 2015 
SIP submittal:
     NOX BART Alternative that includes 
NOX, and SO2 emission reductions from Hunter 
Units 1 through 3, Huntington 1 and 2, and Carbon Units 1 and 2, and 
PM10 emission reductions from Carbon Units 1 and 2.
     Monitoring, recordkeeping and reporting requirements for 
units subject to the BART Alternative.
    2. We are promulgating a FIP to address the deficiencies in the 
Utah regional haze SIP. The FIP includes the following elements:
     NOX BART determinations and limits for Hunter 
Units 1 and 2, Huntington Units 1 and 2.
     Monitoring, recordkeeping, and reporting requirements 
applicable to Hunter Units 1 and 2, and Huntington Units 1 and 2.

C. No Action

    1. We are taking no action on the State's October 20, 2015 SIP 
submittal which includes the following:
     The enforceable commitments to revise, at a minimum, SIP 
Section XX.D.3.c and State rule R307-150 by March 2018.

[[Page 43922]]

IV. Incorporation by Reference

    In this rule, the EPA is finalizing regulatory text that includes 
incorporation by reference. In accordance with requirements of 1 CFR 
51.5, the EPA is finalizing the incorporation by reference of the Utah 
Administrative Code discussed in section III, Final Action of this 
preamble. The EPA has made, and will continue to make, these documents 
generally available electronically through www.regulations.gov and/or 
in hard copy at the appropriate EPA office (see the ADDRESSES section 
of this preamble for more information).

V. Statutory and Executive Order Reviews

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

    This action is exempt from review by the Office of Management and 
Budget (OMB) because this final rule applies to only two facilities 
containing four BART units. It is therefore not a rule of general 
applicability.

B. Paperwork Reduction Act

    This action does not impose an information collection burden under 
the provisions of the Paperwork Reduction Act (PRA).\144\ Because this 
final rule applies to just two facilities, the PRA does not apply.
---------------------------------------------------------------------------

    \144\ 44 U.S.C. 3501 et seq.
---------------------------------------------------------------------------

C. Regulatory Flexibility Act

    I certify that this action will not have a significant economic 
impact on a substantial number of small entities under the RFA. This 
action will not impose any requirements on small entities.
    EPA is partially disapproving the State's SIP submittal and 
promulgating a FIP that consists of imposing federal controls to meet 
the BART requirement for emissions on four specific BART units at two 
facilities in Utah. The net result of this action is that EPA is 
requiring direct emission controls on selected units at only two 
sources, and those sources are large electric generating plants that 
are not owned by small entities, and therefore the owners are not a 
small entities under the RFA.

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.
    EPA has determined that Title II of the UMRA does not apply to this 
rule. In 2 U.S.C. 1502(1) all terms in Title II of UMRA have the 
meanings set forth in 2 U.S.C. 658, which further provides that the 
terms ``regulation'' and ``rule'' have the meanings set forth in 5 
U.S.C. 601(2). Under 5 U.S.C. 601(2), ``the term `rule' does not 
include a rule of particular applicability relating to . . . 
facilities.'' Because this rule is a rule of particular applicability 
relating to all four BART units at the Hunter and Huntington plants, 
EPA has determined that it is not a ``rule'' for the purposes of Title 
II of the UMRA. The private sector expenditures that result from 
promulgating a FIP include BART controls for all four units at the 
Hunter and Huntington plants are $58.6 million \145\ per year. 
Additionally, we do not foresee significant costs (if any) for state 
and local governments. Thus, because the annual expenditures associated 
with promulgating a FIP are less than the threshold of $100 million in 
any one year, this final rule is not subject to the requirements of 
sections 202 or 205 of UMRA. This final rule is also not subject to the 
requirements of section 203 of UMRA because it contains no regulatory 
requirements that might significantly or uniquely affect small 
governments.
---------------------------------------------------------------------------

    \145\ Andover Technology Partners, Cost of NOX BART Controls on 
Utah EGUs, to EC/R, Inc. (May 13, 2016). Andover Technology Partners 
is a subcontractor to EC/R Incorporated.
---------------------------------------------------------------------------

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 
tribal governments. 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 environmental health or safety risks 
that the EPA has reason to believe may disproportionately affect 
children, per the definition of ``covered regulatory action'' in 
section 2-202 of the Executive Order. This action is not subject to 
Executive Order 13045 because the EPA does not believe the 
environmental health or safety risks addressed by this action present a 
disproportionate risk to children. Moreover, ``regulation'' or 
``rule,'' is defined in Executive Order 12866 as ``an agency statement 
of general applicability and future effect.'' E.O. 12866 does not 
define ``statement of general applicability,'' but this term commonly 
refers to statements that apply to groups or classes, as opposed to 
statements, which apply only to named entities. The FIP therefore is 
not a rule of general applicability because its requirements apply and 
are tailored to only the Hunter and Huntington plants, which are 
individually identified facilities. Thus, it is not a ``rule'' or 
``regulation'' within the meaning of E.O. 12866. However, as this 
action will limit emissions of NOX, it will have a 
beneficial effect on children's health by reducing air pollution.

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.

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 within the docket 
in a document entitled ``Environmental Justice Analysis, November 
2015.'' This final rule will result in overall emission reductions for 
NOX, and PM10 and therefore an increase in the 
level of environmental protection for all affected populations.

K. Congressional Review Act

    This action is not subject to the CRA because this is a rule of 
particular applicability. Additionally, this action

[[Page 43923]]

is not a ``major rule'' as defined by 5 U.S.C. 804(2).

L. Judicial Review

    Under section 307(b)(1) of the CAA, petitions for judicial review 
of this action must be filed in the United States Court of Appeals for 
the appropriate circuit by September 6, 2016. Pursuant to CAA section 
307(d)(1)(B), this action is subject to the requirements of CAA section 
307(d) as it promulgates a FIP under CAA section 110(c). Filing a 
petition for reconsideration by the Administrator of this final rule 
does not affect the finality of this action for the purposes of 
judicial review nor does it extend the time within which a petition for 
judicial review may be filed, and shall not postpone the effectiveness 
of such rule or action. This action may not be challenged later in 
proceedings to enforce its requirements. See CAA section 307(b)(2).

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

List of Subjects in 40 CFR Part 52

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

    Dated: June 1, 2016.
Gina McCarthy,
Administrator.
    40 CFR part 52 is amended as follows:

PART 52--APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS

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

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

Subpart TT--Utah

0
2. Section 52.2320 is amended by:
0
a. In the table in paragraph (c), under the heading ``R307-110. General 
Requirements: State Implementation Plan'' revising the entry ``R307-
110-17.''
0
b. In the table in paragraph (e), under the heading ``XVII. Visibility 
Protection'' adding in numerical order the entry ``Section XX.D.6. Best 
Available Retrofit Technology (BART) Assessment for NOX and 
PM''.
    The revision and addition read as follows:

Sec.  52.2320  Identification of plan.

* * * * *
    (c) * * *

----------------------------------------------------------------------------------------------------------------
                                                             State           Final rule
             Rule No.                   Rule title      effective date     citation, date          Comments
----------------------------------------------------------------------------------------------------------------
 
                                                  * * * * * * *
----------------------------------------------------------------------------------------------------------------
                            R307-110. General Requirements: State Implementation Plan
----------------------------------------------------------------------------------------------------------------
 
                                                  * * * * * * *
----------------------------------------------------------------------------------------------------------------
R307-110-17......................  Section IX. Control        6/4/2015  [Insert Federal      Except for Section
                                    Measures for Area                    Register citation]   IX.H.21.e. which
                                    and Point Sources,                   7/5/2016.            is conditionally
                                    Part H, Emissions                                         approved through
                                    Limits.                                                   one year from
                                                                                              [Insert date of
                                                                                              publication in the
                                                                                              Federal Register],
                                                                                              IX.H.21.g.,
                                                                                              Sections of
                                                                                              IX.H.21 that
                                                                                              reference and
                                                                                              apply to the
                                                                                              source specific
                                                                                              emission
                                                                                              limitations
                                                                                              disapproved in
                                                                                              Section IX.H.22,
                                                                                              and Sections
                                                                                              IX.H.22.a.ii-iii,
                                                                                              IX.H.22.b.ii, and
                                                                                              IX.H.22.c.
----------------------------------------------------------------------------------------------------------------
 
                                                  * * * * * * *
----------------------------------------------------------------------------------------------------------------

* * * * *
    (e) * * *

----------------------------------------------------------------------------------------------------------------
                                               State
               Rule title                 effective date   Final rule citation, date           Comments
----------------------------------------------------------------------------------------------------------------
 
                                                  * * * * * * *
----------------------------------------------------------------------------------------------------------------
XVII. Visibility Protection
----------------------------------------------------------------------------------------------------------------
 

[[Page 43924]]

 
                                                  * * * * * * *
----------------------------------------------------------------------------------------------------------------
Section XX.D.6. Best Available Retrofit         6/4/2015  [Insert Federal Register    Except for XX.D.6.a the
 Technology (BART) Assessment for NOX                      citation] 7/5/2016.         phrase ``and BART for NOX
 and PM.                                                                               through alternative
                                                                                       measures under 40 CFR
                                                                                       51.308(e)(2)''; XX.D.6.c;
                                                                                       XX.D.6.d the phrase ``NOX
                                                                                       and'' in the first
                                                                                       sentence, the entire last
                                                                                       sentence in the
                                                                                       introductory paragraph,
                                                                                       all SO2 and NOX
                                                                                       provisions and the word
                                                                                       ``Permitted'' in the
                                                                                       ``Utah Permitted Limits''
                                                                                       column in Table 5,
                                                                                       ``Hunter 3'' and the
                                                                                       Hunter limits, and all
                                                                                       provisions in the
                                                                                       ``Presumptive BART
                                                                                       Rates'' column in Table
                                                                                       5; XX.D.6.e the phrase
                                                                                       ``, and pursuant to
                                                                                       51.308(e)(2)(E)(3) all
                                                                                       alternative measures must
                                                                                       take place within the
                                                                                       first planning period'',
                                                                                       the rows beginning with
                                                                                       ``Hunter 3'', ``Carbon
                                                                                       1'' and ``Carbon 2'' in
                                                                                       Table 6, and the entire
                                                                                       paragraph immediately
                                                                                       following Table 6.
----------------------------------------------------------------------------------------------------------------
 
                                                  * * * * * * *
----------------------------------------------------------------------------------------------------------------

0
3. Section 52.2336 is added to read as follows:

Sec.  52.2336  Federal implementation plan for regional haze.

    (a) Applicability. (1) This section applies to each owner and 
operator of the following emissions units in the State of Utah:
    (i) PacifiCorp Hunter Plant Units 1 and 2; and
    (ii) PacifiCorp Huntington Plant Units 1 and 2.
    (2) [Reserved]
    (b) Definitions. Terms not defined in this paragraph (b) shall have 
the meaning given them in the Clean Air Act or EPA's regulations 
implementing the Clean Air Act. For purposes of this section:
    (1) BART means Best Available Retrofit Technology.
    (2) BART unit means any unit subject to a Regional Haze emission 
limit in Table 1 of this section.
    (3) Continuous emission monitoring system or CEMS means the 
equipment required by this section to sample, analyze, measure, and 
provide, by means of readings recorded at least once every 15 minutes 
(using an automated data acquisition and handling system (DAHS)), a 
permanent record of NOX emissions, diluent, or stack gas 
volumetric flow rate.
    (4) FIP means Federal Implementation Plan.
    (5) The term lb/MMBtu means pounds per million British thermal 
units of heat input to the fuel-burning unit.
    (6) NOX means nitrogen oxides.
    (7) Operating day means a 24-hour period between 12 midnight and 
the following midnight during which any fuel is combusted at any time 
in the BART unit. It is not necessary for fuel to be combusted for the 
entire 24-hour period.
    (8) The owner/operator means any person who owns or who operates, 
controls, or supervises a unit identified in paragraph (a) of this 
section.
    (9) Unit means any of the units identified in paragraph (a) of this 
section.
    (c) Emission limitations. (1) The owners/operators of emission 
units subject to this section shall not emit, or cause to be emitted, 
NOX in excess of the following limitations:

     Table 1 to Sec.   52.2336--Emission limitations for BART Units
------------------------------------------------------------------------
                                                           NOX Emission
                                                         limitation--lb/
                                                          MMBtu (30-day
                 Source name/BART unit                       rolling
                                                             average)
 
------------------------------------------------------------------------
PacifiCorp Hunter Plant/Unit 1 \1\.....................             0.07
PacifiCorp Hunter Plant/Unit 2 \1\.....................             0.07
PacifiCorp Huntington Plant/Unit 1 \1\.................             0.07
PacifiCorp Huntington Plant/Unit 2 \1\.................             0.07
------------------------------------------------------------------------
\1\ The owners and operators of PacifiCorp Hunter Units 1 and 2 and
  Huntington Units 1 and 2, shall comply with the NOX emission limit for
  BART of 0.07 lb/MMBtu and other requirements of this section by August
  4, 2021.

    (2) These emission limitations shall apply at all times, including 
startups, shutdowns, emergencies, and malfunctions.
    (d) Compliance date. (1) The owners and operators of PacifiCorp 
Hunter Units 1 and 2 shall comply with the NOX emission 
limitation of 0.07 lb/MMBtu and other requirements of this section by 
August 4, 2021. The owners and operators of PacifiCorp Huntington Units 
1 and 2 shall comply with the NOX emission limitation of 
0.07 lb/MMBtu and other requirements of this section by August 4, 2021.
    (2) [Reserved]
    (e) Compliance determinations for NOX. (1) For all BART 
units:
    (i) CEMS. At all times after the earliest compliance date specified 
in paragraph (d) of this section, the owner/operator of each unit shall 
maintain, calibrate, and operate a CEMS, in full compliance with the 
requirements found at 40 CFR part 75, to accurately measure 
NOX, diluent, and stack gas volumetric flow rate from each 
unit. The CEMS shall be used to determine compliance with the emission 
limitations in paragraph (c) of this section for each unit.
    (ii) Method. (A) For any hour in which fuel is combusted in a unit, 
the owner/operator of each unit shall calculate the hourly average 
NOX emission rate in lb/MMBtu at the CEMS in accordance with 
the requirements of 40 CFR part 75. At the end of each operating day, 
the owner/operator shall calculate and record a new 30-day rolling 
average emission rate in lb/MMBtu from the arithmetic average of all 
valid hourly emission rates from the CEMS for the current operating day 
and the previous 29 successive operating days.
    (B) An hourly average NOX emission rate in lb/MMBtu is 
valid only if the minimum number of data points, as specified in 40 CFR 
part 75, is acquired by both the pollutant concentration

[[Page 43925]]

monitor (NOX) and the diluent monitor (O2 or 
CO2).
    (C) Data reported to meet the requirements of this section shall 
not include data substituted using the missing data substitution 
procedures of subpart D of 40 CFR part 75, nor shall the data have been 
bias adjusted according to the procedures of 40 CFR part 75.
    (2) [Reserved]
    (f) Recordkeeping. The owner/operator shall maintain the following 
records for at least five years:
    (1) All CEMS data, including the date, place, and time of sampling 
or measurement; parameters sampled or measured; and results.
    (2) Records of quality assurance and quality control activities for 
emissions measuring systems including, but not limited to, any records 
required by 40 CFR part 75.
    (3) Records of all major maintenance activities conducted on 
emission units, air pollution control equipment, and CEMS.
    (4) Any other CEMS records required by 40 CFR part 75.
    (g) Reporting. All reports under this section shall be submitted to 
the Director, Office of Enforcement, Compliance and Environmental 
Justice, U.S. Environmental Protection Agency, Region 8, Mail Code 
8ENF-AT, 1595 Wynkoop Street, Denver, Colorado 80202-1129.
    (1) The owner/operator of each unit shall submit quarterly excess 
emissions reports for NOX BART units no later than the 30th 
day following the end of each calendar quarter. Excess emissions means 
emissions that exceed the emissions limits specified in paragraph (c) 
of this section. The reports shall include the magnitude, date(s), and 
duration of each period of excess emissions, specific identification of 
each period of excess emissions that occurs during startups, shutdowns, 
and malfunctions of the unit, the nature and cause of any malfunction 
(if known), and the corrective action taken or preventative measures 
adopted.
    (2) The owner/operator of each unit shall submit quarterly CEMS 
performance reports, to include dates and duration of each period 
during which the CEMS was inoperative (except for zero and span 
adjustments and calibration checks), reason(s) why the CEMS was 
inoperative and steps taken to prevent recurrence, and any CEMS repairs 
or adjustments. The owner/operator of each unit shall also submit 
results of any CEMS performance tests required by 40 CFR part 75.
    (3) When no excess emissions have occurred or the CEMS has not been 
inoperative, repaired, or adjusted during the reporting period, such 
information shall be stated in the quarterly reports required by 
paragraphs (g)(1) and (2) of this section.
    (h) Notifications. (1) The owner/operator shall promptly submit 
notification of commencement of construction of any equipment which is 
being constructed to comply with the NOX emission limits in 
paragraph (c) of this section.
    (2) The owner/operator shall promptly submit semi-annual progress 
reports on construction of any such equipment.
    (3) The owner/operator shall promptly submit notification of 
initial startup of any such equipment.
    (i) Equipment operation. At all times, the owner/operator shall 
maintain each unit, including associated air pollution control 
equipment, in a manner consistent with good air pollution control 
practices for minimizing emissions.
    (j) Credible evidence. Nothing in this section shall preclude the 
use, including the exclusive use, of any credible evidence or 
information, relevant to whether a source would have been in compliance 
with requirements of this section if the appropriate performance or 
compliance test procedures or method had been performed.

[FR Doc. 2016-14645 Filed 7-1-16; 8:45 am]
BILLING CODE 6560-50-P