Document ID: EPA-R05-OAR-2017-0165-0003
Agency: epa
Document Type: Proposed Rule
Title: Proposed approval of the Ohio 2010 1-Hour SO2 NAAQS Nonattainment SIP for Lake County
Posted Date: 2018-08-21T04:00Z

[Federal Register Volume 83, Number 162 (Tuesday, August 21, 2018)]
[Proposed Rules]
[Pages 42235-42244]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2018-17930]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R05-OAR-2015-0699; EPA-R05-OAR-2017-0165; FRL-9982-31-Region 5]

Air Plan Approval; Ohio; Attainment Plan for the Lake County 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 State Implementation Plan (SIP) revision which Ohio submitted 
to EPA on April 3, 2015, and supplemented in October 2015 and March 
2017, as its plan for attaining the 1-hour sulfur dioxide 
(SO2) primary national ambient air quality standard (NAAQS) 
for the Lake County SO2 nonattainment area. This plan 
(herein called a ``nonattainment plan'') includes Ohio's attainment 
demonstration, enforceable emission limitations and control measures, 
and other elements required under the Clean Air Act (CAA). EPA proposes 
to conclude that Ohio has appropriately demonstrated that the 
nonattainment plan provides for attainment of the 2010 1-hour primary 
SO2 NAAQS in Lake County by the applicable attainment date 
and that the plan meets the other applicable requirements under the 
CAA.

DATES: Comments must be received on or before September 20, 2018.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R05-
OAR-2015-0699 (nonattainment SIP) or EPA-R05-OAR-2017-0165 
(SO2 rule revisions) at http://www.regulations.gov, or via 
email to [email protected]. For comments submitted at 
Regulations.gov, follow the online instructions for submitting 
comments. Once submitted, comments cannot be edited or removed from 
Regulations.gov. For either manner of submission, EPA may publish any 
comment received to its public docket. Do not submit electronically any 
information you consider to be Confidential Business Information (CBI) 
or other information whose disclosure is restricted by statute. 
Multimedia submissions (audio, video, etc.) must be accompanied by a 
written comment. The written comment is considered the official comment 
and should include discussion of all points you wish to make. EPA will 
generally not consider comments or comment contents located outside of 
the primary submission (i.e. on the web, cloud, or other file sharing 
system). For additional submission methods, please contact the person 
identified in the FOR FURTHER INFORMATION CONTACT section. For the full 
EPA public comment policy, information about CBI or multimedia 
submissions, and general guidance on making effective comments, please 
visit http://www2.epa.gov/dockets/commenting-epa-dockets.

FOR FURTHER INFORMATION CONTACT: Mary Portanova, Environmental 
Engineer, Control Strategies Section, Air Programs Branch (AR-18J), 
Environmental Protection Agency, Region 5, 77 West Jackson Boulevard, 
Chicago, Illinois 60604, (312) 353-5954, [email protected].

SUPPLEMENTARY INFORMATION: Throughout this document, whenever ``we,'' 
``us,'' or ''our'' is used, we mean EPA. The docket number EPA-R05-OAR-
2015-0699 refers to Ohio's nonattainment SIP submittal of April 3, 
2015, supplemented on October 13, 2015. This state submittal addressed 
Ohio's Lake County, Muskingum River, and Steubenville OH-WV 
SO2 nonattainment areas. The docket number EPA-R05-OAR-2017-
0165 refers to Ohio's OAC 3745-18 SO2 rules SIP submittal of 
March 13, 2017. EPA is proposing action on only the Lake County portion 
of Ohio's nonattainment SIP submittal and the portions of OAC 3745-18 
that are specifically pertinent to Ohio's Lake County nonattainment SIP 
at this time. The Muskingum River and Steubenville portions of the 
nonattainment SIP and the remainder of the OAC 3745-18 rule revisions 
will be addressed in subsequent rulemaking actions.
    The following outline is provided to aid in locating information 
regarding EPA's proposed action on Ohio's Lake County SO2 
nonattainment plan.

Table of Contents

I. Why was Ohio required to submit an SO2 plan for the 
Lake County 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
    1. Enforceability
    2. Longer-Term Average Limits
    E. Background Concentrations
    F. Summary of Results
V. Review of Other Plan Requirements
    A. Emissions Inventory
    B. Reasonably Available Control Measures and Technology
    C. New Source Review
    D. Reasonable Further Progress
    E. Contingency Measures
VI. Ohio's SIP Rules
VII. EPA's Proposed Action
VIII. Incorporation by Reference
XI. Statutory and Executive Order Reviews

I. Why was Ohio required to submit an SO[bdi2] plan for the Lake County 
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 average concentrations is called the air quality 
monitor's SO2 ``design value.'' For the 3-year period 2009-
2011, the design value at the SO2 monitor in Painesville, 
Lake County (39-085-0007) was 157 ppb, which is a violation of the 
SO2 NAAQS. Lake County's SO2 designation was 
based upon the monitored design value at this location for this three-
year period. (Lake County's other SO2 monitor, located in 
Eastlake, Ohio (39-085-0003), had a 2009-2011 design value of 33 ppb, 
which is not a violation.) On August 5, 2013, EPA designated a first 
set of 29 areas of the country as nonattainment for the 2010 
SO2 NAAQS, including the Lake County nonattainment area. See 
78 FR 47191, codified at 40 CFR part 81, subpart C. These area 
designations were effective on October 4, 2013. Section 191(a) of the 
CAA directs states to submit SIPs for

[[Page 42236]]

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 Lake County is October 4, 2018.
    In response to the requirement for SO2 nonattainment 
plan submittals, Ohio submitted a nonattainment plan for the Lake 
County nonattainment area on April 3, 2015,\1\ and supplemented it on 
October 13, 2015, and on March 13, 2017. 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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    \1\ For a number of areas, EPA published notice 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 had submitted its SO2 
nonattainment plan before that date, EPA did not make such a finding 
with respect to Ohio's submittal for Lake County.
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II. Requirements for SO[bdi2] 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 April 2014 SO2 
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; a demonstration of 
reasonable further progress (RFP); implementation of reasonably 
available control measures (RACM); enforceable emission limitations and 
control measures; new source review (NSR); and adequate contingency 
measures for the affected area. A synopsis of these requirements can be 
found in the proposed rulemaking for the Lemont and Pekin, Illinois, 
SO2 nonattainment plans, which was published on October 5, 
2017 at 82 FR 46434.\2\
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    \2\ See https://www.regulations.gov/document?D=EPA-R05-OAR-2016-0138-0001. The Lemont and Pekin area action was finalized on 
February 1, 2018 (83 FR 4591).
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    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 applicable 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. 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. General Preamble, at 13567-13568. 
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 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 shown to 
provide for attainment.
    The April 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

[[Page 42237]]

average of the annual 99th percentile of daily maximum 1-hour average 
concentrations is less than or equal to 75 ppb. In a year with 365 days 
of valid monitoring data, the 99th percentile would be the fourth 
highest daily maximum 1-hour value. The 2010 SO2 NAAQS, 
including this form of determining compliance with the standard, was 
upheld by the U.S. Court of Appeals for the District of Columbia 
Circuit in Nat'l Envt'l Dev. Ass'n's Clean Air Project v. EPA, 686 F.3d 
803 (D.C. Cir. 2012). Because the standard has this form, a single 
exceedance 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, 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 plans for SO2 based on 1-hour emission limits, the 
standard approach is to conduct modeling using fixed emission rates. 
The maximum emission rate that would be modeled to result in attainment 
(i.e., in an ``average year'' \3\ shows three, not four days with 
maximum hourly levels exceeding 75 ppb) is labeled the ``critical 
emission value.'' The modeling process for identifying this 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.
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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 critical emission value. EPA also acknowledges 
the concern that longer-term emission limits can allow short periods 
with emissions above the ``critical emissions value,'' which, if 
coincident with meteorological conditions conducive to high 
SO2 concentrations, could in turn create the possibility of 
a NAAQS exceedance occurring on a day when an exceedance would not have 
occurred if emissions were continuously controlled at the level 
corresponding to the critical emission value. However, for several 
reasons, EPA believes that the approach recommended in its guidance 
document suitably addresses this concern.
    First, from a practical perspective, EPA expects the actual 
emission profile of a source subject to an appropriately set longer-
term average limit to be similar to the emission profile of a source 
subject to an analogous 1-hour average limit. EPA expects this 
similarity because it has recommended that the longer-term average 
limit be set at a level that is comparably stringent to the otherwise 
applicable 1-hour limit (reflecting a downward adjustment from the 
critical emissions value) 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 
critical emission level, and in the longer-term average limit scenario, 
the source is presumed occasionally to emit more 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 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 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 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 there 
is a source that always emits 1000 pounds of SO2 per hour 
(lb/hr), and thereby maintains air quality at the level of the NAAQS 
(i.e., a calculated design value of 75 ppb). Air quality depends on 
both emissions and meteorological conditions. In an ``average year,'' 
with typically varying meteorological conditions, the steady 1000 lb/hr 
emissions will lead to slightly different daily average 1-hour 
concentrations. Suppose that the five highest maximum daily average 1-
hour concentrations in that average year are 100 ppb, 90 ppb, 80 ppb, 
75 ppb, and 70 ppb. With the fourth value at 75 ppb, the NAAQS is met. 
(In this simplified example, we 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.) Now, 
suppose that the source is 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 1000 lb/hr, but with a 
typical emissions profile emissions would much more commonly be between 
600 and 800 lb/hr. Suppose for example that the emissions on those same 
five days were 800 lb/hr, 1100 lb/hr, 500 lb/hr, 900 lb/hr, and 1200 
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.) Based on the previous ratio of concentrations to 
emissions on each day (representing the influence of meteorology), the 
new emission rates would be expected to 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

[[Page 42238]]

would have an exceedance 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. The fourth highest daily maximum concentration under this 30-day 
average example would be 67.5 ppb. This example serves to show that the 
net effect of allowing some limited emission variability is that a 
longer-term limit can still provide for attainment.
    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 exceedances 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 that a result of 
this type might 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 requirements in sections 110(a)(1), 172(c)(1), 172(c)(6), and 
192(a) 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 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 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 critical 
emission value), and applies an adjustment factor to determine the 
(lower) level of the longer-term average emission limit that would be 
estimated to have a stringency comparable to the otherwise necessary 1-
hour emission limit. This method uses a database of continuous emission 
data reflecting the type of control that the source will be using to 
comply with the SIP emission limits, which (if compliance requires new 
controls) may require use of an emission database from another source. 
The recommended method involves using these data to compute a complete 
set of emission averages, computed according to the averaging time and 
averaging procedures of the prospective emission limitation. In this 
recommended method, the ratio of the 99th percentile among these long-
term averages to the 99th percentile of the 1-hour values represents an 
adjustment factor that may be multiplied by the candidate 1-hour 
emission limit to determine a longer-term average emission limit that 
may be considered comparably stringent.\4\
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    \4\ For example, if the critical emission value is 1000 lb/hr of 
SO2, 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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    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.
    EPA anticipates that most modeling used to develop long-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).\5\ In 2005, EPA promulgated AERMOD as the 
Agency's preferred near-field dispersion modeling for a wide range of 
regulatory applications addressing stationary sources (for example in 
estimating SO2 concentrations) in all types of terrain based 
on extensive developmental and performance evaluation. Supplemental 
guidance on modeling for purposes of demonstrating attainment of the 
SO2 standard is provided in appendix A to the April 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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    \5\ 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

[[Page 42239]]

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 Lake County into 
attainment of the 2010 SO2 NAAQS. Ohio evaluated the three 
highest-emitting facilities in Lake County, which together made up 98 
percent of Lake County's 2011 SO2 emissions. Ohio's analyses 
determined that a reduction in allowable emissions at two facilities 
would provide for attainment in Lake County. The following paragraphs 
evaluate various features of the modeling analysis that Ohio performed 
for its attainment demonstration.

A. Model Selection and General Model Inputs

    For the Lake County SIP attainment demonstration, Ohio used the 
AERMOD model, version 14134. AERMOD is EPA's preferred model for this 
application, and version 14134 was the current, appropriate model 
version when the modeling was performed. Occasionally, EPA releases 
updates to the model between the time that a state completes its 
modeling analysis and the time that EPA acts on the state's submittal.
    If the state's modeling was properly performed using an appropriate 
model version and submitted as expeditiously as practicable, EPA 
considers that model version acceptable, as long as the newer model 
version available at the time of EPA's review does not contain 
revisions or error corrections that are expected to significantly 
damage the credibility of the older modeled results. The more recently 
released versions of AERMOD, 15181 (2015), 16216r (2017), and 18081 
(2018), provided revisions to the model which EPA does not expect to 
have a significant effect on the modeled results for the analysis that 
Ohio performed for Lake County.\6\ Therefore, EPA accepts AERMOD 
version 14134 for Ohio's submitted analysis.
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    \6\ In early 2017, EPA identified an issue in version 15181 of 
AERMOD, which affected the adjusted surface friction velocity 
(ADJ_U*) parameter used in AERMET (AERMOD's meteorological data 
preprocessor). The problem was corrected in AERMOD version 16216r, 
which was released on January 17, 2017. The issue affecting ADJ_U* 
was not present in AERMOD version 14134, and Ohio did not use the 
ADJ_U* option in the Lake County modeling, as it was a non-default 
option at the time. Therefore, the results of the Lake County 
modeling are unaffected by this issue.
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    Ohio ran the AERMOD model in regulatory default mode, with rural 
dispersion coefficients. Ohio performed a land use analysis which 
considered land use within a 3 kilometer (km) radius of each facility, 
using National Land Cover Database data from 1992 and 2011. Ohio 
considered the urban and rural land use percentages both with and 
without the portion of Lake Erie within the 3 km radius. In both cases, 
the land use analyses indicated that running the AERMOD model in rural 
mode was appropriate.
    The state used a set of nested grids of receptors centered on the 
modeled Lake County facilities. The analysis included a total of 14,680 
receptors. Receptors were placed every 50 meters (m) within 1 km of the 
three facilities, then every 100 m to 2.5 km, and every 250 m out to a 
5 km distance from the facilities. Between 5 and 10 km, a 500-m 
receptor spacing was used, and beyond 10 km from the facilities, 
receptors were placed every 1000 m. Ohio placed receptors along the 
fenceline of these three facilities, and did not place receptors within 
plant property where public access is precluded. EPA requires assessing 
whether violations within plant property may be occurring as the result 
of emissions from other plants in the area. As discussed below in 
Section IV.F, EPA believes that Ohio's submitted modeling results, 
based on modeling without receptors on plant property, are adequate to 
demonstrate that no such violations are occurring.
    Ohio used the AERMAP terrain preprocessor, version 11103, with USGS 
Digital Elevation Data to include terrain heights at the receptor 
locations. EPA finds the model selection and these modeling options 
appropriate.

B. Meteorological Data

    Ohio used five years (2008-2012) of National Weather Service 
meteorological data from Cleveland Hopkins International Airport 
(Station 14820) with upper air data from Buffalo Niagara International 
Airport (Station 14733). This data was processed with AERMINUTE version 
14237 and AERMET version 14134. Cleveland Hopkins International Airport 
is located at the southwestern edge of the city of Cleveland, in 
Cuyahoga County, approximately 45-60 km southwest of the Lake County 
power plants. Lake County borders Cuyahoga County to the northeast. The 
Cleveland surface data adequately represents the typical prevailing 
winds in Lake County, the influences of generally similar topography, 
and the meteorological influence from nearby Lake Erie.
    The upper air station in Buffalo, New York, is also considered to 
be representative of Lake County, Ohio. The Buffalo upper air station 
is about 250 km from Painesville, but it is located at the eastern end 
of Lake Erie and south of Lake Ontario, so it is likely to experience 
upper air meteorological conditions similar to those affecting the Lake 
County SO2 sources near Lake Erie. EPA concurs with the 
choice of these meteorological data sets.
    Ohio used AERSURFACE version 13016 to determine the AERMOD surface 
characteristics of albedo, Bowen ratio, and roughness length, which 
were then input into AERMOD. Ohio used National Land Cover Database 
data from 1992, twelve sectors, and four seasons, including moisture 
conditions at the surface meteorological station which were determined 
from 30-year precipitation data. EPA finds that this procedure for 
preparing the input values for AERMOD surface characteristics is 
acceptable.

C. Modeled Emissions Data

    Ohio considered three significant facilities in Lake County for 
inclusion in the Lake County analysis and attainment demonstration: The 
FirstEnergy Generation, LLC, Eastlake Plant (Eastlake plant), the 
Painesville Municipal Electric Plant (Painesville plant), and Carmeuse 
Lime Grand River Operations (Carmeuse Lime). These three facilities 
were responsible for 98 percent of Lake County's total SO2 
emissions (based on 2011 actual emissions data). The Eastlake plant 
emitted 48,303 tons of SO2 per year (tpy), the Painesville 
plant emitted 2,745 tpy, and Carmeuse Lime emitted 891 tpy. The other 
SO2 sources in Lake County each emitted less than 25 tpy in 
2011, and were not considered likely to have significant concentration 
gradients in the area of analysis. The large sources in nearby counties 
outside Lake County, all of which emitted less than the

[[Page 42240]]

Painesville plant did in 2011, were located more than 35 km from the 
Lake County monitor which had indicated violation. Therefore, these 
sources were considered unlikely to create significant concentration 
gradients in the nonattainment area. In accordance with EPA 
recommendations and regulations at 40 CFR part 51, appendix W, section 
8.3, Ohio used a background concentration to account for the 
contributions of sources not included in the modeling analysis. See 
section IV.E for more discussion of Ohio's determination of background 
concentrations. EPA concurs with Ohio's selection of the sources to 
include in its attainment demonstration.
    The Eastlake plant had five large boilers, but at the time of 
Ohio's analysis, two of those boilers had been retired and were no 
longer emitting SO2. Therefore, Ohio's modeling analysis 
included only the three large boilers which were still operating. Ohio 
determined that the SO2 emission rates for each of the three 
boilers must be reduced from 7,473 lb/hr to 1,158.89 lb/hr in order to 
attain the NAAQS. Although FirstEnergy Generation, LLC later informed 
Ohio that all of the Eastlake plant's large boilers would be shut down 
as of April 16, 2015, Ohio did not revise its modeled attainment 
demonstration to reflect the shutdown of boilers B001, B002, and B003. 
Therefore, the final modeled attainment demonstration Ohio submitted 
for Lake County includes modeled emissions of 1,158.89 lb/hr from the 
Eastlake plant's boilers B001, B002, and B003. After receiving the 
formal notification that the remaining three large boilers at the 
Eastlake plant had been retired and would no longer emit 
SO2, Ohio did, however, revise Eastlake's permit to remove 
references to the retired boilers, and Ohio also removed the emission 
limit SIP rule entry for the Eastlake plant at OAC 3745-18-49(G), as 
the five boiler units previously subject to the rule had all been shut 
down.
    The second facility in Lake County which Ohio included in its 
attainment strategy was the Painesville plant. This facility has three 
boilers (numbered 3, 4 and 5). Boilers 3 and 4 exhaust from a single 
stack, 52 m tall. Boiler 5 exhausts from a separate stack, 47 m tall. 
Ohio's modeling analyses indicated that reductions in the Painesville 
plant's SO2 emissions would also be necessary to attain the 
NAAQS. Ohio determined that attainment would be provided with an hourly 
emission limit of 362.997 lb/hr at Boiler 5, an hourly limit of 430.499 
lb/hr for Boilers 3 and 4, and an additional restriction that only one 
of the three boilers could run on coal at any time. The Lake County 
final cumulative attainment modeling analyses were performed using the 
hourly emission values above.
    The third facility, Carmeuse Lime, was included in the final 
cumulative attainment modeling analysis with emissions of 230 lb/hr at 
Lime kiln #4 and 260 lb/hr at Lime kiln #5. These emission rates 
represent Carmeuse Lime's permitted emission rates. Since it was not 
necessary, Ohio did not revise Carmeuse Lime's emission limits as part 
of its Lake County nonattainment SIP.

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. Because some of the limits that Ohio's plan relies on are 
expressed as 30-day 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 
all of the emission limits in Ohio's plan, and the second subsection 
that follows addresses the 30-day limits.
1. Enforceability
    Ohio's nonattainment plan for Lake County relies on revised 
emission limits for the Painesville plant, existing SO2 
emission limits for Carmeuse Lime, and modeled emission reductions at 
the Eastlake plant which have been supplanted by the permanent emission 
reductions which resulted from the Eastlake plant's boiler retirements. 
The emission limits for Lake County are codified at OAC 3745-18-49. 
Ohio's compliance time schedules and emission measurement methods are 
located in OAC 3745-18-03 and OAC 3745-18-04, respectively. These rules 
were included in Ohio's SIP submittals. Ohio's revised SIP rules were 
properly adopted by the state and will provide for permanent Federal 
enforceability after EPA approves them into the Ohio SO2 
SIP.
    As of April 2015, none of the Eastlake plant's five large boilers 
operate or emit SO2. Ohio has removed these units from the 
Eastlake plant's permit. Ohio also removed the Eastlake plant's 
previous entry at OAC 3745-18-49 (G) from the SO2 rule for 
Lake County, OAC 3745-18-49. This facility is no longer authorized to 
operate its former large boilers, and cannot reinstate them without 
obtaining a new permit under Ohio's New Source Review program. 
Therefore, EPA finds that the reductions in SO2 emissions 
from the boiler closures can be considered permanent, enforceable 
reductions.
    For the Painesville plant, Ohio placed new 30-day and 24-hour 
emission limits in OAC 3745-18-49(F), effective on October 23, 2015, 
and submitted its SIP rule package to EPA. In accordance with EPA 
policy, the 30-day average limit is set at a lower level than the 
hourly emission rate used in the modeled attainment demonstration; the 
relationship between these two values is discussed in more detail in 
the following section.
    In its initial review, EPA identified an issue with the Painesville 
plant's limits and their associated compliance requirements as given in 
Ohio's October 2015 submittal. The method stated in Ohio's rule OAC 
3745-18-04 (D)(10) for calculating compliance with the Painesville 
plant's 30-day emission limits in OAC 3745-18-49 (F) could have been 
interpreted to allow a boiler's non-operating hours to be included in 
its 30-day average heat input calculation. Since OAC 3745-18-49 (F) 
also requires that the Painesville plant's boilers must not operate 
simultaneously, the three boilers may each have a number of non-
operating hours in any given 30-day period. Allowing multiple hours of 
zero heat input to be averaged into the 30-day compliance calculations 
could have had the effect of allowing the boilers to operate frequently 
at heat input rates well in excess of the limit which was developed as 
an equivalent to the short-term limit required for attainment. On 
February 6, 2017, Ohio revised OAC 3745-18-04 (D)(10) to clarify the 
heat input averaging procedure, that compliance shall be determined by 
averaging heat input values only while the boiler operates.
    EPA finds that this revised approach provides acceptable confidence 
that, consistent with EPA's policy on longer-term average limits, 
occasions with emissions above the otherwise applicable 1-hour limit 
will be infrequent and of moderate magnitude. As discussed further 
below, with these revisions, EPA finds that the revised rule assures 
that the Painesville plant's 30-day emission limits now appropriately 
correspond to the 1-hour emission limits Ohio demonstrated to be 
protective of the NAAQS. Therefore, EPA proposes to conclude that the 
revised rules for the Painesville plant are acceptable.

[[Page 42241]]

2. Longer-Term Average Limits
    Ohio's revised SIP includes emission limits for the Painesville 
plant which require compliance based on a thirty-operating-day average 
of one-hour emission rates. This longer-term averaged limit provides 
operating flexibility for the facility while continuing to maintain the 
NAAQS. The 30-day SO2 limits are 340 lb/hr each for Boilers 
3 and 4 and 287 lb/hr for Boiler 5. These limits are numerically more 
stringent than the modeled 1-hour emission rates which were 
demonstrated to provide for attainment. The increased stringency is 
intended to account for potential fluctuations in hourly emissions 
which may occur while the facility remains in compliance with its 
limits over the longer averaging time. Ohio also included a 
supplemental short-term (24-hour) limit on the facility's overall 
boiler operating rates of 249 million British Thermal Units per hour 
(MMBtu/hr) in any calendar day. EPA finds that this supplemental limit 
acts to reduce the occurrence of high, short-lived SO2 
emission events and thereby provides additional assurance that this set 
of limits will provide for attainment in this area.
    Ohio calculated the Painesville plant's 30-day emission limits in 
accordance with EPA's recommended method. See section III. Ohio used 
dispersion modeling to determine a 1-hour critical emission value for 
each boiler which would provide for attainment of the NAAQS. These 
critical 1-hour values necessary for modeled attainment were 430.499 
for Boilers 3 and 4 and 362.997 lb/hr at Boiler 5. Ohio then applied 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 critical 1-hour emission value. Ohio was not able to 
calculate a source-specific adjustment factor for the Painesville 
plant, due to the facility's expected operations. The Painesville plant 
has accepted enforceable operating limits which will meet the Federal 
Boiler Maximum Achievable Control Technology (MACT) \7\ Limited Use 
definition. Under this enforceable restriction to a 10 percent annual 
operating capacity factor, which Ohio has codified at OAC 3745-18-49 
(F)(7), the facility will only operate intermittently, during periods 
of high demand or interrupted service. Hourly SO2 emissions 
data representing these intermittent operations were not available for 
use in calculating a source-specific emission ratio. Instead, Ohio used 
the national average ratio of 0.79 for sources with no control 
equipment, which is given in Table 1 of appendix D of EPA's guidance. 
The Painesville plant does not anticipate installing additional control 
technology, as such technology often cannot be consistently effective 
for sources which operate intermittently rather than continually. EPA 
concurs that the appendix D ratio is an acceptable adjustment factor 
for use in calculating a long-term average emission limit that is 
comparably stringent to the 1-hour limit at the critical emission value 
that would otherwise be set for the Painesville plant. Ohio calculated 
that appropriately stringent 30-day SO2 limits would be 340 
lb/hr each for Boilers 3 and 4 and 287 lb/hr for Boiler 5.
---------------------------------------------------------------------------

    \7\ Information about the boiler MACT is available at https://www.epa.gov/stationary-sources-air-pollution/boiler-maximum-achievable-control-technology-mact-40-cfr-part-63.
---------------------------------------------------------------------------

    After reviewing the state's 2015 and 2017 submittals, EPA concurs 
that the 30-day-average limits for the Painesville plant in OAC 3745-
18-49 (F), as amended effective February 16, 2017, and as supplemented 
by the 24-hour operation level restriction, provide an acceptable 
alternative to establishing a 1-hour average emission limit for this 
source. The state has used suitable data in an appropriate manner and 
has applied an appropriate adjustment, yielding an emission limit that 
has comparable stringency to the 1-hour average limit that the state 
determined would otherwise have been necessary to provide for 
attainment. While the 30-day-average limit can allow occasions in which 
emissions may be higher than the level that would be allowed with the 
1-hour limit, the state's limit compensates 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 Ohio's plan, EPA proposes to conclude that the 30-day-
average limit for the Painesville plant, in combination with other 
limitations in the state's plan, will provide for attainment of the 
NAAQS.

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 
sources 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 Lake County attainment demonstration, Ohio used a 
background concentration of 10.3 ppb. This value was based on 2008-2012 
monitored data at the Eastlake monitor (39-085-0003), which is located 
1 km east of the Eastlake plant, 15 km west southwest of the 
Painesville and Carmeuse Lime plants, and 8 km northeast of the 
Cuyahoga County/Lake County border. This monitor is expected to be 
reasonably representative of SO2 emissions coming into Lake 
County from all directions, including from Cuyahoga and Lorain Counties 
to the west, the city of Cleveland, and SO2 emissions from 
small sources in Lake County which were not explicitly modeled. This 
monitor is expected to reflect the emissions of the nearby Eastlake 
plant as well.
    Since the Eastlake plant's emissions were specifically input into 
the model for Lake County's attainment demonstration, Ohio selected a 
20-degree sector for which the monitor's readings are expected to be 
primarily due to the Eastlake plant's emissions. Monitored values 
measured when winds were blowing from this 20-degree wind sector were 
not included in Ohio's determination of a background concentration for 
the Lake County analysis. Using the remaining monitored data, Ohio 
calculated that a background value of 10.3 ppb would account for the 
significant power plant emission reductions which were expected to 
occur in Cuyahoga and Lorain Counties over the next few years. Although 
EPA generally recommends against projecting future background 
concentrations, the monitoring data that have subsequently become 
available indicate that Ohio's estimates of applicable background 
concentrations have proven to be appropriate. EPA notes that the most 
recent years' 99th percentile values measured at the Eastlake monitor 
are 10 ppb for 2016 and 5 ppb for 2017, which are lower than Ohio's 
background estimate. Therefore, EPA finds that the

[[Page 42242]]

background concentration value used by Ohio is reasonable.

F. Summary of Results

    Ohio's attainment modeling analyses resulted in a predicted 1-hour 
design value of 196.2 micrograms per cubic meter ([micro]g/m\3\), or 
74.9 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 less than one kilometer from the Eastlake 
plant. The modeled analysis shows attainment even including the no-
longer-allowable emissions from the Eastlake plant's three retired 
boilers, which offers additional assurance that the final SIP emission 
limitations in Ohio's revised rule OAC 3745-18-49 are adequate to 
protect the SO2 NAAQS in Lake County.
    EPA policy also requires that one facility must not cause or 
contribute to exceedances of the NAAQS on another facility's property. 
Ohio's final submittal does not specifically address the impacts of 
each modeled facility within the plant property boundaries of the other 
modeled facilities, but the final modeled results indicate that no 
facility is causing or contributing to violations within another 
facility's property. The maximum impacts from each facility alone 
occurred within a kilometer of its own fenceline. The two closest 
facilities, Carmeuse Lime and the Painesville plant, are almost 4 km 
from each other. With maximum impacts below the NAAQS and decreasing 
with distance, EPA finds Ohio's submitted modeling results to provide 
adequate evidence that no facility or combination of facilities is 
causing or contributing to violations on another facility's property.
    EPA concurs with the results of Ohio's analysis and proposes to 
conclude that Ohio has demonstrated that its revised emission limits 
are adequate to provide for attainment and maintenance of the 2010 
SO2 NAAQS.

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 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 52,155.57 tpy for all six 
categories. Reflecting growth and known, planned, point source emission 
reductions, the 2018 future year inventory projection totaled 3,322.31 
tpy. To maintain conservatism, Ohio did not apply a population growth 
factor to the EGU and non-EGU categories, although the population in 
Lake County is expected to decline from 2010 to 2020.
    Emissions from the non-EGU facilities which were not required to 
reduce emissions under the Lake County SO2 nonattainment 
plan were projected to remain constant between 2011 and 2018. The EGU 
category of this emissions inventory only contains the Eastlake plant. 
(The Painesville plant, while an electric generating facility, does not 
meet the definition of an EGU, and its emissions and projected 
reductions are included in the non-EGU category.) The 2011 EGU 
inventory included six emission sources at the Eastlake plant (five 
large boilers and one lower-emission turbine), totaling 48,303.10 tpy. 
Ohio's projected 2018 EGU inventory accounted for the closure of two of 
the Eastlake plant's five large boilers and the emission reductions 
which Ohio's modeling analysis initially indicated would be necessary 
at the Eastlake plant to provide for attainment of the NAAQS, resulting 
in projected total emissions of 1,659.53 tpy. Ohio's submitted 2018 
projected inventory did not account for the retirement of the Eastlake 
plant's remaining three large boilers, which occurred in April 2015. 
This boiler retirement would have been expected to reduce Ohio's EGU 
projection by an additional 1657 tpy, and in that case Ohio's total 
six-category 2018 projected year inventory would be 1,665 tpy.
    Ohio's projected inventory indicates that SO2 emissions 
will be significantly and permanently reduced in Lake County as of the 
SO2 NAAQS attainment year. EPA concurs and proposes to 
conclude that Ohio has satisfied the emissions inventory requirement.

B. Reasonably Available Control Measures and Technology

    Section 172(c)(1) of the CAA requires states to adopt and submit 
all RACM, including reasonably available control technology (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's plan for attaining the 1-hour SO2 NAAQS in 
Lake County is based on emission reductions at the Eastlake and 
Painesville plants, and Ohio has demonstrated that emission limitations 
for these plants will result in attainment of the NAAQS.
    While Ohio's demonstration included emission reductions from the 
Eastlake plant, Ohio did not include SO2 limits for the 
Eastlake plant in the final SIP rule package, because during Ohio's 
attainment planning and rulemaking process, the Eastlake plant 
announced the retirement of its three remaining large boilers, which 
would reduce the plant's SO2 emissions to below the intended 
limits. The reductions are permanent, as the large boilers are no 
longer included in the Eastlake plant's Title V permit. To reinstate 
them would require new source review analysis and potentially 
additional emission controls to maintain SO2 attainment in 
Lake County. Therefore, EPA concurs that the Eastlake plant's boiler 
SO2 emissions are currently zero and RACT requirements are 
satisfied at this source.\8\
---------------------------------------------------------------------------

    \8\ Although Ohio's modeling demonstrates that the area would 
attain even if these units at the Eastlake plant had nonzero 
emissions, the plan should be considered to require these units to 
be shut down, and the satisfaction of the RACM/RACT requirement is 
being judged accordingly.
---------------------------------------------------------------------------

    Ohio's plan includes new emission limits at the Painesville plant 
and requires timely compliance. Ohio has determined that these measures 
suffice to provide for timely attainment. EPA concurs and proposes to 
conclude 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

    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).

[[Page 42243]]

Ohio's new source rules, codified at OAC 3745-31, provide for 
appropriate new source review for SO2 sources undergoing 
construction or major modification in Lake County without need for 
modification of the approved rules. EPA concurs and proposes to 
conclude that this requirement has been met for this area.

D. Reasonable Further Progress

    Section 172 of the CAA requires Ohio's Lake County 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 finds that the state's revised limits 
for the Painesville plant and the 2015 retirement of the Eastlake 
plant's boilers represent implementation of control measures as 
expeditiously as practicable. Accordingly, EPA proposes to conclude 
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. Ohio's SIP Rules

    On March 13, 2017, Ohio submitted revisions to its rule OAC 3745-
18, which contains the state's sulfur dioxide emission regulations. 
This submittal consisted of SO2 regulations which apply 
statewide and SO2 regulations specific to certain Ohio 
counties and facilities, which include regulations pertinent to Ohio's 
SO2 nonattainment areas. Certain portions of OAC 3745-18 are 
specifically pertinent to Ohio's Lake County nonattainment SIP. These 
are OAC 3745-18-03 (B)(9), OAC 3745-18-03 (C)(11), OAC 3745-18-
04(D)(10), and OAC 3745-18-49. EPA finds acceptable and proposes to 
approve these four revised rules as part of Ohio's SO2 
nonattainment plan for Lake County. The remainder of the OAC 3745-18 
rule revisions submitted on March 13, 2017, will be addressed in a 
subsequent rulemaking action.

VII. 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 Lake County SO2 
nonattainment area. This SO2 nonattainment plan, which the 
state submitted to EPA on April 3, 2015, and supplemented on October 
13, 2015, and on March 13, 2017, includes Ohio's attainment 
demonstration for the Lake County nonattainment area and addresses the 
CAA requirements for reasonable further progress, RACM/RACT, base-year 
and projection-year emission inventories, enforceable emission 
limitations and control measures, and contingency measures. EPA is 
proposing to approve Ohio's rules OAC 3745-18-03 (B)(9), OAC 3745-18-03 
(C)(11), OAC 3745-18-04(D)(10), and OAC 3745-18-49, which became 
effective on February 16, 2017, and were submitted to EPA by Ohio on 
March 13, 2017.
    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 Lake County by the applicable 
attainment date and that the plan meets the other applicable 
requirements of sections 110, 172 and 192 of the CAA. EPA is therefore 
proposing to approve Ohio's nonattainment plan for Lake County.

VIII. 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 OAC 3745-18-03 (B)(9), OAC 3745-18-03 (C)(11), OAC 3745-18-
04(D)(10), and OAC 3745-18-49, effective on February 16, 2017. 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).

IX. 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 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 (Public Law 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 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

[[Page 42244]]

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: August 2, 2018.
Cathy Stepp,
Regional Administrator, Region 5.
[FR Doc. 2018-17930 Filed 8-20-18; 8:45 am]
BILLING CODE 6560-50-P