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Federal Register / Vol. 86, No. 183 / Friday, September 24, 2021 / Proposed Rules
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c Identification of the 98th percentile 24-hour concentration is based on the number of creditable samples in a given year. See 40 CFR part 50, appendix N, section 4.5. Specifically, in any year for which there are at least 351 creditable samples, the 98th percentile is the 8th highest concentration, and as the number of creditable samples decreases the 98th percentile concentration is represented by a data point closer to the maximum concentration. The number of creditable samples in 2018 for Manteca is reflected inaccurately in AQS and results in an inaccurate 2018 98th percentile concentration and 20182020 design value. Table 5 reflects the 2018 98th percentile concentration and 20182020 design value based on the corrected number of creditable samples. See memorandum dated August 6, 2021, from Dena Vallano, EPA Region IX, to Docket EPAR09OAR20210261, Subject: San Joaquin Valley, CA 1997 24-hour PM2.5 Nonattainment Area, Manteca Monitoring.
d Based on the design calculation methodologies described in 40 CFR part 50, Appendix N, section 4.2b, the Manteca AQS ID: 06077
2010 20182020 design value is considered invalid due to incomplete data in the 1st, 2nd, and 3rd quarters of 2019.

In the EPAs review of monitoring data for the 1997 24-hour PM2.5 NAAQS
for the San Joaquin Valley nonattainment area, the EPA is excluding certain exceedances of the standard from the attainment determination presented herein because they were the result of exceptional events. Under the EPAs Exceptional Events Rule EER,284 exceedances flagged as exceptional events will only be considered for EPA concurrence if the data affect one of the types of regulatory actions specified by the EER.
The State has submitted a demonstration for a wildfire PM2.5
exceptional event covering a total of 30
measured exceedances occurring over 5
consecutive days August 2024, 2020
at 8 monitoring sites within the San Joaquin Valley nonattainment area that were critical for informing this attainment determination.285 The States submission notes that additional San Joaquin Valley monitoring sites were affected by wildfire smoke during the 20182020 period, but that those dates were not included in the submission because they did not cause the 2020
design values to violate the 1997 24hour PM2.5 NAAQS and did not have regulatory significance relevant to this determination.286 The EPA reviewed the documentation that the State provided to demonstrate that these exceedances meet the criteria for exceptional events under the EER. The EPA concurred with the States determinations that, based on the weight of evidence, the exceedances were caused by an exceptional event.287
Accordingly, the EPA has determined that the monitored exceedances associated with this exceptional event should not be used for regulatory purposes, including the evaluation of whether the San Joaquin Valley nonattainment area has attained by the 284 40

CFR 50.1j, k, l; 50.14a1i; 51.930.
eight monitoring sites covered by the August 2024, 2020 wildfire exceptional event demonstration include FresnoFoundry, BakersfieldAirport Planz, CorcoranPatterson, HanfordIrwin, StocktonHazelton, Manteca, Modesto14th Street, and Turlock.
286 SJVUAPCD, Exceptional Event Demonstration for August 2020 PM2.5 Exceedances due to Wildfires, May 11, 2021, 3.
287 Letter dated July 13, 2021, from Elizabeth J.
Adams, Director, Air and Radiation Division, EPA
Region IX, to Michael Benjamin, Division Chief, Air Quality Planning and Science Division, CARB.
285 The
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attainment date and evaluation of the CAA Serious area and section 189d plan submission. Excluding these exceedances caused by uncontrollable emissions, the EPA proposes to determine that the San Joaquin Valley has attained the 1997 24-hour PM2.5
NAAQS, consistent with attainment of the standard projected by the State in the SJV PM2.5 Plan.
VI. Summary of Proposed Action and Request for Public Comment The EPA is proposing to determine that the San Joaquin Valley nonattainment area has attained the 1997 24-hour PM2.5 NAAQS, based on complete or otherwise not inconsistent, quality-assured, and certified ambient air quality monitoring data for the 20182020 monitoring period. If finalized, this proposed determination that the San Joaquin Valley nonattainment area has attained the 1997 24-hour PM2.5 NAAQS would not constitute a redesignation of the area to attainment. Under CAA section 107d3E, redesignations of nonattainment areas to attainment require states to meet a number of additional statutory criteria, including the EPAs approval of a SIP revision demonstrating maintenance of the standard for 10 years after redesignation. The designation status of the San Joaquin Valley area will remain Serious nonattainment for the 1997 24hour PM2.5 NAAQS until such time as the EPA determines that the area meets the CAA requirements for redesignation to attainment.
For the reasons discussed in this proposed rule, under CAA section 110k3, the EPA is also proposing to approve in part and disapprove in part portions of the SJV PM2.5 Plan submitted by California that pertain to the 1997 24hour PM2.5 NAAQS in the San Joaquin Valley nonattainment area as follows:
1 We are proposing to approve the following elements as meeting the Serious nonattainment area planning requirements:
a The 2013 base year emissions inventories as meeting the requirements of CAA section 172c3 and 40 CFR
51.1008b;
b the BACM/BACT demonstration as meeting the requirements of CAA

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section 189b1B and 40 CFR
51.1010a;
c the demonstration including air quality modeling that the Plan provides for attainment as expeditiously as practicable as meeting the requirements of CAA sections 179d and 189b and 40 CFR 51.1011b;
d the RFP demonstration as meeting the requirements of CAA sections 172c2 and 1711 and 40 CFR
51.1012; and e the quantitative milestone demonstration as meeting the requirements of CAA section 189c and 40 CFR 51.1013;
2 We are proposing to approve the following elements as meeting the CAA
section 189d planning requirements:
a The 2013 base year emissions inventories as meeting the requirements of CAA section 172c3 and 40 CFR
51.1008c;
b the BACM/BACT demonstration as meeting the requirements of CAA
sections 189a1C 288 and 189b1B
and 40 CFR 51.1010c;
c the demonstration that the Plan will, at a minimum, achieve an annual five percent reduction in emissions of NOX as meeting the requirements of CAA section 189d and 40 CFR
51.1010c;
d the demonstration including air quality modeling that the Plan provides for attainment as expeditiously as practicable as meeting the requirements of CAA sections 179d and 189d and 40 CFR 51.1011b;
e the RFP demonstration as meeting the requirements of CAA sections 172c2 and 1711 and 40 CFR
51.1012; and f the quantitative milestone demonstration as meeting the requirements of CAA section 189c and 40 CFR 51.1013;
3 We are proposing to approve the motor vehicle emission budgets for 2017
and 2020 as shown in Table 8 of this proposed rule because they are derived 288 As discussed in section III.B of this document, a section 189d plan must address any outstanding Moderate or Serious area requirements that have not previously been approved. Because we have not previously approved a subpart 4 RACM
demonstration for the San Joaquin Valley nonattainment area, we are also proposing to approve the BACM/BACT demonstration in the SJV
PM2.5 Plan as meeting the subpart 4 RACM/RACT
requirement for the area.

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