Document ID: EPA-R03-OAR-2020-0157-0086
Agency: epa
Document Type: Rule
Title: Air Quality State Implementation Plans; Approvals and Promulgations: Pennsylvania; Allegheny County Area Attainment Plan for the 2012 Fine Particulate Matter National Ambient Air Quality Standard
Posted Date: 2021-05-14T04:00Z

[Federal Register Volume 86, Number 92 (Friday, May 14, 2021)]
[Rules and Regulations]
[Pages 26388-26401]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-09565]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R03-OAR-2020-0157; FRL-10023-27-Region 3]

Air Plan Approval; Pennsylvania; Allegheny County Area Attainment 
Plan for the 2012 Fine Particulate Matter National Ambient Air Quality 
Standard

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: The Environmental Protection Agency (EPA) is approving most 
elements of a state implementation plan (SIP) revision submitted by the 
Pennsylvania Department of Environmental Protection (PADEP) on behalf 
of the Allegheny County Health Department (ACHD) to address Clean Air 
Act (CAA or ``the Act'') requirements for the 2012 annual fine 
particulate matter (PM2.5) national ambient air quality 
standards (NAAQS or ``standards'') in the Allegheny County Moderate 
PM2.5 nonattainment area (the ``Allegheny County Area,'' or 
``the Area''). The revision constitutes a comprehensive plan to ensure 
the Allegheny County Area's timely attainment of the 2012 
PM2.5 NAAQS. EPA is approving this revision to the 
Pennsylvania SIP in accordance with the requirements of the CAA.

DATES: This final rule is effective on June 14, 2021.

ADDRESSES: EPA has established a docket for this action under Docket ID 
Number EPA-R03-OAR-2020-0157. All documents in the docket are listed on 
the https://www.regulations.gov website. Although listed in the index, 
some information is not publicly available, e.g., confidential business 
information (CBI) or other information whose disclosure is restricted 
by statute. Certain other material, such as copyrighted material, is 
not placed on the internet and will be publicly available only in hard 
copy form. Publicly available docket materials are available through 
https://www.regulations.gov, or please contact the person identified in 
the FOR FURTHER INFORMATION CONTACT section for additional availability 
information.

FOR FURTHER INFORMATION CONTACT: Brian Rehn, Planning & Implementation 
Branch (3AD30), Air & Radiation Division, U.S. Environmental Protection 
Agency, Region III, 1650 Arch Street, Philadelphia, Pennsylvania 19103. 
The telephone number is (215) 814-2176. Mr. Rehn can also be reached 
via electronic mail at rehn.brian@epa.gov.

SUPPLEMENTARY INFORMATION: Throughout this document, ``we,'' ``us,'' 
and ``our'' refer to EPA.

Table of Contents

I. Background
II. Summary of SIP Revision and EPA Proposed Action
III. Public Comments and EPA Responses
IV. Final Action
    A. Approval of the Attainment Plan and Related Elements
    B. Conditional Approval of the Contingency Measures Portion of 
the Attainment Plan
V. Statutory and Executive Order Reviews

I. Background

    Epidemiological studies have shown statistically significant 
correlations between elevated levels of PM2.5 (particulate 
matter with a diameter of 2.5 microns or less) and premature mortality. 
Other important health effects associated with PM2.5 
exposure include aggravation of respiratory and cardiovascular disease, 
changes in lung function, and increased respiratory symptoms. 
Individuals particularly sensitive to PM2.5 exposure include 
older adults, people with heart and lung disease, and children.\1\ 
PM2.5 can be emitted directly into the atmosphere as a solid 
or liquid particle (``primary PM2.5'' or ``direct 
PM2.5'') or can be

[[Page 26389]]

formed in the atmosphere as a result of various chemical reactions 
among precursor pollutants such as nitrogen oxides (NOX), 
sulfur oxides, volatile organic compounds, and ammonia (``secondary 
PM2.5'').\2\
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    \1\ See National Ambient Air Quality Standards for Particulate 
Matter; (2012) Final Rule (78 FR 3086-3088, January 15, 2013).
    \2\ See Clean Air Fine Particle Implementation Rule; Final Rule 
(72 FR 20586, 20589, April 25, 2007).
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    EPA first established annual and 24-hour NAAQS for PM2.5 
on July 18, 1997.\3\ The annual standard was set at 15.0 micrograms per 
cubic meter ([micro]g/m\3\), based on a 3-year average of annual mean 
PM2.5 concentrations, and the 24-hour (daily) standard was 
set at 65 [micro]g/m\3\, based on the 3-year average of the annual 98th 
percentile values of 24-hour PM2.5 concentrations at each 
monitor within an area.\4\ On October 17, 2006, EPA revised the level 
of the 24-hour PM2.5 NAAQS to 35 [micro]g/m\3\, based on a 
3-year average of the annual 98th percentile values of 24-hour 
concentrations.\5\ On January 15, 2013, EPA revised the annual standard 
to 12.0 [micro]g/m\3\, based on a 3-year average of annual mean 
PM2.5 concentrations.\6\ We refer to this standard as the 
2012 PM2.5 NAAQS. The SIP submission at issue in this action 
pertains to the 2012 PM2.5 NAAQS.
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    \3\ See National Ambient Air Quality Standards for Particulate 
Matter (1997); Final Rule (62 FR 38652, July 18, 1997). The initial 
NAAQS for PM2.5 included annual standards of 15.0 
[micro]g/m3, based on a 3-year average of annual mean 
PM2.5 concentrations and 24-hour (daily) standards of 65 
[micro]g/m3, based on a 3-year average of 98th percentile 
24-hour concentrations (40 CFR 50.7).
    \4\ The primary and secondary standards were set at the same 
level for both the 24-hour and the annual PM2.5 
standards.
    \5\ See National Ambient Air Quality Standards for Particulate 
Matter; Final Rule (71 FR 61144, October 17, 2006).
    \6\ See National Ambient Air Quality Standards for Particulate 
Matter; Final Rule (78 FR 3086, January 15, 2013).
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II. Summary of SIP Revision and EPA Proposed Action

    EPA designated and classified the Allegheny County Area as 
``Moderate'' nonattainment for the 2012 PM2.5 NAAQS.\7\ On 
September 30, 2019, PADEP submitted the Allegheny County 
PM2.5 Plan SIP revision, on behalf of ACHD, in order to meet 
the applicable requirements for Moderate areas and to provide for 
attainment of the 2012 PM2.5 NAAQS in the Allegheny County 
Area. The SIP revision contains the attainment demonstration for the 
Allegheny County Area (also referred to as ``the Allegheny County 
PM2.5 Plan'' or ``the Plan''). On June 12, 2020 (85 FR 
35852), EPA proposed to fully approve the following elements of the 
Allegheny County PM2.5 Plan: The base year emissions 
inventory, the particulate matter precursor contribution demonstration, 
the reasonably available control measures/reasonably available control 
technology (RACM/RACT) element, the air quality modeling demonstration 
supporting attainment by the attainment deadline, the reasonable 
further progress (RFP) analysis, and the quantitative milestones to 
ensure timely attainment.\8\
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    \7\ See Air Quality Designations for the 2012 Primary Annual 
Fine Particle (PM2.5) National Ambient Air Quality 
Standards (NAAQS); Final Rule (80 FR 2206, January 15, 2015).
    \8\ See Allegheny County Area Attainment Plan for the 2012 Fine 
Particulate Matter National Ambient Air Quality Standard; Proposed 
Rulemaking (85 FR 35852, June 12, 2020).
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    Having identified deficiencies (and having obtained a commitment to 
remedy those deficiencies within one year of final action), EPA 
proposed a conditional approval of the contingency measures and the 
2021 motor vehicle emission budget (MVEB) element of the Allegheny 
County PM2.5 Plan. Pennsylvania committed (via an April 20, 
2020 letter to EPA) to submit a supplemental SIP revision to remedy 
those two elements of the Plan by no later than twelve months after 
EPA's final conditional approval action.
    As part of our June 12, 2020 proposal, we proposed to find that the 
suite of PM2.5 control requirements in the Allegheny County 
PM2.5 Plan meets all RACM/RACT requirements for the control 
of direct PM2.5 and PM precursors and to approve the 
PM2.5 RACM evaluation as meeting the applicable 
nonattainment area plan requirements under CAA sections 172(c)(1) and 
189(a)(1)(C) and 40 CFR 51.1009.
    EPA also proposed to find that the attainment demonstration in the 
Allegheny County PM2.5 Plan satisfies the requirements of 
sections 189(a)(1)(B) and 172(c)(1) of the CAA and 40 CFR 51.1011(a). 
In support of this proposal, we found that the ACHD relied upon 
acceptable modeling techniques to demonstrate attainment of the 2012 
PM2.5 NAAQS in the Allegheny County Area, and that the Plan 
demonstrates attainment of the 2012 PM2.5 NAAQS as 
expeditiously as practicable. We determined that the Allegheny County 
PM2.5 Plan provides a convincing justification that emission 
reductions from the control measures listed in the Plan will provide 
for timely attainment of the 2012 PM2.5 NAAQS by the 
December 31, 2021 attainment date. Our June 12, 2020 proposed rule 
provides a more detailed discussion of our evaluation of the Plan.\9\
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    \9\ Id.
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    Other specific requirements applicable to attainment plans under 
the 2012 PM2.5 NAAQS and the rationale for EPA's proposed 
action are explained in the June 12, 2020 proposed rule, and its 
associated technical support documents (TSDs), and will not be restated 
here.

III. Public Comments and EPA Responses

    The June 12, 2020 proposed action to approve the Allegheny County 
PM2.5 Plan opened a public comment period, which ended on 
July 13, 2020. Following a request for additional time from a public 
advocacy group, EPA published a document on July 31, 2020 reopening and 
extending the public comment period through August 13, 2020.\10\ EPA 
received public comments from several environmental groups and several 
individual commenters. The comments received have been placed in the 
docket for this action. EPA's summary of the significant adverse 
comments received on the proposed action and our responses to those 
comments are listed below.
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    \10\ See 85 FR 46046, July 31, 2020.
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    Comment 1: The commenter requests that EPA consider the lateness of 
ACHD submission of the Plan (nearly three years after the due date) 
when assessing the ``credibility'' of ACHD's attainment demonstration. 
The commenter contends that ACHD's stated reason for being late (i.e., 
the complexity of the plan analysis) is inadequate justification for 
the lateness. The commenter states that if ACHD had not submitted a 
plan to EPA before the 18-month sanctions clock deadline, the Allegheny 
PM2.5 nonattainment area would have been subject to 
sanctions, including a more stringent emissions offset ratio 
requirement applicable to new and modified major stationary sources. 
The commenter posits that the delay in submitting this Plan provides 
``context'' for flaws in the submitted plan.
    Response 1: Although the Commonwealth submitted the Allegheny 
County Plan well after the October 15, 2016 CAA statutory deadline, EPA 
disagrees with the commenter's assertion that this delay in submission 
must be presumed to result in a flawed Plan. Lateness of the Plan in 
and of itself does not interfere with the ability of ACHD to prepare an 
attainment plan meeting the CAA and related EPA regulatory 
requirements. Section 110(k) requires EPA to evaluate and to act upon 
SIP submissions from states. EPA has authority to approve, disapprove, 
or conditionally approve a SIP submission, in whole or in part, based 
upon whether the submission meets all applicable requirements. Lateness 
of a state's submission of the

[[Page 26390]]

Plan to EPA does not affect EPA's obligation to evaluate and act upon 
the SIP submission based on its merits, consistent with those 
requirements. As explained in the proposed action, EPA has determined 
that the SIP submission from ACHD does meet most of the applicable 
requirements as submitted. However, EPA is herein requiring that 
Pennsylvania meet these applicable requirements when addressing the 
conditional approval of the contingency measures' requirement.
    Regarding the sanctions process mentioned by the commenter, EPA's 
finding of failure to submit deficiency was remedied by EPA's November 
1, 2019 letter determining that PADEP's September 30, 2019 SIP 
submittal of the Plan was complete.\11\ At that point, sanctions under 
section 179 of the CAA for failing to submit the required nonattainment 
plan ceased to be applicable. If Pennsylvania fails to remedy the 
identified conditions of the conditional approval, converting those 
elements of the Plan to a disapproval, then that disapproval would 
constitute a new finding under the terms of CAA section 179(a), 
beginning a new 18-month period prior to potential application of 
sanctions described by CAA section 179(b). EPA's conversion of the 
proposed conditional approval into a final conditional approval by this 
action will prevent the further imposition of CAA section 179(b) 
sanctions unless Pennsylvania does not submit the required elements of 
the Plan by the deadline under the final conditional approval, i.e., 
one year from the date of EPA's final conditional approval.
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    \11\ See Document EPA-R03-OAR-2020-0157-0045 in the docket for 
this action at www.regulations.gov.
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    Comment 2: The commenter states that EPA should require more 
rigorous analyses from ACHD for the Plan since it contains air quality 
modeling tailored to attaining the NAAQS of 12.0 [mu]g/m\3\ precisely, 
with no margin of safety. The commenter cites EPA's 2018 ``Guidance for 
Attainment Demonstrations for PM2.5,'' which states that 
``supplemental evidence should accompany all model attainment 
demonstrations'' \12\ and that ``generally, those modeling analyses 
that show that attainment will be reached in the future with some 
margin of safety will need more limited supporting material,'' \13\ and 
goes on to state that ``for other attainment cases in which the 
projected future design value is closer to the NAAQS, more rigorous 
supporting analyses should be completed.'' \14\ The commenter points 
out that ACHD's modeling projects attainment at exactly the level of 
the NAAQS (i.e., 12.0 [mu]g/m\3\) and the commenter thus believes EPA 
should adhere to its guidance by compelling ACHD to provide more 
rigorous analyses to support its attainment demonstration.\15\
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    \12\ See EPA, Modeling Guidance for Demonstrating Air Quality 
Goals for Ozone, PM2.5 and Regional Haze (November 29, 
2018), p. 169, available in the online docket for this action at 
www.regulations.gov, Document ID EPA-R03-OAR-2020-1057-0068.
    \13\ Id.
    \14\ Id.
    \15\ See ACHD September 30, 2019 SIP revision Main Document, 
(Table 5-5, Base and Future Design Values ([mu]g/m\3\), Liberty), p. 
36. Available at www.regulations.gov, Document ID EPA-R03-OAR-2020-
1057.
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    The commenter questions the credibility of ACHD's Plan, given 
public statements by ACHD that it is prohibited from developing a 
control strategy for NAAQS attainment that reduces emissions to levels 
that would result in air quality that is better than the level required 
for purposes of the 2012 PM2.5 NAAQS. The commenter argues 
that ACHD's contention in the Plan that they are prevented by state/
local law from adopting a control strategy that exceeds Federal 
requirements (i.e., that provides emission reductions resulting in an 
attainment year design value below the 12.0 [mu]g/m3 standard) is not 
supported by state or local law.
    Response 2: EPA acknowledges that its guidance recommends that 
modeling demonstrations projecting PM2.5 design value 
concentrations that are close to the level of NAAQS (as is the case for 
the Liberty Monitor at issue in the Plan) should have more supporting 
evidence and analyses. EPA's November 2018 Ozone, PM2.5 and 
Regional Haze guidance directs that supplemental evidence should 
accompany all model attainment demonstrations and that, generally, 
those modeling analyses that show that attainment will be reached in 
the future with some margin of safety will need more limited supporting 
material. However, for other attainment cases in which the projected 
future design value is closer to the NAAQS, more rigorous supporting 
analyses should be completed.\16\
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    \16\ See EPA's November 2018 Ozone, PM2.5 and 
Regional Haze guidance, p. 169.
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    Based on information provided in the weight of evidence (WOE) 
analysis submitted as part of the Allegheny County PM2.5 
Plan, including information from the electric grid operator for the 
area (PJM Interconnection, LLC), EPA has concluded that Allegheny 
County has performed a ``more rigorous supporting analyses'' in support 
of its modeling analysis demonstration that meets EPA's guidance. The 
Plan projects that all monitors in the Allegheny County 
PM2.5 nonattainment area will comply with the 2012 
PM2.5 NAAQS by the required 2021 attainment date.\17\ The 
commenter did not mention the Plan's WOE analysis or PJM data in its 
comment, so it is not clear if the commenter was aware of their 
existence. Allegheny County's WOE analysis shows declining 
PM2.5 monitor concentrations, additional source emission 
reductions not included in the modeling analysis, precursor sulfur 
dioxide (SO2) reductions imposed in Allegheny County's 1-
hour SO2 SIP, reductions in emissions due to electric 
generating unit (EGU) shutdowns within the PJM Interconnection 
territory, a comparison of model SO2/NOX EGU 
emissions showing potential excess precursor emissions in the projected 
year model inventory (see Appendix K of ACHD`s SIP submittal) which 
could lead to a model overprediction bias, overall emission reductions 
due to declining local population trends, and additional emission 
reductions associated with several local control measures. These 
represent additional analyses that would not be necessary if the 
modeling projected attainment at a design value below 12.0 [mu]g/m\3\. 
Also, the commenter does not elaborate on why ACHD's analysis is 
inadequate, other than to assert that it should be more rigorous. 
Finally, the commenter did not provide any additional analyses or 
evidence supporting its assertion that Allegheny County's SIP will not 
provide for attainment of the PM2.5 NAAQS by the statutory 
attainment date (see response to comment 4 regarding current 
PM2.5 design values in Allegheny County). In the absence of 
any contrary evidence, upon EPA's review of the SIP submission 
including the modeling and additional evidence supporting the predicted 
attainment by the attainment date, EPA concludes that ACHD's Plan will 
bring the area into attainment.
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    \17\ See Appendix M of ACHD's September 12, 2019 SIP revision, 
comments 69 and 70.
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    The commenter asserts that there is no legal prohibition at the 
state or county level preventing the state or county from requiring a 
greater level of emission reductions of direct PM2.5 or 
PM2.5 precursors that would allow the Area to model 
attainment at a design value below 12.0 [mu]g/m\3\. However, the 
existence or nonexistence of such a prohibition is not germane to the 
task at hand, which is determining whether the submitted Plan will 
result in attainment of the 2012 PM2.5 NAAQS in Allegheny 
County by the attainment date. In this case, the attainment modeling 
projecting

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that the design value for this Area will meet the NAAQS limit by the 
attainment date is sufficient to demonstrate that the PM2.5 
NAAQS will be met, in accordance with CAA requirements.
    Comment 3: The commenter claims that EPA's 2018 guidance does not 
allow the use of a Local Area Analysis (LAA) in order to disregard a 
modeled future (i.e., attainment year) design value that is higher than 
the NAAQS. The commenter asserts this is not reasonable because the 
purpose of the attainment demonstration analysis is to facilitate a 
control strategy, rather than as a substitute for a forecast of 
nonattainment. The commenter states that after calculating a future 
design value of 12.6 [mu]g/m\3\ at the Liberty monitor using CAMx 
modeling, ACHD rejected the result and instead conducted a supplemental 
LAA, the results of which ACHD instead used to demonstrate that the 
attainment year design value test was met.
    The commenter notes that ACHD acknowledges that the CAMx model, 
which is EPA's recommended model for PM2.5, can address 
local impacts as well as regional impacts by selecting certain 
available options within the CAMx model. The commenter also alleges 
that despite the fact that the CAMx modeling addressed local impacts, 
ACHD ignored those CAMx-derived local impacts in favor of a separate 
LAA that used AERMOD to determine those local impacts, which were then 
fed back into the CAMx model.\18\ The commenter argues that this 
approach is not consistent with EPA's PM2.5 attainment 
demonstration guidance. Further, the commenter states that the purpose 
of a LAA is not to engineer a design value that will just meet the 
NAAQS, but rather to supplement the results of the attainment test.
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    \18\ Id. See section 5.4.1 [Liberty LAA Methodology], p. 33.
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    The commenter asserts that EPA's 2018 Guidance cites the relative 
attainment tests described in sections 4.2, 4.4.2 and 4.5 of the 
guidance as the primary modeling tools used in an attainment 
demonstration, and that use of a chemical transport grid model on a 
regional or local scale is the best tool available to judge the impacts 
of changes in future year emissions on concentrations. The commenter 
further argues that ``while the Agency contemplates other models, the 
purpose is only to `supplement' the results of the modeled attainment 
test.'' \19\ The commenter notes that when EPA's guidance indicates 
that while use of such models ``may be useful as a supplemental 
analysis . . .'' it is speaking to the control strategy rather than to 
the attainment demonstration itself.
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    \19\ Id. Pp. 171-172.
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    The commenter argues that EPA's guidance does not state that a 
supplemental dispersion model could be the basis for the actual 
attainment test, which is the result reached by ACHD. The commenter 
disagrees (both from a policy and a legal perspective) with ACHD's 
rationale, which seeks to characterize the sources contributing to 
levels of fine particulates at the Liberty Monitor, based on statements 
in ACHD's modeling demonstration that ``Source characterization with 
CAMx was likely not fully representative of some sources near Liberty, 
specifically for some processes at the USS Clairton Plant,'' and that 
``Refined modeling with AERMOD can more accurately account for many 
processes with the use of different source types . . .'' The commenter 
argues that a question regarding relative contribution among sources is 
separate from a question regarding the reliability of modeling results 
obtained through the use of CAMx.
    The commenter argues that ACHD's other rationales for use of a LAA 
are also invalid, surmising that if CAMx were conservative with its EGU 
assumptions, that would not make the CAMx modeling flawed.\20\ 
Similarly, the commenter argues that if ``some local primary 
PM2.5 emissions were overestimated with the inventory used 
for the CAMx modeling,'' that would not be a justification for 
abandoning the CAMx model.\21\ The commenter further argues that 
suggestions that the spatial grading in the CAMx model is ``likely too 
large to properly simulate localized impacts at Liberty'' or that 
``species are not being properly apportioned by the modeled results'' 
are also not justifiable.\22\
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    \20\ Id.
    \21\ Id.
    \22\ Id.
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    The commenter argues that while EPA guidance contemplates that 
PM2.5 measurement data from monitors may not be 
representative of ``area-wide'' air quality and therefore not suitable 
for comparison with the standard, this statement is limited to ``micro-
scale'' and ``middle-scale'' sites.\23\ The commenter contends that by 
preparing a LAA with ``supplemental'' modeling and then using this to 
replace the ``primary'' modeling analysis, ACHD has made a 
determination that the Liberty Monitor data is unsuitable for 
comparison with the NAAQS--a determination that is contradicted by the 
fact that the Liberty Monitor is a core PM2.5 site 
(characterized in the monitoring plan as a ``neighborhood'' site) that 
is used to determine compliance with NAAQS.\24\
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    \23\ See EPA ``Modeling Guidance for Demonstrating Air Quality 
Goals for Ozone, PM2.5 and Regional Haze,'' p. 133, which 
states, ``PM2.5 measurement data from monitors that are 
not representative of ``area-wide'' air quality, but rather of 
relatively unique micro-scale, or localized hot spot, or unique 
middle-scale impact sites, are not eligible for comparison to the 
annual PM2.5 NAAQS.''
    \24\ See ACHD 2020 Air Monitoring Network Plan, page 33, Section 
10.2.
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    The commenter argues that these supporting arguments prevent use of 
an alternative LAA to ignore the projected 2021 Liberty 12.5 [micro]g/
m\3\ CAMx modeled design value from the primary analysis in lieu of the 
lower 12.0 [micro]g/m\3\ design value provided by ACHD's LAA.
    Response 3: The Community Air Quality Model with Extensions \25\ or 
CAMx, with a 1.33-kilometer (km) grid, projected 2021 model results are 
summarized in Table 5-4 of Allegheny County's main SIP document. 
Projected 2021 PM2.5 design value concentrations for all 
Allegheny County monitors except for the Liberty Monitor, which was not 
included in the table, are below the 24-hr and annual PM2.5 
NAAQS. Results from EPA's Model Attainment Test Software (MATS, version 
2.6.1) for all of the Allegheny County monitors are listed in Appendix 
I.1 of Allegheny County's SIP document. Projected 2021 PM2.5 
concentrations are included in Table 3.6 of Appendix I.1 (for annual 
PM2.5 NAAQS) and Table 3.7 of Appendix I.1 (for the 24-hour 
PM2.5 NAAQS). Liberty's CAMx projected 2021 annual 
PM2.5 design value is 12.5 [micro]g/m\3\ and its projected 
24-hour PM2.5 design value is 38.6 [micro]g/m\3\, which 
exceed both the Annual and 24-hour PM2.5 NAAQS.
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    \25\ CAMx is a state-of-the-science photochemical grid model 
that comprises a ``one-atmosphere'' treatment of tropospheric air 
pollution over spatial scales ranging from neighborhoods to 
continents. See the CAMx web page, at: www.camx.com/about/default.aspx.
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    Allegheny County's SIP document outlines several reasons why it 
believes CAMx has overstated projected 2021 PM2.5 design 
values at the Liberty Monitor (see page 32 of the main SIP document). 
These points include over-projections of future SO2 and 
NOX in the EGU sector (see EPA's TSD regarding PJM 
Interconnection, LLC EGU fuel usage and projected year emission 
differences within the 4-km CAMx domain for additional support on this 
point), overestimated local primary PM2.5 emissions, too 
coarse spatial resolution of CAMx domain (1.33 km)

[[Page 26392]]

used in the projected 2021 PM2.5 concentrations, and CAMx's 
uniform treatment of all emissions as emanating from stack point 
sources when a significant number of sources at some of the larger US 
Steel plants are better represented as (fugitive) volume or area source 
types. Additional discussion of these points can be found in Appendix 
I.2 and Appendix F.3 of the Allegheny County Plan SIP.
    The commenter offers several points to counter Pennsylvania's LAA, 
but EPA's guidance clearly allows an option to utilize a Gaussian type 
air-dispersion model (such as AERMOD) to model the primary components 
of PM2.5 (organic carbon (OC), elemental carbon (EC) and 
other primary PM2.5 (OPP)) and to exclude chemically 
reactive components of PM2.5 such as sulfate and nitrate. 
Per EPA's ``Modeling Guidance for Demonstrating Air Quality Goals for 
Ozone, PM2.5 and Regional Haze,'' dated November 29, 2018, 
states that, ``local influences creating large spatial gradients are 
likely to consist mostly of primary PM2.5 (OC, EC, and OPP). 
These sources may be point sources, or they may be nearby roads or 
other mobile or area sources.'' \26\
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    \26\ See section 4.6.1 of EPA's ``Modeling Guidance for 
Demonstrating Air Quality Goals for Ozone, PM2.5 and 
Regional Haze,'' November 29, 2018.
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    PM2.5 monitor concentrations in Allegheny County show 
there is a significant concentration (spatial) gradient near the 
Liberty Monitor site (see Allegheny County monitor's current 2017-19 
PM2.5 design value maps contained in the attached technical 
support document). Liberty's current design values are 16-29% higher on 
the annual basis and 34-48% higher on the 24-hour basis than the two 
nearest PM2.5 monitors (Clairton and North Braddock). 
Furthermore, Liberty's PM2.5 speciation breakdown from CAMx 
shows it has substantially higher values in its OC, EC and OPP 
components than the other monitors in Allegheny County (see Tables 3.6 
and 3.7 in Appendix I.1). Documentation of high OC, EC and OPP is 
needed to justify using the Gaussian (AERMOD) dispersion model.
    EPA's guidance directs that a grid model can be run at very high 
horizontal resolution (1 or 2 km or finer) or a Gaussian dispersion 
model can be used.\27\ Grid-based models simulate chemical 
transformation and complex meteorological conditions, while dispersion 
models are generally more simplistic; being limited to a local-scale, 
using Gaussian approximations with little or no chemistry. Therefore, 
while dispersion models may not be an appropriate tool for determining 
secondary PM2.5 or ozone concentrations, they work well for 
use in determining local primary PM2.5 impacts.
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    \27\ Id. Section 4.6.1.
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    The commenter asserts that the Allegheny County Area 
PM2.5 plan's modeling demonstration ``abandons'' the (1.33 
km) CAMx demonstration results. This significantly mischaracterizes 
ACHD's PM2.5 SIP modeling demonstration. Allegheny County 
indicated that it was using the LAA for the Liberty Monitor to remodel 
the primary (nonreactive) PM2.5 components of its modeling 
demonstration, while retaining the chemically reactive PM2.5 
species from CAMx. In essence, it is removing only the nonreactive 
portion of PM2.5 generated by CAMx, in accordance with EPA 
guidance, and replacing values from the nonreactive chemical CAMx 
species with results from a Gaussian dispersion model (AERMOD). This 
AERMOD modeling was performed using the same meteorological Weather 
Research and Forecasting (WRF) model data set via EPA's Mesoscale Model 
Interface Program (MMIF) that was used in the CAMx modeling.
    Allegheny County further justified developing and using its LAA 
based on improved model spatial resolution and source characterizations 
available via this pathway. The CAMx model, while relative fine-scaled 
(approximately 1.33 km grid spacing), is still coarse when considering 
some of the large primary PM2.5 emission sources in 
Allegheny County. In essence, all emissions are inserted into CAMx at a 
horizontal scale of approximately 1.33 km and within specified vertical 
layers within CAMx. The CAMx model distributes emissions across the 
entire grid box in which they are emitted, and because of this 
artificial dilution the distribution of these emissions in CAMx may be 
represented in the model as artificially high outside of the source 
plume and artificially low within the source plume. Such artificial 
dilution is not problematic for regional scale air quality modeling 
purposes, but can impact local scale modeling of plumes, as is the case 
here. ACHD pursued plume-in-grid and AERMOD dispersion modeling to 
better resolve the emission sources' plume transport and dispersion 
that were not well resolved with the base CAMx modeling. To alleviate 
this issue, Allegheny County's CAMx modeling system utilized a plume in 
grid parameterization that withholds a portion of emissions from being 
directly released across the entire model grid cell; without plume in 
grid, CAMx would instantaneously disperse source emissions across a 
full grid when in reality the plume will spread more slowly from its 
release point.
    Spatial resolution for a Gaussian dispersion model such as AERMOD 
is not limited in scale; and AERMOD can resolve emissions and processes 
more finely than the CAMx model. Additionally, AERMOD has multiple 
source characterizations available while CAMx can only model stack-like 
point source releases. CAMx treats fugitive emissions using a point 
source parameterization that does not resolve the emissions in 
sufficient detail to properly characterize the impacts of important 
PM2.5 sources such as fugitive releases from the US Steel 
sources in this nonattainment area modeling demonstration. Near the 
Liberty Monitor, there are prominent fugitive emission sources that 
include coke oven emissions (oven leaks, pushing, charging, quenching 
and material handling). AERMOD can more finely resolve these fugitive 
emissions to ensure better placement of these emissions into the 
modeling domain, resulting in a better prediction of source impacts in 
the local area near the source and a better estimate of the projected 
DV. Allegheny County's SIP followed EPA guidance in the development, 
running and processing of its LAA.
    For these reasons, EPA believes Allegheny County is justified in 
conducting a LAA using a Gaussian dispersion model (AERMOD) to more 
accurately project the Liberty Monitor's 2021 PM2.5 design 
values. Furthermore, Allegheny County has fully documented that it has 
followed EPA's guidance in executing its LAA.
    Comment 4: The commenter asserts that ACHD's 2021 modeling 
projection is flawed and unreasonable because the selected 2011 base 
year is unrepresentative of current and potential future meteorological 
conditions for the area. The commenter contends that the area 
experienced an unusually low number of atmospheric inversions and 
higher than normal annual precipitation in 2011. Given the importance 
of meteorological inputs in modeling, the commenter believes the 2011 
meteorological data will result in lower modeled PM2.5 
concentrations for 2021 than modeling using another year's 
meteorological data. As evidence that 2011 is unrepresentative of 
current and future meteorological conditions, the commenter cites 
ACHD's meteorological analysis, which states, ``more recent years have 
recorded above normal average temperatures along with precipitation 
amounts substantially above normal; therefore, the 2011 base year may 
well represent these more

[[Page 26393]]

current conditions.'' The commenter contends that while ACHD used the 
Weather Research and Forecasting (WRF) meteorological model for the 
Allegheny County domain, stating that is has been determined to produce 
appropriate representative meteorological conditions to provide 
meteorological inputs for the air quality modeling, they also cautioned 
that the accuracy of the modeling is dependent upon the 
``representativeness of the meteorological dataset.''
    The commenter argues that 2011 had a lower than average number of 
temperature inversions (134 days versus an average of 157 days with 
inversions from 2008 to 2018), and that the location where temperature 
inversions are measured (the Pittsburgh International Airport) will 
have not only fewer temperature inversions in a year than the low-lying 
valleys that make up most of the nonattainment area, but also that the 
strength of the inversions will be greater in the valleys. The 
commenter argues that 2012 meteorological data would be more 
representative because it had only one more temperature inversion than 
the average from 2008 to 2018.
    The commenter argues that with respect to precipitation, the 
selected 2011 base year is not representative because Allegheny County 
experienced 44.24 inches of precipitation that year, which is more than 
six inches greater than the NWS 30-year mean for the period 1981-2010 
\28\ and was over four-and-one-half inches greater than the average 
between 1991-2019. The commenter contends that ACHD's choice of 2011 
precipitation data is a statistical outlier, exceeded only five years 
in the most recent thirty. The commenter contends that ACHD is 
appealing to climate change as a basis for use of unrepresentative 
meteorological conditions in modeling future year emissions, contrary 
to EPA guidance.\29\ Finally, the commenter contends that ACHD did not 
follow EPA's guidance by using meteorological inputs for modeling that 
are conducive to elevated PM2.5 concentrations.\30\
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    \28\ See National Weather Service, Pittsburgh Historical 
Precipitation Totals 1836 to Current, at: www.weather.gov/media/pbz/records/hisprec.pdf.
    \29\ See 2019 Modeling Guidance for Demonstrating Air Quality 
Goals for Ozone, PM2.5 and Regional Haze, Section 2.6.2 
(Assessing Impacts of Future Year Meteorology), page 32, at 
www.regulations.gov: Document ID EPA-R03-OAR-2020-0157-0068.
    \30\ See U.S. EPA, Modeling Guidance for Demonstrating Air 
Quality Goals for Ozone, PM2.5 and Regional Haze, Section 
2.3.1 (Choosing Time Periods to Model), page 20.
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    Response 4: Multiple factors are considered in selecting a base 
year for modeling purposes. ACHD considered meteorology, source 
emissions data, and monitoring data, and ultimately selected 2011, due 
to the availability of the 2011 National Emissions Inventory (NEI) as 
well as the availability of reasonably representative monitoring and 
meteorological data. In some cases, choice of available actual data 
eases the burden of adjusting or altering the data to represent other 
possible base years (e.g., the availability of 2011 NEI year data lends 
itself to selection of a 2011 base year without adjustment). Allegheny 
County provided an overview of its base year selection in several 
sections of its SIP documentation, namely its Problem Statement 
(Section 2) of the SIP and the CAMx Model Protocol (Appendix F.2). 
Estimates of the effects of climate change over the short time periods 
and small spatial scales (i.e., for the purpose of attainment of the 
PM2.5 NAAQS by the attainment deadline) would be too 
uncertain to add value.
    EPA reviewed Clean Air Council's climatological information for 
Pittsburgh International Airport (temperature and precipitation) and 
inversion strength information generated by the Allegheny County Health 
Department (ventilation rate). A more detailed analysis of Pittsburgh 
International Airport's 30-year temperature and precipitation as well 
as Allegheny County's inversion strength summary is included as a 
separate TSD. EPA will summarize its findings in the next several 
paragraphs.
    EPA analyzed daily temperature and precipitation information 
collected at the Pittsburgh International Airport weather station over 
a 30-year period between 1990 to 2019, listed at the Pennsylvania State 
Climatological website.\31\ EPA focused our review on the 2011 base 
year and the other years that are used to reconstruct the base year 
design values. All years that include 2011 in the Allegheny County 
monitoring design values, and that were used in the model attainment 
test, were considered (i.e., the periods 2009-11, 2010-12 and 2011-13). 
While monthly and annual average temperatures and total precipitation 
values for 2011 do sometimes vary from the 30-year averages, they 
generally fall within 1 standard deviation of the mean. This means that 
while temperatures and precipitation totals may differ from their 30-
year means, the differences in precipitation and temperature would not 
be considered statistically significant outliers in the normal 
distribution (for example several standard deviations from the 30-year 
means). Additionally, the commenter has not established that there is a 
strong correlation between the meteorological conditions (i.e., 
temperature and precipitation values) at the Pittsburgh International 
Airport's weather station and the projected PM2.5 design 
values for Allegheny County monitors, especially the Liberty Monitor.
---------------------------------------------------------------------------

    \31\ See www.climate.met.psu.edu/data/ida/ for select FAA daily 
summaries.
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    EPA also reviewed and updated the inversion strength information 
that is developed by the Allegheny County Health Department as part of 
its assessment of daily dispersion characteristics.\32\ Allegheny 
County has identified a correlation with inversions and elevated 
PM2.5 concentrations within the county and has included it 
in several sections of its SIP documentation (problem statement section 
of the main SIP and more thoroughly discussed in Appendices B and F). 
EPA's review of Allegheny County's most recent 2019 annual inversion 
summary report, available on Allegheny County's website, shows that the 
2011 model base year has an unusually low number of days without 
significant inversions and the number of inversion days in 2011 lies 
outside 1 standard deviation of the 2008-19 average. EPA's analysis 
also shows the Liberty Monitor's annual quarterly means and 98th 
percentile 24-hour PM2.5 concentrations do appear to 
correlate well with Allegheny County's inversion day totals; 
PM2.5 concentrations, both 24-hour and annual, are higher 
during years with more inversion days. EPA therefore finds merit with 
the commenter's point that Allegheny County's base year 2011 is 
unrepresentative of the yearly number of inversions because it has a 
significantly lower number of inversion days, which could lead the 
modeling to skew lower in its PM2.5 concentrations.
---------------------------------------------------------------------------

    \32\ See ACHD's monitoring data web page, at: 
www.alleghenycounty.us/Health-Department/Programs/Air-Quality/
Monitored-Data.aspx, under ``Air Dispersion Reports.''
---------------------------------------------------------------------------

    While we acknowledge the commenter's concern that Allegheny 
County's 2011 meteorological data has a lower number of inversion days 
than other years, EPA disagrees with the commenter's assertion that 
Allegheny County's selection of 2011 as its base year will lead to 
projected 2021 PM2.5 design values that are lower than would 
otherwise be projected using other years of meteorological data. The 
selection of a base year with fewer than usual number of inversion days 
will be mostly muted by how the modeled attainment test is constructed. 
This is because the

[[Page 26394]]

PM2.5 model demonstration uses modeling in a ``relative'' 
sense and not in an absolute sense.\33\ That is, the predicted model 
PM2.5 concentration for the projected year simulation is not 
directly used for attainment determination purposes, and instead is 
used to develop species-by-species PM2.5 relative reduction 
factors that are applied to a weighted base year design value (for each 
individual component of PM2.5). The influence of meteorology 
on model PM2.5 concentrations is dampened because 
projections are done using ratios of concentrations based on the same 
meteorology; the base-year and projection-year meteorology are 
identical. Furthermore, the weighted design value concept that EPA's 
guidance utilizes generates a base year (2011) monitor design value 
that is taken from multiple years of monitoring data. This partially 
offsets the impacts of selecting one or more years with favorable 
meteorology that may contribute to lower modeled concentrations.
---------------------------------------------------------------------------

    \33\ See Section 4.1 of EPA's Modeling Guidance for 
Demonstrating Air Quality Goals for Ozone, PM2.5 and Regional Haze, 
November 29, 2018 for additional discussion on the Model Attainment 
Test.
---------------------------------------------------------------------------

    Furthermore, the commenter's assertion that the selection of a year 
with an unrepresentative number of inversions (2011) as Allegheny 
County's base year would lead to an under-estimation of future monitor 
design values, and therefore attainment, does not hold up when 
Allegheny County's final projected 2021 design values are compared to 
the most recent (2017-19) monitor design values. If anything, Allegheny 
County's modeling results are over-predicting based on current design 
values.\34\ EPA used the modeled base year and future year design 
values for all of the Allegheny County monitors to calculate linear 
annual and 24-hour PM2.5 trend lines, then applied the model 
calculated change in PM2.5 concentration per year to 
generate a projected 2019 design value concentration.\35\ Further 
information on EPA's calculation of the projected 2019 design value 
calculation is available in the TSD prepared for this action. These 
values could then be compared with the actual monitor values to see how 
well Allegheny County's modeling demonstration could reproduce actual 
monitor design values. In nearly every case, the model projected design 
values that were higher than the actual monitor design values, 
suggesting that the model projections are conservative with respect to 
actual monitor PM2.5 design values. The most recent design 
values pulled from EPA's Air Quality System (AQS) indicate that only 
annual PM2.5 design values at the Liberty monitor exceed the 
NAAQS; Liberty's 2017-19 annual design value is 12.4 [micro]g/m\3\.
---------------------------------------------------------------------------

    \34\ EPA's analysis of modeled and monitored design values in 
Allegheny County is more fully explained in its TSD included as part 
of this response.
    \35\ See EPA's Supplemental TSD, ``Providing Responses to 
Comments Regarding the EPA's Proposed Approval of the Attainment 
Demonstration for the Allegheny County PM2.5 
Nonattainment Area, under the 2012 National Ambient Air Quality 
Standard,'' prepared October 2020.
---------------------------------------------------------------------------

    Based on Allegheny County's modeled yearly emission change (-0.24 
[micro]g/m\3\ per year), EPA expects Liberty will achieve the 
PM2.5 NAAQS by its projected attainment date of 2021. All 
other PM2.5 monitors inside Allegheny County currently meet 
the 2012 PM2.5 NAAQS, two years before the statutory 
attainment date. Allegheny County also included an unmonitored area 
analysis (Appendix I.3) to confirm the PM2.5 NAAQS will be 
met across the entire (county) nonattainment area.
    To summarize, EPA agrees with the commenter's point that the 
selected 2011 base year for the PM2.5 modeling demonstration 
has a lower than typical number of inversion days, but this fact does 
not undermine Allegheny County's attainment demonstration, because the 
model is being used in a relative sense and not an absolute sense. 
Lower modeled PM2.5 generation due to meteorology in the 
base year (fewer inversions) would likely lead to lower modeled 
relative reduction factors (that are applied to a multi-year-weighted 
base year design value). Furthermore, Allegheny County's projected 
PM2.5 concentrations appear to be overpredicting current 
PM2.5 design values (2017-19). All current PM2.5 
design values in Allegheny County meet the 2012 PM2.5 NAAQS 
except for the annual PM2.5 design value at Liberty. Using 
the Liberty Monitor's projected modeled PM2.5 reduction 
rate, this monitor is projected to attain the NAAQS by the area's 
December 31, 2021 statutory attainment date. The CAMx modeling projects 
that all other monitors in the area will attain by the 2021 attainment 
deadline.
    Comment 5: The commenter argues that instead of disregarding the 
CAMx modeled attainment year projected design value of 12.5 [mu]g/m\3\ 
at the Liberty Monitor, ACHD should have focused on strengthening the 
emission control strategy for U.S. Steel facilities in the Allegheny 
County PM2.5 nonattainment area. Instead, the commenter 
alleges that during its process to propose the attainment 
demonstration, ACHD claimed that it is not appropriate to require 
companies to make emissions reductions in the context of preparing 
attainment demonstrations. The commenter argues that section 110(a)(2) 
of the CAA directs states to ``include enforceable emission limitations 
and other control measures, or techniques . . . as may be necessary or 
appropriate to meet the applicable requirements of this chapter.'' The 
commenter contends that federal rules, specifically 40 CFR 
51.1009(a)(1), require a state to ``identify, adopt, and implement 
control measures, including control technologies, on sources of direct 
PM2.5 emissions and sources of emissions of PM2.5 
plan precursors,'' in the attainment plan control strategy and that 40 
CFR 51.1009(a)(2) requires the state to ``identify all potential 
control measures to reduce emissions from all sources of direct 
PM2.5 emissions and all sources of emissions of 
PM2.5 plan precursors in the nonattainment area.''
    In developing a control strategy to model attainment of the 
PM2.5 NAAQS, the commenter argues that ACHD should seek 
emission reductions from the largest sources of fine particulates, 
which are the three U.S. Steel facilities that are responsible for over 
half of all point source PM2.5 emissions in the 
nonattainment area.\36\ Given the proximity of these facilities to the 
Liberty Monitor in the Mon Valley, which has typically been the 
violating monitor in the area for the PM2.5 NAAQS, the 
commenter argues that the PM2.5 plan control strategy does 
not adequately focus on reducing emissions contributions to the Liberty 
Monitor from the three U.S. Steel facilities in the Mon Valley. The 
commenter states that there is no change in the annual PM2.5 
emissions at the Edgar Thomson facility in Braddock (633.215 tpy) or 
the Irvin facility in West Mifflin (71.936 tpy), while the Clairton 
Coke Works will see a small reduction of 34.63 tpy between the 2011 
base year and the 2021 attainment year inventory--a decrease of only 
about six percent over ten years.\37\ The commenter points out that 
most of the emission reductions achieved at the Clairton Coke Works 
stem from two coking quench tower

[[Page 26395]]

replacements (approximately 117.2 tpy)--with little progress in 
reducing emissions (less than one tpy) from coal handling or other coke 
manufacturing operations at that facility. The commenter notes that 
upgrades to Battery C (including tower replacement) resulted in a net 
increase in emission of 82.3 tpy--with the new Tower C for C Battery 
being installed in 2012, however, the emission reductions from the 
shutdown of the old towers it replaced occurred prior to the 2011 base 
year and are therefore not creditable as a control strategy in the 
PM2.5 plan. The control strategy, including reductions at 
the Clairton Coke Works, for the PM2.5 plan period of 2011 
to 2021 results in a reduction of 35.1 tpy.
---------------------------------------------------------------------------

    \36\ See ACHD's September 30, 2019 SIP revision, Appendix D.1, 
pp. 10-11 (Table D-2) (identifying base year emissions of 588.725 
tons pr year (tpy), 633.215 tpy, and 71.936 tpy from three U.S. 
Steel facilities, which comprise more than half the total emissions 
of 2,503 tpy from all point sources). Also, pp. 14-15 (Table D-3) 
(identifying future year emissions of 554.094 tpy, 633.215 tpy, and 
71.936 tpy from the three facilities, which exceed half the total 
emissions of 2,256 tpy from all point sources).
    \37\ See ACHD's September 30, 2019 SIP Revision, Appendix D.1, 
pp. 10, 14. The Clairton Coke Works emissions were 588.7 tpy in the 
2011 base year inventory and 554.1 tpy in the 2021 projected 
inventory.
---------------------------------------------------------------------------

    The commenter suggests that over six years have passed since the 
last significant emissions reduction measures were enacted at the U.S. 
Steel facilities and that additional reductions should be enacted as 
part of the attainment demonstration. The commenter suggests, among 
other things, that Clairton undertake projects to reduce emissions from 
leaking doors, lids, and offtakes from coke oven batteries, pursuant to 
the EPA National Emission Standards for Hazardous Air Pollutants 
(NESHAP) for charging, leaks, and bypass stacks at coke oven 
batteries.\38\
---------------------------------------------------------------------------

    \38\ See 40 CFR part 63, subpart L--National Emission Standards 
for Coke Oven Batteries.
---------------------------------------------------------------------------

    Response 5: As explained in EPA's response to Comment 3, ACHD did 
not ``disregard'' any modeling results. EPA believes Allegheny County 
is justified in conducting a LAA using a Gaussian dispersion model 
(AERMOD) to develop more accurately the Liberty Monitor projected 2021 
PM2.5 design values. Furthermore, Allegheny County has fully 
documented that it has followed EPA's guidance in executing its LAA.
    In a moderate area plan, a state is only obligated to adopt 
measures adequate to demonstrate attainment of the NAAQS. As explained 
in EPA's PM Implementation Rule, if a moderate area's attainment 
demonstration shows attainment by the attainment date ``. . . without 
implementing all reasonably available control measures (i.e., RACM/RACT 
and additional reasonable measures), the state would not be required to 
adopt certain otherwise reasonable measures if the state demonstrates 
that collectively such measures would not enable the area to attain the 
standard at least 1 year earlier (i.e., `advance the attainment date' 
by one year). The EPA has long applied this particular test to satisfy 
the statutory provision related to an area demonstrating attainment `as 
expeditiously as practicable.' The EPA continues to believe that this 
approach provides an appropriate degree of flexibility to a state to 
tailor the control strategy in the Plan to the actual attainment needs 
of a particular PM2.5 nonattainment area.'' \39\
---------------------------------------------------------------------------

    \39\ See 81 FR 58010, 58035 (August 24, 2016).
---------------------------------------------------------------------------

    ACHD's modeling projects attainment by the attainment date. The 
RACM analysis indicated that no measures would advance the attainment 
by 1 year. Therefore, additional controls at Clairton Coke Works or any 
other facility in the Area are not required to demonstrate attainment.
    Comment 6: EPA should require that ACHD better substantiate its 
RACT evaluation for the U.S. Steel facilities in the Allegheny County 
Area, in light of more recent innovations in emission control 
technology. The commenter states that ACHD asserts that there are no 
feasible controls (or combination thereof) in the Area that would 
advance the attainment date by one year or more, and that already 
implemented controls represent reasonably available (or better) control 
technology. The commenter believes that ACHD has not substantiated the 
assertion that further reductions are not reasonably available from the 
three Mon Valley U.S. Steel facilities, which are collectively 
projected to emit 1,294 tpy of PM2.5 in 2021 (588.7 tpy from 
Clairton Coke Works, 633 tpy from Edgar Thomson, and 71.9 tpy from 
Irwin).
    The commenter provides multiple examples of sources at the U.S. 
Steel facilities where emissions could be reduced, for example 
reduction of fugitive emissions through improved coke oven door sealing 
measures at the Clairton Coke Works. The commenter also suggests that 
ACHD should have considered potential RACT controls involving enclosure 
of emission sources, where feasible, to fully or partially capture 
emissions, citing examples of this control in use in Japan.\40\ The 
commenter also cites other additional resources for RACT comparison, 
including European Union Best Available Techniques for the iron and 
steel industry \41\ and the website of the Institute for Industrial 
Productivity, which provides a list of coke manufacturing emission 
control innovations.\42\
---------------------------------------------------------------------------

    \40\ See Clean Air Council Comment letter dated August 13, 2020, 
Attachment 8--Okazaki et al., Program for Sustainable Development at 
Nippon Steel, Nippon Steel Technical Report No. 101 (November 2012), 
at: www.nipponsteel.com/en/tech/report/nsc/pdf/NSTR101-30_tech_review-5-1.pdf.
    \41\ See Clean Air Council comment letter dated August 13, 2020, 
Attachment 10--JRC Reference Report, Best Available Techniques (BAT) 
Reference Document for Iron and Steel Production (2013), at: https://ec.europa.eu/jrc/en/publication/reference-reports/best-available-techniques-bat-reference-documentforiron-and-steel-productionindustrial-emissions. Specifically, sections relating to 
Coke Oven Plants (Chapter 5, pages 205-287), Blast Furnaces (Chapter 
6, pages 289-352), and Basic Oxygen Steelmaking and Casting (Chapter 
7, pages 353-418). Id. Refer also to emerging technologies for Coke 
Ovens (Section 11.3, pages 549-553), Blast Furnaces Section 11.4, 
pages 554), and BOF and Casting (Section 11.5, pages 555-558).
    \42\ See Attachment 11--The Institute for Industrial 
Productivity, Industrial Efficiency Technology Database, http://ietd.iipnetwork.org/content/coke-making (coke making); see also 
Attachment 12--The Institute for Industrial Productivity, Industrial 
Efficiency Technology Database, http://ietd.iipnetwork.org/content/coke-dry-quenching (coke dry quenching).
---------------------------------------------------------------------------

    Response 6: The RACT requirements under subparts 1 and 4 of the CAA 
are focused on measures needed to attain the NAAQS. A state is not 
required to impose all potential emission control measures if existing 
measures are sufficient for the area to attain by the attainment date. 
EPA's PM Implementation Rule and EPA's General Preamble provide that: 
(i) RACT has historically been defined as `the lowest emission limit 
that a source is capable of meeting by the application of control 
technology that is reasonably available considering technological and 
economic feasibility'; (ii) RACT generally applies to stationary 
sources, both stack and fugitive emissions; (iii) major stationary 
sources (i.e., sources with potential to emit 100 tons per year or more 
of direct PM2.5 or any PM2.5 precursor) should be 
the minimum starting point for a state's RACT analysis, but states are 
recommended to evaluate RACT for smaller stationary sources as needed 
for attainment and considering the feasibility of controls; and (iv) it 
is possible that a state could demonstrate that an existing source in 
an area should not be subject to a control technology especially where 
such technology is unreasonable in light of the area's attainment 
needs, or such technology is infeasible. In such a case, it could be 
concluded that no control technology is `reasonably available,' and 
RACT for the source could be considered to be no additional control. 
Thus, the RACT requirement under CAA subpart 4 is primarily focused on 
stationary sources and forms of emissions control that are technology 
based.\43\
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    \43\ See 81 FR 58010, 58034. See also ``General Preamble for the 
Implementation of Title I of the Clean Air Act Amendments of 1990,'' 
57 FR 13498 (April 16, 1992). See also ``State Implementation Plans 
for Serious PM-10 Nonattainment Areas: Addendum to the General 
Preamble for the Implementation of Title I of the Clean Air Act 
(CAA) Amendments,'' 59 FR 41998 (August 16, 1994).

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[[Page 26396]]

    EPA's PM2.5 Implementation Rule requires that all 
moderate area plans contain RACM, which is defined in 40 CFR 51.1000 as 
any technologically and economically feasible measure that can be 
implemented within 4 years of designation of a PM2.5 
nonattainment area and that achieves permanent and enforceable 
reductions in emissions of PM2.5 and/or PM2.5 
precursor emissions. RACM includes RACT. As stated in the preamble to 
the Implementation Rule, EPA recommends that the state should follow a 
process by which it first identifies all sources of emissions of direct 
PM2.5 and PM2.5 precursors in the nonattainment 
area, and all potential control measures to reduce emissions from those 
source categories. The state next determines if any of the identified 
potential control measures are not technologically feasible or 
economically feasible. The Preamble to the Implementation Rule also 
states that ``measures that are not necessary for attainment need not 
be considered as RACM/RACT.'' In the preamble to the PM2.5 
Implementation Rule, EPA notes that this has been ``EPA's longstanding 
interpretation of RACM/RACT in CAA sections 172(c)(1) and 189(a)(1)(C), 
which were enacted as part of the amendments to the Act in 1990. Even 
prior to the 1990 amendments, EPA interpreted the statutory term RACM 
to encompass only those measures `necessary to assure reasonable 
further progress and attainment by the required date.' '' \44\ In the 
1990 amendments to the Act, Congress enacted a ``general savings 
clause,'' which states that ``each regulation, standard, rule, notice, 
order and guidance promulgated or issued by [EPA] under this chapter, 
as in effect [before the 1990 Amendments], shall remain in effect 
according to its terms.'' \45\ Since the passage of the 1990 
amendments, EPA's interpretation of RACM and RACT encompasses only 
those measures necessary to advance attainment has been upheld in 
multiple U.S. Circuit Courts of Appeals. See NRDC v. EPA, 571 F.3d 
1245, 1251-1253 (D.C. Cir. 2009); Sierra Club v. EPA, 314 F.3d 735, 
743- 744 (5th Cir. 2002); Sierra Club v. EPA, 294 F.3d 155, 162 (D.C. 
Cir. 2002). But cf. Sierra Club v. EPA, 793 F.3d 656 (6th Cir. 2015) 
(holding that an area must have subpart 1 RACM/RACT approved into its 
SIP prior to redesignation, regardless of whether the area is attaining 
the NAAQS).
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    \44\ Id, at footnote 71, citing 44 FR 20375 (April 4, 1979); see 
40 CFR 51.1(o) (1972) (defining RACT in similar terms); 42 U.S.C. 
7502(b)(2) (1988) (requiring RACM in the precursor to current CAA 
section 172(c)(1)).
    \45\ See 42 U.S.C. 7415.
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    In Appendix J of the Allegheny County PM2.5 Plan, ACHD 
explains the methodology it used for its RACT analysis. ACHD explains 
that the first step was to identify ``all current major stationary 
point sources'' in the nonattainment area. ACHD included major sources 
for PM2.5, SO2, or NOX. The second 
step was to identify the different processes (or process groups) for 
the applicable major source facilities, and then identify current 
controls in place for the processes. After the sources and processes 
(or process groups) were identified, ACHD identified potential RACT 
alternatives for the processes.
    As stated in Appendix J of the Plan for examination of reasonable 
alternative controls, ACHD used several EPA resources, including the 
RACT/BACT/LAER \46\ Clearinghouse (RBLC),\47\ the Menu of Control 
Measures (MCM) for NAAQS Implementation,\48\ and the Control Cost 
Manual.\49\ ACHD also examined determinations from the RBLC over the 
past 10 years (from January 1, 2009 through July 1, 2019) for 
comparison to existing controls. ACHD based its economic analysis of 
alternatives on estimates of total costs (capital costs plus operating/
indirect costs) and/or cost effectiveness (ratio of cost per ton of 
pollutant). Reasonable controls considered by ACHD included operation 
and work practices and/or permitted limits for some processes. ACHD 
concluded in its RACM/RACT analysis that other reasonable control 
measures it considered but decided not to implement would not advance 
the attainment date by one year. EPA believes that ACHD's use of the 
RBLC, the MCM, and the Control Cost Manual comprises a reasonably 
thorough approach for evaluating potential RACT control options for 
sources in this area. Furthermore, the modeling demonstration in ACHD's 
Plan shows attainment by the target attainment date with the control 
measures set forth in the control strategy. EPA agrees with ACHD's 
conclusion that those measures that were identified and evaluated under 
this analysis but that were not adopted and implemented in the area 
would collectively not advance the attainment date by more than a year. 
Therefore, EPA agrees that ACHD did not need to adopt and impose 
additional controls in the area to meet the RACT requirement.
---------------------------------------------------------------------------

    \46\ BACT = Best Available Control Technology; LAER = Lowest 
Achievable Emission Rate.
    \47\ See EPA's RACT/BACT/LAER Clearinghouse web page, at https://cfpub.epa.gov/RBLC/index.cfm?action=Home.Home⟨=en.
    \48\ See EPA's Menu of Control Measures for NAAQS Implementation 
web page, at: https://www.epa.gov/air-quality-implementation-plans/menu-control-measures-naaqs-implementation.
    \49\ EPA Air Pollution Control Cost Manual, 6th Edition: https://www.epa.gov/economic-and-cost-analysis-air-pollution-regulations/cost-analysis-modelstools-air-pollution.
---------------------------------------------------------------------------

    Comment 7: The commenter supports EPA's determination that two 
measures submitted by ACHD as contingency measures do not meet 
statutory requirements for such measures. However, the commenter 
objects to EPA's proposal to approve these two measures instead as 
``additional control measures.'' \50\ The two measures at issue are: 
(1) Newly installed air curtains and/or covers on the Battery B Shed at 
the US Steel Clairton Coke Works; and (2) a new combustion (underfire) 
stack for Battery 15 at the US Steel Clairton Coke Works. In 
particular, the commenter objects to the approval of the taller 
combustion stack not only as a contingency measure, but as a control 
measure appropriate for inclusion in the SIP for the Allegheny 
PM2.5 Plan.
---------------------------------------------------------------------------

    \50\ See EPA's Proposed Rulemaking, at 85 FR 35871 (col. 3), 
June 12, 2020.
---------------------------------------------------------------------------

    The commenter argues that the higher stack is not a ``control 
measure'' at all because control measures must reduce emissions, rather 
than merely disperse the emissions. Commenter cites 40 CFR 
51.1014(b)(1) (``The contingency measures shall consist of control 
measures that are not otherwise included in the control strategy or 
that achieve emissions reductions not otherwise relied upon in the 
control strategy for the area . . . .'' (emphasis added by commenter)) 
and 40 CFR 51.100(n) (``Control strategy means a combination of 
measures designated to achieve the aggregate reduction of emissions 
necessary for attainment and maintenance of national standards . . . 
.'') for the proposition that a higher stack which merely disperses the 
emissions.
    Response 7: EPA has reevaluated its proposal to approve the two 
measures at the US Steel Clairton Plant coke works as ``additional 
measures'' in light of the commenter's objections, and following 
further review, it is clear that these measures are discussed in the 
Plan solely in the context of the contingency measure element of the 
Plan to address CAA section 172(c)(9). As such, EPA's proposed approval 
of these two proposed contingency measures as ``additional measures'' 
went beyond ACHD's proposal and therefore should not have been 
considered by EPA as anything other than proposed contingency measures.

[[Page 26397]]

    Additional review of ACHD's SIP revision shows that the attainment 
plan does not rely on any potential emission reductions from these two 
projects in order to show attainment, and modeling supporting the Plan 
used neither the future increased stack height of the underfire air 
stack of battery 15 nor the cover/air curtains on the south side of 
Battery B shed in the analysis, as mention of these two measures was 
limited to the contingency measure section of the Plan. Thus, EPA's 
decision to not approve these as ``additional measures'' has no impact 
on the modeled attainment demonstrations showing that the other 
measures in the control strategy will result in attainment by the 
attainment date.
    The Plan does not rely on the emission reductions from the two 
measures as part of the control strategy in the modeled attainment 
demonstration for the Allegheny PM2.5 nonattainment area, 
but rather as early implemented contingency measures to be implemented 
under a settlement order between US Steel and ACHD.\51\ EPA reiterates 
our rejection of these two measures as contingency measures as they are 
both required by a settlement order and are being implemented 
regardless of whether triggered as a contingency measure.
---------------------------------------------------------------------------

    \51\ Settlement Agreement and Order #190604, between U.S. Steel 
and ACHD, June 27, 2019.
---------------------------------------------------------------------------

    Comment 8: The commenter also asserts that ACHD's future 
contingency measures must obtain 34 tons per year of emissions 
reductions, which is the amount representing one year of areawide 
reductions necessary under the reasonable further progress (RFP) 
element of the Plan, in order to comply with long-standing policy of 
the EPA.\52\ The commenter believes that ACHD's alternative proposal to 
adopt contingency measure obtaining reductions in emissions near the 
Liberty Monitor of only 9.4 tons per year is not in accordance with EPA 
guidance for contingency measures and that ACHD has not sufficiently 
``shown its work'' to justify why contingency measures representing 
less than one year of RFP reduction for the Area is needed. Commenter 
asserts that ACHD's stated rationale that additional modeling shows 
that the proposed lower level (9.4 tpy) of contingency measures would 
lead to a reduction in absolute annual modeled impacts of 0.10 [mu]g/
m\3\ at the Liberty Monitor--a level sufficient to model attainment at 
that monitor in 2022 (if all other emissions are held constant at 2021 
levels)--is an inadequate justification for this departure from EPA's 
guidance.
---------------------------------------------------------------------------

    \52\ 81 FR 58010 and 58068, column 2. See also General Preamble 
for the Implementation of Title I of the Clean Air Act Amendments of 
1990 (August 16, 1992), 57 FR 13496, 13543 (column 3) through 13544 
(column 1).
---------------------------------------------------------------------------

    Response 8: EPA agrees with the commenter that its longstanding 
guidance to states with respect to contingency measures is that such 
measures should result in at least one year's worth of RFP as 
determined in the nonattainment plan for the area at issue. EPA also 
agrees that the determination of what is necessary for RFP should be 
based upon the overall emission reductions necessary for attainment of 
the relevant NAAQS in the area, not based on the premise that some 
lesser amount of emissions reduction from an individual source in a 
nonattainment area is sufficient for this purpose. This is especially 
the case for attainment of the PM2.5 or Ozone NAAQS, where 
violations of the NAAQS in a given area are commonly the result of 
aggregate emissions from numerous sources located across the designated 
nonattainment area. Similarly, EPA agrees that for purposes of 
supporting a conditional approval of an element of a nonattainment plan 
under section 110(k)(4), the commitment submitted by a state should be 
to adopt and submit additional specific measures that would correctly 
address the deficiency in the original SIP submission that is the 
reason for the conditional approval. In this instance, the conditional 
approval pertains to ACHD's commitment to submit adequate contingency 
measures, consistent with the requirements of section 172(c)(9) and 
with EPA guidance for those requirements.
    EPA disagrees that the ACHD commitment letter is insufficient to 
support conditional approval of the contingency measures element of the 
Allegheny County PM2.5 Plan. In its April 7, 2020 commitment 
letter, ACHD committed to adopt specific contingency measures that 
would achieve 34 tons per year for the Area, or 9.4 tons per year of 
reductions nearby the Liberty Monitor. The Agency's June 12, 2020 
proposed approval of ACHD's SIP revision proposed conditional approval 
of the contingency measure element of the plan on the basis that ACHD 
would adopt additional contingency measures necessary to satisfy CAA 
requirements applicable to contingency measures. EPA's longstanding 
guidance on this is that contingency measures should achieve reductions 
in pollutants from sources that constitute one year's worth of RFP in 
the area, unless presented with facts and circumstances that justify a 
different amount.\53\
---------------------------------------------------------------------------

    \53\ See, for example ``State Implementation Plans; General 
Preamble for the Implementation of Title I of the Clean Air Act 
Amendments of 1990,'' 57 FR 13498 at 13543 and 13544 (April 16, 
1992) and ``Fine Particulate Matter National Ambient Air Quality 
Standards; State Implementation Plan Requirements; Final Rule,'' 81 
FR 58010 at 58067 (August 24, 2016).
---------------------------------------------------------------------------

    EPA is finalizing the conditional approval based on ACHD's 
commitment to adopt and submit contingency measures meeting statutory 
requirements and consistent with EPA guidance. In this action, EPA is 
not determining definitively whether such measures must achieve 34 tpy 
or any other specific amount of emissions. EPA is finalizing this 
conditional approval based on its expectation that ACHD's new 
contingency measures will obtain reductions at least equal to one 
year's worth of RFP, i.e., 34 tpy, but notes that it is neither 
accepting nor rejecting at this time the possibility that the state 
could submit contingency measures obtaining some other amount of 
reductions and adequately justify this other amount. When ACHD adopts 
and submits the specific control measures to remedy the current 
deficiency with respect to the contingency measure element of the plan, 
EPA will review and take rulemaking action to assess the necessary 
levels of emission reductions for ACHD's replacement contingency 
measures.
    Comment 9: The commenter cites federal court decisions for the 
proposition that EPA lacks the authority to conditionally approve a 
PM2.5 Plan that entirely lacks contingency measures, see 
Sierra Club v. EPA, 294 F.3d 155, 164 (D.C. Cir. 2002), and that EPA 
cannot grant conditional approval based on a state commitment letter 
that does not provide specific enforceable limits, see Sierra Club v. 
EPA, 356 F.3d 296 (D.C. Cir. 2004). Based on these cases, the commenter 
then contends that ACHD cannot simply identify specific contingency 
measures without establishing that they would be approvable if 
implemented. The commenter cites the second Sierra Club case for the 
proposition that the commitment must be ``something more than a mere 
promise to take appropriate but unidentified measures in the future,'' 
Sierra Club v. EPA, 356 F.3d 296, 303, and that this ``requires that 
the States complete the analyses necessary to identify appropriate 
measures before, rather than after, conditional approval is granted.'' 
\54\ The commenter argues that because the Department does not quantify 
any putative emissions

[[Page 26398]]

reductions from the ``hypothetical'' contingency measures set forth in 
its commitment letter, it is impossible to identify appropriate 
measures before conditional approval is granted, as the D.C. Circuit 
required.\55\ Therefore, the commenter states that EPA may not grant 
the requested conditional approval.
---------------------------------------------------------------------------

    \54\ Id.
    \55\ See Commitment Letter of the Allegheny County Health 
Department, dated April 7, 2020, available in the docket for this 
action, Document ID EPA-R03-OAR-2020-0157-0071.
---------------------------------------------------------------------------

    Response 9: EPA agrees that in order to support a conditional 
approval under section 110(k)(4), a state must provide a written 
commitment to take specific actions to address the identified 
deficiencies in the initial SIP submission that resulted in the need 
for a conditional approval. As explained in the proposal document, and 
as evidenced by the commitment letter in the docket supporting this 
final action, ACHD has made an adequate commitment to support 
conditional approval of the contingency measures element of the 
Allegheny County PM2.5 Plan. Thus, EPA does not agree that 
the Sierra Club cases cited by the commenter preclude this conditional 
approval.
    The factual circumstances in the 2004 Sierra Club case are 
different and therefore distinguishable from the facts of ACHD's 
PM2.5 Plan in several respects. First, the SIP submission at 
issue in the Sierra Club case initially included nothing addressing 
three required elements of that nonattainment plan: Contingency 
measures, RACM analyses and RACM, and a post-1999 Rate of Progress 
(ROP) plan. Sierra Club at 301. The Sierra Club court concluded that it 
was inappropriate for EPA to exercise its conditional approval 
authority under section 110(k)(4) in a situation in which the states 
had submitted nothing to address these requirements. Here, ACHD did 
address the contingency measures requirement as an element in its 
initial nonattainment plan SIP submission (i.e., installation of a new 
underfire stack on Battery 15 and installation of a cover or air 
curtains on south side of B battery shed). Although EPA found that 
these measures did not meet the statutory requirements for contingency 
measures because a consent order required that these actions take place 
regardless of whether the area failed to attain or failed to meet its 
ROP plan, ACHD did make a good faith effort to submit contingency 
measures as part of the Allegheny County PM2.5 Plan, unlike 
in the 2004 Sierra Club case cited.
    Second, the commitment letters subsequently submitted by the states 
involved in the 2004 Sierra Club case were vague and failed to list any 
specific, enforceable measures that the state would adopt as 
contingency measures. Citing one state's commitment letter, the Court 
noted that the commitment letters only promised to submit ``adopted 
contingency measures to be implemented if the DC Area does not attain 
the one-hour ozone NAAQS by November 15, 2005.'' Id. at 302. Here, ACHD 
has identified seven specific contingency measures it will adopt to 
obtain an additional 34 tons per year of direct PM2.5 
emission reductions (or of PM2.5 precursors) or 9.4 tpy in 
the vicinity of the Liberty Monitor. ACHD has committed to adopt 
contingency measures that will meet EPA's requirements for contingency 
measures (i.e., adopted measures that equate to one year's worth of RFP 
reductions, along with the requisite description of triggering 
mechanisms for these measures) and will submit the contingency measures 
to EPA within one year from EPA's final conditional approval. EPA notes 
that it is basing this approval on the ACHD commitment to obtain the 34 
tpy that would constitute the one year's worth of RFP that is 
consistent with EPA guidance for the contingency measures requirement, 
not the 9.4 tpy alternative posited by ACHD. The Sierra Club court 
found that ``[t]he statute requires that the States commit to adopt 
specific enforceable measures,'' Sierra Club at 302, but that EPA was 
accepting as sufficient a commitment to adopt what it conceded are 
unspecified measures.\56\ The measures identified by ACHD are much more 
specific than those identified in that case, and are made more specific 
by the promise to adopt some combination of these measures to achieve 
the necessary amount of reductions needed in the area.
---------------------------------------------------------------------------

    \56\ Id.
---------------------------------------------------------------------------

    Third, the Sierra Club decision language cited by the commenter as 
requiring state analyses prior to EPA granting conditional approval can 
also be distinguished from the circumstances in this SIP submission. 
The 2004 Sierra Club court was expounding upon its earlier decision in 
the Natural Resources Defense Council (NRDC) v. EPA, 22 F. 3d 1125 
(D.C. Cir. 1994). In the NRDC case, the Court was reviewing EPA's 
interpretation of newly created conditional approval language in 
section 110(k)(4) that Congress adopted in the 1990 CAA amendments. 
Through guidance and rulemaking, EPA had interpreted section 110(k)(4) 
as allowing conditional approval of a ``committal SIP'' containing no 
substantive provisions, so long as the state submitted it within one of 
the deadlines and the state promised to adopt specific enforceable 
measures within a year and a schedule of interim milestones in the 
future adoption process. The NRDC court concluded that ``the 
conditional approval mechanism was intended to provide the EPA with an 
alternative to disapproving substantive, but not entirely satisfactory, 
SIPs submitted by the statutory deadlines and not, as the EPA has used 
it, a means of circumventing those deadlines.'' NRDC at 1134-1135. The 
court then held that ``section 110(k)(4) does not authorize the EPA to 
use committal SIPs to postpone SIP deadlines.'' Id. at 1135. That 
situation is not present here. Although ACHD submitted its 
nonattainment plan SIP submission late, ACHD did submit a complete 
nonattainment plan containing all the required elements--including the 
contingency measures element. Upon further evaluation of the SIP 
submission, EPA determined that the contingency measures were not 
approvable, and therefore based on ACHD's commitment has elected to 
exercise its authority to provide ACHD up to one year to remedy the 
deficiency, in accordance with section 110(k)(4). Thus, EPA is not 
circumventing the original SIP submission deadline by granting 
conditional approval in this matter, but merely allowing ACHD to revise 
these ``substantive, but not entirely satisfactory, elements of the 
SIP.'' See Id. at 1134-1135. EPA is thus using its discretionary 
authority under section 110(k)(4) in an appropriate way.
    Regarding the Clean Air Council's claim that ACHD had to do further 
analyses of the contingency measures before EPA could grant conditional 
approval, EPA has concluded that ACHD has done such an analysis by 
identifying readily available emission control contingency measures 
which, if triggered, will achieve the necessary emission reductions in 
the nonattainment area. The submitted emission reduction numbers come 
from the analysis contained in the attainment demonstration and all the 
elements that make up the demonstration, such as emission inventories 
and modeling. The 34.1 tpy number is one year of emission reductions 
derived from ACHD's Reasonable Further Progress (RFP) plan, which was 
informed by the modeling. Having completed this analysis, ACHD then had 
to analyze where it could obtain emission reductions equal to this 
amount, and that analysis resulted in

[[Page 26399]]

the list of seven specific contingency measures set forth in the ACHD 
commitment letter, which ACHD will evaluate, adopt, and then submit to 
EPA for approval as contingency measures to meet the requirement of the 
conditional approval.
    The commenter also claims that this language from the Sierra Club 
decision requires, under these circumstances, that the SIP submission 
include analyses identifying both the specific contingency measures and 
the specific amount of emission reduction obtained from each measure 
before EPA can grant conditional approval. EPA disagrees with this 
reading of the court's ruling. The 2004 Sierra Club court did not 
specifically identify what ``analyses'' must be done by the state as 
part of the conditional approval. In the Sierra Club case, the three 
missing statutory elements of the attainment plan were contingency 
measures, RACM analyses, and Rate of Progress plans. The court did not 
address the issue of what specific analyses the state needed to perform 
as part of the submittal of the contingency measures, because there 
were no contingency measures identified or included in the SIP. In the 
absence of specific contingency measures in that SIP, the court would 
only be hypothesizing about what analysis needed to accompany specific 
contingency measures.
    The Clean Air Council's argument that ACHD must quantify the 
specific amount of emission reductions available from each specified 
contingency measure (prior to EPA granting conditional approval) is 
also not supported by the Sierra Club case. In the 2004 Sierra Club 
matter, the states did not submit anything to meet the three required 
elements of the attainment plan, including the contingency measures, so 
the court had no reason to opine on what specific analysis should 
accompany three entirely missing elements of the attainment plan. EPA 
does not agree that the decision requires ACHD to identify specific 
amounts of emission reductions from these specific proposed measures 
prior to conditional approval, as EPA expects that the state will 
provide additional information supporting the calculation of estimated 
emission reductions for all adopted contingency measures as part of a 
future SIP revision to address EPA's final conditional approval of the 
contingency measure element of the plan. ACHD has committed to adopt 
sufficient measures from the identified list of potential control 
measures sufficient to achieve the necessary one year's worth of RFP 
for this area.
    EPA does not agree that ACHD must precisely calculate how much 
emission reduction will be achieved by the individual measures until 
ACHD actually submits the adopted measures to EPA for evaluation and 
approval into the SIP, as appropriate at that time. For these reasons, 
EPA does not agree with the commenter's claim that case law prohibits 
EPA from granting conditional approval for the contingency measures 
under the circumstances of this SIP submission, and also disagrees that 
ACHD's commitment to adopt contingency measures must, at this time, 
contain specific amounts of emissions attributable to individual 
measures.

IV. Final Action

A. Approval of the Attainment Plan and Related Elements

    Under CAA section 110(k)(3), EPA is approving Pennsylvania's SIP 
revisions to address the CAA's Moderate area planning requirements for 
the 2012 PM2.5 NAAQS in the Allegheny County nonattainment 
area--with the exception of the contingency measures element of the 
plan, which EPA is conditionally approving. Specifically, EPA is 
proposing to approve the following elements of the Allegheny County 
PM2.5 plan: The 2011 base year emissions inventory as 
meeting the requirements of CAA section 172(c)(3); the RACM/RACT 
demonstration as meeting the requirements of CAA sections 172(c)(1) and 
189(a)(1)(C); the attainment demonstration as meeting the requirements 
of CAA sections 172(c)(1) and 189(a)(1)(B); the RFP demonstration as 
meeting the requirements of CAA section 172(c)(2); the QM demonstration 
as meeting the requirements of CAA section 189(c); and the MVEB for 
2021, which meets the transportation conformity related requirements of 
CAA section 176(c) and 40 CFR part 93, subpart A.
    EPA is approving the 2021 MVEB element of the Plan in this final 
action. EPA has determined that ACHD has remedied the deficiency with 
the 2021 MVEB, for which EPA proposed conditional approval in our June 
12, 2020 proposed action. Pennsylvania, in an April 20, 2020 letter to 
EPA, committed to finalize adoption of its intended 2021 MVEB, which 
had not yet been finally adopted or undergone public participation at 
the local level. EPA's proposed to conditionally approve the MVEB 
element of the Allegheny County PM2.5 Plan, contingent upon 
final adoption by ACHD of the intended 2021 MVEB. On October 2, 2020, 
PADEP submitted a SIP revision (on behalf of ACHD) that contained the 
final 2021 MVEB for the Allegheny County Area, remedying EPA's June 12, 
2020 proposed condition upon approval of the MVEB element of the Plan. 
This final 2021 MVEB was unchanged from the intended MVEB upon which 
EPA proposed conditional approval in our June 12, 2020 proposed 
action.\57\ EPA has determined that this final 2021 MVEB remedies the 
deficiency underlying our conditional approval of the MVEB element of 
the plan, as the final MVEB was adopted (as proposed), satisfies public 
participation requirements of EPA's conformity rule under 40 CFR 
93.118(e), and has been formally submitted to EPA as a supplemental SIP 
revision. The final 2021 MVEB for the 2012 PM2.5 NAAQS, 
including direct PM2.5 and the precursor NOX, is 
listed in Table 1,
---------------------------------------------------------------------------

    \57\ See 85 FR 35872, 35873 (June 12, 2020).

                              Table 1--Allegheny County, PA 2012 PM2.5 NAAQS Attainment Year MVEB for Direct PM2.5 and NOX
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                      Direct PM2.5 on-road emissions (tons per year)
        Motor Vehicle Emissions Budget year                                                                  NOX on-road emissions (tons per year)
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                         2021                                                 266                                              5,708
--------------------------------------------------------------------------------------------------------------------------------------------------------

[[Page 26400]]

B. Conditional Approval of the Contingency Measures Portion of the 
Attainment Plan

    EPA is conditionally approving the contingency measures element of 
the Allegheny County Plan. In accordance with section 172(c)(9) of the 
CAA and EPA's PM2.5 Implementation Rule, the attainment 
demonstration for a moderate PM2.5 nonattainment area must 
include contingency measures.\58\ Contingency measures are additional 
control measures to be implemented in the event that the area fails to 
meet RFP requirements, fails to submit or meet quantitative milestones 
(QM), or EPA determines that the area fails to attain by the attainment 
date.
---------------------------------------------------------------------------

    \58\ See 40 CFR 51.1014 and 81 FR 58010, p. 58066 (August 24, 
2016).
---------------------------------------------------------------------------

    In order for contingency measures to be approved as part of a 
state's PM2.5 moderate area attainment plan, the measures 
must meet the following requirements set forth in the PM2.5 
Implementation Rule and 40 CFR 51.1014: (1) The contingency measures 
must be fully adopted rules or control measures that are ready to be 
implemented quickly upon a determination by the EPA Administrator of 
the nonattainment area's failure to meet RFP, failure to meet any QM, 
failure to submit a QM report or failure to attain the standard by the 
attainment date; (2) the plan must contain trigger mechanisms for the 
contingency measures, specify a schedule for implementation, and 
indicate that the measures will be implemented with minimal further 
action by the state or by EPA; (3) the contingency measures shall 
consist of control measures not otherwise included in the control 
strategy for the area; and (4) the contingency measures should provide 
for emissions reductions approximately equivalent to one year's worth 
of reductions needed for RFP. PADEP submitted a letter to EPA dated 
April 20, 2020 conveying ACHD's commitment to adopt specific 
contingency measures, from a list specified in that letter, that will 
provide for a reduction of one year's worth of reasonable further 
progress towards attainment, or equivalent (up to 34 tons per year of 
direct PM2.5 emissions). Further detail on ACHD's commitment 
and a description of the specific measures is detailed in EPA's June 
12, 2020 proposed rulemaking for this action.
    After ACHD adopts contingency measures, in compliance with related 
requirements under CAA section 172(c)(9) and the PM2.5 
Implementation Rule (specifically the requirements of 40 CFR 51.1003 
and 40 CFR 51.1014), PADEP will submit a SIP revision containing the 
adopted contingency measures, along with a description of the trigger 
mechanisms and schedules for implementation of the contingency 
measures. ACHD and PADEP have committed to submit the contingency 
measures SIP revision to EPA within one year after EPA's conditional 
approval.
    If EPA makes a determination that Pennsylvania has satisfied the 
approval condition, EPA shall take action to remove the condition on 
its approval of the contingency measure element of the Allegheny County 
PM2.5 Plan, converting our action to full approval. Should 
Pennsylvania fail to remedy the condition within the one-year deadline 
for doing so, this conditional approval shall automatically convert to 
a disapproval and EPA will issue a finding of disapproval. A finding of 
disapproval would start an 18-month clock to apply sanctions under CAA 
section 179(b) and a two-year clock for a Federal implementation plan 
under CAA section 110(c)(1).

V. Statutory and Executive Order Reviews

A. General Requirements

    Under the CAA, the Administrator is required to approve a SIP 
submission that complies with the provisions of the CAA and applicable 
Federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in 
reviewing SIP submissions, EPA's role is to approve state choices, 
provided that they meet the criteria of the CAA. Accordingly, this 
action merely approves state law as meeting Federal requirements and 
does not impose additional requirements beyond those imposed by state 
law. For that reason, this action:
     Is not a ``significant regulatory action'' subject to 
review by the Office of Management and Budget under Executive Orders 
12866 (58 FR 51735, October 4, 1993) and 13563 (76 FR 3821, January 21, 
2011);
     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 rule 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.

B. Submission to Congress and the Comptroller General

    The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the 
Small Business Regulatory Enforcement Fairness Act of 1996, generally 
provides that before a rule may take effect, the agency promulgating 
the rule must submit a rule report, which includes a copy of the rule, 
to each House of the Congress and to the Comptroller General of the 
United States. EPA will submit a report containing this action and 
other required information to the U.S. Senate, the U.S. House of 
Representatives, and the Comptroller General of the United States prior 
to publication of the rule in the Federal Register. A major rule cannot 
take effect until 60 days after it is published in the Federal 
Register. This action is not a ``major rule'' as defined by 5 U.S.C. 
804(2).

C. Petitions for Judicial Review

    Under section 307(b)(1) of the CAA, petitions for judicial review 
of this action must be filed in the United States Court of Appeals for 
the appropriate circuit by July 13, 2021. Filing a petition for 
reconsideration by the Administrator of this final rule does not affect 
the finality of this action for the purposes of judicial review nor 
does it extend the time within which a petition for judicial review may 
be filed, and shall not

[[Page 26401]]

postpone the effectiveness of such rule or action. This action to 
approve SIP revisions consisting of the Allegheny County 
PM2.5 Plan may not be challenged later in proceedings to 
enforce its requirements. (See section 307(b)(2)).

List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Incorporation by 
reference, Intergovernmental relations, Nitrogen dioxide, Particulate 
matter, Reporting and recordkeeping requirements, Sulfur oxides, 
Volatile organic compounds.

    Dated: April 30, 2021.
Diana Esher,
Acting Regional Administrator, Region III.

    For the reasons stated in the preamble, the EPA amends 40 CFR part 
52 as follows:

PART 52--APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS

0
1. The authority citation for part 52 continues to read as follows:

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

Subpart NN--Pennsylvania

0
2. In Sec.  52.2020, the table in paragraph (e)(1) is amended by adding 
the entry ``2012 PM2.5 NAAQS Attainment Demonstration 
(including 2011 Base Year Emissions Inventory, Particulate Matter 
Precursor Contribution Demonstration, Reasonable Further Progress 
Demonstration, Demonstration of Interim Quantitative Milestones to 
Ensure Timely Attainment. and Motor Vehicle Emission Budgets for 2021) 
(excluding Section 8, Contingency Measures)'' at the end of the table 
to read as follows:

Sec.  52.2020   Identification of plan.

* * * * *
    (e) * * *
    (1) * * *

----------------------------------------------------------------------------------------------------------------
                                                                 State
   Name of non-regulatory SIP     Applicable geographic area   submittal    EPA approval date      Additional
            revision                                              date                            explanation
----------------------------------------------------------------------------------------------------------------
 
                                                  * * * * * * *
2012 PM2.5 NAAQS Attainment      Allegheny County...........     09/30/19  5/14/21, [INSERT    Contingency
 Demonstration (including 2011                                   10/02/20   FEDERAL REGISTER    Measures
 Base Year Emissions Inventory,                                             CITATION].          (Section 9)
 Particulate Matter Precursor                                                                   portion of the
 Contribution Demonstration,                                                                    plan is
 Reasonable Further Progress                                                                    Conditionally
 Demonstration, Demonstration                                                                   Approved, until
 of Interim Quantitative                                                                        5/16/22.
 Milestones to Ensure Timely                                                                   See 40 CFR
 Attainment. and Motor Vehicle                                                                  52.2023(n).
 Emission Budgets for 2021)
 (excluding Section 8,
 Contingency Measures).
 
                                                  * * * * * * *
----------------------------------------------------------------------------------------------------------------

* * * * *

0
3. Section 52.2023 is amended by adding paragraph (n) to read as 
follows:

Sec.  52.2023   Approval status.

* * * * *
    (n) EPA conditionally approves the Contingency Measures element 
(Section 8) of the Attainment Plan (dated September 12, 2019) for the 
Allegheny County Area for the 2012 PM2.5 NAAQS, as submitted 
to EPA as a SIP revision by Pennsylvania on September 30, 2019. 
Pennsylvania shall submit a SIP revision within one year of EPA's final 
conditional approval to remedy this condition, which satisfies all 
related requirements for contingency measures under CAA section 
172(c)(9) and the PM2.5 Implementation Rule (specifically, 
40 CFR 51.1003 and 40 CFR 51.1014). Pursuant to CAA section 110(k)(4), 
this conditional approval is based upon April 20, 2020 and April 7, 
2020 letters from Pennsylvania and Allegheny County committing to 
submit a SIP to EPA to remedy the deficiencies of this conditional 
approval within 12 months of EPA's conditional approval action.

[FR Doc. 2021-09565 Filed 5-13-21; 8:45 am]
BILLING CODE 6560-50-P