[Federal Register Volume 85, Number 51 (Monday, March 16, 2020)]
[Proposed Rules]
[Pages 14847-14869]
[FR Doc No: 2020-05106]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R06-OAR-2015-0189; FRL-10006-02-Region 6]

Air Plan Approval; Arkansas; Arkansas Regional Haze and
Visibility Transport State Implementation Plan Revisions and Withdrawal
of Federal Implementation Plan

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: Pursuant to the Clean Air Act (CAA or the Act), the
Environmental Protection Agency (EPA) is proposing to approve a
revision to the Arkansas State Implementation Plan (SIP) submitted by
the State of Arkansas through the Arkansas Division of Environmental
Quality (ADEQ) on August 13, 2019. The SIP submittal addresses
requirements of the Act and the Regional Haze Rule for visibility
protection in mandatory Class I Federal areas (Class I areas) for the
first implementation period. The EPA is proposing to approve an
alternative measure to best available retrofit technology (BART) for
sulfur dioxide (SO2), particulate matter (PM), and nitrogen
oxide (NOX) at the Domtar Ashdown Mill and elements of the
SIP submittal that relate to these BART requirements at this facility.
In addition, we are proposing to approve the withdrawal from the SIP
the previously approved PM10 BART limit and the federal
implementation plan (FIP) provisions for the Domtar Ashdown Mill. The
EPA is also concurrently proposing to approve Arkansas' interstate
visibility transport provisions from the August 10, 2018, regional haze
SIP submittal as supplemented by the visibility transport provisions in
the October 4, 2019, interstate transport SIP submittal, which covers
the following national ambient air quality standards (NAAQS): The 2006
24-hour fine particulate matter (PM2.5) NAAQS; the 2012
annual PM2.5 NAAQS; the 2008 and 2015 eight-hour ozone
(O3) NAAQS; the 2010 one-hour nitrogen dioxide
(NO2) NAAQS; and the 2010 one-hour SO2 NAAQS.

DATES: Written comments must be received on or before April 15, 2020.

ADDRESSES: Submit your comments, identified by Docket No. EPA-R06-OAR-
2015-0189, at http://www.regulations.gov or via email to
<EMAIL_ADDRESS>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 any information electronically that is considered
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 with multimedia
submissions and should include all discussion points desired. The EPA
will generally not consider comments or their contents located outside
of the primary submission (i.e., on the web, cloud, or other file
sharing systems). For additional submission methods, please contact
James E. Grady,<PHONE_NUMBER><EMAIL_ADDRESS>For the full EPA
public comment policy, information about CBI or multimedia submissions,
and general guidance on making effective comments, please visit https://www.epa.gov/dockets/commenting-epa-dockets.
    Docket: The index to the docket for this action is available
electronically at www.regulations.gov and in hard copy at the EPA
Region 6, 1201 Elm Street, Suite 500, Dallas, Texas 75270-2102. While
all documents in the docket are listed in the index, some information
may be publicly available only at the hard copy location (e.g.,
copyrighted material), and some may not be publicly available at either
location (e.g., CBI).

FOR FURTHER INFORMATION CONTACT: James E. Grady, EPA Region 6 Office,
Regional Haze and SO2 Section, 1201 Elm Street, Suite 500,
Dallas, TX 72570,<PHONE_NUMBER><EMAIL_ADDRESS>To inspect the
hard copy materials, please schedule an appointment with Mr. Grady or
Mr. Bill Deese at<PHONE_NUMBER>.

SUPPLEMENTARY INFORMATION: Throughout this document ``we,'' ``us,'' or
``our'' mean ``the EPA.''

Table of Contents

I. Background
    A. Regional Haze Principles
    B. Requirements of the CAA and the EPA's Regional Haze Rule
    C. BART Requirements
    D. BART Alternative Requirements
    E. Long-Term Strategy and Reasonable Progress Requirements
    F. Previous Actions on Arkansas Regional Haze

    G. Arkansas Regional Haze Phase III SIP Submittal
    H. Arkansas Visibility Transport
II. Evaluation of the Arkansas Regional Haze Phase III SIP Submittal
    A. Summary of Arkansas' BART Alternative for Domtar Ashdown Mill
    B. Demonstration That BART Alternative Achieves Greater
Reasonable Progress
    1. List All BART-Eligible Sources Within the State
    2. List All BART-Eligible Sources and Source Categories Covered
by the Alternative Program
    3. Analysis of BART and Associated Emission Reductions
    4. Analysis of Projected Emission Reductions Achievable Through
BART Alternative
    5. Determination That Alternative Achieves Greater Reasonable
Progress than BART
    C. Requirement That Emission Reductions Take Place During the
Period of the First Long-Term Strategy
    D. Demonstration That Emission Reductions From Alternative
Measure Will Be Surplus
    E. Implementation of the BART Alternative Through Permit
Conditions
    F. EPA's Conclusion on Arkansas' BART Alternative Determination
for Domtar
    G. Consultation With States and Federal Land Managers
III. Evaluation of Arkansas' Long-Term Strategy Provisions for
Domtar Ashdown Mill
IV. Evaluation of Reasonable Progress Requirements for Domtar
Ashdown Mill
V. Evaluation of Arkansas Visibility Transport
    A. Fully-Approved Regional Haze SIP To Meet Visibility Transport
Requirement
    B. Alternative Demonstration To Meet Visibility Transport
Requirement
    C. EPA's Conclusion on Arkansas Visibility Transport
VI. Evaluation of CAA Section 110(1)
VII. Proposed Action
    A. Arkansas Regional Haze Phase III SIP Submittal
    B. FIP Withdrawal
    C. Arkansas Visibility Transport
    D. CAA Section 110(1)
VIII. Incorporation by Reference
IX. Statutory and Executive Order Reviews

I. Background

A. Regional Haze Principles

    Regional haze is visibility impairment that is produced by a
multitude of sources and activities that are located across a broad
geographic area and emit fine particulates (PM2.5) \1\ into
the air. Fine particulates which cause haze are sulfates
(SO42-), nitrates
(NO3-), organic carbon (OC), elemental carbon
(EC), and soil dust.\2\ PM2.5 precursors consist of
SO2, NOX, volatile organic compounds (VOCs), and
in some cases, ammonia (NH3). Airborne PM2.5 can
scatter and absorb the incident light and, therefore, lead to
atmospheric opacity and horizontal visibility degradation. Regional
haze limits visual distance and reduces color, clarity, and contrast of
view. PM2.5 can cause serious adverse health effects and
mortality in humans. It also contributes to environmental effects such
as acid deposition and eutrophication. Emissions that affect visibility
include a wide variety of natural and man-made sources. Natural sources
can include windblown dust and soot from wildfires. Man-made sources
can include major and minor stationary sources, mobile sources, and
area sources. Reducing PM2.5 and its precursor gases in the
atmosphere is an effective method of improving visibility.
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    \1\ Fine particles are less than or equal to 2.5 microns
([micro]m) in diameter and usually form secondary in nature
indirectly from other sources. Particles less than or equal to 10
[micro]m in diameter are referred to as PM10. Particles
greater than PM2.5 but less than PM10 are
referred to as coarse mass. Coarse mass can contribute to light
extinction as well and is made up of primary particles directly
emitted into the air. Fine particles tend to be man-made, while
coarse particles tend to have a natural origin. Coarse mass settles
out from the air more rapidly than fine particles and usually will
be found relatively close to emission sources. Fine particles can be
transported long distances by wind and can be found in the air
thousands of miles from where they were formed.
    \2\ Organic carbon can be emitted directly as particles or
formed through reactions involving gaseous emissions. Elemental
carbon, in contrast to organic carbon, is exclusively of primary
origin and emitted by the incomplete combustion of carbon-based
fuels. Elemental carbon particles are especially prevalent in diesel
exhaust and smoke from wild and prescribed fires.
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    Data from the existing visibility monitoring network, ``Interagency
Monitoring of Protected Visual Environments'' (IMPROVE), shows that
visibility impairment caused by air pollution occurs virtually all of
the time at most national parks and wilderness areas. In 1999, the
average visual range \3\ in many mandatory Class I Federal areas \4\ in
the western United States was 100-150 kilometers (km), or about one-
half to two-thirds of the visual range that would exist under estimated
natural conditions.\5\ In most of the eastern Class I areas of the
United States, the average visual range was less than 30 km, or about
one-fifth of the visual range that would exist under estimated natural
conditions. Since the promulgation of the original Regional Haze Rule
in 1999, CAA programs have reduced emissions of haze-causing pollution,
lessening visibility impairment and resulting in improved average
visual ranges.\6\
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    \3\ Visual range is the greatest distance, in km or miles, at
which a dark object can be viewed against the sky by a typical
observer.
    \4\ Mandatory Class I Federal areas consist of national parks
exceeding 6,000 acres, wilderness areas and national memorial parks
exceeding 5,000 acres, and all international parks that were in
existence on August 7, 1977. The EPA, in consultation with the
Department of Interior, promulgated a list of 156 areas where
visibility was identified as an important value. The extent of a
mandatory Class I area includes subsequent changes in boundaries,
such as park expansions. Although states and tribes may designate
additional areas as Class I, the requirements of the visibility
program set forth in the CAA applies only to mandatory Class I
Federal areas. Each mandatory Class I Federal area is the
responsibility of a Federal Land Manager (FLM). When the term
``Class I area'' is used in this action, it means ``mandatory Class
I Federal areas.'' See 44 FR 69122 (November 30, 1979) and CAA
Sections 162(a), 169A, and 302(i).
    \5\ 64 FR 35714, 35715 (July 1, 1999).
    \6\ An interactive story map depicting efforts and recent
progress by the EPA and states to improve visibility at national
parks and wilderness areas may be visited at: http://arcg.is/29tAbS3.
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B. Requirements of the CAA and the EPA's Regional Haze Rule

    In section 169A, enacted as part of the 1977 CAA Amendments,
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, visibility impairment in mandatory Class I
Federal areas where impairment results from manmade air pollution.
Congress added section 169B to the CAA in 1990 that added visibility
protection provisions, and the EPA promulgated final regulations
addressing regional haze as part of the 1999 Regional Haze Rule, which
was most recently updated in 2017.\7\ The Regional Haze Rule revised
the existing 1980 visibility regulations and established a more
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 the EPA's broader visibility protection regulations at 40
CFR 51.300-309. The regional haze regulations require states to
demonstrate reasonable progress toward meeting the national goal of a
return to natural visibility conditions for Class I areas by 2064. The
CAA requirement in section 169A(b)(2) to submit a regional haze SIP
applies to all fifty states, the District of Columbia, and the Virgin
Islands. States were required to submit the first implementation plan
addressing visibility impairment caused by regional haze no later than
December 17, 2007.\8\
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    \7\ See the July 1, 1999 Regional Haze Rule final action (64 FR
35714), as amended on July 6, 2005 (70 FR 39156), October 13, 2006
(71 FR 60631), June 7, 2012 (77 FR 33656) and on January 10, 2017
(82 FR 3079).
    \8\ See 40 CFR 51.308(b). Also, under 40 CFR 51.308(f)-(i), the
EPA requires subsequent updates to the regional haze SIPs for each
implementation period. The next update for the second implementation
period is due by July 31, 2021.

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C. BART Requirements

    Section 169A(b)(2)(A) of the CAA directs states to evaluate the use
of BART controls at certain categories of existing major stationary
sources built between 1962 and 1977.\9\ Under 40 CFR 51.308(e)(1)(ii),
any BART-eligible source \10\ that is reasonably anticipated to cause
or contribute to visibility impairment in a Class I area is classified
as subject-to-BART.\11\ States are directed to conduct BART
determinations for each source classified as subject-to-BART. These
large, often under-controlled, older stationary sources are required to
procure, install, and operate BART controls to address visibility
impacts. The determination must be based on an analysis of the best
system of continuous emission control technology available and
associated emission reductions achievable. States are required to
identify the level of control representing BART after considering the
five statutory factors set out in CAA section 169A(g)(2).\12\ States
must establish emission limits, a schedule of compliance, and other
measures consistent with the BART determination process for each source
subject-to-BART.
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    \9\ See 42 U.S.C. 7491(g)(7), which lists the 26 source
categories of major stationary sources potentially subject-to-BART.
    \10\ BART-eligible sources are those sources that fall within
one of 26 source categories that began operation on or after August
7, 1962, and were in existence on August 7, 1977, with potential
emissions greater than 250 tons per year (tpy). (See 40 CFR 51
Appendix Y, section II).
    \11\ Under the BART Guidelines, states may select a visibility
impact threshold, measured in deciviews (dv), 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 threshold in the SIP and specify the basis for its selection of
that value. Any source with visibility impacts 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 visibility impact
threshold set by the state should not be higher than 0.5 dv. (See 40
CFR part 51, Appendix Y, section III.A.1).
    \12\ The State must take into consideration the five statutory
factors: (1) Costs of compliance, (2) the energy and non-air quality
environmental impacts, (3) any existing control technology present
at the source, (4) the remaining useful life of the source, and (5)
the degree of visibility improvement.
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D. BART Alternative Requirements

    A State may opt to implement or require participation in an
emissions trading program or other alternative measure rather than
require sources subject-to-BART to install, operate, and maintain BART.
Such an emissions trading program or other alternative measure must
achieve greater reasonable progress than would be achieved through the
installation and operation of BART. 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) to (iv).\13\ The state must
conduct 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.
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    \13\ 40 CFR 51.308(e)(2)(ii) is reserved. Under 40 CFR
51.308(e)(2)(v), ``At the State's option, a provision that the
emissions trading program or other alternative measure may include a
geographic enhancement to the program to address the requirement
under 40 CFR 51.302(b) or (c) related to reasonably attributable
impairment from the pollutants covered under the emissions trading
program or other alternative measure.''
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    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 ``clear
weight of evidence'' that the alternative measure achieves greater
reasonable progress than BART. 40 CFR 51.308(e)(3) provides two
specific tests applicable under specific circumstances for determining
whether the alternative measure achieves greater reasonable progress
than BART. Under the first test, if the distribution of emissions is
not substantially different than under BART, and the alternative
measure results in greater emission reductions, then the alternative
measure may be deemed to achieve greater reasonable progress. Under the
second test, if the distribution of emissions is significantly
different, then the State must conduct dispersion modeling to determine
the difference in visibility between BART and the alternative measure
for each impacted Class I area, for the twenty percent best and worst
days. The modeling would demonstrate greater reasonable progress if
both of the following two criteria are met: (i) Visibility does not
decline in any Class I area, and (ii) there is an overall improvement
in visibility, determined by comparing the average difference between
BART and the alternative over all affected Class I areas.
    Alternatively, under 40 CFR 51.308(e)(2)(i)(E), states may show
based on ``clear weight of evidence'' that the alternative achieves
greater reasonable progress than would be achieved through the
installation and operation of BART at the covered sources. As stated in
the EPA's revisions to the Regional Haze Rule governing alternatives to
source-specific BART determinations, weight of evidence demonstrations
attempt to make use of all available information and data which can
inform a decision while recognizing the relative strengths and
weaknesses of that information in arriving at the soundest decision
possible.\14\ This array of information and other relevant data must be
of sufficient quality to inform the comparison of visibility impacts
between BART and the alternative. A weight of evidence comparison may
be warranted when there is confidence that the difference in visibility
impacts between BART and the alternative scenarios are expected to be
large enough to show that an alternative is better than BART. The EPA
will carefully consider this evidence in evaluating any SIPs submitted
by States employing such an approach.
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    \14\ See 71 FR 60612, 60622 (October 13, 2006). 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 alternative 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 alternative as compared to BART sources;
monitoring data and emissions inventories; and sensitivity analyses
of any models used.
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    Finally, under 40 CFR 51.308(e)(2)(iii) and (iv), all emission
reductions for the alternative program must take place during the
period of the first long-term strategy for regional haze, 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. These
requirements are discussed in more detail in subsequent sections of
this proposed action.

E. Long-Term Strategy and Reasonable Progress Requirements

    In addition to BART requirements, 40 CFR 51.308(d)(3)(i to iv)
requires each state to include in its SIP a long-term strategy for the
planning period that addresses regional haze visibility impairment for
each Class I area located within the state and outside the state that
may be affected by emissions generated from within the state. The long-
term strategy is the vehicle for ensuring continuing reasonable
progress toward achieving natural visibility conditions. It is a
compilation of all control measures in the SIP that a state will use
during the implementation period to meet the applicable reasonable
progress goals (RPGs) established under 40 CFR 51.308(d)(1) for each
Class I area.\15\ The RPGs established by the

State provide an assessment of the visibility improvement anticipated
to result for that planning period.\16\ Section 51.308(d)(3)(v)
requires that a state consider certain minimum factors (the long-term
strategy factors) in developing its long-term strategy for each Class I
area.\17\ States have significant flexibility in establishing RPGs but
must determine whether additional measures beyond BART and other
controls are needed for reasonable progress during the first planning
period based on a consideration of the following four reasonable
progress factors set out in section 169A(g)(1) of the CAA: (1) The
costs of compliance; (2) the time necessary for compliance; (3) the
energy and non-air quality environmental impacts of compliance; and (4)
the remaining useful life of any potentially affected sources.\18\
States must demonstrate in their regional haze SIPs how these factors
are considered when selecting their long-term strategies and associated
RPGs for each applicable Class I area. We commonly refer to this as the
``reasonable progress analysis'' or ``four-factor analysis.''
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    \15\ See 40 CFR 51.308(d)(3)(i to iv). For the first planning
period, contributing and impacted states must develop coordinated
emission management strategies. Impacted states must demonstrate
that they have included all measures necessary in their SIPs to
obtain their share of emission reductions needed to meet the RPGs
for a Class I area. States must document the technical basis that
they relied upon to determine the apportionment of emission
reduction obligations necessary and identify the baseline emissions
inventory on which their strategies are based. States must also
identify all anthropogenic sources of visibility impairment
considered in developing the strategy, such as major and minor
stationary sources, mobile sources, and area sources.
    \16\ The process for setting RPGs is as follows: (1) Identify
sources that impact visibility; (2) evaluate potential controls
based on consideration of the four reasonable progress factors; (3)
project the visibility conditions based on implementation of on-the-
books and additional selected controls; (4) compare the projected
visibility conditions to the uniform rate of progress (URP) needed
to attain natural visibility conditions by year 2064 for each Class
I area; (5) determine an RPG for each Class I area based on this
analysis that will improve the visibility at or beyond the URP on
the most impaired days and ensure no degradation for the least
impaired days. The Regional Haze Rule allows for the selection of an
RPG at a given Class I area that provides for a slower rate of
improvement than the URP for that area, but in that case a state
must demonstrate that the URP is not reasonable and that the RPG
selected is. (see 40 CFR 51.308(d)(1)(ii).
    \17\ These factors are: (1) Emission reductions due to ongoing
air pollution control programs, including measures to address
reasonably attributable visibility impairment (RAVI); (2) measures
to mitigate the impacts of construction activities; (3) emissions
limitations and schedules for compliance to achieve the reasonable
progress goal; (4) source retirement and replacement schedules; (5)
smoke management techniques for agricultural and forestry management
purposes including plans as currently exist within the state for
these purposes; (6) enforceability of emissions limitations and
control measures; and (7) the anticipated net effect on visibility
due to projected changes in point, area, and mobile source emissions
over the period addressed by the long-term strategy.
    \18\ Guidance for Setting Reasonable Progress Goals under the
Regional Haze Program, June 1, 2007, memorandum from William L.
Wehrum, Acting Assistant Administrator for Air and Radiation, to the
EPA Regional Administrators, EPA Regions 1-10 (pp.4-2, 5-1).
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F. Previous Actions on Arkansas Regional Haze

    The State of Arkansas submitted a regional haze SIP on September 9,
2008, intended to address the requirements of the first regional haze
implementation period. On August 3, 2010, the State submitted a SIP
revision with mostly non-substantive changes that addressed Arkansas
Pollution Control and Ecology Commission (APCEC) Regulation 19, Chapter
15.\19\ On September 27, 2011, the State submitted a supplemental
letter that clarified several aspects of the 2008 submittal. The EPA
collectively refers to the original 2008 submittal, the supplemental
letter, and the 2010 revision together as the 2008 Arkansas Regional
Haze SIP. On March 12, 2012, the EPA partially approved and partially
disapproved the 2008 Arkansas Regional Haze SIP.\20\ Specifically, the
EPA disapproved certain BART compliance dates; the State's
identification of certain BART-eligible sources and subject-to-BART
sources; certain BART determinations for NOX,
SO2, and PM10; the State's reasonable progress
analysis; and a portion of the State's long-term strategy. The
remaining provisions of the 2008 Arkansas Regional Haze SIP were
approved. The final partial disapproval started a two-year FIP clock
that obligated the EPA to either approve a SIP revision and/or
promulgate a FIP to address the disapproved portions of the action.\21\
Because a SIP revision addressing the deficiencies was not approved and
the FIP clock expired in April 2014, the EPA promulgated a FIP (the
Arkansas Regional Haze FIP) on September 27, 2016, to address the
disapproved portions of the 2008 Arkansas Regional Haze SIP.\22\ Among
other things, the FIP established SO2, NOX, and
PM10 emission limits under the BART requirements for nine
units at six facilities: Arkansas Electric Cooperative Corporation
(AECC) Carl E. Bailey Plant Unit 1 Boiler; AECC John L. McClellan Plant
Unit 1 Boiler; American Electric Power/Southwestern Electric Power
Company (AEP/SWEPCO) Flint Creek Plant Boiler No. 1; Entergy \23\ Lake
Catherine Plant Unit 4 Boiler; Entergy White Bluff Plant Units 1 and 2
Boilers and the Auxiliary Boiler; and the Domtar Ashdown Mill Power
Boilers No. 1 and 2. The FIP also established SO2 and
NOX emission limits under the reasonable progress
requirements for the Entergy Independence Plant Units 1 and 2.
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    \19\ The September 9, 2008 SIP submittal included APCEC
Regulation 19, Chapter 15, which is the state regulation that
identified the BART-eligible and subject-to-BART sources in Arkansas
and established BART emission limits for subject-to-BART sources.
The August 3, 2010 SIP revision did not revise Arkansas' list of
BART-eligible and subject-to-BART sources or revise any of the BART
requirements for affected sources. Instead, it included mostly non-
substantive revisions to the state regulation.
    \20\ See the final action on (March 12, 2012) (77 FR 14604).
    \21\ Under CAA section 110(c), the EPA is required to promulgate
a FIP within two years of the effective date of a finding that a
state has failed to make a required SIP submission or has made an
incomplete submission, or of the effective date that the EPA
disapproves a SIP in whole or in part. The FIP requirement is
terminated only if a state submits a SIP, and the EPA approves that
SIP as meeting applicable CAA requirements before promulgating a
FIP.
    \22\ See FIP final action on September 27,2016 (81 FR 66332) as
corrected on October 4, 2016 (81 FR 68319).
    \23\ ``Entergy'' collectively means Entergy Arkansas Inc.,
Entergy Mississippi Inc., and Entergy Power LLC.
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    Following petitions for reconsideration \24\ submitted by the
State, industry, and ratepayers, on April 25, 2017, the EPA issued a
partial administrative stay of the effectiveness of the FIP for ninety
days.\25\ During that period, Arkansas started to address the
disapproved portions of its regional haze SIP through several phases of
SIP revisions. On July 12, 2017, the State submitted its proposed Phase
I SIP submittal (the Arkansas Regional Haze NOX SIP
revision) to address NOX BART requirements for all electric
generating units (EGUs) and the reasonable progress requirements with
respect to NOX. These NOX provisions were
previously disapproved by the EPA in our 2012 final action on the 2008
Arkansas Regional Haze SIP. The Arkansas Regional Haze NOX
SIP submittal replaced all source-specific NOX BART
determinations for EGUs established in the FIP with reliance upon the
Cross-State Air Pollution Rule (CSAPR) emissions trading program for
O3 season NOX as an alternative to NOX
BART. The SIP submittal addressed the NOX BART requirements
for Bailey Unit 1, McClellan Unit 1, Flint Creek Boiler No. 1, Lake
Catherine Unit 4; White Bluff Units 1 and 2, and the Auxiliary Boiler.
The revision did not address NOX BART for Domtar Ashdown
Mill Power Boilers No. 1 and 2. On February 12, 2018, we took final
action to approve the Arkansas Regional Haze

NOX SIP revision and to withdraw the corresponding
NOX provisions of the FIP.\26\
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    \24\ Copies of the petitions for reconsideration and
administrative stay submitted by the State of Arkansas; Entergy;
Arkansas Electric Cooperative Corporation (AECC); and the Energy and
Environmental Alliance of Arkansas (EEAA) are available in the
docket of this action.
    \25\ See 82 FR 18994.
    \26\ See 82 FR 42627 (September 11, 2017) for the proposed
approval. See also 83 FR 5915 and 83 FR 5927 (February 12, 2018) for
the final action.
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    The State submitted its Phase II SIP revision (the Arkansas
Regional Haze SO2 and PM SIP revision) on August 8, 2018,
that addressed most of the remaining parts of the 2008 Arkansas
Regional Haze SIP that were disapproved in the March 12, 2012, action.
The August 8, 2018, SIP submittal was intended to replace the federal
SO2 and PM10 BART determinations as well as the
reasonable progress determinations established in the FIP with the
State's own determinations. Specifically, the SIP revision addressed
the applicable SO2 and PM10 BART requirements for
Bailey Unit 1; SO2 and PM10 BART requirements for
McClellan Unit 1; SO2 BART requirements for Flint Creek
Boiler No. 1; SO2 BART requirements for White Bluff Units 1
and 2; SO2, NOX, and PM10 BART
requirements for the White Bluff Auxiliary Boiler; \27\ and included a
requirement that Lake Catherine Unit 4 not burn fuel oil until
SO2 and PM BART determinations for the fuel oil firing
scenario are approved into the SIP by the EPA.\28\ The submittal
addressed the reasonable progress requirements with respect to
SO2 and PM10 emissions for Independence Units 1
and 2 and all other sources in Arkansas. In addition, it established
revised RPGs for Arkansas' two Class I areas and revised the State's
long-term strategy provisions. The submittal did not address BART and
associated long-term strategy requirements for Domtar Ashdown Mill
Power Boilers No. 1 and 2, but they are addressed in this proposed
action. On September 27, 2019, we took final action to approve a
portion of the Arkansas Regional Haze SO2 and PM SIP
revision and to withdraw the corresponding parts of the FIP.\29\ The
August 8, 2018, SIP also contained a discussion of the interstate
visibility transport provisions, as discussed in more detail in Section
I.H.
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    \27\ The Arkansas Regional Haze SO2 and PM SIP
revision established a new NOX emission limit of 32.2
pounds per hour (pph) for the Auxiliary Boiler to satisfy
NOX BART and replaced the SIP determination that we
previously approved in our final action on the Arkansas Regional
Haze NOX SIP revision. In the Arkansas Regional Haze
NOX SIP revision, ADEQ incorrectly identified the
Auxiliary Boiler as participating in the CSAPR trading program for
O3 season NOX to satisfy the NOX
BART requirements. The new source-specific NOX BART
emission limit that we approved in our final action on the Arkansas
Regional Haze SO2 and PM SIP revision corrected that
error.
    \28\ The 2012 action disapproved SO2, NOX,
and PM BART for the fuel oil firing scenario for the Entergy Lake
Catherine Plant Unit 4, but a FIP BART determination was not
established. Instead, the FIP included a requirement that Entergy
not burn fuel oil at Lake Catherine Unit 4 until final EPA approval
of BART determinations for SO2, NOX, and PM.
In the Arkansas Regional Haze NOX SIP revision, Arkansas
relied on participation in CSAPR for O3 season
NOX to satisfy the NOX BART requirement for
its subject-to-BART EGUs, including Lake Catherine Unit 4. When we
took final action on the Arkansas Regional Haze NOX SIP
revision, we also took final action to withdraw the FIP
NOX emission limit for the natural gas firing scenario
for Lake Catherine Unit 4. In the Arkansas Regional Haze
SO2 and PM SIP revision, Entergy committed to not burn
fuel oil at Lake Catherine Unit 4 until final EPA approval of BART
for SO2 and PM. This commitment was made enforceable by
the State through an Administrative Order that was adopted and
incorporated in the Arkansas Regional Haze SO2 and PM SIP
revision.
    \29\ See 83 FR 62204 (November 30, 2018) for proposed approval
and 84 FR 51033 (September 27, 2019) for final approval. The
Arkansas Regional Haze SO2 and PM SIP revision also
addressed separate CAA requirements related to interstate visibility
transport under CAA section 110(a)(2)(D)(i)(II), but we did not take
action on that part of the submittal. We are incorporating by
reference the visibility transport portion of the Arkansas Regional
Haze SO2 and PM SIP revision in this proposed action.
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G. Arkansas Regional Haze Phase III SIP Submittal

    On August 13, 2019, ADEQ submitted the Arkansas Regional Haze Phase
III SIP (Phase III SIP revision) which we are proposing to approve in
this action. The submittal contains a BART alternative measure to
address BART and the associated long-term strategy requirements for two
subject-to-BART sources (Power Boilers No. 1 and 2) at the Domtar
Ashdown paper mill located in Ashdown, Arkansas. Power Boiler No. 1 was
first installed in 1967-1968 and is currently permitted to burn only
natural gas.\30\ It is capable of burning a variety of other fuels too
including bark, wood waste, tire-derived fuel (TDF), municipal yard
waste, pelletized paper fuel, fuel-oil, and reprocessed fuel-oil but is
not authorized to do so. It is equipped with a wet electrostatic
precipitator (WESP) \31\ but the requirements to operate the WESP were
removed since it is permitted to combust natural gas only. Power Boiler
No. 1 has a design heat input rating of 580 million British Thermal
units per hour (MMBtu/hr) and an average steam generation rate of
approximately 120,000 pounds per hour (pph). Power Boiler No. 2 was
installed in 1975 and is authorized to burn a variety of fuels
including coal, petroleum coke, TDF, natural gas, wood waste, clean
cellulosic biomass (e.g. bark, wood residuals, and other woody biomass
materials), bark, and wood chips used to absorb oil spills. It is
equipped with a traveling grate; \32\ a combustion air system that
includes over-fire air; \33\ multi-clones for PM10 removal;
\34\ and two venturi scrubbers in parallel for removal of
SO2 and remaining particulates. Power Boiler No. 2 has a
heat input rating of 820 MMBtu/hr and an average steam generation rate
of approximately 600,000 pph.
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    \30\ Power Boiler No. 1 operates as natural gas only subject to
the Gas 1 subcategory defined under 40 CFR 63.7575. See ADEQ Air
Permit No. 0287-AOP-R22 (page 64) in the docket of this action.
    \31\ An electrostatic precipitator is an air pollution control
device that functions by electrostatically charging particles in a
gas stream that passes through collection plates with wires. The
ionized particulate matter is attracted to and deposited on the
plates as the cleaner air passes through. A wet electrostatic
precipitator is designed to operate with water vapor saturated air
streams to remove liquid droplets such as sulfuric acid.
    \32\ A traveling grate is a moving grate used to feed fuel to
the boiler for combustion.
    \33\ Over-fire air typically recirculates a portion of the flue
gas back to both the fuel-rich zone and the combustion zone to
achieve complete burnout by encouraging the formation of nitrogen
(N2) rather than NOX.
    \34\ A cyclone separator is an air pollution control device
shaped like a conical tube that creates an air vortex as air moves
through it causing larger particles (PM10) to settle as
the cleaner air passes through. Multi-clones are a sequence of
cyclone separators in parallel used to treat a higher volume of air.
In this particular case, the cleaner air travels to the venturi
scrubbers to remove the smaller remaining particles like
PM2.5 and SO2.
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    ADEQ's original BART analyses and determinations (dated October
2006 and March 2007) for Power Boilers No. 1 and 2 were included in the
2008 Arkansas Regional Haze SIP.\35\ In our 2012 action, we approved
ADEQ's identification of these two units as BART-eligible; ADEQ's
determination that these units are subject-to-BART; and ADEQ's
PM10 BART determination for Power Boiler No. 1.\36\ In that
action, we also disapproved the SO2 and NOX BART
determinations for Power Boiler No. 1; and the SO2,
NOX, and PM10 BART determinations for Power
Boiler No. 2. In the 2016 Arkansas Regional Haze FIP and its associated
technical support document (TSD),\37\ the EPA promulgated
SO2, NOX, and PM10 emission limits for
these boilers. The FIP BART limits were based on

consideration of the 2006 and 2007 BART analyses, a revised BART
analysis (dated May 2014),\38\ and additional information provided by
Domtar for the disapproved BART determinations. On March 20, 2018,
Domtar provided ADEQ with a proposed BART alternative based on changing
boiler operations as part of the company's planned re-purposing and
mill transformation from paper production to fluff pulp production. On
September 5, 2018, Domtar further revised its BART alternative approach
in response to additional boiler operation changes planned at the
Ashdown Mill.\39\ In October 2018, ADEQ proposed a SIP revision that
included Domtar's BART alternative approach to address the BART
requirements for Power Boilers 1 and 2 at the Ashdown Mill.\40\
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    \35\ See ``Best Available Retrofit Technology Determination
Domtar Industries Inc., Ashdown Mill (AFIN 41-00002),'' originally
dated October 31, 2006 and revised on March 26, 2007, prepared by
Trinity Consultants Inc. This was included as part of the Phase III
submittal and included in the docket of this action.
    \36\ See the March 12, 2012 final action (77 FR 14604).
    \37\ See final FIP action on September 27, 2016 (81 FR 66332) as
corrected on October 4, 2016 (81 FR 68319) and the associated TSD,
``AR020.0002-00 TSD for EPA's Proposed Action on the Arkansas
Regional Haze FIP'' in Docket No. EPA-R06-OAR-2015-0189 for the FIP
BART analysis for SO2 and NOX for Power Boiler
No. 1; and SO2, NOX, and PM10 for
Power Boiler No. 2. This was included as part of the Phase III
submittal and included in the docket of this action.
    \38\ See ``Supplemental BART Determination Information Domtar
A.W. LLC, Ashdown Mill (AFIN 41-00002),'' originally dated June 28,
2013 and revised on May 16, 2014, prepared by Trinity Consultants
Inc. in conjunction with Domtar A.W. LLC. This was included as part
of the Phase III SIP submittal and is included in the docket of this
action.
    \39\ See section III.B of the Arkansas Regional Haze Phase III
submittal and the associated September 4, 2018, ``Ashdown Mill BART
Alternative TSD'' in the docket of this action.
    \40\ The proposed October 2018 SIP revision was intended to
replace the portion of our FIP addressing Domtar and would also
resolve the claims regarding Domtar in petitions for review of the
FIP that are currently being held in abeyance, State of Arkansas v.
EPA, No. 16-4270 (8th Cir.).
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    The October 2018 proposal included an administrative order as the
enforceable mechanism for the emission limits established under the
BART alternative; and the order also contained monitoring, reporting,
and recordkeeping requirements for the boilers. During the State's
public comment period, Domtar submitted comments stating that while it
agrees with the BART alternative approach and with the emission limits
themselves, it does not agree with the use of the administrative order
as the enforceable mechanism of the proposed SIP revision. Domtar
requested that the portion of its New Source Review (NSR) permit
containing the regional haze requirements be included in the proposed
SIP revision as the enforceable mechanism instead of the administrative
order. ADEQ addressed Domtar's request in April 2019 by proposing a
supplemental SIP revision to the October 2018 proposal. The
supplemental SIP revision proposal replaced the administrative order
with the incorporation of certain provisions of Domtar's revised NSR
permit into the SIP as the enforceable mechanism for Domtar's regional
haze requirements. On August 1, 2019, the ADEQ issued a final minor
permit modification letter to Domtar,\41\ which included enforceable
emission limitations and compliance schedules for the BART alternative.
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    \41\ See ADEQ Air permit #0287-AOP-R22 (effective August 1,
2019) included as part of the Phase III submittal and is included in
the docket of this action.
---------------------------------------------------------------------------

    ADEQ submitted its third corrective regional haze SIP submittal to
the EPA on August 13, 2019, which is the subject of this proposed
rulemaking (the Arkansas Regional Haze Phase III SIP revision). The
Phase III SIP revision includes Domtar's BART alternative approach and
revises all of the prior BART determinations for Power Boilers No. 1
and 2 at the Ashdown Mill. The Phase III SIP submittal also
incorporates plantwide provisions from the August 1, 2019, permit
including emission limits and conditions for implementing the BART
alternative.\42\ If the EPA takes final action to approve the Arkansas
Regional Haze Phase III SIP revision, ADEQ will have a fully-approved
regional haze SIP for the first implementation period. The Arkansas
Regional Haze NOX SIP revision,\43\ the Arkansas Regional
Haze SO2 and PM SIP revision,\44\ and the Arkansas Regional
Haze Phase III SIP revision (if approved by EPA) will together fully
address all deficiencies of the 2008 Arkansas Regional Haze SIP that
EPA previously identified in the March 12, 2012 partial approval/
disapproval action.\45\
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    \42\ See ADEQ Air permit #0287-AOP-R22, Section VI, Plantwide
Conditions #32 to #43. The ``Regional Haze Program (BART
Alternative) Specific Conditions'' portion of the Plantwide
Conditions section of the permit states the following: ``For
compliance with the CAA Regional Haze Program's requirements for the
first planning period, the No. 1 and 2 Power Boilers are subject-to-
BART alternative measures consistent with 40 CFR 51.308. The terms
and conditions of the BART alternative measures are to be submitted
to EPA for approval as part of the Arkansas SIP. Upon initial EPA
approval of the permit into the SIP, the permittee shall continue to
be subject to the conditions as approved into the SIP even if the
conditions are revised as part of a permit amendment until such time
as the EPA approves any revised conditions into the SIP. The
permittee shall remain subject to both the initial SIP-approved
conditions and the revised conditions, until EPA approves the
revised conditions.''
    \43\ See final action approved on February 12, 2018 (83 FR
5927).
    \44\ See final action approved on September 27, 2019 (84 FR
51033) and the proposed approval on November 30, 2018 (83 FR 62204).
    \45\ The proposed approval of the Arkansas Regional Haze Phase
III SIP submittal is not proposing to revise the Arkansas Regional
Haze Phase I or II SIP revisions.
---------------------------------------------------------------------------

H. Arkansas Visibility Transport

    Sections 110(a)(1) and (2) of the CAA direct each state to develop
and submit to the EPA a SIP that provides for the implementation,
maintenance, and enforcement of a new or revised NAAQS.\46\ This type
of SIP submission is referred to as an infrastructure SIP. Section
110(a)(1) provides the timing and procedural requirements for
infrastructure SIPs. Specifically, each state is required to make a new
SIP submission within three years after promulgation of a new or
revised primary or secondary NAAQS. Section 110(a)(2) lists the
substantive elements that states must address for infrastructure SIPs
to be approved by the EPA. Section 110(a)(2)(D)(i) includes four
distinct elements related to interstate transport of air pollution,
commonly referred to as prongs, that must be addressed in
infrastructure SIP submissions. The first two prongs are codified in
section 110(a)(2)(D)(i)(I) and the third and fourth prongs are codified
in section 110(a)(2)(D)(i)(II). These four prongs prohibit any source
or type of emission activities in one state from:
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    \46\ See the final rules promulgating the NAAQS requirements: 71
FR 61144 (October 17, 2006); 77 FR 50033 (August 20, 2012); 80 FR
11573 (March 4, 2015); 80 FR 38419 (July 6, 2015); 78 FR 53269
(August 29, 2013); 73 FR 16436 (March 27, 2008). 81 FR 74504
(October 26, 2016); 75 FR 35520 (June 22, 2010); 75 FR 6474
(February 9, 2010); and 78 FR 3086 (January 15, 2013).
---------------------------------------------------------------------------

     Contributing significantly to nonattainment of the NAAQS
in another state (prong 1);
     interfering with maintenance of the NAAQS in another state
(prong 2);
     interfering with measures that prevent significant
deterioration of air quality in another state (prong 3); and
     interfering with measures that protect visibility in
another state (prong 4 or ``visibility transport'').
    We are only addressing the prong 4 element in this proposed action.
The Prong 4 element is consistent with the requirements in the regional
haze program, which explicitly require each state to address its share
of emission reductions needed to meet the RPGs for surrounding Class I
areas. The EPA most recently issued guidance that addressed prong 4 on
September 13, 2013.\47\ The 2013 guidance indicates that a state can
satisfy prong 4 requirements with a fully-approved regional haze SIP
that meets 40 CFR 51.308 or 309. Alternatively, in the absence of a
fully-approved regional haze SIP, a state may meet the prong 4
requirements through a demonstration showing that emissions within its
jurisdiction do not interfere with another air agency's plans to
protect visibility. Lastly, the guidance states that prong 4 is
pollutant-specific, so infrastructure SIPs only need to

address the particular pollutant (including precursors) for which there
is a new or revised NAAQS for which the SIP is being submitted that is
interfering with visibility protection.
---------------------------------------------------------------------------

    \47\ See ``Guidance on Infrastructure State Implementation Plan
(SIP) Elements under CAA sections 110(a)(1) and 110(a)(2)'' by
Stephen D. Page (Sept. 13, 2013), (pages 32-35).
---------------------------------------------------------------------------

    On March 24, 2017, the State submitted a SIP revision that
addressed all four infrastructure prongs from section 110(a)(2)(D)(i)
for the 2008 lead (Pb) NAAQS, the 2006 and 2012 PM2.5 NAAQS,
the 2008 O3 NAAQS, the 2010 SO2 NAAQS, and the
2010 NO2 NAAQS. We deferred taking action on the
110(a)(2)(D)(i)(II) prong 4 portion of that infrastructure SIP for a
future rulemaking with the exception of the 2008 Pb NAAQS.\48\ On
August 10, 2018, the State also included a discussion on visibility
transport in its Phase II Arkansas Regional Haze SO2 and PM
SIP revision, but we deferred proposing action on the visibility
transport requirements in that submittal too.\49\ In the Phase II SIP
revision, ADEQ concluded that Missouri is on track to achieve its
visibility goals; that observed visibility progress from Arkansas
sources are not interfering with Missouri's RPG achievements for
Hercules-Glades Wilderness and Mingo National Wildlife Refuge; and that
no additional controls on Arkansas sources are necessary to ensure that
other states' Class I areas meet their visibility goals for the first
planning period. On October 4, 2019, the State submitted the Arkansas
2015 O3 NAAQS Interstate Transport SIP revision to meet the
requirements of CAA section 110(a)(2)(D) regarding interstate transport
for the 2015 O3 NAAQS. In that SIP submittal, Arkansas also
addressed the 2006 and 2012 PM2.5 NAAQS, the 2008
O3 NAAQS, the 2010 SO2 NAAQS, and the 2010
NO2 NAAQS prong 4 visibility transport obligations in
110(a)(2)(D)(i)(II), and we are proposing to approve those prong 4
requirements in this action. The State's prong 4 visibility transport
analysis in the October 4, 2019 submittal supersedes the prong 4
visibility transport portion of the March 24, 2017, infrastructure SIP
submittal and supplements the August 10, 2018, Phase II Arkansas
Regional Haze SO2 and PM SIP revision \50\ for the 2006 and
2012 PM2.5 NAAQS, the 2008 and 2015 O3 NAAQS, the
2010 SO2 NAAQS, and the 2010 NO2 NAAQS. All other
applicable infrastructure SIP requirements in the October 4, 2019, SIP
submission have been or will be addressed in separate rulemakings.
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    \48\ The EPA approved the visibility transport requirement for
the 2008 Pb NAAQS only in the February 2018 final action effective
March 16, 2018 (see 83 FR 6470).
    \49\ See 84 FR 51033, 51054 (September 27, 2019).
    \50\ See 83 FR 62204 (November 30, 2018) for proposed approval
and 84 FR 51033 (September 27, 2019) for final action. The Arkansas
Regional Haze SO2 and PM SIP revision addressed separate
CAA requirements related to interstate visibility transport under
CAA section 110(a)(2)(D)(i)(II), but we did not take action on that
part of the submittal. We are incorporating by reference the prong 4
portion of the Arkansas Regional Haze SO2 and PM SIP
revision in this proposed action.
---------------------------------------------------------------------------

II. Evaluation of the Arkansas Regional Haze Phase III SIP Submittal

    On August 13, 2019, the EPA received a SIP revision (The Arkansas
Regional Haze Phase III SIP), which we are proposing to approve in this
action. The submittal contains a BART alternative measure pursuant to
40 CFR 51.308(e)(2) for Domtar Ashdown Mill's Power Boilers No. 1 and
2.\51\ ADEQ submitted this SIP revision to address the remaining
deficiencies identified by the EPA in the March 12, 2012 previous
partial approval/disapproval action on the 2008 Arkansas Regional Haze
SIP revision. The SIP revision establishes an alternative to BART for
SO2, NOX, and PM10 for Power Boilers
No. 1 and No. 2; and replaces all of the prior SIP-approved and FIP
BART determinations for those units. Specifically, it replaces the SIP-
approved PM10 BART determination \52\ for Power Boiler No.
1; the SO2 and NOX FIP BART determinations for
Power Boiler No. 1; and the SO2, NOX, and
PM10 FIP BART determinations for Power Boiler No. 2. The
Phase III SIP revision includes the State's assessment of Domtar's BART
alternative, including analysis of the modeled visibility impacts
across four-affected Class I areas in Arkansas and Missouri: Caney
Creek Wilderness, Upper Buffalo Wilderness, Hercules-Glades Wilderness,
and Mingo National Wildlife Refuge.\53\ The BART alternative analysis
is based on a demonstration that the clear weight of evidence of the
alternative will result in greater reasonable progress than the FIP
BART limits. We agree with the State's assessment and propose to
approve the Arkansas Regional Haze Phase III SIP revision on the basis
that it satisfies the requirements of 40 CFR 51.308(e)(2) as explained
in further detail in each subsequent section. We also propose to
withdraw the FIP provisions concerning BART for the Domtar power
boilers, as they will be replaced by our approval of the State's BART
alternative. In addition, we propose to approve additional requirements
that rely on the Domtar BART alternative measure. These include the
State's revisions to its long-term strategy and the components of the
State's reasonable progress determination for Arkansas' Class I areas
(discussed in sections III and IV). We also propose to approve the
interstate visibility transport requirements under CAA section
110(a)(2)(D)(i)(II) for pollutants that affect visibility in Class I
areas in nearby states. Our evaluation of the interstate visibility
transport requirements pertaining to a portion of the August 10, 2018,
Phase II Arkansas Regional Haze SO2 and PM SIP, as
supplemented by the Arkansas 2015 O3 NAAQS Interstate
Transport SIP revision (submitted on October 4, 2019) is discussed in
section V.
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    \51\ Previously, on March 20, 2018, Domtar provided to ADEQ a
proposed BART alternative based on boiler operational changes, fuel
switching and repurposing of Ashdown Mill to produce fluff paper. On
September 5, 2018, Domtar proposed to ADEQ a revised BART
alternative with new emission limits and modeling that would
accommodate potential further changes in operation at the Ashdown
Mill and it is included with this SIP submittal. See the associated
September 4, 2018 TSD, ``Ashdown Mill BART Alternative TSD'' in the
docket of this action in Docket No. EPA-R06-OAR-2015-0189.
    \52\ See the final action on March 12, 2012 (77 FR 14604).
    \53\ Arkansas has two Class I areas within its borders: Upper
Buffalo and Caney Creek Wilderness areas. Upper Buffalo Wilderness
area, located in Newton County, Arkansas, is an oak-hickory forest
with intermittent portions of shortleaf pine located in the Ozark
National Forest and offers 12,108 acres of boulder strewn and rugged
scenery along the Buffalo River. Caney Creek Wilderness is located
in Polk County, Arkansas, and covers 14,460 acres on the southern
edge of the Ouachita National Forest and protects a rugged portion
of the Ouachita Mountains. Two Class I areas outside Arkansas'
borders at Hercules-Glades Wilderness and Mingo National Wildlife
Refuge in Missouri are impacted by emissions from within Arkansas.
---------------------------------------------------------------------------

A. Summary of Arkansas' BART Alternative for Domtar Ashdown Mill

    The State's BART alternative operating conditions and emission
rates

are summarized in Table 1.\54\ Under the BART alternative, Power Boiler
No. 1 operates at maximum permitted emission rates consistent with the
combustion of natural gas.\55\ The emission rates for Power Boiler No.
2 were adjusted downward from their previous permitted emission rates
of 984 pph SO2 and 574 pph NOX (44 and 51
percent, respectively, of previous permitted rates).\56\ The
PM10 emission rate for Power Boiler No. 2 is equivalent to
the 2001 to 2003 baseline rate in the 2008 Arkansas Regional Haze SIP
and the 2016 FIP, which is slightly less than the previous permitted
maximum rate of 82 pph PM10 (99.5 percent of the prior
authorized rate).
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    \54\ See Table 3 of the Arkansas Regional Haze Phase III
submittal (pages 9-10). See also Plantwide Conditions #32 to #43
from ADEQ Air permit #0287-AOP-R22.
    \55\ See ADEQ Air Permit No. #0287-AOP-R22. The BART alternative
emission rates for Power Boiler No. 1 in the permit are 0.5 pph
SO2, 191.1 pph NOX, and 5.2 pph
PM10 and are based on the max design heat input capacity
of 580 MMBtu/hr.
    \56\ The BART alternative emission rates for Power Boiler No. 2
in the current ADEQ Air permit No. 0287-AOP-R22 are 44.2, 51, and
99.5 percent of the previous permit rates. The previous permitted
emission rates for Power Boiler No. 2 in ADEQ Air Permit No. 0287-
AOP-R20 were 984 pph SO2, 574 pph NOX, and
82.0 pph PM10. These are based on emission limits of 1.2,
0.7, and 0.1 lb/MMBtu for SO2, NOX, and
PM10 with a design heat input capacity of 820 MMBtu/hr.

                                   Table 1--BART Alternative Emission Rates *
----------------------------------------------------------------------------------------------------------------
                                                                                Emission
                  Unit                        Operating scenario               Pollutant           rates  (pph)
----------------------------------------------------------------------------------------------------------------
Power Boiler No. 1......................  Burn only natural gas.....  SO2.......................             0.5
                                                                      NOX.......................           191.1
                                                                       PM10.....................             5.2
Power Boiler No. 2......................  Adjusted emission rates     SO2.......................             435
                                           for SO2 and NOX.
                                                                       NOX......................             293
                                                                      PM10......................            81.6
----------------------------------------------------------------------------------------------------------------
* These limits are for a thirty boiler-operating-day rolling average as defined in Plantwide Condition #32 of
  ADEQ Air Permit No. 0287-AOP-R22.

B. Demonstration That BART Alternative Achieves Greater Reasonable
Progress

    Pursuant to 40 CFR 51.308(e)(2)(i), the State must demonstrate that
the alternative measure will achieve greater reasonable progress than
would have resulted from the installation and operation of BART at all
sources subject-to-BART in the State and covered by the alternative
program. This demonstration must be based on the following five
criteria, which are addressed in the subsequent sections:
    (1) A list of all BART-eligible sources within the State.
    (2) A list of all BART-eligible sources and source categories
covered by the alternative.
    (3) An analysis of BART and associated emission reductions.
    (4) The projected emission reductions achievable through the
alternative measure.
    (5) A determination that the alternative achieves greater
reasonable progress than BART.
1. List All BART-Eligible Sources Within the State
    Pursuant to 40 CFR 51.308(e)(2)(i)(A), the SIP must include a list
of all BART-eligible sources within the State. The State included a
list of facilities with BART-eligible sources in Arkansas in its
original 2008 Arkansas Regional Haze SIP submittal.\57\ As part of the
final 2012 action on the 2008 SIP submittal, the EPA approved the
majority of the State's list of BART-eligible sources. The 2008
Arkansas Regional Haze SIP omitted Georgia Pacific Crossett Mill Boiler
6A from the list of BART-eligible sources,\58\ but it was later
included in the list of BART-eligible sources adopted into APCEC
Regulation No. 19, Chapter 15. The most recently updated BART-eligible
source list by the State is in the August 8, 2018, Arkansas Regional
Haze SO2 and PM SIP revision, which the EPA approved on
September 27, 2019.\59\ This recent list includes the Domtar Ashdown
Mill Power Boilers No. 1 and No. 2 as BART-eligible. Therefore, with
this revision, all BART-eligible sources within the State have been
identified in the Arkansas Regional Haze SIP. We propose to find that
the existing list in the Arkansas Regional Haze SO2 and PM
SIP revision fulfills the requirement of 40 CFR 51.308(e)(2)(i)(A) to
provide a list of all BART-eligible sources within the State.
---------------------------------------------------------------------------

    \57\ See Figure 9.1 and Table 9.1 (page 45) of the 2008 Arkansas
Regional Haze SIP included in the docket of this proposed action. A
detailed description of each BART-eligible unit is included in
Appendix 9.1A.
    \58\ See 77 FR 14604, 14605 (March 12, 2012).
    \59\ See Table 1 (pages 8-10) of the Arkansas Regional Haze
SO2 and PM SIP revision.
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2. List All BART-Eligible Sources and 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, have a federally enforceable emission limitation determined by
the State and approved by the EPA as meeting BART in accordance with
RAVI under 40 CFR 51.302(c) or source-specific BART under 40 CFR
51.308(e)(1); or otherwise addressed under source-specific BART or the
40 CFR 51.308(e)(4) BART alternative provisions. In this instance, the
BART alternative measure covers two BART-eligible units, Power Boilers
No. 1 and 2 at Domtar Ashdown Mill. All other BART-eligible sources
have already been addressed in the 2008 Arkansas Regional Haze SIP and
subsequent SIP revisions.\60\ As a result, we propose to find that the
Arkansas Regional Haze Phase III SIP revision meets the requirement of
40 CFR 51.308(e)(2)(i)(B).
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    \60\ See the 2017 Arkansas Regional Haze NOX SIP
revision approved on February 12, 2018 (83 FR 5927), and the 2018
Arkansas Regional Haze SO2 and PM SIP revision approved
on September 27, 2019 (84 FR 51033).
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3. Analysis of BART and Associated Emission Reductions
    Pursuant to 40 CFR 51.308(e)(2)(i)(C), the SIP must include an
analysis of BART and the associated emission reductions achievable at
the Domtar Ashdown Mill for Power Boilers No. 1 and 2. ADEQ relied on
the BART determinations in the 2016 FIP for comparison to the baseline
emissions and analysis of emission reductions under BART. The BART
determinations in the 2016 FIP were based on consideration of ADEQ's
2006 and 2007

BART analyses,\61\ a supplemental BART analysis (dated May 2014)
developed by Domtar that included a five-factor analysis,\62\ and
additional information regarding the existing venturi scrubbers for
Power Boiler No. 2.\63\ The SO2 BART determination for Power
Boiler No. 1 is the SO2 baseline emission rate of 21.0 pph
or 504 pounds per day (ppd) on a thirty boiler-operating-day rolling
average, which does not require the installation of additional control
equipment. The SO2 BART determination for Power Boiler No. 2
is an emission limit of 0.11 lb/MMBtu on a thirty boiler-operating-day
rolling average, based on the boiler's maximum heat input of 820 MMBtu/
hr. This is achieved by operating the existing venturi scrubbers at
ninety percent control efficiency with additional scrubbing reagent and
upgraded scrubber pumps. This results in a controlled emission rate of
91.5 pph SO2 for Power Boiler No. 2. The NOX BART
determination for Power Boiler No. 1 is an emission limit of 207.4 pph
on a thirty boiler-operating-day rolling average with no additional
control equipment needed. This emission limit is based on the boiler's
NOX baseline emission rate. The NOX BART
determination for Power Boiler No. 2 is an emission limit of 345 pph on
a thirty boiler-operating-day rolling average, achieved by the
installation and operation of low NOX burners. The
PM10 BART determination for Power Boiler No. 2 is subject to
the maximum achievable control technology (MACT) standard for boilers
promulgated under CAA section 112, which provides for a PM10
emission limit of 0.44 lb/MMBtu and no additional control equipment.
Power Boiler No. 2 falls under the ``biomass hybrid suspension grate''
subcategory for the Boiler MACT at 40 CFR part 63, subpart DDDDD-
National Emission Standards for Hazardous Air Pollutants (NESHAP) for
Major Sources: Industrial, Commercial, and Institutional Boilers and
Process Heaters. Finally, the EPA approved the State's PM10
BART determination of 0.07 lb/MMBtu for Power Boiler No. 1 in 2012,
which was based on the then-final Boiler MACT. The FIP BART limits and
the SIP-approved PM10 BART limit for Power Boiler No. 1 are
listed in Table 2.
---------------------------------------------------------------------------

    \61\ See ``Best Available Retrofit Technology Determination
Domtar Industries Inc., Ashdown Mill (AFIN 41-00002),'' originally
dated October 31, 2006 and revised on March 26, 2007, prepared by
Trinity Consultants Inc. This was included as part of the Phase III
SIP submittal and included in the docket of this action in Docket
No. EPA-R06-OAR-2015-0189.
    \62\ See ``Supplemental BART Determination Information Domtar
A.W. LLC, Ashdown Mill (AFIN 41-00002),'' originally dated June 28,
2013 and revised on May 16, 2014, prepared by Trinity Consultants
Inc. in conjunction with Domtar A.W. LLC. This was included as part
of the Phase III SIP submittal and included in the docket of this
action in Docket No. EPA-R06-OAR-2015-0189.
    \63\ See final FIP action on September 27, 2016 (81 FR 66332) as
corrected on October 4, 2016 (81 FR 68319) and the associated
technical support document (TSD), ``AR020.0002-00 TSD for EPA's
Proposed Action on the Arkansas Regional Haze FIP'' in Docket No.
EPA-R06-OAR-2015-0189 for the FIP BART analysis for SO2
and NOX for Power Boiler No. 1; and SO2,
NOX, and PM10 for Power Boiler No. 2. The FIP
TSD was included as part of the Phase III SIP submittal and included
in the docket of this action.

                Table 2--Summary of EPA-Approved SIP and FIP BART Limits for Domtar Ashdown Mill
----------------------------------------------------------------------------------------------------------------
                                                                  Emission limits *
                Unit                ----------------------------------------------------------------------------
                                               SO2                     NOX                       PM10
----------------------------------------------------------------------------------------------------------------
Power Boiler No. 1.................  504 ppd...............  207.4 pph.............  0.07 lb/MMBtu.**
Power Boiler No. 2.................  91.5 pph..............  345 pph...............  Satisfied by reliance on
                                                                                applicable PM10 standard
                                                                                under 40 CFR part 63,
                                                                                subpart DDDDD (currently
                                                                                0.44 lb/MMBtu).
----------------------------------------------------------------------------------------------------------------
* See the final BART emission limits in Table 1 of the final action of the approved FIP (81 FR 66332, 66339).
** The EPA approved the State's PM10 BART determination for Power Boiler No. 1 in the March 12, 2012, final
  action (77 FR 14604).

    The baseline emission rates assumed in the 2016 FIP for purposes of
determining the visibility improvement anticipated from BART controls
(based on Domtar's May 2014 supplemental BART analysis) are summarized
in Table 3. The State did not make any changes in the Phase III SIP
submittal to the modeled baseline emission rates presented in the 2014
report. ADEQ is relying on these baseline emission rates for comparison
of the BART alternative to BART (see Table 3 note). The baseline rates
for Power Boiler No. 1 in Domtar's May 2014 BART analysis and our 2016
FIP were based on the 2009 to 2011 adjusted baseline period. The
adjusted 2009 to 2011 baseline rates for Power Boiler No. 1, as
presented in the 2016 FIP, were 21 pph SO2; 207.4 pph
NOX; and 30.4 pph PM10. These replaced the 2001
to 2003 original baseline rates (442.5 pph SO2; 179.5 pph
NOX; and 169.5 pph PM10) submitted by the State.
The 2009 to 2011 period was used as the baseline for Power Boiler No. 1
because a WESP was installed on Power Boiler No. 1 in 2007 to meet MACT
standards under CAA section 112, resulting in a reduction in PM and
SO2 emissions from Power Boiler No. 1. In the 2016 FIP, we
found that the use of the 2009 to 2011 baseline rates to be consistent
with the BART Guidelines, which provide that the baseline emission
rates should represent a realistic depiction of anticipated annual
emissions for the source. The baseline rates for Power Boiler No. 2
were based on the original 2001 to 2003 baseline period. The 2001 to
2003 baseline rates for Power Boiler No. 2 as presented in the 2016 FIP
were 788.2 pph SO2; 526.8 pph NOX; and 81.6 pph
PM10.

                               Table 3--Summary of Baseline Annual Emission Rates
----------------------------------------------------------------------------------------------------------------
                                                                              Emission rates (tpy) *
                              Unit                               -----------------------------------------------
                                                                        SO2             NOX            PM10
----------------------------------------------------------------------------------------------------------------
Power Boiler No. 1 (2009 to 2011 Baseline)......................              92           908.4           133.2
Power Boiler No. 2 (2001 to 2003 Baseline)......................           3,452         2,307.4           357.4
                                                                 -----------------------------------------------

    Total.......................................................           3,544         3,215.8           490.6
----------------------------------------------------------------------------------------------------------------
* These baseline rates from the FIP are being incorporated into this proposed action. These baseline emission
  rates are based on Table 43 of the April 8, 2015 proposed FIP (80 FR 18979) in terms of pph but have been
  converted here to tpy. Supporting documentation for this data was included in the SIP submittal from the State
  and is included in the docket of this action.

    A summary of the annual emissions resulting from the implementation
of BART estimated by the State in the Phase III SIP is shown in Table
4. These rates are based on the BART limits from the 2016 Arkansas
Regional Haze FIP (see Table 2) and the approved PM10 BART
limit for Power Boiler No. 1 from the 2008 Arkansas Regional Haze SIP
in the 2012 action.

                                       Table 4--Annual BART Emission Rates
----------------------------------------------------------------------------------------------------------------
                                                                              Emission rates (tpy) *
                              Unit                               -----------------------------------------------
                                                                        SO2             NOX            PM10
----------------------------------------------------------------------------------------------------------------
Power Boiler No. 1..............................................              92           908.4        ** 177.8
Power Boiler No. 2..............................................           400.7         1,511.1        [dagger]
                                                                                359.16
                                                                 -----------------------------------------------
    Total.......................................................           492.7         2,419.5           536.9
----------------------------------------------------------------------------------------------------------------
* These BART rates are being incorporated into this proposed action. These BART emission rates are based on
  Table 1, ``Final BART Emission Limits'' of the September 27, 2016, final action on the FIP (81 FR 66332,
  66339) and the EPA-approved PM10 BART determination for Power Boiler No. 1 in the March 12, 2012, final action
  (77 FR 14604). These emission rates were reported in terms of pph but have been converted here to tpy.
  Supporting documentation for this data was included in the SIP submittal from the State and is included in the
  docket of this action.
** The estimated annual PM10 emission rate for Power Boiler No. 1 was calculated in Domtar's May 2014
  supplemental BART determination report using 0.066 lb/MMBtu (an emission factor developed from analysis of
  past stack testing) and a heat input rate from 2009 to 2011 of 11,069.67 MMBtu/day (461 MMBtu/hr), resulting
  in 30.4 pph PM10 (or 133.2 tpy). In the Phase III SIP submittal, for purposes of comparing the emission
  reductions achievable through BART versus the BART alternative, the State calculated the PM10 BART emission
  rate for Power Boiler No. 1 by multiplying the actual PM10 BART determination (0.07 lb/MMBtu) that was
  approved in the 2012 final action and a maximum design heat input capacity of 580 MMBtu/hr to reflect the
  current emission reductions achievable (resulting in 40.6 pph PM10 or 177.8 tpy) instead of relying on the
  analysis from the 2014 BART determination.
[dagger] This does not reflect the FIP BART limit which is subject to the 40 CFR part 63, subpart DDDDD Boiler
  MACT PM10 emission limit of 0.44 lb/MMBtu for the biomass hybrid suspension grate subcategory (resulting in
  360.8 pph). Instead, the State used the more conservative permit limit of 0.1 lb/MMBtu and the design heat
  input capacity of 820 MMBtu/hr, resulting in 82 pph, which is more stringent than the FIP limit.

    Table 5 compares the BART controlled emissions from Power Boilers
No. 1 and 2 to the baseline emissions and shows the estimated annual
emission reductions achievable with BART. The BART controls result in
reduced SO2 and NOX emissions for Power Boiler
No. 2 only. There are no SO2 and NOX emission
reductions expected to result from Power Boiler No. 1 since the
SO2 and NOX BART emission rates for Power Boiler
No. 1 are consistent with the baseline. BART controls for Power Boiler
No. 2 reduce the total SO2 and NOX annual
emissions by 3,051 and 796 tpy from the baseline (86 and 25 percent
decreases, respectively). Calculated emissions under the BART controls
for PM10 exhibit slight increases in PM10
emissions for both power boilers totaling 46.3 tpy above the baseline
(nine percent increase in PM10). As mentioned in the Table 4
notes, this difference is because the calculated baseline emissions by
the State were based on stack test data and actual heat input capacity
while the estimated BART emissions were based on the BART emission
limit and the maximum capacity. We propose to find that the Arkansas
Regional Haze Phase III SIP revision has met the requirement for an
analysis of BART and associated emission reductions achievable at the
Domtar Ashdown Mill for Power Boilers No. 1 and 2 under 40 CFR
51.308(e)(2)(i)(C).

                            Table 5--Domtar Emission Reductions Achievable With BART
----------------------------------------------------------------------------------------------------------------
                                                                    Power boilers 1 and 2 total emissions (tpy)
                            Condition                            -----------------------------------------------
                                                                        SO2             NOX            PM10
----------------------------------------------------------------------------------------------------------------
Baseline........................................................         3,544.3         3,215.8           490.6
BART............................................................           492.7         2,419.5           536.9
Emission Reduction..............................................           3,051           795.5           -46.3
----------------------------------------------------------------------------------------------------------------
* A negative number indicates an increase in emissions from the baseline.

4. Analysis of Projected Emission Reductions Achievable Through BART
Alternative
    Pursuant to 40 CFR 51.308(e)(2)(i)(D), the SIP must also include an
analysis of the projected emission reductions achievable through the
BART alternative measure. The estimated annual emission reductions
achievable with the BART alternative can be seen in Table 6. The BART
alternative would result in a decrease in SO2,
NOX, and PM10 emissions from the baseline for
both power boilers. The BART alternative results in greater emission
reductions of NOX and PM10 than the BART
controls. The implemented BART alternative controls would reduce
NOX and PM10 emissions by 1,096 and 111 tpy,
respectively, from the baseline. The BART alternative reduces fewer
SO2 emissions compared to the BART controls (BART achieves
3,051 tpy SO2 reduction) but still achieves a decrease of
1,637 tpy SO2 from the baseline. Since the distribution of
emission reductions between the BART alternative and BART are slightly
different, the State conducted dispersion modeling to determine
differences in visibility improvement between BART and the alternative
measure as discussed in section II.B.5. We propose to find that ADEQ
has met the requirement in this section for reporting an analysis of
the projected emission reductions achievable through the BART
alternative measure under 40 CFR 51.308(e)(2)(i)(D).

                    Table 6--Domtar Emission Reductions Achievable With the BART Alternative
----------------------------------------------------------------------------------------------------------------
                                                                    Power boilers 1 and 2 total emissions (tpy)
                            Condition                            -----------------------------------------------
                                                                        SO2             NOX            PM10
----------------------------------------------------------------------------------------------------------------
Baseline........................................................         3,544.3         3,215.8           490.6
BART Alternative................................................         1,907.5         2,120.3          380.18
Emission Reduction..............................................           1,637           1,096             111
----------------------------------------------------------------------------------------------------------------

5. Determination That Alternative Achieves Greater Reasonable Progress
Than 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 measure achieves greater
reasonable progress than BART. Based on the data provided by Domtar in
the BART alternative analysis, ADEQ performed a clear weight of
evidence approach to determine whether the Ashdown Mill satisfies the
requirements of 40 CFR 51.308(e)(2)(i)(E). Factors which can be used in
a weight of evidence determination in this context may include, but are
not limited to, future projected emissions levels under the alternative
as compared to under BART and future projected visibility conditions
under the two scenarios. When comparing the summary of overall emission
reductions in Tables 5 and 6, the BART alternative achieves greater
emission reductions than the BART controls for NOX and
PM10, but not for SO2. Because the BART controls
achieve higher SO2 emission reductions than the BART
alternative, the State also relied on a modeling analysis to support
its conclusion that Domtar's BART alternative is better than BART.\64\
This weight of evidence analysis is based on the comparison of
emissions under the BART and alternative control scenarios, as well as
a modified version of the two-part modeling test set forth in 40 CFR
51.308(e)(3), and described in section I.D of this action. The State
used an air quality modeling methodology approach using the maximum
98th percentile visibility impact of three modeled years using the
CALPUFF model instead of modeled visibility conditions for the twenty
percent best and worst days. This modeling approach differs from the
modeling contemplated under 40 CFR 51.308(e)(3) for BART alternatives.
However, this approach is consistent with the approach recommended by
the BART guidelines \65\ for comparing different control options at a
single source when developing BART determinations relying on the 98th
percentile visibility impact as the key metric,\66\ and is also
consistent with the methodology followed in EPA's 2016 FIP BART
determination for Domtar. This approach is, therefore, acceptable for
the comparison of the proposed BART alternative to the FIP BART for
Domtar since it is the same modeling used to determine BART in the FIP,
and the BART alternative is focused on only the BART sources at Domtar.
---------------------------------------------------------------------------

    \64\ See BART Alternative Analysis Domtar A.W. LLC, Ashdown Mill
(AFIN 41-00002) submitted March 20, 2018.
    \65\ See 40 CFR 51 Appendix Y section III.A.3 and IV.D.5,
``Guidelines for BART Determinations Under the Regional Haze Rule.''
CALPUFF is a single source air quality model that is recommended in
the BART Guidelines. Since CALPUFF was used for this BART
alternative analysis, the modeling results were post-processed in a
manner consistent with the BART guidelines.
    \66\ The EPA recognized the uncertainty in the CALPUFF modeling
results when the EPA made the decision, in the final BART
Guidelines, to recommend that the model be used to estimate the 98th
percentile visibility impairment rather than the highest daily
impact value. ``Most important, the simplified chemistry in the
model tends to magnify the actual visibility effects of that source.
Because of these features and the uncertainties associated with the
model, we believe it is appropriate to use the 98th percentile--a
more robust approach that does not give undue weight to the extreme
tail of the distribution.'' (see 70 FR 39104, 39121).
---------------------------------------------------------------------------

    ADEQ considered two methods of modeling evaluation provided by
Domtar for this approach of using the maximum 98th percentile
visibility impact. Method 1 assesses visibility impairment on a per
source per pollutant basis and does not account for the full chemical
interaction of emissions from the two boilers. Method 1 was performed
to create a direct comparison with the approach that the EPA used in
the Arkansas Regional Haze FIP, based on the modeling submitted by
Domtar in the 2014 analysis. The 2014 Domtar analysis and the FIP
focused on modeling each unit and pollutant separately to evaluate the
potential visibility benefit from specific controls at each unit to
inform the BART determination. In method 2, all sources and pollutants
were combined into a single modeling run per year for the baseline and
each control scenario. Method 2 allows for interaction of the
pollutants from both boilers, as emitted pollutants from each unit
disperse and compete for the same reactants in the atmosphere,
providing modeled overall impacts due to emissions from both units. The
State followed the same general CALPUFF modeling protocol and used the
same meteorological data inputs for the BART alternative assessment as
discussed in Appendix B to the FIP TSD.\67\ Only the modeled

emission rates change to represent the modeled scenarios for each
method.
---------------------------------------------------------------------------

    \67\ See final FIP action on September 27, 2016 (81 FR 66332) as
corrected on October 4, 2016 (81 FR 68319) and the associated FIP
TSD, titled ``AR020.0002-00 TSD for EPA's Proposed Action on the AR
RH FIP'' which was included in the SIP submittal from the State and
in the docket of this action. See Docket No. EPA-R06-OAR-2015-0189
for a detailed discussion of the FIP modeled emission rates and
results of the visibility modeling.
---------------------------------------------------------------------------

    Domtar completed the BART alternative analysis using both methods
and documented that the proposed BART alternative results in greater
visibility improvement than the BART controls at Caney Creek and on
average across the four Class I areas. The modeled baseline visibility
impairment, in deciviews (dv), was compared to the modeled visibility
impairment under the implementation of the modeled control scenarios
for BART and the BART alternative. ADEQ included an analysis utilizing
method 1 that shows that the BART alternative controls achieve greater
overall reductions in visibility impairment ([Delta]dv) from the
baseline cumulatively across the four Class I areas when compared to
BART (0.549 [Delta]dv for the alternative versus 0.473 [Delta]dv for
BART).\68\ ADEQ also included the visibility improvement anticipated
(see Tables 7 and 8) at each Class I area utilizing method 2 (the full
chemistry assessment method).\69\ ADEQ determined that the visibility
benefits contained in Table 7 from method 2 and the BART determinations
\70\ in Table 2 (see section II.B.3) form an appropriate BART benchmark
for the purposes of the evaluation of Domtar's BART alternative. We
agree with ADEQ that because method 2 provides for the full chemical
interaction of emissions from both power boilers, method 2 analysis
results shown in Tables 7 and 8 are a more reliable assessment of the
anticipated overall visibility improvement of controls than method 1
analysis results under each scenario.
---------------------------------------------------------------------------

    \68\ See Table 4 of the Arkansas Regional Haze Phase III SIP
revision to see the method 1 results (page 11).
    \69\ See Table 5 (page 12) of the Arkansas Regional Haze Phase
III submittal for a comparison of the cumulative visibility
improvement under BART versus the BART alternative. See also the
associated September 4, 2018, ``Ashdown Mill BART Alternative TSD''
which was included in the SIP submittal from the State and in the
docket of this action in Docket No. EPA-R06-OAR-2015-0189.
    \70\ Associated with the approved PM10 BART
determination for Power Boiler No. 1 in the 2008 SIP and the FIP
BART determinations for SO2, NOX, and
PM10 for Power Boilers No. 1 and 2.

   Table 7--Method 2--Visibility Improvement From BART Controls (98th Percentile Impacts) Max of Three Modeled
                                                      Years
----------------------------------------------------------------------------------------------------------------
                                                                                Visibility
                                                                                improvement
                 Unit                         Class I area         Baseline (dv)     BART (dv)     from controls
                                                                                ([Delta]dv)
----------------------------------------------------------------------------------------------------------------
Both Boilers..........................  Caney Creek Wilderness..           1.137           0.776           0.361
                                        Upper Buffalo Wilderness           0.163           0.103           0.060
                                        Hercules-Glades                    0.118           0.057           0.061
                                         Wilderness.
                                        Mingo National Wildlife            0.072           0.038           0.034
                                         Refuge.
                                       -------------------------------------------------------------------------
    Total.............................  ........................            1.49           0.974           0.516
----------------------------------------------------------------------------------------------------------------

 Table 8--Method 2--Visibility Improvement From BART Alternative Controls (98th Percentile Impacts) Max of Three
                                                  Modeled Years
----------------------------------------------------------------------------------------------------------------
                                                                                Visibility
                                                                                BART         improvement
                 Unit                         Class I area         Baseline (dv)    alternative    from controls
                                                                                (dv)         ([Delta]dv)
----------------------------------------------------------------------------------------------------------------
Both boilers..........................  Caney Creek Wilderness..           1.137           0.753           0.384
                                        Upper Buffalo Wilderness           0.163           0.104           0.059
                                        Hercules-Glades                    0.118           0.069           0.049
                                         Wilderness.
                                        Mingo National Wildlife            0.072           0.044           0.028
                                         Refuge.
                                       -------------------------------------------------------------------------
    Total.............................  ........................            1.49            0.97           0.520
----------------------------------------------------------------------------------------------------------------

    The BART alternative modeling in Table 8 demonstrates that
visibility does not degrade in any Class I area from the baseline and
shows greater visibility improvement at Caney Creek and cumulatively
across the four impacted Class I areas than the modeled BART controls
in Table 7. Despite a smaller reduction in SO2 emissions
than BART (a 1,414 tpy SO2 difference), the BART alternative
results in 300 tpy fewer NOX emissions and 157 tpy fewer
PM10 emissions compared to BART. The additional reduction in
NOX emissions under the BART alternative controls results in
more overall modeled visibility improvement than BART even with the
smaller reduction in SO2 emissions. Greater visibility
improvement occurs because Domtar's baseline NOX emissions
contribute more to visibility impairment across all four Class I areas
for Power Boiler No. 1, and also contribute more at Caney Creek for
Power Boiler No. 2 than other pollutants.\71\ Specifically, for Power
Boiler No. 1, baseline modeled NO3- and
NO2 impacts have the highest contribution to visibility
impairment at all Class I areas. For Power Boiler No. 2, baseline
modeled NO3- and NO2 impacts are the
primary driver for visibility impacts at Caney Creek, which is the
Class I area impacted the most by the Domtar units. As a result, for
Power Boiler No. 2, the visibility impacts resulting from
NOX at Caney Creek outweigh SO42-
species contributions (from SO42- precursors) to
impacts at the other three Class I areas combined (see Table 9). The
baseline visibility impacts and the benefits modeled under the control
scenarios at Caney Creek are significantly larger than at the other
Class I areas.
---------------------------------------------------------------------------

    \71\ See Appendix C ``Supplemental BART Determination
Information Domtar A.W. LLC, Ashdown Mill (AFIN 41-00002),''
originally dated June 28, 2013 and revised on May 16, 2014, prepared
by Trinity Consultants Inc. in conjunction with Domtar A.W. LLC.

                      Table 9--Baseline CALPUFF Modeled Pollutant Species Contributions to Impacts From Power Boilers No 1 and 2 *
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                               98th                       Species contribution to impacts
                                                                            Percentile   ---------------------------------------------------------------
                   Unit                             Class I area            visibility        % SO42-
                                                                           impacts (dv)                       % NO3-          % PM10           % NO2
--------------------------------------------------------------------------------------------------------------------------------------------------------
Power Boiler No. 1........................  Caney Creek Wilderness......           0.335            2.23           85.26            6.68            5.83
                                            Upper Buffalo Wilderness....           0.038            2.75           85.89            8.03            3.32
                                            Hercules-Glades Wilderness..           0.020            2.70           91.82            3.94            1.55
                                            Mingo National Wildlife                0.014            4.03           90.06            5.13            0.78
                                             Refuge.
Power Boiler No. 2........................  Caney Creek Wilderness......           0.844           22.04           70.68            4.58            2.69
                                            Upper Buffalo Wilderness....           0.146           76.99           20.76            2.26               0
                                            Hercules-Glades Wilderness..           0.105           61.17           37.68            1.06            0.09
                                            Mingo National Wildlife                0.065           81.46           15.47            3.07               0
                                             Refuge.
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Max values among the three modeled years.

    ADEQ determined that the BART alternative controls reduce the
overall visibility impairment from the baseline by 0.520 [Delta]dv for
method 2 and is greater than the overall visibility improvement modeled
under BART, which is 0.516 [Delta]dv. ADEQ noted that the most impacted
Class I area, Caney Creek (1.137 dv baseline impairment), improves the
greatest (0.384 [Delta]dv) with the BART alternative for method 2, and
would experience greater visibility improvement under the BART
alternative scenario than under the BART scenario, which improves by
0.361 [Delta]dv. Given that baseline impacts at Caney Creek are much
larger than impacts at the other Class I areas, it is reasonable to
give greater weight to visibility benefits at Caney Creek due to the
alternative over BART. The baseline visibility impacts and the level of
visibility benefit from controls at the other three Class I areas are
smaller than those at Caney Creek and well below the 0.5 dv threshold
used by the State to determine if a source contributes to visibility
impairment at a Class I area. We took this same approach in our 2016
FIP to emphasize the visibility benefits at Caney Creek when
considering different potential BART controls. Our FIP analysis also
showed that the anticipated visibility benefits due to potential BART
controls at the other three Class I areas were much smaller.\72\
---------------------------------------------------------------------------

    \72\ See 80 FR 18944, 18978-18989 (April 8, 2015) and 81 FR
66332, 66347 (September 27, 2016).
---------------------------------------------------------------------------

    Tables 10 and 11, provided by the EPA to complement the State's
analysis, compare the average visibility impact across the top ten
highest impacted days at each Class I area (average 8th to 17th
highest).\73\ This analysis provides a broader look at those days with
the highest impacts at each Class I area. The results are consistent
with the State's analysis based on the 98th percentile day, which was
selected as representative of the highest impact (the 8th highest
day).\74\ The average results across the top ten highest impacted days
also support that it is appropriate to focus on Caney Creek impacts
(0.9819 dv baseline impairment) since they are much larger than impacts
at the other Class I areas (see Table 10). The BART alternative results
in more visibility improvement at Caney Creek and slightly less at the
other Class I areas when compared to the BART limits, but the
visibility improvement at Caney Creek outweighs the difference in
visibility benefit at the other three Class I areas altogether. On
average, (see Table 11) the BART alternative controls achieve greater
overall visibility improvement from the baseline compared to BART for
the ten highest impacted days (0.439 [Delta]dv for the alternative
versus 0.423 [Delta]dv for BART).
---------------------------------------------------------------------------

    \73\ This data is based on the CALPUFF modeling provided by
Domtar and relied on by the State in the Phase III SIP. See ``EPA--
CALPUFF summary for Method 2.xlsx'' for the EPA's summary of the
modeling data, available in the docket for this action.
    \74\ See 70 FR 39104, 39121 (July 6, 2005), Regional Haze
Regulations and Guidelines for Best Available Retrofit Technology
(BART) Determinations.

                  Table 10--Average Modeled Visibility Impacts of the Ten Highest Impacted Days
                                           [Average 8th-17th highest]
----------------------------------------------------------------------------------------------------------------
                                                                   Visibility impacts (dv) (max of three modeled
                                                                                years)
                              Area                               -----------------------------------------------
                                                                     Baseline       FIP limits      Alternative
----------------------------------------------------------------------------------------------------------------
Caney Creek Wilderness..........................................           0.982           0.692           0.655
Hercules-Glades Wilderness......................................           0.086           0.045           0.053
Mingo National Wildlife Refuge..................................           0.066           0.031           0.039
Upper Buffalo Wilderness........................................           0.138           0.082           0.087
                                                                 -----------------
    Total.......................................................           1.273           0.850           0.834
----------------------------------------------------------------------------------------------------------------

  Table 11--Average Visibility Improvement of the Ten Highest Impacted
                                  Days
                       [Average 8th-17th highest]
------------------------------------------------------------------------
                                              Visibility improvement
                                             ([Delta]dv) (max of three
                                                  modeled years)
                  Area                   -------------------------------
                                                               BART
                                               BART         alternative
------------------------------------------------------------------------
Caney Creek Wilderness..................           0.290           0.327
Hercules-Glades Wilderness..............           0.041           0.034
Mingo National Wildlife Refuge..........           0.035           0.027
Upper Buffalo Wilderness................           0.057           0.051
                                         -------------------------------
    Total...............................           0.423           0.439
------------------------------------------------------------------------

    Table 12, also provided by the EPA to complement the State's
analysis, evaluates the modeled number of days impacted by Domtar over
1.0 dv and 0.5 dv for each scenario at each Class I area.\75\ These
metrics provide additional information comparing the frequency and
duration of higher visibility impacts. Caney Creek is the only Class I
area with days of modeled visibility impacts from Domtar greater than
0.5 dv. Overall, the FIP limits and the BART alternative both
significantly reduce the number of impacted days over 1.0 dv and 0.5 dv
from the baseline at Caney Creek. Table 12 shows that both the FIP
limits and the BART alternative reduce the total modeled days with
visibility impacts over 1.0 dv from fifteen days in the baseline to
four days for each scenario. For days with modeled visibility impacts
over 0.5 dv, the FIP limits reduce the number of days from 82 to 36,
compared to the BART alternative which reduces the number to 37 days.
This metric of days impacted over 0.5 dv very slightly favors the FIP
limits over the BART alternative.
---------------------------------------------------------------------------

    \75\ This data is based on the CALPUFF modeling provided by
Domtar and relied on by the State in the Phase III SIP revision. See
``EPA--CALPUFF summary for Method 2.xlsx'' for the EPA's summary of
the modeling data, available in the docket for this action.

                 Table 12--Modeled Number of Days With Visibility Impacts Over 0.5 dv and 1.0 dv
----------------------------------------------------------------------------------------------------------------
                                                  Baseline  (days)     FIP limits  (days)    Alternative  (days)
                                               -----------------------------------------------------------------
                                  Area          [Delta]dv  [Delta]dv  [Delta]dv  [Delta]dv  [Delta]dv  [Delta]dv
                                                   >=0.5      >=1.0      >=0.5      >=1.0      >=0.5      >=1.0
----------------------------------------------------------------------------------------------------------------
2001...................  Caney Creek..........         41         10         23          4         23          3
                         Upper Buffalo,                 0          0          0          0          0          0
                          Hercules-Glades, and
                          Mingo.
2002...................  Caney Creek..........         22          4          7          0          8          1
                         Upper Buffalo,                 0          0          0          0          0          0
                          Hercules-Glades, and
                          Mingo.
2003...................  Caney Creek..........         19          1          6          0          6          0
                         Upper Buffalo,                 0          0          0          0          0          0
                          Hercules-Glades, and
                          Mingo.
                                               ------------
    Total..............  Caney Creek..........         82         15         36          4         37          4
                         Upper Buffalo,                 0          0          0          0          0          0
                          Hercules-Glades, and
                          Mingo.
----------------------------------------------------------------------------------------------------------------

    In accordance with our regulations governing BART alternatives, we
support the use of a weight of evidence determination as an alternative
to the methodology set forth in 40 CFR 51.308(e)(3).\76\ In evaluating
Arkansas' weight of evidence demonstration, we have evaluated ADEQ's
analysis and additional model results (relying primarily on the
analysis of the 98th percentile impacts at Caney Creek), the analysis
of emission reductions, and the analysis of Domtar's visibility impacts
due to NO3- compared to SO4\2\
-, which all support the conclusion that the BART
alternative provides for greater reasonable progress than BART. In
addition, we also considered our analysis of the ten highest impacted
days and our analysis of the number of days impacted over 0.5 dv and
1.0 dv. Our analysis of the ten highest impacted days similarly
supports the conclusion that the BART alternative provides for greater
reasonable progress than BART, but the analysis of the number of days
impacted over 0.5 dv and 1.0 dv slightly favored BART over the BART
alternative. This single metric, however, on which BART performed
better than the BART alternative (days impacted over 0.5 dv) is not
sufficient to outweigh the substantial evidence presented using the
other metrics as to the relatively greater benefits of the BART
alternative over BART. Based on this weight of evidence analysis of
emission reductions and visibility improvement by the State (using the
98th percentile metric) as complemented by the EPA's analysis of the
ten highest impacted days and number of days impacted over 0.5 dv and
1.0 dv, we propose to approve the determination by the State that the
BART alternative achieves greater reasonable progress than BART under
40 CFR 51.308(e)(2)(i)(E).
---------------------------------------------------------------------------

    \76\ 71 FR 60622 (October 13, 2006).
---------------------------------------------------------------------------

C. Requirement That Emission Reductions Take Place During the Period of
the 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. the first regional
haze implementation period for Arkansas. To meet this requirement, the
State must provide a detailed description of the alternative measure,
including schedules for

implementation, the emission reductions required by the program, all
necessary administrative and technical procedures for implementing the
program, rules for accounting and monitoring emissions, and procedures
for enforcement.
    While the BART alternative emission limits became enforceable by
the State immediately upon issuance of a minor modification letter sent
by the State to Domtar on February 28, 2019,\77\ the State notes in its
Phase III SIP revision that Domtar provided documentation demonstrating
that Power Boilers No. 1 and 2 have actually been operating at emission
levels below the BART alternative emission limits since December 2016.
This documentation included a letter dated December 20, 2018, submitted
to ADEQ by Domtar,\78\ providing emissions data for Power Boilers No. 1
and 2 from December 2016 to November 2018. The letter noted that
because Power Boiler No. 1 has been in standby mode, it has emitted
zero emissions since early 2016. The letter also provided continuous
emissions monitoring system (CEMS) daily average and thirty-day rolling
average emissions data for SO2 and NOX for Power
Boiler No. 2 from December 1, 2016 through November 30, 2018. Based on
this CEMS data (see Table 13), the highest thirty-day rolling averages
for Power Boiler No. 2 were found to be 294 pph SO2 and 179
pph NOX, which are below the BART alternative emission
limits of 435 pph SO2 and 293 pph NOX. The
December 20, 2018 letter explained that compliance with the
PM10 BART alternative limit for Power Boiler No. 2 is
demonstrated via compliance with the Boiler MACT. Based on previous
compliance stack testing results conducted by Domtar in January 2016,
PM10 emissions for Power Boiler No. 2 are equal to 34 pph
PM10,\79\ which is below the BART alternative
PM10 emission limit of 81.6 pph PM10.\80\ Based
on this demonstration, we are proposing to find that Power Boilers No.
1 and No. 2 at the Ashdown Mill satisfy the timing requirements of 40
CFR 51.308(e) that the necessary emission reductions associated with
the BART alternative occur during the first long-term strategy for
regional haze.
---------------------------------------------------------------------------

    \77\ See Minor Modification Letter entitled, ``Application for
Minor Modification Determination of Qualifying Minor Modification,''
included with the SIP revision and in the docket for this action.
    \78\ See letter from Domtar to ADEQ entitled, ``Demonstration of
Compliance with Proposed BART Alternative,'' included with the SIP
revision documenting compliance with the Phase III SIP emission
limits.
    \79\ Based on the January 2016 stack testing, it was found that
the actual PM10 emissions from Power Boiler No. 2 are
0.059 lb/MMBtu (thirteen percent of the MACT standard of 0.44 lb/
MMBtu), which Domtar estimated to equal 34 pph based on a heat input
of 569 MMBtu/hr during testing.
    \80\ See information provided in letters dated December 20,
2018, and January 19, 2017, submitted by Domtar to ADEQ. These
letters can be found in the ``Documentation of Compliance with Phase
III SIP Emission Limits'' section of the Arkansas Regional Haze
Phase III SIP revision.

           Table 13--Actual Emissions for Power Boiler No. 2 From December 2016 Through November 2018
----------------------------------------------------------------------------------------------------------------
                                                                    Emission rates, (pph) (based on maximum of
                                                                           thirty-day rolling averages)
                              Date                               -----------------------------------------------
                                                                        SO2             NOX            PM10
----------------------------------------------------------------------------------------------------------------
December 2016 through November 2018.............................      294 (-141)      179 (-114)      34 (-47.6)
----------------------------------------------------------------------------------------------------------------
* The numbers in parentheses indicate an increase (+) or decrease (-) in emissions from the BART alternative
  rates of 435 pph SO2; 293 pph NOX; and 81.6 pph PM10.

    Domtar submitted additional letters to ADEQ containing CEMS
emission data from January 2018 to April 2019.\81\ This CEMS data
demonstrates continued compliance for Power Boilers No. 1 and 2 by
showing emission levels below the BART alternative emission limits
beyond 2018 (see Table 14). Domtar noted that Power Boiler No. 1
continued to be in standby mode and that its emissions have continued
to be zero since early 2016. The Domtar letters also noted that the
CEMS daily average and thirty-day rolling average emissions for
SO2 and NOX were below the BART alternative
limits for each month from January 2018 to April 2019. Additionally,
based on the previous January 2016 Boiler MACT stack testing results,
actual PM10 emissions from Power Boiler No. 2 were
conservatively estimated to be 48 pph PM10, which is below
the BART alternative emission limit of 81.6 pph PM10 for
Power Boiler No. 2.\82\
---------------------------------------------------------------------------

    \81\ See letters from Domtar to ADEQ dated February 21, 2019;
March 15, 2019; April 16, 2019; and May 16, 2019. These letters can
be found in the ``Documentation of Compliance with Phase III SIP
Emission Limits'' section of the Arkansas Regional Haze Phase III
SIP revision.
    \82\ The PM10 emission rates were based on the 0.059
lb/MMBtu stack testing result (thirteen percent of the MACT
standard, 0.44 lb/MMBtu) and a maximum heat input capacity of the
boiler of 820 MMBtu/hr.

                Table 14--Actual Emissions for Power Boiler No. 2 From January 2019 to April 2019
----------------------------------------------------------------------------------------------------------------
                                                                   Emission rates, (pph) * (based on maximum of
                                                                           thirty-day rolling averages)
                              Date                               -----------------------------------------------
                                                                        SO2             NOX            PM10
----------------------------------------------------------------------------------------------------------------
January 2019....................................................      280 (-155)      170 (-123)      48 (-33.6)
February 2019...................................................      305 (-130)      178 (-115)      48 (-33.6)
March 2019......................................................      270 (-165)      153 (-140)      48 (-33.6)
April 2019......................................................      250 (-185)      137 (-156)      48 (-33.6)
----------------------------------------------------------------------------------------------------------------
* The numbers in parentheses indicate an increase (+) or decrease (-) in emissions from the BART alternative
  rates of 435 pph SO2; 293 pph NOX; and 81.6 pph PM10.

    We propose to conclude that the State has adequately addressed the
applicable provisions under 40 CFR 51.308(e)(2)(iii) to ensure all
reductions take place during the period of the first long-term
strategy.

D. Demonstration That Emission Reductions From Alternative Measure Will
Be Surplus

    Pursuant to 40 CFR 51.308(e)(2)(iv), the SIP must demonstrate that
the emission 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. When
promulgating this requirement in 1999, the EPA explained that emission
reductions must be ``surplus to other Federal requirements as of the
baseline date of the SIP, that is, the date of the emission inventories
on which the SIP relies.'' \83\ The baseline date for the 2008 Arkansas
Regional Haze SIP emission inventory was previously established as 2002
during SIP planning stages for the first implementation period.\84\ In
the Arkansas Regional Haze Phase III SIP revision, ADEQ states that the
BART alternative emission reductions are based on operational changes
for Domtar and are surplus to reductions as of the baseline of the 2008
Arkansas Regional Haze SIP. We agree with the State that the emission
reductions required by the State's BART alternative are additional and
will not result in double-counting of reductions from other Federal
requirements since they will occur after the original 2002 emission
inventory. Therefore, we propose to find that the Domtar BART
alternative meets the requirements of 40 CFR 51.308(e)(2)(iv).
---------------------------------------------------------------------------

    \83\ See 64 FR 35714, 35742 (July 1, 1999); see also 70 FR
39104, 39143 (July 6, 2005).
    \84\ See Memorandum from Lydia Wegman and Peter Tsirigotis, 2002
Base Year Emission Inventory SIP Planning: 8-hr Ozone,
PM2.5, and Regional Haze Programs, November 8, 2002.
---------------------------------------------------------------------------

E. Implementation of the BART Alternative Through Permit Conditions

    The Arkansas Regional Haze Phase III SIP revision incorporates
certain provisions of the permit that became effective August 1, 2019
and includes all conditions for implementing the Domtar BART
alternative and making it enforceable in practice.\85\ The emission
limits became enforceable by the State immediately upon issuance of the
minor modification letter sent to Domtar on February 28,
2019.86 87 The final permit revision that became effective
August 1, 2019 (0287-AOP-R22) includes plantwide conditions 32 through
43 that contain enforceable emission limits for NOX,
SO2, and PM10 (see Table 1) as well as compliance
requirements for the power boilers. Compliance with SO2,
NOX and PM10 emissions limits (0.5, 191.1, and
5.2 pph, respectively) for Power Boiler No. 1 is based on a thirty-day
boiler operating day rolling average \88\ based on natural gas fuel
usage records and the following AP-42 emission factors: 0.6 lb
SO2/MMscf, 280 lb NOX/MMscf, and 7.6 lb
PM10/MMscf (conditions 32 and 33).\89\ In the event Power
Boiler No. 1 is permanently retired, the BART alternative limits and
conditions applicable to Power Boiler No. 1 shall be satisfied by the
permanent retirement and ADEQ receipt of a disconnection notice
(condition 34). Records showing compliance for Power Boiler No. 1 are
required and shall be retained for at least five years and made
available to ADEQ or EPA upon request (condition 36). Compliance with
SO2, NOX, and PM10 emission limits
(435, 293, and 81.6 pph, respectively) for Power Boiler No. 2 is based
on a thirty-day boiler operating day rolling average (condition 37).
Compliance with the SO2 and NOX emission limits
for Power Boiler No. 2 is based on CEMS data that is subject to 40 CFR
part 60, as amended (condition 38). Since Power Boiler No. 2 is subject
to 40 CFR part 63 subpart DDDDD, the applicable PM10
compliance demonstration requirements under the Boiler MACT shall be
utilized to demonstrate compliance for PM10 emissions
(condition 41). If Power Boiler No. 2 switches to natural gas
combustion, the applicable natural gas AP-42 emission factors of 0.6 lb
SO2/MMscf, 280 lb NOX/MMscf, and 7.6 lb
PM10/MMscf in conjunction with natural gas fuel usage
records (condition 40) shall be used to demonstrate compliance with the
BART emission limits. In the event Power Boiler No. 2 is permanently
retired, the BART alternative limits and conditions applicable to Power
Boiler No. 2 shall be satisfied by the permanent retirement and ADEQ
receipt of a disconnection notice (condition 39).\90\ Records showing
compliance for Power Boiler No. 2 are required and shall be retained
for at least five years and made available to ADEQ or EPA upon request
(condition 43). With the EPA concurrence with the State, Domtar may
request alternative sampling or monitoring methods that are equivalent
to the methods specified in conditions 32 to 35 for Power Boiler No. 1,
and in conditions 37 to 41 for Power Boiler No. 2 (conditions 35 and
42). We propose to approve these specific plantwide permit provisions
for the BART alternative as source-specific SIP requirements.
---------------------------------------------------------------------------

    \85\ See Plantwide Conditions #32 to #43 from permit #0287-AOP-
R22. For compliance with the CAA Regional Haze Program's
requirements for the first planning period, the No. 1 and 2 Power
Boilers are subject-to-BART alternative measures consistent with 40
CFR 51.308. These Plantwide Conditions state that the terms and
conditions of the BART alternative measures are to be submitted to
the EPA for approval as part of the Arkansas SIP, which ADEQ has
done through submittal of the Phase III SIP revision. The Plantwide
Conditions also state that upon initial EPA approval of the permit
into the SIP, the permittee shall continue to be subject to the
conditions as approved into the SIP even if the conditions are
revised as part of a permit amendment until such time as the EPA
approves any revised conditions into the SIP. The permittee shall
remain subject to both the initial SIP-approved conditions and the
revised conditions, until the EPA approves the revised conditions.
    \86\ See Minor Modification Letter entitled, ``Application for
Minor Modification Determination of Qualifying Minor Modification,''
included with the SIP revision and in the docket for this action.
    \87\ Under APCEC Reg. 26.1007, ``a source may make the change
proposed in its minor permit modification application upon receipt
of written notification from the Department.'' After the source
makes the proposed change and until the Department takes action on
the minor modification application, the source ``must comply with
both the applicable requirements governing the change and the
proposed permit terms and conditions.''
    \88\ A thirty-day boiler operating day rolling average is
defined as the arithmetic average of thirty consecutive daily values
in which there is any hour of operation, and where each daily value
is generated by summing the pounds of pollutant for that day and
dividing the total by the sum of the hours the boiler was operating
that day. A day is from 6 a.m. one calendar day to 6 a.m. the
following calendar day.
    \89\ AP-42, Compilation of Air Pollutant Emission Factors, has
been published since 1972 as the primary compilation of the EPA's
emission factor information. It contains emission factors and
process information for more than 200 air pollution source
categories. The emission factors have been developed and compiled
from source test data, material balance studies, and engineering
estimates. The Fifth Edition of AP-42 was published in January 1995.
Since then, the EPA has published supplements and updates to the
fifteen chapters available in Volume I, Stationary Point and Area
Sources.
    \90\ This is a notice to ADEQ that indicates that a unit is
being taken permanently out-of-service.
---------------------------------------------------------------------------

F. EPA's Conclusion on Arkansas' BART Alternative Determination for
Domtar

    We are proposing to find that the State submitted as part of their
Arkansas Regional Haze Phase III SIP revision all of the required plan
elements under 40 CFR 51.308(e)(2) and documentation of all required
analyses for the BART alternative determination. We are proposing to
find that the State demonstrated through a clear weight of evidence
approach that the BART alternative achieves greater reasonable progress
than would be achieved through the installation and operation of BART.
The State also established that all necessary emission reductions took
place during the period of the first long-term strategy, and that no
double-

counting of emission reductions would occur but would be surplus to