[Federal Register Volume 81, Number 9 (Thursday, January 14, 2016)]
[Proposed Rules]
[Pages 2003-2052]
[FR Doc No: 2015-33108]

Vol. 81

Thursday,

No. 9

January 14, 2016

Part II

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; Proposed Rule

Federal Register / Vol. 81 , No. 9 / Thursday, January 14, 2016 /
Proposed Rules

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R08-OAR-2015-0463; FRL--9939-43-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: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to take
action pursuant to section 110 of the Clean Air Act (CAA or Act) on
State Implementation Plan (SIP) revisions submitted by the State of
Utah on June 4, 2015, and October 20, 2015 to implement the regional
haze program. The State's SIP revisions 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, Bryce Canyon and Zion National Parks. The EPA is issuing two
co-proposals in order to fully evaluate the State's submittals and the
public's input thereon. The EPA would work with the State on a revised
State plan should a partial disapproval and FIP be finalized.

DATES: Comments: Written comments must be received on or before March
14, 2016.
    Public Hearing: A public hearing for this proposal is scheduled to
be held on Tuesday, January 26, 2016, at the Salt Lake City Public
Library, Main Library, from 1 p.m. until 5 p.m., and again from 6 p.m.
until 8 p.m. (local time).

ADDRESSES: The public hearing will be held at the Salt Lake City Public
Library, Main Library, 210 East 400 South, Salt Lake City, Utah 84111.
    Submit your comments, identified by Docket ID No. EPA-R08-OAR-2015-
0463, to the Federal eRulemaking Portal: http://www.regulations.gov.
Follow the online instructions for submitting comments. Once submitted,
comments cannot be edited or removed from Regulations.gov. The EPA may
publish any comment received to its public docket. Do not submit
electronically any information you consider to be Confidential Business
Information (CBI) or other information whose disclosure is restricted
by statute. Multimedia submissions (audio, video, etc.) must be
accompanied by a written comment. The written comment is considered the
official comment and should include discussion of all points you wish
to make. The EPA will generally not consider comments or comment
contents located outside of the primary submission (i.e., on the web,
cloud, or other file sharing system). For additional submission
methods, the full EPA public comment policy, information about CBI or
multimedia submissions, and general guidance on making effective
comments, please visit http://www2.epa.gov/dockets/commenting-epa-dockets.
    Instructions: Direct your comments to Docket ID No. EPA-R08-OAR-
2015-0463. The EPA's policy is that all comments received will be
included in the public docket and may be made available online at
http://www.regulations.gov, including any personal information
provided, unless the comment includes information claimed to be
Confidential Business Information (CBI) or other information whose
disclosure is restricted by statute. Do not submit information that you
consider to be CBI or otherwise protected through www.regulations.gov
or email. The www.regulations.gov Web site is an ``anonymous access''
system, which means EPA will not know your identity or contact
information unless you provide it in the body of your comment. If you
send an email comment directly to EPA, without going through
www.regulations.gov your email address will be automatically captured
and included as part of the comment that is placed in the public docket
and made available on the Internet. If you submit an electronic
comment, EPA recommends that you include your name and other contact
information in the body of your comment and with any disk or CD-ROM you
submit. If EPA cannot read your comment due to technical difficulties
and cannot contact you for clarification, EPA may not be able to
consider your comment. Electronic files should avoid the use of special
characters, any form of encryption, and be free of any defects or
viruses. For additional information about EPA's public docket visit the
EPA Docket Center homepage at http://www.epa.gov/epahome/dockets.htm.
For additional instructions on submitting comments, go to section I,
General Information, of the SUPPLEMENTARY INFORMATION section of this
document.
    Docket: All documents in the docket are listed in the
www.regulations.gov index. Although listed in the index, some
information is not publicly available, e.g., CBI or other information
whose disclosure is restricted by statute. Certain other material, such
as copyrighted material, will be publicly available only in hard copy.
Publicly available docket materials are available either electronically
in 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<EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION:

Public Hearing

    The public hearing will provide interested parties the opportunity
to present data, views, or arguments concerning the proposed action.
The EPA may ask clarifying questions during the oral presentations, but
will not respond to the presentations at that time. Written statements
and supporting information submitted during the comment period will be
considered with the same weight as oral comments and supporting
information presented at the public hearing. The hearing officer may
limit the time available for each commenter to address the proposal to
5 minutes or less if the hearing officer determines it to be
appropriate. The limitation is to ensure that everyone who wants to
make a comment has the opportunity to do so. We will not be providing
equipment for commenters to show overhead slides or make computerized
slide presentations. Any person may provide written or oral

comments and data pertaining to our proposal at the public hearings.
Verbatim transcripts, in English, of the hearings and written
statements will be included in the rulemaking docket.

Table of Contents

I. General Information
II. Overview of Proposed Actions
    A. Brief Description of These Co-Proposals
    1. Summary of Proposal To Approve the SIP
    2. Summary of Proposal To Partially Approve and Partially
Disapprove the SIP and Propose a FIP
III. Background and Requirements for Regional Haze SIPs and Utah
Submittals
    A. Statutory and Regulatory Background
    1. Regional Haze
    2. Requirements of the CAA and EPA's Regional Haze Rule (RHR)
    3. Roles of Agencies in Addressing Regional Haze
    4. Development of the Requirements for 40 CFR 51.309
    5. SIP and FIP Background
    B. Requirements for Regional Haze SIPs Applicable to This
Proposal
    1. The CAA and the Regional Haze Rule
    2. Determination of Baseline, Natural and Current Visibility
Conditions
    3. Best Available Retrofit Technology
    4. Monitoring, Recordkeeping and Reporting
    5. Consultation With States and Federal Land Managers (FLMs)
    C. Requirements for Regional Haze SIPs Submitted Under 40 CFR
51.309
    1. Projection of Visibility Improvement
    2. Stationary Source Reductions
    a. Sulfur Dioxide Emission Reductions
    b. Provisions for Stationary Source Emissions of Nitrogen Oxides
and Particulate Matter
    D. General Requirements for PM10 and NOX
Alternative Programs Under the Regional Haze Rule and the ``Better-
Than-BART Demonstration''
    E. Summary of State Regional Haze Submittals and EPA Actions
    1. 2008 and 2011 Utah RH SIPs
    2. 2012 EPA Action on 2011 and 2008 Utah RH SIPs
    3. 2013 Litigation
    4. 2015 Utah RH SIPs
IV. Utah's Regional Haze SIP
    A. Summary of Elements Under EPA's Previous Actions Upon Which
We Are Relying
    1. Affected Class I Areas
    2. BART-Eligible Sources
    3. Sources Subject-to-BART
    B. Summary of Utah's BART Alternative and PM10 BART
SIP Revision
    1. Utah BART Alternative
    2. PM10 BART Determinations
    3. Monitoring, Recordkeeping and Reporting
    C. Summary of Utah's Demonstration for Alternative Program
    1. A List of All BART-Eligible Sources Within the State
    2. A List of All BART-Eligible Sources and All BART Source
Categories Covered by the Alternative Program
    3. Analysis of BART and Associated Emission Reductions
Achievable
    4. Analysis of Projected Emissions Reductions Achievable Through
the BART Alternative
    5. A Determination That the Alternative Achieves Greater
Reasonable Progress Than Would Be Achieved Through the Installation
and Operation of BART
    a. Annual Emissions Comparison for Visibility-Impairing
Pollutants
    b. Improvement in the Number of Days With Significant Visibility
Impairment
    c. 98th Percentile Impact (dv)
    d. Annual Average Impact (dv)
    e. 90th Percentile Impact (dv)
    f. Timing for the Emissions Reductions
    g. IMPROVE Monitoring Data
    h. Energy and Non-Air Quality Benefits
    i. Cost
    6. Requirement That Emission Reductions Take Place During Period
of First Long-Term Strategy
    7. Demonstration That Emission Reductions From Alternative
Program Will Be Surplus
    D. Summary of Utah's Enforceable Commitment SIP Revision
    E. Consultation With FLMs
V. EPA's Evaluation and Proposed Approval of Utah's Regional Haze
SIP
    A. Basis for Proposed Approval
    B. Utah BART Alternative
    1. Summary of Utah BART Alternative
    2. Demonstration of Greater Reasonable Progress for the
Alternative Program
    a. A List of All BART-Eligible Sources Within the State
    b. A List of All BART-Eligible Sources and All BART Source
Categories Covered by the Alternative Program
    c. Analysis of BART and Associated Emission Reductions
    d. Analysis of Projected Emissions Reductions Achievable Through
the BART Alternative
    e. A Determination That the Alternative Achieves Greater
Reasonable Progress Than Would Be Achieved Through the Installation
and Operation of BART
    f. Evaluation of the Weight of Evidence
    g. Requirement That Emission Reductions Take Place During Period
of First Long-Term Strategy
    h. Demonstration That Emission Reductions From Alternative
Program Will Be Surplus
    C. PM10 BART Determinations
    D. Monitoring, Recordkeeping, and Reporting
    E. Consultation With FLMs
VI. EPA's Evaluation and Proposed Partial Approval and Partial
Disapproval of Utah's Regional Haze SIP
    A. Basis for Proposed Partial Disapproval and Partial Approval
    B. Utah BART Alternative
    1. Summary of Utah BART Alternative
    2. Demonstration of Greater Reasonable Progress for Alternative
Program
    a. A List of All BART-Eligible Sources Within the State
    b. A List of All BART-Eligible Sources and All BART Source
Categories Covered by the Alternative Program
    c. Analysis of BART and Associated Emission Reductions
Achievable
    d. Analysis of Projected Emissions Reductions Achievable Through
the BART Alternative
    e. A Determination That the Alternative Achieves Greater
Reasonable Progress Than Would Be Achieved Through the Installation
and Operation of BART
    f. Evaluation of the Weight of Evidence
    g. Evaluation That Emission Reductions Take Place During Period
of First Long-Term Strategy
    h. Demonstration That Emission Reductions From Alternative
Program Will Be Surplus
    C. Monitoring, Recordkeeping and Reporting for Utah's BART
Alternative
    D. Proposed Federal Implementation Plan
    1. BART Evaluations
    a. Costs of Compliance
    b. Visibility Impact Modeling
    2. Hunter Power Plant
    a. Hunter Unit 1
    b. Hunter Unit 2
    3. Huntington Power Plant
    a. Huntington Unit 1
    b. Huntington Unit 2
    4. Federal Monitoring, Recordkeeping, and Reporting
    E. PM10 BART Determinations
    F. Consultation With FLMs
VII. EPA's Proposed Actions
    A. Proposed Approval
    B. Proposed Partial Disapproval/Approval and Federal
Implementation Plan
VIII. 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

I. General Information

What should I consider as I prepare my comments for EPA?

    1. Submitting Confidential Business Information (CBI). Do not
submit CBI to EPA through http://www.regulations.gov or email. Clearly
mark the part or all of the information that you claim to be CBI. For
CBI information on a disk or CD-ROM that you mail to EPA, mark the
outside of the disk or CD-ROM as CBI and then identify electronically
within the disk or CD ROM the specific

information that is claimed as CBI. In addition to one complete version
of the comment that includes information claimed as CBI, a copy of the
comment that does not contain the information claimed as CBI must be
submitted for inclusion in the public docket. Information so marked
will not be disclosed except in accordance with procedures set forth in
40 CFR part 2.
    2. Tips for preparing your comments. When submitting comments,
remember to:
     Identify the rulemaking by docket number and other
identifying information (subject heading, Federal Register, date, and
page number);
     Follow directions and organize your comments;
     Explain why you agree or disagree;
     Suggest alternatives and substitute language for your
requested changes;
     Describe any assumptions and provide any technical
information and/or data that you used;
     If you estimate potential costs or burdens, explain how
you arrived at your estimate in sufficient detail to allow for it to be
reproduced;
     Provide specific examples to illustrate your concerns, and
suggest alternatives;
     Explain your views as clearly as possible, avoiding the
use of profanity or personal threats; and
     Make sure to submit your comments by the comment period
deadline identified.

II. Overview of Proposed Actions

    The State of Utah submitted SIP revisions on June 4, 2015, and
October 20, 2015, to fulfill the CAA requirement to meet the
requirements for the Best Available Retrofit Technology (BART) in the
Regional Haze Rule (RHR) for the pollutants NOX and
PM10. As described more fully in Section III, the purpose of
the RHR is to remedy and prevent impairment of visibility in Class I
areas resulting from anthropogenic air pollution. Instead of
establishing BART controls for NOX, Utah's SIP revisions
contain an alternative to BART. The revisions also include BART
controls for PM10. The idea of a BART alternative, which can
take into account (and even encourage) plans that take into account
state specific situations is a reasonable one, and one EPA supports
where consistent with the CAA and RHR.
    The State's SIP contains a NOX BART Alternative and
metrics to evaluate the BART Alternative. In light of the variety of
metrics Utah used, this is a complicated analysis and EPA considered
the State's BART Alternative in the context of other previous decisions
we and the states have made. EPA carefully analyzed the SIP revisions
and the supporting information submitted by the State. We also
conducted additional analyses, which are included with this proposal.
Based on a careful consideration of all of this information, EPA is
proposing and soliciting comments on two different actions: A proposal
to approve the State SIP in its entirety,\1\ and a proposal to
partially approve and partially disapprove the State SIP and propose a
FIP.\2\ EPA takes seriously its decision to co-propose these two
actions (disapprove part of the State's plan, alongside proposing to
approve it), as it is preferable that the regional haze program be
implemented through state plans. As part of its oversight
responsibilities, EPA must be able to find that the state plan is
consistent with the requirements of the Act. In this instance, we
developed analyses and rationale supporting both a proposed approval
and a proposed partial approval and partial disapproval, and we solicit
input on each proposal. EPA intends to finalize only one proposal,
although the details of our final action may differ somewhat from what
is presented here based on any comments and additional information we
receive.
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    \1\ Our proposed approval for one element, reporting for PM BART
limits, is a conditional approval based on a commitment from Utah to
provide a SIP revision to address this element. See section V.D of
this document for a more detailed explanation.
    \2\ In March 2015, conservation groups sued EPA in the U.S.
District Court for the District of Colorado alleging that EPA failed
to promulgate a regional haze FIP for Utah within the two-year
period allowed by CAA section 110(c). See Wildearth Guardians v.
McCarthy, Case No. 1:15-cv-oo630-MSK-KLM, at *1-2 (D. Colo. Mar. 27,
2015). EPA entered into a consent decree resolving this dispute
requiring EPA to sign notices of proposed and final rulemaking for
the regional haze requirements for Utah by December 16, 2015 and
June 1, 2016, respectively. The signing of this proposed rule
partially fulfills EPA's obligations under the consent decree. See
id. (Doc. 60, Motion to Enter Consent Decree filed on December 8,
2015).
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    Deciding whether to approve the State SIP entails an evaluation of
Utah's SIP revision with respect to three elements in the RHR: (1)
``[a] demonstration that the emissions trading program or other
alternative measure will achieve greater reasonable progress than would
have resulted from the installation and operation of BART at all
sources subject to BART in the State and covered by the alternative
program''; \3\ (2) ``[a] requirement that all necessary emission
reductions take place during the period of the first long-term strategy
for regional haze''; \4\ and (3) ``[a] demonstration that the emissions
reductions resulting from the alternative measure will be surplus to
those reductions resulting from measures adopted to meet requirements
of the CAA as of the baseline date of the SIP.'' \5\
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    \3\ 40 CFR 51.308(e)(2)(i).
    \4\ 40 CFR 51.308(e)(2)(iii).
    \5\ 40 CFR 51.308(e)(2)(iv).
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    For the first element, the determination that the alternative
measure will achieve greater reasonable progress than BART, the State
must provide the following: (1) A list of all BART-eligible sources
within the State; (2) a list of all BART-eligible sources and all BART
source categories covered by the alternative program; (3) an analysis
of BART and associated emission reductions; (4) an analysis of the
projected emission reductions achievable through the BART alternative;
and (5) a determination that the alternative achieves greater
reasonable progress than would be achievable through the installation
and operation of BART. A State has several options for making the
greater reasonable progress determination; \6\ in this instance, the
State elected to use two separate approaches.
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    \6\ 40 CFR 51.308(e)(2)(i)(E); 40 CFR 51.308(e)(3).
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    EPA's evaluation of the BART Alternative therefore entails
consideration of both of the State's analyses. As 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.'' \7\ As presented in section V, several
of the metrics in the State's analyses appear to support a
determination that a BART Alternative presented by the State achieves
greater reasonable progress than BART. However, several other metrics
in the State's analyses do not appear to support a conclusion that the
BART Alternative achieves greater reasonable progress. The complexity
of our evaluation leads us to propose and solicit comment on two
conclusions and courses of action: (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 request
comment on all aspects of each proposal.
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    \7\ 71 FR 60612, 60621 (Oct. 13, 2006).
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    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. Therefore, in addition to
seeking comments on the co-proposals, we are

also asking if interested parties have additional information or
analysis on the co-proposals, for example, analysis related to the
modeled visibility benefits of the BART Alternative compared to BART.
In light of any such information, we are asking whether interested
parties think the Agency should consider BART Alternatives or BART
control technology options that are related to what we propose and that
could be finalized as our FIP (if we disapprove the Utah SIP submittal
in our final action). The Agency is also asking if interested parties
have additional information or comments on the proposed timing of
compliance.
    The Agency will take the comments and testimony received, as well
as any further SIP revisions received from the State prior to our final
action, into consideration in our final promulgation. As noted above,
additional information and comments may lead the Agency to adopt final
SIP and/or FIP regulations that differ somewhat from the co-proposals
presented here regarding the BART Alternative, BART control technology
option or emission limits, or impact other proposed regulatory
provisions. EPA's final action will fully consider these complex issues
and the comments received, which will result in the selection of a
final action that meets the CAA and regulatory requirements requiring
development and implementation of plans to ensure reasonable progress
toward improving visibility in mandatory Class I areas by reducing
emissions that cause or contribute to regional haze.

A. Brief Description of These Co-Proposals

1. Summary of Proposal To Approve the SIP
    As explained more fully later, we are proposing to approve 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 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 are proposing 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 Proposal to Partially Approve and Partially Disapprove
the SIP and Propose a FIP
    We are proposing to approve these elements of the State's SIP
submittals:
     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.
    We are proposing to disapprove these aspects of the State's June 4,
2015 SIP:
     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 are proposing to disapprove the State's October 20, 2015 SIP
submittal.
    We are proposing promulgation of a FIP to address the deficiencies
in the Utah regional haze SIPs that are identified in this notice. The
proposed FIP includes 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.
    If we partially disapprove the SIP, and promulgate a FIP, the State
may submit a SIP revision to supersede the FIP. 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. If we issue a final FIP, we encourage the State to submit a
SIP revision to replace the FIP.

III. Background and Requirements for Regional Haze SIPs and Utah
Submittals

A. Statutory and Regulatory Background

1. Regional Haze
    Regional haze is visibility impairment that is produced by numerous
sources that are located across a broad geographic area and emit fine
particles (PM2.5) (e.g., sulfates, nitrates, organic carbon
(OC), elemental carbon (EC), and soil dust), and their precursors
(e.g., SO2, NOX, and in some cases, ammonia
(NH3) and volatile organic compounds (VOC)). Coarse PM also
impairs visibility. Fine particle precursors react in the atmosphere to
form PM2.5, which impairs visibility by scattering and
absorbing light. Visibility impairment reduces the clarity, color, and
visible distance that one can see, PM2.5 can also cause
serious health effects and mortality in humans and contributes to
environmental effects such as acid deposition and eutrophication.
Coarse PM also can cause adverse health effects.
    Data from the existing visibility monitoring network, the
``Interagency Monitoring of Protected Visual Environments'' (IMPROVE)
monitoring network, show that at the time the regional haze rule was
finalized in 1999, visibility impairment caused by air pollution
occurred virtually all the time at most national parks and wilderness
areas. The average visual range \8\ in many Class I areas (i.e.,
national parks, wilderness areas, and international parks meeting
certain size criteria) in the western U.S. was 62-93 miles, but in some
Class I areas, these visual ranges may have been impacted by natural
wildfire and dust episodes.\9\ In most of the eastern Class I areas of
the U.S., the average visual range was less than 19 miles, ``or about
one-fifth of the visual range that would exist under estimated natural
conditions.'' \10\
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    \8\ Visual range is the greatest distance, in kilometers or
miles, at which a dark object can be viewed against the sky.
    \9\ 64 FR 35715, 35716 (July 1, 1999).
    \10\ Id.
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2. Requirements of the CAA and EPA's Regional Haze Rule (RHR)
    In section 169A of the 1977 Amendments to the CAA, Congress created
a program for protecting visibility in the nation's national parks and
wilderness areas. This section of the CAA establishes ``as a national
goal the prevention of any future, and the remedying of any existing,
impairment of visibility in mandatory class I Federal areas which
impairment results from manmade air pollution.'' \11\ On

December 2, 1980, EPA promulgated regulations to address visibility
impairment in Class I areas that are ``reasonably attributable'' to a
single source or small group of sources, i.e., reasonably attributable
visibility impairment.\12\ These regulations represented the first
phase in addressing visibility impairment. EPA deferred action on
regional haze that emanates from a variety of sources until monitoring,
modeling and scientific knowledge about the relationships between
pollutants and visibility impairment were improved.
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    \11\ 42 U.S.C. 7491(a). Areas designated as mandatory Class I
Federal areas consist of national parks exceeding 6000 acres,
wilderness areas and national memorial parks exceeding 5000 acres,
and all international parks that were in existence on August 7,
1977. 42 U.S.C. 7472(a). In accordance with section 169A of the CAA,
EPA, in consultation with the Department of Interior, promulgated a
list of 156 areas where visibility is identified as an important
value. 44 FR 69122 (Nov. 30, 1979). The extent of a mandatory Class
I area includes subsequent changes in boundaries, such as park
expansions. 42 U.S.C. 7472(a). Although states and tribes may
designate as Class I additional areas which they consider to have
visibility as an important value, the requirements of the visibility
program set forth in section 169A of the CAA apply only to
``mandatory Class I Federal areas.'' Each mandatory Class I Federal
area is the responsibility of a ``Federal Land Manager.'' 42 U.S.C.
7602(i). When we use the term ``Class I area'' in this section, we
mean a ``mandatory Class I Federal area.''
    \12\ 45 FR 80084, 80084 (Dec. 2, 1980).
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    Congress added section 169B to the CAA in 1990 to address regional
haze issues. EPA promulgated a rule to address regional haze on July 1,
1999.\13\ The RHR revised the existing visibility regulations to
integrate into the regulation provisions addressing regional haze
impairment and established a comprehensive visibility protection
program for Class I areas. The requirements for regional haze, found at
40 CFR 51.308 and 51.309, are included in EPA's visibility protection
regulations at 40 CFR 51.300 through 309. Some of the main elements of
the regional haze requirements are summarized later in section III.C of
this preamble. The requirement to submit a regional haze SIP applies to
all 50 states, the District of Columbia, and the Virgin Islands. 40 CFR
51.308(b) requires states to submit the first implementation plan
addressing regional haze visibility impairment no later than December
17, 2007.\14\
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    \13\ 64 FR 35714, 35714 (July 1, 1999) (codified at 40 CFR part
51, subpart P).
    \14\ EPA's RHR requires subsequent updates to the regional haze
SIPs. 40 CFR 51.308(g) through (i).
---------------------------------------------------------------------------

    Once EPA has found that a state has failed to make a required
submission, EPA is required to promulgate a FIP within two years unless
the state submits a SIP and the Agency approves it within the two-year
period.\15\
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    \15\ 42 U.S.C. 7410(c)(1).
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3. Roles of Agencies in Addressing Regional Haze
    Successful implementation of the regional haze program requires
long-term regional coordination among states, tribal governments, and
various federal agencies. As noted previously, pollution affecting the
air quality in Class I areas can be transported over long distances,
even hundreds of kilometers. Therefore, to effectively address the
problem of visibility impairment in Class I areas, states need to
develop strategies in coordination with one another, taking into
account the effect of emissions from one jurisdiction on the air
quality in another.
    Because the pollutants that lead to regional haze can originate
from sources located across broad geographic areas, EPA has encouraged
the states and tribes across the United States to address visibility
impairment from a regional perspective. Five regional planning
organizations (RPOs) were created to address regional haze and related
issues. The RPOs first evaluated technical information to better
understand how their states and tribes impact Class I areas across the
country, and then pursued the development of regional strategies to
reduce emissions of pollutants that lead to regional haze.
    The Western Regional Air Partnership (WRAP) RPO is a collaborative
effort of state governments, tribal governments, and various federal
agencies established to initiate and coordinate activities associated
with the management of regional haze, visibility and other air quality
issues in the western United States. WRAP member state governments
include: Alaska, Arizona, California, Colorado, Idaho, Montana, New
Mexico, North Dakota, Oregon, South Dakota, Utah, Washington, and
Wyoming. Tribal members include Campo Band of Kumeyaay Indians,
Confederated Salish and Kootenai Tribes, Cortina Indian Rancheria, Hopi
Tribe, Hualapai Nation of the Grand Canyon, Native Village of Shungnak,
Nez Perce Tribe, Northern Cheyenne Tribe, Pueblo of Acoma, Pueblo of
San Felipe, and Shoshone-Bannock Tribes of Fort Hall.
4. Development of the Requirements for 40 CFR 51.309
    EPA's RHR provides two paths to address regional haze. One is 40
CFR 51.308, requiring states to perform individual point source BART
determinations and evaluate the need for other control strategies.
These strategies must be shown to make ``reasonable progress'' in
improving visibility in Class I areas inside the state and in
neighboring jurisdictions. The other method for addressing regional
haze is through 40 CFR 51.309, and is an option for nine states termed
the ``Transport Region States,'' which include: Arizona, California,
Colorado, Idaho, Nevada, New Mexico, Oregon, Utah, and Wyoming. By
meeting the requirements under 40 CFR 51.309, states can be deemed to
be making reasonable progress toward the national goal of achieving
natural visibility conditions for the 16 Class I areas on the Colorado
Plateau.
    Section 309 requires participating states to adopt regional haze
strategies that are based on recommendations from the Grand Canyon
Visibility Transport Commission (GCVTC) for protecting the 16 Class I
areas on the Colorado Plateau.\16\ The EPA established the GCVTC on
November 13, 1991. The purpose of the GCVTC was to assess information
about the adverse impacts on visibility in and around the 16 Class I
areas on the Colorado Plateau and to provide policy recommendations to
EPA to address such impacts. Section 169B of the CAA called for the
GCVTC to evaluate visibility research, as well as other available
information, pertaining to adverse impacts on visibility from potential
or projected growth in emissions from sources located in the region.
The GCVTC determined that all Transport Region States could potentially
impact the Class I areas on the Colorado Plateau. The GCVTC submitted a
report to EPA in 1996 with its policy recommendations for protecting
visibility for the Class I areas on the Colorado Plateau. Provisions of
the 1996 GCVTC report include: Strategies for addressing smoke
emissions from wildland fires and agricultural burning; provisions to
prevent pollution by encouraging renewable energy development; and
provisions to manage clean air corridors (CACs), mobile sources, and
wind-blown dust, among other things. The EPA codified these
recommendations as an option available to states as part of the 1999
RHR.\17\
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    \16\ The Colorado Plateau is a high, semi-arid tableland in
southeast Utah, northern Arizona, northwest New Mexico, and western
Colorado. The 16 mandatory Class I areas are as follows: Grand
Canyon National Park, Mount Baldy Wilderness, Petrified Forest
National Park, Sycamore Canyon Wilderness, Black Canyon of the
Gunnison National Park Wilderness, Flat Tops Wilderness, Maroon
Bells Wilderness, Mesa Verde National Park, Weminuche Wilderness,
West Elk Wilderness, San Pedro Parks Wilderness, Arches National
Park, Bryce Canyon National Park, Canyonlands National Park, Capital
Reef National Park, and Zion National Park.
    \17\ 64 FR 35714, 35749 (July 1, 1999).
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    EPA determined that the GCVTC strategies would provide for
reasonable progress in mitigating regional haze if supplemented by an
annex containing quantitative emission reduction milestones and
provisions for a trading program or other alternative measure.\18\
Thus, the 1999 RHR required that western states submit an annex to the
GCVTC report with quantitative milestones and detailed guidelines for
an alternative program in order to establish the GCVTC recommendations
as an alternative approach to fulfilling the section 308 requirements
for compliance with the RHR. In September

2000, the WRAP, which is the successor organization to the GCVTC,
submitted an annex to EPA. The annex contained SO2 emissions
reduction milestones and detailed provisions of a backstop trading
program to be implemented automatically if voluntary measures failed to
achieve the SO2 milestones. EPA codified the annex on June
5, 2003 at 40 CFR 51.309(h).\19\
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    \18\ 64 FR 35714, 35749, 35756.
    \19\ 68 FR 33764, 33767 (June 5, 2003).
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    Five western states, including Utah, submitted implementation plans
under section 309 in 2003. EPA was challenged by the Center for Energy
and Economic Development (CEED) on the validity of the annex
provisions. In CEED v. EPA, the DC Circuit Court of Appeals vacated EPA
approval of the WRAP annex.\20\ In response to the court's decision,
EPA vacated the annex requirements adopted under 40 CFR 51.309(h), but
left in place the stationary source requirements in 40 CFR
51.309(d)(4).\21\ The requirements under 40 CFR 51.309(d)(4) contain
general requirements pertaining to stationary sources and market
trading, and allow states to adopt alternatives to the point source
application of BART.
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    \20\ Ctr. for Energy & Econ. Dev. v. EPA, 398 F.3d 653, 654
(D.C. Cir. 2005).
    \21\ 71 FR 60612, 60612 (Oct. 13, 2006).
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5. SIP and FIP Background
    The CAA requires each state to develop plans to meet various air
quality requirements, including protection of visibility.\22\ The plans
developed by a state are referred to as SIPs. A state must submit its
SIPs and SIP revisions to EPA for approval. Once approved, a SIP is
enforceable by EPA and citizens under the CAA, which is also known as
being federally enforceable. If a state fails to make a required SIP
submittal or if we find that a state's required submittal is incomplete
or not approvable, then we must promulgate a FIP to fill this
regulatory gap.\23\ As discussed elsewhere in this preamble, one of the
proposals would disapprove aspects of Utah's regional haze SIP and
promulgate a FIP to address the deficiencies in Utah's regional haze
SIP, should we disapprove the SIP in our final action.
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    \22\ 42 U.S.C. 7410(a), 7491, and 7492(a), 169A, and 169B.
    \23\ 42 U.S.C. 7410(c)(1).
---------------------------------------------------------------------------

B. Requirements for Regional Haze SIPs Applicable to This Proposal

1. The CAA and the Regional Haze Rule
    Regional haze SIPs must assure reasonable progress towards the
national goal of achieving natural visibility conditions in Class I
areas. Section 169A of the CAA and EPA's implementing regulations
require states to establish long-term strategies for making reasonable
progress toward meeting this goal. Implementation plans must also give
specific attention to certain stationary sources that were in existence
on August 7, 1977, but were not in operation before August 7, 1962, and
require these sources, where appropriate, to install BART controls for
the purpose of eliminating or reducing visibility impairment. The
specific regional haze SIP requirements are discussed in further detail
later on.
2. Determination of Baseline, Natural, and Current Visibility
Conditions
    The RHR establishes the deciview (dv) as the principal metric or
unit for expressing visibility.\24\ This visibility metric expresses
uniform changes in the degree of haze in terms of common increments
across the entire range of visibility conditions, from pristine to
extremely hazy conditions. Visibility expressed in deciviews is
determined by using air quality measurements to estimate light
extinction and then transforming the value of light extinction using a
logarithmic function. The dv is a more useful measure for tracking
progress in improving visibility than light extinction itself because
each dv change is an equal incremental change in visibility perceived
by the human eye. Most people can detect a change in visibility at one
dv.\25\
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    \24\ See 70 FR 39104, 39118 (July 6, 2005).
    \25\ The preamble to the RHR provides additional details about
the deciview (dv) scale. 64 FR 35714, 35725 (July 1, 1999).
---------------------------------------------------------------------------

    The dv is used in expressing reasonable progress goals (RPGs, which
are interim visibility goals towards meeting the national visibility
goal), in defining baseline, current, and natural conditions; and in
tracking changes in visibility. The regional haze SIPs must contain
measures that ensure ``reasonable progress'' toward the national goal
of preventing and remedying visibility impairment in Class I areas
caused by anthropogenic emissions that cause or contribute to regional
haze. The national goal is a return to natural conditions, i.e. to
reach a state at which anthropogenic sources of air pollution no longer
impair visibility in Class I areas.
    To track changes in visibility over time at each of the 156 Class I
areas covered by the visibility program,\26\ and as part of the process
for determining reasonable progress, states must calculate the degree
of existing visibility impairment at each Class I area at the time of
each regional haze SIP submittal and review progress every five years,
midway through each 10-year implementation period. To do this, the RHR
requires states to determine the degree of impairment (in deciviews)
for the average 20 percent least impaired (``best'') and 20 percent
most impaired (``worst'') visibility days over a specified time period
at each of their Class I areas. In addition, states must also develop
an estimate of natural visibility conditions for the purpose of
comparing progress toward the national goal. Natural visibility is
determined by estimating the natural concentrations of pollutants that
cause visibility impairment and then calculating total light extinction
based on those estimates. In 2003, EPA provided guidance to states
regarding how to calculate baseline, natural and current visibility
conditions.\27\ Subsequently, the Natural Haze Levels II Committee
developed updated estimates of natural haze for average natural
conditions and for the averages of the best 20% and worst 20% natural
condition days \28\ that have been used by states and EPA in visibility
assessments.
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    \26\ 40 CFR 81.401-437.
    \27\ Guidance for Estimating Natural Visibility Conditions Under
the Regional Haze Rule, EPA-454/B-03-005, available at http://www3.epa.gov/ttn/caaa/t1/memoranda/rh_envcurhr_gd.pdf, (hereinafter
referred to as ``our 2003 Natural Visibility Guidance'') (Sept.
2003) (documents identified with Internet addresses are available in
the docket) ; Guidance for Tracking Progress Under the Regional Haze
Rule, EPA-454/B-03-004, available at http://www3.epa.gov/ttnamti1/files/ambient/visible/tracking.pdf (hereinafter referred to as our
``2003 Tracking Progress Guidance'') (Sept. 2003).
    \28\ ``Natural Haze Levels II: Application of the New IMPROVE
Algorithm to Natural Species Concentrations Estimates'', Final
Report by the Natural Haze Levels II Committee to the RPO
Monitoring/Data Analysis Workgroup, power point presentation
included in the docket.
---------------------------------------------------------------------------

    For the first regional haze SIPs that were due by December 17,
2007, ``baseline visibility conditions'' were the starting points for
assessing ``current'' visibility impairment. Baseline visibility
conditions represent the five-year averages of the degree of visibility
impairment for the 20 percent least impaired days and the 20 percent
most impaired days for each calendar year from 2000 to 2004. Using
monitoring data for 2000 through 2004, states are required to calculate
the average degree of visibility impairment for each Class I area,
based on the average of annual values over the five-year period. The
comparison of initial baseline visibility conditions to natural
visibility conditions indicates the amount of improvement necessary to
attain natural visibility, while the future comparison of baseline
conditions to the then current conditions will indicate the

amount of progress made. In general, the 2000-2004 baseline period is
considered the time from which improvement in visibility is measured.
3. Best Available Retrofit Technology
    Section 169A of the CAA directs states to evaluate the use of
retrofit controls at certain larger, often uncontrolled, older
stationary sources in order to address visibility impacts from these
sources. Specifically, section 169A(b)(2)(A) of the CAA requires states
to revise their SIPs to contain such measures as may be necessary to
make reasonable progress towards the natural visibility goal, including
a requirement that certain categories of existing major stationary
sources \29\ built between 1962 and 1977 procure, install, and operate
the ``Best Available Retrofit Technology'' as determined by the state.
Under the RHR, states are directed to conduct BART determinations for
such ``BART-eligible'' sources that may be anticipated to cause or
contribute to any visibility impairment in a Class I area. Rather than
requiring source-specific BART controls, states also have the
flexibility to adopt an emissions trading program or other alternative
program as long as the alternative provides greater reasonable progress
towards improving visibility than BART.
---------------------------------------------------------------------------

    \29\ See 42 U.S.C. 7491(g)(7) (listing the set of ``major
stationary sources'' potentially subject-to-BART).
---------------------------------------------------------------------------

    On July 6, 2005, EPA published the ``Guidelines for BART
Determinations Under the Regional Haze Rule'' at appendix Y to 40 CFR
part 51 (hereinafter referred to as the ``BART Guidelines'') to assist
states in determining which of their sources should be subject to the
BART requirements and in determining appropriate emission limits for
each applicable source.\30\ In making a BART determination for a fossil
fuel-fired electric generating plant with a total generating capacity
in excess of 750 megawatts (MW), a state must use the approach set
forth in the BART Guidelines. A state is encouraged, but not required,
to follow the BART Guidelines in making BART determinations for other
types of sources. Regardless of source size or type, a state must meet
the requirements of the CAA and our regulations for selection of BART,
and the state's BART analysis and determination must be reasonable in
light of the overarching purpose of the regional haze program.
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    \30\ 70 FR 39104, 39104 (July 6, 2005).
---------------------------------------------------------------------------

    The process of establishing BART emission limitations can be
logically broken down into three steps: First, states identify those
sources that meet the definition of ``BART-eligible source'' set forth
in 40 CFR 51.301; \31\ second, states determine which of such sources
``emits any air pollutant which may reasonably be anticipated to cause
or contribute to any impairment of visibility in any such area'' \32\
(a source that fits this description is ``subject-to-BART''); and
third, for each source subject-to-BART, states then identify the best
available type and level of control for reducing emissions.
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    \31\ BART-eligible sources are those sources that have the
potential to emit 250 tons or more of a visibility-impairing air
pollutant, were not in operation prior to August 7, 1962, but were
in existence on August 7, 1977, and whose operations fall within one
or more of 26 specifically listed source categories. 40 CFR 51.301.
    \32\ 42 U.S.C. 7491(b)(2)(A).
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    States must address all visibility-impairing pollutants emitted by
a source in the BART determination process. The most significant
visibility impairing pollutants are SO2, NOX, and
PM. EPA has stated that states should use their best judgment in
determining whether VOC or NH3 compounds impair visibility
in Class I areas.
    Under the BART Guidelines, states may select an exemption threshold
value for their BART modeling, below which a BART-eligible source would
not be expected to cause or contribute to visibility impairment in any
Class I area. The state must document this exemption threshold value in
the SIP and must state the basis for its selection of that value. Any
source with emissions that model above the threshold value would be
subject to a BART determination review. The BART Guidelines acknowledge
varying circumstances affecting different Class I areas. States should
consider the number of emission sources affecting the Class I areas at
issue and the magnitude of the individual sources' impacts. Any
exemption threshold set by the state should not be higher than 0.5
dv.\33\
---------------------------------------------------------------------------

    \33\ 40 CFR part 51, appendix Y, Sec.  III.A.1.
---------------------------------------------------------------------------

    In their SIPs, states must identify the sources that are subject-
to-BART and document their BART control determination analyses for such
sources. In making their BART determinations, section 169A(g)(2) of the
CAA requires that states consider the following factors when evaluating
potential control technologies: (1) The costs of compliance; (2) the
energy and non-air quality environmental impacts of compliance; (3) any
existing pollution control technology in use at the source; (4) the
remaining useful life of the source; and (5) the degree of improvement
in visibility which may reasonably be anticipated to result from the
use of such technology.
    A regional haze SIP must include source-specific BART emission
limits and compliance schedules for each source subject-to-BART. Once a
state has made its BART determination, the BART controls must be
installed and in operation as expeditiously as practicable, but no
later than five years after the date of EPA approval of the regional
haze SIP.\34\ As noted previously, the RHR allows states to implement
an alternative program in lieu of BART so long as the alternative
program can be demonstrated to achieve greater reasonable progress
toward the national visibility goal than would BART.
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    \34\ 42 U.S.C. 7491(g)(4); 40 CFR 51.308(e)(1)(iv).
---------------------------------------------------------------------------

4. Monitoring, Recordkeeping and Reporting
    The CAA requires that SIPs, including the regional haze SIP,
contain elements sufficient to ensure emission limits are practically
enforceable. CAA section 110(a)(2) requires in part that the
monitoring, recordkeeping and reporting (MRR) provisions of states'
SIPs must include enforceable emission limitations, control measures,
and compliance timeframes. It also requires SIPs to provide for
enforcement of these measures, installation, maintenance, and
replacement of equipment, emissions monitoring, periodic emissions
reports and availability of emissions reports for public inspection.
    Accordingly, 40 CFR part 51, subpart K, Source Surveillance,
requires the SIP to provide for monitoring the status of compliance
with the regulations in it, including ``[p]eriodic testing and
inspection of stationary sources,'' \35\ and ``legally enforceable
procedures'' for recordkeeping and reporting.\36\ Furthermore, 40 CFR
part 51, appendix V, Criteria for Determining the Completeness of Plan
Submissions, states in section 2.2 that complete SIPs contain: ``(g)
Evidence that the plan contains emission limitations, work practice
standards and recordkeeping/reporting requirements, where necessary, to
ensure emission levels''; and ``(h) Compliance/enforcement strategies,
including how compliance will be determined in practice.''
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    \35\ 40 CFR 51.212(a).
    \36\ 40 CFR 51.211.
---------------------------------------------------------------------------

5. Consultation With States and Federal Land Managers (FLMs)
    The RHR requires that states consult with FLMs before adopting and
submitting their SIPs.\37\ States must

provide FLMs an opportunity for consultation, in person and at least 60
days prior to holding any public hearing on the SIP. This consultation
must include the opportunity for the FLMs to discuss their assessments
of impairment of visibility in any Class I area and to offer
recommendations on the development of the RPGs and on the development
and implementation of strategies to address visibility impairment.
Further, a state must include in its SIP a description of how it
addressed any comments provided by the FLMs. Finally, a SIP must
provide procedures for continuing consultation between the state and
FLMs regarding the state's visibility protection program, including
development and review of SIP revisions, five-year progress reports,
and the implementation of other programs having the potential to
contribute to impairment of visibility in Class I areas.
---------------------------------------------------------------------------

    \37\ 40 CFR 51.308(i).
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C. Requirements for Regional Haze SIPs Submitted Under 40 CFR 51.309

    The following is a summary and basic explanation of the regulations
covered under section 51.309 of the RHR that are addressed in this
notice.\38\
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    \38\ Utah addressed some of the requirements of 40 CFR 51.309 in
2008 and 2011 SIP submissions. EPA took final action on some of the
provisions in the 2008 and 2011 SIP submissions in earlier notices.
See 40 CFR 51.309 for a complete listing of the regulations under
which the 2008 and 2011 SIP submissions were evaluated.
---------------------------------------------------------------------------

1. Projection of Visibility Improvement
    For each of the 16 Class I areas located on the Colorado Plateau,
the SIP must include a projection of the improvement in visibility
expressed in deciviews.\39\ An explanation of the deciview metric is
provided in section III.C.2. States need to show the projected
visibility improvement for the best and worst 20 percent days through
the year 2018, based on the application of all section 309 control
strategies.
---------------------------------------------------------------------------

    \39\ 40 CFR 51.309(d)(2).
---------------------------------------------------------------------------

2. Stationary Source Reductions
a. Sulfur Dioxide Emission Reductions
    Rather than requiring source-specific BART controls as explained
previously in section III.C.4, states have the flexibility to adopt an
emissions trading program or other alternative program as long as the
alternative provides greater reasonable progress than would be achieved
by the application of BART pursuant to 40 CFR 51.308(e)(2). Under 40
CFR 51.309, states can satisfy the SO2 BART requirements by
adopting SO2 emission milestones and a backstop trading
program.\40\ Under this approach, states must establish declining
SO2 emission milestones for each year of the program through
2018. The milestones must be consistent with the GCVTC's goal of 50 to
70 percent reduction in SO2 emissions by 2040.
---------------------------------------------------------------------------

    \40\ 40 CFR 51.309(d)(4).
---------------------------------------------------------------------------

    Pursuant to 40 CFR 51.309(d)(4)(ii) through (iv), states must
include requirements in the SIP that allow states to determine whether
the milestone has been exceeded. These requirements include
documentation of the baseline emission calculation, monitoring,
recordkeeping, and reporting of SO2 emissions, and
provisions for conducting an annual evaluation to determine whether the
milestone has been exceeded. SIPs must also contain requirements for
implementing the backstop trading program in the event that the
milestone is exceeded and the program is triggered.\41\
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    \41\ 40 CFR 51.309(d)(4)(v).
---------------------------------------------------------------------------

    The WRAP, in conjunction with EPA, developed a model for a backstop
trading program. In order to ensure consistency between states, states
opting to participate in the 309 program needed to adopt rules that are
substantively equivalent to the model rules for the backstop trading
program to meet the requirements of 40 CFR 51.309(d)(4). The trading
program must also be implemented no later than 15 months after the end
of the first year that the milestone is exceeded, require that sources
hold allowances to cover their emissions, and provide a framework,
including financial penalties, to ensure that the 2018 milestone is
met.
b. Provisions for Stationary Source Emissions of Nitrogen Oxides and
Particulate Matter
    Pursuant to 40 CFR 51.309(d)(4)(vii), a section 309 SIP must
contain any necessary long term strategies and BART requirements for PM
and NOX. These requirements, including the process for
conducting BART determinations either based on the consideration of the
five statutory factors or based on an alternative program, are
explained previously in section III.C.4 and in section III.E,
respectively.

D. General Requirements for PM10 and NOX
Alternative Programs Under the Regional Haze Rule and the ``Better-
Than-BART Demonstration''

    States opting to submit an alternative program must meet
requirements under 40 CFR 51.308(e)(2) and (e)(3). These requirements
for alternative programs relate to the ``better-than-BART'' test and
fundamental elements of any alternative program.
    In order to demonstrate that the alternative program achieves
greater reasonable progress than source-specific BART, a state must
demonstrate that its SIP meets the requirements in 40 CFR
51.308(e)(2)(i) through (v). States submitting section 309 SIPs or
other alternative programs are required to list all BART-eligible
sources and categories covered by the alternative program. States are
then required to determine which BART-eligible sources are ``subject-
to-BART.'' The SIP must provide an analysis of the best system of
continuous emission control technology available and the associated
reductions for each source subject-to-BART covered by the alternative
program, or what is termed a ``BART benchmark.'' Where the alternative
program has been designed to meet requirements other than BART, states
may use simplifying assumptions in establishing a BART benchmark.
    Pursuant to 40 CFR 51.308(e)(2)(i)(E), the State must also provide
a determination that the alternative program achieves greater
reasonable progress than BART under 40 CFR 51.308(e)(3) or otherwise
based on the clear weight of evidence. 40 CFR 51.308(e)(3), in turn,
provides a specific test for determining whether the alternative
achieves greater reasonable progress than BART. If the distribution of
emissions for the alternative program is not substantially different
than for BART, and the alternative program results in greater emission
reductions, then the alternative program may be deemed to achieve
greater reasonable progress. If the distribution of emissions is
significantly different, the differences in visibility between BART and
the alternative program, must be determined by conducting dispersion
modeling for each impacted Class I area for the best and worst 20
percent of days. The modeling would demonstrate ``greater reasonable
progress'' if both of the two following criteria are met: (1)
Visibility does not decline in any Class I area, and (2) there is
overall improvement in visibility when comparing the average
differences between BART and the alternative program over all of the
affected Class I areas.
    Alternately, pursuant to 40 CFR 51.308(e)(2) States may show that
the BART alternative achieves greater reasonable progress than the BART
benchmark ``based on the clear weight of evidence'' determinations,
which

``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
SIPs submitted by States employing such an approach.'' \42\
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    \42\ 71 FR 60612, 60622 (Oct. 13, 2006).

    Finally, in promulgating the final regional haze program
requirements and responding to concerns regarding ``impermissibly
vague'' language in Sec.  51.308(e)(3) that would allow a State to
``approve alternative measures 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
decisions be supported by adequate documentation of its analyses.''
\43\
---------------------------------------------------------------------------

    \43\ 71 FR 60612, 60621.
---------------------------------------------------------------------------

    Under 40 CFR 51.308(e)(2)(iii) and (iv), all emission reductions
for the alternative program must take place by 2018, and all the
emission reductions resulting from the alternative program must be
surplus to those reductions resulting from measures adopted to meet
requirements of the CAA as of the baseline date of the SIP. Pursuant to
40 CFR 51.309(e)(2)(v), states have the option of including a provision
that the emissions trading program or other alternative measure include
a geographic enhancement to the program to address the requirement
under 40 CFR 51.302(c) related to BART for reasonably attributable
visibility impairment from the pollutants covered under the emissions
trading program or other alternative measure.

E. Summary of State Regional Haze Submittals and EPA Actions

1. 2008 and 2011 Utah RH SIPs
    On May 26, 2011, the Governor of the State of Utah submitted to EPA
a Regional Haze SIP under 40 CFR 51.309 of the RHR (``2011 Utah RH
SIP''). This submittal included BART determinations for NOX
and PM10 at Utah's four subject-to-BART sources:
PacifiCorp's Hunter Units 1 and 2 and Huntington Units 1 and 2. All
four units are tangentially fired fossil fuel fired EGUs each with a
net generating capacity of 430 MW, permitted to burn bituminous coal.
This submittal also included a backstop trading program under 40 CFR
51.309 intended to meet the requirement for controlling SO2
by establishing a cap on emissions. The trading program covers Utah,
Wyoming, New Mexico and the City of Albuquerque.
    Utah also submitted SIPs on December 12, 2003, August 8, 2004 and
September 9, 2008, to meet the requirements of the RHR. These
submittals were, for the most part, superseded and replaced by the May
26, 2011 submittal as further explained in the next section discussing
our action on these submittals.
2. 2012 EPA Action on 2011 and 2008 Utah RH SIPs
    On December 14, 2012, EPA partially approved and partially
disapproved the 2011 Utah RH SIP.\44\ We approved all sections of the
2011 Utah RH SIP as meeting the requirements of 40 CFR 51.309, with the
exception of the requirements under 40 CFR 51.309(d)(4)(vii) pertaining
to NOX and PM10 BART. EPA's partial disapproval
action was based on the following: (1) Utah did not take into account
the five statutory factors in its BART analyses for NOX and
PM10; and (2) the 2011 Utah RH SIP did not contain the
provisions necessary to make the BART limits practically enforceable as
required by section 110(a)(2) of the CAA and 40 CFR 51, appendix V.\45\
---------------------------------------------------------------------------

    \44\ 77 FR 74355, 74357 (Dec. 14, 2012).
    \45\ Id.
---------------------------------------------------------------------------

    We also approved two sections of the 2008 Utah RH SIP.
Specifically, we approved UAR R307-250--Western Backstop Sulfur Dioxide
Trading Program and R307-150--Emission Inventories. We took no action
on the rest of the 2008 submittal as the 2011 submittal superseded and
replaced the remaining sections of the 2008 submittal. We also took no
action on the December 12, 2003 and August 8, 2004 submittals as these
were superseded by the 2011 submittal.
    On November 8, 2011, we separately proposed approval of Section G--
Long-Term Strategy for Fire Programs of the May 26, 2011 submittal and
finalized our approval of that action on January 18, 2013.\46\
---------------------------------------------------------------------------

    \46\ 78 FR 4071, 4072 (Jan. 18, 2013).
---------------------------------------------------------------------------

3. 2013 Litigation
    In 2013, conservation groups sued EPA in the U.S. Court of Appeals
for the Tenth Circuit on our approval of the SO2 backstop
trading program as an alternative to BART. On October 21, 2014, the
court upheld EPA's finding that the trading program was better than
BART.\47\
---------------------------------------------------------------------------

    \47\ Wildearth Guardians v. United States EPA, 728 F.3d 1075,
1083-84 (10th Cir. 2013).
---------------------------------------------------------------------------

4. 2015 Utah RH SIPs
    On June 4, 2015, the Governor of the State of Utah submitted to EPA
a revision to its Regional Haze SIP under 40 CFR 51.309 of the RHR
(``June 2015 Utah RH SIP''), specifically to address the requirements
under 40 CFR 51.309(d)(4)(vii) pertaining to NOX and
PM10 BART. Utah developed the June 2015 Utah RH SIP in
response to EPA's December 14, 2012 partial disapproval of the 2011
Utah RH SIP. The June 2015 Utah RH SIP evolved from a draft SIP on
which Utah sought public comment in October 2014. After receiving
extensive public comments, Utah decided to pursue a BART alternative
(``Utah BART Alternative,'' ``BART Alternative,'' or ``Alternative'')
under 40 CFR 51.308(e)(2) that takes credit for early NOX
reductions due to combustion controls installed at PacifiCorp's Hunter
and Huntington power plants in addition to NOX,
SO2, and PM10 reductions from the August 2015
retirement of PacifiCorp's nearby Carbon power plant. The June 2015
Utah RH SIP also includes measures to make the SIP requirements
practically enforceable and includes additional information pertaining
to the PM10 BART determinations for Hunter and Huntington to
address deficiencies identified by EPA in our December 2012 partial
disapproval.
    On October 20, 2015, Utah submitted to EPA an additional revision
to its Regional Haze SIP under 40 CFR 51.309 of the RHR (``October 2015
Utah RH SIP''). This SIP includes an enforceable commitment to provide
an additional SIP revision by mid-March 2018 to address concerns raised
in public comments that the State would be double counting certain
emissions reductions under the Utah BART Alternative in respect to
milestone reporting for the SO2 backstop trading program.
    Sections 110(a)(2) and 110(l) of the CAA require that a state
provide reasonable notice and public hearing

before adopting a SIP revision and submitting it to us. Utah, after
providing notice, accepted comments on the June 2015 Utah RH SIP in
April 2015 and accepted comments on the October 2015 Utah RH SIP in
mid-August through mid-September 2015. Following the comment period and
legal review by the Utah Attorney General's Office, the Utah Air
Quality Board adopted the June 2015 Utah RH SIP on June 3, 2015 and the
October 2015 Utah RH SIP on October 7, 2015. The Governor submitted the
SIP revisions to EPA on June 4, 2015 and October 20, 2015.

IV. Utah's Regional Haze SIP

A. Summary of Elements Under EPA's Previous Actions Upon Which We Are
Relying

    Several SIP elements that we previously approved in our December
2012 final rule and upon which we are relying in our current action
include the following:
1. Affected Class I Areas
    Utah provided two maps in Section XX of its 2011 RH SIP, one
showing the locations of the 16 Class I areas on the Colorado Plateau
and one showing the locations of the five in Utah (Arches National
Park, Bryce Canyon National Park, Canyonlands National Park, Capitol
Reef National Park, and Zion National Park).\48\ Utah also provided a
comparison of the monitored 2000-2004 baseline visibility conditions in
deciviews for the 20 percent best and 20 percent worst days to the
projected visibility improvement for 2018 for the 16 Class I areas.\49\
---------------------------------------------------------------------------

    \48\ See Utah Regional Haze State Implementation Plan, Sec.
XX.B.8, pp. 8-9 (Figures 1 and 2) (2011).
    \49\ See id., at Sec.  XX.K.2, p. 116 (Table 24).
---------------------------------------------------------------------------

    We determined that the State's SIP satisfies the requirements of 40
CFR 51.309(d)(2) for this element in our December 14, 2012 rulemaking.
2. BART-Eligible Sources
    Pursuant to 40 CFR 51.308(e)(2)(i)(A), the 2011 Utah RH SIP listed
the BART-eligible sources covered by the backstop trading program (see
Table 1). The State identified the following BART-eligible sources in
Utah: PacifiCorp Hunter Units 1 and 2 and PacifiCorp Huntington Units 1
and 2.
    PacifiCorp's Hunter Power Plant (Hunter), is located in Castle
Dale, Utah and consists of three electric utility steam generating
units. Of the three units, only Units 1 and 2 are subject to BART.
Hunter Units 1 and 2 have a nameplate generating capacity of 488.3 MW
each.\50\ The boilers are tangentially fired pulverized coal boilers,
burning bituminous coal from the Deer Creek Mine in Utah.
---------------------------------------------------------------------------

    \50\ See U.S. Energy Information Administration, Electric
Generating Capacity for 2011 (taken from Form EIA-860). See ``EIA
existing generating units 2011.xls'' spreadsheet in the docket.
---------------------------------------------------------------------------

    PacifiCorp's Huntington Power Plant (Huntington), is located in
Huntington City, Utah, and consists of two electric utility steam
generating units. Huntington Units 1 and 2 have a nameplate generating
capacity of 498 MW each.\51\ The boilers are tangentially fired
pulverized coal boilers, burning bituminous coal from the nearby Deer
Creek Mine.
---------------------------------------------------------------------------

    \51\ Id.
---------------------------------------------------------------------------

    We determined that the State's SIP satisfies the requirements of 40
CFR 51.309(e)(2)(i)(A) in our December 14, 2012 rulemaking.
3. Sources Subject-to-BART
    Pursuant to 40 CFR 51.308(e)(2)(i)(B), the 2011 Utah RH SIP
described the State's source modeling that determined which of the
BART-eligible sources within Utah cause or contribute to visibility
impairment and are thus subject-to-BART (more information on subject-
to-BART sources and modeling can be found in Section XX.D.6 of the 2011
Utah RH SIP and section V.F of our May 16, 2012 proposed rulemaking).
    Table 1 shows Utah's BART-eligible sources covered by the 309
SO2 backstop program, Hunter Units 1 and 2, and Huntington
Units 1 and 2, and indicates that all are subject-to-BART.
    We determined that the State's SIP satisfies the requirements of 40
CFR 51.308(e)(2)(i)(B) in our December 14, 2012 rulemaking.

                                      Table 1--Subject-to-BART Status for Utah's Section 309 BART-Eligible Sources
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Generating
           Company                  Source        Unit ID    Service     BART Category     capacity       Coal type        Boiler type     Subject-  to-
                                                               date                          (MW)                                              BART?
--------------------------------------------------------------------------------------------------------------------------------------------------------
PacifiCorp...................  Hunter..........          1       1978  Fossil Fuel EGU.          430  Bituminous......  Tangential......  Yes.
PacifiCorp...................  Hunter..........          2       1980  Fossil Fuel EGU.          430  Bituminous......  Tangential......  Yes.
PacifiCorp...................  Huntington......          1       1977  Fossil Fuel EGU.          430  Bituminous......  Tangential......  Yes.
PacifiCorp...................  Huntington......          2       1974  Fossil Fuel EGU.          430  Bituminous......  Tangential......  Yes.
--------------------------------------------------------------------------------------------------------------------------------------------------------

    We note that Section XX.D.6 in the June 2015 Utah RH SIP supersedes
Section XX.D.6 in the 2011 Utah RH SIP and that some reformatting
occurred. As Utah did not make substantive revisions to the SIP
provisions addressing BART-eligible sources and subject-to-BART
sources, XX.D.6.b and XX.D.6.c, in the 2011 SIP, we are not proposing
any additional action on these provisions in this preamble.

B. Summary of Utah's BART Alternative and PM10 BART SIP Revision

    Utah's June 2015 RH SIPs include the following SIP provisions:
     Revised R307-110-17, General Requirements: State
Implementation Plan. Section IX, Control Measures for Area and Point
Sources, Part H, Emissions Limits (incorporates by reference most
recently amended SIP Section IX, Part H into state rules)
     Revised R307-110-28, General Requirements: State
Implementation Plan, Regional Haze (incorporates by reference most
recently amended SIP Section XX into state rules)
     Revised SIP Section XX.D.6 Regional Haze. Long-Term
Strategy for Stationary Sources. Best Available Retrofit Technology
(BART) Assessment for NOX and PM (supersedes Section XX.D.6
in the 2011 Utah RH SIP)
     New SIP Section IX.H.21 General Requirements: Control
Measures for Area and Point Sources, Emission Limits and Operating
Practices, Regional Haze Requirements
     New SIP Section IX.H.22 Source Specific Emission
Limitations: Regional Haze Requirements, Best Available Retrofit
Technology.
    The June 2015 Utah RH SIP, including the five SIP revisions listed
previously, consists of the following three components: (1) a
NOX BART alternative that includes NOX and
SO2, and PM10 emission reductions from

Hunter Units 1-3, Huntington Units 1 and 2, and Carbon Units 1 and 2
and PM10 emission reductions from Carbon Units 1 and 2; (2)
BART determinations for PM10 at Hunter Units 1 and 2 and
Huntington Units 1 and 2 based on a streamlined analysis; and (3)
monitoring, recordkeeping and reporting requirements for the Utah BART
Alternative and PM10 BART emission limits to make the SIP
requirements practically enforceable. The emission limits in the June
2015 Utah RH SIP are provided in Table 2. We further explain the three
components of the SIP.

                Table 2--Emission Limits and Shutdown in Utah's BART Alternative and PM10 SIP\1\
----------------------------------------------------------------------------------------------------------------
                                                PM10 Limit \2\ (lb/    NOX Limit \3\ (lb/
              Source                   Unit    MMBtu, three-run test      MMBtu, 30-Day           SO2 Limit
                                                      average)          Rolling Average)
----------------------------------------------------------------------------------------------------------------
Hunter............................          1  0.015................  0.26................  NA.
  2...............................          2  0.015................  0.26................  NA.
                                            3  NA...................  0.34................  NA.
Huntington........................          1  0.015................  0.26................  NA.
                                            2  0.015................  0.26................  NA.
Carbon............................          1  Shutdown by August     Shutdown by August    Shutdown by August
                                                15, 2015.              15, 2015.             15, 2015.
                                            2  Shutdown by August     Shutdown by           Shutdown by August
                                                15, 2015.              August15, 2015.       15, 2015.
----------------------------------------------------------------------------------------------------------------
\1\ Obtained from the June 2015 Utah RH SIP, Section IX.H.22.
\2\ Based on annual stack testing.
\3\ Based on continuous emission monitoring system (CEMS) measurement.

1. Utah BART Alternative
    Utah has opted to establish an alternative measure for
NOX under 40 CFR 51.308(e)(2). The State compared the Utah
BART Alternative against a BART Benchmark of selective catalytic
reduction (SCR) on all four BART units at Hunter and Huntington (Units
1 and 2 at both plants). Utah's BART Alternative consists of the
shutdown of Carbon Units 1 and 2 and the installation of upgraded
NOX combustion controls (new low-NOX burners
[LNB] and overfire air [OFA]) on Hunter Unit 3 (all non-BART units).
The Utah BART Alternative also includes the NOX reductions
from installation of upgraded combustion controls (new LNB and
separated overfire air [SOFA]) at Hunter Units 1 and 2 and Huntington
Units 1 and 2 (all BART units). The BART Benchmark includes the four
BART units with combustion controls and SCR, Carbon's baseline
emissions, and Hunter Unit 3's emissions with original combustion
controls. The Utah BART Alternative is generally described in SIP
Section XX.D.6 with a detailed demonstration included in Chapter 1 of
Utah's Technical Support Document (TSD) to support the State's
assertion that the alternative achieves greater reasonable progress
than BART. The State's demonstration is also described in more detail
in section IV.C.
    A summary of the State's estimates of emissions for the Utah BART
Alternative and the BART Benchmark is provided in Table 3. EPA
developed a summary of the emissions reductions based on Utah's
emission estimates and this is presented in Table 4.
    Utah indicated that PacifiCorp announced plans to shut down the
Carbon Power Plant in 2015 due to the high cost to control mercury to
meet the requirements of EPA's Mercury and Air Toxics Standards
(MATS).\52\ The State noted that the MATS rule was finalized in 2011,
and the Utah RH SIP contains the requirement for the Carbon Power Plant
to shut down in August 2015. Therefore, the emission reductions occur
after the 2002 base year for Utah's RH SIP and thus, Utah asserts, the
reductions may be considered as part of an alternative strategy under
40 CFR 51.308(e)(2)(iv).
---------------------------------------------------------------------------

    \52\ Utah Regional Haze State Implementation Plan, p. 7 (TSD
Chapter 1) (2011).
---------------------------------------------------------------------------

2. PM10 BART Determinations
    Utah included a streamlined analysis for PM10 BART
determinations in accordance with section D.9 of the BART Guidelines
for the BART units at Hunter and Huntington in the SIP TSD in Chapter
1, Section III and referenced this analysis in SIP Section XX.D.6. In
the TSD, Utah summarized the BART analysis submitted by PacifiCorp in
an August 5, 2014 report.\53\
---------------------------------------------------------------------------

    \53\ For PacifiCorp BART analyses reports, see TSD Chapter 2 of
the SIP.
---------------------------------------------------------------------------

    PacifiCorp's analysis identified three available technologies:
Upgraded ESP and flue gas conditioning (0.040 lb/MMBtu); polishing
fabric filter (0.015 lb/MMBtu); and replacement fabric filter (0.015
lb/MMBtu). The 2008 Utah RH SIP and BART determination had required
PacifiCorp to install a fabric filter baghouse with a PM10
emission limit of 0.015 lb/MMBtu at the Hunter and Huntington BART
units. Utah staff reviewed PacifiCorp's 2012 analysis and determined
that the baghouse technology required in 2008 is still the most
stringent technology available and that 0.015 lb/MMBtu represents the
most stringent emission limit. Utah cited EPA's BART Guidelines and
regional haze actions in Colorado, Wyoming, North Dakota and Montana to
support these assertions.
    Utah determined that the PM10 BART emission limit for
Hunter Units 1 and 2 and Huntington Units 1 and 2 was 0.015 lb/MMBtu
based on a three-run test average. Utah noted that because the most
stringent technology is in place at these units and that the
PM10 emission limits have been made enforceable in the SIP,
no further analysis was required.
3. Monitoring, Recordkeeping and Reporting
    To address EPA's partial disapproval of the 2011 Utah RH SIP for
lack of enforceable measures and monitoring, recordkeeping and
reporting requirements for the Utah BART Alternative and the
PM10 BART determinations, Utah added two new subsections to
SIP Sections IX, General H.21 and 22. Under H.21, Utah has detailed
general requirements for sources subject to its regional haze program.
Under H.22, Utah has listed source-specific regional haze requirements
for Hunter, Huntington and Carbon.
    Specifically, under H.21, Utah added a new definition for boiler
operating day. Utah noted that state rules R307-107-1 and R307-107-2
(applicability, timing and reporting of breakdowns) apply to sources
subject to regional haze requirements under H.22. Utah required that
information used to determine compliance shall be recorded for all
periods when the source is in operation, and that such records shall be
kept for a minimum of five years. Under H.21, Utah specified that
emission limitations listed in H.22 shall apply at all times

and identified stack testing requirements to show compliance with those
emission limitations. Finally, under H.21, Utah also specified the
requirements for continuous emission monitoring by listing the
requirements and cross-referencing the State's rule for continuous
emission monitoring system requirements, R307-170 as well as 40 CFR
part 13 and 40 CFR part 60, appendix B--Performance Specifications.
Utah included the requirements to calculate hourly average
NOX concentrations for any hour in which fuel is combusted
and a new 30-day rolling average emission rate at the end of each
boiler operating day. Utah also noted that the hourly average
NOX emission rate is valid only if the minimum number of
data points specified in R307-170 is acquired for both the pollutant
concentration monitor and diluent monitor.
    Under H.21, Utah did not provide for reporting of violations of
PM10 emissions limitations for instances other than
breakdowns (e.g., stack test violations). However, the State provided a
commitment letter on December 10, 2015 to address this deficiency with
a SIP revision within one year of EPA's final action on the June 4,
2015 RH SIP.\54\
---------------------------------------------------------------------------

    \54\ Letter from Department of Environmental Quality, State of
Utah to EPA, DAQP-120-15 (Dec. 10, 2015).
---------------------------------------------------------------------------

    Under H.22, Utah provided the NOX and PM10
emission limitations for Hunter Units 1 through 3 and Huntington Units
1 and 2, a requirement to perform annual stack testing for
PM10, and a requirement to measure NOX via
continuous emission monitoring for the sources covered under the Utah
BART Alternative. Under H.22, Utah also listed the enforceable
conditions related to closing Carbon Units 1 and 2 by August 15, 2015
including PacifiCorp's and Utah's notification and permit rescission
obligations.

C. Summary of Utah's Demonstration for Alternative Program

    As discussed previously in background section III.A, a state may
opt to implement an alternative measure rather than to require sources
subject to BART to install, operate, and maintain BART. Utah has
included the following information in its June and October 2015 RH SIPs
to address the regulatory criteria for an alternative program:

1. A List of All BART-Eligible Sources Within the State
    Pursuant to 40 CFR 51.308(e)(2)(i)(A) and (B), the SIP must include
a list of all BART-eligible sources within the State. Utah included a
list of BART-eligible sources and noted the following sources are all
covered by the alternative program:

 PacifiCorp Hunter, Unit 1
 PacifiCorp Hunter, Unit 2
 PacifiCorp, Huntington, Unit 1
 PacifiCorp, Huntington, Unit 2

    Utah provided the same list of BART-eligible sources in the 2011 RH
SIP. We determined that the State's SIP satisfies the requirements of
40 CFR 51.309(e)(2)(i)(A) in our December 14, 2012 rulemaking.
2. A List of All BART-Eligible Sources and All BART Source Categories
Covered by the Alternative Program
    Pursuant to 40 CFR 51.308(e)(2)(i)(B), each BART-eligible source in
the State must be subject to the requirements of the alternative
program or have a federally enforceable emission limitation determined
by the State and approved by EPA as meeting BART. In this instance, the
alternative program covers all the BART-eligible sources in the state,
Hunter Units 1 and 2 and Huntington Units 1 and 2, in addition to three
non-BART units, PacifiCorp's Hunter Unit 3 and Carbon Units 1 and 2.
    Utah provided the same list of BART sources subject to an
alternative program in the 2011 RH SIP. We determined that the State's
SIP satisfies the requirements of 40 CFR 51.309(e)(2)(i)(B) in our
December 14, 2012 rulemaking.
3. Analysis of BART and Associated Emission Reductions Achievable
    Pursuant to 40 CFR 51.308(e)(2)(i)(C), the SIP must include an
analysis of BART and associated emission reductions at Hunter and
Huntington. In the June 2015 Utah RH SIP, the State compared the Utah
BART Alternative to a BART Benchmark that included the most stringent
NOX BART controls, SCR plus new LNBs and SOFA, at the four
BART units.
4. Analysis of Projected Emissions Reductions Achievable Through the
BART Alternative
    Pursuant to 40 CFR 51. 308(e)(2)(D), the SIP must include ``[a]n
analysis of the projected emissions reductions achievable through the .
. . alternative measure.'' A summary of the State's estimates of
emissions in tons per year (tpy) for the Utah BART Alternative and the
BART Benchmark is provided in Table 3. A summary of the emissions
reductions based on those emission estimates is presented in Table 4.
---------------------------------------------------------------------------

    \55\ Utah Regional Haze State Implementation Plan, Technical
Support Document, Ch. 1 (Reference Table 2) (2015).

                                 Table 3--Estimated Emissions Under Utah's BART Benchmark and the BART Alternative \55\
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                              NOX emissions (tpy)         SO2 emissions (tpy)      PM10 emissions (tpy) \4\            Combined
                                         ---------------------------------------------------------------------------------------------------------------
                  Units                     Benchmark    Alternative    Benchmark    Alternative
                                               \2\           \3\           \2\           \3\        Benchmark    Alternative    Benchmark    Alternative
--------------------------------------------------------------------------------------------------------------------------------------------------------
Carbon 1................................         1,408             0         3,388             0           221             0         5,016             0
Carbon 2................................         1,940             0         4,617             0           352             0         6,909             0
Hunter 1 \1\............................           775         3,412         1,529         1,529           169           169         2,473         5,100
Hunter 2................................           843         3,412         1,529         1,529           169           169         2,541         5,110
Hunter 3................................         6,530         4,622         1,033         1,033           122           122         7,685         5,777
Huntington 1............................           809         3,593         1,168         1,168           176           176         2,153         4,937
Huntington 2............................           856         3,844         1,187         1,187           200           200         2,243         5,231
                                         ---------------------------------------------------------------------------------------------------------------
    Total...............................        13,161        18,882        14,451         6,446         1,409           836        29,020        26,164
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Hunter 1 controls were installed in the spring of 2014, therefore Hunter 2 actual emissions are used as a surrogate.
\2\ Most stringent NOX rate for BART-eligible units (see email and spreadsheet, ``Attachment to Utah September 16, 2015 email, BART Analysis.pdf'' in
  the docket, inadvertently omitted from Utah TSD), 2012-2013 actual emissions Carbon, 2001-2003 actual emissions Hunter 3 (EPA Acid Rain Program).
\3\ Average actual emissions 2012-13 for Hunter and Huntington units, EPA Acid Rain Program.
\4\ Actual emissions for 2012, Utah Department of Air Quality annual inventory.

  Table 4--EPA Summary of Emission Reductions Achievable With the Utah BART Alternative as Compared to the BART
                                                    Benchmark
----------------------------------------------------------------------------------------------------------------
                                                                    Combined emissions for all units  (tpy)
                         Description                         ---------------------------------------------------
                                                                  NOX          SO2          PM10       Combined
----------------------------------------------------------------------------------------------------------------
BART Benchmark..............................................       13,161       14,451        1,409       29,020
BART Alternative............................................       18,882        6,446          836       26,164
Emission Reduction (BART Benchmark minus BART Alternative)         -5,721        8,005          573        2,856
 \1\........................................................
----------------------------------------------------------------------------------------------------------------
\1\ A negative value indicates the BART Alternative results in more emissions of the specified pollutant in
  comparison to the BART Benchmark.

5. A Determination That the Alternative Achieves Greater Reasonable
Progress Than Would Be Achieved Through the Installation and Operation
of BART
    Pursuant to 40 CFR 51.308(e)(2)(i)(E), the State must provide a
determination under 40 CFR 51.308(e)(3) or otherwise based on the clear
weight of evidence that the alternative achieves greater reasonable
progress than BART. 40 CFR 51.308(e)(3), in turn, provides two
different tests for determining whether the alternative achieves
greater reasonable progress than BART.
    Utah first used the ``greater emission reductions'' test in 40 CFR
51.308(e)(3) to support its assertion that the BART Alternative
achieves greater reasonable progress. In the June 2015 Utah RH SIP, the
State noted that the Hunter, Huntington and Carbon plants are all
located within 40 miles of each other in Central Utah. Utah stated that
because of the close proximity of the three plants, the distribution of
emissions would not be substantially different under the Utah BART
Alternative than under BART. With the alternative measure resulting in
greater aggregate emission reductions by 2,856 tons/year (tpy)
(described in Table 4), Utah asserted that the alternative measure may
be deemed to achieve greater reasonable progress than BART under
51.308(e)(3).
    Utah also chose to conduct a weight-of-evidence analysis under
51.308(e)(2) based on emissions from the Hunter, Huntington, and Carbon
power plants and considered the following evidence: \56\
---------------------------------------------------------------------------

    \56\ Utah referenced that greater reasonable progress can be
demonstrated using one of two methods: (1) greater emission
reductions than under BART (40 CFR 51.308(e)(3)); or (2) based on
the clear weight of evidence (40 CFR 51.308(e)(2)(i)(E)). Utah
further explained that: As the U.S. Circuit Court of Appeals for the
10th Circuit recently observed, the state is free to choose one
method or the other. WildEarth Guardians v. E.P.A., 770 F.3d 919,
935-37 (10th Cir. 2014). Finally, Utah noted that the court
characterized the former approach as ``quantitative'' and the latter
as ``qualitative,'' and specifically sanctioned the use of
qualitative factors under the clear weight of evidence.
---------------------------------------------------------------------------

a. Annual Emissions Comparison for Visibility-impairing Pollutants
    The emissions of visibility-impairing pollutants from both the Utah
BART Alternative and the BART Benchmark, as estimated by the State, are
summarized in Table 3. Compared with the Utah BART Benchmark, the State
projects that the Utah BART Alternative will result in 5,721 tpy more
NOX emissions, 8,005 tpy fewer SO2 emissions and
573 tpy fewer PM10 emissions. Utah also found that the
combined emissions of NOX, SO2 and
PM10 will be 2,856 tpy lower under the Utah BART
Alternative.
b. Improvement in the Number of Days With Significant Visibility
Impairment
    Utah provided modeling results to assess the improvement in the
number of days with significant visibility impairment--that is, the
improvement in the number of days with impacts that either cause (> 1.0
dv) or contribute (> 0.5 dv) to visibility impairment. The State
presented this information in a number of ways, including: (1) the
average number of days per year for three years modeled (2001-2003)
with impacts above the cause and contribute thresholds for the nine
affected Class I areas under the BART Alternative as compared to under
the BART Benchmark; and (2) the total number of days for the three
years modeled with impacts above the thresholds for the nine Class I
areas under the two scenarios.\57\
---------------------------------------------------------------------------

    \57\ Utah noted that EPA has proposed approval of an Alternative
Measure for the Apache Generating Station in Arizona on similar
``weight of evidence'' grounds. 79 FR 56322, 56327 (Sept. 19, 2014).
Utah also noted that EPA has approved a similar Alternative Measure
in Washington, based in part on a reduction in the number of days of
impairment greater than 0.5 dv and 1.0 dv. 79 FR 33438, 33440-33442
(June 11, 2014).
---------------------------------------------------------------------------

    On average for the three years modeled, the Utah BART Alternative
causes visibility impairment (>1.0 dv) on fewer days than the BART
Benchmark (258 days vs. 264 days, for the nine affected Class I areas).
Similarly, on average for the three years modeled, the Utah BART
Alternative also contributes to visibility impairment (>0.5 dv) on
fewer days than the BART Benchmark (441 days vs. 499 days for the nine
affected Class I areas). See Tables 5 and 6.
---------------------------------------------------------------------------

    \58\ Utah Regional Haze State Implementation Plan, Technical
Support Document, Ch. 1 (Reference Table 5) (2015).

                         Table 5--Average (2001-2003) Number of Days >1.0 dv Impact \58\
----------------------------------------------------------------------------------------------------------------
                                                                                BART            BART
                          Class I area                               Basecase       alternative      benchmark
----------------------------------------------------------------------------------------------------------------
Arches..........................................................             128              68              77
Black Canyon of the Gunnison....................................              36              10               9
Bryce Canyon....................................................              19               9               8
Canyonlands.....................................................             141              87              87
Capitol Reef....................................................              68              42              41
Flat Tops.......................................................              46              13              15
Grand Canyon....................................................              22              11              10
Mesa Verde......................................................              40              13              12
Zion............................................................              11               6               6
                                                                 -----------------------------------------------

    Total.......................................................             511             258             264
----------------------------------------------------------------------------------------------------------------

                         Table 6--Average (2001-2003) Number of Days >0.5 dv Impact \59\
----------------------------------------------------------------------------------------------------------------
                                                                                BART            BART
                          Class I area                               Basecase       alternative      benchmark
----------------------------------------------------------------------------------------------------------------
Arches..........................................................             176             109             130
Black Canyon of the Gunnison....................................              75              27              34
Bryce Canyon....................................................              36              17              19
Canyonlands.....................................................             178             131             140
Capitol Reef....................................................              96              63              65
Flat Tops.......................................................              93              34              44
Grand Canyon....................................................              38              19              20
Mesa Verde......................................................              71              32              37
Zion............................................................              21              10              10
                                                                 -----------------------------------------------
    Total.......................................................             784             441             499
----------------------------------------------------------------------------------------------------------------

    As for the total number of days over the course of the three
modeled years, the Utah BART Alternative causes visibility impairment
(> 1.0 dv) on fewer days than the BART Benchmark (775 days vs. 793 days
for the nine affected Class I areas). Similarly, in total for the three
years modeled, the Utah BART Alternative also contributes to visibility
impairment (> 0.5 dv) on fewer days than the BART Benchmark (1,323 days
vs. 1,498 days for the nine affected Class I areas). See Tables 7 and
8.
---------------------------------------------------------------------------

    \59\ See id., at Technical Support Document, Ch. 1 (Reference
Table 6).
    \60\ See id., at Technical Support Document, Chapter 6.b
(Summary of Visibility Modeling).

                          Table 7--Total (2001-2003) Number of Days >1.0 dv Impact \60\
----------------------------------------------------------------------------------------------------------------
                                                                                BART            BART
                          Class I area                               Basecase       alternative      benchmark
----------------------------------------------------------------------------------------------------------------
Arches..........................................................             383             203             230
Black Canyon of the Gunnison....................................             108              31              28
Bryce Canyon....................................................              57              26              25
Canyonlands.....................................................             422             260             260
Capitol Reef....................................................             204             126             124
Flat Tops.......................................................             138              38              44
Grand Canyon....................................................              67              34              30
Mesa Verde......................................................             121              40              35
Zion............................................................              32              17              17
                                                                 -----------------------------------------------
    Total.......................................................           1,532             775             793
----------------------------------------------------------------------------------------------------------------

                          Table 8--Total (2001-2003) Number of Days >0.5 dv Impact \61\
----------------------------------------------------------------------------------------------------------------
                                                                                BART            BART
                          Class I area                               Basecase       alternative      benchmark
----------------------------------------------------------------------------------------------------------------
Arches..........................................................             529             327             391
Black Canyon of the Gunnison....................................             224              81             103
Bryce Canyon....................................................             107              50              57
Canyonlands.....................................................             533             393             420
Capitol Reef....................................................             288             188             194
Flat Tops.......................................................             280             101             133
Grand Canyon....................................................             115              56              59
Mesa Verde......................................................             213              97             110
Zion............................................................              63              30              31
                                                                 -----------------------------------------------
    Total.......................................................           2,352           1,323           1,498
----------------------------------------------------------------------------------------------------------------

c. 98th Percentile Impact (dv)
    Utah explained that the only metric it evaluated that showed
greater improvement for the BART Benchmark in comparison to the BART
Alternative was the 98th percentile metric when visibility impacts were
averaged across all Class I areas and meteorological years modeled.
Utah's comparison of the modeled visibility impacts on the 98th
percentile day (8th highest impacted day in a given meteorological
year) for the most impacted year shows that the BART Benchmark would
result in greater visibility improvement at five of the nine Class I
areas, and is better on average across all nine Class I areas (0.11 dv
difference). At two of the most impacted Class I areas, Canyonlands and
Capitol Reef, Utah found that the 98th percentile metric indicates the
BART Benchmark has 0.76 dv and 0.57 dv, respectively, greater
improvement than the Utah BART Alternative. At other Class I areas,
Utah found that the 98th percentile metric indicates that the BART
Alternative provides greater visibility improvement (for example, 0.44
dv at Flat Tops).
---------------------------------------------------------------------------

    \61\ See id.
---------------------------------------------------------------------------

    Utah noted that because high nitrate values occur primarily in the
winter months, the BART Benchmark achieved greater modeled visibility
improvement on certain winter days with high nitrate impacts. Utah
stated its position that there is greater uncertainty regarding the
effect of NOX reductions on wintertime nitrate values, and
thus on visibility, because past NOX emission reductions
have not resulted in corresponding reductions in monitored nitrate
values during the winter months. Utah noted it has greater confidence
in the visibility improvement due to reductions of SO2
because past reductions have resulted in corresponding reductions in
monitored sulfate values throughout the year.
d. Annual Average Impact (dv)
    As modeled by Utah, which used CALPUFF modeling results, the
average annual dv impact is better under the Utah BART Alternative at
five of the nine Class I areas, and is better on average across all the
Class I areas. The average impact was calculated by averaging all daily
modeling results for each year and then calculating a three-year
average from the annual average. Utah's information shows that the BART
Alternative is better than the BART Benchmark by 0.009 dv on average
across all nine Class I areas.
e. 90th Percentile Impact (dv)
    Utah's comparison of the modeled visibility impacts at the 90th
percentile (the 110th highest day across three years) dv impact shows
that the Utah BART Alternative is better at seven of the nine Class I
areas and is better averaged both across three years and across nine
Class I areas by 0.006 dv.
f. Timing for the Emissions Reductions
    Utah provided the schedule for installation of controls as noted in
Table 9. Utah discussed that NOX reductions at Hunter Units
1 and 2 and Huntington Units 1 and 2 occurred between 2006 and 2014,
earlier than was required by the Regional Haze Rule, providing a
corresponding early and on-going visibility improvement. Utah cited the
2014 10th Circuit Court of Appeals decision regarding the 309 program
to support that such early reductions are properly included as weight
of evidence in the State's analysis.

                     Table 9--Installation Schedule
------------------------------------------------------------------------
                                     Timing of control installation or
           Source/Unit                           shutdown
------------------------------------------------------------------------
Hunter 1........................  New LNB and SOFA-Spring 2014.
Hunter 2........................  New LNB and SOFA-Spring 2011.
Hunter 3........................  New LNB and OFA-Summer 2008.
Huntington 1....................  New LNB and SOFA-Fall 2010.
Huntington 2....................  New LNB and SOFA-December 2006.
Carbon 1........................  Shutdown August 2015.
Carbon 2........................  Shutdown August 2015.
------------------------------------------------------------------------

    The reductions under the Utah BART Alternative are required under
the State SIP by August 2015, as noted in Table 5, providing an early
and on-going visibility benefit as compared to BART.\62\ Installation
and operation of the combustion control upgrades at Hunter and
Huntington were made enforceable under Administrative Orders DAQE-
AN0102370012-08 and DAQE-AN0102380021-10.\63\
---------------------------------------------------------------------------

    \62\ Conforming permit amendments for the Carbon plant are due
under the SIP by December 15, 2015. Section IX.H.22 of Utah's SIP
requires PacifiCorp to cease operation of Carbon by August 15, 2015,
notify the State of the permanent closure by September 15, 2015, and
request rescission of Operating Permit #700002004 and Approval Order
DAQE-AN0100810005-08 by September 15, 2015. The State is then
required to rescind the operating permit and approval order by
December 15, 2015.
    \63\ Copies of Administrative Orders DAQE-AN0102370012-08 and
DAQE-AN0102380021-10 are included in the docket.
---------------------------------------------------------------------------

g. IMPROVE Monitoring Data
    Utah's SIP presents sulfate and nitrate monitoring data at the
Canyonlands IMPROVE monitor that shows that ``sulfates are the dominant
visibility impairing pollutant'' \64\ and that sulfate levels have
decreased,\65\ and references similar results at other Class I areas in
the TSD.\66\ Utah also presents data on trends in emissions from EGUs
showing substantial reductions in emissions of both SO2 and
NOX.\67\ Based on these data, Utah indicates it ``has
confidence that the SO2 reductions will achieve meaningful
visibility improvement,'' under the Utah BART Alternative, while ``the
visibility improvement during the winter months due to NOX
reductions is much more uncertain.'' \68\ Utah makes this point even
though nitrate concentrations are highest in the winter, explaining
that while there has been a reduction in NOX, the ammonium
nitrate values do not show similar improvement in the winter
months.\69\ Utah offers several possible explanations for the results,
but does not provide any definitive conclusions.\70\
---------------------------------------------------------------------------

    \64\ Utah Regional Haze State Implementation Plan, Technical
Support Document, Ch. 1, p. 12 (2015).
    \65\ Id. at p. 15.
    \66\ Id. at p. 12.
    \67\ Id. at p. 14.
    \68\ Id. at p.13.
    \69\ Id.
    \70\ Id. at pp. 16-19.
---------------------------------------------------------------------------

    Utah also presents data on the seasonality of park visitation and
monitoring data for nitrate and sulfates. The data show that the
highest measured nitrate concentrations occur in winter during the
period of lowest park visitation, and that sulfates affect visibility
throughout the year and are the dominant visibility impairing pollutant
from anthropogenic sources during the high visitation period of March
through November. Utah concludes that it has greater confidence that
reductions in SO2 will be reflected in improved visibility
for visitors to the Class I areas, while reductions in NOX
will have a more uncertain benefit for visitors to Class I areas.
h. Energy and Non-Air Quality Benefits
    Utah stated that energy and non-air quality environmental impacts
are one of the factors listed in CAA section 169A(g)(2) that must be
considered when determining BART. The State noted that the Utah BART
Alternative would avoid the energy penalty due to operating SCR units.
PacifiCorp included the energy penalty in its BART analysis as part of
the total cost for installing SCR on each of the units. The energy
penalty costs are provided in Table 10.
---------------------------------------------------------------------------

    \71\ PacifiCorp quantified the energy penalty associated with
SCR in its August 4, 2014 BART Analysis Update, Appendix A. See id.
at p. 26 (Table 13 presents this information).

                     Table 10--SCR Energy Penalty 71
------------------------------------------------------------------------
                                                       Energy penalty
                    Source/unit                    ---------------------
                                                        kW       $/year
------------------------------------------------------------------------
Hunter Unit 1.....................................      2,090    494,247
Hunter Unit 2.....................................      2,090    494,247
Huntington Unit 1.................................      2,182    516,098
Huntington Unit 2.................................      2,182    516,098
                                                   ---------------------
    Total.........................................      8,544  2,020,690
------------------------------------------------------------------------

    Utah presented additional non-air quality benefits associated with
the closure of the Carbon plant. First, it noted that solid wastes in
the form of fly ash from the electrostatic precipitators and bottom ash
conveyors which clean the residuals from the two steam generating units
(the boilers), would be eliminated. These wastes are currently
landfilled. The Carbon plant also runs water through the boilers as
well as two cooling towers. This uses water and has associated
wastewater discharge. Hauling the ash to the landfill requires
additional fuel use and water or chemical dust suppression for
minimization of fugitive dust. Finally, for maintenance and emergency
purposes, Utah noted that the plant has a number of emergency
generators, fire pumps, and ancillary equipment--all of which must be
periodically operated, tested and maintained--with associated air
emissions, fuel use, painting, and the like. Utah suggests that all of
these non-air quality impacts are reduced as the result of closing the
Carbon plant.
i. Cost
    Utah cited PacifiCorp's comments on the State's proposed SIP
revision that the BART Alternative not only produces greater reasonable
progress, including lower emissions and improved visibility, but that
it does so at a significant capital cost savings to PacifiCorp and its
customers as compared to the BART Benchmark. Utah acknowledged that it
did not officially determine the cost of installing SCR on the four
BART units, but that it believed the cost of installing SCR would be
significant. On the other hand, Utah noted that the Carbon Plant has
already been closed due to the high cost of complying with the MATS
rule. Utah explained that the costs to Utah rate payers (and those in
other states served by PacifiCorp) to replace the power generated by
the Carbon Plant have already occurred; there will be no additional
cost to achieve the co-benefit of visibility improvement. As a result,
Utah asserted that the BART Alternative not only achieves better
visibility improvements than would be achieved by requiring SCR as BART
at the four EGUs, but at a significantly lower cost. The State believed
this presents a classic ``win/win'' scenario--the BART Alternative
results in greater reasonable progress that is achieved at a much lower
price compared to SCR. The State also noted that cost is one of the
factors listed in CAA section 169A(g)(2) that should be considered when
determining BART.
6. Requirement That Emission Reductions Take Place During Period of
First Long-Term Strategy
    Pursuant to 40 CFR 51.308(e)(2)(iii), the State must ensure that
all necessary emission reductions take place during the period of the
first long-term strategy for regional haze, i.e., by December 31, 2018.
The RHR further provides that, ``[t]o meet this requirement, the State
must provide a detailed description of the . . . alternative measure,
including schedules for implementation, the emission reductions
required by the program, all necessary administrative and technical
procedures for implementing the program, rules for accounting and
monitoring emissions, and procedures for enforcement.'' \72\
---------------------------------------------------------------------------

    \72\ 40 CFR 51.308(e)(2)(iii).
---------------------------------------------------------------------------

    As noted previously, the Utah SIP revision incorporates the
revisions to R307-110-17, Section IX, Control Measures for Area and
Point Sources, Part H, Emissions Limits, which includes provisions for
implementing the Utah BART Alternative. In addition to the emission
limitations for NOX and PM10, and the requirement
for shutdown of the Carbon Plant listed in Table 2, the SIP includes
compliance dates, operation and maintenance requirements, and
monitoring, recordkeeping, and reporting requirements.
7. Demonstration That Emissions Reductions From Alternative Program
Will Be Surplus
    Pursuant to 40 CFR 51.308(e)(2)(iv), the SIP must demonstrate that
the emissions reductions resulting from the alternative measure will be
surplus to those reductions resulting from measures adopted to meet
requirements of the CAA as of the baseline date of the SIP. The
baseline date for regional haze SIPs is 2002.\73\ Utah developed the
2002 baseline inventory in the 2008 RH SIP for regional modeling,
evaluating the impact on Class I areas outside of the Colorado Plateau,
and BART as outlined in EPA Guidance and the July 6, 2005 BART Rule.
Utah noted that 2002 is the baseline inventory that was used by other
states throughout the country when evaluating BART under the provisions
of 40 CFR 51.308 and that any measure adopted after 2002 is considered
``surplus'' under 40 CFR 51.308(e)(2)(iv). Utah referenced other EPA
actions that are consistent with this interpretation.\74\ Utah stated
that the BART Benchmark scenario includes measures required before the
baseline date of the SIP but does not include later measures that are
credited as part of the BART Alternative scenario.
---------------------------------------------------------------------------

    \73\ See Memorandum from Lydia Wegman and Peter Tsirigotis, 2002
Base Year Emission Inventory SIP Planning: 8-hr Ozone,
PM2.5, and Regional Haze Programs (Nov. 18, 2002),
available at http://www3.epa.gov/ttnchie1/eidocs/2002baseinven_102502new.pdf.
    \74\ 79 FR 33438, 33441-33442 (June 11, 2014); 79 FR 56322,
56328 (Sept. 9, 2014).
---------------------------------------------------------------------------

    To address potential concerns with double counting SO2
emissions reductions from the Carbon plant closure under both the 308
and 309 programs, in addition to providing the explanation in the June
2015 SIP (discussed in TSD Chapter 1, Section X), Utah's October 7,
2015 SIP also includes enforceable commitments to address these
concerns. The State explained how the WRAP modeling done to support the
Utah RH backstop trading program SIP included regional SO2
emissions based on the 2018 SO2 milestone and also included
NOX and PM10 emissions from the Carbon plant.
Actual emissions in the three-state region are calculated each year and
compared to the milestones. Utah provided Table 11 to show that in 2011
emissions were below the 2018 milestone (141,849 tpy). Utah noted that
the most recent milestone report for 2013 demonstrates that
SO2 emissions are currently 26 percent lower than the 2018
milestone. Utah stated that the Carbon plant was fully operational in
the years 2011-2013 when the emissions were below the 2018 milestone.
The State noted that the SO2 emission reductions from the
closure of the Carbon plant are surplus to what is needed to meet the
2018 milestone established in Utah's RH SIP.
---------------------------------------------------------------------------

    \75\ See Utah Regional Haze State Implementation Plan, Technical
Support Document, Ch. 1 (Reference Table 15) (2015).

                                        Table 11--SO2 Milestone Trends 75
----------------------------------------------------------------------------------------------------------------
                                                                                Three-Year