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[Federal Register Volume 89, Number 238 (Wednesday, December 11, 2024)]
[Proposed Rules]
[Pages 99790-99799]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-28536]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 52 and 81

[EPA-R03-OAR-2024-0316; FRL-11777-01-R3]

Air Plan Approval; Pennsylvania; Redesignation of the Allegheny 
County Nonattainment Area to Attainment and Approval of the Area's 
Maintenance Plan for the 2010 1-Hour Primary Sulfur Dioxide 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 and redesignation 
request submitted on November 14, 2023, by the Pennsylvania Department 
of Environmental Protection (PADEP) on behalf of the Allegheny County 
Health Department (ACHD). The SIP revision asks the EPA to redesignate 
the Allegheny County, Pennsylvania area from nonattainment to 
attainment for the 2010 1-hour primary sulfur dioxide (SO2) 
national ambient air quality standard (NAAQS). The revision also asks 
the EPA to approve into the SIP Allegheny County's maintenance plan for 
the 2010 1-hour primary SO2 standard for the Allegheny 
County area. This action is being taken under the Clean Air Act (CAA).

DATES: Written comments must be received on or before January 10, 2025.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R03-
OAR-2024-0316 at 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, the 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. The 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 www.epa.gov/dockets/commenting-epa-dockets.

FOR FURTHER INFORMATION CONTACT: Philip McGuire, Planning & 
Implementation Branch (3AD30), Air & Radiation Division, U.S. 
Environmental Protection Agency, Region III, 1600 John F Kennedy 
Boulevard, Philadelphia, Pennsylvania 19103. The telephone number is 
(215) 814-2251. Mr. McGuire can also be reached via electronic mail at 
[email protected].

SUPPLEMENTARY INFORMATION:

I. Background

A. Nonattainment Designation

    On June 22, 2010, the EPA revised the primary SO2 NAAQS, 
establishing a new 1-hour primary standard of 75 parts per billion 
(ppb).\1\ Under the EPA's regulations at title 40 of the Code of 
Federal Regulations (CFR) part 50, the 2010 1-hour SO2 NAAQS 
is met at a 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 (based on the rounding convention in 40 CFR part 50, 
appendix T).\2\ Ambient air quality monitoring data for the 3-year 
period must meet a data completeness requirement. A year meets data 
completeness requirements when all four quarters are complete, and a 
quarter is complete when at least 75 percent of the sampling days for 
each quarter have complete data. A sampling day has complete data if 75 
percent of the hourly concentration values, including State-flagged 
data affected by exceptional events which have been approved for 
exclusion by the Administrator, are reported.\3\
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    \1\ 75 FR 35520, June 22, 2010.
    \2\ 40 CFR 50.17.
    \3\ 40 CFR part 50, appendix T, section 3(b).
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    Upon promulgation of a new or revised NAAQS, the CAA requires the 
EPA to designate as nonattainment any area that does not meet (or that 
contributes to ambient air quality in a nearby area that does not meet) 
the NAAQS.\4\ On August 5, 2013, the EPA designated a portion of 
Allegheny County, Pennsylvania (hereafter the ``Allegheny County 
NAA''), as nonattainment for the 2010 1-hour primary SO2 
NAAQS, effective October

[[Page 99791]]

4, 2013.\5\ The designation was based on violating air quality 
monitoring data for calendar years 2009-2011. The Allegheny County NAA 
consists of 22 municipalities including: the Borough of Braddock, 
Borough of Dravosburg, Borough of East McKeesport, Borough of East 
Pittsburgh, Borough of Elizabeth, Borough of Glassport, Borough of 
Jefferson Hills, Borough of Liberty, Borough of Lincoln, Borough of 
North Braddock, Borough of Pleasant Hills, Borough of Port Vue, Borough 
of Versailles, Borough of Wall, Borough of West Elizabeth, Borough of 
West Mifflin, City of Clairton, City of Duquesne, City of McKeesport, 
Elizabeth Township, Forward Township, and North Versailles Township.\6\ 
This action established an attainment date five years after the 
effective date for the areas designated as nonattainment for the 2010 
SO2 NAAQS (i.e., by October 4, 2018). The Commonwealth was 
also required to submit an attainment SIP revision for the Allegheny 
County NAA to the EPA that meets the requirements of CAA sections 110, 
172(c) and 191-192 within 18 months following the October 4, 2013, 
effective date of designation (i.e., by April 6, 2015).
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    \4\ CAA section 107(d)(1)(A)(i).
    \5\ 78 FR 47191, August 5, 2013.
    \6\ A list of Pennsylvania's attainment status designations is 
available at 40 CFR 81.339.
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B. Relevant Historical SIP Actions

    The EPA did not receive an attainment SIP revision for the 
Allegheny County NAA by the April 6, 2015 deadline and subsequently on 
March 18, 2016, the EPA published a finding of failure to submit 
indicating that Pennsylvania did not submit the required SO2 
attainment plan.\7\ This finding initiated a clock under CAA section 
179(a) for the potential imposition of new source review sanctions 18 
months after the effective date of the finding and the potential 
imposition of highway funding sanctions 6 months following that, in 
accordance with CAA section 179(b) and 40 CFR 52.31. Additionally, 
under CAA section 110(c), the finding triggered a requirement for the 
EPA to promulgate a Federal implementation plan (FIP) within two years 
of the effective date of the finding unless, by that time, Pennsylvania 
made the necessary complete submittal, and the EPA approved the 
submittal.
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    \7\ 81 FR 14736, March 18, 2016.
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    Pursuant to Pennsylvania's October 3, 2017 attainment plan 
submittal, and the EPA's October 6, 2017 letter to Pennsylvania finding 
the submittal complete and noting the stopping of the sanctions' 
deadline, these CAA section 179(b) sanctions were not imposed as 
Pennsylvania did not miss the original deadline.\8\ The EPA proposed 
approving the SIP revision submittal on November 19, 2018,\9\ and 
issued a final approval on April 23, 2020.\10\ This approval ended the 
requirement for the EPA to promulgate a FIP under CAA section 110(c). 
On November 14, 2023, PADEP, on behalf of ACHD, submitted a revision to 
its SIP for the inclusion of a maintenance plan for the 2010 1-hour 
primary SO2 NAAQS and requested a concurrent redesignation 
of the Allegheny County NAA to attainment for the 2010 1-hour primary 
SO2 NAAQS.
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    \8\ Both the 2017 attainment plan submittal and EPA completeness 
letter are available in the docket for this action and are titled 
Allegheny County September 2017 Attainment Demonstration and EPA 
Letter of Completeness dated October 6, 2017, respectively.
    \9\ 83 FR 58206, November 19, 2018.
    \10\ 85 FR 22593, April 23, 2020.
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C. Redesignation to Attainment Criteria

    After a State has submitted a redesignation request for a 
nonattainment area, the EPA must assess if the statutory criteria 
identified in CAA section 107(d)(3)(E) have been met to redesignate the 
area to attainment. These conditions include: (1) the EPA has 
determined that the applicable NAAQS has been attained; (2) the 
applicable SIP has been fully approved by the EPA under CAA section 
110(k); (3) the EPA has determined that the improvement in the area's 
air quality is due to permanent and enforceable reductions in 
emissions; (4) the area has a fully approved maintenance plan, 
including a contingency plan, under CAA section 175A; and (5) the State 
has met all applicable requirements for the area under CAA section 110 
and part D. The EPA has provided direction for how it would consider if 
these conditions have been met in the April 23, 2014 memorandum 
``Guidance for 1-Hour SO2 Nonattainment Area SIP 
Submissions'' (2014 SO2 Guidance).\11\
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    \11\ Available in the docket for this action as 
2014_SO2_Guidance and at www.epa.gov/sites/default/files/2016-06/documents/20140423guidance_nonattainment_sip.pdf.
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D. Maintenance Plan Approval Criteria

    CAA section 175A and additional EPA guidance, including the 
September 4, 1992 memorandum ``Procedures for Processing Requests to 
Redesignate Areas to Attainment'' (Calcagni Memo),\12\ identify the 
required elements for an approvable maintenance plan for areas seeking 
redesignation from nonattainment to attainment. Under CAA section 175A, 
the plan must demonstrate continued attainment of the applicable NAAQS 
for at least 10 years after the EPA approves a redesignation request to 
attainment. Eight years after the redesignation, the State must submit 
a revised maintenance plan demonstrating that attainment will continue 
to be maintained for an additional 10 years following the initial 10-
year period. To address the possibility of future NAAQS violations, the 
maintenance plan must contain contingency measures, as the EPA deems 
necessary, to assure prompt correction of any future 2010 1-hour 
SO2 violations. The Calcagni Memo provides further guidance 
on the content of a maintenance plan, explaining that a maintenance 
plan should address five requirements: (1) an attainment emissions 
inventory that identifies the level of emissions in the area which is 
sufficient to attain the NAAQS; (2) a maintenance demonstration that 
shows future emissions of a pollutant will not exceed the level of the 
attainment inventory; (3) the continued operation of a monitoring 
network that conforms to 40 CFR part 58; (4) a means for verifying the 
continued attainment of the NAAQS; and (5) a contingency plan to 
correct any violation of the NAAQS in the area following redesignation 
of the area.
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    \12\ Available in the docket for this action as Calcagni Memo 
and at www.epa.gov/sites/default/files/2016-03/documents/calcagni_memo__procedures_for_processing_requests_to_redesignate_areas_to_attainment_090492.pdf.
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II. Summary of SIP Revision and EPA Analysis

    The EPA's evaluation of Pennsylvania's redesignation request and 
maintenance plan is based on consideration of the five redesignation 
criteria provided under CAA section 107(d)(3)(E) and relevant guidance, 
including the aforementioned 2014 SO2 Guidance and Calcagni 
Memo.

A. Criterion (1)--The Allegheny County SO2 Nonattainment Area Has 
Attained the 2010 1-Hour SO2 NAAQS

    CAA section 107(d)(3)(E)(i) requires that the EPA determine if a 
nonattainment area has attained the applicable NAAQS in order to 
redesignate the area to attainment. In assessing if the area has 
attained the NAAQS, the 2014 SO2 Guidance stipulates that 
the EPA can interdependently consider two components to support an 
attainment

[[Page 99792]]

determination: air quality monitoring data and air quality modeling 
data.\13\
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    \13\ See 2014 SO2 Guidance, at 62.
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    The Allegheny County NAA contains two operational SO2 
monitor sites: the Liberty site (Air Quality System (AQS) Site ID 42-
003-0064) and the North Braddock site (AQS Site ID 42-003-1301). The 
Liberty monitor is located centrally within the Allegheny County NAA 
and has been in operation since 1969, while the North Braddock monitor 
is located in the northern segment of the Allegheny County NAA and has 
been in operation since 2014. Both monitors have been in attainment of 
the 2010 1-hour primary SO2 NAAQS since the 2019-2021 
period, with Liberty recording a design value of 63 ppb for the 2021-
2023 period and North Braddock recording a design value of 54 ppb for 
the 2021-2023 period.\14\ Design values for the past 10 years are 
reported in Table 1 in this document. Although both monitors are 
currently in attainment of the NAAQS, prior analysis has determined 
that neither of these monitoring sites are located in the area of 
maximum concentration,\15\ and as such, additional air quality modeling 
is generally needed to estimate SO2 concentrations within 
the area.
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    \14\ Design values are calculated by computing the three-year 
average of the annual 99th percentile daily maximum 1-hour average 
concentrations. An SO2 1-hour primary standard design 
value is valid if it encompasses three consecutive calendar years of 
complete data. The data completeness requirements were previously 
described in the Nonattainment Designation section I.A. of this 
document above.
    \15\ See Allegheny County EPA Modeling TSD at pp. 16-17, 
available in the docket for this action.

                               Table 1--2014-2023 SO2 Design Values for Allegheny County Nonattainment Area Monitor Sites
                                                                   [Parts per billion]
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          Monitor site             2012-2014   2013-2015   2014-2016   2015-2017   2016-2018   2017-2019   2018-2020   2019-2021   2020-2022   2021-2023
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Liberty.........................         101          99          94          97         103         109          85          59          56          63
North Braddock *................          89          71          64          55          61          63          64          58          56          54
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* North Braddock design values from the 2012-2014 and 2013-2015 periods are comprised of less than three years of data as the monitor began operating in
  2014.

    Pennsylvania's 2017 attainment plan contained an attainment 
demonstration which utilized allowable SO2 emission limits 
from stationary sources within the Allegheny County NAA to inform 
several modeling analyses for SO2 emissions.\16\ These 
modeling analyses were based on emissions limits for large, stationary 
sources of SO2, which, if enacted, would ensure that the 
Allegheny County NAA would attain the 2010 1-hour primary 
SO2 NAAQS. The 2014 SO2 Guidance states that the 
EPA may make a determination of attainment based on this attainment 
plan modeling, eliminating the need for separate actual emissions-based 
modeling to support a redesignation request--provided that the source 
characteristics are still reasonably represented.\17\ The source 
characteristics are still reasonably represented \18\ and from 2020-
2021, large, stationary SO2 sources \19\ within the 
Allegheny County NAA were meeting their allowable emission limits for 
attainment.\20\ As such, the 2017 attainment demonstration modeling 
submitted by Pennsylvania will allow for the EPA's determination of 
attainment. The 2014 SO2 Guidance further states that a 
demonstration that the control strategy in the SIP has been fully 
implemented will also be pertinent for making the determination of 
attainment.\21\ Pennsylvania has submitted information detailed in its 
redesignation request and maintenance plan to confirm that the control 
strategy outlined in the SIP has been fully implemented. The specific 
measures identified in the control strategy include upgrades to the 
Vacuum Carbonate Unit equipment at the U.S. Steel (USS) Clairton Plant, 
the implementation of a tail gas recycling project at the USS Clairton 
Plant, and a new stack and combined flue system for select boilers at 
the USS Edgar Thomson Plant.\22\ Additionally, lower permitted 
SO2 emission rates were implemented for nearly all processes 
at the primary stationary SO2 sources in the Allegheny 
County NAA, including the USS Clairton Plant, the USS Edgar Thomson 
Plant, the USS Irvin Plant, and Harsco Metals. These implemented, 
permanent and federally enforceable control measures have aided in 
reducing the actual total emissions from large, stationary USS 
SO2 sources to 2,373 tons per year (as of 2021),\23\ which 
is below the revised total emissions limits proposed for USS facilities 
in the 2017 attainment demonstration modeling (2,669 tons per 
year),\24\ thus contributing to bringing the Allegheny County NAA into 
attainment.
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    \16\ See Allegheny County September 2017 Attainment 
Demonstration.
    \17\ See 2014 SO2 Guidance, at 50.
    \18\ See ACHD_Email_Source_Characteristics, available in the 
docket for this action.
    \19\ Large, stationary sources specifically include US Steel 
Clairton, US Steel Edgar Thomson, and US Steel Irvin, which 
collectively account for over 99% of all point source SO2 
emissions within the Allegheny County NAA.
    \20\ See Allegheny County September 2017 Attainment 
Demonstration, at 15, and ACHD_SO2_RR_and_MP_App_B_Emissions_Inv, at 
2, available in the docket for this action.
    \21\ See supra Note 17.
    \22\ See ACHD_SO2_RR_and_MP, at 15.
    \23\ See ACHD_SO2_RR_and_MP_App_B_Emissions_Inv, at 2.
    \24\ See Allegheny County September 2017 Attain_Demo_App_D, at 
2, available in the docket for this action.
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    In this action, the EPA proposes to find that the air quality 
monitoring data and air quality modeling data demonstrate that the 
Allegheny County NAA has attained the 2010 1-hour primary 
SO2 NAAQS.

B. Criterion (2)--Pennsylvania Has a Fully Approved SIP Under Section 
110(k)

    CAA section 107(d)(3)(E)(ii) requires that the EPA fully approve 
the applicable implementation plan for the area under CAA section 
110(k) in order to redesignate that area to attainment. The EPA has 
fully approved the applicable Pennsylvania SIP for the Allegheny County 
NAA under section 110(k) of the CAA for all requirements applicable for 
purposes of redesignation. An area cannot be redesignated to attainment 
if a required element of the SIP is the subject of a disapproval; a 
finding of failure to submit, or failure to implement the SIP; or a 
partial, conditional, or limited approval.\25\ The 2017 attainment plan 
SIP was initially proposed for EPA approval on November 19, 2018 \26\ 
and received final EPA approval on April 23, 2020.\27\ The approved 
elements from the 2017 attainment plan include a 2011 base year 
emissions inventory, a control strategy and air quality modeling 
demonstration, a reasonable available control measures/reasonably 
available control technology (RACM/RACT)

[[Page 99793]]

analysis, a reasonable further progress (RFP) analysis, contingency 
measures, and nonattainment new source review (NNSR) regulations.
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    \25\ See 2014 SO2 Guidance, at 64.
    \26\ 83 FR 58206, November 19, 2018.
    \27\ 85 FR 22593, April 23, 2020.
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C. Criterion (3)--The Air Quality Improvement in the Allegheny County 
SO2 Nonattainment Area Is Due to Permanent and Enforceable Reductions 
in Emissions

    For redesignating a nonattainment area to attainment, CAA section 
107(d)(3)(E)(iii) requires the EPA to determine that the air quality 
improvement in the area is due to permanent and enforceable reductions 
in emissions resulting from implementation of the SIP, applicable 
Federal air pollution control regulations, and other permanent and 
enforceable reductions. The EPA proposes to find that Pennsylvania has 
demonstrated that the requirements of CAA section 107(d)(3)(E)(iii) 
have been met.
    Specifically, the implementation of multiple permanent and 
federally enforceable control measures at stationary point sources of 
SO2 identified in the EPA-approved 2017 attainment 
demonstration aided in a substantial decrease in SO2 
emissions, and consequently lower SO2 concentrations in the 
Allegheny County NAA. These measures include upgrades to the Vacuum 
Carbonate Unit equipment at the USS Clairton Plant, the implementation 
of a tail gas recycling project at the USS Clairton Plant, and a new 
stack and combined flue system for select boilers at the USS Edgar 
Thomson Plant. Furthermore, the Guardian Glass Plant ceased operations 
in August 2015 and its operating permit was terminated in November 
2015.\28\ The Calcagni Memo states that ``[e]mission reductions from 
source shutdowns can be considered permanent and enforceable to the 
extent that those shutdowns have been reflected in the SIP and all 
applicable permits have been modified accordingly,'' and therefore the 
Guardian shutdown is considered permanent and enforceable.\29\ Any 
future operations at this location would require a new permit and a new 
source evaluation, as described in ACHD Article XXI, sections 2102.04 
and 2103.13.\30\ Additionally, Emissions Reductions Credits for 
SO2 were not requested for the Guardian Glass Plant, 
preventing the transfer or sale of associated emission credits to 
another entity in Pennsylvania or some surrounding states.
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    \28\ Documentation of this closure is in Guardian_closure-App_J, 
available in the docket for this action.
    \29\ See Calcagni Memo, at 10.
    \30\ See Allegheny_County_Article_XXI, available in the docket 
for this action and at www.alleghenycounty.us/files/assets/county/v/
1/government/health/documents/air-quality/article-21-air-pollution-
control.pdf.
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    Allegheny County also established lower SO2 emissions 
limits for nearly all processes at the USS facilities in the Allegheny 
County NAA, including USS Clairton, USS Edgar Thomson, and USS Irvin, 
as well as the Harsco (Braddock Recovery) facility, located on the 
property of USS Edgar Thomson. These emissions limits are embedded in 
the installation permits issued by ACHD for these facilities and are 
federally enforceable as they have been approved into Pennsylvania's 
SIP, and they are permanent because they cannot be altered without an 
additional SIP submittal.\31\ Details on the imposed emissions limits 
were included as copies of the installation permits in Appendix K of 
the 2017 attainment plan submittal and are available in the docket for 
this action.\32\
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    \31\ 85 FR 22593, April 23, 2020 and 40 CFR 52.2020(d)(3).
    \32\ See Installation_Permits_with_emission_limits-App_K, 
available in the docket for this action.
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    Collectively, the implemented controls and lower permitted 
SO2 emissions rates resulted in an actual decrease of 835 
tons of SO2 emitted per year from 2011 to 2017. This is 
approximately a 25% reduction from 2011 levels of 3,418 tons of 
SO2 emitted per year.\33\ As this reduction comes from EPA-
approved SIP controls and permit-controlled emission limits, the EPA 
finds the air quality improvement in the Allegheny County NAA to be due 
to permanent and enforceable reductions in emissions.
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    \33\ See ACHD_SO2_RR_and_MP, at 16.
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D. Criterion (4)--The Allegheny County SO2 Nonattainment Area Has a 
Fully Approved Maintenance Plan Pursuant to Section 175A of the CAA

    To redesignate a NAA to attainment, CAA section 107(d)(3)(E)(iv) 
requires the EPA to determine that the area has a fully approved 
maintenance plan pursuant to section 175A of the CAA. In conjunction 
with its request to redesignate the Allegheny County NAA to attainment 
for the 2010 1-hour primary SO2 NAAQS, the State submitted a 
SIP revision to provide for the maintenance of the 2010 1-hour primary 
SO2 NAAQS for at least 10 years after the effective date of 
redesignation to attainment. The EPA is proposing to find that this 
maintenance plan meets the requirements for approval under section 175A 
of the CAA.
1. What is required in a maintenance plan?
    CAA section 175A sets forth the elements of a maintenance plan. 
Under section 175A, the plan must demonstrate continued attainment of 
the applicable NAAQS for at least 10 years after the Administrator 
approves a redesignation request to attainment. Eight years after the 
redesignation, the State must submit a revised maintenance plan 
demonstrating that attainment will continue to be maintained for an 
additional 10 years following the initial 10-year period. To address 
the possibility of future NAAQS violations, the maintenance plan must 
contain contingency measures as the EPA deems necessary to assure 
prompt correction of any future 2010 1-hour primary SO2 
NAAQS violations. The Calcagni Memo provides further guidance on the 
content of a maintenance plan, explaining that a maintenance plan 
should address five requirements: the attainment emissions inventory, 
maintenance demonstration, monitoring, verification of continued 
attainment, and a contingency plan.\34\ As is discussed more fully 
later in this section, the EPA is proposing to determine that 
Pennsylvania's maintenance plan meets the requirements in CAA section 
175A and is thus proposing to approve it as a revision to the Allegheny 
County portion of the Pennsylvania SIP.
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    \34\ See Calcagni Memo, at pp. 8-12.
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2. Attainment Emissions Inventory
    In a maintenance plan, states are required to submit an emissions 
inventory to identify the level of emissions in the area which is 
sufficient to attain and maintain the SO2 NAAQS, which is 
called the attainment inventory. This inventory is used as the basis 
for future, projected emission inventories that are used to show the 
area will remain in attainment. Pennsylvania submitted a 2017 
SO2 emissions inventory as the attainment inventory with its 
maintenance plan. The year 2017 was selected because it was the first 
year in which emissions were at levels required to demonstrate 
attainment of the 2010 SO2 NAAQS, with the exception of 
emissions associated with malfunctions of the desulfurization facility 
at the USS Clairton Plant. Additionally, 2017 was a year in which a 
fully reviewed National Emission Inventory (NEI) was released. The NEI 
is a comprehensive, triennial estimate of emissions. Generally, the

[[Page 99794]]

attainment year is selected as a year within the attaining design value 
period (i.e., 2019-2021). However, alternate years from 2018-2022 were 
less ideal than 2017 for the attainment year for a variety of factors, 
including excess emissions from sources due to equipment breakdowns, 
atypical emissions during the COVID pandemic, and incomplete emissions 
compilations for recent years. Additional details for choosing 2017 as 
the attainment year are available in the submitted redesignation 
request.\35\
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    \35\ See ACHD_SO2_RR_and_MP, at 19.
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    For the 2017 attainment year inventory, Pennsylvania directly used 
point and area source emissions reported in the 2017 NEI, except for 
corrections identified in Appendix B of the submitted redesignation 
request.\36\ The point source emissions for the Allegheny County NAA 
were verified against the EPA's emissions inventory system (EIS) and 
the EPA found them to be acceptable.\37\ Area source emissions were 
estimated based on the relative percentage of the Allegheny County 
population residing in the Allegheny County NAA and the resulting 
factor allocated the appropriate fraction of the County's total 
emissions to the Allegheny County NAA.
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    \36\ See ACHD_SO2_RR_and_MP_App_B_Emissions_Inv, at pp. 1-2.
    \37\ See EI_TSD_ACHD_SO2_RR_and_MP, available in the docket for 
this action.
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    Nonroad and onroad mobile source emissions for 2017 were obtained 
from the EPA's Motor Vehicle Emissions Simulator (MOVES) model, 
specifically the MOVES3 version. PADEP executed the MOVES3 modeling 
runs for nonroad mobile sources and utilized a contractor to run the 
model for onroad mobile source emissions.
    Natural SO2 emission sources, such as fires and 
biogenics, were also compiled. Fire emissions data was pulled from the 
EPA's Fires \38\ inventory, while biogenic emissions from soils and 
vegetation were predicted by the Biogenic Emission Inventory System 
\39\ (BEIS) model.
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    \38\ EPA Fires: www3.epa.gov/ttn/chief/ap42/ch13/related/firerept.pdf.
    \39\ EPA BEIS: www.epa.gov/air-emissions-modeling/biogenic-emission-inventory-system-beis.
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    Projection inventories predicted from the attainment inventory 
demonstrate that the area will continue to remain in attainment during 
the maintenance period. Pennsylvania developed 2026 and 2035 emission 
projections for the interim and maintenance plan end year, 
respectively. Projected emissions for these years--as well as the base 
year inventory--are available in Table 2 in this document. Projected 
emissions for point and area sources were estimated from the 2017 base 
year emissions and growth factors developed by the Mid-Atlantic 
Regional Air Management Association, Inc., and other sources. These 
growth factors are developed based on forecasts from various databases 
and tools, including the Energy Information Administration's Annual 
Energy Outlook 2022, Pennsylvania Industry Employment 2018-2028 Long-
Term Projections, National Inventory Collaborative 2016v1 Emissions 
Modeling Platform, and the Federal Aviation Administration's Terminal 
Area Forecast. Projected emissions were subject to the same corrections 
utilized in the 2017 base year inventory for consistency. Furthermore, 
point sources with implemented enforceable controls or shutdowns since 
the 2017 base year were excluded from the 2026 and 2035 projections. 
Specifically, the Koppers Clairton tar refining facility ceased 
operation in 2017 and its permit expired in 2021. Additionally, Coke 
Batteries 1, 2, and 3 at the USS Clairton Plant ceased operation in 
March 2023. Conversely, projections for the 2026 and 2035 inventories 
included the permitted plantwide SO2 emissions limit of 
23.89 tons/year for a new major source facility--the Invenergy 
Allegheny Energy Center. However, the permit for this facility was 
terminated on November 9, 2023,\40\ and construction of this facility 
is not expected to proceed at this time. As such, the actual emissions 
in 2026 and 2035 should be even lower than the anticipated values 
reported in the maintenance year projections. Nonroad and onroad mobile 
source emissions for the projected years 2026 and 2035 were also 
obtained from the MOVES3 version. MOVES3 modeling runs were once again 
executed by PADEP for nonroad mobile source emissions and by the 
contractor for onroad mobile source emissions. Additional details on 
some of the assumptions and inputs to the model are available in the 
redesignation request and its associated Appendix B.\41\ Fire and 
biogenic sources are typically not projected for future case scenarios 
and therefore emissions were held constant from 2017 to 2026 and 2035.
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    \40\ See Allegheny County Energy Center Termination Letter, 
available in the docket for this action.
    \41\ See ACHD_SO2_RR_and_MP, at 22 and 
ACHD_SO2_RR_and_MP_App_B_Emissions_Inv.

                   Table 2--Emissions Inventories for the Allegheny County Nonattainment Area
                                                 [Tons per year]
----------------------------------------------------------------------------------------------------------------
                                                        2017 Actual       2026 Projected       2035 Projected
                      Sector                          emissions (base   emissions (interim        emissions
                                                           year)               year)         (maintenance year)
----------------------------------------------------------------------------------------------------------------
Point Sources.....................................               2,556               2,511                 2,472
Area Sources......................................                  22                  26                    27
Nonroad Mobile Sources............................                   0                   0                     0
Onroad Mobile Sources.............................                   5                   2                     2
Fires.............................................                   0                   0                     0
Biogenics.........................................                   0                   0                     0
                                                   -------------------------------------------------------------
    Total.........................................               2,583               2,539                 2,501
----------------------------------------------------------------------------------------------------------------

3. Maintenance Demonstration
    The Calcagni memo describes two ways for a State to demonstrate 
maintenance of the NAAQS for a period of at least 10 years following 
the redesignation of the area: (1) the State can show that future 
emissions of a pollutant will not exceed the level of the attainment 
inventory, or (2) the State can model to show that the future mix of 
sources and emission rates will not cause a violation of the 
standard.\42\ Pennsylvania's projected actual emissions for the interim 
year of 2026 and for the maintenance year of 2035

[[Page 99795]]

are both below the total attainment inventory, which is acceptable for 
showing maintenance in the Allegheny County NAA.
---------------------------------------------------------------------------

    \42\ See Calcagni Memo, at 9.
---------------------------------------------------------------------------

4. Monitoring Network
    The 2014 SO2 Guidance indicates that once an area has 
been redesignated to attainment, the state should continue to operate 
an appropriate air quality monitoring network as provided under 40 CFR 
part 58 to verify the attainment status of the area. ACHD has committed 
to continued operation of its SO2 monitoring network in the 
Allegheny County NAA to verify the attainment status. Also, ACHD will 
continue to submit an annual monitoring network plan to the EPA for 
approval, in accordance with 40 CFR 58.10. No changes will be made to 
the existing network unless pre-approved by the EPA.
5. Verification of Continued Attainment
    The 2014 SO2 Guidance states that each air agency should 
ensure that it has the legal authority to implement and enforce all 
measures necessary to attain and maintain the 2010 SO2 
NAAQS. The air agency's submittal should indicate how it will track the 
progress of the maintenance plan for the area either through air 
quality monitoring or modeling.
    Article XXI, section 2101.07(a) grants the ACHD legal authority to 
implement and enforce all measures necessary to maintain the 2010 1-
hour primary SO2 NAAQS. In addition, ACHD has indicated it 
will track the progress of the maintenance plan through an integrated 
approach utilizing monitoring data and emissions inventories.
    As previously indicated, ACHD will continue to operate its 
SO2 monitoring network to verify the attainment status of 
the Allegheny County NAA. Monitored concentrations will serve as the 
primary indicator for verifying continued attainment and will also act 
as the triggering mechanism for contingency measures.
    ACHD will also use emissions inventories--developed annually by 
ACHD for point sources and triennially by PADEP for area and mobile 
sources--and compare these inventories to the 2017 attainment inventory 
for assessing continued attainment. It is anticipated that future 
inventories will remain below the levels of the attainment inventory. 
However, if future inventories exceed the attainment inventory levels, 
ACHD will conduct a study to evaluate if the increased emissions have 
caused increased monitored concentrations within the Allegheny County 
NAA and, if so, ACHD will determine if any additional emission control 
measures should be enacted. Emissions data will not serve as a 
triggering mechanism for contingency measures for two reasons. 
Primarily, increased emissions may not directly affect monitored 
concentrations, as SO2 concentrations can be impacted by 
meteorological conditions. Additionally, emissions inventory reporting 
is slower than monitoring data reporting, and the use of emissions data 
as a contingency initiator would not provide for a prompt response to 
any potential NAAQS violations.
    Under ACHD's new source review program, any major new sources or 
modifications to existing sources that would affect emissions must 
provide a modeling demonstration that illustrates new emissions will 
not cause or contribute to a violation of the 2010 1-hour primary 
SO2 NAAQS, as described in ACHD Article XXI, section 
2102.04(b). ACHD will not approve any modifications that would lead to 
expected violations of the 2010 1-hour primary SO2 NAAQS in 
the Allegheny County NAA.
    The EPA proposes to find that these proposed measures will provide 
for verifying continued attainment within the Allegheny County NAA.
6. Contingency Measures
    Section 175A(d) of the CAA requires that a maintenance plan include 
such contingency measures as the EPA deems necessary to assure that the 
State will promptly correct a violation of the NAAQS that occurs after 
redesignation. The maintenance plan should identify the contingency 
measures to be adopted, a schedule and procedure for adoption and 
implementation, and a time limit for action by the State. A State 
should also identify specific indicators to be used to determine when 
the contingency measures need to be implemented. The maintenance plan 
must also include a requirement that a State will continue to implement 
all measures with respect to control of the pollutant that were 
contained in the SIP before redesignation of the area to attainment.
    ACHD has committed to continuing implementation of all measures 
indicated in the SIP after redesignation of the Allegheny County 
NAA.\43\ Furthermore, ACHD has identified triggering indicators for its 
contingency measures, a schedule for implementing these potential 
measures, and has specified multiple potential options to correct any 
NAAQS violation.\44\
---------------------------------------------------------------------------

    \43\ See ACHD_SO2_RR_and_MP, at 27.
    \44\ See ACHD_SO2_RR_and_MP, at 28-31.
---------------------------------------------------------------------------

    Fully validated and quality assured SO2 monitoring data 
will serve as the primary trigger for any responses to prevent or 
correct a NAAQS violation in the Area. ACHD has established both 
warning level and action level responses with specific triggering 
indicators for each.
    Warning level responses are sub-divided into two tiers. A first-
level warning will occur when the 99th percentile daily maximum 1-hour 
SO2 concentration exceeds 75 ppb at any monitor site in the 
Allegheny County NAA in a single calendar year. This first-level 
warning will prompt an ACHD study to determine if the trigger indicates 
a trend toward increasing SO2 concentrations in the 
Allegheny County NAA. If there seems to be a rising trend in 
SO2 concentrations, the study will examine if the trend is 
likely to continue and if so, the needed measures that could reverse 
the trend. A second-level warning will occur when the average of two 
consecutive years of 99th percentile daily maximum 1-hour 
SO2 concentrations exceeds 75 ppb at any monitor in the 
Allegheny County NAA. This second-level warning will result in ACHD 
evaluating the chance of a violation of the NAAQS and the need for 
supplemental control measures to be activated. Both first- and second-
level warnings will allow for ACHD to consider the early adoption of 
measures to permit the expeditious implementation of these measures in 
the event of a NAAQS violation. This early adoption could allow for 
implementation of the measures within 30 to 90 days following the 
potential occurrence of a NAAQS violation.
    An action level response will occur when the 1-hour design value, 
based on the average of three consecutive years of 99th percentile 
daily maximum 1-hour SO2 concentrations, violates the 2010 
1-hour SO2 NAAQS at any monitor site in the Allegheny County 
NAA. This response will include the adoption and implementation of 
additional control measures as needed to promptly correct the 
violation. If regulatory measures are selected, these measures will 
conform to all Federal, State, and local rules and regulations. Both 
non-regulatory and regulatory measures are expected to be implemented 
within one year following a violation of the NAAQS.\45\
---------------------------------------------------------------------------

    \45\ Specific schedules and associated procedures for the 
adoption and implementation of regulatory and non-regulatory 
measures are available in the ACHD_SO2_RR_and_MP document at pp. 29-
30.
---------------------------------------------------------------------------

    ACHD has specified multiple potential regulatory and non-regulatory

[[Page 99796]]

contingency measures for this maintenance plan--including both area-
wide and USS Mon Valley Works measures.\46\ Selection will be based on 
several factors, including but not limited to, the degree of the 
violation, the emission reduction potential, and cost. ACHD has 
identified non-regulatory, area-wide measures such as wood burning-
related programs and alternative fuel promotions as potential options 
for correcting a NAAQS violation. Additionally, ACHD has proposed USS 
Mon Valley Works regulatory measures, including but not limited to, 
additional desulfurization controls for coke oven gas at USS Clairton, 
additional fugitive controls at USS Mon Valley Works plants, and 
restrictions on fuel usage at USS Mon Valley Works plants. All of these 
measures can be individually implemented or in conjunction with others 
to ensure correction of any NAAQS violation.
---------------------------------------------------------------------------

    \46\ USS Mon Valley Works collectively refers to the USS 
Clairton, Edgar Thomson, and Irvin Plants located within the 
Allegheny County NAA.
---------------------------------------------------------------------------

    The EPA proposes to find that ACHD's submitted maintenance plan 
meets the requirements set forth in CAA section 175A and EPA guidance 
and is proposing to approve the maintenance plan as a revision to the 
Pennsylvania SIP.

E. Criterion (5)--Pennsylvania Has Met All Applicable Requirements 
Under Section 110 and Part D of Title I of the CAA

    In accordance with section 107(d)(3)(E)(v) of the CAA, to 
redesignate the Allegheny County NAA to attainment, Pennsylvania must 
meet all requirements applicable to the Allegheny County NAA under CAA 
section 110 (general SIP requirements) and part D of title I of the CAA 
(SIP requirements for nonattainment areas).
1. Section 110 General Requirements for SIPs
    Pursuant to CAA section 110(a)(1), whenever new or revised NAAQS 
are promulgated, the CAA requires States to submit a plan (i.e., SIP) 
for the implementation, maintenance, and enforcement of such NAAQS. 
Section 110(a)(2) of title I of the CAA contains the general 
requirements for a SIP, also known as ``infrastructure'' requirements. 
These requirements include, but are not limited to, the following: 
submittal of a SIP that has been adopted by the state after reasonable 
public notice and hearing; provisions for establishment and operation 
of appropriate procedures needed to monitor ambient air quality; 
implementation of a source permit program; provisions for the 
implementation of part C requirements (Prevention of Significant 
Deterioration (PSD)) and provisions for the implementation of part D 
requirements (New Source Review (NSR) permit programs); provisions for 
air pollution modeling; and provisions for public and local agency 
participation in planning and emission control rule development.
    Section 110(a)(2)(D) requires that SIPs contain certain measures to 
prevent sources in a state from significantly contributing to air 
quality problems in another state. To implement this provision, the EPA 
has required certain states to establish programs to address the 
interstate transport of air pollutants.\47\ The section 110(a)(2)(D) 
requirements for a state are not linked with a particular nonattainment 
area's designation and classification in that state. The EPA has 
concluded that the requirements linked with a particular nonattainment 
area's designation and classifications are the relevant measures to 
evaluate in reviewing a redesignation request. The transport SIP 
submittal requirements, where applicable, continue to apply to a state 
regardless of the designation of any one particular area in the state. 
Thus, the EPA has concluded that the CAA's interstate transport 
requirements should not be construed to be applicable requirements for 
purposes of redesignation.
---------------------------------------------------------------------------

    \47\ See Nitrogen Oxides (NOX) SIP Call and 
amendments to the NOX SIP Call (64 FR 26298, May 14, 1999 
and 65 FR 11222, March 2, 2000), and the Cross-State Air Pollution 
Rule (CSAPR) Update (81 FR 74504, October 26, 2016).
---------------------------------------------------------------------------

    In addition, the EPA has concluded other section 110 elements--
those that are neither connected with nonattainment plan submissions 
nor linked with an area's attainment status--are not applicable 
requirements for purposes of redesignation. The area will still be 
subject to these requirements after the area is redesignated. The 
section 110 and part D requirements which are linked with a particular 
area's designation and classification are the relevant measures to 
evaluate in reviewing a redesignation request. This approach is 
consistent with the EPA's existing policy on applicability (i.e., for 
redesignations) of conformity and oxygenated fuels requirements, as 
well as with section 184 ozone transport requirements. See Reading, 
Pennsylvania, proposed and final rules (61 FR 53174-53176, October 10, 
1996), (62 FR 24826, May 7, 2008); Cleveland-Akron-Loraine, Ohio, final 
rule (61 FR 20458, May 7,1996); and Tampa, Florida, final rule (60 FR 
62748, December 7, 1995). See also the discussion on this issue in the 
Cincinnati, Ohio, redesignation (65 FR 37890, June 19, 2000), and in 
the Pittsburgh, Pennsylvania, redesignation (66 FR 50399, October 19, 
2001).
    The EPA approved elements of Pennsylvania's June 15, 2014 
SO2 infrastructure SIP submittal on August 5, 2015.\48\ As 
explained previously, certain general requirements of CAA section 
110(a)(2) are statewide requirements that are not linked to the 
nonattainment status of the Allegheny County NAA and are therefore not 
``applicable requirements'' for the purpose of reviewing Pennsylvania's 
redesignation request. Because Pennsylvania satisfies the general SIP 
elements and requirements set forth in CAA section 110(a)(2) applicable 
to and necessary for SO2 redesignation, the EPA proposes to 
conclude that Pennsylvania has satisfied the criterion of section 
107(d)(3)(E)(v) related to section 110(a)(2) of the CAA.
---------------------------------------------------------------------------

    \48\ 80 FR 46494, August 5, 2015.
---------------------------------------------------------------------------

2. Part D Requirements
    In addition to the CAA section 110 requirements, section 
107(d)(3)(E)(v) requires that the state meet all the requirements 
applicable to the nonattainment area ``under part D of this 
subchapter'' for the nonattainment area to be redesignated. Both 
section 107 and part D are within subchapter 1 of the CAA. Part D, 
entitled ``Plan Requirements for Nonattainment Areas,'' consists of six 
subparts, of which only subparts 1 and 5 are applicable to 
SO2 nonattainment areas. Subpart 1 (sections 171 through 
179B) contains provisions that can apply to all nonattainment areas for 
all criteria pollutants, while subpart 5 (sections 191 through 192) 
contains additional provisions for SO2, NOX, or 
lead nonattainment areas. The requirements applicable to this 
redesignation are discussed below.
a. Subpart 1 Requirements
1. Section 172 Requirements
    CAA section 172 requires states with nonattainment areas to submit 
plans that provide for timely attainment of the NAAQS. More 
specifically, CAA section 172(c) contains general requirements for 
nonattainment plans. A thorough discussion of these requirements is 
found in the General Preamble for Implementation of title I.\49\
---------------------------------------------------------------------------

    \49\ 57 FR 13498, April 16, 1992.
---------------------------------------------------------------------------

    As noted in the General Preamble, certain attainment-related 
planning requirements under section 172(c) no longer have meaning for 
an area that is already attaining the NAAQS, and

[[Page 99797]]

therefore are not applicable for purposes of redesignation. For 
example, for an area that is already attaining the NAAQS, there would 
be nothing for the State to provide to show reasonable further progress 
to attainment in that area. Similarly, the CAA section 172 requirements 
for the attainment demonstration, implementation of reasonably 
available control measures, including reasonably available control 
technology, and contingency measures that are triggered if an area 
fails to meet RFP or fails to attain are also not applicable for 
purposes of redesignation.
    With respect to CAA section 172(c)(3), Pennsylvania was required to 
submit an actual current emissions inventory with its attainment plan. 
Pennsylvania had submitted a base year inventory with its attainment 
plan SIP on October 3, 2017 and the EPA approved this element on April 
23, 2020.\50\
---------------------------------------------------------------------------

    \50\ 85 FR 22593, April 23, 2020.
---------------------------------------------------------------------------

2. Section 173 Requirements
    Section 173 of the CAA includes requirements for permit programs 
that are required in a nonattainment area for new sources as required 
by section 172(c)(5), known as nonattainment new source review (NNSR). 
However, the EPA has a longstanding interpretation that because the 
NNSR permit program is replaced by the PSD permit program upon an 
area's redesignation to attainment, nonattainment areas seeking 
redesignation to attainment do not need a fully approved part D NNSR 
program to be redesignated. A more detailed rationale for this view is 
described in a memorandum from Mary Nichols, Assistant Administrator 
for Air and Radiation, dated October 14, 1994, entitled, ``Part D New 
Source Review Requirements for Areas Requesting Redesignation to 
Attainment.'' \51\ Nevertheless, the EPA notes that the ACHD's Article 
XXI Rules and Regulations for Air Pollution Control have SIP-approved 
NNSR and PSD programs found in section 2102.06 for NNSR and section 
2102.07 for PSD. Allegheny County has incorporated by reference 
Pennsylvania's NNSR provisions at 25 Pa. Code 127.201-127.218 and also 
Pennsylvania's PSD regulations found at 25 Pa. Code 127.81-127.83. 
Pennsylvania's PSD regulations merely incorporate by reference the 
Federal PSD regulations found at 40 CFR part 52. Allegheny County has 
therefore addressed all required provisions for the permitting of 
sources in NAAs, including NNSR. See 40 CFR 52.2020(c). Pennsylvania's 
PSD program will become applicable for SO2 in the Allegheny 
County NAA upon redesignation to attainment.
---------------------------------------------------------------------------

    \51\ Available in the docket for this action as Nichols_Memo and 
at www.epa.gov/sites/default/files/2015-07/documents/101494m.pdf.
---------------------------------------------------------------------------

3. Section 175A Requirements
    CAA section 175A requires that states seeking redesignation of an 
area to attainment submit a ``maintenance plan'' containing certain 
elements. Pennsylvania included a maintenance plan for the Allegheny 
County NAA with its November 14, 2023 redesignation request, which the 
EPA is proposing to approve in conjunction with the redesignation, and 
it is discussed in detail in section II, Criterion (4) of this 
document.
4. Section 176 Requirements
    Section 176(c) of the CAA requires that Federal actions conform to 
the air quality planning goals in the applicable SIP. The requirement 
to determine conformity applies to transportation plans, programs, and 
projects that are developed, funded, or approved under title 23 of the 
United States Code and the Federal Transit Act (transportation 
conformity) as well as to all other Federally-supported or funded 
projects (general conformity). Section 176(c) of the CAA also requires 
that states establish criteria and procedures to ensure that Federally-
supported or funded transportation plans, transportation improvement 
programs (TIPs) and projects conform to the goals of the applicable 
SIP. This is referred to as a transportation conformity SIP. In the 
preamble to the January 1993 proposed transportation conformity rule, 
the EPA stated that, ``Based on available emissions information, EPA 
believes highway and transit motor vehicles are not significant sources 
of lead or sulfur dioxide. Therefore, transportation plans, TIPs, and 
projects are presumed to conform to the applicable implementation plans 
for these pollutants.'' \52\ In November 1993, the EPA finalized its 
transportation conformity regulations. One section of those regulations 
addressed the geographic applicability of the transportation conformity 
regulations. The regulation stated at that time that, ``The provisions 
of this subpart apply with respect to emissions of the following 
criteria pollutants: Ozone, carbon monoxide, nitrogen dioxide, and 
particles with an aerodynamic diameter less than or equal to a nominal 
10 micrometers (PM10).'' \53\ Based on this provision, 
transportation conformity does not apply in nonattainment or 
maintenance areas for SO2. Therefore, a transportation 
conformity SIP is not required for SO2 nonattainment and 
maintenance areas and is not necessary for an SO2 
nonattainment area to be redesignated to attainment, and the EPA's 
transportation conformity rules do not apply to SO2 for the 
Allegheny County NAA.
---------------------------------------------------------------------------

    \52\ 58 FR 3776, January 11, 1993.
    \53\ This provision has been revised to include particles with 
an aerodynamic diameter less than or equal to a nominal 2.5 
micrometers (PM2.5). See 40 CFR 93.102(b)(1).
---------------------------------------------------------------------------

5. Section 179 Requirements
    Section 179(a) of the CAA addresses potential sanctions for the 
failure of a State to submit certain required SIP elements by statutory 
deadlines. The EPA is not aware of any missing or incomplete Allegheny 
County planning elements subject to Section 179(a) of the CAA.
b. Subpart 5 Requirements
    The subpart 5 requirements, which consist of sections 191 and 192 
of the CAA, are specific provisions applicable to SO2, 
NO2 or lead nonattainment areas. Section 191 of the CAA 
requires states with areas designated nonattainment for SO2, 
NO2 or lead after November 15, 1990, to submit within 18 
months of the designation an implementation plan meeting the 
requirements of part D. The substance of the required plans is 
established by section 172(c). Section 192 sets forth attainment dates 
for nonattainment areas under section 191.
    For SO2, section 192(a) requires that attainment plans 
provide for attainment of the primary standard as expeditiously as 
possible, but no later than five years from the date of the 
nonattainment designation. The EPA designated the Allegheny County NAA 
as nonattainment on August 5, 2013, with an attainment date of October 
4, 2018. However, because the EPA is reviewing a redesignation request 
under section 107(d)(3)(E), rather than a determination of attainment 
under section 179(c), the determination of whether the Area attained by 
the attainment date set forth in section 192 is not applicable to this 
action proposing approval of Pennsylvania's redesignation request.
    Based on the above, the EPA is proposing to find that Pennsylvania 
has satisfied the applicable requirements for the redesignation of the 
Allegheny County NAA under section 110 and part D of title I of the 
CAA.

III. Environmental Justice Concerns

    Within its redesignation request and maintenance plan, ACHD 
provided

[[Page 99798]]

supplemental information regarding environmental justice considerations 
within the Allegheny County NAA. Utilizing the Environmental Justice 
Index (EJI) tool developed by ACHD's Bureau of Assessment, Statistics, 
& Epidemiology, ACHD identified areas within the Allegheny County NAA 
with higher environmental health risks. The EJI tool uses Allegheny 
County-specific factors to evaluate environmental justice concerns, 
including the following indicators: race, education, median household 
income, housing vacancy, lead paint risk, greenness, air quality, and 
flood risk. Six municipalities within the Allegheny County NAA were 
designated as ``highest need'' areas according to EJI, while seven 
other municipalities were designated as ``high need'' areas. ACHD has 
indicated that its SO2 monitoring network provides enhanced 
surveillance in vulnerable communities, and the two current 
SO2 monitors in the Allegheny County NAA are located within 
or directly downwind of areas labeled as ``highest need.'' Furthermore, 
ACHD states that the controls specified in its 2017 attainment 
demonstration as well as the shutdowns denoted in the maintenance 
demonstration illustrate the greatest emissions reductions in the 
``highest need'' areas.
    As explained in the EJ Legal Tools to Advance Environmental Justice 
2022 document, the CAA provides states with the discretion to consider 
environmental justice in developing rules and measures related to 
redesignation requests and maintenance plans. In this instance, ACHD 
exercised this discretion, as is described above in summary. In 
reviewing ACHD's analysis, the EPA defers to ACHD's reasonable exercise 
of its discretion in considering EJ in this way. The EPA is taking 
proposed action to approve the SIP revision because it meets minimum 
requirements pursuant to the CAA and relevant implementing regulations. 
The EPA also finds that ACHD's consideration of EJ analyses in this 
context is reasonable. The EPA encourages air agencies generally to 
evaluate environmental justice considerations of their actions and 
carefully consider impacts to communities. The EJ analyses submitted by 
the air agency were considered but were not the basis for the EPA's 
decision making and the SIP met the minimum applicable requirements, as 
explained above.

IV. Proposed Action

    The EPA's review of this material indicates that the Allegheny 
County NAA has met the criteria necessary under CAA section 
107(d)(3)(E) for the EPA to redesignate the Area from nonattainment to 
attainment for the 2010 1-hour primary SO2 NAAQS. The EPA is 
proposing to approve the Pennsylvania redesignation request for the 
Allegheny County NAA, which was submitted on behalf of ACHD on November 
14, 2023. Final approval of Pennsylvania's redesignation request would 
change the legal designation of the portion of Allegheny County 
designated nonattainment at 40 CFR 81.339 to attainment for the 2010 1-
hour primary SO2 NAAQS. The EPA is also proposing to approve 
ACHD's maintenance plan, which is designed to ensure that the 
potentially redesignated Allegheny County NAA will continue to maintain 
the SO2 NAAQS. The EPA is soliciting public comments on the 
issues discussed in this document. These comments will be considered 
before taking final action.

V. Statutory and Executive Order Reviews

    Under the CAA, the redesignation of an area to attainment and the 
accompanying approval of the maintenance plan under CAA section 
107(d)(3)(E) are actions that affect the status of geographical area 
and do not impose any additional regulatory requirements on sources 
beyond those required by state law. A redesignation to attainment does 
not in and of itself impose any new requirements, but rather results in 
the application of requirements contained in the CAA for areas that 
have been redesignated to attainment. Moreover, the Administrator is 
required to approve a SIP submission that complies with the provisions 
of the Act and applicable Federal regulations. 42 U.S.C. 7410(k); 40 
CFR 52.02(a). Thus, in reviewing SIP submissions, the 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);
     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); and
     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 Clean Air Act;
    Executive Order 12898 (Federal Actions to Address Environmental 
Justice in Minority Populations and Low-Income Populations, 59 FR 7629, 
February 16, 1994) directs Federal agencies to identify and address 
``disproportionately high and adverse human health or environmental 
effects'' of their actions on minority populations and low-income 
populations to the greatest extent practicable and permitted by law. 
The EPA defines environmental justice (EJ) as ``the fair treatment and 
meaningful involvement of all people regardless of race, color, 
national origin, or income with respect to the development, 
implementation, and enforcement of environmental laws, regulations, and 
policies.'' The EPA further defines the term fair treatment to mean 
that ``no group of people should bear a disproportionate burden of 
environmental harms and risks, including those resulting from the 
negative environmental consequences of industrial, governmental, and 
commercial operations or programs and policies.''
    ACHD evaluated environmental justice considerations as part of its 
SIP submittal even though the CAA and applicable implementing 
regulations neither prohibit nor require an evaluation. The EPA's 
evaluation of ACHD's environmental justice considerations is described 
above in the section titled, ``Environmental Justice Considerations.'' 
The analysis was done for the purpose of providing additional context 
and information about this rulemaking to the public, not as a basis of 
the action. The EPA is taking action under the CAA on bases independent 
of ACHD's evaluation of environmental justice. Due to the nature of the 
action

[[Page 99799]]

being taken here, this action is expected to have a neutral to positive 
impact on the air quality of the affected area. In addition, there is 
no information in the record upon which this decision is based that is 
inconsistent with the stated goal of Executive Order 12898 of achieving 
environmental justice for people of color, low-income populations, and 
Indigenous peoples.
    In addition, this proposed rulemaking, for the redesignation and 
approval of the maintenance plan for the Allegheny County NAA, 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 the EPA notes that it will not 
impose substantial direct costs on tribal governments or preempt tribal 
law.

List of Subjects

40 CFR Part 52

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

40 CFR Part 81

    Environmental protection, Air pollution control, Carbon monoxide, 
Intergovernmental relations, Lead, Nitrogen dioxide, Ozone, Particulate 
matter, Reporting and recordkeeping requirements, Sulfur oxides, 
Volatile organic compounds.

Adam Ortiz,
Regional Administrator, Region III.
[FR Doc. 2024-28536 Filed 12-10-24; 8:45 am]
BILLING CODE 6560-50-P
```