[Federal Register Volume 84, Number 121 (Monday, June 24, 2019)]
[Proposed Rules]
[Pages 29456-29471]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[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 protected] at EPA Region III or to 
[email protected] 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, (215) 814-2308, 
[email protected]. 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, (312) 886-6067, [email protected].

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

[[Page 29457]]

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

[[Page 29458]]

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

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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

[[Page 29460]]

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 2.6.1.2 of the August 23, 2010 clarification memo on 
``Applicability of appendix W Modeling Guidance for the 1-hr 
SO2 National Ambient Air Quality Standard'' (U.S. EPA, 
2010a).

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

[[Page 29461]]

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-

[[Page 29462]]

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

[[Page 29463]]

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

[[Page 29464]]

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

[[Page 29465]]

 
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

[[Page 29466]]

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

[[Page 29467]]

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

[[Page 29468]]

 
    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

[[Page 29469]]

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

[[Page 29470]]

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.

[[Page 29471]]

    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