83_FR_32741 83 FR 32606 - Approval and Promulgation of Air Quality Implementation Plans; Pennsylvania; Attainment Plan for the Indiana, Pennsylvania Nonattainment Area for the 2010 Sulfur Dioxide Primary National Ambient Air Quality Standard

83 FR 32606 - Approval and Promulgation of Air Quality Implementation Plans; Pennsylvania; Attainment Plan for the Indiana, Pennsylvania Nonattainment Area for the 2010 Sulfur Dioxide Primary National Ambient Air Quality Standard

ENVIRONMENTAL PROTECTION AGENCY

Federal Register Volume 83, Issue 135 (July 13, 2018)

Page Range32606-32615
FR Document2018-14947

The Environmental Protection Agency (EPA) is proposing to approve a state implementation plan (SIP) revision, submitted by the Commonwealth of Pennsylvania through the Pennsylvania Department of Environmental Protection (PADEP), to EPA on October 11, 2017, for the purpose of providing for attainment of the 2010 sulfur dioxide (SO<INF>2</INF>) primary national ambient air quality standard (NAAQS) in the Indiana, Pennsylvania SO<INF>2</INF> nonattainment area (hereafter referred to as the ``Indiana Area'' or ``Area''). The Indiana Area is comprised of Indiana County and a portion of Armstrong County (Plumcreek Township, South Bend Township, and Elderton Borough) in Pennsylvania. The major sources of SO<INF>2</INF> in the Indiana Area emitting over 2,000 tpy of SO<INF>2</INF> include several large electric generating units (EGUs): Keystone Plant, Conemaugh Plant, Homer City Generation, and Seward Generation Station (hereafter referred to as ``Keystone,'' ``Conemaugh,'' ``Homer City,'' and ``Seward''). The SIP submission is an attainment plan which includes the base year emissions inventory, an analysis of the reasonably available control technology (RACT) and reasonably available control measure (RACM) requirements, enforceable emission limitations and control measures, a reasonable further progress (RFP) plan, a modeling demonstration of SO<INF>2</INF> attainment, and contingency measures for the Indiana Area. As part of approving the attainment plan, EPA is also proposing to approve into the Pennsylvania SIP SO<INF>2</INF> emission limits and associated compliance parameters for Keystone, Conemaugh, Homer City and Seward and proposes to find Pennsylvania has measures in place to address nonattainment new source review. EPA proposes to approve Pennsylvania's attainment plan and concludes that the Indiana Area will attain the 2010 1-hour primary SO<INF>2</INF> NAAQS by the applicable attainment date and that the plan meets all applicable requirements under the Clean Air Act (CAA).

Federal Register, Volume 83 Issue 135 (Friday, July 13, 2018)
[Federal Register Volume 83, Number 135 (Friday, July 13, 2018)]
[Proposed Rules]
[Pages 32606-32615]
From the Federal Register Online  [www.thefederalregister.org]
[FR Doc No: 2018-14947]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R03-OAR-2017-0615; FRL-9980-65-Region 3]


Approval and Promulgation of Air Quality Implementation Plans; 
Pennsylvania; Attainment Plan for the Indiana, Pennsylvania 
Nonattainment Area for the 2010 Sulfur Dioxide Primary National Ambient 
Air Quality Standard

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, submitted by the 
Commonwealth of Pennsylvania through the Pennsylvania Department of 
Environmental Protection (PADEP), to EPA on October 11, 2017, for the 
purpose of providing for attainment of the 2010 sulfur dioxide 
(SO2) primary national ambient air quality standard (NAAQS) 
in the Indiana, Pennsylvania SO2 nonattainment area 
(hereafter referred to as the ``Indiana Area'' or ``Area''). The 
Indiana Area is comprised of Indiana County and a portion of Armstrong 
County (Plumcreek Township, South Bend Township, and Elderton Borough) 
in Pennsylvania. The major sources of SO2 in the Indiana 
Area emitting over 2,000 tpy of SO2 include several large 
electric generating units (EGUs): Keystone Plant, Conemaugh Plant, 
Homer City Generation, and Seward Generation Station (hereafter 
referred to as ``Keystone,'' ``Conemaugh,'' ``Homer City,'' and 
``Seward''). The SIP submission is an attainment plan which includes 
the base year emissions inventory, an analysis of the reasonably 
available control technology (RACT) and reasonably available control 
measure (RACM) requirements, enforceable emission limitations and 
control measures, a reasonable further progress (RFP) plan, a modeling 
demonstration of SO2 attainment, and contingency measures 
for the Indiana Area. As part of approving the attainment plan, EPA is 
also proposing to approve into the Pennsylvania SIP SO2 
emission limits and associated compliance parameters for Keystone, 
Conemaugh, Homer City and Seward and proposes to find Pennsylvania has 
measures in place to address nonattainment new source review. EPA 
proposes to approve Pennsylvania's attainment plan and concludes that 
the Indiana Area will attain the 2010 1-hour primary SO2 
NAAQS by the applicable attainment date and that the plan meets all 
applicable requirements under the Clean Air Act (CAA).

DATES: Written comments must be received on or before August 13, 2018.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R03-
OAR-2017-0615 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: Megan Goold, (215) 814-2027, or by 
email at [email protected].

SUPPLEMENTARY INFORMATION:

Table of Contents

I. Background for EPA's Proposed Action
II. Pennsylvania's Attainment Plan Submittal for the Indiana Area
III. EPA's Analysis of Pennsylvania's Attainment Plan for the 
Indiana Area
    A. Pollutants Addressed
    B. Emissions Inventory Requirements
    C. Air Quality Modeling
    D. RACM/RACT
    E. RFP Plan
    F. Contingency Measures
    G. New Source Review
IV. EPA's Proposed Action
V. Incorporation by Reference
VI. Statutory and Executive Order Reviews

I. Background for EPA's Proposed Action

    On June 2, 2010, the EPA Administrator signed a final rule 
establishing a new primary SO2 NAAQS as a 1-hour standard of 
75 parts per billion (ppb), based on a 3-year average of the annual 
99th percentile of daily maximum 1-hour average concentrations. See 75 
FR 35520 (June 22, 2010), codified at 40 CFR 50.17. This action also 
revoked the existing 1971 primary annual and 24-hour standards, subject 
to certain conditions.\1\ EPA established the NAAQS based on 
significant evidence and numerous health studies demonstrating that 
serious health effects are associated with short-term exposures to 
SO2 emissions ranging from five minutes to 24 hours with an 
array of adverse respiratory effects including narrowing of the airways 
which can cause difficulty breathing (bronchoconstriction) and 
increased asthma symptoms. For more information regarding the health 
impacts of SO2, please refer to the June 22, 2010 final 
rulemaking. See 75 FR 35520. Following promulgation of a new or revised 
NAAQS, EPA is required by the CAA to designate areas throughout the 
United States as attaining or not attaining the NAAQS; this designation 
process is described in section 107(d)(1)-(2) of the CAA. On August 5, 
2013, EPA promulgated initial air quality designations for 29 areas for 
the 2010 SO2 NAAQS (78 FR 47191), which

[[Page 32607]]

became effective on October 4, 2013, based on violating air quality 
monitoring data for calendar years 2009-2011, where there were 
sufficient data to support a nonattainment designation.\2\
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    \1\ EPA's June 22, 2010 final action revoked the two 1971 
primary 24-hour standard of 140 ppb and the annual standard of 30 
ppb because they were determined not to add additional public health 
protection given a 1-hour standard at 75 ppb. See 75 FR 35520. 
However, the secondary 3-hour SO2 standard was retained. 
Currently, the 24-hour and annual standards are only revoked for 
certain of those areas the EPA has already designated for the 2010 
1-hour SO2 NAAQS. See 40 CFR 50.4(e).
    \2\ EPA is continuing its designation efforts for the 2010 
SO2 NAAQS. Pursuant to a court-order finalized March 2, 
2015, in the U.S. District Court for the Northern District of 
California, EPA must complete the remaining designations for the 
rest of the country on a schedule that contains three specific 
deadlines. Sierra Club, et al. v. Environmental Protection Agency, 
13-cv-03953-SI (2015).
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    Effective on October 4, 2013, the Indiana Area was designated as 
nonattainment for the 2010 SO2 NAAQS for an area that 
encompasses the primary SO2 emitting sources of Keystone, 
Conemaugh, Homer City, and Seward. The October 4, 2013 final 
designation triggered a requirement for Pennsylvania to submit by April 
4, 2015, a SIP revision with an attainment plan for how the Area would 
attain the 2010 SO2 NAAQS as expeditiously as practicable, 
but no later than October 4, 2018, in accordance with CAA sections 
172(c) and 191-192.
    For a number of areas, including the Indiana Area, EPA published a 
notice on March 18, 2016, effective April 18, 2016, that Pennsylvania 
and other pertinent states had failed to submit the required 
SO2 attainment plan by this submittal deadline. See 81 FR 
14736. This finding initiated a deadline under CAA section 179(a) for 
the potential imposition of new source review and highway funding 
sanctions. However, pursuant to Pennsylvania's submittal of October 11, 
2017, and EPA's subsequent letter dated October 13, 2017, to 
Pennsylvania finding the submittal complete and noting the stopping of 
the sanctions' deadline, these sanctions under section 179(a) will not 
be imposed as a consequence of Pennsylvania having missed the April 4, 
2015 deadline. Additionally, under CAA section 110(c), the March 18, 
2016, finding triggered a requirement that EPA promulgate a federal 
implementation plan (FIP) within two years of the effective date of the 
finding unless, by that time, the state has made the necessary complete 
submittal and EPA has approved the submittal as meeting applicable 
requirements. This FIP obligation will no longer apply if and when EPA 
makes final the approval action proposed here.
    Attainment plans must meet the applicable requirements of the CAA, 
and specifically CAA sections 172, 191, and 192. The required 
components of an attainment plan submittal are listed in section 172(c) 
of Title 1, part D of the CAA. 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 13545-49, 13567-68.
    On April 23, 2014, EPA issued recommended guidance (hereafter 2014 
SO2 Nonattainment Guidance) for how state submissions could 
address the statutory requirements for SO2 attainment 
plans.\3\ In this guidance, EPA described the statutory requirements 
for an attainment plan, which include: An accurate base year emissions 
inventory of current emissions for all sources of SO2 within 
the nonattainment area (172(c)(3)); an attainment demonstration that 
includes a modeling analysis showing that the enforceable emissions 
limitations and other control measures taken by the state will provide 
for expeditious attainment of the NAAQS (172(c) and (c)(6)); 
demonstration of RFP (172(c)(2)); implementation of RACM, including 
RACT (172(c)(1)); new source review (NSR) requirements (172(c)(5)); and 
adequate contingency measures for the affected area (172(c)(9)). A 
synopsis of these requirements is also provided in the notice of 
proposed rulemaking on the Illinois SO2 nonattainment plans, 
published on October 5, 2017 at 82 FR 46434.
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    \3\ See ``Guidance for 1-Hour SO2 Nonattainment Area 
SIP Submissions'' (April 23, 2014), available at https://www.epa.gov/sites/production/files/2016-06/documents/20140423guidance_nonattainment_sip.pdf.
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    In order for the 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, the 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.
    CAA section 172(c)(1) directs states with areas designated as 
nonattainment to demonstrate that the submitted plan provides for 
attainment of the NAAQS. 40 CFR part 51, subpart G further delineates 
the control strategy requirements that SIPs must meet, and EPA has long 
required that all SIPs and control strategies reflect four fundamental 
principles of quantification, enforceability, replicability, and 
accountability (General Preamble, at 13567-68). SO2 
attainment plans must consist of two components: (1) Emission limits 
and other control measures that assure implementation of permanent, 
enforceable and necessary emission controls, and (2) a modeling 
analysis which meets the requirements of 40 CFR part 51, Appendix W 
which demonstrates that these emission limits and control measures 
provide for timely attainment of the primary SO2 NAAQS as 
expeditiously as practicable, but by no later than the attainment date 
for the affected area. In all cases, the emission limits and control 
measures must be accompanied by appropriate methods and conditions to 
determine compliance with the respective emission limits and control 
measures and must be quantifiable (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 Nonattainment Guidance recommends that 
the emission limits established for the attainment demonstration be 
expressed as short-term average limits (e.g., addressing emissions 
averaged over one or three hours), but also describes the option to 
utilize emission limits with longer averaging times of up to 30 days so 
long as the state meets various suggested criteria. See 2014 
SO2 Nonattainment Guidance, pp. 22 to 39. The guidance 
recommends that--should states and sources utilize longer averaging 
times--the longer term

[[Page 32608]]

average limit should be set at an adjusted level that reflects a 
stringency comparable to the 1-hour average limit at the critical 
emission value shown to provide for attainment that the plan otherwise 
would have set.
    The 2014 SO2 Nonattainment 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 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. 22-39, and Appendices 
B, C, and D.
    As specified in 40 CFR 50.17(b), the 1-hour primary SO2 
NAAQS is met at an ambient air quality monitoring site when the 3-year 
average of the annual 99th percentile of daily maximum 1-hour average 
concentrations is less than or equal to 75 ppb. In a year with 365 days 
of valid monitoring data, the 99th percentile would be the fourth 
highest daily maximum 1-hour value. The 2010 SO2 NAAQS, 
including this form of determining compliance with the standard, was 
upheld by the U.S. Court of Appeals for the District of Columbia 
Circuit in Nat'l Envt'l Dev. Ass'n's Clean Air Project v. EPA, 686 F.3d 
803 (D.C. Cir. 2012). Because the standard has this form, a single 
exceedance does not create a violation of the standard. Instead, at 
issue is whether a source operating in compliance with a properly set 
longer term average could cause exceedances, and if so the resulting 
frequency and magnitude of such exceedances, and in particular, whether 
EPA can have reasonable confidence that a properly set longer term 
average limit will provide that the average fourth highest daily 
maximum value will be at or below 75 ppb. A synopsis of how EPA 
evaluates whether such plans ``provide for attainment,'' based on 
modeling of projected allowable emissions and in light of the NAAQS' 
form for determining attainment at monitoring sites follows.
    For SO2 attainment plans based on 1-hour emission 
limits, the standard approach is to conduct modeling using fixed 
emission rates. The maximum modeled emission rate that results in 
attainment is labeled the ``critical emission value.'' The modeling 
process for identifying this critical emission value inherently 
considers the numerous variables that affect ambient concentrations of 
SO2, such as meteorological data, background concentrations, 
and topography. In the standard approach, the state would then provide 
for attainment by setting a continuously applicable 1-hour emission 
limit at this critical emission value.
    EPA recognizes that some sources have highly variable emissions, 
for example due to variations in fuel sulfur content and operating 
rate, that can make it extremely difficult, even with a well-designed 
control strategy, to ensure in practice that emissions for any given 
hour do not exceed the critical emission value. EPA also acknowledges 
the concern that longer term emission limits can allow short periods 
with emissions above the ``critical emission value,'' which, if 
coincident with meteorological conditions conducive to high 
SO2 concentrations, could in turn create the possibility of 
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 (and inherent level of emissions 
variability) 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,'' \4\ 
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 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.
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    \4\ 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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    To illustrate this point, EPA conducted a statistical analysis 
using a range of scenarios using actual plant data. The analysis is 
described in Appendix B of EPA's 2014 SO2 Nonattainment 
Guidance. Based on the analysis described in its 2014 SO2 
Nonattainment 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 this 
result can be expected to occur.
    The question then becomes whether this approach, which is likely to 
produce a lower number of overall exceedances even though it may 
produce some unexpected exceedances above the critical emission value, 
meets the requirement in section 110(a)(1) and 172(c)(1) for SIPs to 
``provide for

[[Page 32609]]

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 attainment plan to fail 
and unexpectedly not result in attainment, for example if meteorology 
occurs that is more conducive to poor air quality than was anticipated 
in the plan. Therefore, in determining whether a plan meets the 
requirement to provide for attainment, EPA's task is commonly to judge 
not whether the plan provides absolute certainty that attainment will 
in fact occur, but rather whether the plan provides an adequate level 
of confidence of prospective NAAQS attainment. From this perspective, 
in evaluating use of a 30-day average limit, EPA must weigh the likely 
net effect on air quality. Such an evaluation must consider the risk 
that occasions with meteorology conducive to high concentrations will 
have elevated emissions leading to exceedances that would not otherwise 
have occurred, and must also weigh the likelihood that the requirement 
for lower emissions on average will result in days not having 
exceedances that would have been expected with emissions at the 
critical emissions value. Additional policy considerations, such as in 
this case the desirability of accommodating real world emissions 
variability without significant risk of violations, are also 
appropriate factors for EPA to consider when evaluating 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 Nonattainment 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 (i.e., 
using 1-hour historical emission values from the emissions database to 
calculate 30-day average emission values). 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 (critical 
emission value) to determine a longer term average emission limit that 
may be considered comparably stringent.\5\
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    \5\ For example, if the critical emission value is 1000 pounds 
of SO2 per hour, and a suitable adjustment factor is 
determined to be 70 percent, the recommended longer term average 
limit would be 700 pounds per hour.
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    The 2014 SO2 Nonattainment 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.
    Preferred air quality models for use in regulatory applications are 
described in Appendix A of the EPA's Guideline on Air Quality Models 
(40 CFR part 51, appendix W).\6\ In 2005, the 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 Guidance. 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\ The 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, the EPA believes that 
dispersion modeling, using allowable emissions and addressing 
stationary sources in the affected area (and in some cases those 
sources located outside the nonattainment area which may affect 
attainment in the area) is technically appropriate, efficient and 
effective in demonstrating attainment in nonattainment areas because it 
takes into consideration combinations of meteorological and emission 
source operating conditions that may contribute to peak ground-level 
concentrations of SO2.
    The meteorological data used in the analysis should generally be 
processed with the most recent version of AERMET. Estimated 
concentrations should include ambient background concentrations, should 
follow the form of the standard, and should be calculated as described 
in section 2.6.1.2 of the August 23, 2010 clarification memo on 
``Applicability of Appendix W Modeling Guidance for the 1-hr 
SO2 National Ambient Air Quality Standard'' (U.S. EPA, 
2010a).

II. Pennsylvania's Attainment Plan Submittal for the Indiana Area

    In accordance with section 172(c) of the CAA, the Pennsylvania 
attainment plan for the Indiana Area includes: (1) An emissions 
inventory for SO2 for the plan's base year (2011); and (2) 
an attainment demonstration. The attainment demonstration includes the 
following: Analyses that locate, identify, and quantify sources of 
emissions contributing to violations of the 2010 SO2 NAAQS; 
a determination that the control strategy for the primary 
SO2 sources within the nonattainment areas constitutes RACM/
RACT; a dispersion modeling analysis of an emissions control strategy 
for the primary SO2 sources (Keystone, Conemaugh, Homer 
City, and Seward), showing attainment of the SO2 NAAQS by 
the October 4, 2018, attainment date; requirements for RFP toward 
attaining the SO2 NAAQS in the Area; contingency measures; 
the assertion that Pennsylvania's existing SIP-approved NSR program 
meets the applicable requirements for SO2; and the request 
that emission limitations

[[Page 32610]]

and compliance parameters for Keystone, Conemaugh, Homer City, and 
Seward be incorporated into the SIP.

III. EPA's Analysis of Pennsylvania's Attainment Plan for the Indiana 
Area

    Consistent with CAA requirements (see section 172), an attainment 
demonstration for an SO2 nonattainment area must include a 
showing that the area will attain the 2010 SO2 NAAQS as 
expeditiously as practicable. The demonstration must also meet the 
requirements of 40 CFR 51.112 and 40 CFR part 51, Appendix W, and 
include inventory data, modeling results, and emissions reductions 
analyses on which the state has based its projected attainment. EPA is 
proposing that the attainment plan submitted by Pennsylvania meets all 
applicable requirements of the CAA, and EPA is proposing to approve the 
plan submitted by Pennsylvania to ensure ongoing attainment in the 
Indiana Area.

A. Pollutants Addressed

    Pennsylvania's SO2 attainment plan evaluates 
SO2 emissions for the Indiana Area comprised of Indiana 
County and a portion of Armstrong County (Plumcreek Township, South 
Bend Township, and Elderton Borough) that is designated nonattainment 
for the 2010 SO2 NAAQS. There are no precursors to consider 
for the SO2 attainment plan. SO2 is a pollutant 
that arises from direct emissions, and therefore concentrations are 
highest relatively close to the sources and much lower at greater 
distances due to dispersion. Thus, SO2 concentration 
patterns resemble those of other directly emitted pollutants like lead, 
and differ from those of photochemically-formed (secondary) pollutants 
such as ozone. Pennsylvania's attainment plan appropriately considered 
SO2 emissions for the Indiana Area.

B. Emissions Inventory Requirements

    States are required under section 172(c)(3) of the CAA to develop 
comprehensive, accurate and current emissions inventories of all 
sources of the relevant pollutant or pollutants in the nonattainment 
area. These inventories provide detailed accounting of all emissions 
and emissions sources by precursor or pollutant. In addition, 
inventories are used in air quality modeling to demonstrate that 
attainment of the NAAQS is as expeditious as practicable. The 
SO2 Nonattainment Guidance provides that the emissions 
inventory should be consistent with the Air Emissions Reporting 
Requirements (AERR) at Subpart A to 40 CFR part 51.\7\
---------------------------------------------------------------------------

    \7\ The AERR at Subpart A to 40 CFR part 51 cover overarching 
federal reporting requirements for the states to submit emissions 
inventories for criteria pollutants to EPA's Emissions Inventory 
System. EPA uses these submittals, along with other data sources, to 
build the National Emissions Inventory.
---------------------------------------------------------------------------

    For the base year inventory of actual emissions, a ``comprehensive, 
accurate and current'' inventory can be represented by a year that 
contributed to the three-year design value used for the original 
nonattainment designation. The 2014 SO2 Nonattainment 
Guidance notes that the base year inventory should include all sources 
of SO2 in the nonattainment area as well as any sources 
located outside the nonattainment area which may affect attainment in 
the area. Pennsylvania appropriately elected to use 2011 as the base 
year as the designation of nonattainment was based on data from 2009-
2011. Actual emissions from all the sources of SO2 in the 
Indiana Area were reviewed and compiled for the base year emissions 
inventory requirement. The primary SO2-emitting point 
sources located within the Indiana Area are Keystone, Conemaugh, Homer 
City, and Seward, all coal-fired power plants. Keystone and Conemaugh 
each have two pulverized coal-fired (PC) boilers; Homer City has three 
coal-fired boilers; and Seward has two circulating fluidized bed (CFB) 
waste coal-fired boilers. More information about the emissions 
inventory for the Indiana Area (and analysis of the inventory) can be 
found in Pennsylvania's October 11, 2017, submittal as well as EPA's 
emissions inventory Technical Support Document (TSD), which can be 
found under Docket ID No. EPA-R03-OAR-2017-0615 and online at 
www.regulations.gov.
    Table 1 shows the level of emissions, expressed in tons per year 
(tpy), in the Indiana Area for the 2011 base year by emissions source 
category. The point source category includes all sources within the 
Area.

  Table 1--2011 Base Year SO2 Emissions Inventory for the Indiana Area
------------------------------------------------------------------------
                                                          SO2 Emissions
                Emission source category                      (tpy)
 
------------------------------------------------------------------------
Point..................................................      144,269.017
Area...................................................          555.610
Non-road...............................................            1.025
On-road................................................            7.730
Total..................................................      144,833.382
------------------------------------------------------------------------

    EPA has evaluated Pennsylvania's 2011 base year emissions inventory 
for the Indiana Area and has made the preliminary determination that 
this inventory was developed in a manner consistent with EPA's 
guidance. Therefore, pursuant to section 172(c)(3), EPA is proposing to 
approve Pennsylvania's 2011 base year emissions inventory for the 
Indiana Area as it meets CAA requirements.
    The attainment demonstration also provides for a projected 
attainment year inventory that includes estimated emissions for all 
emission sources of SO2 which are determined to impact the 
nonattainment area for the year in which the area is expected to attain 
the NAAQS. Pennsylvania provided a 2018 projected emissions inventory 
for all known sources included in the 2011 base year inventory. The 
projected 2018 emissions are shown in Table 2. Pennsylvania's submittal 
asserts that the SO2 emissions are expected to decrease by 
approximately 75,340 tons, or 40%, by 2018 from the 2011 base year. 
More information about the projected emissions for the Indiana Area can 
be found in Pennsylvania's October 11, 2017, submittal which can be 
found under Docket ID No. EPA-R03-OAR-2017-0615 and online at 
www.regulations.gov.

  Table 2--2018 Anticipated Actual Projected SO2 Emission Inventory for
                            the Indiana Area
------------------------------------------------------------------------
                                                          SO2 Emissions
                Emission source category                      (tpy)
 
------------------------------------------------------------------------
Point..................................................       68,545.292
Area...................................................          944.688
Non-road...............................................            0.460
On-road................................................            3.260
Total..................................................       69,493.700
------------------------------------------------------------------------

C. Air Quality Modeling

    The SO2 attainment demonstration provides air quality 
dispersion modeling analyses to demonstrate that control strategies 
chosen to reduce SO2 source emissions will bring the Area 
into attainment by the statutory attainment date of October 4, 2018. 
The modeling analyses, conducted pursuant to recommendations outlined 
in Appendix W to 40 CFR part 51 (EPA's Modeling Guidance), are used to 
assess the control strategy for a nonattainment area and establish 
emission limits that will provide for attainment. The analysis requires 
five years of meteorological data to simulate the dispersion of 
pollutant plumes from multiple point, area, or volume sources across 
the averaging times of interest. The modeling demonstration typically 
also relies on maximum allowable emissions from sources in the 
nonattainment area. Though the actual

[[Page 32611]]

emissions are likely to be below the allowable emissions, sources have 
the ability to run at higher production rates or optimize controls such 
that emissions approach the allowable emissions limits. A modeling 
analysis that provides for attainment under all scenarios of operation 
for each source must therefore consider the worst case scenario of both 
the meteorology (e.g. predominant wind directions, stagnation, etc.) 
and the maximum allowable emissions.
    PADEP provided two sets of modeling analyses: One analysis was 
developed in accordance with EPA's Modeling Guidance and the 2014 
SO2 Nonattainment Guidance, and was prepared using the 
default option in EPA's preferred dispersion modeling system, AERMOD; a 
second modeling analysis also utilized AERMOD but included a procedure 
called AERMOIST, an alternative model option which accounts for 
additional plume rise associated with the latent heat release of 
condensation due to moisture in a stack's plume. AERMOIST is currently 
not approved by EPA for regulatory use. A more detailed discussion of 
PADEP's modeling analysis for the Indiana Area can be found in 
Pennsylvania's October 11, 2017 submittal.
    In addition to submitting the Indiana Area attainment plan to EPA 
on October 11, 2017, PADEP also submitted a request to EPA to review 
AERMOIST for use in the Indiana Area attainment plan. EPA has completed 
a review and determined that the AERMOIST procedure is not an 
appropriate option for use in the Indiana attainment plan for the 
following reasons: (1) There is no multi-monitor database of 
SO2 monitoring data available for the four major sources of 
SO2 in the Indiana Area to conduct a source-specific 
statistical test to determine if AERMOIST provides a definitive 
improvement over the current regulatory default version of AERMOD; (2) 
AERMOIST was universally applied to all the major sources in the 
Indiana Area regardless of whether the source plumes are actually 
saturated; and (3) there is a lack of supporting analysis for using 
relative humidity measurements in AERMOIST. For these reasons, EPA is 
rejecting the AERMOIST modeling analysis for the Indiana Area 
attainment plan. A detailed discussion of the deficiencies of the 
AERMOIST modeling analysis submitted for the Indiana Area can be found 
in EPA's AERMOIST modeling TSD for the Indiana which can be found under 
Docket ID No. EPA-R03-OAR-2017-0615 and available online at 
www.regulations.gov.
    EPA has reviewed the default AERMOD analysis without the AERMOIST 
module submitted for the Indiana Area. The Indiana Area was divided 
into two separate modeling domains. Refer to EPA's Modeling TSD for the 
Indiana Area under Docket ID EPA-R03-OAR-2017-0615, available at 
www.regulations.gov for EPA's review of the modeling domains. One 
domain included portions of Armstrong County which only addressed 
emissions from Keystone as a source. The other domain covered all of 
Indiana County and addressed emissions from all four sources in the 
nonattainment area. For both domains, background concentrations 
included impacts from non-modeled sources. Each separate model domain 
used its own (different) background concentration.
    AERMOD was used to determine the critical emission values (CEV) for 
Conemaugh, Keystone, and Seward where the modeled 1-hour emission rates 
demonstrate compliance with the 2010 1-hour SO2 NAAQS. The 
SO2 emission rates for Homer City were based on the unit 1, 
unit 2, and unit 3 combined mass-based SO2 emission limits 
established in Plan Approval 32-00055H,\8\ which authorized the 
installation of Novel Integrated Desulfurization (NID) systems, often 
referred to as Dry Flue Gas Desulphurization (FGD) systems on unit 1 
and unit 2. This 1-hour SO2 limit was based on air 
dispersion modeling that demonstrated compliance with the 2010 1-hour 
SO2 NAAQS. The CEV rates used in the demonstration analysis 
for each of the four sources are summarized in the following table. The 
modeled emission rate in grams per second was converted to pounds per 
hour, which is the CEV limit.\9\
---------------------------------------------------------------------------

    \8\ Plan Approval 32-00055H was issued on April 2, 2012, and 
modified on April 4, 2013, by the DEP.
    \9\ Based on the National Institute of Standards and Technology 
conversion: 1 pound = 453.59237 grams.

     Table 3--Critical Emission Values From Indiana, PA SIP Modeling
                              Demonstration
------------------------------------------------------------------------
                                           Modeled rate   CEV limit (lbs/
                Facility                       (g/s)            hr)
------------------------------------------------------------------------
Conemaugh Generating Station............          426.00        3,381.00
Homer City Generating Station, Unit 1...          195.30        1,550.02
Homer City Generating Station, Unit 2...          195.30        1,550.02
Homer City Generating Station, Unit 3...          410.76        3,260.02
Keystone Generating Station.............        1,223.58        9,711.10
Seward Generating Station...............          640.00        5,079.44
------------------------------------------------------------------------

    Using the EPA conversion factor for the SO2 NAAQS, the 
final 1-hour CEV model run design values for the Armstrong County 
portion (196.28 [mu]g/m\3\) and the Indiana County portion (196.44 
[mu]g/m\3\) of the Indiana Area are less than 75 ppb.\10\
---------------------------------------------------------------------------

    \10\ The SO2 NAAQS level is expressed in ppb but 
AERMOD gives results in [mu]g/m\3\. The conversion factor for 
SO2 (at the standard conditions applied in the ambient 
SO2 reference method) is 1ppb = approximately 2.619 
[mu]g/m\3\.
    See Pennsylvania's SO2 Round 3 Designations Proposed 
Technical Support Document at https://www.epa.gov/sites/production/files/2017-08/documents/35_pa_so2_rd3-final.pdf.
---------------------------------------------------------------------------

    PADEP also provided air dispersion modeling with randomly 
reassigned emissions (RRE) to provide support for establishing longer 
term emission limits for Keystone and Seward that would provide for 
attainment of the NAAQS. EPA's 2014 SO2 Nonattainment 
Guidance and Section I of this proposed rulemaking provide an extensive 
discussion of EPA's rationale for concluding that emission limits that 
are appropriately set based on averaging times longer than 1 hour and 
up to as long as 30 days can be found to provide for attainment of the 
2010 SO2 NAAQS. When determining longer term emission 
limits, EPA's 2014 SO2 Nonattainment Guidance states,

    ``[T]he EPA is not precluding states from using other approaches 
to determine appropriate longer term average limits. However, the 
EPA would recommend in all cases that the analysis begin with 
determination of the critical emission values. A comparison of the 
1-hour limit and the proposed longer term limit, in particular an 
assessment of whether the longer term

[[Page 32612]]

average limit may be considered to be of comparable stringency to a 
1-hour limit at the critical emission value, would be a critical 
element of a demonstration that any longer term average limits in 
the SIP will help provide adequate assurance that the plan will 
provide for attainment and maintenance of the 1-hour NAAQS.''

    As discussed in the RACM/RACT section below, a 24-hour block 
average SO2 emission limit for Keystone and a rolling 30-day 
average SO2 emission limit for Seward were developed by 
conducting additional modeling with SO2 emissions 
distributions representative of future operations which were derived 
for each facility by evaluating emissions for 2014-2016. For each 
facility, the emissions were randomly reassigned to develop 100 hourly 
emission files for use in 100 AERMOD simulations. These AERMOD 
simulations included CEV rates for three facilities, and hourly 
emissions for either Seward or Keystone. EPA believes that the 
distribution of emissions modeled in the 100 RRE methodology, which 
were based on historical operating levels and scaled to conform with 
the longer term limits, are a reasonable representation of an allowable 
emissions distribution for both Seward and Keystone. EPA believes that 
the 100 RRE analyses and model results for Keystone and Seward provide 
adequate assurance that the longer term emission limits for both of 
these facilities will result in attainment of the 2010 SO2 
NAAQS by the attainment date. A more detailed discussion of the RRE 
modeling is provided in EPA's Modeling TSD for the Indiana Area under 
Docket ID EPA-R03-OAR-2017-0615, available at www.regulations.gov.
    EPA has reviewed the modeling that Pennsylvania submitted to 
support the attainment demonstration for the Indiana Area and has 
determined that the default AERMOD modeling is consistent with CAA 
requirements, Appendix W to 40 CFR part 51, and EPA's 2014 
SO2 Guidance for SO2 attainment demonstration 
modeling. Because the AERMOD analysis employing AERMOIST has not been 
approved by EPA for use in the attainment demonstration for the Indiana 
Area, EPA is not proposing to approve the modeling submitted by PADEP 
which employed AERMOIST. EPA is proposing to approve the default non-
AERMOIST modeling, including the CEV and RRE simulations, provided in 
the attainment plan and EPA believes that the modeling reasonably 
demonstrates that the Indiana Area will attain the 2010 1-hour primary 
SO2 NAAQS by the attainment date.

D. RACM/RACT

    CAA section 172(c)(1) requires that each attainment plan provide 
for the implementation of all reasonably available control measures 
(i.e., RACM) as expeditiously as practicable and shall provide for 
attainment of the NAAQS. Section 172(c)(6) requires SIPs to contain 
enforceable emission limitations and control measures as may be 
necessary or appropriate to provide for NAAQS attainment. EPA 
interprets RACM, including RACT, under section 172, as measures that a 
state determines to be both reasonably available and contribute to 
attainment as expeditiously as practicable ``for existing sources in 
the area.''
    Pennsylvania's October 11, 2017, submittal discusses federal and 
state measures that Pennsylvania asserts will provide emission 
reductions leading to attainment and maintenance of the 2010 
SO2 NAAQS. With regards to state rules, Pennsylvania cites 
its low sulfur fuel rules, which were SIP-approved on July 10, 2014 (79 
FR 39330). Pennsylvania's low sulfur fuel oil provisions apply to 
refineries, pipelines, terminals, retail outlet fuel storage 
facilities, commercial and industrial facilities, and facilities with 
units burning regulated fuel oil to produce electricity and domestic 
home heaters. These low sulfur fuel oil rules reduce the amount of 
sulfur in fuel oils used in combustion units, thereby reducing 
SO2 emissions and the formation of sulfates that cause 
decreased visibility.
    Pennsylvania's submittal discusses that the main SO2 
emitting sources at Conemaugh, Homer City, Keystone, and Seward are all 
equipped with FGD systems (wet limestone scrubbers, dry FGD, or in-
furnace limestone injection systems) to reduce SO2 
emissions. Table 4 lists the control technology at each of the main 
SO2 emitting sources at each facility.

                  Table 4--Control Technology at the Four Major SO2 Sources in the Indiana Area
----------------------------------------------------------------------------------------------------------------
                                                                                                      Control
                Facility                             Unit                     SO2 control          installation
                                                                                                       date
----------------------------------------------------------------------------------------------------------------
Conemaugh...............................  031--Main Boiler 1........  Wet limestone scrubber....           ~1994
                                          031--Main Boiler 2........  Wet limestone scrubber....           ~1995
Homer City..............................  031--Boiler 1.............  Dry FGD...................      11/18/2015
                                          032--Boiler 2.............  Dry FGD...................       5/23/2016
                                          033--Boiler 3.............  Wet limestone scrubber....           ~2002
Keystone................................  031--Boiler 1.............  Wet limestone scrubber....       9/24/2009
                                          032--Boiler 2.............  Wet limestone scrubber....      11/22/2009
Seward..................................  034--CFB Boiler 1.........  In-furnace limestone                 ~2004
                                                                       injection.
                                          035--CFB Boiler 2.........  In-furnace limestone                 ~2004
                                                                       injection.
----------------------------------------------------------------------------------------------------------------

    With these controls installed, Pennsylvania's submittal discusses 
facility-specific control measures, namely SO2 emission 
limits for Conemaugh, Homer City, and Seward, and new SO2 
emission limits for Keystone. Keystone's new limits were developed 
through air dispersion modeling (default AERMOD) submitted by PADEP. 
The modeling analysis is discussed in section III.C. Air Quality 
Modeling of this proposed rulemaking and in the Modeling TSD. In order 
to ensure that the Indiana Area demonstrates attainment with the 
SO2 NAAQS, PADEP asserts that the following combination of 
emission limits at the four facilities is sufficient for the Indiana 
Area to meet the SO2 NAAQS and serve as RACM/RACT:
     Conemaugh's current SO2 emission limits 
contained in the Title V Operating Permit (TVOP) 32-00059 because the 
emission limits for Conemaugh determined by the modeling as necessary 
for SO2 attainment would be less stringent;
     Seward's current SO2 emission limit in TVOP 32-
00040 because the emission limits for Seward determined by the modeling 
as necessary for SO2 attainment would be less stringent;
     Homer City's current SO2 emission limits 
established in Plan Approval 32-00055H and Plan Approval 32-00055I; and

[[Page 32613]]

     A new, more stringent combined SO2 emission 
limit for Keystone Unit 1 and Unit 2 of 9,600 pounds per hour (lbs/hr) 
block 24-hour average limit.
    The emission limits for each of the SO2-emitting 
facilities are listed in Table 5.

                            Table 5--SO2 Emission Limits for Indiana Area Facilities
----------------------------------------------------------------------------------------------------------------
                                                           Emission limit (lbs/
             Facility                 Source description            hr)                  Averaging period
----------------------------------------------------------------------------------------------------------------
Conemaugh.........................  Unit 1...............  1,656 (TVOP 32-       3-hour block.
                                    Unit 2...............   00059).
Homer City........................  Unit 1...............  6,360 (Plan Approval  1-hour block.
                                    Unit 2...............   32-00055H) and
                                    Unit 3...............   limits specified in
                                                            Plan Approval 32-
                                                            00055I.
Keystone..........................  Unit 1...............  9,600 (New limit      24-hour block.
                                    Unit 2...............   based on default
                                                            AERMOD).
Seward............................  Unit 1...............  3,038.4 (TVOP 32-     30-day rolling.
                                    Unit 2...............   00040).
----------------------------------------------------------------------------------------------------------------

    The emission limits for Conemaugh, Keystone and Seward have 
averaging times greater than 1-hour (ranging between three hours and 30 
days). The default non-AERMOIST modeling analysis for the Indiana Area 
was used to establish CEVs for each facility. These (1-hour) CEVs were 
used for developing longer than 1-hour emission limits for Seward, 
Conemaugh, and Keystone. SO2 limits at Conemaugh are set to 
a 3-hour block average. This average is roughly in line with the CEV 
modeled limit and the ratio from Appendix C in EPA's 2014 
SO2 Nonattainment Guidance. Keystone's limits were set to a 
24-hour block average based on the 100 RRE simulation method discussed 
in Section III.C. Air Quality Modeling in this proposed rulemaking. A 
similar approach was used to establish a 30-day rolling average for 
Seward. Appendices C-1a and C-4 of Pennsylvania's October 11, 2017 SIP 
submittal provide a detailed explanation of the longer term emission 
limits. EPA believes the 100 RRE iteration approach used in 
Pennsylvania's submittal for determining longer term emission limits 
for Seward and Keystone can be used to demonstrate compliance with the 
2010 SO2 NAAQS. EPA's analysis of the default AERMOD 
modeling analysis using longer term emission limits shows, as discussed 
in detail in the Modeling TSD, that the emission limits listed in Table 
5 are sufficient for the Indiana Area to attain the 1-hour 
SO2 NAAQS. EPA's analysis of the longer term emission limits 
is discussed in more detail in the Modeling TSD for the Indiana Area 
under Docket ID EPA-R03-OAR-2017-0615, available at 
www.regulations.gov.
    The emission limits or compliance parameters, such as contingency 
measures, or both, were established through Consent Orders and 
Agreements (COAs) and Consent Orders (COs) between PADEP and the 
respective facility (see Appendices B-1 through B-4 of the October 11, 
2017, SIP submittal). The collective emission limits and all related 
compliance parameters (i.e. the measures which include system audits, 
record-keeping and reporting, and corrective actions) have been 
proposed for incorporation into the SIP to make these changes 
permanently federally enforceable. PADEP affirms that the 
implementation of existing and new emission limits and corresponding 
compliance parameters for the four EGUs will enable the Indiana Area to 
attain and maintain the SO2 NAAQS.
    EPA is proposing to approve Pennsylvania's determination that the 
proposed SO2 control strategy at Keystone, Conemaugh, Homer 
City, and Seward constitutes RACM/RACT for each SO2 source 
in the Indiana Area based on the modeling analysis previously 
described. EPA finds Pennsylvania's control strategy for RACM/RACT 
including emission limits and compliance parameters for the four EGUs 
will enable the Indiana Area to attain and maintain the NAAQS.
    Furthermore, PADEP requests that the unredacted portions of the 
COAs, COs, Plan Approvals, and TVOP submitted by PADEP with the 
attainment plan be approved into the Pennsylvania SIP. Including the 
emission limits listed in the CO for Keystone, the Plan Approval for 
Homer City, and the TVOPs for Conemaugh and Seward (see Table 4), and 
corresponding compliance parameters found in the COAs and COs for 
Keystone, Conemaugh, Homer City, and Seward in the Pennsylvania SIP 
means that these measures will become permanent and enforceable SIP 
measures to meet the requirements of the CAA. EPA, therefore, proposes 
to approve Pennsylvania's October 11, 2017 SIP submittal as meeting the 
RACM/RACT requirements of section 172(c)(1) and the enforceable 
emission limitation and control measures requirements of section 
172(c)(6) of the CAA.

E. RFP Plan

    Section 172(c)(2) of the CAA requires that an attainment plan 
includes a demonstration that shows reasonable further progress (i.e., 
RFP) for meeting air quality standards will be achieved through 
generally linear incremental improvement in air quality. Section 171(1) 
of the CAA defines RFP as ``such annual incremental reductions in 
emissions of the relevant air pollutant as are required by this part 
(part D) or may reasonably be required by EPA for the purpose of 
ensuring attainment of the applicable NAAQS by the applicable 
attainment date.'' As stated in the 1994 SO2 Guidelines 
Document \11\ and repeated in the 2014 SO2 Nonattainment 
Guidance, EPA continues to believe that this definition is most 
appropriate for pollutants that are emitted from numerous and diverse 
sources, where the relationship between particular sources and ambient 
air quality are not directly quantified. In such cases, emissions 
reductions may be required from various types and locations of sources. 
The relationship between SO2 and sources is much more 
defined, and usually there is a single step between pre-control 
nonattainment and post-control attainment. Therefore, EPA interpreted 
RFP for SO2 as adherence to an ambitious compliance schedule 
in both the 1994 SO2 Guideline Document and the 2014 
SO2 Nonattainment Guidance. EPA finds the control measures 
included in Pennsylvania's submittal demonstrate attainment for the 
Area with the 2010 SO2 NAAQS based on the modeling submitted 
by

[[Page 32614]]

Pennsylvania. The permits and compliance orders submitted by 
Pennsylvania for inclusion in the SIP require these control measures 
and resulting emission reductions to be achieved as expeditiously as 
practicable. As a result, based on air quality modeling reviewed by 
EPA, this is projected to yield a sufficient reduction in 
SO2 emissions from the major sources in the Indiana Area 
resulting in modeled attainment of the SO2 NAAQS for the 
Indiana Area. Therefore, EPA has determined that PADEP's SO2 
attainment plan for the Indiana Area fulfills the RFP requirements for 
the Indiana Area. EPA does not anticipate future nonattainment, or that 
the Area will not attain the NAAQS by the October 4, 2018 attainment 
date. EPA proposes to approve Pennsylvania's attainment plan with 
respect to the RFP requirements.
---------------------------------------------------------------------------

    \11\ SO2 Guideline Document, U.S. Environmental 
Protection Agency, Office of Air Quality Planning and Standards, 
Research Triangle Park, N.C. 27711, EPA-452/R-94-008, February 1994. 
Located at: http://www.epa.gov/ttn/oarpg/t1pgm.html.
---------------------------------------------------------------------------

F. Contingency Measures

    In accordance with section 172(c)(9) of the CAA, contingency 
measures are required as additional measures to be implemented in the 
event that an area fails to meet the RFP requirements or fails to 
attain the standard by its attainment date. These measures must be 
fully adopted rules or control measures that can be implemented quickly 
and without additional EPA or state action if the area fails to meet 
RFP requirements or fails to meet its attainment date, and should 
contain trigger mechanisms and an implementation schedule. However, 
SO2 presents special considerations. As stated in the final 
2010 SO2 NAAQS promulgation on June 22, 2010 (75 FR 35520) 
and in the 2014 SO2 Nonattainment Guidance, EPA concluded 
that because of the quantifiable relationship between SO2 
sources and control measures, it is appropriate that state agencies 
develop a comprehensive program to identify sources of violations of 
the SO2 NAAQS and undertake an aggressive follow-up for 
compliance and enforcement.
    The COAs or COs for Conemaugh, Homer City, Keystone, and Seward 
(see Appendices B-1 through B-4 of the October 11, 2017 submittal) each 
contain the following measures that are designed to keep the Indiana 
Area from triggering an exceedance or violation of the SO2 
NAAQS: (1) Upon execution of the COA or CO, if SO2 emissions 
from the combined SO2 emitting sources at the facility 
exceed 99% of the SO2 emissions limit for the facility 
(listed in Table 3), within 48 hours the facility is required to 
undertake a full system audit of the SO2 emitting sources 
and submit a written report to PADEP within 15 days, and corrective 
actions shall be identified by PADEP as necessary; and (2) Upon 
execution of the COA or CO, if the Strongstown monitor (ID 42-063-0004) 
measures a 1-hour concentration exceeding 75 ppb, PADEP will notify the 
facility in the Area, and the facility in the Area is required to 
identify whether any of the SO2-emitting sources at the 
respective facility were running at the time of the exceedance, and 
within a reasonable time period leading up to the exceedance, not to 
exceed 24 hours. If any of the SO2-emitting sources were 
running at the time of the exceedance, the facility must then analyze 
the meteorological data on the day the daily exceedance occurred to 
ensure that the daily exceedance was not due to SO2 
emissions from the respective facility. The facility's findings must be 
submitted to PADEP within 30 days of being notified of the exceedance.
    Additionally, if PADEP identifies a daily maximum SO2 
concentration exceeding 75 ppb at a PADEP-operated SO2 
ambient air quality monitor in the Indiana Area, within five days, 
PADEP will contact Conemaugh, Homer City, Keystone, and Seward to 
trigger the implementation of the daily exceedance report contingency 
measure described in section VIII.C. of the October 11, 2017 submittal. 
If necessary, section 4(27) of the Pennsylvania Air Pollution Control 
Act (APCA) authorizes PADEP to take any action it deems necessary or 
proper for the effective enforcement of APCA and the rules and 
regulations promulgated under APCA. Such actions include the issuance 
of orders and the assessment of civil penalties. A more detailed 
description of the contingency measures can be found in section VIII of 
the October 11, 2017 submittal as well as the COAs and COs included in 
the submittal and included for incorporation by reference into the SIP.
    EPA is proposing to find that Pennsylvania's October 11, 2017 
submittal includes sufficient measures to expeditiously identify the 
source of any violation of the SO2 NAAQS and for aggressive 
follow-up including enforcement measures within PADEP's authority as 
necessary. Therefore, EPA proposes that the contingency measures 
submitted by Pennsylvania follow the 2014 SO2 Nonattainment 
Guidance and meet the section 172(c)(9) requirements.

G. New Source Review 12
---------------------------------------------------------------------------

    \12\ The CAA new source review (NSR) program is composed of 
three separate programs: Prevention of significant deterioration 
(PSD), NNSR, and Minor NSR. PSD is established in part C of title I 
of the CAA and applies in undesignated areas and in areas that meet 
the NAAQS--designated ``attainment areas''--as well as areas where 
there is insufficient information to determine if the area meets the 
NAAQS--designated ``unclassifiable areas.'' The NNSR program is 
established in part D of title I of the CAA and applies in areas 
that are not in attainment of the NAAQS--designated ``nonattainment 
areas.'' The Minor NSR program addresses construction or 
modification activities that do not qualify as ``major'' and applies 
regardless of the designation of the area in which a source is 
located. Together, these programs are referred to as the NSR 
programs. Section 173 of the CAA lays out the NNSR program for 
preconstruction review of new major sources or major modifications 
to existing sources, as required by CAA section 172(c)(5). The 
programmatic elements for NNSR include, among other things, 
compliance with the lowest achievable emissions rate and the 
requirement to obtain emissions offsets.
---------------------------------------------------------------------------

    Section 172(c)(5) of the CAA requires that an attainment plan 
require permits for the construction and operation of new or modified 
major stationary sources in a nonattainment area. Pennsylvania has a 
fully implemented Nonattainment New Source Review (NNSR) program for 
criteria pollutants in 25 Pennsylvania Code Chapter 127, Subchapter E, 
which was approved into the Pennsylvania SIP on December 9, 1997 (62 FR 
64722). On May 14, 2012 (77 FR 28261), EPA approved a SIP revision 
pertaining to the pre-construction permitting requirements of 
Pennsylvania's NNSR program to update the regulations to meet EPA's 
2002 NSR reform regulations. EPA then approved an update to 
Pennsylvania's NNSR regulations on July 13, 2012 (77 FR 41276). These 
rules provide for appropriate NSR as required by CAA sections 172(c)(5) 
and 173 and 40 CFR 51.165 for SO2 sources undergoing 
construction or major modification in the Indiana Area without need for 
modification of the approved rules. Therefore, EPA concludes that the 
Pennsylvania SIP meets the requirements of section 172(c)(5) for this 
Area.

IV. EPA's Proposed Action

    EPA is proposing to approve Pennsylvania's SIP revision for the 
Indiana Area, as submitted through PADEP to EPA on October 11, 2017, 
for the purpose of demonstrating attainment of the 2010 1-hour 
SO2 NAAQS. Specifically, EPA is proposing to approve the 
base year emissions inventory, a modeling demonstration of 
SO2 attainment, an analysis of RACM/RACT, enforceable 
emission limitations and control measures, a RFP plan, and contingency 
measures for the Indiana Area and is proposing that the Pennsylvania 
SIP has met requirements for NSR for the 2010 1-hour SO2 
NAAQS. Additionally, EPA is proposing to approve into the Pennsylvania 
SIP specific SO2 emission limits,

[[Page 32615]]

compliance parameters, and contingency measures established for the 
SO2 sources impacting the Indiana Area.
    EPA has determined that Pennsylvania's SO2 attainment 
plan for the 2010 1-hour SO2 NAAQS for Indiana County meets 
the applicable requirements of the CAA. Thus, EPA is proposing to 
approve Pennsylvania's attainment plan for the Indiana Area as 
submitted on October 11, 2017. EPA's analysis for this proposed action 
is discussed in Section III of this proposed rulemaking. EPA is 
soliciting public comments on the issues discussed in this document. 
These comments will be considered before taking final action. Final 
approval of this SIP submittal will remove EPA's duty to promulgate and 
implement a FIP under CAA section 110(c).

V. Incorporation by Reference

    In this proposed 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 portions of the COAs or COs entered 
between Pennsylvania and Conemaugh, Homer City, Keystone, and Seward 
that are not redacted, as well as the unredacted portions of the TVOPs 
or Plan Approval included in the October 11, 2017 submittal. These 
include emission limits and associated compliance parameters (i.e. the 
measures which include system audits, record-keeping and reporting, and 
corrective actions). EPA has made, and will continue to make, these 
materials generally available through http://www.regulations.gov and at 
the EPA Region III Office (please contact the person identified in the 
FOR FURTHER INFORMATION CONTACT section of this proposed rulemaking for 
more information).

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

List of Subjects in 40 CFR Part 52

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

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

    Dated: June 27, 2018.
Cecil Rodrigues,
Acting Regional Administrator, Region III.
[FR Doc. 2018-14947 Filed 7-12-18; 8:45 am]
BILLING CODE 6560-50-P



                                                  32606                      Federal Register / Vol. 83, No. 135 / Friday, July 13, 2018 / Proposed Rules

                                                  petty officer who has been designated                    Station (hereafter referred to as                     FOR FURTHER INFORMATION CONTACT:
                                                  by the Captain of the Port Buffalo to act                ‘‘Keystone,’’ ‘‘Conemaugh,’’ ‘‘Homer                  Megan Goold, (215) 814–2027, or by
                                                  on his behalf.                                           City,’’ and ‘‘Seward’’). The SIP                      email at goold.megan@epa.gov.
                                                    (4) Vessel operators desiring to enter                 submission is an attainment plan which                SUPPLEMENTARY INFORMATION:
                                                  or operate within the safety zone must                   includes the base year emissions
                                                  contact the Captain of the Port Buffalo                  inventory, an analysis of the reasonably              Table of Contents
                                                  or his on-scene representative to obtain                 available control technology (RACT)                   I. Background for EPA’s Proposed Action
                                                  permission to do so. The Captain of the                  and reasonably available control                      II. Pennsylvania’s Attainment Plan Submittal
                                                  Port Buffalo or his on-scene                             measure (RACM) requirements,                                for the Indiana Area
                                                  representative may be contacted via                      enforceable emission limitations and                  III. EPA’s Analysis of Pennsylvania’s
                                                                                                                                                                       Attainment Plan for the Indiana Area
                                                  VHF Channel 16. Vessel operators given                   control measures, a reasonable further                   A. Pollutants Addressed
                                                  permission to enter or operate in the                    progress (RFP) plan, a modeling                          B. Emissions Inventory Requirements
                                                  safety zone must comply with all                         demonstration of SO2 attainment, and                     C. Air Quality Modeling
                                                  directions given to them by the Captain                  contingency measures for the Indiana                     D. RACM/RACT
                                                  of the Port Buffalo, or his on-scene                     Area. As part of approving the                           E. RFP Plan
                                                  representative.                                          attainment plan, EPA is also proposing                   F. Contingency Measures
                                                                                                           to approve into the Pennsylvania SIP                     G. New Source Review
                                                    Dated: July 5, 2018.                                                                                         IV. EPA’s Proposed Action
                                                  Joseph S. Dufresne,
                                                                                                           SO2 emission limits and associated                    V. Incorporation by Reference
                                                                                                           compliance parameters for Keystone,                   VI. Statutory and Executive Order Reviews
                                                  Captain, U.S. Coast Guard, Captain of the
                                                  Port Buffalo.
                                                                                                           Conemaugh, Homer City and Seward
                                                                                                           and proposes to find Pennsylvania has                 I. Background for EPA’s Proposed
                                                  [FR Doc. 2018–14993 Filed 7–12–18; 8:45 am]                                                                    Action
                                                                                                           measures in place to address
                                                  BILLING CODE 9110–04–P
                                                                                                           nonattainment new source review. EPA                     On June 2, 2010, the EPA
                                                                                                           proposes to approve Pennsylvania’s                    Administrator signed a final rule
                                                                                                           attainment plan and concludes that the                establishing a new primary SO2 NAAQS
                                                  ENVIRONMENTAL PROTECTION                                 Indiana Area will attain the 2010 1-hour              as a 1-hour standard of 75 parts per
                                                  AGENCY                                                   primary SO2 NAAQS by the applicable                   billion (ppb), based on a 3-year average
                                                                                                           attainment date and that the plan meets               of the annual 99th percentile of daily
                                                  40 CFR Part 52                                           all applicable requirements under the                 maximum 1-hour average
                                                  [EPA–R03–OAR–2017–0615; FRL–9980–65-                     Clean Air Act (CAA).                                  concentrations. See 75 FR 35520 (June
                                                  Region 3]                                                DATES: Written comments must be                       22, 2010), codified at 40 CFR 50.17. This
                                                                                                           received on or before August 13, 2018.                action also revoked the existing 1971
                                                  Approval and Promulgation of Air                                                                               primary annual and 24-hour standards,
                                                                                                           ADDRESSES: Submit your comments,
                                                  Quality Implementation Plans;                                                                                  subject to certain conditions.1 EPA
                                                                                                           identified by Docket ID No. EPA–R03–
                                                  Pennsylvania; Attainment Plan for the                                                                          established the NAAQS based on
                                                                                                           OAR–2017–0615 at http://
                                                  Indiana, Pennsylvania Nonattainment                                                                            significant evidence and numerous
                                                                                                           www.regulations.gov, or via email to
                                                  Area for the 2010 Sulfur Dioxide                                                                               health studies demonstrating that
                                                                                                           spielberger.susan@epa.gov. For
                                                  Primary National Ambient Air Quality                                                                           serious health effects are associated
                                                                                                           comments submitted at Regulations.gov,
                                                  Standard                                                                                                       with short-term exposures to SO2
                                                                                                           follow the online instructions for
                                                  AGENCY:  Environmental Protection                        submitting comments. Once submitted,                  emissions ranging from five minutes to
                                                  Agency (EPA).                                            comments cannot be edited or removed                  24 hours with an array of adverse
                                                  ACTION: Proposed rule.                                   from Regulations.gov. For either manner               respiratory effects including narrowing
                                                                                                           of submission, EPA may publish any                    of the airways which can cause
                                                  SUMMARY:    The Environmental Protection                 comment received to its public docket.                difficulty breathing
                                                  Agency (EPA) is proposing to approve a                   Do not submit electronically any                      (bronchoconstriction) and increased
                                                  state implementation plan (SIP)                          information you consider to be                        asthma symptoms. For more
                                                  revision, submitted by the                               confidential business information (CBI)               information regarding the health
                                                  Commonwealth of Pennsylvania                             or other information whose disclosure is              impacts of SO2, please refer to the June
                                                  through the Pennsylvania Department of                   restricted by statute. Multimedia                     22, 2010 final rulemaking. See 75 FR
                                                  Environmental Protection (PADEP), to                     submissions (audio, video, etc.) must be              35520. Following promulgation of a new
                                                  EPA on October 11, 2017, for the                         accompanied by a written comment.                     or revised NAAQS, EPA is required by
                                                  purpose of providing for attainment of                   The written comment is considered the                 the CAA to designate areas throughout
                                                  the 2010 sulfur dioxide (SO2) primary                    official comment and should include                   the United States as attaining or not
                                                  national ambient air quality standard                    discussion of all points you wish to                  attaining the NAAQS; this designation
                                                  (NAAQS) in the Indiana, Pennsylvania                     make. EPA will generally not consider                 process is described in section
                                                  SO2 nonattainment area (hereafter                        comments or comment contents located                  107(d)(1)–(2) of the CAA. On August 5,
                                                  referred to as the ‘‘Indiana Area’’ or                   outside of the primary submission (i.e.               2013, EPA promulgated initial air
                                                  ‘‘Area’’). The Indiana Area is comprised                 on the web, cloud, or other file sharing              quality designations for 29 areas for the
                                                  of Indiana County and a portion of                       system). For additional submission                    2010 SO2 NAAQS (78 FR 47191), which
                                                  Armstrong County (Plumcreek                              methods, please contact the person
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                                                                                                                                                                   1 EPA’s June 22, 2010 final action revoked the two
                                                  Township, South Bend Township, and                       identified in the FOR FURTHER
                                                                                                                                                                 1971 primary 24-hour standard of 140 ppb and the
                                                  Elderton Borough) in Pennsylvania. The                   INFORMATION CONTACT section. For the
                                                                                                                                                                 annual standard of 30 ppb because they were
                                                  major sources of SO2 in the Indiana                      full EPA public comment policy,                       determined not to add additional public health
                                                  Area emitting over 2,000 tpy of SO2                      information about CBI or multimedia                   protection given a 1-hour standard at 75 ppb. See
                                                  include several large electric generating                submissions, and general guidance on                  75 FR 35520. However, the secondary 3-hour SO2
                                                                                                                                                                 standard was retained. Currently, the 24-hour and
                                                  units (EGUs): Keystone Plant,                            making effective comments, please visit               annual standards are only revoked for certain of
                                                  Conemaugh Plant, Homer City                              http://www2.epa.gov/dockets/                          those areas the EPA has already designated for the
                                                  Generation, and Seward Generation                        commenting-epa-dockets.                               2010 1-hour SO2 NAAQS. See 40 CFR 50.4(e).



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                                                                              Federal Register / Vol. 83, No. 135 / Friday, July 13, 2018 / Proposed Rules                                         32607

                                                  became effective on October 4, 2013,                      CAA. EPA’s regulations governing                      November 15, 1990) in any area which
                                                  based on violating air quality                            nonattainment SIPs are set forth at 40                is a nonattainment area for any air
                                                  monitoring data for calendar years                        CFR part 51, with specific procedural                 pollutant, may be modified in any
                                                  2009–2011, where there were sufficient                    requirements and control strategy                     manner unless it ensures equivalent or
                                                  data to support a nonattainment                           requirements residing at subparts F and               greater emission reductions of such air
                                                  designation.2                                             G, respectively. Soon after Congress                  pollutant.
                                                     Effective on October 4, 2013, the                      enacted the 1990 Amendments to the                       CAA section 172(c)(1) directs states
                                                  Indiana Area was designated as                            CAA, EPA issued comprehensive                         with areas designated as nonattainment
                                                  nonattainment for the 2010 SO2 NAAQS                      guidance on SIPs, in a document                       to demonstrate that the submitted plan
                                                  for an area that encompasses the                          entitled the ‘‘General Preamble for the               provides for attainment of the NAAQS.
                                                  primary SO2 emitting sources of                           Implementation of Title I of the Clean                40 CFR part 51, subpart G further
                                                  Keystone, Conemaugh, Homer City, and                      Air Act Amendments of 1990,’’                         delineates the control strategy
                                                  Seward. The October 4, 2013 final                         published at 57 FR 13498 (April 16,                   requirements that SIPs must meet, and
                                                  designation triggered a requirement for                   1992) (General Preamble). Among other                 EPA has long required that all SIPs and
                                                  Pennsylvania to submit by April 4,                        things, the General Preamble addressed                control strategies reflect four
                                                  2015, a SIP revision with an attainment                   SO2 SIPs and fundamental principles for               fundamental principles of
                                                  plan for how the Area would attain the                    SIP control strategies. Id. at 13545–49,              quantification, enforceability,
                                                  2010 SO2 NAAQS as expeditiously as                        13567–68.                                             replicability, and accountability
                                                  practicable, but no later than October 4,                    On April 23, 2014, EPA issued                      (General Preamble, at 13567–68). SO2
                                                  2018, in accordance with CAA sections                     recommended guidance (hereafter 2014                  attainment plans must consist of two
                                                  172(c) and 191–192.                                       SO2 Nonattainment Guidance) for how                   components: (1) Emission limits and
                                                     For a number of areas, including the                   state submissions could address the                   other control measures that assure
                                                  Indiana Area, EPA published a notice                      statutory requirements for SO2                        implementation of permanent,
                                                  on March 18, 2016, effective April 18,                    attainment plans.3 In this guidance, EPA              enforceable and necessary emission
                                                  2016, that Pennsylvania and other                         described the statutory requirements for              controls, and (2) a modeling analysis
                                                  pertinent states had failed to submit the                 an attainment plan, which include: An                 which meets the requirements of 40 CFR
                                                  required SO2 attainment plan by this                      accurate base year emissions inventory                part 51, Appendix W which
                                                  submittal deadline. See 81 FR 14736.                      of current emissions for all sources of               demonstrates that these emission limits
                                                  This finding initiated a deadline under                   SO2 within the nonattainment area                     and control measures provide for timely
                                                  CAA section 179(a) for the potential                      (172(c)(3)); an attainment demonstration              attainment of the primary SO2 NAAQS
                                                  imposition of new source review and                       that includes a modeling analysis                     as expeditiously as practicable, but by
                                                  highway funding sanctions. However,                       showing that the enforceable emissions                no later than the attainment date for the
                                                  pursuant to Pennsylvania’s submittal of                   limitations and other control measures                affected area. In all cases, the emission
                                                  October 11, 2017, and EPA’s subsequent                    taken by the state will provide for                   limits and control measures must be
                                                  letter dated October 13, 2017, to                         expeditious attainment of the NAAQS                   accompanied by appropriate methods
                                                  Pennsylvania finding the submittal                        (172(c) and (c)(6)); demonstration of                 and conditions to determine compliance
                                                  complete and noting the stopping of the                   RFP (172(c)(2)); implementation of                    with the respective emission limits and
                                                  sanctions’ deadline, these sanctions                      RACM, including RACT (172(c)(1)); new                 control measures and must be
                                                  under section 179(a) will not be                          source review (NSR) requirements                      quantifiable (a specific amount of
                                                  imposed as a consequence of                               (172(c)(5)); and adequate contingency                 emission reduction can be ascribed to
                                                  Pennsylvania having missed the April 4,                   measures for the affected area                        the measures), fully enforceable
                                                  2015 deadline. Additionally, under                        (172(c)(9)). A synopsis of these                      (specifying clear, unambiguous and
                                                  CAA section 110(c), the March 18, 2016,                   requirements is also provided in the                  measurable requirements for which
                                                  finding triggered a requirement that EPA                  notice of proposed rulemaking on the                  compliance can be practicably
                                                  promulgate a federal implementation                       Illinois SO2 nonattainment plans,                     determined), replicable (the procedures
                                                  plan (FIP) within two years of the                        published on October 5, 2017 at 82 FR                 for determining compliance are
                                                  effective date of the finding unless, by                  46434.                                                sufficiently specific and non-subjective
                                                                                                               In order for the EPA to fully approve              so that two independent entities
                                                  that time, the state has made the
                                                                                                            a SIP as meeting the requirements of                  applying the procedures would obtain
                                                  necessary complete submittal and EPA
                                                                                                            CAA sections 110, 172 and 191–192 and                 the same result), and accountable
                                                  has approved the submittal as meeting
                                                                                                            EPA’s regulations at 40 CFR part 51, the              (source specific limits must be
                                                  applicable requirements. This FIP
                                                                                                            SIP for the affected area needs to                    permanent and must reflect the
                                                  obligation will no longer apply if and                    demonstrate to EPA’s satisfaction that                assumptions used in the SIP
                                                  when EPA makes final the approval                         each of the aforementioned                            demonstrations).
                                                  action proposed here.                                     requirements have been met. Under                        EPA’s 2014 SO2 Nonattainment
                                                     Attainment plans must meet the
                                                                                                            CAA sections 110(l) and 193, the EPA                  Guidance recommends that the
                                                  applicable requirements of the CAA,
                                                                                                            may not approve a SIP that would                      emission limits established for the
                                                  and specifically CAA sections 172, 191,                   interfere with any applicable                         attainment demonstration be expressed
                                                  and 192. The required components of an                    requirement concerning NAAQS                          as short-term average limits (e.g.,
                                                  attainment plan submittal are listed in                   attainment and RFP, or any other                      addressing emissions averaged over one
                                                  section 172(c) of Title 1, part D of the                  applicable requirement, and no                        or three hours), but also describes the
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                                                     2 EPA is continuing its designation efforts for the
                                                                                                            requirement in effect (or required to be              option to utilize emission limits with
                                                  2010 SO2 NAAQS. Pursuant to a court-order
                                                                                                            adopted by an order, settlement,                      longer averaging times of up to 30 days
                                                  finalized March 2, 2015, in the U.S. District Court       agreement, or plan in effect before                   so long as the state meets various
                                                  for the Northern District of California, EPA must                                                               suggested criteria. See 2014 SO2
                                                  complete the remaining designations for the rest of          3 See ‘‘Guidance for 1-Hour SO Nonattainment
                                                                                                                                             2                    Nonattainment Guidance, pp. 22 to 39.
                                                  the country on a schedule that contains three             Area SIP Submissions’’ (April 23, 2014), available
                                                  specific deadlines. Sierra Club, et al. v.                at https://www.epa.gov/sites/production/files/2016-
                                                                                                                                                                  The guidance recommends that—should
                                                  Environmental Protection Agency, 13–cv–03953–SI           06/documents/20140423guidance_nonattainment_          states and sources utilize longer
                                                  (2015).                                                   sip.pdf.                                              averaging times—the longer term


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                                                  32608                      Federal Register / Vol. 83, No. 135 / Friday, July 13, 2018 / Proposed Rules

                                                  average limit should be set at an                        for identifying this critical emission                to emit well below the critical emission
                                                  adjusted level that reflects a stringency                value inherently considers the                        value. In an ‘‘average year,’’ 4
                                                  comparable to the 1-hour average limit                   numerous variables that affect ambient                compliance with the 1-hour limit is
                                                  at the critical emission value shown to                  concentrations of SO2, such as                        expected to result in three exceedance
                                                  provide for attainment that the plan                     meteorological data, background                       days (i.e., three days with hourly values
                                                  otherwise would have set.                                concentrations, and topography. In the                above 75 ppb) and a fourth day with a
                                                     The 2014 SO2 Nonattainment                            standard approach, the state would then               maximum hourly value at 75 ppb. By
                                                  Guidance provides an extensive                           provide for attainment by setting a                   comparison, with the source complying
                                                  discussion of EPA’s rationale for                        continuously applicable 1-hour                        with a longer term limit, it is possible
                                                  concluding that appropriately set                        emission limit at this critical emission              that additional exceedances would
                                                  comparably stringent limitations based                   value.                                                occur that would not occur in the
                                                  on averaging times as long as 30 days                       EPA recognizes that some sources                   1-hour limit scenario (if emissions
                                                  can be found to provide for attainment                   have highly variable emissions, for                   exceed the critical emission value at
                                                  of the 2010 SO2 NAAQS. In evaluating                     example due to variations in fuel sulfur              times when meteorology is conducive to
                                                  this option, EPA considered the nature                   content and operating rate, that can                  poor air quality). However, this
                                                  of the standard, conducted detailed                      make it extremely difficult, even with a              comparison must also factor in the
                                                  analyses of the impact of 30-day average                 well-designed control strategy, to ensure             likelihood that exceedances that would
                                                  limits on the prospects for attaining the                in practice that emissions for any given              be expected in the 1-hour limit scenario
                                                  standard, and carefully reviewed how                     hour do not exceed the critical emission              would not occur in the longer term limit
                                                  best to achieve an appropriate balance                   value. EPA also acknowledges the                      scenario. This result arises because the
                                                  among the various factors that warrant                   concern that longer term emission limits              longer term limit requires lower
                                                  consideration in judging whether a                       can allow short periods with emissions                emissions most of the time (because the
                                                  state’s plan provides for attainment. Id.                above the ‘‘critical emission value,’’                limit is set below the critical emission
                                                  at pp. 22–39, and Appendices B, C, and                   which, if coincident with                             value), so a source complying with an
                                                  D.                                                       meteorological conditions conducive to                appropriately set longer term limit is
                                                     As specified in 40 CFR 50.17(b), the                  high SO2 concentrations, could in turn                likely to have lower emissions at critical
                                                  1-hour primary SO2 NAAQS is met at an                    create the possibility of a NAAQS                     times than would be the case if the
                                                  ambient air quality monitoring site                      exceedance occurring on a day when an                 source were emitting as allowed with a
                                                  when the 3-year average of the annual                    exceedance would not have occurred if                 1-hour limit.
                                                  99th percentile of daily maximum                         emissions were continuously controlled                   To illustrate this point, EPA
                                                  1-hour average concentrations is less                    at the level corresponding to the critical            conducted a statistical analysis using a
                                                  than or equal to 75 ppb. In a year with                  emission value. However, for several                  range of scenarios using actual plant
                                                  365 days of valid monitoring data, the                   reasons, EPA believes that the approach               data. The analysis is described in
                                                  99th percentile would be the fourth                      recommended in its guidance document                  Appendix B of EPA’s 2014 SO2
                                                  highest daily maximum 1-hour value.                      suitably addresses this concern. First,               Nonattainment Guidance. Based on the
                                                  The 2010 SO2 NAAQS, including this                       from a practical perspective, EPA                     analysis described in its 2014 SO2
                                                  form of determining compliance with                      expects the actual emission profile of a              Nonattainment Guidance, EPA expects
                                                  the standard, was upheld by the U.S.                     source subject to an appropriately set                that an emission profile with maximum
                                                  Court of Appeals for the District of                     longer term average limit to be similar               allowable emissions under an
                                                  Columbia Circuit in Nat’l Envt’l Dev.                    to the emission profile of a source                   appropriately set comparably stringent
                                                  Ass’n’s Clean Air Project v. EPA, 686                    subject to an analogous 1-hour average                30-day average limit is likely to have the
                                                  F.3d 803 (D.C. Cir. 2012). Because the                   limit. EPA expects this similarity                    net effect of having a lower number of
                                                  standard has this form, a single                         because it has recommended that the                   exceedances and better air quality than
                                                  exceedance does not create a violation                   longer term average limit be set at a                 an emission profile with maximum
                                                  of the standard. Instead, at issue is                    level that is comparably stringent to the             allowable emissions under a 1-hour
                                                  whether a source operating in                            otherwise applicable 1-hour limit                     emission limit at the critical emission
                                                  compliance with a properly set longer                    (reflecting a downward adjustment from                value. This result provides a compelling
                                                  term average could cause exceedances,                    the critical emissions value) and that
                                                                                                                                                                 policy rationale for allowing the use of
                                                  and if so the resulting frequency and                    takes the source’s emissions profile (and
                                                                                                                                                                 a longer averaging period, in
                                                  magnitude of such exceedances, and in                    inherent level of emissions variability)
                                                  particular, whether EPA can have                                                                               appropriate circumstances where the
                                                                                                           into account. As a result, EPA expects
                                                  reasonable confidence that a properly                                                                          facts indicate this result can be expected
                                                                                                           either form of emission limit to yield
                                                  set longer term average limit will                                                                             to occur.
                                                                                                           comparable air quality.                                  The question then becomes whether
                                                  provide that the average fourth highest                     Second, from a more theoretical
                                                                                                                                                                 this approach, which is likely to
                                                  daily maximum value will be at or                        perspective, EPA has compared the
                                                                                                                                                                 produce a lower number of overall
                                                  below 75 ppb. A synopsis of how EPA                      likely air quality with a source having
                                                                                                                                                                 exceedances even though it may
                                                  evaluates whether such plans ‘‘provide                   maximum allowable emissions under an
                                                  for attainment,’’ based on modeling of                   appropriately set longer term limit, as               produce some unexpected exceedances
                                                  projected allowable emissions and in                     compared to the likely air quality with               above the critical emission value, meets
                                                  light of the NAAQS’ form for                             the source having maximum allowable                   the requirement in section 110(a)(1) and
                                                  determining attainment at monitoring                     emissions under the comparable 1-hour                 172(c)(1) for SIPs to ‘‘provide for
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                                                  sites follows.                                           limit. In this comparison, in the 1-hour                4 An ‘‘average year’’ is used to mean a year with
                                                     For SO2 attainment plans based on                     average limit scenario, the source is                 average air quality. While 40 CFR 50 appendix T
                                                  1-hour emission limits, the standard                     presumed at all times to emit at the                  provides for averaging three years of 99th percentile
                                                  approach is to conduct modeling using                    critical emission level, and in the longer            daily maximum hourly values (e.g., the fourth
                                                  fixed emission rates. The maximum                        term average limit scenario, the source               highest maximum daily hourly concentration in a
                                                                                                                                                                 year with 365 days with valid data), this discussion
                                                  modeled emission rate that results in                    is presumed occasionally to emit more                 and an example below uses a single ‘‘average year’’
                                                  attainment is labeled the ‘‘critical                     than the critical emission value but on               in order to simplify the illustration of relevant
                                                  emission value.’’ The modeling process                   average, and presumably at most times,                principles.



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                                                                             Federal Register / Vol. 83, No. 135 / Friday, July 13, 2018 / Proposed Rules                                          32609

                                                  attainment’’ of the NAAQS. For SO2, as                   reflecting the type of control that the               primary SO2 NAAQS must demonstrate
                                                  for other pollutants, it is generally                    source will be using to comply with the               future attainment and maintenance of
                                                  impossible to design a nonattainment                     SIP emission limits, which (if                        the NAAQS in the entire area
                                                  plan in the present that will guarantee                  compliance requires new controls) may                 designated as nonattainment (i.e., not
                                                  that attainment will occur in the future.                require use of an emission database                   just at the violating monitor) by using
                                                  A variety of factors can cause a well-                   from another source. The recommended                  air quality dispersion modeling (see
                                                  designed attainment plan to fail and                     method involves using these data to                   Appendix W to 40 CFR part 51) to show
                                                  unexpectedly not result in attainment,                   compute a complete set of emission                    that the mix of sources and enforceable
                                                  for example if meteorology occurs that                   averages, computed according to the                   control measures and emission rates in
                                                  is more conducive to poor air quality                    averaging time and averaging                          an identified area will not lead to a
                                                  than was anticipated in the plan.                        procedures of the prospective emission                violation of the SO2 NAAQS. For a
                                                  Therefore, in determining whether a                      limitation (i.e., using 1-hour historical             short-term (i.e., 1-hour) standard, the
                                                  plan meets the requirement to provide                    emission values from the emissions                    EPA believes that dispersion modeling,
                                                  for attainment, EPA’s task is commonly                   database to calculate 30-day average                  using allowable emissions and
                                                  to judge not whether the plan provides                   emission values). In this recommended                 addressing stationary sources in the
                                                  absolute certainty that attainment will                  method, the ratio of the 99th percentile              affected area (and in some cases those
                                                  in fact occur, but rather whether the                    among these long term averages to the                 sources located outside the
                                                  plan provides an adequate level of                       99th percentile of the 1-hour values                  nonattainment area which may affect
                                                  confidence of prospective NAAQS                          represents an adjustment factor that may              attainment in the area) is technically
                                                  attainment. From this perspective, in                    be multiplied by the candidate 1-hour                 appropriate, efficient and effective in
                                                  evaluating use of a 30-day average limit,                emission limit (critical emission value)              demonstrating attainment in
                                                  EPA must weigh the likely net effect on                  to determine a longer term average                    nonattainment areas because it takes
                                                  air quality. Such an evaluation must                     emission limit that may be considered                 into consideration combinations of
                                                  consider the risk that occasions with                    comparably stringent.5                                meteorological and emission source
                                                  meteorology conducive to high                              The 2014 SO2 Nonattainment                          operating conditions that may
                                                  concentrations will have elevated                        Guidance also addresses a variety of                  contribute to peak ground-level
                                                  emissions leading to exceedances that                    related topics, such as the potential                 concentrations of SO2.
                                                  would not otherwise have occurred, and                   utility of setting supplemental emission                 The meteorological data used in the
                                                  must also weigh the likelihood that the                  limits, such as mass-based limits, to                 analysis should generally be processed
                                                  requirement for lower emissions on                       reduce the likelihood and/or magnitude                with the most recent version of
                                                  average will result in days not having                   of elevated emission levels that might                AERMET. Estimated concentrations
                                                  exceedances that would have been                         occur under the longer term emission                  should include ambient background
                                                  expected with emissions at the critical                  rate limit.                                           concentrations, should follow the form
                                                                                                             Preferred air quality models for use in             of the standard, and should be
                                                  emissions value. Additional policy
                                                                                                           regulatory applications are described in              calculated as described in section
                                                  considerations, such as in this case the
                                                                                                           Appendix A of the EPA’s Guideline on                  2.6.1.2 of the August 23, 2010
                                                  desirability of accommodating real
                                                                                                           Air Quality Models (40 CFR part 51,                   clarification memo on ‘‘Applicability of
                                                  world emissions variability without
                                                                                                           appendix W).6 In 2005, the EPA                        Appendix W Modeling Guidance for the
                                                  significant risk of violations, are also
                                                                                                           promulgated AERMOD as the Agency’s                    1-hr SO2 National Ambient Air Quality
                                                  appropriate factors for EPA to consider
                                                                                                           preferred near-field dispersion modeling              Standard’’ (U.S. EPA, 2010a).
                                                  when evaluating whether a plan
                                                                                                           for a wide range of regulatory
                                                  provides a reasonable degree of                                                                                II. Pennsylvania’s Attainment Plan
                                                                                                           applications addressing stationary
                                                  confidence that the plan will lead to                    sources (for example in estimating SO2                Submittal for the Indiana Area
                                                  attainment. Based on these                               concentrations) in all types of terrain                  In accordance with section 172(c) of
                                                  considerations, especially given the                     based on extensive developmental and                  the CAA, the Pennsylvania attainment
                                                  high likelihood that a continuously                      performance evaluation. Supplemental                  plan for the Indiana Area includes: (1)
                                                  enforceable limit averaged over as long                  guidance on modeling for purposes of                  An emissions inventory for SO2 for the
                                                  as 30 days, determined in accordance                     demonstrating attainment of the SO2                   plan’s base year (2011); and (2) an
                                                  with EPA’s guidance, will result in                      standard is provided in Appendix A to                 attainment demonstration. The
                                                  attainment, EPA believes as a general                    the 2014 SO2 Nonattainment Guidance.                  attainment demonstration includes the
                                                  matter that such limits, if appropriately                Appendix A provides extensive                         following: Analyses that locate, identify,
                                                  determined, can reasonably be                            guidance on the modeling domain, the                  and quantify sources of emissions
                                                  considered to provide for attainment of                  source inputs, assorted types of                      contributing to violations of the 2010
                                                  the 2010 SO2 NAAQS.                                      meteorological data, and background                   SO2 NAAQS; a determination that the
                                                     The 2014 SO2 Nonattainment                            concentrations. Consistency with the                  control strategy for the primary SO2
                                                  Guidance offers specific                                 recommendations in this guidance is                   sources within the nonattainment areas
                                                  recommendations for determining an                       generally necessary for the attainment                constitutes RACM/RACT; a dispersion
                                                  appropriate longer term average limit.                   demonstration to offer adequately                     modeling analysis of an emissions
                                                  The recommended method starts with                       reliable assurance that the plan provides             control strategy for the primary SO2
                                                  determination of the 1-hour emission                     for attainment.                                       sources (Keystone, Conemaugh, Homer
                                                  limit that would provide for attainment                    As stated previously, attainment                    City, and Seward), showing attainment
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                                                  (i.e., the critical emission value), and                 demonstrations for the 2010 1-hour                    of the SO2 NAAQS by the October 4,
                                                  applies an adjustment factor to                                                                                2018, attainment date; requirements for
                                                  determine the (lower) level of the longer                  5 For example, if the critical emission value is    RFP toward attaining the SO2 NAAQS
                                                  term average emission limit that would                   1000 pounds of SO2 per hour, and a suitable           in the Area; contingency measures; the
                                                  be estimated to have a stringency                        adjustment factor is determined to be 70 percent,     assertion that Pennsylvania’s existing
                                                                                                           the recommended longer term average limit would
                                                  comparable to the otherwise necessary                    be 700 pounds per hour.                               SIP-approved NSR program meets the
                                                  1-hour emission limit. This method uses                    6 The EPA published revisions to the Guideline      applicable requirements for SO2; and
                                                  a database of continuous emission data                   on Air Quality Models on January 17, 2017.            the request that emission limitations


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                                                  32610                      Federal Register / Vol. 83, No. 135 / Friday, July 13, 2018 / Proposed Rules

                                                  and compliance parameters for                            Reporting Requirements (AERR) at                             preliminary determination that this
                                                  Keystone, Conemaugh, Homer City, and                     Subpart A to 40 CFR part 51.7                                inventory was developed in a manner
                                                  Seward be incorporated into the SIP.                        For the base year inventory of actual                     consistent with EPA’s guidance.
                                                                                                           emissions, a ‘‘comprehensive, accurate                       Therefore, pursuant to section 172(c)(3),
                                                  III. EPA’s Analysis of Pennsylvania’s                    and current’’ inventory can be                               EPA is proposing to approve
                                                  Attainment Plan for the Indiana Area                     represented by a year that contributed to                    Pennsylvania’s 2011 base year
                                                                                                           the three-year design value used for the                     emissions inventory for the Indiana
                                                     Consistent with CAA requirements
                                                                                                           original nonattainment designation. The                      Area as it meets CAA requirements.
                                                  (see section 172), an attainment
                                                                                                           2014 SO2 Nonattainment Guidance                                The attainment demonstration also
                                                  demonstration for an SO2 nonattainment
                                                                                                           notes that the base year inventory                           provides for a projected attainment year
                                                  area must include a showing that the
                                                                                                           should include all sources of SO2 in the                     inventory that includes estimated
                                                  area will attain the 2010 SO2 NAAQS as
                                                                                                           nonattainment area as well as any                            emissions for all emission sources of
                                                  expeditiously as practicable. The                        sources located outside the                                  SO2 which are determined to impact the
                                                  demonstration must also meet the                         nonattainment area which may affect                          nonattainment area for the year in
                                                  requirements of 40 CFR 51.112 and 40                     attainment in the area. Pennsylvania                         which the area is expected to attain the
                                                  CFR part 51, Appendix W, and include                     appropriately elected to use 2011 as the                     NAAQS. Pennsylvania provided a 2018
                                                  inventory data, modeling results, and                    base year as the designation of                              projected emissions inventory for all
                                                  emissions reductions analyses on which                   nonattainment was based on data from                         known sources included in the 2011
                                                  the state has based its projected                        2009–2011. Actual emissions from all                         base year inventory. The projected 2018
                                                  attainment. EPA is proposing that the                    the sources of SO2 in the Indiana Area                       emissions are shown in Table 2.
                                                  attainment plan submitted by                             were reviewed and compiled for the                           Pennsylvania’s submittal asserts that the
                                                  Pennsylvania meets all applicable                        base year emissions inventory                                SO2 emissions are expected to decrease
                                                  requirements of the CAA, and EPA is                      requirement. The primary SO2-emitting                        by approximately 75,340 tons, or 40%,
                                                  proposing to approve the plan                            point sources located within the Indiana                     by 2018 from the 2011 base year. More
                                                  submitted by Pennsylvania to ensure                      Area are Keystone, Conemaugh, Homer                          information about the projected
                                                  ongoing attainment in the Indiana Area.                  City, and Seward, all coal-fired power                       emissions for the Indiana Area can be
                                                  A. Pollutants Addressed                                  plants. Keystone and Conemaugh each                          found in Pennsylvania’s October 11,
                                                                                                           have two pulverized coal-fired (PC)                          2017, submittal which can be found
                                                     Pennsylvania’s SO2 attainment plan                    boilers; Homer City has three coal-fired                     under Docket ID No. EPA–R03–OAR–
                                                  evaluates SO2 emissions for the Indiana                  boilers; and Seward has two circulating                      2017–0615 and online at
                                                  Area comprised of Indiana County and                     fluidized bed (CFB) waste coal-fired                         www.regulations.gov.
                                                  a portion of Armstrong County                            boilers. More information about the
                                                  (Plumcreek Township, South Bend                          emissions inventory for the Indiana                            TABLE 2—2018 ANTICIPATED ACTUAL
                                                  Township, and Elderton Borough) that                     Area (and analysis of the inventory) can                        PROJECTED SO2 EMISSION INVEN-
                                                  is designated nonattainment for the                      be found in Pennsylvania’s October 11,                          TORY FOR THE INDIANA AREA
                                                  2010 SO2 NAAQS. There are no                             2017, submittal as well as EPA’s
                                                  precursors to consider for the SO2                       emissions inventory Technical Support                                                                     SO2 Emissions
                                                                                                                                                                          Emission source category
                                                  attainment plan. SO2 is a pollutant that                 Document (TSD), which can be found                                                                            (tpy)
                                                  arises from direct emissions, and                        under Docket ID No. EPA–R03–OAR–
                                                                                                           2017–0615 and online at                                      Point ....................................      68,545.292
                                                  therefore concentrations are highest
                                                                                                           www.regulations.gov.                                         Area ....................................          944.688
                                                  relatively close to the sources and much                                                                              Non-road .............................               0.460
                                                  lower at greater distances due to                           Table 1 shows the level of emissions,
                                                                                                                                                                        On-road ...............................              3.260
                                                  dispersion. Thus, SO2 concentration                      expressed in tons per year (tpy), in the                     Total ....................................      69,493.700
                                                  patterns resemble those of other directly                Indiana Area for the 2011 base year by
                                                  emitted pollutants like lead, and differ                 emissions source category. The point                         C. Air Quality Modeling
                                                  from those of photochemically-formed                     source category includes all sources
                                                                                                           within the Area.                                                The SO2 attainment demonstration
                                                  (secondary) pollutants such as ozone.
                                                                                                                                                                        provides air quality dispersion
                                                  Pennsylvania’s attainment plan
                                                                                                                TABLE 1—2011 BASE YEAR SO2                              modeling analyses to demonstrate that
                                                  appropriately considered SO2 emissions
                                                                                                                EMISSIONS INVENTORY FOR THE IN-                         control strategies chosen to reduce SO2
                                                  for the Indiana Area.
                                                                                                                DIANA AREA
                                                                                                                                                                        source emissions will bring the Area
                                                  B. Emissions Inventory Requirements                                                                                   into attainment by the statutory
                                                                                                                                                        SO2 Emissions   attainment date of October 4, 2018. The
                                                     States are required under section                      Emission source category                                    modeling analyses, conducted pursuant
                                                                                                                                                            (tpy)
                                                  172(c)(3) of the CAA to develop                                                                                       to recommendations outlined in
                                                  comprehensive, accurate and current                      Point ....................................     144,269.017   Appendix W to 40 CFR part 51 (EPA’s
                                                  emissions inventories of all sources of                  Area ....................................          555.610   Modeling Guidance), are used to assess
                                                  the relevant pollutant or pollutants in                  Non-road .............................               1.025
                                                                                                           On-road ...............................              7.730
                                                                                                                                                                        the control strategy for a nonattainment
                                                  the nonattainment area. These                                                                                         area and establish emission limits that
                                                                                                           Total ....................................     144,833.382
                                                  inventories provide detailed accounting                                                                               will provide for attainment. The
                                                  of all emissions and emissions sources                     EPA has evaluated Pennsylvania’s                           analysis requires five years of
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                                                  by precursor or pollutant. In addition,                  2011 base year emissions inventory for                       meteorological data to simulate the
                                                  inventories are used in air quality                      the Indiana Area and has made the                            dispersion of pollutant plumes from
                                                  modeling to demonstrate that                                                                                          multiple point, area, or volume sources
                                                  attainment of the NAAQS is as                              7 The AERR at Subpart A to 40 CFR part 51 cover            across the averaging times of interest.
                                                  expeditious as practicable. The SO2                      overarching federal reporting requirements for the           The modeling demonstration typically
                                                  Nonattainment Guidance provides that                     states to submit emissions inventories for criteria          also relies on maximum allowable
                                                                                                           pollutants to EPA’s Emissions Inventory System.
                                                  the emissions inventory should be                        EPA uses these submittals, along with other data             emissions from sources in the
                                                  consistent with the Air Emissions                        sources, to build the National Emissions Inventory.          nonattainment area. Though the actual


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                                                                                    Federal Register / Vol. 83, No. 135 / Friday, July 13, 2018 / Proposed Rules                                                                       32611

                                                  emissions are likely to be below the                                  EPA has completed a review and                                         the modeling domains. One domain
                                                  allowable emissions, sources have the                                 determined that the AERMOIST                                           included portions of Armstrong County
                                                  ability to run at higher production rates                             procedure is not an appropriate option                                 which only addressed emissions from
                                                  or optimize controls such that emissions                              for use in the Indiana attainment plan                                 Keystone as a source. The other domain
                                                  approach the allowable emissions                                      for the following reasons: (1) There is no                             covered all of Indiana County and
                                                  limits. A modeling analysis that                                      multi-monitor database of SO2                                          addressed emissions from all four
                                                  provides for attainment under all                                     monitoring data available for the four                                 sources in the nonattainment area. For
                                                  scenarios of operation for each source                                major sources of SO2 in the Indiana                                    both domains, background
                                                  must therefore consider the worst case                                Area to conduct a source-specific                                      concentrations included impacts from
                                                  scenario of both the meteorology (e.g.                                statistical test to determine if
                                                                                                                                                                                               non-modeled sources. Each separate
                                                  predominant wind directions,                                          AERMOIST provides a definitive
                                                                                                                                                                                               model domain used its own (different)
                                                  stagnation, etc.) and the maximum                                     improvement over the current
                                                  allowable emissions.                                                  regulatory default version of AERMOD;                                  background concentration.
                                                     PADEP provided two sets of modeling                                (2) AERMOIST was universally applied                                     AERMOD was used to determine the
                                                  analyses: One analysis was developed in                               to all the major sources in the Indiana                                critical emission values (CEV) for
                                                  accordance with EPA’s Modeling                                        Area regardless of whether the source                                  Conemaugh, Keystone, and Seward
                                                  Guidance and the 2014 SO2                                             plumes are actually saturated; and (3)                                 where the modeled 1-hour emission
                                                  Nonattainment Guidance, and was                                       there is a lack of supporting analysis for                             rates demonstrate compliance with the
                                                  prepared using the default option in                                  using relative humidity measurements                                   2010 1-hour SO2 NAAQS. The SO2
                                                  EPA’s preferred dispersion modeling                                   in AERMOIST. For these reasons, EPA                                    emission rates for Homer City were
                                                  system, AERMOD; a second modeling                                     is rejecting the AERMOIST modeling                                     based on the unit 1, unit 2, and unit 3
                                                  analysis also utilized AERMOD but                                     analysis for the Indiana Area attainment                               combined mass-based SO2 emission
                                                  included a procedure called                                           plan. A detailed discussion of the                                     limits established in Plan Approval 32–
                                                  AERMOIST, an alternative model option                                 deficiencies of the AERMOIST modeling                                  00055H,8 which authorized the
                                                  which accounts for additional plume                                   analysis submitted for the Indiana Area                                installation of Novel Integrated
                                                  rise associated with the latent heat                                  can be found in EPA’s AERMOIST                                         Desulfurization (NID) systems, often
                                                  release of condensation due to moisture                               modeling TSD for the Indiana which
                                                  in a stack’s plume. AERMOIST is                                                                                                              referred to as Dry Flue Gas
                                                                                                                        can be found under Docket ID No. EPA–
                                                  currently not approved by EPA for                                                                                                            Desulphurization (FGD) systems on unit
                                                                                                                        R03–OAR–2017–0615 and available
                                                  regulatory use. A more detailed                                       online at www.regulations.gov.                                         1 and unit 2. This 1-hour SO2 limit was
                                                  discussion of PADEP’s modeling                                           EPA has reviewed the default                                        based on air dispersion modeling that
                                                  analysis for the Indiana Area can be                                  AERMOD analysis without the                                            demonstrated compliance with the 2010
                                                  found in Pennsylvania’s October 11,                                   AERMOIST module submitted for the                                      1-hour SO2 NAAQS. The CEV rates used
                                                  2017 submittal.                                                       Indiana Area. The Indiana Area was                                     in the demonstration analysis for each
                                                     In addition to submitting the Indiana                              divided into two separate modeling                                     of the four sources are summarized in
                                                  Area attainment plan to EPA on October                                domains. Refer to EPA’s Modeling TSD                                   the following table. The modeled
                                                  11, 2017, PADEP also submitted a                                      for the Indiana Area under Docket ID                                   emission rate in grams per second was
                                                  request to EPA to review AERMOIST for                                 EPA–R03–OAR–2017–0615, available at                                    converted to pounds per hour, which is
                                                  use in the Indiana Area attainment plan.                              www.regulations.gov for EPA’s review of                                the CEV limit.9

                                                                            TABLE 3—CRITICAL EMISSION VALUES FROM INDIANA, PA SIP MODELING DEMONSTRATION
                                                                                                                                                                                                                    Modeled rate   CEV limit
                                                                                                                            Facility                                                                                   (g/s)        (lbs/hr)

                                                  Conemaugh Generating Station ..............................................................................................................................             426.00       3,381.00
                                                  Homer City Generating Station, Unit 1 ....................................................................................................................              195.30       1,550.02
                                                  Homer City Generating Station, Unit 2 ....................................................................................................................              195.30       1,550.02
                                                  Homer City Generating Station, Unit 3 ....................................................................................................................              410.76       3,260.02
                                                  Keystone Generating Station ...................................................................................................................................       1,223.58       9,711.10
                                                  Seward Generating Station .....................................................................................................................................         640.00       5,079.44



                                                    Using the EPA conversion factor for                                 for Keystone and Seward that would                                     When determining longer term emission
                                                  the SO2 NAAQS, the final 1-hour CEV                                   provide for attainment of the NAAQS.                                   limits, EPA’s 2014 SO2 Nonattainment
                                                  model run design values for the                                       EPA’s 2014 SO2 Nonattainment                                           Guidance states,
                                                  Armstrong County portion (196.28 mg/                                  Guidance and Section I of this proposed                                  ‘‘[T]he EPA is not precluding states from
                                                  m3) and the Indiana County portion                                    rulemaking provide an extensive                                        using other approaches to determine
                                                  (196.44 mg/m3) of the Indiana Area are                                discussion of EPA’s rationale for                                      appropriate longer term average limits.
                                                  less than 75 ppb.10                                                   concluding that emission limits that are                               However, the EPA would recommend in all
                                                                                                                                                                                               cases that the analysis begin with
                                                    PADEP also provided air dispersion                                  appropriately set based on averaging
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                                                                                                                                                                                               determination of the critical emission values.
                                                  modeling with randomly reassigned                                     times longer than 1 hour and up to as                                  A comparison of the 1-hour limit and the
                                                  emissions (RRE) to provide support for                                long as 30 days can be found to provide                                proposed longer term limit, in particular an
                                                  establishing longer term emission limits                              for attainment of the 2010 SO2 NAAQS.                                  assessment of whether the longer term

                                                     8 Plan Approval 32–00055H was issued on April                        10 The SO NAAQS level is expressed in ppb but                          See Pennsylvania’s SO2 Round 3 Designations
                                                                                                                                     2
                                                  2, 2012, and modified on April 4, 2013, by the DEP.                   AERMOD gives results in mg/m3. The conversion                          Proposed Technical Support Document at https://
                                                     9 Based on the National Institute of Standards and                 factor for SO2 (at the standard conditions applied                     www.epa.gov/sites/production/files/2017-08/
                                                  Technology conversion: 1 pound = 453.59237                            in the ambient SO2 reference method) is 1ppb =                         documents/35_pa_so2_rd3-final.pdf.
                                                  grams.                                                                approximately 2.619 mg/m3.



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                                                  32612                             Federal Register / Vol. 83, No. 135 / Friday, July 13, 2018 / Proposed Rules

                                                  average limit may be considered to be of                              discussion of the RRE modeling is                                   necessary or appropriate to provide for
                                                  comparable stringency to a 1-hour limit at the                        provided in EPA’s Modeling TSD for the                              NAAQS attainment. EPA interprets
                                                  critical emission value, would be a critical                          Indiana Area under Docket ID EPA–                                   RACM, including RACT, under section
                                                  element of a demonstration that any longer
                                                                                                                        R03–OAR–2017–0615, available at                                     172, as measures that a state determines
                                                  term average limits in the SIP will help
                                                  provide adequate assurance that the plan will                         www.regulations.gov.                                                to be both reasonably available and
                                                  provide for attainment and maintenance of                                EPA has reviewed the modeling that                               contribute to attainment as
                                                  the 1-hour NAAQS.’’                                                   Pennsylvania submitted to support the                               expeditiously as practicable ‘‘for
                                                                                                                        attainment demonstration for the                                    existing sources in the area.’’
                                                     As discussed in the RACM/RACT                                      Indiana Area and has determined that
                                                  section below, a 24-hour block average                                                                                                       Pennsylvania’s October 11, 2017,
                                                                                                                        the default AERMOD modeling is                                      submittal discusses federal and state
                                                  SO2 emission limit for Keystone and a                                 consistent with CAA requirements,
                                                  rolling 30-day average SO2 emission                                                                                                       measures that Pennsylvania asserts will
                                                                                                                        Appendix W to 40 CFR part 51, and                                   provide emission reductions leading to
                                                  limit for Seward were developed by                                    EPA’s 2014 SO2 Guidance for SO2
                                                  conducting additional modeling with                                                                                                       attainment and maintenance of the 2010
                                                                                                                        attainment demonstration modeling.                                  SO2 NAAQS. With regards to state rules,
                                                  SO2 emissions distributions                                           Because the AERMOD analysis
                                                  representative of future operations                                                                                                       Pennsylvania cites its low sulfur fuel
                                                                                                                        employing AERMOIST has not been                                     rules, which were SIP-approved on July
                                                  which were derived for each facility by                               approved by EPA for use in the
                                                  evaluating emissions for 2014–2016. For                                                                                                   10, 2014 (79 FR 39330). Pennsylvania’s
                                                                                                                        attainment demonstration for the
                                                  each facility, the emissions were                                                                                                         low sulfur fuel oil provisions apply to
                                                                                                                        Indiana Area, EPA is not proposing to
                                                  randomly reassigned to develop 100                                                                                                        refineries, pipelines, terminals, retail
                                                                                                                        approve the modeling submitted by
                                                  hourly emission files for use in 100                                                                                                      outlet fuel storage facilities, commercial
                                                                                                                        PADEP which employed AERMOIST.
                                                  AERMOD simulations. These AERMOD                                                                                                          and industrial facilities, and facilities
                                                                                                                        EPA is proposing to approve the default
                                                  simulations included CEV rates for three                                                                                                  with units burning regulated fuel oil to
                                                                                                                        non-AERMOIST modeling, including
                                                  facilities, and hourly emissions for                                                                                                      produce electricity and domestic home
                                                                                                                        the CEV and RRE simulations, provided
                                                  either Seward or Keystone. EPA believes                                                                                                   heaters. These low sulfur fuel oil rules
                                                                                                                        in the attainment plan and EPA believes
                                                  that the distribution of emissions                                                                                                        reduce the amount of sulfur in fuel oils
                                                                                                                        that the modeling reasonably
                                                  modeled in the 100 RRE methodology,                                   demonstrates that the Indiana Area will                             used in combustion units, thereby
                                                  which were based on historical                                        attain the 2010 1-hour primary SO2                                  reducing SO2 emissions and the
                                                  operating levels and scaled to conform                                NAAQS by the attainment date.                                       formation of sulfates that cause
                                                  with the longer term limits, are a                                                                                                        decreased visibility.
                                                  reasonable representation of an                                       D. RACM/RACT                                                           Pennsylvania’s submittal discusses
                                                  allowable emissions distribution for                                    CAA section 172(c)(1) requires that                               that the main SO2 emitting sources at
                                                  both Seward and Keystone. EPA                                         each attainment plan provide for the                                Conemaugh, Homer City, Keystone, and
                                                  believes that the 100 RRE analyses and                                implementation of all reasonably                                    Seward are all equipped with FGD
                                                  model results for Keystone and Seward                                 available control measures (i.e., RACM)                             systems (wet limestone scrubbers, dry
                                                  provide adequate assurance that the                                   as expeditiously as practicable and shall                           FGD, or in-furnace limestone injection
                                                  longer term emission limits for both of                               provide for attainment of the NAAQS.                                systems) to reduce SO2 emissions. Table
                                                  these facilities will result in attainment                            Section 172(c)(6) requires SIPs to                                  4 lists the control technology at each of
                                                  of the 2010 SO2 NAAQS by the                                          contain enforceable emission limitations                            the main SO2 emitting sources at each
                                                  attainment date. A more detailed                                      and control measures as may be                                      facility.

                                                                          TABLE 4—CONTROL TECHNOLOGY AT THE FOUR MAJOR SO2 SOURCES IN THE INDIANA AREA
                                                                                                                                                                                                                                           Control
                                                                          Facility                                                        Unit                                                  SO2 control                              installation
                                                                                                                                                                                                                                            date

                                                  Conemaugh .............................................        031—Main Boiler 1 ..................................       Wet limestone scrubber ..........................                  ∼1994
                                                                                                                 031—Main Boiler 2 ..................................       Wet limestone scrubber ..........................                  ∼1995
                                                  Homer City ...............................................     031—Boiler 1 ...........................................   Dry FGD ..................................................    11/18/2015
                                                                                                                 032—Boiler 2 ...........................................   Dry FGD ..................................................     5/23/2016
                                                                                                                 033—Boiler 3 ...........................................   Wet limestone scrubber ..........................                  ∼2002
                                                  Keystone ..................................................    031—Boiler 1 ...........................................   Wet limestone scrubber ..........................              9/24/2009
                                                                                                                 032—Boiler 2 ...........................................   Wet limestone scrubber ..........................             11/22/2009
                                                  Seward .....................................................   034—CFB Boiler 1 ..................................        In-furnace limestone injection .................                   ∼2004
                                                                                                                 035—CFB Boiler 2 ..................................        In-furnace limestone injection .................                   ∼2004



                                                    With these controls installed,                                      and in the Modeling TSD. In order to                                Conemaugh determined by the
                                                  Pennsylvania’s submittal discusses                                    ensure that the Indiana Area                                        modeling as necessary for SO2
                                                  facility-specific control measures,                                   demonstrates attainment with the SO2                                attainment would be less stringent;
                                                  namely SO2 emission limits for                                        NAAQS, PADEP asserts that the                                          • Seward’s current SO2 emission
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                                                  Conemaugh, Homer City, and Seward,                                    following combination of emission                                   limit in TVOP 32–00040 because the
                                                  and new SO2 emission limits for                                       limits at the four facilities is sufficient                         emission limits for Seward determined
                                                  Keystone. Keystone’s new limits were                                  for the Indiana Area to meet the SO2                                by the modeling as necessary for SO2
                                                  developed through air dispersion                                      NAAQS and serve as RACM/RACT:                                       attainment would be less stringent;
                                                  modeling (default AERMOD) submitted                                     • Conemaugh’s current SO2 emission                                   • Homer City’s current SO2 emission
                                                  by PADEP. The modeling analysis is                                    limits contained in the Title V                                     limits established in Plan Approval 32–
                                                  discussed in section III.C. Air Quality                               Operating Permit (TVOP) 32–00059                                    00055H and Plan Approval 32–00055I;
                                                  Modeling of this proposed rulemaking                                  because the emission limits for                                     and


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                                                                                    Federal Register / Vol. 83, No. 135 / Friday, July 13, 2018 / Proposed Rules                                                                            32613

                                                   • A new, more stringent combined                                      and Unit 2 of 9,600 pounds per hour                                      The emission limits for each of the
                                                  SO2 emission limit for Keystone Unit 1                                 (lbs/hr) block 24-hour average limit.                                  SO2-emitting facilities are listed in
                                                                                                                                                                                                Table 5.

                                                                                                    TABLE 5—SO2 EMISSION LIMITS FOR INDIANA AREA FACILITIES
                                                                                                                                                                                           Emission limit
                                                                        Facility                                            Source description                                                                                Averaging period
                                                                                                                                                                                             (lbs/hr)

                                                  Conemaugh .........................................        Unit   1   ...................................................   1,656 (TVOP 32–00059) .....................   3-hour block.
                                                                                                             Unit   2   ...................................................
                                                  Homer City ...........................................     Unit   1   ...................................................   6,360 (Plan Approval 32–00055H) and           1-hour block.
                                                                                                             Unit   2   ...................................................     limits specified in Plan Approval 32–
                                                                                                             Unit   3   ...................................................     00055I.
                                                  Keystone ..............................................    Unit   1   ...................................................   9,600 (New limit based on default             24-hour block.
                                                                                                             Unit   2   ...................................................     AERMOD).
                                                  Seward .................................................   Unit   1   ...................................................   3,038.4 (TVOP 32–00040) ..................    30-day rolling.
                                                                                                             Unit   2   ...................................................



                                                     The emission limits for Conemaugh,                                  respective facility (see Appendices B–1                                limitation and control measures
                                                  Keystone and Seward have averaging                                     through B–4 of the October 11, 2017,                                   requirements of section 172(c)(6) of the
                                                  times greater than 1-hour (ranging                                     SIP submittal). The collective emission                                CAA.
                                                  between three hours and 30 days). The                                  limits and all related compliance
                                                                                                                                                                                                E. RFP Plan
                                                  default non-AERMOIST modeling                                          parameters (i.e. the measures which
                                                  analysis for the Indiana Area was used                                 include system audits, record-keeping                                     Section 172(c)(2) of the CAA requires
                                                  to establish CEVs for each facility. These                             and reporting, and corrective actions)                                 that an attainment plan includes a
                                                  (1-hour) CEVs were used for developing                                 have been proposed for incorporation                                   demonstration that shows reasonable
                                                  longer than 1-hour emission limits for                                 into the SIP to make these changes                                     further progress (i.e., RFP) for meeting
                                                  Seward, Conemaugh, and Keystone. SO2                                   permanently federally enforceable.                                     air quality standards will be achieved
                                                  limits at Conemaugh are set to a 3-hour                                PADEP affirms that the implementation                                  through generally linear incremental
                                                  block average. This average is roughly in                              of existing and new emission limits and                                improvement in air quality. Section
                                                  line with the CEV modeled limit and the                                corresponding compliance parameters                                    171(1) of the CAA defines RFP as ‘‘such
                                                  ratio from Appendix C in EPA’s 2014                                    for the four EGUs will enable the                                      annual incremental reductions in
                                                  SO2 Nonattainment Guidance.                                            Indiana Area to attain and maintain the                                emissions of the relevant air pollutant as
                                                  Keystone’s limits were set to a 24-hour                                SO2 NAAQS.                                                             are required by this part (part D) or may
                                                  block average based on the 100 RRE                                        EPA is proposing to approve                                         reasonably be required by EPA for the
                                                  simulation method discussed in Section                                 Pennsylvania’s determination that the                                  purpose of ensuring attainment of the
                                                  III.C. Air Quality Modeling in this                                    proposed SO2 control strategy at                                       applicable NAAQS by the applicable
                                                  proposed rulemaking. A similar                                         Keystone, Conemaugh, Homer City, and                                   attainment date.’’ As stated in the 1994
                                                  approach was used to establish a 30-day                                Seward constitutes RACM/RACT for                                       SO2 Guidelines Document 11 and
                                                  rolling average for Seward. Appendices                                 each SO2 source in the Indiana Area                                    repeated in the 2014 SO2 Nonattainment
                                                  C–1a and C–4 of Pennsylvania’s October                                 based on the modeling analysis                                         Guidance, EPA continues to believe that
                                                  11, 2017 SIP submittal provide a                                       previously described. EPA finds                                        this definition is most appropriate for
                                                  detailed explanation of the longer term                                Pennsylvania’s control strategy for                                    pollutants that are emitted from
                                                  emission limits. EPA believes the 100                                  RACM/RACT including emission limits                                    numerous and diverse sources, where
                                                  RRE iteration approach used in                                         and compliance parameters for the four                                 the relationship between particular
                                                  Pennsylvania’s submittal for                                           EGUs will enable the Indiana Area to                                   sources and ambient air quality are not
                                                  determining longer term emission limits                                attain and maintain the NAAQS.                                         directly quantified. In such cases,
                                                  for Seward and Keystone can be used to                                    Furthermore, PADEP requests that the                                emissions reductions may be required
                                                  demonstrate compliance with the 2010                                   unredacted portions of the COAs, COs,                                  from various types and locations of
                                                  SO2 NAAQS. EPA’s analysis of the                                       Plan Approvals, and TVOP submitted                                     sources. The relationship between SO2
                                                  default AERMOD modeling analysis                                       by PADEP with the attainment plan be                                   and sources is much more defined, and
                                                  using longer term emission limits                                      approved into the Pennsylvania SIP.                                    usually there is a single step between
                                                  shows, as discussed in detail in the                                   Including the emission limits listed in                                pre-control nonattainment and post-
                                                  Modeling TSD, that the emission limits                                 the CO for Keystone, the Plan Approval                                 control attainment. Therefore, EPA
                                                  listed in Table 5 are sufficient for the                               for Homer City, and the TVOPs for                                      interpreted RFP for SO2 as adherence to
                                                  Indiana Area to attain the 1-hour SO2                                  Conemaugh and Seward (see Table 4),                                    an ambitious compliance schedule in
                                                  NAAQS. EPA’s analysis of the longer                                    and corresponding compliance                                           both the 1994 SO2 Guideline Document
                                                  term emission limits is discussed in                                   parameters found in the COAs and COs                                   and the 2014 SO2 Nonattainment
                                                  more detail in the Modeling TSD for the                                for Keystone, Conemaugh, Homer City,                                   Guidance. EPA finds the control
                                                  Indiana Area under Docket ID EPA–                                      and Seward in the Pennsylvania SIP                                     measures included in Pennsylvania’s
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                                                  R03–OAR–2017–0615, available at                                        means that these measures will become                                  submittal demonstrate attainment for
                                                  www.regulations.gov.                                                   permanent and enforceable SIP                                          the Area with the 2010 SO2 NAAQS
                                                     The emission limits or compliance                                   measures to meet the requirements of                                   based on the modeling submitted by
                                                  parameters, such as contingency                                        the CAA. EPA, therefore, proposes to
                                                  measures, or both, were established                                    approve Pennsylvania’s October 11,                                       11 SO Guideline Document, U.S. Environmental
                                                                                                                                                                                                        2
                                                                                                                                                                                                Protection Agency, Office of Air Quality Planning
                                                  through Consent Orders and                                             2017 SIP submittal as meeting the                                      and Standards, Research Triangle Park, N.C. 27711,
                                                  Agreements (COAs) and Consent Orders                                   RACM/RACT requirements of section                                      EPA–452/R–94–008, February 1994. Located at:
                                                  (COs) between PADEP and the                                            172(c)(1) and the enforceable emission                                 http://www.epa.gov/ttn/oarpg/t1pgm.html.



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                                                  32614                      Federal Register / Vol. 83, No. 135 / Friday, July 13, 2018 / Proposed Rules

                                                  Pennsylvania. The permits and                            within 15 days, and corrective actions                for the construction and operation of
                                                  compliance orders submitted by                           shall be identified by PADEP as                       new or modified major stationary
                                                  Pennsylvania for inclusion in the SIP                    necessary; and (2) Upon execution of                  sources in a nonattainment area.
                                                  require these control measures and                       the COA or CO, if the Strongstown                     Pennsylvania has a fully implemented
                                                  resulting emission reductions to be                      monitor (ID 42–063–0004) measures a 1-                Nonattainment New Source Review
                                                  achieved as expeditiously as                             hour concentration exceeding 75 ppb,                  (NNSR) program for criteria pollutants
                                                  practicable. As a result, based on air                   PADEP will notify the facility in the                 in 25 Pennsylvania Code Chapter 127,
                                                  quality modeling reviewed by EPA, this                   Area, and the facility in the Area is                 Subchapter E, which was approved into
                                                  is projected to yield a sufficient                       required to identify whether any of the               the Pennsylvania SIP on December 9,
                                                  reduction in SO2 emissions from the                      SO2-emitting sources at the respective                1997 (62 FR 64722). On May 14, 2012
                                                  major sources in the Indiana Area                        facility were running at the time of the              (77 FR 28261), EPA approved a SIP
                                                  resulting in modeled attainment of the                   exceedance, and within a reasonable                   revision pertaining to the pre-
                                                  SO2 NAAQS for the Indiana Area.                          time period leading up to the                         construction permitting requirements of
                                                  Therefore, EPA has determined that                       exceedance, not to exceed 24 hours. If                Pennsylvania’s NNSR program to
                                                  PADEP’s SO2 attainment plan for the                      any of the SO2-emitting sources were                  update the regulations to meet EPA’s
                                                  Indiana Area fulfills the RFP                            running at the time of the exceedance,                2002 NSR reform regulations. EPA then
                                                  requirements for the Indiana Area. EPA                   the facility must then analyze the                    approved an update to Pennsylvania’s
                                                  does not anticipate future                               meteorological data on the day the daily              NNSR regulations on July 13, 2012 (77
                                                  nonattainment, or that the Area will not                 exceedance occurred to ensure that the                FR 41276). These rules provide for
                                                  attain the NAAQS by the October 4,                       daily exceedance was not due to SO2                   appropriate NSR as required by CAA
                                                  2018 attainment date. EPA proposes to                    emissions from the respective facility.               sections 172(c)(5) and 173 and 40 CFR
                                                  approve Pennsylvania’s attainment plan                   The facility’s findings must be                       51.165 for SO2 sources undergoing
                                                  with respect to the RFP requirements.                    submitted to PADEP within 30 days of                  construction or major modification in
                                                                                                           being notified of the exceedance.                     the Indiana Area without need for
                                                  F. Contingency Measures
                                                                                                             Additionally, if PADEP identifies a                 modification of the approved rules.
                                                     In accordance with section 172(c)(9)                  daily maximum SO2 concentration                       Therefore, EPA concludes that the
                                                  of the CAA, contingency measures are                     exceeding 75 ppb at a PADEP-operated                  Pennsylvania SIP meets the
                                                  required as additional measures to be                    SO2 ambient air quality monitor in the                requirements of section 172(c)(5) for this
                                                  implemented in the event that an area                    Indiana Area, within five days, PADEP                 Area.
                                                  fails to meet the RFP requirements or                    will contact Conemaugh, Homer City,
                                                  fails to attain the standard by its                                                                            IV. EPA’s Proposed Action
                                                                                                           Keystone, and Seward to trigger the
                                                  attainment date. These measures must                     implementation of the daily exceedance                   EPA is proposing to approve
                                                  be fully adopted rules or control                        report contingency measure described                  Pennsylvania’s SIP revision for the
                                                  measures that can be implemented                         in section VIII.C. of the October 11, 2017            Indiana Area, as submitted through
                                                  quickly and without additional EPA or                    submittal. If necessary, section 4(27) of             PADEP to EPA on October 11, 2017, for
                                                  state action if the area fails to meet RFP               the Pennsylvania Air Pollution Control                the purpose of demonstrating
                                                  requirements or fails to meet its                                                                              attainment of the 2010 1-hour SO2
                                                                                                           Act (APCA) authorizes PADEP to take
                                                  attainment date, and should contain                                                                            NAAQS. Specifically, EPA is proposing
                                                                                                           any action it deems necessary or proper
                                                  trigger mechanisms and an                                                                                      to approve the base year emissions
                                                                                                           for the effective enforcement of APCA
                                                  implementation schedule. However,                                                                              inventory, a modeling demonstration of
                                                                                                           and the rules and regulations
                                                  SO2 presents special considerations. As                                                                        SO2 attainment, an analysis of RACM/
                                                                                                           promulgated under APCA. Such actions
                                                  stated in the final 2010 SO2 NAAQS                                                                             RACT, enforceable emission limitations
                                                                                                           include the issuance of orders and the
                                                  promulgation on June 22, 2010 (75 FR                                                                           and control measures, a RFP plan, and
                                                                                                           assessment of civil penalties. A more
                                                  35520) and in the 2014 SO2                                                                                     contingency measures for the Indiana
                                                                                                           detailed description of the contingency
                                                  Nonattainment Guidance, EPA                                                                                    Area and is proposing that the
                                                                                                           measures can be found in section VIII of
                                                  concluded that because of the                                                                                  Pennsylvania SIP has met requirements
                                                  quantifiable relationship between SO2                    the October 11, 2017 submittal as well
                                                                                                                                                                 for NSR for the 2010 1-hour SO2
                                                  sources and control measures, it is                      as the COAs and COs included in the
                                                                                                                                                                 NAAQS. Additionally, EPA is proposing
                                                  appropriate that state agencies develop                  submittal and included for
                                                                                                                                                                 to approve into the Pennsylvania SIP
                                                  a comprehensive program to identify                      incorporation by reference into the SIP.
                                                                                                             EPA is proposing to find that                       specific SO2 emission limits,
                                                  sources of violations of the SO2 NAAQS
                                                                                                           Pennsylvania’s October 11, 2017
                                                  and undertake an aggressive follow-up                                                                          NSR. PSD is established in part C of title I of the
                                                                                                           submittal includes sufficient measures
                                                  for compliance and enforcement.                                                                                CAA and applies in undesignated areas and in areas
                                                     The COAs or COs for Conemaugh,                        to expeditiously identify the source of               that meet the NAAQS—designated ‘‘attainment
                                                  Homer City, Keystone, and Seward (see                    any violation of the SO2 NAAQS and for                areas’’—as well as areas where there is insufficient
                                                                                                           aggressive follow-up including                        information to determine if the area meets the
                                                  Appendices B–1 through B–4 of the                                                                              NAAQS—designated ‘‘unclassifiable areas.’’ The
                                                  October 11, 2017 submittal) each                         enforcement measures within PADEP’s                   NNSR program is established in part D of title I of
                                                  contain the following measures that are                  authority as necessary. Therefore, EPA                the CAA and applies in areas that are not in
                                                  designed to keep the Indiana Area from                   proposes that the contingency measures                attainment of the NAAQS—designated
                                                                                                           submitted by Pennsylvania follow the                  ‘‘nonattainment areas.’’ The Minor NSR program
                                                  triggering an exceedance or violation of                                                                       addresses construction or modification activities
                                                  the SO2 NAAQS: (1) Upon execution of                     2014 SO2 Nonattainment Guidance and                   that do not qualify as ‘‘major’’ and applies
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                                                  the COA or CO, if SO2 emissions from                     meet the section 172(c)(9) requirements.              regardless of the designation of the area in which
                                                                                                                                                                 a source is located. Together, these programs are
                                                  the combined SO2 emitting sources at                     G. New Source Review 12                               referred to as the NSR programs. Section 173 of the
                                                  the facility exceed 99% of the SO2                                                                             CAA lays out the NNSR program for
                                                                                                             Section 172(c)(5) of the CAA requires
                                                  emissions limit for the facility (listed in                                                                    preconstruction review of new major sources or
                                                                                                           that an attainment plan require permits               major modifications to existing sources, as required
                                                  Table 3), within 48 hours the facility is
                                                                                                                                                                 by CAA section 172(c)(5). The programmatic
                                                  required to undertake a full system                        12 The CAA new source review (NSR) program is       elements for NNSR include, among other things,
                                                  audit of the SO2 emitting sources and                    composed of three separate programs: Prevention of    compliance with the lowest achievable emissions
                                                  submit a written report to PADEP                         significant deterioration (PSD), NNSR, and Minor      rate and the requirement to obtain emissions offsets.



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                                                                             Federal Register / Vol. 83, No. 135 / Friday, July 13, 2018 / Proposed Rules                                                 32615

                                                  compliance parameters, and                               of Management and Budget under                           Dated: June 27, 2018.
                                                  contingency measures established for                     Executive Orders 12866 (58 FR 51735,                   Cecil Rodrigues,
                                                  the SO2 sources impacting the Indiana                    October 4, 1993) and 13563 (76 FR 3821,                Acting Regional Administrator, Region III.
                                                  Area.                                                    January 21, 2011);                                     [FR Doc. 2018–14947 Filed 7–12–18; 8:45 am]
                                                     EPA has determined that
                                                                                                              • is not an Executive Order 13771 (82               BILLING CODE 6560–50–P
                                                  Pennsylvania’s SO2 attainment plan for
                                                                                                           FR 9339, February 2, 2017) regulatory
                                                  the 2010 1-hour SO2 NAAQS for Indiana
                                                                                                           action because SIP approvals are
                                                  County meets the applicable
                                                                                                           exempted under Executive Order 12866;                  DEPARTMENT OF COMMERCE
                                                  requirements of the CAA. Thus, EPA is
                                                  proposing to approve Pennsylvania’s                         • does not impose an information
                                                  attainment plan for the Indiana Area as                  collection burden under the provisions                 National Oceanic and Atmospheric
                                                  submitted on October 11, 2017. EPA’s                     of the Paperwork Reduction Act (44                     Administration
                                                  analysis for this proposed action is                     U.S.C. 3501 et seq.);
                                                  discussed in Section III of this proposed                                                                       50 CFR Part 218
                                                                                                              • is certified as not having a
                                                  rulemaking. EPA is soliciting public                     significant economic impact on a                       RIN 0648–XG273
                                                  comments on the issues discussed in                      substantial number of small entities
                                                  this document. These comments will be                    under the Regulatory Flexibility Act (5                Taking and Importing Marine
                                                  considered before taking final action.                   U.S.C. 601 et seq.);                                   Mammals; Taking Marine Mammals
                                                  Final approval of this SIP submittal will                                                                       Incidental to U.S. Navy Operations of
                                                  remove EPA’s duty to promulgate and                         • does not contain any unfunded
                                                                                                           mandate or significantly or uniquely                   Surveillance Towed Array Sensor
                                                  implement a FIP under CAA section                                                                               System Low Frequency Active Sonar
                                                  110(c).                                                  affect small governments, as described
                                                                                                           in the Unfunded Mandates Reform Act                    in the Western and Central North
                                                  V. Incorporation by Reference                            of 1995 (Pub. L. 104–4);                               Pacific Ocean and Eastern Indian
                                                                                                                                                                  Ocean
                                                    In this proposed rule, EPA is                             • does not have federalism
                                                  proposing to include in a final EPA rule                 implications as specified in Executive                 AGENCY:  National Marine Fisheries
                                                  regulatory text that includes                            Order 13132 (64 FR 43255, August 10,                   Service (NMFS), National Oceanic and
                                                  incorporation by reference. In                           1999);                                                 Atmospheric Administration (NOAA),
                                                  accordance with requirements of 1 CFR                                                                           Commerce.
                                                  51.5, EPA is proposing to incorporate by                    • is not an economically significant
                                                                                                           regulatory action based on health or                   ACTION: Receipt of application for
                                                  reference the portions of the COAs or                                                                           rulemaking and letter of authorization;
                                                  COs entered between Pennsylvania and                     safety risks subject to Executive Order
                                                                                                           13045 (62 FR 19885, April 23, 1997);                   request for comments and information.
                                                  Conemaugh, Homer City, Keystone, and
                                                  Seward that are not redacted, as well as                    • is not a significant regulatory action            SUMMARY:   NMFS has received a request
                                                  the unredacted portions of the TVOPs or                  subject to Executive Order 13211 (66 FR                from the U.S. Navy (Navy) for
                                                  Plan Approval included in the October                    28355, May 22, 2001);                                  authorization to take marine mammals
                                                  11, 2017 submittal. These include                           • is not subject to requirements of                 incidental to the use of Surveillance
                                                  emission limits and associated                           Section 12(d) of the National                          Towed Array Sensor Systems Low
                                                  compliance parameters (i.e. the                          Technology Transfer and Advancement                    Frequency Active (SURTASS LFA)
                                                  measures which include system audits,                    Act of 1995 (15 U.S.C. 272 note) because               sonar systems onboard U.S. Navy
                                                  record-keeping and reporting, and                        application of those requirements would                surveillance ships for training and
                                                  corrective actions). EPA has made, and                   be inconsistent with the CAA; and                      testing activities conducted under the
                                                  will continue to make, these materials                                                                          authority of the Secretary of the Navy in
                                                  generally available through http://                         • does not provide EPA with the                     the western and central North Pacific
                                                  www.regulations.gov and at the EPA                       discretionary authority to address, as                 and eastern Indian oceans beginning
                                                  Region III Office (please contact the                    appropriate, disproportionate human                    August 2019. Pursuant to the
                                                  person identified in the FOR FURTHER                     health or environmental effects, using                 implementing regulations of the Marine
                                                  INFORMATION CONTACT section of this                      practicable and legally permissible                    Mammal Protection Act (MMPA), NMFS
                                                  proposed rulemaking for more                             methods, under Executive Order 12898                   is announcing our receipt of the Navy’s
                                                  information).                                            (59 FR 7629, February 16, 1994).                       request for the development and
                                                  VI. Statutory and Executive Order                           In addition, this proposed rule,                    implementation of regulations
                                                  Reviews                                                  concerning the SO2 attainment plan for                 governing the incidental taking of
                                                                                                           the Indiana nonattainment area in                      marine mammals and inviting
                                                    Under the CAA, the Administrator is                    Pennsylvania, does not have tribal                     information, suggestions, and comments
                                                  required to approve a SIP submission                     implications as specified by Executive                 on the Navy’s application and request.
                                                  that complies with the provisions of the                 Order 13175 (65 FR 67249, November 9,                  DATES: Comments and information must
                                                  CAA and applicable federal regulations.                  2000), because the SIP is not approved                 be received no later than August 13,
                                                  42 U.S.C. 7410(k); 40 CFR 52.02(a).                      to apply in Indian country located in the              2018.
                                                  Thus, in reviewing SIP submissions,                      state, and EPA notes that it will not
                                                  EPA’s role is to approve state choices,                  impose substantial direct costs on tribal              ADDRESSES:   Comments on the
                                                  provided that they meet the criteria of                                                                         application should be addressed to Jolie
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                                                                                                           governments or preempt tribal law.
                                                  the CAA. Accordingly, this action                                                                               Harrison, Chief, Permits and
                                                  merely approves state law as meeting                     List of Subjects in 40 CFR Part 52                     Conservation Division, Office of
                                                  federal requirements and does not                                                                               Protected Resources, National Marine
                                                                                                             Environmental protection, Air                        Fisheries Service. Physical comments
                                                  impose additional requirements beyond
                                                                                                           pollution control, Incorporation by                    should be sent to 1315 East-West
                                                  those imposed by state law. For that
                                                                                                           reference, Reporting and recordkeeping                 Highway, Silver Spring, MD 20910–
                                                  reason, this proposed action:
                                                    • Is not a ‘‘significant regulatory                    requirements, Sulfur oxides.                           3225 and electronic comments should
                                                  action’’ subject to review by the Office                      Authority: 42 U.S.C. 7401 et seq.                 be sent to ITP.Youngkin@noaa.gov.


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Document Created: 2018-07-13 01:04:42
Document Modified: 2018-07-13 01:04:42
CategoryRegulatory Information
CollectionFederal Register
sudoc ClassAE 2.7:
GS 4.107:
AE 2.106:
PublisherOffice of the Federal Register, National Archives and Records Administration
SectionProposed Rules
ActionProposed rule.
DatesWritten comments must be received on or before August 13, 2018.
ContactMegan Goold, (215) 814-2027, or by email at [email protected]
FR Citation83 FR 32606 
CFR AssociatedEnvironmental Protection; Air Pollution Control; Incorporation by Reference; Reporting and Recordkeeping Requirements and Sulfur Oxides

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