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Federal Register / Vol. 86, No. 25 / Tuesday, February 9, 2021 / Proposed Rules FOR FURTHER INFORMATION CONTACT:

Serena Nichols, Planning &
Implementation Branch 3AD30, Air &
Radiation Division, U.S. Environmental Protection Agency, Region III, 1650
Arch Street, Philadelphia, PA 19103.
The telephone number is 215 814
2053. Ms. Nichols can also be reached via electronic mail at Nichols.Serena@
epa.gov.
SUPPLEMENTARY INFORMATION: On February 27, 2020, the PADEP
submitted a revision to the Pennsylvania SIP to incorporate a plan for maintaining the 1997 ozone NAAQS
in the Erie Area through November 8, 2027, in accordance with CAA section 175A.

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I. Background In 1979, under section 109 of the CAA, EPA established primary and secondary NAAQS for ozone at 0.12
parts per million ppm, averaged over a 1-hour period. 44 FR 8202 February 8, 1979. On July 18, 1997 62 FR
38856,1 EPA revised the primary and secondary NAAQS for ozone to set the acceptable level of ozone in the ambient air at 0.08 ppm, averaged over an 8-hour period. EPA set the 1997 ozone NAAQS
based on scientific evidence demonstrating that ozone causes adverse health effects at lower concentrations and over longer periods of time than was understood when the pre-existing 1-hour ozone NAAQS was set.
Following promulgation of a new or revised NAAQS, EPA is required by the CAA to designate areas throughout the nation as attaining or not attaining the NAAQS. On April 30, 2004 69 FR
23858, EPA designated the Erie Area as nonattainment for the 1997 ozone NAAQS. The Erie Area consists solely of Erie County.
Once a nonattainment area has three years of complete and certified air quality data that has been determined to attain the NAAQS, and the area has met the other criteria outlined in CAA
section 107d3E,2 the state can 1 In March 2008, EPA completed another review of the primary and secondary ozone standards and tightened them further by lowering the level for both to 0.075 ppm. 73 FR 16436 March 27, 2008.
Additionally, in October 2015, EPA completed a review of the primary and secondary ozone standards and tightened them by lowering the level for both to 0.70 ppm. 80 FR 65292 October 26, 2015.
2 The requirements of CAA section 107d3E
include attainment of the NAAQS, full approval under section 110k of the applicable SIP, determination that improvement in air quality is a result of permanent and enforceable reductions in emissions, demonstration that the state has met all applicable section 110 and part D requirements, and a fully approved maintenance plan under CAA
section 175A.

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submit a request to EPA to redesignate the area to attainment. Areas that have been redesignated by EPA from nonattainment to attainment are referred to as maintenance areas. One of the criteria for redesignation is to have an approved maintenance plan under CAA
section 175A. The maintenance plan must demonstrate that the area will continue to maintain the standard for the period extending 10 years after redesignation, and it must contain such additional measures as necessary to ensure maintenance as well as contingency measures as necessary to assure that violations of the standard will be promptly corrected.
On October 9th, 2007 72 FR 57207, EPA approved a redesignation request and maintenance plan from PADEP for the Erie Area. In accordance with section 175Ab, at the end of the eighth year after the effective date of the redesignation, the state must also submit a second maintenance plan to ensure ongoing maintenance of the standard for an additional 10 years.
EPAs final implementation rule for the 2008 ozone NAAQS revoked the 1997 ozone NAAQS and provided that one consequence of revocation was that areas that had been redesignated to attainment i.e., maintenance areas for the 1997 ozone NAAQS no longer needed to submit second 10-year maintenance plans under CAA section 175Ab.3 However, in South Coast Air Quality Management District v. EPA 4
South Coast II, the United States Court of Appeals for the District of Columbia D.C. Circuit vacated EPAs interpretation that, because of the revocation of the 1997 ozone standard, second maintenance plans were not required for orphan maintenance areas, i.e., areas like the Erie Area that had been redesignated to attainment for the 1997 ozone NAAQS and were designated attainment for the 2008
ozone NAAQS. Thus, states with these orphan maintenance areas under the 1997 ozone NAAQS must submit maintenance plans for the second maintenance period.
As previously discussed, CAA section 175A sets forth the criteria for adequate maintenance plans. In addition, EPA
has published longstanding guidance that provides further insight on the content of an approvable maintenance plan, explaining that a maintenance plan should address five elements: 1
An attainment emissions inventory; 2
a maintenance demonstration; 3 a commitment for continued air quality monitoring; 4 a process for verification 3 See 4 882

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80 FR 12315 March 6, 2015.
F.3d 1138 D.C. Cir. 2018.

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of continued attainment; and 5 a contingency plan. The 1992 Calcagni Memo 5 provides that states may generally demonstrate maintenance by either performing air quality modeling to show that the future mix of sources and emission rates will not cause a violation of the NAAQS or by showing that future emissions of a pollutant and its precursors will not exceed the level of emissions during a year when the area was attaining the NAAQS i.e., attainment year inventory. See 1992
Calcagni Memo at p. 9. EPA further clarified in three subsequent guidance memos describing limited maintenance plans LMPs 6 that the requirements of CAA section 175A could be met by demonstrating that the areas design value 7 was well below the NAAQS and that the historical stability of the areas air quality levels showed that the area was unlikely to violate the NAAQS in the future. Specifically, EPA believes that if the most recent air quality design value for the area is at a level that is below 85% of the standard, or in this case below 0.071 ppm, then EPA
considers the state to have met the section 175A requirement for a demonstration that the area will maintain the NAAQS for the requisite period. Accordingly, on February 27, 2020, PADEP submitted an LMP for the Erie Area, following EPAs LMP
guidance and demonstrating that the area will maintain the 1997 ozone NAAQS through November 8, 2027, i.e., through the entire 20-year maintenance period.
II. Summary of SIP Revision and EPA
Analysis PADEPs February 27, 2020 SIP
submittal outlines a plan for continued maintenance of the 1997 ozone NAAQS
which addresses the criteria set forth in the 1992 Calcagni Memo as follows.
5 Procedures for Processing Requests to Redesignate Areas to Attainment, Memorandum from John Calcagni, Director, Air Quality Management Division, September 4, 1992 1992
Calcagni Memo.
6 See Limited Maintenance Plan Option for Nonclassifiable Ozone Nonattainment Areas from Sally L. Shaver, Office of Air Quality Planning and Standards OAQPS, dated November 16, 1994;
Limited Maintenance Plan Option for Nonclassifiable CO Nonattainment Areas from Joseph Paisie, OAQPS, dated October 6, 1995; and Limited Maintenance Plan Option for Moderate PM10 Nonattainment Areas from Lydia Wegman, OAQPS, dated August 9, 2001.
7 The ozone design value for a monitoring site is the 3-year average of the annual fourth-highest daily maximum 8-hour average ozone concentrations.
The design value for an ozone nonattainment area is the highest design value of any monitoring site in the area.

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