Document ID: EPA-R03-OAR-2020-0157-0001
Agency: epa
Document Type: Proposed 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: 2020-06-12T04:00Z

[Federal Register Volume 85, Number 114 (Friday, June 12, 2020)]
[Proposed Rules]
[Pages 35852-35874]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-12499]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R03-OAR-2020-0157; FRL-10010-42-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: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to 
approve 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 (``Allegheny County 
area''). The SIP revision contains the ``Attainment Demonstration for 
the Allegheny County, PA PM2.5 Nonattainment Area, 2012 
NAAQS,'' submitted on September 30, 2019 (also referred to as ``the 
Allegheny County PM2.5 Plan'' or simply ``the plan''). EPA 
is proposing 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) demonstration, the attainment demonstration, the air 
quality modeling demonstration supporting attainment by the attainment 
deadline, the reasonable further progress (RFP) demonstration, and the 
a demonstration of interim quantitative milestones to ensure timely 
attainment. EPA is proposing to conditionally approve the following 
elements of this Allegheny County PM2.5 Plan SIP revision: 
The contingency measures and the motor vehicle emission budget (MVEB) 
elements of the plan. PADEP commits, on behalf of ACHD, to submit a 
supplemental SIP revision to remedy those portions of the plan for 
which EPA is proposing conditional approval within twelve months of 
EPA's final conditional approval action. This action is being taken 
under the CAA.

DATES: Written comments must be received on or before July 13, 2020.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R03-
OAR-2020-0157 at https://www.regulations.gov, or via email to 
spielberger.susan@epa.gov. For comments submitted at Regulations.gov, 
follow the online instructions for submitting comments. Once submitted, 
comments cannot be edited or removed from Regulations.gov. For either 
manner of submission, EPA may publish any comment received to its 
public docket. Do not submit electronically any information you 
consider to be confidential business information (CBI) or other 
information whose disclosure is restricted by statute. Multimedia 
submissions (audio, video, etc.) must be accompanied by a written 
comment.

[[Page 35853]]

The written comment is considered the official comment and should 
include discussion of all points you wish to make. EPA will generally 
not consider comments or comment contents located outside of the 
primary submission (i.e. on the web, cloud, or other file sharing 
system). For additional submission methods, please contact the person 
identified in the For Further Information Contact section. For the full 
EPA public comment policy, information about CBI or multimedia 
submissions, and general guidance on making effective comments, please 
visit https://www.epa.gov/dockets/commenting-epa-dockets.

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. Clean Air Act Plan Requirements for Areas Designated Moderate 
Nonattainment for the PM2.5 NAAQS
III. Review of the Allegheny County PM2.5 Plan
    A. Emissions Inventories for the Base Year and Attainment Year
    1. Requirements for Emissions Inventories
    2. Emissions Inventories in the Allegheny County 
PM2.5 Plan
    3. EPA's Evaluation and Proposed Action on the Emission 
Inventories
    B. Particulate Matter Precursor Demonstration
    1. PM2.5 Precursor Requirements
    2. Precursor Demonstration in the Allegheny County 
PM2.5 Plan
    3. EPA's Evaluation and Proposed Action on the Precursor 
Demonstration
    C. Reasonably Available Control Measures (RACM)/Reasonably 
Available Control Technology (RACT)
    1. Requirements for RACM/RACT
    2. RACM Analysis in the Allegheny County PM2.5 Plan
    a. RACM Measures Evaluation
    3. RACT Analysis in the Allegheny County PM2.5 Plan
    a. RACT Measures Evaluation
    4. EPA's Evaluation and Proposed Action on RACM and RACT
    D. Air Quality Modeling
    1. Requirements for Air Quality Modeling
    2. Air Quality Modeling in the Allegheny County PM2.5 
Plan
    3. EPA's Evaluation and Proposed Action on Modeling
    E. Attainment Demonstration
    1. Requirements for an Attainment Demonstration
    2. Attainment Demonstration in the Allegheny County 
PM2.5 Plan
    3. EPA's Evaluation of ACHD's PM2.5 Attainment 
Demonstration
    4. EPA's Proposed Action on the PM2.5 Attainment 
Demonstration
    F. Reasonable Further Progress (RFP)
    1. Requirements for Ensuring Reasonable Further Progress
    2. RFP Demonstration in the Allegheny County PM2.5 
Plan
    3. EPA's Evaluation of and Proposed Action on RFP
    G. Quantitative Milestone (QM) Demonstration
    1. Requirements for a QM Demonstration
    2. QM Demonstration in the Allegheny County PM2.5 
Plan and 2019 QM Report
    a. Allegheny County Area QM Demonstration
    b. Allegheny County PM2.5 Area 2019 QM Report
    3. EPA's Evaluation and Proposed Action on the QM Demonstration
    H. Contingency Measures
    1. Requirements for Contingency Measures
    2. Contingency Measures in the Allegheny County PM2.5 
Plan
    3. EPA's Evaluation and Proposed Action on Contingency Measures
    I. Transportation Conformity and MVEBs
    1. Requirements for Motor Vehicle Emission Budgets
    2. Motor Vehicle Emission Budgets in the Allegheny County 
PM2.5 Attainment Plan
    3. EPA's Evaluation and Proposed Action on the Intended MVEB
IV. Summary of Proposed Action and Request for Public Comment
V. Statutory and Executive Order Reviews

I. Background

    Under section 109 of the CAA, EPA has established NAAQS for certain 
pervasive air pollutants (referred to as ``criteria pollutants'') and 
conducts periodic reviews of the NAAQS to determine whether they should 
be revised or whether new NAAQS should be established. EPA sets the 
NAAQS for criteria pollutants at levels required to protect public 
health and welfare. ``Primary'' NAAQS are those determined by EPA as 
requisite to protect human health, while ``secondary'' NAAQS are those 
determined by EPA as requisite to protect the public welfare from any 
known or anticipated adverse effects of the NAAQS pollutant.\1\ 
Particulate matter is one of the criteria pollutants for which EPA has 
established health-based standards. The CAA requires states to submit 
regulations that control particulate matter emissions.
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    \1\ See CAA section 109(b).
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    Particulate matter includes particles with diameters that are 
generally 2.5 microns or smaller (referred to as PM2.5) and 
particles with diameters that are generally 10 microns or smaller (or 
PM10). Particulate matter has deleterious effects on the 
environment, both to human health and to plants and wildlife. The 
effects on human health include premature mortality, aggravation of 
respiratory and cardiovascular disease, and decreased lung function. 
Some individuals, such as older adults and people with lung or heart 
disease, are particularly sensitive to PM2.5 exposure. 
Impacts on the environment include impairment of visibility, as well as 
damage to vegetation and ecosystems.\2\ Sources can directly emit 
PM2.5 into the atmosphere, in the form of a solid or a 
liquid particle (i.e., ``direct PM2.5'' or ``primary 
PM2.5''). PM2.5 can also form as a result of 
chemical reactions in the atmosphere of precursor pollutants emitted 
from sources (i.e. ``secondary PM2.5''). Such secondary 
PM2.5 precursor pollutants include nitrogen oxides 
(NOX), sulfur dioxide (SO2), volatile organic 
compounds (VOC), and ammonia.\3\
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    \2\ See 78 FR 3086, 3088 (January 15, 2013).
    \3\ See EPA, Air Quality Criteria for Particulate Matter, No. 
EPA/600/P-99/002aF and EPA/600/P-99/002bF, October 2004.
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    On July 18, 1997, EPA revised the particulate matter NAAQS to 
establish new primary and secondary annual and 24-hour standards for 
PM2.5.\4\ 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. 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 
population-oriented monitor within an area.\5\
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    \4\ 62 FR 38652 (July 18, 1997).
    \5\ In this action, EPA set primary and secondary standards at 
the same level for both the 24-hour and the annual PM2.5 
standards.
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    On October 17, 2006,\6\ EPA revisited the particulate matter NAAQS, 
retaining the annual average PM2.5 NAAQS at 15 [mu]g/m\3\, 
but revising 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).\7\ On January 15, 2013, EPA finalized the 2012 
PM2.5 NAAQS, which revised the annual standard to 12.0 
[mu]g/m\3\ based on a 3-year average of annual mean PM2.5 
concentrations, but retained the current 24-hour standard of 35 
[micro]g/m\3\ based on a 3-year average of the 98th percentile of 24-
hour concentrations.\8\
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    \6\ See 71 FR 61144.
    \7\ Under 40 CFR part 50, the primary and secondary 2006 24-hour 
PM2.5 NAAQS are attained when the annual arithmetic mean 
concentration (as determined in accordance with 40 CFR part 50, 
appendix N) is less than or equal to 35 [micro]g/m\3\ at all 
relevant monitoring sites in the subject area, averaged over a 3-
year period.
    \8\ See 78 FR 3086.

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[[Page 35854]]

    Following promulgation of a new or revised NAAQS, EPA is required 
by CAA section 107(d) to designate areas throughout the nation as 
attaining or not attaining the NAAQS. EPA designated and classified the 
Allegheny County area as ``Moderate'' nonattainment for the 2012 annual 
PM2.5 standards based on ambient monitoring data that showed 
the area was above 12.0 [micro]g/m\3\ for the 2011-2013 monitoring 
period.\9\ Based on monitoring data for the 2011-2013 period, the 
PM2.5 annual design values for the Liberty monitor [AIRS ID 
42-00300064] were 13.4 [mu]g/m\3\.
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    \9\ See 80 FR 2206 (January 15, 2015).
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    The Allegheny County 2012 PM2.5 nonattainment area lies 
in southwestern Pennsylvania and in 2018 had a population of 1,218,452 
persons. Pittsburgh is the largest city in Allegheny County, which also 
contains the Cities of Clairton, Duquesne, and McKeesport. In total, 
the County has 130 self-governing municipalities. Allegheny County has 
complex, mountainous terrain cut by numerous river valleys, which can 
work to trap locally generated air pollutants. Within the County, some 
river valleys lie at less than 720 feet in elevation above mean sea 
level (MSL), while adjacent hilltops can be greater than 1250 feet--
with frequently large temperature differences between the hilltop and 
valley floor (e.g. 2 to 7 [deg]F) during clear, light-wind, nighttime 
conditions. The combination of higher elevation mountainous terrain and 
river valleys, in conjunction with cool weather, traps locally 
generated pollution and makes the area prone to atmospheric inversions 
that impair PM2.5 dispersion, sometimes for multiple days, 
particularly during winter. The Liberty monitor sits above the east 
bank of the Monongahela River at an elevation of 1,100 feet, 
immediately downwind of the highest emitting PM2.5 
stationary source in the area, the U.S. Steel Clairton Coke Works, 
which lies in the river valley at an elevation 300 feet below the 
monitor. As a result, the monitored PM2.5 values at the 
Liberty monitor are sometimes far higher than those of other monitors 
in the surrounding region.
    ACHD has the primary responsibility for developing a plan to attain 
the 2012 annual PM2.5 NAAQS in this area, working in 
conjunction with the PADEP in preparing the Allegheny County 
PM2.5 Plan. Under Pennsylvania law, authority for regulating 
sources in the area is split between the County and Pennsylvania, with 
ACHD having primary responsibility for regulating stationary sources in 
the area.

II. Clean Air Act Plan Requirements for Areas Designated Moderate 
Nonattainment for the PM2.5 NAAQS

    A January 4, 2013, U.S. Court of Appeals for the District of 
Columbia Circuit decision \10\ stated that EPA must implement 
PM2.5 NAAQS pursuant to title I, part D, subpart 4 of the 
CAA, which contains provisions specifically concerning PM10 
nonattainment areas. With respect to the statutory requirements for 
attainment plans for the 2012 annual PM2.5 NAAQS, general 
CAA nonattainment area planning requirements are found in part D, 
subpart 1, and planning requirements specific to areas designated 
Moderate for particulate matter are found in subpart 4 of part D.
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    \10\ Natural Resources Defense Council v. EPA, 706 F. 3d 428 
(D.C. Cir. 2013).
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    EPA has a longstanding general guidance document interpreting the 
1990 amendments to the CAA, referred to as the General Preamble for the 
Implementation of title I of the Clean Air Act of 1990 (or the 
``General Preamble'').\11\ The General Preamble addresses the 
relationship between the requirements of CAA part D, subpart 1 and 
subpart 4, and provides recommendations to states for meeting certain 
statutory requirements for particulate matter attainment plans. As 
explained in the General Preamble, requirements specific to Moderate 
area attainment plan SIP submissions for particulate matter NAAQS are 
set forth in subpart 4 of part D, title I of the CAA. However, such SIP 
submissions must also meet the general attainment planning provisions 
in subpart 1 of part D, title I of the CAA, to the extent these 
provisions ``are not otherwise subsumed by, or integrally related to,'' 
the more specific subpart 4 requirements.\12\
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    \11\ See General Preamble, 57 FR 13498 (April 16, 1992).
    \12\ See 57 FR 13538, April 16, 1992.
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    To implement the PM2.5 NAAQS, EPA also promulgated the 
``Fine Particulate Matter National Ambient Air Quality Standard: State 
Implementation Plan Requirements; Final Rule'' (or the 
``PM2.5 SIP Requirements Rule'').\13\ The PM2.5 
SIP Requirements Rule provides additional regulatory requirements and 
guidance applicable to attainment plan submissions for the 
PM2.5 NAAQS, including the 2012 annual PM2.5 
NAAQS that is the subject of this action. The PM2.5 SIP 
Requirements Rule also clarifies how states should meet the statutory 
SIP requirements that apply to areas designated nonattainment for any 
PM2.5 NAAQS under both subparts 1 and 4.
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    \13\ See 81 FR 58010, August 24, 2016.
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    The CAA subpart 1 statutory requirements for attainment plans 
include: (i) The section 172(c)(1) requirements for RACM/RACT and 
attainment demonstrations; (ii) the section 172(c)(2) requirement to 
demonstrate RFP; (iii) the section 172(c)(3) requirement for 
preparation of emissions inventories; (iv) the section 172(c)(5) 
requirements for adoption of a nonattainment new source review (NNSR) 
permitting program; and (v) the section 172(c)(9) requirement to adopt 
contingency measures.
    Requirements specific to Moderate PM2.5 nonattainment 
areas under CAA subpart 4 include: (i) The section 189(a)(1)(A) and 
189(e) NNSR permit program requirements; (ii) the section 189(a)(1)(B) 
requirements for attainment demonstrations; (iii) the section 
189(a)(1)(C) requirements for RACM; and (iv) the section 189(c) 
requirements for RFP and QMs. Under CAA subpart 4, states with Moderate 
PM2.5 nonattainment areas must provide for attainment in the 
area as expeditiously as practicable (but no later than December 31, 
2021) for the 2012 PM2.5 annual NAAQS. In addition, under 
CAA subpart 4, direct PM2.5 (and all precursors to the 
formation of PM2.5) are subject to control unless EPA 
approves a demonstration from the state establishing that a given 
precursor does not contribute significantly to PM2.5 levels 
that exceed the PM2.5 NAAQS in the area.\14\
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    \14\ See 40 CFR 51.1006 and 51.1009.
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III. Review of the Allegheny County PM2.5 Plan

A. Emissions Inventories for the Base Year and Attainment Year

1. Requirements for Emissions Inventories
    CAA section 172(c)(3) requires that each SIP include a 
``comprehensive, accurate, current inventory of actual emissions from 
all sources of the relevant pollutant or pollutants in [the] area . . 
.'' By requiring an accounting of actual emissions from all sources of 
the relevant pollutants in the area, this section provides for the base 
year inventory to include all emissions that contribute to the 
formation of a particular NAAQS pollutant. For the 2012 
PM2.5 NAAQS, this includes emissions of direct 
PM2.5 as well as the main chemical precursors to the 
formation of secondary PM2.5, including NOX, 
SO2, VOCs, and ammonia (NH3). Primary 
PM2.5 is comprised of both

[[Page 35855]]

condensable and filterable particulate matter components.
    EPA PM2.5 requirements rule establishes that ``the base 
year inventory for the nonattainment area: (a) Be required to represent 
one of the 3 years used for designations or another technically 
appropriate year; (b) include actual emissions of all sources within 
the nonattainment area; (c) be annual total or average-season-day 
emissions in accordance with the NAAQS violation; (d) include direct 
PM2.5 (filterable and condensable) as well as all scientific 
PM2.5 precursors . . .'' \15\
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    \15\ 81 FR 58027-58033, August 24, 2016.
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    A state must include in its SIP submission documentation explaining 
how the emissions data were calculated. In estimating mobile source 
emissions, a state should use the latest emissions models and planning 
assumptions available at the time it develops the SIP submission.\16\ 
States are also required to use EPA's ``Compilation of Air Pollutant 
Emission Factors'' (AP-42) \17\ road dust method for calculating re-
entrained road dust emissions from paved roads.\18\ MOVES is EPA's 
state-of-the-art tool for estimating emissions from on-road mobile 
sources. At the time ACHD prepared the SIP, MOVES2014a was the latest 
available version of the MOVES model, which included new data, emission 
standards, and functional improvements and features over prior versions 
of the model.\19\ EPA subsequently released an updated MOVES model 
(MOVES2014b) in August 2018, which better estimates non-road mobile 
emissions compared to MOVES2014a. However, MOVES2014b was not available 
at the time ACHD began working on emission inventories in support of 
this plan, and EPA does not consider MOVES2014b a new model for SIP and 
transportation conformity purposes.\20\
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    \16\ See EPA's ``Policy Guidance on the Use of MOVES2014 for 
State Implementation Plan Development, Transportation Conformity, 
and Other Purposes,'' (EPA-420-B-14-008; July 2014), p. 6.
    \17\ EPA released an update to AP-42 in January 2011 that 
revised the equation for estimating paved road dust emissions based 
on an updated data regression that included new emission tests 
results.
    \18\ See 76 FR 6328 (February 4, 2011).
    \19\ See EPA guidance document ``Policy Guidance on the Use of 
MOVES2014 for State Implementation Plan Development, Transportation 
Conformity, and Other Purposes'' (EPA-420-B-14-008; July 2014).
    \20\ See EPA guidance document ``EPA Releases MOVES2014b Mobile 
Source Emissions Model: Questions and Answers,'' (EPA-420-F-18-014; 
August 2018), available at: https://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=P100V7H1.pdf.
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    In addition to the base year inventory submitted to meet the 
requirements of CAA section 172(c)(3), the State must also submit 
future ``baseline inventories'' for the projected attainment year and 
each RFP milestone year, and any other year of significance for meeting 
applicable CAA requirements.\21\ By ``baseline inventories'' (also 
referred to as ``projected baseline inventories''), we mean projected 
emissions inventories for future years that account for, among other 
things, the ongoing effects of economic growth and adopted emissions 
control requirements. The SIP submission should include documentation 
to explain how the state calculated the emissions projections.
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    \21\ See 40 CFR 51.1007(a), 51.1008(b), and 51.1009(f). See also 
U.S. EPA, ``Emissions Inventory Guidance for Implementation of Ozone 
[and Particulate Matter] National Ambient Air Quality Standards 
(NAAQS) and Regional Haze Regulations,'' available at: https://www.epa.gov/sites/production/files/2017-07/documents/ei_guidance_may_2017_final_rev.pdf.
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2. Emissions Inventories in the Allegheny County PM2.5 Plan
    The Allegheny County PM2.5 nonattainment area emissions 
inventory has both small and medium city typical emission sources and 
is home to several large industrial sources of PM2.5 
pollution. The Monongahela River Valley contains the U.S. Steel 
Corporation's Mon Valley Works, which includes the largest coke 
manufacturing plant in the United States (the U.S. Steel Clairton Coke 
Works) as well as the Irvin and Edgar Thomson steel works. The area is 
also home (or nearby to) to several steel manufacturing facilities, 
coal fired electric generating facilities, and other manufacturing and 
industrial facilities.
    As specified by EPA's PM2.5 Implementation Rule, 
pollutants inventoried for the Allegheny County PM2.5 area 
include primary (direct) PM2.5 along with precursors 
SO2, NOX, VOC, and NH3. Particulate 
emissions are also transported into the Allegheny County area from 
surrounding counties in southwestern Pennsylvania, as well as 
surrounding, upwind states. EPA's Emissions Inventory Guidance for 
PM2.5 specifies that PM10 should also be included 
because PM10 emissions are often used as the basis for 
calculating PM2.5.\22\
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    \22\ See U.S. EPA, ``Emissions Inventory Guidance for 
Implementation of Ozone [and Particulate Matter] National Ambient 
Air Quality Standards (NAAQS) and Regional Haze Regulations,'' 
available at: https://www.epa.gov/sites/production/files/2017-07/documents/ei_guidance_may_2017_final_rev.pdf
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    The 2021 inventory is a projection of the 2011 base year inventory, 
which accounts for expected growth trends for each source category, as 
well as emission reductions from adopted and implemented control 
measures. This projection inventory also factors in stationary source 
shutdowns occurring since the base year. Local projections were focused 
on PM2.5 and precursor reductions from stationary point 
source emissions, while regional projections were based on reductions 
from all sectors as incorporated into the Mid-Atlantic Regional Air 
Management Association (MARAMA) inventories. ACHD staff worked with 
PADEP to develop the base year and projection emissions inventories for 
the Allegheny County PM2.5 nonattainment area.
    The base 2011 and future projection 2021 emissions inventories for 
the Allegheny County PM2.5 area used in this demonstration 
are found in Section 4 (Emissions Inventories) of the Commonwealth's 
September 30, 2019 SIP revision, with detailed emissions inventories 
found in Appendix D (Emissions Inventories) of the SIP revision. 
Documentation of the regional inventory development is included in 
Appendix E (Emissions Inventory Documentation) of the SIP revision, and 
emissions inputs used for the modeling are described in Section 5 
(Modeling Demonstration) and Appendix F (Modeling Protocols). Table 1 
provides a summary of the 2011 base year emission inventory for the 
Allegheny County area in tons per year (tpy) of direct PM2.5 
and PM2.5 precursors and also a summary of the 2021 
projected emissions inventory.

[[Page 35856]]

                               Table 1--Base Year and Projected Attainment Year Emission Inventories for Allegheny County
                                                                     [Tons per year]
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                                                     PM2.5         PM2.5           PM2.5
                Allegheny County                    (total)    (filterable)    (condensable)     PM10         SO2         NOX         VOC         NH3
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                                    2011 Base Year Emission Inventory for Allegheny County, by Sector (Tons per Year)
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Point Sources...................................       2,503           1,338           1,164       2,987      13,460      11,128       1,169         207
Area Sources....................................       2,491           2,011             480       4,683       1,528       6,979      11,200         621
Non-road Mobile Sources.........................         361             361               0         378          11       3,921       3,780           5
Highway Mobile Sources..........................         450             450               0         984          78      13,259       7,383         304
Fires...........................................          24              24               0          29           2           5          64           4
Biogenic Sources................................           0               0               0           0           0         166       5,876           0
                                                 -------------------------------------------------------------------------------------------------------
    Total.......................................       5,829           4,185           1,644       9,061      15,080      35,460      29,972       1,141
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Point Sources...................................       2,256           1,256             999       2,722       5,921       7,928       1,534         202
Area Sources....................................       2,708           2,226             472       5,486       1,079       6,664      10,221         615
Non-road Mobile Sources.........................         234             234               0         248           5       2,212       2,752           6
Highway Mobile Sources..........................         266             266               0         722          31       5,708       3,479         209
Fires...........................................          24              24               0          29           2           5          64           4
Biogenic Sources................................           0               0               0           0           0         168       5,876           0
                                                 -------------------------------------------------------------------------------------------------------
    Total.......................................       5,488           4,007           1,471       9,207       7,039      22,684      23,926       1,037
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3. EPA's Evaluation and Proposed Action on the Emission Inventories
    The emission inventories in the Allegheny County area 
PM2.5 plan are based on the most current and accurate 
information available to PADEP and ACHD at the time the attainment plan 
was developed and used the most recently available tools and planning 
assumptions. The emission inventories in the attainment plan 
comprehensively address all source categories in the Allegheny County 
PM2.5 nonattainment area and were developed consistent with 
EPA's emission inventory preparation guidance. The selection of 2011 
for use as a base year emissions inventory is one of the three years 
(2011-2013) used for purposes of designation of the area and the 2021 
projection emissions inventory corresponds to the moderate area 
attainment deadline, in accordance with EPA's SIP requirements rule. 
The inventories model direct PM2.5 (including the filterable 
and condensable components), as well as PM2.5 precursor 
emissions. For these reasons, we are proposing to approve the 2011 base 
year emissions inventory in the Allegheny County PM2.5 Plan 
as meeting the requirements of CAA section 172(c)(3). We are also 
proposing to find that the 2021 projected inventory in the plan is an 
adequate basis for the determination of RACM, RFP, and for 
demonstrating attainment in the Allegheny County PM2.5 Plan. 
For further information on our review of the emission inventories 
supporting this plan, refer to EPA's Technical Support Document (TSD) 
for Emission Inventories prepared in support of this action, which is 
available in the docket.

B. Particulate Matter Precursor Demonstration

1. PM2.5 Precursor Requirements
    The provisions of subpart 4 of part D, title I of the CAA do not 
define the term ``precursor'' for purposes of PM2.5, nor 
does subpart 4 explicitly require the control of any specifically 
identified PM precursor. However, the definition of ``air pollutant'' 
in CAA section 302(g) ``includes any precursors to the formation of any 
air pollutant, to the extent the Administrator has identified such 
precursor or precursors for the particular purpose for which the term 
`air pollutant' is used.''
    In the PM2.5 SIP Requirements Rule, EPA recognized that 
treatment of PM2.5 precursors is an important issue in 
developing a PM2.5 attainment plan.\23\ Therein, EPA 
identified SO2, NOX, VOC, and NH3 as 
precursors to formation of PM2.5. Accordingly, the 
attainment plan requirements of subpart 4 apply to emissions of all 
four precursor pollutants and direct PM2.5 from all types of 
stationary, area, and mobile sources, except as otherwise provided in 
the Act (e.g., in CAA section 189(e)).
---------------------------------------------------------------------------

    \23\ See section III of EPA's PM2.5 SIP Requirements 
Rule (81 FR 58017, August 24, 2016).
---------------------------------------------------------------------------

    Section 189(e) of the CAA requires that the control requirements 
for major stationary sources of direct PM10 (which includes 
PM2.5) also apply to major stationary sources of 
PM10 precursors, except where the Administrator determines 
that such sources do not contribute significantly to PM10 
levels that exceed the standard in the area. Section 189(e) contains 
the only expressed exception to the control requirements under subpart 
4 for sources of PM2.5 precursor emissions. Although section 
189(e) explicitly addresses only major stationary sources, EPA 
interprets the Act as authorizing it to also determine, under 
appropriate circumstances, that regulation of specific PM2.5 
precursors from other sources in a given nonattainment area is not 
necessary.
    Under the PM2.5 SIP Requirements Rule, a state may elect 
to submit to EPA a ``comprehensive precursor demonstration'' for a 
specific nonattainment area to show that emissions of a particular 
precursor from all existing sources located in the nonattainment area 
do not contribute significantly to PM2.5 levels that exceed 
the standard in the area.\24\ Such a comprehensive precursor 
demonstration must include a concentration-based contribution analysis 
(i.e., evaluation of the contribution of a particular precursor to 
PM2.5 levels in the area) and may also include a 
sensitivity-based contribution analysis (i.e., evaluation of the 
sensitivity of PM2.5 levels in the area to a decrease in 
emissions of the precursor). If EPA determines that the contribution of 
the precursor to PM2.5 levels in the area is not significant 
and approves the demonstration, the state is not required to control 
emissions of the relevant precursor from existing sources in the 
current attainment plan.\25\
---------------------------------------------------------------------------

    \24\ See 40 CFR 51.1006(a)(1).
    \25\ Id.
---------------------------------------------------------------------------

    EPA issued PM2.5 Precursor Demonstration Guidance 
(``Precursor

[[Page 35857]]

Guidance'') to provide recommendations to states for conducting an 
optional, comprehensive precursor demonstration as part of an 
attainment plan SIP submission.\26\ Section 1.1.1 of the Precursor 
Guidance describes the steps for performing a precursor demonstration. 
First, a concentration-based analysis should be performed to determine 
whether all emissions of the relevant precursor contribute 
significantly to total PM2.5 concentrations. If the 
concentration-based analysis does not support a finding of 
insignificant contribution, then a sensitivity analysis may be 
conducted to evaluate, through air quality modeling, the effect of 
reducing emissions of the precursor (by a certain percentage) from 
either all existing emission sources of the precursor or only existing 
major stationary sources of the precursor, on PM2.5 levels 
in the area.
---------------------------------------------------------------------------

    \26\ See EPA Office of Air Quality Planning and Standards, 
``Fine Particulate Matter (PM2.5) Precursor Demonstration 
Guidance,'' [EPA-454/R-19-004, May 30, 2019] https://www.epa.gov/pm-pollution/pm25-precursor-demonstration-guidance.
---------------------------------------------------------------------------

    Section 2.2 of the Precursor Guidance recommends the use of 0.2 
[micro]g/m\3\ for the annual PM2.5 NAAQS and 1.5 [micro]g/
m\3\ for the 24-hour PM2.5 NAAQS as thresholds below which 
ambient air quality impacts could be considered ``insignificant'' 
(i.e., impacts that do not ``contribute'' to PM2.5 
concentrations that exceed the NAAQS). When considering whether a 
precursor contributes significantly to PM2.5 levels which 
exceed the NAAQS in the area, a state may also consider additional 
factors based on the specific circumstances of the area. As to air 
quality impacts that exceed the 0.2 [micro]g/m\3\ annual or 1.5 
[micro]g/m\3\ 24-hour contribution thresholds, states may provide 
additional support for a conclusion that a particular precursor does 
not contribute significantly to ambient PM2.5 levels that 
exceed the NAAQS. States may consider other information, such as the 
amount by which the impacts exceed the recommended contribution 
threshold; the severity of nonattainment at relevant monitors and/or 
grid cell locations in the area; anticipated growth or loss of sources; 
analyses of speciation data and precursor emission inventories; and air 
quality trends.\27\
---------------------------------------------------------------------------

    \27\ Id. at p. 17.
---------------------------------------------------------------------------

2. Precursor Demonstration in the Allegheny County PM2.5 
Plan
    The Allegheny County PM2.5 Plan includes a comprehensive 
precursor demonstration, which evaluates the impact of the precursors 
VOC and NH3 to nonattainment of the PM2.5 NAAQS 
in Allegheny County. The concentration-based analysis indicates that 
all precursors show ambient monitored levels above the thresholds for 
significant contribution.\28\ Therefore, a sensitivity analysis was 
performed using Comprehensive Air Quality Model with extensions 
(CAMx).\29\ CAMx is a Eulerian photochemical grid model that simulates 
a wide variety of inert and chemically active pollutants, including 
ozone, particulate matter, inorganic and organic PM2.5/
PM10, and mercury and other toxics. For the sensitivity 
analysis, a total of three CAMx runs were used to evaluate 
PM2.5 sensitivity to reductions of NH3 and VOC 
emissions in Allegheny County: A base case and two sensitivity-case 
runs. For one sensitivity-case run, anthropogenic emissions of VOC in 
Allegheny County were reduced by 50%. For the other sensitivity-case 
run, anthropogenic emissions of NH3 were reduced by 50%. For 
both runs, the 50% reductions were applied to both point and area 
source anthropogenic emissions with all other emissions held constant. 
EPA's Modeled Attainment Test Software (MATS) was then used to model 
design values at monitoring sites in Allegheny County with and without 
the 50% reduction in VOC and NH3. Table 2 shows the 
projected annual and 24-hour reductions in PM2.5 design 
values (DVs) at the monitoring sites in the nonattainment area based on 
the reductions for VOC and NH3. Additional information 
regarding the sensitivity analysis can be found in Appendix I.4 
(Precursor Insignificance Demonstration) of the Allegheny County 
PM2.5 Plan.
---------------------------------------------------------------------------

    \28\ For additional information on the concentration-based 
analysis, see Appendix C of the Allegheny County PM2.5 
Plan.
    \29\ CAMx is a photochemical grid model that simulates a wide 
variety of inert and chemically active pollutants, including ozone, 
particulate matter, inorganic and organic PM2.5/
PM10, and mercury and other toxics.

          Table 2--Sensitivity Test Reductions in Design Values (DVs) at Allegheny County Area Monitors
----------------------------------------------------------------------------------------------------------------
                                                           Annual basis                    24-hour basis
                                                 ---------------------------------------------------------------
                                                   Reduction in    Reduction in    Reduction in    Reduction in
       Monitoring Site               AQS ID         DV with 50%     DV with 50%     DV with 50%     DV with 50%
                                                     less VOC        less NH3        less VOC        less NH3
                                                    ([micro]g/      ([micro]g/      ([micro]g/      ([micro]g/
                                                       m\3\)           m\3\)           m\3\)           m\3\)
----------------------------------------------------------------------------------------------------------------
Avalon.......................        42-003-0002            0.01            0.20             0.0             0.1
Lawrenceville................        42-003-0008            0.00            0.23             0.0             0.0
Liberty......................        42-003-0064            0.00            0.15             0.0             0.8
South Fayette................        42-003-0067            0.00            0.10             0.0             0.1
North Park...................        42-003-0093            0.00            0.17             0.1             0.9
Harrison.....................        42-003-1008            0.00            0.13             0.0             0.0
North Braddock...............        42-003-1301            0.00            0.21             0.0             0.4
Clairton.....................        42-003-3007            0.00            0.13             0.0             0.0
----------------------------------------------------------------------------------------------------------------

    As can be seen in Table 2, the modeled decreases in design values 
due to a 50% reduction in VOC and NH3 at the Liberty monitor 
are both below the significance thresholds of 0.2 [micro]g/m\3\ for the 
annual PM2.5 NAAQS and 1.5 [micro]g/m\3\ for the 24-hour 
PM2.5 NAAQS. Therefore, ACHD determined that VOC and 
NH3 are both insignificant contributors to nonattainment in 
Allegheny County and excluded both precursors from additional analysis 
in the Allegheny County PM2.5 Plan.
3. EPA's Evaluation and Proposed Action on the Precursor Demonstration
    EPA has reviewed the comprehensive precursor demonstration included 
in the Allegheny County PM2.5 Plan and is proposing to find 
that it meets the requirements of the PM2.5 SIP Requirements 
Rule and EPA's Precursor Guidance. The comprehensive precursor 
demonstration includes a sensitivity analysis that indicates that the 
estimated impacts of a 50% reduction in point and area source 
anthropogenic

[[Page 35858]]

emissions of VOC and NH3 are below the significance 
thresholds of 0.2 [micro]g/m\3\ for the annual PM2.5 NAAQS 
and 1.5 [micro]g/m\3\ for the 24-hour PM2.5 NAAQS at the 
Liberty monitor, which has consistently been the highest reading 
PM2.5 monitor in Allegheny County and the only monitor in 
the County not meeting the 2012 annual PM2.5 NAAQS. Since 
the estimated impacts at the Liberty monitor are below the significance 
threshold, it can be concluded, for purposes of the precursor 
demonstration, that the precursors VOC and NH3 do not 
significantly contribute to nonattainment of the PM2.5 NAAQS 
in Allegheny County. Therefore, pursuant to 40 CFR 51.1006, EPA is 
proposing to find that Allegheny County is not required to control 
emissions of VOC or NH3 from existing sources in the 
Allegheny County PM2.5 Plan.

C. Reasonably Available Control Measures (RACM)/Reasonably Available 
Control Technology (RACT)

1. Requirements for RACM/RACT
    CAA section 172(c)(1) requires that each attainment plan ``provide 
for the implementation of all reasonably available control measures as 
expeditiously as practicable (including such reductions in emissions 
from existing sources in the area as may be obtained through the 
adoption, at a minimum, of reasonably available control technology) and 
shall provide for attainment of the national ambient air quality 
standards.'' Section 189(a)(1)(C) of the CAA requires that states with 
areas classified as moderate nonattainment for PM2.5 have 
attainment plan provisions to assure that RACM and RACT are implemented 
no later than four years after designation of the area. EPA reads CAA 
sections 172(c)(1) and 189(a)(1)(C) together to require that attainment 
plans for moderate nonattainment areas must provide for the 
implementation of RACM and RACT for existing sources of 
PM2.5 and PM2.5 precursors in the nonattainment 
area as expeditiously as practicable but no later than four years after 
designation.\30\
---------------------------------------------------------------------------

    \30\ See 81 FR 58010 and 58034, August 24, 2016.
---------------------------------------------------------------------------

    The preamble to the PM2.5 SIP Requirements Rule defines 
RACM as ``any technologically and economically feasible measure that 
can be implemented in whole or in part within four years after the 
effective date of designation of a PM2.5 nonattainment 
area,'' including RACT.\31\ The preamble also recommends steps for 
evaluating control measures as part of a RACM/RACT analysis.\32\ In 
short, a RACM/RACT analysis is a process for states to identify 
emission sources, evaluate potential emission controls, and impose 
those control measures and technologies that are reasonable and 
necessary to bring the area into attainment as expeditiously as 
practicable, but no later than the statutory attainment date for the 
area.
---------------------------------------------------------------------------

    \31\ See 81 FR 58010-58035 and 58043, August 24, 2016, as well 
as 40 CFR 51.1009(a)(4)(i)(A).
    \32\ See 81 FR 58010-58035 and 58046, August 24, 2016.
---------------------------------------------------------------------------

    Pursuant to the preamble of the PM2.5 SIP Requirements 
Rule, in the case of a moderate area that can demonstrate it can attain 
by the statutory 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 one 
year earlier (i.e. ``advance the attainment date'' by one year).\33\ 
The attainment date for the Allegheny County nonattainment area is 
December 31, 2021.
---------------------------------------------------------------------------

    \33\ See 81 FR 58018, August 24, 2016.
---------------------------------------------------------------------------

2. RACM Analysis in the Allegheny County PM2.5 Plan
    A summary of ACHD's RACM analysis is provided in Section 6 of the 
Allegheny County PM2.5 Plan and a detailed analysis is 
provided in Appendix J. Based on the insignificance findings for VOC 
and NH3, ACHD did not evaluate options for the control of 
VOC and NH3 in their RACM analysis. ACHD's RACM analysis 
examines options for the control of primary PM2.5 and 
precursors SO2 and NOX in the Allegheny County 
nonattainment area for the following source categories: Area sources, 
non-road mobile sources, on-road mobile sources, and some small point 
sources.
    For each source category, ACHD evaluated RACM alternatives through 
the following process: (1) Examine source category emissions in the 
nonattainment area; (2) determine technologically feasible control 
technologies or measures for each source category; and, (3) for each 
technologically feasible control technology or measure, examine the 
control efficiency by pollutant, the estimated emission reductions by 
pollutant, the estimated cost per ton of pollutant reduced, and the 
date by which the technology or measure could be reasonably 
implemented.
a. RACM Measures Evaluation
    Table 3 lists the RACM measures in the Allegheny County 
PM2.5 Plan. These measures are discussed in more detail in 
Appendix J of the Allegheny County PM2.5 Plan, which is 
located in the docket for this rulemaking.

                      Table 3--Summary of RACM Alternatives Evaluated for Allegheny County
----------------------------------------------------------------------------------------------------------------
                                          Existing controls/
        Source category group                  programs           RACM alternative(s)             Notes
----------------------------------------------------------------------------------------------------------------
Agriculture..........................  None...................  None identified........  Small source of
                                                                                          emissions; mostly NH3
                                                                                          emissions, NH3 is an
                                                                                          insignificant
                                                                                          precursor in the
                                                                                          nonattainment area.
Commercial Cooking...................  None...................  1. Charbroiler           1. Small emission
                                                                 catalytic oxidizers      reductions county-
                                                                 for chain-driven         wide.
                                                                 broilers..              2. Full implementation
                                                                2. HEPA filters for       could take five years
                                                                 under-fired boilers..    from promulgation.
Cremation............................  None...................  None identified........  Small source of
                                                                                          emissions county-wide;
                                                                                          permit restrictions
                                                                                          are BACT.
Fuel Combustion (Industrial and        Federal standards for    Low-NOX burners........  Full implementation
 Commercial).                           boilers and engines.                              could take five years
                                                                                          from promulgation.
Fuel Combustion (Residential)........  Sulfur limit for home    None identified........  Small source of
                                        heating oil.                                      emissions compared to
                                                                                          commercial and
                                                                                          industrial fuel
                                                                                          combustion.

[[Page 35859]]

 
Fuel Combustion (Residential Wood)...  1. Fireplace insert      1. Additional wood       1. Insignificant
                                        program.                 stove change-out         emission reductions.
                                       2. Prohibition of non-    program.                2. Reductions difficult
                                        phase 2 outdoor wood-   2. Education and          to quantify.
                                        fired boilers (OWBs)..   outreach on clean       3. Reductions and costs
                                       3. No outdoor burning     burning..                difficult to quantify;
                                        when Air Quality        3. Replacement of old     Significant PM2.5
                                        Action Days are          stoves when homes are    emission reductions
                                        predicted..              sold..                   unlikely within short
                                       4. Wood stove change-    4. OWB compliance for     to medium timeframe.
                                        out program..            pre-2011 units..        4. Insignificant
                                                                                          emission reductions.
Fugitive Dust........................  Use of dust              Paving of all unpaved    Small emission
                                        suppressants.            roads countywide.        reductions county-
                                                                                          wide.
Oil and Gas Exploration and            None...................  No feasible, cost        None.
 Production.                                                     effective options were
                                                                 identified.
Petroleum Storage....................  None...................  None identified........  VOC emissions only, VOC
                                                                                          is an insignificant
                                                                                          precursor in the
                                                                                          nonattainment area.
Solvent Utilization..................  ACHD regulations.......  None identified........  VOC emissions only, VOC
                                                                                          is an insignificant
                                                                                          precursor in the
                                                                                          nonattainment area.
Surface Coatings.....................  ACHD regulations.......  None identified........  VOC emissions only, VOC
                                                                                          is an insignificant
                                                                                          precursor in the
                                                                                          nonattainment area.
Marine...............................  Federal standards;       1. Vessel repowering     1. High costs.
                                        towboat repowering       from Tier 0 to newer    2. Small emission
                                        project.                 engines.                 reductions.
                                                                2. Retrofit tugboats     3. Emission reductions
                                                                 with diesel              not quantified,
                                                                 particulate filters..    potential
                                                                3. Control idling......   insignificant emission
                                                                4. Pleasure craft         reductions.
                                                                 controls..              4. Emission reductions
                                                                                          not quantified,
                                                                                          potential
                                                                                          insignificant emission
                                                                                          reductions that are
                                                                                          not cost effective.
Railroad.............................  Federal standards......  Replacement of older     High costs relative to
                                                                 engines to newer         emission reductions.
                                                                 engines.
Off-Highway Equipment (Gasoline).....  Rebate program for       Additional gas-for       Emission reductions not
                                        gasoline-fueled          electric exchange        quantified, potential
                                        equipment exchange.      programs.                insignificant emission
                                                                                          reductions.
Off-Highway Equipment (Diesel).......  Federal Standards;       Retrofit construction    Small emission
                                        idling restrictions.     equipment with a         reductions county-
                                                                 diesel particulate       wide.
                                                                 filter (DPF).
Off-Highway Equipment (Other)........  None...................  None identified........  None.
Gasoline Refueling...................  Stage II vapor recovery  None identified........  VOC emissions only, VOC
                                        systems.                                          is an insignificant
                                                                                          precursor in the
                                                                                          nonattainment area.
Gasoline Vehicles (Light-Duty).......  Federal emission         Ridesharing program....  Reductions not
                                        standards; Inspection/                            quantified; light duty
                                        Maintenance (I/M)                                 gasoline vehicles show
                                        program.                                          large reductions
                                                                                          through 2021 with
                                                                                          current controls.
Gasoline Vehicles (Heavy-Duty).......  Federal emission         None...................  Small portion of the on-
                                        standards; idling                                 road mobile source
                                        restrictions.                                     inventory.
Diesel Refueling.....................  None...................  None identified........  VOC emissions only, VOC
                                                                                          is an insignificant
                                                                                          precursor in the
                                                                                          nonattainment area.
Diesel Vehicles (Light-Duty).........  Federal emission         None identified........  Small portion of the on-
                                        standards; idling                                 road mobile source
                                        restrictions.                                     inventory.
Diesel Vehicles (Heavy Duty).........  Federal emission         (1) Additional diesel    (1) Small emission
                                        standards; idling        engine retrofits.        reductions county-
                                        restrictions.           (2) Replacement of        wide.
                                                                 public or private       (2) Small emission
                                                                 fleets ahead of normal   reductions county-
                                                                 schedule..               wide.
                                                                (3) Additional diesel    (3) Reductions not
                                                                 idling requirements..    quantified.
Compressed Natural Gas (CNG) Vehicles  None...................  None identified........  Small portion of the on-
 (Heavy Duty).                                                                            road mobile source
                                                                                          inventory.
Ethanol E-85 Vehicles (Light-duty      None...................  None identified........  Small portion of the on-
 gasoline, capable of burning 85%                                                         road mobile source
 ethanol 15% gasoline blend).                                                             inventory.
Aggregate Processing.................  Rules in effect for      Require water sprays,    None.
                                        stone, sand, and         dust suppressants,
                                        gravel operations.       telescopic chutes, and
                                                                 baghouse/cyclone dust
                                                                 collectors.
----------------------------------------------------------------------------------------------------------------

[[Page 35860]]

3. RACT Analysis in the Allegheny County PM2.5 Plan
    Section 6 of the Allegheny County PM2.5 Plan also 
includes a summary of ACHD's RACT analysis. ACHD's detailed analysis is 
provided in Appendix J of the Allegheny County PM2.5 Plan.
    ACHD used the following methodology for their RACT analysis: (1) 
Identify all current major stationary point sources of 
PM2.5, SO2, or NOX in the Allegheny 
County nonattainment area; (2) identify the different processes, or 
process groups, for the applicable major source facilities and the 
current controls for the processes; (3) identify potential RACT 
alternatives for the process groups; and (4) evaluate the technological 
and economic feasibility of any potential RACT alternatives.\34\
---------------------------------------------------------------------------

    \34\ An explanation of sources that were excluded from ACHD's 
RACT analysis as well as the control technologies that were analyzed 
are provided in Appendix J of the Allegheny County PM2.5 
Plan.
---------------------------------------------------------------------------

a. RACT Measures Evaluation
    Table 4 summarizes the identified facilities and corresponding 
findings from ACHD's RACT analysis for the Allegheny County 
PM2.5 Plan. ACHD's complete RACT analysis is provided in 
Appendix J of the Allegheny County PM2.5 Plan.

                        Table 4--Summary of RACT Analysis in Allegheny County PM2.5 Plan
----------------------------------------------------------------------------------------------------------------
                                                          Summary of
            Facility               Major  pollutants       facility            Controls          RACT Findings
----------------------------------------------------------------------------------------------------------------
Allegheny Energy Springdale.....  PM, NOX...........  Combined-cycle      Low NOX burners     Meets RACT
(now Springdale Energy).........                       turbine EGU,        (LNB), selective    requirements.
                                                       natural gas (NG)    catalytic
                                                       or fuel oil.        reduction (SCR).
ATI Allegheny Ludlum............  PM, SO2, NOX......  Specialty steel     Baghouses, ultra-   Meets RACT
                                                       facility.           low NOX burners     requirements.
                                                                           (ULNB), mist
                                                                           eliminators.
Bay Valley (now Riverbend)......  NOX...............  Food manufacturing  LNB, flue gas       Meets RACT
                                                       facility.           recirculation       requirements.
                                                                           (FGR); switched
                                                                           from coal to
                                                                           natural gas as
                                                                           fuel for all
                                                                           units.
Bellefield Boiler...............  NOX...............  Steam generation    LNB, FGR..........  Meets RACT
                                                       facility.                               requirements.
Energy Center Pittsburgh (North   NOX...............  District heating    LNB, drift          Meets RACT
 Shore).                                               and cooling plant.  eliminators.        requirements.
GenOn Brunot Island.............  PM, SO2, NOX......  Combined-cycle      Water injection     Meets RACT
                                                       turbine EGU, NG     with SCR, mist      requirements.
                                                       or fuel oil.        eliminators.
GenOn Cheswick..................  PM, SO2, NOX......  Coal-fired EGU....  FGD, LNB with       Meets RACT
                                                                           overfire air        requirements.
                                                                           (OFA), SCR, ESP.
Pittsburgh Allegheny County       NOX...............  Steam generation    NOX limits........  Meets RACT
 Thermal (PACT).                                       facility.                               requirements.
Universal Stainless.............  NOX...............  Specialty steel     LNB, baghouses....  Meets RACT
                                                       facility.                               requirements.
University of Pittsburgh--Main    NOX...............  Public university.  ULNB, FGR, low      Meets RACT
 Campus.                                                                   sulfur fuel oil.    requirements.
U.S. Steel Clairton.............  PM, SO2, NOX......  Metallurgical coke  Baghouses, baffles  Meets RACT
                                                       and by-products     (quench towers),    requirements.
                                                       facility.           coke oven gas
                                                                           (COG) grain
                                                                           limits,
                                                                           afterburners,
                                                                           visible emission
                                                                           (VE) restrictions.
USS Edgar Thomson...............  PM, SO2, NOX......  Iron and steel      Baghouses, COG      Meets RACT
                                                       making facility.    grain limits,       requirements.
                                                                           scrubbers, drift
                                                                           eliminators.
USS Irvin.......................  PM, SO2, NOX......  Secondary steel     COG grain limits,   Meets RACT
                                                       processing          scrubbers, mist     requirements.
                                                       facility.           eliminators.
----------------------------------------------------------------------------------------------------------------

4. EPA's Evaluation and Proposed Action on RACM and RACT
    ACHD has found that no economically or technologically feasible 
controls (or combination thereof) in Allegheny County are needed to 
show attainment by the attainment date of December 31, 2021 and that no 
feasible controls (or combination thereof) will advance the attainment 
date by one year or more (i.e. to December 31, 2020). The Allegheny 
County PM2.5 Plan includes a modeling demonstration showing 
that Allegheny County can attain the 2012 PM2.5 NAAQS by the 
December 31, 2021 attainment date through the control strategy 
described in the plan.
    EPA is proposing to approve ACHD's evaluation of RACM/RACT control 
measures in the Allegheny County PM2.5 Plan. ACHD has 
demonstrated in the plan that Allegheny County can attain the 
PM2.5 NAAQS by the attainment date without implementing 
RACM/RACT. Also, according to the Allegheny County PM2.5 
Plan, the implementation of additional control measures will not 
advance the attainment date in Allegheny County by one year or more. 
Therefore, EPA is proposing to find that the Allegheny County 
PM2.5 Plan satisfies the RACM/RACT requirements of title I, 
part D, subpart 1 and subpart 4 of the CAA.

D. Air Quality Modeling

1. Requirements for Air Quality Modeling
    Section 189(a)(1)(B) of the CAA requires that a plan for a Moderate 
PM2.5 nonattainment area include a demonstration (including 
air quality modeling) that the plan will provide for attainment by the 
applicable attainment date, or a demonstration that attainment by such 
date is impracticable. An attainment demonstration must show that the 
control measures in the plan are sufficient to attain the NAAQS by the 
attainment date. The attainment demonstration predicts future ambient 
concentrations for comparison to the NAAQS, making use of available

[[Page 35861]]

information on ambient concentrations, meteorology, and current and 
projected emissions inventories, including the effect of control 
measures in the plan. This information is typically used in conjunction 
with a computer model of the atmosphere.
    EPA has provided additional modeling requirements and guidance for 
modeling analyses in the ``Guideline on Air Quality Models'' 
(``Guideline'').\35\ Per the PM2.5 SIP Requirements Rule, 
the attainment demonstration modeling guidance provides recommendations 
that include: Developing a conceptual description of the problem to be 
addressed; developing a modeling/analysis protocol; selecting an 
appropriate model to support the demonstration; selecting appropriate 
meteorological episodes or time periods to model; choosing an 
appropriate area to model with appropriate horizontal/vertical 
resolution; generating meteorological and air quality inputs to the air 
quality model; generating emissions inputs to the air quality model; 
and, evaluating performance of the air quality model. After these steps 
are completed, the state can apply a model to simulate effects of 
future year emissions and candidate control strategies.
---------------------------------------------------------------------------

    \35\ 40 CFR part 51 appendix W, ``Guideline on Air Quality 
Models,'' 82 FR 5182, January 17, 2017; available at https://www.epa.gov/scram/clean-air-act-permit-modeling-guidance.
---------------------------------------------------------------------------

2. Air Quality Modeling in the Allegheny County PM2.5 Plan
    ACHD's September 30, 2019 PM2.5 SIP revision includes a 
modeling demonstration showing that monitors in Allegheny County will 
comply with both the 24-hour and the annual 2012 PM2.5 
standards by December 31, 2021. The demonstration is based, in part, on 
results from the CAMx analysis. The modeling analysis also includes a 
local area analysis using the US EPA's AERMOD Gaussian dispersion model 
to analyze the direct PM2.5 component for the Liberty 
monitor, which has consistently been the highest reading 
PM2.5 monitor in Allegheny County.
    The highest PM monitor readings in Allegheny County are generally 
attributed to a combination of high localized industrial source 
emissions with strong temperature inversions, which trap those locally 
generated emissions within the major river valleys. Elevation 
differences between the valley floors and surrounding terrain can be on 
the order of 500 feet. Under ideal meteorological conditions (i.e. 
light winds and clear night-time skies), Allegheny County has observed 
temperature differences between hilltop and valley floor in the range 
of 2 to 7 degrees Fahrenheit along with strong channeled flow within 
the Monongahela River valley (``Mon Valley''). Strong temperature 
inversions inhibit vertical mixing, trapping emissions emitted at near 
ground-level within the valleys, contributing to episodes of poor air 
quality.
    Given the topography of the area, which is marked by low mountains 
and river valleys, and the resulting influence of that topography on 
localized meteorological conditions and a propensity for atmospheric 
inversions, ACHD developed their modeling analysis to consider these 
localized conditions. Further, the modeling analysis needed to properly 
account for both regional emission sources, and more importantly the 
specific, localized impacts of several large industrial source 
emissions that strongly contribute to episodes of poor air quality. 
Further details related to development of the baseline and projected 
year inventories can be found in appendices D and E of the 
Commonwealth's September 30, 2019 SIP revision, which are available in 
the docket for this rulemaking. The modeling protocols used for the 
Commonwealth's analysis are found in Appendix F of the September 2019 
SIP revision.
    Modeling for the Allegheny County area assesses regional impacts 
from PM2.5 precursors and localized impacts from primary 
PM2.5 sources. CAMx was utilized at fine grid resolution to 
model both long-range transport and near-field impacts of most sources. 
EPA's AERMOD Gaussian dispersion model was used for simulating 
localized primary PM2.5 impacts at the Liberty monitor, 
which has consistently recorded the highest monitor concentrations 
since PM2.5 monitoring began in the area in the late 1990s.
    ACHD provided an extensive review of meteorological conditions in 
Allegheny County over a five-year period from 2009 through 2013.\36\ 
The ACHD analysis involved a general review of inversions, winds, 
temperature, and precipitation in general and its appropriateness for 
the modeling demonstration. The modeling demonstration is indicative of 
these meteorological conditions and the use of 2011 base year emissions 
data is suitable to represent typical conditions over the five-year 
(2009-2013) period examined--with the exception of one month (October 
2011) that recorded severe inversions.
---------------------------------------------------------------------------

    \36\ See Appendix B of the September 30, 2019 SIP submittal 
``Meteorological Analysis.''
---------------------------------------------------------------------------

    CAMx-ready emissions were prepared for the 2011 modeling base year 
and projected 2021 attainment year and pre-processed for input to CAMx 
using the Sparse Matrix Operator Kernel Emissions (SMOKE) model.\37\ 
CAMx was evaluated using ambient observational data from three 
monitoring networks: EPA's Air Quality System (AQS) database; Federal 
Reference Method (FRM) total PM2.5 mass; and the Chemical 
Speciation Network (CSN) speciated PM2.5. The Atmospheric 
Model Evaluation Tool (or AMET) was the primary software tool used to 
compare observations and modeled values from the 1.333 kilometer (km) 
domain in Allegheny County.\38\ ACHD found good agreement between 
modeled and observed PM2.5 concentrations across Allegheny 
County. The results of the model performance evaluations can be 
referenced in Appendix G of the Commonwealth's September 30, 2019 SIP.
---------------------------------------------------------------------------

    \37\ See SMOKE model, at https://www.cmascenter.org/smoke/.
    \38\ See AMET software at: https://www.cmascenter.org/amet/.
---------------------------------------------------------------------------

    ACHD used MATS with the CAMx 2011 and 2021 modeling results to 
obtain 2021 projected attainment year design value concentrations at 
all of the FRM monitoring sites within the modeling domain. This 
included some monitoring sites outside the Allegheny County 
PM2.5 nonattainment area. Allegheny County's projected 2021 
PM2.5 concentrations are summarized in Table 5 and include a 
breakdown of each modeled PM2.5 component (2021 projected 
value is the sum of all the PM2.5 components).

[[Page 35862]]

                         Table 5--Projected 2021 CAMx Modeled Values for the 2012 PM2.5 NAAQS for Allegheny County Area Monitors
                                                                [Based on a 1.33 km grid]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                          CAMx projected design value and PM2.5 modeled components  (1.333 km grid)
                                    --------------------------------------------------------------------------------------------------------------------
          Monitoring Site               Actual     Projected
                                      2016-18 DV    2021 DV        OPP           ED          NH4          OCmb         SO4          NO3          NaCl
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                     Allegheny County Area 24-Hour Design Values **
--------------------------------------------------------------------------------------------------------------------------------------------------------
Avalon.............................         20.2         21.4        0.606        0.965        2.191        9.064        3.258        3.564        0.150
Clairton...........................         18.7         21.4        0.869        3.542        1.882        7.753        4.464        0.828        0.038
Harrison...........................         20.0         20.7        0.870        1.348        1.809        8.807        4.917        0.862        0.055
Lawrenceville......................         18.4         20.4        1.000        0.996        1.855        8.723        4.334        1.480        0.087
Liberty............................         34.9         38.6        1.248        3.910        2.520       21.634        4.978        2.253        0.060
North Braddock.....................         24.5         23.4        1.178        2.564        2.353        8.304        4.577        2.403        0.096
North Park.........................         15.6         17.3        1.280        0.948        1.537        6.783        4.272        0.585        0.047
South Fayette......................         18.3         18.4        1.188        1.480        1.613        6.952        4.552        0.700        0.039
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                       Allegheny County Area Annual Design Values
--------------------------------------------------------------------------------------------------------------------------------------------------------
Avalon.............................          9.7         10.0        0.398        0.508        0.772        4.727        1.926        0.566        0.028
Clairton...........................          9.3          9.2        0.508        1.266        0.843        2.703        2.205        0.734        0.014
Harrison...........................          9.6          9.4        0.495        0.633        0.856        3.470        2.219        0.689        0.026
Lawrenceville......................          9.1          9.0        0.483        0.530        0.810        3.395        1.999        0.614        0.032
Liberty............................         12.6         12.5        0.618        1.509        1.058        4.637        2.795        0.937        0.017
North Braddock.....................         10.7         10.0        0.608        0.989        0.951        3.192        2.463        0.797        0.023
North Park.........................          7.8          7.6        0.593        0.478        0.743        2.219        1.908        0.560        0.026
South Fayette......................          8.3          8.5        0.579        0.636        0.774        2.844        2.071        0.592        0.020
--------------------------------------------------------------------------------------------------------------------------------------------------------
** 24-Hour Design values are rounded to nearest whole number so Avalon's projected 2021 24-hour design value is 21 [micro]g/m\3\
Blank = Salt and passive component held constant from base to future case, OPP = other primary PM2.5, EC = elemental carbon, NH4 = ammonium, OCmb =
  organic carbon mass (by) mass balance, SO4 = sulfate, NO3 = Nitrate, NaCl = ``salt''.

    Modeled 2021 PM2.5 design values for all monitors except 
the Liberty monitor meet the revised 2012 PM2.5 NAAQS. All 
monitors in Allegheny County meet the 24-hour PM2.5 NAAQS 
using 2018 design values. Only the Liberty monitor is projected to 
exceed the revised 2012 annual PM2.5 NAAQS in 2021, based on 
the CAMx developed design values. Therefore, in accordance with EPA's 
modeling guidance, ACHD undertook a more refined local area analysis to 
better gauge emission control impacts for sources nearby the Liberty 
monitor in southern Allegheny County and the effect of controlling 
those sources on projected PM2.5 concentrations in the 
Liberty monitor area. The Liberty monitor's location on elevated 
terrain several miles downwind of the U.S. Steel Clairton Coke Works 
complicates this analysis.
    As stated in EPA's ``Modeling Guidance for Demonstrating Air 
Quality Goals for Ozone, PM2.5 and Regional Haze'' 
(``Modeling Guidance''), ``. . . there are numerous cases where local 
source contributions may not be dominant but are a sizable contributor 
to total annual average PM2.5 at this monitor. In these 
cases, a more refined analysis of the contribution of local primary 
PM2.5 sources to PM2.5 at the monitor(s) will 
help explain the causes of nonattainment at and near the monitor and 
may lead to more efficient ways to attain the NAAQS by controlling 
emissions from local sources which may be important contributors to the 
violating area.'' \39\ ACHD has done analysis of regional monitor 
concentrations and demonstrated unique industrial source influences 
using source apportionment modeling \40\ and concluded that the Liberty 
monitor, ``shows a large contribution from carbon-rich industrial 
sources, not present at the other sites, that contribute carbons as 
well as primary sulfate and several trace elements.''
---------------------------------------------------------------------------

    \39\ EPA policy memo, Modeling Guidance for Demonstrating Air 
Quality Goals for Ozone, PM2.5 and Regional Haze, from 
Richard Wayland, dated November 29, 2018. See p. 134. Available at: 
https://epa.gov/ttn/scram/guidance/guide/O3-PM-RH-Modeling_Guidance-2018.pdf.
    \40\ See Appendix C of the September 30, 2019 SIP Revision, 
``Speciation and Source Apportionment Analysis.''
---------------------------------------------------------------------------

    EPA's Modeling Guidance allows the use of several tools to evaluate 
contributions of local PM2.5 sources, such as Gaussian 
dispersion modeling. 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.\41\ ACHD utilized EPA's AERMOD model to 
conduct a local area analysis of the Liberty monitor area. The refined 
Liberty local analysis modeling used AERMOD to further resolve the 
impact of local area sources and meteorology beyond the CAMx analysis, 
to generate the final modeled design values at the Liberty monitor. 
This local area analysis shows that the Liberty monitor will attain by 
attainment deadline.
---------------------------------------------------------------------------

    \41\ Modeling Guidance for Demonstrating Air Quality Goals for 
Ozone, PM2.5 and Regional Haze, from Richard Wayland, 
dated November 29, 2018, at p. 134.
---------------------------------------------------------------------------

    Finally, ACHD included additional information in its September 30, 
2019 SIP revision constituting a ``weight of evidence'' demonstration 
to support its modeling analysis, per EPA's Modeling guidance.\42\ 
ACHD's weight of evidence demonstration includes analysis of downward 
PM2.5 monitoring trends at Allegheny County monitors, a 
listing of permanent stationary source shutdowns (not reflected in the 
modeling analysis), PM2.5 precursor reductions of 
SO2 resulting from reductions in neighboring areas, emission 
reductions due to population decrease projections, and emission 
reductions due to voluntary programs (not included in the SIP). Also, 
additional EGU deactivations in Pennsylvania and surrounding states 
were announced after EGU forecasting was performed (based on 2015 
data). These deactivations, which were not included in the air quality 
modeling for this plan, will lead to further reductions of 
PM2.5 precursor emissions that

[[Page 35863]]

potentially contribute PM2.5 emissions to Allegheny County. 
Further information on recent planned EGU deactivations can be found in 
Section 11.4 of the Allegheny County PM2.5 Plan.
---------------------------------------------------------------------------

    \42\ See pp. 169-171 of EPA's Modeling Guidance for 
Demonstrating Air Quality Goals for Ozone, PM2.5 and 
Regional Haze, which outlines several other analyses that could be 
included in any attainment demonstration to help bolster results 
from the primary modeling analysis. These could include additional 
modeling analyses, analyses of trends in ambient air quality and 
emissions, and additional emissions controls/reductions.
---------------------------------------------------------------------------

3. EPA's Evaluation and Proposed Action on Modeling
    EPA has reviewed the modeling demonstration prepared by ACHD for 
the Allegheny County PM2.5 nonattainment area. EPA also 
reviewed the supporting local area AERMOD dispersion model analysis 
prepared by ACHD to assess the impact of sources closest to the Liberty 
monitor. ACHD modeling protocols covering the Weather Research and 
Forecasting (WRF) prognostic meteorological model, the CAMx modeling 
domains and the AERMOD local area analysis all comport with EPA's 
Modeling Guidance.\43\
---------------------------------------------------------------------------

    \43\ Ibid.
---------------------------------------------------------------------------

    With the exception of the Liberty monitor, the CAMx model projected 
2021 PM2.5 design values for all monitors in Allegheny 
County are projected to be below the NAAQS by the attainment deadline. 
ACHD elected to conduct a refined local area assessment to further 
assess the impact of several large nearby sources beyond the scope of 
the CAMx modeling. The Allegheny County Plan contains ACHD's arguments 
supporting its contention that the CAMx 1.333 km modeling analysis 
could be overestimating projected 2021 PM2.5 concentrations 
at the Liberty monitor.\44\ These CAMx modeling limitations cited 
include: Limitations in CAMx's ability to properly characterize 
concentration gradients across the 1.333 km grid cells, failure to use 
the most up to date available stack test emissions data and stack test 
emission calculations for several key sources in the area, improper 
CAMx source characterizations, and improper source apportionment by 
CAMx.
---------------------------------------------------------------------------

    \44\ See Appendix F.3 of the September 30, 2019 SIP revision.
---------------------------------------------------------------------------

    EPA proposes to agree with ACHD's assessment that these are 
reasonable arguments to support use of a supplemental local area 
analysis using AERMOD dispersion modeling to refine projected 2021 
model concentrations at the Liberty monitor. Final projected 2021 
values at the Liberty monitor using the local area analysis were 35 
[micro]g/m\3\ (24-hour) and 12.0 [micro]g/m\3\ (annual), which 
demonstrate attainment with the 2012 PM2.5 NAAQS.
    Given that the projected 2021 PM2.5 concentrations at 
the Liberty monitor just meet the 2012 PM2.5 NAAQS, ACHD's 
use of additional supporting information via a weight of evidence 
demonstration is warranted. The Allegheny County Plan contains a 
monitor value trends analysis showing statistically significant 
downward trends at all of its PM2.5 monitoring sites, 
including the Liberty monitor. EPA agrees with ACHD's contention that 
the Pennsylvania Jersey Maryland Power Pool (PJM Interconnection, or 
simply PJM) forecasts of electric generation for the last few years 
have overestimated the actual amount of electric generation needed, and 
as a result the projected regional PM2.5 precursor emissions 
from the electric generation sector are likely overestimated.\45\ 
Electricity generation and demand reports from PJM indicate a decline 
in coal-fired power plant operations and an increase in power 
generation share from a rise in number and capacity of lower emission 
producing, more efficient combined-cycle natural gas plants. This trend 
is leading to significant reductions in regional emissions of 
SO2, a precursor to PM2.5.\46\ It also appears 
that the CAMx model overestimates projections for some monitor 
locations in Allegheny County, as shown by the fact that actual 
measured 2018 PM2.5 design values are already below forecast 
2021 model projections. Allegheny County also documented additional 
local emission reductions and source shutdowns which were not accounted 
for in the projected emission inventories, along with other voluntary 
programs that could lead to additional emission reductions. The 
combination of these weight of evidence impacts should lead to 
continued reductions in PM2.5 monitor concentrations in 
Allegheny County.
---------------------------------------------------------------------------

    \45\ See Appendix K of the September 30, 2019 SIP revision.
    \46\ See Section 3, page 104, http://www.monitoringanalytics.com/reports/PJM_State_of_the_Market/2018.shtml.
---------------------------------------------------------------------------

    EPA believes ACHD's modeling demonstration shows that its projected 
2021 PM2.5 design values will likely comply with the 2012 
PM2.5 NAAQS--particularly since the actual 2018 
PM2.5 design values at all monitoring sites in Allegheny 
County (except the Liberty monitor) meet the 2012 PM2.5 
NAAQS. Allegheny County's unmonitored area analysis attempts to more 
accurately ensure attainment over the entire county and not just those 
portions covered by the monitoring network. Given the results of ACHD's 
CAMx modeling for the area, the refined AERMOD local area assessment, 
and the additional emission reductions and other supporting arguments 
from ACHD's weight of evidence demonstration, EPA supports ACHD's 
finding that PM2.5 design values at the Liberty monitor will 
meet the 2012 PM2.5 NAAQS by the December 31, 2021 
attainment date.

E. Attainment Demonstration

1. Requirements for an Attainment Demonstration
    CAA section 189(a)(1)(B) requires that each state in which a 
Moderate PM2.5 nonattainment area is located submit an 
attainment plan that includes, among other things, either a 
demonstration (including air quality modeling) that the plan will 
provide for attainment by the applicable attainment date, or a 
demonstration that attainment by such date is impracticable. In 
addition, CAA section 172(c)(1) generally requires, for each 
nonattainment area, a plan that provides for the implementation of all 
RACM and RACT as expeditiously as practicable and provides for 
attainment of the NAAQS. EPA interprets these two provisions together 
to require that an attainment demonstration for a Moderate 
PM2.5 nonattainment area meet the following criteria: (1) 
The attainment demonstration must show the projected attainment date 
for the area that is as expeditious as practicable; (2) the attainment 
demonstration must meet the requirements of 40 CFR part 51, appendix W 
and must include inventory data, modeling results, and emission 
reduction analyses on which the state has based its projected 
attainment date; (3) the base year for the emissions inventory required 
for the attainment demonstration must be one of the three years used 
for designations or another technically appropriate inventory year; and 
(4) the control strategies modeled as part of the attainment 
demonstration must be consistent with the control strategy requirements 
under 40 CFR 51.1009(a), including the requirements for RACM/RACT and 
additional reasonable measures.\47\
---------------------------------------------------------------------------

    \47\ See EPA's PM2.5 Implementation Rule, at 40 CFR 
51.1011(a).
---------------------------------------------------------------------------

    In addition, the attainment demonstration must provide for the 
implementation of all control measures needed for attainment as 
expeditiously as practicable, but no later than the beginning of the 
year containing the applicable attainment date.\48\
---------------------------------------------------------------------------

    \48\ Id.
---------------------------------------------------------------------------

2. Attainment Demonstration in the Allegheny County PM2.5 
Plan
    As explained in section III.D of this document, ACHD's 
PM2.5 SIP includes a modeling demonstration, based on

[[Page 35864]]

modeling using currently implemented emission control measures, that 
shows that monitors in Allegheny County, Pennsylvania will comply with 
both the 24-hour and the annual PM2.5 standards by December 
31, 2021. The modeling for the Allegheny County PM2.5 
nonattainment area focuses on regional impacts from PM2.5 
precursors and localized impacts from primary PM2.5 sources. 
ACHD also conducted an unmonitored area analysis to better refine those 
areas of Allegheny County further from the air monitor sites, as was 
discussed earlier in section III.D of this document pertaining to the 
modeling.
    The attainment plan includes a weight of evidence analysis to 
further bolster the attainment demonstration. The plan shows reductions 
in PM2.5 emissions and PM2.5 precursor emission 
inventories between 2011 and 2021 as a result of implementation of 
RACT/RACM, stationary source shutdowns (not reflected in the 2011 
inventory), and from implemented state, local, and Federal emission 
controls.
    ACHD contends that the results from their modeling analysis, as 
well as its weight of evidence supplemental analysis, demonstrate that 
all monitors in Allegheny County will attain the revised 2012 24-hour 
and annual PM2.5 NAAQS by the statutory date (December 31, 
2021).
3. EPA's Evaluation of ACHD's PM2.5 Attainment Demonstration
    EPA evaluated whether ACHD has adequately demonstrated that the 
Allegheny County Area meets EPA requirements for demonstration of 
attainment, as described here:
    a. The attainment demonstration must show the projected attainment 
date for the area that is as expeditious as practicable.
    As discussed in section III.D of this preamble, EPA proposes to 
find that the modeling demonstration and additional analysis in the 
attainment plan show that the area will achieve the 2012 
PM2.5 NAAQS by the attainment date. In its review of RACM 
measures, ACHD found no additional measures that, if enacted, would 
advance the attainment deadline earlier than the December 31, 2021 
attainment deadline. Currently, 2018 PM2.5 design values at 
all monitoring sites in Allegheny County except Liberty meet the 2012 
PM2.5 NAAQS. Allegheny County's unmonitored area analysis 
predicts attainment over the entire County. Given the results of the 
refined local area analysis, ACHD's analysis of potential model 
overestimations, and additional emission reductions identified as part 
of the weight of evidence demonstration (that are not included in the 
modeling demonstration), EPA concludes that attainment demonstration 
modeling reasonably projects that all the monitors in the area will 
meet the 2012 PM2.5 NAAQS by the 2021 projected attainment 
date and that attainment prior to that date is not practicable.
    b. The attainment demonstration must meet the requirements of 40 
CFR part 51, appendix W and must include inventory data, modeling 
results, and emission reduction analyses on which the state has based 
its projected attainment date;
    Based on our analysis of the attainment modeling demonstration in 
section III.D of this document, EPA also proposes to conclude that the 
attainment demonstration modeling includes appropriate modeling 
analysis information complying with the requirements of 40 CFR part 51, 
appendix W. Based on EPA's review of the supporting PM2.5 
and PM2.5 precursor emission inventories (as described in 
the emission inventory section of this action), EPA also proposes to 
conclude that the plan includes appropriate emission inventory data to 
meet the related EPA emission inventory requirements.
    c. The base year for the emissions inventory required for the 
attainment demonstration must be one of the three years used for 
designations or another technically appropriate inventory year; and
    ACHD selected 2011 as its base year for the emissions inventory 
used for the attainment demonstration. Since 2011 is one of the three 
years (i.e., 2011-2013) used for designation purposes, EPA finds that 
this choice of base year for the attainment demonstration meets EPA 
requirements.
    d. The control strategies modeled as part of the attainment 
demonstration must be consistent with the control strategy requirements 
under 40 CFR 51.1009(a), including the requirements for RACM/RACT and 
additional reasonable measures.
    Based on our review of ACHD's attainment demonstration modeling, 
EPA proposes to find that the air quality modeling meets the 
requirements of 40 CFR 51.1011(a) and accounts for all technically and 
economically feasible control measures for direct PM2.5 (as 
well as PM2.5 precursor) emissions sources upon which PADEP 
and ACHD have based their projected attainment date for the area. 40 
CFR 51.1009(a) and 40 CFR 51.1011.
    As part of the RACT/RACM determination (in conjunction with the 
accompanying weight of evidence demonstration emission reductions), EPA 
proposes to conclude that the control strategies modeled as part of the 
attainment demonstration are consistent with the control strategy 
requirements under 40 CFR 51.1009(a), including the requirements for 
RACM/RACT and additional reasonable measures. Based on the RACT/RACM 
analysis and the additional weight of evidence demonstration for 
PM2.5 and PM2.5 precursor emission reductions, 
EPA believes the attainment modeling analysis shows that the projected 
December 31, 2021 attainment date for the area is as expeditious as 
practicable.
    e. The attainment demonstration must provide for the implementation 
of all control measures needed for attainment as expeditiously as 
practicable, but no later than the beginning of the year containing the 
applicable attainment date.
    In Section 3 (Control Strategy) of the Allegheny County 
PM2.5 Plan, ACHD sets out its attainment control strategy. 
ACHD incorporated the controls described in Section 3 in the future 
case 2021 emissions and modeling inventories for the attainment 
demonstration. These controls include local source modifications, local 
source shutdowns, and regional controls. ACHD states that the local 
source modifications are Federally enforceable through ACHD 
installation permits and operating permits. These local source 
modifications are fully implemented, and the shutdowns all occurred 
after the 2011 base year, but prior to the submittal of the plan. The 
regional controls include various Federal control measures as well as 
two Pennsylvania statewide measures related to sulfur limits for 
commercial fuel oil and VOC limits for adhesives and sealants. These 
regional measures are also fully implemented.
    EPA has evaluated ACHD's control strategy for attainment and found 
that all control measures needed for attainment have been implemented 
has expeditiously as practicable. The attainment date is December 31, 
2021. These controls were all implemented prior to PADEP submitting the 
September 30, 2019 SIP revision. Therefore, EPA concludes that the 
control measures were implemented well before the beginning of the year 
containing the applicable attainment date, 2021.
4. EPA's Proposed Action on the PM2.5 Attainment 
Demonstration
    EPA proposes to conclude that the attainment demonstration for the 
Allegheny County PM2.5 Plan meets the requirements for a 
moderate area plan under CAA section 189(a)(1)(B), and

[[Page 35865]]

that this plan contains an approvable demonstration (including air 
quality modeling) showing that the plan provides for attainment by the 
applicable attainment date. EPA also proposes to conclude that this 
plan meets CAA section 172(c)(1) requirements to provide for the 
implementation of RACM and RACT as expeditiously as practicable and 
provides for attainment of the NAAQS. By meeting these requirements, 
EPA proposes to conclude that ACHD's plan for the Allegheny County 
PM2.5 area meets applicable requirements for an approvable 
attainment demonstration for a Moderate PM2.5 nonattainment 
area.

F. Reasonable Further Progress (RFP)

1. Requirements for Ensuring Reasonable Further Progress
    CAA section 172(c)(2) states that all nonattainment area plans 
shall demonstrate reasonable progress towards attainment. In addition, 
CAA section 189(c) requires that all PM2.5 nonattainment 
area SIPs include a QM demonstration, to be achieved every three years 
until the area is redesignated to attainment and which demonstrate RFP, 
as defined in CAA section 171(l). Section 171(l) defines RFP as ``such 
annual incremental reductions in emissions of the relevant air 
pollutant as are required by part D or may reasonably be required by 
the Administrator for the purpose of ensuring attainment of the 
applicable [NAAQS] by the applicable date.'' Neither subpart 1 nor 
subpart 4 of part D, title I of the Act requires that a set percentage 
of emissions reductions be achieved in any given year for purposes of 
satisfying the RFP requirement. EPA's SIP requirements rule does not 
require a specific RFP related inventory, but the attainment projected 
inventory for the nonattainment area also may serve a purpose for 
evaluation of RFP.\49\
---------------------------------------------------------------------------

    \49\ See EPA PM2.5 Implementation Rule. 81 FR 58029, 
August 24, 2016.
---------------------------------------------------------------------------

    For purposes of the PM2.5 NAAQS, EPA has interpreted the 
RFP requirement to require that nonattainment area plans show annual 
incremental emission reductions sufficient to maintain generally linear 
progress toward attainment by the applicable deadline.\50\ As discussed 
in EPA guidance in the Addendum to the General Preamble (or ``the 
Addendum''),\51\ requiring linear progress in reductions of direct 
PM2.5 and any individual precursor in a PM2.5 
plan may be appropriate in situations where: The pollutant is emitted 
by a large number and range of sources; the relationship between any 
individual source or source category and overall air quality is not 
well known; a chemical transformation is involved (e.g., secondary 
particulate significantly contributes to PM2.5 levels over 
the standard); and/or the emission reductions necessary to attain the 
PM2.5 standard are inventory-wide.\52\
---------------------------------------------------------------------------

    \50\ Addendum to the General Preamble at p. 42015. 59 FR 41998, 
August 16, 1994.
    \51\ Id.
    \52\ Id.
---------------------------------------------------------------------------

    The Addendum indicates that requiring linear progress may be less 
appropriate in other situations, such as: Where there are a limited 
number of sources of direct PM2.5 or a precursor; where the 
relationships between individual sources and air quality are relatively 
well defined; and/or where the emission control systems utilized will 
result in swift and dramatic emission reductions.
    In nonattainment areas characterized by any of these latter 
conditions, RFP may be better represented as stepwise progress as 
controls are implemented and achieve significant reductions soon 
thereafter. For example, if an area's nonattainment problem can be 
attributed to a few major sources, EPA guidance indicates that ``RFP 
should be met by adherence to an ambitious compliance schedule, which 
is likely to periodically yield significant emission reductions of 
direct PM2.5 or a PM2.5 precursor.'' \53\ This 
latter case is applicable to the Allegheny County Area, as the 
violating monitor is impacted heavily by nearby major emission sources, 
which are implementing controls in a stepwise fashion between the base 
year and attainment deadline.
---------------------------------------------------------------------------

    \53\ Id at p. 42015.
---------------------------------------------------------------------------

    Where attainment is driven by regulatory compliance, the 
PM2.5 attainment plan should include a detailed schedule for 
compliance with regulations in the area and provide corresponding 
annual emission reductions to be realized from each milestone in the 
schedule.\54\ In reviewing an attainment plan under CAA subpart 4, EPA 
considers whether the annual incremental emission reductions to be 
achieved are reasonable in light of the statutory objective of timely 
attainment. States should consider both cost-effectiveness and 
pollution reduction effectiveness when developing implementation 
schedules for its control measures and may implement measures that are 
more effective at reducing PM2.5 earlier to provide greater 
public health benefits.\55\
---------------------------------------------------------------------------

    \54\ Id. at p. 42016.
    \55\ Id.
---------------------------------------------------------------------------

    The PM2.5 SIP Requirements Rule establishes specific 
regulatory requirements for purposes of satisfying the Act's RFP 
requirements and provides related guidance in the preamble to the rule. 
Specifically, under the PM2.5 SIP Requirements Rule, each 
PM2.5 attainment plan must contain an RFP analysis that 
includes, at minimum: (1) An implementation schedule for control 
measures; (2) RFP projected emissions for direct PM2.5 and 
all PM2.5 plan precursors for each applicable milestone 
year, based on the anticipated control measure implementation schedule; 
(3) a demonstration that the control strategy and implementation 
schedule will achieve reasonable progress toward attainment between the 
base year and the attainment year; and (4) a demonstration that by the 
end of the calendar year for each milestone date for the area, 
pollutant emissions will be at levels that reflect either generally 
linear progress or stepwise progress in reducing emissions on an annual 
basis between the base year and the attainment year.\56\ States should 
estimate the RFP projected emissions for each milestone year by sector 
on a pollutant-by-pollutant basis.\57\
---------------------------------------------------------------------------

    \56\ 40 CFR 51.1012(a).
    \57\ See 81 FR 58010, 58056 (August 24, 2016).
---------------------------------------------------------------------------

2. RFP Demonstration in the Allegheny County PM2.5 Plan
    The RFP demonstration and QM demonstration methodology are detailed 
in Section 7 of the Allegheny County PM2.5 Plan. ACHD 
elected to try to show that nonattainment area emissions of direct 
PM2.5 pollutants (and significant PM2.5 precursor 
pollutants) decline from the base year to the attainment year, in a 
generally linear manner.
    The Allegheny County Plan estimates that emissions of direct 
PM2.5 will decline steadily from 2011 through 2021 and that 
emissions of direct PM2.5 will generally remain below the 
levels needed to show incremental, continuing progress toward 
attainment. ACHD compiled RFP emissions inventories for the milestone 
years of 2019 and 2022 using the base and projected inventories used in 
the attainment demonstration. Milestone years are based on a schedule 
of 4.5 and 7.5 years after designation (years 2019 and 2022, 
respectively), as outlined in the PM2.5 Implementation Rule 
for a moderate PM2.5 nonattainment area.\58\ Year 2019

[[Page 35866]]

emissions were calculated by linearly interpolating base year 2011 and 
projected case 2021 emissions. Year 2022 emissions were held constant 
from the projected 2021 case, as a conservative approach beyond the 
expected attainment timeframe. In addition to direct PM2.5 
emissions, the RFP demonstration includes PM2.5 precursor 
emissions of SO2 and NOX. However, it does not 
include VOC and NH3 emissions as PM2.5 precursors 
because those emissions were shown to be insignificant for purposes of 
the Allegheny County Plan. The direct PM2.5 emissions for 
the baseline, milestone, and attainment years are shown in Table 6 
(with PM2.5 broken down into filterable and condensable 
components).\59\ The precursor emissions are shown in Tables 7 and 8.
---------------------------------------------------------------------------

    \58\ RFP milestones occur every three years, starting from the 
due date of the SIP (i.e., 18 months after designation), or 4.5 
years and 7.5 after designation in 2015. The second milestone of 7.5 
years, although beyond the attainment date for a moderate area, is 
included in the event the area (at a future date) is reclassified 
from moderate to serious nonattainment.
    \59\ See corresponding Tables 7.1, 7.2, and 7.3 of 
Pennsylvania's September 30, 2019 SIP revision.

                                                      Table 6--Direct PM2.5 RFP Emissions Inventory for Allegheny County, by Milestone Year
                                                                                           [Tons/year]
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                       Base year 2011                Milestone year 2019           Projected attainment 2021           Milestone year 2022
                                                             -----------------------------------------------------------------------------------------------------------------------------------
                            Year                                           PM2.5      PM2.5                 PM2.5      PM2.5                 PM2.5      PM2.5                 PM2.5      PM2.5
                                                                PM2.5     (filter)    (cond)     PM2.5     (filter)    (cond)     PM2.5     (filter)    (cond)     PM2.5     (filter)    (cond)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Point Sources...............................................     2,503      1,338      1,164      2,305      1,272      1,032      2,256      1,256        999      2,256      1,256        999
Area Sources................................................     2,491      2,011        480      2,665      2,183        473      2,708      2,226        472      2,708      2,226        472
Non-road Mobile Sources.....................................       361        361          0        259        259          0        234        234          0        234        234          0
On-road Mobile Sources......................................       450        450          0        303        303          0        266        266          0        266        266          0
Fires.......................................................        24         24          0         24         24          0         24         24          0         24         24          0
Biogenic....................................................         0          0          0          0          0          0          0          0          0          0          0          0
                                                             -----------------------------------------------------------------------------------------------------------------------------------
    Total...................................................     5,829      4,185      1,644      5,556      4,042      1,505      5,488      4,007      1,471      5,488      4,007      1,471
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

               Table 7--Allegheny County SO2 Precursor RFP Emissions Inventory, by Milestone Year
                                                   [Tons/year]
----------------------------------------------------------------------------------------------------------------
                                                                                     Projected
                                                   Baseline 2011  Milestone 2019    attainment    Milestone 2022
                                                                                       2021
----------------------------------------------------------------------------------------------------------------
Stationary Point Sources........................          13,460           7,429           5,921           5,921
Area Sources....................................           1,528           1,169           1,079           1,079
Non-road Mobile Sources.........................              11               6               5               5
On-road Mobile Sources..........................              78              41              31              31
Fires...........................................               2               2               2               2
Biogenic Sources................................               0               0               0               0
                                                 ---------------------------------------------------------------
    Total.......................................          15,080           8,647           7,039           7,039
----------------------------------------------------------------------------------------------------------------

                         Table 8--Allegheny County NOX Precursor RFP Emissions Inventory
                                                   [Tons/year]
----------------------------------------------------------------------------------------------------------------
                                                   Baseline 2011  Milestone 2019  Projected 2021  Milestone 2022
----------------------------------------------------------------------------------------------------------------
Stationary Point Sources........................          11,128           8,568           7,928           7,928
Area Sources....................................           6,979           6,727           6,664           6,664
Non-road Mobile Sources.........................           3,921           2,554           2,212           2,212
On-road Mobile Sources..........................          13,259           7,218           5,708           5,708
Fires...........................................               5               5               5               5
Biogenic Sources................................             166             166             166             166
                                                 ---------------------------------------------------------------
    Total.......................................          35,460          25,239          22,684          22,684
----------------------------------------------------------------------------------------------------------------

    Allegheny County then compared these RFP inventory projections 
against the most currently available National Emissions Inventory (NEI) 
data (i.e., 2017 for stationary point source and 2014 for mobile and 
area emissions) to track the progress of their actual emissions against 
their 2019 milestone year shown in Table 9.\60\
---------------------------------------------------------------------------

    \60\ See Table 7.4 of the September 30, 2019 SIP revision.

[[Page 35867]]

        Table 9--Allegheny County Composite Emissions Inventory, Based on Most Recent Available NEI Data
                                                   [Tons/year]
----------------------------------------------------------------------------------------------------------------
                                                  PM2.5 (filter)   PM2.5 (cond)
                                       PM2.5                                            SO2             NOX
----------------------------------------------------------------------------------------------------------------
Point Sources (2017 NEI)........           1,305             775             530           4,712           6,148
Area Sources (2014 NEI).........           2,646           2,174             473             481           8,687
Non-road Mobile Sources (2014                315             315               0               8           3,183
 NEI)...........................
On-road Mobile Sources (2014                 389             389               0              76          11,754
 NEI)...........................
Fires (2011 NEI)................              24              24               0               2               5
Biogenic Sources (2011 NEI).....               0               0               0               0             166
                                 -------------------------------------------------------------------------------
    Total.......................           4,679           3,677           1,003           5,279          29,943
----------------------------------------------------------------------------------------------------------------

    While the NEI dates do not directly correspond to the 2019 RFP 
milestone year, the composite inventory shows that Allegheny County is 
already meeting their projected PM2.5 and SO2 
emissions. While NOX was not yet meeting the 2019 milestone 
based on actual emissions data, additional NOX reductions 
from mobile sources that occur after 2014 are expected to close the gap 
between 2014 (when the latest mobile NEI data was available) and the 
2019 projected NOX milestone.
    ACHD attempted to show that linear progress towards attainment is 
being made by examining its monitoring data and its point source 
emissions data for the period between the base and attainment years, 
achieved by performing a linear regression on this data to show yearly 
progress. Monitored concentrations are presented in Tables 10 and 11, 
showing the annual and 24-hour PM2.5 design values, 
respectively, for each Allegheny County site for years 2011 through 
2018.\61\
---------------------------------------------------------------------------

    \61\ See Tables 7.5 and 7.6 in the September 30, 2019 SIP 
revision.

               Table 10--Monitored Annual PM2.5 Design Values ([mu]g/m\3\) for Allegheny County Monitor Sites, With Linear Progress Rates
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                             Monitored annual design value ([mu]g/m\3\)                          Yearly
                                                      ----------------------------------------------------------------------------------------  rate of
                     Monitor site                                                                                                                linear
                                                          2011       2012       2013       2014       2015       2016       2017       2018     progress
--------------------------------------------------------------------------------------------------------------------------------------------------------
Liberty..............................................       15.0       14.8       13.4       13.0       12.6       12.8       13.0       12.6      -0.33
Avalon...............................................       14.7       13.4       11.4       10.6       10.6       10.4       10.2        9.7      -0.64
North Braddock.......................................       12.7       12.5       11.7       11.4       11.2       11.0       10.8       10.7      -0.30
Harrison.............................................       12.4       11.7       10.6       10.0        9.8        9.8        9.8        9.6      -0.38
Lawrenceville........................................       11.6       11.1       10.3       10.0        9.7        9.5        9.2        9.1      -0.35
Clairton.............................................       11.5       10.9        9.8        9.5        9.9        9.8        9.8        9.3      -0.24
South Fayette........................................       11.0       10.5        9.6        9.0        8.8        8.5        8.4        8.3      -0.39
North Park...........................................        9.7        9.4        8.8        8.5        8.5        8.2        8.2        7.8      -0.25
--------------------------------------------------------------------------------------------------------------------------------------------------------

                                       Table 11--Monitored 24-Hour PM2.5 Design Values, With Linear Progress Rates
                                                                      [[mu]g/m\3\]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                             Monitored 24-hour design value ([mu]g/m\3\)                         Linear
                                                      ----------------------------------------------------------------------------------------  progress
            Allegheny county monitor site                                                                                                        yearly
                                                          2011       2012       2013       2014       2015       2016       2017       2018       rate
--------------------------------------------------------------------------------------------------------------------------------------------------------
Liberty..............................................         44         43         37         35         33         36         37         35       -1.2
Avalon...............................................         34         29         25         22         23         22         21         20       -1.7
North Braddock.......................................         34         33         29         26         25         25         24         24       -1.5
Harrison.............................................         30         28         25         22         22         21         21         20       -1.4
Clairton.............................................         28         26         22         23         25         26         22         19       -0.8
Lawrenceville........................................         27         26         23         21         21         20         19         18       -1.3
South Fayette........................................         27         26         24         20         21         19         19         18       -1.3
North Park...........................................         25         23         19         17         18         18         17         16       -1.1
--------------------------------------------------------------------------------------------------------------------------------------------------------

    ACHD's analysis of historical monitored PM2.5 design 
values shows that all sites in Allegheny County are achieving roughly 
linear reductions from baseline case through the most recently 
available monitor data. All sites are already below the NAAQS on both 
annual and 24-hour bases, with the exception of the Liberty monitor 
(for the annual PM2.5 NAAQS). Based on the linear annual 
rate of 0.33 [mu]g/m\3\ improvement (for annual design values), ACHD 
expects the Liberty monitor to achieve the annual NAAQS by 2021. Based 
on the linear yearly rate of 1.2 [mu]g/m\3\ for 24-hour design values, 
ACHD expects that the Liberty monitor will continue to achieve the 24-
hour standard.
    EPA's Implementation Rule requires attainment plans to provide an

[[Page 35868]]

implementation schedule containing regulatory implementation timeframes 
showing progress towards attainment. However, ACHD did not present a 
schedule, contending that because all control measures identified for 
the Allegheny County Plan have already been implemented, and there are 
no identified RACM/RACT or ``additional control measures'' to be 
implemented, a schedule for implementation of controls is not 
applicable to this SIP.
3. EPA's Evaluation of and Proposed Action on RFP
    For direct PM2.5, EPA agrees that ACHD has shown steady 
progress towards measuring RFP for the 2012 PM2.5 NAAQS in 
the Allegheny County area. ACHD has shown that the measures being 
implemented in the area show ongoing progress towards achieving the 
NAAQS.
    ACHD has established milestones for comparison of emissions and 
monitored values corresponding to the milestone compliance 
demonstration timeframes discussed in the QM and has demonstrated that 
it has achieved its RFP related milestone requirements for the area. 
Monitored ambient values in the area are trending downward at a steady, 
if not linear rate, and ACHD has demonstrated that both emission 
reductions and monitor values (for both the annual and 24-hour 
PM2.5 NAAQS) are expected to continue to decrease through 
the 2019 milestone deadline and the 2021 attainment deadline.
    As discussed in the precursors section of this proposed document 
(section III.B), EPA is proposing to determine that SO2 and 
NOX are significant precursors in the Allegheny County area, 
but that VOCs and NH3 are insignificant PM2.5 
precursors that do not contribute significantly to ambient 
PM2.5 levels in the area.
    The Allegheny County PM2.5 Plan documents ACHD's 
assertion that they are implementing all reasonable RACM and RACT and 
additional reasonable measures for direct PM2.5 as 
expeditiously as practicable. The plan projects levels of direct 
PM2.5 emissions in 2019 and 2022 that reflect full 
implementation of the Commonwealth's and ACHD's attainment control 
strategy for direct PM2.5 and PM2.5 precursors. 
ACHD's comparison of the most recently available NEI emissions data 
with the projections for 2019 and 2022 in the plan show that emissions 
are falling at expected rates to achieve RFP, and (with the exception 
of NOX), most emissions are at or below 2021 projected 
levels (and are expected to continue to drop with continued 
implementation of control measures identified in the plan).\62\ 
Stationary source controls in the area include controls at the U.S. 
Steel Clairton Coke Works (the largest modeled emission source of 
PM2.5 in the area), including installation of new low-
emission quench towers in 2013, replacement of an older coking battery 
in 2012, and new baffle washing requirements implemented in 2012. Other 
stationary source controls in the area include addition of flue gas 
desulfurization at the GenOn Cheswick coal fired EGU, arc furnace 
improvements and replacements at several area steel manufacturing 
facilities, etc. Further, a number of facilities in the area have been 
permanently shut down and have surrendered their permits, including: 
The Shenango Coke facility, the Guardian and GE Bridgeville glass 
plants, Bakerstown Container, and Allegheny Aggregates, among 
others.\63\ In addition, new mobile source NOX controls and 
the replacement of older, higher emitting mobile sources with new, 
lower-emitting mobile sources due to fleet turnover are expected to 
continue to reduce NOX emissions between the 2014 NEI and 
the 2019 and 2022 future milestone cases.
---------------------------------------------------------------------------

    \62\ See section 3.0 of this document for a list of current 
control measures in the Allegheny County area, including new 
stationary source controls and source shutdowns in the area.
    \63\ See Section 3 of ACHD's plan in the September 30, 2019 SIP 
revision for a complete listing of implemented PM2.5 and 
PM2.5 precursor control strategies.
---------------------------------------------------------------------------

    In the case of an RFP demonstration based solely on linear 
reductions in emissions through the attainment deadline, EPA expects 
that, so long as the attainment date is as expeditious as practicable, 
then generally linear progress toward attainment by that date would 
satisfy the RFP requirement.\64\
---------------------------------------------------------------------------

    \64\ See EPA's PM2.5 Requirements Rule at 81 FR 
58056, August 24, 2016.
---------------------------------------------------------------------------

    Thus, EPA proposes to find that the Allegheny County 
PM2.5 Plan demonstrates that emissions of direct 
PM2.5 will be reduced at rates representing generally linear 
progress towards attainment. EPA also proposes to find that the plan 
demonstrates that all reasonable measures that provide the bases for 
the direct PM2.5 emissions projections in the RFP analysis 
are being implemented as expeditiously as practicable. Accordingly, we 
propose to determine that the plan requires the annual incremental 
reductions in emissions of direct PM2.5 (and significant 
precursors of PM2.5) that are necessary to ensure RFP 
towards attainment of the 2012 annual PM2.5 NAAQS by 2021, 
in accordance with the requirements of CAA sections 171(1) and 
172(c)(2).

G. Quantitative Milestone (QM) Demonstration

1. Requirements for a QM Demonstration
    Section 189(c) requires that attainment plans include milestones to 
demonstrate that RFP is being achieved on a timely basis. The purpose 
of the QM demonstration is to allow for periodic evaluation of the 
area's progress towards attainment of the NAAQS consistent with RFP 
requirements. Because RFP is an annual emission reduction requirement 
while the QMs are to be achieved every three years, when a state 
demonstrates compliance with the QM, it demonstrates that RFP has been 
achieved during each of the relevant three years. QMs provide an 
objective means to evaluate progress toward attainment, e.g., through 
imposition of emission controls in the attainment plan and the 
requirement to quantify those required emission reductions.
    The CAA does not specify the starting point for counting the three-
year periods for QMs under CAA section 189(c). In the General Preamble 
and Addendum, EPA interpreted the CAA to require that the starting 
point for the first three-year period be the due date for the Moderate 
area plan submission.\65\ Consistent with this longstanding 
interpretation of the Act, the PM2.5 SIP Requirements Rule 
requires that each plan for a Moderate PM2.5 nonattainment 
area contain QMs to be achieved no later than milestone dates 4.5 years 
and 7.5 years from the date of designation of the area.\66\ Because EPA 
designated the Allegheny County area nonattainment for the 2012 annual 
PM2.5 NAAQS effective April 15, 2015, the applicable QM 
dates for purposes of the Allegheny County PM2.5 Plan are 
October 15, 2019 and October 15, 2022.\67\
---------------------------------------------------------------------------

    \65\ General Preamble, 57 FR 13539 (April 16, 1992); and 
Addendum, 59 FR 42016 (August 16, 1994).
    \66\ 40 CFR 51.1013(a)(1).
    \67\ 80 FR 2206 (January 15, 2015).
---------------------------------------------------------------------------

    The CAA requires states to submit QM reports (due 90 days after 
each milestone). Under EPA's PM2.5 implementation rule,\68\ 
a submitted QM report must include, at minimum: (1) A certification by 
the Governor (or Governor's designee) that the SIP control strategy is 
being implemented consistent with the RFP plan, as described in the 
applicable attainment plan; (2) technical support, including

[[Page 35869]]

calculations, sufficient to document completion statistics for 
appropriate milestones and to demonstrate that the QM has been 
satisfied and how the emissions reductions achieved to date compare to 
those required or scheduled to meet RFP; and (3) a discussion of 
whether the area will attain the applicable PM2.5 NAAQS by 
the projected attainment date for the area.\69\ These reports should 
include calculations and any assumptions made by the state concerning 
how RFP has been met, e.g., through quantification of emission 
reductions to date.\70\
---------------------------------------------------------------------------

    \68\ 81 FR 58010 (August 24, 2016) (codified at 40 CFR part 51, 
subpart Z).
    \69\ 40 CFR 51.1013(b).
    \70\ Id. at pp. 42016-42017.
---------------------------------------------------------------------------

2. QM Demonstration in the Allegheny County PM2.5 Plan and 
2019 QM Report
a. Allegheny County Area QM Demonstration
    The September 30, 2019 SIP revision describes ACHD's approach to 
demonstrating compliance with the QM requirements of CAA section 189, 
in which measured air quality concentrations, as well as future 
projected air quality concentrations, are used to satisfy the milestone 
reporting requirement. For the Allegheny County moderate 
PM2.5 nonattainment area, these QMs must to be reported to 
EPA for the milestone years 2019 and (if applicable) 2022. The QM 
report for year 2019 was due January 14, 2020 (i.e., 90 days after the 
first milestone date of October 15, 2019). The second report for the 
2022 milestone would be required only if the area failed to attain the 
NAAQS by its 2021 attainment date and were to be reclassified to a 
serious area. In that case, a 2022 milestone report would be due by 
January 14, 2023.
    Because the Liberty monitor was the only monitor in the Allegheny 
County area not meeting the 2012 annual PM2.5 NAAQS when EPA 
designated the area nonattainment and is currently not meeting the 
NAAQS, ACHD based its QMs on the design values for the Liberty monitor. 
For the 2019 QM demonstration in the September 20, 2019 SIP, ACHD 
calculated the expected design values at the Liberty monitor based on a 
linear regression over a 10-year timeframe (from 2011 to the 2021 
attainment year). The air quality modeling in the Allegheny County Plan 
predicts that the area will attain the 2012 annual PM2.5 
NAAQS by its December 31, 2021 attainment deadline. ACHD assumed that 
the 2019-2021 design value at the Liberty monitor would be equal to the 
level of the 2012 annual PM2.5 NAAQS, or 12 [micro]g/m\3\. 
Assuming linear progress, ACHD calculated 2019 design values for the 
Liberty monitor for both the annual and 24-hour \71\ PM2.5 
NAAQS in Table 12.
---------------------------------------------------------------------------

    \71\ The 24-hour PM2.5 NAAQS is set at 35 [micro]g/
m\3\.

                         Table 12--Liberty Monitor Air Quality Concentration Milestones
                                                  [[mu]g/m\3\]
----------------------------------------------------------------------------------------------------------------
                                     Base year    Projected year   Linear yearly  Milestone year  Milestone year
      Liberty design value            (2011)          (2021)           rate           (2019)          (2022)
----------------------------------------------------------------------------------------------------------------
Annual..........................            15.0            12.0            -0.3            12.6            12.0
24-Hour.........................              44              35            -0.9              37              35
----------------------------------------------------------------------------------------------------------------

b. Allegheny County PM2.5 Area 2019 QM Report
    PADEP submitted the Allegheny County 2019 QM Report to EPA on 
January 14, 2020 and a supplement to that report dated April 8, 2020, 
(collectively, the 2019 QM Report). The 2019 QM Report includes air 
quality monitoring data reports from AQS showing that the 2016-2018 
design values for the Liberty monitor met the milestone levels set 
forth in Table 12. In addition, the preliminary \72\ 2017-2019 design 
values at the Liberty monitor are lower than the 2016-2018 design 
values. The data is presented in Table 13.
---------------------------------------------------------------------------

    \72\ The 2019 data is fully validated and quality-assured, but 
not yet certified. The 2019 data must be certified by May 1, 2020, 
in accordance with 40 CFR 58.15.

               Table 13--Liberty Monitor Design Values for the 2012 Annual and 24 Hour PM2.5 NAAQS
                                                  [In [mu]g/m3]
----------------------------------------------------------------------------------------------------------------
                                                                       2019          2016-2018       2017-2019
                              NAAQS                                  Milestone         Final        Preliminary
----------------------------------------------------------------------------------------------------------------
Annual..........................................................            12.6            12.6            12.4
24-Hour.........................................................              37              37              35
----------------------------------------------------------------------------------------------------------------

    AQS reports submitted in the 2019 QM Report continue to show that 
all other monitors in the Allegheny County area have design values 
lower than those of the Liberty monitor. To demonstrate RFP is being 
met, as part of the 2019 QM Report ACHD verified that all controls 
listed as part of the plan's control strategy remain in place. Further, 
ACHD states that, ``RFP is being achieved for Allegheny County and 
progress should continue toward attainment, to be achieved by the 
attainment date of December 31, 2021.'' Furthermore, PADEP concurred 
with ACHD's certification that the control strategy is being 
implemented in Allegheny County consistent with the RFP plan and that 
milestones are being achieved as included in the SIP.
    In the attainment plan, ACHD developed the 2019 RFP milestone 
emissions inventory by linearly interpolating 2011 base year and 
projected 2021 attainment year emissions inventories used in its 
modeled attainment demonstration. In the 2019 QM report, ACHD presented 
updated actual emissions data for the stationary point source sector of 
the emissions inventory for 2017 and 2018, along with prior data for 
the 2011-2016 period, as listed in Table 14.

[[Page 35870]]

                  Table 14--Annual Allegheny County Point Source Emissions for the Period 2011-2018, With Yearly Linear Progress Rates
                                                                     [In tons/year]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                 Point source emissions (tons/year)                              Linear
                                                      ----------------------------------------------------------------------------------------  progress
                      Pollutant                                                                                                                  yearly
                                                          2011       2012       2013       2014       2015       2016       2017       2018       rate
--------------------------------------------------------------------------------------------------------------------------------------------------------
PM2.5................................................      2,503      1,725      1,822      2,127      1,511      1,373      1,282      1,360       -145
SO2..................................................     13,460      6,542      6,032      8,593      5,279      4,864      4,758      7,122       -716
NOX..................................................     11,128     11,881     13,073     13,715     10,278      8,560      6,337      6,925       -882
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Pursuant to 40 CFR 51.1013(b)(3), the QM report must include a 
discussion of whether the PM2.5 NAAQS will be attained by 
the projected attainment date for the area. ACHD's 2019 QM report 
contains an evaluation of ambient air quality trends, meteorology, and 
emission control strategies. In the 2019 QM Report, ACHD concludes that 
it expects the area to attain the 2012 annual PM2.5 NAAQS by 
the December 31, 2021 attainment date. The 2019 report also contains a 
trend analysis of the Liberty monitor showing a decline in monitored 
PM2.5 concentrations through 2019. An accompanying analysis 
of quarterly means for the Liberty monitor from 1999 to 2019 shows that 
the lowest quarterly means have occurred in the last four years, with 
three of the record-low quarters occurring in the last two years. The 
annual weighted PM2.5 means for the Liberty monitor are 
shown in Table 15 for the 2009-2019 period.

                                        Table 15--Liberty Monitor Annual Weighted Mean Concentrations, 2009-2019
--------------------------------------------------------------------------------------------------------------------------------------------------------
                  Metric                      2009      2010      2011      2012      2013      2014      2015      2016      2017      2018      2019
--------------------------------------------------------------------------------------------------------------------------------------------------------
Liberty weighted mean ([mu]g/m\3\)........     15.0      16.0      14.0      14.3      12.0      12.7      12.9      12.8      13.4      11.5      12.2
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: ACHD observes that concentrations are declining based on emission controls, but differences in the yearly concentrations at the Liberty monitor
  show dependence on the frequency and severity of inversions. Inversions were less frequent in 2013 and more prevalent in 2012 and 2017.

    ACHD concludes that, based on monitored data, meteorology, and 
controls, ACHD expects that the Allegheny County Area will attain the 
2012 annual PM2.5 NAAQS by or before its December 31, 2021 
attainment deadline.
3. EPA's Evaluation and Proposed Action on the QM Demonstration
    EPA has reviewed the QM demonstration contained in the September 
30, 2019 moderate area attainment plan for the Allegheny County Area, 
as well as the 2019 QM Report submitted to EPA on January 14, 2020 (as 
supplemented on April 8, 2020). This demonstration confirms that the 
monitored ambient air quality levels in the area satisfy EPA 
requirements for milestone levels.
    The 2019 QM report shows that 2016-2018 design values for the 
Liberty monitor (the only monitor that did not meet the NAAQS since the 
area was designated nonattainment) met the milestone test established 
by ACHD in the attainment plan. Preliminary 2017-2019 design values at 
the Liberty monitor presented in the 2019 QM report are lower than the 
2016-2018 design values. Finally, air quality data reports from EPA's 
AQS show that the 2016-2018 design values for the Liberty monitor met 
the QM levels set out in the attainment plan.
    EPA has reviewed the RFP data presented in the 2019 QM Report and 
finds that the Allegheny County area has made demonstrable progress in 
reducing emissions of PM2.5 and PM2.5 significant 
precursors since EPA designated the area nonattainment for the 
PM2.5 NAAQS in 2015. Comparing stationary source emissions 
in the 2019 QM Report to those predicted in the attainment plan for 
2019, EPA finds that the most recent emissions inventory is well below 
the RFP milestone. Therefore, EPA finds that emissions reductions are 
meeting RFP through the 2019 period.
    EPA determined in an April 22, 2020 letter to PADEP that (based on 
its review of information contained in the plan and additional 
information provided in the 2019 QM report) ACHD has adequately 
demonstrated that the 2019 QMs for a moderate area plan have been met. 
The 2019 QM Report contains each of the required components to meet the 
QM requirements of CAA section 189(c)(2) and 40 CFR 51.1013(b).
    For further information on EPA's review of the QM methodology and 
the 2019 QM Report, please refer to our TSD on the 2019 QM Report 
prepared in support of this action, which is available in the 
docket.\73\
---------------------------------------------------------------------------

    \73\ By letter dated April 22, 2020, from EPA Regional 
Administrator Servidio to PADEP Secretary McDonnell, EPA determined 
that ACHD adequately demonstrated that the 2019 QMs provided in the 
attainment plan have been met.
---------------------------------------------------------------------------

H. Contingency Measures

1. Requirements for Contingency Measures
    In accordance with section 172(c)(9) of the CAA, the 
PM2.5 SIP Requirements Rule requires that attainment 
demonstrations for moderate PM2.5 nonattainment areas 
include contingency measures.\74\ Contingency measures are additional 
control measures to be implemented in the event that EPA determines 
that an area failed to meet RFP requirements (including associated QMs) 
or failed to attain the PM2.5 primary standard by the 
applicable attainment date.
---------------------------------------------------------------------------

    \74\ See 40 CFR 51.1014 and 81 FR 58010 at p. 58066, August 24, 
2016.
---------------------------------------------------------------------------

    In order for contingency measures to be approvable 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 
SIP Requirements 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 Administrator of the 
nonattainment area's failure to meet RFP, failure to meet any QM, 
failure to submit a QM

[[Page 35871]]

report or failure to attain the standard by the applicable 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; \75\ (3) 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; and (4) the contingency measures should 
provide for emissions reductions approximately equivalent to one year's 
worth of reductions needed for RFP.
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    \75\ According to the PM2.5 SIP Requirements Rule, 
states must show that the contingency measures can be implemented 
with minimal further action and no additional rulemaking actions, 
such as public hearings or legislative review. EPA generally expects 
all actions needed to effect full implementation of the contingency 
measures to occur within 60 days after EPA notifies the state of the 
area's failure to meet an RFP requirement or attain the NAAQS.
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2. Contingency Measures in the Allegheny County PM2.5 Plan
    Section 8 (Contingency Measures) of the Allegheny County 
PM2.5 Plan identifies as contingency measures two actions 
for the mitigation of primary PM2.5 from the U.S. Steel 
Clairton Plant that are to be implemented as the result of a July 27, 
2019 settlement agreement and order (#19060) between ACHD and U.S. 
Steel. These actions, which include the installation of a cover and/or 
air curtain and the installation of a new combustion (under-firing) 
stack at the U.S. Steel Clairton Works, are to be implemented by May 1, 
2020 and November 1, 2021, respectively. ACHD predicts that, based on 
additional modeling, these two actions will lead to a reduction in 
absolute annual modeled impacts of 0.10 [micro]g/m\3\ at the Liberty 
monitor (AQS Site ID 42-003-0064) and that the resulting 2022 
PM2.5 annual design value will be lowered by 0.07 [micro]g/
m\3\. ACHD did not include these expected reductions in 
PM2.5 emissions at the U.S. Steel Clairton facility in the 
emissions inventory portion of the Allegheny County PM2.5 
Plan.
3. EPA's Evaluation and Proposed Action on Contingency Measures
    EPA does not consider the two actions contained in the July 27, 
2019 settlement agreement and order to be suitable contingency 
measures. According to the PM2.5 SIP Requirements Rule, 
``Contingency measures must be fully adopted rules or control measures 
that are ready to be implemented quickly upon a determination by the 
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 applicable attainment date.'' 81 FR 58010 at 58066, 
August 24, 2016.
    Contingency measures are to be implemented only if they are 
``triggered'' in the event of the Administrator's determination that 
the Area failed to meet RFP requirements (including associated QMs) or 
failed to attain the PM2.5 NAAQS by the applicable 
attainment date. The installation of the air curtain and stack at the 
U.S. Steel Clairton Coke Works will be implemented regardless of 
whether the Allegheny County Area fails to meet the RFP requirements or 
attain the PM2.5 NAAQS by the attainment date. Measures that 
will be implemented regardless of being triggered are not considered 
appropriate to use as contingency measures. Therefore, EPA cannot fully 
approve Section 8 (Contingency Measures) of the Allegheny County 
PM2.5 Plan because the two measures in the settlement 
agreement and order do not meet the contingency measures requirements 
of the PM2.5 SIP Requirements Rule and 40 CFR 51.1014.
    EPA informed ACHD of this concern prior to the publication of 
ACHD's proposed plan. In response, PADEP submitted a letter to EPA 
dated April 20, 2020, concurring with ACHD's commitment to adopt 
specific contingency measures and an attainment year MVEB in accordance 
with EPA's proposed conditional approval of those elements of the 
September 30, 2019 SIP revision. In its April 7, 2020 letter to PADEP, 
ACHD commits to adopt measures from the following list that will 
provide for a reduction of 34 tons per year of direct PM2.5 
emissions countywide (or an equivalent reduction in combination of 
PM2.5 precursors), or 9.4 tons per year of PM2.5 
in the immediate vicinity of the Liberty monitor. Measures include 
implementation of the following at the U.S. Steel Clairton Coke Works: 
(1) Increased residence times for the Pushing Emission Control (PEC) 
hoods during the pushing process (as described in ACHD Article XXI 
Sec.  2105.21.e.6) for batteries 1-3, 13-15, and 19-20; (2) increased 
baffle washing for the Quench Towers; (3) road and parking lot paving; 
and (4) improvements to the PEC baghouses. Additional potential 
measures include road paving on a portion of unpaved public county 
roads; adoption of an ordinance to restrict sale and use of heavy fuel 
oil and/or waste derived liquid fuel (WDLF) in Allegheny County; 
expansion of an existing wood stove change out program; repowering or 
replacement of tugboats and/or locomotives utilized by the U.S. Steel 
Mon Valley Works facilities; and replacement of locomotives at the 
McKeesport switchyard with new, cleaner equipment that meets the most 
recent standards.
    After adopting measures, PADEP will submit a SIP revision, on 
behalf of ACHD, containing the adopted measures and meeting the 
requirements of the PM2.5 SIP Requirements Rule and 40 CFR 
51.1014. In addition, the contingency measures section will include a 
description of the trigger mechanisms and schedules for implementation 
of the contingency measures, as required by section 51.1014. ACHD and 
PADEP have committed to submit the contingency measures SIP revision to 
EPA as expeditiously as possible, but no later than one year after the 
effective date of EPA's final notice of conditional approval of the 
September 30, 2019 SIP revision.
    However, as stated previously, the expected emission reductions 
from the installation of the air curtain and stack at the U.S. Steel 
Clairton Coke Works were not included in the emissions inventory 
included in the Allegheny County PM2.5 Plan. Therefore, it 
is expected that these actions will provide for additional emission 
reductions beyond those projected in the Allegheny County 
PM2.5 Plan. Thus, the installation of the air curtain and 
stack at Clairton provide additional assurance that the 2012 
PM2.5 NAAQS will be attained in the Allegheny County 
nonattainment area by the attainment date.
    Therefore, EPA concludes that the installation of the air curtain 
and stack at the U.S. Steel Clairton Coke Works are better suited as 
additional control measures for attainment of the PM2.5 
NAAQS in the Allegheny County Area. EPA is proposing to approve the 
installation of the air curtain and stack at the Clairton Coke Works 
contained in the settlement agreement and order (#19060) referenced in 
the Allegheny County PM2.5 Plan as additional control 
measures for the attainment of the PM2.5 NAAQS in the 
Allegheny County nonattainment area.
    EPA is also proposing to conditionally approve the contingency 
measures portion of the Allegheny County PM2.5 Plan. As 
discussed previously, ACHD commits to adopt contingency measures and 
submit, through PADEP, a supplemental SIP revision consisting of

[[Page 35872]]

a revised contingency measures section of the Allegheny County 
PM2.5 Plan that includes adopted contingency measures from 
the April 20, 2020 letter and meets the requirements of the 
PM2.5 SIP Requirements Rule and 40 CFR 51.1014. EPA's 
approval of the contingency measures portion of the Allegheny County 
PM2.5 Plan is contingent on ACHD's adoption of approvable 
contingency measures and submittal of a SIP revision that meets the 
contingency measures requirements of the PM2.5 SIP 
Requirements Rule and 40 CFR 51.1014.

I. Transportation Conformity and MVEBs

1. Requirements for Motor Vehicle Emission Budgets
    Section 176(c) of the CAA requires Federal actions in nonattainment 
and maintenance areas to conform to the SIP's goals of eliminating or 
reducing the severity and number of violations of the NAAQS and 
achieving expeditious attainment of the standards. Conformity to the 
SIP's goals means that such actions will not: (1) Cause or contribute 
to violations of a NAAQS, (2) worsen the severity of an existing 
violation, or (3) delay timely attainment of any NAAQS or any interim 
milestone. Section 176(c)(4) of the CAA requires that transportation 
plans, programs, and projects which are funded or approved under title 
23 of the United States Code must be determined to conform with state 
or Federal air implementation plans. A MVEB is that portion of the 
total allowable emissions allocated to highway and transit vehicle use 
that are defined in the implementation plan for a control strategy SIP 
revision.\76\
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    \76\ EPA's Transportation Conformity Rule at 40 CFR 93.101 
defines a ``control strategy SIP revision'' as a ``plan which 
contains specific strategies for controlling the emissions and 
reducing ambient levels of pollutants in order to satisfy CAA 
requirements of RFP and attainment.''
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    Actions involving Federal Highway Administration (FHWA) or Federal 
Transit Administration (FTA) funding or approval are subject to EPA's 
transportation conformity rule, codified at 40 CFR part 93, subpart A. 
Under this rule, the area metropolitan planning organization (MPO) 
coordinates with state and local air quality and transportation 
agencies, EPA, FHWA, and FTA to demonstrate that an area's regional 
transportation plans and transportation improvement programs conform to 
the applicable SIP.\77\ This conformity demonstration is typically done 
by showing that estimated emissions from existing and planned highway 
and transit systems are less than or equal to the MVEB contained in all 
control strategy SIPs.\78\ An attainment, maintenance, or RFP plan SIP 
should include budgets for the attainment year, each required RFP 
milestone year, and the last year of the maintenance plan, as 
appropriate. Budgets are generally established for specific years and 
specific pollutants or precursors and must reflect all of the motor 
vehicle control measures contained in the applicable plan.\79\ For 
MVEBs to be approvable, they must meet, at a minimum, EPA's conformity 
adequacy criteria at 40 CFR 93.118(e)(4).
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    \77\ The Southwestern Pennsylvania Commission (SPC) is the 
official Metropolitan Planning Organization (MPO) for the 10-county 
Southwestern Pennsylvania Region, which includes the City of 
Pittsburgh and surrounding counties--including Allegheny County. SPC 
is responsible for planning and prioritizing the use of all state 
and Federal transportation funds allocated to the region.
    \78\ See 40 CFR 93.118(a).
    \79\ See 40 CFR 93.118(e)(4)(v).
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    All PM2.5 control strategy SIP MVEBs must include direct 
PM2.5 motor vehicle emissions (including emissions from 
tailpipes, brake wear, and tire wear).\80\ Precursors of 
PM2.5 must also be included in the MVEB, in certain 
circumstances. NOX is included in PM2.5 
nonattainment area MVEBs, unless both EPA Regional Administrator and 
the director of the state air agency made a finding that 
transportation-related emissions of NOX are insignificant to 
PM2.5 nonattainment in the area.\81\ Other potential 
PM2.5 precursor emissions, such as VOC, SO2 and 
NH3 are only included in PM2.5 area MVEBs if EPA 
has determined them to be significant in the area.\82\
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    \80\ Per 40 CFR 93.102(b)(3), direct PM2.5 emissions 
from re-entrained road dust need only be included in the MVEB if EPA 
Regional Administrator or the director of the state air agency has 
made a finding that re-entrained road dust emissions within the area 
are a significant contributor to the PM2.5 nonattainment 
problem or if the applicable SIP includes re-entrained road dust in 
the budget as part of the RFP, attainment, or maintenance strategy.
    \81\ See 40 CFR 93.102(b)(2)(iv).
    \82\ See 40 CFR 93.102(b)(2)(v).
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    In order for a pollutant or precursor to be considered an 
insignificant contributor, the control strategy SIP must demonstrate 
that it is unreasonable to expect that such an area would experience 
enough motor vehicle emissions growth in that pollutant/precursor for a 
NAAQS violation to occur. Insignificance determinations are based on 
factors such as air quality, SIP motor vehicle control measures, trends 
and projections of motor vehicle emissions, and the percentage of the 
total SIP inventory that is comprised of motor vehicle emissions.\83\ 
ACHD did not submit and is not seeking an insignificance determination 
for NOX.
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    \83\ See 40 CFR 93.109(f) for criteria for insignificance 
determinations. EPA's rationale for allowing insignificance 
determinations is described in the July 1, 2004 revision to the 
Transportation Conformity Rule at 69 FR 40004.
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2. Motor Vehicle Emission Budgets in the Allegheny County 
PM2.5 Attainment Plan
    The Commonwealth's September 30, 2019 SIP revision lacks a MVEB 
specific to the 2012 PM2.5 attainment plan for the 
attainment year of 2021. Instead, the SIP revision refers to existing 
MVEBs for the 1997 and 2006 PM2.5 NAAQS established by EPA's 
approval of the maintenance plan for the Pittsburgh-Beaver Valley area 
for the 1997 and 2006 PM2.5 NAAQS.\84\ This maintenance plan 
included MVEBs for 2017 and 2025, for the larger Pittsburgh-Beaver 
Valley area (comprised of part of Allegheny County (excluding the 
Liberty-Clairton area), Beaver, Butler, Washington, and Westmoreland 
Counties, as well as portions of Armstrong County, Greene, and Lawrence 
Counties).
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    \84\ See 80 FR 59624, October 2, 2015.
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    Neither EPA nor the Commonwealth's air director have made 
transportation-related insignificance findings for NOX, and 
EPA has not determined that transportation-related emissions of 
SO2, VOC, or NH3 are significant in Allegheny 
County. Therefore, there is no established MVEB for SO2, 
VOC, and NH3 in any approved control strategy SIP for the 
Allegheny County PM2.5 area. ACHD has determined VOC and 
NH3 to be insignificant as precursors to PM2.5 
nonattainment as part of the attainment plan.\85\ Therefore, 
transportation conformity requirements are applicable only to 
PM2.5 and NOX for the Allegheny County Area.
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    \85\ See Section 5 (Modeling Demonstration) of the September 30, 
2019 SIP revision.
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3. EPA's Evaluation and Proposed Action on the Intended MVEB
    EPA is proposing to find that ACHD's plan failed to establish a 
MVEB for the 2012 PM2.5 attainment plan control strategy SIP 
for the 2021 attainment year, as required for emission budgets by 40 
CFR 93.118. A budget is required for each NAAQS for each control 
strategy SIP, so that conformity can be demonstrated via a ``budget'' 
test for that particular area and control strategy milestone.\86\
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    \86\ See 40 CFR 93.118(a), (b), and (e).
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    Because the Allegheny County PM2.5 Plan fails to 
establish an attainment year 2021 MVEB for PM2.5 and 
NOX, EPA cannot approve this element of the plan at this 
time. However, PADEP subsequently submitted a letter to EPA

[[Page 35873]]

dated April 20, 2020, committing to remedy this deficiency by 
establishing a MVEB in accordance with EPA's Transportation Conformity 
Rule requirements by September 30, 2020. Because ACHD and the MPO have 
identified the actual MVEB to be established as part of their April 20, 
2020 commitment, EPA is including the MVEB in this action for 
informational purposes only. The MVEB must still be adopted by 
Allegheny County through its normal SIP development process, which 
includes EPA's related requirements to undergo public comment. The 
April 20, 2020 commitment letter clearly identifies the MVEB that ACHD 
and the MPO intend to propose for the 2021 attainment year, as shown in 
Table 16.

Table 16--Allegheny County, PA 2012 PM2.5 NAAQS Attainment Year Intended
             MVEB for Direct PM2.5 and Nitrogen Oxides (NOx)
------------------------------------------------------------------------
                                        Direct PM2.5 on-
                                        road  emissions    NOX on-road
  Motor vehicle emissions budget year       (tons per       emissions
                                             year)       (tons per year)
 
------------------------------------------------------------------------
2021..................................             266            5,708
------------------------------------------------------------------------

    Remedy of this MVEB-related deficiency of the September 30, 2019 
SIP revision entails: Identifying the attainment year MVEB in a 
supplemental SIP revision; conducting a public comment process on the 
identified MVEB (per the requirements of EPA conformity rule at 40 CFR 
93.118(e)); and formally submitting the established MVEB to EPA as a 
supplemental revision to the attainment plan SIP revision. EPA is 
proposing to conditionally approve the MVEB element of the SIP 
submittal until ACHD remedies the deficiency with the 2021 MVEB.

IV. Summary of Proposed Action and Request for Public Comment

    Under CAA section 110(k)(3), EPA is proposing to approve 
Pennsylvania's September 30, 2019 SIP revision 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 and MVEB elements of the plan, which EPA proposes 
to conditionally approve.
    Specifically, EPA is proposing to approve the following elements of 
the Allegheny County PM2.5 Plan:
    (1) The 2011 base year emissions inventory as meeting the 
requirements of CAA section 172(c)(3);
    (2) The RACM/RACT demonstration as meeting the requirements of CAA 
sections 172(c)(1) and 189(a)(1)(C);
    (3) The attainment demonstration as meeting the requirements of CAA 
sections 172(c)(1) and 189(a)(1)(B);
    (4) The RFP demonstration as meeting the requirements of CAA 
section 172(c)(2); and
    (5) The QM demonstration as meeting the requirements of CAA section 
189(c).
    EPA also proposes to conditionally approve the MVEB and contingency 
measures elements of the Allegheny County PM2.5 Plan. Under 
section 110(k)(4) of the CAA, EPA may conditionally approve a plan 
based on a commitment from the Commonwealth to adopt specific 
enforceable measures within a date certain no more than one year from 
the date of final conditional approval. If Pennsylvania fails to meet 
its commitments by the commitment date, the approval is treated as a 
disapproval.
    Specifically, EPA is proposing to conditionally approve the 
following elements of the Allegheny County PM2.5 Plan:
    (1) The attainment year 2021 MVEB, as the plan failed to identify 
the MVEB, as required by CAA section 176(c) and 40 CFR part 93, subpart 
A. However, Pennsylvania submitted a commitment letter to EPA on April 
20, 2020 transmitting ACHD's April 7, 2020 letter that identifies their 
proposed MVEB for 2021 and commits to finalize a 2021 budget (following 
public notice and comment) and to submit it to EPA by September 30, 
2020 as a revision to this SIP submission and;
    (2) The contingency measures in Section 8 (Contingency Measures) of 
the Allegheny County PM2.5 Plan, as the submitted 
contingency measures do not satisfy the requirements of the CAA section 
172(c)(9) or the PM2.5 SIP Requirements Rule at 40 CFR 
51.1014. Upon receipt of that subsequent SIP submission, EPA will take 
separate action to determine whether those adopted contingency measures 
satisfy relevant EPA requirements for contingency measures.
    EPA is soliciting public comments on the issues discussed in this 
document. The deadline and instructions for submission of comments are 
provided in the DATES and ADDRESSES sections of this action. EPA will 
consider any received comments prior to finalizing this proposed 
action.

V. Statutory and Executive Order Reviews

    Under the CAA, the Administrator is required to approve a SIP 
submission that complies with the provisions of the CAA and applicable 
Federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in 
reviewing SIP submissions, EPA's role is to approve state choices, 
provided that they meet the criteria of the CAA.
    Accordingly, this action merely approves state law as meeting 
Federal requirements and does not impose additional requirements beyond 
those imposed by state law. For that reason, this proposed action:
     Is not a ``significant regulatory action'' subject to 
review by the Office of Management and Budget under Executive Orders 
12866 (58 FR 51735, October 4, 1993) and 13563 (76 FR 3821, January 21, 
2011);
     Is not an Executive Order 13771 (82 FR 9339, February 2, 
2017) regulatory action because SIP approvals are exempted under 
Executive Order 12866.
     Does not impose an information collection burden under the 
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
     Is certified as not having a significant economic impact 
on a substantial number of small entities under the Regulatory 
Flexibility Act (5 U.S.C. 601 et seq.);
     Does not contain any unfunded mandate or significantly or 
uniquely affect small governments, as described in the Unfunded 
Mandates Reform Act of 1995 (Pub. L. 104-4);
     Does not have Federalism implications as specified in 
Executive Order 13132 (64 FR 43255, August 10, 1999);
     Is not an economically significant regulatory action based 
on health or safety risks subject to Executive Order 13045 (62 FR 
19885, April 23, 1997);

[[Page 35874]]

     Is not a significant regulatory action subject to 
Executive Order 13211 (66 FR 28355, May 22, 2001);
     Is not subject to requirements of Section 12(d) of the 
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 
note) because application of those requirements would be inconsistent 
with the CAA; and
     Does not provide EPA with the discretionary authority to 
address, as appropriate, disproportionate human health or environmental 
effects, using practicable and legally permissible methods, under 
Executive Order 12898 (59 FR 7629, February 16, 1994).
    In addition, this proposed rule proposing to approve the Allegheny 
County PM2.5 Plan (with the exception of the contingency 
measures and MVEB elements, which EPA is proposing to conditionally 
approve) 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 Commonwealth, and 
EPA notes that it will not impose substantial direct costs on tribal 
governments or preempt tribal law.

List of Subjects in 40 CFR Part 52

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

    Dated: June 4, 2020
Cosmo Servidio,
Regional Administrator, Region III.
[FR Doc. 2020-12499 Filed 6-11-20; 8:45 am]
BILLING CODE 6560-50-P