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Federal Register / Vol. 86, No. 24 / Monday, February 8, 2021 / Proposed Rules
On July 6, 2007 72 FR 36892, effective the same day, EPA approved a redesignation request and maintenance plan from PADEP for the Tioga County 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 Tioga County 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 of continued attainment; and 5 a 3 See
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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 March 10, 2020, PADEP submitted an LMP for the Tioga County Area, following EPAs LMP
guidance and demonstrating that the area will maintain the 1997 ozone 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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NAAQS through July 6, 2027, i.e., through the entire 20-year maintenance period.
II. Summary of SIP Revision and EPA
Analysis PADEPs March 10, 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.
A. Attainment Emissions Inventory For maintenance plans, a state should develop a comprehensive and accurate inventory of actual emissions for an attainment year which identifies the level of emissions in the area which is sufficient to maintain the NAAQS. The inventory should be developed consistent with EPAs most recent guidance. For ozone, the inventory should be based on typical summer days emissions of oxides of nitrogen NOX and volatile organic compounds VOC, the precursors to ozone formation. In the first maintenance plan for the Tioga County Area, PADEP used 2004 for the attainment year inventory, because 2004 was a reasonable year within the 20022004 3-year block and is one of the years in the 20032005
three-year period when the area first attained the 1997 ozone NAAQS.8 The Tioga County Area continued to monitor attainment of the 1997 ozone NAAQS in 2014. Therefore, the emissions inventory from 2014 represents emissions levels conducive to continued attainment i.e., maintenance of the NAAQS. Thus, PADEP is using 2014 as representing attainment level emissions for its second maintenance plan.
Pennsylvania used 2014 summer day emissions from EPAs 2014 version 7.0
modeling platform as the basis for the 2014 inventory presented in Table 1.9
8 For more information, see EPAs May 8, 2007
notice proposing to redesignate the Tioga County Area to attainment for the 1997 ozone NAAQS 72
FR 26046.
9 For more information, visit https
www.epa.gov/sites/production/files/2018-11/ozone_
1997_naaqs_emiss_inv_data_nov_19_2018_0.xlsx.

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