Document ID: EPA-R03-OAR-2023-0219-0001
Agency: epa
Document Type: Proposed Rule
Title: Air Quality State Implementation Plans; Approvals and Promulgations: Pennsylvania; Liberty Borough Area Second 10-Year PM10 Limited Maintenance Plan
Posted Date: 2023-07-12T04:00Z

[Federal Register Volume 88, Number 132 (Wednesday, July 12, 2023)]
[Proposed Rules]
[Pages 44237-44244]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-14645]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R03-OAR-2023-0219; FRL-8813-01-R3]

Air Plan Approval; Pennsylvania; Liberty Borough Area Second 10-
Year PM10 Limited Maintenance Plan

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to 
approve the Liberty Borough area second 10-year maintenance plan 
submitted by the Commonwealth of Pennsylvania Department of 
Environmental Protection (PADEP or Commonwealth) on behalf of the 
Allegheny County Health Department (ACHD). This plan addresses the 
second 10-year maintenance period after redesignation for particulate 
matter with an aerodynamic diameter less than or equal to a nominal 10 
micrometers (PM10). A limited maintenance plan (LMP) is used 
to meet the Clean Air Act (CAA or the Act) requirements for formerly 
designated nonattainment areas that meet certain qualification 
criteria. EPA is proposing to determine that ACHD's second maintenance 
plan meets applicable CAA requirements. The plan relies upon control 
measures contained in the attainment plan and the first 10-year 
maintenance plan and the determination that the Liberty Borough area 
currently monitors PM10 levels well below the 
PM10 national ambient air quality standards (NAAQS or 
standard).

DATES: Written comments must be received on or before August 11, 2023.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R03-
OAR-2023-0219 at www.regulations.gov, or via email to 
[email protected]. For comments submitted at Regulations.gov, follow 
the online instructions for submitting comments. Once submitted, 
comments cannot be edited or removed from Regulations.gov. For either 
manner of submission, EPA may publish any comment received to its 
public docket. Do not submit electronically any information you 
consider to be confidential business information (CBI) or other 
information whose disclosure is restricted by statute. Multimedia 
submissions (audio, video, etc.) must be accompanied by a written 
comment. The written comment is considered the official comment and 
should include discussion of all points you wish to make. EPA will 
generally not consider comments or comment contents located outside of 
the primary submission (i.e., on the web, cloud, or other file sharing 
system). For additional submission methods, please contact the person 
identified in the FOR FURTHER INFORMATION CONTACT section. For the full 
EPA public comment policy, information about CBI or multimedia 
submissions, and general guidance on making effective comments, please 
visit www.epa.gov/dockets/commenting-epa-dockets.

FOR FURTHER INFORMATION CONTACT: Ellen Schmitt, Planning & 
Implementation Branch (3AD30), Air & Radiation Division, U.S. 
Environmental Protection Agency, Region III, Four Penn Center, 1600 
John F. Kennedy Boulevard, Philadelphia, Pennsylvania

[[Page 44238]]

19103. The telephone number is (215) 814-5787. Ms. Schmitt can also be 
reached via electronic mail at [email protected].

SUPPLEMENTARY INFORMATION: On July 21, 2021, EPA received from PADEP, 
on behalf of ACHD, a revision to the Commonwealth's state 
implementation plan (SIP) for the Liberty Borough area.\1\ The Liberty 
Borough area is comprised of the Boroughs of Liberty, Lincoln, Port 
Vue, and Glassport and the City of Clairton in Allegheny County, 
Pennsylvania. This action is expected to ensure that the Commonwealth 
of Pennsylvania meets CAA requirements. There is no information on the 
record indicating that this action is expected to have 
disproportionately high or adverse human health or environmental 
effects on a particular group of people.
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    \1\ In its SIP submission, ACHD refers to the area at issue as 
the Liberty-Clairton area. In this proposed rulemaking, EPA refers 
to this area as the Liberty Borough area to distinguish it from the 
Liberty-Clairton fine particulate matter (PM2.5) area and 
to be consistent with what the Agency called the area in our 
approval of the first 10-year maintenance plan and attainment plan. 
See 63 FR 47343 (September 8, 1998) and 68 FR 53515 (September 11, 
2003).
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I. Background

    On July 1, 1987, EPA promulgated two primary standards for 
PM10: A 24-hour standard of 150 micrograms per cubic meter 
([micro]g/m\3\) and an annual standard of 50 [micro]g/m\3\. EPA also 
promulgated secondary PM10 standards that were identical to 
the primary standards.\2\ Effective December 18, 2006, EPA revoked the 
annual PM10 standards but retained the 24-hour standards.\3\ 
In this document, references to the PM10 NAAQS or 
PM10 standard refer to the 24-hour average standard of 150 
[micro]g/m\3\, unless otherwise noted. Because they are identical, we 
refer to the primary and secondary 24-hour standards using the single 
term, NAAQS.
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    \2\ 52 FR 24634 (July 1, 1987).
    \3\ 71 FR 61144 (October 17, 2006).
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    On November 15, 1990, amendments to the CAA were enacted, and 
pursuant to section 107(d)(4)(B) of the Act, the Liberty Borough area 
was designated nonattainment by operation of law.\4\ To support an 
attainment demonstration, ACHD and the Commonwealth submitted to EPA 
several SIP revisions that included permanent and enforceable pollution 
controls in the Liberty Borough area, resulting in reduced ambient air 
quality concentrations.\5\
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    \4\ On August 7, 1987 (56 FR 56694), EPA designated portions of 
Allegheny County as a PM10 nonattainment area due to 
measured violations of the 24-hour PM10 NAAQS (52 FR 
29383). The publication announcing the nonattainment designation 
upon enactment of the 1990 CAA Amendments was published on March 15, 
1991 (56 FR 11101). On November 6, 1991, the area was subsequently 
classified as moderate nonattainment under sections 107(d)(4)(B) and 
188(a) of the CAA.
    \5\ 61 FR 29664 (June 12, 1996). 63 FR 47434 (September 8, 
1998). 63 FR 32126 (June 12, 1998).
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    On September 8, 1998 (63 FR 47493), EPA finalized a determination 
that the Liberty Borough area had attained the PM10 NAAQS 
based on 1995-1997 air quality data. In that same action, EPA approved 
the attainment demonstration and contingency measures for the area, 
concluding that the Liberty Borough area attainment plan was sufficient 
to help the Liberty Borough area attain and maintain the NAAQS.
    On October 28, 2002, the Commonwealth, on behalf of ACHD, submitted 
to EPA a redesignation request and maintenance plan for the Liberty 
Borough area. EPA redesignated the Liberty Borough area from 
nonattainment to attainment for the PM10 NAAQS and approved 
the maintenance plan for this first 10-year maintenance period on 
September 11, 2003 (68 FR 53515).\6\ The first 10-year maintenance 
period ended in 2013 and the second 10-year maintenance plan, which is 
the subject of this proposed rulemaking, extends through 2023.
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    \6\ Effective on October 14, 2003.
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    Since the redesignation request in 2002, ACHD has been operating an 
ambient PM10 monitoring network with monitors at four sites 
within the Liberty Borough area, in accordance with 40 Code of Federal 
Register (CFR) part 58. The Liberty Borough area PM10 
monitors are the Lincoln monitor (air quality system (AQS) site ID 42-
003-7003), the Liberty monitor (AQS site ID 42-003-0064),\7\ the 
Glassport monitor (AQS site ID 42-003-3006), and the Clairton monitor 
(AQS site ID 42-003-3007). The Lincoln, Liberty, and Glassport monitors 
are Federal Equivalent Method (FEM) continuous monitors for 
PM10. Liberty is also considered a multi-pollutant site with 
monitors for other air pollutants at the same site, including a Federal 
Reference Method (FRM) filter-based monitor for PM10. The 
Clairton site has an FRM filter-based monitor.
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    \7\ The Liberty monitor site has two monitors, one is filter-
based and the other is continuous.
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II. Limited Maintenance Plan Option for PM10 Areas

A. Requirements for the Limited Maintenance Plan Option

    Section 175A of the CAA sets forth the elements for maintenance 
plans. Under section 175A, a state or locality must submit a 
maintenance plan to demonstrate continued attainment of the applicable 
NAAQS for at least ten years after an area is redesignated to 
attainment. Eight years into the first maintenance period, the 
applicable state or local agency must submit a second maintenance plan 
demonstrating that the area will continue to attain for the following 
10-year period. On September 4, 1992, EPA issued guidance on the 
content of a maintenance plan (Memorandum from John Calcagni, Director, 
Air Quality Management Division, entitled ``Procedures for Processing 
Requests to Redesignate Areas to Attainment,'' (Calcagni Memo)).\8\ The 
Calcagni Memo states that a maintenance plan should include the 
following provisions: (1) an attainment emissions inventory; (2) a 
maintenance demonstration showing maintenance for 10 years; (3) a 
commitment to maintain the existing monitoring network; (4) 
verification of continued attainment; and (5) a contingency plan to 
prevent or correct future violations of the NAAQS.
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    \8\ The Memorandum from the EPA's Air Quality Management 
Division Director to EPA Regional Air Directors entitled 
``Procedures for Processing Requests to Redesignate Areas to 
Attainment,'' dated September 4, 1992 (Calcagni Memo) can be found 
at www.epa.gov/sites/default/files/2016-03/documents/calcagni_memo_-_procedures_for_processing_requests_to_redesignate_areas_to_attainment_090492.pdf.
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    On August 9, 2001, EPA issued guidance on streamlined maintenance 
plan provisions for certain moderate PM10 nonattainment 
areas (see Memorandum from Lydia Wegman, Director, Air Quality 
Standards and Strategies Division, entitled ``Limited Maintenance Plan 
Option for Moderate PM10 Nonattainment Areas'' (LMP Option 
Memo).\9\ The LMP Option Memo contains a statistical demonstration air 
agencies can use to show that areas are meeting certain air quality 
criteria with a high degree of probability, and therefore will maintain 
the standard ten years into the future. By providing this statistical 
demonstration, EPA can consider the maintenance demonstration 
requirement of the CAA to be satisfied for the moderate PM10 
nonattainment area meeting these air quality criteria. If the tests 
described in section IV of the LMP Option Memo are met, EPA will treat 
that as a demonstration that the area will maintain the NAAQS. 
Consequently, the state or local agency is not required to submit in 
its SIP certain future year emission inventories for these areas nor 
some of the standard transportation conformity analyses.
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    \9\ The ``Limited Maintenance Plan Option for Moderate 
PM10 Nonattainment Areas'' can be found at www3.epa.gov/ttn/naaqs/aqmguide/collection/cp2/20010809_wegman_lmp_moderate_pm10_naa.pdf and in the docket for this 
proposed rulemaking.

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[[Page 44239]]

    To qualify for the LMP option, the applicable state or local agency 
must demonstrate that the area meets the following criteria. First, the 
area should have attained the PM10 NAAQS. Second, the most 
recent five years of air quality data at all monitors in the area, 
referred to as the 24-hour average design value, should be at or below 
98 [micro]g/m\3\. Third, the applicable state or local agency should 
expect only limited growth in on-road motor vehicle PM10 
emissions and should have passed a motor vehicle regional emissions 
analysis test. Lastly, the LMP Option Memo identifies core provisions 
that must be included in all limited maintenance plans. These 
provisions include an attainment year emissions inventory, assurance of 
continued operation of an EPA-approved air quality monitoring network, 
and contingency provisions.

B. Conformity Under the Limited Maintenance Option

    The transportation conformity rule and the general conformity rule 
(set forth in 40 CFR parts 51 and 93) apply to nonattainment areas and 
maintenance areas covered by an approved maintenance plan. Under either 
conformity rule, an acceptable method of demonstrating that a Federal 
action conforms to the applicable SIP is to demonstrate that expected 
emissions from the planned action are consistent with the on-road 
mobile emissions budget for the area.
    While EPA's LMP option does not exempt an area from the need to 
affirm conformity, it explains that the area may demonstrate conformity 
without conforming to an emissions budget. Under the LMP option, 
emissions budgets are treated as essentially not constraining for the 
length of the maintenance period because it is unreasonable to expect 
that the qualifying areas would experience so much on-road mobile 
source emissions growth in that period that a violation of the 
PM10 NAAQS would result. For transportation conformity 
purposes, EPA would conclude that emissions in these areas need not be 
capped for the maintenance period and therefore a regional emissions 
analysis would not be required.
    While areas with maintenance plans approved under the LMP option 
are not subject to the budget test (see 40 CFR 93.109(e)), those areas 
remain subject to the other transportation conformity requirements of 
40 CFR part 93, subpart A. Thus, the metropolitan planning organization 
(MPO) in the area or the state must document and ensure that:
    a. Transportation plans and projects provide for timely 
implementation of SIP transportation control measures (TCMs) in 
accordance with 40 CFR 93.113;
    b. Transportation plans and projects comply with the fiscal 
constraint element as set forth in 40 CFR 93.108;
    c. The MPO's interagency consultation procedures meet the 
applicable requirements of 40 CFR 93.105;
    d. Conformity of transportation plans is determined no less 
frequently than every four years, and conformity of plan amendments and 
transportation projects is demonstrated in accordance with the timing 
requirements specified in 40 CFR 93.104;
    e. The latest planning assumptions and emissions model are used as 
set forth in 40 CFR 93.110 and 40 CFR 93.111;
    f. Projects do not cause or contribute to any new localized carbon 
monoxide or particulate matter violations, in accordance with 
procedures specified in 40 CFR 93.123; and
    g. Project sponsors and/or operators provide written commitments as 
specified in 40 CFR 93.125.
    If EPA approves the second 10-year LMP, the Liberty Borough area 
will continue to be exempt from performing a regional emissions 
analysis, but must meet project-level conformity analyses as well as 
the transportation conformity criteria described previously.

III. Review of the SIP Submittal

A. Qualifying for the Limited Maintenance Plan Option

    As discussed in Section II.A. of this preamble, the LMP Option Memo 
outlines the requirements for an area to qualify for an LMP. First, the 
area should be attaining the PM10 NAAQS. The PM10 
NAAQS is attained when the expected number of days per calendar year 
with a 24-hour average concentration above 150 [micro]g/m\3\ is equal 
to or less than one (40 CFR 50.6). EPA has evaluated recent ambient air 
quality data and the Liberty Borough area continues to attain the 24-
hour standard for PM10, not exceeding the standard on any 
day at any of the four monitoring sites for over ten years (2011-
2021).\10\ Table 1, in this document, shows the highest and second 
highest 24-hour PM10 concentrations measured at the five 
Liberty Borough area monitors from 2011-2021, all of which are 
consistently below the NAAQS of 150 [micro]g/m\3\.
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    \10\ There are four monitoring sites within the Liberty Borough 
area, three sites with one monitor each and one site with two 
monitors.

 Table 1--Highest/Second Highest Annual 24-Hour PM10 Concentrations ([micro]g/m\3\) at the Clairton, Glassport,
                                   Liberty, and Lincoln Monitors, 2011-2021\a\
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                                                     Glassport
              Year                Clairton (FRM)       (FEM)       Liberty (FEM)   Liberty (FRM)   Lincoln (FEM)
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2011............................           37/37           83/74           70/70           93/72          115/94
2012............................           34/32           91/72           71/66           73/72           84/75
2013............................           25/25           60/57           49/48           59/47           76/65
2014............................           39/32           64/52           63/50           64/55           70/56
2015............................           41/34           91/56           78/61           64/59           85/79
2016............................           46/27           68/49           65/63           70/62           93/84
2017............................           29/28           68/68           87/58          106/61          108/93
2018............................           27/21           57/48           54/53           50/50           83/67
2019............................           26/22          105/86           74/68           72/71           75/57
2020............................           31/24           46/45           49/48           39/38           73/71
2021............................           24/24           58/54           57/54        Shutdown        Shutdown
                                                                                        11/11/20        12/31/20
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\a\ Data provided by EPA's Air Quality System (AQS).

[[Page 44240]]

    The second criteria for the PM10 LMP option is that the 
24-hour average design value for the most recent five years of 
monitoring data must be at or below 98 [micro]g/m\3\.\11\ ACHD 
calculated the design values for the Liberty Borough area as the 3-year 
averages of the yearly second-highest 24-hour PM10 
concentration at each monitoring site, which was provided through 2020 
in Table A-10 in its July 2021 LMP SIP submittal.12 13 EPA 
looked at the most recent five years of 3-year averages from that table 
(2016-2020) \14\ and determined that the Lincoln monitor showed the 
uppermost second-highest design value with a value of 85 [micro]g/m\3\, 
well below the LMP Option Memo threshold of 98 [micro]g/m\3\.
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    \11\ While the 2001 PM10 LMP Option Memo refers to a 
June 1987 ``PM10 SIP Development Guideline'' document for 
methods in calculating design values for PM10, neither 
document provides specific information on how to calculate a design 
value using five years of air quality data. In October 2022, after 
ACHD submitted its PM10 LMP for the Liberty Borough area, 
EPA gave further clarification of how to compute a design value 
using five years of air quality data in a document titled ``Guidance 
on the Limited Maintenance Plan Option for Moderate PM2.5 
Nonattainment Areas and PM2.5 Maintenance Areas.''
    \12\ ACHD took this method from EPA's NetAssess2020 tool for 
monitored network assessments. https://sti-r-shiny.shinyapps.io/EPA_Network_Assessment/.
    \13\ See Table A-10 of ACHD's July 21, 2021 LMP SIP located in 
the docket for this proposed rulemaking.
    \14\ The 3-year design values for 2016-2020 include the 
following years: 2014-2016 (2016 3-year design value); 2015-2017 
(2017 3-year design value); 2016-2018 (2018 3-year design value); 
2017-2019 (2019 3-year design value); and 2018-2020 (2020 3-year 
design value).
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    EPA used the table look-up procedure as one of the acceptable 
approaches for determining appropriate 24-hour PM10 design 
concentrations.\15\ The Agency calculated the 5-year average design 
value for the Liberty Borough based on PM10 monitoring data 
from 2017 through 2021, the most recently available certified data from 
the Liberty Borough area monitoring sites.
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    \15\ The methods for calculating design values for 
PM10 are presented in a document entitled the 
``PM10 SIP Development Guideline,'' EPA-450/2-86-001, 
June 1987.
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    For the tabular approach for the 24-hour PM10 standard, 
EPA first determined the total number of 24-hour PM10 
concentrations at each monitoring site and the number of available 24-
hour concentrations to determine which of the highest concentrations is 
chosen as the design concentration. Table 2, in this document, which is 
the tabular estimation taken from EPA's PM10 SIP Development 
Guideline, specifies which rank value corresponds to the probable 
annual maximum value.\16\
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    \16\ The look-up procedure is a tabular technique for 
determining what point on the empirical frequency distribution 
corresponds to a frequency of 1/365. By construction, the table 
look-up procedure tends to provide a design concentration slightly 
lower than would be derived using a continuous curve representing a 
theoretical frequency distribution for PM10 values. 
Additional explanation regarding the use of tabular estimation can 
be found in EPA's PM10 SIP Development Guideline 
document.

        Table 2--Tabular Estimation of PM10 Design Concentrations
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                                           Data point used for design
        Number of daily values                    concentration
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<=347.................................  Highest Value.
348-695...............................  Second Highest Value.
696-1042..............................  Third Highest Value.
1043-1390.............................  Fourth Highest Value.
1391-1738.............................  Fifth Highest Value.
1739-2086.............................  Sixth Highest Value.
2087-2434.............................  Seventh Highest Value.
>2345.................................  Eighth Highest Value.
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    With multiple monitoring sites, the highest PM10 
concentrations at each site would have to be considered and a design 
concentration established for each location and the ``controlling'' 
design concentration for an area with multiple sites would be the 
highest values. For routine model applications with five full years of 
24-hour concentration estimates, the PM10 design 
concentration of critical interest becomes the highest of the sixth-
highest concentrations for the entire receptor network.
    Tables 3, 4, and 5, in this document, provide the average design 
values based on the tabular estimation method for the three Liberty 
Borough area monitors that remained in operation through 2021. EPA 
averaged the design values two ways for each of these monitors. First, 
we conducted the 5-year design value by looking at the five years as a 
whole set. For example, we counted the number of samples that occurred 
between January 1, 2017 and December 31, 2021. Then, as guided by in 
Table 2, in this document, we found the appropriate data point from 
amongst the 5-year data set.
    Alternatively, EPA also conducted the same process of reviewing the 
number of samples and finding the appropriate data point, but with each 
3-year design value period for the following five years: 2017, 2018, 
2019, 2020, and 2021. We then calculated the average of the five 3-year 
design values. The results can be found in Tables 3 through 5, in this 
document.

          Table 3--PM10 Average Design Value for the Clairton Monitor (FRM), Tabular Estimation Method
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Design value years                           Number of  Data point used for          Limited maintenance plan
                                         daily samples   design concentration.    average design value ([micro]g/
                                                                                               m\3\)
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2017-2021.............................             290  Highest Value...........                31
                                                                                 -------------------------------
2015-2017.............................             167  Highest Value...........              46            36.6
2016-2018.............................             170  Highest Value...........              46
2017-2019.............................             173  Highest Value...........              29
2018-2020.............................             175  Highest Value...........              31
2019-2021.............................             177  Highest Value...........              31
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[[Page 44241]]

          Table 4--PM10 Average Design Value for the Glassport (FEM) Monitor, Tabular Estimation Method
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Design value years                           Number of  Data point used for          Limited maintenance plan
                                         daily samples   design concentration.    average design value ([micro]g/
                                                                                               m\3\)
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2017-2021.............................            1797  Sixth Highest Value.....                59
                                                                                 -------------------------------
2015-2017.............................            1084  Fourth Highest Value....              68            62.6
2016-2018.............................            1082  Fourth Highest Value....              59
2017-2019.............................            1080  Fourth Highest Value....              68
2018-2020.............................            1079  Fourth Highest Value....              59
2019-2021.............................            1080  Fourth Highest Value....              59
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           Table 5--PM10 Average Design Value for the Liberty (FEM) Monitor, Tabular Estimation Method
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Design value years                           Number of  Data point used for          Limited maintenance plan
                                         daily samples   design concentration.    average design value ([micro]g/
                                                                                               m\3\)
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2017-2021.............................            1799  Sixth Highest Value.....                57
                                                                                 -------------------------------
2015-2017.............................            1051  Fourth Highest Value....              63            59.6
2016-2018.............................            1055  Fourth Highest Value....              62
2017-2019.............................            1071  Fourth Highest Value....              60
2018-2020.............................            1083  Fourth Highest Value....              56
2019-2021.............................            1086  Fourth Highest Value....              57
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    As shown in Tables 3 through 5, in this document, all of the 
average design values determined using the table look-up method through 
2021 are below the LMP option design value criteria of 98 [micro]g/
m\3\. The highest average values obtained using EPA's method were at 
the Glassport monitor (as seen in Table 4 in this document), but both 
methods of calculating average design value provided results well below 
98 [micro]g/m\3\. Therefore, EPA finds that the Liberty Borough area 
meets the design value criteria outlined in the LMP Option Memo.
    Third, the area must meet the motor vehicle regional emissions 
analysis test described in the LMP Option Memo. The Commonwealth and 
ACHD submitted an analysis showing that growth of on-road mobile 
PM10 emissions was minimal and would not threaten the 
assumption of maintenance that underlies the LMP policy. Using EPA's 
methodology, ACHD calculated total projected growth in on-road motor 
vehicle PM10 emissions through 2031 \17\ for the Liberty 
Borough area. This calculation is derived using Attachment B of the 
EPA's LMP Option Memo, where the projected percentage increase in 
vehicle miles traveled over the next ten years (VMTpi) is 
multiplied by the on-road mobile portion of the attainment year 
inventory (DVmv), including re-entrained road dust. This 
test is met when (VMTpi x DVmv) plus the design 
value for the most recent five years of quality assured data is below 
the margin of safety (MOS) for the relevant PM10 standard in 
[micro]g/m\3\ for a given area. This MOS value can be 98 [micro]g/m\3\, 
as ACHD chose to use, or a site-specific value computed from data 
collected at the site of interest using methods outlined in Attachment 
A of the LMP Option Memo.
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    \17\ Although this LMP applies to maintenance through 2023, ACHD 
still used ten years as the vehicle miles traveled (VMT) projection 
to be conservative. An interpolation of 2025 and 2035 VMT 
projections was calculated to project for the year 2031. Projections 
for Allegheny County were used to represent the area, since there 
are no projections specific to the Liberty Borough area.
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    ACHD used the motor vehicle regional analysis methodology with the 
average design value of 85 [micro]g/m\3\ for the Liberty Borough area 
using the highest 3-year design value for 2015, 2016, and 2017. 
Additionally, for the motor vehicle regional analysis calculation, ACHD 
used a VMTpi of 3.6 percent and a DVmv of 4.3 
[micro]g/m\3\. ACHD's motor vehicle regional emissions test analysis 
indicated a resulting value of 85.2 [micro]g/m\3\, which is below the 
MOS of 98 [micro]g/m\3\.\18\ EPA reviewed the calculations in the 
Liberty Borough area LMP SIP submission and the Agency proposes to find 
that the area meets the motor vehicle regional emissions analysis test.
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    \18\ Additional information on the data and calculations used 
for ACHD's analysis can be found in ACHD's SIP submission which is 
located in the docket for this proposed rulemaking.
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    As described previously, the Liberty Borough area PM10 
maintenance area meets the qualification criteria set forth in the LMP 
Option Memo and accordingly qualifies for the LMP option. To ensure 
these requirements continue to be met, ACHD commits to recalculating 
the design value on an annual basis through the end of 2023. The motor 
vehicle emissions test will also be recalculated annually using the 
updated maximum design value over the past five years for the area. If 
the test cannot be met (i.e., the equation shows a value above the 
MOS), ACHD will submit a full maintenance plan for the area according 
to CAA 175A requirements within one year after the determination of the 
updated design values.

B. Attainment Inventory

    Pursuant to the LMP Option Memo, an LMP SIP submission should 
include an emissions inventory, which can be used to demonstrate 
attainment of the relevant NAAQS. The inventory should represent 
emissions during the same 5-year period associated with air quality 
data used to determine whether the area meets the applicability 
requirements of the LMP option.
    The redesignation request and first 10-year maintenance plan for 
the Liberty Borough area included a 1994 emissions inventory.\19\ The 
inventory focused on stationary sources in Allegheny County and 
surrounding counties, as well as wood burning, public roads, and 
fugitive sources without permitted limits. Since the initial 
maintenance plan and redesignation request, many of the sources have 
lowered their permitted emissions rates of PM10 due to the 
installation of controls, equipment upgrades, fuel switches, as well as 
other factors, including shutting down. In the LMP SIP submittal, ACHD 
noted several of the emission reductions from over the

[[Page 44242]]

years, including several modifications at the United States Steel 
Corporation (USS) Mon Valley Works (MVW) Clairton Plant,\20\ 
representing an overall reduction of 268 tons per year (tpy) of 
PM10 from the previous allowable inventory, as well as 
shutdowns at several large sources outside of the area that provided 
over 3,000 tpy of PM10 reductions from the previous 
allowable inventory.\21\
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    \19\ The inventory was updated in 1999.
    \20\ Mon Valley Works--Clairton Plant ``is an integrated 
steelmaking operation that includes four separate facilities: 
Clairton Plant, Edgar Thomson Plant, Irvin Plant and Fairless 
Plant.'' Taken from www.ussteel.com/about-us/locations.
    \21\ See the PADEP/ACHD's July 21, 2021 SIP submission, located 
in the docket for this proposed rulemaking, for additional changes 
to the initial emissions allowable inventory.
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    According to ACHD, the total reductions in permitted allowable 
rates since the initial redesignation request represent an almost 
13,000 tpy overall reduction of PM10 allowable emissions. 
This is approximately 55 percent lower than the allowable inventory 
from the first 10-year maintenance period.
    To illustrate the current emissions in the Liberty Borough area, 
ACHD's current LMP SIP submission included an inventory of actual 
emissions using base year 2017. ACHD refers to this as the ``Liberty 
Borough area maintenance emissions inventory.'' ACHD used the 2017 
national emissions inventory (NEI), which was the most recent 
comprehensive inventory that was available to ACHD at the time it was 
preparing the LMP for the Liberty Borough area. The 2017 NEI is 
representative of the typical emissions during which continued 
attainment has occurred since the end of the Liberty Borough area's 
first 10-year maintenance plan period in 2013.\22\ Table 6 includes the 
following four main categories from the 2017 inventory: Stationary 
point sources, area (nonpoint) sources, nonroad mobile sources, and on-
road mobile sources.\23\ Stationary point sources contribute the 
largest amount of primary PM10 emissions (82 percent) and 
its precursors (87 percent),\24\ within the Liberty Borough area. Among 
all the stationary sources in the Liberty Borough area, the USS MVW 
Clairton Plant contributes the most PM10 primary and 
precursor emissions.
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    \22\ Additional information on ACHD's actual inventory can be 
found in the SIP submission located in the docket for this proposed 
action.
    \23\ A more detailed version of the inventory can be found in 
Appendix A of PADEP/ACHD's July 2021 SIP submission.
    \24\ Precursors for PM10 include sulfur dioxide 
(SO2), nitrogen oxides (NOX), volatile organic 
compounds (VOCs), and ammonia (NH3).

                             Table 6--Liberty Borough Area 2017 Emissions Inventory
                                                    [tpy] \a\
----------------------------------------------------------------------------------------------------------------
      Liberty borough area            PM10\c\           SO2             NOX            VOCs             NH3
----------------------------------------------------------------------------------------------------------------
Stationary Point Sources \b\....          877.93        1,129.86        2,626.26          184.45          118.87
Area (Nonpoint) Sources \d\.....          175.07            4.01           95.80          275.23            9.85
Nonroad Mobile Sources \d\......            4.33            0.10           37.83           33.19            0.09
Onroad Mobile Sources \d\.......           10.48            0.83           94.11           57.41            3.60
                                 -------------------------------------------------------------------------------
    Total.......................        1,067.81        1,134.80        2,854.00          550.28          132.41
----------------------------------------------------------------------------------------------------------------
\a\ Taken from ACHD's PM10 LMP for the Liberty Borough area.
\b\ Inventoried stationary sources within the Liberty Borough area include USS MVW Clairton Plant, Tech Met,
  Inc., Koppers Inc., and AKJ Steel Industries.
\c\ Total primary PM10.
\d\ Since NEI emissions are located to the county-level, ACHD used the U.S. Census's estimates for the 2017
  population percentage of the Liberty Borough area to scale down emissions from the total Allegheny County
  population.

1. Expected Emissions
    In the July 21, 2021, second maintenance plan SIP submission, ACHD 
noted that there is little growth in emissions expected for the Liberty 
Borough area through the end of the maintenance period in 2023. ACHD 
attributes the lack of potential for emissions growth through 2023 to 
several factors, including a 2019 settlement agreement and order with 
USS MVW Clairton Plant that requires the facility to conduct upgrades 
and work practice enhancements through 2023.\25\ ACHD provides 
additional information in their LMP submission regarding other programs 
and actions that will help to maintain or lower PM10 
emissions in the Liberty Borough area.
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    \25\ Allegheny County Health Department Air Quality Program. 
Settlement Agreement and Order #19060.
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2. PM10 SIP Controls
    In accordance with the CAA, areas seeking to use the LMP approach 
for maintenance must have an attainment plan that has been approved by 
EPA. That LMP should clearly indicate that all controls that were 
relied on to demonstrate attainment will remain in place. The July 21, 
2021, LMP SIP submission identifies the control strategies approved 
into the Liberty Borough area's attainment plan to bring the area into 
compliance. These controls were approved into the Pennsylvania SIP as 
permanent and enforceable measures and assisted the Liberty Borough 
area in attaining the PM10 NAAQS.\26\ These controls are to 
remain in place for the duration of the second maintenance period.
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    \26\ 61 FR 29664 (June 12, 1996) and 63 FR 32126 (June 12, 
1998).
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    The July 21, 2021 SIP submission meets EPA guidance for purposes of 
an attainment emissions inventory, and the emissions inventory data 
supports ACHD's conclusions that the existing control measures will 
continue to protect and maintain the PM10 NAAQS.

C. Maintenance Demonstration

    ACHD provided a maintenance demonstration for the Liberty Borough 
area in the first 10-year maintenance plan, which EPA approved on 
September 11, 2003 (68 FR 53515). According to EPA's 2001 
PM10 LMP Option Memo, if an area qualifies for the LMP 
option, EPA will treat that as a demonstration that the area will 
maintain the NAAQS and that, consequently, there is no need to model 
projected emissions over the maintenance period. Therefore, the Liberty 
Borough area is exempt from projecting emissions levels through the end 
date of the second 10-year maintenance plan.

D. Air Quality Monitoring Network

    Once an area is redesignated, the applicable state or local agency 
must continue to operate an appropriate air monitoring network in 
accordance with 40 CFR part 58 to verify the attainment

[[Page 44243]]

status of the area. ACHD has operated PM10 monitors 
according to 40 CFR part 58 requirements at four sites within the 
Liberty Borough area since submittal of the redesignation request in 
2002. A description, as well as a map, of the four Liberty Borough area 
PM10 monitors can be found in ACHD's LMP plan.\27\ On 
December 21, 2022, ACHD submitted its 2021 Annual Monitoring Network 
Plan, which EPA approved on February 24, 2023.\28\ ACHD indicated in 
the Liberty Borough area second 10-year maintenance plan that it will 
continue to operate the air monitoring network in accordance with 40 
CFR part 58 to verify the attainment status of the area, with no 
changes to the existing network unless preapproved by EPA.
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    \27\ Located in the docket for this proposed rulemaking. Docket 
No. EPA-R03-OAR-2023-0219, www.regulations.gov.
    \28\ EPA's approval letters for ACHD's past several Annual 
Monitoring Network Plans are included in the docket for this 
proposed rulemaking.
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E. Verification of Continued Attainment

    The level of the PM10 NAAQS is 150 [micro]g/m\3\, 24-
hour average concentration. The NAAQS is attained when the expected 
number of days per calendar year with a 24-hour average concentration 
above 150 [micro]g/m\3\ is equal to or less than one.\29\ As stated in 
the previous section of this preamble, ACHD plans to continue to 
operate a regulatory monitoring network and will continue to track the 
attainment status of the Liberty Borough area for the PM10 
NAAQS by reviewing monitored air quality concentrations during the 
maintenance period through 2023. ACHD will also continue to operate the 
air monitoring network in accordance with 40 CFR part 58 to verify the 
attainment status of the area, with no changes to the existing network 
unless pre-approved by EPA. Included in its second 10-year maintenance 
plan SIP submission, ACHD evaluated the complete, quality-assured, 
maximum 24-hour PM10 concentrations at each Liberty Borough 
area monitor from 2001-2020 to verify continued attainment of the 
standard.
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    \29\ See 40 CFR 50.6.
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F. Contingency Provisions

    Section 175A of the CAA states that a maintenance plan must include 
contingency provisions, as necessary, to ensure prompt correction of 
any violation of the NAAQS which may occur after redesignation of the 
area to attainment. As explained in the LMP Option Memo and the 
Calcagni Memo, these contingency provisions are an enforceable part of 
a federally approved SIP. The maintenance plan should clearly identify 
the events that would ``trigger'' the adoption and implementation of a 
contingency provision, the contingency provision(s) that would be 
adopted and implemented, and the schedule indicating the time frame by 
which the state and/or locality would adopt and implement the 
provision(s). The LMP Option Memo and the Calcagni Memo state that EPA 
will determine the adequacy of a contingency plan on a case-by-case 
basis. At a minimum, it must require that the applicable state or local 
agency implement all measures contained in the CAA part D nonattainment 
plan for the area prior to redesignation.
    In the Liberty Borough area PM10 LMP, ACHD indicated 
that the contingency provisions for the second 10-year maintenance plan 
are identical the contingency measures included in the area's 
attainment plan that was approved on September 8, 1998 (63 FR 47434). 
The contingency provisions include a requirement that the USS MVW 
Clairton Plant improve the capture of pushing emissions from its coke 
batteries. Within 60 days after determination of a violation of the 24-
hour PM10 NAAQS at any Liberty Borough area monitor, the 
contingency measures will be implemented. No contingency provisions or 
measures have been triggered at any time since the attainment plan SIP 
was approved in 1998.
    EPA proposes to determine that the contingency provisions submitted 
in the Liberty Borough area PM10 LMP are adequate to meet 
CAA section 175A requirements and the contingency provisions as 
outlined in the LMP Option Memo.

III. Proposed Action

    EPA is proposing to approve the second 10-year PM10 
limited maintenance plan for the Liberty Borough area. EPA has reviewed 
the air quality data for this area and determined that it continues to 
show attainment of the PM10 NAAQS and meets all the LMP 
requirements as described in this action. EPA is soliciting public 
comments on the issues discussed in this document. These comments will 
be considered before taking final action. If finalized, EPA's approval 
of this LMP will satisfy the section 175A CAA requirements for 
PM10 for the second 10-year maintenance period for the 
Liberty Borough area.

IV. 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);
     Does not impose an information collection burden under the 
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
     Is certified as not having a significant economic impact 
on a substantial number of small entities under the Regulatory 
Flexibility Act (5 U.S.C. 601 et seq.);
     Does not contain any unfunded mandate or significantly or 
uniquely affect small governments, as described in the Unfunded 
Mandates Reform Act of 1995 (Pub. L. 104-4);
     Does not have Federalism implications as specified in 
Executive Order 13132 (64 FR 43255, August 10, 1999);
     Is not an economically significant regulatory action based 
on health or safety risks subject to Executive Order 13045 (62 FR 
19885, April 23, 1997);
     Is not a significant regulatory action subject to 
Executive Order 13211 (66 FR 28355, May 22, 2001);
     Is not subject to requirements of section 12(d) of the 
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 
note) because application of those requirements would be inconsistent 
with the CAA; and
     Executive Order 12898 (Federal Actions to Address 
Environmental Justice in Minority Populations and Low-Income 
Populations, 59 FR 7629, February 16, 1994) directs Federal agencies to 
identify and address ``disproportionately high and adverse human health 
or environmental effects'' of their actions on minority populations and 
low-income populations to the greatest extent practicable and permitted 
by law. EPA defines environmental justice (E.J.) as ``the fair 
treatment and meaningful involvement of all people regardless of race, 
color,

[[Page 44244]]

national origin, or income with respect to the development, 
implementation, and enforcement of environmental laws, regulations, and 
policies.'' EPA further defines the term fair treatment to mean that 
``no group of people should bear a disproportionate burden of 
environmental harms and risks, including those resulting from the 
negative environmental consequences of industrial, governmental, and 
commercial operations or programs and policies.''
    The ACHD did not evaluate environmental justice considerations as 
part of its SIP submittal; the CAA and applicable implementing 
regulations neither prohibit nor require such an evaluation. EPA did 
not perform an E.J. analysis and did not consider E.J. in this proposed 
rulemaking. Due to the nature of the proposed action being taken here, 
this proposed rulemaking is expected to have a neutral to positive 
impact on the air quality of the affected area.
    In addition, this proposed rulemaking, regarding the second 10-year 
maintenance plan for the Liberty Borough PM10 area, does not 
have tribal implications as specified by Executive Order 13175 (65 FR 
67249, November 9, 2000), because the SIP is not approved to apply in 
Indian country located in the State, and EPA notes that it will not 
impose substantial direct costs on tribal governments or preempt tribal 
law.

List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Incorporation by 
reference, Particulate matter, Reporting and recordkeeping 
requirements.

Adam Ortiz,
Regional Administrator, Region III.
[FR Doc. 2023-14645 Filed 7-11-23; 8:45 am]
BILLING CODE 6560-50-P