[Federal Register Volume 84, Number 121 (Monday, June 24, 2019)]
[Proposed Rules]
[Pages 29456-29471]
[FR Doc No: 2019-13294]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R03-OAR-2019-0044; EPA-R05-OAR-2015-0699; FRL-9995-43-Region 3 and
5]

Approval of Air Quality Implementation Plans; Ohio and West
Virginia; Attainment Plans for the Steubenville, Ohio-West Virginia
2010 Sulfur Dioxide Nonattainment Area

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to
approve, under the Clean Air Act (CAA), two State Implementation Plan
(SIP) revision submittals, submitted by Ohio and West Virginia,
respectively. Ohio's requested SIP revision was submitted to EPA
through the Ohio Environmental Protection Agency (OEPA) on April 1,
2015 with supplemental submissions on October 13, 2015 and March 25,
2019, with expectation of an additional submittal within two to three
months. This additional submittal is expected to include final, adopted
limits corresponding to the limits in proposed form in the March 25,
2019 submittal. West Virginia's requested SIP revision was submitted to
EPA through the West Virginia Department of Environmental Protection
(WVDEP) on April 25, 2016 with a supplemental submission from WVDEP on
November 27, 2017 and a clarification letter on May 1, 2019. The Ohio
and West Virginia submittals include each State's attainment
demonstration for the Steubenville Ohio-West Virginia sulfur dioxide
(SO2) nonattainment area (hereinafter ``Steubenville Area''
or ``Area''). Each state plan contains an attainment demonstration,
enforceable emission limits and control measures and other elements
required under the CAA to address the nonattainment area requirements
for the Steubenville Area.
    EPA proposes to conclude that the Ohio and West Virginia attainment
plan submittals demonstrate that the provisions in the States'
respective plans provide for attainment of the 2010 1-hour primary
SO2 national ambient air quality standard (NAAQS) in the
entire Steubenville Area and meet the requirements of the CAA. EPA is
also proposing to approve into the West Virginia SIP new emissions
limits, operational restrictions, and associated compliance
requirements for Mountain State Carbon, and proposing to approve into
the Ohio SIP the limits on emissions from Mingo Junction Energy Center
and JSW Steel as well as the proposed limits for the Cardinal Power
Plant.

DATES: Written comments must be received on or before July 24, 2019.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R03-
OAR-2019-0044 for comments relating to West Virginia or EPA-R05-2015-
0699 for comments relating to Ohio at http://www.regulations.gov, or
via email to<EMAIL_ADDRESS>at EPA Region III or to
<EMAIL_ADDRESS>at EPA Region V. 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 http://www2.epa.gov/dockets/commenting-epa-dockets.

FOR FURTHER INFORMATION CONTACT: Marilyn Powers at EPA Region III,
Planning & Implementation Branch (3AD30), Air & Radiation Division,
U.S. Environmental Protection Agency, Region III, 1650 Arch Street,
Philadelphia, Pennsylvania 19103,<PHONE_NUMBER>,
<EMAIL_ADDRESS>John Summerhays at EPA Region V, Attainment
Planning and Maintenance Section, Air Programs Branch (AR-18J),
Environmental Protection Agency, Region V, 77 West Jackson Boulevard,
Chicago, Illinois 60604,<PHONE_NUMBER><EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION: Throughout this document whenever ``we,''
``us,'' or ``our'' is used, we mean EPA.
    The following outline is provided to aid in locating information in
this preamble.

Table of Contents

I. Why were Ohio and West Virginia required to submit SO2
plans for the Steubenville Area?
II. Requirements for SO2 Nonattainment Area Plans
III. Attainment Demonstration and Longer-Term Averaging
IV. Review of Modeled Attainment Plan
    A. Which modeling analysis is Ohio and West Virginia relying on?
    B. Model Selection
    C. Meteorological Data
    D. Receptor Network
    E. Emissions Data
    F. Source Characterization
    G. Emission Limits
    H. Background Concentrations
    I. Assessment of Plant-Wide Emission Limit for Cardinal
    J. Summary of Results
V. Review of Other Plan Requirements
    A. Emissions Inventory
    B. Reasonably Available Control Measures/Reasonably Available
Control Technology (RACM/RACT)
    C. New Source Review (NSR)
    D. Reasonable Further Progress (RFP)
    E. Contingency Measures
VI. EPA's Proposed Action
VII. Incorporation by Reference Section
VIII. Statutory and Executive Order Reviews

I. Why were Ohio and West Virginia required to submit SO2
plans for the Steubenville Area?

    On June 22, 2010, EPA promulgated 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. See 75 FR 35520, codified at 40 CFR 50.17(a)-(b). On
August 5, 2013, EPA designated a first set of 29 areas of the country
as nonattainment for the 2010 SO2 NAAQS, including the
Steubenville nonattainment area comprised of portions within Ohio and
West Virginia. See 78 FR 47191, codified at 40 CFR part 81, subpart C,
Sec. Sec.  81.336 and 81.349. These area designations became effective
October 4, 2013. Section 191(a) of the CAA directs states to submit
SIPs for areas designated as nonattainment for the SO2

NAAQS to EPA within 18 months of the effective date of the designation,
i.e., by no later than April 4, 2015 in this case. Under CAA section
192(a), these SIPs are required to demonstrate that their respective
areas will attain the NAAQS as expeditiously as practicable, but no
later than five years from the effective date of designation, which is
October 4, 2018.
    For a number of areas, including the West Virginia portion of the
Steubenville Area, EPA published a notice on March 18, 2016 finding
that West Virginia and other states had failed to submit the required
SO2 attainment SIPs by this submittal deadline. See 81 FR
14736. This finding initiated a deadline under CAA section 179(a) for
the potential imposition of new source and highway funding sanctions.
Ohio submitted its SO2 attainment plan before the required
deadline, therefore, EPA did not make such a finding with respect to
Ohio's submittal for the Ohio portion of the Steubenville Area.
Pursuant to West Virginia's submittal of its attainment plan on April
25, 2016, which became complete by operation of law, EPA subsequently
notified West Virginia via letter dated June 13, 2017 that the SIP
submittal was complete and that sanctions under section 179(a) would
not be imposed in West Virginia due to its prior failure to submit a
SIP. Additionally, under CAA section 110(c), the failure to submit
finding triggered a requirement that EPA promulgate a Federal
implementation plan (FIP) for West Virginia within two years of the
finding unless, by that time (a) the state has made the necessary
complete submittal and (b) EPA has approved the submittal as meeting
all applicable requirements. The FIP obligation for West Virginia will
no longer apply if EPA finalizes the approval that is proposed in
today's action. The SIPs that West Virginia and Ohio submitted focus on
four sources in the Steubenville area. The significant source in Brooke
County, West Virginia, is the Mountain State Carbon facility (Mountain
State Carbon), located in Follansbee. The other three significant
sources in the Steubenville area are in Jefferson County, Ohio. Two of
these facilities are located in Mingo Junction, namely the Mingo
Junction Energy Center and the JSW Steel facility.\1\ The other
significant source in Jefferson County is the Cardinal power plant
(Cardinal) located near Brilliant, Ohio.
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    \1\ Although this facility (formerly owned by Wheeling-
Pittsburgh Steel and other owners) is identified as Mingo Junction
Steel Works, LLC in Ohio's rules, this action will refer to this
facility by the name of its current owners, JSW Steel.
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    In accordance with section 172(c) of the CAA, the April 25, 2016
West Virginia SO2 attainment plan submittal for the West
Virginia portion of the Area includes a 2011 base year emissions
inventory; an attainment demonstration; the assertion that West
Virginia's existing SIP-approved NSR program meets the applicable
requirements for SO2; requirements for RFP toward attaining
the SO2 NAAQS; a determination that the control strategy for
the primary SO2 source within the nonattainment areas
constitutes RACM/RACT; contingency measures; and a consent order
between West Virginia and Mountain State Carbon (the primary
SO2 source in the West Virginia portion of the Area) that
includes emission limitations, operational restrictions, and associated
compliance requirements for Mountain State Carbon, which WVDEP
requested be incorporated into the West Virginia SIP. The attainment
demonstration is comprised of an analysis that locates, identifies, and
quantifies sources of emissions contributing to violations of the 2010
SO2 NAAQS in the Steubenville Area and dispersion modeling
of the emissions control measures in the Area that shows attainment of
the 2010 SO2 NAAQS. On November 27, 2017, WVDEP submitted a
revised consent order for Mountain State Carbon to clarify certain
provisions related to enforceability.
    Likewise, Ohio's April 1, 2015 submittal for the Ohio portion of
the Steubenville Area, as supplemented on October 13, 2015, included
the nonattainment area submittal requirements under sections 172, 191
and 192 of the CAA. The supplemental submittal included rules which in
the Steubenville Area limited the emissions of Mingo Junction Energy
Center and JSW Steel.
    On March 25, 2019, Ohio provided a requested SIP revision comprised
of proposed further revisions to Ohio Administrative Code (OAC) Rule
3745-18-47, along with proposed revisions to associated compliance
provisions in OAC Rules 3745-18-03 and 3745-18-04. The proposed SIP
revision would modify the SO2 limit for the coal-fired
boilers at Cardinal. In the submittal, Ohio requested that EPA initiate
action to propose approval of its attainment SIP concurrently with
Ohio's administrative process to adopt the rule and submit the rule as
a SIP revision to EPA. Under this process, EPA publishes its notice of
proposed rulemaking in the Federal Register and solicits public comment
in approximately the same time frame during which Ohio is completing
its rulemaking process. OEPA provided an anticipated schedule for
submittal of the final SIP package to EPA. If changes are made to the
SIP revision after this proposal, such changes will be described in
EPA's final rulemaking action and, if such changes are significant, EPA
may re-propose the action and provide an additional public comment
period before issuing a final action.
    The remainder of this notice describes the requirements that such
plans must meet in order to obtain EPA approval, provides a review of
each States' plan with respect to these requirements, and describes
EPA's proposed action on the plans.

II. Requirements for SO2 Nonattainment Area Plans

    Nonattainment area SIPs must meet the applicable requirements of
the CAA, and specifically CAA sections 110, 172, 191 and 192. The EPA's
regulations governing nonattainment area SIPs are set forth at 40 CFR
part 51, with specific procedural requirements and control strategy
requirements residing at subparts F and G, respectively. Soon after
Congress enacted the 1990 Amendments to the CAA, EPA issued
comprehensive guidance on SIPs, in a document entitled the ``General
Preamble for the Implementation of Title I of the Clean Air Act
Amendments of 1990,'' published at 57 FR 13498 (April 16, 1992)
(General Preamble). Among other things, the General Preamble addressed
SO2 SIPs and fundamental principles for SIP control
strategies. Id., at 13545-49, 13567-68. On April 23, 2014, the EPA
issued recommended guidance for meeting the statutory requirements in
SO2 SIPs, in a document entitled, ``Guidance for 1-Hour
SO2 Nonattainment Area SIP Submissions,'' (April 2014
guidance) available at https://www.epa.gov/sites/production/files/2016-06/documents/20140423guidance_nonattainment_sip.pdf. In the April 2014
guidance, EPA described the statutory requirements for a complete
nonattainment area SIP, which includes: An accurate emissions inventory
of current emissions for all sources of SO2 within the
nonattainment area; an attainment demonstration; enforceable emissions
limitations and control measures; demonstration of RFP; implementation
of RACM (including RACT); NSR; and adequate contingency measures for
the affected area.
    In order for EPA to fully approve a SIP as meeting the requirements
of CAA sections 110, 172 and 191-192 and EPA's regulations at 40 CFR
part 51, the SIP for the affected area needs to demonstrate to EPA's
satisfaction that

each of the aforementioned requirements have been met. Under CAA
sections 110(l) and 193, EPA may not approve a SIP that would interfere
with any applicable requirement concerning NAAQS attainment and RFP, or
any other applicable requirement, and no requirement in effect (or
required to be adopted by an order, settlement, agreement, or plan in
effect before November 15, 1990) in any area which is a nonattainment
area for any air pollutant, may be modified in any manner unless it
insures equivalent or greater emission reductions of such air
pollutant.

III. 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. 40 CFR part 51, subpart G further delineates
the control strategy requirements that SIPs must meet, and EPA has long
required that all SIPs and control strategies reflect four fundamental
principles of quantification, enforceability, replicability, and
accountability. General Preamble, at 13567-68. SO2
attainment plans 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, pp. 22 to 39. The 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
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 pp. 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 (DC Cir. 2012). Because the standard has this form, a single
exceedance of the NAAQS' 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 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' 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'' \2\ shows three,
not four days with maximum hourly levels exceeding 75 ppb) is labeled
the ``critical emission value.'' The modeling process for identifying
this critical emissions value 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
critical emission value. 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 critical emission value.
EPA also acknowledges the concern that longer term emission limits can
allow short periods with emissions above the critical emission value
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 critical emission value. However, for
several reasons, EPA believes that the approach recommended in its
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 critical emission value 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.
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    \2\ An ``average year'' is used to mean a year with average air
quality. While 40 CFR 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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    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
critical emission value but on average, and presumably at most times,
to emit well below the critical emission value. 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-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
critical emission value 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
critical emission value), 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 critical
emission value. 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 critical emission value--
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 critical emissions
value. 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 critical emission value), 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.\3\ 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 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 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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    \3\ For example, if the critical emission value is 1000 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).\4\ 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 23, 2014
SO2 nonattainment area SIP 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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    \4\ The 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 future 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 <IP_ADDRESS> 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).

IV. Review of Modeled Attainment Plans

    Ohio and West Virginia have submitted various modeling analyses of
prospective allowable SO2 air quality in the Steubenville,
OH-WV area. Ultimately, Ohio and West Virginia reached agreement on a
common set of modeling runs that may be considered their joint
attainment demonstration, which Ohio submitted on March 25, 2019 and
West Virginia concurred with on May 1, 2019. The following subsection
describes the history and nature of these various modeling analyses.
Subsequent subsections review various features of the air dispersion
modeling in Ohio's and West Virginia's joint attainment demonstration.
Additional, more detailed discussion of the modeling is contained in
the EPA technical support document (TSD) for today's action, which is
available in the docket for this proposed rulemaking.

A. History of Ohio's and West Virginia's Modeling Analyses

    Ohio and West Virginia have made a variety of submittals in
response to the requirements for nonattainment plans for SO2
for the Steubenville area. As noted above, Ohio submitted its
nonattainment plans for Steubenville and other areas on April 1, 2015.
(A supplemental submittal dated October 13, 2015 provides rules with
limits that are reflected in these nonattainment plans but does not
change the pertinent modeling analyses.) West Virginia submitted its
nonattainment plan for the Steubenville area on April 25, 2016, and on
November 27, 2016, submitted a supplemental submission that changed
certain provisions of the consent order with Mountain State Carbon.
    Ohio's and West Virginia's modeling analyses were similar in most
respects but differed in important respects as well. Both modeling
analyses used a hybrid approach to characterize the release of fugitive
emissions from the Mountain State Carbon facility, using hourly
meteorology to estimate hourly plume heights and initial plume
dispersion, as discussed at length below. Both analyses used the same
version of AERMOD, the same receptor grid, the same set of modeled
sources, the same emission rates for these facilities, and the same
background concentration. However, Ohio and West Virginia used
different meteorological data sets and used different approaches to
characterize the release of emissions from Cardinal.
    Ohio used meteorological data for a 1-year period from July 1, 2013
to June 30, 2014, using data from a tower near Mountain State Carbon to
represent meteorology in the northern part of the area and using data
from a station near Cardinal to represent meteorology in the southern
part of the area. In contrast, West Virginia used meteorological data
from a 3-year period from 2007 to 2009 from the tower near Mountain
State Carbon to represent meteorology throughout the area.
    Cardinal has three boilers, two of which (Units 1 and 2) emit from
separate vents on a single stack and one of which (Unit 3) is vented
out the top of a cooling tower that services the

facility. Ohio represented the release from Units 1 and 2 as being
released from the actual height of the stack. For Unit 3, Ohio found
that the use of actual cooling tower parameters yielded concentration
estimates dramatically unlike the concentrations monitored nearby, and
Ohio instead used a hybrid approach (similar in some respects to the
approach used in modeling Mountain State Carbon). West Virginia used
the same characterization of Units 1 and 2 but for Unit 3 used the
stack height and other release characteristics of a previously used
Unit 3 stack.
    EPA also conducted modeling of this Area, to inform discussions
among EPA and the states regarding this Area. This modeling used West
Virginia's meteorological data but used a different characterization of
the stacks at Cardinal, for Units 1 and 2 using the height calculated
from the formula in 40 CFR 51.100(ii)(2)(ii) (the stack height
regulations) and for Unit 3 using the actual stack height in
combination with historic other release characteristics.
    Finally, as noted above, Ohio and West Virginia agreed on a joint
attainment demonstration, which Ohio submitted on March 25, 2019 and
West Virginia concurred with on May 1, 2019. This modeling used West
Virginia's meteorological data, used EPA's characterization of the
release of emissions from the stacks at Cardinal, but used an updated
background concentration and demonstrated attainment based on an
allowable Cardinal emission level that was somewhat higher than the
previously modeled level. The details of this joint attainment
demonstration and EPA's review are provided in the following
subsections.

B. Model Selection

    Ohio and West Virginia used the EPA-recommended AERMOD Model
(version 18081, the most recent version) for their joint attainment
demonstration. AERMOD is a refined, steady-state (both emissions and
meteorology over a 1-hour time step), multiple source, air-dispersion
model that, according to the Guideline on Air Quality Models, is the
preferred model to use for industrial sources in this type of air
quality analysis.

C. Meteorological Data

    The joint attainment demonstration used processed meteorological
data from Mountain State Carbon's 50 m meteorological tower in
Follansbee, reflecting the data used in West Virginia's original
attainment demonstration. Meteorological tower measurements were taken
at 2 meters, 10 meters and 50 meters and included wind direction, wind
speed, temperature and turbulence measurements. Additional surface
meteorological data also came from the Pittsburgh International Airport
located in western Pennsylvania, as necessary when data were not
available from the Follansbee tower. One-minute data from Pittsburgh,
Pennsylvania were processed using AERMINUTE (version 14337) and
included in AERMET's (version 14134) Stage 2 processing. Surface
characteristics were processed seasonally according to the Stage 3 file
included in West Virginia's modeling files. Upper-air soundings needed
to create the final processed meteorology data sets came from
Pittsburgh. Three years of meteorological data from 2007-09 were
processed in AERMET to produce the surface and profile files used in
West Virginia's modeling demonstration. The Mountain State Carbon
meteorological tower is considered an on-site measurement and therefore
meets the minimum records length requirement (one year) outlined in
section 8.4.2(e) of appendix W. The Guideline recommends using up to
five years of on-site data where available. In this case, since
subsequent years had significant missing data, EPA believes that the
three years of data from 2007 to 2009 provides as good or better
representation of meteorology in the area as any other available data
set. Given the close location of the Follansbee met tower, EPA believes
that the meteorological data is likely representative of conditions in
the northern portion of the Steubenville area near Mountain State
Carbon and the Mingo Junction facilities, where the highest collective
impacts from the various sources in the area are estimated to occur.
EPA believes the tower provides good measurements of the flow within
the Ohio River Valley where the nonattainment sources are located,
which is important because relatively steep terrain surrounding the
Ohio River creates complex wind flows as air channels through the
valley.

D. Receptor Network

    In their joint demonstration, Ohio and West Virginia used a
receptor network with 21,476 receptors within the nonattainment area.
Ohio also conducted additional modeling using numerous receptors
outside the nonattainment area that demonstrated that the limits also
provide for attainment outside the nonattainment area as well. Further
discussion of the receptor network is provided in the TSD. EPA finds
the receptor network used in the joint demonstration to be consistent
with EPA guidance.

E. Emissions Data

    The joint modeling analysis included SO2 emissions from
the Mountain State Carbon coke plant and three facilities in Ohio
including Cardinal, the Mingo Junction Energy Center, and JSW Steel.
The modeling includes 59 emission points from these four facilities,
including 48 emission points from the Mountain State Carbon coke plant.
    The consent order for Mountain State Carbon sets limits applicable
most of the year reflecting well controlled operation of coke oven gas
desulfurization equipment. The consent order authorizes the company to
shut down this control equipment for maintenance for up to 10 days in
April and 10 days in November, while continuing coke production;
however, the consent order also establishes a limit on coal sulfur
content and limits operation of the coke plant, to minimize the
SO2 emissions during these periods. The joint modeling
analysis uses an hourly emissions file reflecting the lower limits most
of the year but reflecting the higher emissions associated with the
restrictions that apply for 10 days in April and November.
    Mingo Junction Energy Center is currently not operating. However,
this facility is authorized to restart partially, and is subject to
limits in Ohio's rules that would allow modest emissions upon
restarting. Ohio's and West Virginia's modeling both appropriately
reflect the emissions this facility would be allowed to emit, were it
to resume operating. JSW Steel was not operating at the time of Ohio's
original rule adoption, but this facility has resumed operation,
subject to the adopted limits.
    Cardinal was modeled as emitting 6,942 pounds per hour (lbs/hr) of
SO2. As discussed further below, in Subsection F, in lieu of
setting a 1-hour emission limit at this level, Ohio determined that a
comparably stringent 30-day average emission limit would be 4,858.75
pounds per hour, which is the limit that Ohio has proposed. No other
source emitting 100 tons of SO2 per year or more is located
within the nonattainment area in either Ohio or West Virginia. Table 1
shows the hourly allowable emissions and the modeled emissions (annual
total) from the four facilities that were included in the attainment
demonstration. The modeled emission rate for Cardinal in this table
corresponds to the modeled emission rate of 6,942 pounds per hour, even
though annual emissions would not be allowed to be greater than 21,281
tons per year (tpy), corresponding to the 30-

day average limit of 4,858.75 pounds per hour (lb/hr).

                    Table 1--Facility Total Emissions
------------------------------------------------------------------------
                                                              Modeled
                                      Hourly allowable       combined
             Facility                 emissions (lb/hr)    emission rate
                                                               (tpy)
------------------------------------------------------------------------
Mountain State Carbon, West         See below...........         2,229.7
 Virginia.
Mingo Junction Energy Center, Ohio  0.0028 lb/MMBTU *...             8.8
JSW Steel, Ohio...................  120.................           534.4
Cardinal, Ohio....................  4,859...............        30,406.7
------------------------------------------------------------------------
* Corresponds to a maximum of 2 lb/hr.

    West Virginia's consent order for Mountain State Carbon establishes
individual limits for numerous emission points at the facility. Some of
these limits are in the form of 1-hour limits, applicable every day of
the year. Other limits are expressed as 24-hour average limits. Table 2
shows the emission limits included in West Virginia's consent order and
the emission rate. For the emission points with 24-hour average limits,
the limits are set at a lower level than the emission rate used in the
attainment demonstration; the relationship between these two values is
discussed in more detail in Subsection F below. (Subsection F also
discusses the relationship between the critical emission value and the
30-day average limit that Ohio has proposed for Cardinal.)

                              Table 2--Limits for Sources at Mountain State Carbon
----------------------------------------------------------------------------------------------------------------
                                                                      Emission limits, lbs/hr
                                                                 --------------------------------      Limit
                             Source                                   Normal          Outage      averaging time
                                                                     operation       operation        (hours)
----------------------------------------------------------------------------------------------------------------
Pushing Emission Control Sources
    #1, 2, and 3 Batteries......................................           10.48           10.48               1
    #8 Battery..................................................           15.72           15.72               1
Acid Plant Tail Gas Scrubber....................................             6.0               0              24
Battery 1 Combustion............................................            21.4         * 241.5              24
Battery 2 Combustion............................................            21.4          * 76.8              24
Battery 3 Combustion............................................            24.5          * 76.8              24
Battery 8 Combustion............................................           115.4         * 360.6              24
Batteries 6, 7, 9,10 Combustion Stack...........................            85.7         * 344.8              24
Excess COG Flare................................................           137.7         * 241.5              24
----------------------------------------------------------------------------------------------------------------
* As described in section V.B, the consent order establishes operational restrictions on the ovens and other
  measures to limit SO2 emissions during the outages. The modeled rates during the outages were engineering
  estimates for maximum emissions with the required operational restrictions and measures.

    No other source emitting 100 tons of SO2 per year or
more is located within the nonattainment area in either state, and the
nearest source emitting 100 tons of SO2 per year outside of
Ohio (i.e., in West Virginia or Pennsylvania) is about 35 kilometers
south, in the Marshall County nonattainment area, sufficiently distant
that explicit modeling of that source is not warranted for the
Steubenville Area. According to the 2014 National Emissions Inventory
(NEI), two other Ohio sources emitting over 100 tons of SO2
per year are located within 50 kilometers of the nonattainment area,
both within Jefferson County, Ohio. The first is the Sammis plant,
located in Stratton, 20 kilometers north of the modeled design site
near Steubenville, and which in 2014 emitted 10,262 tons of
SO2. The second is a landfill, located in Amsterdam, 25
kilometers northwest of the modeled design value, and which in the 2014
NEI is estimated to emit 206 tons of SO2 per year. The most
common wind directions in this area are from the south and southwest,
and modeling shows that these are the applicable wind directions at the
times the design concentrations were modeled to occur. During these
times, these sources would not be upwind of the nonattainment area.
Furthermore, these sources are relatively distant from the relevant
portions of the nonattainment area (and the concentration gradients in
the area of interest resulting from these sources can be presumed to be
relatively insignificant). For these reasons, explicit modeling of
these sources to the north and northwest of the area would not have
altered the design concentrations in the nonattainment area, and
explicit modeling of these sources is not warranted.

F. Source Characterization

    Emissions from Mingo Junction Energy Center and from JSW Steel are
released from conventional stacks, and Ohio and West Virginia have
modeled these sources as point sources with reasonable stack
parameters. However, determining appropriate release characteristics
for Mountain State Carbon and Cardinal is considerably more difficult.
    The various SO2 emission points at Mountain State Carbon
were modeled as either point sources or as volume sources. In numerous
cases, emissions are released out of a stack, and these emissions were
modeled as point sources with the associated stack parameters. Of
particular note is one coke oven gas flare, which was modeled as a
point source with its actual release height and typical other release
characteristics. Fugitive coke battery emissions were modeled as volume

sources, using hourly release heights and initial vertical dispersion
values, reflecting hourly estimates from an independent run of the BLP
dispersion model, which were entered into the hourly varying input file
for use in AERMOD. As noted by West Virginia, this technique was used
in previous particulate matter (PM10) modeling
demonstrations and was also used for the Allegheny County, Pennsylvania
modeling demonstration for the 1-hour SO2 nonattainment
area. The BLP/AERMOD hybrid approach, however, is considered an
alternative model under section 3.2.2 of appendix W--Guideline on Air
Quality Models, and therefore requires approval from EPA's Regional
Administrator as well as concurrence from EPA's Model Clearinghouse.
    Allegheny County confronted similar circumstances in developing a
plan for assuring attainment near the Clairton Works coke batteries,
also involving coke plants in relatively complex terrain. The Allegheny
County Health Department (ACHD) conducted extensive statistical
analyses, finding that the same hybrid approach that West Virginia and
Ohio used provides a more realistic simulation of fugitive emissions
from coke ovens in that area than more conventional characterizations
of the release of these emissions.\5\ A more complete description of
the ACHD approach can be found in the Model Clearinghouse Information
Storage and Retrieval System (Record No: 18-III-01).\6\
---------------------------------------------------------------------------

    \5\ See appendix A and I of Allegheny County Health Department's
1-Hour SO2 SIP available in Docket No. EPA-R03-OAR-2017-
0730 (83 FR 58206, November 19, 2018).
    \6\ https://cfpub.epa.gov/oarweb/MCHISRS/index.cfm?fuseaction=main.resultdetails&recnum=18-III-01.
---------------------------------------------------------------------------

    EPA Region 3 approved and requested concurrence from the Model
Clearinghouse on the use for Mountain State Carbon of the same BLP/
AERMOD hybrid approach for the fugitive coke oven emissions that
Allegheny County justified for Clairton Works, based on the
similarities of the sources and the complex terrain and meteorology in
the two areas. On October 30, 2018 the Model Clearinghouse granted
concurrence with EPA Region 3's approval to use the BLP/AERMOD hybrid
approach for Mountain State Carbon's fugitive coke oven emissions. This
concurrence is available on EPA's Model Clearinghouse Information
Storage and Retrieval System, Record No: 18-III-02 \7\ and explains
that the Model Clearinghouse concurred on the alternate model approval
for the West Virginia SIP based on the unique similarities between the
emissions sources at these two facilities, the similarities in complex
topographical and meteorological settings surrounding these two
facilities, and the similarities in alternative modeling approach for
assessing the fugitive emissions from the coke oven batteries at these
two facilities. Since Ohio as well as West Virginia is relying on this
alternative modeling approach, Region 5 has also requested Model
Clearinghouse concurrence on the use of this approach in the joint
attainment plan, which the Model Clearinghouse has granted.\8\
---------------------------------------------------------------------------

    \7\ https://cfpub.epa.gov/oarweb/MCHISRS/index.cfm?fuseaction=main.resultdetails&recnum=18-III-02.
    \8\ See the concurrence on EPA's Clearinghouse Information
Storage and Retrieval System, Record No: 19-V-01, available at
https://cfpub.epa.gov/oarweb/MCHISRS/index.cfm?fuseaction=main.resultdetails&recnum=19-V-01.
---------------------------------------------------------------------------

    Characterizing the release of emissions from Cardinal also poses
significant challenges. The emissions for Unit 3 are released from a
cooling tower, i.e. with nearly unique release characteristics. The
emissions for Units 1 and 2 are released from a more conventional
stack, although the vents for these two units are on the same stack in
very close proximity, which raises the question whether modeling these
releases as a merged plume is appropriate. The following discussion
summarizes Ohio's and West Virginia's rationale for their approach in
the joint attainment demonstration. More detailed discussion of the
characterization of these releases from Cardinal are provided in the
TSD for this action.
    The cooling tower at Unit 3 has a height of approximately 129
meters and a diameter at the top of approximately 56 meters. Modeling
conducted by Ohio shows that modeling using these stack dimensions
yields a peak concentration over 20,000 [mu]g/m\3\ and widespread
modeled concentrations over 10,000 [mu]g/m\3\, dramatically higher than
the concentrations measured at well-placed nearby monitoring sites.
These unrealistic concentration estimates are presumably the result of
mischaracterization of the dispersion from such a wide opening, unlike
the more conventional stack diameters present in the studies that
informed the development of AERMOD. In the course of working with the
states on planning for this Area, EPA conducted an additional modeling
run using more conventional stack parameters, in particular using the
actual release height of 129 meters but otherwise using the stack
parameters used in West Virginia's original modeling analysis,
reflecting the diameter and exit gas characteristics of the prior
(conventional) stack at Cardinal's Unit 3. This run used actual
emissions for a one-year period from July 1, 2013 to June 30, 2014,
yielding concentration estimates that could be compared to the
concentrations measured at multiple nearby monitoring sites. This run
demonstrated that simulating the Unit 3 emissions as being released
from a conventional stack yields concentration estimates that are
dramatically closer to the observed concentrations. Indeed, based on a
comparison of peak concentrations, 99th percentile concentrations, and
the average of the top 25 concentrations modeled and monitored at four
nearby monitoring locations, EPA found that modeling the Unit 3
emissions as being released from a conventional stack with the noted
stack characteristics provides a reasonable characterization of this
plume. Additional details of this modeling are provided in the appendix
to the TSD for this rulemaking. The subsequent state model runs,
including the model runs underlying the joint attainment demonstration,
reflect this characterization of the release of emissions from Unit 3.
    EPA has also examined whether the emissions from Units 1 and 2
warrant being merged. The emissions from these units are vented out of
different vents from a single stack. Satellite imagery indicates that
the top of the stack is approximately 22 meters in diameter, and the
vents are approximately 9 meters in diameter with less than 2 meters
separation between the edges of the two vents. Consequently, treating
the release of the emissions from these two units as a single combined
release (which, given the similarity of the two units, means modeling a
single plume with twice the heat flux) provides for the best simulation
of expected plume behavior. Nevertheless, EPA's stack height
regulations restrict the circumstances under which plume merging is
creditable.
    Under 40 CFR 51.100(hh), plume merging is defined to be a
prohibited dispersion technique except, in the case of merging
occurring after July 8, 1985, for cases in which such merging is part
of a change in operation at the facility that includes the installation
of pollution controls and is accompanied by a net reduction in the
allowable emissions of a pollutant. (See 40 CFR 51.100(hh)(2)(B)). The
stack height regulations also note that this exclusion from the
definition of dispersion techniques shall apply only to the emission
limitation for the pollutant affected by such change in operation.
    As a compliance strategy for meeting the requirements of the Clean
Air

Interstate Rule (CAIR), Cardinal began operation of flue gas
desulfurization of the emissions from Units 1 and 2 on March 25, 2008
and December 15, 2007, respectively. Available evidence indicates that
the construction of the new stack to vent the emissions from these
units was part of the same project as installation of flue gas
desulfurization equipment. Although Ohio is proposing its emission
limit reflecting a reduction of allowable emissions several years after
the installation of the pollution controls, the merging accompanied the
installation of controls and may also be considered to accompany a net
reduction in allowable emissions in the sense that the initial request
for credit for merging (in this SIP) is accompanied by a limit that
requires the net emission reduction that the Cardinal control project
achieved. In addition, although CAIR did not establish specific
emission limits for Cardinal, CAIR imposed requirements contemporaneous
with the installation of controls and construction of a new stack with
a configuration resulting in the physical merging of the two plumes,
requirements that resulted in a net reduction of SO2
emissions from Cardinal. For these reasons, EPA views the merging of
the plumes from Units 1 and 2 to qualify as creditable for
SO2 under 40 CFR 51.100(hh)(2)(ii)(B).

G. Emission Limits and Enforceability

a. Enforceability
    An important prerequisite for approval of an attainment plan is
that the emission limits that provide for attainment be quantifiable,
fully enforceable, replicable, and accountable. See General Preamble at
13567-68. The attainment plan for the Steubenville Area reflects limits
on all significant SO2 emission sources in the Area.
    The limits on Ohio sources are in the form of state regulations,
with the limits in OAC 3745-18-47 and related compliance provisions in
OAC 3745-18-03 and 3745-18-04. The limits for Mingo Junction Energy
Center and for JSW Steel are already an adopted part of these rules, as
submitted on October 13, 2015. Ohio proposed revisions to these rules
on March 25, 2019 to limit the emissions of Cardinal as well. On this
same date, Ohio submitted these proposed revisions, provided a schedule
for adoption of these revisions, requested EPA approval of these
revisions, and requested that EPA conclude that final adoption of the
limit for Cardinal, in conjunction with the other limits already
adopted by Ohio and West Virginia, would assure attainment in this
area. As discussed below, EPA's proposed action today is based on the
understanding that Ohio will adopt these proposed rule revisions in
final form in the near future, at which time this limit would be fully
state enforceable, and then Federally enforceable upon EPA's final
approval of the SIP. As set forth above, if the proposed limits are not
finalized at the State level, then EPA will reconsider this proposed
approval based on the limits that are actually in place on Cardinal.
    The limits for the Mountain State Carbon facility are in Consent
Order CO-SIP-C-2017-9.\9\ WVDEP issued this consent order following a
process with public notice and hearing and submitted the consent order
for incorporation into the West Virginia SIP. EPA finds that the
revised consent order submitted on November 27, 2017 meets the
requirements for Federal enforceability.
---------------------------------------------------------------------------

    \9\ This consent order, submitted on November 27, 2017, reflects
selected revisions as compared to the consent order contained in
West Virginia's April 25, 2016 submittal, to address certain
enforceability issues identified by EPA.
---------------------------------------------------------------------------

    Some of the limits that Ohio and West Virginia's plans rely on are
expressed as longer-term average limits. In particular, some of West
Virginia's limits for Mountain State Carbon are expressed as 24-hour
average limits, and Ohio's proposed limit for Cardinal is expressed as
a 30-day average limit. Therefore, EPA's review of these attainment
plans considered the use of these limits, both with respect to the
general suitability of using such limits for this purpose and with
respect to whether the particular limits included in the plans have
been suitably demonstrated to provide for attainment. The two
subsections that follow address the derivation and suitability of the
longer-term average limits for Mountain State Carbon and Cardinal,
respectively.
b. Longer Term Average Limits for Mountain State Carbon
    Modeled emission rates at Mountain State Carbon represent the set
of hourly critical emission values that (in combination with critical
emission values for other facilities in the area) show compliance with
the standard. Several of Mountain State Carbon's sources that consume
the treated coke oven gas (COG) can experience fluctuating
SO2 emissions due to the variability in the sulfur content
of the coal in the coke ovens and operations at the by-product plant
that can impact sulfur removal efficiencies. To allow for these
fluctuations, Mountain State Carbon requested a 24-hour block limit for
its #1, #2, #3 and # 8 coke batteries, its new combined boilers 6, 7,
9, and 10 stack, and its Acid Plant Tail Gas Scrubber. Appendix D-2 of
West Virginia's April 25, 2016 submittal describes the statistical
analysis that was used to develop the proposed 24-hour average limits.
    Actual historic operating data from the sources at Mountain State
Carbon were used to calculate emission point-specific adjustment
factors that were applied to the modeled critical emission value for
the sources to determine a comparable emission limits with a 24-hour
averaging period. The hourly SO2 emission rates were
calculated using the hourly H2S concentrations in the COG
measured by Mountain State Carbon's existing analyzer and daily average
COG flow rates for the combustion sources, assuming complete
stoichiometric conversion of H2S to SO2 during
combustion of the COG. Table 3 addresses normal operation, showing the
modeled emission rate, the adjustment factor, and the resulting
comparable 24-hour average SO2 emission rate for normal
operation, calculated by applying the adjustment factor to the critical
emissions value for normal operation.

                     Table 3--Equivalent Longer-Term Emission Rates at Mountain State Carbon
----------------------------------------------------------------------------------------------------------------
                                              Modeled 1-hour                                      Equivalent 24-
                                                average SO2                                        hour average
                                               emission rate     Calculated adjustment factor      SO2 emission
                                                  (lb/hr)                                          limit (lb/hr)
----------------------------------------------------------------------------------------------------------------
Battery 1 Combustion........................            22.9  0.935.............................            21.4
Battery 2 Combustion........................            22.9  0.933.............................            21.4
Battery 3 Combustion........................            25.7  0.951.............................            24.5

Battery 8 Combustion........................           122.1  0.945.............................           115.4
Batteries 6-10..............................            90.0  See Note..........................            85.7
Excess COG Flare............................           139.8  0.985.............................           137.7
----------------------------------------------------------------------------------------------------------------
Note: Batteries 6-10 have a merged stack. The calculated adjustment factors are: Battery 6--0.968, Battery 7--
  0.968, Battery 9--0.947, and Battery 10--0.928.

    Table 4 summarizes Mountain State Carbon's modeled emission rates
for the total facility and for fugitive emissions during normal
operations and during the two 10-day by-product plant outage periods in
the model simulation. Facility wide emissions are listed in the table
along with fugitive battery emissions, which were modeled using the
BLP/AERMOD hybrid approach discussed previously. The fugitive coke oven
emissions from Batteries 1, 2, 3 and 8 make up approximately 5% of the
total emission and a smaller percentage during the by-product plant
outages (~1%). Modeled emission rates represent the hourly critical
emission value that shows compliance with the standard.

                              Table 4--Mountain State Carbon Modeled Emission Rates
----------------------------------------------------------------------------------------------------------------
                                              Normal                  By-product plant outage          Total
        Modeled emissions        -------------------------------------------------------------------------------
                                        g/s            lb/hr            g/s            lb/hr            tpy
----------------------------------------------------------------------------------------------------------------
Mountain State Carbon Total.....         * 60.68        * 481.60          151.75        1,204.39        2,229.68
Combined Coke Oven Fugitives....            3.27           25.98            1.68           13.31          110.63
    Battery 1 Fugitives.........            0.41            3.28            0.16            1.24           13.88
    Battery 2 Fugitives.........            0.41            3.28            0.16            1.24           13.88
    Battery 3 Fugitives.........            0.45            3.53            0.16            1.24           14.92
    Battery 8 Fugitives.........            2.00           15.86            1.21            9.59           67.95
----------------------------------------------------------------------------------------------------------------
* In addition to the 53.35 g/s (423.43 lb/hr) shown in Table 3 and the 3.27 g/s (25.98 lb/hr) from fugitive
  emissions shown here, this total also includes 1.98 g/s (15.72 lb/hr) from the Battery 8 pushing scrubber,
  0.76 g/s (6.00 lb/hr) from the acid plant tail gas scrubber, and 1.32 g/s (10.48 lb/hr) from the power
  boilers.

    Based on a review of the state's submittal, EPA believes that the
24-hour average limit for sources at Mountain State Carbon provide a
suitable alternative to establishing a 1-hour average emission limit
for these sources. The State has used a suitable database in an
appropriate manner and has thereby applied an appropriate adjustment,
yielding a set of emission limits that have comparable stringency to
the 1-hour average limits that the state determined would otherwise
have been necessary to provide for attainment. While the 24-hour
average limits allow occasions in which emissions may be higher than
the level that would be allowed with the 1-hour limit, the State's
limits compensate by requiring average emissions to be lower than the
level that would otherwise have been required by a 1-hour average
limit. For reasons described above and explained in more detail in
EPA's April 2014 guidance for SO2 nonattainment plans, EPA
finds that appropriately set longer term average limits provide a
reasonable basis by which nonattainment plans may provide for
attainment. Based on its review of this general information as well as
the particular information in West Virginia's plan, EPA finds that the
24-hour average limit for Mountain State Carbon in combination with
other limitations in Ohio's plan as discussed below, will provide for
attainment of the NAAQS.
c. Longer Term Average Limits for Cardinal
    The emission rate for Cardinal in the joint attainment
demonstration is 6,942.2 pounds per hour. In lieu of a 1-hour limit at
this level, Ohio has proposed a 30-day average limit that is designed
to be comparably stringent. Specifically, Ohio's proposed 30-day
average limit reflects multiplication of 6,942.2 pounds per hour times
an adjustment factor (described below) determined in accordance with
appendix C of EPA's SO2 SIP guidance. The data used to
determine this adjustment factor were the five then most recent years
of hourly Cardinal emissions data reported to EPA's Clean Air Markets
Division, i.e., the data for 2013 to 2017, except that data for a
modest number of hours was not considered because the reported
emissions are substitute data required under 40 CFR 75 in the absence
of direct measurements. Since Cardinal already operates the control
equipment necessary to meet the proposed limit, and has done so
throughout this five-year period, EPA considers these data to provide a
good representation of the variability of SO2 emissions that
Cardinal can be expected to continue to show.
    Given Ohio's intent to adopt the limit in the form of a multi-stack
limit governing the sum of emissions from the three units, the
adjustment factor was derived from an evaluation of statistics for the
hourly and 30-day average sums of emissions from the three units.
Consistent with Ohio's proposed limit, these statistics included only
days in which at least one of the three units was operating and
considered only operating hours. That is, the five years of hourly
emissions data were screened to eliminate a modest number of substitute
data and then screened to eliminate days in which none of the three
units were operating; plant total emissions were determined for each
remaining

hour, 30-operating-day average emissions (not including hours with no
operation) were calculated for the end of each 30-operating-day period,
and the 99th percentile value among the hourly (nonzero) values and the
99th percentile among the 30-operating-day values was computed. The
resulting adjustment factor, reflecting the ratio of these 99th
percentile values, was 70.0 percent. This adjustment factor may be
considered to represent an estimate of the impact of using a 30-day
average limit on total emissions of this facility. EPA finds that this
analysis supports Ohio's conclusion that its proposed limit of 4,858.75
pounds per hour as a 30-day average is comparably stringent to a limit
of 6,942.2 pounds per hour as a 1-hour limit, so that modeling Cardinal
as emitting 6,942.2 pounds per hour is an appropriate means of
assessing whether Ohio's proposed limit of 4,858.75 pounds per hour
will provide for attainment.
    EPA guidance states that limits with averaging times of up to 30
days can in many cases adequately provide for attainment so long as (1)
the limit is established at an adjusted level such that the limit is
comparably stringent to the 1-hour limit that is shown to provide for
attainment (the latter reflecting the ``critical emission level''), and
(2) emissions are sufficiently constrained that occasions of emissions
above the critical emission value will be limited in frequency and
magnitude. The dataset used in assessing an appropriate adjustment
factor, reflecting the last five calendar years, is also a suitable
dataset for assessing the likely frequency and magnitude of emissions
above the critical emission value. During these five years, from 2013
to 2017, total emissions from Cardinal were always below 4,858.75
pounds per hour on a 30-day average basis, and hourly emissions
exceeded 6,942.2 pounds per hour less than 0.05 percent of the time. A
spreadsheet containing these data and the calculations supporting the
above adjustment factor are included in the dockets for this rulemaking
on Ohio's and West Virginia's submittals.

H. Background Concentration

    The joint Ohio/West Virginia attainment demonstration used a
uniform background concentration of 5.0 ppb (which AERMOD translates to
13.08 micrograms per cubic meter ([mu]g/m\3\)). While Ohio's and West
Virginia's original attainment demonstrations used a background value
of 8.1 ppb (21.17 [mu]g/m\3\), based on 2007 to 2009 monitor values
within the Steubenville nonattainment area, the updated analysis that
Ohio provided uses a 2016 to 2018 design value from a regional monitor
located approximately 21 kilometers south of the Steubenville
nonattainment area along the Ohio River, namely site number 39-013-0006
in Belmont County, Ohio. As Ohio has shown, the complexities of terrain
and meteorology along the Ohio River in the Steubenville area make it
difficult to distinguish those values monitored in the Steubenville
Area that are and are not influenced by modeled Steubenville Area
sources, and so it is difficult to use the Steubenville Area monitoring
data to determine a concentration that truly reflects a background
concentration that would exist in absence of the modeled Steubenville
area sources. Thus, the Belmont County monitor likely provides the best
basis for determining an appropriate background concentration, and EPA
believes that the 5.0 ppb value is an appropriate representation of
background concentrations in the Area without the influence of the four
modeled sources included in West Virginia's model demonstration.

I. Assessment of Plant-Wide Emission Limit for Cardinal

    The limit that Ohio has proposed for Cardinal is a limit on total
SO2 emissions from the plant. Therefore, an assessment of
whether this limit provides for attainment must evaluate whether
attainment is predicted under a full range of distributions of
emissions allowed under this limit. Particularly given the 1.6
kilometer distance between the stack for Units 1 and 2 and the stack
for Unit 3, the endpoints of the range of allowable distributions of
emissions are (1) to have all emissions arising from the stack for
Units 1 and 2 and (2) to have all emissions arising from the stack for
Unit 3.
    The joint attainment demonstration includes this range of
simulations. In one simulation, 6,942.2 pounds per hour were emitted
from the stack for Units 1 and 2. In a second simulation, 6,942.2
pounds per hour were emitted from the stack for Unit 3. (Since Unit 1
and Unit 2 are essentially identical units with a single stack and
essentially identical other stack parameters, it was not necessary to
distinguish whether emissions arose from Unit 1 or from Unit 2.) A
third simulation used an intermediate, more typical mix of emissions,
again adding up to 6,942.2 pounds per hour. Specifically, in this run,
Units 1 and 2 together emitted 5,484 pounds per hour and Unit 3 emitted
1,458 pounds per hour. EPA believes that these three runs address the
range of air quality that can result from the range of possible
distributions of emissions at Cardinal within the total plant emissions
limit proposed by Ohio, including the worst case distribution of
allowable emissions.

J. Summary of Results

    The joint modeling demonstration shows that peak model
concentrations occur in the northern Ohio portion of the Steubenville
Area, near Mountain State Carbon, with substantial contributions from
both Mountain State Carbon and Cardinal. The modeling shows that the
maximum 1-hour SO2 concentration is 192.1 microgram per
cubic meter (ug/m\3\) (corresponding to 73.4 parts per billion), which
meets the 1-hour SO2 NAAQS level of 196.4 ug/m\3\. The
maximum modeled concentration includes a fixed representative
background concentration and demonstrates that the limits used in the
modeling achieve compliance with the 1-hour SO2 NAAQS. This
modeling demonstration follows current guidance included in appendix W
to 40 CFR part 51--Guideline on Air Quality Models (2017). EPA finds
that the modeling demonstration properly characterized source limits,
local meteorological data, background concentrations and provided an
adequate model receptor grid to capture maximum modeled concentrations.
Final model results are below the current 1-hour SO2 NAAQS
and demonstrate that the modeled emission limits will allow the
Steubenville Area to continue to comply with the standard.

V. Review of Other Plan Requirements

A. Emissions Inventory

    The emissions inventory and source emission rate data for an area
serve as the foundation for air quality modeling and other analyses
that enable states to: (1) Estimate the degree to which different
sources within a nonattainment area contribute to violations within the
affected area; and (2) assess the expected improvement in air quality
within the nonattainment area due to the adoption and implementation of
control measures. As noted above, the state must develop and submit to
EPA a comprehensive, accurate and current inventory of actual emissions
from all sources of SO2 emissions in each nonattainment
area, as well as any sources located outside the nonattainment area
which may affect attainment in the area. See CAA section 172(c)(3).
    For the base year inventory of actual emissions, a ``comprehensive,
accurate and current'' inventory can be represented by a year that
contributed to

the three-year design value used for the original nonattainment
designation. The 2014 SO2 Nonattainment Guidance notes that
the base year inventory should include all sources of SO2 in
the nonattainment area as well as any sources located outside the
nonattainment area which may affect attainment in the area.
Ohio Emissions Inventory
    In Ohio, major point sources in all counties are required to submit
air emissions information annually, in accordance with EPA's
Consolidated Emissions Reporting Rule (CERR). OEPA prepares a new
periodic inventory for all SO2 emission sectors every three
years. The 2011 periodic inventory has been identified as one of the
preferred databases for SIP development and coincides with
nonattainment air quality in the Steubenville Area, thus the 2011
inventory was used as the base year for OEPA's submittal to fulfill the
base-year emissions inventory requirements under the 2010
SO2 standard.
    Because October 4, 2018 was the attainment date for the 2010
SO2 NAAQS, 2018 was selected as the future year to fulfill
the projected year emissions inventory requirements under the 2010
SO2 NAAQS. Emissions from 2011 for electric generating units
(EGU) and non-EGUs were based on annual data reported by these sources
in accordance with the CERR. Projections for area (non-point), on-road
mobile (on-road), marine/air/rail (MAR), and non-road mobile (non-road)
sources sectors were developed using 2011 county level emissions data
downloaded from the 2011 NEI version 1-based Emissions Modeling
Platform (Version 6). For townships, county level emissions for area,
MAR and non-road were adjusted using population ratios while county
level emissions for on-road were adjusted using vehicle miles traveled
(VMT) ratios. The resulting inventory is summarized in Table 5.

Table 5--2011 Base Year and 2018 Projection Year SO2 Emissions Inventory
      for the Ohio Portion of the Steubenville, Ohio-West Virginia
                   Nonattainment Area in Tons Per Year
                                  [tpy]
------------------------------------------------------------------------
                                                               2018
                                            2011  base       projected
                                            year  (tpy)     year  (tpy)
------------------------------------------------------------------------
WarrenTownship:
    EGU Point...........................            0.00            0.00
    Non-EGU.............................            0.20            0.20
    Non-road............................            0.03            0.01
    MAR.................................            0.57            0.07
    Area................................            5.86            5.86
    On-road.............................            0.65            0.25
                                         -------------------------------
        Total...........................            7.31            6.39
------------------------------------------------------------------------
Cross Creek Township:
    EGU Point...........................            0.00            0.00
    Non-EGU.............................            0.00            0.00
    Non-road............................            0.06            0.03
    MAR.................................            1.13            0.13
    Area................................           11.58           11.58
    On-road.............................            0.93            0.36
                                         -------------------------------
        Total...........................            13.7            12.1
------------------------------------------------------------------------
City of Steubenville:
    EGU Point...........................            0.00            0.00
    Non-EGU.............................            0.00            0.00
    Non-road............................            0.14            0.06
    MAR.................................            2.54            0.30
    Area................................           26.07           26.07
    On-road.............................            1.22            0.48
                                         -------------------------------
        Total...........................           29.97           26.91
------------------------------------------------------------------------
Wells Township:
    EGU Point...........................       25,122.43       10,681.56
    Non-EGU.............................            0.00            0.00
    Non-road............................            0.02            0.01
    MAR.................................            0.38            0.04
    Area................................            3.92            3.92
    On-road.............................            0.56            0.23
                                         -------------------------------
        Total...........................       25,127.31       10,685.76
------------------------------------------------------------------------
Steubenville Township:
    EGU Point...........................            0.00            0.00
    Non-EGU.............................          223.24          188.29
    Non-road............................            0.03            0.01
    MAR.................................            0.58            0.07
    Area................................            5.99            5.99

    On-road.............................            1.26            0.50
                                         -------------------------------
        Total...........................          231.10          194.86
------------------------------------------------------------------------
Ohio Portion of Steubenville Area:
    EGU Point...........................       25,122.43       10,685.76
    Non-EGU.............................          223.44          188.49
    Non-road............................            0.28            0.12
    MAR.................................            5.20            0.61
    Area................................           53.42           53.42
    On-road.............................            4.62            1.81
                                         -------------------------------
        Total...........................       25,409.39       10,930.22
------------------------------------------------------------------------

West Virginia Emissions Inventory
    West Virginia submitted a 2011 base year inventory for all source
categories in the West Virginia portion of the Area. West Virginia used
emissions from EPA's 2011 NEI Version 2 for the 2011 base year
inventory. Since designation of the Area as nonattainment was based on
monitored data from the 2010-2012 period, EPA finds the election of
2011 as a base year to be appropriate, as 2011 data is representative
of the operations of the facilities that contributed to the monitored
violations leading to the Area's designation. EPA reviewed the results,
procedures, and methodologies for the base year and found them to be
acceptable. Actual emissions from all the sources of SO2 in
the West Virginia portion of the area were reviewed and compiled for
the base year emissions inventory requirement. The primary
SO2-emitting point source located within the West Virginia
portion of the area is Mountain State Carbon.
    For the base year emissions inventory, WVDEP used emissions from
EPA's 2011 NEI, Version 2. Table 1 shows the level of emissions,
expressed in tons per year (tpy), in the West Virginia portion of the
Steubenville Area for the 2011 base year and 2018 projection year
inventories.
    EPA has evaluated West Virginia's 2011 base year emissions
inventory for the West Virginia portion of the Area and has made the
determination that this inventory was developed consistent with section
172(c)(3) and EPA's guidance. Therefore, EPA is proposing to approve
West Virginia's 2011 base year emissions inventory for the Area.
    The attainment demonstration also provides for a projected
attainment year inventory that includes estimated emissions for all
emission sources of SO2 which are determined to impact the
nonattainment area for the year in which the area is expected to attain
the NAAQS. West Virginia provided a 2018 projected emissions inventory
for all known sources included in the 2011 base year inventory.
SO2 emissions are expected to decrease by approximately 290
tons, or approximately 33%, by 2018 from the 2011 base year. EPA finds
that the use of the 2018 inventory is acceptable for use in the
modeling analysis submitted by West Virginia for this Area.

Table 6--2011 Base Year and 2018 Projection Year SO2 Emissions Inventory
  for the West Virginia Portion of the Steubenville, Ohio-West Virginia
                           Nonattainment Area
------------------------------------------------------------------------
                                                               2018
        Emission source category            2011  base      projection
                                            year  (tpy)     year  (tpy)
------------------------------------------------------------------------
Point...................................             730             428
Non-Point (Area)........................             154             168
Non-road (includes Marine, Air, Rail                   2               2
 (MAR)).................................
On-road.................................               2               0
                                         -------------------------------
    Total...............................             888             598
------------------------------------------------------------------------

B. RACM/RACT

Ohio
    OEPA's October 13, 2015 Attainment SIP submittal identified three
sources in the Ohio portion of the Steubenville Area subject to RACM/
RACT, consisting of Cardinal, JSW Steel and Mingo Junction Energy
Center. As Cardinal is already equipped with a flue gas desulfurization
unit, OEPA's submittal did not identify any further reductions required
at this facility. However, on March 25, 2019, OEPA submitted proposed
revisions to its OAC Rule 3745-18-47 that, if finalized, will impose
more stringent limits on Cardinal that will assure continued, efficient
operation of this control.
    EPA's analysis of the proposed limit (discussed previously in
section IV.J of this preamble) shows that the more stringent limits,
along with the other measures in the area, will achieve attainment in
the Area for the 2010 1-hour SO2 NAAQS. As noted previously,
the proposal establishes an SO2 emission limit of 4,858.75
pounds per

hour for Cardinal, effective upon adoption of the final rule.
    Mingo Junction Energy Center is currently not operational but is
allowed to be partially operated in the future, subject to stringent
limits. For JSW Steel, OEPA considered potential SO2
emission controls that included wet scrubbing, spray dryer absorption
and dry sorbent injection for the electric arc furnace (EAF) but
determined that these emission control technologies were not
technically feasible for EAF operations. In addition, the RACT/BACT/
LAER Clearing House (RBLC) does not identify any EAF that employs add-
on SO2 emission controls. The current recommended reasonably
available control technology (RACT) for controlling SO2
emissions from the EAF is a scrap management program, which is
currently a requirement of the facility's permit. In addition, 40 CFR,
Subpart YYYYY (Electric Arc Steelmaking Facilities) requires a facility
subject to this subpart to employ an approved scrap management program
to aid in reducing overall emissions. Therefore, EPA finds that the EAF
at JSW Steel, upon resumption of operations, would be subject to limits
that satisfy current RACT/RACM requirements.
    In addition to the EAF, this facility also has a Ladle
Metallurgical Furnace (LMF) to refine molten steel from the EAF, and
three reheat furnaces. OEPA determined that with current permitted
SO2 rates at the LMF and a lower emission rate at the three
reheat furnaces, additional RACT/RACM controls were not needed as a
part of the control strategy for this Area.The Mingo Junction Energy
Center is comprised of four 180 MMBtu/hr boilers that can burn a
combination of natural gas, blast furnace gas or COG, and two of the
units can also burn desulfurized coke oven gas. The consent order
between West Virginia and Mountain State Carbon prohibits Mountain
State Carbon from providing COG or desulfurized COG to the Mingo
Junction Energy Center as of January 2017. Because the blast furnace at
JSW Steel was permanently shut down and dismantled, this gas will also
not be supplied. Therefore, it is highly likely the only form of fuel
that may be burned in the future is natural gas.
    Also, to meet Best Available Control Technology (BACT)
requirements, a water injection system was installed on these four
units. Their current permitted limits allow for 45.7 lbs/hr
SO2, as a 3-hour rolling average, when burning natural gas
or natural gas/blast furnace gas blend; or 49.5 lbs/hr SO2,
as a 3-hour rolling average, when burning only COG, a blend of natural
gas and COG, or a blend of natural gas, COG, and blast furnace gas. As
part of the control strategy for this Area, emissions from each of the
four units will be limited to 20.34 pounds per hour of SO2.
Thus, EPA finds that additional RACT/RACM to control SO2
emissions is not necessary for these sources.
West Virginia
    West Virginia's plan for attaining the 1-hour SO2 NAAQS
in the West Virginia portion of the SO2 nonattainment area
is based on measures at Mountain State Carbon. For coke oven batteries,
SO2 reduction can be accomplished by two general
methodologies: Pre-combustion desulfurization and restrictions on coal
sulfur content. The Mountain State Carbon plant is currently controlled
with a pre-combustion desulfurization unit that reduces the sulfur
content of COG before it is combusted in the coke ovens. Based on its
analysis, West Virginia proposed that the controls already in place,
with a hydrogen sulfide (H2S) limit of 50 grains per dry
standard cubic feet (dscf), constitutes RACT, and established
SO2 emission limits on the combustion sources during normal
operation of the desulfurization unit to reflect the lowest achievable
limits given the technology. However, the desulfurization unit is
required to be shut down for up to 20 days a year for maintenance
purposes, during which time the existing limits cannot be met without
additional operational changes at the plant.
    During the maintenance outages, West Virginia proposes its control
strategy for Mountain State Carbon as a limit on the sulfur content of
the coal to 1.25 percent and restricting the number of ovens in
operation to 63 ovens per day on Battery #8, or no more than a combined
51 ovens per day on Battery #8 and no more than 72 ovens per day total
on Batteries #1, #2, and #3. Additionally, Mountain State Carbon was
required to physically disconnect the COG pipeline leading to the Mingo
Junction Energy Center, was prohibited from providing COG to any entity
outside of the Mountain State Carbon plant and was required to divert
the #9 and #10 Boiler Stack into the combined #6 and #7 Boiler Stack.
These requirements are part of a West Virginia consent order with
Mountain State Carbon that West Virginia submitted with its April 25,
2016 attainment SIP, and revised in a supplemental submission on
November 27, 2017, for incorporation into the West Virginia SIP. The
consent order required compliance with these measures by January 1,
2017.
    West Virginia and Ohio have determined that these measures,
including the limits on Cardinal that Ohio is concurrently proposing at
the State level, will suffice to provide for attainment in the
Steubenville Area. EPA concurs and proposes to find that the measures
submitted by Ohio and West Virginia, along with the limits on Cardinal
proposed in Ohio rule 3745-18-47 to be submitted as a SIP revision
after their adoption at the State level, satisfy the requirement in
section 172(c)(1) to adopt and submit all RACM as needed to attain the
standard as expeditiously as practicable.

C. New Source Review (NSR)

    Section 172(c)(5) of the CAA requires that an attainment plan
require permits for the construction and operation of new or modified
major stationary sources in a nonattainment area.
    Ohio has a longstanding and fully implemented NSR program that
meets the nonattainment NSR permitting requirements for the entire
state of Ohio. This is addressed in OAC Chapter 3745-31. The Chapter
includes provisions for the PSD permitting program in OAC rules 3745-
31-01 to 3745-31-20 and the nonattainment NSR program in OAC rules
3745-31-21 to 3745-31-27. Ohio's NNSR program was conditionally
approved on October 10, 2001 (66 FR 51570) and was approved by EPA on
January 22, 2003 (68 FR 2909). The latest revisions to OAC Chapter
3745-31 were approved into Ohio's SIP on February 20, 2013 (78 FR
11748).
    EPA has approved West Virginia's nonattainment NSR rules at 45CSR13
``Permits for Construction, Modification, or Relocation of Stationary
Sources or Air Pollutants, and Procedures for Registration and
Evaluation'' and 45CSR19 ``Requirements for Pre-Construction Review,
Determination of Emission Offsets for Proposed New or Modified
Stationary Sources of Air Pollutants and Bubble Concept for Intrasource
Pollutants,'' with the most recent revisions on August 20, 2014 (79 FR
42212) and on May 26, 2015 (80 FR 29973), respectively. These rules
provide for appropriate new source review for SO2 sources
undergoing construction or major modification in the West Virginia
portion of the Area without need for modification of the approved
rules.
    As both Ohio and West Virginia have appropriate NSR for
SO2 sources undergoing construction or major modification,
EPA concludes that the NSR requirement has already been met for the
Steubenville Area.

D. Reasonable Further Progress (RFP)

    Section 172(c)(2) of the CAA requires that an attainment plan
include a

demonstration that shows reasonable further progress (i.e., RFP) for
meeting air quality standards will be achieved through generally linear
incremental improvement in air quality. Section 171(1) of the CAA
defines RFP as such annual incremental reductions in emissions of the
relevant air pollutant as are required by this part (part D) or may
reasonably be required by EPA for the purpose of ensuring attainment of
the applicable NAAQS by the applicable attainment date. As stated
originally in the 1994 SO2 Guidelines Document and repeated
in the April 2014 guidance, EPA continues to believe that this
definition is most appropriate for pollutants that are emitted from
numerous and diverse sources, where the relationship between particular
sources and ambient air quality are not directly quantified. In such
cases, emissions reductions may be required from various types and
locations of sources. The relationship between SO2 and
sources is much more defined, and usually there is a single step
between pre-control nonattainment and post-control attainment.
Therefore, EPA interpreted RFP for SO2 as adherence to an
ambitious compliance schedule in both the 1994 SO2 Guideline
Document and the April 2014 guidance. The control measures for Mountain
State Carbon included in West Virginia's attainment plan submittals
(which are contained in Consent Order CO-SIP-C-2017-9 between West
Virginia and Mountain State Carbon) and Ohio's proposed limits for
Cardinal in Ohio rule 3745-18-47, both discussed previously, achieve
attainment of the 2010 SO2 NAAQS for the Steubenville Area.
The West Virginia plan required that affected sources implement
appropriate control measures as expeditiously as practicable in order
to ensure attainment of the standard by the applicable attainment date
(Mountain State Carbon was required under the consent order to
implement the control measures starting on January 1, 2017). Proposed
Ohio rule 3745-18-47 requires implementation of SO2 emission
limits for Cardinal upon the Ohio's adoption of the final rule,
although Cardinal in fact has been meeting these limits for the last 6
years. Ohio and West Virginia concluded that their respective plans
provide for RFP in accordance with the approach to RFP described in
EPA's guidance. EPA concurs and proposes to find that the plans, along
with the revised limits for Cardinal, provide for RFP in the
Steubenville Area.

E. Contingency Measures

    As noted above, EPA guidance describes special features of
SO2 planning that influence the suitability of alternative
means of addressing the requirement in section 172(c)(9) for
contingency measures for SO2, such that in particular an
appropriate means of satisfying this requirement is for the state to
have a comprehensive enforcement program that identifies sources of
violations of the SO2 NAAQS and to undertake an aggressive
follow-up for compliance and enforcement. OEPA's plan states that it
has an active enforcement program to address violations of the
SO2 NAAQS. OEPA will continue to operate a comprehensive
program to identify sources of violations of the SO2 NAAQS
and to undertake an aggressive follow-up for compliance and
enforcement, including expedited procedures for establishing
enforceable consent agreements pending the adoption of revised SIPs.
West Virginia's plan provides for satisfying the contingency measure
requirement in this manner as well. West Virginia's plan provides for
thorough compliance and enforcement inspections, monthly parametric
monitoring data review, and quarterly record reviews along with
cyclical stack testing for an aggressive compliance assurance plan.
Non-compliance may lead to an immediate notice of violation and
drafting of an enforceable consent order.
    With the special features of SO2, EPA concurs that the
contingency measures described by both Ohio and West Virginia meet the
EPA guidance, and EPA proposes to approve both the Ohio and West
Virginia plans for meeting the contingency measure requirement in this
manner.

VI. EPA's Proposed Action

    EPA is proposing to approve two SIP revision submittals, one
submitted by the State of Ohio on April 1, 2015, which Ohio
supplemented on October 13, 2015 and March 25, 2019, and the other
submitted by the State of West Virginia on April 25, 2016, which West
Virginia supplemented on November 27, 2017, with a clarification letter
submitted on May 1, 2019. This proposed approval is contingent on Ohio
adopting in final form the limit it submitted in proposed form on March
25, 2019. The submittals provide Ohio's and West Virginia's plans for
attaining the 2010 1-hour SO2 NAAQS and how they are meeting
other nonattainment area planning requirements. Specifically, EPA is
proposing to approve the emissions limitations and control measures,
the base year emissions inventory, NNSR program, and contingency
measures submitted by Ohio and West Virginia for the Steubenville Area.
In the West Virginia SIP, EPA is proposing to approve the emission
limits and other measures for Mountain State Carbon contained in a
consent order submitted by West Virginia, including operational
restrictions and sulfur content limits during the periods in which the
desulfurization unit for Mountain State Carbon is shut down for
maintenance purposes, and their associated compliance requirements. In
the Ohio SIP, EPA is proposing to approve Ohio Administrative Code
(OAC) Rule 3745-18-03, 3745-18-04, and 3745-18-47, provided Ohio
completes adoption of these rules as proposed or in substantially
similar form. EPA is also proposing approval of the Ohio and West
Virginia attainment demonstrations, RFP, and RACT/RACM, provided that
Ohio adopts and submits in final form its proposed SO2
emission limits for Cardinal.
    EPA is proposing approval of the attainment plans, RFP, and RACM/
RACT for each State concurrently with Ohio's rulemaking process to
establish revised enforceable limits on Cardinal. EPA plans no final
action until Ohio finalizes and submits the proposed rule.
    On May 1, 2019, WVDEP provided a letter to EPA stating that WVDEP
concurs with the attainment demonstration submitted by Ohio,
demonstrating that the area attains the standard notwithstanding the
expected adoption of higher Cardinal emission limits than accounted for
in WVDEP's initial submittal. EPA is proposing to finalize this action
in conjunction with approval of the Ohio SIP submittal for revised OAC
Rule 3745-18-03, pertinent sections of 3745-18-04,\10\ and 3745-18-47.
If Ohio fails to adopt final limits for Cardinal or adopts final limits
that differ significantly from the proposed limits, EPA may withdraw
this proposed action or may re-propose based on Ohio's final adopted
rule before EPA takes final action.
---------------------------------------------------------------------------

    \10\ EPA has historically not taken action on several paragraphs
of this rule as listed in section VII of this action. These
paragraphs are not pertinent to today's action, and EPA is
continuing to take no action on these paragraphs.
---------------------------------------------------------------------------

    The TSD for this proposed action is available on-line at
www.regulations.gov, Docket No. EPA-R03-OAR-2019-0044 and Docket No.
EPA-R05-OAR-2015-0699. The TSD provides additional explanation of EPA's
analyses supporting this proposal.

    EPA is taking public comments for 30 days following the publication
of this proposed action in the Federal Register. We will take all
comments into consideration in our final action.

VII. Incorporation by Reference

    In this document, EPA is proposing to include in a final EPA action
regulatory text that includes incorporation by reference. In accordance
with requirements of 1 CFR 51.5, EPA is proposing to incorporate by
reference the consent order between West Virginia and Mountain State
Carbon identified as CO-SIP-C-2017-9, effective September 29, 2017, and
Ohio rules OAC 3745-18-03, 3745-18-04 (except for paragraphs (D)(2),
(D)(3), (D)(5), (D)(6), (D)(9)(c), (E)(2), (E)(3), and (E)(4), and
3745-18-47. EPA has made, and will continue to make, these materials
generally available through http://www.regulations.gov and at the EPA
Regional Offices (please contact the respective EPA Region 3 or 5
person identified in the For Further Information Contact section of
this proposed rulemaking for more information).

VIII. Statutory and Executive Order Reviews

    Under the CAA, the Administrator is required to approve a SIP
submission that complies with the provisions of the CAA 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
proposed action merely approves state law as meeting Federal
requirements and does not impose additional requirements beyond those
imposed by state law. For that reason, this proposed action:
     Is not a ``significant regulatory action'' subject to
review by the Office of Management and Budget under Executive Order
12866 (58 FR 51735, October 4, 1993) and 13563 (76 FR 3821, January 21,
2011);
     Is not an Executive Order 13771 (82 FR 9339, February 2,
2017) regulatory action because SIP approvals are exempted under
Executive Order 12866;
     Does not impose an information collection burden under the
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
     Is certified as not having a significant economic impact
on a substantial number of small entities under the Regulatory
Flexibility Act (5 U.S.C. 601 et seq.);
     Does not contain any unfunded mandate or significantly or
uniquely affect small governments, as described in the Unfunded
Mandates Reform Act of 1995 (Pub. L. 104-4);
     Does not have Federalism implications as specified in
Executive Order 13132 (64 FR 43255, August 10, 1999);
     Is not an economically significant regulatory action based
on health or safety risks subject to Executive Order 13045 (62 FR
19885, April 23, 1997);
     Is not a significant regulatory action subject to
Executive Order 13211 (66 FR 28355, May 22, 2001);
     Is not subject to requirements of Section 12(d) of the
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272
note) because application of those requirements would be inconsistent
with the CAA; and
     Does not provide EPA with the discretionary authority to
address, as appropriate, disproportionate human health or environmental
effects, using practicable and legally permissible methods, under
Executive Order 12898 (59 FR 7629, February 16, 1994).
    In addition, the proposed approval of the SO2 attainment
plan SIPs submitted by Ohio and West Virginia is not approved to apply
on any Indian reservation land or in any other area where EPA or an
Indian tribe has demonstrated that a tribe has jurisdiction. In those
areas of Indian country, the rule does not have tribal implications and
will not impose substantial direct costs on tribal governments or
preempt tribal law as specified by Executive Order 13175 (65 FR 67249,
November 9, 2000).

List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Incorporation by
Reference, Reporting and recordkeeping requirements, Sulfur oxides.

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

    Dated: June 4, 2019.
Cosmo Servidio,
Regional Administrator, Region III.
    Dated: June 11, 2019.
Cathy Stepp,
Regional Administrator, Region V.
[FR Doc. 2019-13294 Filed 6-21-19; 8:45 am]
 BILLING CODE 6560-50-P