[Federal Register Volume 86, Number 53 (Monday, March 22, 2021)]
[Rules and Regulations]
[Pages 15104-15132]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-05362]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R06-OAR-2015-0189; FRL-10019-63-Region 6]


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

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: Pursuant to the Clean Air Act (CAA or the Act), the 
Environmental Protection Agency (EPA) is finalizing approval of a 
revision to the Arkansas State Implementation Plan (SIP) submitted by 
the State of Arkansas through the Arkansas Department of Energy and 
Environment, Division of Environmental Quality (DEQ) 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 approving an alternative measure to best available retrofit 
technology (BART) at the Domtar Ashdown Mill for sulfur dioxide 
(SO2), particulate matter (PM), and nitrogen oxide 
(NOX); and elements of the SIP submittal that relate to 
these BART requirements at this facility. In addition, we are approving 
the withdrawal from the SIP of the previously approved PM10 
BART limit for Power Boiler No. 1. The EPA is also concurrently 
approving Arkansas' interstate visibility transport provisions from the 
August 8, 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. In conjunction with our final approval of these 
SIP revisions, we are finalizing in a separate rulemaking, published 
elsewhere in this issue of the Federal Register, our withdrawal of the 
Federal implementation plan (FIP) provisions for the Domtar Ashdown 
Mill.

DATES: This rule is effective on April 21, 2021.

ADDRESSES: The EPA has established a docket of all documents for this 
action at https://www.regulations.gov under

[[Page 15105]]

Docket ID No. EPA-R06-OAR-2015-0189. Although listed in the index, some 
information is not publicly available, e.g., Confidential Business 
Information or other information whose disclosure is restricted by 
statute. Certain other material, such as copyrighted material, is not 
placed on the internet. Publicly available docket materials are 
available electronically through https://www.regulations.gov.

FOR FURTHER INFORMATION CONTACT: James E. Grady, EPA Region 6 Office, 
Regional Haze and SO2 Section, 1201 Elm Street, Suite 500, 
Dallas TX 72570, 214-665-6745; [email protected]. Please call or 
email Mr. Grady or Mr. Bill Deese at 214-665-7253 if you need 
alternative access to material indexed but not provided in the docket.

SUPPLEMENTARY INFORMATION: Throughout this document ``we,'' ``us,'' and 
``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. Summary of Proposed Action and Our Final Decisions
III. Public Comments and EPA Responses
    A. Demonstration That the BART Alternative Is Better-Than-BART
    B. Monitoring, Recordkeeping and Reporting Requirements
    C. Requirements for Emission Reductions To Occur During the 
First Implementation Period and for a Compliance Schedule
    D. The CAA Section 110(l) Anti-Backsliding Provision
    E. Interstate Visibility Transport and Regional Haze Reasonable 
Progress Requirements
    F. Comments From Domtar
IV. Final Action
    A. Arkansas Regional Haze Phase III SIP Submittal
    B. Arkansas Visibility Transport
    C. CAA Section 110(l)
V. Incorporation by Reference
VI. 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, which strengthened the 
visibility protection program of the Act, 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 
restoring 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

[[Page 15106]]

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 to address visibility impacts for each source classified 
as subject-to-BART. These large, often under-controlled, older 
stationary sources are then required to procure, install, and operate 
the BART controls established in these determinations to reduce 
visibility impairment. The determinations 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) for the 
potential BART controls.\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 five statutory factors in determining BART controls 
are: (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 improvement in visibility which may reasonably be 
anticipated to result from the use of such technology.
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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). Among other things, the 
state must conduct an analysis of BART and the associated reductions 
for each source subject-to-BART covered by the alternative program, and 
compare the reductions and visibility improvements of the alternative 
program to what would have been achieved by 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. 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 the ``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.\13\ 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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    \13\ 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.

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

[[Page 15107]]

area.\14\ The RPGs established by the State provide an assessment of 
the visibility improvement anticipated to result for that planning 
period.\15\ 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.\16\ States have 
significant flexibility in establishing RPGs during the first planning 
period and must determine whether additional measures beyond BART are 
needed for reasonable progress. Under CAA section 169A(g)(1), once a 
set of potential control measures have been identified for a selected 
source, the State must collect data on and apply the four statutory 
factors that will be considered in selecting the measure(s) for that 
source that are necessary to make reasonable progress. The four 
statutory factors used to characterize potential emission controls are 
as follows: (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. A state planning to consider visibility benefits will 
also need to characterize those benefits (often referred to as the 5th 
factor).\17\ States must demonstrate in their regional haze SIPs how 
these factors are considered when selecting the controls for their 
long-term strategies and provide an assessment of the visibility 
improvement anticipated to establish RPGs for each applicable Class I 
area. This is commonly referred to this as the ``reasonable progress 
analysis'' or ``four-factor analysis.''
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    \14\ 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.
    \15\ 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).
    \16\ 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.
    \17\ 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.\18\ 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.\19\ 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 SIP.\20\ 
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.\21\ 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; Entergy22 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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    \18\ 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.
    \19\ See the final action on (March 12, 2012) (77 FR 14604).
    \20\ 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.
    \21\ See FIP final action on September 27, 2016 (81 FR 66332) as 
corrected on October 4, 2016 (81 FR 68319).
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    Following petitions for reconsideration and administrative stay 
submitted by the State, industry, and ratepayers, on April 14, 
2017,\23\ the EPA announced our decision to reconsider several elements 
of the FIP \24\ and 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 Phase I SIP 
submittal (the Arkansas Regional Haze NOX SIP revision) to 
address NOX BART requirements for all electric generating

[[Page 15108]]

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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    \23\ 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.
    \24\ Letter from E. Scott Pruitt, Administrator, EPA, to 
Nicholas Jacob Bronni and Jamie Leigh Ewing, Arkansas Attorney 
General's Office (April 14, 2017). A copy of this letter is included 
in the docket, https://www.regulations.gov/document?D=EPAR06-OAR-2015-0189-0240.
    \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. 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 30 The August 8, 2018, SIP also contained a 
discussion of the interstate visibility transport provisions, as 
discussed in more detail in Section I.H of this final action.
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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, DEQ 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 action 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 acting on the interstate 
visibility transport portion of the Arkansas Regional Haze 
SO2 and PM SIP revision in this final action.
    \30\ See 84 FR 51056 (September 27, 2019) for the final 
withdrawal action.
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G. Arkansas Regional Haze Phase III SIP Submittal

    On August 13, 2019, DEQ submitted the Arkansas Regional Haze Phase 
III SIP revision (Phase III SIP revision), which we are finalizing 
approval of in this action. This submittal contains an 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. At the time of SIP 
submittal and our proposed approval, the unit was permitted to burn 
only natural gas.\31\ It was 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 was not authorized to do so. It was equipped with a wet 
electrostatic precipitator (WESP) \32\ but the requirements to operate 
the WESP were removed when the permit was modified to combust natural 
gas only. In 2020, DEQ received a disconnection notice \33\ for Power 
Boiler No. 1 and it is now permanently retired. 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), and wood 
chips used to absorb oil spills. It is equipped with a traveling grate; 
\34\ a combustion air system that includes over-fire air; \35\ multi-
clones for PM10 removal; \36\ 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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    \31\ Power Boiler No. 1 operates as natural gas only subject to 
the Gas 1 subcategory defined under 40 CFR 63.7575. See DEQ Air 
Permit No. 0287-AOP-R22 (page 64) in the docket of this action.
    \32\ 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.
    \33\ See November 18, 2020 Disconnection Notice from Domtar for 
Power Boiler No. 1 (SN[hyphen]03) in the docket of this action.
    \34\ A traveling grate is a moving grate used to feed fuel to 
the boiler for combustion.
    \35\ 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.
    \36\ 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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    DEQ's original BART analyses and determinations (dated October 2006 
and March 2007) for Power Boilers No. 1 and 2 were included in the 2008

[[Page 15109]]

Arkansas Regional Haze SIP.\37\ In our 2012 partial approval/partial 
disapproval action, we approved DEQ's identification of these two units 
as BART-eligible; DEQ's determination that these units are subject-to-
BART; and DEQ's PM10 BART determination for Power Boiler No. 
1.\38\ 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),\39\ 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),\40\ and additional information provided by Domtar for the 
disapproved BART determinations. On March 20, 2018, Domtar provided DEQ 
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.\41\ In October 
2018, DEQ 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.\42\ 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. DEQ 
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, DEQ issued a final minor permit 
modification letter to Domtar,\43\ which included enforceable emission 
limitations and compliance schedules for the BART alternative.
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    \37\ 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.
    \38\ See the March 12, 2012 final action (77 FR 14604).
    \39\ 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.
    \40\ 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.
    \41\ 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.
    \42\ 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.).
    \43\ See DEQ 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.
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    DEQ submitted its third corrective regional haze SIP submittal to 
the EPA on August 13, 2019, which is the subject of this final action 
(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.\44\ With final 
approval of the Arkansas Regional Haze Phase III SIP revision in this 
action, DEQ now has a fully-approved regional haze SIP for the first 
implementation period. The Arkansas Regional Haze NOX SIP 
revision (Phase I SIP),\45\ the Arkansas Regional Haze SO2 
and PM SIP revision (Phase II SIP),\46\ and the Arkansas Regional Haze 
Phase III SIP revision together fully address all deficiencies of the 
2008 Arkansas Regional Haze SIP that EPA previously identified in the 
March 12, 2012 partial approval/partial disapproval action.\47\
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    \44\ See DEQ 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.''
    \45\ See final action approved on February 12, 2018 (83 FR 
5927).
    \46\ See final action approved on September 27, 2019 (84 FR 
51033) and the proposed approval on November 30, 2018 (83 FR 62204).
    \47\ The Arkansas Regional Haze Phase III SIP submittal did not 
revise any aspects of the previous Phase I or II SIP revisions.
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H. Arkansas Visibility Transport

    We are also addressing the interstate visibility transport element 
required under CAA section 110(a)(2)(D)(i)(II) in this final action 
from multiple SIP revisions for several NAAQS. 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.\48\ 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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    \48\ See the final rules promulgating the revised NAAQS: 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).

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[[Page 15110]]

     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 final approval. 
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.\49\ 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.
---------------------------------------------------------------------------

    \49\ 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).
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    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.\50\ On 
August 8, 2018, the State also included a discussion on visibility 
transport in its regional haze Phase II SIP revision, but we deferred 
taking action on the visibility transport requirements in that 
submittal too.\51\ In the Phase II SIP revision, the State considered 
all Class I areas in Arkansas and also considered those in Missouri, 
which is the only State that was determined to potentially be impacted 
by sources from within Arkansas for the first implementation period. 
Missouri is currently not relying on emission reductions from Domtar in 
its regional haze plan. DEQ 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 finalizing approval of 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 8, 2018, Phase II Arkansas 
Regional Haze SO2 and PM SIP revision \52\ 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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    \50\ 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).
    \51\ See 84 FR 51033, 51054 (September 27, 2019).
    \52\ 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 acting on the prong 4 portion of the 
Arkansas Regional Haze SO2 and PM SIP revision in this 
final action.
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II. Summary of Proposed Action and Our Final Decisions

    On March 16, 2020, we published a Notice of Proposed Rulemaking 
(NPRM) \53\ proposing to approve the Arkansas Regional Haze Phase III 
SIP revision submitted by DEQ on August 13, 2019. The SIP submittal 
addressed requirements of the Act and the Regional Haze Rule for 
visibility protection in mandatory Federal Class I areas for the first 
implementation period. The EPA proposed to approve an alternative 
measure to BART for SO2, PM, and NOX at the 
Domtar Ashdown Mill and elements of the SIP submittal that relate to 
these BART requirements at this facility. We are finalizing our 
determination in the NPRM that the Arkansas Regional Haze Phase III SIP 
revision meets all of the applicable regional haze BART alternative 
provisions set forth in 40 CFR 51.308(e)(2)(i) to (iv) for the Domtar 
Ashdown Mill. We are also finalizing our approval of specific plantwide 
permit provisions as the enforceable mechanism for the BART alternative 
emission limits and conditions for implementing the BART alternative. 
We are finalizing our approval of the reasonable progress components 
under 40 CFR 51.308(d) relating to Domtar Power Boilers No. 1 and 2. 
With the final approval of the BART alternative requirements for the 
Domtar Ashdown Mill in this action, DEQ has satisfied all long-term 
strategy requirements under section 40 CFR 51.308(d)(3). We also 
proposed to approve Arkansas' consultation with FLMs and Missouri and 
our determination that the SIP submittal satisfies the consultation 
requirements under 40 CFR 51.308(i)(2) and 40 CFR 51.308(d)(3)(i). We 
also agreed with DEQ's determination that the revised 2018 RPGs in the 
Phase II action do not need to be further revised. We proposed to 
approve Arkansas' request to withdrawal from the approved SIP the 
previously approved PM10 BART limit for Power Boiler No. 1. 
and the regional haze FIP provisions for the Domtar Ashdown Mill, and 
we are finalizing the withdrawal of those provisions in a separate 
rulemaking published elsewhere in this issue of the Federal Register.
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    \53\ See March 16, 2020 proposed approval (85 FR 14847).
---------------------------------------------------------------------------

    The EPA also proposed to approve in its NPRM Arkansas' interstate 
visibility transport provisions from the August 8, 2018, regional haze 
Phase II SIP submittal as supplemented by the visibility transport 
provisions in the October 4, 2019, interstate transport SIP submittal, 
which cover the following six NAAQS: The 2006 24-hour PM2.5 
NAAQS; the 2012 annual PM2.5 NAAQS; the 2008 and 2015 eight-
hour O3 NAAQS; the 2010 one-hour NO2 NAAQS; and 
the 2010 one-hour SO2 NAAQS. We are finalizing our approval 
of the prong 4 portions of these SIP submittals addressing CAA section 
110(a)(2)(D)(i)(II) for these NAAQS on the basis that with our approval 
of the Arkansas Regional Haze Phase III SIP revision in this notice, 
Arkansas has a fully-approved regional haze SIP. The Arkansas Regional 
Haze NOX SIP

[[Page 15111]]

revision,\54\ the Arkansas Regional Haze SO2 and PM SIP 
revision,\55\ and the Arkansas Regional Haze Phase III SIP revision 
together fully address the deficiencies of the 2008 Arkansas Regional 
Haze SIP that were identified in the March 12, 2012, partial approval/
partial disapproval action. As an alternative basis for approval of the 
State's CAA section 110(a)(2)(D)(i)(II) prong 4 submittals for these 
NAAQS, we are finalizing our determination that Arkansas has provided 
an adequate demonstration in the October 4, 2019 submittal that 
emissions within its jurisdiction do not interfere with other air 
agencies' plans to protect visibility.
---------------------------------------------------------------------------

    \54\ Final action approved on February 12, 2018 (83 FR 5927).
    \55\ See 83 FR 62204 (November 30, 2018) for proposed approval 
and 84 FR 51033 (September 27, 2019) for final approval.
---------------------------------------------------------------------------

    The public comment period for the NPRM closed on April 15, 2020. We 
received two sets of public comments concerning our proposed action. 
The comments are included in the publicly posted docket associated with 
this action at https://www.regulations.gov. We received a comment 
letter with adverse comments dated April 15, 2020, submitted on behalf 
of the National Parks Conservation Association, the Sierra Club, and 
Earthjustice regarding our proposed approval. We also received another 
comment letter dated April 15, 2020, from Domtar that was largely in 
support of our proposed approval. Below we provide a summary of the 
comments with our detailed responses. The complete comments can be 
found in the docket associated with this final rulemaking. After 
careful consideration of the public comments received, we have decided 
to finalize our action with no changes from the proposed action. For 
our complete, comprehensive evaluation of the Arkansas Regional Haze 
Phase III SIP revision, please refer to the proposed approval (See 85 
FR 14847). Our final actions regarding the NPRM are summarized in 
section IV of this notice.

III. Public Comments and EPA Responses

A. Demonstration That the BART Alternative Is Better-Than-BART

    Comment A.1: The BART alternative measure submitted by the State 
fails to demonstrate that the BART alternative achieves greater 
reasonable progress than BART. Rather than submit a revised BART 
analysis determination, DEQ's Arkansas Regional Haze Phase III SIP 
includes what it asserts are approvable SIP measures in a BART 
alternative for two subject-to-BART sources (Power Boilers No. 1 and 2) 
at the Domtar Ashdown paper mill located in Ashdown, Arkansas. Compared 
to BART, the BART alternative results in an overall (Power Boilers No. 
1 and 2) increase in sulfur dioxide (SO2) emissions and 
decrease in NOX emissions. While DEQ claims that the 
NOX decrease mitigates the SO2 increase, the SIP 
fails to demonstrate the BART alternative achieves greater reasonable 
progress than BART.
    Response: We disagree with the commenter's assertion that the BART 
alternative measure submitted by the State fails to demonstrate that 
the BART alternative achieves greater reasonable progress than BART.
    As explained in the proposed action, the BART alternative would 
result in an overall decrease in SO2, NOX, and 
particulate matter (PM10) emissions from the baseline for 
both power boilers at Domtar Ashdown paper mill. The BART alternative 
results in greater emission reductions of NOX and 
PM10 than the BART controls in the FIP. The BART alternative 
controls would reduce NOX and PM10 emissions by 
1,096 and 111 tons per year (tpy), respectively, from the baseline. The 
BART alternative results in a smaller reduction in 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. 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. Model results show that the additional reduction in 
NOX emissions under the BART alternative controls results in 
more overall modeled visibility improvement across the impacted Class I 
areas than BART even with the smaller reduction in SO2 
emissions.
    We explained in our proposed action that greater visibility 
improvement occurs because Domtar's baseline NOX emissions 
are the primary driver of visibility impacts from the source and 
contribute more to visibility impairment across the four-affected Class 
I areas in Arkansas and Missouri for Power Boiler No. 1, and also 
contribute more at Caney Creek for Power Boiler No. 2 than other 
pollutants emitted by the source. DEQ first included an analysis 
utilizing method 1 \56\ that shows that the BART alternative controls 
achieve greater overall cumulative reductions in visibility impairment 
(as expressed by the change in deciviews or [Delta]dv) from the 
baseline across the four Class I areas when compared to BART (0.549 
[Delta]dv for the alternative versus 0.473 [Delta]dv for BART). DEQ 
then determined that the BART alternative controls reduce the overall 
visibility impairment from the baseline by 0.520 [Delta]dv under its 
method 2 evaluation and is greater than the overall visibility 
improvement modeled under BART, which is 0.516 [Delta]dv. The DEQ noted 
that the most impacted Class I area, Caney Creek (1.137 dv baseline 
impairment), improved the greatest (0.384 [Delta]dv) with the BART 
alternative under 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.
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    \56\ Method 1 assessed visibility impairment on a per source per 
pollutant basis and Method 2 allowed for interaction of the 
pollutants from both boilers. See descriptions of method 1 and 2 
modeling evaluations in the March 16, 2020 proposed approval (85 FR 
14847, 14857-14858).
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    The State's weight of evidence analysis of visibility improvement 
in the SIP was supported by our analysis of various metrics, which 
reinforced that the BART alternative achieves greater reasonable 
progress. We analyzed the pollutant species contribution to visibility 
impacts at the Class I areas from each power boiler. Specifically, for 
Power Boiler No. 1, baseline modeled nitrate (NO3-) and 
nitrogen dioxide (NO2) impacts had 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. For Power Boiler 
No. 2, the visibility impacts resulting from NOX at Caney 
Creek outweigh SO42- species 
contributions (from SO2 precursors) to impacts at the other 
three Class I areas combined. In addition to pollutant species 
contributions to impacts, we also considered the ten highest impacted 
days.\57\ This analysis provided a broader look at those days with the 
highest impacts at each Class I area. The results were consistent with

[[Page 15112]]

the State's analysis based on the 98th percentile day, which was 
selected as representative of the highest impact (the 8th highest day). 
The average results across the top ten highest impacted days also 
supported our position that it is appropriate to give greater weight to 
Caney Creek impacts (0.9819 dv baseline impairment) in our 
consideration of whether the BART alternative achieves greater 
reasonable progress than BART since they are much larger than impacts 
at the other Class I areas. The BART alternative resulted 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 outweighed the difference in visibility 
benefit at the other three Class I areas altogether. On average, the 
BART alternative controls achieved 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). Our analysis of the ten highest impacted days 
similarly supported the conclusion that the BART alternative provides 
for greater reasonable progress than BART. Finally, we complemented the 
State's analysis by evaluating the modeled number of days impacted by 
Domtar over 1.0 dv and 0.5 dv for each scenario at each Class I area. 
This compared the frequency and duration of higher visibility impacts 
between the two control scenarios. The BART FIP limits and the BART 
alternative both reduce the total modeled number of days with 
visibility impacts over 1.0 dv from fifteen days in the baseline to 
four days for each scenario. For the metric of days with modeled 
visibility impacts over 0.5 dv, the FIP limits and the BART alternative 
showed nearly identical reduction in the number of days, but very 
slightly favored the FIP limits over the BART alternative (from 82 to 
36 days for the FIP limits compared to 37 days for the BART 
alternative). This single metric, however, on which BART performed 
slightly 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. These different metrics reinforce the State's 
analysis in the SIP that greater reasonable progress was achieved by 
the BART alternative.\58\
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    \57\ The ``ten highest impacted days'' means the 8th to 17th 
highest days at each Class I area. The 98th percentile means that 
for a given distribution, it is equal to or higher than 98 percent 
of the rest of the distribution. The 98th percentile impact day 
means that only two percent of the 365 days in a calendar year, or 
7.3 days (rounded up to 8 days) have higher impacts. The simplified 
chemistry in the CALPUFF model tends to magnify the actual 
visibility effects of that source so it is appropriate to use the 
98th percentile, or 8th highest day, to not give undue weight to the 
extreme tail of the distribution. This approach will effectively 
capture the sources that contribute to visibility impairment in a 
Class I area, while minimizing the likelihood that the highest 
modeled visibility impacts might be caused by unusual meteorology or 
conservative assumptions in the model. See 70 FR 39104, 39121 (July 
6, 2005), Regional Haze Regulations and Guidelines for BART 
Determinations.
    \58\ See discussion regarding the different metrics in the March 
16, 2020 proposed approval (85 FR 14847, 14859-14860).
---------------------------------------------------------------------------

    The State's weight of evidence analysis of emission reductions and 
visibility improvement (using the 98th percentile metric) as 
complemented by our analysis of different metrics, justify our approval 
of the State's determination that the BART alternative achieves greater 
reasonable progress than BART under 40 CFR 51.308(e)(2)(i)(E). The 
State followed the prescribed process for determining the level of 
control required for the BART alternative for the Domtar Ashdown Mill 
and adequately supported its determination with analysis that meets the 
requirements under section 40 CFR 51.308(e)(2).
    Comment A.2: EPA proposes approving the Arkansas Regional Haze 
Phase III SIP and relaxing the BART emission limitations established in 
its 2016 FIP. The proposed facility-wide emission limitation would 
allow for fewer emission reductions from the Domtar Ashdown Mill. EPA's 
proposal reverses course on its FIP, failing to make reasonable 
progress on reducing visibility impairment in Class I areas in 
accordance with the CAA mandates and requirements.
    Response: The BART alternative establishes pollutant-specific 
limits at each of the two BART sources at the Ashdown Mill. There is no 
``facility-wide emission limitation'' as stated by the commenter. In 
addition, we disagree with the commenter that the EPA is reversing 
course on its FIP by relaxing BART limitations established in the FIP, 
and thus failing to make reasonable progress and reduce visibility 
impairment in Class I areas in accordance with the CAA and its 
mandates.
    The BART alternative results in larger reductions in NOX 
and PM emissions than required by the FIP, while SO2 
emissions are not reduced to the same extent as would be required under 
the FIP. As explained in our response to comment A.1 of this final 
action and also in section IV of our proposed action, our analysis of 
the State's weight of evidence conclusion as complemented by EPA's 
analysis, demonstrate that the State has met the BART and reasonable 
progress requirements for regional haze under the applicable provisions 
of the CAA and the Regional Haze Rule. Thus, the proposed withdrawal of 
the BART provisions in the FIP and replacement with the BART 
alternative requirements in the SIP will not result in a failure to 
meet the applicable requirements.
    The Arkansas Regional Haze Phase III SIP revision and concurrent 
withdrawal of the corresponding parts of the FIP pertaining to Domtar 
will also not reverse course from the prior FIP with respect to the 
separate reasonable progress requirements for Arkansas. As mentioned in 
section IV of our proposed action, we determined in our September 27, 
2019 Arkansas Regional Haze SO2 and PM SIP revision that 
Arkansas had fully addressed the reasonable progress requirements under 
40 CFR 51.308(d)(1) for the first implementation period in that final 
action. In that action, we also noted that the 2016 FIP BART 
determination requirements for Domtar were still in place but we agreed 
with the State that as long as those requirements continued to be 
addressed by the measures in the FIP, nothing further is needed to 
satisfy the reasonable progress requirements for the first 
implementation period. In the Arkansas Regional Haze Phase III SIP 
submittal, the State assessed whether changes would be needed with 
respect to the reasonable progress analysis, based on any differences 
between the SIP and FIP-based measures for Domtar. The BART alternative 
analysis performed for the Domtar power boilers was based, in part, on 
an assessment of the same factors that must be addressed in the 
reasonable progress analysis. The FIP BART determination analysis was 
compared to the proposed BART alternative controls in the Arkansas 
Regional Haze Phase III SIP submittal. The BART alternative measures 
for Domtar resulted in greater overall visibility improvement than the 
BART requirements in the FIP and the previously approved BART 
PM10 limit for Power Boiler No. 1. As a result, nothing 
further is needed to satisfy the reasonable progress requirements for 
the first implementation period. For these reasons, approval of the 
Arkansas Regional Haze Phase III SIP revision and concurrent withdrawal 
of the corresponding parts of the FIP do not interfere or reverse 
course from the FIP with respect to the CAA requirements pertaining to 
BART or reasonable progress under 40 CFR 51.308(d) or (e).
    Comment A.3: EPA's proposal cobbles together two pieces of 
information (a comparison of emission reductions and a modeling 
analysis) and fails to demonstrate that the BART alternative is clearly 
better than BART. The Regional Haze Rule provides different regulatory 
tests for a state to use to demonstrate that a BART alternative is 
better than BART. Arkansas claims that it used the ``clear weight of 
evidence test,'' but the information it provides falls under 40 CFR 
51.308(e): An emission reduction comparison and modeling. The 
information Arkansas provides fails to meet the requirements in 40 CFR 
51.308(e). Therefore, it is

[[Page 15113]]

unreasonable for EPA to provide weight to the information.
    Response: We disagree with the commenter's assertion that the 
information on which our approval of the State's SIP is based fails to 
provide an adequate clear weight of evidence analysis to meet the 
requirements in 40 CFR 51.308(e). The commenter is apparently alleging 
that the analysis provided by the State instead falls under 40 CFR 
51.308(e)(3) rather than under 40 CFR 51.308(e)(2)(i)(E) because it is 
based on an emission reduction comparison and modeling. The argument 
that the kind of data and analysis to be used under the clear weight of 
evidence test must somehow be sufficiently different from what would be 
required under 40 CFR 51.308(e)(3) is not a reasonable interpretation 
of these regulations. EPA interprets 40 CFR 51.308(e)(2)(i)(E) as 
permitting data and analysis that may be relevant under 40 CFR 
51.308(e)(3) analysis to be used in supporting a clear weight of 
evidence demonstration.
    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. The State relied on a modeling analysis 
to determine if the BART alternative could be shown to make greater 
reasonable progress than BART, but that modeling was different than the 
modeling described under 40 CFR 51.308(e)(3). 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 overall visibility conditions for the twenty percent 
best and worst days, as would be required under 40 CFR 51.308(e)(3). 
The State's approach could be considered a modified version of the two-
part modeling test under 40 CFR 51.308(e)(3) and is more appropriate to 
classify under the weight of evidence analysis approach instead allowed 
under 40 CFR 51.308(e)(2)(i)(E).
    The State's methodology and analysis under the clear weight of 
evidence test is reasonable. The State's CALPUFF modeling approach 
utilizing the 98th percentile visibility impacts is consistent with the 
approach recommended by the BART guidelines \59\ for comparing 
different control options at a single source when developing BART 
determinations relying on the 98th percentile visibility impact as the 
key metric. It is also consistent with the methodology followed in 
EPA's 2016 FIP BART determination 60 61 for Domtar.
---------------------------------------------------------------------------

    \59\ See 40 CFR 51 Appendix Y section III.A.3 and IV.D.5, 
``Guidelines for BART Determinations Under the Regional Haze Rule.''
    \60\ See proposed FIP on April 8, 2015 (80 FR 18979).
    \61\ 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.
---------------------------------------------------------------------------

    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. This approach is, therefore, 
acceptable and reasonable for the comparison of the proposed BART 
alternative to the FIP BART determination 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. The State 
also considered two methods of modeling evaluation provided by Domtar 
for this approach of using the maximum 98th percentile visibility 
impact. Method 1 assessed visibility impairment on a per source per 
pollutant basis and method 2 allowed for interaction of the pollutants 
from both boilers. 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. Only 
the modeled emission rates changed to represent the modeled scenarios 
for each method.
    DEQ determined that the visibility benefits as measured under 
method 2 and the previous FIP BART determination formed an appropriate 
BART benchmark for the purposes of the evaluation of Domtar's BART 
alternative. We continue to agree with DEQ that because method 2 
provides for the full chemical interaction of emissions from both power 
boilers, method 2 analysis results are a reliable assessment of the 
anticipated overall visibility improvement of controls utilizing the 
98th percentile impact. Under the weight of evidence approach, we made 
use of all available information and data which could inform our 
decision while recognizing the relative strengths and weaknesses of 
that information in arriving at the soundest decision possible.\62\ 
This array of information and other relevant data was of sufficient 
quality to inform our comparison of visibility impacts between BART and 
the BART alternative. We carefully considered this evidence in 
evaluating the Arkansas Phase III SIP revision submitted by the State. 
Overall, the difference in visibility impacts between the BART and the 
BART alternative scenarios was large enough to show that the BART 
alternative achieves greater reasonable progress than BART based on the 
clear weight of the evidence.
---------------------------------------------------------------------------

    \62\ 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.
---------------------------------------------------------------------------

    As explained in response to comment A.1 in section III.A of this 
final action, we evaluated DEQ's analysis and additional model results 
(relying primarily on the analysis of the 98th percentile impacts),\63\ 
the analysis of emission reductions,\64\ and the analysis of Domtar's 
visibility impacts due to NO3- compared to 
SO4-.\65\ In addition, we also considered our analysis of 
the ten highest impacted days (8th to 17th highest) \66\ and our 
analysis of the number of days impacted over 0.5 dv and 1.0 dv.\67\ All 
of these metrics, except the number of days impacted over 0.5 dv (which 
only very slightly favored BART), provided substantial evidence and 
collectively supported the conclusion that the BART alternative 
provides for greater reasonable progress than BART. For these reasons, 
we are finalizing our approval of the State's weight of evidence 
analysis approach and the conclusions reached by the State. In the 
course of evaluating the SIP submittal, EPA developed some additional 
analysis that complements and supports

[[Page 15114]]

the State's analysis. Taken as a whole, the record supports approval of 
the State's determination that the BART alternative achieves greater 
reasonable progress than BART under the clear weight of evidence 
pursuant to 40 CFR 51.308(e)(2)(i)(E).
---------------------------------------------------------------------------

    \63\ See Tables 7 and 8 of the proposed approval, 85 FR 14847, 
14858.
    \64\ See Tables 5 and 6 of the proposed approval, 85 FR 14847, 
14856-14857.
    \65\ 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.
    \66\ See 85 FR 14847, 14859. 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.
    \67\ See 85 FR 14847, 14860. 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.
---------------------------------------------------------------------------

    Comment A.4: EPA fails to provide a basis to rely on a comparison 
of emissions. EPA merely presents the emission reductions under BART 
and the alternative, but fails to explain the strengths and weaknesses 
of this information and does not assign any weight to the emission 
comparison. A comparison of multiple pollutant species emission levels 
alone is not informative without visibility modeling. The pollutants' 
differing visibility impacts and complex interactions between them and 
in the atmosphere make it extremely difficult to discern their 
collective impacts without visibility modeling. EPA has consistently 
relied on modeling to assess the visibility impacts under these 
circumstances.
    Response: We disagree with the commenter's assertion that EPA 
``merely presents the emission reductions under BART and the 
alternative.'' In our proposed action,\68\ our basis for presenting the 
emission reduction information laid the foundation for describing the 
differences in visibility outcomes achieved between the FIP and the 
BART alternative, leading EPA to agree with the State that there was a 
need to support the BART alternative with visibility modeling. The 
State first showed reduced emissions from the baseline and then used 
the modeling to support a conclusion that the emission reduction 
differences between the FIP BART benchmark and BART alternative were 
acceptable because NOX precursor emissions are the main 
driver contributing to the visibility impacts from this source. Thus, 
the State proceeded to conduct precisely the modeling analysis the 
commenter seems to assert is required, using CALPUFF. Indeed, 
recognizing the potential interaction between multiple species of 
visibility pollutants, the State used Method 2 in evaluating the 
visibility consequences of the BART alternative compared to the BART 
benchmark. EPA has relied on the modeling submitted by the State in 
reaching a conclusion that the SIP submittal is approvable. While EPA 
does not concede that modeling is required in all cases to conduct an 
approvable ``clear weight of evidence'' analysis under 
51.308(e)(2)(i)(E), modeling was in fact done in this instance to 
support the analysis. This comment is thus premised on a 
misunderstanding of the record.
---------------------------------------------------------------------------

    \68\ 85 FR 14847, 14857.
---------------------------------------------------------------------------

    To the extent the commenter is asserting that the emissions 
comparisons alone cannot be used as even one part of a weight of 
evidence demonstration, the commenter is mistaken in how a ``weight of 
evidence'' analysis is conducted. The term ``weight'' connotes that 
multiple pieces of evidence are brought together and analyzed as a 
whole.\69\ Comparative emissions data is obviously a critical piece of 
that evidentiary record, and provides a foundation on which further 
analysis, such as modeling, may be conducted. To assert that EPA must 
ignore emissions comparisons--or any single piece of evidence--because 
it does not provide, on its own, a sufficient basis to make a ``weight 
of evidence'' determination is both illogical and a misreading of EPA's 
regulations. We also note that the regulations require an analysis of 
emission reductions under BART and the alternative, see 40 CFR 
51.308(e)(2)(i)(C) and (D).
---------------------------------------------------------------------------

    \69\ See 71 FR 60612, 60622 (October 13, 2006).
---------------------------------------------------------------------------

    Comment A.5: EPA should not provide weight to modeling data of 
insufficient quality, which fails to meet the requirements of the 
regulations. It is disingenuous for EPA to suggest that the CALPUFF 
model is a ``modified'' version of the two-part modeling test. EPA has 
consistently interpreted the two-part dispersion modeling test under 40 
CFR 51.308(e)(3) to mean the Comprehensive Air Quality Model with 
Extensions (CAMx) model, and not CALPUFF. EPA and states have 
consistently used CAMx to assess whether a BART alternative would 
result in ``greater reasonable progress'' under the two-prong test. 
CAMx and CALPUFF are vastly different models and 40 CFR 51.308(e)(3) 
requires a specific type of dispersion modeling. EPA's suggestion that 
use of CALPUFF is acceptable because it ``is consistent with the 
approach recommended by the BART guidelines for comparing different 
control options at a single source when developing BART determinations 
relying on the 98th percentile visibility impact as the key metric'' 
also fails. A comparison of control options at a single source compares 
changes in the emission reductions in one pollutant, but does not 
compare the complexities involved in analyzing interactions between 
multiple pollutants. It is also irrelevant that only the BART sources 
at Domtar are under consideration. While the FIP considered each 
pollutant separately, the alternative attempts to analyze and take 
credit for combined emission reductions from three pollutants as it 
fails to actually assess the effect of the alternative on visibility as 
compared to BART.
    Response: We disagree with the comment that CAMx must be used for 
the two-part test under 40 CFR 51.308(e)(3) or that CALPUFF cannot be 
used to support the determination here, which is not under 40 CFR 
51.308(e)(3) in any case. The first point is irrelevant because the 
State is not proceeding under 40 CFR 51.308(e)(3); however, it is worth 
noting that the regulatory text does not require the use of CAMx. 
CALPUFF is also an air dispersion model, and one that the Agency has 
recognized as available for use for BART alternatives under 40 CFR 
51.308(e)(3).\70\
---------------------------------------------------------------------------

    \70\ See 71 FR 60612, 60616.
---------------------------------------------------------------------------

    Regarding the use of CALPUFF, we did not suggest that CALPUFF was 
replacing CAMx under 40 CFR 51.308(e)(3). We logically examined the 
two-part analysis under 40 CFR 51.308(e)(3) in the proposed action to 
show how the State arrived at classifying the approach as a weight of 
evidence approach. Our choice of using the term ``modified'' to 
describe the relationship of this analysis to the two-part test under 
40 CFR 51.308(e)(3) was intended to describe how the State's approach 
was similar to 40 CFR51.308(e)(3) in considering distribution of 
emissions and visibility improvements using modeling, but different 
from 40 CFR 51.308(e)(3) because the analysis based on the CALPUFF 
modeling focused on the 98th percentile visibility impacts instead of 
the twenty percent best and worst days required by 40 CFR 51.308(e)(3). 
Therefore, the State's weight of evidence analysis is acceptable under 
40 CFR 51.308(e)(2)(i)(E) and should not be judged according to 40 CFR 
51.308(e)(3). The commenter's objection to 40 CFR 51.308(e)(3) not 
being met is immaterial since the weight of evidence approach followed 
in the SIP submittal does not fall under 40 CFR 51.308(e)(3) but under 
40 CFR 51.308(e)(2)(i)(E).
    The commenter states that EPA is wrong to consider CALPUFF as 
acceptable just because it ``is consistent with the approach 
recommended by the BART guidelines for comparing different control 
options at a single source when developing BART determinations relying 
on the 98th percentile visibility impact as the key metric.'' The 
commenter points out that a comparison of control options at a single 
source compares changes in the emission reductions in one pollutant,

[[Page 15115]]

but does not compare the complexities involved in analyzing 
interactions between multiple pollutants. We disagree with this point 
in relation to the alternative analysis here. First, particularly for 
purposes of a BART alternative analysis for a single facility (with two 
BART units), EPA's regulations recognize CALPUFF to be an acceptable 
model, (explaining that CALPUFF is particularly suited for BART and 
BART alternative applications at a single source).\71\ Further, Method 
2, incorporated by the State in its SIP submittal, is a full assessment 
method where all sources and pollutants are combined into a single 
CALPUFF 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. It is because of this that method 2 
analysis results are a more reliable assessment of the anticipated 
overall visibility improvement of controls under each scenario. Thus, 
this is an entirely suitable application of the CALPUFF model, and the 
commenter is incorrect to state that the CALPUFF modeling did not 
account for the interactive chemistry of visibility pollutants.
---------------------------------------------------------------------------

    \71\ See 71 FR 60616.
---------------------------------------------------------------------------

    EPA recognizes that the CALPUFF model includes simplified chemistry 
to account for interactions between pollutants. The simplified 
chemistry tends to magnify the actual visibility effects of a single 
source; thus, it is appropriate to use the 98th percentile to avoid 
overprediction and not give undue weight to the extreme tail of the 
distribution. This approach will effectively capture the sources that 
contribute to visibility impairment in a Class I area, while minimizing 
the likelihood that the highest modeled visibility impacts might be 
caused by unusual meteorology or conservative assumptions in the model.
    The EPA has previously recognized this approach of using CALPUFF as 
an acceptable approach in the past when analyzing BART alternatives 
that only include emission reductions at a single or small group of 
BART sources. Specifically, we approved this approach for the State of 
Arizona which established a BART alternative for Steam Units 2 and 3 at 
Arizona Electric Power Cooperative's Apache Generating Station.\72\ See 
also 70 FR 60616 (recognizing CALPUFF as particularly appropriate for 
single-source applications).
---------------------------------------------------------------------------

    \72\ See Arizona's September 19, 2014 proposed approval (79 FR 
56322) which was finalized on April 10, 2015 (80 FR 19220).
---------------------------------------------------------------------------

    The commenter states that the FIP considered each pollutant 
separately, whereas the alternative attempts to analyze and take credit 
for combined emission reductions from three pollutants, which allegedly 
fails to assess the effect of the alternative on visibility as compared 
to BART. The commenter is incorrect in their premise. The CALPUFF 
modeling in the FIP evaluated each unit separately, but modeled the 
visibility impacts from all pollutants from that unit. For example, in 
evaluating the visibility benefit from NOX controls on Power 
Boiler No. 1, the NOX emissions varied between each control 
scenario modeled, while the SO2 and PM emissions were 
included but held constant in these NOX control scenarios. 
In evaluating the BART alternative, the State provided EPA with two 
separate methods of using the CALPUFF modeling to evaluate visibility 
impacts of the BART alternative as compared to BART, including Method 2 
(described above) that modeled all pollutants from both BART units to 
assess the total visibility impact from these two units.
    For these reasons, we disagree that the modeling data was of 
insufficient quality and failed to meet the requirements of the 
regulations.
    Comment A.6: EPA lacks authority to give one Class I area more 
weight than others. EPA suggests that it is reasonable to give one of 
the Class I areas ``greater weight'' when considering visibility 
benefits and cherry-picks the Class I area with the greatest visibility 
improvement, which is closest to Domtar. Focusing on that Class I area 
serves to support a source's preferred control outcome. Showing that 
one Class I area will have greater visibility benefits does nothing to 
tip the weight of evidence scale in favor of the BART alternative. It 
merely shows one area will see more benefits. In addition, EPA fails to 
provide a basis for applying the 0.5 deciview threshold used by the 
State to determine if a source contributes to visibility impairment at 
a Class I area with the BART alternative analysis.
    Response: We disagree with the commenter's assertion that EPA 
``cherry picks'' the Class I areas with the greatest visibility 
improvement. We considered many metrics in analyzing the weight of 
evidence approach by the State, including the overall visibility 
improvement on average across the four impacted Class I areas. As a 
whole, these factors supported a conclusion that the BART alternative 
achieves greater reasonable progress than BART at the subject facility. 
One metric that we analyzed was the breakdown of pollutant speciation 
impacts across each Class I area due to modeled emissions from each 
power boiler. We highlighted impacts at Caney Creek specifically in 
this analysis because Domtar's Ashdown facility impacts this Class I 
area the greatest, and this is due to NOX emissions from 
Power Boiler No. 2. We also found that NOX emissions 
contributed more to visibility impairment across all four Class I areas 
for Power Boiler No. 1. The greater impact due to NOX 
emissions is relevant because it demonstrates that the higher 
SO2 emissions allowed under the BART alternative is offset 
by the larger reduction in NOX emissions. This is just one 
factor among many that we considered in analyzing the State's weight of 
evidence approach as explained in the proposed approval and in 
preceding responses in this final approval. We took into account the 
visibility impacts at all impacted Class I areas (individually and on 
average) and did not solely focus on the benefits at the most impacted 
area.
    We disagree with the assertion that we are supporting the source's 
preferred control outcome instead of addressing emissions cumulatively 
across all Class I areas. The commenter points out that the court in 
Nat'l Parks Conservation Ass'n v. EPA held that EPA's analysis in 
reviewing SIP submittals must take into account the visibility impacts 
at all impacted Class I areas rather than focusing solely on the 
benefits at the most impacted areas, 803 F.3d 151, 165 (3d Cir. 2015). 
However, the facts of Nat'l Parks Conservation Ass'n v. EPA, are not 
analogous to the facts surrounding our proposed approval. In Nat'l 
Parks Conservation Ass'n v. EPA, the court was reviewing EPA's approval 
of the state's assessment of the visibility-improvement factor within 
the five-factor BART analysis. The state calculated visibility 
improvement that could be achieved at Class I areas by implementing 
additional controls at BART-eligible sources.\73\ The state's 
calculations for each source, however, took into account only the 
potential impact such controls would have on the visibility in the 
Class I area most severely impacted by the source. The state did not 
consider ``cumulative visibility impact,'' which the EPA itself had 
conceded was improper under the

[[Page 15116]]

visibility BART factor.\74\ The court in NPCA rejected that this flaw 
in the State's analysis could be dismissed as harmless error.\75\
---------------------------------------------------------------------------

    \73\ Id. at 164.
    \74\ Id. at 165.
    \75\ Id. at 167.
---------------------------------------------------------------------------

    In this action, by contrast, both the State and EPA have evaluated 
the cumulative visibility impacts across all of the affected Class I 
areas. The State considered this with both of its methods of analysis, 
and EPA coupled those results with our own analysis of cumulative 
visibility improvement. DEQ first included an analysis utilizing method 
1 that shows that the BART alternative controls achieve greater overall 
cumulative reductions in visibility impairment 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). DEQ 
also determined using method 2 that the BART alternative controls 
reduce the overall cumulative visibility impairment from the baseline 
by 0.520 [Delta]dv, which is greater than the overall visibility 
improvement modeled under BART, which is 0.516 [Delta]dv. We 
complemented the State's analysis by comparing the average visibility 
impact across the top ten highest impacted days at each Class I area 
(average 8th to 17th highest). This analysis provided a broader look at 
those days with the highest impacts at each Class I area. The results 
were consistent with the State's analysis based on the 98th percentile 
day, which was selected as representative of the highest impact (i.e., 
the 8th highest day). 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). Thus, visibility benefits at each 
Class I area were considered and analyzed by multiple metrics that 
confirmed our proposed approval of the alternative.
    The commenter argues that EPA ``fails to provide a basis for 
applying the 0.5 deciview threshold used by the State to determine if a 
source contributes to visibility impairment at a Class I area with the 
BART alternative analysis,'' noting that numerous BART determinations 
relied on lower deciview thresholds that resulted in significant 
emission reducing outcomes. The meaning of this comment is not clear. 
EPA did not apply a 0.5 deciview threshold to cut off its evaluation of 
other Class I areas. However, it is reasonable to provide additional 
analysis when one Class I area is much more heavily impacted by a 
source than others. In the case of Domtar, the baseline visibility 
impacts at Caney Creek are much larger than impacts at the other Class 
I areas, so it is reasonable to give greater weight to visibility 
benefits at Caney Creek resulting from the alternative as compared to 
BART. The level of visibility benefit from controls at the other three 
Class I areas are smaller than those at Caney Creek, and the baseline 
visibility impacts of the source at these areas was 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. In making this observation, we 
do not categorically dismiss or ignore impacts to other Class I areas 
below 0.5 or any other threshold. We simply note that the changes in 
visibility at these other Class I areas were individually very small 
and collectively smaller than the comparative gain in visibility 
achieved by the BART alternative at Caney Creek.
    The commenter mentioned that Congress provided no authority for EPA 
to treat one Class I area differently from others. As mentioned 
previously, we treated all Class I areas the same and measured the 
cumulative visibility impacts across all of them using multiple 
metrics. We specifically analyzed the effects at Caney Creek, since it 
is the Class I area impacted the most. But that analysis does not show 
favoritism and merely provides one metric for interpreting how impacts 
are correlated to overall emissions from the source at each Class I 
area.

B. Monitoring, Recordkeeping and Reporting Requirements

    Comment B.1: EPA lacks authority to approve the State's SIP 
submission with respect to provisions pertaining to alternative test 
methods. EPA proposes to allow the State to authorize alternative 
sampling or monitoring methods (equivalent to methods in the permit) 
that EPA would concur on, outside the SIP process. Specifically, EPA 
proposes approving permit conditions 35 and 42 as a part of the SIP. 
Neither the State's SIP nor EPA's proposal explains what criteria and 
process EPA would use to approve an alternative method. Arkansas' 
alteration or elimination of SIP requirements can have no effect for 
purposes of federal law unless and until EPA ratifies that action with 
a SIP revision that is subject to the SIP requirements, including 
provisions for public notice and comment. Moreover, the monitoring, 
recordkeeping and reporting provisions in the State's SIP are not 
approvable and therefore, those methods cannot be used a basis for 
assessing whether an alternative method is approvable. Based on 
Arkansas' SIP provisions, there is no way for the public to assess 
whether an alternative method will comply with the Act. Therefore, EPA 
should not approve these provisions because they are inconsistent with 
the requirements of CAA section 110(i), 110(l) and 110(k)(3).
    Response: We recognize that the commenter raises a concern that the 
State's ability to authorize (with EPA concurrence) alternative test 
methods in conditions 35 and 42 may be inconsistent with the Act 
insofar as ``[n]either the State's SIP nor EPA's proposed approval 
explains what criteria and process EPA would use to approve an 
alternative method.'' In general, EPA agrees that SIP provisions cannot 
authorize a State to make changes in the EPA-approved and federally 
enforceable SIP requirements applicable to sources without going 
through the statutorily required SIP-revision process. EPA refers to 
SIP provisions that purport to authorize States to make unilateral 
changes to existing SIP requirements as impermissible ``director's 
discretion'' provisions. However, EPA interprets the CAA to allow two 
types of such provisions: (i) Where the provision provides director's 
discretion for the State to make changes, but specifies that such 
changes have no effect for purposes of federal law or alter SIP 
requirements unless and until the EPA approves the changes through a 
SIP revision pursuant to CAA requirements; or (ii) where the provision 
provides director's discretion that is adequately bounded, such that at 
the time EPA approves the SIP provision the agency can evaluate it for 
compliance with applicable CAA requirements and evaluate the potential 
impacts of the State's exercise of that discretion. EPA interprets CAA 
section 110(i) to allow SIP provisions with director's discretion of 
either type. In the case of an adequately bounded provision, EPA 
considers such provisions consistent with section 110(i) because, at 
the time of initial approval into the SIP, the agency will already have 
evaluated the provision for compliance with applicable requirements and 
evaluated the potential impacts from exercise of the discretion. By 
their terms, conditions 35 and 42 do not specify that DEQ must seek a 
SIP revision to change the required monitoring at the source. Thus, to 
be approvable, EPA would have to determine that the State's discretion 
in these provisions is adequately bounded and assess the potential 
impacts from the exercise of that authority.

[[Page 15117]]

    In response to the commenter's concerns, EPA has further evaluated 
conditions 35 and 42 to determine whether they provide adequate 
bounding, allowing EPA to assess the provisions for compliance with 
applicable requirements and the potential impacts that could result 
from DEQ's potential exercise of the discretion to authorize 
alternative monitoring. In support of EPA's proposed approval of 
plantwide conditions 35 and 42 into the Arkansas SIP, DEQ provided 
additional information in a letter (dated December 3, 2020) to EPA to 
clarify the process and standards that the State shall follow and apply 
to approve the use of any alternative method under plantwide conditions 
35 and 42 of the Domtar permit.\76\ DEQ notes in the letter that DEQ 
has received a disconnection notice \77\ for Power Boiler No. 1 and 
that it is now permanently retired. In accordance with plantwide 
condition 34, Power Boiler No. 1 is in compliance with the BART 
alternative limits by virtue of being permanently retired and, 
therefore, not emitting any of the relevant visibility pollutants. The 
numerical emission limits will still apply, even though the unit has 
been taken out of service. As a result, the process to be used by DEQ 
in its approval of any request for an alternative sampling or 
monitoring method is only applicable to Power Boiler No. 2 under 
plantwide condition 42.
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    \76\ See December 3, 2020 clarification letter to EPA from DEQ 
posted in the docket of this action.
    \77\ See November 18, 2020 Disconnection Notice from Domtar for 
Power Boiler No. 1 (SN-03) in the docket of this action.
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    For Power Boiler No. 2, which currently relies on a continuous 
emissions monitoring system (CEMS) to monitor SO2 and 
NOX emissions, DEQ explained in its letter that it will use 
the criteria for alternate monitoring systems contained in 40 CFR part 
75, subpart E in its evaluation of the approvability of any request for 
an alternative sampling or monitoring method for SO2 and 
NOX emissions. More specifically, the State explained that 
any request for approval of an alternative sampling or monitoring 
method under plantwide condition 42 shall meet the general 
demonstration requirements for alternative monitoring systems under 40 
CFR 75.40 and require Domtar (or the current owner of the Ashdown Mill) 
to demonstrate adequately that the average hourly emission data for 
SO2, NOX, and/or volumetric flow in the proposed 
alternative sampling or monitoring has the same or better precision, 
reliability, accessibility, and timeliness as that provided by the 
currently applicable continuous emission monitoring system (see 
criteria in 40 CFR 75.41-75.46). Furthermore, DEQ will require all 
information in 40 CFR 75.48 of Domtar (or the current owner of Ashdown 
Mill) in the application for certification or recertification of the 
alternative monitoring system. DEQ notes that the requirements of 40 
CFR part 75, subpart E shall be met by the alternative monitoring 
system when compared to a contemporaneously operating, fully certified 
continuous emission monitoring system or a contemporaneously operating 
reference method, where the appropriate reference methods are listed in 
40 CFR 75.22.
    With respect to any request for alternative sampling or monitoring 
methods for PM10 under plantwide condition 42, we note that 
Power Boiler No. 2 is subject to 40 CFR part 63, subpart DDDDD and 
reference is made to those requirements for PM10 compliance 
demonstrations in plantwide condition 41. Condition 41 clearly explains 
that the applicable PM10 compliance demonstration 
requirements from 40 CFR part 63 subpart DDDDD shall be utilized by 
Domtar (or the current owner of Ashdown Mill). These requirements, 
which are at 40 CFR 63.7505--63.7541, do not cease and are ongoing. In 
response to comment B.8 in section III of this final action, we address 
the alternative option provided in the permit for monitoring emissions 
from Power Boiler #2 when that unit is combusting natural gas.
    DEQ explained in its letter that it expects that Domtar will work 
with both DEQ and EPA in the development of equivalent testing 
protocols before seeking approval from DEQ (with EPA concurrence) and 
before performing the equivalency testing. The alternate sampling or 
monitoring protocol submittal to DEQ must contain EPA's official letter 
of documented recommendations and concurrence, as required for DEQ 
approval. Although not the same as EPA approval of an alternative 
sampling or monitoring requirement through a SIP revision, in the case 
of a valid director's discretion provision that is already adequately 
bounded, EPA considers the inclusion of consultation with EPA an extra 
measure of assurance that any such alternative will be appropriate. 
Given the process that DEQ will follow and standards that DEQ will 
apply in evaluating any potential alternative (and EPA's consultation 
in the process) EPA anticipates that DEQ's exercise of its well bounded 
discretion to authorize alternative sampling or monitoring will not 
result in adverse impacts, e.g., adverse impacts on regional haze 
requirements that are relevant to this SIP submission.
    Based on the information contained in DEQ's December 3, 2020, 
letter which forms a critical part of the record basis for EPA's 
approval of this submittal, EPA has determined that conditions 35 and 
42 as supplemented by the letter are adequately bounded director's 
discretion provisions. In particular, EPA agrees with DEQ that the 
criteria in 40 CFR part 75, subpart E for SO2 and 
NOX emissions and in 40 CFR part 63, subpart DDDDD for 
PM10 emissions are appropriate to evaluate the approvability 
of any alternative sampling or monitoring methods and establish the 
proper bounds for DEQ's exercise of discretion and EPA approval for any 
future requests from the source to use alternative sampling and 
monitoring methods. Further, in determining whether it is appropriate 
for EPA to provide its concurrence to any future request for a change 
in sampling and monitoring methods under these conditions, EPA reserves 
the right to withhold its concurrence if EPA determines that the 
request falls outside the process and bounds specified in DEQ's letter. 
In such circumstances, the CAA would require that the State seek to 
make the change through the normal SIP revision process.
    For these reasons, these permit provisions are consistent with the 
requirements of CAA sections 110(i), 110(l) and 110(k)(3).
    Comment B.2: The Arkansas Regional Haze SIP for Domtar does not 
satisfy the requirement to provide for periodic testing of stationary 
sources and to use enforceable test methods for each emission limit 
specified in the plan, and should therefore be disapproved. For 
example, the SIP lacks specificity regarding test methods in permit 
conditions 38 and 40. Permit condition 38 refers to 40 CFR part 60, 
without identifying the specific rule provisions that apply. Similarly, 
permit condition 40 fails to identify the specific AP-42 emission 
factor.
    Response: We disagree with the commenter that the SIP lacks 
specificity regarding test methods in permit conditions 38 and 40 for 
the boilers. The commenter states that permit condition 38 refers to 40 
CFR part 60 regarding utilizing CEMS without identifying the specific 
rule provisions that apply. In permit condition 38, the State provided 
that ``the permittee shall demonstrate compliance with the 30-boiler 
operating

[[Page 15118]]

day rolling average SO2 and NOX limits utilizing 
a continuous emissions monitor (CEMS) subject to 40 CFR part 60.'' 
Permit condition 38 identifies the source category type as being a 
boiler and the pollutants to be monitored by CEMS as SO2 and 
NOX. It is clear from the pollutant, fuel type, and the 
nature of the emission unit which of the tests would apply under 40 CFR 
60 for demonstrating compliance. That is sufficient information to 
locate the performance specifications and quality assurance procedures 
for Power Boiler No. 2 to determine how to utilize CEMS to determine 
compliance with the SO2 and NOX limits of the 
Arkansas Regional Haze Phase III SIP revision. The State is being all-
inclusive when referring to Part 60 to include all of the general 
provisions in Subpart A related to CEMS, such as 40 CFR 60.8 for 
performance tests, 40 CFR 60.13 pertaining to monitoring requirements, 
and Appendix B to Part 60, which includes performance specifications 
for CEMS. In addition, these permit conditions also implement APCEC 
Rule 19.703--Continuous Emission Monitoring,\78\ which is already part 
of the approved SIP, and applies to this source.\79\ Specific condition 
54 of the permit provides additional information regarding CEMS 
requirements for Power Boiler No 2. Specifically, it says, ``The 
permittee shall install, calibrate, maintain and operate continuous 
emissions monitoring systems for measuring SO2 emissions, 
NOX emissions, and either oxygen or carbon dioxide. The CEMS 
shall have readouts which demonstrate compliance with any of the 
applicable limits for the pollutant in question. The permittee shall 
comply with the DEQ CEMS conditions found in Appendix B. [Reg. 19.703, 
40 CFR 52, Subpart E, and Ark. Code Ann. Sec.  8-4-203 as referenced by 
Ark. Code Ann. Sec. Sec.  8-4-304 and 8-4-311].'' Appendix B sections 
II through IV of the permit lay out specific guidelines for CEMS 
operating conditions.
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    \78\ Under APCEC Rule 19.703--Continuous Emission Monitoring, 
any stationary source subject to this regulation shall, as required 
by federal law and upon request of the Department: (A) Install, 
calibrate, operate, and maintain equipment to continuously monitor 
or determine federally regulated air pollutant emissions in 
accordance with applicable performance specifications in 40 CFR part 
60 Appendix B as of the effective date of the federal final rule 
published by EPA in the Federal Register on February 27, 2014 (79 FR 
11271), and quality assurance procedures in 40 CFR part 60 Appendix 
F as of the effective date of the federal final rule published by 
EPA in the Federal Register on February 27, 2014 (79 FR 11274), and 
other methods and conditions that the Department, with the 
concurrence of the EPA, shall prescribe. Any source listed in a 
category in 40 CFR part 51 Appendix P as of the effective date of 
the federal final rule published by EPA in the Federal Register on 
November 7, 1986 (51 FR 40675), or in 40 CFR part 60 as of August 
30, 1992, shall adhere to all continuous emissions monitoring or 
alternative continuous emission monitoring requirements stated 
therein, if applicable. (B) Report the data collected by the 
monitoring equipment to the Department at such intervals and on such 
forms as the Department shall prescribe, in accordance with 40 CFR 
part 51, Appendix P, Section 4.0 (Minimum Data Requirements) as of 
the effective date of the federal final rule published by EPA in the 
Federal Register on November 7, 1986 (51 FR 40675), and any other 
applicable reporting requirements promulgated by the EPA.
    \79\ See 52.170(c) (table) for EPA-approved regulations in the 
Arkansas SIP.
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    The commenter also states that permit condition 40 fails to 
identify the specific AP-42 emission factors. Condition 40 refers to 
``the applicable natural gas AP-42 emission factors'' and provides an 
appropriate description because the applicable emission factors are 
based on the nature of the emissions unit, fuel, and pollutants in 
question. As explained in the proposed approval,\80\ 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 shall be used to demonstrate 
compliance with the BART emission limits.\81\ Therefore, the boiler 
will operate under CEMs, and these AP-42 emissions factors would only 
be used for estimation of emissions if Power Boiler No. 2 burns natural 
gas. We note, just as we did in the FIP, for which these provisions are 
replacing,82 83 that burning only natural gas would very 
likely be sufficient in itself to demonstrate that the boiler is 
complying with the SO2 emission limit. SO2 
emissions from combustion of natural gas are inherently very low and 
are virtually eliminated during the combustion process. Any 
SO2 emissions will be in trace amounts well below the BART 
alternative emission limit so there should be no concern that the 
alternative limit for SO2 will be met. NOX and 
PM10 emissions are also expected to be lower than the BART 
alternative emission limit for natural gas combustion.84 85 
Using the most conservative NOX, SO2, and 
PM10 AP-42 factors (highest factor) for boiler combustion 
indicates that the BART alternative emission limits will be met even 
when firing natural gas at full capacity. Based on this information, 
any ambiguity in the use of AP-42 factors for compliance using only 
natural gas is not of concern because of the characteristically lower 
emissions during natural gas combustion. When natural gas is used, the 
limits in the BART alternative demonstration will be met. DEQ has the 
State authority to enforce these emission factors to document 
compliance and EPA will have federal authority once this approval takes 
effect.
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    \80\ See 85 FR 14847, 14862.
    \81\ See AP 42, Fifth Edition Compilation of Air Pollutant 
Emissions Factors, Volume 1: Stationary Point and Area Sources, 
section 1.4, Tables 1.4-1 and 2 pertaining to natural gas 
combustion.
    \82\ See 40 CFR 52.173(c)(8)(iv) and (v). However, the FIP 
regulations required burning only pipeline quality natural gas, and 
no such requirement to burn only pipeline quality natural gas can be 
located in the permit or the SIP for this unit. Nonetheless, there 
is no indication (nor has the commenter supplied any such 
information) that burning other types of natural gas would result in 
SO2 emissions that would even approach the BART 
alternative emission limit.
    \83\ Table 1.4-2 from Fifth Edition Compilation of Air Pollutant 
Emissions Factors, Volume 1: Stationary Point and Area Sources, 
section 1.4 indicates that the AP-42 factor contemplates varying 
amounts of sulfur and the potential need to adjust the emission 
factor. The AP-42 factor for sulfur from natural gas (0.6 lb/10\6\ 
scf) is based on 100% conversion of fuel sulfur to SO2. 
It assumes a sulfur content for natural gas of 2,000 grains/10\6\ 
scf. The SO2 emission factor in this table can be 
converted to other natural gas sulfur contents by multiplying the 
SO2 emission factor by the ratio of the site-specific 
sulfur content (grains/10\6\ scf) to 2,000 grains/10\6\ scf. To 
convert the emission factors in the AP-42 tables on a volume basis 
(lb/10\6\ scf) to an energy basis (lb/MMBtu) divide by a heating 
value of 1,020 MMBtu/10\6\ scf. Then, multiply the result by the 
heat input capacity of the boiler (MMBtu/hr) to get a mass flow rate 
(lb/hr). Accordingly, an AP factor of 0.6 lb SO2/MMscf 
multiplied by Power Boiler No. 2 maximum heat input of 820 MMBtu/hr 
would result in 0.5 lb/hr SO2, showing that the sulfur 
emissions would be very low and almost negligible. It is also more 
conservative than the FIP (``pipeline quality natural gas'' would 
result in 1.2 lb/hr SO2 assuming pipeline natural gas 
contains 0.5 grains or less of total sulfur per 100 standard cubic 
feet). These results are well below the BART alternative limit for 
SO2 of 435 lb/hr.
    \84\ From Table 1.4-1 of Fifth Edition Compilation of Air 
Pollutant Emissions Factors, Volume 1: Stationary Point and Area 
Sources, section 1.4 we can also appropriately select the most 
conservative NOX emission factor based on the design heat 
input capacity for Power Boiler No. 2 of 820 MMBtu/hr. From this, we 
can choose emission factors from the combustor type. The applicable 
AP-42 emission factor (280 lb NOX/MMscf) is consistent 
with what was used in the FIP for a large wall-fired boiler > 100 
MMBtu/hr. This is the highest emission factor in the table for 
NOX and results in 225 lb/hr NOX (985 tpy 
NOX) which can be calculated from the heat input capacity 
of the boiler (820 MMBtu/hr) similarly as explained in previous 
footnote. The result is less than both the FIP NOX limit 
of 345 lb/hr (1,511 tpy) and the BART alternative NOX 
rate of 293 lb/hr (1,283 tpy).
    \85\ From Table 1.4-2 of Fifth Edition Compilation of Air 
Pollutant Emissions Factors, Volume 1: Stationary Point and Area 
Sources, section 1.4 an AP factor of 7.6 lb PM10/MMscf 
represents total PM and equates to 6.1 lb/hr PM applying a heat 
input capacity of 820 MMBtu/hr. This is less than the BART 
alternative rate of 81.6 lb/hr PM.
---------------------------------------------------------------------------

    The State made clear in its SIP submittal that the BART alternative 
SIP requirements for this source would be implemented in conjunction 
with preexisting SIP requirements for monitoring, reporting, and

[[Page 15119]]

recordkeeping, thus ensuring that the emissions limitations applicable 
to this source under the BART alternative are practically enforceable. 
See Aug. 2019 SIP Submittal at 2. These provisions of Arkansas's air 
regulations have been approved by EPA into Arkansas' federally 
enforceable SIP.\86\ In particular, APCEC Rule 19 Chapter 7--Sampling, 
Monitoring and Reporting Requirements, sets forth the powers of DEQ in 
requiring sampling, monitoring, and reporting requirements at 
stationary sources. Specifically, any stationary source is subject to 
air emission sampling (APCEC Rule 19.702); \87\ continuous emission 
monitoring (APCEC Rule 19.703); recordkeeping and reporting 
requirements (APCEC Rule 19.705); \88\ and Public Availability of 
Emissions Data (APCEC Rule 19.706).\89\ All of these requirements will 
become federally enforceable against Domtar with EPA's final approval 
of this SIP submittal. For these reasons, conditions 38 and 40 contain 
sufficient specificity regarding testing for compliance for Power 
Boiler No. 2.
---------------------------------------------------------------------------

    \86\ See 40 CFR 52.170(c) (table) for EPA-approved regulations 
in the Arkansas SIP.
    \87\ Under APCEC Rule 19.702--Air Emissions Sampling, any 
stationary source subject to this regulation shall be subject to the 
following requirements: (A) Sampling Ports To provide any sampling 
ports, at the request of the Department, required for federally 
regulated air pollutant emissions sampling, including safe and easy 
access to such ports. (B) Sampling To conduct federally regulated 
air pollutant emissions sampling, at the request of the Department, 
to determine the rate, opacity, composition, and/or contaminant 
concentration of the emissions. All compliance testing shall be done 
at the expense of the permittee by an independent firm, unless 
otherwise approved by the Department. Sampling shall not be required 
for those pollutants with continuous emissions monitors. (C) 
Averaging Times All compliance testing averaging times shall be 
consistent with the averaging times of the applicable federally 
regulated air pollutant emissions limitations stated in the 
applicable permit, which in no case shall be greater than the 
minimum averaging times of the applicable NAAQS. (D) Process Rates 
Unless otherwise approved by the Department, all federally regulated 
air pollutant emissions sampling shall be performed with the 
equipment being tested operating at least at ninety percent of its 
permitted capacity. Emissions results shall be extrapolated to 
correlate with 100 percent of permitted capacity to determine 
compliance.
    \88\ Under APCEC Rule 19.705--Record Keeping and Reporting 
Requirements, any stationary source subject to this regulation 
shall, upon request by the Department: (A) Maintain records on the 
nature and amounts of federally regulated air pollutants emitted to 
the air by the equipment in question. All records, including 
compliance status reports and excess emissions measurements shall be 
retained for at least five (5) years, and shall be made available to 
any agent of the Department or EPA during regular business hours. 
(B) Supply the following information, correlated in units of the 
applicable emissions limitations, to the Department: (1) General 
process information related to the emissions of federally regulated 
air pollutants into the air. (2) Emissions data obtained through 
sampling or continuous emissions monitoring. (C) Information and 
data shall be submitted to the Department by a responsible official 
on such forms and at such time intervals as prescribed by applicable 
federal regulations or the Department. Reporting periods shall be a 
twelve-month period. (D) Each emission inventory is to be 
accompanied by a certifying statement, signed by the owner(s) or 
operator(s) and attesting that the information contained in the 
inventory is true and accurate to the best knowledge of the 
certifying official. The certification shall include the full name, 
title, signature, date of signature, and telephone number of the 
certifying official.
    \89\ Emissions data obtained by the Department shall be 
correlated in units of applicable emissions limitations and be made 
available to the public at the Department's central offices during 
normal business hours.
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    Comment B.3: The provisions for recordkeeping are inadequate for 
permit conditions 36 and 43. In addition to failing to require that 
``owners and operators'' are subject to these provisions, these 
provisions fail to specify necessary specifics to determine compliance. 
For example, these provisions lack requirements that records shall be 
maintained for CEMS data; quality assurance and quality control 
activities for emissions measuring systems; major maintenance 
activities conducted on emission units, control equipment, and CEMS; 
and any other records required by the underlying requirements.
    Response: We disagree with the commenter's assertion that the 
provisions for recordkeeping are inadequate for conditions 36 and 43. 
The commenter cites CAA section 110(a)(2)(F), 40 CFR 51 Subpart K,\90\ 
and the BART guidelines \91\ in identifying the applicable 
recordkeeping and reporting requirements.\92\ However, these 
requirements do not mandate the level of specificity the commenter 
would like to see regarding recordkeeping, and the commenter cites no 
authority for the notion that that level of specificity is required. 
Nor did the commenter cite any examples from other BART alternative 
actions that would demonstrate that the level of specificity of the 
recordkeeping requirements here is inconsistent with what has been 
approved in other SIPs. Commenter's suggestions do not reflect how the 
regulations are worded regarding recordkeeping and reporting, 
therefore, we conclude that the commenter has failed to establish how 
the recordkeeping and reporting requirements in 40 CFR 51 Subpart K, 
and the BART guidelines are not met by conditions 36 and 43.\93\ Permit 
conditions 36 and 43 clearly require maintaining ``all records'' 
necessary to determine compliance ``for at least 5 years.'' This is 
sufficient under the regional haze regulations. Further, such broad 
terms encompass many if not all of the specific enumerated types of 
records the commenter claims should be retained. The recordkeeping 
provisions in conditions 36 and 43 are, therefore, not lacking and are 
sufficient enough on their own merit to meet 40 CFR 51 Subpart K and 
the BART-alternative requirements of subpart P. As mentioned in the 
previous response, Appendix B sections II through IV of the permit lay 
out specific guidelines for CEMS operating conditions. These CEMS 
conditions are reflected in and administered by the State under APCEC 
Rule 19.703--Continuous Emission Monitoring. The State applies APCEC 
Rule 19.705 \94\--Record Keeping and Reporting Requirements to air 
pollution sources subject to the regulation.\95\ The State made clear 
in its August 2019 SIP Submittal, at page 2, that these provisions 
apply to the Domtar Ashdown Mill for purposes of implementing the BART 
alternative emission limitations at Power Boilers No. 1 and No. 2. 
These requirements will become federally enforceable

[[Page 15120]]

against Domtar with final approval of this SIP submittal.
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    \90\ 40 CFR 51.210-214.
    \91\ Guidelines for BART Determinations Under the Regional Haze 
Rule, Appendix Y.
    \92\ See Laumann Legal comments on behalf of the National Parks 
Conservation Association, the Sierra Club, and Earthjustice (pages 
11-13).
    \93\ We note that section 110(a)(2)(F) of the statute only 
establishes such requirements ``as may be prescribed by the 
Administrator.'' Therefore, the language of 110(a)(2)(F) does not 
apply directly to our evaluation of a SIP revision. Rather, the 
specific monitoring, reporting, and recordkeeping requirements that 
apply to our evaluation of the SIP revision are those that have been 
``prescribed,'' i.e., promulgated, in the governing regulations at 
subparts K and P of Part 51.
    \94\ Under APCEC Rule 19.705--Record Keeping and Reporting 
Requirements, the State, ``maintains records on the nature and 
amounts of federally regulated air pollutants emitted to the air by 
the equipment in question. All records, including compliance status 
reports and excess emissions measurements shall be retained for at 
least five years, and shall be made available to any agent of the 
Department or EPA during regular business hours. Stationary sources 
are subject to supply the following information, correlated in units 
of the applicable emissions limitations, to the DEQ: (1) General 
process information related to the emissions of federally regulated 
air pollutants into the air. (2) Emissions data obtained through 
sampling or continuous emissions monitoring. Information and data 
shall be submitted to the Department by a responsible official on 
such forms and at such time intervals as prescribed by applicable 
federal regulations or the Department. Reporting periods shall be a 
twelve-month period. Each emission inventory is to be accompanied by 
a certifying statement, signed by the owner(s) or operator(s) and 
attesting that the information contained in the inventory is true 
and accurate to the best knowledge of the certifying official. The 
certification shall include the full name, title, signature, date of 
signature, and telephone number of the certifying official.''
    \95\ See 52.170(c) (table) for EPA-approved regulations in the 
Arkansas SIP.
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    The commenter lastly mentioned that these conditions fail to 
require that ``owners and operators'' are subject to the provisions in 
them. We address this in response to comment B.5 in section III.B of 
this final action. As mentioned in that response, we recognize Domtar 
as both the permittee and the owner subject to the permit conditions. 
Further, because the permit conditions are being incorporated into the 
state's SIP, they are state- and federally-enforceable on any owner or 
operator of this facility regardless of any changes that may occur in 
ownership of the facility or in the permit itself. Therefore, Domtar 
and any future owner or operator is subject to the provisions being 
approved in this action, including conditions 36 and 43, and DEQ will 
continue to enforce these measures with EPA oversight.
    Comment B.4: EPA's proposal suggests there are reporting 
requirements for Power Boiler No. 1 in conditions 33 to 36 and in 
conditions 38 to 43 for Power Boiler No. 2 but these provisions do not 
contain requirements for reporting. The SIP lacks any requirements for 
reporting and EPA must disapprove the SIP.
    Response: The commenter asserts that conditions 33 to 36 for Power 
Boiler No. 1 and conditions 38 to 43 for Power Boiler No. 2 fail to 
contain reporting requirements as EPA suggests. However, permit 
conditions 36 and 43 state that all records ``shall be made available 
to any agent of DEQ or EPA upon request.'' Accordingly, the records 
will be provided upon request by DEQ or EPA. This is sufficient to 
satisfy periodic reporting of records in 40 CFR 51.211. The general 
BART alternative implementation requirements of 51.308(e)(2)(iii), 
which do not include a requirement of reporting on any specific time 
period, are also met. The commenter also suggests that the State is 
required to provide periodic reporting requirements as stated in 42 
U.S.C. 7410(a)(2)(F)(ii) and the BART guidelines. However, section 
110(a)(2)(F) requires EPA to ``prescribe'' its requirements, and thus 
this provision is implemented through the applicable regulations. The 
BART guidelines call for adequate reporting and recordkeeping so that 
air quality agency personnel can determine the compliance status of the 
source. Permit conditions 36 and 43 clearly require maintaining ``all 
records'' necessary to determine compliance ``for at least 5 years'' 
and permit conditions 36 and 43 state that all records ``shall be made 
available to any agent of DEQ or EPA upon request'' so determination of 
compliance can be made.
    Further, other SIP-approved provisions of Arkansas' regulations 
also apply, ensuring the reporting obligations of 51.211 and the BART-
alternative implementation measures of 51.308(e)(2)(iii) are satisfied. 
The commenter mentions that the SIP lacks any requirements for 
reporting, but that is not the case. APCEC Rule 19 Chapter 7--Sampling, 
Monitoring and Reporting Requirements, sets forth the powers of DEQ in 
requiring sampling, monitoring, and reporting requirements at 
stationary sources.\96\ As mentioned previously, the State made clear 
in its SIP submittal that the BART alternative SIP requirements for 
this source would be implemented in conjunction with preexisting SIP 
requirements for sampling, monitoring, and reporting requirements under 
APCEC Rule 19 Chapter 7, thus ensuring that the emissions limitations 
applicable to this source under the BART alternative are practically 
enforceable.\97\ Per APCEC Rule 19.705(C), Domtar must submit annual 
reports demonstrating compliance with applicable emission limitations. 
In addition, they must keep all records demonstrating compliance for at 
least five years (APCEC Rule 19.705(A)). Inspectors audit these records 
during site inspections. Therefore, Domtar does have a pre-existing 
annual reporting requirement, and, with the approval of the BART-
alternative emission limits into the State's regional haze SIP, their 
compliance with these emission limits will also be a part of that 
annual report going forward. For these reasons, the SIP is not lacking 
reporting requirements, including any periodic reporting requirement as 
required under part 51, subpart K.
---------------------------------------------------------------------------

    \96\ See 52.170(c) (table) for EPA-approved regulations in the 
Arkansas SIP.
    \97\ See Aug. 2019 SIP Submittal at 2.
---------------------------------------------------------------------------

    It is also worth noting that as a source subject to Title V 
requirements, it is subject to annual deviation reports under APCEC 
Rule 26.703(E)(3)(c). In addition, as a major source it is required to 
provide an annual emissions inventory. EPA finds that the reporting 
requirements applicable to Domtar under this SIP submittal are 
sufficient to meet the requirements of the BART alternative regulations 
and subpart K.
    Comment B.5: The SIP fails to require that the source surveillance 
provisions apply to owners and operators. The source surveillance 
provisions must apply to owners and operators of the source instead of 
the Title V permittee in permit condition 32. This provision does not 
meet the requirements of subpart K. If the Title V permit were to 
expire, there would be no permittee to hold accountable. EPA must 
therefore disapprove this provision of the SIP because it fails to 
identify the appropriate liable entity. Similarly, permit condition 33 
fails to specify the entity responsible for making the demonstration, 
and therefore, EPA must also disapprove this provision.
    Response: The commenter stated that the SIP fails to require that 
the source surveillance provisions apply to owners and operators. EPA 
disagrees with this comment because the terms of the permit are 
incorporated into the SIP and are therefore applicable to both the 
permittee and any other owner or operator of this facility. Currently, 
those entities are one and the same: Domtar. Because conditions 32 and 
33 in the permit both say ``permittee'' instead of ``owner and 
operator,'' the commenter asserts that nobody will be subject to the 
provisions in these conditions if the Title V permit were to expire. 
This is incorrect, and nothing in the State's SIP submittal or any 
other information before the EPA suggests that this is how these terms 
are to be interpreted. The terms ``permittee'' and ``owner'' are both 
used in the permit. Domtar is recognized as both the owner of the 
Ashdown mill who operates the boilers and the permittee of the Title V 
permit containing the revised conditions implementing the BART 
alternative. ``The BART Alternative specific conditions'' portion of 
the plantwide conditions section of the permit clarifies that the 
permittee is the one who is subject to these conditions.
    In addition, these requirements would not cease to apply if Domtar 
were for any reason to cease to be the permittee. Although 
``permittee'' is being used in the wording of the permit conditions, 
these conditions are being approved into the State's SIP and are state- 
and federally-enforceable by virtue of being in the SIP. As the State's 
SIP submittal explains,\98\ ``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

[[Page 15121]]

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'' (emphasis added). Because of this, should the Title V 
permit expire, be modified, or transferred, any person who owns or 
operates this facility, including the current permittee, will still be 
subject to these conditions as a result of their being incorporated 
into the federally enforceable SIP. We note in addition that permits 
are transferable due to changes in ownership of a source, given proper 
notification to the director including required disclosures.\99\ In 
terms of expiration, the Arkansas program is based on a one permit 
system meaning that a source contains a single document that contains 
both the Title I New Source Review (NSR) and Title V permit conditions/
requirements. The conditions of the NSR permit do not ever expire. 
Title V permits do have a permit expiration date, but the expiration of 
the Title V permit does not impact the ``status'' of NSR permit 
requirements.\100\ These requirements live on unless modified/removed 
via an NSR permit action. Because NSR permit changes are automatically 
updated in the Title V permit there isn't any impact on operational 
status if the NSR permit was modified.
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    \98\ See DEQ Air permit #0287-AOP-R22 (page 203), the ``Regional 
Haze Program (BART Alternative) Specific Conditions'' portion of the 
Plantwide Conditions section of the permit, Section VI, Plantwide 
Conditions #32 to #43.
    \99\ See the criteria for change of ownership addressed in APCEC 
Reg.19.407(B).
    \100\ To avoid expiration, sources apply for a renewal of the 
Title V permit at least six months prior to expiration in order to 
operate under a permit shield (in cases where a renewed permit is 
not issued prior to expiration). If a case exists where a source 
does not meet this six-month timeline, the Title V permit would 
expire according to the expiration date and the source could no 
longer operate.
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    Therefore, the provisions in conditions 32 and 33 and in other 
provisions addressing ownership will continue to be enforceable 
requirements, regardless of who owns or operates this facility, and DEQ 
and EPA will continue to be able to enforce these measures. We, 
therefore, disagree that these conditions need to place requirements on 
the ``owners and operators'' rather than the ``permittee'' to be 
permanently enforceable.
    Comment B.6: The SIP lacks enforceable provisions regarding 
permanent retirement. The SIP provides an option for permanent 
retirement of Power Boiler No. 1, but permit condition 34 lacks 
enforceable language. This permit condition and EPA's proposal lack the 
details necessary for enforcement. For example, it fails to explain 
what a ``disconnection notice'' is and what information is contained in 
the notice. Therefore, the public is unable to assess whether a 
``disconnection notice'' is a permanent action that satisfies the BART 
requirements. EPA is prohibited from approving this additional BART 
alternative since the condition contains vague and unenforceable 
language.
    Response: We disagree with the commenter that the SIP lacks 
enforceable provisions in condition 34 regarding permanent retirement. 
The term ``disconnection notice'' is self-defining in that it simply 
describes DEQ receiving communication in the form of a notice after 
Power Boiler No. 1 has already been taken out of service and is 
permanently retired. ``Permanently retired'' self-evidently means that 
once the power boiler is taken out of service it will never operate 
again. Indeed, this has already occurred. As indicated in a November 
18, 2020, letter \101\ to DEQ from Domtar, the No. 1 Power Boiler was 
placed in standby mode and stopped operating in April 2016. That letter 
also documented that the unit was disconnected and permanently retired 
on August 6, 2018, with the removal of a section of boiler feedwater 
piping that prevents the boiler from producing steam. In addition, 
finalization of the permit amendment 0287-AOP-R23 removed authority for 
Domtar to operate No. 1 Power Boiler. As stated in an April 15, 2020, 
permit revision,\102\ ``By request of the facility, this source has 
been retired and removed from the permit as a source in permit revision 
#23. The specific conditions have been marked, by request of the 
facility, as reserved in order to not change the numbering of the 
subsequent conditions. SN-03 is subject to the Regional Haze Program, 
specifically the BART Alternative. These conditions can be found 
starting with Plantwide Condition 32.'' Because Domtar has requested 
that Power Boiler No. 1 be retired and removed as a source from the 
permit, the source specific permit provisions have been removed from 
the permit for Power Boiler No. 1 and they are not authorized to 
operate the unit. Power Boiler No. 1 is in compliance with the BART 
alternative limits by virtue of being permanently retired and therefore 
not emitting any of the relevant visibility pollutants. The numerical 
emission limits will apply, even though the unit has been taken out of 
service. DEQ has State authority established in its SIP, including 
APCEC Rule Chapter 7, for any other reporting requirements including 
documenting source retirement of this unit.\103\ For this reason, this 
condition does not lack enforceable provisions for retirement.
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    \101\ See November 18, 2020 Disconnection Notice from Domtar for 
Power Boiler No. 1 (SN-03) in the docket of this action.
    \102\ See DEQ Air Permit No. 0287-AOP-R23 included in the docket 
of this action.
    \103\ See 52.170(c) (table) for EPA-approved regulations in the 
Arkansas SIP.
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    Comment B.7: The SIP neither specifies a compliance date nor 
requires compliance at all times. BART must reflect the best system of 
continuous emission reduction and the BART limits must apply at all 
times. EPA must clarify that the permit conditions proposed for 
approval in the SIP apply at all times. Furthermore, permit conditions 
38 and 41 cross reference test methods found in other regulations that 
are inconsistent with the BART requirements since they do not require 
compliance at all times and exempt emissions during certain activities. 
These regulations and associated test methods are inconsistent with 
BART in that they do not require compliance at all times and exempt 
emissions during certain activities.
    Response: We disagree with the commenter that the permit conditions 
do not apply at all times. There is no language in the proposed limits 
to suggest that they do not apply at all times. Conditions 32 and 37, 
which describe the emission rates for the power boilers, both say, 
``The permittee shall not exceed the emission rates set forth in the 
following table. The limits are based on a 30-day boiler operating day 
rolling average. 30 boiler operating day rolling average is defined as 
the arithmetic average of 30 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. 
[Reg.19.304, 40 CFR 51.308(e)(2), and 40 CFR 52.173].'' The language 
for permit conditions 38 and 41 describes ongoing compliance action 
into the future and does not indicate that the emission limits would 
cease or not apply continuously. Therefore, the BART alternative limits 
that we proposed to approve do indeed apply at all times.
    The commenter argues that certain permit conditions cross-reference 
test methods in other regulations (i.e., the NESHAP, MACT and NSPS), 
which they allege are inconsistent with BART requirements since they do 
not require compliance at all times and exempt emissions during certain 
activities. The

[[Page 15122]]

commenter specifically identifies this flaw in condition 38 pertaining 
to 40 CFR 60 and condition 41 pertaining to 40 CFR 63 subpart DDDDD. 
Programs like the NESHAP, MACT, and NSPS have different requirements, 
such as performance testing that is carried out over certain time 
frames that demonstrates compliance for particular pollutants. While 
those types of emission tests may have been designed to serve a 
different regulatory purpose, they are not in conflict with the BART 
requirements; nor do they override the BART alternative emission limits 
express set forth in the permit. There is no legal or regulatory 
barrier to incorporating performance testing requirements found in 
other regulatory programs as a means of implementing and ensuring 
compliance with a BART alternative. The commenter fails to demonstrate 
with reasonable specificity how the use of testing requirements that 
are intended to meet other criteria are in conflict or fail to meet the 
BART alternative requirements.
    Further, the State made clear which test methods from those 
regulations are required for demonstrating compliance with these 
conditions. With respect to condition 38's reference to 40 CFR 60, the 
requirement to use CEMS to demonstrate compliance for SO2 
and NOX is clear, unambiguous, and continuous. The State is 
being all-inclusive when referring to Part 60 to include all of the 
general provisions in Subpart A related to CEMS such as 40 CFR 60.8 for 
performance tests, 40 CFR 60.13 pertaining to monitoring requirements, 
and Appendix B to Part 60 that includes performance specifications. In 
addition, these permit conditions also implement APCEC Rule 19.703--
Continuous Emission Monitoring, which is already part of the approved 
SIP, and applies to this source. Appendix B sections II through IV of 
the permit lay out specific guidelines for CEMS operating conditions. 
With respect to condition 41's reference to 40 CFR 63 subpart DDDDD, 
condition 41 clearly explains that the applicable PM10 
compliance demonstration requirements from 40 CFR part 63 subpart DDDDD 
shall be utilized. These requirements, which are at 40 CFR 63.7505-
63.7541, do not cease and are ongoing. In response to comment B.8 in 
section III of this final action, we address the alternative option 
provided in the permit for monitoring emissions from Power Boiler #2 
when that unit is combusting natural gas. Either method, however, 
provides for demonstration of continuous compliance with the BART 
alternative emission limits for PM10. For these reasons, the 
test methods in conditions 38 and 41 are sufficient to provide 
continuous compliance and are not in conflict with the BART 
requirements.
    The commenter particularly notes that because the permit conditions 
do not reference specific sections in these regulations, it is unclear 
whether the startup, shutdown, and malfunction emissions are included 
or exempt from monitoring. The commenter does not establish with 
reasonable specificity which of the performance testing or monitoring 
requirements from part 60 or part 63 would be affected here by 
provisions in those parts relating to ``startup, shutdown, and 
malfunction.'' Also, Table 10 to subpart DDDDD of Part 63 shows that 
SSM plan requirements and actions taken to minimize emissions during 
startup, shutdown, or malfunction are not required for subpart DDDDD.
    The commenter lastly mentions that the State's SIP fails to include 
the schedule and timetable for compliance. We address comments 
regarding the schedule and timetable for compliance in response to 
comment C.1 in section III.C of this final action. These new BART 
alternative limits became enforceable by the State immediately upon 
issuance of a minor modification letter sent by the State to Domtar on 
February 28, 2019. The two Domtar power boilers have already been 
operating at emission levels below the proposed BART alternative 
emission limits since December 2016, three years before the limits 
became enforceable, continuing to do so through February 2019 and up to 
the present. The BART alternative limits and all associated permit 
conditions will become federally enforceable upon the effective date of 
this final action approving the SIP.
    Comment B.8: The PM10 test method for Power Boiler No. 2 
permit is inappropriately conditioned on applicability under another 
regulation. The BART emission limits must have test methods that apply 
at all times. Permit condition 41 lacks enforceability in this regard. 
This permit condition is conditioned on when a National Emission 
Standards for Hazardous Air Pollutants (NESHAP) rule applies to this 
boiler. In other words, ``while'' the boiler ``is subject to'' the 
NESHAP, the requirements of the NESHAP rule are used to demonstrate 
compliance. In the event this boiler is no longer subject to the 
NESHAP, there would no longer be compliance demonstration requirements 
for the BART emission limits. This provision lacks specificity 
regarding the specific test methods in 40 CFR part 63 subpart DDDDD 
that apply and fails to identify what entity is required to meet these 
requirements.
    Response: We disagree with the commenter that the PM10 
test method for Power Boiler No. 2 permit is inappropriately 
conditioned on applicability under another regulation. The commenter 
suggests that the word ``while'' in condition 41 is being used to allow 
avoidance of the BART alternative emission limit for PM10. 
As we explained in our proposed action,\104\ ``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.'' \105\ Therefore, ``while'' is used to draw a 
contrasting relationship between MACT, subpart DDDDD, and switching to 
natural gas combustion. If Power Boiler No. 2 switches to natural gas, 
fuel usage records will then apply for compliance demonstration. If the 
boiler does not burn natural gas only, then Power Boiler No. 2 is 
subject to 40 CFR 63 subpart DDDDD as an ongoing requirement for 
PM10, and that requirement would not cease at any time.
---------------------------------------------------------------------------

    \104\ See 85 FR 14847, 14862.
    \105\ See AP 42, Fifth Edition Compilation of Air Pollutant 
Emissions Factors, Volume 1: Stationary Point and Area Sources, 
section 1.4, Tables 1.4-1 and 2 pertaining to natural gas 
combustion.
---------------------------------------------------------------------------

    The commenter also claims that permit condition 41 fails to 
identify which specific test methods found in 40 CFR 63 subpart DDDDD 
would apply. We disagree with this statement. Although the revised 
permit condition 41 does not spell out specific test methods, that does 
not mean it is not clear which test methods apply. In regard to 40 CFR 
63 DDDDD, boiler MACT test methods are quite detailed and specific and 
are based on the source-specific unit type and pollutant emissions to 
be tested. It is clear from the pollutant, fuel type, and the nature of 
the emission unit here which of the tests would apply under DDDDD. 
Therefore, there is sufficient information to determine compliance. 
Table 10 to subpart DDDDD of Part 63 shows the applicable general 
provisions and includes performance testing requirements in 40 CFR 
63.7.

[[Page 15123]]

Continuous compliance is demonstrated for PM10 under MACT, 
subpart DDDDD by maintaining the appropriate operating limit, depending 
on the control technology used (see Table 4 of subpart DDDDD). In this 
case, Power Boiler No. 2 uses venturi scrubbers so a site-specific 
minimum scrubber pressure drop and minimum flow rate operating limit 
according to 40 CFR 63.7530 would be used as the operating parameters. 
If no control device is used to demonstrate compliance with the 
PM10 limit, the facility must monitor operating load (see 
item 8 of Table 4 and item 10 of Table 8) based on the operating limit 
set during the most recent PM10 performance test (item 8 of 
Table 4 of subpart DDDDD), or by maintaining fuel records (40 CFR 
63.7555(d)(1)) which is what will occur if Power Boiler No. 2 burns 
natural gas, as previously stated. Using the most conservative 
PM10 AP-42 factor (highest factor) for boiler combustion 
indicates that the BART alternative emission limits will be met even 
when firing natural gas at full capacity.
    Finally, the commenter mentions that this provision fails to 
identify what entity is required to meet these requirements (i.e., the 
owner or operator). The has been addressed previously in our response 
to comment B.5.
    Comment B.9: The permit conditions appear to preclude the use of 
any credible evidence. EPA's proposal fails to explain whether the test 
procedures in the permit conditions are the ``only'' evidence that may 
be used to demonstrate compliance. EPA must disapprove the State's SIP 
submittal if approving these permit conditions were to preclude the use 
of any credible evidence.
    Response: We disagree with the commenter that the permit conditions 
in any way preclude or appear to preclude the use of any credible 
evidence. The commenter does not identify anything in the permit or the 
Arkansas SIP that would preclude the use of other credible evidence. 
Both the SIP and the permit make clear that credible evidence can be 
used to determine compliance.
    First, the SIP includes APCEC Regulation 19.701--Purpose, which 
states, ``The purpose of this chapter is to generally define the powers 
of the Department in requiring sampling, monitoring, and reporting 
requirements at stationary sources. The Department shall enforce all 
properly incorporated and delegated federal testing requirements at a 
minimum. Any credible evidence based on sampling, monitoring, and 
reporting may be used to determine violations of applicable emission 
limitations'' Similarly, general provision #27 of the Domtar permit 
provides that, ``Any credible evidence based on sampling, monitoring, 
and reporting may be used to determine violations of applicable 
emission limitations. [Reg.18.1001, Reg.19.701, Ark. Code Ann. Sec.  8-
4-203 as referenced by Ark. Code Ann. Sec. Sec.  8-4-304 and 8-4-311, 
and 40 CFR 52 Subpart E]'' Lastly, the Credible Evidence Revisions rule 
revised 40 CFR parts 51, 52, 60, and 61 to permit the use of any 
credible evidence (i.e., both reference test data and comparable non-
reference test data) to prove or disprove CAA violations in enforcement 
actions. In this regard, the preamble to the rule states: ``These 
revisions make clear that enforcement authorities can prosecute actions 
based exclusively on any credible evidence, without the need to rely on 
any data from a particular reference test.'' \106\ Therefore, although 
the permit does not specifically identify all types of evidence that 
may be used to determine compliance or non-compliance, neither the 
permit conditions nor the SIP preclude the use of any credible 
evidence. Furthermore, any attempt to specifically enumerate the types 
of evidence that may be used to determine compliance would undermine 
the purpose of the Credible Evidence Revisions rule. Thus, the 
requirement in subpart K, 40 CFR 51.212(c), is met.
---------------------------------------------------------------------------

    \106\ Credible Evidence Revisions, 62 FR 8314, 8316 (February 
24, 1997).
---------------------------------------------------------------------------

    Comment B.10: The proposal lacks an analysis and determination as 
to whether the monitoring requirements are met. Section 110(a)(2)(F)(i) 
covers monitoring emissions by owners and operators from stationary 
sources, and 40 CFR 51.214 contains explicit monitoring requirements. 
EPA's proposal fails to explain whether the permit conditions proposed 
for approving into the SIP meet these requirements.
    Response: We disagree with the commenter's assertion that the 
proposal lacks an analysis and determination as to whether the permit 
conditions meet the monitoring requirements in CAA section 
110(a)(2)(F)(i) and 40 CFR 51.214. The Arkansas Regional Haze Phase III 
SIP revision meets the applicable monitoring requirements under 40 CFR 
51.214. In addition, it meets the applicable requirements found in 40 
CFR 51.308(e)(2)(iii), which discusses rules for accounting and 
monitoring emissions, and procedures for enforcement of BART 
alternatives. This is established through our analysis of the 
monitoring regime discussed above in response to comments 2.B.3, 2.B.4, 
and 2.B.7. Commenter does not provide any further information with 
reasonable specificity as to how the applicable monitoring requirements 
in subparts K or P fail to be met. As discussed previously, the 
Arkansas SIP includes procedures in APCEC Regulation 19.703,\107\ 
including detailed information regarding CEMS, which DEQ has authority 
to administer. These procedures are already part of the State's plan 
requiring monitoring of this source's emissions. Because these 
monitoring provisions have already been adopted into the Arkansas SIP, 
the permit conditions pertaining to the BART alternative conditions 
will be administered under these existing approved provisions for 
monitoring. This is sufficient to meet the monitoring requirements in 
40 CFR 51.214 and 40 CFR 51.308(e)(2)(iii). Therefore, the applicable 
monitoring requirements for this SIP revision are being met.\108\
---------------------------------------------------------------------------

    \107\ APCEC Rule 19.703 includes detailed information regarding 
Continuous Emissions Monitoring. Any stationary source subject to 
this regulation shall, as required by federal law and upon request 
of the Department: (A) Install, calibrate, operate, and maintain 
equipment to continuously monitor or determine federally regulated 
air pollutant emissions in accordance with applicable performance 
specifications in 40 CFR part 60 Appendix B as of the effective date 
of the federal final rule published by EPA in the Federal Register 
on February 27, 2014 (79 FR 11271), and quality assurance procedures 
in 40 CFR part 60 Appendix F as of the effective date of the federal 
final rule published by EPA in the Federal Register on February 27, 
2014 (79 FR 11274), and other methods and conditions that the 
Department, with the concurrence of the EPA, shall prescribe. Any 
source listed in a category in 40 CFR part 51 Appendix P as of the 
effective date of the federal final rule published by EPA in the 
Federal Register on November 7, 1986 (51 FR 40675), or in 40 CFR 
part 60 as of August 30, 1992, shall adhere to all continuous 
emissions monitoring or alternative continuous emission monitoring 
requirements stated therein, if applicable. (B) Report the data 
collected by the monitoring equipment to the Department at such 
intervals and on such forms as the Department shall prescribe, in 
accordance with 40 CFR part 51, Appendix P, Section 4.0 (Minimum 
Data Requirements) as of the effective date of the federal final 
rule published by EPA in the Federal Register on November 7, 1986 
(51 FR 40675), and any other applicable reporting requirements 
promulgated by the EPA.
    \108\ See 52.170(c) (table) for EPA-approved regulations in the 
Arkansas SIP.
---------------------------------------------------------------------------

C. Requirements for Emissions Reductions To Occur During the First 
Implementation Period and a Compliance Schedule

    Comment C.1: The SIP fails to demonstrate that emission reductions 
occurred during the first planning period by December 31, 2018 pursuant 
to 40 CFR 51.308(e)(2)(iii). EPA's proposal describes the emission 
reductions, but fails to explain whether the SIP contains the 
provisions necessary to satisfy regulatory

[[Page 15124]]

requirements. For example, there are no compliance dates in the SIP 
that shows the emission limitations were enforceable in the first 
planning period. Furthermore, there is nothing in the SIP that 
demonstrates the monitoring, recordkeeping, and reporting requirements 
applied during the first planning period. Therefore, EPA lacks a basis 
to approve the SIP as meeting the element of the rule that the emission 
reductions occurred within the first planning period. Related to this 
issue, EPA's proposal suggests that the SIP included compliance 
schedules for Domtar, but the SIP fails to include any compliance 
schedules.
    Response: We disagree with the commenter that the SIP fails to 
demonstrate that the required emission reductions occurred during the 
first planning period or that the SIP otherwise fails to meet the 
requirements of 40 CFR 51.308(e)(2)(iii). In our proposed approval, we 
explained that even though the BART alternative emission limits became 
enforceable by the State upon issuance of a minor modification letter 
sent by the State to Domtar on February 28, 2019,\109\ Domtar provided 
documentation demonstrating that Power Boilers No. 1 and 2 have been 
operating at emission levels below the BART alternative emission limits 
since December 2016. This shows that although the limits became 
enforceable shortly after the 2008 to 2018 planning period ended, 
Domtar had been in compliance with those limits for three years prior 
to the first planning period ending. Domtar's emission levels remained 
below the BART alternative levels up to the point at which the State's 
BART alternative emission limits and associated requirements became 
enforceable in February 2019. This is sufficient for the SIP submittal 
to meet the requirement of 40 CFR 51.308(e)(2)(iii).
---------------------------------------------------------------------------

    \109\ 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.
---------------------------------------------------------------------------

    The commenter argues that there is nothing in the SIP that 
demonstrates the monitoring, recordkeeping, and reporting requirements 
applied to the source during the first planning period. First, 40 CFR 
51.308(e)(2)(iii) does not impose this requirement and neither does any 
other provision of the BART alternative regulations. Rather, in order 
to demonstrate that BART alternative emission limits are being achieved 
by the end of the first planning period, ``the State must provide a 
detailed description of the emissions trading program or other 
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.'' \110\ EPA does not interpret this language as requiring 
that the monitoring, recordkeeping, and reporting requirements 
associated with a BART alternative must be in place and be state- or 
federally-enforceable before the end of the first planning period. The 
SIP must include such requirements, but with respect to demonstrating 
when they are applied to the source, it is reasonable that such 
requirements accompany the BART alternative. As discussed in the 
paragraph above, the reductions secured under the BART alternative have 
been documented to occur before the end of the first planning period, 
and the documentation further demonstrates that the requisite emission 
levels were maintained up until the point that the State imposed the 
enforceable BART-alternative emission limits and associated monitoring, 
recordkeeping, and reporting requirements on the source. This is 
sufficient to satisfy 40 CFR 51.308(e)(2)(iii).
---------------------------------------------------------------------------

    \110\ See 40 CFR 51.308(e)(2)(iii).
---------------------------------------------------------------------------

    In particular, the compliance documentation included a letter dated 
December 20, 2018, submitted to DEQ by Domtar,\111\ 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 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 that CEMS data, 
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, which is below 
the BART alternative PM10 emission limit of 81.6 pph 
PM10.\112\ This demonstrates that Power Boilers No. 1 and 
No. 2 at the Ashdown Mill satisfy the timing requirements of 40 CFR 
51.308(e)(2)(iii) and shows that the necessary emission reductions 
associated with the BART alternative occurred during the first long-
term strategy period for regional haze.
---------------------------------------------------------------------------

    \111\ See letter from Domtar to DEQ entitled, ``Demonstration of 
Compliance with Proposed BART Alternative,'' included with the SIP 
revision documenting compliance with the Phase III SIP emission 
limits.
    \112\ See information provided in letters dated December 20, 
2018, and January 19, 2017, submitted by Domtar to DEQ. 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.
---------------------------------------------------------------------------

    In addition to being in compliance before the first implementation 
period ended, Domtar submitted additional letters to DEQ showing 
continued compliance for both power boilers. The letters contained CEMS 
emission data from January 2018 to April 2019.\113\ This CEMS data 
demonstrated continued compliance for Power Boiler No. 2 by showing 
emission levels below the BART alternative emission limits beyond 2018. 
Domtar noted that Power Boiler No. 1 continued to be in standby mode 
and that its emissions have been 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.
---------------------------------------------------------------------------

    \113\ See letters from Domtar to DEQ 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.
---------------------------------------------------------------------------

    The commenter argues that there are no compliance dates in the SIP 
that show that the emission limitations were enforceable in the first 
planning period. This is not required by EPA's regulations, as 
explained above. In addition, there is no schedule for future 
compliance because the source is already complying with the emission 
limits which are already in place and enforceable through the State 
permit. Upon the effective date of this final action the emission 
limits (and associated requirements) will be federally enforceable. 
These provisions have never been administratively or judicially stayed, 
are currently in effect, and will remain in effect; the source has been 
compliant with those requirements. We note with respect to the 
SO2 and NOX BART limits

[[Page 15125]]

promulgated by the FIP, which is now being withdrawn in this action, 
the compliance schedule did not require that these limits be in effect 
until October 27, 2021. Domtar has been in compliance with those 
schedules for both boilers for the past three years.
    For these reasons, the State's BART alternative SIP revision for 
Domtar Ashdown Mill meets the provisions of 40 CFR 51.308(e)(2)(iii): 
It documents that the required reductions took place during the period 
of the first long-term strategy (i.e. before the end of 2018) and those 
reductions continued up until the point the enforceable BART 
alternative emission limits took effect at the state level. The BART 
alternative limits are now in effect, satisfying the implementation-
schedule requirement of (e)(2)(iii), and the SIP establishes relevant 
monitoring, recordkeeping, and reporting requirements, as set forth in 
plantwide permit conditions 32 to 43 and the associated provisions of 
the State's SIP-approved monitoring and compliance regulations found at 
APCEC Rule 19, Chapter 7.\114\
---------------------------------------------------------------------------

    \114\ See 52.170(c) (table) for EPA-approved regulations in the 
Arkansas SIP.
---------------------------------------------------------------------------

D. The CAA 110(l) Anti-Backsliding Provision

    Comment D.1: The proposed rule violates the Clean Air Act's ``anti-
backsliding'' requirement at 42 U.S.C. 7410(l) because compared to the 
existing federal plan, the State's plan would result in greater air 
pollution. EPA's proposal explains that ``[b]ased on an assessment of 
current air quality in the areas most affected by this SIP revision, we 
are concluding that the less stringent SO2 emission limits 
in the Phase III SIP will not interfere with attainment of the NAAQS.'' 
EPA's proposal fails to explain and provide information regarding what 
areas it assessed and the basis for its assessment. Moreover, EPA's 
analysis only considers regional haze and the NAAQS, and not other CAA 
requirements such as PSD increments. Moreover, the increase in 
SO2 emissions under the SIP relative to the FIP violates the 
Clean Air Act's section 110(l) anti-backsliding provision, which 
provides that ``[t]he Administrator shall not approve a revision of a 
plan if the revision would interfere with any applicable requirement 
concerning attainment and reasonable further progress . . . or any 
other applicable requirement of this chapter.'' Section 110(l) 
prohibits plan revisions that would interfere with any applicable 
requirement, including a BART determination. When determining whether a 
plan revision interferes with NAAQS attainment, EPA has interpreted 
section 110(l) as preventing plan revisions that would increase overall 
air pollution or worsen air quality. In Kentucky Resources Council, 
Inc. v. EPA, 467 F.3d 986 (6th Cir. 2006), EPA interpreted section 
110(l) as allowing the agency to approve a plan revision that weakened 
some existing control measures while strengthening others, but only 
``[a]s long as actual emissions in the air are not increased.'' The 
Eleventh Circuit and the Seventh Circuit have upheld EPA's section 
110(l) interpretation as prohibiting plan revisions that would increase 
emissions or worsen air quality.\115\ In a discussion regarding a 
challenge to the Nevada regional haze plan, the Ninth Circuit also 
suggested that a haze plan that ``weakens or removes any pollution 
controls'' would violate section 110(l).\116\ Emissions under the 
Domtar BART alternative would increase, which is plainly at odds with 
CAA anti-backsliding requirements and the interpretation of these 
provisions in various circuit courts.
---------------------------------------------------------------------------

    \115\ Indiana v. EPA, 796 F.3d 803 (7th Cir. 2015); Alabama 
Envtl. Council v. EPA, 711 F.3d 1277 (11th Cir. 2013).
    \116\ WildEarth Guardians v. EPA, 759 F.3d 1064 (9th Cir. 2014).
---------------------------------------------------------------------------

    Response: We disagree with the commenter that ``the proposed rule 
violates the CAA's anti-backsliding requirement due to an increase in 
SO2 emissions under the SIP relative to the FIP.'' For the 
reasons explained below, EPA concludes that CAA section 110(l) does not 
prohibit approval of this SIP.
    Under CAA Section 110(l), the EPA cannot approve a plan revision 
``if the revision would interfere with any applicable requirement 
concerning attainment and reasonable further progress, or any other 
applicable requirement of this chapter.'' \117\ Section 110(l) applies 
to all requirements of the CAA, and it applies to all areas of the 
country, whether attainment, nonattainment, unclassifiable, or 
maintenance for one or more of the six criteria pollutants. The EPA 
interprets section 110(l) as applying to all NAAQS that are in effect, 
including those for which SIP submissions have not been made. A section 
110(l) demonstration should address all pollutants whose emissions and/
or ambient concentrations may change as a result of a plan revision, 
even if the SIP provision was originally adopted only to address one 
particular NAAQS. In general, the level of rigor needed for any CAA 
section 110(l) demonstration will vary depending on the nature of the 
revision. Where available attainment demonstration or maintenance plans 
indicate that any change in emissions will not interfere with any 
applicable requirement concerning attainment and reasonable further 
progress, or any other applicable CAA requirement, EPA may rely on such 
plans to demonstrate that section 110(l) does not prohibit approval of 
the plan.
---------------------------------------------------------------------------

    \117\ Note that ``reasonable further progress'' as used in CAA 
section 110(l) is a reference to that term as defined in section 
301(a) (i.e., 42 U.S.C. 7501(a)), and as such means reductions 
required to attain the NAAQS set for criteria pollutants under 
section 109. This term as used in section 110(l) (and defined in 
section 301(a)) is not synonymous with ``reasonable progress'' as 
that term is used in the regional haze program. Instead, section 
110(l) provides that the EPA cannot approve plan revisions that 
interfere with regional haze requirements (including reasonable 
progress requirements) insofar as they are ``other applicable 
requirements'' of the CAA.
---------------------------------------------------------------------------

    A state, instead of submitting an air quality analysis showing that 
the revision will not interfere with any applicable requirement, may 
substitute equivalent emissions reductions to compensate for any change 
to a plan to ensure actual emissions to the air are not increased and 
thus preserve status quo air quality. Equivalent emissions reductions 
are reductions that are equal to or greater than those reductions 
achieved by the control measure approved into the plan. To show that 
compensating emissions reductions are equivalent, adequate 
justification must be provided. The compensating, equivalent reductions 
should represent actual emissions reductions achieved in a 
contemporaneous time frame to the change of the existing control 
measure in order to preserve the status quo air quality. In addition to 
being contemporaneous, the equivalent emissions reductions should also 
be permanent, enforceable, quantifiable, and surplus. A showing that 
the substitute measures preserve status quo air quality is generally 
sufficient to demonstrate noninterference through this alternative 
approach.
    As an initial matter, the commenter misstates the EPA's 
interpretation of CAA section 110(l). Neither EPA nor any court has 
concluded, as the commenter asserts, that plan revisions are 
permissible only if emissions to the air are not increased. The case 
cited by the commenter, Kentucky Resources Council, Inc. v. EPA, 467 
F.3d 986 (6th Cir. 2006), involved a situation in which the state had 
opted to substitute equivalent emission reductions to compensate for 
emission changes associated with the plan revision, and the EPA 
concluded that the offsetting emission reductions were adequate to

[[Page 15126]]

maintain the status quo air quality.\118\ Because no attainment 
demonstrations were available to guide an analysis of whether the 
revision would interfere with attainment of the NAAQS, the EPA had 
relied on its conclusion that status quo air quality would be 
maintained instead of conducting an air quality analysis evaluating the 
impact on attainment and maintenance of the NAAQS. The court upheld, as 
a reasonable reading of the statute entitled to deference, the EPA's 
conclusion that approval of the SIP revision was permissible in those 
circumstances.\119\ The court held that the use of substitute measures 
was permissible, not that such measures were required in every 
circumstance.\120\
---------------------------------------------------------------------------

    \118\ See Kentucky Resources, 467 F.3d at 996 (evaluating the 
EPA's conclusion that the reductions were adequate to maintain 
status quo air quality).
    \119\ See id. at 995.
    \120\ In that same case, the court emphasized that ``it seems 
fairly clear that Congress did not intend that the EPA reject each 
and every SIP revision that presents some remote possibility for 
interference. Thus, where the EPA does not find that a SIP revision 
would interfere with attainment, approval of the revision does no 
violence to the statute.'' Kentucky Resources, 467 F.3d at 994.
---------------------------------------------------------------------------

    The Seventh Circuit decision mentioned by commenter--Indiana v. 
EPA, 796 F.3d 803 (7th Cir. 2015)--does not support commenter's 
argument. This case emphasizes that the EPA is required to determine 
whether the revision would, going forward, interfere with attainment. 
In Indiana, the court rejected arguments that the revised program could 
not be approved because it had led to a past O3 NAAQS 
exceedance.\121\ The court also agreed that it was permissible for EPA 
to rely on the fact that the state demonstrated that substitute 
measures more than offset any increase associated with the plan 
revision. In the context of reviewing whether the substitute measures 
were sufficient, the court explained that ``EPA can approve a SIP 
revision unless the agency finds it will make the air quality worse.'' 
\122\ In doing so, however, the court did not hold that substitute 
measures are always required to demonstrate noninterference under CAA 
section 110(l) or that section 110(l) prohibits approval of any SIP 
revision which leads to an increase in emissions.\123\
---------------------------------------------------------------------------

    \121\ Id.
    \122\ Id.
    \123\ Id.
---------------------------------------------------------------------------

    The Ninth Circuit decision commenters cite--WildEarth Guardians v. 
EPA, 759 F.3d 1064 (9th Cir. 2014)--also does not establish that EPA is 
prohibited from approving this SIP. In WildEarth Guardians, the Ninth 
Circuit rejected a challenge to an EPA action approving a haze plan and 
concluded that WildEarth had identified ``nothing in the SIP that 
weakens or removes any pollution controls. And even if the SIP merely 
maintained the status quo, that would not interfere with the attainment 
or maintenance of the NAAQS.'' For that reason, the court concluded 
that WildEarth had failed to show that EPA's approval of the SIP 
contravened CAA section 110(l).\124\ In brief, the court explained that 
a plan approval that does not weaken or remove pollution controls would 
not violate section 110(l). The court did not, however, suggest that 
any plan that weakens or removes pollution controls would necessarily 
violate CAA section 110(l). Several courts have deferred to EPA's 
interpretation of the phrase ``would interfere'' in CAA Section 
110(l).\125\ In addition, determinations that are scientific in nature 
are entitled to the most deference on review.\126\ The county that 
Domtar is located in (Little River County) was previously designated as 
``Attainment/Unclassifiable.'' for the 2010 SO2 NAAQS.\127\ 
In addition, EPA has evaluated the air quality impact of the repeal of 
the FIP requiring BART controls and the approval of the BART 
alternative limits. As mentioned in the proposed approval, the BART 
alternative limits do not reduce SO2 emissions as much as 
the BART controls in the FIP; however, all areas in Arkansas have been 
and are currently attaining all of the NAAQS, even though the 
SO2 BART controls for Domtar have not been implemented. 
Those controls were not obligated to be in place until October 27, 
2021, when the BART emission limits would have taken effect under the 
FIP. Therefore, even though the BART alternative will not achieve the 
same level of emission reductions for SO2 as the BART FIP 
would have (in 2021), there is no reason to expect that this will 
negatively impact current air quality, which is already sufficient to 
attain the SO2 NAAQS in Arkansas and (as discussed further 
below) any other areas that could be impacted by SO2 
emissions from this source. Further, the State of Missouri did not rely 
on reductions from Domtar for its regional haze plans, and the EPA is 
not aware of (nor has commenter identified) any other air quality 
analyses that rely on implementation of the BART requirements for 
Domtar in the FIP. The proposed withdrawal of the BART provisions in 
the FIP and replacement with the BART alternative requirements in the 
SIP will not cause air quality to become worse than current air quality 
or interfere with existing plans to attain and maintain the NAAQS.
---------------------------------------------------------------------------

    \124\ Id. at 1074.
    \125\ See, e.g., Alabama Envtl. Council v. EPA, 711 F.3d 1277, 
1292-93 (11th Cir. 2013); Galveston-Houston Ass'n for Smog 
Prevention v. EPA, 289 Fed. Appx. 745, 754 (5th Cir. 2008); Kentucky 
Resources Council, 467 F.3d at 995.
    \126\ See Ass'n of Irritated Residents v. EPA, 423 F.3d 989, 997 
(9th Cir. 2005).
    \127\ 83 FR 1098 (January 9, 2018).
---------------------------------------------------------------------------

    The more stringent SO2 emission limits for Domtar in the 
BART FIP did not go into effect before the SIP BART alternative 
replaced them. Given that current air quality is already sufficient to 
attain the SO2 NAAQS in Arkansas and any other areas that 
could be impacted by SO2 emissions from this source, there 
is no evidence that withdrawal of the SO2 limits in the FIP 
for Domtar and the approval of the SO2 emission limits in 
the Arkansas Regional Haze Phase III SIP revision will interfere with 
attainment of the 2010 one-hour SO2 NAAQS or the 2006 24-
hour or the 2012 annual PM2.5 NAAQS (of which SO2 
is a precursor). In addition, 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. At this time, all areas that would be potentially 
impacted by the increase in SO2 emissions allowed under the 
SIP revision as compared to the FIP are attaining the 2010 one-hour 
SO2 NAAQS, the 2006 24-hour PM2.5 NAAQS, and the 
2012 annual PM2.5 NAAQS without the FIP-required controls 
being in operation. Based on this assessment of current air quality in 
the areas most affected by this SIP revision, we conclude that the less 
stringent SO2 emission limits in the Phase III SIP will not 
interfere with attainment of these NAAQS.
    The commenter states that EPA's proposal fails to explain and 
provide information regarding what areas it assessed and the basis for 
its assessment. With respect to regional haze requirements, we disagree 
with the commenter. We explained in the proposal that we considered all 
Class I areas in Arkansas and also considered those in Missouri, which 
is the only State that was determined to potentially be impacted by 
sources from within Arkansas for the first implementation period. 
Missouri is currently not relying on emission reductions from Domtar in 
its regional haze plan.
    Further, there are no PM2.5 or SO2 
nonattainment areas in any other state that could be impacted by the 
emissions from Domtar. Regarding PM nonattainment areas in other 
states, EPA

[[Page 15127]]

previously approved Arkansas' interstate transport SIP submittals under 
CAA 110(a)(2)(D)(i)(I), which established that emissions from Arkansas 
do not significantly contribute to nonattainment or interfere with 
maintenance of the 2006 24-hour or 2012 annual PM2.5 NAAQS 
in any other state.\128\ Concerning SO2 nonattainment areas 
in other states,\129\ the nearest SO2 nonattainment area to 
Domtar is within Titus County, Texas, approximately 100 km away. EPA 
designated part of Titus County, around the Monticello Power Plant, as 
nonattainment in Round 2 of the SO2 designations 
process.\130\ Domtar is also not near any large SO2 sources 
in other states. Large SO2 sources greater than 100 tpy 
SO2 in Oklahoma [IP Vaillant Paper Mill (100 km away) and 
Hugo Station (119 km away)] and Texas [Welsh Power Plant (95 km away)] 
are all approximately 100 km away from Domtar, which is too far for 
Domtar to contribute to air quality in those areas. 50 km is the useful 
distance to which AERMOD is considered accurate. Therefore, under the 
Data Requirements Rule (DRR), sources beyond 50 km were determined to 
not cause concentration gradient impacts within the area of analysis. 
The distance between Domtar and any of the large SO2 sources 
in neighboring states makes it unlikely that SO2 emissions 
from Arkansas interact with emissions from another state in such a way 
as to contribute to existing nonattainment of the 2010 one-hour 
SO2 NAAQS. The DRR SO2 monitor \131\ for the 
Welsh Power Plant (the closest large source to Domtar), showed 
attainment and characterized the air quality design value for 2017 to 
2019 as 28 parts per billion (ppb) SO2 which is below the 
2010 one-hour SO2 NAAQS of 75 ppb SO2. For these 
reasons, we conclude that emissions from Domtar will not adversely 
impact air quality in PM2.5 or SO2 nonattainment 
areas in any other state.
---------------------------------------------------------------------------

    \128\ See 78 FR 53269 (August 30, 2013) regarding the 2006 24-
hour PM2.5 NAAQS and 83 FR 47569 (November 7, 2018) 
regarding the 2012 annual PM2.5 NAAQS.
    \129\ See TSD associated with the Arkansas SO2 
transport final action (84 FR 55864) in Docket number EPA-R06-OAR-
2019-0438 titled, ``Technical Support Document Arkansas SIP 
Addressing the Interstate Transport of Air Pollution Requirements of 
CAA 110(a)(2)(D)(i)(I) for the 2010 Sulfur Dioxide Primary National 
Ambient Air Quality Standard March 2019.'' (pages 24-25)
    \130\ See 81 FR 89870.
    \131\ Texas installed and began operation of a new, approved 
monitor in Titus County on December 7, 2016 to characterize air 
quality around the Welsh Power Plant.
---------------------------------------------------------------------------

    The commenter argues that DEQ addressed the reasonable progress 
requirements under 40 CFR 51.308(d)(1) based on faulty analysis that 
the BART alternative for Domtar is approvable. We addressed objections 
to the BART alternative under 40 CFR 51.308(e) in section III.A of this 
final action and explained why the BART alternative provides greater 
reasonable progress for regional haze. We also explained how the 
reasonable progress requirements for regional haze under 40 CFR 
51.308(d)(1) are being met, and found that reasonable progress was not 
impacted by the transition from the BART FIP requirements to the BART 
alternative at Domtar. Therefore, the BART alternative does not 
interfere with ``reasonable progress'' under the Regional Haze Rule as 
an ``other CAA requirement'' that could be affected under CAA 110(l).
    The commenter mentioned that EPA's analysis only considers regional 
haze and the NAAQS, and not the other CAA requirements, for example, 
PSD increments. The commenter asserts that, for this reason also, EPA 
fails to demonstrate that withdrawing the FIP and approving the State's 
SIP complies with Section 110(l) of the Act. EPA did not evaluate PSD 
increments in the proposal for two reasons: (1) Both power boilers were 
in operation before the major source baseline trigger dates for all 
three pollutants with increments (SO2, NOX, and 
PM/PM10/PM2.5); and (2) both the FIP limits and 
alternative BART limits are less than past actual emissions (both on an 
annual tons per year basis and a short-term emission rate basis), so 
increment around the Domtar facility was being expanded, not consumed. 
We noted in our proposed approval that the BART alternative emission 
rates were 44 percent lower for SO2 and 51 percent lower for 
NO2 compared to previously permitted emission rates.\132\ 
Based on this and the knowledge that the power boilers historically 
have operated greater than 56 percent of their permitted rates on a 
short term and annual basis, it can be concluded that increment was 
being expanded by the BART alternative. The major source baseline 
trigger date for PM/PM10/PM2.5 and SO2 
increment was August 7, 1977. The major source baseline trigger date 
for NOX was February 8, 1988. Both Power Boiler No. 1 and 
Power Boiler No. 2 are baseline increment sources since they received 
permits and/or were in operation before the major source baseline date 
for NOX, SO2 and PM/PM10/
PM2.5 increments. PM/PM10/PM2.5, 
SO2, and NOX all have annual increment standards; 
SO2 has a three-hour and a 24-hour increment standard, and 
PM/PM10/PM2.5 all have 24-hour Class II increment 
standards. The Air Quality Control Region (AQCR) that Domtar facility 
is located in is AQCR 22, and the minor source baseline date for AQCR 
22 was triggered for PM/PM10/PM2.5 and 
SO2 by a PSD permit modification (Domtar permit 287-AR-3) on 
May 31, 1983.133 134 The NOX minor source 
baseline date was triggered for NOX in AQCR 22 by a PSD 
permit modification (Domtar permit 946-A) on August 31, 1989.\135\
---------------------------------------------------------------------------

    \132\ See proposed approval notice (85 FR 14854).
    \133\ Arkansas AQCR Map (https://www.adeq.state.ar.us/air/permits/pdfs/aqcr.pdf).
    \134\ Arkansas Minor Source Baseline Dates (https://www.adeq.state.ar.us/air/permits/pdfs/minor_source_baseline_dates.pdf).
    \135\ Id.
---------------------------------------------------------------------------

    The conversion of Power Boiler No. 1 to burn only natural gas was 
an increment expanding change. For the purpose of overall increment 
analysis, we evaluated the emissions of Power Boiler No. 1 prior to the 
conversion of only burning natural gas as these emissions were part of 
the pre-BART baseline. As can be seen in Table 1, the annual emission 
limits (tpy) for the Arkansas BART alternative are less than the 
Arkansas baseline actual emissions for SO2, NOX, 
and PM/PM10/PM2.5. Therefore, the Arkansas BART 
alternative results in annual increment expansion for all three 
pollutants.

                                       Table 1--Annual Emissions Analysis
----------------------------------------------------------------------------------------------------------------
                                                                               Emission rates (tpy)
                            Condition                            -----------------------------------------------
                                                                        SO2             NOX            PM10
----------------------------------------------------------------------------------------------------------------
Arkansas Baseline (Actual Emissions)............................           3,544           3,216             491
Arkansas BART FIP...............................................             493           2,420             537
Arkansas BART Alternative.......................................           1,907           2,120             380
BART Alternative Reduction from Baseline (Baseline Minus                   1,637           1,096             111
 Alternative)...................................................
----------------------------------------------------------------------------------------------------------------


[[Page 15128]]

    As can be seen in Table 2, the short-term emission limits (pph) for 
the Arkansas BART alternative are less than the previously permitted 
limits, the Arkansas baseline (2001-2003 actual emissions), and the 
BART FIP baseline emissions (mixture of 2001-2003 and 2009-2011 actual 
emissions) for SO2, NOX, and PM/PM10/
PM2.5. Therefore, the Arkansas BART alternative results in 
short-term increment expansion for SO2 and PM/
PM10/PM2.5 pollutants (there is no short term 
increment for NOX). Therefore, removal of the FIP and 
approval of the Arkansas BART alternative would not interfere with PSD 
increments.

                                     Table 2--Short Term Emissions Analysis
----------------------------------------------------------------------------------------------------------------
                                                                   Emission Rate (pph) (30 boiler-operating day
                                                                                 rolling average)
                            Condition                            -----------------------------------------------
                                                                        SO2             NOX            PM10
----------------------------------------------------------------------------------------------------------------
Power Boiler No. 1 (580 MMBTU/hr)
    Previously Permitted (Prior to natural gas conversion) *....           1,285           247.5             343
    Arkansas SIP BART Baseline (2001-2003)......................           442.5           179.5           169.5
    BART FIP Baseline...........................................            21.0           207.4            30.4
    Arkansas BART Alternative **................................             0.5           191.1             5.2
Power Boiler No. 2 (820 MMBTU/hr)
    Previously Permitted........................................             984             574              82
    Arkansas SIP BART Baseline (2001-2003)......................           788.2           526.8            81.6
    BART FIP Baseline...........................................           788.2           526.8            81.6
    Arkansas BART Alternative **................................             435             293            81.6
Power Boiler No. 1 & Power Boiler No. 2
    Previously Permitted (Prior to Power Boiler No. 1 natural              2,269           821.5             425
     gas conversion) *..........................................
    Arkansas SIP BART Baseline (2001-2003)......................         1,230.7           706.3           251.1
    BART FIP Baseline...........................................           809.2           734.2             112
    Arkansas BART Alternative **................................           435.5           484.1            86.8
----------------------------------------------------------------------------------------------------------------
* Not 30 boiler-operating day rolling average (Prior to Power Boiler No. 1 natural gas conversion). See Permit
  No. 287-AOP-R2 (8/16/2001). DEQ permits for Domtar are available at https://www.adeq.state.ar.us/home/pdssql/p_facil_info.aspx?AFINDash=41-00002&AFIN=4100002.
** See Plantwide Condition #32 of DEQ Air Permit No. 0287-AOP-R22 limits in Table 1 of the proposed approval (85
  FR 14854).

    As discussed above, EPA's technical documentation shows that 
approval of the Arkansas SIP submittal is not prohibited under CAA 
section 110(l). As also explained above, CAA section 110(l) does not 
prohibit states from submitting a SIP less stringent than a FIP or 
replacing a SIP with a less stringent SIP. Even though the requirements 
adopted in the SIP revision here do not match the emissions limitations 
in the FIP, there is no expectation that approval of the SIP will 
interfere with attainment or maintenance of the NAAQS or any other 
requirements under the Act.

E. Interstate Visibility Transport and Regional Haze Reasonable 
Progress Requirements

    Comment E.1: A state can satisfy prong 4 interstate transport 
requirements with a fully approved regional haze SIP. EPA's proposal 
contains numerous fatal flaws and EPA cannot approve the State's SIP 
submittal for Domtar Ashdown Mill. Therefore, EPA similarly cannot 
approve prong 4 since the State does not have a fully approvable 
regional haze SIP. Similarly, EPA cannot determine the State's SIP 
meets the reasonable progress requirements under 40 CFR 51.308(d)(1) 
since the State's BART alternative fails to comply with the Act and 
regulations.
    Response: We disagree with the commenter's assertion that EPA is 
prohibited from approving the Arkansas SIP submission regarding 
interstate visibility transport requirements and regional haze 
reasonable progress requirements. As explained in our proposed 
rule,\136\ a state can demonstrate compliance with CAA section 
110(a)(2)(D)(i)(II) prong 4 by either having a fully-approved regional 
haze SIP or by demonstrating that emissions within its jurisdiction do 
not interfere with another air agency's plans to protect 
visibility.\137\ The State addressed interstate visibility transport 
requirements in its 2018 Phase II SIP revision, as supplemented by the 
Arkansas 2015 O3 NAAQS Interstate Transport SIP revision 
(submitted October 4, 2019), for the following NAAQS: the 2006 24-hour 
PM2.5 NAAQS; the 2012 annual PM2.5 NAAQS; the 
2008 and 2015 eight-hour O3 NAAQS; the 2010 one-hour 
NO2 NAAQS; and the 2010 one-hour SO2 NAAQS. The 
State's analysis in the Arkansas 2015 O3 NAAQS Interstate 
Transport SIP supersedes the interstate visibility transport portion of 
the 2017 infrastructure SIP.\138\
---------------------------------------------------------------------------

    \136\ See 85 FR 14847.
    \137\ 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).
    \138\ See 83 FR 6470. 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.
---------------------------------------------------------------------------

    As to the first basis for approval, the Arkansas Regional Haze 
NOX SIP revision \139\ (Phase I), the Arkansas Regional Haze 
SO2 and PM SIP revision \140\ (Phase II), and this action 
(the Arkansas Regional Haze Phase III SIP revision) together fully 
address the State's outstanding regional haze requirements for the 
first planning period and address the deficiencies of the 2008 Arkansas 
Regional Haze SIP that were identified in EPA's March 12, 2012, action. 
Thus, Arkansas now has a fully-approved regional haze SIP for the first 
planning period. This is sufficient under EPA's 2013 infrastructure SIP 
guidance to determine that Arkansas has also adequately addressed 
interstate visibility transport under ``prong 4'' for the above-listed 
NAAQS.
---------------------------------------------------------------------------

    \139\ 83 FR 5927.
    \140\ 84 FR 51033.
---------------------------------------------------------------------------

    As an alternative basis for approval of Arkansas' CAA section 
110(a)(2)(D)(i)(II) prong 4 SIP submittals, EPA finds that DEQ provided 
an adequate demonstration that it is not interfering with other states' 
visibility programs in the Arkansas 2015 O3 NAAQS Interstate 
Transport SIP submittal, which addressed the prong 4 requirements for

[[Page 15129]]

the six NAAQS previously mentioned. Arkansas documented its 
apportionment of emission reduction obligations needed at the affected 
Class I areas in other states and provided a demonstration that the SIP 
includes approved federally enforceable measures that contribute to 
achieving the 2018 RPGs set for those areas.\141\ The demonstration 
showed that emissions within Arkansas' jurisdiction do not interfere 
with other air agencies' plans to protect visibility, as expressed via 
the 2018 reasonable progress goals for Class I areas in other states. 
In particular, Arkansas' SIP submittals demonstrated that the RPGs for 
the only two Class I areas outside Arkansas potentially impacted by 
Arkansas emissions, Hercules-Glades Wilderness and Mingo National 
Wildlife Refuge, in Missouri, were achieving the visibility goals that 
were determined through interstate consultation. Further, the emissions 
from certain EGU sources in Arkansas are demonstrated to be below the 
levels Arkansas had agreed to in the interstate consultation process.
---------------------------------------------------------------------------

    \141\ See 85 FR 14847, 14865.
---------------------------------------------------------------------------

    For these reasons, Arkansas has fulfilled its prong 4 visibility 
transport requirements for the 2006 24-hour PM2.5 NAAQS; the 
2012 annual PM2.5 NAAQS; the 2008 and 2015 eight-hour 
O3 NAAQS; the 2010 one-hour NO2 NAAQS; and the 
2010 one-hour SO2 NAAQS in accordance with EPA's 2013 
infrastructure SIP guidance. This alternative basis for approving these 
SIP submittals is not dependent on Arkansas having a fully approved 
Regional Haze SIP for the first planning period, and it is not 
dependent on the emission reductions achieved by the BART alternative 
for the two BART sources at Domtar Ashdown Mill. Thus, this basis for 
these prong 4 approvals is independent and severable from any other 
aspect of this action. Such approvals, on this basis, would not be 
affected by any administrative or judicial action altering, modifying, 
vacating, remanding, staying, or enjoining any other aspect of this 
action.
    The commenter's objections to EPA approving reasonable progress 
requirements have been addressed in previous responses in this 
document.

F. Comments From Domtar

    Comment F.1: Overall the commenter agrees with EPA's summary of 
ADEQ's BART Alternative for the Ashdown Mill, and further agrees that 
the BART Alternative, by the clear weight of evidence, achieves greater 
reasonable progress than the FIP. Commenter supports EPA's 
determination that the BART Alternative meets the applicable Regional 
Haze requirements and supports approving DEQ's Regional Haze Phase III 
SIP submittal. Commenter also agrees and supports EPA's determination 
that with this submittal ADEQ has satisfied all of the regional haze 
first planning period SIP requirements for Domtar.
    Response: We appreciate the commenter's support of our proposed 
approval.
    Comment F.2: The commenter believes a sufficient demonstration was 
made to grant an exemption under 40 CFR 51.303. However, for purposes 
of these comments, the commenter supports EPA's proposal with the 
reservation that it reserves the right to raise challenges to EPA's 
modeling approach in any effort to impose further reductions on the 
Ashdown Mill emissions in any subsequent Regional Haze SIP proceedings 
that may involve the Ashdown Mill.
    Response: We appreciate the commenter's support of our proposed 
approval. An exemption under 40 CFR 51.303 is outside the scope of this 
action.
    Comment F.3: Two nonsubstantive corrections were suggested for 
consideration to make the proposed action record factually correct, but 
do not affect the BART alternative limits or conditions: \142\
---------------------------------------------------------------------------

    \142\ See March 16, 2020 proposed approval (85 FR 14847).
---------------------------------------------------------------------------

     At 14851, middle column about two-thirds of the way down, 
referring to Power Boiler 1: `It is equipped with a wet electrostatic 
precipitator. . . .' It should be stated `It was. . . .' The wet 
electrostatic precipitator is no longer needed after the boiler was 
converted to burn natural gas.
     At 14855, middle column just above Table 2, referring to 
the FIP's nitrogen oxide (NOX) BART determination for Power 
Boiler 2: `. . . achieved by the installation and operation of low 
NOX burners.' The reference to low NOX burners 
needs to be removed.''
    Response: The EPA agrees with commenter's non substantive textual 
edits and the proposed SIP approval should read as follows:
    At 14851, ``It is equipped with a wet electrostatic precipitator'' 
should be changed to read:
    ``It was equipped with a wet electrostatic precipitator.'' With the 
conversion and permit modification to burn only natural gas, the wet 
electrostatic precipitator is no longer needed to control PM emissions 
from Power Boiler 1.
    At 14855, ``The NOX Best Available Retrofit Technology 
(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'' should be 
changed to read: ``The NOX BART determination for Power 
Boiler No. 2 is an emission limit of 345 pph on a thirty boiler-
operating-day rolling average consistent with the installation and 
operation of low NOX burners.'' (see 81 FR 66332, 66348). A 
BART determination is an emission limit based on the determination of a 
particular control strategy considering the BART factors, rather than a 
requirement to undertake the selected control.
    These non-substantive textual edits do not impact our analysis and 
our final decision regarding approval of the BART alternative for Power 
Boilers No. 1 and 2.

IV. Final Action

A. Arkansas Regional Haze Phase III SIP Submittal

    We finalize approval of the Arkansas Regional Haze Phase III SIP 
revision (submitted August 13, 2019) as meeting the applicable regional 
haze BART alternative provisions set forth in 40 CFR 51.308(e)(2) for 
the Domtar Ashdown Mill. Specifically, we finalize approval of the 
regional haze program-specific plantwide conditions 32 to 43 from 
section VI of permit revision #0287-AOP-R22 (effective August 1, 2019) 
into the SIP for implementing the Domtar BART alternative. These 
plantwide conditions of permit #0287-AOP-R22 \143\ include 
SO2, NOX, and PM10 emission limits and 
associated conditions for implementing these BART alternative limits 
for Power Boiler No. 1 and Power Boiler No. 2.
---------------------------------------------------------------------------

    \143\ The permittee will continue to be subject to the 
conditions as approved into the SIP even if the conditions are 
revised as part of a permit amendment by DEQ until such time as EPA 
approves any revised conditions into the SIP. The permittee shall 
remain subject to both the initial SIP-approved conditions and the 
revised SIP conditions, unless and until EPA approves the revised 
conditions.
---------------------------------------------------------------------------

    We finalize approval of the reasonable progress components under 40 
CFR 51.308(d)(1), to the extent they relate to Domtar Power Boilers No. 
1 and 2. With the approved Phase I and II SIP revision requirements and 
the Arkansas Regional Haze Phase III BART alternative requirements 
being approved in this final action, Arkansas has addressed all 
reasonable progress requirements under 40 CFR51.308(d)(1) with a fully-
approved regional haze SIP. We,

[[Page 15130]]

therefore, finalize approval of the emission limits and schedules of 
compliance long-term strategy element under 40 CFR 51.308(d)(3)(v)(3) 
pertaining to the Domtar Ashdown Mill in the August 13, 2019, 
submittal. With the final approval of the BART alternative requirements 
for the Domtar Ashdown Mill being addressed in this action, DEQ has 
satisfied all long-term strategy requirements under 40 CFR 
51.308(d)(3), as pertains to the first planning period for regional 
haze. We agree with DEQ's determination that the revised 2018 RPGs in 
the Phase II action do not need to be revised further. We finalize 
approval of the State's withdrawal of the current PM10 BART 
determination of 0.07 lb/MMBtu for Power Boiler No. 1 in the 2008 
Arkansas Regional Haze SIP, and approve its replacement with the 
PM10 BART alternative limit in the Arkansas Regional Haze 
Phase III SIP submittal. We finalize approval of Arkansas' consultation 
with FLMs and Missouri and finalize our determination that the SIP 
submittal satisfies the consultation requirements under 40 CFR 
51.308(i)(2) and 40 CFR 51.308(d)(3)(i).

B. Arkansas Visibility Transport

    We finalize approval of the portion of the Arkansas 2015 
O3 NAAQS Interstate Transport SIP revision (submitted 
October 4, 2019) addressing CAA section 110(a)(2)(D)(i)(II) prong 4 
visibility transport for the following six NAAQS: 2006 24-hour 
PM2.5 NAAQS; the 2012 annual PM2.5 NAAQS; the 
2008 and 2015 eight-hour O3 NAAQS; the 2010 one-hour 
NO2 NAAQS; and the 2010 one-hour SO2 NAAQS. We 
also finalize approval of the visibility transport portion of the 2018 
Phase II SIP revision, as supplemented by the Arkansas 2015 
O3 NAAQS Interstate Transport SIP revision. The State's 
analysis in the Arkansas 2015 O3 NAAQS Interstate Transport 
SIP supersedes the visibility transport portion of the 2017 
infrastructure SIP. We finalize approval of the prong 4 portions of 
these SIP submittals on the basis that Arkansas has a fully-approved 
regional haze SIP with our final approval of the Arkansas Regional Haze 
Phase III SIP submittal. The Arkansas Regional Haze NOX SIP 
revision,\144\ the Arkansas Regional Haze SO2 and PM SIP 
revision,\145\ and the Arkansas Regional Haze Phase III SIP revision 
together fully address the deficiencies of the 2008 Arkansas Regional 
Haze SIP that were identified in the March 12, 2012 partial approval/
partial disapproval action. Arkansas has a fully-approved regional haze 
SIP comprised of the portion of the 2008 Arkansas Regional Haze SIP 
approved in our 2012 final action, the Arkansas Regional Haze 
NOX SIP revision, the Arkansas Regional Haze SO2 
and PM SIP revision, and the Arkansas Regional Haze Phase III SIP 
revision. A fully-approved regional haze plan ensures that emissions 
from Arkansas sources do not interfere with measures required to be 
included in another air agencies' plans to protect visibility. As an 
alternative basis for approval of CAA section 110(a)(2)(D)(i)(II) prong 
4 for these NAAQS, we finalize a determination that Arkansas has 
provided an adequate demonstration in the October 4, 2019 submittal 
showing that emissions within its jurisdiction do not interfere with 
other air agencies' plans to protect visibility.
---------------------------------------------------------------------------

    \144\ Final action approved on February 12, 2018 (83 FR 5927).
    \145\ See 83 FR 62204 (November 30, 2018) for proposed approval 
and 84 FR 51033 (September 27, 2019) for final approval.
---------------------------------------------------------------------------

C. CAA Section 110(l)

    We finalize our determination that approval of the Arkansas 
Regional Haze Phase III SIP revision and concurrent withdrawal of the 
corresponding parts of the FIP meet the provisions of CAA section 
110(l).

V. Incorporation by Reference

    In this rule, the EPA is finalizing regulatory text that includes 
incorporation by reference. In accordance with requirements of 1 CFR 
51.5, the EPA is finalizing the incorporation by reference of revisions 
to the Arkansas source specific requirements as described in the Final 
Action section above. The EPA has made, and will continue to make, 
these materials generally available through www.regulations.gov a 
(please contact the person identified in the FOR FURTHER INFORMATION 
CONTACT section of this preamble for more information). Therefore, 
these materials have been approved by EPA for inclusion in the SIP, 
have been incorporated by reference by EPA into that plan, are fully 
federally enforceable under sections 110 and 113 of the CAA as of the 
effective date of the final rulemaking of EPA's approval, and will be 
incorporated by reference in the next update to the SIP compilation.

VI. Statutory and Executive Order Reviews

    Under the Clean Air Act, the Administrator is required to approve a 
SIP submission that complies with the provisions of the Act and 
applicable Federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). 
Thus, in reviewing SIP submissions, the EPA's role is to approve state 
choices, provided that they meet the requirements of the Clean Air Act. 
Accordingly, this action merely approves state law as meeting Federal 
requirements and does not impose additional requirements beyond those 
imposed by state law. For that reason, this action:
     Is not a ``significant regulatory action'' subject to 
review by the Office of Management and Budget under Executive Orders 
12866 (58 FR 51735, October 4, 1993) and 13563 (76 FR 3821, January 21, 
2011);
     Does not impose an information collection burden under the 
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
     Is certified as not having a significant economic impact 
on a substantial number of small entities under the Regulatory 
Flexibility Act (5 U.S.C. 601 et seq.);
     Does not contain any unfunded mandate or significantly or 
uniquely affect small governments, described in the Unfunded Mandates 
Reform Act of 1995 (Pub. L. 104-4);
     Does not have federalism implications as specified in 
Executive Order 13132 (64 FR 43255, August 10, 1999);
     Is not an economically significant regulatory action based 
on health or safety risks subject to Executive Order 13045 (62 FR 
19885, April 23, 1997);
     Is not a significant regulatory action subject to 
Executive Order 13211 (66 FR 28355, May 22, 2001);
     Is not subject to requirements of section 12(d) of the 
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 
note) because application of those requirements would be inconsistent 
with the CAA; and
     Does not provide EPA with the discretionary authority to 
address, as appropriate, disproportionate human health or environmental 
effects, using practicable and legally permissible methods, under 
Executive Order 12898 (59 FR 7629, February 16, 1994).
    In addition, the SIP is not approved to apply on any Indian 
reservation land or in any other area where EPA or an Indian tribe has 
demonstrated that a tribe has jurisdiction. In those areas of Indian 
country, the rule does not have tribal implications and will not impose 
substantial direct costs on tribal governments or preempt tribal law as 
specified by Executive Order 13175 (65 FR 67249, November 9, 2000).
    The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the 
Small Business Regulatory Enforcement Fairness Act of 1996, generally 
provides

[[Page 15131]]

that before a rule may take effect, the agency promulgating the rule 
must submit a rule report, which includes a copy of the rule, to each 
House of the Congress and to the Comptroller General of the United 
States. EPA will submit a report containing this action and other 
required information to the U.S. Senate, the U.S. House of 
Representatives, and the Comptroller General of the United States prior 
to publication of the rule in the Federal Register. A major rule cannot 
take effect until 60 days after it is published in the Federal 
Register. This action is not a ``major rule'' as defined by 5 U.S.C. 
804(2).
    Under section 307(b)(1) of the Clean Air Act, petitions for 
judicial review of this action must be filed in the United States Court 
of Appeals for the appropriate circuit by May 21, 2021. Filing a 
petition for reconsideration by the Administrator of this final rule 
does not affect the finality of this action for the purposes of 
judicial review nor does it extend the time within which a petition for 
judicial review may be filed, and shall not postpone the effectiveness 
of such rule or action. This action may not be challenged later in 
proceedings to enforce its requirements. (See section 307(b)(2).)

List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Best available 
retrofit technology, Incorporation by reference, Intergovernmental 
relations, Interstate transport of pollution, Nitrogen dioxide, Ozone, 
Particulate matter, Regional haze, Reporting and recordkeeping 
requirements, Sulfur oxides, Visibility.

    Dated: March 10, 2021.
David Gray,
Acting Regional Administrator, Region 6.
    Title 40, chapter I, of the Code of Federal Regulations is amended 
as follows:

PART 52--APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS

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

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

Subpart E--Arkansas

0
2. In Sec.  52.170:
0
a. The table in paragraph (d), entitled ``EPA-Approved Arkansas Source-
Specific Requirements'' is amended by adding an entry for ``Domtar 
Ashdown Mill'' at the end of the table.
0
b. In paragraph (e), the third table titled ``EPA-Approved Non-
Regulatory Provisions and Quasi-Regulatory Measures in the Arkansas 
SIP'' is amended by adding an entry for ``Arkansas Regional Haze Phase 
III SIP Revision'' at the end of the table.
    The additions read as follows:


Sec.  52.170  Identification of plan.

* * * * *
    (d) * * *

                               EPA-Approved Arkansas Source-Specific Requirements
----------------------------------------------------------------------------------------------------------------
                                                            State
                                                          approval/
          Name of source            Permit or order No.   effective     EPA approval date         Comments
                                                             date
----------------------------------------------------------------------------------------------------------------
 
                                                  * * * * * * *
Domtar Ashdown Mill..............  Permit..............     8/1/2019  3/22/2021 [Insert     Approval of
                                   #0287-AOP-R22.......                Federal Register      plantwide
                                                                       citation].            conditions 32 to 43
                                                                                             of section VI from
                                                                                             the permit,
                                                                                             addressing emission
                                                                                             limits for SO2,
                                                                                             NOX, and PM10 and
                                                                                             conditions for
                                                                                             implementing the
                                                                                             BART alternative
                                                                                             for Power Boilers
                                                                                             No. 1 and 2.
----------------------------------------------------------------------------------------------------------------

    (e) * * *

            EPA-Approved Non-Regulatory Provisions and Quasi-Regulatory Measures in the Arkansas SIP
----------------------------------------------------------------------------------------------------------------
                                                            State
                                        Applicable        submittal/
      Name of SIP provision            geographic or      effective     EPA approval date        Explanation
                                    nonattainment area       date
----------------------------------------------------------------------------------------------------------------
 
                                                  * * * * * * *
Arkansas Regional Haze Phase III   Statewide...........    8/13/2019  3/22/2021 [Insert     Approval of regional
 SIP Revision.                                                         Federal Register      haze SIP revision
                                                                       citation].            pertaining to the
                                                                                             Domtar Ashdown mill
                                                                                             that addresses SO2,
                                                                                             NOX, and PM10 BART
                                                                                             alternative
                                                                                             requirements under
                                                                                             40 CFR
                                                                                             51.308(e)(2);
                                                                                             reasonable progress
                                                                                             components under 40
                                                                                             CFR 51.308(d)(1);
                                                                                             and long-term
                                                                                             strategy components
                                                                                             under 40 CFR
                                                                                             51.308(d)(3) for
                                                                                             this facility.

[[Page 15132]]

 
Arkansas 2015 O3 NAAQS Interstate  Statewide...........    10/4/2019  3/22/2021 [Insert     Approval of
 Transport SIP Revision.                                               Federal Register      visibility
                                                                       citation].            transport portion
                                                                                             of this interstate
                                                                                             transport SIP
                                                                                             revision that
                                                                                             addresses CAA
                                                                                             section
                                                                                             110(a)(2)(D)(i)(II)
                                                                                             for the following
                                                                                             NAAQS: 2006 24-hour
                                                                                             PM2.5 NAAQS; the
                                                                                             2012 annual PM2.5
                                                                                             NAAQS; the 2008 and
                                                                                             2015 eight-hour O3
                                                                                             NAAQS; the 2010 one-
                                                                                             hour NO2 NAAQS; and
                                                                                             the 2010 one-hour
                                                                                             SO2 NAAQS.
Arkansas Regional Haze SO2 and PM  Statewide...........     8/8/2018  3/22/2021 [Insert     Approval of
 SIP Revision.                                                         Federal Register      visibility
                                                                       citation].            transport portion
                                                                                             of this regional
                                                                                             haze SIP revision,
                                                                                             as supplemented by
                                                                                             the Arkansas 2015
                                                                                             O3 NAAQS Interstate
                                                                                             Transport SIP
                                                                                             Revision.
----------------------------------------------------------------------------------------------------------------


0
3. In Sec.  52.173, add paragraphs (h) and (i) to read as follows:


Sec.  52.173  Visibility protection.

* * * * *
    (h) Arkansas Regional Haze Phase III SIP Revision. The Arkansas 
Regional Haze Phase III SIP Revision submitted on August 13, 2019, is 
approved as follows:
    (1) The clear weight of evidence determination that the BART 
alternative for Power Boilers No. 1 and 2 satisfies all of the 
applicable regional haze provisions set forth in 40 CFR 51.308(e)(2)(i) 
to (iv) for the Domtar Ashdown Mill with respect to SO2, 
NOX, and PM10.
    (2) The regional haze program-specific plantwide conditions 32 to 
43 from section VI of Permit #0287-AOP-R22 are approved for Power 
Boilers No. 1 and 2 for the Domtar Ashdown Mill, which contain 
SO2, NOX, and PM10 emission limits and 
conditions for implementing the BART alternative.
    (3) The approval of the withdrawal of the current PM10 
BART determination of 0.07 lb/MMBtu for Power Boiler No. 1 in the 2008 
Arkansas Regional Haze SIP and replacement with the PM10 
BART alternative limit in the Arkansas Regional Haze Phase III SIP 
Revision.
    (4) The reasonable progress components under 40 CFR 51.308(d)(1) 
pertaining to the Domtar Ashdown Mill are approved.
    (5) The long-term strategy component pertaining to the Domtar 
Ashdown Mill that includes the emission limits and schedules of 
compliance component under 40 CFR 51.308(d)(3)(v)(3) is approved.
    (6) Consultation and coordination in the development of the SIP 
revision with the FLMs and with other states with Class I areas 
affected by emissions from Arkansas sources, as required under 40 CFR 
51.308(i)(2) and 40 CFR 51.308(d)(3)(i), is approved.
    (i) Portions of the Arkansas 2015 O3 NAAQS Interstate 
Transport SIP Revision and Arkansas Regional Haze SO2 and PM 
SIP Revision addressing Visibility Transport. The portion of the 
Arkansas 2015 O3 NAAQS Interstate Transport SIP revision 
addressing the visibility transport requirements of CAA section 
110(a)(2)(D)(i)(II) for Arkansas for the 2006 24-hour PM2.5 
NAAQS; the 2012 annual PM2.5 NAAQS; the 2008 and 2015 eight-
hour O3 NAAQS; the 2010 one-hour NO2 NAAQS; and 
the 2010 one-hour SO2 NAAQS are approved. The visibility 
transport portion of the Arkansas Regional Haze SO2 and PM 
SIP revision, as supplemented by the Arkansas 2015 O3 NAAQS 
Interstate Transport SIP revision, is also approved.

[FR Doc. 2021-05362 Filed 3-19-21; 8:45 am]
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