[Federal Register Volume 85, Number 127 (Wednesday, July 1, 2020)]
[Proposed Rules]
[Pages 39505-39517]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-13585]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 52 and 81

[EPA-R03-OAR-2020-0171; FRL-10010-86-Region 3]


Air Plan Approval; West Virginia; Redesignation of the Marshall 
Sulfur Dioxide Nonattainment Area to Attainment and Approval of the 
Area's Maintenance Plan

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to 
approve a

[[Page 39506]]

redesignation request and state implementation plan (SIP) revisions 
submitted by the State of West Virginia related to the national ambient 
air quality standard (NAAQS or Standard) for the 2010 1-hour sulfur 
dioxide (SO2) NAAQS (2010 SO2 NAAQS). On March 
18, 2020, West Virginia, through the West Virginia Department of 
Environmental Protection (WVDEP), submitted a redesignation request for 
the Marshall, West Virginia SO2 Nonattainment Area (Marshall 
Area or Area). In conjunction with its request, WVDEP submitted SIP 
revisions comprised of a maintenance plan providing for continued 
attainment of the SO2 NAAQS for a period of ten years 
following redesignation of the Area, SO2 emissions limits 
for the Mitchell Power Plant (Mitchell), and a modeling analysis 
demonstrating that the Mitchell limits provide for attainment in the 
Area. The effect of this proposal, if finalized, would change the 
designation of the Marshall Area from nonattainment to attainment of 
the 2010 SO2 NAAQS. This action is being taken under the 
Clean Air Act (CAA).

DATES: Written comments must be received on or before July 31, 2020.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R03-
OAR-2020-0171 at https://www.regulations.gov, or via email to 
[email protected]. For comments submitted at Regulations.gov, 
follow the online instructions for submitting comments. Once submitted, 
comments cannot be edited or removed from Regulations.gov. For either 
manner of submission, 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, please contact the person 
identified in the FOR FURTHER INFORMATION CONTACT section. For the full 
EPA public comment policy, information about CBI or multimedia 
submissions, and general guidance on making effective comments, please 
visit https://www.epa.gov/dockets/commenting-epa-dockets.

FOR FURTHER INFORMATION CONTACT: Marilyn Powers, Planning & 
Implementation Branch (3AD30), Air & Radiation Division, U.S. 
Environmental Protection Agency, Region III, 1650 Arch Street, 
Philadelphia, Pennsylvania 19103. The telephone number is (215) 814-
2308. Ms. Powers can also be reached via electronic mail at 
[email protected].

SUPPLEMENTARY INFORMATION: EPA is proposing to take the following 
actions: (1) Approve and incorporate into the SIP the SO2 
limits and associated compliance and monitoring parameters in consent 
order CO-SIP-C-2019-13 for Mitchell; (2) determine that the air quality 
modeling submitted by the WVDEP demonstrates that the Marshall Area has 
attained the 2010 SO2 NAAQS as a result of compliance with 
the consent order limits for Mitchell; (3) approve and incorporate into 
the SIP West Virginia's plan for maintaining the 2010 SO2 
NAAQS in the Marshall Area through 2030 pursuant to section 175A of the 
CAA; and (4) redesignate the Marshall Area to attainment for the 2010 
SO2 NAAQS.

Table of Contents

I. Background
II. Criteria for Redesignation to Attainment
III. EPA's Analysis of West Virginia's Redesignation Request for the 
Marshall Area
    A. The Marshall Area Has attained the 2010 SO2 NAAQS
    1. Attainment Demonstration and Longer Term Averaging
    2. Modeling Analysis
    B. West Virginia Has Met All Applicable Requirements of Section 
110 and Part D of the CAA for the Marshall Area and EPA Has Fully 
Approved the Applicable Implementation Plan Under Section 110(k) of 
the CAA
    a. Section 110 General Requirements for SIPs
    b. Part D Requirements
    i. Subpart 1 Requirements
    (1) Section 172 Requirements
    (2) Section 173
    (3) Section 175A
    (4) Section 176 Requirements
    ii. Subpart 5 Requirements
    C. The Air Quality Improvements in the Marshall Area Are Due to 
Permanent and Enforceable Emissions Reductions
    D. West Virginia Has a Fully Approvable Maintenance Plan for the 
Marshall Area
IV. The Effect of EPA's Proposed Actions
V. Proposed Actions
VI. Incorporation by Reference
VII. Statutory and Executive Order Reviews

I. Background

    On June 22, 2010 (75 FR 35520), EPA published a new 1-hour primary 
SO2 NAAQS of 75 parts per billion (ppb), which is met at an 
ambient air quality monitoring site when the 3-year average of the 
annual 99th percentile of daily maximum 1-hour average concentrations 
does not exceed 75 ppb, as determined in accordance with appendix T of 
40 CFR part 50. On August 5, 2013 (78 FR 47191), EPA designated 29 
areas of the country as nonattainment for the 2010 SO2 
NAAQS, including the Marshall Area in West Virginia. These designations 
are referred to as ``round one'' SO2 area designations which 
were effective on October 4, 2013. In that action, the Marshall Area 
was designated nonattainment for the 2010 SO2 NAAQS based on 
data collected at the Moundsville, West Virginia ambient air quality 
monitoring station for calendar years 2009 through 2011. The Marshall 
Area is comprised of the Clay, Franklin, and Washington Tax Districts 
of Marshall County, West Virginia.
    Under CAA section 191(a), attainment plan SIPs were due for areas 
designated nonattainment in round one 18 months after the effective 
date of designation, or April 4, 2015. Such SIPs were required by CAA 
section 192(a) to provide for attainment of the NAAQS as expeditiously 
as practicable, but no later than five years from the effective date of 
nonattainment designation, or October 4, 2018. West Virginia submitted 
an attainment SIP on March 17, 2017 (2017 SIP).\1\ The SIP addressed 
the required elements of an attainment SIP under CAA section 172(c), 
including an attainment demonstration that the State asserted showed 
attainment of the 2010 SO2 Standard, SO2 
emissions limits for the Mitchell Power Plant, reasonably available 
control measures including reasonably available control technology 
(RACM/RACT), reasonable further progress (RFP), contingency measures, 
and certification that nonattainment new source review (NNSR) permit 
program requirements were being met. The 2017 SIP included a West 
Virginia Compliance Order on Consent (2016 consent order) that required 
Kentucky Power Company, the operator of American Electric Power's (AEP) 
Mitchell Power Plant, to comply with an SO2 maximum 
emissions limit from Units 1 and 2, of 6,175 pounds per hour (lbs/hr) 
on a 30-day rolling average, along with associated monitoring, 
recordkeeping, and reporting requirements, starting on January 1, 2017. 
The March 18, 2020 submittal requesting redesignation included a

[[Page 39507]]

demonstration showing attainment, a maintenance plan, contingency 
measures, and a December 2, 2019 consent order (2019 consent order) 
with Kentucky Power for Mitchell with lower SO2 emissions 
limits based on modeling with a changed stack height. Specifically, the 
2019 consent order establishes an SO2 emissions limit for 
Mitchell Units 1 and 2 as a maximum of 3,149 lbs/hr on a 30-day rolling 
average, with compliance parameters including continuous emissions 
monitoring, recordkeeping including a calculation of the daily 30-day 
average, reporting of deviations from the requirements and semi-annual 
compliance reporting. Compliance with the limits and other provisions 
in the 2019 consent order were required starting on January 1, 2020.
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    \1\ On March 18, 2016, EPA made a finding of failure to submit 
nonattainment area SIPs for 19 nonattainment areas, including the 
Marshall Area. EPA's letter to West Virginia dated September 27, 
2017 confirmed that West Virginia's March 17, 2017 submittal 
corrected the deficiency identified in the finding.
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    Under CAA section 110(k)(2) through (4), EPA was required to take 
action to approve or disapprove West Virginia's 2017 SIP within 12 
months of determining it to be complete, but EPA did not take timely 
action. Subsequently, the Center for Biological Diversity and other 
plaintiffs (CBD) sued EPA in the U.S. District Court for the Northern 
District of California seeking a court order to compel EPA's action on 
West Virginia's 2017 SIP and several other SIPs for other areas in the 
nation. Center for Biological Diversity, et al., v. Wheeler, No. 4:18-
cv-03544-YGR. That lawsuit resulted in the plaintiffs and EPA agreeing 
to a schedule, entered by the court as an order, for EPA to take action 
on the covered SIPs by certain deadlines. October 30, 2020 was the 
court ordered deadline given for EPA to take action on West Virginia's 
2017 SIP. The order also provided that if EPA issues a redesignation to 
attainment for any area for which the order required EPA action on a 
submitted SIP covered by the order, then EPA's obligation to take 
action on that SIP's CAA section 172(c) elements would be automatically 
terminated. Consequently, if EPA takes final action to redesignate the 
Marshall, West Virginia nonattainment area to attainment before October 
30, 2020, EPA will not be required to take action on the 2017 SIP.

II. Criteria for Redesignation to Attainment

    Under CAA section 107(d)(3)(E), there are five criteria which must 
be met before a nonattainment area may be redesignated to attainment:
    1. EPA has determined that the relevant NAAQS has been attained in 
the area;
    2. The applicable implementation plan has been fully approved by 
EPA under section 110(k);
    3. EPA has determined that improvement in air quality is due to 
permanent and enforceable reductions in emissions resulting from the 
SIP, Federal regulations, and other permanent and enforceable 
reductions;
    4. EPA has fully approved a maintenance plan, including a 
contingency plan, for the area under section 175A of the CAA; and,
    5. The state has met all applicable requirements for the area under 
section 110 and part D.

III. EPA's Analysis of West Virginia's Redesignation Request for the 
Marshall Area

A. The Marshall Area Has Attained the 2010 SO2 NAAQS

    EPA's 2014 Guidance \2\ for areas designated nonattainment explains 
that there are generally two components needed to support an attainment 
determination, which should be considered interdependently. First, to 
demonstrate that it is meeting the Standard, an SO2 
nonattainment area which was designated based on air quality monitoring 
data would need to have three consecutive calendar years of air quality 
monitoring data showing that the area is meeting the Standard. The data 
would need to be complete and quality-assured, consistent with 40 CFR 
part 58 requirements, and other relevant EPA guidance, and properly 
submitted to the Air Quality System (AQS) database of the EPA's 
Aerometric Information Retrieval System (AIRS). Areas relying on 
monitoring data alone to support a determination of attainment are also 
expected to provide a demonstration (via air quality modeling) that the 
affected monitor(s) is or are located in the area of maximum 
concentration. If there are air quality monitors located in the area, 
but none are located in the area of predicted maximum concentration, 
then air quality dispersion modeling will generally be needed to 
estimate SO2 concentrations in the area for purposes of 
determining attainment. If both monitoring and modeling evidence is 
available, EPA will consider all available evidence.
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    \2\ Guidance for 1-Hour Sulfur Dioxide Nonattainment Area SIP 
Submissions, April 23, 2014, page 62.
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    Under EPA regulations at 40 CFR 50.17, the SO2 Standard 
is met at an ambient air quality monitoring site when the three-year 
average of the annual 99th percentile of daily maximum one-hour average 
concentrations is less than or equal to 75 ppb, as determined in 
accordance with appendix T of 40 CFR part 50. The Standard must be met 
at all relevant monitoring sites in the subject area. There is only one 
monitor in the Marshall Area, which is located at the Moundsville 
National Guard Armory in Marshall County. The data from this monitor 
has been certified and uploaded to EPA's AQS website, through December 
31, 2019, and shows an attaining design value for the most recent 
three-year period (2017 through 2019) of 8 ppb. The 2019 AQS design 
value report is included in the docket for this rulemaking action and 
is summarized in Table 1.

                   Table 1--Marshall Area 99th Percentile of 1-Hour Daily Maximum SO2 Concentrations (ppb), and 2017-2019 Design Value
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                                                                                                                                            2017-2019
                              Monitor                                   Monitor ID          2017             2018             2019         design value
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Moundsville National Guard Armory..................................     54-051-1002                7                9                9                8
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1. Attainment Demonstration and Longer Term Averaging
    CAA section 172(c)(1) directs states with areas designated as 
nonattainment to demonstrate that the submitted plan provides for 
attainment of the NAAQS. The control strategy requirements that SIPs 
must meet are further delineated in 40 CFR part 51 subpart G. EPA has 
long required that all SIPs and control strategies reflect four 
fundamental principles of quantification, enforceability, 
replicability, and accountability. General Preamble for

[[Page 39508]]

Implementation of title I of the CAA. 57 FR 13498, April 16, 1992, at 
13567-68. Attainment plans for the SO2 NAAQS must consist of 
two components: (1) Emission limits and other control measures that 
assure implementation of permanent, enforceable and necessary emission 
controls, and (2) a modeling analysis which meets the requirements of 
40 CFR part 51, appendix W, which demonstrates that these emission 
limits and control measures provide for timely attainment of the 
primary SO2 NAAQS as expeditiously as practicable, but by no 
later than the attainment date for the affected area. In all cases, the 
emission limits and control measures must be accompanied by appropriate 
methods and conditions to determine compliance with the respective 
emission limits and control measures and must be quantifiable (i.e., a 
specific amount of emission reduction can be ascribed to the measures), 
fully enforceable (specifying clear, unambiguous and measurable 
requirements for which compliance can be practicably determined), 
replicable (the procedures for determining compliance are sufficiently 
specific and non-subjective so that two independent entities applying 
the procedures would obtain the same result), and accountable (source 
specific limits must be permanent and must reflect the assumptions used 
in the SIP demonstrations).
    EPA's April 2014 guidance recommends that the emission limits be 
expressed as short-term average limits (e.g., addressing emissions 
averaged over one or three hours), but also describes the option to 
utilize emission limits with longer averaging times of up to 30 days, 
so long as the state meets various suggested criteria. See April 2014 
guidance, pages 22 to 39. The April 2014 Guidance recommends that--
should states and sources utilize longer averaging times--the longer 
term average limit should be set at an adjusted level that reflects a 
stringency comparable to the 1-hour average limit at the critical 
emission value (CEV) shown to provide for attainment that the plan 
otherwise would have set.
    The April 2014 guidance provides an extensive discussion of EPA's 
rationale for concluding that appropriately set, comparably stringent 
limitations based on averaging times for periods as long as 30 days can 
be found to provide for attainment of the 2010 SO2 NAAQS. In 
evaluating this option, EPA considered the nature of the Standard, 
conducted detailed analyses of the impact of use of 30-day average 
limits on the prospects for attaining the Standard, and carefully 
reviewed how best to achieve an appropriate balance among the various 
factors that warrant consideration in judging whether a state's plan 
provides for attainment. Id. at pages 22 to 39. See also Id. at 
appendices B, C, and D.
    As specified in 40 CFR 50.17(b), the 1-hour primary SO2 
NAAQS is met at an ambient air quality monitoring site when the 3-year 
average of the annual 99th percentile of daily maximum 1-hour average 
concentrations is less than or equal to 75 ppb. In a year with 365 days 
of valid monitoring data, the 99th percentile would be the fourth 
highest daily maximum 1-hour value. The 2010 SO2 NAAQS, 
including this form of determining compliance with the Standard, was 
upheld by the U.S. Court of Appeals for the District of Columbia 
Circuit in Nat'l Envt'l Dev. Ass'n's Clean Air Project v. EPA, 686 F.3d 
803 (D.C. Cir. 2012). Because the Standard has this form, a single 
exceedance of the NAAQS's 75 ppb level does not create a violation of 
the Standard. Instead, at issue is whether a source operating in 
compliance with a properly set emission limit with a longer term 
average could cause exceedances of 75 ppb, and if so the resulting 
frequency and magnitude of such exceedances, and in particular whether 
EPA can have reasonable confidence that a properly set longer term 
average limit will provide that the 3-year average of the annual fourth 
highest daily maximum 1-hour average value will be at or below 75 ppb. 
A synopsis of how EPA judges whether such plans ``provide for 
attainment,'' based on modeling of projected allowable emissions and in 
light of the NAAQS's form for determining attainment at monitoring 
sites, follows.
    For SO2 attainment demonstrations based on 1-hour 
emission limits, the standard approach is to conduct modeling using 
fixed emission rates. The maximum emission rate that would be modeled 
to result in attainment (i.e., in an ``average year'' \3\ shows three, 
not four days with maximum hourly levels exceeding 75 ppb) is labeled 
the ``critical emission value.'' The modeling process for identifying 
this CEV inherently considers the numerous variables that affect 
ambient concentrations of SO2, such as meteorological data, 
background concentrations, and topography. In the standard approach, 
the state would then provide for attainment by setting a continuously 
applicable 1-hour emission limit at this CEV.
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    \3\ An ``average year'' is used to mean a year with average air 
quality. While 40 CFR part 50 appendix T provides for averaging 
three years of 99th percentile daily maximum 1-hour values (e.g., 
the fourth highest daily maximum 1-hour concentration in a year with 
365 days with valid data), this discussion and an example below uses 
a single ``average year'' in order to simplify the illustration of 
relevant principles.
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    EPA recognizes that some sources have highly variable emissions, 
for example due to variations in fuel sulfur content and operating 
rate, that can make it extremely difficult, even with a well-designed 
control strategy, to ensure in practice that emissions for any given 
hour do not exceed the CEV. EPA also acknowledges the concern that 
longer term emission limits can allow short periods with emissions 
above the CEV which, if coincident with meteorological conditions 
conducive to high SO2 concentrations, could in turn create 
the possibility of an exceedance of the NAAQS level occurring on a day 
when an exceedance would not have occurred if emissions were 
continuously controlled at the level corresponding to the CEV. However, 
for several reasons, EPA believes that the approach recommended in its 
April 2014 Guidance document suitably addresses this concern. First, 
from a practical perspective, EPA expects the actual emission profile 
of a source subject to an appropriately set longer term average limit 
to be similar to the emission profile of a source subject to an 
analogous 1-hour average limit. EPA expects this similarity because it 
has recommended that the longer term average limit be set at a level 
that is comparably stringent to the otherwise applicable 1-hour limit, 
reflecting a downward adjustment from the CEV that is proportionate to 
the anticipated variability in the source's emissions profile. As a 
result, EPA expects either form of emission limit to yield a comparable 
reduction in SO2 emissions and comparable air quality.
    Second, from a more theoretical perspective, EPA has compared the 
likely air quality with a source having maximum allowable emissions 
under an appropriately set longer term limit, as compared to the likely 
air quality with the source having maximum allowable emissions under 
the comparable 1-hour limit. In this comparison, in the 1-hour average 
limit scenario, the source is presumed at all times to emit at the 
critical emission level, and in the longer term average limit scenario, 
the source is presumed occasionally to emit at levels higher than the 
CEV but on average, and presumably at most times, to emit well below 
the CEV. In an ``average year,'' compliance with the 1-hour limit is 
expected to result in three exceedance days (i.e., three days with 
maximum hourly values above 75 ppb) and a fourth day with a maximum 
hourly value at 75 ppb. By comparison, with the source complying with a 
longer

[[Page 39509]]

term limit, it is possible that additional exceedances of 75 ppb would 
occur that would not occur in the 1-hour limit scenario (if emissions 
exceed the CEV at times when meteorology is conducive to poor air 
quality). However, this comparison must also factor in the likelihood 
that exceedances of 75 ppb that would be expected in the 1-hour limit 
scenario would not occur in the longer term limit scenario. This result 
arises because the longer term limit requires lower emissions most of 
the time (because the limit is set well below the CEV), so a source 
complying with an appropriately set longer term limit is likely to have 
lower emissions at critical times than would be the case if the source 
were emitting as allowed with a 1-hour limit.
    As a hypothetical example to illustrate these points, suppose a 
source that always emits 1,000 pounds of SO2 per hour, which 
results in air quality at the level of the NAAQS (i.e., results in a 
design value of 75 ppb). Suppose further that in an ``average year,'' 
these emissions cause the five highest maximum daily average 1-hour 
concentrations to be 100 ppb, 90 ppb, 80 ppb, 75 ppb, and 70 ppb. Then 
suppose that the source becomes subject to a 30-day average emission 
limit of 700 pounds per hour. It is theoretically possible for a source 
meeting this limit to have emissions that occasionally exceed 1,000 
pounds per hour, but with a typical emissions profile, emissions would 
much more commonly be between 600 and 800 pounds per hour. In this 
simplified example, assume a zero background concentration, which 
allows one to assume a linear relationship between emissions and air 
quality. (A nonzero background concentration would make the mathematics 
more difficult but would give similar results.) Air quality will depend 
on what emissions happen on what critical hours, but suppose that 
emissions at the relevant times on these 5 days are 800 pounds per 
hour, 1,100 pounds per hour, 500 pounds per hour, 900 pounds per hour, 
and 1,200 pounds per hour, respectively. (This is a conservative 
example because the average of these emissions, 900 pounds per hour, is 
well over the 30-day average emission limit.) These emissions would 
result in daily maximum 1-hour concentrations of 80 ppb, 99 ppb, 40 
ppb, 67.5 ppb, and 84 ppb. In this example, the fifth day would have an 
exceedance of 75 ppb that would not otherwise have occurred, but the 
third day would not have exceedances that otherwise would have 
occurred, and the fourth day would be below rather than at 75 ppb. In 
this example, the fourth highest maximum daily 1-hour concentration 
under the 30-day average would be 67.5 ppb.
    This simplified example illustrates the findings of a more 
complicated statistical analysis that EPA conducted using a range of 
scenarios using actual plant data. As described in appendix B of EPA's 
April 2014 Guidance, EPA found that the requirement for lower average 
emissions over a longer averaging period is highly likely to yield 
better air quality than is required with a comparably stringent 1-hour 
limit. Based on analyses described in appendix B of its 2014 guidance, 
EPA expects that an emission profile with maximum allowable emissions 
under an appropriately set comparably stringent 30-day average limit is 
likely to have the net effect of having a lower number of exceedances 
of 75 ppb and better air quality than an emission profile with maximum 
allowable emissions under a 1-hour emission limit at the CEV. This 
result provides a compelling policy rationale for allowing the use of a 
longer averaging period, in appropriate circumstances where the facts 
indicate this result can be expected to occur.
    The question then becomes whether this approach--which is likely to 
produce a lower number of overall exceedances even though it may 
produce some unexpected exceedances above the CEV--meets the 
requirement in section 110(a)(1) and 172(c)(1) for state implementation 
plans to ``provide for attainment'' of the NAAQS. For SO2, 
as for other pollutants, it is generally impossible to design a 
nonattainment area plan in the present that will guarantee that 
attainment will occur in the future. A variety of factors can cause a 
well-designed attainment plan to fail and unexpectedly not result in 
attainment, for example if meteorology occurs that is more conducive to 
poor air quality than was anticipated in the plan. Therefore, in 
determining whether a plan meets the requirement to provide for 
attainment, EPA's task is commonly to judge not whether the plan 
provides absolute certainty that attainment will in fact occur, but 
rather whether the plan provides an adequate level of confidence of 
prospective NAAQS attainment. From this perspective, in evaluating use 
of a 30-day average limit, EPA must weigh the likely net effect on air 
quality. Such an evaluation must consider the risk that occasions with 
meteorology conducive to high concentrations will have elevated 
emissions leading to exceedances that would not otherwise have occurred 
and must also weigh the likelihood that the requirement for lower 
emissions on average will result in days not having exceedances that 
would have been expected with emissions at the CEV. Additional policy 
considerations, such as in this case the desirability of accommodating 
real world emissions variability without significant risk of 
violations, are also appropriate factors for EPA to weigh in judging 
whether a plan provides a reasonable degree of confidence that the plan 
will lead to attainment. Based on these considerations, especially 
given the high likelihood that a continuously enforceable limit 
averaged over as long as 30 days, determined in accordance with EPA's 
guidance, will result in attainment, EPA believes as a general matter 
that such limits, if appropriately determined, can reasonably be 
considered to provide for attainment of the 2010 SO2 NAAQS.
    The April 2014 Guidance offers specific recommendations for 
determining an appropriate longer term average limit. The recommended 
method starts with determination of the 1-hour emission limit that 
would provide for attainment (i.e., the CEV), and applies an adjustment 
factor to determine the (lower) level of the longer term average 
emission limit that would be estimated to have a stringency comparable 
to the otherwise necessary 1-hour emission limit. This method uses a 
database of continuous emission data reflecting the type of control 
that the source will be using to comply with the SIP emission limits, 
which (if compliance requires new controls) may require use of an 
emission database from another source. The recommended method involves 
using these data to compute a complete set of emission averages, 
computed according to the averaging time and averaging procedures of 
the prospective emission limitation. In this recommended method, the 
ratio of the 99th percentile among these long term averages to the 99th 
percentile of the 1-hour values represents an adjustment factor that 
may be multiplied by the candidate 1-hour emission limit to determine a 
longer term average emission limit that may be considered comparably 
stringent.\4\ The guidance provided extensive recommendations regarding 
the calculation of the adjustment factor, for example to derive the 
adjustment factor from long term average versus 1-hour emissions 
statistics computed in accordance with the compliance

[[Page 39510]]

determination procedures that the state is applying. These 
recommendations are intended to yield the most pertinent estimate of 
the impact of applying a longer term average limit on the stringency of 
the limit in the relevant context. The April 2014 Guidance also 
addresses a variety of related topics, such as the potential utility of 
setting supplemental emission limits, such as mass-based limits, to 
reduce the likelihood and/or magnitude of elevated emission levels that 
might occur under the longer term emission rate limit.
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    \4\ For example, if the CEV is 1,000 pounds of SO2 
per hour, and a suitable adjustment factor is determined to be 70 
percent, the recommended longer term average limit would be 700 
pounds per hour.
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    Preferred air quality models for use in regulatory applications are 
described in appendix A of EPA's Guideline on Air Quality Models (40 
CFR part 51, appendix W).\5\ In 2005, EPA promulgated AERMOD as the 
Agency's preferred near-field dispersion modeling for a wide range of 
regulatory applications addressing stationary sources (for example in 
estimating SO2 concentrations) in all types of terrain based 
on extensive developmental and performance evaluation. Supplemental 
guidance on modeling for purposes of demonstrating attainment of the 
SO2 Standard is provided in appendix A to the April 2014 
SO2 Guidance document referenced above. Appendix A provides 
extensive guidance on the modeling domain, the source inputs, assorted 
types of meteorological data, and background concentrations. 
Consistency with the recommendations in this guidance is generally 
necessary for the attainment demonstration to offer adequately reliable 
assurance that the plan provides for attainment.
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    \5\ EPA published revisions to the Guideline on Air Quality 
Models (40 CFR part 51, appendix W) on January 17, 2017.
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    As stated previously, attainment demonstrations for the 2010 1-hour 
primary SO2 NAAQS must demonstrate attainment and 
maintenance of the NAAQS in the entire area designated as nonattainment 
(i.e., not just at the violating monitor) by using air quality 
dispersion modeling (See appendix W to 40 CFR part 51) to show that the 
mix of sources and enforceable control measures and emission rates in 
an identified area will not lead to a violation of the SO2 
NAAQS. For a short-term (i.e., 1-hour) Standard, EPA believes that 
dispersion modeling, using allowable emissions and addressing 
stationary sources in the affected area (and in some cases those 
sources located outside the nonattainment area which may affect 
attainment in the area) is technically appropriate, efficient and 
effective in demonstrating attainment in nonattainment areas because it 
takes into consideration combinations of meteorological and emission 
source operating conditions that may contribute to peak ground-level 
concentrations of SO2.
    The meteorological data used in the analysis should generally be 
processed with the most recent version of AERMET. Estimated 
concentrations should include ambient background concentrations, should 
follow the form of the Standard, and should be calculated as described 
in section 2.6.1.2 of the August 23, 2010 clarification memo on 
``Applicability of appendix W Modeling Guidance for the 1-hr 
SO2 National Ambient Air Quality Standard'' (U.S. EPA, 
2010a).
    In the modeling analysis for Marshall, attainment was demonstrated 
at an hourly SO2 emission rate of 0.31 pounds per million 
British thermal units (lb/MMBtu) from both generating units at the 
Mitchell Power Plant, which equates to a 1-hour modeled CEV of 5,222.08 
lbs/hr (both units combined). West Virginia submitted an analysis of 
emissions from October 1, 2011 through September 30, 2016 to determine 
a rolling 30-day average emission rate that would be of comparable 
stringency to a 1-hour limit at the modeled emission rate, as suggested 
in the April 2014 Guidance. West Virginia followed the steps 
established by Appendix C, Example Determination of Longer Term Average 
Emission Limits of the April 2014 Guidance, including the evaluation of 
five years of historical data and the distribution of the hourly and 
30-day averages. The 99th percentile value among the hourly data and 
the 99th percentile value among the 30 operating-day period averages 
were each computed. In order to calculate the 30-day average, only 
operating days were included in the average. An operating day is a day 
in which one or both of units had at least one hour of emissions data 
reported. The ratio of these two values was an adjustment factor of 
60.3 percent. Multiplying this adjustment factor by the CEV serves to 
estimate the 30-day average limit that is comparably stringent to a 1-
hour limit at the CEV. By this means, West Virginia calculated a 30-day 
average limit of 3,149 pounds of SO2 per hour on a 30-day 
rolling average basis (both units combined). EPA agrees that West 
Virginia appropriately determined the CEV, the adjustment factor, and 
the resulting 30-day average limit.
2. Modeling Analysis
    The Moundsville Armory monitor was sited to assess the 
SO2 impacts caused by the major SO2 sources 
located along the Ohio River Valley in Marshall County. These 
facilities have had significant contributions of SO2 
emissions to the area and impacted the Moundsville monitoring site for 
over three decades. During the 2009-2011 time frame upon which the 
nonattainment designation was based, the sources included the R.E. 
Burger Power Plant in Belmont County, Ohio, the Kammer Power Plant, and 
the Rain CII Carbon Plant, which have all permanently shut down, and 
the Eagle Natrium, LLC plant, which now burns natural gas, and the 
Mitchell Power Plant. Mitchell Power Plant is the remaining primary 
source of SO2 in the Area that contributes to the 
Moundsville monitor, which is located approximately 11 kilometers 
northeast of Mitchell. However, the attainment modeling submitted in 
the 2017 SIP showed that the maximum SO2 concentration 
within the Area is located 0.75 kilometers east-northeast of the 
Mitchell Power Plant.
    Because the Moundsville Armory monitor is not at the location of 
maximum concentration, a modeling demonstration is required to show 
that SO2 concentrations throughout the Area show attainment. 
West Virginia's March 18, 2020, SIP submittal includes a modeling 
analysis to show that the Area will attain the 2010 SO2 
NAAQS based on the SO2 emission limit established for 
Mitchell Power Plant in a 2019 consent order with WVDEQ. EPA's analysis 
of the West Virginia modeling is more fully described in a Modeling 
Technical Support Document (TSD) that is provided in the docket for 
this rulemaking action and summarized below.
    The modeling protocol was developed by West Virginia in September 
of 2016 and periodically revised throughout the development of the 2017 
attainment SIP modeling demonstration. Final revisions to the protocol 
were made in December of 2016 and reflect the procedures that were used 
in the submitted 2017 attainment SIP modeling analysis. Although WVDEP 
did not subsequently alter the modeling protocol, WVDEP revised the 
attainment SIP modeling inputs in July 2019 to change the Mitchell 
stack height used in the modeling analysis to determine the lower 
limits needed to attain the SO2 Standard. The modeling 
analysis was submitted as part of West Virginia's 2020 redesignation 
request and was conducted in accordance with appendix A of EPA's April 
2014 Guidance and appendix W to 40 CFR part 51--Guideline on Air 
Quality Models, that

[[Page 39511]]

was published on January 17, 2017 \6\ and became effective May 22, 
2017.
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    \6\ https://www3.epa.gov/ttn/scram/appendix_w/2016/AppendixW_2017.pdf.
---------------------------------------------------------------------------

    West Virginia developed its modeling analysis for the Marshall, 
West Virginia SO2 redesignation request in July 2019 using 
AERMOD version 18081, which was the most current version of the model 
available when the modeling was being performed. AERMOD is a refined, 
steady-state (both emissions and meteorology over a 1-hour time step), 
multiple source, air-dispersion model that was originally promulgated 
by the EPA as part of its December 2005 revision to the Guideline on 
Air Quality Models, and is the preferred model to use for industrial 
sources in this type of air quality analysis. At the time West Virginia 
was preparing the 2017 SO2 attainment SIP, the available 
version of AERMOD was version 15181, which was made available by EPA's 
Support Center for Air Quality Models \7\ on July 24, 2015. On April 
24, 2018, EPA released AERMOD version 18081. For the March 18, 2020 
redesignation request, West Virginia re-ran the model using AERMOD 
18081. The most notable changes between version 18081 and version 15181 
of the model was the inclusion of an alternate surface friction option 
(``ADJ_U*'') and the allowance for the use of prognostic meteorological 
data as regulatory default options according to the final modeling 
guideline (40 CFR part 51 appendix W), released on December 20, 2016. 
The ADJ_U* option was used in the latest modeling.
---------------------------------------------------------------------------

    \7\ https://www.epa.gov/scram/air-quality-dispersion-modeling-preferred-and-recommended-models#aermod.
---------------------------------------------------------------------------

    The AERMOD system used in the modeling demonstration is comprised 
of several preprocessors that are needed to develop the files necessary 
to run the air-dispersion model. These preprocessors include the 
meteorological preprocessors AERMET \8\ and AERSURFACE,\9\ as well as 
the building preprocessor, BPIPPRM, to calculate building downwash 
parameters and the terrain preprocessor, AERMAP,\10\ to determine 
emission source and receptor elevations used in the final SIP modeling 
analysis. The primary SO2 emitting facility remaining in 
operation and impacting the Marshall Area is the Mitchell Power 
Plant.\11\ To ensure maintenance of the 2010 SO2 NAAQS in 
the Marshall Area, air dispersion modeling was conducted for the 
SO2 emissions from the Mitchell Plant to show that the 
Marshall Area will continue to attain the 2010 SO2 NAAQS. 
The Mitchell Plant consists of two coal-fired electric generating units 
(EGU) rated at 800 megawatts (MW) net each, equipped with an 
electrostatic precipitator for particulate control, selective catalytic 
reduction (SCR) for nitrogen oxide and mercury control, and a 
limestone-based flue gas desulfurization system for SO2 
control. The plant is located in the Ohio River Valley in Marshall 
County, West Virginia, approximately 11 kilometers southwest of 
Moundsville, West Virginia. The units were modeled as point sources and 
a load analysis was performed at full load, 75% load, and 50% load.
---------------------------------------------------------------------------

    \8\ American Meteorological Society/Environmental Protection 
Agency Regulatory Model Meteorological Processor.
    \9\ American Meteorological Society/Environmental Protection 
Agency Regulatory Model Land Cover Processor.
    \10\ American Meteorological Society/Environmental Protection 
Agency Regulatory Model Terrain Preprocessor.
    \11\ See Round 1 SO2 designations TSD for West 
Virginia for EPA's analysis of emissions and boundaries for the 
Marshall Area, at https://www.epa.gov/sites/production/files/2016-03/documents/wv-tsd.pdf.
---------------------------------------------------------------------------

    The meteorological inputs used were developed for the period 2011 
through 2015 using Version 18081 of AERMET using Wheeling Airport 
surface data along with one minute and five minute data from the 
Automated Surface Observing System (ASOS) located at the site. Upper 
Air Data was sourced from the Greater Pittsburgh International Airport 
(KPIT) site through the National Oceanic and Atmospheric Administration 
Earth System Research Laboratory Radiosonde Database.
    The modeled design concentration is the combination of the 
appropriate background concentration (section 8.3 of appendix W--
Guideline on Air Quality Models) and the estimated modeled impact of 
the Mitchell Plant and any other identified nearby sources, which in 
this case was none. A comparison of the modeled design concentrations 
for each load case to the 2010 SO2 NAAQS is shown on Table 
2.

Table 2--Summary of West Virginia SO2 Modeling Demonstration Results, in
                 Micrograms per Cubic Meter ([mu]g/m\3\)
------------------------------------------------------------------------
                                           West Virginia
                                            1-hour SO2      1-hour SO2
                  Case                     concentration   NAAQS ([mu]g/
                                           ([mu]g/m\3\)        m\3\)
------------------------------------------------------------------------
Full Load...............................           196.2           196.4
75% Load................................           187.9           196.4
50% Load................................           175.5           196.4
------------------------------------------------------------------------

    The West Virginia modeling demonstration generally follows guidance 
included in appendix A of EPA's 2014 Guidance and EPA's revised 
``Guideline on Air Quality Models'' published on January 17, 2017 (82 
FR 5182). Peak model concentrations from the compliance run were 196.2 
[mu]g/m\3\. The modeled emission rates reflect emission rates contained 
in the 2019 consent order between West Virginia and Kentucky Power that 
are part of the SIP submittal, and which became enforceable at the 
state level on January 1, 2020, and which will become Federally 
enforceable if this proposed rulemaking is finalized. The modeling 
demonstration properly characterized source limits, local 
meteorological data, background concentrations and provided an adequate 
model receptor grid to capture maximum modeled concentrations. The 
modeling simulations show that even at the worst-case scenario, with 
the Mitchell facility operating at full capacity at the allowable 
emission limits, the design value would be below the NAAQS, 
demonstrating that the modeled emission limits will allow the Marshall 
Area to comply with the 2010 SO2 NAAQS for the maintenance 
period.
    EPA's April 2014 Guidance \12\ explains that EPA may also make 
determinations of attainment based on the modeling from the attainment 
demonstration for the applicable SIP for the affected area, eliminating 
the need for separate actuals-based modeling to support a redesignation 
request. A demonstration that the control strategy in the SIP has been 
fully implemented (compliance records demonstrating that the control 
measures have been implemented as required by the approved SIP) would 
also be relevant for making this determination. An additional SIP 
submittal from the air agency would not be required by the CAA, and if 
the air agency has previously submitted a modeled attainment 
demonstration, using allowable emissions, no further modeling would be 
needed as long as the source characteristics (e.g., factors affecting 
plume height) are still reasonably represented.
---------------------------------------------------------------------------

    \12\ See page 63.
---------------------------------------------------------------------------

    The modeling submitted by West Virginia as part of its 2020 
redesignation request is based on emission limits established in the 
2019 consent order. The 2019 consent order requires Kentucky Power, the 
operator of the Mitchell Power Plant, to comply with SO2 
limits at the Mitchell Power Plant and associated compliance parameters 
starting on January 1, 2020. The air quality modeling submitted with 
the state's request used allowable emissions

[[Page 39512]]

(i.e., the SO2 limits effective January 1, 2020), and so 
long as Mitchell is meeting its allowable limits, and the source 
characteristics are consistent with the demonstration, such modeling is 
likely conservative given that the actual emissions from Mitchell are 
well below the emission used in the modeling. First quarter 2020 
emissions data for Mitchell Power Plant shows compliance with the 
SO2 emissions limit established under the 2019 consent 
order.\13\ In addition, West Virginia's submittal includes a chart of 
the last ten years of Mitchell's actual emissions, as compared to the 
new limits in the consent order. In that chart, shown in figure 4 of 
the submittal, the combined actual emissions from the stacks at 
Mitchell are well below the 30-day average rolling limit of 3,149 
pounds of SO2 per hour that took effect on January 1, 2020.
---------------------------------------------------------------------------

    \13\ See graph entitled ``2020Q1 Historical AEP Mitchell 
Combined Units 1 & 2 30-Day Rolling Average Emissions of 
SO2'' available in the docket for this rulemaking action. 
The first quarter SO2 emissions data for Mitchell Power 
Plant is publicly available at EPA's Air Markets Program Data at 
https://ampd.epa.gov//ampd/QueryToolie.html.
---------------------------------------------------------------------------

    Based upon the modeling submitted as part of the maintenance plan 
for the redesignation request submitted on March 18, 2020, EPA is 
proposing to find that West Virginia has shown that the Marshall Area 
is attaining the 2010 SO2 NAAQS.

B. West Virginia Has Met All Applicable Requirements of Section 110 and 
Part D of the CAA for the Marshall Area and EPA Has Fully Approved the 
Applicable Implementation Plan Under Section 110(k) of the CAA

    In accordance with section 107(d)(3)(E)(v) of the CAA, in order to 
redesignate the Marshall Area to attainment, West Virginia must meet 
all requirements applicable to the Marshall Area under CAA section 110 
(general SIP requirements) and part D of title I of the CAA (SIP 
requirements for nonattainment areas), and in accordance with section 
107(d)(3)(E)(ii) of the CAA, those requirements must be fully approved 
into the West Virginia SIP under CAA section 110(k).
    EPA is proposing to determine that, in accordance with section 
107(d)(3)(E)(v), West Virginia has met all SIP requirements under 
section 110 of the CAA and part D of title I of the CAA applicable for 
purposes of this redesignation. In making these determinations, EPA 
identified the requirements that are applicable to the Area for 
purposes of redesignation and determined that these requirements are 
fully approved under section 110(k) of the CAA. EPA's rationale is 
discussed in more detail in sections III.B.1 and III.B.1.a of the 
preamble for this proposed rulemaking.
a. Section 110 General Requirements for SIPs
    Pursuant to CAA section 110(a)(1), whenever new or revised NAAQS 
are promulgated, the CAA requires states to submit a plan (i.e., 
``SIP'') for the implementation, maintenance and enforcement of such 
NAAQS. Section 110(a)(2) of title I of the CAA contains the general 
requirements for a SIP, also known as ``infrastructure'' requirements. 
The infrastructure requirements of section 110(a)(2) include the 
requirements in subsections 110(a)(2)(A) through (M). However, not 
every requirement of section 110(a)(2) is an applicable requirement for 
the purposes of redesignating the Marshall Area to attainment for the 
SO2 NAAQS. For example, section 110(a)(2)(D) requires that 
SIPs contain certain measures to prevent sources in a state from 
significantly contributing to air quality problems in another state. 
When such issues have been identified, EPA has required certain states 
to establish programs to address transport of air pollutants. See 
Nitrogen Oxides (NOX) SIP Call and amendments to the 
NOX SIP Call (64 FR 26298, May 14, 1999 and 65 FR 11222, 
March 2, 2000), and the Cross-State Air Pollution Rule (CSAPR) Update 
(81 FR 74504, October 26, 2016). However, the section 110(a)(2)(D) SIP 
requirements are not linked with a particular area's SO2 
designation. That is, the section 110(a)(2)(D) requirement continues to 
apply to a state regardless of the attainment designation (or 
redesignation) of an area. EPA has concluded that the SIP requirements 
linked to an area's SO2 designation for a particular NAAQS 
are the relevant (applicable) measures when reviewing a redesignation 
request for an area, and therefore the general requirements of section 
110(a)(2), such as section 110(a)(2)(D), are not applicable 
requirements for the purposes of a SO2 redesignation.
    Similarly, other section 110(a)(2) elements that are neither 
connected with attainment plan submissions nor linked with an area's 
SO2 designation are not applicable requirements for purposes 
of redesignation. An area redesignated from SO2 
nonattainment to attainment will remain subject to these requirements 
after redesignation to attainment. This approach is consistent with 
EPA's existing policy on the applicability for the purpose of 
redesignations of conformity and oxygenated fuels requirements, as well 
as CAA section 184 ozone transport requirements. See Reading, 
Pennsylvania, proposed and final rulemakings (61 FR 53174, October 10, 
1996; 62 FR 24826, May 7, 2008); Cleveland-Akron-Loraine, Ohio, final 
rulemaking (61 FR 20458, May 7, 1996); and Tampa, Florida, final 
rulemaking (60 FR 62748, December 7, 1995). See also the discussion on 
this issue in the Cincinnati, Ohio, redesignation (65 FR 37890, June 
19, 2000), and in the Pittsburgh, Pennsylvania, redesignation (66 FR 
50399, October 19, 2001).
    Nonetheless, EPA approved elements of West Virginia's July 1, 2013, 
and June 1, 2015, SO2 infrastructure SIP submittals on 
November 17, 2014 (79 FR 62022) and August 11, 2016 (81 FR 53008), 
respectively.\14\ As explained previously, the general requirements of 
CAA section 110(a)(2) are statewide requirements that are not linked to 
the nonattainment status of the Marshall Area and are therefore not 
``applicable requirements'' for the purpose of reviewing West 
Virginia's redesignation request. Because West Virginia satisfies the 
general SIP elements and requirements set forth in CAA section 
110(a)(2) applicable to and necessary for SO2 redesignation, 
EPA proposes to conclude that West Virginia has satisfied the criterion 
of section 107(d)(3)(E)(v) related to section 110(a)(2) of the CAA.
---------------------------------------------------------------------------

    \14\ West Virginia's SO2 infrastructure SIP 
submittals did not address the interstate transport element of CAA 
section 110(a)(2)(D)(i). As explained previously, the interstate 
transport element of CAA section 110(a)(2)(D)(i) is not an 
applicable requirement for redesignation of the Marshall Area.
---------------------------------------------------------------------------

b. Part D Requirements
    In addition to the CAA section 110 requirements, section 
107(d)(3)(E)(v) requires that the state meet all the requirements 
applicable to the nonattainment area ``under part D of this 
subchapter'' in order for the nonattainment area to be redesignated. 
Both section 107 and part D are within subchapter 1 of the CAA. Part D, 
entitled ``Plan Requirements for Nonattainment Areas,'' consists of six 
subparts, of which only subparts 1 and 5 are applicable to 
SO2 nonattainment areas. Subpart 1 (sections 171 through 
179B) contains provisions that can apply to all nonattainment areas for 
all criteria pollutants, while subpart 5 (sections 191 through 192) 
contains additional provisions for SO2, NOX, or 
lead nonattainment areas. The requirements applicable to this 
redesignation are discussed below.

[[Page 39513]]

i. Subpart 1 Requirements
(1) Section 172 Requirements
    CAA section 172 requires states with nonattainment areas to submit 
plans that provide for timely attainment of the NAAQS. More 
specifically, CAA section 172(c) contains general requirements for 
nonattainment plans. A thorough discussion of these requirements is 
found in the General Preamble for Implementation of title I. 57 FR 
13498, April 16, 1992.
    As noted in the General Preamble, certain attainment-related 
planning requirements under section 172(c) no longer have meaning for 
an area that is already attaining the NAAQS, and therefore are not 
applicable for purposes of redesignation. For example, for an area that 
is already attaining the NAAQS, there would be nothing for the state to 
provide in order to show reasonable further progress to attainment in 
that area. Similarly, the CAA section 172 requirements for the 
attainment demonstration, implementation of reasonably available 
control measures, including reasonably available control technology, 
and contingency measures that are triggered if an area fails to meet 
RFP or fails to attain also are not applicable for purposes of 
redesignation.
    With respect to the CAA section 172(c)(3) requirement to submit an 
actual current emissions inventory, WVDEP submitted a 2011 base year 
emissions inventory for the Marshall Area on May 6, 2015. On July 31, 
2015 (80 FR 45613), EPA approved the base year inventory into the West 
Virginia SIP.
(2) Section 173
    Section 173 of the CAA includes requirements for permit programs 
that are required in a nonattainment area for new sources as required 
by section 172(c)(5), known as nonattainment new source review (NNSR). 
However, EPA has a longstanding interpretation that because the NNSR 
permit program is replaced by the prevention of significant 
deterioration (PSD) permit program upon an area's redesignation to 
attainment, nonattainment areas seeking redesignation to attainment do 
not need a fully approved part D NNSR program in order to be 
redesignated. A more detailed rationale for this view is described in a 
memorandum from Mary Nichols, Assistant Administrator for Air and 
Radiation, dated October 14, 1994, entitled, ``Part D New Source Review 
Requirements for Areas Requesting Redesignation to Attainment.'' 
Nevertheless, EPA notes that West Virginia has SIP-approved NNSR and 
PSD programs, found at 45CSR13, 45CSR19, and 45CSR14. See 40 CFR 
52.2520(c). West Virginia's PSD program will become applicable for 
SO2 in the Marshall Area upon redesignation to attainment.
(3) Section 175A
    CAA section 175A requires that states seeking redesignation of an 
area to attainment submit a ``maintenance plan'' containing certain 
elements. West Virginia included a maintenance plan for the Marshall 
Area with its March 18, 2020 redesignation request, which EPA is 
proposing to approve in conjunction with the redesignation, and it is 
discussed in detail in section III.D of the preamble of this proposed 
rulemaking.
(4) Section 176 Requirements
    Section 176(c) of the CAA requires Federal actions conform to the 
air quality planning goals in the applicable SIP. The requirement to 
determine conformity applies to transportation plans, programs, and 
projects that are developed, funded, or approved under title 23 of the 
United States Code and the Federal Transit Act (transportation 
conformity) as well as to all other Federally-supported or funded 
projects (general conformity). Section 176(c) of the CAA also requires 
that states establish criteria and procedures to ensure that Federally-
supported or funded transportation plans, transportation improvement 
programs (TIPs) and projects conform to the goals of the applicable 
SIP. This is referred to as a transportation conformity SIP. In the 
preamble to the January 1993 proposed transportation conformity rule, 
EPA stated that, ``Based on available emissions information, EPA 
believes highway and transit motor vehicles are not significant sources 
of lead or sulfur dioxide. Therefore, transportation plans, TIPs, and 
projects are presumed to conform to the applicable implementation plans 
for these pollutants.'' (See 58 FR 3776, January 11, 1993.) In November 
1993, EPA finalized its transportation conformity regulations. One 
section of those regulations addressed the geographic applicability of 
the transportation conformity regulations. The regulation stated at 
that time that, ``The provisions of this subpart apply with respect to 
emissions of the following criteria pollutants: Ozone, carbon monoxide, 
nitrogen dioxide, and particles with an aerodynamic diameter less than 
or equal to a nominal 10 micrometers (PM10).'' \15\ Based on 
this provision, transportation conformity does not apply in 
nonattainment or maintenance areas for SO2. Therefore, a 
transportation conformity SIP is not required for SO2 
nonattainment and maintenance areas and is not necessary in order for 
an SO2 nonattainment area to be redesignated to attainment, 
and EPA's transportation conformity rules do not apply to 
SO2 for the Marshall Area.
---------------------------------------------------------------------------

    \15\ This provision has been revised to include particles with 
an aerodynamic diameter less than or equal to a nominal 2.5 
micrometers (PM2.5). See 40 CFR 93.102(b)(1).
---------------------------------------------------------------------------

ii. Subpart 5 Requirements
    The subpart 5 requirements, which consist of sections 191 and 192 
of the CAA, are specific provisions applicable to SO2, 
NO2 or lead nonattainment areas. Section 191 of the CAA 
requires states with areas designated nonattainment for SO2, 
NO2 or lead after November 15, 1990, to submit within 18 
months of the designation an implementation plan meeting the 
requirements of part D. The substance of the required plans is 
established by section 172(c). Section 192 sets forth attainment dates 
for nonattainment areas under section 191.
    For SO2, section 192(a) requires that attainment plans 
provide for attainment of the primary Standard as expeditiously as 
possible, but no later than five years from the date of the 
nonattainment designation. EPA designated the Marshall Area as 
nonattainment on August 5, 2013, with an attainment date of October 4, 
2018. However, because EPA is reviewing a redesignation request under 
section 107(d)(3)(E), rather than a determination of attainment under 
section 179(c), the determination of whether the Area attained by the 
attainment date set forth in section 192 is not applicable to this 
action proposing approval of West Virginia's redesignation request.
    Based on the above, EPA is proposing to find that West Virginia has 
satisfied the applicable requirements for the redesignation of the 
Marshall Area under section 110 and part D of title I of the CAA.

C. The Air Quality Improvements in the Marshall Area Are Due to 
Permanent and Enforceable Emission Reductions

    For an area to be redesignated, the state must be able to 
reasonably attribute the improvement in air quality to emission 
reductions which are permanent and enforceable.\16\ The Marshall Area 
was designated nonattainment on August 5, 2013 based on monitored data 
from 2009-2011. Since the Area was designated, several

[[Page 39514]]

large SO2 emitting facilities in the Marshall Area have 
permanently shut down, and one facility has switched to a cleaner fuel. 
On June 1, 2015 and October 9, 2015, the AEP's Kammer Power Plant 
(Kammer) and the Rain CII Carbon facility (Rain CII), respectively, 
closed permanently. On November 12, 2015 and June 10, 2016, the Eagle 
Natrium, LLC plant implemented a fuel switch from burning coal to 
burning natural gas on boiler #6 and boiler #5, respectively.\17\ The 
Mitchell Power Plant is therefore the remaining primary source of 
SO2 emissions in the Marshall Area. Mitchell has 
significantly reduced its SO2 emissions since the Area was 
designated, and these emission reductions are being made permanent and 
enforceable by the limits contained in West Virginia consent order CO-
SIP-C-2019-13. West Virginia requested that the 2019 consent order be 
incorporated into the West Virginia SIP. If this action is finalized, 
the emission limits and associated parameters in the 2019 consent order 
will become permanent and Federally-enforceable. The 2019 consent order 
requires that combined SO2 emissions from Mitchell Units 1 
and 2 be limited to a total maximum of 3,149 lbs/hr on a 30-operating 
day rolling average basis, and includes monitoring, recordkeeping, and 
reporting provisions to show compliance with the limits. Compliance 
with the 2019 consent order was required starting on January 1, 2020.
---------------------------------------------------------------------------

    \16\ See April 2014 Guidance, page 64.
    \17\ Appendix D of the March 18, 2020 West Virginia 
redesignation request includes documentation showing the permanent 
closure of the Kammer and Rain CII facilities, and the fuel switch 
at the Eagle Natrium facility, included in the docket for this 
rulemaking action.
---------------------------------------------------------------------------

    At the time of the Marshall Area's nonattainment designation, the 
monitored SO2 design value at the Moundsville monitor for 
2009-2011 was 80 ppb. These monitored values occurred before the 
permanent closure of the two facilities and the switch to burning 
natural gas at another facility mentioned in the preceding paragraph as 
well as the emission reductions at Mitchell. More recent monitoring 
data indicate that ambient SO2 levels have improved 
significantly at the monitor. The 2019 data shows the 99th percentile 
value at 9 ppb. The monitored design value for the Marshall Area for 
2017-2019 is 8 ppb, which is well below the SO2 NAAQS of 75 
ppb. This air quality improvement is attributable to the substantial 
SO2 emission reductions noted above, and therefore EPA 
proposes to find that the improvement in air quality in the Marshall 
Area can be attributed to permanent and enforceable emission 
reductions, and that CAA section 107(d)(3)(E)(iii) has been satisfied 
by West Virginia.

D. West Virginia Has a Fully Approvable Maintenance Plan for the 
Marshall Area

    CAA section 175A sets forth the elements of a maintenance plan for 
areas seeking redesignation from nonattainment to attainment. Under 
section 175A, the plan must demonstrate continued attainment of the 
applicable NAAQS for at least ten years after the nonattainment area is 
redesignated to attainment. Eight years after the redesignation, the 
state must submit a revised maintenance plan demonstrating that 
attainment will continue to be maintained for the ten years following 
the initial ten-year period. To address the possibility of future NAAQS 
violations, the maintenance plan must also contain contingency measures 
as EPA deems necessary to assure prompt correction of any future 
violations. Specifically, the maintenance plan should address five 
requirements: (1) An attainment emissions inventory; (2) a maintenance 
demonstration; (3) a commitment for continued air quality monitoring; 
(4) the verification of continued attainment; and (5) a contingency 
plan.\18\
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    \18\ See Memorandum from John Calcagni, Director, Air Quality 
Management Division, EPA, ``Procedures for Processing Requests to 
Redesignate Areas to Attainment'' September 4, 1992.
---------------------------------------------------------------------------

    In conjunction with its request to redesignate the Marshall Area, 
West Virginia submitted, as a revision to its SIP, a plan to provide 
for maintenance of the SO2 NAAQS through 2030 in the Area, 
which is 10 years after the expected effective date of the 
redesignation to attainment. West Virginia has committed to review the 
maintenance plan for the Area eight years after redesignation. The 
maintenance plan includes the five components noted previously in this 
section.
    In a maintenance plan, states are required to submit an inventory 
used for the year of attainment, which is called the attainment year 
inventory. This inventory is used as the basis for future, projected 
emission inventories that are used to show the area will remain in 
attainment. West Virginia submitted a 2016 SO2 emissions 
inventory as the attainment year inventory. The year 2016 was selected 
because it is one of the three years of monitoring data from 2016 
through 2018 for which the design value showed compliance with the 
SO2 NAAQS.
    For the 2016 attainment year inventory for point sources, West 
Virginia used actual emissions reported by each facility. Eagle Natrium 
switched its fuel source from coal to natural gas between 2015 and 
2016, resulting in lower SO2 emissions in 2016. The Kammer 
Power Plant and Rain CII Carbon plant both closed in 2015 and therefore 
there were no emissions from these plants in 2016. The point source 
emissions for the Marshall Area were verified against EPA's emissions 
inventory system (EIS) and EPA found them to be acceptable.
    Nonroad and onroad emissions for 2016 were calculated by West 
Virginia using EPA's Motor Vehicle Emissions Simulator (MOVES) 2014a 
model. NONROAD is a component of the MOVES model that is run within the 
model. Monthly results were summed to get the yearly emissions.
    Emissions for the nonpoint or area source category for 2016 were 
not available at the time of the attainment plan submittal, and so 
emissions for these sources were calculated using projections from the 
Mid Atlantic Regional Air Management Association's (MARAMA) 2017 Beta 
Modeling Inventory \19\ found in the emissions modeling framework 
(EMF). The EMF is a tool that supports the management and quality 
assurance of emissions inventories and emissions modeling-related data, 
and the running of the Sparse Matrix Operator Kernel Emissions Model 
(SMOKE) to develop air quality model inputs. West Virginia stated that 
2017 is a reasonable substitution since the MARAMA model used a ``no-
growth'' assumption for fuel usage, population, and employment between 
2016 and 2017. The 2017 projected nonpoint emissions for Marshall 
County are 49.66 tpy, while the nonpoint emissions in the National 
Emissions Inventory (NEI) 2014 version2 for Marshall County is 30 tpy, 
therefore the 2017 projected nonpoint emissions is conservative 
compared to the 2014 version2 NEI.
---------------------------------------------------------------------------

    \19\ MARAMA emissions inventories: https://www.marama.org/technical-center/emissions-inventory/2011-inventory-and-projections.
---------------------------------------------------------------------------

    Oil and gas emissions for 2016 were calculated using EPA's Oil and 
Gas Tool version 2.2 with local data from West Virginia's Geological 
and Economic Survey. These emissions represent the sum of 
SO2 generated by oil and gas production and exploration 
activities.
    Projection inventories are used to show that the area will remain 
in attainment. West Virginia, with the assistance of MARAMA, developed 
2023 and 2030 emission projections for the interim and maintenance plan 
end year, respectively. The Mitchell Power Plant is the primary point 
source still in

[[Page 39515]]

operation within the nonattainment area. The projection inventory for 
the Mitchell Power Plant is based on actual emission trends over the 
last five years. Onroad and nonroad emissions were calculated using the 
same methodologies as the 2016 attainment year inventory. For the 
nonpoint emission projections, West Virginia submitted emissions from 
MARAMA's Emissions Inventory Development for 2011 and 2017 Beta2 
Modeling Inventory, which projected emissions for 2023.\20\ The 
emissions for 2030 were ``grown'' using the emission factors used to 
calculate the 2023 emissions. Oil and gas emissions for 2023 and 2030 
were developed using Annual Energy Outlook (AEO) 2017 future year 
production projections and growth factors and following the 
methodologies documented in EPA's ``TSD for Additional Updates to 
Emissions Inventories for the Version 6.3, 2011 Emissions Modeling 
Platform for Year 2023.''
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    \20\ Mid-Atlantic Regional Air Management Association emissions 
inventories: https://www.marama.org/technical-center/emissions-inventory/2011-inventory-and-projections.
---------------------------------------------------------------------------

    EPA reviewed all the files and the emission results provided by 
West Virginia for both the attainment year inventory and the projected 
inventories and found them to be acceptable. The detailed inventory 
information for the Marshall Area is contained in appendix B of the 
March 18, 2020 SIP submittal. Appendix B, as well as EPA's Emissions 
Inventory TSD, is included in the docket for this rulemaking action. 
The inventories are shown in Table 3.

           Table 3--Emissions Inventories for the Marshall Nonattainment Area, in Tons per Year (tpy)
----------------------------------------------------------------------------------------------------------------
                                            2011 actuals    2016 actuals \a\   2023 projected    2030 projected
                 Sector                        (base)         (attainment)        (interim)       (maintenance)
----------------------------------------------------------------------------------------------------------------
EGU.....................................            21,231             3,605             2,900             2,900
Non-EGU.................................            12,792             2,556                12                12
Oil & Gas...............................            6.1001             10.55             12.76             13.46
Area (non-point)........................             51.19             49.66             45.58             45.05
Non-Road................................              0.02              0.01              0.01              0.01
On-Road.................................              2.10              2.03              0.81              0.76
                                         -----------------------------------------------------------------------
    Total...............................         34,082.41          6,223.25          2,971.16          2,971.28
----------------------------------------------------------------------------------------------------------------
\a\ With the exception of non-point sources as explained previously.

    A state may generally demonstrate maintenance of the NAAQS by 
either showing that future emissions of a pollutant or its precursors 
will not exceed the level of the attainment inventory, or by modeling 
to show that the future mix of sources and emission rates will not 
cause a violation of the NAAQS.\21\ West Virginia's projected actual 
emissions for the interim year of 2023 and for the maintenance year of 
2030 are both below the total attainment year inventory, which is 
acceptable for showing maintenance in the Marshall Area.
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    \21\ See April 2014 Guidance, page 67.
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    West Virginia has committed to continue monitoring SO2 
levels at the Moundsville monitor, and will consult with EPA prior to 
making changes to the existing monitoring network, should changes be 
needed in the future. West Virginia has committed to enter all data 
into AQS on a timely basis in accordance with Federal guidelines, and 
to continue to quality assure the monitoring data to meet the 
requirements of 40 CFR part 58 and all other Federal requirements.
    The closures of Kammer and Rain CII, and the fuel switch to natural 
gas at Eagle Natrium LLC, has resulted in significant reductions of 
SO2 emissions in the Marshall Area. The only significant 
SO2 emitting facility remaining in the Marshall Area is the 
Mitchell Power Plant.
    The new, permanent and enforceable SO2 emission limits 
for the Mitchell Power Plant described above, which were shown to be 
comparably stringent to the CEV established by the March 18, 2020 
modeling, ensure that the Marshall Area will continue attain the NAAQS.
    For the Marshall Area and SO2 in general, ``attainment 
revolves around compliance of a single source or a small set of sources 
with emission limits shown to provide for attainment,'' \22\ 
specifically the Mitchell Power Plant. West Virginia has committed to 
track the SO2 emissions and compliance status of the 
Mitchell Power Plant in order to verify that the plant complies with 
the emission limit in the 2019 consent order, so that modeling using 
the corresponding 1-hour CEV may be considered to demonstrate that the 
Area is maintaining the Standard. To demonstrate compliance with the 
SO2 emission limitations of the 2019 consent order, Kentucky 
Power is required to use the continuous emissions monitoring system 
(CEMS) installed, certified, operated, and maintained in accordance 
with 40 CFR part 75, and is required to calculate and record a 30-
operating day rolling average SO2 emission rate, updated 
after each new boiler operating day. Each 30-operating day rolling 
average emission rate is the average of all of the valid hourly 
SO2 emission rates in the 30-operating day period. The 2019 
consent order also requires the reporting of any exceedance of the 30-
operating day rolling average SO2 emission limit to WVDEP 
within five business days after the exceedance occurs, and must include 
information related to any deviations from the 30-operating day rolling 
average limit, if any, the duration of the deviation, and the cause of 
the deviation. Kentucky Power must also submit semiannual compliance 
reports to WVDEP on emissions from Mitchell Units 1 and 2. All major 
sources in West Virginia are required to submit annual emissions data, 
which the State uses to update its emission inventories as required by 
the CAA, and West Virginia has committed to provide updates to future 
inventories in accordance with EPA's AERR rule every three years. West 
Virginia has also committed to assure that existing control measures 
will remain in effect, that any changes to its rules or emissions 
applicable to SO2 as required for maintenance of the 2010 
SO2 Standard will be submitted to EPA for approval as a SIP 
revision, and that it intends to continue enforcing all rules that 
relate to the emission of SO2 precursors in the Marshall 
Area.\23\
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    \22\ See April 2014 Guidance, page 69.
    \23\ See March 18, 2020 West Virginia redesignation request 
submittal, page 28.
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    The April 2014 Guidance, pages 65-69, states that the requirement 
to submit contingency measures in accordance with section 175A(d) can 
be adequately addressed for SO2 by having a

[[Page 39516]]

comprehensive enforcement program which can quickly identify and 
address sources that might be causing exceedances of the NAAQS. To do 
so, West Virginia has committed to adopt and expeditiously implement 
necessary corrective actions as follows. A warning level response shall 
be triggered whenever the 99th percentile of the 1-hour daily 
SO2 maximum concentration of 75.5 ppb occurs in a single 
calendar year within the maintenance area (i.e., the Marshall Area). A 
warning level response will consist of a study to determine whether 
SO2 values indicate a trend toward higher ambient 
SO2 values or whether SO2 source emissions appear 
to be increasing.
    The study will evaluate whether the trend, if any, is likely to 
continue and, if so, the control measures necessary to reverse the 
trend, taking into consideration ease and timing for implementation as 
well as economic and social considerations. Implementation of necessary 
controls in response to a warning level response trigger will take 
place as expeditiously as possible, but in no event later than 12 
months from the conclusion of the most recent calendar year. If the 2-
year average of the 99th percentile of the 1-hour daily SO2 
maximum concentrations is 75 ppb or greater, or a violation of the 
SO2 NAAQS occurs within the maintenance area, an ``action 
level response'' will be triggered. If the exceedance is found to not 
be caused by an exceptional event, malfunction, or noncompliance with a 
permit condition or rule requirement, the West Virginia Division of Air 
Quality (DAQ), in conjunction with the metropolitan planning 
organization (MPO) or regional council of governments, will determine 
additional control measures needed to assure continued attainment of 
the 2010 SO2 NAAQS. Any selected measures will be those that 
can be implemented within 18 months from the close of the calendar year 
that prompted the action level response.\24\ If additional control 
measures are required, West Virginia commits to adopt the measures in 
accordance with the State's administrative process for rulemaking and 
submit an analysis to EPA to demonstrate the proposed measures are 
adequate to return the area to attainment.
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    \24\ See March 18, 2020 West Virginia redesignation request 
submittal, page 29.
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    Based on EPA's findings, the Agency proposes to find that West 
Virginia's submitted maintenance plan adequately addresses the five 
basic components necessary to maintain the SO2 NAAQS in the 
Marshall Area. EPA is proposing to find that West Virginia's 
maintenance plan for the Marshall Area is approvable per the CAA, 
including CAA section 175A and EPA guidance, and is proposing to 
approve the maintenance plan as a revision to the West Virginia SIP.

IV. The Effect of EPA's Proposed Actions

    The effect of this proposal, if finalized, would change the 
classification of the Marshall Area from nonattainment to attainment of 
the 2010 SO2 NAAQS, incorporate the emissions limits 
contained in the 2019 consent order for Mitchell into the West Virginia 
SIP, and incorporate the maintenance plan into the West Virginia SIP. 
In addition, if finalized before October 30, 2020, the redesignation 
would terminate EPA's obligation to act by that date on the 2017 SIP 
submitted for the Marshall Area, under the terms of the court order 
entered in Center for Biological Diversity v. Wheeler.

V. Proposed Actions

    EPA is proposing to find that the Marshall Area has attained the 
2010 SO2 NAAQS, as demonstrated by a modeling analysis 
reflecting a new SO2 emission limit for the Mitchell Power 
Plant. EPA is also proposing that West Virginia has met the planning 
requirements necessary for EPA to redesignate the Marshall Area from 
nonattainment to attainment of the 2010 SO2 NAAQS, including 
the requirements for permanent and enforceable measures, submission of 
an approvable maintenance plan that will assure attainment for ten 
years after redesignation, and that all other CAA requirements under 
section 110 and part D, as discussed in this rulemaking, have been met. 
EPA is also proposing to approve the Marshall Area redesignation 
request, maintenance plan, SO2 emission limits and 
associated compliance parameters for Mitchell in the 2019 consent 
order, and the modeling demonstration showing that the limits provide 
for maintenance. EPA is proposing these actions under the CAA.

VI. Incorporation by Reference

    In this document, EPA is proposing to include in a final EPA rule 
regulatory text that includes incorporation by reference. In accordance 
with requirements of 1 CFR 51.5, EPA is proposing to incorporate by 
reference West Virginia consent order CO-SIP-C-2019-13. EPA has made, 
and will continue to make, these materials generally available through 
https://www.regulations.gov and at the EPA Region III Office (please 
contact the person identified in the For Further Information Contact 
section of this preamble for more information).

VII. Statutory and Executive Order Reviews

    Under the CAA, the redesignation of an area to attainment and the 
accompanying approval of the maintenance plan under CAA section 
107(d)(3)(E) are actions that affect the status of a geographical area 
and do not impose any additional regulatory requirements on sources 
beyond those required by state law. A redesignation to attainment does 
not in and of itself impose any new requirements, but rather results in 
the application of requirements contained in the CAA for areas that 
have been redesignated to attainment. Moreover, the Administrator is 
required to approve a SIP submission that complies with the provisions 
of the Act and applicable Federal regulations. 42 U.S.C. 7410(k); 40 
CFR 52.02(a). Thus, in reviewing SIP submissions, EPA's role is to 
approve state choices, provided that they meet the criteria of the CAA. 
Accordingly, this action merely approves state law as meeting Federal 
requirements and does not impose additional requirements beyond those 
imposed by state law. For these reasons, this proposed action:
     Is not a ``significant regulatory action'' subject to 
review by the Office of Management and Budget under Executive Orders 
12866 (58 FR 51735, October 4, 1993) and 13563 (76 FR 3821, January 21, 
2011);
     Is not an Executive Order 13771 (82 FR 9339, February 2, 
2017) regulatory action because it is not a significant regulatory 
action under Executive Order 12866.
     Does not impose an information collection burden under the 
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
     Is certified as not having a significant economic impact 
on a substantial number of small entities under the Regulatory 
Flexibility Act (5 U.S.C. 601 et seq.);
     Does not contain any unfunded mandate or significantly or 
uniquely affect small governments, as described in the Unfunded 
Mandates Reform Act of 1995 (Pub. L. 104-4);
     Does not have federalism implications as specified in 
Executive Order 13132 (64 FR 43255, August 10, 1999);
     Is not an economically significant regulatory action based 
on health or safety risks subject to Executive Order 13045 (62 FR 
19885, April 23, 1997);

[[Page 39517]]

     Is not a significant regulatory action subject to 
Executive Order 13211 (66 FR 28355, May 22, 2001);
     Is not subject to requirements of Section 12(d) of the 
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 
note) because application of those requirements would be inconsistent 
with the CAA; and
     Does not provide EPA with the discretionary authority to 
address, as appropriate, disproportionate human health or environmental 
effects, using practicable and legally permissible methods, under 
Executive Order 12898 (59 FR 7629, February 16, 1994).
    In addition, this proposed rulemaking redesignating the Marshall 
Area, approving the Marshall Area maintenance plan, and approving other 
related SIP revisions, does not have tribal implications as specified 
by Executive Order 13175 (65 FR 67249, November 9, 2000), because the 
SIP is not approved to apply in Indian country located in the state, 
and EPA notes that it will not impose substantial direct costs on 
tribal governments or preempt tribal law.

List of Subjects

40 CFR Part 52

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

40 CFR Part 81

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

    Dated: June 18, 2020.
Cosmo Servidio,
Regional Administrator, Region III.
[FR Doc. 2020-13585 Filed 6-30-20; 8:45 am]
BILLING CODE 6560-50-P