Document ID: EPA-R06-OAR-2015-0189-0265
Agency: epa
Document Type: Proposed Rule
Title: AR020.0265 Approval and Promulgation of Implementation Plans; Arkansas; Approval of Regional Haze State Implementation Plan Revision and Partial Withdrawal of Federal Implementation Plan, Proposed rule, 37 pages.
Posted Date: 2018-11-30T05:00Z

[Federal Register Volume 83, Number 231 (Friday, November 30, 2018)]
[Proposed Rules]
[Pages 62204-62240]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2018-26073]

[[Page 62203]]

Vol. 83

Friday,

No. 231

November 30, 2018

Part V

 Environmental Protection Agency

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40 CFR Part 52

 Approval and Promulgation of Implementation Plans; Arkansas; Approval 
of Regional Haze State Implementation Plan Revision and Partial 
Withdrawal of Federal Implementation Plan; Proposed Rule

  Federal Register / Vol. 83 , No. 231 / Friday, November 30, 2018 / 
Proposed Rules  

[[Page 62204]]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R06-OAR-2015-0189; FRL-9986-67-Region 6]

Approval and Promulgation of Implementation Plans; Arkansas; 
Approval of Regional Haze State Implementation Plan Revision and 
Partial Withdrawal of Federal Implementation Plan

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: Pursuant to the Federal Clean Air Act (CAA or the Act), the 
Environmental Protection Agency (EPA) is proposing to approve a portion 
of the revision to the Arkansas State Implementation Plan (SIP) that 
addresses certain requirements of the CAA and the EPA's regional haze 
rules for the protection of visibility in mandatory Class I Federal 
areas (Class I areas) for the first implementation period. The EPA is 
proposing to approve the portions of the SIP revision addressing the 
best available retrofit technology (BART) requirements for sulfur 
dioxide (SO2), particulate matter (PM) and nitrogen oxide 
(NOX) for seven electric generating units (EGUs) in 
Arkansas. The EPA is also proposing to approve the determination that 
no additional controls at any Arkansas sources are necessary under 
reasonable progress; calculation of the revised reasonable progress 
goals (RPGs) for Arkansas' Class I areas; certain components of the 
long-term strategy for making reasonable progress; the clarification 
that both the 6A and 9A Boilers at the Georgia-Pacific Crossett Mill 
are BART-eligible; and the additional information and technical 
analysis in support of the determination that the Georgia-Pacific 
Crossett Mill 6A and 9A Boilers are not subject to BART. In conjunction 
with our proposed approval of portions of the SIP revision, we are 
proposing to withdraw the corresponding federal implementation plan 
(FIP) provisions established in a prior action to address regional haze 
requirements for Arkansas.

DATES: Written comments must be received on or before December 31, 
2018.

ADDRESSES: Submit your comments, identified by Docket No. EPA-R06-OAR-
2015-0189, at http://www.regulations.gov or via email to 
[email protected]. Follow the online instructions for submitting 
comments. Once submitted, comments cannot be edited or removed from 
Regulations.gov. The EPA may publish any comment received to its public 
docket. Do not submit electronically any information you consider to be 
Confidential Business Information (CBI) or other information whose 
disclosure is restricted by statute. Multimedia submissions (audio, 
video, etc.) must be accompanied by a written comment. The written 
comment is considered the official comment and should include 
discussion of all points you wish to make. The EPA will generally not 
consider comments or comment contents located outside of the primary 
submission (i.e. on the web, cloud, or other file sharing system). For 
additional submission methods, please contact Dayana Medina, 
[email protected]. For the full EPA public comment policy, 
information about CBI or multimedia submissions, and general guidance 
on making effective comments, please visit http://www2.epa.gov/dockets/commenting-epa-dockets.
    Docket: The index to the docket for this action is available 
electronically at www.regulations.gov and in hard copy at the EPA 
Region 6, 1445 Ross Avenue, Suite 700, Dallas, Texas. While all 
documents in the docket are listed in the index, some information may 
be publicly available only at the hard copy location (e.g., copyrighted 
material), and some may not be publicly available at either location 
(e.g., CBI).

FOR FURTHER INFORMATION CONTACT: Dayana Medina, 214-665-7241, 
[email protected]. To inspect the hard copy materials, please 
schedule an appointment with Dayana Medina or Mr. Bill Deese at 214-
665-7253.

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

Table of Contents

I. Background
    A. The Regional Haze Program
    B. Our Previous Actions on Arkansas Regional Haze
II. Our Evaluation of Arkansas' SO2 and PM Regional Haze 
SIP Revision
    A. Identification of BART-Eligible and Subject-to-BART Sources
    B. Arkansas' Five-Factor Analyses for SO2 and PM BART
    1. AECC Bailey Unit 1
    a. SO2 BART Analysis and Determination
    b. PM BART Analysis and Determination
    2. AECC McClellan Unit 1
    a. SO2 BART Analysis and Determination
    b. PM BART Analysis and Determination
    3. SWEPCO Flint Creek Plant Boiler No. 1
    a. SO2 BART Analysis and Determination
    4. Entergy Lake Catherine Unit 4
    5. Entergy White Bluff Units 1 and 2 and the White Bluff 
Auxiliary Boiler
    a. White Bluff Units 1 and 2 SO2 BART Analysis and 
Determinations
    b. White Bluff Auxiliary Boiler BART Determinations
    C. Reasonable Progress Analysis for SO2
    1. Arkansas' Discussion of Key Pollutants and Source Category 
Contributions
    a. Region-Wide PSAT Data for Caney Creek and Upper Buffalo
    b. Arkansas PSAT Data for Caney Creek and Upper Buffalo
    c. Arkansas' Conclusions Regarding Key Pollutants and Source 
Category Contributions
    2. Arkansas' Analysis of Reasonable Progress Factors Broadly 
Applicable to Arkansas Sources
    3. Identification of Potential Sources for Evaluation of 
SO2 Controls Under Reasonable Progress
    4. Arkansas' Reasonable Progress Analysis for Independence Units 
1 and 2
    a. Arkansas' Evaluation of the Reasonable Progress Factors for 
SO2 for Entergy Independence Units 1 and 2
    b. Arkansas' Determination Regarding Reasonable Progress 
Requirements for Independence
    5. Arkansas' Determination Regarding Additional Controls 
Necessary Under Reasonable Progress and Revised RPGs
    6. EPA's Evaluation and Conclusions on Arkansas' Reasonable 
Progress Analysis and Revised RPGs
    D. Long-Term Strategy
    E. Required Consultation
    F. Interstate Visibility Transport Under Section 
110(a)(2)(D)(i)(II)
    G. Clean Air Act Section 110(l)
III. Proposed Action
    A. Arkansas' Regional Haze SIP Revision
    B. Partial FIP Withdrawal
    C. Clean Air Act Section 110(l)
IV. Incorporation by Reference
V. Statutory and Executive Order Reviews

I. Background

A. The Regional Haze Program

    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) (e.g., 
sulfates, nitrates, organic carbon (OC), elemental carbon (EC), and 
soil dust), and their precursors (e.g., SO2, NOX, 
and in some cases, ammonia (NH3) and volatile organic 
compounds (VOCs)). Fine particle precursors react in the atmosphere to 
form PM2.5, which impairs visibility by scattering and 
absorbing light. This light scattering reduces the clarity, color and 
visible distance that one can see. Particulate matter can also cause 
serious health effects in humans (including premature death, heart 
attacks, irregular heartbeat, aggravated asthma, decreased lung 
function and increased respiratory symptoms) and contribute to

[[Page 62205]]

environmental effects such as acid deposition and eutrophication.
    Data from the existing visibility monitoring network, the 
``Interagency Monitoring of Protected Visual Environments'' (IMPROVE) 
monitoring network, show that at the time the Regional Haze Rule was 
finalized in 1999, visibility impairment caused by air pollution 
occurred virtually all the time at most national parks and wilderness 
areas. The average visual range \1\ in many Class I areas in the 
western U.S. was 62-93 miles, but in some Class I areas, these visual 
ranges may have been impacted by natural wildfire and dust episodes in 
addition to anthropogenic impacts. In most of the eastern Class I areas 
of the U.S., the average visual range was less than 19 miles.\2\ CAA 
programs have reduced emissions of some haze-causing pollution, 
lessening some visibility impairment and resulting in partially 
improved average visual ranges.\3\
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    \1\ Visual range is the greatest distance, in kilometers or 
miles, at which a dark object can be discerned against the sky by a 
typical observer. Visual range is inversely proportional to light 
extinction (bext) by particles and gases and is calculated as: 
Visual Range = 3.91/bext (Bennett, M.G., The physical conditions 
controlling visibility through the atmosphere; Quarterly Journal of 
the Royal Meteorological Society, 1930, 56, 1-29). Light extinction 
has units of inverse distance (i.e., Mm-1 or inverse 
Megameters [mega = 106]).
    \2\ 64 FR 35715 (July 1, 1999).
    \3\ An interactive ``story map'' depicting efforts and recent 
progress by EPA and states to improve visibility at national parks 
and wilderness areas may be visited at: http://arcg.is/29tAbS3.
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    In section 169A of the 1977 Amendments to the CAA, Congress created 
a program for protecting visibility in the nation's national parks and 
wilderness areas. This section of the CAA establishes as a national 
goal the prevention of any future, and the remedying of any existing, 
man-made impairment of visibility in 156 national parks and wilderness 
areas designated as mandatory Class I Federal areas.\4\ Congress added 
section 169B to the CAA in 1990 to address regional haze issues, and 
the EPA promulgated regulations addressing regional haze in 1999. The 
Regional Haze Rule \5\ revised the existing visibility regulations to 
add provisions addressing regional haze impairment and established a 
comprehensive visibility protection program for Class I areas. The 
requirements for regional haze, found at 40 CFR 51.308 and 51.309, are 
included in our visibility protection regulations at 40 CFR 51.300-309. 
The requirement to submit a regional haze SIP revision at periodic 
intervals applies to all 50 states, the District of Columbia, and the 
Virgin Islands. States were required to submit the first implementation 
plan addressing regional haze visibility impairment no later than 
December 17, 2007.\6\
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    \4\ Areas designated as 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. 42 U.S.C. 7472(a). 
In accordance with section 169A of the CAA, EPA, in consultation 
with the Department of Interior, promulgated a list of 156 areas 
where visibility is identified as an important value. 44 FR 69122 
(November 30, 1979). The extent of a mandatory Class I area includes 
subsequent changes in boundaries, such as park expansions. 42 U.S.C. 
7472(a). Although states and tribes may designate as Class I 
additional areas which they consider to have visibility as an 
important value, the requirements of the visibility program set 
forth in section 169A of the CAA apply only to ``mandatory Class I 
Federal areas.'' Each mandatory Class I Federal area is the 
responsibility of a ``Federal Land Manager.'' 42 U.S.C. 7602(i). 
When we use the term ``Class I area'' in this action, we mean a 
``mandatory Class I Federal area.''
    \5\ Here and elsewhere in this document, the term ``Regional 
Haze Rule,'' refers to the 1999 final rule (64 FR 35714), as amended 
in 2005 (70 FR 39156, July 6, 2005), 2006 (71 FR 60631, October 13, 
2006), 2012 (77 FR 33656, June 7, 2012), and 2017 (82 FR 3078, 
January 10, 2017).
    \6\ See 40 CFR 51.308(b). EPA's regional haze regulations 
require subsequent updates to the regional haze SIPs. 40 CFR 
51.308(f)-(i). The next update is due by July 31, 2021.
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    Section 169A of the CAA directs states to evaluate the use of 
retrofit controls at certain larger, often under-controlled, older 
stationary sources in order to address visibility impacts from these 
sources. Specifically, section 169A(b)(2)(A) of the CAA requires states 
to revise their SIPs to contain such measures as may be necessary to 
make reasonable progress toward the natural visibility goal, including 
a requirement that certain categories of existing major stationary 
sources \7\ built between 1962 and 1977 procure, install, and operate 
BART controls. Larger ``fossil-fuel fired steam electric plants'' are 
one of these source categories. Under the Regional Haze Rule, states 
are directed to conduct BART determinations for ``BART-eligible'' 
sources that may be anticipated to cause or contribute to any 
visibility impairment in a Class I area. Sources that are reasonably 
anticipated to cause or contribute to any visibility impairment in a 
Class I area are determined to be subject-to-BART. For each source 
subject to BART, 40 CFR 51.308(e)(1)(ii)(A) requires that states (or 
EPA, in the case of a FIP) identify the level of control representing 
BART after considering the factors set out in CAA section 169A(g). The 
evaluation of BART for EGUs that are located at fossil-fuel fired power 
plants having a generating capacity in excess of 750 megawatts (MW) 
must follow the ``Guidelines for BART Determinations Under the Regional 
Haze Rule'' at appendix Y to 40 CFR part 51 (hereinafter referred to as 
the ``BART Guidelines''). Rather than requiring source-specific BART 
controls, states also have the flexibility to adopt an emissions 
trading program or other alternative program as long as the alternative 
provides for greater reasonable progress towards improving visibility 
than BART.
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    \7\ See 42 U.S.C. 7491(g)(7) (listing the set of ``major 
stationary sources'' potentially subject-to-BART).
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    The vehicle for ensuring continuing progress towards achieving the 
natural visibility goal is the submission of a series of regional haze 
SIPs that contain long-term strategies to make reasonable progress 
towards natural visibility conditions. As part of this process, States 
also establish RPGs for every Class I area to provide assessments of 
the improvements in visibility anticipated to result from the long-term 
strategies. States have significant flexibility in establishing long-
term strategies and RPGs,\8\ but must determine whether additional 
control measures beyond BART and other ``on the books'' controls are 
needed for reasonable progress based on consideration of the following 
factors set out in section 169A of the CAA: (1) The costs of 
compliance; (2) the time necessary for compliance; (3) the energy and 
non-air quality environmental impacts of compliance; and (4) the 
remaining useful life of any potentially affected sources. States must 
demonstrate in their SIPs how these factors are considered when 
selecting measures for their long-term strategies and calculating the 
associated RPGs for each applicable Class I area. We commonly refer to 
this as the ``reasonable progress analysis'' or ``four factor 
analysis.''
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    \8\ 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 EPA 
Regional Administrators, EPA Regions 1-10 (pp. 4-2, 5-1).
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B. Our Previous Actions on Arkansas Regional Haze

    Arkansas submitted a SIP revision on September 9, 2008, to address 
the requirements of the first regional haze implementation period. On 
August 3, 2010, Arkansas submitted a SIP revision with mostly non-
substantive revisions to Arkansas Pollution Control and Ecology 
Commission (APCEC) Regulation 19, Chapter 15.\9\ On

[[Page 62206]]

September 27, 2011, the State submitted supplemental information to 
address the regional haze requirements. We are hereafter referring to 
these regional haze submittals collectively as the ``2008 Arkansas 
Regional Haze SIP.'' On March 12, 2012, we partially approved and 
partially disapproved the 2008 Arkansas Regional Haze SIP.\10\ On 
September 27, 2016, we promulgated a FIP (the Arkansas Regional Haze 
FIP) addressing the disapproved portions of the 2008 Arkansas Regional 
Haze SIP.\11\ Among other things, the FIP established SO2, 
NOX, and PM emission limits under the BART requirements for 
nine units at six facilities: AECC Bailey Plant Unit 1; AECC McClellan 
Plant Unit 1; SWEPCO Flint Creek Plant Boiler No. 1; Entergy Lake 
Catherine Plant Unit 4; Entergy White Bluff Plant Units 1 and 2; 
Entergy White Bluff 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 Entergy Independence Units 1 and 2.
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    \9\ 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.
    \10\ 77 FR 14604.
    \11\ 81 FR 66332; see also 81 FR 68319 (October 4, 2016) 
(correction).
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    Following the issuance of the Arkansas Regional Haze FIP, the State 
of Arkansas and several industry parties filed petitions for 
reconsideration and an administrative stay of the final rule.\12\ On 
April 14, 2017, we announced our decision to convene a proceeding to 
reconsider several elements of the FIP, as follows: Appropriate 
compliance dates for the NOX emission limits for Flint Creek 
Boiler No. 1, White Bluff Units 1 and 2, and Independence Units 1 and 
2; the low-load NOX emission limits applicable to White 
Bluff Units 1 and 2 and Independence Units 1 and 2 during periods of 
operation at less than 50 percent of the unit's maximum heat input 
rating; the SO2 emission limits for White Bluff Units 1 and 
2; and the compliance dates for the SO2 emission limits for 
Independence Units 1 and 2.\13\
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    \12\ See the docket associated with this proposed rulemaking for 
a copy of the petitions for reconsideration and administrative stay 
submitted by the State of Arkansas; Entergy Arkansas Inc., Entergy 
Mississippi Inc., and Entergy Power LLC (collectively ``Entergy''); 
AECC; and the Energy and Environmental Alliance of Arkansas (EEAA).
    \13\ 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=EPA-R06-OAR-2015-0189-0240.
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    EPA also published a notice in the Federal Register on April 25, 
2017, administratively staying the effectiveness of the NOX 
compliance dates in the FIP for the Flint Creek, White Bluff, and 
Independence units, as well as the compliance dates for the 
SO2 emission limits for the White Bluff and Independence 
units for a period of 90 days.\14\ On July 13, 2017, the EPA published 
a proposed rule to extend the NOX compliance dates for Flint 
Creek Boiler No. 1, White Bluff Units 1 and 2, and Independence Units 1 
and 2, by 21 months to January 27, 2020.\15\ However, EPA did not take 
final action on the July 13, 2017, proposed rule because on July 12, 
2017, Arkansas submitted a proposed SIP revision with a request for 
parallel processing, addressing 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, White Bluff Auxiliary 
Boiler, as well as the reasonable progress requirements with respect to 
NOX (Arkansas Regional Haze NOX SIP revision or 
Arkansas NOX SIP revision). In a proposed rule published in 
the Federal Register on September 11, 2017, we proposed to approve the 
Arkansas Regional Haze NOX SIP revision and to withdraw the 
corresponding parts of the Arkansas Regional Haze FIP.\16\ On October 
31, 2017, we received ADEQ's final Regional Haze NOX SIP 
revision addressing NOX BART for EGUs and the reasonable 
progress requirements with respect to NOX for the first 
implementation period. On February 12, 2018, we took final action to 
approve the Arkansas Regional Haze NOX SIP revision and to 
withdraw the corresponding parts of the FIP.\17\
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    \14\ 82 FR 18994.
    \15\ 82 FR 32284.
    \16\ 82 FR 42627.
    \17\ 83 FR 5927 and 83 FR 5915 (February 12, 2018).
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II. Our Evaluation of Arkansas' SO2 and PM Regional Haze SIP Revision

    On August 8, 2018, Arkansas submitted a SIP revision (Arkansas 
Regional Haze SO2 and PM SIP revision) addressing all 
remaining disapproved parts of the 2008 Regional Haze SIP, with the 
exception of the BART and associated long-term strategy requirements 
for the Domtar Ashdown Mill Power Boilers No. 1 and 2. The SIP revision 
also includes a discussion on Arkansas' interstate visibility transport 
requirements. We are proposing action on a portion of the August 8, 
2018, Arkansas Regional Haze SO2 and PM SIP revision in this 
Federal Register notice, and we are also proposing to withdraw the 
parts of the FIP corresponding to our proposed approvals. Since we are 
proposing to withdraw certain portions of the FIP, we are also 
proposing to redesignate the FIP by revising the numbering of certain 
paragraphs under section 40 CFR 52.173. Our proposed redesignation of 
the numbering of these paragraphs is non-substantive and does not mean 
we are reopening these parts for public comment in this proposed 
rulemaking. We intend to propose action on the portion of this SIP 
revision discussing the interstate visibility transport requirements 
for pollutants that affect visibility in Class I areas in nearby states 
in a future proposed rulemaking.
    The Arkansas Regional Haze SO2 and PM SIP revision 
submitted to us on August 8, 2018, addresses the majority of the 
remaining parts of the 2008 Regional Haze SIP that EPA disapproved on 
March 12, 2012.\18\ Specifically, the August 8, 2018, SIP revision 
revises ADEQ's identification of BART-eligible sources by now 
identifying the 6A Boiler at the Georgia-Pacific Crossett Mill as BART-
eligible; provides additional information and technical analysis in 
support of the determination that the Georgia-Pacific Crossett Mill 6A 
and 9A Boilers are not subject to BART; \19\ prohibits the burning of 
fuel oil at Lake Catherine Unit 4 until SO2 and PM BART 
determinations for the fuel oil firing scenario are approved into the 
SIP by EPA; and addresses the following BART requirements: 
SO2 and PM BART for Bailey Unit 1 and McClellan Unit 1; 
SO2 BART for Flint Creek Boiler No. 1; SO2 BART 
for White Bluff Units 1 and 2; and SO2, NOX, and 
PM BART for the White Bluff Auxiliary Boiler. The SIP revision also 
addresses the reasonable progress requirements, arriving at the 
conclusion that no additional controls at Independence Units 1 and 2 or 
any other Arkansas sources are necessary under reasonable progress,\20\ 
and establishes revised RPGs for Arkansas' two Class I areas, the Caney 
Creek Wilderness Area and the Upper Buffalo Wilderness Area. Finally, 
the SIP

[[Page 62207]]

revision revises the State's long-term strategy by including in the 
long-term strategy an SO2 emission limit of 0.60 lb/MMBtu 
for Independence Units 1 and 2 based on the use of low sulfur coal, as 
well as each of the BART measures listed above. The August 8, 2018, SIP 
revision does not address BART for the Domtar Ashdown Mill Power 
Boilers No. 1 and 2 and relies on the Domtar BART emission limits from 
our FIP and the 2012 partially approved SIP for the associated long-
term strategy requirements.
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    \18\ 77 FR 14604.
    \19\ BART eligible sources that are reasonably anticipated to 
cause or contribute to any visibility impairment in a Class I area 
are determined to be subject-to-BART. In the 2008 Arkansas Regional 
Haze SIP, ADEQ used a contribution threshold of 0.5 dv for 
determining whether a source ``contributes'' to visibility 
impairment and is thus subject to BART.
    \20\ In a SIP revision submitted on October 31, 2017, Arkansas 
provided a reasonable progress analysis and reasonable progress 
determination with respect to NOX, and we took final 
action to approve the analysis and determination in a final action 
published on February 12, 2018 (see 83 FR 5927). Thus, the August 8, 
2018 SIP revision addresses reasonable progress requirements with 
respect to SO2 and PM emissions.
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    The August 8, 2018, SIP revision is the subject of this proposed 
action, in conjunction with our proposed withdrawal of the parts of the 
Arkansas Regional Haze FIP corresponding to our proposed approval. We 
are proposing to approve ADEQ's revised identification of the 6A Boiler 
at the Georgia-Pacific Crossett Mill as BART-eligible; the additional 
information and technical analysis presented in the SIP revision in 
support of the determination that the Georgia-Pacific Crossett Mill 6A 
and 9A Boilers are not subject to BART; and the state's BART decisions 
for the seven subject-to-BART units listed above. We are proposing to 
withdraw our prior approval of Arkansas' reliance on participation in 
the Cross-State Air Pollution Rule (CSAPR) for ozone season 
NOX to satisfy the NOX BART requirement for the 
White Bluff Auxiliary Boiler. The Arkansas Regional Haze NOX 
SIP revision erroneously stated that the Auxiliary Boiler participates 
in CSAPR for ozone season NOX and that the state was 
electing to rely on participation in that trading program to satisfy 
the Auxiliary Boiler's NOX BART requirements, and we 
erroneously approved this determination in a final action published in 
the Federal Register on February 12, 2018.\21\ We are proposing to 
withdraw our approval of that determination for the Auxiliary Boiler 
and to replace it with our proposed approval of a source specific 
NOX BART emission limit contained in the Arkansas Regional 
Haze SIP Revision before us.
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    \21\ 83 FR 5927.
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    We are also proposing to approve Arkansas' reasonable progress 
determinations for Independence Units 1 and 2 and all other sources in 
Arkansas, and to approve the revised RPGs contained in the August 8, 
2018, SIP revision. We are further proposing to find that, based on the 
state's currently approved SIP and the analyses and determinations we 
are proposing to approve in this action, the state's reasonable 
progress obligations for the first implementation period have been 
satisfied. At this time, the majority of the BART requirements for the 
Domtar Ashdown Mill are satisfied by a FIP.\22\ The SIP revision 
explains that, based upon the BART determinations and analysis in that 
FIP, nothing further is currently needed for reasonable progress at the 
Domtar Ashdown Mill. EPA agrees. If the State chooses to submit a 
further SIP revision to address BART requirements for Domtar Power 
Boilers No. 1 and No. 2 that are currently satisfied by the FIP, we 
will evaluate that SIP submittal, including as well as any conclusions 
ADEQ draws about the adequacy of such SIP-based measures for reasonable 
progress. We will also, at that time, evaluate any changes in the 
measures for the Domtar Ashdown Mill relative to those currently in the 
FIP to determine whether the calculation of the reasonable progress 
goals for the first implementation period continue to be sufficient.
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    \22\ We note that the PM determination for Domtar Ashdown Mill 
Power Boiler No. 1 in the 2008 SIP was approved in our 2012 
rulemaking. (77 FR 14604, March 12, 2012).
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    Finally, we are proposing to approve the components of the long-
term strategy addressed by the August 8, 2018, SIP revision and to find 
that Arkansas' long-term strategy for reasonable progress with respect 
to all sources other than Domtar is approved. The long-term strategy is 
the compilation of all control measures a state will use during the 
implementation period of the specific SIP submittal to make reasonable 
progress towards the goal of natural visibility conditions, including 
emission limitations corresponding to BART determinations. If the 
proposed approvals of the BART measures and the emission limitations 
for the Independence facility addressed in this action are finalized, 
those measures will also be integrated into the State's long-term 
strategy. Because the August 8, 2018, SIP revision does not address the 
BART requirements for Domtar, that component of the long-term strategy 
will remain satisfied by the FIP unless and until EPA has received and 
approved a SIP revision containing the required analyses and 
determinations for this facility.
    We are also proposing to withdraw the majority of the Arkansas 
Regional Haze FIP we promulgated on September 27, 2016. Upon 
finalization of this proposed rulemaking, the majority of remaining FIP 
provisions would be replaced by the corresponding revisions to the SIP 
that we are proposing to approve in this proposed rulemaking. 
Specifically, we are proposing to withdraw the following components of 
the FIP: The SO2 and PM BART emission limits for Bailey Unit 
1; the SO2 and PM BART emission limits for McClellan Unit 1; 
the SO2 BART emission limit for Flint Creek Boiler No. 1; 
the SO2 BART emission limit for White Bluff Units 1 and 2; 
the SO2 and PM BART emission limits for the White Bluff 
Auxiliary Boiler; the prohibition on burning fuel oil at Lake Catherine 
Unit 4; and the SO2 emission limits for Independence Units 1 
and 2 under the reasonable progress provisions. Since we are proposing 
to withdraw certain portions of the FIP, we are also proposing to 
redesignate the FIP by revising the numbering of certain paragraphs 
under section 40 CFR 52.173. Our proposed redesignation of the 
numbering of these paragraphs is non-substantive and does not mean we 
are reopening these parts for public comment in this proposed 
rulemaking.
    The SIP revision also includes a discussion on interstate 
visibility transport. Specifically, the SIP revision discusses the 
impacts of Arkansas sources on Missouri's Class I areas, as well as the 
most recent IMPROVE monitoring data for Missouri's Class I areas. The 
SIP revision concludes that Missouri is on track to achieve its 
visibility goals, that the visibility progress observed indicates that 
sources in Arkansas are not interfering with the achievement of 
Missouri's RPGs for the Hercules-Glades Wilderness Area and Mingo 
Wilderness Area, and that no additional controls on sources within 
Arkansas are necessary to ensure that other states' visibility goals 
for their Class I areas are met. We are deferring proposing action on 
the interstate visibility transport portion of the SIP revision until a 
future proposed rulemaking.

A. Identification of BART-Eligible and Subject-to-BART Sources

    States are required to identify all the BART-eligible sources 
within their boundaries by utilizing the three eligibility criteria in 
the BART Guidelines \23\ and the Regional Haze Rule \24\: (1) One or 
more emission units at the facility fit within one of the 26 categories 
listed in the BART Guidelines; (2) the emission unit(s) began operation 
on or after August 6, 1962, and the unit was in existence on August 6, 
1977; and (3) the potential emissions of any visibility impairing 
pollutant from subject units are 250 tons or more per year. Sources 
that meet

[[Page 62208]]

these three criteria are considered BART-eligible. Once a list of the 
BART-eligible sources within a state has been compiled, states must 
determine whether to make BART determinations for all of them or 
whether some may not reasonably be anticipated to cause or contribute 
to any visibility impairment in a Class I area and may thus not be 
subject to further BART analysis or requirements. The BART Guidelines 
present several options that rely on modeling and/or emissions analyses 
to determine if a source may reasonably be anticipated to cause or 
contribute to visibility impairment in a Class I area. A source that 
may not be reasonably anticipated to cause or contribute to any 
visibility impairment in any Class I area is not ``subject to BART,'' 
and for such sources, a state need not make a BART determination.
---------------------------------------------------------------------------

    \23\ 70 FR 39158.
    \24\ 40 CFR 51.301.
---------------------------------------------------------------------------

    In our March 12, 2012, final action on the 2008 Arkansas Regional 
Haze SIP, we approved Arkansas' identification of BART-eligible sources 
with the exception of the Georgia-Pacific Crossett Mill 6A Boiler.\25\ 
We also approved Arkansas' determination of which sources are subject 
to BART, with the exception of its determination that the Georgia-
Pacific Crossett Mill 6A and 9A Boilers are not subject to BART. In 
that final action, we determined that the 2008 Arkansas Regional Haze 
SIP did not include sufficient documentation to demonstrate that the 6A 
Boiler is not BART-eligible and did not contain sufficient 
documentation to demonstrate that the 6A and 9A Boilers are not subject 
to BART. In the Arkansas Regional Haze FIP, we made the determination 
that the 6A Boiler is BART-eligible. We also noted that we continued to 
agree with the state's previous determination from the 2008 Arkansas 
Regional Haze SIP that the 9A Boiler is BART-eligible. Based on 
additional information and a technical analysis provided to the EPA by 
Georgia-Pacific, EPA determined that the 6A and 9A Boilers are not 
subject to BART. In the August 8, 2018, Arkansas Regional Haze 
SO2 and PM SIP revision, Arkansas has made determinations 
consistent with our findings in the FIP. Specifically, Arkansas made a 
revision to its identification of BART-eligible sources,\26\ now 
identifying the 6A Boiler at the Georgia-Pacific Crossett Mill as BART-
eligible. In the 2008 Arkansas Regional Haze SIP, the state had already 
identified the 9A Boiler at the Georgia-Pacific Crossett Mill as BART-
eligible; in the August 8, 2018, SIP revision, the state made no 
changes to the identification of the 9A Boiler as BART-eligible. In 
addition, Arkansas included in the SIP revision a copy of the technical 
analysis and other information that was provided by Georgia-Pacific to 
EPA, which we previously included in the record for the Arkansas 
Regional Haze FIP in support of our determination that the 6A and 9A 
Boilers are not subject to BART.\27\ As Arkansas explains in the SIP 
revision, Georgia-Pacific provided information regarding revisions to 
emission limits included in the facility's permit and additional 
dispersion modeling conducted in 2011 using those revised limits. The 
results of this 2011 BART screening modeling demonstrated that the 
maximum impact of the Georgia-Pacific Crossett Mill boilers on any 
Class I area was less than the 0.5 dv threshold used by ADEQ to 
determine whether a BART-eligible source should be considered subject 
to BART. Because the 2011 BART screening modeling was based on permit 
limits from a permit revision issued in 2012 rather than on maximum 24-
hour emission rates from the 2001-2003 baseline period, Georgia-Pacific 
also provided further information regarding fuel usage during the 2001-
2003 baseline and performed calculations using AP-42, Compilation of 
Air Pollutant Emission Factors, to estimate the 24-hour emission rates 
for SO2, NOX, and PM10 for the 6A and 
9A Boilers for each day during the baseline years. Georgia Pacific then 
identified the maximum 24-hour emission rates for each pollutant for 
the two boilers during the 2001-2003 baseline period. A comparison of 
the estimated maximum 24-hour emission rates with the emission rates 
modeled in Georgia-Pacific's 2011 BART screening modeling demonstrates 
that the maximum 24-hour emission rates from the 2001-2003 baseline 
were lower than the rates modeled in the 2011 BART screening modeling 
and lower than the boilers' permit limits. Based upon the additional 
information provided by Georgia-Pacific, ADEQ concluded that the 6A and 
9A Boilers are not subject to BART.\28\ Thus, ADEQ revised its 
identification of BART-eligible sources by identifying the Georgia-
Pacific Mill 6A Boiler as BART-eligible. Since ADEQ previously 
determined in the 2008 Regional Haze SIP that the 9A Boiler is BART-
eligible, it made no change to that previous determination. ADEQ did 
not make changes to its list of subject-to-BART sources, but did 
include in the SIP revision the additional information and technical 
analysis from Georgia-Pacific to support and document the determination 
that the 6A and 9A boilers are not subject to BART.
---------------------------------------------------------------------------

    \25\ 80 FR 18947.
    \26\ See Arkansas Regional Haze SO2 and PM SIP 
revision, Table 1, page 8 and 9.
    \27\ See the documentation provided by Georgia Pacific to EPA 
that was previously included in the record for the Arkansas Regional 
Haze FIP. This documentation is included in the docket at the 
following location: https://www.regulations.gov/searchResults?rpp=50&so=ASC&sb=docId&po=0&dktid=EPA-R06-OAR-2015-0189.
    \28\ ADEQ provides documentation in support of the determination 
that the Georgia-Pacific Crossett Mill 6A and 9A Boilers are not 
subject to BART in Appendix A to the Arkansas Regional Haze 
SO2 and PM SIP revision.
---------------------------------------------------------------------------

    We are proposing to find that the analysis and documentation 
provided by Georgia-Pacific and included in the Arkansas Regional Haze 
SO2 and PM SIP revision appropriately and sufficiently 
demonstrate that the 6A and 9A Boilers are not subject to BART. We are 
proposing to approve ADEQ's revised determination that the 6A Boiler is 
BART-eligible and concur that the 6A and 9A Boilers are not subject to 
BART.

B. Arkansas' Five-Factor Analyses for SO2 and PM BART

    In determining BART, the state must consider the five statutory 
factors in section 169A of the CAA: (1) The costs of compliance; (2) 
the energy and nonair quality environmental impacts of compliance; (3) 
any existing pollution control technology in use at the source; (4) the 
remaining useful life of the source; and (5) the degree of improvement 
in visibility which may reasonably be anticipated to result from the 
use of such technology.\29\ All units that are subject to BART must 
undergo a BART analysis. The BART Guidelines break the analysis down 
into five steps:\30\
---------------------------------------------------------------------------

    \29\ See also 40 CFR 51.308(e)(1)(ii)(A).
    \30\ 70 FR 39103, 39164 (July 6, 2005) [40 CFR 51, App. Y].
---------------------------------------------------------------------------

    STEP 1--Identify All Available Retrofit Control Technologies,
    STEP 2--Eliminate Technically Infeasible Options,
    STEP 3--Evaluate Control Effectiveness of Remaining Control 
Technologies,
    STEP 4--Evaluate Impacts and Document the Results, and
    STEP 5--Evaluate Visibility Impacts.
    As mentioned previously, EPA partially approved and partially 
disapproved the 2008 Arkansas Regional Haze SIP revision in a final 
action published on March 12, 2012.\31\ Following our 2012 partial 
disapproval of the 2008 Arkansas Regional Haze SIP, ADEQ began the 
process of generating additional technical information and analyses 
from the companies whose BART determinations we disapproved. These 
analyses and technical

[[Page 62209]]

information were provided to EPA and were the basis for our evaluation 
of BART for subject-to-BART facilities in the FIP. In turn, ADEQ relied 
on those same analyses and technical information in the state's 
evaluation of BART for subject-to-BART sources in the Arkansas Regional 
Haze SO2 and PM SIP revision, with the exception of White 
Bluff Units 1 and 2, for which updated technical information has been 
provided by Entergy and is included in the SIP revision. In evaluating 
the Arkansas Regional Haze SO2 and PM SIP revision, we 
reviewed each BART analysis for SO2 and PM for each subject-
to-BART source and other relevant information provided in the SIP 
revision.
---------------------------------------------------------------------------

    \31\ 77 FR 14604.
---------------------------------------------------------------------------

    As noted above, we approved certain parts of the 2008 Arkansas 
Regional Haze SIP in 2012.\32\ The parts that we approved in 2012 
included PM BART for Flint Creek Boiler No. 1; PM BART for White Bluff 
Units 1 and 2; SO2 and PM BART for the natural gas firing 
scenario for Lake Catherine Unit 4; and PM BART for Domtar Power Boiler 
No. 1. We also published a final action on February 12, 2018, in which 
we approved a SIP revision submitted by ADEQ on October 31, 2017, to 
address the regional haze requirements for NOX for EGUs in 
Arkansas (``Arkansas Regional Haze NOX SIP Revision'').\33\ 
That final action included approval of Arkansas' NOX BART 
determinations for Bailey Unit 1; McClellan Unit 1; Flint Creek Boiler 
No. 1; Lake Catherine Unit 4 (for both the natural gas firing and fuel 
oil firing scenarios); White Bluff Units 1 and 2; and the White Bluff 
Auxiliary Boiler; and removed the corresponding portions of the 
Arkansas Regional Haze FIP. Thus, the only BART requirements currently 
addressed under the Arkansas Regional Haze FIP are the SO2 
and PM BART requirements for Bailey Unit 1; the SO2 and PM 
BART requirements for McClellan Unit 1; the SO2 BART 
requirements for Flint Creek Boiler No. 1; the prohibition on burning 
fuel oil at Lake Catherine Unit 4 until SO2 and PM BART 
determinations for the fuel oil firing scenario are approved into the 
SIP by EPA; the SO2 BART requirements for White Bluff Units 
1 and 2; the SO2 and PM BART requirements for the White 
Bluff Auxiliary Boiler; the SO2 and NOX BART 
requirements for the Domtar Ashdown Mill Power Boiler No. 1; and the 
SO2, NOX, and PM BART requirements for the Domtar 
Ashdown Mill Power Boiler No. 2. The Arkansas Regional Haze 
SO2 and PM SIP revision addresses all these BART 
requirements currently covered under the FIP, with the exception of the 
requirements for the Domtar Ashdown Mill Power Boilers No. 1 and 2. As 
noted above, in the Arkansas Regional Haze NOX SIP revision, 
ADEQ erroneously stated that the Auxiliary Boiler participated in CSAPR 
for ozone season NOX and the state decided to rely on 
participation in that trading program to satisfy the Auxiliary Boiler's 
NOX BART requirement. In a final action published in the 
Federal Register on February 12, 2018, we took final action to approve 
this SIP revision, including reliance on CSAPR for ozone season 
NOX to satisfy the Auxiliary Boiler's NOX BART 
requirement.\34\ Since the White Bluff Auxiliary Boiler does not 
participate in CSAPR for ozone season NOX, we are proposing 
to withdraw our prior approval of the NOX BART determination 
for the Auxiliary Boiler and to replace it with our proposed approval 
of a source specific NOX BART emission limit contained in 
the August 8, 2018, Arkansas Regional Haze SIP revision. We discuss 
this in greater detail in section II.B.5.b. of this proposed action.
---------------------------------------------------------------------------

    \32\ 77 FR 14604.
    \33\ 83 FR 5927.
    \34\ 83 FR 5927.
---------------------------------------------------------------------------

1. AECC Bailey Unit 1
    The AECC Bailey Unit 1 has a wall-fired boiler, a gross output of 
122 MW, and a maximum heat input rate of 1,350 million British thermal 
units per hour (MMBtu/hr). The unit is currently permitted to burn 
pipeline quality natural gas and fuel oil. The fuel oil burned is 
currently subject to a sulfur content limit of 2.3% by weight. AECC 
produced BART analyses dated March 2014 for Bailey Unit 1, which were 
evaluated by EPA and largely formed the basis for EPA's SO2 
and PM BART evaluations in the FIP.\35\ The same BART analyses \36\ 
have now been adopted and incorporated by ADEQ into the Arkansas 
Regional Haze SO2 and PM BART SIP revision to address the 
SO2 and PM BART requirements for Bailey Unit 1.
---------------------------------------------------------------------------

    \35\ 80 FR 18950.
    \36\ ``BART Five Factor Analysis, Arkansas Electric Cooperative 
Corporation Bailey and McClellan Generating Stations,'' dated March 
2014, Version 4, prepared by Trinity Consultants Inc. in conjunction 
with Arkansas Electric Cooperative Corporation,'' which can be found 
in Appendix B to the Arkansas Regional Haze SO2 and PM 
BART SIP Revision.
---------------------------------------------------------------------------

a. SO2 BART Analysis and Determination
    In assessing SO2 BART, ADEQ explained that AECC 
considered the five BART factors. In assessing feasible control 
technologies and their effectiveness, AECC considered flue gas 
desulfurization (FGD) systems and fuel switching during fuel oil 
burning. Due to the intrinsically low sulfur content of natural gas, no 
control technologies were evaluated for natural gas burning scenarios. 
As such, the BART analysis focused on fuel oil firing as the base case. 
For fuel oil firing, fuel switching was determined to be the only 
technically feasible control option, and thus AECC did not further 
consider FGD for SO2 BART. The baseline fuel AECC assumed in 
the BART analysis is No. 6 fuel oil with 1.81% sulfur content by 
weight, which is based on the average sulfur content of the fuel oil 
from the most recent shipment received by the facility in December 
2006. ADEQ explained that AECC evaluated switching to the following 
fuel types: 1% sulfur No. 6 fuel oil, corresponding to an estimated 45% 
control efficiency; 0.5% sulfur No. 6 fuel oil, corresponding to 72% 
control efficiency; and 0.05% sulfur diesel, corresponding to 97% 
control efficiency.\37\
---------------------------------------------------------------------------

    \37\ We also note that AECC evaluated switching to natural gas 
as an available SO2 control option in its SO2 
BART analysis, but the evaluation of this control option was not 
discussed by ADEQ in the SIP revision. We discuss this issue in 
greater detail below when we present our evaluation of the state's 
BART determination.
---------------------------------------------------------------------------

    In considering the costs of compliance for fuel switching, AECC 
concluded that the fuel switching options evaluated would not require 
capital investments in equipment, but instead the annual costs would be 
based upon operation and maintenance costs associated with the 
different fuel types. AECC estimated that the cost-effectiveness of 
switching Bailey Unit 1 to No. 6 fuel oil with 1% and 0.5% sulfur 
content by weight is $1,198/ton and $2,559/ton, respectively. Switching 
to diesel, which has 0.05% sulfur content, is estimated to cost $5,382/
ton. ADEQ stated that the cost in dollars per ton for diesel is out of 
the range of what is typically considered cost-effective, while the 
cost of both 1% and 0.5% sulfur No. 6 fuel oil is estimated to be 
within the range of what is typically considered cost-effective.
    ADEQ stated that AECC's evaluation did not identify any energy or 
non-air quality environmental impacts associated with switching to 1% 
sulfur No. 6 fuel oil, 0.5% sulfur No. 6 fuel oil, or diesel. In 
assessing the remaining useful life of Bailey Unit 1, AECC concluded 
that this factor does not impact the annualized costs of the evaluated 
control options since fuel switching is not expected to require any 
significant capital costs in this case.

[[Page 62210]]

    In assessing visibility impacts, the state's submittal included 
CALPUFF modeling evaluating the visibility benefits of switching from 
the baseline fuel oil (assuming 100% use of fuel oil) to the various 
fuel switching options. We summarize the results of that modeling in 
Table 1.

               Table 1--Anticipated Visibility Benefit Due to Fuel Switching at AECC Bailey Unit 1
                                           [CALPUFF, 98th percentile]
----------------------------------------------------------------------------------------------------------------
                                                              Visibility benefit of controls over baseline (dv)
                                              Baseline     -----------------------------------------------------
              Class I area                   visibility     No. 6 fuel oil--  No. 6 fuel oil--   Diesel-- 0.05%
                                             impact (dv)        1% sulfur        0.5% sulfur         sulfur
----------------------------------------------------------------------------------------------------------------
Caney Creek.............................             0.330             0.137             0.188             0.246
Upper Buffalo...........................             0.348             0.154             0.221             0.279
Hercules-Glades.........................             0.368             0.162             0.233             0.299
Mingo...................................             0.379             0.173             0.209             0.284
----------------------------------------------------------------------------------------------------------------

    Switching to 1% sulfur No. 6 fuel oil is anticipated to achieve 
visibility benefits of approximately 0.137 dv at Caney Creek, 0.154 dv 
at Upper Buffalo, 0.162 dv at Hercules-Glades, and 0.173 dv at Mingo 
over baseline visibility conditions. Switching to 0.5% sulfur No. 6 
fuel oil is anticipated to achieve visibility benefits of approximately 
0.188 dv at Caney Creek, 0.221 dv at Upper Buffalo, 0.233 dv at 
Hercules-Glades, and 0.209 dv at Mingo over the baseline. The 
visibility benefits of switching to diesel are anticipated to be even 
greater, with benefits of approximately 0.246 dv at Caney Creek, 0.279 
dv at Upper Buffalo, 0.299 dv at Hercules-Glades, and 0.284 dv at Mingo 
over the baseline.
    Taking into consideration the cost-effectiveness and the 
anticipated visibility improvement of the fuel switching options, ADEQ 
concurred with AECC's recommendation that SO2 BART for AECC 
Bailey Unit 1 be determined to be the use of fuel with a sulfur content 
by weight of 0.5% or less.
    We note that switching to diesel would result in additional 
reductions in SO2 emissions, but the additional costs per 
ton for doing so would be high in comparison to the additional 
visibility benefits. We also note that AECC evaluated switching to 
natural gas as an available SO2 control option in its 
SO2 BART analysis,\38\ but the evaluation of this control 
option in the SO2 BART analysis was not discussed by ADEQ in 
the SIP revision. In its analysis, AECC explained that switching to 
natural gas may have an adverse energy impact during periods of natural 
gas curtailment and that the ability to burn both fuel oil and natural 
gas was important for the facility to maintain electrical 
reliability.\39\ Therefore, AECC did not recommend switching to natural 
gas and instead recommended switching to fuels with 0.5% sulfur content 
to be SO2 BART for Bailey Unit 1.\40\ In the Arkansas 
Regional Haze FIP, we agreed with AECC's recommendation, and explained 
that the BART Guidelines provide that it is not our intent to direct 
subject-to-BART sources to switch fuel forms, such as from coal or fuel 
oil to natural gas (40 CFR part 51, Appendix Y, section IV.D.1).\41\ We 
noted that since natural gas has a sulfur content by weight that is 
well below 0.5%, the facility may elect to use this type of fuel to 
comply with BART, but we did not require a switch to natural gas for 
SO2 BART in the FIP.\42\ Therefore, we do not find that 
ADEQ's lack of consideration of switching to natural gas as an 
SO2 control option in the SO2 BART analysis for 
Bailey Unit 1 changes the result of the BART analysis in this instance. 
We are proposing to approve the state's determination that 
SO2 BART for AECC Bailey Unit 1 is the use of fuel with a 
sulfur content by weight of 0.5% or less. We are also proposing to 
approve the state's determination that Bailey Unit 1 must comply with 
this BART requirement no later than October 27, 2021, and that as of 
the effective date of the Administrative Order, which is August 7, 
2018, the source shall not purchase fuel that does not meet the sulfur 
limit requirement for combustion at Bailey Unit 1. These BART 
requirements have now been made enforceable by the state through an 
Administrative Order that has been adopted and incorporated in the SIP 
revision. The Administrative Order for AECC Bailey Unit 1 includes not 
only the requirement to limit the sulfur content of the fuel burned, 
but also requirements for the source to sample and analyze each 
shipment of fuel to determine the sulfur content by weight and maintain 
records pertaining to the sampling of each fuel shipment to assess 
compliance with the BART requirements.\43\ We are proposing to approve 
the state's Administrative Order, including the compliance 
determination requirements contained in the Administrative Order, into 
the SIP. The state's SO2 BART emission limit and compliance 
date for Bailey Unit 1 are consistent with the BART decision EPA 
previously made in the FIP we promulgated on September 27, 2016.\44\ We 
are concurrently proposing to withdraw the FIP's SO2 BART 
requirements for Bailey Unit 1, as they would be replaced by our 
approval of the state's SO2 BART decision.
---------------------------------------------------------------------------

    \38\ See ``BART Five Factor Analysis, Arkansas Electric 
Cooperative Corporation Bailey and McClellan Generating Stations, 
dated March 2014, Version 4, prepared by Trinity Consultants Inc. in 
conjunction with Arkansas Electric Cooperative Corporation,'' pages 
5-1 to 5-14. This BART analysis has been adopted and incorporated by 
ADEQ into the SIP revision (see Appendix B to the Arkansas Regional 
Haze SO2 and PM BART SIP revision).
    \39\ See ``BART Five Factor Analysis, Arkansas Electric 
Cooperative Corporation Bailey and McClellan Generating Stations, 
dated March 2014, Version 4, prepared by Trinity Consultants Inc. in 
conjunction with Arkansas Electric Cooperative Corporation,'' pages 
5-2, 5-10, and 5-14.
    \40\ Id.
    \41\ 80 FR 18952 and 81 FR at 66339.
    \42\ Id.
    \43\ The Administrative Order can be found in the Arkansas 
Regional Haze SO2 and PM BART SIP Revision.
    \44\ The Arkansas Regional Haze FIP requires Bailey Unit 1 to 
only use fuel with a sulfur content limit of 0.5% by weight, with a 
compliance date of October 27, 2021. Additionally, the FIP prohibits 
the owner or operator of the unit from purchasing fuel for 
combustion at the unit that does not meet the sulfur content limit; 
the compliance date for this requirement is October 27, 2016. See 81 
FR 66335, 66415-16.
---------------------------------------------------------------------------

b. PM BART Analysis and Determination
    PM emissions are inherently low when burning natural gas, but are 
higher when burning fuel oil. Bailey Unit 1 does not currently have 
pollution control equipment for PM emissions. In assessing PM BART for 
Bailey Unit 1, ADEQ explained that AECC considered the five BART 
factors. In assessing feasible control technologies and their

[[Page 62211]]

effectiveness, AECC considered the following control technologies for 
PM BART: Dry electrostatic precipitator (ESP), wet ESP, fabric filter, 
wet scrubber, cyclone (i.e., mechanical collector), and fuel switching. 
AECC's evaluation noted that the particulate matter from oil-fired 
boilers tends to be sticky and small, affecting the collection 
efficiency of dry ESPs and fabric filters. Dry ESPs operate by placing 
a charge on the particles through a series of electrodes, and then 
capturing the charged particles on collection plates, while fabric 
filters work by filtering the PM in the flue gas through filter bags. 
The collected particles are periodically removed from the filter bag 
through a pulse jet or reverse flow mechanism. Because of the sticky 
nature of particles from oil-fired boilers, AECC considered dry ESPs 
and fabric filters to be technically infeasible for use at Bailey Unit 
1. AECC found wet ESPs, wet scrubbers, cyclones, and fuel switching to 
be technically feasible PM control options.
    Residual fuel, such as the baseline No. 6 fuel oil burned at Bailey 
Unit 1, has inherent ash that contributes to emissions of filterable 
PM. Reductions in filterable PM emissions are directly related to the 
sulfur content of the fuel.\45\ Therefore, switching to No. 6 fuel oil 
with a lower sulfur content is expected to result in lower filterable 
PM emissions. Also, ash content is much lower in a distillate fuel such 
as diesel and essentially zero in natural gas. The fuel switching 
options considered by AECC in the PM BART analysis are No. 6 fuel oil 
with 1% sulfur content by weight, No. 6 fuel oil with 0.5% sulfur 
content by weight, natural gas, and diesel. AECC estimated that 
switching to a lower sulfur fuel has a PM control efficiency ranging 
from approximately 44%-99%, depending on the fuel type. The estimated 
PM control efficiency of each control option is summarized in Table 2.
---------------------------------------------------------------------------

    \45\ See ``AP-42, Compilation of Air Pollutant Emission 
Factors,'' section 1.3.3.1, and Table 1.3-1, available at http://www.epa.gov/ttnchie1/ap42/.

                  Table 2--PM Control Efficiency of BART Control Options for AECC Bailey Unit 1
----------------------------------------------------------------------------------------------------------------
                                                                                    Fuel switching
                                                                     -------------------------------------------
                                        Wet                                        No. 6
         PM control option            scrubber   Cyclone    Wet ESP     No. 6    fuel oil--  Natural
                                                                      fuel oil--   0.5% S      gas       Diesel
                                                                         1% S
----------------------------------------------------------------------------------------------------------------
PM Control Efficiency..............       55.0       85.0       90.0       65.7       89.3       99.0       99.5
(%)................................
----------------------------------------------------------------------------------------------------------------

    In considering the costs of the PM control options, AECC noted that 
add-on controls such as a wet scrubber, cyclone, and wet ESP involve 
capital costs for new equipment, which AECC annualized over a 15-year 
period in the analysis. Based on this analysis, AECC determined that 
the estimated cost-effectiveness of the add-on control options are as 
follows: $3,558,286/ton for a wet scrubber; $54,570/ton for a cyclone; 
and $981,583/ton for a wet ESP. AECC determined that the estimated 
cost-effectiveness of the fuel switching options are as follows: 
$27,528/ton for No. 6 fuel oil with 1% sulfur content; $22,386/ton for 
No. 6 fuel oil with 0.5% sulfur content; $25,004/ton for diesel; and 
$2,327/ton for natural gas. AECC noted that it does not consider any of 
the PM control options to be cost-effective.
    ADEQ explained that AECC's PM BART evaluation did not discuss any 
energy or non-air quality environmental impacts associated with fuel 
switching. AECC did identify certain energy and non-air quality 
environmental impacts associated with wet ESPs and wet scrubbers. These 
impacts, which are factored in the cost of compliance, include 
increased energy usage for operation of the control equipment, the 
generation of wastewater streams that must be treated on-site or sent 
to a waste water treatment plant, and the generation of a filter cake 
that would likely require land-filling. In assessing the remaining 
useful life of Bailey Unit 1, AECC concluded that this factor does not 
impact the annualized costs of the evaluated control options since the 
remaining useful life of Bailey Unit 1 is at least as long as the 
capital cost recovery period of 15 years.
    In assessing visibility impacts, the state's submittal included 
CALPUFF modeling evaluating the visibility benefits of switching from 
the baseline fuel oil (assuming 100% use of fuel oil) to the various 
fuel switching options. We summarize the results of that modeling in 
Table 3.
---------------------------------------------------------------------------

    \46\ The modeled visibility improvement of the fuel switching 
options reflects both SO2 and PM emissions reductions 
since reductions in filterable PM are directly related to the sulfur 
content of the fuel.

                                      Table 3--Anticipated Visibility Benefit of PM Controls at AECC Bailey Unit 1
                                                               [CALPUFF, 98th percentile]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                        Visibility benefit of controls over baseline (dv) \46\
                                                                  Baseline  ----------------------------------------------------------------------------
                                                                 visibility                                     No. 6      No. 6
                          Class I area                             impact       Wet                           fuel oil-- fuel oil--  Diesel--   Natural
                                                                    (dv)      scrubber   Cyclone    Wet ESP   1% sulfur     0.5%      0.05%       gas
                                                                                                                           sulfur     sulfur
--------------------------------------------------------------------------------------------------------------------------------------------------------
Caney Creek....................................................       0.330      0.002      0.002      0.003      0.137      0.188      0.246      0.247
Upper Buffalo..................................................       0.347      0.002      0.002      0.004      0.154      0.221      0.279      0.276
Hercules-Glades................................................       0.367      0.007      0.006      0.011      0.162      0.233      0.299      0.295
Mingo..........................................................       0.378      0.004      0.004      0.007      0.173      0.209      0.284      0.277
--------------------------------------------------------------------------------------------------------------------------------------------------------

    The anticipated visibility benefits of add-on controls (i.e., wet 
scrubber, cyclone, and wet ESP) are anticipated to be very small, 
ranging from 0.002 to 0.011 dv at each affected Class I area. As 
discussed above, fuel switching to lower

[[Page 62212]]

sulfur fuels is expected to result in both lower filterable PM 
emissions and lower SO2 emissions. Switching to 1% sulfur 
No. 6 fuel oil is anticipated to achieve visibility benefits of 
approximately 0.137 dv at Caney Creek, 0.154 dv at Upper Buffalo, 0.162 
dv at Hercules-Glades, and 0.173 dv at Mingo over baseline visibility 
conditions. Switching to 0.5% sulfur No. 6 fuel oil is anticipated to 
achieve visibility benefits of approximately 0.188 dv at Caney Creek, 
0.221 dv at Upper Buffalo, 0.233 dv at Hercules-Glades, and 0.209 dv at 
Mingo over the baseline. The visibility benefits of switching to diesel 
are anticipated to be even greater, with benefits of approximately 
0.246 dv at Caney Creek, 0.279 dv at Upper Buffalo, 0.299 dv at 
Hercules-Glades, and 0.284 dv at Mingo over the baseline. The 
visibility benefits of switching to natural gas are anticipated to be 
only slightly more than switching to diesel. The modeled visibility 
improvement of switching to lower sulfur fuels reflects benefits of 
both SO2 and PM emissions reductions since reductions in 
filterable PM are directly related to the sulfur content of the fuel. 
We do note that the majority of the baseline visibility impact at each 
Class I area when burning the baseline fuel oil is due to 
SO2 emissions that form sulfate PM, while direct 
PM10 emissions contribute only a small portion of the 
baseline visibility impacts at each Class I area.\47\ Accordingly, the 
majority of the visibility improvement associated with switching to 
lower sulfur fuels, as shown in Table 3, can reasonably be expected to 
be the result of a reduction in SO2 emissions rather than PM 
emissions.
---------------------------------------------------------------------------

    \47\ See Table 4-3 BASELINE VISIBILITY IMPAIRMENT ATTRIBUTABLE 
TO BAILEY, UNIT 1 (2001-2003)--FUEL OIL, ``BART Five Factor 
Analysis, Arkansas Electric Cooperative Corporation Bailey and 
McClellan Generating Stations,'' dated March 2014, Version 4, 
prepared by Trinity Consultants Inc. in conjunction with Arkansas 
Electric Cooperative Corporation,'' which can be found in Appendix B 
to the Arkansas Regional Haze SO2 and PM BART SIP 
Revision.
---------------------------------------------------------------------------

    Taking into consideration the cost-effectiveness and the 
anticipated visibility improvement of the PM control options 
considered, ADEQ concluded that add-on controls are not cost-effective, 
with AECC estimating the cost of these controls to be approximately 
$55,000/ton and greater. ADEQ concluded that the cost of switching to 
lower sulfur fuels is also not a cost-effective method for reducing PM 
emissions. However, ADEQ noted that the SO2 BART 
determination for Bailey Unit 1, which is the use of fuel that has 0.5% 
or less sulfur content by weight, would also result in PM emissions 
reductions. ADEQ therefore arrived at the determination that PM BART 
for Bailey Unit 1 is no additional control beyond switching to fuel 
with 0.5% or less sulfur content, consistent with the SO2 
BART decision for the unit.
    We do not agree with the use of a 15-year capital cost recovery 
period for calculating the average cost-effectiveness of a wet ESP, wet 
scrubber, and cyclone. Per the EPA Control Cost Manual, facilities are 
to rely on a 30-year capital cost recovery period for calculating the 
average cost-effectiveness of a wet ESP, wet scrubber, or cyclone 
barring a technical rationale to deviate from the 30-year capital cost 
recovery period. AECC Bailey Generating Station did not provide a 
technical rationale to deviate from the assumed 30-year capital cost 
recovery period. In addition, we are not aware of any enforceable 
shutdown date for the AECC Bailey Generating Station, nor did AECC's 
evaluation or ADEQ's SIP revision indicate any future planned shutdown 
or provide any reason for adopting a 15-year equipment life for the 
controls under consideration. Therefore, we believe that assuming a 30-
year equipment life rather than a 15-year equipment life would be more 
appropriate for these control technologies.\48\ Extending the 
amortization period from 15 to 30 years has the effect of decreasing 
the total annual cost of each control option, thereby improving the 
average cost-effectiveness value of controls (i.e., lower dollars per 
ton removed). As discussed above, the cost of add-on PM control 
equipment at Bailey Unit 1, assuming a 15-year remaining useful life, 
ranges from $54,570/ton of PM removed for a cyclone to $3,558,286/ton 
of PM removed for a wet scrubber. Even though adjusting the costs of 
the add-on controls based on a 30-year remaining useful life as opposed 
to a 15-year remaining useful life would decrease the $/ton costs, we 
anticipate that the costs in $/ton would still be considerable and well 
outside of the range that has generally been considered to be cost-
effective for BART. Therefore, we believe that add-on PM controls would 
still not be justified in light of the considerable costs and the 
minimal visibility benefits, which would range from 0.002 to 0.011 at 
each Class I area (see Table 3 above). Therefore, we are proposing to 
agree with ADEQ's determination that PM add-on controls are not PM BART 
for Bailey Unit 1.
---------------------------------------------------------------------------

    \48\ The Arkansas Regional Haze FIP assumed a 30-year equipment 
life in the PM BART analysis for AECC Bailey Unit 1. See 80 FR 
18955.
---------------------------------------------------------------------------

    We also disagree with the total annual cost and cost-effectiveness 
values for fuel switching presented in AECC's PM BART analysis \49\ and 
in the SIP revision. In AECC's SO2 BART cost analysis for 
the same unit, the company considered the same fuel switching options, 
yet the total annual cost numbers presented in the PM cost analysis are 
significantly greater than those presented in the SO2 cost 
analysis.\50\ This appears to be because in the SO2 cost 
analysis, AECC calculated the differential cost of fuel switching 
(i.e., the difference in cost between the baseline fuel and the fuel 
switching options), whereas the absolute cost of the fuel switching 
options was calculated in the PM cost analysis. We believe that AECC 
and ADEQ should have considered the differential cost of fuel switching 
as opposed to the absolute cost of fuel for each of the fuel switching 
options in the PM BART analysis, as was done in the SO2 BART 
analysis. Thus, we believe that the correct cost effectiveness values 
that ADEQ should have considered in the PM BART analysis are those 
presented in Table 5-9 of AECC's SO2 BART analysis,\51\ 
which shows that the costs of switching to fuel oil with a sulfur 
content of 1% or 0.5% are within the range that have generally been 
considered to be cost-effective for BART. Although switching to diesel 
would result in additional reductions in PM emissions, we believe that 
the additional cost per ton for switching to diesel would be high in 
comparison to the additional visibility benefits.\52\ We

[[Page 62213]]

believe that switching to fuel with 0.5% or less sulfur content is 
within the range that has generally been considered to be cost-
effective for BART and since the source will have to comply with that 
same requirement for SO2 BART, we consider it appropriate to 
require it under PM BART as well. Therefore, we are proposing to 
approve ADEQ's determination that PM BART for AECC Bailey Unit 1 is no 
additional control beyond switching to fuel with 0.5% or less sulfur 
content by October 27, 2021. Additionally, the owner or operator of the 
unit shall not purchase fuel for combustion at the unit that does not 
meet this sulfur content limit as of the effective date of the 
Administrative Order, which is August 7, 2018. This BART determination 
has now been made enforceable by the state through an Administrative 
Order that has been adopted and incorporated in the SIP revision. We 
are proposing to approve into the SIP the state's Administrative Order 
with respect to the PM BART requirements for AECC Bailey Unit 1.\53\
---------------------------------------------------------------------------

    \49\ See ``BART Five Factor Analysis, Arkansas Electric 
Cooperative Corporation Bailey and McClellan Generating Stations,'' 
dated March 2014, Version 4, prepared by Trinity Consultants Inc. in 
conjunction with Arkansas Electric Cooperative Corporation,'' Table 
7-4, page 7-6. This BART analysis can be found in Appendix B to the 
Arkansas Regional Haze SO2 and PM BART SIP Revision.
    \50\ See ``BART Five Factor Analysis, Arkansas Electric 
Cooperative Corporation Bailey and McClellan Generating Stations,'' 
dated March 2014, Version 4, prepared by Trinity Consultants Inc. in 
conjunction with Arkansas Electric Cooperative Corporation,'' Table 
5-9, page 5-9.
    \51\ See ``BART Five Factor Analysis, Arkansas Electric 
Cooperative Corporation Bailey and McClellan Generating Stations,'' 
dated March 2014, Version 4, prepared by Trinity Consultants Inc. in 
conjunction with Arkansas Electric Cooperative Corporation,'' Table 
5-9, column titled ``PM10 Cost Effectiveness,'' page 5-9.
    \52\ Based on Table 5-13 from AECC's SO2 BART 
analysis, switching to diesel would result in an additional 
visibility benefit of 0.111 dv compared to switching to 1% No. 6 
fuel oil, and in an additional visibility benefit of only 0.075 dv 
compared to switching to 0.5% No. 6 fuel oil at Mingo, which is the 
Class I area with the greatest visibility impacts from Bailey Unit 
1. Based on Table 5-9 from AECC's SO2 BART analysis, the 
corrected cost of switching to 1% and 0.5% No. 6 fuel oil is 
estimated to be $1,165/ton of PM removed and $2,998/ton of PM 
removed (respectively), while the corrected cost of diesel is 
estimated to be $7,608/ton of PM removed. We do not consider the 
additional cost of switching to diesel at Bailey Unit 1 to be 
warranted by the additional level of anticipated visibility benefit.
    \53\ The Administrative Order can be found in the Arkansas 
Regional Haze SO2 and PM BART SIP Revision.
---------------------------------------------------------------------------

    The state's PM BART decision for Bailey Unit 1 is consistent with 
the BART decision EPA previously made in the FIP we promulgated on 
September 27, 2016.\54\ We are concurrently proposing to withdraw the 
FIP's PM BART requirements for Bailey Unit 1, as they would be replaced 
by our approval of the state's PM BART decision.
---------------------------------------------------------------------------

    \54\ The Arkansas Regional Haze FIP required Bailey Unit 1 to 
only use fuel with a sulfur content limit of 0.5% by weight, with a 
compliance date of October 27, 2021. Additionally, the FIP 
prohibited the owner or operator of the unit from purchasing fuel 
for combustion at the unit that does not meet the sulfur content 
limit; the compliance date for this requirement was October 27, 
2016. See 81 FR 66335 and 66415-16.
---------------------------------------------------------------------------

2. AECC McClellan Unit 1
    The AECC McClellan Unit 1 has a wall-fired boiler, a gross output 
of 122 MW and a maximum heat input rate of 1,436 MMBtu/hr. The unit is 
currently permitted to burn pipeline quality natural gas and fuel oil. 
The fuel oil burned is currently subject to a sulfur content limit of 
2.8% by weight. AECC produced BART analyses dated March 2014 for 
McClellan Unit 1, which were evaluated by EPA and largely formed the 
basis for EPA's SO2 and PM BART evaluations in the FIP.\55\ 
The same BART analyses \56\ have now been adopted and incorporated by 
ADEQ into the Arkansas Regional Haze SO2 and PM BART SIP 
revision to address the SO2 and PM BART requirements for 
McClellan Unit 1.
---------------------------------------------------------------------------

    \55\ 80 FR 18957.
    \56\ ``BART Five Factor Analysis, Arkansas Electric Cooperative 
Corporation Bailey and McClellan Generating Stations,'' dated March 
2014, Version 4, prepared by Trinity Consultants Inc. in conjunction 
with Arkansas Electric Cooperative Corporation,'' which can be found 
in Appendix B to the Arkansas Regional Haze SO2 and PM 
BART SIP Revision.
---------------------------------------------------------------------------

a. SO2 BART Analysis and Determination
    In assessing SO2 BART, ADEQ explained that AECC 
considered the five BART factors. In assessing feasible control 
technologies and their effectiveness, AECC considered FGD systems and 
fuel switching during fuel oil burning. Due to the intrinsically low 
sulfur content of natural gas, no control technologies were evaluated 
for natural gas burning scenarios. As such, the BART analysis focused 
on fuel oil firing as the base case. For fuel oil firing, fuel 
switching was determined to be the only technically feasible control 
option, and thus AECC did not further consider FGD for SO2 
BART. The baseline fuel AECC assumed in the BART analysis is No. 6 fuel 
oil with 1.38% sulfur content by weight, which is based on the average 
sulfur content of the fuel oil from the most recent shipment received 
by the facility in April 2009. ADEQ explained that AECC evaluated 
switching to the following fuel types: 1% Sulfur No. 6 fuel oil, 
corresponding to an estimated 28% control efficiency; 0.5% sulfur No. 6 
fuel oil, corresponding to 64% control efficiency; and 0.05% sulfur 
diesel, corresponding to 96% control efficiency.\57\
---------------------------------------------------------------------------

    \57\ We also note that AECC evaluated switching to natural gas 
as an available SO2 control option in its SO2 
BART analysis, but the evaluation of this control option was not 
discussed by ADEQ in the SIP revision. We discuss this issue in 
greater detail below when we present our evaluation of the state's 
BART determination.
---------------------------------------------------------------------------

    In considering the costs of compliance for fuel switching, AECC 
concluded that the fuel switching options evaluated would not require 
capital investments in equipment, but instead the annual costs would be 
based upon operation and maintenance costs associated with the 
different fuel types. AECC estimated that the cost-effectiveness of 
switching McClellan Unit 1 to No. 6 fuel oil with 1% and 0.5% sulfur 
content by weight is $2,613/ton and $3,823/ton, respectively. Switching 
to diesel, which has 0.05% sulfur content, is estimated to cost $7,145/
ton. ADEQ stated that the cost in dollars per ton for diesel is out of 
the range of what is typically considered cost-effective, while the 
cost of both 1% and 0.5% sulfur No. 6 fuel oil is estimated to be 
within the range of what is typically considered cost-effective.
    ADEQ stated that AECC's evaluation did not identify any energy or 
non-air quality environmental impacts associated with switching to 1% 
sulfur No. 6 fuel oil, 0.5% sulfur No. 6 fuel oil, or diesel. In 
assessing the remaining useful life of McClellan Unit 1, AECC concluded 
that this factor does not impact the annualized costs of the evaluated 
control options since fuel switching is not expected to require any 
significant capital costs in this case.
    In assessing visibility impacts, the state's submittal included 
CALPUFF modeling evaluating the visibility benefits of switching from 
the baseline fuel (assuming 100% use of fuel oil) to the various fuel 
switching options. We summarize the results of that modeling in Table 
4.

             Table 4--Anticipated Visibility Benefit Due to Fuel Switching at AECC McClellan Unit 1
                                           [CALPUFF, 98th percentile]
----------------------------------------------------------------------------------------------------------------
                                                                   Visibility benefit of controls over baseline
                                                                                       (dv)
                                                     Baseline    -----------------------------------------------
                  Class I area                      visibility                      No. 6 fuel
                                                    impact (dv)     No. 6 fuel       oil--0.5%     Diesel--0.05%
                                                                  oil--1% sulfur      sulfur          sulfur
----------------------------------------------------------------------------------------------------------------
Caney Creek.....................................           0.622           0.085           0.300           0.448
Upper Buffalo...................................           0.266           0.035           0.120           0.193
Hercules-Glades.................................           0.231           0.029           0.116           0.169

[[Page 62214]]

 
Mingo...........................................           0.228           0.035           0.092           0.148
----------------------------------------------------------------------------------------------------------------

    Switching to 1% sulfur No. 6 fuel oil is anticipated to achieve 
visibility benefits of approximately 0.085 dv at Caney Creek, 0.035 dv 
at Upper Buffalo, 0.029 dv at Hercules-Glades, and 0.035 dv at Mingo 
over baseline visibility conditions. Switching to 0.5% sulfur No. 6 
fuel oil is anticipated to achieve visibility benefits of approximately 
0.300 dv at Caney Creek, 0.120 dv at Upper Buffalo, 0.116 dv at 
Hercules-Glades, and 0.092 dv at Mingo over the baseline. The 
visibility benefits of switching to diesel are anticipated to be even 
greater, with benefits of approximately 0.448 dv at Caney Creek, 0.193 
dv at Upper Buffalo, 0.169 dv at Hercules-Glades, and 0.148 dv at Mingo 
over the baseline.
    Taking into consideration the cost-effectiveness and the 
anticipated visibility improvement of the fuel switching options, ADEQ 
concurred with AECC's recommendation that SO2 BART for AECC 
McClellan Unit 1 be determined to be the use of fuel with a sulfur 
content by weight of 0.5% or less.
    We note that switching to diesel would result in additional 
reductions in SO2 emissions, but the additional costs per 
ton for doing so would be high in comparison to the additional 
visibility benefits. We also note that AECC evaluated switching to 
natural gas as an available SO2 control option in its 
SO2 BART analysis,\58\ but the evaluation of this control 
option in the SO2 BART analysis was not discussed by ADEQ in 
the SIP revision. In its analysis, AECC explained that switching to 
natural gas may have an adverse energy impact during periods of natural 
gas curtailment and that the ability to burn both fuel oil and natural 
gas was important for the facility to maintain electrical 
reliability.\59\ Therefore, AECC did not recommend switching to natural 
gas and instead recommended switching to fuels with 0.5% sulfur content 
to be SO2 BART for McClellan Unit 1.\60\ In the Arkansas 
Regional Haze FIP, we agreed with AECC's recommendation, and explained 
that the BART Guidelines provide that it is not our intent to direct 
subject-to-BART sources to switch fuel forms, such as from coal or fuel 
oil to natural gas (40 CFR part 51, Appendix Y, section IV.D.1).\61\ We 
noted that since natural gas has a sulfur content by weight that is 
well below 0.5%, the facility may elect to use this type of fuel to 
comply with BART, but we did not require a switch to natural gas for 
SO2 BART in the FIP.\62\ Therefore, we do not find that 
ADEQ's lack of consideration of switching to natural gas as an 
SO2 control option in the SO2 BART analysis for 
McClellan Unit 1 changes the result of the BART analysis in this 
instance. We are proposing to approve the state's determination that 
SO2 BART for McClellan Unit 1 is the use of fuel with a 
sulfur content by weight of 0.5% or less. We are also proposing to 
approve the state's determination that McClellan Unit 1 must comply 
with this BART requirement no later than October 27, 2021, and that as 
of the effective date of the Administrative Order, which is August 7, 
2018, the source shall not purchase fuel that does not meet the sulfur 
limit requirement for combustion at McClellan Unit 1. These BART 
requirements have now been made enforceable by the state through an 
Administrative Order that has been adopted and incorporated in the SIP 
revision. The Administrative Order for AECC McClellan Unit 1 includes 
not only the requirement to limit the sulfur content of the fuel 
burned, but also requirements for the source to sample and analyze each 
shipment of fuel to determine the sulfur content by weight and maintain 
records pertaining to the sampling of each fuel shipment to assess 
compliance with the BART requirements.\63\ We are proposing to approve 
the state's Administrative Order, including the compliance 
determination requirements contained in the Administrative Order, into 
the SIP. The state's SO2 BART emission limit and compliance 
date for McClellan Unit 1 are consistent with the BART decision EPA 
previously made in the FIP we promulgated on September 27, 2016.\64\ We 
are concurrently proposing to withdraw the FIP's SO2 BART 
requirements for McClellan Unit 1, as they would be replaced by our 
approval of the state's SO2 BART decision.
---------------------------------------------------------------------------

    \58\ See ``BART Five Factor Analysis, Arkansas Electric 
Cooperative Corporation Bailey and McClellan Generating Stations, 
dated March 2014, Version 4, prepared by Trinity Consultants Inc. in 
conjunction with Arkansas Electric Cooperative Corporation,'' pages 
5-1 to 5-14. This BART analysis has been adopted and incorporated by 
ADEQ into the SIP revision (see Appendix B to the Arkansas Regional 
Haze SO2 and PM BART SIP revision).
    \59\ See ``BART Five Factor Analysis, Arkansas Electric 
Cooperative Corporation Bailey and McClellan Generating Stations, 
dated March 2014, Version 4, prepared by Trinity Consultants Inc. in 
conjunction with Arkansas Electric Cooperative Corporation,'' pages 
5-2, 5-10, and 5-14.
    \60\ Id.
    \61\ See 80 FR at 18959 and 81 FR at 66340.
    \62\ Id.
    \63\ The Administrative Order can be found in the Arkansas 
Regional Haze SO2 and PM BART SIP Revision.
    \64\ The Arkansas Regional Haze FIP requires McClellan Unit 1 to 
only use fuel with a sulfur content limit of 0.5% by weight, with a 
compliance date of October 27, 2021. Additionally, the FIP prohibits 
the owner or operator of the unit from purchasing fuel for 
combustion at the unit that does not meet the sulfur content limit; 
the compliance date for this requirement is October 27, 2016. See 81 
FR 66335 and 66415-16.
---------------------------------------------------------------------------

b. PM BART Analysis and Determination
    PM emissions are inherently low when burning natural gas, but are 
higher when burning fuel oil. McClellan Unit 1 does not currently have 
pollution control equipment for PM emissions. In assessing PM BART for 
McClellan Unit 1, ADEQ explained that AECC considered the five BART 
factors. In assessing feasible control technologies and their 
effectiveness, AECC considered the following control technologies for 
PM BART: Dry ESP, wet ESP, fabric filter, wet scrubber, cyclone, and 
fuel switching. AECC's evaluation noted that the particulate matter 
from oil-fired boilers tends to be sticky and small, affecting the 
collection efficiency of dry ESPs and fabric filters. Dry ESPs operate 
by placing a charge on the particles through a series of electrodes, 
and then capturing the charged particles on collection plates,

[[Page 62215]]

while fabric filters work by filtering the PM in the flue gas through 
filter bags. The collected particles are periodically removed from the 
filter bag through a pulse jet or reverse flow mechanism. Because of 
the sticky nature of particles from oil-fired boilers, AECC considered 
dry ESPs and fabric filters to be technically infeasible for use at 
McClellan Unit 1. AECC found wet ESPs, wet scrubbers, cyclones, and 
fuel switching to be technically feasible PM control options.
    Residual fuel, such as the baseline No. 6 fuel oil burned at 
McClellan Unit 1, has inherent ash that contributes to emissions of 
filterable PM. Reductions in filterable PM emissions are directly 
related to the sulfur content of the fuel. Therefore, switching to No. 
6 fuel oil with a lower sulfur content is expected to result in lower 
filterable PM emissions. Also, ash content is much lower in a 
distillate fuel such as diesel and essentially zero in natural gas. The 
fuel switching options considered by AECC in the BART analysis are No. 
6 fuel oil with 1% sulfur content by weight, No. 6 fuel oil with 0.5% 
sulfur content by weight, natural gas, and diesel. AECC estimated that 
switching to a lower sulfur fuel has a PM control efficiency ranging 
from approximately 44%-99%, depending on the fuel type. The estimated 
PM control efficiency of each control option is summarized in Table 5.

                Table 5--PM Control Efficiency of BART Control Options for AECC McClellan Unit 1
----------------------------------------------------------------------------------------------------------------
                                                                                  Fuel switching
                                                                 -----------------------------------------------
      PM control option           Wet       Cyclone     Wet ESP               No. 6 fuel
                               scrubber                           No. 6 fuel   oil--0.5%    Natural     Diesel
                                                                   oil--1% S       S          gas
----------------------------------------------------------------------------------------------------------------
PM Control Efficiency (%)...       55.0        85.0        90.0        43.6        82.4        99.0        99.2
----------------------------------------------------------------------------------------------------------------

    In considering the costs of the PM control options, AECC noted that 
add-on controls such as the wet scrubber, cyclone, and wet ESP involve 
capital costs for new equipment, which AECC annualized over a 15-year 
period in the analysis. Based on this analysis, AECC determined that 
the estimated cost-effectiveness of the add-on control options are as 
follows: $695,549/ton for a wet scrubber; $14,882/ton for a cyclone; 
and $266,237/ton for a wet ESP. AECC determined that the estimated 
cost-effectiveness of the fuel switching options are as follows: 
$53,044/ton for No. 6 fuel oil with 1% sulfur content; $31,338/ton for 
No. 6 fuel oil with 0.5% sulfur content; $32,952/ton for diesel; and 
$571/ton for natural gas. AECC noted that it does not consider any of 
the PM control options to be cost-effective.
    ADEQ explained that AECC's PM BART evaluation did not discuss any 
energy or non-air quality environmental impacts associated with fuel 
switching. AECC did identify certain energy and non-air quality 
environmental impacts associated with wet ESPs and wet scrubbers. These 
impacts, which are factored in the cost of compliance, include 
increased energy usage for operation of the control equipment, the 
generation of wastewater streams that must be treated on-site or sent 
to a waste water treatment plant, and the generation of a filter cake 
that would likely require land-filling. In assessing the remaining 
useful life of McClellan Unit 1, AECC concluded that this factor does 
not impact the annualized costs of the evaluated control options since 
the remaining useful life of McClellan Unit 1 is at least as long as 
the capital cost recovery period of 15 years.
    In assessing visibility impacts, the state's submittal included 
CALPUFF modeling evaluating the visibility benefits of switching from 
the baseline fuel oil (assuming 100% use of fuel oil) to the various 
fuel switching options. We summarize the results of that modeling in 
Table 6.

                                     Table 6--Anticipated Visibility Benefit of PM Controls at AECC McClellan Unit 1
                                                               [CALPUFF, 98th percentile]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                     Visibility benefit of controls over baseline  (dv) \65\
                                                              Baseline  --------------------------------------------------------------------------------
                                                             visibility                                     No. 6      No. 6
                        Class I area                           impact       Wet                           fuel oil-- fuel oil-- Diesel--0.05%   Natural
                                                                (dv)      scrubber   Cyclone    Wet ESP   1% sulfur     0.5%        sulfur        gas
                                                                                                                       sulfur
--------------------------------------------------------------------------------------------------------------------------------------------------------
Caney Creek................................................       0.621      0.002      0.002      0.004      0.085      0.300        0.448        0.497
Upper Buffalo..............................................       0.266      0.002      0.001      0.003      0.035      0.120        0.193        0.214
Hercules-Glades............................................       0.230      0.002      0.001      0.003      0.029      0.116        0.169        0.191
Mingo......................................................       0.227      0.003      0.002      0.004      0.035      0.092        0.148         0.17
--------------------------------------------------------------------------------------------------------------------------------------------------------

    The anticipated visibility benefits of add-on controls (i.e., wet 
scrubber, cyclone, and wet ESP) are very small, ranging from 0.001 to 
0.004 dv at each affected Class I area. As discussed above, fuel 
switching to lower sulfur fuels is expected to result in both lower 
filterable PM emissions and lower SO2 emissions. Switching 
to 1% sulfur No. 6 fuel oil is anticipated to achieve visibility 
benefits of approximately 0.085 dv at Caney Creek, 0.035 dv at Upper 
Buffalo, 0.029 dv at Hercules-Glades, and 0.035 dv at Mingo over 
baseline visibility conditions. Switching to 0.5% sulfur No. 6 fuel oil 
is anticipated to achieve visibility benefits of approximately 0.3 dv 
at Caney Creek, 0.12 dv at Upper Buffalo, 0.116 dv at Hercules-Glades, 
and 0.092 dv at Mingo over the baseline. The visibility benefits of 
switching to diesel are anticipated to be even greater, with benefits 
of approximately 0.448 dv at Caney Creek, 0.193 dv at Upper Buffalo, 
0.169 dv at

[[Page 62216]]

Hercules-Glades, and 0.148 dv at Mingo over the baseline. The 
visibility benefits of switching to natural gas are anticipated to be 
only slightly more than switching to diesel. The modeled visibility 
improvement of switching to lower sulfur fuels reflects benefits of 
both SO2 and PM emissions reductions since reductions in 
filterable PM are directly related to the sulfur content of the fuel. 
We do note that the majority of the baseline visibility impact at each 
Class I area when burning the baseline fuel oil is due to 
SO2 emissions that form sulfate PM, while direct 
PM10 emissions contribute only a small portion of the 
baseline visibility impacts at each Class I area.\66\ Accordingly, the 
majority of the visibility improvement associated with switching to 
lower sulfur fuels, as shown in Table 6, can reasonably be expected to 
be the result of a reduction in SO2 emissions rather than PM 
emissions.
---------------------------------------------------------------------------

    \65\ The modeled visibility improvement of the fuel switching 
options reflects both SO2 and PM emissions reductions 
since reductions in filterable PM are directly related to the sulfur 
content of the fuel.
    \66\ See Table 4-5 BASELINE VISIBILITY IMPAIRMENT ATTRIBUTABLE 
TO McCLELLAN, UNIT 1 (2001-2003)--FUEL OIL, ``BART Five Factor 
Analysis, Arkansas Electric Cooperative Corporation Bailey and 
McClellan Generating Stations,'' dated March 2014, Version 4, 
prepared by Trinity Consultants Inc. in conjunction with Arkansas 
Electric Cooperative Corporation,'' which can be found in Appendix B 
to the Arkansas Regional Haze SO2 and PM BART SIP 
Revision.
---------------------------------------------------------------------------

    Taking into consideration the cost-effectiveness and the 
anticipated visibility improvement of the PM control options 
considered, ADEQ concluded that add-on controls are not cost-effective, 
with AECC estimating the cost of these controls to be approximately 
$15,000/ton and greater. ADEQ concluded that the cost of switching to 
lower sulfur fuels is also not a cost-effective method for reducing PM 
emissions. However, ADEQ noted that the SO2 BART 
determination for McClellan Unit 1, which is the use of fuel that has 
0.5% or less sulfur content by weight, would also result in PM 
emissions reductions. ADEQ therefore arrived at the determination that 
PM BART for McClellan Unit 1 is no additional control beyond switching 
to fuel with 0.5% or less sulfur content, consistent with the 
SO2 BART decision for the unit.
    We do not agree with the use of a 15-year capital cost recovery 
period for calculating the average cost-effectiveness of a wet ESP, wet 
scrubber, and cyclone. Per the EPA Control Cost Manual, facilities are 
to rely on a 30-year capital cost recovery period for calculating the 
average cost-effectiveness of a wet ESP, wet scrubber, or cyclone 
barring a technical rationale to deviate from the 30-year capital cost 
recovery period. AECC Bailey Generating Station did not provide a 
technical rationale to deviate from the assumed 30-year capital cost 
recovery period. In addition, we are not aware of any enforceable 
shutdown date for the AECC McClellan Generating Station, nor did AECC's 
evaluation or ADEQ's SIP revision indicate any future planned shutdown 
or provide any reason for adopting a 15-year equipment life for the 
controls under consideration. Therefore, we believe that assuming a 30-
year equipment life rather than a 15-year equipment life would be more 
appropriate for these control technologies.\67\ Extending the 
amortization period from 15 to 30 years has the effect of decreasing 
the total annual cost of each control option, thereby improving the 
average cost-effectiveness value of controls (i.e., lower dollars per 
ton removed). As discussed above, the cost of add-on PM control 
equipment at McClellan Unit 1, assuming a 15-year remaining useful 
life, ranges from $14,882/ton of PM removed for a cyclone to $695,549/
ton of PM removed for a wet scrubber. Even though adjusting the costs 
of the add-on controls based on a 30-year remaining useful life as 
opposed to a 15-year remaining useful life would decrease the $/ton 
costs, we anticipate that the costs in $/ton would still be 
considerable and well outside of the range that has generally been 
considered to be cost-effective for BART. Therefore, we believe that 
add-on PM controls would still not be justified in light of the 
considerable costs and the minimal visibility benefits, which would 
range from 0.001 to 0.004 at each Class I area (see Table 6 above). 
Therefore, we are proposing to agree with ADEQ's determination that PM 
add-on controls are not PM BART for McClellan Unit 1.
---------------------------------------------------------------------------

    \67\ The Arkansas Regional Haze FIP assumed a 30-year equipment 
life in the PM BART analysis for AECC McClellan Unit 1. See 80 FR 
18962.
---------------------------------------------------------------------------

    We also disagree with the total annual cost and cost-effectiveness 
values for fuel switching presented in AECC's PM BART analysis \68\ and 
in the SIP revision. In AECC's SO2 BART cost analysis for 
the same unit, the company considered the same fuel switching options, 
yet the total annual cost numbers presented in the PM cost analysis are 
significantly greater than those presented in the SO2 cost 
analysis.\69\ This appears to be because in the SO2 cost 
analysis, AECC calculated the differential cost of fuel switching 
(i.e., the difference in cost between the baseline fuel and the fuel 
switching options), whereas the absolute cost of the fuel switching 
options was calculated in the PM cost analysis. We believe that AECC 
and ADEQ should have considered the differential cost of fuel switching 
as opposed to the absolute cost of fuel for each of the fuel switching 
options in the PM BART analysis, as was done in the SO2 BART 
analysis. Thus, we believe that the correct cost effectiveness values 
that ADEQ should have considered in the PM BART analysis are those 
presented in Table 5-10 of AECC's SO2 BART analysis,\70\ 
which shows that the costs of switching to fuel oil with a sulfur 
content of 1% or 0.5% are within the range that have generally been 
considered to be cost effective for BART. Although switching to diesel 
would result in additional reductions in PM emissions, we believe that 
the additional cost per ton for switching to diesel would be high in 
comparison to the additional visibility benefits.\71\ We believe that 
switching to fuel with 0.5% or less sulfur content is within the range 
that has generally been considered to be cost-effective for BART and 
since the source will have to comply with that same requirement for 
SO2 BART, we consider it appropriate to require it under PM 
BART as well. Therefore, we are proposing to approve ADEQ's 
determination that PM BART for AECC McClellan Unit 1 is no additional 
control beyond switching to fuel with 0.5% or less sulfur content by 
October 27, 2021. Additionally, the owner or

[[Page 62217]]

operator of the unit shall not purchase fuel for combustion at the unit 
that does not meet this sulfur content limit as of the effective date 
of the Administrative Order, which is August 7, 2018. This BART 
determination has now been made enforceable by the state through an 
Administrative Order that has been adopted and incorporated in the SIP 
revision. We are proposing to approve into the SIP the state's 
Administrative Order with respect to the PM BART requirements for AECC 
McClellan Unit 1.\72\
---------------------------------------------------------------------------

    \68\ See ``BART Five Factor Analysis, Arkansas Electric 
Cooperative Corporation Bailey and McClellan Generating Stations,'' 
dated March 2014, Version 4, prepared by Trinity Consultants Inc. in 
conjunction with Arkansas Electric Cooperative Corporation,'' Table 
7-5, page 7-6. This BART analysis can be found in Appendix B to the 
Arkansas Regional Haze SO2 and PM BART SIP Revision.
    \69\ See ``BART Five Factor Analysis, Arkansas Electric 
Cooperative Corporation Bailey and McClellan Generating Stations,'' 
dated March 2014, Version 4, prepared by Trinity Consultants Inc. in 
conjunction with Arkansas Electric Cooperative Corporation,'' Table 
5-10, page 5-9.
    \70\ See ``BART Five Factor Analysis, Arkansas Electric 
Cooperative Corporation Bailey and McClellan Generating Stations,'' 
dated March 2014, Version 4, prepared by Trinity Consultants Inc. in 
conjunction with Arkansas Electric Cooperative Corporation,'' Table 
5-10, column titled ``PM10 Cost Effectiveness,'' page 5-
9.
    \71\ Based on Table 5-14 from AECC's SO2 BART 
analysis, switching to diesel would result in an additional 
visibility benefit of 0.363 dv compared to switching to 1% No. 6 
fuel oil and in an additional visibility benefit of only 0.148 dv 
compared to switching to 0.5% No. 6 fuel oil at Caney Creek, which 
is the Class I area with the greatest visibility impacts from 
McClellan Unit 1. Based on Table 5-10 from AECC's SO2 
BART analysis, the corrected costs of switching to 1% and 0.5% No. 6 
fuel oil is estimated to be $2,457/ton of PM removed and $4,553/ton 
of PM removed (respectively), while the corrected cost of switching 
to diesel is estimated to be $10,698/ton of PM removed. We do not 
consider the additional cost of switching to diesel at McClellan 
Unit 1 to be warranted by the additional level of anticipated 
visibility benefit.
    \72\ The Administrative Order can be found in the Arkansas 
Regional Haze SO2 and PM BART SIP Revision.
---------------------------------------------------------------------------

    The state's PM BART decision for McClellan Unit 1 is consistent 
with the BART decision EPA previously made in the FIP we promulgated on 
September 27, 2016.\73\ We are concurrently proposing to withdraw the 
FIP's PM BART requirements for McClellan Unit 1, as they would be 
replaced by our approval of the state's PM BART decision.
---------------------------------------------------------------------------

    \73\ The Arkansas Regional Haze FIP required McClellan Unit 1 to 
only use fuel with a sulfur content limit of 0.5% by weight, with a 
compliance date of October 27, 2021. Additionally, the FIP 
prohibited the owner or operator of the unit from purchasing fuel 
for combustion at the unit that does not meet the sulfur content 
limit; the compliance date for this requirement was October 27, 
2016. See 81 FR 66335 and 66415-16.
---------------------------------------------------------------------------

3. SWEPCO Flint Creek Plant Boiler No. 1
    SWEPCO Flint Creek Plant Boiler No. 1 has a 558 MW dry bottom wall-
fired boiler that commenced operation in 1978, has a maximum heat input 
of 6,324 MMBtu/hr, and burns low sulfur western coal as a primary fuel, 
but is also permitted to combust fuel oil and tire-derived fuels. Fuel 
oil firing is only allowed during unit startup and shutdown, during 
startup and shutdown of pulverizer mills, for flame stabilization when 
coal is frozen, for No. 2 fuel oil tank maintenance, to prevent boiler 
tube failure in extreme cold weather when the unit is offline for 
maintenance, and during malfunction.
    SWEPCO produced a BART analysis dated September 2013 for Flint 
Creek Plant Boiler No. 1, which was evaluated by EPA and largely formed 
the basis for EPA's SO2 BART evaluation in the FIP.\74\ This 
BART analysis \75\ has now been adopted and incorporated by ADEQ into 
the Arkansas Regional Haze SO2 and PM BART SIP revision to 
address the SO2 BART requirements for Flint Creek Boiler No. 
1.\76\
---------------------------------------------------------------------------

    \74\ 80 FR 18964.
    \75\ ``BART Five Factor Analysis Flint Creek Power Plant Gentry, 
Arkansas (AFIN 04-00107),'' dated September 2013, Version 4, 
prepared by Trinity Consultants Inc. in conjunction with American 
Electric Power Service Corporation for the Southwestern Electric 
Power Company Flint Creek Power Plant,'' which can be found in 
Appendix E to the Arkansas Regional Haze SO2 and PM BART 
SIP Revision.
    \76\ In a final action published on March 12, 2012, EPA approved 
Arkansas' PM BART determination for Flint Creek Plant Boiler No. 1. 
In the Arkansas Regional Haze SO2 and PM BART SIP 
revision, the state is not revising that BART determination or the 
underlying analysis.
---------------------------------------------------------------------------

a. SO2 BART Analysis and Determination
    At the time that SWEPCO performed the BART analysis, no 
SO2 controls were in place at Flint Creek Plant Boiler No. 
1. The cost analysis and visibility improvement data that are part of 
SWEPCO's BART analysis are based on the 2001-2003 baseline, not on 
emissions reflecting current SO2 controls in place. Since 
the time the BART analysis was developed, SWEPCO has installed a Novel 
Integrated Deacidification (NID) system and Activated Carbon Injection 
(ACI) system at Flint Creek Boiler No. 1 in anticipation of regional 
haze requirements as well as other CAA requirements. The installation 
of these controls was completed in May 2016.
    In assessing SO2 BART, SWEPCO considered the five BART 
factors. The available SO2 retrofit control technology 
options considered were dry sorbent injection (DSI), dry FGD, and wet 
FGD.\77\ DSI was estimated to have a control efficiency of 40-60%. Dry 
FGD was estimated to have a control efficiency of 60-95%. NID, which is 
a form of dry FGD, was predicted to have a control efficiency of 92%, 
achieving an SO2 emission rate of 0.06 lb/MMBtu. Wet FGD was 
estimated to have a control efficiency of 80-95%, achieving an 
SO2 emission rate of 0.04 lb/MMBtu. All control options 
considered were deemed to be technically feasible.
---------------------------------------------------------------------------

    \77\ SWEPCO's September 2013 SO2 BART analysis did 
not identify or discuss any existing SO2 control 
equipment in use at the source because at the time the BART analysis 
was developed, there were no existing SO2 controls in 
place. Since the Arkansas Regional Haze SO2 and PM SIP 
revision was submitted at a time when the NID system is the 
pollution control equipment in use at the source, we give ADEQ 
credit for considering the existing pollution controls factor in the 
SIP revision because the existing SO2 control equipment 
is among the ``new'' controls addressed in the older SWEPCO 
SO2 BART analysis.
---------------------------------------------------------------------------

    In considering the costs of compliance, SWEPCO estimated the 
capital and operating costs of a NID system and wet FGD based on EPA's 
Control Cost Manual and supplemented, where available, with vendor and 
site-specific information obtained by SWEPCO. These values were then 
used by SWEPCO to estimate the cost-effectiveness of controls. SWEPCO 
estimated the cost of the SO2 control options to be $3,845/
ton for a NID system and $4,919/ton for wet FGD. Since control options 
with higher control efficiencies were within a range considered cost-
effective (with one ultimately selected as BART), SWEPCO's BART 
analysis did not evaluate the cost of DSI or further consider that 
control option in the analysis. Thus, the remainder of SWEPCO's 
analysis focused on a NID system (dry FGD) and wet FGD.
    SWEPCO determined that although wet FGD is expected to achieve a 
slightly higher level of SO2 control compared to NID 
technology, it would also have greater potential negative energy and 
nonair quality environmental impacts. For example, wet FGD is expected 
to generate large volumes of wastewater and solid waste/sludge that 
must be treated. Additionally, wet FGD systems have increased power 
requirements and increased reagent usage over dry FGD, as well as the 
potential for increased particulate and sulfuric acid mist releases. 
The costs associated with increased power requirements and greater 
reagent usage have already been factored into the cost analysis for wet 
FGD. In assessing the remaining useful life of Flint Creek Boiler No. 
1, SWEPCO concluded that this factor does not impact the annualized 
capital costs of the evaluated control options because the useful life 
of the unit is anticipated to be at least as long as the capital cost 
recovery period (30 years).
    In assessing visibility impacts, the state's submittal included 
CALPUFF modeling evaluating the visibility benefits of dry FGD and wet 
FGD. We summarize the results of that modeling in Table 7.

[[Page 62218]]

             Table 7--Anticipated Visibility Benefit Due to SO2 Controls at Flint Creek Boiler No. 1
                                           [CALPUFF, 98th percentile]
----------------------------------------------------------------------------------------------------------------
                                                                                  Visibility benefit of controls
                                                                     Baseline           over baseline  (dv)
                          Class I area                              visibility   -------------------------------
                                                                    impact (dv)     NID System        Wet FGD
----------------------------------------------------------------------------------------------------------------
Caney Creek.....................................................           0.963           0.615           0.629
Upper Buffalo...................................................           0.965           0.464           0.477
Hercules-Glades.................................................           0.657           0.345           0.352
Mingo...........................................................           0.631           0.414           0.423
----------------------------------------------------------------------------------------------------------------

    The installation and operation of SO2 controls is 
anticipated to result in considerable visibility improvement from the 
baseline at the four impacted Class I areas. NID technology is 
anticipated to result in visibility improvement ranging from 0.345 to 
0.615 dv at each affected Class I area. Although wet FGD is also 
anticipated to result in considerable visibility improvement, the 
visibility benefit of wet FGD over NID technology at each individual 
Class I area is anticipated to be only slight, ranging from 0.007 to 
0.014 dv at each Class I area.
    As discussed above, SWEPCO determined that NID technology would 
result in considerable visibility improvement and is estimated to cost 
$3,845/ton. On the other hand, a wet scrubber is estimated to cost 
$4,919/ton, and would only achieve slightly more visibility benefit 
than NID technology (see Table 7).\78\ Therefore, SWEPCO recommended 
that SO2 BART for Flint Creek Boiler No. 1 be an emission 
limit of 0.06 lb/MMBtu on a 30-day rolling average over each boiler 
operating day, based on the installation of NID technology. ADEQ 
concurred with this BART recommendation. We are proposing to agree that 
an SO2 emission limit of 0.06 lb/MMBtu based on NID 
technology would result in significant visibility benefits from the 
baseline and is generally cost-effective. We do not believe the 
additional cost of a wet scrubber would be justified in light of the 
small amount of additional visibility benefit anticipated over NID 
technology. Therefore, we are proposing to approve the state' 
determination that SO2 BART for Flint Creek Boiler No. 1 is 
an emission limit of 0.06 lb/MMBtu based on NID technology.
---------------------------------------------------------------------------

    \78\ Although not discussed by ADEQ in the SIP revision, 
SWEPCO's BART analysis also presents the incremental cost 
effectiveness of wet scrubbers over NID technology. As shown in 
Tables 5-3 and 5-7 of SWEPCO's September 2013 SO2 BART 
analysis for Flint Creek, the incremental cost effectiveness of wet 
scrubbers over NID technology for Boiler No. 1 is estimated to be 
$35,198/ton removed, yet the incremental visibility benefit is 
projected to be only 0.014 dv at Caney Creek and 0.013 dv at Upper 
Buffalo and even less at Hercules Glades and Mingo.
---------------------------------------------------------------------------

    Taking into consideration that the control equipment has already 
been installed and is operating at the facility, we are also proposing 
to approve the state's determination that the source must comply with 
the SO2 BART requirements as of the effective date of the 
Administrative Order, which is August 7, 2018. These BART requirements 
have now been made enforceable by the state through an Administrative 
Order that has been adopted and incorporated in the SIP revision. The 
Administrative Order for Flint Creek Boiler No. 1 includes not only the 
SO2 emission limit, but also a requirement for the source to 
determine compliance with the SO2 emission limit by using a 
continuous emission monitoring system.\79\ We are proposing to approve 
into the SIP the state's Administrative Order with respect to the 
SO2 BART requirements, including the compliance 
determination requirements contained in the Administrative Order. The 
state's SO2 BART decision for Flint Creek Boiler No. 1 is 
consistent with the BART decision EPA previously made in the FIP we 
promulgated on September 27, 2016.\80\ We are concurrently proposing to 
withdraw the FIP's SO2 BART requirements for Flint Creek 
Boiler No. 1, as they would be replaced by our approval of the state's 
SO2 BART decision.
---------------------------------------------------------------------------

    \79\ The Administrative Order can be found in the Arkansas 
Regional Haze SO2 and PM BART SIP Revision.
    \80\ 81 FR 66335 and 66416-17.
---------------------------------------------------------------------------

4. Entergy Lake Catherine Unit 4
    Entergy Lake Catherine Unit 4 has a 558 MW tangentially-fired 
boiler with a maximum heat input of 5,850 MMBtu/hr. Lake Catherine Unit 
4 is currently permitted to burn only pipeline quality natural gas, but 
until recently was also permitted to burn No. 6 fuel oil as a secondary 
fuel. Entergy produced a BART analysis dated May 2014 for Lake 
Catherine Unit 4, which was evaluated by EPA and largely formed the 
basis for EPA's BART evaluation in the FIP.\81\ The same BART analysis 
\82\ has now been adopted and incorporated by ADEQ into the Arkansas 
Regional Haze SO2 and PM BART SIP revision to address BART 
requirements for Lake Catherine Unit 4 under the fuel oil firing 
scenario.\83\
---------------------------------------------------------------------------

    \81\ 80 FR 18975.
    \82\ ``Revised BART Five Factor Analysis Lake Catherine Steam 
Electric Station Malvern, Arkansas (AFIN 30-00011),'' dated May 
2014, prepared by Trinity Consultants Inc. in conjunction with 
Entergy Services Inc.,'' which can be found in Appendix C to the 
Arkansas Regional Haze SO2 and PM BART SIP Revision.
    \83\ In a final action published on March 12, 2012, EPA approved 
Arkansas' SO2 and PM BART determinations under the 
natural gas firing scenario for Lake Catherine Unit 4. In the 
Arkansas Regional Haze SO2 and PM BART SIP revision, the 
state is not revising those BART determinations or any of the 
underlying analyses.
---------------------------------------------------------------------------

    In the May 2014 BART analysis submitted by ADEQ as part of the SIP 
revision, Entergy explained that no fuel oil has been burned at Unit 4 
since prior to the 2001-2003 baseline period and that the company does 
not project that it will burn fuel oil at the unit in the foreseeable 
future. Therefore, the May 2014 BART analysis does not consider 
emissions from fuel oil firing and does not include a BART five factor 
analysis or BART determinations for the fuel oil firing scenario. 
Entergy stated in the BART analysis that if conditions change such that 
it becomes economic to burn fuel oil in the future, it will submit a 
BART five factor analysis for the fuel oil firing scenario to the state 
for use in the development of a SIP revision, and that Entergy commits 
to not burn fuel oil at Lake Catherine Unit 4 until final EPA approval 
of BART for the fuel oil firing scenario. Furthermore, Unit 4 is not 
currently permitted to burn fuel oil.\84\ Entergy's commitment has now 
been made enforceable by the state through an Administrative Order that 
has been adopted and incorporated in the SIP revision. We are proposing 
to find that

[[Page 62219]]

this approach is appropriate and we are proposing to approve the 
state's Administrative Order for Lake Catherine Unit 4 into the SIP. 
The Administrative Order would allow the unit to burn natural gas only, 
per Entergy's commitment to not burn fuel oil at Unit 4 until ADEQ 
submits a SIP revision that includes BART analyses for the fuel oil 
firing scenario for Unit 4 and EPA takes final action to approve the 
BART determinations. The state's action with respect to addressing BART 
for the fuel oil firing scenario for Lake Catherine Unit 4 is 
consistent with the action EPA previously took in the FIP we 
promulgated on September 27, 2016.\85\ We are concurrently proposing to 
withdraw the FIP provision concerning BART for the fuel oil firing 
scenario for Lake Catherine Unit 4, as it would be replaced by our 
approval of the state's BART action.
---------------------------------------------------------------------------

    \84\ See ADEQ Air Permit No. 1717-AOP-R7, issued on October 26, 
2016. A copy of the air permit can be found in the docket for this 
proposed rulemaking.
    \85\ 81 FR 66335 and 66418.
---------------------------------------------------------------------------

5. Entergy White Bluff Units 1 and 2 and the White Bluff Auxiliary 
Boiler
    Entergy White Bluff Units 1 and 2 each have tangentially-fired 850 
MW boilers with a maximum heat input capacity of 8,950 MMBtu/hr. White 
Bluff also has a 183 MMBtu/hr Auxiliary Boiler that is permitted to 
burn only No. 2 fuel oil or biodiesel. Entergy produced a BART analysis 
for White Bluff dated October 2013, which was evaluated by EPA and 
largely formed the basis for EPA's SO2 BART evaluation in 
the FIP.\86\ Entergy also submitted revised analyses dated August 2015 
and August 2016 for EPA to consider before the FIP was finalized. 
Entergy provided ADEQ with supplemental information on April 5, 2017, 
providing cost-effectiveness data for dry FGD for Units 1 and 2 with 
various remaining useful life assumptions. Additionally, at ADEQ's 
request, Entergy produced an updated BART analysis dated August 18, 
2017, that evaluated several control options and provided updated 
remaining useful life information for White Bluff Units 1 and 2. These 
BART analyses and other documentation provided by Entergy have been 
adopted and incorporated by ADEQ into the Arkansas Regional Haze 
SO2 and PM BART SIP revision \87\ to address the 
SO2 BART requirements for White Bluff Units 1 and 2, as well 
as the SO2, NOX, and PM BART requirements for the 
Auxiliary Boiler.\88\
---------------------------------------------------------------------------

    \86\ 80 FR 18969. See also ``Revised BART Five Factor Analysis 
White Bluff Steam Electric Station Redfield, Arkansas (AFIN 35-
00110),'' dated October 2013, prepared by Trinity Consultants Inc. 
in conjunction with Entergy Services Inc.'' This BART analysis can 
be found in Appendix D to the Arkansas Regional Haze SO2 
and PM BART SIP Revision.
    \87\ These BART analyses and other information provided by 
Entergy can be found in Appendix D to the Arkansas Regional Haze 
SO2 and PM BART SIP Revision.
    \88\ In a final action published on March 12, 2012, EPA approved 
Arkansas' PM BART determinations for White Bluff Units 1 and 2. In 
the Arkansas Regional Haze SO2 and PM BART SIP revision, 
the state is not revising those PM BART determinations or any of the 
underlying analyses.
---------------------------------------------------------------------------

a. White Bluff Unit 1 and Unit 2 SO2 BART Analysis and 
Determinations
    In assessing SO2 BART, Entergy considered the five BART 
factors. There is currently no SO2 control equipment in use 
at Units 1 and 2. The current permitted SO2 emissions rate 
for Units 1 and 2 is a 3-hour average emission rate of 1.2 lb/MMBtu, 
based on the new source performance standard for fossil-fuel fired 
steam generators in effect at the time they were constructed. The 
available SO2 control technology options considered in 
Entergy's August 2017 BART analysis are switching to low sulfur coal, 
DSI, spray dryer absorber (SDA), circulating dry scrubber (CDS), and 
wet FGD.
    Entergy estimated that by switching to low sulfur coal, Units 1 and 
2 can achieve an emission rate of 0.6 lb/MMBtu,\89\ which would result 
in approximately an 8.75% reduction in SO2 emissions from 
baseline levels. For DSI, Entergy considered two particulate collection 
methods. The first collection method, ``DSI,'' would utilize the 
existing ESP, and is expected to achieve a control efficiency of 50%. 
Entergy expects that DSI would achieve an SO2 emission rate 
of 0.35 lb/MMBtu. The second collection method, ``enhanced DSI,'' would 
require the installation of a fabric filter or baghouse. The use of a 
fabric filter or baghouse in enhanced DSI increases the residence time 
and improves the collection efficiency to allow more sorbent to be 
injected, thereby resulting in greater emissions reductions. Entergy 
expects that enhanced DSI would achieve 80% control efficiency, and an 
SO2 emission rate of 0.15 lb/MMBtu. In the August 2017 BART 
analysis, Entergy claimed that DSI has not yet been demonstrated on 
units comparable to those at White Bluff. Entergy explained that the 
largest known installed and operational DSI system has a design feed 
rate of 12 tons/hour of sorbent, while most installed DSI systems 
typically inject approximately 5-6 tons/hour of sorbent into the 
exhaust gas stream. Entergy pointed out that the predicted injection 
rate of enhanced DSI at White Bluff is approximately 15 tons/hour of 
sorbent. Entergy noted that the greater the injection rates, it is 
anticipated that more issues associated with supply and delivery 
logistics are likely to arise. Entergy stated that before DSI 
technology is selected as BART for White Bluff, a demonstration test 
would need to be performed to confirm its feasibility, achievable 
performance, and balance of plant impacts (brown plume formation, ash 
handling modifications, landfill/leachate considerations, and impact to 
mercury control).
---------------------------------------------------------------------------

    \89\ The White Bluff SO2 BART analysis provided to 
ADEQ by Entergy and incorporated by ADEQ as part of the SIP revision 
considered an SO2 emission limit of 0.6 lb/MMBtu for the 
switching to low sulfur coal control option. However, in response to 
comments the state received during the public comment period that 
noted that it is typical to round to the nearest significant digit 
when demonstrating compliance, which could result in less emissions 
reductions than assumed in the BART analysis, ADEQ ultimately 
finalized an emission limit of 0.60 lb/MMBtu in the final SIP 
revision.
---------------------------------------------------------------------------

    The dry FGD control option considered by Entergy is SDA, which 
utilizes a fine mist of lime slurry sprayed into an absorption tower to 
absorb SO2 with the resulting calcium sulfite and calcium 
sulfate then collected with a fabric filter. SDA systems can typically 
achieve SO2 control efficiencies ranging from 60-95%. 
Entergy expects that an SDA system would achieve an emission rate of 
0.06 lb/MMBtu at Units 1 and 2. Although wet FGD was identified as a 
technically feasible control option, it is not expected to achieve 
significant visibility benefit beyond dry/semi-dry FGD despite having a 
greater estimated cost, based on the October 2013 BART analysis that 
EPA relied on to develop the Arkansas Regional Haze FIP.\90\ In fact, 
dry/semi-dry FGD was expected to achieve slightly greater visibility 
benefit than wet FGD at Hercules-Glades and Mingo based on the October 
2013 BART analysis.\91\ Therefore, Entergy did not further consider wet 
FGD in its August 18, 2017, BART analysis, on which the Arkansas 
Regional Haze SO2 and PM BART SIP revision is largely based.
---------------------------------------------------------------------------

    \90\ 80 FR 18972.
    \91\ 80 FR 18972.
---------------------------------------------------------------------------

    In considering the costs of compliance, Entergy's coal suppliers 
provided the company with an estimated incremental cost of $0.50 per 
ton for delivering coal guaranteed to have a sulfur content consistent 
with achieving an SO2 emission limit of 0.6 lb/MMBtu. ADEQ 
noted in the SIP revision that the annualized cost of switching to low 
sulfur coal is not dependent on the remaining useful life of White 
Bluff Units 1 and 2, since no capital investments in equipment would be 
necessary. For the remaining control options, Entergy obtained capital 
costs

[[Page 62220]]

and annual operating and maintenance costs from its consultant and used 
this to estimate the cost effectiveness of controls. The annualized 
cost of DSI, enhanced DSI, and dry/semi-dry FGD is dependent on the 
remaining useful life of the White Bluff units since those control 
options require capital investments in new equipment or retrofit of 
existing equipment. These capital investments were amortized over the 
remaining useful life of the White Bluff units to determine the 
annualized costs and compared to annual emission reductions to 
determine cost-effectiveness. In the August 18, 2017, BART analysis, 
Entergy stated that it anticipates cessation of coal combustion at 
White Bluff by the end of 2028 and that it will voluntarily take an 
enforceable restriction on Units 1 and 2 to that effect. ADEQ noted 
that the BART Guidelines provide that the remaining useful life 
calculation should begin on the date that controls will be put in place 
(i.e., compliance date) and end on the date the facility permanently 
stops operations.\92\ The Regional Haze Rule also states that the 
compliance date for BART controls must be as expeditiously as 
practicable, but in no event later than 5 years after approval of the 
SIP.\93\ Considering that the FIP currently requires SO2 
emission limits for White Bluff Units 1 and 2 that are based on dry 
scrubber installation and which have a compliance date of October 27, 
2021, ADEQ acknowledged that the record suggests that a compliance date 
for scrubbers that is ``as expeditiously as practicable'' would be 
October 27, 2021. Therefore, ADEQ assumed a remaining useful life of 7 
years to estimate the cost-effectiveness of SDA for White Bluff Units 1 
and 2. Entergy also assumed that DSI and enhanced DSI could be 
installed and operational 2 years earlier than FGD, and therefore 
assumed in the BART analysis that DSI and enhanced DSI could be 
operational at White Bluff Units 1 and 2 by the end of 2019 and that 
the capital recovery period for those controls is therefore 9 years.
---------------------------------------------------------------------------

    \92\ 70 FR 39104.
    \93\ 40 CFR 51.308(e)(iv).
---------------------------------------------------------------------------

    Entergy also explained that for DSI, enhanced DSI, and SDA, it 
developed two sets of cost estimates. The first is the actual cost 
Entergy anticipates incurring for each control option, and the second 
reflects the exclusion of certain cost items that are disallowed costs 
under the methodology in the EPA's Air Pollution Control Cost Manual 
(EPA Control Cost Manual).\94\ These ``disallowed'' line items include 
Allowance for Funds Used During Construction (AFUDC). Entergy stated in 
its BART analysis that it disagrees with EPA that AFUDC and certain 
other cost items are not allowed to be considered in estimating the 
cost effectiveness of controls for BART purposes under the EPA Control 
Cost Manual, but nonetheless provided a set of cost estimates 
reflecting the exclusion of the disallowed line items as well as a set 
of cost estimates that included these line items. ADEQ explained in the 
SIP revision that its evaluation of controls is based on Entergy's set 
of cost numbers that excludes the disallowed line items and follows the 
EPA Control Cost Manual. Therefore, we present here only the set of 
cost numbers that follows the methodology allowed under the Control 
Cost Manual.\95\
---------------------------------------------------------------------------

    \94\ At the time the BART Guidelines were finalized, the current 
version of the Control Cost Manual was the EPA Air Pollution Control 
Cost Manual, Sixth Edition, EPA/452/B-02-001, January 2002. https://www.epa.gov/economic-and-cost-analysis-air-pollution-regulations/cost-reports-and-guidance-air-pollution. The EPA is engaged in a 
long-term process to update portions of the Control Cost Manual. A 
project plan describing the scope and schedule for this update 
effort is available at https://www3.epa.gov/ttn/ecas/docs/cost_manual_timeline_2016-08-04.pdf. As draft or final updated 
chapters are available, states should follow the recommendations in 
those rather than in the 6th Edition. Final revised chapters are 
posted at https://www.epa.gov/economic-and-cost-analysis-air-pollution-regulations/cost-reports-and-guidance-air-pollution. Draft 
revised chapters are announced in the Federal Register when 
available for public comment and can be obtained from EPA Docket No. 
EPA-HQ-OAR-2015-0341 at www.regulationgs.gov.
    \95\ Please see the TSD associated with this proposed rulemaking 
and the Arkansas Regional Haze SO2 and PM SIP revision 
for Entergy's set of cost numbers that included line items that are 
not allowed to be considered in estimating the cost effectiveness of 
controls for BART purposes under the EPA Control Cost Manual.
---------------------------------------------------------------------------

    Entergy determined that switching to low sulfur coal would entail 
an increased annual cost of operation based on purchase contract terms 
for the specific sulfur content of the coal. Based on estimates 
provided by the coal supplier of the cost premium for low sulfur coal 
and the estimated reduction in emissions, Entergy anticipated that the 
cost to guarantee that the units achieve an SO2 emission 
limit of 0.6 lb/MMBtu translates to a cost-effectiveness for 
SO2 control of approximately $1,150/ton at Unit 1 and 
$1,148/ton at Unit 2. Entergy estimated the cost-effectiveness of DSI 
to be $6,269/ton at Unit 1 and $6,211/ton at Unit 2 and the cost-
effectiveness of enhanced DSI to be $6,427/ton at Unit 1 and $6,384/ton 
at Unit 2. Entergy also estimated the cost of SDA to be $5,420/ton at 
Unit 1 and $5,387/ton at Unit 2. In the BART analysis, ADEQ also took 
into consideration the cost of controls in terms of dollars per dv 
improvement ($/dv) for each SO2 control option considered 
for White Bluff. A summary of the cost of controls in terms of $/dv is 
provided in Table 8. A summary of Entergy's assessment of the 
visibility benefits of the control options in terms of dv is presented 
in Tables 9 and 10. ADEQ stated that the average cost-effectiveness 
values for DSI, enhanced DSI, and SDA at White Bluff all exceed what is 
typically considered to be cost-effective for BART, taking into account 
a capital cost recovery period of 7 years for SDA and 9 years for DSI 
and enhanced DSI. ADEQ noted that cost-effectiveness values of BART 
determinations made in previous regional haze actions have typically 
been below $5,000/ton, and that the costs of DSI and SDA exceed this 
value. Additionally, ADEQ noted that the cost in terms of $/dv for DSI, 
enhanced DSI, and SDA are approximately an order of magnitude greater 
than for switching to low sulfur coal.

                       Table 8--Cost of SO2 Controls ($/dv) for White Bluff Units 1 and 2
----------------------------------------------------------------------------------------------------------------
                                                                           Class I area
                                                 ---------------------------------------------------------------
               SO2 control option                                                    Hercules
                                                    Caney Creek    Upper Buffalo      Glades           Mingo
----------------------------------------------------------------------------------------------------------------
Low Sulfur Coal.................................     $14,500,519     $11,932,988     $10,666,332     $13,554,882
DSI.............................................     133,341,667     105,417,939     120,512,761     116,126,126
Enhanced DSI....................................     158,855,956     139,165,572     168,897,541     173,433,064
SDA.............................................     131,447,683     121,373,255     153,165,608     153,852,117
----------------------------------------------------------------------------------------------------------------

[[Page 62221]]

    In the BART analysis, Entergy noted that there were adverse energy 
and nonair quality environmental impacts associated with DSI, enhanced 
DSI, and SDA. These impacts were factored into the costs of compliance. 
With regard to consideration of the remaining useful life factor, 
Entergy stated in the August 2017 BART analysis that it anticipates 
cessation of coal combustion at White Bluff by the end of 2028 and that 
it will voluntarily take an enforceable restriction on Units 1 and 2 to 
that effect. Entergy's voluntary decision to cease coal combustion by 
the end of 2028 is enforceable by the state through an Administrative 
Order that has been adopted and incorporated in the SIP revision. 
Therefore, for White Bluff Units 1 and 2, ADEQ assumed a remaining 
useful life of 7 years to estimate the cost-effectiveness of SDA and a 
remaining useful life of 9 years to estimate the cost-effectiveness of 
DSI.
    In assessing visibility impacts, the state's submittal included the 
CALPUFF modeling that was included in Entergy's August 18, 2017, BART 
analysis, evaluating the visibility benefits of switching to low sulfur 
coal, DSI, enhanced DSI, and SDA. We summarize the results of that 
modeling in Tables 9 and 10.\96\
---------------------------------------------------------------------------

    \96\ As explained by ADEQ in the SIP revision, Entergy's 
modeling of the visibility improvement from evaluated SO2 
controls in the August 18, 2017, SO2 BART analysis for 
White Bluff is based on an updated baseline of 2009-2013 emissions, 
rather than the 2001-2003 emissions baseline EPA used in the 
Arkansas Regional Haze FIP to estimate the visibility improvement 
anticipated from SDA and wet FGD. Entergy's change in baseline 
emissions impacts the modeled visibility benefit anticipated from 
SDA, resulting in a modeled visibility benefit that is 15% to 26% 
lower at each unit in Entergy's updated analysis compared to the 
FIP. In the FIP, EPA did not evaluate the visibility improvement 
anticipated from DSI, enhanced DSI, and switching to low sulfur 
coal, but ADEQ stated it expects that the relative difference in $/
dv among the control options evaluated by Entergy would be similar 
across both baseline periods. Further, ADEQ believes that the 
differences in projected visibility benefits resulting from 
different baseline emissions in the FIP, compared to the updated 
Entergy BART analysis, would not result in a change to ADEQ's 
ultimate SO2 BART decision for White Bluff Units 1 and 2.

                Table 9--Anticipated Visibility Benefit Due to SO2 Controls at White Bluff Unit 1
                                          [CALPUFF, 98th percentile] *
----------------------------------------------------------------------------------------------------------------
                                                        Visibility benefit of controls over baseline  (dv)
                                     Baseline    ---------------------------------------------------------------
          Class I area              visibility      Low sulfur
                                   impact  (dv)        coal             DSI        Enhanced DSI         SDA
----------------------------------------------------------------------------------------------------------------
Caney Creek.....................           1.505           0.129           0.308           0.492           0.603
Upper Buffalo...................           1.051           0.143           0.375           0.555           0.642
Hercules-Glades.................           0.925           0.167           0.341           0.467           0.525
Mingo...........................           0.802           0.115           0.333           0.436           0.504
----------------------------------------------------------------------------------------------------------------
* This table shows the modeled visibility benefits of SO2 controls for White Bluff Unit 1, as presented in Table
  4-6 of Entergy's August 18, 2017, SO2 BART analysis for White Bluff, which can be found in Appendix D of the
  Arkansas Regional Haze SO2 and PM SIP revision. Although the combined visibility benefits on a facility-wide
  basis were not modeled, we expect that such combined visibility benefits would be greater than the unit
  specific values shown in this table.

               Table 10--Anticipated Visibility Benefit Due to SO2 Controls at White Bluff Unit 2
                                          [CALPUFF, 98th percentile] *
----------------------------------------------------------------------------------------------------------------
                                                        Visibility benefit of controls over baseline  (dv)
                                     Baseline    ---------------------------------------------------------------
          Class I area              visibility      Low sulfur
                                   impact  (dv)        coal             DSI        Enhanced DSI         SDA
----------------------------------------------------------------------------------------------------------------
Caney Creek.....................           1.533           0.097           0.274           0.460           0.574
Upper Buffalo...................           1.059           0.127           0.359           0.531           0.632
Hercules-Glades.................           0.912           0.137           0.303           0.429           0.486
Mingo...........................           0.819           0.122           0.333           0.435           0.501
----------------------------------------------------------------------------------------------------------------
* This table shows the modeled visibility benefits of SO2 controls for White Bluff Unit 2, as presented in Table
  4-7 of Entergy's August 18, 2017, SO2 BART analysis for White Bluff, which can be found in Appendix D of the
  Arkansas Regional Haze SO2 and PM SIP revision. Although the combined visibility benefits on a facility-wide
  basis were not modeled, we expect that such combined visibility benefits would be greater than the unit
  specific values shown in this table.

    The SO2 control options considered are anticipated to 
result in considerable visibility improvement from the baseline at the 
four impacted Class I areas. For White Bluff Unit 1, switching to low 
sulfur coal is anticipated by the state submittal to result in 
visibility improvement ranging from 0.115 to 0.167 dv at each affected 
Class I area. DSI is anticipated to result in visibility improvement 
ranging from 0.308 to 0.375 dv at each affected Class I area, while 
enhanced DSI is anticipated to result in visibility improvement ranging 
from 0.436 to 0.555 dv. SDA is anticipated to result in the greatest 
visibility improvement, ranging from 0.504 to 0.642 dv.
    For White Bluff Unit 2, switching to low sulfur coal is anticipated 
by the state submittal to result in visibility improvement ranging from 
0.097 to 0.137 dv at each affected Class I area. DSI is anticipated to 
result in visibility improvement ranging from 0.274 to 0.359 dv at each 
affected Class I area, while enhanced DSI is anticipated to result in 
visibility improvement ranging from 0.429 to 0.531 dv. SDA is 
anticipated to result in the greatest visibility improvement, ranging 
from 0.486 to 0.632 dv.

[[Page 62222]]

    Taking into consideration the remaining useful life of White Bluff 
Units 1 and 2 and the resulting cost-effectiveness as well as the 
anticipated visibility improvement of the SO2 control 
options, ADEQ concurred with Entergy's recommendation that 
SO2 BART for White Bluff Units 1 and 2 is an emission limit 
of 0.60 lb/MMBtu based on the use of low sulfur coal.\97\ All other 
SO2 control options for White Bluff have an average cost-
effectiveness value greater than $5,000/ton, which ADEQ stated exceeds 
what has typically been considered to be cost-effective for BART. 
Additionally, ADEQ noted that the cost-effectiveness in terms of $/dv 
for DSI, enhanced DSI, and SDA are approximately an order of magnitude 
greater than for LSC. Considering the costs and the visibility benefits 
of the control options, ADEQ determined that SO2 BART for 
White Bluff is an emission limit of 0.60 lb/MMBtu based on the use of 
low sulfur coal.\98\
---------------------------------------------------------------------------

    \97\ Entergy evaluated an SO2 emission rate of 0.6 
lb/MMBtu based on the use of low sulfur coal in the SO2 
BART analysis for White Bluff. However, ADEQ ultimately selected 
0.60 lb/MMBtu as the BART emission limit in response to comments it 
received during the state public comment period raising concerns 
that finalizing an emission limit of 0.6 lb/MMBtu could result in 
smaller SO2 reductions than assumed because it is typical 
to round to the nearest significant digit when demonstrating 
compliance.
    \98\ The White Bluff SO2 BART analysis submitted by 
Entergy and ADEQ's SIP revision both considered an SO2 
emission limit of 0.6 lb/MMBtu for the switching to low sulfur coal 
control option. However, in response to comments the state received 
during the public comment period that noted that it is typical to 
round to the nearest significant digit when demonstrating 
compliance, which could result in less emissions reductions than 
assumed in the analysis, ADEQ ultimately finalized an emission limit 
of 0.60 lb/MMBtu in the final SIP revision.
---------------------------------------------------------------------------

    In support of its assertion that a 3-year compliance deadline is 
needed to meet this emission limit, Entergy submitted a letter to ADEQ 
dated April 3, 2018, explaining that it is the company's practice to 
project how much coal will be needed in future years and to contract 
for a portion of its coal supply up to 3 years in advance.\99\ Entergy 
stated that it keeps a reserve supply of coal at White Bluff to ensure 
that the units can continue to operate in the event of a fuel supply 
disruption. Entergy finds that a 3-year compliance date is necessary 
for the 0.60 lb/MMBtu emission limit because the sulfur content limits 
of Entergy's existing coal contracts for the next 3 years exceed this 
emission rate. Entergy is currently under contract for coal with a 
sulfur content of 1.2 lb/MMBtu or less. Entergy noted that even though 
the coal delivered to White Bluff has lately been of lower sulfur 
content than required by the contract, its experience is that the 
sulfur content can vary widely. Entergy also stated that as of the 
letter dated April 3, 2018, it had already contracted for a portion of 
its coal supply needs for the next 3 years (through the end of the year 
2020). Those contracts are for coal with a sulfur content limit ranging 
from 0.7 to 0.9 lb/MMBtu. Additionally, Entergy stated it cannot 
accurately calculate expected SO2 emissions from blending of 
coals from its stockpile and new deliveries of coal because the sulfur 
content of the stockpile coal is not tracked. Entergy explained that 
this means that it cannot ensure that White Bluff will receive coal 
with a low enough sulfur content to ensure compliance with the 0.60 lb/
MMBtu emission limit until the company has had sufficient time to 
negotiate new contracts and the existing coal supply has been depleted 
and replaced with coal that has a lower sulfur content. ADEQ agreed 
that a 3-year compliance date for the 0.60 lb/MMBtu emission limit 
based on the use of low sulfur coal is reasonable given the site-
specific circumstances for White Bluff as discussed in Entergy's letter 
dated April 3, 2018.
---------------------------------------------------------------------------

    \99\ The letter from Entergy, dated April 3, 2018, is found in 
Appendix D the Arkansas Regional Haze SO2 and PM BART SIP 
Revision.
---------------------------------------------------------------------------

    With regard to the cost analysis for SO2 controls for 
White Bluff, we agree that AFUDC and certain other cost items are not 
allowed to be considered in estimating the cost effectiveness of 
controls for BART purposes under the EPA Control Cost Manual, and we 
also acknowledge and agree with ADEQ's decision to base its evaluation 
of controls on Entergy's set of cost numbers that does not include the 
disallowed line items. Nevertheless, there is one aspect of Entergy's 
cost analysis that we do not agree with. Entergy's cost analysis is 
based on an SDA system assuming a coal sulfur content of 1.2 lb/MMBtu, 
which Entergy stated is based on its current coal contract sulfur 
limit. However, the White Bluff units have historically burned coal 
with a lower sulfur content. In its BART analysis, Entergy stated that 
the current average sulfur content of coal received at the White Bluff 
station is 0.57 lb SO2/MMBtu but that the facility could 
receive coal with sulfur content up to 1.2 lb SO2/MMBtu. 
Given that, Entergy's analysis is based on a scrubber designed to 
handle that sulfur load. In the Arkansas Regional Haze FIP, we noted 
that Entergy's SO2 cost analysis for White Bluff, which was 
provided to us by Entergy for EPA's evaluation and consideration in the 
development of the FIP, took the approach of costing a scrubber system 
designed to burn coal with a sulfur content much higher than what has 
been historically burned,\100\ an approach similar to what Entergy has 
done in the August 2017 BART analysis. In the FIP, we stated that we 
disagreed with Entergy's approach for costing of the scrubber system, 
and our FIP cost analysis was instead based on a dry scrubber system 
assuming a sulfur content of 0.68 lb/MMBtu, the maximum monthly 
emission rate from 2009-2013. Relying on our FIP's cost analysis for 
dry scrubbers for White Bluff, which was based on a scrubber system 
designed to burn coal having a sulfur content consistent with what the 
units have historically burned, and adjusting for a 7-year as opposed 
to a 30-year capital cost recovery period to reflect that the units 
will cease coal combustion by the end of 2028,\101\ we estimate that 
the cost of dry scrubbers at White Bluff Units 1 and 2 is $4,376/ton 
for Unit 1 and $4,129/ton for Unit 2.\102\ As noted in the SIP 
revision, Entergy's August 18, 2017, SO2 BART analysis for 
White Bluff shows that the estimated visibility benefit of dry 
scrubbers for Unit 1 is 0.603 dv at Caney Creek and 0.642 dv at Upper 
Buffalo, and for Unit 2 is 0.574 dv at Caney Creek and 0.632 dv at 
Upper Buffalo.\103\ Although our cost estimates for dry scrubbers are 
more cost-effective than estimated by Entergy, we still consider these 
cost numbers to be on the higher end of what has been found to be cost 
effective in other regional haze actions when also taking into account 
the level of visibility benefit of the controls. We are proposing to 
agree with ADEQ's conclusion that dry scrubbers are not BART for White 
Bluff Units 1 and 2.
---------------------------------------------------------------------------

    \100\ 81 FR 66385; See also ``Response to Comments for the 
Federal Register Notice for the State of Arkansas; Regional Haze and 
Interstate Visibility Transport Federal Implementation Plan,'' pages 
261-263, and 345-349. The FIP Response to Comments document is found 
in the docket at https://www.regulations.gov/document?D=EPA-R06-OAR-2015-0189-0187.
    \101\ We are proposing to agree that it is appropriate to assume 
a capital cost recovery period of 7 years for scrubber controls in 
the BART analysis since Entergy's voluntarily proposed date for 
cessation of coal combustion at White Bluff Units 1 and 2 by the end 
of 2028 has been made enforceable through an Administrative Order. 
The Administrative Order can be found in the Arkansas Regional Haze 
SO2 and PM BART SIP Revision.
    \102\ See Excel spreadsheet titled ``EPA Revised cost 
calcs_WB_Corrected CRF 7 years.xlsx,'' which is found in the docket 
for this proposed rulemaking.
    \103\ See Tables 4-6 and 4-7 of Entergy's August 18, 2017, White 
Bluff SO2 BART analysis.
---------------------------------------------------------------------------

    We are also proposing to agree with ADEQ that the cost of 
compliance, in dollars per ton, for DSI and enhanced DSI is not cost 
effective when the

[[Page 62223]]

remaining useful life of White Bluff Units 1 and 2 is taken into 
account. We are proposing to agree that switching to low sulfur coal 
would result in visibility benefits from the baseline and would be very 
cost-effective. Therefore, we are proposing to approve the state's 
determination that given Entergy's enforceable commitment to cease coal 
combustion at White Bluff Units 1 and 2 by the end of 2028, 
SO2 BART for Units 1 and 2 is an SO2 emission 
limit of 0.60 lb/MMBtu based on switching to low sulfur coal. The 
Administrative Order for the White Bluff units also includes a 
requirement for the source to determine compliance with the 
SO2 emission limits for Units 1 and 2 by using a continuous 
emission monitoring system. These BART requirements are enforceable by 
the state through an Administrative Order that has been adopted and 
incorporated in the SIP revision. We are proposing to approve in the 
SIP the state's Administrative Order, including the 3-year compliance 
date to meet the 0.60 lb/MMBtu emission limit and the requirement for 
Entergy to move forward with its proposed plan to cease coal combustion 
at White Bluff Units 1 and 2 no later than December 31, 2028.\104\ We 
are proposing to find that Entergy's explanation that it cannot ensure 
that White Bluff will receive coal with a low enough sulfur content to 
ensure compliance with the 0.60 lb/MMBtu emission limit until the 
company has had sufficient time to negotiate new contracts and the 
existing coal supply, including the coal for which Entergy is already 
under contract through the year 2020, has been depleted and replaced 
with coal that has a lower sulfur content, is reasonable. Therefore, we 
are proposing to find that a 3-year compliance date for the 0.60 lb/
MMBtu SO2 BART emission limit is appropriate and reasonable. 
We are concurrently proposing to withdraw the FIP's SO2 BART 
requirements for White Bluff Units 1 and 2, as they would be replaced 
by our approval of the state's SO2 BART decision.
---------------------------------------------------------------------------

    \104\ The Administrative Order can be found in the Arkansas 
Regional Haze SO2 and PM BART SIP Revision.
---------------------------------------------------------------------------

b. White Bluff Auxiliary Boiler BART Determinations
    In determining BART for the White Bluff Auxiliary Boiler, ADEQ 
relied on Entergy's October 2013 BART analysis for White Bluff.\105\ In 
the BART analysis, Entergy explained that air dispersion modeling 
demonstrates that the maximum visibility impact predicted from the 
Auxiliary Boiler is 0.036 dv, which it characterized as a very low 
level of visibility impact. The modeling results also show that looking 
at the 98th percentile visibility impacts, the greatest impact from the 
Auxiliary Boiler is 0.01 dv at Caney Creek.\106\ Entergy reasoned that 
since the existing visibility impairment due to the Auxiliary Boiler is 
extremely low, any improvement due to controls are expected to be 
negligible. ADEQ further expanded on this finding by explaining that 
the Arkansas Regional Haze FIP found that due to the small level of 
baseline visibility impairment caused by the Auxiliary Boiler, the 
existing SO2, NOX, and PM emission limitations in 
the Entergy White Bluff permit were determined to satisfy BART for the 
Auxiliary Boiler. ADEQ stated that it agrees that SO2, 
NOX, and PM BART for the Auxiliary Boiler are the existing 
emission limits in the facility's air permit. We are proposing to find 
that the state's SO2, NOX, and PM BART decisions 
for the Auxiliary Boiler are appropriate. The BART Rule provides:
---------------------------------------------------------------------------

    \105\ ``Revised BART Five Factor Analysis White Bluff Steam 
Electric Station Redfield, Arkansas (AFIN 35-00110), dated October 
2013, prepared by Trinity Consultants Inc. in conjunction with 
Entergy Services Inc.'' This BART analysis can be found in Appendix 
D to the Arkansas Regional Haze SO2 and PM BART SIP 
Revision.
    \106\ ``Revised BART Five Factor Analysis White Bluff Steam 
Electric Station Redfield, Arkansas (AFIN 35-00110), dated October 
2013, prepared by Trinity Consultants Inc. in conjunction with 
Entergy Services Inc.,'' see Table 4-4.
---------------------------------------------------------------------------

    ``Consistent with the CAA and the implementing regulations, States 
can adopt a more streamlined approach to making BART determinations 
where appropriate. Although BART determinations are based on the 
totality of circumstances in a given situation, such as the distance of 
the source from a Class I area, the type and amount of pollutant at 
issue, and the availability and cost of controls, it is clear that in 
some situations, one or more factors will clearly suggest an outcome. 
Thus, for example, a State need not undertake an exhaustive analysis of 
a source's impact on visibility resulting from relatively minor 
emissions of a pollutant where it is clear that controls would be 
costly and any improvements in visibility resulting from reductions in 
emissions of that pollutant would be negligible.'' \107\
---------------------------------------------------------------------------

    \107\ 70 FR 39116.
---------------------------------------------------------------------------

    Given the very small baseline visibility impacts from the Auxiliary 
Boiler, we believe it is appropriate to take a streamlined approach for 
determining BART in this case. Because of the very low baseline 
visibility impacts from the Auxiliary Boiler at each modeled Class I 
area, we believe that the visibility improvement that could be achieved 
through the installation and operation of controls would be negligible, 
such that the cost of those controls could not be justified. Therefore, 
we are proposing to approve the state's determination that the existing 
SO2, NOX, and PM emission limitations in the 
Entergy White Bluff permit are BART for the Auxiliary Boiler. 
Specifically, these emission limits are 105.2 lb/hr SO2, 
32.2 lb/hr NOX, and 4.5 lb/hr PM. These BART requirements 
are enforceable by the state through an Administrative Order that has 
been adopted and incorporated in the SIP revision. We are proposing to 
approve into the SIP the state's Administrative Order, including the 
requirement that the White Bluff Auxiliary Boiler comply with BART as 
of the effective date of the Administrative Order, which is August 7, 
2018.\108\ We are concurrently proposing to withdraw the FIP's 
SO2 and PM BART requirements for the Auxiliary Boiler, as 
they would be replaced by our approval of the state's BART decisions.
---------------------------------------------------------------------------

    \108\ The Administrative Order can be found in the Arkansas 
Regional Haze SO2 and PM BART SIP Revision.
---------------------------------------------------------------------------

    We also note that in the Arkansas Regional Haze NOX SIP 
revision, ADEQ erroneously identified the Auxiliary Boiler as 
participating in CSAPR for ozone season NOX, and the state 
elected to rely on participation in that trading program to satisfy the 
Auxiliary Boiler's NOX BART requirements. In a final action 
published in the Federal Register on February 12, 2018, we took final 
action to approve this SIP revision, including reliance on CSAPR for 
ozone season NOX to satisfy the Auxiliary Boiler's 
NOX BART requirements.\109\ Our approval of this 
determination for the Auxiliary Boiler was made in error. Therefore, we 
are proposing to withdraw our prior approval of the state's reliance on 
CSAPR for ozone season NOX to satisfy the NOX 
BART requirement for the Auxiliary Boiler that was included in the 
Arkansas Regional Haze NOX SIP revision submitted to us on 
October 31, 2017. We are proposing to replace our approval of that BART 
finding for the Auxiliary Boiler with approval of the source specific 
32.2 lb/hr NOX BART emission limit contained in the August 
8, 2018, Arkansas Regional Haze SIP revision.
---------------------------------------------------------------------------

    \109\ 83 FR 5927.
---------------------------------------------------------------------------

C. Reasonable Progress Analysis for SO2

    In determining whether additional controls are necessary under the 
reasonable progress requirements and

[[Page 62224]]

thus in establishing RPGs, a state must consider the four statutory 
factors in section 169A(g)(1) of the CAA: (1) The costs of compliance, 
(2) the time necessary for compliance, (3) the energy and nonair 
quality environmental impacts of compliance, and (4) the remaining 
useful life of any existing source subject to such requirements. The 
Regional Haze Rule also states that in establishing the RPGs, the state 
must consider the uniform rate of improvement in visibility for the 
period covered by the implementation plan.\110\ The uniform rate of 
visibility improvement, or uniform rate of progress (URP), needed to 
reach natural conditions by 2064 for each Class I area can be 
determined by comparing baseline conditions with natural conditions. 
The Regional Haze Rule provides for the use of an analytical framework 
that compares the rate of progress that will be achieved by a SIP (as 
represented by the reasonable progress goals for the end of the 
implementation period) to the rate of progress that if continued would 
result in natural conditions in 2064 (i.e., the URP). When a Class I 
area's visibility conditions for the most impaired days are better 
(i.e., less impaired) than the URP, the visibility conditions at the 
Class I areas are said to be ``below the URP line'' or ``below the 
glidepath.''
---------------------------------------------------------------------------

    \110\ 40 CFR 51.308(d)(1)(i)(B).
---------------------------------------------------------------------------

    Consistent with section 169A(b) of the CAA, 40 CFR 51.308(d)(3) 
requires that states include in their SIP a long-term strategy for 
making reasonable progress for each Class I area within their state. 
This long-term strategy is the compilation of all control measures a 
state will use during the implementation period of the specific SIP 
submittal to achieve reasonable progress, and thus to meet any 
applicable RPGs for a particular Class I area. The long-term strategy 
includes control measures determined necessary pursuant to both the 
BART and reasonable progress analyses.
    In the Arkansas Regional Haze SO2 and PM SIP 
revision,\111\ ADEQ noted that EPA's ``Guidance for Setting Reasonable 
Progress Goals under the Regional Haze Program'' \112\ (EPA's RPG 
Guidance), provides that states have flexibility in how to take into 
consideration the four statutory factors. The SIP revision states that, 
considering this guidance, ADEQ believes that the four reasonable 
progress factors can be appropriately applied broadly to a group of 
sources state-wide rather than in a source-specific manner. However, 
ADEQ stated that since EPA evaluated the four factors for controls at 
the Independence facility in the Arkansas Regional Haze FIP as part of 
a source-specific analysis, it determined that application of the four 
factors to that particular source is also ``relevant'' in its 
reasonable progress analysis as a way of addressing EPA's previous 
analysis as reflected in the FIP. Therefore, in addition to considering 
a broader analysis using the four factors, ADEQ also conducted a more 
specific analysis for the Independence facility. The former analysis in 
the SIP is ``broad'' in the sense that it does not quantify costs or 
visibility benefits for any particular source or source category and 
discusses visibility benefits and costs in only qualitative terms. In 
the explanation of its approach, the SIP states that both analyses were 
completed and the results taken into consideration before the state 
determined whether any controls are necessary under reasonable 
progress.
---------------------------------------------------------------------------

    \111\ In a SIP revision submitted on October 31, 2017, Arkansas 
provided a reasonable progress analysis and reasonable progress 
determination with respect to NOX, and we took final 
action to approve the analysis and determination in a final action 
published on February 12, 2018 (see 83 FR 5927). Thus, the Arkansas 
Regional Haze SO2 and PM SIP revision addresses the 
reasonable progress requirements with respect to SO2 and 
PM emissions.
    \112\ 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 EPA 
Regional Administrators, EPA Regions 1-10 (p. 5-1).
---------------------------------------------------------------------------

    Before presenting its broad analysis, the SIP identified the key 
pollutants and source categories that contribute to visibility 
impairment in Arkansas Class I areas. After presenting its broad 
analysis, the SIP presents an evaluation of which sources should be the 
focus of a narrow four-factor analysis and selected Independence as the 
only such source. The identification of the key pollutants and source 
categories that contribute to visibility impairment in Arkansas Class I 
areas, the broad reasonable progress analysis performed by ADEQ, the 
identification of Independence as the only source for which a narrow 
analysis would be performed, and ADEQ's determination regarding 
additional measures for Independence that are necessary for reasonable 
progress are discussed in the subsections that follow. We provide our 
assessment of each component of the reasonable progress section of the 
SIP revision before summarizing and assessing the next component.
1. Arkansas' Discussion of Key Pollutants and Source Category 
Contributions
    As part of its reasonable progress analysis, ADEQ provided a 
discussion of the results of air quality modeling performed by the 
Central Regional Air Planning Association (CENRAP) in support of SIP 
development in the central states region for 2002 and projected 2018 
emissions.\113\ The CENRAP modeling included Particulate Source 
Apportionment Technology Tool (PSAT) with Comprehensive Air Quality 
model with extensions (CAMx) version 4.4, which was used to provide 
source apportionment by geographic regions and major source categories 
for pollutants that contribute to visibility impairment at each of the 
Class I areas in the central states region.\114\ The SIP revision 
provided a discussion of PSAT data for sources region-wide (i.e., 
sources both in and outside Arkansas, including sources in the 
continental U.S. and international sources) as well as a discussion of 
PSAT data for Arkansas sources. Below, we provide a summary of each set 
of PSAT data.
---------------------------------------------------------------------------

    \113\ The central states region includes Texas, Oklahoma, 
Louisiana, Arkansas, Kansas, Missouri, Nebraska, Iowa, Minnesota, 
and the tribal governments within these states.
    \114\ See the TSD for CENRAP Emissions and Air Quality Modeling 
to Support Regional Haze State Implementation, which is found in 
Appendix 8.1 of the 2008 Arkansas Regional Haze SIP. The 2008 
Arkansas Regional Haze SIP can be found in the docket associated 
with this proposed rulemaking.
---------------------------------------------------------------------------

a. Region-Wide PSAT Data for Caney Creek and Upper Buffalo
    Based on the region-wide PSAT data, which looked at sources both in 
and outside Arkansas, it was found that point sources are the primary 
contributor to light extinction at Arkansas' Class I areas on the 20% 
worst days in 2002. Region-wide point sources were found to contribute 
81.04 inverse Megameters (Mm-1) at Caney Creek and 77.8 
Mm-1 at Upper Buffalo on the 20% worst days in 2002, which 
makes up approximately 60% of the total light extinction at each Class 
I area. The region-wide PSAT data showed that area stationary 
anthropogenic sources are the next largest source category contributor 
to light extinction at Arkansas Class I areas, contributing 17.81 
Mm-1 at Caney Creek and 20.46 Mm-1 at Upper 
Buffalo, which makes up approximately 13% and 16% of the total light 
extinction at each Class I area, respectively. The remaining source 
categories (i.e., natural, on-road, and non-road sources) were found to 
each contribute between 2 and 6% of the

[[Page 62225]]

total light extinction at Arkansas Class I areas.
    Based on the region-wide PSAT data, Arkansas also found that 
sulfate (SO4) contributed 87.05 Mm-1 at Caney 
Creek and 83.18 Mm-1 at Upper Buffalo on the 20% worst days 
in 2002, which is approximately 65% and 63% of the total modeled light 
extinction at each Class I area, respectively. Most of the light 
extinction due to SO4 was attributed to point sources. Out 
of the light extinction due to SO4, the point source 
category was responsible for approximately 86 to 87% of that light 
extinction. Point sources of SO4 contributed 75.1 
Mm-1 at Caney Creek and 72.17 Mm-1 at Upper 
Buffalo, or approximately 55 to 56% of the total light extinction at 
Arkansas Class I areas on the 20% worst days in 2002. In contrast, the 
other pollutant species were responsible for a much smaller proportion 
of the total light extinction at Arkansas' Class I areas. For example, 
nitrate (NO3) contributed approximately 10%, primary organic 
aerosols (POA) contributed approximately 8%, elemental carbon (EC) 
contributed approximately 4%, crustal material (CM) contributed 
approximately 3 to 5%, and soil contributed approximately 1% of the 
total modeled light extinction at each Arkansas Class I area on the 20% 
worst days in 2002.
    The region-wide PSAT data also showed that point sources are 
projected to remain the primary contributor to light extinction at 
Arkansas Class I areas, contributing 45.27 Mm-1 at Caney 
Creek and 43.02 Mm-1 at Upper Buffalo on the 20% worst days 
in 2018. This constitutes approximately 53% of the total light 
extinction at Caney Creek and 50% of the total light extinction at 
Upper Buffalo. Area sources are projected to continue to be the second 
largest contributor to light extinction, being responsible for 20% of 
the total light extinction at Caney Creek and 23% of the total light 
extinction at Upper Buffalo. The remaining source categories (i.e., 
natural, on-road, and non-road sources) are projected to continue to 
contribute 5% of the total light extinction at Arkansas Class I areas 
on the 20% worst days in 2018. Based on the region-wide PSAT data, 
light extinction due to SO4 is projected to decrease by 44% 
at Caney Creek and 45% at Upper Buffalo between 2002 and 2018.\115\ 
However, SO4 is projected to continue to be the primary 
driver of total light extinction at Arkansas Class I areas, with point 
sources continuing to be the primary source of light extinction due to 
SO4. Point sources of SO4 are projected to 
contribute 39.83 Mm-1 at Caney Creek and 37.09 
Mm-1 at Upper Buffalo, which is between 43 and 46% of the 
total light extinction on the 20% worst days in 2018.
---------------------------------------------------------------------------

    \115\ The CENRAP's 2018 modeling projections made the following 
regional haze control assumptions for Arkansas' point sources: (1) 
Installation of scrubber controls at Flint Creek Boiler No. 1 to 
meet the presumptive SO2 BART limit of 0.15 lb/MMBtu; (2) 
installation of low NOX burners to satisfy NOX 
BART requirements at Flint Creek Boiler No. 1 and White Bluff Units 
1 and 2; and (3) the shutdown of AECC Bailey Unit 1 and Entergy Lake 
Catherine Unit 4 by 2018. The SIP revision we are proposing to take 
action on requires a more stringent SO2 emission limit 
for Flint Creek Boiler No. 1; requires an interim SO2 
emission limit of 0.60 lb/MMBtu and cessation of coal combustion by 
the end of 2028 at White Bluff Units 1 and 2; requires an 
SO2 emission limit of 0.60 lb/MMBtu for Independence 
Units 1 and 2; does not require the installation of low 
NOX burners for any of Arkansas' EGUs; and does not 
require shutdown of AECC Bailey Unit 1 or Entergy Lake Catherine 
Unit 4.
---------------------------------------------------------------------------

b. Arkansas PSAT Data for Caney Creek and Upper Buffalo
    When looking at the PSAT data for sources within Arkansas only, the 
state found that the relative contribution of sources within Arkansas 
to total light extinction on the 20% worst days at Arkansas Class I 
areas is small. Species attributed to Arkansas sources contributed 
approximately 10% of the total light extinction on the 20% worst days 
in 2002 and were projected to contribute between 13 and 14% of the 
total light extinction on the 20% worst days in 2018. Additionally, the 
state found that when only the visibility impact of sources within 
Arkansas were considered, area sources actually had a larger impact on 
light extinction than point sources. Based on the Arkansas source PSAT 
data, area sources within Arkansas contributed 5.03 Mm-1 at 
Caney Creek on the 20% worst days in 2002, which is approximately 37% 
of the light extinction attributed to Arkansas sources at Caney Creek 
and accounts for 4% of the total light extinction at the Class I area. 
Based on the Arkansas source PSAT data, area sources within Arkansas 
contributed 6.72 Mm-1 at Upper Buffalo on the 20% worst days 
in 2002, which is approximately 50% of the light extinction attributed 
to Arkansas sources at Upper Buffalo and accounts for 5% of the total 
light extinction at the Class I area. In contrast, Arkansas point 
sources contributed 3.85 Mm-1 at Caney Creek on the 20% worst days in 
2002, which is approximately 28% of the light extinction attributed to 
Arkansas sources at Caney Creek and accounts for 3% of the total light 
extinction at the Class I area. Arkansas point sources also contributed 
3.25 Mm-1 at Upper Buffalo on the 20% worst days in 2002, 
which is approximately 24% of the light extinction attributed to 
Arkansas sources and accounts for 2% of the total light extinction at 
the Class I area. The other sources in Arkansas contributed between 7 
and 14% each to light extinction attributed to Arkansas sources, 
accounting for approximately 1% each to the total light extinction at 
each Arkansas Class I area on the 20% worst days in 2002.
    Based on the Arkansas source PSAT data, it was also found that 
SO4 from Arkansas sources (all source categories) 
contributed 4.14 Mm-1 at Caney Creek and 3.97 Mm-1 at Upper 
Buffalo, which is approximately 3% of the total visibility extinction 
at each of the Class I areas on the 20% worst days in 2002. Out of the 
light extinction attributed to SO4 from Arkansas sources, 
the point source category contributed approximately 67% of that light 
extinction at Caney Creek and Upper Buffalo. At Caney Creek, the 
largest contributing pollutant species next to SO4 was POA, 
which contributed approximately 3.54 Mm-1. At Upper Buffalo, 
the largest contributing pollutant species next to SO4 was 
CM, which contributed approximately 3.53 Mm-1. 
NO3 from Arkansas sources was found to contribute 2.11 
Mm-1 at Caney Creek and 1.07 Mm-1 at Upper 
Buffalo, which is approximately 2% and 1% of the of the total light 
extinction at Caney Creek and Upper Buffalo, respectively. On-road 
sources accounted for approximately 50% of the light extinction 
attributed to Arkansas sources of NO3 at Arkansas Class I 
areas.
    The Arkansas source PSAT data also showed that when only sources 
located in Arkansas are considered, area sources are projected to 
remain the primary contributor to light extinction at Arkansas Class I 
areas on the 20% worst days in 2018. Arkansas area sources are 
projected to contribute 4.85 Mm-1 at Caney Creek and 6.52 
Mm-1 at Upper Buffalo on the 20% worst days in 2018, which 
is approximately 43% of light extinction attributed to Arkansas sources 
at Caney Creek and 54% of the light extinction attributed to Arkansas 
sources at Upper Buffalo. In contrast, Arkansas point sources are 
projected to contribute 4.05 Mm-1 at Caney Creek and 3.63 
Mm-1 at Upper Buffalo on the 20% worst days in 2018. 
Arkansas also notes that overall, light extinction attributed to 
Arkansas sources of SO4 is projected to decrease at Arkansas 
Class I areas on the 20% worst days in 2018, but light extinction 
attributed to point sources of SO4 located in Arkansas is 
projected to increase by 4% at Caney Creek and 5% at Upper Buffalo.

[[Page 62226]]

Nevertheless, Arkansas noted that the contribution to total light 
extinction of SO4 from Arkansas point sources is projected 
to be approximately 3% of the total light extinction at each Arkansas 
Class I area on the 20% worst days in 2018, which is a value the state 
considers to be relatively small.
c. Arkansas' Conclusions Regarding Key Pollutants and Source Category 
Contributions
    Based on an assessment of both the region-wide PSAT data and the 
Arkansas source PSAT data, Arkansas identified SO4 as the 
key pollutant species contributing to light extinction at Caney Creek 
and Upper Buffalo. When looking at the region-wide PSAT data, 
SO4 is the pollutant species responsible for the vast 
majority of the visibility impairment at Arkansas Class I areas on the 
20% worst days. When looking at the Arkansas source PSAT data, 
SO4 is still the pollutant species with the largest 
contribution to visibility impairment at Arkansas Class I areas on the 
20% worst days, but its relative contribution to light extinction is 
not as heavily weighted as it is in the region-wide PSAT data. The 
primary driver of SO4 formation at Arkansas Class I areas is 
emissions of SO2 from point sources, both when looking at 
visibility impacts from sources region-wide and also when looking at 
visibility impacts only from sources in Arkansas.
    Arkansas also noted that only a small proportion of total light 
extinction is due to NO3 from Arkansas sources, and that 
this proportion has been driven by on-road sources. For example, 
NO3 from Arkansas point sources contributed less than 0.5% 
of the total light extinction on the 20% worst days at Caney Creek and 
Upper Buffalo. Based on this observation, Arkansas decided not to 
evaluate sources of NO3 under the four reasonable progress 
factors in the October 2017 Arkansas Regional Haze NOX SIP 
Revision. When focusing only on sources in Arkansas, a comparison of 
the various source categories reveals that area sources do contribute a 
larger proportion of total light extinction than the other source 
categories. The majority of the light extinction from Arkansas area 
sources is due to CM and POA, but Arkansas noted that these pollutant 
species originate from many individual small sources and that the cost-
effectiveness of these controls is therefore difficult to quantify and 
Arkansas therefore decided not to evaluate area sources under the four 
reasonable progress factors.
    Since Arkansas determined that SO4 is the key pollutant 
species contributing to light extinction at Caney Creek and Upper 
Buffalo on the 20% worst days and that the majority of light extinction 
due to SO4 is attributed to point sources, it evaluated 
point sources emitting at least 250 tons per year (tpy) of 
SO2 to determine whether their emissions and proximity to 
Arkansas Class I areas warrant further analysis under the four 
reasonable progress factors.
    We agree with Arkansas that the PSAT results for Arkansas sources 
show that the relative contribution to light extinction of 
SO4 on the 20% worst days at Arkansas Class I areas is not 
as great compared to the regional contribution results. However, 
SO4 is still the species with the largest contribution to 
light extinction at Caney Creek and Upper Buffalo on the 20% worst days 
in both the regional data and the Arkansas source PSAT data. We agree 
with Arkansas' identification of SO4 as the key species 
contributing to light extinction at Caney Creek and Upper Buffalo on 
the 20% worst days. Newer IMPROVE monitoring data that has become 
available after the CENRAP modeling was performed does not appear to 
contradict this conclusion.\116\ We are also proposing to agree that 
the primary driver of SO4 formation at Arkansas Class I 
areas is SO2 emissions from point sources, both when looking 
at visibility impacts from sources region-wide and also when looking at 
visibility impacts only from sources in Arkansas. Arkansas' conclusions 
are consistent with our finding in the Arkansas Regional Haze FIP that 
the CENRAP's CAMx modeling shows that SO4 from point sources 
is the driver of regional haze at Caney Creek and Upper Buffalo on the 
20% worst days in both 2002 and 2018.\117\ We also agree with Arkansas' 
assertion that when only sources located in Arkansas are considered, 
light extinction due to area sources (all pollutant species considered) 
is greater compared to the light extinction due to point sources at 
both Caney Creek and Upper Buffalo on the 20% worst days in 2002. And 
we agree with Arkansas that the cost of controlling many individual 
small area sources may be difficult to quantify, and we are therefore 
proposing to find that it is acceptable for Arkansas to choose not to 
further evaluate area sources for controls under reasonable progress in 
this implementation period. This is consistent with EPA's decision not 
to conduct a four-factor analysis of area sources under reasonable 
progress for this implementation period in the Arkansas Regional Haze 
FIP.\118\ Therefore, we are proposing to find that it is appropriate 
for Arkansas to focus its evaluation on point sources emitting at least 
250 SO2 tpy to determine whether their emissions and 
proximity to Arkansas Class I areas warrant further analysis under the 
four reasonable progress factors.
---------------------------------------------------------------------------

    \116\ IMPROVE monitoring data for Caney Creek and Upper Buffalo, 
as well as other Class I areas can be found at http://views.cira.colostate.edu/fed/QueryWizard/Default.aspx.
    \117\ 80 FR 18996.
    \118\ In the FIP we explained that the CENRAP CAMx modeling with 
PSAT showed that point sources are responsible for a majority of the 
light extinction at Arkansas Class I areas on the 20% worst days in 
2002 (this is taking into account all pollutant species and sources 
both in and outside Arkansas). We reasoned that since other source 
types (i.e., natural, on-road, non-road, and area) each contributed 
a much smaller proportion of the total light extinction at each 
Class I area, it was appropriate to focus only on point sources in 
our reasonable progress analysis for this implementation period. See 
80 FR 18944 and 81 FR 66332 at 66336. See also the ``Arkansas 
Regional Haze FIP Response to Comments (RTC) Document,'' pages 71-
99.
---------------------------------------------------------------------------

2. Arkansas' Analysis of Reasonable Progress Factors Broadly Applicable 
to Arkansas Sources
    In addition to the four reasonable progress factors under CAA 
section 169A(g)(1), ADEQ determined that visibility is also a relevant 
factor for consideration in its reasonable progress analysis. ADEQ's 
broad evaluation of the four reasonable progress factors plus 
visibility is summarized below.
    Visibility: ADEQ explained that, since restoring natural visibility 
conditions in Class I areas is the central goal of the regional haze 
program, it considers visibility to be the necessary context within 
which to view whether additional controls are reasonable in the first 
planning period. ADEQ noted that visibility has improved dramatically 
in Arkansas' Class I areas since 2004, with visibility improving at a 
rate more rapid than needed to meet the 2018 point on the URP and 
Arkansas' Class I areas being on track to achieve natural visibility 
conditions in Arkansas Class I areas by 2064. ADEQ also noted that the 
observed improvement in visibility conditions has taken place even 
before implementation of most of the controls included in the Arkansas 
Regional Haze SO2 and PM SIP revision. ADEQ stated that the 
observed visibility improvement at Arkansas Class I areas is the result 
of reductions from state and federal programs, including New Source 
Performance Standards for a variety of source types; vehicle emissions 
standards; changes in NAAQS; innovations in emissions control 
technologies; retirement or reconstruction of older facilities; and 
market-driven changes in electricity generation. ADEQ stated it 
anticipates

[[Page 62227]]

that the implementation of the BART controls required under the SIP 
revision will further keep Arkansas Class I areas on track to achieve 
natural visibility conditions on or before 2064.
    ADEQ also stated that the visibility trajectory in Arkansas' Class 
I areas is a relevant factor for consideration in its reasonable 
progress analysis. According to ADEQ, if Arkansas Class I areas were 
making less progress than necessary to achieve the URP during the first 
planning period, then more costly controls could be warranted if found 
reasonable after consideration of the four statutory factors and other 
factors the state considers relevant. ADEQ stated that ADEQ therefore 
deems it reasonable to consider that Arkansas Class I areas are already 
below the 2018 point on the URP, in addition to considering the 
statutory reasonable progress factors, in evaluating whether additional 
controls are necessary under reasonable progress for the first 
implementation period.
    Costs of Compliance: ADEQ pointed out that EPA's RPG Guidance 
provides that the cost of compliance factor ``can be interpreted to 
encompass . . . the implication of compliance costs to the health and 
vitality of industries within a state.'' \119\ Considering the 
visibility trends at Arkansas' Class I areas, ADEQ determined that this 
interpretation is appropriate to apply in this case. ADEQ believes that 
the cost of additional controls under reasonable progress would create 
a negative impact on the health and vitality of industries within the 
state, and that such adverse impacts would be especially great if 
additional SO2 controls were imposed on the electricity 
sector. This is because under Arkansas law, energy companies are 
permitted to recover costs related to the installation of emissions 
controls at EGUs required under a SIP from electricity ratepayers 
subject to approval by the Arkansas Public Service Commission. These 
costs, in turn, would be allowed to be passed on to Arkansas 
ratepayers, including a variety of industries, in the form of increased 
electric rates. ADEQ believes that energy-intensive industries would be 
disproportionately impacted by these costs.
---------------------------------------------------------------------------

    \119\ 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 EPA 
Regional Administrators, EPA Regions 1-10 (p. 5-1).
---------------------------------------------------------------------------

    Time Necessary for Compliance: ADEQ noted that the time necessary 
for compliance varies depending on the control technology under 
consideration. ADEQ stated that the time necessary for compliance for 
SO2 control technologies considered for BART in the SIP 
revision was typically 3-5 years, unless progress had already been made 
toward implementing those control technologies.
    Energy and Non-air Quality Impacts of Compliance: ADEQ stated that 
the installation of additional controls, such as dry and wet scrubbers, 
under reasonable progress for Arkansas EGUs may have negative impacts, 
including temporary outages necessary to install the controls. Arkansas 
expects that this would temporarily disrupt the supply of electricity 
to the grid. Additionally, ADEQ noted that certain control technologies 
can result in reduced generating capacity for EGUs, which is referred 
to as parasitic load.
    Furthermore, ADEQ noted that market trends for coal and natural gas 
have already resulted in the decreased dispatch of coal-fired 
facilities, which has in turn resulted in a decrease in overall 
emissions of key pollutants that impact visibility at Arkansas Class I 
areas. ADEQ cited to data from the Energy Information Administration 
showing that the trend of decreased net electricity generation from 
coal and increased net electricity generation from natural gas and 
renewable energy is expected to continue for the remainder of the 2008-
2018 implementation period, and well beyond.
    Remaining Useful Life of Potentially Affected Sources: ADEQ pointed 
out that the EPA RPG Guidance provides that this factor is generally 
best treated as one element of the overall cost analysis. ADEQ noted 
that if the remaining useful life for a given facility is less than the 
typical amortization period for new control equipment, the annualized 
cost increases and the controls become less cost effective. 
Additionally, ADEQ pointed out that the cost of controls may result in 
a company making an economic decision to discontinue operations, thus 
truncating the remaining useful life of a source.
3. Identification of Potential Sources for Evaluation of SO2 
Controls Under Reasonable Progress
    In identifying which sources to evaluate for SO2 
controls in its reasonable progress analysis, Arkansas compiled a list 
of all point sources that emitted at least 250 SO2 tpy as 
reported to the EPA emissions Inventory System (EIS) in any given year 
between 2002 and 2015. For sources that participate in EPA's Acid Rain 
Program, Arkansas obtained SO2 emissions data for 2015 using 
the Air Markets Program Data tool. Arkansas then narrowed down the list 
to only those sources that emitted at least 250 tpy averaged over the 
most recent 3-year period for which data is available. Arkansas 
identified 11 sources that met this criterion (see Table 11).

 Table 11--Point Sources in Arkansas With SO2 Emissions Greater Than 250
                                   tpy
------------------------------------------------------------------------
                                                            Average SO2
                                          Most recent 3-     emissions
                Facility                    year period        (tpy)
 
------------------------------------------------------------------------
Entergy White Bluff *...................       2014-2016          24,346
Entergy Independence....................       2014-2016          22,531
SWEPCO Flint Creek Power Plant *........       2014-2016           5,350
Plum Point Energy Station Unit 1........       2014-2016           2,759
FutureFuel Chemical Company.............       2013-2015           2,837
Domtar A.W. LLC, Ashdown Mill *.........       2013-2015           1,553
Evergreen Packaging--Pine Bluff.........       2013-2015             986
Albemarle Corporation--South Plant......       2013-2015           1,382
SWEPCO John W. Turk Jr. Power Plant.....       2014-2016             908
Ash Grove Cement Company/Foreman Cement        2013-2015             369
 Plant..................................
Nucor--Yamato Steel Company.............       2013-2015             301
------------------------------------------------------------------------
*These facilities are subject to BART requirements, and the state
  therefore did not further consider these sources for additional
  controls under reasonable progress.

[[Page 62228]]

    Arkansas explained that, since White Bluff, Flint Creek, and Domtar 
are subject to BART and the BART analyses conducted to determine BART 
control requirements are based on an assessment of many of the same 
factors that must be evaluated in determining whether additional 
controls are needed under the reasonable progress provisions and thus 
in establishing the RPGs, no additional controls under reasonable 
progress are necessary for these sources in the first implementation 
period. For the remaining sources on the list, Arkansas calculated the 
total average actual emission rate (Q) in SO2 tpy over the 
most recent 3-year period and determined the distance (D) in kilometers 
of each source to its closest Class I area (see Table 12). Arkansas 
used a ``Q divided by D'' (Q/D) value of 10 as a threshold for 
identifying sources to further evaluate for reasonable progress 
controls. Arkansas explained that it selected this value as a threshold 
based on guidance contained in the BART Guidelines and also noted that 
this is consistent with the approach used in other regional haze 
actions.

      Table 12--Q/D Values for Large SO2 Point Sources in Arkansas
------------------------------------------------------------------------
                                                     Q/D value
                Facility                 -------------------------------
                                           Upper buffalo    Caney creek
------------------------------------------------------------------------
Entergy Independence....................             126              81
Plum Point Energy Station Unit 1........               9               7
FutureFuel Chemical Company.............              17              10
Evergreen Packaging--Pine Bluff.........               4               5
Albemarle Corporation--South Plant......               5               9
SWEPCO John W. Turk Jr. Power Plant.....               4              11
Ash Grove Cement Company/Foreman Cement                1               5
 Plant..................................
Nucor--Yamato Steel Company.............               1               1
------------------------------------------------------------------------

    As shown in Table 12, Arkansas found that only three sources had a 
maximum Q/D value greater than or equal to 10: Entergy Independence, 
FutureFuel Chemical Company, and John W. Turk Jr. Power Plant. Arkansas 
noted that Entergy Independence is the second largest point source of 
SO2 emissions in Arkansas, with average 2014-2016 emissions 
of 22,531 SO2 tpy. In comparison, the FutureFuel Chemical 
Company and the John W. Turk Jr. Power Plant had much lower 
SO2 emissions. FutureFuel Chemical Company had average 2013-
2015 SO2 emissions of 2,837 tpy, while the John W. Turk Jr. 
Power Plant had average 2014-2016 SO2 emissions of 908 tpy. 
Arkansas noted that SO2 emissions from the FutureFuel 
Chemical Company and the John W. Turk Jr. Power Plant are approximately 
an order of magnitude lower than emissions from Entergy Independence. 
In addition, Arkansas noted that the FutureFuel Chemical Company was 
previously identified as a BART eligible source, but was determined to 
be not subject to BART in the 2008 Arkansas Regional Haze SIP based on 
CALPUFF modeling performed in the development of that SIP. Therefore, 
ADEQ did not find it necessary to further evaluate controls under 
reasonable progress for this facility for this implementation period. 
The John W. Turk Jr. Power Plant, which began operation in 2012, has 
implemented best available control technology, which Arkansas noted is 
more stringent than BART. Therefore, ADEQ stated that it does not 
anticipate that more stringent controls would be available and/or 
reasonable for this facility in the first implementation period. 
Arkansas ultimately determined that since the Independence facility is 
a source not subject to BART and because it was required by the 
Arkansas Regional Haze FIP to install controls under reasonable 
progress, this particular source warrants further consideration and 
evaluation under the four reasonable progress factors.
    We are proposing to find that Arkansas' overall method of 
identifying sources for potential further evaluation under the four 
reasonable progress factors is appropriate. We find that Arkansas' 
approach of narrowing down the list of sources to further evaluate 
under reasonable progress to only those sources that emitted at least 
250 SO2 tpy averaged over the most recent 3-year period for 
which data is available is reasonable. We agree with Arkansas that 
since White Bluff and Flint Creek are subject to BART and are addressed 
under this SIP revision, the BART analyses conducted to determine BART 
control requirements for these sources and the determinations adopted 
and incorporated by the state in this SIP revision are adequate to 
eliminate these sources from further consideration of additional 
controls under the reasonable progress requirements for the first 
implementation period. The EPA RPG Guidance explains that the BART 
analysis is based, in part, on an assessment of many of the same 
factors that must be addressed in establishing the RPGs, and therefore 
it is reasonable to conclude that any control requirements imposed in 
the BART determination also satisfy the RPG-related requirements for 
source review in the first implementation period.\120\ The guidance 
provides that it is reasonable to conclude that any control 
requirements imposed in the BART determination also satisfy the RPG-
related requirements for source review in the first RPG planning 
period.\121\ The same rationale applies for the Domtar Ashdown Mill, 
although the August 8, 2018 SIP revision does not address the BART 
requirements for Domtar, which will remain satisfied by the FIP and the 
2008 Arkansas Regional Haze SIP. Based on the consideration of the BART 
factors and resulting determinations in that FIP and the 2008 Arkansas 
Regional Haze SIP, it is reasonable for ADEQ to conclude that nothing 
further is needed to address emissions from Domtar under the 
requirement for reasonable progress analysis at this time. If ADEQ 
chooses to submit a SIP revision to address BART requirements for 
Domtar Power Boilers No. 1 and No. 2, we will evaluate that SIP 
submittal, including whether it also sufficiently addresses the 
reasonable progress requirements for Domtar for the first 
implementation period.
---------------------------------------------------------------------------

    \120\ 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 EPA 
Regional Administrators, EPA Regions 1-10 (pp. 4-2, 4-3, and 5-1).
    \121\ Id.
---------------------------------------------------------------------------

    We are proposing to find that Arkansas' use of a Q/D value of 10 as 
a threshold for identifying sources to further evaluate for reasonable 
progress controls is reasonable and appropriate. We agree with 
Arkansas, that the FutureFuel Chemical Company was

[[Page 62229]]

found by the state to be not subject to BART in the 2008 Arkansas 
Regional Haze SIP, which is a determination that was approved by EPA in 
our March 2012 final action on the SIP.\122\ The FutureFuel Chemical 
Company and the John W. Turk Jr. Power Plant are the fifth and ninth 
largest SO2 point sources in Arkansas, based on average 
annual emissions from the most recent 3-year period.\123\ In comparison 
to the SO2 emissions from the 3 largest SO2 point 
sources in Arkansas, emissions from these two facilities are relatively 
small.\124\ Taking into consideration the significantly lower 3-year 
average SO2 emissions from the FutureFuel Chemical Company 
and the John W. Turk Jr. Power Plant in comparison to the Independence 
Power Plant and considering that the John W. Turk Jr. Power Plant 
operates best available control technology, we are proposing to find 
that it is reasonable and appropriate for Arkansas to not further 
evaluate these sources for controls under reasonable progress for this 
planning period. We also consider it appropriate and reasonable for 
Arkansas to decide to conduct an analysis of the reasonable progress 
factors for the Independence facility. In particular, we consider it 
appropriate to evaluate the Independence facility because it is the 
second highest point source of SO2 emissions in Arkansas, 
accounting for approximately 36% of the SO2 point source 
emissions in Arkansas; its Q/D values as determined by ADEQ are high 
(see Table 12), especially when compared to other Arkansas point 
sources; and it is a source not subject to BART. Therefore, we are 
proposing to agree with Arkansas' decision to evaluate the four 
reasonable progress factors for the Independence facility.
---------------------------------------------------------------------------

    \122\ The 2008 Arkansas Regional Haze SIP showed that FutureFuel 
Chemical Company had a maximum visibility impact (i.e., 1st high 
value) of 0.711 dv at Hercules Glades. EPA found that closer 
inspection of the visibility modeling results revealed that only 
this single day out of the 3 years modeled exceeded the 0.5 dv 
threshold used by ADEQ to determine if a source is subject to BART. 
Since only one day modeled above the threshold, EPA found in its 
final action on the 2008 Arkansas Regional Haze SIP that it is 
unlikely that a refined modeling approach using updated 
meteorological data, which would allow the use of the 98th 
percentile visibility impact instead of the max visibility impact, 
would show impacts above the 0.5 dv threshold. Therefore, EPA 
concluded in our March 2012 final action on the 2008 Arkansas 
Regional Haze SIP that it was not necessary to further evaluate 
controls under reasonable progress for the FutureFuel Chemical 
Company in the first implementation period.
    \123\ See the Arkansas Regional Haze SO2 and PM SIP 
Revision, Table 11.
    \124\ The three largest SO2 point sources in 
Arkansas, based on average annual emissions from the most recent 3-
year period, are the Entergy White Bluff Plant, Entergy Independence 
Plant, and SWEPCO Flint Creek Plant (see Table 11 of the Arkansas 
Regional Haze SO2 and PM SIP Revision). The Entergy White 
Bluff Plant and the SWEPCO Flint Creek Plant are subject to BART and 
controls for these facilities are already addressed in the SIP 
revision based on ADEQ's consideration of the 5 BART factors.
---------------------------------------------------------------------------

4. Arkansas' Reasonable Progress Analysis for Independence Units 1 and 
2
    As noted above, ADEQ determined that application of the four 
factors to that specific source is also ``relevant'' in its reasonable 
progress analysis as a way of addressing EPA's previous analysis.
a. Arkansas' Evaluation of the Reasonable Progress Factors for 
SO2 for Entergy Independence Units 1 and 2
    Section 169(A)(g)(1) of the CAA requires states to evaluate the 
costs of compliance, the time necessary for compliance, the energy and 
non-air quality environmental impacts of compliance, and the remaining 
useful life of any potentially affected sources, when determining 
reasonable progress. In its evaluation of the four reasonable progress 
factors for the Independence facility, Arkansas relied on information 
provided by Entergy for the Independence facility in the evaluation of 
low sulfur coal and dry scrubbers. Arkansas also relied on data 
developed by EPA in support of the Arkansas Regional Haze FIP in the 
evaluation of wet scrubbers and dry scrubbers. The Entergy Independence 
Power Plant is a coal-fired electric generating station with two 
identical 900 MW boilers. The boilers burn Wyoming Powder River Basin 
sub-bituminous coal as their primary fuel and No. 2 fuel oil or bio-
diesel as start-up fuel. The layout and boiler units at this facility 
are similar to those at Entergy White Bluff, but since the units at 
Independence were installed in 1983 (9 years after the installation of 
the White Bluff units), Independence Units 1 and 2 are not BART 
eligible.
    There is currently no SO2 control equipment in use at 
Units 1 and 2. Arkansas noted that the Independence units are subject 
to a prevention of significant deterioration (PSD) emission limit of 
0.93 lb/MMBtu. Arkansas also noted that market trends for coal and 
natural gas have resulted in decreased dispatch of the Independence 
units, which has resulted in reduced emissions from the facility. The 
available SO2 control technology options considered in 
Arkansas' analysis are as follows: Switching to coal with a lower 
sulfur content, dry FGD, and wet FGD, all of which Arkansas identified 
as being technically feasible. Switching to coal with a sulfur content 
of 0.6 lb/MMBtu (referred to herein as low sulfur coal) is expected to 
result in a 4 to 6% reduction in SO2 emissions from 2009-
2013 levels. Dry FGD systems typically have SO2 control 
efficiencies ranging from 60 to 95% control, while wet FGD is typically 
capable of achieving 80 to 95% control of SO2 emissions.
    Degree of Improvement in Visibility: Although the degree of 
visibility improvement is not one of the four statutory factors that 
must be evaluated in a reasonable progress analysis, as noted above, 
Arkansas chose to consider visibility improvement since the ultimate 
goal of any controls under reasonable progress is to achieve visibility 
improvements. For switching to low sulfur coal, Entergy submitted 
CALPUFF modeling that estimated the visibility benefit of switching to 
low sulfur coal for Independence Units 1 and 2. This modeling showed 
that switching to low sulfur coal is anticipated to result in 
visibility improvements of 0.112 dv at Caney Creek and 0.236 dv at 
Upper Buffalo. For dry scrubbers, Arkansas relied on the visibility 
improvement estimates from the modeling conducted by EPA for the 
Arkansas Regional Haze FIP. Arkansas noted that the installation of dry 
FGD at Independence Units 1 and 2 is anticipated to result in 
visibility improvements of 1.096 dv at Caney Creek and 1.178 dv at 
Upper Buffalo.\125\ As discussed above, Arkansas also estimated that 
the cost in terms of dollars per deciview of dry FGD at Independence 
Units 1 and 2 ranges from $63,580,175/dv to $71,672,197/dv at each of 
the four affected Class I areas (see Table 13).
---------------------------------------------------------------------------

    \125\ We note that in the SIP revision, ADEQ relied on EPA's 
visibility modeling from the FIP for dry scrubbers at the 
Independence facility. In that visibility modeling, EPA modeled two 
baseline scenarios: (1) The BASE case emission rates for 
NOX and SO2 were from the maximum actual 24-
hour emissions during the 2001-2003 period; and (2) the BASE 2 case 
emission rates for SO2 were based on the maximum actual 
24-hour emissions during the 2001-2003 period and the NOX 
emissions were based on the maximum 24-hour emissions during the 
2011-2013 period. Entergy's CALPUFF modeling for low sulfur coal at 
the Independence facility was based on a 2011-2013 baseline period 
for modeled emission rates. While Entergy's baseline for low sulfur 
coal differed from the two baselines modeled by EPA for dry 
scrubbers, ADEQ stated they do not expect that the difference would 
substantially impact the comparison of the visibility benefits among 
controls evaluated.
---------------------------------------------------------------------------

    Remaining Useful Life: Since there are no state- or federally-
enforceable limitations on continued operations at the Independence 
facility, Arkansas' cost analysis for SO2 controls assumed a 
30-year amortization period for dry

[[Page 62230]]

FGD and wet FGD.\126\ However, Arkansas acknowledged Entergy's 
intention, as stated in comments to Arkansas regarding the draft SIP, 
to cease coal combustion at Independence Units 1 and 2 by the end of 
2030. In addition, Arkansas noted that market pressures may also impact 
continued operations at the Independence facility, including changes in 
dispatch and economic decisions concerning the continued viability of 
the units. Therefore, Arkansas recognized that the amortization period 
of controls may end up being less than the 30 years assumed in 
Arkansas' cost analysis, potentially resulting in the controls being 
less cost effective than estimated in the analysis.
---------------------------------------------------------------------------

    \126\ As explained above, Entergy annualized the capital cost of 
controls on the Independence facility assuming a 9-year amortization 
period, based on Entergy's plans for ceasing coal combustion at 
Independence by the end of 2030. However, given that Entergy's plans 
to cease coal combustion by the end of 2030 are not state or 
federally-enforceable, ADEQ re-calculated the cost-effectiveness of 
controls by annualizing the capital cost of controls assuming a 30-
year amortization period.
---------------------------------------------------------------------------

    Costs of Compliance: In considering the costs of compliance, 
Arkansas noted that switching to low sulfur coal has no associated 
capital costs, but there would be a cost associated with guaranteeing 
that the sulfur content remains below 0.6 lb/MBtu. Arkansas stated it 
calculated cost estimates for switching to low sulfur coal using 
information provided by Entergy regarding cost premiums for low sulfur 
coal, U.S. Energy Information Administration fuel consumption data, and 
EPA Air Markets Program Data. Arkansas estimated that the annualized 
operation and maintenance costs of switching to low sulfur coal is $1.6 
million for Unit 1 and $1.7 million for Unit 2.\127\ Arkansas estimated 
that the cost effectiveness of switching to low sulfur coal is 
approximately $2,437/ton for Unit 1 and $2,345/ton for Unit 2.
---------------------------------------------------------------------------

    \127\ ADEQ calculated annualized operation and maintenance costs 
of switching to low sulfur coal by multiplying average annual fuel 
consumption in tons for the years 2009-2013 by the $0.50/ton cost 
premium Entergy was quoted by its coal supplier, per Entergy's 
August 18, 2017, SO2 BART analysis for White Bluff. ADEQ 
obtained annual fuel consumption data for the years 2009-2013 from 
U.S. Energy Information Administration Form EIA-923.
---------------------------------------------------------------------------

    In contrast to switching to low sulfur coal, the installation of 
dry FGD and wet FGD is expected to require a large capital investment. 
Entergy provided Arkansas with Independence-specific cost estimates for 
dry scrubbers for use in Arkansas' cost analysis. Entergy estimated 
total capital costs of dry scrubbers at Independence to be $491,893,500 
per unit based on ``actual costs'' and $355,391,500 per unit based on 
costs allowed under EPA's Control Cost Manual. Entergy annualized the 
capital cost for both sets of numbers assuming a 9-year amortization 
period, based on Entergy's plans to cease coal combustion at 
Independence by the end of 2030. Additionally, Entergy based its 
calculations of SO2 emissions reductions based on a 2009-
2013 baseline. In the SIP revision, ADEQ based its evaluation of the 
cost of dry scrubbers on the set of capital costs that reflect the 
costs allowed under EPA's Control Cost Manual, and also assumed a 30-
year amortization period in its calculation of the cost-effectiveness 
of dry scrubbers. Based on these assumptions, Arkansas estimated that 
the cost-effectiveness of dry scrubbers is $2,970/ton for Unit 1 and 
$2,742/ton for Unit 2.
    Since Entergy did not provide Independence-specific cost estimates 
for wet scrubbers for Arkansas to base its cost analysis on, Arkansas 
relied on the cost estimates for Independence developed by EPA in the 
Arkansas Regional Haze FIP.\128\ Based on a 30-year amortization 
period, our FIP estimated wet FGD to cost $3,706/ton at Unit 1 and 
$3,416/ton at Unit 2. Arkansas noted that in the Arkansas Regional Haze 
FIP, EPA eliminated wet scrubbers due to the high incremental cost-
effectiveness but small incremental visibility benefit of wet scrubbers 
compared to dry scrubbers. Therefore, consistent with EPA's action in 
the FIP, ADEQ found that wet FGD did not warrant further consideration 
in its analysis.
---------------------------------------------------------------------------

    \128\ See 80 FR 18992-18993. See also the Arkansas Regional Haze 
SO2 and PM SIP Revision, Appendix F.
---------------------------------------------------------------------------

    In addition to considering cost-effectiveness calculations in the 
cost analysis, Arkansas found that other cost-related factors were of 
relevance in its evaluation of the reasonable progress factors for the 
Independence facility. This includes total capital costs, cost to 
Arkansas communities, and the cost in terms of dollar per dv 
improvement in visibility anticipated from the control options 
evaluated ($/dv). Arkansas considered the capital costs of dry 
scrubbers and wet scrubbers to be high, even though the costs in terms 
of $/ton of SO2 emissions reduced for both dry and wet 
scrubbers (assuming a 30-year remaining useful life) are within a range 
that has been found to be cost effective in other regional haze 
actions. In addition, acknowledging Entergy's anticipated cessation of 
coal combustion at the Independence facility, although it is not state- 
or federally-enforceable, Arkansas noted that assuming a 9-year 
remaining useful life would likely result in scrubber controls no 
longer being cost-effective. In light of this, Arkansas considered it 
important to take into account the capital cost of controls along with 
the cost-effectiveness in terms of dollars per ton of emissions 
reduced. Arkansas also noted that these costs would be passed on to 
Arkansas ratepayers. Finally, Arkansas also took into account that the 
$/dv improvement in visibility for dry scrubbers is a little over 2 
times higher than for low sulfur coal at Caney Creek and between 5 and 
6 times higher at Upper Buffalo and the 2 Missouri Class I areas (see 
Table 13). Arkansas noted that consideration of the cost in terms of $/
dv improvement demonstrates a greater disparity in costs among the 
control options compared to consideration of the cost in terms of $/ton 
reduced. Arkansas concluded that all the control options considered 
would result in millions of dollars spent to achieve what it considers 
to be little visibility benefit.

                      Table 13--Cost of SO2 Controls ($/dv) for Independence Units 1 and 2
----------------------------------------------------------------------------------------------------------------
                                                                           Class I Area
                                                 ---------------------------------------------------------------
               SO2 control option                                                    Hercules
                                                    Caney Creek    Upper Buffalo      Glades           Mingo
----------------------------------------------------------------------------------------------------------------
Low Sulfur Coal.................................     $29,469,780     $10,929,190     $13,985,658     $12,179,393
Dry FGD.........................................      68,337,085      63,580,175      70,925,611      71,672,197
----------------------------------------------------------------------------------------------------------------

    Time Necessary for Compliance: Arkansas explained that the typical 
time necessary for compliance for dry FGD and wet FGD is 5 years. 
Considering the time left on existing coal supply contracts between 
Entergy and its coal

[[Page 62231]]

supplier, the time required to burn through current fuel stocks, and 
the time needed to build a stockpile of low sulfur coal to assure 
against potential fuel supply disruptions, Entergy informed Arkansas 
that the time necessary to comply with an SO2 emission limit 
based on low sulfur coal is estimated to be 3 years.
    Energy and Non-air Quality Environmental Impacts of Compliance: 
Arkansas noted that dry FGD utilizes lime slurry to remove 
SO2 from flue gas and that in the process, particulate 
matter is generated that must be controlled through the use of a 
baghouse or ESP. Once collected, the waste material is disposed of 
through landfilling. Arkansas noted that the costs associated with 
control of particulate matter and additional power requirements were 
factored into the cost estimates used in its analysis. Arkansas 
determined that Entergy has not indicated unusual circumstances that 
would create greater problems than experienced in other cases where dry 
FGD has been utilized to meet regional haze requirements. Arkansas also 
noted that switching to low sulfur coal is not anticipated to result in 
any adverse energy or non-air environmental impacts.
b. Arkansas' Determination Regarding Reasonable Progress Requirements 
for Independence
    Based on its evaluation of the reasonable progress factors for the 
Independence facility, ADEQ arrived at the conclusion that no 
additional controls are necessary for reasonable progress during the 
first implementation period. According to ADEQ, the controls it 
evaluated would cost millions of dollars annually, which would be 
passed on to Arkansas ratepayers, for what ADEQ considers to be little 
visibility benefit when Arkansas' Class I areas are already making more 
progress than the URP.
    Although ADEQ concluded that none of the controls evaluated for the 
Independence facility are necessary for achieving reasonable progress 
in the first planning period, ADEQ acknowledged Entergy's intention to 
switch to low sulfur coal at Independence Units 1 and 2 within the next 
3 years. ADEQ noted that this measure would strengthen the SIP and 
result in some visibility benefit at Arkansas' Class I areas, while 
having no associated capital costs. According to ADEQ, the lack of any 
capital costs will provide Entergy with flexibility regarding the 
company's planned cessation of coal combustion at the Independence 
facility by the end of 2030. Therefore, Entergy's commitment to switch 
to low sulfur coal at Independence Units 1 and 2 has now been made 
enforceable by ADEQ as part of the long-term strategy for this 
implementation period, through an Administrative Order that has been 
adopted and incorporated in the SIP revision. The Administrative Order 
requires Independence Units 1 and 2 to meet an SO2 emission 
limit of 0.60 lb/MMBtu no later than 3 years from the effective date of 
the Administrative Order, which is August 7, 2018.\129\
---------------------------------------------------------------------------

    \129\ The Administrative Order can be found in the Arkansas 
Regional Haze SO2 and PM BART SIP Revision.
---------------------------------------------------------------------------

5. Arkansas' Determination Regarding Additional Controls Necessary 
Under Reasonable Progress and Revised RPGs
    After consideration of the statutory reasonable progress factors, 
along with an evaluation of the monitored trajectory of visibility 
impairment during the first implementation period, particulate source 
apportionment data, and SO2 emissions relative to proximity 
to Arkansas Class I areas, Arkansas determined that no additional 
controls beyond BART and other Clean Air Act programs are necessary 
under the reasonable progress provisions for the first implementation 
period. Based on its analysis of the reasonable progress factors in the 
context of both the analysis of a group of sources as well as the 
source-specific analysis that applied the reasonable progress factors 
specifically to the Independence facility, Arkansas determined that all 
the evaluated controls would result in the expenditure of millions of 
dollars annually for what the state considers to be little visibility 
benefit. In addition, the costs of any control requirements would be 
passed on to Arkansas citizens and businesses through electricity rate 
increases. Arkansas deems that these costs are not warranted under 
reasonable progress given that Arkansas Class I areas are well below 
their respective 2018 URPs. Arkansas believes that its reasonable 
progress determination is consistent with EPA's decision to establish a 
64-year lifespan for the regional haze program, which is broken down 
into several 10-year implementation periods. Arkansas stated that the 
way the regional haze program was set up allows for a fresh look at the 
changing landscape of sources that impact visibility and potential 
controls every 10 years. Arkansas noted that the EPA Reasonable 
Progress Guidance provides that it is reasonable for states to defer 
reductions to later planning periods in order to maintain a consistent 
glidepath toward the long-term goal of natural visibility conditions. 
Therefore, Arkansas determined that no SO2 or PM controls 
beyond BART are necessary for reasonable progress during the first 
implementation period.
    To reflect the control measures required in the Arkansas Regional 
Haze SO2 and PM SIP revision and the Arkansas Regional Haze 
NOX SIP revision, which was approved by EPA in a prior 
action,\130\ Arkansas revised the RPGs for the 20% worst days for Caney 
Creek and Upper Buffalo that it had previously established in the 2008 
Arkansas Regional Haze SIP. Arkansas did not revise its RPGs for the 
20% best days included in the 2008 Arkansas Regional Haze SIP. In order 
to provide RPGs for the 20% worst days that account for emissions 
reductions from its SIP revisions, Arkansas utilized a method that is 
based on a scaling of modeled light extinction components in proportion 
to emissions changes anticipated from SIP controls for which compliance 
is required on or before December 31, 2018. Arkansas noted that this is 
the same method utilized by EPA to revise the RPGs in the Arkansas 
Regional Haze FIP. Arkansas scaled CENRAP's CAMx 2018 projection of 
light extinction components for SO4 and NO3 in 
proportion to the SIP revisions' emission reductions for SO2 
and NOX from the CENRAP modeled 2018 emissions. Arkansas 
decided to use the most recent 3 years of data (2014-2016) as opposed 
to EPA's method in the Arkansas FIP, which involved using the 5 most 
recent years of data (2009-2013) with the exclusion of the minimum and 
maximum values. Arkansas explained that this was done to ensure that 
recent changes in dispatch at Arkansas EGUs were captured. Arkansas' 
revised RPGs for Caney Creek and Upper Buffalo are presented in Table 
14.
---------------------------------------------------------------------------

    \130\ 83 FR 5927.

 Table 14--Arkansas' Revised 2018 RPGs for Caney Creek and Upper Buffalo
------------------------------------------------------------------------
                                                           2018 RPG 20%
                      Class I area                          worst days
                                                               (dv)
------------------------------------------------------------------------
Caney Creek.............................................           22.47
Upper Buffalo...........................................           22.51
------------------------------------------------------------------------

6. EPA's Evaluation and Conclusions on Arkansas' Reasonable Progress 
Analysis and Revised RPGs
    As noted above, as part of its reasonable progress analysis, 
Arkansas

[[Page 62232]]

conducted both a broad source analysis and a source-specific analysis 
that evaluated the four statutory factors for the Independence 
facility. The former analysis was ``broad'' in the sense that it did 
not quantify costs or visibility benefits for any particular source or 
source category, and discussed anticipated visibility benefits and 
costs in only general terms. We agree that an approach that involves a 
broad analysis of groups of sources or source categories may be 
appropriate in certain cases, as provided by EPA's RPG Guidance. 
However, we believe that the broad analysis of a group of sources 
provided by ADEQ does not clearly identify what sources or controls 
were evaluated in the state's weighing of the costs and other statutory 
factors. While informative, we find that the state's broad analysis of 
a group of sources was not a determinative component of the state's 
reasonable progress analysis given that the state's determination was 
also informed by an evaluation of large point sources individually to 
identify sources for potential further evaluation under the four 
reasonable progress factors and by a more narrow and focused analysis 
conducted for those sources identified, specifically the Independence 
facility, which included consideration of various control options and 
weighing of costs and the other statutory factors.
    We are proposing to find that the reasonable progress requirements 
under section 51.308(d)(1) have been fully addressed for the first 
regional haze planning period. Specifically, we are proposing to find 
that the following components of Arkansas' analysis satisfy the 
reasonable progress requirements: Arkansas' discussion of the key 
pollutants and source categories that contribute to visibility 
impairment in Arkansas Class I areas based on the CENRAP's source 
apportionment modeling; the identification of a group of large 
SO2 point sources for potential consideration of controls 
under reasonable progress and the eventual narrowing down of the list 
to the Independence facility; \131\ and the evaluation of the four 
reasonable progress factors for SO2 controls on the 
Independence facility.
---------------------------------------------------------------------------

    \131\ As explained elsewhere in this notice, ADEQ relied on the 
fact that a FIP is in place to satisfy the BART requirements for the 
Domtar Ashdown Mill to find that nothing further is needed to 
address the reasonable progress requirements with regard to this 
source for the first implementation period. EPA is proposing to 
agree that it is appropriate to rely on the FIP in this manner.
---------------------------------------------------------------------------

    We are proposing to agree with Arkansas' cost analysis for dry 
scrubbers and switching to low sulfur coal for Independence Units 1 and 
2, and with the state's decision to assume a 30-year capital cost 
recovery period in the cost analysis. It is appropriate to assume a 30-
year capital cost recovery period in the cost analysis since Entergy's 
plans to cease coal combustion at the Independence facility are not 
state or federally-enforceable. We also agree with Arkansas' estimates 
of the cost of dry scrubbers, and note that the state's estimates of 
the cost effectiveness of dry scrubbers for Units 1 and 2 are very 
similar to the cost effectiveness estimates we developed in the 
Arkansas Regional Haze FIP.\132\
---------------------------------------------------------------------------

    \132\ Compare Arkansas' estimates of the cost effectiveness of 
dry scrubbers for the Independence facility ($2,970/ton for Unit 1 
and $2,742/ton for Unit 2) with EPA's estimates of the cost 
effectiveness of dry scrubbers for the facility ($2,853/ton for Unit 
1 and $2,634/ton for Unit 2). See 81 FR 66352.
---------------------------------------------------------------------------

    Since the White Bluff and Independence facilities are sister 
facilities with nearly identical units and comparable levels of annual 
SO2 emissions, and since both DSI and enhanced DSI were 
evaluated in the BART analysis for White Bluff Units 1 and 2, we 
believe it would be appropriate to consider these controls in the four-
factor analysis for the Independence facility as well. However, neither 
the SIP revision nor Entergy's four factor analysis for controls on the 
Independence facility considered DSI or enhanced DSI as control 
options. Therefore, relying on Entergy's estimates of the capital costs 
and annual operation and maintenance costs for DSI and enhanced DSI for 
White Bluff Units 1 and 2 from Entergy's August 18, 2017, White Bluff 
BART analysis,\133\ and assuming a 30-year equipment life, we estimate 
the cost-effectiveness of DSI at the Independence facility to be 
approximately $4,963/SO2 ton removed for Unit 1 and $4,593/
SO2 ton removed for Unit 2.\134\ We estimate the cost-
effectiveness of enhanced DSI to be approximately $4,951/SO2 
ton removed for Unit 1 and $4,581/SO2 ton removed for Unit 
2.\135\ Based on our cost estimates for DSI, we find that DSI is less 
cost-effective than dry scrubbers or wet scrubbers for Independence 
Units 1 and 2.\136\ Although the anticipated visibility benefits of DSI 
at the Independence facility were not modeled, we expect that these 
would be less than that for dry scrubbers or wet scrubbers, since DSI 
and enhanced DSI typically have a lower SO2 removal 
efficiency than scrubber controls. Further, we expect that the 
installation and operation of DSI or enhanced DSI would likely present 
the same potential issues discussed by Entergy in its SO2 
BART analysis for White Bluff. Specifically, Entergy stated that before 
DSI technology could be selected as BART for White Bluff, a 
demonstration test would need to be performed to confirm its 
feasibility, achievable performance, and balance of plant impacts 
(brown plume formation, ash handling modifications, landfill/leachate 
considerations, and impact to mercury control). In addition, Entergy 
claimed that DSI has not yet been demonstrated on units comparable to 
those at White Bluff. Because of the similarities between the White 
Bluff and Independence facilities, we expect that these same potential 
issues related to the installation and operation of DSI or enhanced DSI 
would also apply to the Independence facility. In light of all this, we 
expect that even if ADEQ had considered DSI and enhanced DSI in its 
reasonable progress analysis for the Independence facility, it likely 
would not have changed the state's final determination on reasonable 
progress. Therefore, under these particular circumstances, we do not 
consider the omission of consideration of DSI and enhanced DSI as 
control options for SO2 at the Independence facility an 
impediment to approving the reasonable progress analysis.
---------------------------------------------------------------------------

    \133\ We are relying on Entergy's ``adjusted costs,'' which 
reflect Entergy's exclusion of line items not allowed under EPA's 
Control Cost Manual. See ``Entergy Updated BART Five-Factor Analysis 
for Units 1 and 2,'' dated August 18, 2017, Table 4-4. This analysis 
is found under Appendix D of the Arkansas Regional Haze 
SO2 and PM SIP revision.
    \134\ See the file titled ``EPA Cost Calcs_DSI and enhanced 
DSI_Independence.xlsx,'' which can be found in the docket for this 
proposed rulemaking.
    \135\ Id.
    \136\ This is based on a comparison of our cost estimates for 
DSI with Entergy's cost estimates for dry scrubbers and the FIP's 
cost estimates for wet scrubbers for Independence Units 1 and 2. 
Entergy's cost estimates for dry scrubbers and the FIP's cost 
estimates for wet scrubbers for Independence Units 1 and 2 are 
discussed earlier in this notice under Section II.C.4.a.
---------------------------------------------------------------------------

    In its reasonable progress analysis for the Independence facility, 
the statutory factor that appears to have been the most significant in 
Arkansas' reasonable progress determination is the cost of compliance, 
as well as visibility, which the state deemed to be a relevant factor 
for consideration in its analysis. Arkansas discussed its concerns 
regarding the significant capital cost of scrubber controls, noted that 
the evaluation of the $/dv metric demonstrated a greater difference in 
cost between dry FGD and low sulfur coal compared to the $/ton metric, 
and ultimately concluded that all the controls it evaluated would cost 
millions of dollars for what it considers to be little visibility 
benefit. We believe

[[Page 62233]]

that Arkansas' weighing of the four statutory factors and other factors 
it deemed relevant in its reasonable progress analysis for the 
Independence facility was reasonable. Considering the state's concerns 
about the high capital costs and high $/dv of the evaluated controls 
and given that the state is requiring Independence Units 1 and 2 to 
switch to low sulfur coal within 3 years under the long-term strategy, 
which is expected to reduce SO2 emissions and result in 
visibility improvements at Arkansas' Class I areas, it is not 
unreasonable for Arkansas to conclude that SO2 controls 
under the reasonable progress requirements are not necessary for the 
Independence facility in the first implementation period. We are 
proposing to fully approve Arkansas' focused reasonable progress 
analysis, which applied the four statutory factors directly to the 
Independence facility, and its determination that no additional 
controls under the reasonable progress requirements are necessary to 
achieve reasonable progress for the first implementation period. Our 
proposed approval is based on the following: (1) The state's discussion 
of the key pollutants and source categories that contribute to 
visibility impairment in Arkansas' Class I areas per the CENRAP's 
source apportionment modeling; (2) the state's identification of a 
group of large SO2 point sources in Arkansas for potential 
evaluation of controls under reasonable progress; (3) the state's 
rationale for narrowing down its list of potential sources to evaluate 
under the reasonable progress requirements; \137\ and (4) the state's 
evaluation and reasonable weighing of the four statutory factors along 
with consideration of the visibility benefits of controls for the 
Independence facility.
---------------------------------------------------------------------------

    \137\ As explained above, part of ADEQ's basis for determining 
the sources for which to conduct a narrow reasonable progress 
analysis was that certain sources were subject to BART analyses and 
determinations in the first implementation period. For the Domtar 
facility in particular, the state relied on the fact that a FIP is 
in place to address the BART requirements. We propose to agree that 
this is an appropriate basis on which find that nothing further is 
needed for reasonable progress at this source. If, in the future, 
Arkansas submits a further SIP revision addressing the Domtar 
Ashdown Mill, EPA will evaluate whether the analysis and 
determinations therein satisfy the reasonable progress requirements 
as well as BART.
---------------------------------------------------------------------------

    We are also proposing to find that the method used by Arkansas to 
estimate revised 2018 RPGs for the 20% worst days for Caney Creek and 
Upper Buffalo is appropriate. We agree with Arkansas that this is the 
same method utilized by us to revise the RPGs in the Arkansas Regional 
Haze FIP. We are also proposing to find that Arkansas' use of the most 
recent 3 years of data (2014-2016) as opposed to use of the 5 most 
recent years of data (2009-2013) with the exclusion of the minimum and 
maximum values, as we used in the Arkansas FIP, is appropriate because 
it reflects updated data and we also agree with Arkansas that it will 
ensure that recent changes in dispatch at Arkansas EGUs are captured. 
Therefore, we are proposing to agree with Arkansas' revised 2018 RPGs 
of 22.47 dv for Caney Creek and 22.51 dv for Upper Buffalo.
    As discussed elsewhere in this proposed rulemaking, BART controls 
for Domtar Power Boilers No. 1 and 2 are not addressed in the Arkansas 
Regional Haze SO2 and PM SIP Revision, and we are not 
proposing to withdraw the FIP's BART emission limits for the facility 
at this time. If and when ADEQ submits a SIP revision to address BART 
requirements for Domtar Power Boilers No. 1 and No. 2, we will evaluate 
any conclusions ADEQ has drawn in that submission with respect to the 
need to conduct a reasonable progress analysis for Domtar. As long as 
the BART requirements for Domtar continue to be addressed by the 
measures in the FIP, however, we propose to agree with ADEQ's 
conclusion that nothing further is needed to satisfy the reasonable 
progress requirements for the first implementation period. With respect 
to the RPGs for Arkansas' Class I areas, if and when ADEQ submits a SIP 
revision addressing Domtar, we will assess that future SIP revision to 
determine if changes are needed based on any differences between the 
SIP-based measures and the measures currently contained in the FIP.

D. Long-Term Strategy

    Section 169A(b) of the CAA and 40 CFR 51.308(d)(3) require that 
states include in their SIPs a 10 to 15-year strategy, referred to as 
the long-term strategy, for making reasonable progress for each Class I 
area within their state. This long-term strategy is the compilation of 
all control measures a state will use during the implementation period 
of the specific SIP submittal to meet any applicable RPGs for a 
particular Class I area. The long-term strategy must include 
``enforceable emissions limitations, compliance schedules, and other 
measures as necessary to achieve the reasonable progress goals'' for 
all Class I areas within, or affected by emissions from, the 
state.\138\
---------------------------------------------------------------------------

    \138\ 40 CFR 51.308(d)(3).
---------------------------------------------------------------------------

    Section 51.308(d)(3)(v) requires that a state consider certain 
elements in developing its long-term strategy for each Class I area. 
These considerations are the following: (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. Since states are required 
to consider emissions limitations and schedules of compliance to 
achieve the RPGs for each Class I area, the BART emission limits that 
are in a state's regional haze SIP are elements of the state's long-
term strategy for each Class I area. In our March 12, 2012, final 
action on the 2008 Arkansas Regional Haze SIP, since we disapproved a 
portion of Arkansas' BART determinations for Arkansas' two Class I 
areas, we also disapproved the corresponding emissions limitations and 
schedules of compliance elements of the state's long-term strategy, 
while approving remaining elements under section 51.308(d)(3)(v).
    As discussed above, the state is making enforceable Entergy's 
commitment to switch Independence Units 1 and 2 to low sulfur coal and 
comply with an SO2 emission limit of 0.60 lb/MMBtu within 3 
years as part of the long-term strategy. We are proposing to approve 
Arkansas' decision to make enforceable the 0.60 lb/MMBtu SO2 
emission limit for Independence Units 1 and 2 as part of the long-term 
strategy and we are also proposing to approve the other components of 
the long-term strategy addressed by the August 8, 2018 SIP revision. We 
are proposing to find that Arkansas' long-term strategy is approved 
with respect to sources other than the Domtar Ashdown Mill. Because we 
disapproved the majority of ADEQ's 2008 BART determinations for the 
Domtar facility and promulgated a FIP to satisfy these requirements, 
the corresponding components of the long-term strategy for Domtar are 
also currently satisfied by the FIP. No further action by ADEQ is 
required at this time; the Domtar-related components will remain 
covered by the FIP and the approved portion of the 2008 Arkansas 
Regional Haze SIP unless and until EPA

[[Page 62234]]

has received and approved a SIP revision containing the required 
analyses and determinations for this facility.

E. Required Consultation

    The Regional Haze Rule requires states to provide the designated 
Federal Land Managers (FLMs) with an opportunity for consultation at 
least 60 days prior to holding any public hearing on a SIP revision for 
regional haze for the first implementation period. Arkansas sent 
letters to the FLMs on October 27, 2017, providing notification of the 
proposed SIP revision and providing electronic access to the draft SIP 
revision and related documents.\139\ ADEQ also engaged in telephone 
communications with the FLMs and considered and addressed comments 
submitted by the FLMs on the proposed SIP revision.\140\
---------------------------------------------------------------------------

    \139\ See Arkansas Regional Haze SO2 and PM SIP 
revision, Tab E.
    \140\ ADEQ included copies of correspondence with the FLM's, 
included comments received from the FLMs in Tab E of the Arkansas 
Regional Haze SO2 and PM SIP revision.
---------------------------------------------------------------------------

    The Regional Haze Rule at section 51.308(d)(3)(i) also provides 
that if a state has emissions that are reasonably anticipated to 
contribute to visibility impairment in a Class I area located in 
another state, the state must consult with the other state(s) in order 
to develop coordinated emission management strategies. Since Missouri 
has two Class I areas impacted by Arkansas sources, Arkansas sent a 
letter to the Missouri Department of Natural Resources (MDNR) on 
October 27, 2017, providing notification of the proposed SIP revision 
and providing electronic access to the draft SIP revision and related 
documents.\141\ Missouri did not provide comments to Arkansas on the 
proposed SIP revision.
---------------------------------------------------------------------------

    \141\ See Arkansas Regional Haze SO2 and PM SIP 
revision, Tab E.
---------------------------------------------------------------------------

    We are proposing to find that Arkansas provided an opportunity for 
consultation to the FLMs and to Missouri on the proposed SIP revision, 
as required under section 51.308(i)(2) and 51.308(d)(3)(i). We are also 
proposing to find that Arkansas has appropriately considered and 
provided written responses to comments from the FLMs in the final SIP 
submission. Therefore, we are proposing to find that Arkansas has 
satisfied the consultation requirements under sections 51.308(i)(2) and 
51.308(d)(3)(i).

F. Interstate Visibility Transport Under Section 110(a)(2)(D)(i)(II)

    The SIP revision also includes a discussion on interstate 
visibility transport. Specifically, the SIP revision discusses the 
impacts of Arkansas sources on Missouri's Class I areas, as well as the 
most recent IMPROVE monitoring data for Missouri's Class I areas. The 
SIP revision concludes that Missouri is on track to achieve its 
visibility goals, that the visibility progress observed indicates that 
sources in Arkansas are not interfering with the achievement of 
Missouri's RPGs for Hercules Glades and Mingo, and that no additional 
controls on sources within Arkansas are necessary to ensure that other 
states' visibility goals for their Class I areas are met. We are 
deferring proposing action on the interstate visibility transport 
portion of the SIP revision until a future proposed rulemaking.

G. Clean Air Act Section 110(l)

    Section 110(l) of the CAA states 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.'' We 
believe an approval of the Arkansas Regional Haze SO2 and PM 
SIP revision and concurrent withdrawal of the corresponding parts of 
the FIP, as proposed, will meet the Clean Air Act's 110(1) provisions 
concerning attainment and maintenance. No areas in Arkansas are 
currently designated nonattainment for any NAAQS pollutants. As all 
areas in Arkansas are attaining the NAAQS with current emissions 
levels, further reductions from current emission levels because of 
compliance with the emission limits contained in this SIP revision will 
not interfere with attainment or maintenance. The SIP will result in 
emission reductions beyond the status quo.
    Additionally, we do not believe an approval of the Arkansas 
Regional Haze SO2 and PM SIP revision and concurrent 
withdrawal of the corresponding parts of the FIP would interfere with 
the CAA requirements for BART or reasonable progress because our 
proposed approval of the SIP revision is supported by our evaluation of 
the state's conclusions and our rationale explaining why we are 
proposing to find that the BART and reasonable progress requirements 
under the CAA are met, as discussed under sections II.B and II.C of 
this notice. With respect to BART requirements, the SIP would replace 
federal determinations regarding SO2 and PM control 
requirements for EGUs in Arkansas with the state's own determinations. 
We do note that the majority of the state's SO2 and PM BART 
determinations in the SIP revision are essentially identical to the 
BART determinations contained in the Arkansas Regional Haze FIP. The 
only exception to this is White Bluff Units 1 and 2, for which the FIP 
requires an SO2 emission limit of 0.06 lb/MMBtu with a 5-
year compliance date, based on the installation of dry scrubbers. The 
Arkansas Regional Haze SO2 and PM SIP revision does not 
require the SO2 emission limit of 0.06 lb/MMBtu, but it does 
require that Entergy move forward with its announced plans to cease 
coal combustion at White Bluff Units 1 and 2 by the end of 2028 and to 
meet an interim SO2 emission limit of 0.60 lb/MMBtu prior to 
ceasing coal combustion. Once the units cease coal combustion, 
SO2 emissions from White Bluff Units 1 and 2 are expected to 
significantly decrease. Therefore, we expect that the BART controls 
contained in the SIP revision are comparable to the BART controls 
required under the FIP in the long term. More importantly, our proposed 
approval of the SIP revision does not violate CAA section 110(l) with 
respect to BART requirements because the state's BART decisions in the 
SIP revision, which we are proposing to approve, are adequately 
supported by BART five factor analyses that have been adopted and 
incorporated into the SIP revision.
    With respect to reasonable progress, we are proposing to approve 
Arkansas' determination that no additional controls under the 
reasonable progress requirements are necessary to achieve reasonable 
progress for the first implementation period. In contrast to the 
Arkansas Regional Haze FIP, the Arkansas Regional Haze SO2 
and PM SIP revision does not require an SO2 emission limit 
of 0.06 lb/MMBtu with a 5-year compliance date for Independence Units 1 
and 2 based on the installation of dry scrubber controls under the 
reasonable progress requirements. Nevertheless, as discussed in Section 
II.C of this notice, we are proposing to find that the reasonable 
progress requirements under section 51.308(d)(1) have been fully 
addressed for the first implementation period, based on Arkansas' 
discussion of the key pollutants and source categories that contribute 
to visibility impairment in Arkansas' Class I areas per the CENRAP's 
source apportionment modeling; its identification of a group of large 
SO2 point sources in Arkansas for potential evaluation of 
controls under reasonable progress; the state's rationale for narrowing 
down its list of potential sources to evaluate under the reasonable 
progress requirements; and its analysis

[[Page 62235]]

with reasonable weighing of the four statutory factors along with 
consideration of the visibility benefits of controls for the 
Independence facility. Therefore, even though the SIP revision would 
allow for an increase in SO2 emissions from the Independence 
facility compared to the FIP, our proposed approval of the SIP revision 
and concurrent withdrawal of the corresponding parts of the FIP does 
not violate CAA section 110(l) with respect to reasonable progress 
because we are proposing to find that Arkansas has provided a reasoned 
basis to support its determination that the scrubber controls are not 
needed for reasonable progress.

III. Proposed Action

A. Arkansas Regional Haze SIP Revision

    The EPA is proposing to approve the following revisions to the 
Arkansas Regional Haze SIP submitted to EPA on August 8, 2018: The 
SO2 and PM BART requirements for the AECC Bailey Plant Unit 
1; the SO2 and PM BART requirements for the AECC McClellan 
Plant Unit 1; the SO2 BART requirements for Flint Creek 
Plant Boiler No. 1; the SO2 BART requirements for the White 
Bluff Plant Units 1 and 2; the SO2, NOX, and PM 
BART requirements for the White Bluff Auxiliary Boiler; and the 
prohibition on burning of fuel oil at Lake Catherine Unit 4 until 
SO2 and PM BART determinations for the fuel oil firing 
scenario are approved into the SIP by EPA. These BART requirements have 
now been made enforceable by the state through Administrative Orders 
that have been adopted and incorporated in the SIP revision. We are 
proposing to approve these Administrative Orders as source-specific 
BART revisions to the SIP. The BART requirements and associated 
Administrative Orders are listed under Table 15 below. We are proposing 
to withdraw our February 12, 2018,\142\ approval of Arkansas' reliance 
on participation in the CSAPR ozone season NOX trading 
program to satisfy the NOX BART requirement for the White 
Bluff Auxiliary Boiler given that Arkansas erroneously identified the 
Auxiliary Boiler as participating in CSAPR for ozone season 
NOX. We are proposing to replace our prior approval of 
Arkansas' determination for the White Bluff Auxiliary Boiler with our 
proposed approval of the source specific NOX BART emission 
limit contained in the August 8, 2018, SIP revision. We are proposing 
to approve ADEQ's revised identification of the 6A Boiler at the 
Georgia-Pacific Crossett Mill as BART-eligible and the additional 
information and technical analysis presented in the SIP revision in 
support of the determination that the Georgia-Pacific Crossett Mill 6A 
and 9A Boilers are not subject to BART.
---------------------------------------------------------------------------

    \142\ 83 FR 5927.
---------------------------------------------------------------------------

    We are also proposing to find that the reasonable progress 
requirements under section 51.308(d)(1) have been fully addressed for 
the first implementation period. Specifically, we are proposing to 
approve the state's focused reasonable progress analysis and the 
reasonable progress determination that no additional SO2 
controls at Independence Units 1 and 2 or any other Arkansas sources 
are necessary under reasonable progress for the first implementation 
period. We are also proposing to agree with the state's revised RPGs 
for Arkansas' Class I areas. We are basing our proposed approval of the 
reasonable progress provisions and revised RPGs on the state's 
discussion of the key pollutants and source categories that contribute 
to visibility impairment in Arkansas' Class I areas per the CENRAP's 
source apportionment modeling; the state's identification of a group of 
large SO2 point sources in Arkansas for potential evaluation 
of controls under reasonable progress; the state's rationale for 
narrowing down its list of potential sources to evaluate under the 
reasonable progress requirements; and the state's evaluation and 
reasonable weighing of the four statutory factors along with 
consideration of the visibility benefits of controls for the 
Independence facility. The August 8, 2018, SIP revision does not 
address BART and associated long-term strategy requirements for the 
Domtar Ashdown Mill Power Boilers No. 1 and 2, and we are not proposing 
to withdraw the FIP's BART emission limits for the facility at this 
time. If and when ADEQ submits a SIP revision to address BART 
requirements for Domtar Power Boilers No. 1 and No. 2, we will evaluate 
any conclusions ADEQ has drawn in that submission with respect to the 
need to conduct a reasonable progress analysis for Domtar. As long as 
the BART requirements for Domtar continue to be addressed by the 
measures in the FIP, however, we propose to agree with ADEQ's 
conclusion that nothing further is needed to satisfy the reasonable 
progress requirements for the first implementation period. With respect 
to the RPGs for Arkansas' Class I areas, if and when ADEQ submits a SIP 
revision addressing Domtar, we will assess that future SIP revision to 
determine if changes are needed based on any differences between the 
SIP-based measures and the measures currently contained in the FIP.
    We are proposing to approve the components of the long-term 
strategy under section 51.308(d)(3) addressed by the August 8, 2018, 
SIP revision, including the BART measures contained in the SIP revision 
and the SO2 emission limit of 0.60 lb/MMBtu for Independence 
Units 1 and 2 based on the use of low sulfur coal. These requirements 
for Independence Units 1 and 2 have now been made enforceable by the 
state through an Administrative Order that has been adopted and 
incorporated in the SIP revision. We are proposing to approve this 
Administrative Order as a source-specific revision to the SIP. The 
SO2 emission limit and associated Administrative Order for 
the Independence facility are listed under Table 16 below. We are 
proposing to find that Arkansas' long-term strategy is approved with 
respect to sources other than the Domtar Ashdown Mill. We are also 
proposing to find that Arkansas has provided an opportunity for 
consultation to the FLMs and to Missouri on the proposed SIP revision, 
as required under section 51.308(i)(2) and 51.308(d)(3)(i). The BART 
emission limits we are proposing to approve are presented in Table 15; 
the SO2 emission limits under the long-term strategy and 
associated Administrative Order we are proposing to approve for the 
Independence facility are presented in Table 16; and Arkansas' revised 
2018 RPGs are presented in Table 17.

[[Page 62236]]

           Table 15--SIP Revision BART Emission Limits and Administrative Orders Proposed for Approval
----------------------------------------------------------------------------------------------------------------
                                   SIP revision SO2     SIP revision PM    SIP revision NOX
     Subject-to-BART source          BART emission       BART emission       BART emission      Administrative
                                        limits              limits              limits               order
----------------------------------------------------------------------------------------------------------------
AECC Bailey Unit 1..............  0.5% limit on       0.5% limit on       Already SIP-        Administrative
                                   sulfur content of   sulfur content of   approved.           Order LIS No. 18-
                                   fuel combusted*.    fuel combusted*.                        071.
AECC McClellan Unit 1...........  0.5% limit on       0.5% limit on       Already SIP-        Administrative
                                   sulfur content of   sulfur content of   approved.           Order LIS No. 18-
                                   fuel combusted*.    fuel combusted*.                        071.
AEP Flint Creek Boiler No. 1....  0.06 lb/MMBtu*....  Already SIP-        Already SIP-        Administrative
                                                       approved.           approved.           Order LIS No. 18-
                                                                                               072.
Entergy Lake Catherine Unit 4     Unit is allowed to  Unit is allowed to  Already SIP-        Administrative
 (fuel oil firing scenario).       burn only natural   burn only natural   approved.           Order LIS No. 18-
                                   gas*.               gas*.                                   073.
Entergy White Bluff Unit 1......  0.60 lb/MMBtu.....  Already SIP-        Already SIP-        Administrative
                                  (Interim emission    approved.           approved.           Order LIS No. 18-
                                   limit with a 3-                                             073.
                                   year compliance
                                   date and
                                   cessation of coal
                                   combustion by end
                                   of 2028).
Entergy White Bluff Unit 2......  0.60 lb/MMBtu.....  Already SIP-        Already SIP-        Administrative
                                  (Interim emission    approved.           approved.           Order LIS No. 18-
                                   limit with a 3-                                             073.
                                   year compliance
                                   date and
                                   cessation of coal
                                   combustion by end
                                   of 2028).
Entergy White Bluff Auxiliary     105.2 lb/hr*......  4.5 lb/hr*........  32.2 lb/hr*.......  Administrative
 Boiler.                                                                                       Order LIS No. 18-
                                                                                               073.
----------------------------------------------------------------------------------------------------------------
* This BART emission limit required by the SIP revision is the same as what was required under the Arkansas
  Regional Haze FIP.

  Table 16--SIP Revision Emission Limits Under Reasonable Progress and
               Administrative Orders Proposed for Approval
------------------------------------------------------------------------
                                   SIP revision SO2
             Source                emission limits      Administrative
                                                            order
------------------------------------------------------------------------
Entergy Independence Unit 1.....      0.60 lb/MMBtu  Administrative
                                                      Order LIS No. 18-
                                                      073.
Entergy Independence Unit 2.....      0.60 lb/MMBtu  Administrative
                                                      Order LIS No. 18-
                                                      073.
------------------------------------------------------------------------

                  Table 17--Arkansas' Revised 2018 RPGs
------------------------------------------------------------------------
                                                          2018 RPG 20%
                     Class I area                        worst days (dv)
------------------------------------------------------------------------
Caney Creek...........................................             22.47
Upper Buffalo.........................................             22.51
------------------------------------------------------------------------

B. Partial FIP Withdrawal

    We are proposing to withdraw those portions of the Arkansas 
Regional Haze FIP at 40 CFR 52.173 that impose SO2 and PM 
BART requirements on Bailey Unit 1; SO2 and PM BART 
requirements on McClellan Unit 1; SO2 BART requirements on 
Flint Creek Boiler No. 1; the provisions concerning BART for the fuel 
oil firing scenario for Lake Catherine Unit 4; SO2 BART 
requirements for White Bluff Units 1 and 2; SO2 and PM BART 
requirements for the White Bluff Auxiliary Boiler; and the 
SO2 emission limits under reasonable progress for 
Independence Units 1 and 2. We are proposing that these portions of the 
FIP will be replaced by the portion of the Arkansas Regional Haze 
SO2 and PM SIP revision that we are proposing to approve in 
this action. Since we are proposing to withdraw certain portions of the 
FIP, we are also proposing to redesignate the FIP by revising the 
numbering of certain paragraphs under section 40 CFR 52.173. Our 
proposed redesignation of the numbering of these paragraphs is non-
substantive and does not mean we are reopening these parts for public 
comment in this proposed rulemaking.

C. Clean Air Act Section 110(l)

    We are proposing to find that an approval of a portion of the 
Arkansas Regional Haze SO2 and PM SIP revision and 
concurrent withdrawal of the corresponding parts of the FIP, as 
proposed, will meet the Clean Air Act's 110(1) provisions.

IV. Incorporation by Reference

    In this action, we are proposing to include in a final rule 
regulatory text that includes incorporation by reference. In accordance 
with the requirements of 1 CFR 51.5, we are proposing to incorporate by 
reference revisions to the Arkansas source specific requirements as 
described in the Proposed Action section above. We have made, and will 
continue to make, these documents generally available electronically 
through www.regulations.gov and in hard copy at the EPA Region 6 office 
(please contact Dayana Medina, 214-665-7241, [email protected] for 
more information).

V. Statutory and Executive Order Reviews

    Under the CAA, 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 criteria of the CAA. Accordingly, this 
action merely proposes to approve 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);
     Is not an Executive Order 13771 (82 FR 9339, February 2, 
2017) regulatory action because SIP approvals are exempted under 
Executive Order 12866;

[[Page 62237]]

     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, as 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 this action does not involve technical standards; 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 proposed 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).

List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Best available 
retrofit technology, Incorporation by reference, Intergovernmental 
relations, Ozone, Particulate matter, regional haze, Reporting and 
recordkeeping requirements, Sulfur dioxide, Visibility.

    Dated: November 21, 2018.
David Gray,
Acting Regional Administrator, Region 6.

    Title 40, chapter I, of the Code of Federal Regulations is proposed 
to be 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. In paragraph (d), the table titled ``EPA-Approved Arkansas Source-
Specific Requirements'' is amended by revising the heading ``Permit 
No.'' to ``Permit or Order No.'' and adding the entries ``Arkansas 
Electric Cooperative Corporation Carl E. Bailey Plant'', ``Arkansas 
Electric Cooperative Corporation John L. McClellan'', ``Entergy 
Arkansas, Inc. Lake Catherine Plant'', ``Entergy Arkansas, Inc. White 
Bluff Plant'', and ``Entergy Arkansas, Inc. Independence Plant''.
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 the entry ``Arkansas Regional Haze 
SO2 and PM SIP Revision'' at the end of the third table.
    The revision and additions read as follows:

Sec.  52.170  Identification of plan.

* * * * *
    (d) * * *
    (e) * * *
* * * * *

                               EPA-Approved Arkansas Source-Specific Requirements
----------------------------------------------------------------------------------------------------------------
                                                        State approval/
          Name of source           Permit or order no.     effective     EPA approval date         Comments
                                                             date
----------------------------------------------------------------------------------------------------------------
Arkansas Electric Cooperative      Administrative             8/7/2018  [Date of             Unit 1.
 Corporation Carl E. Bailey Plant.  Order LIS No. 18-                    publication of the
                                    071.                                 final rule in the
                                                                         Federal Register]
                                                                         [Federal Register
                                                                         citation of the
                                                                         final rule].
Arkansas Electric Cooperative      Administrative             8/7/2018  [Date of             Unit 1.
 Corporation John L. McClellan.     Order LIS No. 18-                    publication of the
                                    072.                                 final rule in the
                                                                         Federal Register]
                                                                         [Federal Register
                                                                         citation of the
                                                                         final rule].
Entergy Arkansas, Inc. Lake        Administrative             8/7/2018  [Date of             Unit 4.
 Catherine Plant.                   Order LIS No. 18-                    publication of the
                                    073.                                 final rule in the
                                                                         Federal Register]
                                                                         [Federal Register
                                                                         citation of the
                                                                         final rule].
Entergy Arkansas, Inc. White       Administrative             8/7/2018  [Date of             Units 1, 2, and the
 Bluff Plant.                       Order LIS No. 18-                    publication of the   Auxiliary Boiler.
                                    073.                                 final rule in the
                                                                         Federal Register]
                                                                         [Federal Register
                                                                         citation of the
                                                                         final rule].
Entergy Arkansas, Inc.             Administrative             8/7/2018  [Date of             Units 1 and 2.
 Independence Plant.                Order LIS No. 18-                    publication of the
                                    073.                                 final rule in the
                                                                         Federal Register]
                                                                         [Federal Register
                                                                         citation of the
                                                                         final rule].
----------------------------------------------------------------------------------------------------------------

[[Page 62238]]

            EPA-Approved Non-regulatory Provisions and Quasi-Regulatory Measures in the Arkansas SIP
----------------------------------------------------------------------------------------------------------------
                                     Applicable
                                   geographic or     State submittal/
     Name of SIP provision         nonattainment      effective date   EPA approval date        Explanation
                                        area
----------------------------------------------------------------------------------------------------------------
 
                                                  * * * * * * *
Arkansas Regional Haze SO2 and   Statewide........  August 8, 2018...  [Date of           Regional Haze SIP
 PM SIP Revision.                                                       publication of     submittal addressing
                                                                        the final rule     SO2 and PM BART
                                                                        in the Federal     requirements for
                                                                        Register]          Arkansas EGUs, NOX
                                                                        [Federal           BART requirement for
                                                                        Register           the White Bluff
                                                                        citation of the    Auxiliary Boiler, and
                                                                        final rule].       reasonable progress
                                                                                           requirements for SO2
                                                                                           for the first
                                                                                           implementation
                                                                                           period.
----------------------------------------------------------------------------------------------------------------

0
3. Section 52.173 is amended by:
0
a. Revising the introductory text of paragraph (c) and paragraph 
(c)(1);
0
b. In paragraph (c)(2) revising the definition ``Boiler-operating-
day'';
0
c. Removing paragraphs (c)(3) through (12), and (22) through (24);
0
d. Redesignating paragraphs (c)(13) through (21) as paragraphs (c)(3) 
through (11);
0
e. Redesignating paragraphs (c)(25) through (27) as paragraphs (c)(12) 
through (14);
0
f. Revising newly redesignated paragraphs (c)(4), (c)(5),(c)(7), 
(c)(8), (c)(10), (c)(11), and (c)(12);
0
g. Adding paragraphs (g) and (h).
    The revisions and additions read as follows:

Sec.  52.173  Visibility protection.

* * * * *
    (c) Federal implementation plan for regional haze. Requirements for 
Domtar Ashdown Paper Mill Power Boilers No. 1 and 2 affecting 
visibility.
    (1) Applicability. The provisions of this section shall apply to 
each owner or operator, or successive owners or operators of the 
sources designated as Domtar Ashdown Paper Mill Power Boilers No. 1 and 
2.
    (2) * * *
    Boiler-operating-day means a 24-hr period between 6 a.m. and 6 a.m. 
the following day during which any fuel is fed into and/or combusted at 
any time in the power boiler.
* * * * *
    (4) Compliance dates for Domtar Ashdown Mill Power Boiler No. 1. 
The owner or operator of the boiler must comply with the SO2 
and NOX emission limits listed in paragraph (c)(3) of this 
section by November 28, 2016.
    (5) Compliance determination and reporting and recordkeeping 
requirements for Domtar Ashdown Paper Mill Power Boiler No. 1. (i)(A) 
SO2 emissions resulting from combustion of fuel oil shall be 
determined by assuming that the SO2 content of the fuel 
delivered to the fuel inlet of the combustion chamber is equal to the 
SO2 being emitted at the stack. The owner or operator must 
maintain records of the sulfur content by weight of each fuel oil 
shipment, where a ``shipment'' is considered delivery of the entire 
amount of each order of fuel purchased. Fuel sampling and analysis may 
be performed by the owner or operator, an outside laboratory, or a fuel 
supplier. All records pertaining to the sampling of each shipment of 
fuel oil, including the results of the sulfur content analysis, must be 
maintained by the owner or operator and made available upon request to 
EPA and ADEQ representatives. SO2 emissions resulting from 
combustion of bark shall be determined by using the following site-
specific curve equation, which accounts for the SO2 
scrubbing capabilities of bark combustion: Y= 0.4005 * X-0.2645

Where:

Y = pounds of sulfur emitted per ton of dry fuel feed to the boiler.
X = pounds of sulfur input per ton of dry bark.

    (B) The owner or operator must confirm the site-specific curve 
equation through stack testing. By October 27, 2017, the owner or 
operator must provide a report to EPA showing confirmation of the site 
specific-curve equation accuracy. Records of the quantity of fuel input 
to the boiler for each fuel type for each day must be compiled no later 
than 15 days after the end of the month and must be maintained by the 
owner or operator and made available upon request to EPA and ADEQ 
representatives. Each boiler-operating-day of the 30-day rolling 
average for the boiler must be determined by adding together the pounds 
of SO2 from that boiler-operating-day and the preceding 29 
boiler-operating-days and dividing the total pounds of SO2 
by the sum of the total number of boiler operating days (i.e., 30). The 
result shall be the 30 boiler-operating-day rolling average in terms of 
lb/day emissions of SO2. Records of the total SO2 
emitted for each day must be compiled no later than 15 days after the 
end of the month and must be maintained by the owner or operator and 
made available upon request to EPA and ADEQ representatives. Records of 
the 30 boiler-operating-day rolling averages for SO2 as 
described in this paragraph (c)(5)(i) must be maintained by the owner 
or operator for each boiler-operating-day and made available upon 
request to EPA and ADEQ representatives.
    (ii) If the air permit is revised such that Power Boiler No. 1 is 
permitted to burn only pipeline quality natural gas, this is sufficient 
to demonstrate that the boiler is complying with the SO2 
emission limit under paragraph (c)(3) of this section. The compliance 
determination requirements and the reporting and recordkeeping 
requirements under paragraph (c)(5)(i) of this section would not apply 
and confirmation of the accuracy of the site-specific curve equation 
under paragraph (c)(5)(i)(B) of this section through stack testing 
would not be required so long as Power Boiler No. 1 is only permitted 
to burn pipeline quality natural gas.
    (iii) To demonstrate compliance with the NOX emission 
limit under paragraph (c)(3) of this section, the owner or operator 
shall conduct stack testing using EPA Reference Method 7E, found at 40 
CFR part 60, Appendix A, once every 5 years, beginning 1 year from the 
effective date of our final rule, which corresponds to October 27, 
2017. Records and reports pertaining to the stack testing must be 
maintained by the owner or operator and made available upon request to 
EPA and ADEQ representatives.
    (iv) If the air permit is revised such that Power Boiler No. 1 is 
permitted to burn only pipeline quality natural gas, the owner or 
operator may demonstrate compliance with the NOX emission 
limit under paragraph (c)(3) of this section by calculating 
NOX emissions using fuel usage records and the applicable 
NOX emission factor under AP-42, Compilation of Air 
Pollutant Emission Factors, section 1.4, Table 1.4-1. Records of the 
quantity of natural gas

[[Page 62239]]

input to the boiler for each day must be compiled no later than 15 days 
after the end of the month and must be maintained by the owner or 
operator and made available upon request to EPA and ADEQ 
representatives. Records of the calculation of NOX emissions 
for each day must be compiled no later than 15 days after the end of 
the month and must be maintained by the owner or operator and made 
available upon request to EPA and ADEQ representatives. Each boiler-
operating-day of the 30-day rolling average for the boiler must be 
determined by adding together the pounds of NOX from that 
day and the preceding 29 boiler-operating-days and dividing the total 
pounds of NOX by the sum of the total number of hours during 
the same 30 boiler-operating-day period. The result shall be the 30 
boiler-operating-day rolling average in terms of lb/hr emissions of 
NOX. Records of the 30 boiler-operating-day rolling average 
for NOX must be maintained by the owner or operator for each 
boiler-operating-day and made available upon request to EPA and ADEQ 
representatives. Under these circumstances, the compliance 
determination requirements and the reporting and recordkeeping 
requirements under paragraph (c)(5)(iii) of this section would not 
apply.
* * * * *
    (7) SO2 and NOX Compliance dates for Domtar 
Ashdown Mill Power Boiler No. 2. The owner or operator of the boiler 
must comply with the SO2 and NOX emission limits 
listed in paragraph (c)(6) of this section by October 27, 2021.
    (8) SO2 and NOX Compliance determination and 
reporting and recordkeeping requirements for Domtar Ashdown Mill Power 
Boiler No. 2. (i) NOX and SO2 emissions for each 
day shall be determined by summing the hourly emissions measured in 
pounds of NOX or pounds of SO2. Each boiler-
operating-day of the 30-day rolling average for the boiler shall be 
determined by adding together the pounds of NOX or 
SO2 from that day and the preceding 29 boiler-operating-days 
and dividing the total pounds of NOX or SO2 by 
the sum of the total number of hours during the same 30 boiler-
operating-day period. The result shall be the 30 boiler-operating-day 
rolling average in terms of lb/hr emissions of NOX or 
SO2. If a valid NOX pounds per hour or 
SO2 pounds per hour is not available for any hour for the 
boiler, that NOX pounds per hour shall not be used in the 
calculation of the 30 boiler-operating-day rolling average for 
NOX. For each day, records of the total SO2 and 
NOX emitted for that day by the boiler must be maintained by 
the owner or operator and made available upon request to EPA and ADEQ 
representatives. Records of the 30 boiler-operating-day rolling average 
for SO2 and NOX for the boiler as described in 
this paragraph (c)(8)(i) must be maintained by the owner or operator 
for each boiler-operating-day and made available upon request to EPA 
and ADEQ representatives.
    (ii) The owner or operator shall continue to maintain and operate a 
CEMS for SO2 and NOX on the boiler listed in 
paragraph (c)(6) of this section in accordance with 40 CFR 60.8 and 
60.13(e), (f), and (h), and appendix B of 40 CFR part 60. The owner or 
operator shall comply with the quality assurance procedures for CEMS 
found in 40 CFR part 60. Compliance with the emission limits for 
SO2 and NOX shall be determined by using data 
from a CEMS.
    (iii) Continuous emissions monitoring shall apply during all 
periods of operation of the boiler listed in paragraph (c)(6) of this 
section, including periods of startup, shutdown, and malfunction, 
except for CEMS breakdowns, repairs, calibration checks, and zero and 
span adjustments. Continuous monitoring systems for measuring 
SO2 and NOX and diluent gas shall complete a 
minimum of one cycle of operation (sampling, analyzing, and data 
recording) for each successive 15-minute period. Hourly averages shall 
be computed using at least one data point in each fifteen-minute 
quadrant of an hour. Notwithstanding this requirement, an hourly 
average may be computed from at least two data points separated by a 
minimum of 15 minutes (where the unit operates for more than one 
quadrant in an hour) if data are unavailable as a result of performance 
of calibration, quality assurance, preventive maintenance activities, 
or backups of data from data acquisition and handling system, and 
recertification events. When valid SO2 or NOX 
pounds per hour emission data are not obtained because of continuous 
monitoring system breakdowns, repairs, calibration checks, or zero and 
span adjustments, emission data must be obtained by using other 
monitoring systems approved by the EPA to provide emission data for a 
minimum of 18 hours in each 24-hour period and at least 22 out of 30 
successive boiler operating days.
    (iv) If the air permit is revised such that Power Boiler No. 2 is 
permitted to burn only pipeline quality natural gas, this is sufficient 
to demonstrate that the boiler is complying with the SO2 
emission limit under paragraph (c)(6) of this section. Under these 
circumstances, the compliance determination requirements under 
paragraphs (c)(8)(i) through (iii) of this section would not apply to 
the SO2 emission limit listed in paragraph (c)(6) of this 
section.
    (v) If the air permit is revised such that Power Boiler No. 2 is 
permitted to burn only pipeline quality natural gas and the operation 
of the CEMS is not required under other applicable requirements, the 
owner or operator may demonstrate compliance with the NOX 
emission limit under paragraph (c)(6) of this section by calculating 
NOX emissions using fuel usage records and the applicable 
NOX emission factor under AP-42, Compilation of Air 
Pollutant Emission Factors, section 1.4, Table 1.4-1. Records of the 
quantity of natural gas input to the boiler for each day must be 
compiled no later than 15 days after the end of the month and must be 
maintained by the owner or operator and made available upon request to 
EPA and ADEQ representatives. Records of the calculation of 
NOX emissions for each day must be compiled no later than 15 
days after the end of the month and must be maintained and made 
available upon request to EPA and ADEQ representatives. Each boiler-
operating-day of the 30-day rolling average for the boiler must be 
determined by adding together the pounds of NOX from that 
day and the preceding 29 boiler-operating-days and dividing the total 
pounds of NOX by the sum of the total number of hours during 
the same 30 boiler-operating-day period. The result shall be the 30 
boiler-operating-day rolling average in terms of lb/hr emissions of 
NOX. Records of the 30 boiler-operating-day rolling average 
for NOX must be maintained by the owner or operator for each 
boiler-operating-day and made available upon request to EPA and ADEQ 
representatives. Under these circumstances, the compliance 
determination requirements under paragraphs (c)(8)(i) through (iii) of 
this section would not apply to the NOX emission limit.
* * * * *
    (10) PM compliance dates for Domtar Ashdown Mill Power Boiler No. 
2. The owner or operator of the boiler must comply with the PM BART 
requirement listed in paragraph (c)(9) of this section by November 28, 
2016.
    (11) Alternative PM Compliance Determination for Domtar Ashdown 
Paper Mill Power Boiler No.2. If the air permit is revised such that 
Power Boiler No. 2 is permitted to burn only pipeline quality natural 
gas, this is sufficient to demonstrate that the boiler is complying

[[Page 62240]]

with the PM BART requirement under paragraph (c)(9) of this section.
    (12) Reporting and recordkeeping requirements. Unless otherwise 
stated, all requests, reports, submittals, notifications, and other 
communications to the Regional Administrator required under paragraph 
(c) of this section shall be submitted, unless instructed otherwise, to 
the Director, Multimedia Division, U.S. Environmental Protection 
Agency, Region 6, to the attention of Mail Code: 6MM, at 1445 Ross 
Avenue, Suite 1200, Dallas, Texas 75202-2733. For each unit subject to 
the emissions limitation under paragraph (c) of this section, the owner 
or operator shall comply with the following requirements, unless 
otherwise specified:
* * * * *
    (g) Measures addressing best available retrofit technology (BART) 
for electric generating unit (EGU) emissions of sulfur dioxide 
(SO2) and particulate matter. The BART requirements for 
SO2 and PM emissions from EGUs in Arkansas and 
NOX emissions from the White Bluff Auxiliary Boiler are 
satisfied by the Arkansas Regional Haze SO2 and PM SIP 
Revision approved [Date 30 days after date of publication of the final 
rule in the Federal Register].
    (h) Other measures addressing reasonable progress. The reasonable 
progress requirements for SO2 and PM emissions are satisfied 
by the Arkansas Regional Haze SO2 and PM SIP Revision 
approved [Date 30 days after date of publication of the final rule in 
the Federal Register], the Arkansas Regional Haze FIP, and the 2008 
Arkansas Regional Haze SIP.

[FR Doc. 2018-26073 Filed 11-29-18; 8:45 am]
 BILLING CODE 6560-50-P