Document ID: EPA-R05-OAR-2015-0699-0025
Agency: epa
Document Type: Proposed Rule
Title: Proposed approval of the Ohio 2010 1-Hour SO2 NAAQS Nonattainment SIP for Muskingum River
Posted Date: 2020-09-29T04:00Z

[Federal Register Volume 85, Number 189 (Tuesday, September 29, 2020)]
[Proposed Rules]
[Pages 60933-60942]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-21560]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R05-OAR-2015-0699; FRL-10015-10-Region 5]

Air Plan Approval; Ohio; Attainment Plan for the Muskingum River 
SO2 Nonattainment Area

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to 
approve a revision to the Ohio State Implementation Plan (SIP) 
submitted on April 3, 2015 and October 13, 2015, and supplemented on 
June 23, 2020, by the Ohio Environmental Protection Agency (Ohio EPA), 
consisting of its plan for attaining the 1-hour sulfur dioxide 
(SO2) primary national ambient air quality standard (NAAQS) 
for the Muskingum River, Ohio SO2 nonattainment area. This 
plan (herein called a ``nonattainment plan'') includes Ohio's 
attainment demonstration and other elements required under the Clean 
Air Act (CAA). In addition to an attainment demonstration, the plan 
addresses the requirements for meeting reasonable further progress 
(RFP) toward attainment of the NAAQS, reasonably available control 
measures (RACM) and reasonably available control technology (RACT), 
enforceable emission limitations and control measures, base-year and 
projection-year emission inventories, and contingency measures. EPA 
proposes to conclude that Ohio has appropriately demonstrated that the 
plan provisions provide for attainment of the 2010 1-hour primary 
SO2 NAAQS in the Muskingum River, Ohio nonattainment area 
and that the plan meets the other applicable requirements under the 
CAA.

DATES: Comments must be received on or before October 29, 2020.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R05-
OAR-2015-0699 at http://www.regulations.gov, or via email to 
aburano.douglas@epa.gov. For comments submitted at Regulations.gov, 
follow the online instructions for submitting comments. Once submitted,

[[Page 60934]]

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: Gina Harrison, Environmental 
Scientist, Attainment Planning and Maintenance Section, Air Programs 
Branch (AR-18J), Environmental Protection Agency, Region 5, 77 West 
Jackson Boulevard, Chicago, Illinois 60604, (312) 353-6956, 
harrison.gina@epa.gov. The EPA Region 5 office is open from 8:30 a.m. 
to 4:30 p.m., Monday through Friday, excluding Federal holidays and 
facility closures due to COVID-19.

SUPPLEMENTARY INFORMATION: Throughout this document, whenever ``we,'' 
``us,'' or ''our'' is used, we mean EPA. This state submittal addressed 
Ohio's Lake County, Muskingum River, and Steubenville OH-WV 
SO2 nonattainment areas. EPA is proposing action on only the 
Muskingum River portion of Ohio's submittal at this time; the Lake 
County and Steubenville portions were addressed in prior rulemaking 
actions. The following outline is provided to aid in locating 
information regarding EPA's proposed action on Ohio's Muskingum River 
SO2 nonattainment plan.

Table of Contents

I. Why was Ohio required to submit an SO2 plan for the 
Muskingum River area?
II. Requirements for SO2 Nonattainment Area Plans
III. Attainment Demonstration and Longer Term Averaging
IV. Review of Modeled Attainment Plan
    A. Model Selection and General Model Inputs
    B. Meteorological Data
    C. Modeled Emissions Data
    D. Emission Limits
    E. Background Concentrations
    F. Summary of Results
V. Review of Other Plan Requirements
    A. Emissions Inventory
    B. RACM/RACT and Emissions Limitations and Control Measures
    C. New Source Review (NSR)
    D. RFP
    E. Contingency Measures
VI. EPA's Proposed Action
VII. Incorporation by Reference
VIII. Statutory and Executive Order Reviews

I. Why was Ohio required to submit an SO2 plan for the 
Muskingum River 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 the 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). The 3-year average of the annual 99th percentile of daily 
maximum 1-hour concentrations is called the air quality monitor's 
SO2 ``design value.'' For the 3-year period 2009-2011, the 
design value at the Muskingum River SO2 monitor in Morgan 
County, Ohio (39-115-004) was 180 ppb, which is a violation of the 
SO2 NAAQS. On August 5, 2013, EPA designated a first set of 
29 areas of the country as nonattainment for the 2010 SO2 
NAAQS, including the Muskingum River nonattainment area. Muskingum 
River's SO2 designation was based upon the monitored design 
value at this location for this three-year period. The Muskingum River 
nonattainment area is defined to include part of Morgan County (Center 
Township) and part of Washington County (Waterford Township). See 78 FR 
47191, codified at 40 CFR part 81, subpart C. This area designation was 
effective on October 4, 2013.
    Section 191(a) of the CAA directs states to submit SIPs for areas 
designated as nonattainment for the SO2 NAAQS to EPA within 
18 months of the effective date of the designation; in this case, by no 
later than April 4, 2015. These SIPs are required by CAA section 192(a) 
to demonstrate that their respective areas will attain the NAAQS as 
expeditiously as practicable, but no later than 5 years from the 
effective date of designation. The SO2 attainment deadline 
for Muskingum River was October 4, 2018. EPA is proposing to approve 
this plan in accordance with a court-ordered deadline of October 30, 
2020 for final action on the SIP.\1\
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    \1\ In a November 26, 2019, order issued in Center for 
Biological Diversity, et al. v. Wheeler, No. 4:18-cv-03544 (N.D. 
Cal.), the court ordered EPA to take action on certain aspects of 
Ohio's SIP submittal, including the attainment demonstration for the 
Muskingum River area, by October 30, 2020.
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    In response to the SO2 nonattainment plan submittal 
requirement, Ohio submitted a nonattainment plan for the Muskingum 
River nonattainment area on April 3, 2015,\2\ submitted revisions on 
October 13, 2015, and submitted a supplement specific to the Muskingum 
River area on June 23, 2020. The June 23, 2020 supplement contains the 
core features of the attainment plan. The remainder of this document 
describes the requirements that such plans must meet in order to obtain 
EPA approval, provides a review of the state's plan with respect to 
these requirements, and describes EPA's proposed action on the plan.
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    \2\ For a number of areas, EPA published a final rule on March 
18, 2016 that the pertinent states had failed to submit the required 
SO2 nonattainment plan by this submittal deadline. See 81 
FR 14736. However, because Ohio EPA had submitted its SO2 
nonattainment plan before that date, EPA did not make such a finding 
with respect to Ohio's submittal for Muskingum River.
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II. Requirements for SO2 Nonattainment Area Plans

    Nonattainment SIPs must meet the applicable requirements of the 
CAA, and specifically CAA sections 110, 172, 191 and 192. EPA's 
regulations governing nonattainment 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 13545-13549, 13567-13568. On April 23, 2014, 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,'' available at 
https://www.epa.gov/sites/production/files/2016-06/documents/20140423guidance_nonattainment_sip.pdf. In this guidance, referred to 
in this document as the 2014 SO2 guidance, EPA described the 
statutory requirements for a complete nonattainment area SIP,

[[Page 60935]]

which includes an accurate emissions inventory of current emissions for 
all sources of SO2 within the nonattainment area; an 
attainment demonstration; demonstration of RFP; implementation of RACM/
RACT; enforceable emission limitations and control measures; NSR; and 
adequate contingency measures for the affected area.
    In order for EPA to fully approve a SIP as meeting the requirements 
of CAA sections 110, 172 and 191-192, and EPA's regulations at 40 CFR 
part 51, the SIP for the affected area needs to demonstrate to EPA's 
satisfaction that each of the aforementioned requirements have been 
met. Under CAA sections 110(l) and 193, EPA may not approve a SIP that 
would interfere with any applicable requirement concerning NAAQS 
attainment and RFP, or any other applicable requirement, and no 
requirement in effect (or required to be adopted by an order, 
settlement, agreement, or plan in effect before November 15, 1990) in 
any area which is a nonattainment area for any air pollutant, may be 
modified in any manner unless it ensures 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. The regulations at 40 CFR part 51, subpart G 
further delineate the control strategy requirements that SIPs must 
meet. EPA has long required that all SIPs and control strategies 
reflect four fundamental principles of quantification, enforceability, 
replicability, and accountability. See General Preamble, at 13567-
13568. SO2 attainment plans must consist of two components: 
(1) Emission limits and other control measures that ensure 
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 2014 SO2 guidance recommends that emission limits 
be expressed as short-term average limits (e.g., addressing emissions 
averaged over one or three hours), but also describes an option to 
utilize emission limits with longer averaging times of up to 30 days so 
long as the state meets various suggested criteria. See 2014 
SO2 guidance, pp. 22 to 39. Should states and sources 
utilize longer averaging times, the guidance recommends that the longer 
term average limit be set at an adjusted level that reflects a 
stringency comparable to the 1-hour average limit that the plan 
otherwise would have set at the critical emission value (CEV) shown to 
provide for attainment.
    The 2014 SO2 guidance provides an extensive discussion 
of EPA's rationale for concluding that appropriately set, comparably 
stringent limitations based on averaging times 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.
    EPA considered that the 1-hour primary SO2 NAAQS, as 
specified in 40 CFR 50.17(b), is met at an ambient air quality 
monitoring site when the 3-year average of the annual 99th percentile 
of daily maximum 1-hour average concentrations is less than or equal to 
75 ppb. In a year with 365 days of valid monitoring data, the 99th 
percentile would be the fourth highest daily maximum 1-hour value. The 
2010 SO2 NAAQS, including this form of determining 
compliance with the standard, was upheld by the U.S. Court of Appeals 
for the District of Columbia Circuit in Nat'l Envt'l Dev. Ass'n's Clean 
Air Project v. EPA, 686 F.3d 803 (D.C. Cir. 2012). Because the standard 
has this form, a single hourly exceedance of the 75 ppb NAAQS level 
does not create a violation of the standard. Therefore, an emission 
limit which allows some operational flexibility or emission variability 
may still be protective of the standard.
    At issue is whether a source operating in compliance with a 
properly set longer term average could cause exceedances of the NAAQS 
level, and if so, what are the resulting frequency and magnitude of 
such exceedances. Specifically, EPA must determine with reasonable 
confidence whether a properly set longer term average limit will 
provide that the 3-year average of the annual fourth highest daily 
maximum 1-hour value will be at or below 75 ppb. A synopsis of EPA's 
review of how to judge whether such plans provide for attainment in 
light of the NAAQS' form, based on modeling of projected allowable 
emissions for determining attainment at monitoring sites, is given 
below.
    For SO2 plans based on 1-hour emission limits, the 
standard approach is to conduct modeling using fixed emission rates. 
The maximum emission rate that would be modeled to result in attainment 
(i.e., in an ``average year'' \3\ shows three, not four days with 
maximum hourly levels exceeding 75 ppb) is labeled the ``critical 
emission value'' or ``CEV.'' The modeling process for identifying this 
CEV inherently considers the numerous variables that affect ambient 
concentrations of SO2, such as meteorological data, 
background concentrations, and topography. In the standard approach, 
the state would then provide for attainment by setting a continuously 
applicable 1-hour emission limit at this CEV.
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    \3\ An ``average year'' is used to mean a year with average air 
quality. While 40 CFR 50 appendix T provides for averaging three 
years of 99th percentile daily maximum hourly values (e.g., the 
fourth highest maximum daily hourly concentration in a year with 365 
days with valid data), this discussion and an example below uses a 
single ``average year'' in order to simplify the illustration of 
relevant principles.
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    EPA recognizes that some sources have highly variable emissions, 
for example due to variations in fuel sulfur content and operating 
rate, that can make it extremely difficult, even with a well-designed 
control strategy, to ensure in practice that emissions for any given 
hour do not exceed the CEV. EPA also acknowledges the concern that 
longer term emission limits can allow short periods with emissions 
above the CEV, which, if coincident with meteorological conditions 
conducive to high SO2 concentrations, could in turn create 
the possibility of a NAAQS

[[Page 60936]]

exceedance occurring on a day when an exceedance would not have 
occurred if emissions were continuously controlled at the level 
corresponding to the CEV. However, for several reasons, EPA believes 
that the approach recommended in its guidance document suitably 
addresses this concern. First, from a practical perspective, EPA 
expects the actual emission profile of a source subject to an 
appropriately set longer term average limit to be similar to the 
emission profile of a source subject to an analogous 1-hour average 
limit. EPA expects this similarity because it has recommended that the 
longer term average limit be set at a level that is comparably 
stringent to the otherwise applicable 1-hour limit (reflecting a 
downward adjustment from the CEV) and that takes the source's emissions 
profile into account. As a result, EPA expects either form of emission 
limit to yield comparable air quality.
    Second, from a more theoretical perspective, EPA has compared the 
likely air quality with a source having maximum allowable emissions 
under an appropriately set longer term limit, as compared to the likely 
air quality with the source having maximum allowable emissions under 
the comparable 1-hour limit. In this comparison, in the 1-hour average 
limit scenario, the source is presumed at all times to emit at the CEV 
level, and in the longer term average limit scenario, the source is 
presumed occasionally to emit more than the CEV level but on average, 
and presumably at most times, to emit well below the CEV. In an 
``average year,'' compliance with the 1-hour limit is expected to 
result in three exceedance days (i.e., three days with maximum hourly 
values above 75 ppb) and a fourth day with a maximum hourly value at 75 
ppb. By comparison, with the source complying with a longer term limit, 
it is possible that additional hourly exceedances would occur that 
would not occur in the 1-hour limit scenario (if emissions exceed the 
CEV at times when meteorology is conducive to poor air quality). 
However, this comparison must also factor in the likelihood that hourly 
exceedances that would be expected in the 1-hour limit scenario would 
not occur in the longer term limit scenario. This result arises because 
the longer term limit requires lower emissions most of the time 
(because the limit is set well below the CEV), so a source complying 
with an appropriately set longer term limit is likely to have lower 
emissions at critical times than would be the case if the source were 
emitting as allowed with a 1-hour limit.
    As a hypothetical example to illustrate these points, suppose a 
source that always emits 1,000 pounds of SO2 per hour (lb/
hr), 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 5 highest daily maximum 1-
hour average 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 lb/hr. It is theoretically possible for a 
source meeting this limit to have emissions that occasionally exceed 
1,000 lb/hr, but with a typical emissions profile emissions would much 
more commonly be between 600 and 800 lb/hr. 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/hour, 1,100 lb/hr, 500 
lb/hr, 900 lb/hr, and 1,200 lb/hr, respectively. (This is a 
conservative example because the average of these emissions, 900 lb/hr, 
is well over the 30-day average emission limit.) These emissions would 
result in daily maximum 1-hour average 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 the NAAQS level that would not otherwise have 
occurred, but the third day would not have an exceedance that otherwise 
would have occurred, and the fourth day would have been below, rather 
than at, 75 ppb. In this example, the fourth highest maximum daily 
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 SO2 guidance, EPA found that the requirement for 
lower average emissions 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 April 2014 SO2 
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 NAAQS exceedances and better air quality than an emission profile 
with maximum allowable emissions under a 1-hour emission limit at the 
CEV. This result provides a compelling policy rationale for allowing 
the use of a longer averaging period in appropriate circumstances where 
the facts indicate that a result of this type might occur.\4\
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    \4\ See also work done to supplement the work described in 
appendix B. This supplemental work, done to address a comment on 
rulemaking for the Southwest Indiana SO2 nonattainment 
area objecting that the appendix B analysis is not comparable to an 
assessment of air quality with a 1-hour emission limit, provides 
further evidence that longer term limits that are appropriately 
determined can be expected to achieve comparable air quality as 
comparably stringent 1-hour limits. Documentation of this 
supplemental work is available in the docket for the Southwest 
Indiana rulemaking, at https://www.regulations.gov/document?D=EPA-R05-OAR-2015-0700-0023, as discussed in the associated rulemaking at 
85 FR 49969-49971 (August 17, 2020).
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    The question then becomes whether this approach--which is likely to 
produce no more overall NAAQS exceedances even though it may produce 
some unexpected exceedances above the CEV--meets the requirements in 
sections 110(a)(1), 172(c)(1), and 172(c)(6) for emission limitations 
in state implementation plans to ``provide for attainment'' of the 
NAAQS. For SO2, as for other pollutants, it is generally 
impossible to design a nonattainment plan in the present that will 
guarantee that attainment will occur in the future. A variety of 
factors can cause a well-designed plan to fail and unexpectedly not 
result in attainment, for example if meteorological conditions occur 
that are 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 meteorological conditions 
conducive to high concentrations will have elevated emissions leading 
to exceedances of the NAAQS level that would not otherwise have 
occurred, and must also weigh the likelihood that the requirement for 
lower emissions on average will result in days not having exceedances 
that would have been expected with emissions at the CEV. Additional 
policy considerations, such as in this case the desirability of 
accommodating real

[[Page 60937]]

world emissions variability without significant risk of NAAQS 
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 2014 SO2 guidance offers specific recommendations 
for determining an appropriate longer term average limit. The 
recommended method starts with determination of the 1-hour emission 
limit that would provide for attainment (i.e., the CEV), and applies an 
adjustment factor to determine the (lower) level of the longer term 
average emission limit that would be estimated to have a stringency 
comparable to the otherwise necessary 1-hour emission limit. This 
method uses a database of continuous emission data reflecting the type 
of control that the source will be using to comply with the SIP 
emission limits, which (if compliance requires new controls) may 
require use of an emission database from another source. The 
recommended method involves using these data to compute a complete set 
of emission averages, computed according to the averaging time and 
averaging procedures of the prospective emission limitation. In this 
recommended method, the ratio of the 99th percentile among these longer 
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.\5\ 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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    \5\ For example, if the CEV is 1,000 pounds of SO2 
per hour, and a suitable adjustment factor is determined to be 70 
percent, the recommended longer term average limit would be 700 lb/
hr.
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    EPA anticipates that most modeling used to develop longer term 
average emission limits and to prepare full attainment demonstrations 
will be performed using one of EPA's preferred air quality models. 
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).\6\ 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 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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    \6\ EPA published revisions to the Guideline on Air Quality 
Models 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'' (EPA, 2010).

IV. Review of Modeled Attainment Plan

    As part of its SIP development process, Ohio used EPA's regulatory 
dispersion model, AERMOD, to help determine the SO2 emission 
limit revisions that would be needed to bring the Muskingum River area 
into attainment of the 2010 SO2 NAAQS. Ohio evaluated the 
two highest-emitting facilities in the Muskingum River area--the 
Muskingum River Power Plant and the Globe Metallurgical, Inc. facility 
(Globe). According to Ohio's submittal, 99 percent of the Muskingum 
River area's 2011 SO2 emissions were attributable to the 
Muskingum River Power Plant, with the Globe facility accounting for 
1,203 tons of SO2, which comprised the remaining 1 percent 
that year. On May 31, 2015, all coal fired boilers at the Muskingum 
River Power Plant were permanently shut down. Subsequently, the ambient 
monitor which had been showing violations of the NAAQS no longer 
recorded violations. Nevertheless, for purposes of assuring attainment 
and maintenance of the NAAQS, Ohio determined that, in addition to the 
permanent retirement of the Muskingum River Power Plant, a reduction in 
allowable emissions at the remaining source, the Globe facility, was 
warranted. Ohio performed air quality modeling and analysis and issued 
Director's Final Findings and Orders (DFFOs) to the Globe facility 
establishing 24-hour average SO2 emission limits at the 
facility. Ohio submitted the DFFOs to EPA as a supplement its original 
SIP submission. These DFFOs were issued on June 23, 2020, and have a 
compliance deadline of September 15, 2020.
    The following paragraphs evaluate various features of the most 
recent modeling analysis that Ohio performed for its attainment 
demonstration, as supplemented by the DFFOs.

A. Model Selection and General Model Inputs

    For the Muskingum River attainment demonstration, Ohio used the 
AERMOD model, version 19191. AERMOD is EPA's preferred model for this 
type of application and version 19191 is the current version. The 
AERMOD model was run using the regulatory default mode.
    AERMOD requires land use to be characterized to determine how 
pollutants are dispersed in the atmosphere. The state used urban 
dispersion coefficients to represent the proposed heat island generated 
by the facility operations. Beyond the facility

[[Page 60938]]

industrial region, the area is best classified as rural.
    EPA's Guideline on Air Quality Models (40 CFR part 51 appendix W) 
acknowledges that larger industrial facilities can impact turbulence 
and dispersion in the vicinity of the facility, similar to overnight 
impacts on turbulence in cities.
    The Globe facility analysis used two approaches to examine and 
justify whether the heat released from the facility was significant 
enough to influence dispersion. They first used satellite thermal 
images to estimate the urban-rural temperature difference. Twelve 
images from the Advanced Spaceborne Thermal Emission and Reflection 
radiometer satellite system were identified, with 8 images without 
cloud interference, to estimate the difference in temperature between 
warm facility areas and cooler rural areas. The average difference 
between the industrial area temperatures and the rural temperatures was 
8.7 degrees Celsius.
    The second analysis used formulas from the AERMOD Formulation 
Document to relate heat flux to temperature differences between urban 
and rural areas. Another formula relates the temperature difference to 
population. The temperature difference using the Formulation Document 
equation results in a value of 8.5 degrees Celsius. This compares well 
with the 8.7 degree value determined from thermal satellite images. 
Ultimately the calculated heat release and temperature difference 
information can be used to calculate an estimated population. AERMOD 
uses a population value to represent the strength of the urban impact. 
The population used in the Globe analysis is 108,000, which reflects a 
relatively modest industrial heat island effect.
    The state used a set of nested grids of receptors centered on the 
Globe facility. The analysis included a total of 5,049 receptors. 
Receptors were placed every 25 meters (m) along the ambient air 
boundary out to 350 m; 50 m out to 1 km; 100 m spacing out to 2 km, and 
200 m spacing out to 5 km. The facility is in the process of purchasing 
property to the north. This property will be non-ambient air and does 
not have receptors in the current modeling. A fence runs around the 
entire Globe facility with adjacent property protected through 
surveillance and patrols. EPA finds that Ohio's submitted modeling 
results, based on modeling without receptors on fenced plant property 
and surveilled and patrolled property currently under purchase, are 
adequate to demonstrate that no such violations of the 1-hour 
SO2 NAAQS are occurring.
    Ohio used the AERMAP terrain preprocessor, version 18081, with USGS 
Digital Elevation Data to include terrain heights at the receptor 
locations. The Globe facility is in the Muskingum River valley. Terrain 
rises about 50-60 m within a kilometer to the east and north of the 
facility. Similar terrain increases also occur about 2-3 km in the 
westerly and southern directions. EPA finds the model selection and 
these modeling options appropriate.

B. Meteorological Data

    Ohio used five years (2014-2018) of National Weather Service (NWS) 
meteorological data from the Parkersburg, West Virginia Airport 
(Station 03804) with upper air data from Pittsburgh, Pennsylvania 
(Station 94823). One-minute wind data was processed using AERMINUTE 
version 15272 with a 0.5 m/s minimum wind speed threshold option. 
Surface parameters of the Bowen ratios (a measure of surface moisture) 
were developed using monthly precipitation data compared to 
climatological averages. The Parkersburg NWS station is at the Regional 
Airport located about 10 km northeast of Parkersburg, and about 35 km 
southeast of the Globe facility. The station is up out of the Ohio 
River valley on the elevated terrain. The Pittsburgh upper air station 
is at the International Airport and is roughly 140 km from the Globe 
facility. The prevailing winds in southeast Ohio are from the south and 
west. The Parkersburg NWS wind roses illustrate a predominantly 
southwesterly flow. Both the surface and upper air station are 
considered reasonably representative of surface and upper air 
meteorological conditions, respectively, impacting the area around the 
Globe facility. EPA finds that the meteorological data and the 
procedure for determining surface characteristics are acceptable.

C. Modeled Emissions Data

    The Globe facility consists of two electric arc furnace shops. The 
main sources of SO2 emissions are two baghouses, which 
collect emissions at the two shops from the electric arc furnaces and 
ancillary equipment, respectively. Emissions from each baghouse exit 
through a roof monitor. The Globe facility modeled emissions from the 
roof monitors using point source release characteristics that allowed 
for capturing building downwash impacts while also preserving the total 
buoyancy of the emission releases. Neither of these features would have 
been represented had the sources been modeled as volume sources. Volume 
source characterization does not include plume buoyancy or building 
downwash impacts. The baghouse stack characterizations include a stack 
height equal to the height of the roof monitor. The exit velocities 
were calculated to match the actual flow rates from each baghouse roof 
monitor. Additionally, one of the baghouses (Baghouse 1) has a roof 
monitor that releases emissions horizontally rather than vertically. 
Consequently, the POINTHOR AERMOD option was used for this source to 
more accurately characterize its release.
    Fugitive emissions released from the roof of the furnace shops were 
modeled using volume source parameters. A series of seven alternate 
volume sources were placed at the height of the roof monitor at furnace 
shop 1, and a series of 4 alternate volume sources were placed at the 
height of furnace shop 2. All were aligned evenly along monitor 
openings. Volume source model inputs were developed based on 
recommendations in the AERMOD User's Guide, Table 3-2.
    Ohio modeled 26 different scenarios reflecting 26 different 
combinations of emissions from the two baghouses. Each of the 26 
scenarios was specifically modeled for attainment of the 1-hr 
SO2 NAAQS. Each of the 26 different scenarios also included 
an assumption that 2 percent of the total emissions were being released 
as fugitive emissions from the furnace shop. The 2 percent fugitive 
value was based on a capture efficiency analysis document prepared for 
the Globe facility and included in Ohio's submittal.
    Ohio EPA's attainment demonstration only modeled emission units 
associated with the Globe facility. An examination of National 
Emissions Inventory data shows there are no other SO2 
sources of significance in the area near the Globe facility, 
specifically that no other sources within 25 km emit over 5 tons per 
year (tpy).

D. Emission Limits

    An important prerequisite for approval of a nonattainment plan is 
that the emission limits that provide for attainment be quantifiable, 
fully enforceable, replicable, and accountable. See General Preamble at 
13567-68. Ohio issued DFFOs to Globe on June 23, 2020, which set forth 
new emission limits for the facility on the basis of a matrix of CEVs 
for the two baghouses, where each combination was modeled to 
demonstrate attainment and maintenance of the standard. As part of this 
proposed approval of Ohio's

[[Page 60939]]

supplemented attainment plan for this area, EPA is proposing to approve 
Ohio's June 23, 2020 DFFOs for the Globe facility into the SIP, which 
include these new CEV combinations as emission limits. See Table 1.

                                 Table 1
------------------------------------------------------------------------
                                              Calendar day (24-hour)
                                                  emission limits
        SO2  emission  limit sets        -------------------------------
                                           BH1 (lbs/hr)    BH2 (lbs/hr)
------------------------------------------------------------------------
1.......................................           195.3             0.0
2.......................................           190.6            55.8
3.......................................           186.0            74.4
4.......................................           181.3           102.3
5.......................................           176.7           116.2
6.......................................           172.0           130.2
7.......................................           167.4           144.1
8.......................................           162.7           158.1
9.......................................           158.1           167.4
10......................................           153.4           176.7
11......................................           148.8           186.0
12......................................           144.1           190.6
13......................................           139.5           195.3
14......................................           134.8           199.9
15......................................           130.2           204.6
16......................................           125.5           213.9
17......................................           120.9           218.5
18......................................           116.2           223.2
19......................................           111.6           223.2
20......................................           106.9           227.8
21......................................            88.3           232.5
22......................................            74.4           237.1
23......................................            60.4           241.8
24......................................            41.8           246.4
25......................................            27.9           251.1
26......................................             0.0           260.4
------------------------------------------------------------------------

    As described in the DFFOs, compliance with the emission limit sets 
is determined through mass balance calculations, as implemented through 
a compliance assurance plan (CAP). Compliance with the emission limits 
will also be determined through periodic compliance performance 
testing.
    Ohio EPA stated in its June 2020 attainment plan supplement that it 
plans to adopt and submit a state rule that incorporates the emission 
limits for the Globe facility, and associated requirements, into its 
regulations (Ohio Administrative Code Chapter 3745-18). Ohio believes 
that its DFFOs provide enforceable limits and specification of the 
procedures that will be used to determine compliance with these limits 
such that the DFFOs provide sufficient enforceable requirements for EPA 
to rely on these DFFOs as enforceable measures that provide for 
attainment, if incorporated as permanent measures into the SIP. Any 
future submittal of rules to replace the DFFOs in the SIP will be 
addressed in separate future rulemaking, subject to the requirements of 
CAA section 110(l).
    Because the limits set forth in the DFFOs are expressed as 24-hour 
average limits, part of the review of Ohio's nonattainment plan must 
address 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 plan have been suitably 
demonstrated to provide for attainment. The first subsection that 
follows addresses the overall enforceability of the emission limits in 
Ohio's plan, and the second subsection that follows addresses the 24-
hour average limits.
    The DFFOs also require that validation testing be performed to 
verify the accuracy of the mass balance calculations. In addition, a 
Capture Evaluation conducted by a third party is required to be 
performed during the validation testing. This Capture Evaluation will 
include observations of emissions capture during the validation testing 
period, an evaluation of emissions capture performance, and, if 
appropriate, recommendations for measures to improve capture, as well 
as operational parameter(s) and ranges that could serve as an indicator 
of ongoing performance of the capture system.
1. Enforceability
    Ohio's supplemented nonattainment plan for the Muskingum River area 
relies on the permanence of the Muskingum River Power Plant retirement 
and on revised emission limits for the Globe facility as discussed 
above (in section D. Emission Limits). As of April 2015, the entire 
Muskingum River Power Plant was shut down and all coal fired boilers 
were permanently retired. This facility is no longer authorized to 
operate its coal-fired boilers, and cannot reinstate them without 
obtaining a new permit under Ohio's New Source Review program. 
Therefore, the reductions in SO2 emissions from the 
Muskingum River Power Plant retirement can be considered permanent, 
enforceable reductions.
    Ohio's June 2020 DFFOs issued to Globe, in addition to establishing 
new emission limits, also provide specific measures and requirements 
that add stringency to the required emission control requirements. 
Specifically, the DFFOs require that Globe conduct validation testing 
and perform a Capture Evaluation at the facility's two baghouses to 
validate the mass balance calculation, and that Globe submit a CAP to 
be approved by Ohio EPA in consultation with EPA. The DFFOs require 
that the Capture Evaluation be performed by a third party in a manner 
designed to identify improvements and other measures, if any, that may 
aid in the capture of SO2 emissions, and operational 
parameters that could serve as a reasonable indicator of ongoing 
performance of the capture systems. The CAP will include specific 
monitoring data and techniques used to perform the mass balance 
calculations, associated recordkeeping and reporting to demonstrate 
compliance with the emission limits, parameters to be monitored to 
ensure adequate performance of the capture system, and reporting from 
the Capture Evaluation.
    To provide an additional level of assurance that air quality 
standards are being met in the area, Ohio's new DFFOs require Globe to 
install an ambient SO2 monitor. This monitor will be located 
across the Muskingum River in the vicinity of the Globe facility near 
an expected area of maximum impact as approved by Ohio EPA.
2. Longer Term Average Limits
    Ohio's SIP submittal includes emission limits for the Globe 
facility which require compliance based on 24-hour average emission 
rates. See Table 1. Ohio's primary method for determining compliance is 
a mass balance method, in which the emissions are assessed by 
determining the sulfur content of the raw materials, determining the 
sulfur content of the product and the process by-products, and assuming 
that the difference between these quantities of sulfur is all converted 
to SO2 and emitted to the atmosphere. Ohio adopted a 24-hour 
limit to provide a more practical frequency of conducting this 
compliance determination.
    In accordance with EPA's recommendations, Ohio adopted its limits 
at levels that were adjusted to account for the effect on stringency of 
adopting the limits on a 24-hour average basis. The Globe facility does 
not have the continuous emissions monitoring system (CEMS) data 
necessary to determine an appropriate site-specific adjustment factor. 
Therefore, Ohio applied a national average adjustment factor from 
appendix D of EPA's 2014 guidance. Specifically, Ohio applied an 
adjustment factor of 0.93, appropriate for establishment of 24-hour 
average SO2 limits for sources without SO2 
emissions control equipment. Since EPA anticipates that the Globe 
facility will meet its limits through careful management of the sulfur 
content of its feed materials, EPA considers this selection of an 
adjustment factor to be acceptable.
    Ohio calculated the Globe facility's emission limits in accordance 
with EPA's recommended method. See

[[Page 60940]]

section III. Ohio used dispersion modeling to determine 26 combinations 
of 1-hour CEVs for each unit that would provide for attainment of the 
NAAQS. Ohio then applied the above adjustment factor to determine, for 
each combination, the level of the longer term average emission limit 
for each unit that would be estimated to have a stringency comparable 
to the critical 1-hour emission values for each combination. EPA finds 
this acceptable.

E. Background Concentrations

    The modeled attainment demonstration for a nonattainment area 
specifically includes the maximum allowable emissions and the 
individual dispersion characteristics of the most significant emission 
source in the area. To ensure that the demonstration also represents 
the cumulative impacts of additional sources which are individually too 
small or too distant to be expected to show a significant concentration 
gradient within the modeling domain, a background concentration is 
added to the modeled results. Data from a nearby air quality monitor 
can be used to determine a background value which approximates the 
diffuse impacts of these sources within the modeling domain. For the 
Globe emissions assessment, Ohio used background contributions on a 
season/hour-of-day basis using values from the Hackney monitor, located 
approximately 5.5 km to the north of the Globe facility. In order to 
avoid double counting of impacts from Globe, hourly values in a 90 
degree sector representing winds from the south were removed from the 
monitoring data and replaced with the average of those hourly values 
prior to determining season/hour-of-day values. Values ranged from 6.32 
micrograms per cubic meter ([micro]g/m\3\) to 13.09 [micro]g/m\3\. EPA 
finds the background values used in the Globe assessment to be 
acceptable.

F. Summary of Results

    Ohio's attainment modeling analyses resulted in a predicted 1-hour 
design value of 196.0 [micro]g/m\3\, or 74.8 ppb, which is below the 
SO2 NAAQS of 75 ppb/196.4 [micro]g/m\3\. This modeled value, 
which includes the background concentration, occurred at the northern 
boundary of the Globe facility, less than 200 meters from the emission 
units.
    EPA policy also requires that one facility must not cause or 
contribute to exceedances of the NAAQS on another facility's property. 
Ohio's modeling only excludes receptors from the Globe facility. 
Consequently, EPA agrees that the modeling shows that no facility is 
causing or contributing to violations within another facility's 
property.
    The emission releases from the Globe facility are difficult to 
characterize. Ohio considered various options for characterizing the 
release of fugitive emissions from the baghouses and the furnace shops 
before concluding that the characterizations described above were 
warranted. While no direct means of assessing the efficiency at 
capturing the emissions of the furnace are available, the requirements 
of the DFFOs, particularly the requirement to implement recommendations 
of the Capture Evaluation, help make the plan's estimate of 98 percent 
capture a reasonable estimate. Therefore, despite the uncertainties 
inherent in modeling this source, EPA finds that Ohio has submitted an 
appropriate analysis of the impact of this source. In addition, EPA 
finds that the ambient SO2 monitoring that Globe and Ohio 
are undertaking will provide a further assessment of the reliability of 
this modeling and thereby will provide further assurance that air 
quality in this area is attaining the 1-hour SO2 NAAQS.
    Based on its review of Ohio's analysis, EPA finds that the emission 
limits for the Globe facility set forth in the DFFOs, in combination 
with other measures identified in the state's plan, will provide for 
attainment and maintenance of the 2010 SO2 NAAQS, and 
proposes to approve the DFFOs into the SIP.

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).
    Ohio prepared an emissions inventory \7\ using 2011 as the base 
year and 2018, the SO2 NAAQS attainment year, as the future 
year. The inventories were prepared for six categories: Electrical 
generating units (EGU), non-electrical generating units (non-EGU), non-
road mobile sources, on-road mobile sources, area sources, and marine, 
air and rail sources. The 2011 base year inventory totaled 105,317.67 
tpy for all six categories. Reflecting growth and known, planned, point 
source emission reductions, the 2018 future year inventory projection 
totaled 1,204.18 tpy. Emissions from the Globe facility were projected 
to remain constant between 2011 and 2018. The EGU category of this 
emissions inventory only contains the Muskingum River Power Plant's six 
emission sources (six coal-fired boilers). The 2018 inventory submitted 
by Ohio accounted for the closure of the Muskingum River Power Plant. 
As of April 2015, the Muskingum River Power Plant retired its coal-
fired boilers, which resulted in projected 2018 EGU emissions of 0.0 
tpy (104,113.16 tpy reduction from 2011), and thus would reduce Ohio's 
total six-category 2018 projected year inventory to 1,204.18 tpy. 
Ohio's emissions inventory indicates that SO2 emissions were 
significantly and permanently reduced in the Muskingum River area of 
the SO2 NAAQS attainment year.
---------------------------------------------------------------------------

    \7\ The Emissions Modeling Clearinghouse (EMCH) provides 
emissions model input formatted inventories based on the latest 
versions of the NEI databases as well as the projection of these 
emissions. For Ohio's inventory, Ohio used 2011 and projected 2018 
county level emissions data for area (non-point), on-road, marine/
air/rail (MAR), and non-road sources from the 2011 NEI version 1-
based Emissions Modeling Platform (2011v6) (http://ftp.epa.gov/EmisInventory/2011v6/v1platform/).
---------------------------------------------------------------------------

B. RACM/RACT and Emissions Limitations and Control Measures

    Section 172(c)(1) of the CAA requires states to adopt and submit 
all RACM, including RACT, as needed to attain the standards as 
expeditiously as practicable. Section 172(c)(6) requires the SIP to 
contain enforceable emission limitations and control measures necessary 
to provide for timely attainment of the standard. Ohio EPA's initial 
plan for attaining the 1-hour SO2 NAAQS in the Muskingum 
River area was based only on emission reductions resulting from the 
Muskingum River Power Plant. Following discussions with EPA, Ohio 
determined that a combination of the permanent retirement of the 
Muskingum River Power Plant and additional emission limitations and 
emission reduction strategies implemented at the Globe facility will 
result in attainment of the NAAQS. Redevelopment of the Muskingum River 
Power Plant site would require new source review analysis and 
potentially additional emission controls to maintain SO2

[[Page 60941]]

attainment in the Muskingum River area. Therefore, EPA concludes that 
the Muskingum River Power Plant's SO2 emissions are 
currently zero and RACT requirements are satisfied at this source.
    The initial Globe facility RACM evaluation and subsequent 
supplemental RACM evaluation[1] determined that RACM for control of 
SO2 emissions from the electric arc furnaces (EAFs) at the 
Globe facility is pollution prevention through the use of low sulfur 
coal and low sulfur coke. In its evaluation of whether Ohio satisfied 
the requirement for RACM, in accordance with EPA guidance, EPA 
evaluated whether Ohio had provided for sufficient control to provide 
for attainment.
    Ohio's plan includes new emission limits at the Globe facility and 
requires timely compliance with such limits and other control measures 
required by the June 23, 2020 DFFOs. Ohio has determined that these 
measures suffice to provide for timely attainment. EPA concurs and 
proposes to find that the state has satisfied the requirements in 
sections 172(c)(1) and 172(c)(6) to adopt and submit all RACM and 
enforceable limitations and control measures as are needed to attain 
the standards as expeditiously as practicable.

C. New Source Review (NSR)

    Section 172 of the CAA requires the state to have an adequate new 
source review program. EPA approved Ohio's nonattainment new source 
review rules on January 22, 2003 (68 FR 2909). Ohio's new source review 
rules, codified at OAC 3745-31, provide for appropriate new source 
review for SO2 sources undergoing construction or major 
modification in the Muskingum River area without need for modification 
of the approved rules. The latest revisions to OAC Chapter 3745-31 were 
approved into Ohio's SIP on February 20, 2013 (78 FR 11748). EPA 
concludes that this requirement has been met for this area.

D. RFP

    Section 172 of the CAA requires Ohio's Muskingum River 
nonattainment SIP to provide for reasonable further progress toward 
attainment. For SO2 SIPs, which address a small number of 
affected sources, requiring expeditious compliance with attainment 
emission limits can address the RFP requirement. EPA concludes that the 
state's revised limits and required additional control strategy 
measures for the Globe facility and the 2015 retirement of the 
Muskingum River Power Plant represent implementation of control 
measures as expeditiously as practicable. Accordingly, EPA proposes to 
find that Ohio's plan provides for RFP.

E. Contingency Measures

    Section 172 of the CAA requires that nonattainment plans include 
additional measures which will take effect if an area fails to meet RFP 
or fails to attain the standard by the attainment date. 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. 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 for 
the state to undertake aggressive follow-up for compliance and 
enforcement. Ohio's plan provides for satisfying the contingency 
measure requirement in this manner. EPA concurs and proposes to approve 
Ohio's plan for meeting the contingency measure requirement in this 
manner.

VI. EPA's Proposed Action

    EPA is proposing to approve Ohio's SIP submission for attaining the 
2010 1-hour SO2 NAAQS and for meeting other nonattainment 
area planning requirements for the Muskingum River SO2 
nonattainment area. This SO2 nonattainment plan includes 
Ohio's revised emission limits and attainment demonstration for the 
Muskingum River nonattainment area as submitted on June 23, 2020, and 
addresses the CAA requirements for reasonable further progress, RACM/
RACT, base-year and projection-year emission inventories, and 
contingency measures. In conjunction with this proposed plan approval, 
EPA is also proposing to approve the DFFOs issued by Ohio to Globe on 
June 23, 2020, and submitted to EPA as a supplement to the original SIP 
submission.
    EPA concludes that Ohio has appropriately demonstrated that the 
plan provisions provide for attainment of the 2010 1-hour primary 
SO2 NAAQS in the Muskingum River nonattainment area and that 
the plan meets the other applicable requirements of section 172 of the 
CAA. EPA therefore is proposing to approve Ohio's nonattainment plan 
for the Muskingum River nonattainment area.

VII. Incorporation by Reference

    In this rule, EPA is proposing to include in a final EPA rule 
regulatory text that includes incorporation by reference. In accordance 
with requirements of 1 CFR 51.5, EPA is proposing to incorporate by 
reference the Ohio Director's Final Findings and Orders for the Globe 
facility, issued on June 23, 2020. EPA has made, and will continue to 
make, these documents generally available through www.regulations.gov, 
and at the EPA Region 5 Office (please contact the person identified in 
the FOR FURTHER INFORMATION CONTACT section of this preamble 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 
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 action:
     Is not a significant regulatory action subject to review 
by the Office of Management and Budget under Executive Orders 12866 (58 
FR 51735, October 4, 1993) and 13563 (76 FR 3821, January 21, 2011);
     Is not an Executive Order 13771 (82 FR 9339, February 2, 
2017) regulatory action because it is not a significant regulatory 
action under Executive Order 12866;
     Does not impose an information collection burden under the 
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
     Is certified as not having a significant economic impact 
on a substantial number of small entities under the Regulatory 
Flexibility Act (5 U.S.C. 601 et seq.);
     Does not contain any unfunded mandate or significantly or 
uniquely affect small governments, as described in the Unfunded 
Mandates Reform Act of 1995 (Pub. L. 104-4);
     Does not have federalism implications as specified in 
Executive Order 13132 (64 FR 43255, August 10, 1999);
     Is not an economically significant regulatory action based 
on health or safety risks subject to Executive Order 13045 (62 FR 
19885, April 23, 1997);
     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

[[Page 60942]]

     Does not provide EPA with the discretionary authority to 
address, as appropriate, disproportionate human health or environmental 
effects, using practicable and legally permissible methods, under 
Executive Order 12898 (59 FR 7629, February 16, 1994).
    In addition, the SIP is not approved to apply on any Indian 
reservation land or in any other area where EPA or an Indian tribe has 
demonstrated that a tribe has jurisdiction. In those areas of Indian 
country, the 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, Intergovernmental relations, Reporting and recordkeeping 
requirements, Sulfur oxides.

    Dated: September 24, 2020.
Kurt Thiede,
Regional Administrator, Region 5.
[FR Doc. 2020-21560 Filed 9-28-20; 8:45 am]
BILLING CODE 6560-50-P