Document ID: EPA-R04-OAR-2019-0447-0001
Agency: epa
Document Type: Proposed Rule
Title: Air Quality State Implementation Plans; Approvals and Promulgations: Mississippi; Best Available Retrofit Technology State Implementation Plan and Regional Haze Progress Report
Posted Date: 2020-08-04T04:00Z

[Federal Register Volume 85, Number 150 (Tuesday, August 4, 2020)]
[Proposed Rules]
[Pages 47134-47151]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-16443]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R04-OAR-2019-0447; FRL-10012-92-Region 4]

Air Plan Approval; MS; BART SIP and Regional Haze Progress Report

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to 
approve, through parallel processing, a draft Mississippi State 
Implementation Plan (SIP) revision, submitted through a letter dated 
April 23, 2020, addressing best available retrofit technology (BART) 
determinations for 14 electric generating units (EGUs) (``draft BART 
SIP''). These EGUs were initially addressed in EPA's prior limited 
approval and limited disapproval actions on Mississippi's regional haze 
SIP because of deficiencies arising from the State's reliance on the 
Clean Air Interstate Rule (CAIR) to satisfy certain regional haze 
requirements. EPA proposes to approve the draft BART SIP and finds that 
it corrects the deficiencies that led to the limited approval and 
limited disapproval of the State's regional haze SIP; to withdraw the 
limited disapproval of the regional haze SIP; and to replace the prior 
limited approval with a full approval of the regional haze SIP as 
meeting all regional haze requirements of the Clean Air Act (CAA or 
Act) for the first implementation period. In addition, EPA is proposing 
to approve the State's first periodic report describing progress 
towards reasonable progress goals (RPGs) established for regional haze 
and the associated determination that the State's regional haze SIP is 
adequate to meet these RPGs for the first implementation period 
(``Progress Report''). The State submitted the

[[Page 47135]]

progress report as a SIP revision by letter dated October 4, 2018.

DATES: Comments must be received on or before September 3, 2020.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R04-
OAR-2019-0447, at http://www.regulations.gov. Follow the online 
instructions for submitting comments. Once submitted, comments cannot 
be edited or removed from Regulations.gov. 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. EPA will 
generally not consider comments or comment contents located outside of 
the primary submission (i.e., on the web, cloud, or other file sharing 
system). For additional submission methods, the full EPA public comment 
policy, information about CBI or multimedia submissions, and general 
guidance on making effective comments, please visit http://www2.epa.gov/dockets/commenting-epa-dockets.

FOR FURTHER INFORMATION CONTACT: Michele Notarianni or Gobeail 
McKinley, Air Regulatory Management Section, Air Planning and 
Implementation Branch, Air and Radiation Division, U.S. Environmental 
Protection Agency, Region 4, 61 Forsyth Street, SW, Atlanta, Georgia 
30303-8960. Ms. Notarianni can be reached via telephone at (404) 562-
9031 or electronic mail at notarianni.michele@epa.gov. Ms. McKinley can 
be reached via telephone at (404) 562-9230 or electronic mail at 
mckinley.gobeail@epa.gov.

SUPPLEMENTARY INFORMATION:

I. Parallel Processing

    Parallel processing refers to a process that utilizes concurrent 
state and federal proposed rulemaking actions. Generally, the state 
submits a copy of the proposed regulation or other revisions to EPA 
before conducting its public hearing and completing its public comment 
process under state law. EPA reviews this proposed state action and 
prepares a notice of proposed rulemaking (NPRM) under federal law.\1\ 
If, after the state completes its public comment process and after 
EPA's public comment process has run, the state changes its final 
submittal from the proposed submittal, EPA evaluates those changes and 
decides whether to publish another NPRM in light of those changes or to 
proceed to taking final action on its proposed action and describe the 
state's changes in its final rulemaking action. Any final rulemaking 
action by EPA will occur only after the final submittal has been 
adopted by the state and formally provided to EPA.
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    \1\ Although not the case in this proposed rulemaking, in some 
instances, EPA's NPRM is published in the Federal Register during 
the same time frame that the state is holding its public hearing and 
conducting its public comment process. The state and EPA then 
provide for concurrent public comment periods on both the state 
action and federal action.
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    In its previously submitted regional haze SIP,\2\ the Mississippi 
Department of Environmental Quality (MDEQ) relied on CAIR \3\ to meet 
BART requirements for the 14 BART-eligible units, located at seven 
facilities, formerly subject to that trading program.\4\ Mississippi's 
newly submitted draft BART SIP addresses BART for these EGUs in lieu of 
relying on CAIR as an alternative to BART. Because the draft BART SIP 
has not yet completed the State's public notice-and-comment process, 
Mississippi has requested that EPA parallel process the SIP revision 
with the State's rulemaking proceedings. Mississippi submitted the 
draft BART SIP to EPA on April 23, 2020,\5\ and noticed it for public 
comment on the same date. The State's public comment period closed on 
May 23, 2020.
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    \2\ In this notice, EPA is using ``regional haze SIP'' and 
``regional haze plan'' interchangeably.
    \3\ CAIR created regional cap-and-trade programs to reduce 
sulfur dioxide (SO2) and nitrogen oxide (NOX) 
emissions in 27 eastern states (and the District of Columbia), 
including Mississippi, that contributed to downwind nonattainment or 
interfered with maintenance of the 1997 8-hour ozone national 
ambient air quality standards (NAAQS) or the 1997 fine particulate 
matter (PM2.5) NAAQS.
    \4\ See 77 FR 38191 (June 27, 2012); 77 FR 33642 (June 7, 2012).
    \5\ EPA received MDEQ's April 23, 2020, draft BART SIP on April 
24, 2020.
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    After Mississippi submits the final BART SIP (including a response 
to all public comments raised during the State's public participation 
process), EPA will evaluate the submittal. If the State changes the 
final submittal from the draft BART SIP that EPA is proposing to 
approve today, EPA will evaluate those changes for significance. If EPA 
finds any such changes to be significant, then the Agency intends to 
determine whether to re-propose based on the revised submission or to 
proceed to take final action on the BART SIP as changed by the State.

II. Background

A. Regional Haze and the Regional Haze Plan

    Regional haze is visibility impairment that is produced by a 
multitude of sources and activities which are located across a broad 
geographic area and emit PM2.5 (e.g., sulfates, nitrates, 
organic carbon, elemental carbon, and soil dust), and their precursors 
(e.g., SO2, NOX, and in some cases, ammonia 
(NH3) and volatile organic compounds (VOC)). Fine particle 
precursors react in the atmosphere to form PM2.5 which 
impairs visibility by scattering and absorbing light. Visibility 
impairment (i.e., light scattering) reduces the clarity, color, and 
visible distance that one can see. PM2.5 can also cause 
serious health effects (including premature death, heart attacks, 
irregular heartbeat, aggravated asthma, decreased lung function, and 
increased respiratory symptoms) and mortality in humans and contributes 
to 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 visibility impairment caused by air 
pollution occurs virtually all the time at most national park and 
wilderness areas. The average visual range \6\ in many Class I areas 
\7\ in the western United States is 100-150 kilometers (km), or about 
one-half to two-thirds of the visual range that would exist without 
anthropogenic air pollution. In most of the eastern Class I areas of 
the United States, the average visual range is less than 30 km, or 
about one-fifth of the visual range that would exist under estimated 
natural conditions. See 64 FR 35714, 35715 (July 1, 1999). CAA programs

[[Page 47136]]

have reduced emissions of haze-causing pollution, lessening visibility 
impairment and resulting in improved average visual ranges.\8\
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    \6\ Visual range is the greatest distance, in km or miles, at 
which a dark object can be viewed against the sky.
    \7\ Areas designated as mandatory Class I 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. See 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. See 44 FR 69122 
(November 30, 1979); 40 CFR part 81 Subpart D. The extent of a 
mandatory Class I area includes subsequent changes in boundaries, 
such as park expansions. See 42 U.S.C. 7472(a). Although states and 
tribes may designate as Class I additional areas which they consider 
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 area is 
the responsibility of a ``Federal Land Manager.'' See 42 U.S.C. 
7602(i). When the term ``Class I area'' is used in this action, it 
means a ``mandatory Class I Federal area.''
    \8\ An interactive ``story map'' depicting efforts and recent 
progress by EPA and states to improve visibility at national parks 
and wilderness areas is available 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, 
anthropogenic impairment of visibility in 156 national parks and 
wilderness areas designated as mandatory Class I federal areas. 
Congress added section 169B to the CAA in 1990 to address regional haze 
issues, and EPA subsequently promulgated the Regional Haze Rule 
(RHR).\9\ The RHR established a requirement to submit a regional haze 
SIP which applies to all 50 states, the District of Columbia, and the 
Virgin Islands.\10\ Each jurisdiction was required to submit a SIP 
addressing regional haze requirements for the first implementation 
period no later than December 17, 2007.\11\
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    \9\ See 64 FR 35713 (July 1, 1990).
    \10\ 40 CFR 51.300(b).
    \11\ 40 CFR 51.308(b).
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    On September 22, 2008, Mississippi submitted a SIP revision to 
address regional haze in Class I areas impacted by emissions from 
Mississippi and subsequently amended that submittal on May 9, 2011. As 
discussed further in Section II.B.2, EPA finalized a limited approval 
and a limited disapproval of the Mississippi regional haze SIP in June 
2012 because of deficiencies \12\ in the regional haze SIP arising from 
the State's reliance on CAIR to meet certain regional haze 
requirements, including BART.
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    \12\ The deficiencies resulting from Mississippi's reliance on 
CAIR to satisfy BART relate to those BART determinations and to the 
use of those determinations as an element of the required long-term 
strategy for achieving RPGs. Mississippi's reliance on CAIR did not 
affect its reasonable progress control analysis because the State 
determined in its regional haze SIP that no controls were necessary 
for reasonable progress given the areas of influence and 
consultation with neighboring states. See 77 FR 11879, 11888 
(February 28, 2012) for further information on the reasonable 
progress evaluation.
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B. BART

1. Statutory and Regulatory Requirements
    Section 169A of the CAA directs states to evaluate the use of 
retrofit controls at certain larger, often uncontrolled, older 
stationary sources in order to address visibility impacts from these 
sources. Specifically, section 169A(b)(2) of the CAA requires states to 
revise their SIPs to contain such measures as may be necessary to make 
reasonable progress towards the natural visibility goal, including a 
requirement that certain categories of existing major stationary 
sources built between 1962 and 1977 procure, install, and operate 
``Best Available Retrofit Technology'' as determined by the state. On 
July 6, 2005, EPA published the Guidelines for BART Determinations 
Under the Regional Haze Rule at Appendix Y to 40 CFR part 51 
(hereinafter referred to as the ``BART Guidelines'') to assist states 
in the BART evaluation process. Under the RHR and the BART Guidelines, 
the BART evaluation process consists of three steps: (1) An 
identification of all BART-eligible sources, (2) an assessment of 
whether the BART-eligible sources are subject to BART, and (3) a 
determination of the BART controls.\13\ States must conduct BART 
determinations for all ``BART-eligible'' sources that may reasonably be 
anticipated to cause or contribute to any visibility impairment in a 
Class I area, or in the alternative, adopt an emissions trading program 
or other alternative program as long as the alternative provides 
greater reasonable progress towards improving visibility than BART. In 
making a BART determination for a fossil fuel-fired electric generating 
plant with a total generating capacity in excess of 750 megawatts, a 
state must use the approach set forth in the BART Guidelines. A state 
is generally encouraged, but not required, to follow the BART 
Guidelines in other aspects.
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    \13\ See 40 CFR 51.308(e); BART Guidelines, I.F.
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    In the first step of the BART evaluation process, states are 
required to identify all the BART-eligible sources within their 
boundaries by utilizing the three eligibility criteria in the Act and 
the RHR: (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 was in 
existence on August 6, 1977; and (3) the potential emissions of any 
visibility-impairing pollutant from the units exceed 250 tons per year 
(tpy).\14\ With respect to the third criterion, states must address all 
visibility-impairing pollutants emitted by a BART-eligible source, 
which is the collection of emissions units whose potential to emit for 
a visibility-impairing pollutant is greater than 250 tpy. The most 
significant visibility-impairing pollutants are SO2, 
NOX, and particulate matter (PM).\15\ States should use 
their best judgment in determining whether VOC or NH3 
compounds impair visibility in Class I areas.\16\ Sources that meet all 
three criteria are BART-eligible.
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    \14\ See CAA section 169A(b)(2)(A), (g)(7); 40 CFR 51.301 
(definition of ``Existing stationary facility''); see also BART 
Guidelines, II.
    \15\ See 70 FR 39160.
    \16\ See BART Guidelines, II.A.3, III.A.2.
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    The second phase of the BART evaluation is to identify those BART-
eligible sources that may reasonably be anticipated to cause or 
contribute to visibility impairment at any Class I area, i.e., those 
sources that are subject to BART. Section III of the BART Guidelines 
allows states to exempt BART-eligible sources from further BART review 
(i.e., deem them not subject to BART) via modeling and emissions 
analyses demonstrating that the sources may not reasonably be 
anticipated to cause or contribute to any visibility impairment in any 
Class I area. For such sources, a state need not make a BART 
determination.
    For states using modeling to determine whether single sources are 
subject to BART, the BART Guidelines note that the first step is to set 
a contribution threshold to assess whether the impact of a single 
source is sufficient to cause or contribute to visibility impairment at 
a Class I area.\17\ Under the BART Guidelines, states may select an 
exemption threshold value for their BART modeling below which a BART-
eligible source would not be expected to cause or contribute to 
visibility impairment in any Class I area. The state must document this 
exemption threshold value in the SIP and must state the basis for its 
selection of that value. Any source with emissions that model above the 
threshold value would be subject to a BART determination review. The 
BART Guidelines acknowledge varying circumstances affecting different 
Class I areas. States should consider the number of emissions sources 
affecting the Class I areas at issue and the magnitude of the 
individual sources' impacts. Generally, the exemption threshold set by 
the state should not be higher than 0.5 deciview (dv).\18\ States

[[Page 47137]]

are also free to use a lower threshold if, for instance, they conclude 
that the location of a large number of BART-eligible sources in 
proximity of a Class I area justifies this approach.
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    \17\ See BART Guidelines, III.A.3 (``Option 1: Individual Source 
Attribution Approach (Dispersion Modeling)'').
    \18\ A dv is the unit of measurement on the dv index scale for 
quantifying in a standard manner human perceptions of visibility. 
See 40 CFR 51.301. The BART Guidelines state that ``[a] single 
source that is responsible for a 1.0 deciview change or more should 
be considered to `cause' visibility impairment.'' The BART 
Guidelines also state that ``the appropriate threshold for 
determining whether a source `contributes to visibility impairment' 
may reasonably differ across states,'' but, ``[a]s a general matter, 
any threshold that you use for determining whether a source 
`contributes' to visibility impairment should not be higher than 0.5 
deciviews.'' See BART Guidelines, III.A.1.
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    Once a state has determined which sources are subject to BART, the 
state must determine BART for these sources in the third and final step 
of the BART evaluation process. In making BART determinations, section 
169A(g)(2) of the CAA requires that states consider the following 
factors: (1) The costs of compliance; (2) the energy and non-air 
quality environmental impacts of compliance; (3) any existing pollution 
control technology in use at the source; (4) the remaining useful life 
of the source; and (5) the degree of improvement in visibility which 
may reasonably be anticipated to result from the use of such 
technology. States are free to determine the weight and significance to 
be assigned to each factor, but must reasonably consider all five 
factors.
    A regional haze SIP must include source-specific BART emissions 
limits and compliance schedules for each source subject to BART. Once a 
state has made its BART determination, the BART controls must be 
installed and in operation as expeditiously as practicable, but no 
later than five years after the date of EPA approval of the regional 
haze SIP. See CAA section 169A(g)(4); 40 CFR 51.308(e)(1)(iv). In 
addition to what is required by the RHR, general SIP requirements 
mandate that the SIP must also include all regulatory requirements 
related to monitoring, recordkeeping, and reporting for the BART 
controls on the source. See CAA section 110(a)(2).
2. Draft BART SIP
a. Relationship to EPA's Transport Rules
    Like many other states formerly subject to CAIR, Mississippi had 
relied on CAIR in its regional haze SIP to meet certain requirements of 
EPA's RHR, including BART requirements for emissions of SO2 
and NOX from its BART-eligible EGUs in the State.\19\ This 
reliance was consistent with EPA's regulations at the time that 
Mississippi developed its regional haze SIP. See 70 FR 39104 (July 6, 
2005). However, in 2008, the United States Court of Appeals for the 
District of Columbia Circuit (D.C. Circuit) invalidated CAIR, although 
it ultimately remanded the rule to EPA without vacatur to preserve the 
environmental benefits CAIR provided. See North Carolina v. EPA, 550 
F.3d 1176, 1178 (D.C. Cir. 2008).
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    \19\ In addition to relying on CAIR to satisfy BART 
SO2 and NOX requirements, these sources also 
modeled their coars PM (PM10) emissions and found that 
those emissions do not contribute to visibility impairment in any 
Class 1 area. See 77 FR 11890.
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    On August 8, 2011 (76 FR 48208), acting on the D.C. Circuit's 
remand, EPA promulgated the Cross-State Air Pollution Rule (CSAPR) to 
replace CAIR and issued Federal Implementation Plans (FIPs) to 
implement the rule in CSAPR-subject states.\20\ Although Mississippi 
was covered under CAIR's annual NOX and SO2 
trading programs, only CSAPR's ozone-season NOX program 
applied to the State. See 40 CFR 52.1284.\21\ Implementation of CSAPR 
was scheduled to begin on January 1, 2012, when CSAPR would have 
superseded the CAIR program. However, numerous parties filed petitions 
for review of CSAPR, and at the end of 2011, the D.C. Circuit issued an 
order staying CSAPR pending resolution of the petitions and directing 
EPA to continue to administer CAIR. Order of December 30, 2011, in EME 
Homer City Generation, L.P. v. EPA, D.C. Cir. No. 11-1302. EPA 
ultimately began implementation of CSAPR on January 1, 2015.\22\
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    \20\ CSAPR requires substantial reductions of SO2 and 
NOX emissions from EGUs in 27 states in the Eastern 
United States that significantly contribute to downwind 
nonattainment of the 1997 PM2.5 and ozone NAAQS, 2006 
PM2.5 NAAQS, and the 2008 8-hour ozone NAAQS.
    \21\ See also 76 FR 48208 (Mississippi FIP for 1997 ozone 
NAAQS); 81 FR 74504 (October 26, 2016) (Mississippi FIP for 2008 
ozone 8-hour ozone NAAQS).
    \22\ See 79 FR 71663.
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    During this same timeframe, EPA also finalized a limited approval 
and a limited disapproval of the Mississippi regional haze SIP in June 
2012 because of deficiencies in the regional haze SIP arising from the 
State's reliance on CAIR as an alternative to BART for the State's 
BART-eligible EGUs.\23\ See 77 FR 38191 (June 27, 2012) (limited 
approval); 77 FR 33642 (June 7, 2012) (limited disapproval). In the 
limited disapproval action, EPA did not subject Mississippi to a FIP. 
Mississippi had requested that EPA not issue a FIP and instead provide 
the State with additional time to correct the deficiencies in its 
regional haze SIP through a SIP revision.\24\
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    \23\ The State's analysis of reasonable progress controls was 
not dependent on CAIR, and thus not affected by CAIR's invalidation. 
See 77 FR 11879, 11888 (February 28, 2012) (finding no controls were 
necessary for reasonable progress given the areas of influence and 
consultation with neighboring states).
    \24\ See 77 FR 33654.
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    Accordingly, Mississippi began working on a new SIP submission to 
address the limited disapproval of the State's regional haze SIP and 
the change from CAIR and CSAPR. One important impact of the transition 
from CAIR to CSAPR was that Mississippi previously relied on CAIR as an 
alternative to BART for both SO2 and NOX because 
it participated in trading programs for both pollutants under CAIR; 
however, because Mississippi is only part of the CSAPR seasonal 
NOX program (and not part of the SO2 program), it 
could not rely on CSAPR to satisfy BART for SO2. Thus, the 
State worked with the BART-eligible EGUs formerly subject to CAIR to 
determine how these facilities would now address BART.\25\ These 14 
BART-eligible units are located at the following seven facilities:
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    \25\ EPA previously approved the State's identification of BART-
eligible sources in its limited approval action. EPA is not 
reexamining these BART-eligibility findings in this rulemaking, and 
any comments on this issue are beyond the scope of this notice.
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     Cooperative Energy \26\--Plant Moselle (Plant Moselle);
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    \26\ Cooperative Energy was formerly known as South Mississippi 
Electric Power Association.
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     Cooperative Energy--R. D. Morrow Sr. Generating Plant 
(Plant Morrow);
     Entergy Mississippi, Inc.--Baxter Wilson Plant (Baxter 
Wilson);
     Entergy Mississippi, Inc.--Gerald Andrus Plant (Gerald 
Andrus);
     Mississippi Power Company--Plant Chevron (Plant Chevron);
     Mississippi Power Company--Plant Daniel (Plant Daniel); 
and
     Mississippi Power Company--Plant Watson (Plant Watson).
    As explained further in Section III of this notice, the draft BART 
SIP proposes to find that these 14 BART-eligible EGUs are exempt from 
BART because visibility modeling and/or supplemental analyses 
demonstrate that they are not reasonably anticipated to cause or 
contribute to visibility impairment in any Class I area.
b. Pollutants Addressed
    As described earlier, the BART Guidelines direct states to address 
SO2, NOX, and direct PM (including both 
PM10 and PM2.5) emissions as visibility-impairing 
pollutants, and to exercise judgment in determining whether VOC or 
NH3 emissions from a source impair visibility in an area. 
See 70 FR 39160. Mississippi had previously determined that VOC from 
anthropogenic sources and NH3 from point sources are not 
significant visibility-impairing pollutants in Mississippi for the 
first implementation period. The State continues to rely on these 
findings in its draft BART SIP. EPA previously approved these findings 
in our earlier limited approval, and the Agency is not

[[Page 47138]]

reexamining this issue in this rulemaking.\27\
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    \27\ See 77 FR 11887-88 (discussing analysis by the State and 
the Visibility Improvement State and Tribal Association of the 
Southeast (VISTAS)).
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c. Dispersion Modeling Methodology
    Consistent with the BART Guidelines, Mississippi requested that 
each of its seven BART-eligible facilities formerly subject to CAIR 
develop and submit dispersion modeling to assess the extent of their 
contribution to visibility impairment at surrounding Class I areas. The 
BART Guidelines allow states to use the CALPUFF \28\ modeling system 
(CALPUFF) or another appropriate model to predict the visibility 
impacts from a single source on a Class I area, and therefore, to 
determine whether an individual source may reasonably be anticipated to 
cause or contribute to impairment of visibility in Class I areas (i.e., 
whether it is subject to BART). The BART Guidelines also recommend that 
states develop a modeling protocol for making individual source 
attributions.
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    \28\ EPA's reference to CALPUFF encompasses the entire CALPUFF 
modeling system, which includes the CALMET, CALPUFF, and CALPOST 
models and other pre and post processors. The different versions of 
CALPUFF have corresponding versions of CALMET, CALPOST, etc. which 
may not be compatible with previous versions (e.g., the output from 
a newer version of CALMET may not be compatible with an older 
version of CALPUFF). The different versions of the CALPUFF modeling 
system are available from the model developer at: http://www.src.com/calpuff/download/download.htm.
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    The VISTAS states, including Mississippi, developed a ``Protocol 
for the Application of CALPUFF for BART Analyses'' (VISTAS BART 
Modeling Protocol).\29\ Mississippi, in coordination with VISTAS, used 
this modeling protocol to apply CALPUFF to determine whether individual 
sources in Mississippi were subject to or exempt from BART. EPA 
previously approved the use of this modeling methodology by 
Mississippi,\30\ and the Agency believes that the continued use of this 
modeling methodology in the draft BART SIP remains appropriate.
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    \29\ The VISTAS BART Modeling Protocol, December 22, 2005, 
Revision 3.2 (August 31, 2006), is included in Appendix L.8 of the 
BART SIP.
    \30\ See 77 FR 11888-89.
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d. Contribution Threshold
    In its prior regional haze submissions, MDEQ used a contribution 
threshold of 0.5 dv for determining which BART-eligible units 
(including the 14 units addressed by the draft BART SIP) are subject to 
BART. EPA previously approved the use of this 0.5 dv BART contribution 
threshold, and the Agency is not reexamining this issue in this 
rulemaking.\31\
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    \31\ The factors supporting the Agency's original approval of 
the 0.5 dv BART contribution threshold have not changed. See 77 FR 
11889 (Feb. 28, 2012). In fact, there are now fewer BART-eligible 
sources (due to the removal of all BART-eligible units at Plant 
Morrow and Unit 2 at Baxter Wilson) and less visibility-impairing 
pollutants emitted from BART-eligible sources than existed in the 
record at the time of EPA's earlier limited approval (due to 
SO2 scrubbers installed at Plant Daniel and removal of 
fuel oil burning capabilities for Unit 1 at Gerald Andrus and Unit 1 
at Baxter Wilson). These changes are discussed further in Section 
III of this notice.
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C. Progress Report Requirements

    The RHR requires each state to submit progress reports that 
evaluate progress towards the RPGs for each mandatory Class I area 
within the state and for each Class I area outside the state which may 
be affected by emissions from within the state. See 40 CFR 51.308(g). 
In addition, the provisions of 40 CFR 51.308(h) require a state to 
submit, at the same time as each progress report, a determination of 
the adequacy of the state's existing regional haze plan. The first 
progress report is due five years after submittal of the initial 
regional haze plan and must be submitted as a SIP revision. Mississippi 
submitted its progress report for the first implementation period to 
EPA on October 4, 2018.

III. Summary and EPA's Evaluation of Mississippi's BART SIP

A. Summary of Mississippi's BART SIP

    The draft BART SIP sets forth MDEQ's subject-to-BART determinations 
for the BART-eligible sources formerly subject to CAIR, and finds that 
none of these sources is subject to BART. Table 1 identifies these 
BART-eligible sources, the highest modeled impact at the Class I area 
nearest each source,\32\ and the State's determination regarding 
whether the sources are subject to BART.
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    \32\ MDEQ followed the VISTAS BART Modeling protocol which 
specifies that BART exemption modeling should be performed for Class 
I areas located within 300 km of each BART-eligible source. The 
Class I areas listed in Table 1 are the only Class I areas located 
within 300 km of each BART-eligible source with the exception of 
Baxter Wilson, which has no Class I areas within 300 km and is 
located 310 km from Breton.

                               Table 1--Mississippi EGUs Subject-to-BART Modeling
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                                                                             Maximum 24-
                                                                              hour 98th
                                     BART-eligible                           percentile
           Facility name                 units       Nearest Class I Area    visibility       Subject to BART?
                                                                             impact \33\
                                                                                (dv)
----------------------------------------------------------------------------------------------------------------
Baxter Wilson.....................            1, 2  Breton Wilderness               0.49*  No.
                                                     Area (Breton) (LA).
Gerald Andrus.....................               1  Caney Creek                     0.15*  No.
                                                     Wilderness Area
                                                     (Caney Creek) (AR).
Plant Chevron.....................      1, 2, 3, 4  Breton (LA)..........            0.27  No.
Plant Daniel......................            1, 2  Breton (LA)..........            0.39  No.
Plant Morrow......................            1, 2  Breton (LA)..........           N/A**  N/A**.
Plant Moselle.....................               3  Breton (LA)..........            0.05  No.
Plant Watson......................            4, 5  Breton (LA)..........            0.44  No.
----------------------------------------------------------------------------------------------------------------
* These visibility impacts for Baxter Wilson and Gerald Andrus are based on burning natural gas only as these
  facilities have removed the ability to burn fuel oil at Unit 1 for each facility. In addition, as explained
  further below, the visibility impact for Baxter Wilson was modeled based on emissions from both Unit 1 and
  Unit 2, but Unit 2 at Baxter Wilson has since been removed.
** ``N/A'' indicates that there is no visibility impact from Plant Morrow Units 1 and 2 because these BART-
  eligible units were removed from service.

[[Page 47139]]

     
---------------------------------------------------------------------------

    \33\ EPA's BART Guidelines recommend comparing visibility 
improvements between control options using the 98th percentile of 
24-hour delta dv, which is equivalent to the facility's 8th highest 
visibility impact day. See 70 FR 39162 (July 6, 2005). The 98th 
percentile is recommended rather than the maximum value to allow for 
uncertainty in the modeled impacts and to avoid undue influence from 
unusual meteorological conditions. The ``delta'' refers to the 
difference between total dv impact from the facility plus natural 
background, and dv of natural background alone, so ``delta 
deciviews'' is the estimate of the facility's impact relative to 
natural visibility conditions. The VISTAS BART Modeling Protocol 
interprets EPA's recommended use of the 98th percentile value as the 
highest of the three annual 98th percentile values at a particular 
Class I area or the 22nd highest value in the combined 3-year 
period, whichever is more conservative (p.14).
---------------------------------------------------------------------------

    The original modeling for each of these plants was generally 
performed in the early 2010s, using data from an earlier period (e.g., 
2001-03 or 2003-05) and earlier versions of the CALPUFF model. For four 
facilities (Baxter Wilson, Gerald Andrus, Plant Chevron, and Plant 
Moselle), the State supplemented the original modeling with new 
analyses of emissions changes for SO2, NOX, and 
PM10 \34\ since the BART baseline period. For each plant, 
recent emissions have either remained roughly equivalent to or 
decreased relative to the baseline period modeled. Accordingly, the 
State concluded that the prior modeling results remain valid for 
determining whether the sources are subject to BART.\35\
---------------------------------------------------------------------------

    \34\ PM10 includes PM2.5, thus, MDEQ 
evaluated PM10 emissions data in the supplemental 
emissions analyses in the draft BART SIP.
    \35\ In addition, as further explained in Section III.B.2, EPA 
has also evaluated the potential impacts of updates to the CALPUFF 
model, and found that such updates are unlikely to result in 
significantly different visibility impacts.
---------------------------------------------------------------------------

    For Plant Daniel and Plant Watson, the sources conducted updated 
modeling with recent emissions data and the current version of CALPUFF. 
Finally, Plant Morrow's BART-eligible units are permanently retired, 
and thus there is no need to determine whether this source is subject 
to BART.
    The following subsections discuss in more detail MDEQ's assessment 
of the BART exemption modeling for each of the seven facilities.
1. Mississippi Power Company--Chevron Cogenerating Plant Units 1, 2, 3, 
and 4
    Units 1, 2, 3, and 4 at Plant Chevron, located in Pascagoula, 
Mississippi, and owned and operated by Mississippi Power Company, have 
been identified by MDEQ as BART-eligible. Plant Chevron is located 
approximately 48 km north of Breton. Plant Chevron is an electric 
generating facility with four gas-fired combined cycle turbines. All 
four units each have the potential to emit more than 250 tpy of 
NOX emissions. Plant Chevron performed CALPUFF modeling in 
2011 on these four units utilizing CALPUFF version 5.754 Level 060202. 
The modeling analysis predicted a maximum annual 98th percentile 24-
hour average visibility impact of 0.27 dv over the three years modeled 
on Breton, and a 22nd highest day's visibility impact over all three 
years of 0.24 dv.
    As explained previously, because the original modeling was 
conducted years ago, MDEQ also performed a supplemental emissions 
analysis for this facility. MDEQ compared more current (2016-2018) 
SO2, NOX, and PM10 emissions values 
from annual emissions reports submitted by Plant Chevron with the 2003-
2005 baseline emissions values and showed that recent emissions have 
remained roughly equivalent to or decreased relative to the baseline 
period modeled. Therefore, MDEQ concluded that it is not necessary to 
remodel using recent emissions. Table 2 compares the maximum 24-hour 
emissions rates for 2003-2005 that were modeled in 2011 against updated 
maximum 24-hour emissions rates for 2016-2018. The State found that: 
(1) The maximum SO2 emissions rates from all four units 
combined were slightly higher, but still quite low, in the updated 
period compared to the baseline period (approximately 8 pounds per hour 
(lb/hr) vs 4 lb/hr); (2) the maximum NOX emissions rates 
from all four units combined were significantly lower in the updated 
period compared to the baseline period (approximately 420 lb/hr vs 558 
lb/hr); and (3) the maximum PM10 emissions rates from all 
four units combined were approximately the same (9 lb/hr). The 2011 
CALPUFF modeling found that most of the visibility impact from this 
facility was from nitrates, so the recent decrease in NOX 
emissions would suggest a corresponding decrease in visibility impact 
on Breton.
    In addition, Table 3 compares the annual 2003-2005 baseline 
emissions of SO2, NOX, and PM10 to 
2016-2018 annual emissions. Annual emissions are not an input into 
CALPUFF modeling, but MDEQ elected to consider them. The annual 
emissions comparison provides a general indication of overall trends in 
emissions between the baseline period that was used in the 2011 
modeling and more recent emissions. The annual emissions of 
NOX and SO2 are higher in the 2016-2018 period 
and PM10 emissions are lower.

                                Table 2--Plant Chevron Modeled (2003-2005) and 2016-2018 Maximum 24-Hour Emissions Rates
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                          Maximum 24-hour emissions rates (lb/hr) (2003-  Maximum 24-hour emissions rates (lb/hr) (2016-
                                                                               2005)                                           2018)
                      Emission unit                      -----------------------------------------------------------------------------------------------
                                                                SO2             NOX            PM10             SO2             NOX            PM10
--------------------------------------------------------------------------------------------------------------------------------------------------------
Unit 1..................................................            0.75          119.58            1.90            0.17           90.91            1.88
Unit 2..................................................            0.78          122.64            1.95            0.17           88.84            1.83
Unit 3..................................................            1.00          159.23            2.55            4.11          119.64            2.47
Unit 4..................................................            0.98          156.84            2.50            3.66          120.56            2.49
                                                         -----------------------------------------------------------------------------------------------
    Total...............................................            3.51          558.29            8.90            8.11          419.95            8.67
--------------------------------------------------------------------------------------------------------------------------------------------------------

     Table 3--Plant Chevron Baseline (2001-2003) and Current (2016-2018) Period Annual Emissions Comparison
----------------------------------------------------------------------------------------------------------------
                                                                     Combined annual emission (tons) units 1-4
                              Year                               -----------------------------------------------
                                                                        SO2             NOX            PM10
----------------------------------------------------------------------------------------------------------------
2001............................................................            1.61        1,238.26           66.14

[[Page 47140]]

 
2002............................................................            1.55        1,181.77           62.59
2003............................................................            1.44        1,264.50           67.65
2016............................................................            8.01        1,430.36           29.50
2017............................................................            7.77        1,274.89           26.30
2018............................................................            5.76        1,240.95           26.11
----------------------------------------------------------------------------------------------------------------

    In sum, MDEQ concluded that Plant Chevron Units 1, 2, 3, and 4 are 
not subject to BART, and thus, no further BART analysis is required 
because Plant Chevron's 2011 modeling found that its visibility impact 
was 0.27 dv which is significantly less than 0.5 dv, and there have 
been no significant increases in SO2, NOX, or 
PM10 emissions since the modeled baseline period. 
Specifically, there have been no significant increases in the maximum 
24-hour SO2 nor PM10 emissions rates, and the 
maximum 24-hour NOX emissions rates have declined.
2. Mississippi Power Company--Plant Victor J Daniel Units 1 and 2
    Units 1 and 2 at Plant Daniel, located in Escatawpa, Mississippi, 
and owned and operated by Mississippi Power Company, have been 
identified by MDEQ as BART-eligible. Plant Daniel is approximately 63 
km northeast of Breton. Plant Daniel is an electric generating facility 
with two coal-fired steam EGUs. Each of the units have the potential to 
emit over 250 tpy of SO2, NOX, and 
PM10. Plant Daniel controls SO2 emissions from 
these units through scrubbers (i.e., wet flue gas desulfurization (FGD) 
systems) installed to comply with EPA's Mercury and Air Toxics 
Standards (MATS).\36\ Scrubber operation began in September 2015. 
Mississippi Power Company performed updated CALPUFF modeling on Units 1 
and 2 using recent emissions data (i.e., from September 2015-August 
2018) and the current EPA-approved version of CALPUFF. The modeling 
analysis predicted a maximum annual 98th percentile 24-hour average 
visibility impact of 0.39 dv over the three years modeled, and a 22nd 
highest day's visibility impact over all three years of 0.33 dv. MDEQ 
concluded that Plant Daniel's Units 1 and 2 are not subject to BART, 
and thus, no further BART analysis is required because the 98th 
percentile 24-hour average visibility impact of 0.39 dv is below the 
State's 0.5 dv contribution threshold for BART.
---------------------------------------------------------------------------

    \36\ See June 15, 2020, email from MDEQ to EPA Region 4 that 
includes an October 30, 2015 title V permit renewal application 
addendum for Plant Daniel addressing MATS requirements. These 
documents are included in the docket for this proposed action.
---------------------------------------------------------------------------

3. Entergy Mississippi Inc.--Baxter Wilson Plant Units 1 and 2
    Units 1 and 2 at Baxter Wilson, located in Vicksburg, Mississippi, 
and owned and operated by Entergy Mississippi, Inc., have been 
identified by MDEQ as BART-eligible. Baxter Wilson is located 
approximately 310 km northwest of Breton. Baxter Wilson is an electric 
generating facility that currently has one natural gas-fired unit (Unit 
1). The initial CALPUFF modeling was performed in 2012 with CALPUFF 
version 5.8 Level 070623. The modeling used the maximum 24-hour 
emissions rates over the three-year baseline period of 2001-2003 
assuming that both Units 1 and 2 fired only natural gas. This modeling 
indicated a maximum 98th percentile 24-hour impact of 0.49 dv over the 
three years modeled and a 22nd highest day's visibility impact over all 
three years of 0.39 dv, both of which are below the contribution 
threshold of 0.5 dv.
    Since the modeling was performed, the facility has undergone 
changes. Unit 1 at Baxter Wilson originally was a dual fuel oil and 
gas-fired unit, but the fuel oil tanks have been rendered unusable, and 
the capability to burn fuel oil is in the process of being removed.\37\ 
Unit 2, the larger unit, permanently retired thereby reducing 
SO2, NOX, and PM emissions from the plant.\38\ 
Given these changes and the fact that the original modeling was 
conducted years ago, MDEQ also performed a supplemental emissions 
analysis for this facility. MDEQ compared more current (2016-2018) 
SO2, NOX, and PM10 emissions values 
from annual emissions reports submitted by Baxter Wilson with the 2001-
2003 baseline emissions values and showed that recent emissions have 
remained roughly equivalent to or decreased relative to the baseline 
period modeled. Therefore, MDEQ concluded that it is not necessary to 
remodel using recent emissions. Table 4 compares the maximum 24-hour 
emissions rates for 2001-2003 that were modeled with updated rates for 
2016-2018. Because the facility can no longer burn fuel oil, all 
emissions values in Table 4 reflect the burning of natural gas. The 
State found that the combined current emissions rates from Units 1 and 
2 have decreased considerably relative to the baseline values modeled 
for SO2, NOX, and PM10 because Unit 2 
has shut down. In particular, current NOX emissions rates 
are approximately one-fifth of the modeled emissions rates.
---------------------------------------------------------------------------

    \37\ See May 27, 2020, email from MDEQ to EPA Region 4 that 
includes a September 8, 2019, letter providing an update on the 
removal of fuel oil capabilities at Gerald Andrus and Baxter Wilson. 
These documents are included in the docket for this proposed action.
    \38\ Unit 2 at Baxter Wilson was decommissioned in June 2018. A 
copy of the Acid Rain and CSAPR Trading Programs Retired Unit 
Exemption Form is located in Appendix L.7.2 of the draft BART SIP.
---------------------------------------------------------------------------

    In addition, Table 5 compares the annual baseline emissions of 
2001-2003 to 2016-2018 annual emissions. Table 5 reflects annual 
emissions from burning both natural gas and fuel oil. MDEQ concludes 
that the current annual emissions are much less than the baseline 
emissions for all pollutants.

[[Page 47141]]

                        Table 4--Baxter Wilson Modeled 2001-2003 and 2016-2018 Maximum 24-Hour Emissions Rates--Natural Gas Only
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                          Maximum 24-hour emissions rates (lb/hr) (2001-  Maximum 24-hour emissions rates (lb/hr) (2016-
                                                                               2003)                                           2018)
                      Emission unit                      -----------------------------------------------------------------------------------------------
                                                                SO2             NOX            PM10             SO2             NOX            PM10
--------------------------------------------------------------------------------------------------------------------------------------------------------
Unit 1..................................................            2.71           2,030           35.69            3.67           1,337           36.17
Unit 2..................................................            2.40           4,674           49.77               0               0               0
                                                         -----------------------------------------------------------------------------------------------
    Total...............................................            5.11           6,704           85.46            3.67           1,337           36.17
--------------------------------------------------------------------------------------------------------------------------------------------------------

 Table 5--Baxter Wilson Baseline (2001-2003) and Current (2016-2018) Period Annual Emissions Comparison--Natural
                                                Gas and Fuel Oil
----------------------------------------------------------------------------------------------------------------
                                                                          Combined annual emission (tons)
                              Year                               -----------------------------------------------
                                                                        SO2             NOX            PM10
----------------------------------------------------------------------------------------------------------------
2001............................................................       34,117.18       14,274.82        2,796.09
2002............................................................            8.34        6,375.26          102.94
2003............................................................            1.99        1,325.02           24.51
2016............................................................            2.49        1,550.71           25.19
2017............................................................            2.65          794.41           25.06
2018............................................................            3.08        1,111.63           34.08
----------------------------------------------------------------------------------------------------------------

    MDEQ concluded that Baxter Wilson is not subject to BART, and no 
further BART analysis is required because the maximum 98th percentile 
24-hour average visibility impact of 0.49 dv is below the State's 0.5 
dv contribution threshold for BART, and recent maximum 24-hour 
emissions rates and annual emissions of SO2, NOX, 
and PM have declined since the 2001-2003 modeled baseline period.
4. Entergy Mississippi Inc.--Gerald Andrus Plant Unit 1
    Gerald Andrus Unit 1, located in Greenville, Mississippi, and owned 
and operated by Entergy Mississippi, Inc., has been identified by MDEQ 
as BART-eligible. Gerald Andrus is located approximately 290 km east of 
Caney Creek. Gerald Andrus is an electric generating facility that 
currently has one natural gas-fired unit (Unit 1). The initial CALPUFF 
modeling performed in 2012 for Unit 1 using CALPUFF Version 5.8 Level 
070623 was based on Unit 1 only firing natural gas. This modeling 
demonstrated a maximum 98th percentile 24-hour average visibility 
impact over the three years modeled of 0.15 dv and a 22nd highest day's 
visibility impact over all three years of 0.12 dv based on burning 
natural gas.
    As with Baxter Wilson, the facility has undergone changes since the 
original modeling. Namely, Unit 1 at Gerald Andrus originally was a 
dual fuel oil- and gas-fired unit. As of April 23, 2020, Gerald Andrus 
removed the capability to utilize fuel oil.\39\ Given this change and 
the fact that the original modeling was conducted years ago, MDEQ also 
performed a supplemental emissions analysis for this facility. MDEQ 
compared more current (2016-2018) SO2, NOX, and 
PM10 emissions values from annual emissions reports 
submitted by Gerald Andrus with the 2001-2003 baseline emissions values 
and showed that recent emissions have remained roughly equivalent to or 
decreased relative to the baseline period modeled. Therefore, MDEQ 
concluded that it is not necessary to remodel using recent emissions. 
The comparison of 2001-2003 modeled maximum 24-hour emissions rates to 
updated 2016-2018 maximum 24-hour emissions rates of SO2, 
NOX, and PM10 is shown in Table 6. Because the 
facility has removed the ability to burn fuel oil, all emissions values 
in Table 6 reflect the burning of natural gas. The State's evaluation 
found that the maximum 24-hour SO2 emissions rates from 
2016-2018 were essentially the same as the modeled value (approximately 
3.8 lb/hr vs. 3.7 lb/hr), and that recent maximum 24-hour 
PM10 and NOX emissions rates were less than the 
modeled emissions rates. In addition, Table 7 compares the annual 2001-
2003 baseline emissions to 2016-2018 annual emissions of 
SO2, NOX, and PM10. Table 7 reflects 
annual emissions from burning both natural gas and fuel oil. MDEQ 
concluded that the current annual emissions are much less than the 
baseline emissions for all pollutants.
---------------------------------------------------------------------------

    \39\ See May 27, 2020, email from MDEQ to EPA Region 4 with a 
September 8, 2019, letter providing an update on the removal of fuel 
oil capabilities at Gerald Andrus and Baxter Wilson. These documents 
are included in the docket for this proposed action.

[[Page 47142]]

                        Table 6--Gerald Andrus Modeled 2001-2003 and 2016-2018 Maximum 24-Hour Emissions Rates--Natural Gas Only
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                          Maximum 24-hour emissions rates (lb/hr) (2001-  Maximum 24-hour emissions rates (lb/hr) (2016-
                                                                               2003)                                           2018)
                      Emission unit                      -----------------------------------------------------------------------------------------------
                                                                SO2             NOX            PM10             SO2             NOX            PM10
--------------------------------------------------------------------------------------------------------------------------------------------------------
Unit 1..................................................            3.66           3,971            54.2            3.83           1,813           47.13
--------------------------------------------------------------------------------------------------------------------------------------------------------

 Table 7--Gerald Andrus Baseline (2001-2003) and Current (2016-2018) Period Annual Emissions Comparison--Natural
                                                Gas and Fuel Oil
----------------------------------------------------------------------------------------------------------------
                                                                          Combined annual emission (tons)
                              Year                               -----------------------------------------------
                                                                        SO2             NOX            PM10
----------------------------------------------------------------------------------------------------------------
2001............................................................       32,725.12        8,417.70        2,108.27
2002............................................................            8.44        4,809.19          103.72
2003............................................................       12,568.21        6,626.94        1,096.43
2016............................................................            2.22          763.67           26.36
2017............................................................            1.53          436.82           17.26
2018............................................................            3.15        1,138.78           36.39
----------------------------------------------------------------------------------------------------------------

    MDEQ concluded that Gerald Andrus is not subject to BART, and no 
further BART analysis is required because the 98th percentile 24-hour 
average visibility impact of 0.15 dv is well below the State's 0.5 dv 
threshold contribution for BART, 2016-2018 annual emissions of 
SO2, NOX, and PM have declined from 2001-2003 
levels, and the maximum 24-hour emissions rates of SO2, 
NOX, and PM10 have remained equivalent to 
(SO2) or lower than (NOX and PM10) 
those in the 2001-2003 modeled baseline period.
5. Cooperative Energy--R. D. Morrow Sr. Generating Plant Units 1 and 2
    Plant Morrow Units 1 and 2, located in Purvis, Mississippi, and 
owned and operated by Cooperative Energy, were previously identified by 
MDEQ as BART-eligible. Plant Morrow is located approximately 138 km 
from Breton. On November 17, 2018, Units 1 and 2 were permanently 
retired.\40\ MDEQ concluded that there are no other units at Plant 
Morrow that are BART-eligible, and therefore, the facility has no 
further BART obligations.
---------------------------------------------------------------------------

    \40\ A copy of the Acid Rain and CSAPR Trading Programs Retired 
Unit Exemption Form is located in Appendix L.4.2 of the draft BART 
SIP.
---------------------------------------------------------------------------

6. Cooperative Energy--Plant Moselle Unit 3
    Plant Moselle Unit 3, located in Moselle, Mississippi, and owned 
and operated by Cooperative Energy, has been identified by MDEQ as 
BART-eligible. Plant Moselle is located approximately 170 km north of 
Breton. Plant Moselle is an electric generating facility that currently 
has one natural gas-fired unit (Unit 3). Plant Moselle conducted 
CALPUFF modeling for Unit 3 in 2011 using CALPUFF Version 5.8 Level 
070623. The modeling analysis demonstrated a maximum 98th percentile 
24-hour average visibility impact over the three years modeled of 0.05 
dv, and a 22nd highest day's visibility impact over all three years of 
0.042 dv.
    Given that the original modeling was conducted years ago, MDEQ also 
performed a supplemental emissions analysis for this facility. MDEQ 
compared more current (2016-2018) SO2, NOX, and 
PM10 emissions values from annual emissions reports 
submitted by Plant Moselle with the 2001-2003 baseline emissions values 
and showed that recent emissions have remained roughly equivalent to or 
decreased relative to the baseline period modeled. Therefore, MDEQ 
concluded that it is not necessary to remodel using recent emissions. 
The comparison of modeled 2001-2003 maximum 24-hour emissions rates of 
SO2, NOX, and PM10 to updated 2016-
2018 maximum 24-hour emissions rates is shown in Table 8. The State's 
evaluation found that the 2016-2018 maximum 24-hour SO2 
emissions rate was equivalent to the modeled value (0.25 lb/hr vs. 0.24 
lb/hr). MDEQ notes maximum 24-hour average NOX and 
PM10 emissions rates from 2016-2018 are less than the 
modeled emissions rates. In addition, Table 9 compares the annual 2001-
2003 baseline emissions of SO2, NOX, and 
PM10 to 2016-2018 annual emissions. MDEQ concluded that the 
2016-2018 annual emissions of SO2, NOX, and 
PM10 are less than the baseline emissions.

                                 Table 8--Plant Moselle Modeled 2001-2003 and 2016-2018 Maximum 24-Hour Emissions Rates
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                          Maximum 24-hour emissions rates emissions (lb/  Maximum 24-hour emissions rates emissions (lb/
                                                                          hr) (2001-2003)                                 hr) (2016-2018)
                 Emissions period (date)                 -----------------------------------------------------------------------------------------------
                                                                SO2             NOX            PM10             SO2             NOX            PM10
--------------------------------------------------------------------------------------------------------------------------------------------------------
Unit 3..................................................            0.24          245.25            6.50            0.25          217.25            3.21
--------------------------------------------------------------------------------------------------------------------------------------------------------

[[Page 47143]]

     Table 9--Plant Moselle Baseline (2001-2003) and Current (2016-2018) Period Annual Emissions Comparison
----------------------------------------------------------------------------------------------------------------
                                                                              Annual emissions (tons)
                              Year                               -----------------------------------------------
                                                                        SO2             NOX            PM10
----------------------------------------------------------------------------------------------------------------
2001............................................................            0.85          249.56            6.59
2002............................................................            0.63          317.39            7.80
2003............................................................            0.56          344.65            6.93
2016............................................................            0.11           56.35            1.37
2017............................................................            0.09           43.42            1.14
2018............................................................            0.11           58.79            1.36
----------------------------------------------------------------------------------------------------------------

    MDEQ concluded that Plant Moselle is not subject to BART, and no 
further BART analysis is required because the 98th percentile 24-hour 
average visibility impact of 0.05 dv is well below the State's 0.5 dv 
contribution threshold for BART, 2016-2018 annual emissions of 
SO2, NOX, and PM10 have declined from 
2001-2003 levels, and maximum 24-hour emissions rates of 
SO2, NOX and PM10 have remained 
equivalent to (SO2) or declined (NOX and 
PM10) since the 2001-2003 baseline period modeled.
7. Mississippi Power Company--Plant Watson Units 4 and 5
    Plant Watson Units 4 and 5, located in Gulfport, Mississippi, and 
owned and operated by Mississippi Power Company, have been identified 
by MDEQ as being BART-eligible. Plant Watson is 45 km from Breton. 
Plant Watson is an electric generating facility that has two natural-
gas fired units (Units 4 and 5). These units were previously capable of 
firing coal and fuel oil. Plant Watson conducted CALPUFF modeling in 
2012 for Units 4 and 5 using CALPUFF Version 5.8 Level 070623 and 
assuming that these units would convert to firing only natural gas. The 
modeling analysis demonstrated a maximum 98th percentile 24-hour 
average visibility impact of 0.48 dv over the three years modeled, and 
a 22nd highest day's visibility impact over all three years of 0.46 dv. 
Since the 2012 CALPUFF modeling was conducted, Units 4 and 5 were 
modified in 2015 by removing all liquid burning equipment and 
dismantling the coal handling systems. Now both units are physically 
limited to burn natural gas only.\41\ Although the 2012 modeled values 
are below the State's contribution threshold for sources that are 
subject to BART, these changes at Plant Watson reduced annual emissions 
of visibility-impairing pollutants such that the source elected to 
model using more recent emissions. On behalf of Mississippi Power 
Company, Southern Company Services performed updated CALPUFF modeling 
on Units 1 and 2 using current emissions (i.e., 2017-2019) and the 
current EPA-approved version of CALPUFF. The modeling analysis 
predicted a maximum annual 98th percentile 24-hour average visibility 
impact of 0.44 dv over the three years modeled, and a 22nd highest 
day's visibility impact over all three years of 0.41 dv. MDEQ concluded 
that Plant Watson's Units 4 and 5 are not subject to BART, and thus, no 
further BART analysis is required because the 98th percentile 24-hour 
average visibility impact of 0.44 dv is below the State's 0.5 dv 
contribution threshold for BART.
---------------------------------------------------------------------------

    \41\ In an April 9, 2015, letter to MDEQ, Mississippi Power 
Company requested a modification to its title V permit for Plant 
Watson to reflect actions to render Units 4 and 5 incapable of 
combusting any solid or liquid fuels. These activities included the 
removal of liquid fuel burning equipment and the permanent 
dismantlement of the coal handling system. MDEQ issued a revised 
title V permit and acid rain permit on December 29, 2016. These 
documents are located in the docket for this proposed action for 
informational purposes.
---------------------------------------------------------------------------

B. EPA's Evaluation of Mississippi's BART SIP

1. Overview
    EPA proposes to find that the draft BART SIP corrects the 
deficiencies arising from Mississippi's prior reliance on CAIR to meet 
certain regional haze requirements that resulted in EPA's limited 
disapproval of Mississippi's regional haze plan. Because this was the 
sole deficiency leading to EPA's prior limited disapproval, the Agency 
is also proposing to withdraw that limited disapproval and to fully 
approve the State's regional haze SIP.
    As discussed above, Plant Morrow's BART-eligible Units 1 and 2 
permanently retired in 2018, and EPA therefore proposes to approve the 
State's finding that this source is exempt from further BART analysis. 
The remaining six facilities all modeled below the State's BART 
contribution threshold of 0.5 dv. As explained previously, modeling for 
four facilities (Baxter Wilson, Gerald Andrus, Plant Chevron, and Plant 
Moselle) was conducted in the early 2010s with earlier versions of 
CALPUFF. For these facilities, EPA evaluated potential impacts of 
changes to the CALPUFF modeling system, and, as discussed in Section 
III.B.2, EPA believes that the modeling system changes do not 
significantly affect the modeling results for these sources. In 
addition, EPA agrees with the State's analyses of the modeling results 
and the supplemental emissions analyses, as discussed in Section 
III.B.3, below. Thus, EPA proposes to approve the State's determination 
that Baxter Wilson, Gerald Andrus, Plant Chevron, Plant Daniel, Plant 
Moselle, and Plant Watson are not subject to BART, and no further BART 
analysis is required of these sources.
2. Assessment of CALPUFF Modeling System Changes
    MDEQ opted to rely on existing BART exemption modeling for four 
sources, Baxter Wilson, Gerald Andrus, Plant Chevron, and Plant 
Moselle, which utilized older versions of the CALPUFF modeling system. 
For this reason, EPA assessed whether the updates to the CALPUFF 
modeling system could affect the modeling results for these four 
sources such that they would become subject to BART. EPA first 
considered the changes to the CALPUFF modeling system and an earlier 
analysis prepared by an EPA contractor, and found that these changes 
are generally unlikely to result in significant differences in modeled 
visibility impacts. Second, EPA analyzed Plant Watson's modeling 
results under both the current CALPUFF model and the older version of 
the model used by Baxter Wilson, Gerald Andrus, and Plant Moselle. This 
analysis accounts for the significant similarities between the 
emissions profiles of Plant Watson and the other plants, and further 
corroborates that using the updated CALPUFF model is unlikely to result 
in the other plants becoming subject to BART. Thus, EPA proposes to 
find that it is not necessary

[[Page 47144]]

to remodel Baxter Wilson, Gerald Andrus, Plant Chevron, and Plant 
Moselle using the current EPA-approved version of CALPUFF.
CALPUFF Modeling System Versions Used for Mississippi's BART-Eligible 
Sources
    The initial BART exemption modeling utilized CALPUFF and CALMET 
Version 5.8 Level 070623 for all sources except Plant Chevron, which 
utilized CALPUFF version 5.754 Level 060202 and CALMET version 5.7. The 
EPA-approved version of the CALPUFF modeling system has since been 
updated to Version 5.8.5 Level 151214.\42\ Specific updates to the 
CALPUFF and CALMET models since Version 5.8 are summarized below:
---------------------------------------------------------------------------

    \42\ See EPA, CALPUFF Modeling System, available at: https://www3.epa.gov/ttn/scram/7thconf/calpuff/Previous_SCRAM_CALPUFF_ 
Posting_Reference.pdf.
---------------------------------------------------------------------------

     December 4, 2013--CALPUFF and CALMET updated from Version 
5.8 to Version 5.8.4 Level 130731. Changes are described in Model 
Change Bulletins E, F, and G.\43\ This update included bug fixes only 
and no enhancements or new features.
---------------------------------------------------------------------------

    \43\ Bulletins E, F, and G are available at https://www3.epa.gov/ttn/scram/models/calpuff/calpuff_mcb_e.txt, https://www3.epa.gov/ttn/scram/models/calpuff/calpuff_mcb_f.txt, and https://www3.epa.gov/ttn/scram/models/calpuff/calpuff_mcb_g.txt, 
respectively.
---------------------------------------------------------------------------

     July 26, 2016--CALPUFF and CALMET updated to Version 5.8.5 
Level 151214 which is the current EPA-approved version of the models. 
This was the version of CALUFF used in revised modeling for Plants 
Watson and Daniel. Changes are described in Model Change Bulletin 
H.\44\ This update included program fixes to the PRIME downwash 
algorithm along with updates to eliminate specific compilation and list 
file errors.
---------------------------------------------------------------------------

    \44\ https://www3.epa.gov/ttn/scram/models/calpuff/calpuff_mcb_h.txt.
---------------------------------------------------------------------------

    A December 3, 2013, memorandum prepared by an EPA contractor 
summarized the changes to the CALPUFF modeling system described in 
Model Change Bulletins E, F, and G, and the potential effect of those 
changes on predicted pollutant impacts for several scenarios and source 
types.\45\ This memorandum broadly concluded that the changes to the 
CALPUFF modeling system resulted in no difference, or almost no 
difference (+/- 1 percent (%)), in predicted values for most scenarios 
and source types evaluated.
---------------------------------------------------------------------------

    \45\ AMEC, AERMOD Technical Assistance--Modification of CALPUFF 
and CALMET Final Report (December 3, 2013), available at: https://www3.epa.gov/ttn/scram/models/calpuff/CALPUFF_Update_Memo_12032013.pdf.
---------------------------------------------------------------------------

    In addition to the differences in CALPUFF versions, three sources 
(Baxter Wilson, Gerald Andrus, and Plant Chevron) used Version 6.292 
Level 110406 of the CALPOST processor (one of the components of the 
CALPUFF modeling framework), while four sources (Plant Daniel, Plant 
Morrow, Plant Moselle, and Plant Watson) used Version 6.221 Level 
080724. Use of either version of CALPOST is consistent with EPA policy 
in this context.\46\
---------------------------------------------------------------------------

    \46\ This context refers to calculating visibility using the new 
IMPROVE equation through CALPOST Method 8. See p.71 of the November 
2012 Plant Watson modeling report (Appendix B). This modeling report 
is included in the docket for this rulemaking. The IMPROVE Equation 
is available at: http://npshistory.com/publications/air-quality/flag-2010.pdf.
---------------------------------------------------------------------------

Further Evaluation of CALPUFF Model Changes at Baxter Wilson, Gerald 
Andrus, Plant Chevron, and Plant Moselle
    EPA also performed a specific assessment of the potential impacts 
of these updates to the EPA-approved version of the CALPUFF modeling 
system on the visibility results for Baxter Wilson, Gerald Andrus, 
Plant Chevron, and Plant Moselle. Because the emissions profile and 
visibility impact for Plant Watson is similar to these four sources, 
and Plant Watson also used an earlier version of CALPUFF, EPA analyzed 
Plant Watson modeling information using the earlier and current 
versions of CALPUFF as a point of comparison to illustrate the effect 
of the CALPUFF model changes. Emissions from Baxter Wilson, Gerald 
Andrus, Plant Chevron, and Plant Moselle were all dominated primarily 
by NOX and secondarily by PM10, similar to Plant 
Watson. The predicted visibility impacts from these five facilities on 
the nearest Class I areas were dominated by NOX emissions, 
accounting for 86% of the visibility impacts from Plant Watson and 90% 
to 98% of the visibility impacts from the remaining facilities.\47\ The 
magnitude of NOX emissions from Baxter Wilson, Gerald 
Andrus, and Plant Watson are greater than the magnitude of 
NOX emissions from Plants Chevron and Moselle. With the 
noted similarities in the emissions profiles and predicted visibility 
impacts in the initial modeling performed for these facilities, the 
updated modeling performed for Plant Watson using the current EPA-
approved version of CALPUFF and recent emissions data provides insight 
on the potential effects of updates to the CALPUFF modeling system on 
predicted visibility impacts for Baxter Wilson, Gerald Andrus, Plant 
Chevron, and Plant Moselle.
---------------------------------------------------------------------------

    \47\ Breton is the nearest Class I area for Plant Watson, Baxter 
Wilson, Plant Chevron, and Plant Moselle, and Caney Creek is the 
nearest Class I area for Gerald Andrus.
---------------------------------------------------------------------------

    The modeling performed for Plant Watson in 2020 using 2017-2019 
emissions data and the current EPA-approved version of CALPUFF 
indicated similar visibility impacts as those predicted by the 2012 
modeling: 91% of the visibility impacts at Breton due to the facility 
are the result of NOX emissions, 8% of the visibility 
impacts are the result of PM10 emissions, and only 1% of the 
visibility impacts are the result of SO2 emissions. A 
comparison of emissions utilized in the initial modeling for Plant 
Watson compared to the emissions utilized in the revised modeling for 
Plant Watson is presented in Table 10 along with the contribution to 
visibility impacts from each pollutant.

                    Table 10--Emissions Rates Modeled and Visibility Impacts for Plant Watson
----------------------------------------------------------------------------------------------------------------
                                                                                                  Change in 2012
                                   2012 Modeling   2020 Modeling   2012 Modeling   2020 Modeling      to 2020
            Pollutant              contribution    contribution   emissions rate  emissions rate      modeled
                                   to visibility   to visibility      (lb/hr)         (lb/hr)        emissions
                                    impacts (%)     impacts (%)                                      rates (%)
----------------------------------------------------------------------------------------------------------------
SO2.............................               1               1            4.99            4.08             -18
NOX.............................              86              91        2,491.39        2,141.34             -14
PM10............................              13               8           62.32           66.94              +7
----------------------------------------------------------------------------------------------------------------

[[Page 47145]]

    The 2017-2019 emissions rates used in the 2020 BART exemption 
modeling for Plant Watson changed relative to the 2003-2005 emissions 
rates used in the source's initial 2012 modeling as follows: 
NOX emissions decreased by 14%; PM10 emissions 
increased by 7%; and SO2 emissions decreased by 18%; in 
addition, SO2 emissions remained substantially lower than 
NOX and PM10 emissions.
    The 2020 modeling for Plant Watson indicated that the maximum 98th 
percentile 24-hour average visibility impact at Breton over the three 
years modeled decreased by 10% relative to the initial 2012 modeling. 
The 2020 modeling also indicated that the 22nd highest day's visibility 
impact over the three years modeled decreased by 11% relative to the 
initial 2012 modeling. This information is presented in Table 11. Table 
11 indicates that the 10-11% reduction in predicted visibility impacts 
is closely correlated to the 14% reduction in the NOX 
emissions rate. These results suggest that the reductions in predicted 
visibility impacts are primarily due to the 14% reductions in 
NOX emissions rather than the updates to CALPUFF.

                  Table 11--Comparison of Initial Modeling to Revised Modeling for Plant Watson
----------------------------------------------------------------------------------------------------------------
                                                     Max 98th      22nd highest
                                                    percentile      day over 3     NOX emissions  PM10 emissions
                                                   over 3 years    years modeled   rate (lb/hr)    rate (lb/hr)
                                                   modeled (dv)        (dv)
----------------------------------------------------------------------------------------------------------------
Initial 2012 Modeling...........................           0.482           0.457         2,491.4            62.3
Revised 2020 Modeling...........................           0.436           0.408         2,141.3            66.9
2012 to 2020 Change (%).........................           -9.5%          -10.7%          -14.1%           +7.4%
----------------------------------------------------------------------------------------------------------------

    The updated modeling performed for Plant Watson using the current 
EPA-approved version of CALPUFF and recent emissions data suggests that 
the updates to the CALPUFF model did not significantly affect predicted 
visibility impacts for Plant Watson. Instead, the predicted changes in 
visibility from Plant Watson between the initial and revised modeling 
appear to be driven by NOX emissions reductions. With the 
noted similarities in the emissions profiles and predicted visibility 
impacts between Plant Watson and Baxter Wilson, Gerald Andrus, Plant 
Chevron, and Plant Moselle, the updates to CALPUFF are also not 
expected to have a significant impact on predicted visibility impacts 
from these other facilities. Revised modeling performed with the 
current EPA-approved version of CALPUFF and recent emissions for these 
facilities would likely result in visibility impacts the same as or 
less than the values from the 2011/2012 modeling shown in Table 12 
because recent emissions have either remained equivalent to or 
decreased since the 2011/2012 modeling. Therefore, the reduction in 
NOX and PM10 emissions shown in Table 12 would 
suggest a corresponding decrease in visibility impact at the nearest 
Class I area.

 Table 12--2011/2012 Visibility Modeling Results and Changes in Recent NOX and PM10 Emissions for Baxter Wilson, Gerald Andrus, Plant Chevron, and Plant
                                                                         Moselle
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                NOX         Percent (%)        PM10
                                                                             2011/2012     contribution    change in NOX   contribution   Percent change
                 Facility                       Nearest class I area        modeled DV     to visibility  emissions \49\   to visibility      in PM10
                                                                            impact \48\     impact (%)                      impact (%)    emissions \50\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Baxter Wilson.............................  Breton......................            0.49              96             -80               3             -58
Gerald Andrus.............................  Caney Creek.................            0.15              98             -54               2             -13
Plant Chevron.............................  Breton......................            0.27              90             -25               9               0
Plant Moselle.............................  Breton......................            0.05              92             -11               7             -57
--------------------------------------------------------------------------------------------------------------------------------------------------------

    As previously noted, Plant Chevron used a different version of 
CALPUFF (Version 5.754) than Plant Watson used in its initial modeling 
(Version 5.8). While EPA did not specifically analyze the changes from 
CALPUFF Version 5.754 to 5.8 (or from 5.754 to the current version), 
EPA nonetheless believes that updating the modeling for Plant Chevron 
is not necessary. As previously shown, the updates to Version 5.8 of 
the CALPUFF model did not significantly affect predicted visibility 
impacts for Plant Watson. Instead, the predicted changes in visibility 
from Plant Watson between the initial and revised modeling appear to be 
driven by NOX emissions reductions. If EPA assumes a similar 
relationship also holds true for Plant Chevron, then the Agency would 
expect updated modeling to show decreased visibility impact for Plant 
Chevron. That is, the 2011 modeling for Plant Chevron indicated a 
maximum 98th percentile 24-hour impact of 0.27 dv over the three years 
modeled, which is well below the value of 0.5 dv. The reduction in 
NOX emissions shown in Table 12 for Plant Chevron would 
suggest a corresponding decrease in visibility impact at Breton. 
Specifically, if EPA assumed that any visibility impact changes would 
be solely due to changes in NOX emissions, then the 
visibility impact of updated modeling would be approximately 0.21 
dv.\51\ In

[[Page 47146]]

addition, while EPA is not aware of evidence indicating that CALPUFF 
Version 5.754 underpredicts visibility impacts relative to the current 
CALPUFF version, even were this to be true, the Agency thinks it is 
extremely unlikely that would cause the visibility impact to rise above 
0.5 dv, given that Plant Chevron initially modeled 0.27 dv and the 
subsequent emission reductions at the source.
---------------------------------------------------------------------------

    \48\ The maximum 98th percentile 24-hour visibility impact over 
the three years modeled.
    \49\ Percent decrease in NOX emissions from the 
emissions used in the 2012 modeling to emissions that would be used 
in the 2020 modeling. Detailed emissions data for each of the four 
facilities are presented in Section III.A.
    \50\ Percent decrease in PM10 emissions from the 
emissions used in the 2012 modeling to emissions that would be used 
in the 2020 modeling. Detailed emissions data for each of the four 
facilities are presented in Section III.A.
    \51\ The basis for the estimated impact of 0.21 dv due to 
NOX reductions alone is as follows. The 2011 CALPUFF 
modeling for Plant Chevron indicated that 90% of visibility impacts 
at Breton were from NOX emissions which equates to 
approximately 0.243 dv (90% of the total estimated impact of 0.27 
dv). The remaining 10% of visibility impacts are due to 
PM10 and SO2 emissions which equates to 
approximately 0.027 dv (10% of 0.27 dv). To approximate the impact 
of the 25% reduction in NOX emissions from Plant Chevron, 
EPA decreased the portion of the visibility impacts due to 
NOX emissions (0.243 dv) by 25% (0.243 * (1-0.25) = 0.182 
dv). The PM10 and SO2 portion of the 
visibility impacts remains at 0.027 dv. Thus, the revised estimated 
total visibility impact from Plant Chevron on Breton is 0.21 dv 
(0.182 + 0.027 = 0.209 dv (rounded to 0.21)).
---------------------------------------------------------------------------

3. Evaluation of Supplemental Emissions Analyses and Operational 
Changes at Baxter Wilson, Gerald Andrus, Plant Chevron, and Plant 
Moselle
    EPA agrees with the supplemental emission analyses performed by 
MDEQ for Baxter Wilson, Gerald Andrus, Plant Chevron and Plant Moselle.
Baxter Wilson
    Even though the 2012 modeling for Baxter Wilson indicated 
visibility impacts below but near the 0.5 dv threshold (0.49 dv), there 
have been operational changes that have significantly reduced the 
emissions from this facility, including the shutdown of the larger of 
the two units at this facility. These changes have resulted in 
substantial reductions in both annual and maximum 24-hour emissions of 
SO2, NOX, and PM10 relative to the 
baseline period modeled as shown in Tables 4 and 5.
Gerald Andrus
    The 2012 modeling for the Gerald Andrus indicated visibility 
impacts of 0.15 dv, which is well below the 0.5 dv threshold. As shown 
in Table 6 above, recent maximum 24-hour emissions rates of 
SO2 are essentially the same as those modeled in 2012 while 
NOX and PM10 maximum 24-hour emissions rates have 
decreased substantially. Overall the recent annual emissions of 
SO2, NOX, and PM10 have drastically 
reduced at Gerald Andrus as shown in Table 7.
Plant Chevron
    The 2011 modeling for Plant Chevron indicated visibility impacts of 
0.27 dv, which is well below the 0.5 dv threshold. While recent annual 
emissions of SO2 have increased relative to the baseline 
period modeled, the magnitude of the facility's current maximum 24-hour 
SO2 emissions rate remains relatively low (8 lb/hr) compared 
to its NOX emissions rates (420 lb/hr) for all four units 
combined (see Table 2), and CALPUFF predicted that visibility impacts 
from Chevron were dominated by NOX emissions. During the 
same period, maximum 24-hour NOX emissions rates have 
decreased by about 25% while PM10 maximum 24-hour emissions 
rates are essentially unchanged.
Plant Moselle
    The 2011 modeling for Plant Moselle indicated visibility impacts of 
0.05 dv which is well below the 0.5 dv threshold. As shown in Table 8 
above, recent maximum 24-hour emissions rates of NOX, 
SO2, and PM10 are equivalent to or less than 
those modeled in 2011.
    Based on the State's submission and EPA's analysis in this section 
and Section III.B.2, EPA proposes to approve MDEQ's finding that the 
four facilities (i.e., Baxter Wilson, Gerald Andrus, Plant Chevron, and 
Plant Moselle) remain exempt from further BART review.
4. Evaluation of Updated Modeling at Plant Daniel and Plant Watson
    Plant Daniel and Plant Watson have updated BART exemption modeling 
using current emissions of SO2, NOX, and PM to 
reflect the emissions changes as a result of the operational changes at 
each plant. The updated BART exemption modeling also used a newer 
version of CALPUFF, which is the current EPA-approved version. EPA 
believes the updated modeling analyses for Plant Daniel and Plant 
Watson properly reflect additional emissions controls and operational 
changes that have reduced emissions since the original modeling was 
conducted. For both facilities, the updated modeling shows that the two 
facilities model below the BART contribution threshold. Therefore, EPA 
proposes to approve MDEQ's finding that these facilities are also 
exempt from further BART review.
5. Federal Land Manager (FLM) Review
    MDEQ provided the draft BART SIP to the FLMs to review in 
accordance with 40 CFR 51.308(i)(2), and the FLMs have not provided any 
comments. MDEQ's draft BART SIP references the procedures for 
continuing consultation between the State and FLMs on the 
implementation of the State's visibility protection program in 
accordance with 40 CFR 51.308(i)(4) that are contained in Section 11 of 
the State's September 22, 2008, regional haze plan.\52\ These 
procedures remain in effect for the draft BART SIP.
---------------------------------------------------------------------------

    \52\ The draft BART SIP references Section 10, but EPA believes 
the State meant to refer to Section 11.
---------------------------------------------------------------------------

6. Summary
    In summary, EPA proposes to approve the draft BART SIP and finds 
that it corrects the deficiencies that led to the limited approval and 
limited disapproval of the State's regional haze SIP; to withdraw the 
limited disapproval of Mississippi's regional haze SIP; and to fully 
approve Mississippi's regional haze SIP as meeting all regional haze 
requirements of the CAA for the first implementation period, replacing 
the prior limited approval.

IV. Summary and EPA's Evaluation of Mississippi's Progress Report and 
Adequacy Determination

A. Regional Haze Progress Report

    This section includes EPA's analysis of Mississippi's Progress 
Report and an explanation of the basis for the Agency's proposed 
approval. EPA cannot take final action to approve Mississippi's 
Progress Report unless the Agency finalizes its proposal to approve the 
draft BART SIP because the existing regional haze SIP contains a 
deficiency in its current strategy to achieve RPGs.
1. Control Measures
    In its Progress Report, Mississippi summarizes the status of the 
emissions reduction measures that were relied upon by the State in its 
regional haze plan. The measures include, among other things, 
applicable federal programs (e.g., federal consent agreements, federal 
control strategies for EGUs, Maximum Achievable Control Technology 
standards, and mobile source rules). Additionally, MDEQ highlighted 
control programs and measures that were not relied upon in its regional 
haze plan which provide further assurances that visibility impacts from 
Mississippi's sources are addressed (e.g., EPA's MATS Rule and measures 
taken by certain sources to address the 2010 1-hour SO2 
NAAQS). In the Progress Report, MDEQ also reviewed the status of BART 
requirements for the non-EGU BART-subject sources in the State--Chevron 
Pascagoula Refinery (Chevron Refinery) and Mississippi Phosphates 
Corporation (MPC)--both located in Pascagoula, Mississippi, and notes 
that it will address BART for the aforementioned BART-eligible EGUs in 
a separate SIP submittal.\53\
---------------------------------------------------------------------------

    \53\ Subsequent to submittal of the Progress Report, Mississippi 
addressed EGU BART in its draft BART SIP, which is discussed in 
Section III of this notice.

---------------------------------------------------------------------------

[[Page 47147]]

    As discussed in Section II of this notice, a number of states, 
including Mississippi, submitted regional haze plans that relied on 
CAIR to meet certain regional haze requirements. EPA finalized a 
limited disapproval of Mississippi's regional haze plan due to this 
reliance on CAIR. In its draft BART SIP, Mississippi determined that 
none of its seven BART-eligible facilities with EGUs formerly subject 
to CAIR are subject to BART.
    Mississippi's draft BART SIP explains the status of each BART-
eligible EGU formerly subject to CAIR. Table 1 identifies the 14 BART-
eligible units (located at seven facilities) and the highest modeled 
impact at the nearest Class I area for each facility. Section III of 
this notice explains the status of each BART-eligible EGU in greater 
detail.
    In the State's regional haze plan and Progress Report, Mississippi 
focuses its assessment on SO2 emissions from coal-fired 
boilers at EGUs and industrial boilers because of VISTAS' findings that 
ammonium sulfate accounted for 69-87% of the visibility-impairing 
pollution in all of the VISTAS states, except one coastal area, based 
on 2000 to 2004 data. The emissions sensitivity analyses conducted by 
VISTAS predicted that reductions in SO2 emissions from EGU 
and non-EGU industrial point sources would result in the greatest 
improvements in visibility in the Class I areas in the VISTAS region, 
more than any other visibility-impairing pollutant. Thus, Mississippi 
concluded that reducing SO2 emissions from EGU and non-EGU 
point sources would have the greatest visibility benefits for the Class 
I areas impacted by Mississippi sources.\54\
---------------------------------------------------------------------------

    \54\ See 77 FR 11887 (February 28, 2012).
---------------------------------------------------------------------------

    Because many states had not yet defined their criteria for 
identifying sources to evaluate for reasonable progress at the time 
Mississippi was developing its September 22, 2008, regional haze plan, 
Mississippi initially applied its criteria for identifying emissions 
units eligible for a reasonable progress control analysis as a 
screening tool to identify Class I areas outside of the State 
potentially impacted by Mississippi sources.\55\ Mississippi only 
identified SO2 emissions from E.I. DuPont Delisle (DuPont) 
and Plant Watson as potentially impacting visibility at Breton in 
Louisiana for reasonable progress during the first implementation 
period.\56\ However, when Louisiana completed its reasonable progress 
assessments and finalized its regional haze SIP submittal, it did not 
identify any Mississippi sources as impacting Breton using Louisiana's 
evaluation criteria. Thus, MDEQ concluded, and EPA agreed, that no 
further evaluation of Dupont and Plant Watson was needed for reasonable 
progress and MDEQ updated its 2008 regional haze plan in the May 9, 
2011, amendment with this conclusion.\57\
---------------------------------------------------------------------------

    \55\ As noted earlier, Breton in Louisiana, Sipsey in Alabama, 
and Caney Creek in Arkansas are the closest Class I areas to 
Mississippi. With respect to reasonable progress, Louisiana, 
Alabama, and Arkansas did not identify any Mississippi sources as 
having an impact on the visibility at Breton, Sipsey, and Caney 
Creek, respectively.
    \56\ See 77 FR 11888 (February 28, 2012). See also page 14 of 
the Progress Report.
    \57\ See 77 FR 11888 (February 28, 2012).
---------------------------------------------------------------------------

    EPA proposes to find that Mississippi has adequately addressed the 
applicable provisions under 40 CFR 51.308(g) regarding the 
implementation status of control measures because the State described 
the implementation of measures within Mississippi, including BART for 
NOX, SO2, and PM at its BART-subject sources for 
non-EGUs in its Progress Report and for EGUs in its draft BART SIP.
2. Emissions Reductions
    As discussed in Section IV.A.1. of this notice, Mississippi focused 
its assessment in its regional haze plan and Progress Report on 
SO2 emissions from coal-fired boilers at point sources in 
Mississippi because of VISTAS' findings that ammonium sulfate is the 
primary component of visibility-impairing pollution in the VISTAS 
states based upon 2000 to 2004 data.\58\ In its Progress Report, MDEQ 
provides a bar graph with Mississippi's EGU SO2 emissions 
from 2002 to 2017 and states that these emissions have decreased from 
65,741 tons in 2002 to 2,569 tons in 2017. MDEQ notes that these 
emissions are trending downward overall, with significant decreases 
from 2014 to 2016 (following increases in 2013 and 2014 due to 
emissions from Plant Watson) and consistently low values in 2016 and 
2017 due to the conversion of Plant Watson from coal to natural gas in 
2015.\59\
---------------------------------------------------------------------------

    \58\ The Progress Report also documents that sulfates continue 
to be the biggest single contributor to regional haze at Breton. See 
Section IV.A.5 for additional information.
    \59\ The Progress Report identifies Plant Watson as ``Watson 
Electric'' on page 10 in Figure 1 and in the associated note. The 
Progress Report notes that Plant Watson converted to natural gas in 
2014 on page 16; the correct date is 2015 as stated on page 10.
---------------------------------------------------------------------------

    Mississippi includes cumulative VOC, PM2.5, 
PM10, SO2, and NOX emissions data from 
2002, 2007, and 2014 for EGUs and non-EGUs in the State, along with the 
2018 emissions projections from its 2008 regional haze plan. The 2007 
actual emissions data were developed through the Southeastern Modeling, 
Analysis and Planning (SEMAP) partnership. At the time of Progress 
Report development, the 2014 National Emissions Inventory (NEI) was the 
latest available inventory.\60\ EPA's NEI is a comprehensive and 
detailed estimate of air emissions for criteria pollutants, criteria 
pollutant precursors, and hazardous air pollutants from air emissions 
sources that is updated every three years using information provided by 
the states and other information available to EPA.\61\
---------------------------------------------------------------------------

    \60\ See EPA's website for additional data and documentation for 
the 2014 version of the NEI (https://www.epa.gov/air-emissions-inventories/2014-national-emissions-inventory-nei-data).
    \61\ EPA's NEI is available at https://www.epa.gov/air-emissions-inventories/national-emissions-inventory.
---------------------------------------------------------------------------

    According to MDEQ, EGU emissions are near or below the 2018 
projections for all pollutants except SO2. As noted in 
Section III.A.7., Plant Watson converted from coal to natural gas in 
2015, and the source's SO2 emissions dropped from 70,667 
tons in 2014 to 5.1 tons in 2017 and 4.6 tons in 2018. MDEQ notes that 
this change in emissions from 2014 to 2018 at Plant Watson brings the 
State's EGU SO2 emissions closer to the 2018 value of 15,213 
tons projected in the regional haze plan (see Table 13).\62\ The 
emissions reductions identified by Mississippi are due, in part, to the 
implementation of measures included in the State's regional haze plan.
---------------------------------------------------------------------------

    \62\ Progress Report, page 11, Table 3.
---------------------------------------------------------------------------

    Since the time of SIP development and submission, more recent 
emissions data has become available for Mississippi's EGUs and non-EGUs 
from the 2017 NEI, which are reflected in Tables 13 and 14. For 
Mississippi's EGUs, actual emissions from the NEI for 2017 are below 
the 2018 projected emissions shown in Table 13 for all pollutants 
except VOC and NOX. Of particular note is that 2017 actual 
SO2 emissions of the State's EGUs are well below (2,877 tpy) 
the 2018 projected value of 15,213 tpy of SO2.

[[Page 47148]]

                            Table 13--EGU Emissions Inventory Summary for Mississippi
                                                      [tpy]
----------------------------------------------------------------------------------------------------------------
           Year/source                  VOC             NOX            PM2.5           PM10             SO2
----------------------------------------------------------------------------------------------------------------
2002 (VISTAS)...................             648          43,135           1,138           1,633          67,429
2007 (SEMAP)....................             669          48,150           1,426           2,165          75,563
2014 (NEI)......................             349          21,686           1,829           2,359          90,733
2018 (Projected)................           1,274          21,535           7,252           7,412          15,213
2017 (NEI)......................           2,515          30,214           2,752           3,213           2,877
----------------------------------------------------------------------------------------------------------------

    Emissions from the State's non-EGU point sources are below the 2018 
emissions projections for all pollutants as shown in Table 14.

                          Table 14--Non-EGU Emissions Inventory Summary for Mississippi
                                                      [tpy]
----------------------------------------------------------------------------------------------------------------
           Year/source                  VOC             NOX            PM2.5           PM10             SO2
----------------------------------------------------------------------------------------------------------------
2002 (VISTAS)...................          43,204          61,526           9,906          19,472          35,960
2007 (SEMAP)....................          33,917          50,033           7,305          10,203          19,415
2014 (NEI)......................          28,885          31,761           9,363          10,769          13,450
2018 (Projected)................          45,335          61,252          10,719          22,837          25,674
2017 (NEI)......................          24,840          13,498           6,226           7,376           5,500
----------------------------------------------------------------------------------------------------------------

    Emissions data for 2018 has also become available for the State's 
EGUs since the time that Mississippi submitted its Progress Report, and 
EPA notes that Mississippi's EGUs emitted 3,189.7 tons of 
SO2 in 2018,\63\ well below the projected 2018 value.
---------------------------------------------------------------------------

    \63\ Mississippi's EGUs emitted 13,041.3 tons of NOX 
in 2018. See EPA's Air Markets Program Data website, located at: 
https://ampd.epa.gov/ampd/.
---------------------------------------------------------------------------

    In the Progress Report, MDEQ also detailed emissions reductions at 
the State's two non-EGU BART-subject sources, Chevron Refinery and MPC. 
In the State's regional haze plan, Chevron Refinery and MPC modeled 
visibility impacts at Breton of 3.89 dv and 0.81 dv, respectively. To 
satisfy a 2005 consent decree, Chevron Refinery installed numerous 
controls on its units by 2008 which resulted in a modeled visibility 
improvement of 2.99 dv at Breton.\64\ With respect to MPC, the Progress 
Report summarized the upgrades made at the source under a November 9, 
2010, Permit to Construct Air Emissions Equipment that included Best 
Available Control Technology emissions limits for SO2 and 
sulfuric acid mist. The facility filed for bankruptcy on October 24, 
2014, fully ceased operations in December of 2014, and has been 
permanently shut down and declared a Superfund site.\65\
---------------------------------------------------------------------------

    \64\ See Progress Report, pp. 13-14 and the 2005 consent decree 
in U.S. v. Chevron, available at: https://www.epa.gov/sites/production/files/documents/chevron-cd.pdf. Table 6 of the Progress 
Report identifies emissions reductions from the BART-eligible units 
covered by the consent decree.
    \65\ For more information on MPC as a Superfund site, see 
https://cumulis.epa.gov/supercpad/SiteProfiles/index.cfm?fuseaction=second.Cleanup&id=0403508#bkground.
---------------------------------------------------------------------------

    Based on the information provided in the Progress Report, EPA 
proposes to find that Mississippi has adequately addressed the 
applicable provisions of 40 CFR 51.308(g) regarding emissions 
reductions.
3. Visibility Conditions
    40 CFR 51.308(g)(3) requires that states with Class I areas within 
their borders provide information on current visibility conditions and 
the difference between current visibility conditions and baseline 
visibility conditions expressed in terms of five-year averages of these 
annual values. Because there are no Class I areas in Mississippi, the 
State is not required to provide an assessment of visibility conditions 
under 40 CFR 51.308(g)(3) as noted in the Progress Report.
4. Emissions Tracking
    In its Progress Report, Mississippi presents EGU SO2 
emissions data (from 2002 to 2017), and data from statewide actual 
emissions inventories for 2007 (SEMAP) and 2014 (NEI) and compares 
these data to the baseline emissions inventory for 2002 (actual 
emissions) and the projected emissions for 2018 from the State's 
regional haze plan. These emissions inventories, shown in Tables 15-18 
include the following source classifications: Point, area, biogenic 
(e.g., VOC from vegetation, emissions from fires), non-road mobile, and 
on-road mobile sources. The pollutants inventoried for these categories 
are VOC, NOX, PM2.5, PM10, 
NH3, and SO2.
    The 2014 emissions for VOC, NOX, and NH3 are 
all below the projected 2018 emissions for these pollutants. The 
increases in total PM10 and PM2.5 from 2007 to 
2014 (shown in Tables 16 and 17) are due to different methodologies for 
these years in calculating unpaved road emissions in the emission 
inventories. MDEQ notes that according to data from the Mississippi 
Department of Transportation, the number of miles of unpaved roads in 
the State have decreased from 22,547 miles in 2006 to 18,857 miles in 
2014. The increase in SO2 emissions from 105,657 tons in 
2007 to 108,429 tons in 2014 was due to emissions from Plant Watson 
prior to the source converting to natural gas in 2015. As noted in 
Section IV.A.2, the overall SO2 emissions from EGUs 
decreased substantially following this conversion.

[[Page 47149]]

                                            Table 15--2002 Actual Emissions Inventory Summary for Mississippi
                                                                          [tpy]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                     Source category                            VOC             NOX            PM2.5           PM10             NH3             SO2
--------------------------------------------------------------------------------------------------------------------------------------------------------
Point...................................................          43,852         104,661          11,044          21,106           1,359         103,389
Area....................................................         131,808           4,200          50,401         343,377          58,721             771
On-Road Mobile..........................................          86,811         110,672           2,089           2,828           3,549           4,566
Nonroad Mobile..........................................          41,081          88,787           4,690           5,010              23          11,315
Biogenic................................................       1,544,646          20,305               0               0               0               0
Fires...................................................          13,621           3,326          13,763          14,686             177              99
                                                         -----------------------------------------------------------------------------------------------
    Total...............................................       1,861,820         331,952          81,896         387,007          63,829         120,139
--------------------------------------------------------------------------------------------------------------------------------------------------------

                                            Table 16--2007 Actual Emissions Inventory Summary for Mississippi
                                                                          [tpy]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                     Source category                            VOC             NOX            PM2.5           PM10             NH3             SO2
--------------------------------------------------------------------------------------------------------------------------------------------------------
Point...................................................          34,586          98,183           8,731          12,368           1,640          94,978
Area....................................................          74,755           6,091          42,758         326,350          58,774             344
On-Road Mobile..........................................           4,516         117,225           4,061           5,030           1,809             920
Nonroad Mobile..........................................          35,315          48,321           3,105           3,308              35           3,088
Biogenic................................................       1,544,646          20,305               0               0               0               0
Fires...................................................         178,431          12,454          66,621          78,612          12,413           6,327
                                                         -----------------------------------------------------------------------------------------------
    Total...............................................       1,872,249         302,579         125,276         425,668          74,671         105,657
--------------------------------------------------------------------------------------------------------------------------------------------------------

                                            Table 17--2014 Actual Emissions Inventory Summary for Mississippi
                                                                          [tpy]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                     Source category                            VOC             NOX            PM2.5           PM10             NH3             SO2
--------------------------------------------------------------------------------------------------------------------------------------------------------
Point...................................................          29,234          53,477          11,192          13,128           2,891         104,183
Area....................................................          47,959          19,504         122,136         977,608          64,986             951
On-Road Mobile..........................................          28,852          72,763           2,336           4,438           1,428             399
Nonroad Mobile..........................................          22,408          14,631           1,434           1,510              23              34
Biogenic................................................       1,515,263          14,157               0               0               0               0
Fires...................................................          69,792           6,156          26,913          31,758           4,855           2,863
                                                         -----------------------------------------------------------------------------------------------
    Total...............................................       1,713,509         180,658         164,012       1,028,442          74,184         108,429
--------------------------------------------------------------------------------------------------------------------------------------------------------

                                          Table 18--2018 Projected Emissions Inventory Summary for Mississippi
                                                                          [tpy]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                     Source category                            VOC             NOX            PM2.5           PM10             NH3             SO2
--------------------------------------------------------------------------------------------------------------------------------------------------------
Point...................................................          46,452          71,804          17,172          30,046           1,591          54,367
Area....................................................         140,134           4,483          53,222         375,495          69,910             746
On-Road Mobile..........................................          31,306          30,259             810           1,607           4,520             435
Nonroad Mobile..........................................          28,842          68,252           3,203           3,452              29           6,683
Biogenic................................................       1,544,646          20,305               0               0               0               0
Fires...................................................          14,747           3,840          15,669          17,013             285             240
                                                         -----------------------------------------------------------------------------------------------
    Total...............................................       1,806,127         198,943          90,076         427,613          76,335          62,471
--------------------------------------------------------------------------------------------------------------------------------------------------------

    As discussed in Section IV.A.2, the Progress Report also contains 
other emissions data, including a figure displaying Mississippi's EGU 
SO2 emissions from 2002 to 2017 and two tables summarizing 
EGU and non-EGU actual emissions data for 2002, 2007, and 2014, along 
with the 2018 emissions projections for the State's regional haze plan 
(see Tables 13 and 14 of this notice). MDEQ states that EGU 
SO2 emissions have decreased from 65,741 tons in 2002 to 
2,569 tons in 2017.
    EPA is proposing to find that Mississippi adequately addressed the 
provisions of 40 CFR 51.308(g) regarding emissions tracking because the 
State compared the most recent updated emission inventory data at the 
time of SIP development with the baseline emissions used in the 
modeling for the regional haze plan. Furthermore, Mississippi evaluated 
EPA Air Markets Program Data \66\ SO2 emissions data from 
2002-2017 for EGUs in the State because ammonium sulfate is the primary 
component of visibility-impairing pollution in the VISTAS states and 
EGUs are the largest source of SO2 in the State.
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    \66\ EPA Air Markets Program Data is available at: https://ampd.epa.gov/ampd/.

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[[Page 47150]]

5. Assessment of Changes Impeding Visibility Progress
    In its Progress Report, Mississippi documented that sulfates, which 
are formed from SO2 emissions, continue to be the biggest 
single contributor to regional haze for Breton, and therefore focused 
its analysis on large SO2 emissions from point sources.\67\ 
In its September 22, 2008, regional haze SIP submittal, Mississippi 
notes that ammonium sulfate is the largest contributor to visibility 
impairment for Class I in the southeastern United States based upon 
2000 to 2004 data, and that reducing SO2 emissions would be 
the most effective means of reducing ammonium sulfate.\68\ In 
addressing the requirements at 40 CFR 51.308(g)(5), Mississippi shows 
in the Progress Report that the overall contribution of sulfates toward 
visibility impairment at Breton \69\ over the 2008-2012 period is 66% 
for the 20 percent haziest days and 54 percent for the 20 percent 
clearest days. Although the State concludes that sulfates continue to 
be the major component to visibility impairment at Breton, it also 
examines other potential pollutants of concern affecting visibility at 
this Class I area. Furthermore, the Progress Report shows that 
SO2 emissions reductions from 2002-2017 for EGUs in 
Mississippi overall are decreasing, and with the conversion of Plant 
Watson to natural gas in 2015, are estimated to well exceed the 
projected emission reductions from 2002-2018 in the State's regional 
haze plan.
---------------------------------------------------------------------------

    \67\ See Figures 2 and 3 in the Progress Report.
    \68\ See page 15 of Mississippi's September 22, 2008, regional 
haze SIP narrative.
    \69\ While Mississippi does not have any Class I areas, MDEQ 
reviewed particle speciation data for Breton because it is the 
closest Class I area.
---------------------------------------------------------------------------

    MDEQ summarized the changes in emissions from 2002 to 2014, the 
latest complete emissions inventory for all source categories in the 
State. For VOC, NH3, and NOX, the actual 
emissions decreased from 2002 to 2014. For SO2, total 
emissions in the State decreased from 2002, with a slight increase from 
2007, due to the point source category. MDEQ explains that the increase 
in SO2 emissions was due to emissions from Plant Watson 
which, as noted previously, converted from coal to natural gas in 2015 
and emitted 5.1 tons and 4.6 tons of SO2 in 2017 and 2018, 
respectively.\70\ For PM2.5 and PM10, increases 
in statewide PM2.5 and PM10 emissions occurred 
from 2002 to 2014 due to increases in area source emissions for these 
pollutants. The increase in 2014 is due to an increase in the unpaved 
road dust category created by different methodologies used to calculate 
unpaved road emissions over the years. MDEQ notes that according to 
data from the Mississippi Department of Transportation, the number of 
miles of unpaved roads in the State have decreased from 22,547 miles in 
2006 to 18,857 miles in 2014. Thus, MDEQ concludes that here have been 
no emissions changes that would impede progress and no significant 
changes in anthropogenic emissions within the State that have limited 
or impeded progress over the review period.
---------------------------------------------------------------------------

    \70\ As noted in Section IV.A.2, the conversion of Plant Watson 
from coal to natural gas in 2015 contributed to significant 
SO2 emissions decreases. In addition, 2017 Mississippi 
EGU SO2 emissions were 3,841 tons, which are well below 
the 2018 projected 15,213 tons shown in Table 13 of section IV.A.2 
of this rulemaking.
---------------------------------------------------------------------------

    EPA proposes to find that Mississippi has adequately addressed the 
provisions of 40 CFR 51.308(g) regarding an assessment of significant 
changes in anthropogenic emissions for the reasons discussed in this 
section.
6. Assessment of Current Strategy
    Mississippi believes that its regional haze plan is sufficient to 
enable potentially impacted Class I areas to meet their RPGs. MDEQ 
based this conclusion on the data provided in the Progress Report, 
including the emissions reductions of visibility-impairing pollutants 
from EGU and non-EGU point sources achieved in the State (summarized in 
Section IV.A.2).\71\
---------------------------------------------------------------------------

    \71\ See Tables 3 and 4 on page 11 of the Progress Report which 
are reproduced as Tables 13 and 14 in this notice, with the addition 
of ``2017 (NEI)'' emissions to Tables 13 and 14.
---------------------------------------------------------------------------

    Mississippi asserts that it consulted with other states during the 
development of its regional haze plan for reasonable progress, 
including Alabama and Louisiana, and that these states indicated that 
Mississippi sources have no impact on the visibility at Sipsey in 
Alabama and at Breton in Louisiana, respectively. As discussed above, 
MDEQ assessed the particle speciation data for Breton indicating that 
sulfates continue to be the dominant contributor to regional haze in 
this area.
    EPA proposes to find that Mississippi has adequately addressed the 
provisions of 40 CFR 51.308(g) regarding the strategy assessment. In 
its Progress Report, Mississippi assesses the particle speciation data 
at Breton and affirms that the focus of the State's regional haze plan 
on addressing SO2 emissions in the State continues to be 
most effective strategy to improve visibility at Breton. Mississippi 
documents the overall downward emissions trends in key pollutants, with 
a focus on SO2 emissions from EGUs in the State and 
determined that its regional haze plan is sufficient to enable Class I 
areas outside the State potentially impacted by the emissions from 
Mississippi to meet their RPGs.\72\ EPA's proposed approval of the 
strategy assessment is also based on the fact that CAIR was in effect 
in Mississippi through 2014, providing some of the emission reductions 
relied upon in Mississippi's regional haze plan through that date; the 
implementation of CSAPR, which by the end of the first regional haze 
implementation period, reduced emissions of NOX from EGUs 
formerly subject to CAIR in Mississippi; and the significant reductions 
of SO2 from EGUs formerly subject to CAIR in the State due 
to retirements, emissions controls, and permanent conversions to 
natural gas as described in Section III.A.
---------------------------------------------------------------------------

    \72\ Visibility conditions for 2009-2013 are below the 2018 RPGs 
for Sipsey in Alabama. See 83 FR 64797, 64800 (December 18, 2018). 
For Caney Creek, visibility conditions for 2012-2016 are below the 
revised 2018 RPG for the 20 percent worst days and below 2000-2004 
baseline conditions for the 20 percent best days. See 84 FR 11697, 
11707 (March 28, 2019).
---------------------------------------------------------------------------

7. Review of Current Monitoring Strategy
    EPA notes that the primary monitoring network for regional haze 
nationwide is the IMPROVE network, which monitors visibility conditions 
in Class I areas. The Visibility Information Exchange Web System 
(VIEWS) \73\ website has been maintained by VISTAS and the other 
regional planning organizations to provide ready access to the IMPROVE 
data and data analysis tools.
---------------------------------------------------------------------------

    \73\ The VIEWS website is located at: http://views.cira.colostate.edu/fed/SiteBrowser/Default.aspx?appkey=SBCF_VisSum.
---------------------------------------------------------------------------

    In its Progress Report, Mississippi states that no modifications to 
the existing monitoring network are necessary because it has no Class I 
areas and thus no monitoring strategy. EPA proposes to find that 
Mississippi has adequately addressed the applicable provisions of 40 
CFR 51.308(g) regarding the monitoring strategy because the State has 
no Class I areas.

B. Determination of Adequacy of the Existing Regional Haze Plan

    In its Progress Report, MDEQ submitted a negative declaration to 
EPA that the existing regional haze plan requires no further 
substantive revision at this time to achieve the RPGs for Class I areas 
potentially impacted by the State's sources. The State's negative 
declaration is based on the findings from the Progress Report, 
including the findings that: Actual emissions reductions of visibility-
impairing

[[Page 47151]]

pollutants in 2014 from EGUs and non-EGUs in Mississippi exceed the 
predicted reductions in MDEQ's regional haze plan with the exception of 
SO2 for EGUs; \74\ additional EGU control measures not 
relied upon in the State's 2008 regional haze plan have occurred during 
the first implementation period that have further reduced 
SO2 emissions; and the State's expectation that emissions of 
SO2 from EGUs in Mississippi are expected to continue to 
trend downward.
---------------------------------------------------------------------------

    \74\ As noted in Section IV.A.2, the conversion of Plant Watson 
from coal to natural gas in 2015 contributed to significant 
SO2 emissions decreases after 2014. In addition, 2017 
Mississippi EGU SO2 emissions were 3,841 tons, which were 
below the 2018 projected 15,213 tons shown in Table 13 of section 
IV.A.2 of this notice.
---------------------------------------------------------------------------

    EPA proposes to conclude that Mississippi has adequately addressed 
40 CFR 51.308(h) because the emissions trends of the largest emitters 
of visibility-impairing pollutants in the State indicate that the RPGs 
for any Class I areas in other states potentially impacted by 
Mississippi sources will be met and because MDEQ submitted the draft 
BART SIP which, if finalized, would correct the deficiencies in the 
regional haze plan that led to the limited disapproval. As previously 
noted, EPA is simultaneously proposing to approve a SIP revision to 
address certain BART determinations for 14 EGUs. EPA cannot take final 
action to approve Mississippi's declaration under 40 CFR 51.308(h) 
unless the Agency finalizes its proposal to approve the draft BART SIP.

V. Proposed Action

    EPA proposes to approve the draft BART SIP and finds that it 
corrects the deficiencies that led to the limited approval and limited 
disapproval of the State's regional haze SIP; to withdraw the limited 
disapproval of Mississippi's regional haze SIP; and to fully approve 
Mississippi's regional haze SIP as meeting all regional haze 
requirements of the CAA for the first implementation period, replacing 
the prior limited approval. EPA also proposes to approve Mississippi's 
October 4, 2018, Regional Haze Progress Report, as meeting the 
applicable regional haze requirements set forth in 40 CFR 51.308(g) and 
to approve the State's negative declaration under 51.308(h). EPA cannot 
take final action to approve Mississippi's Progress Report and negative 
declaration unless the Agency finalizes its proposal to approve the 
draft BART SIP.

VI. 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. See 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in 
reviewing SIP submissions, EPA's role is to approve state choices, 
provided that they meet the criteria of the CAA. These actions merely 
propose to approve state law as meeting Federal requirements and do not 
impose additional requirements beyond those imposed by state law. For 
that reason, these proposed actions:
     Are not significant regulatory actions 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);
     Are not Executive Order 13771 (82 FR 9339, February 2, 
2017) regulatory actions because SIP approvals are exempted under 
Executive Order 12866;
     Do not impose an information collection burden under the 
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
     Are 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.);
     Do 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);
     Do not have Federalism implications as specified in 
Executive Order 13132 (64 FR 43255, August 10, 1999);
     Are not economically significant regulatory actions based 
on health or safety risks subject to Executive Order 13045 (62 FR 
19885, April 23, 1997);
     Are not significant regulatory actions subject to 
Executive Order 13211 (66 FR 28355, May 22, 2001);
     Are not subject to requirements of Section 12(d) of the 
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 
note) because application of those requirements would be inconsistent 
with the CAA; and
     Do 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).
    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, these rules 
do not have tribal implications as specified by Executive Order 13175 
(65 FR 67249, November 9, 2000), nor will they impose substantial 
direct costs on tribal governments or preempt tribal law.

List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Incorporation by 
reference, Intergovernmental relations, Nitrogen dioxide, Ozone, 
Particulate matter, Reporting and recordkeeping requirements, Sulfur 
oxides, Volatile organic compounds.

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

    Dated: July 23, 2020.
Mary Walker,
Regional Administrator, Region 4.

[FR Doc. 2020-16443 Filed 8-3-20; 8:45 am]
BILLING CODE 6560-50-P