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Federal Register / Vol. 86, No. 156 / Tuesday, August 17, 2021 / Proposed Rules
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EPA approves a SIP for the area before that date.
In the meantime, EGLE obtained air quality monitoring data in the St. Clair area which had not been available before the St. Clair area was designated nonattainment. On July 24, 2020, EGLE
submitted a request that EPA make a determination under the Clean Air Act CAA and EPAs Clean Data Policy, based on both local monitored air quality data and a new dispersion modeling analysis, that the St. Clair nonattainment area has attained the 2010 SO2 NAAQS Clean Data Determination. Approval of EGLEs request would suspend the requirement for the state to submit certain planning elements otherwise required under CAA
section 172c for a NA SIP for the St.
Clair area, and suspend the sanctions and FIP clocks, for so long as the area continues to attain the 2010 SO2
NAAQS. EGLE would still be required to submit an emissions inventory EI
required by CAA section 172c3 and a nonattainment new source review NNSR program required by CAA
section 172c5, in order to avoid sanctions. EGLE submitted the St. Clair areas EI and NNSR verification to EPA
on June 30, 2021.
II. Clean Data Determinations Following enactment of the CAA
Amendments of 1990, EPA discussed its interpretation of the requirements for implementing the NAAQS in the General Preamble for the Implementation of title I of the CAA
Amendments of 1990 General Preamble, 57 FR 13498, 13564 April 16, 1992. In 1995, based on the interpretation of CAA sections 171, 172, and 182 in the General Preamble, EPA
set forth what has become known as its Clean Data Policy for the 1-hour ozone NAAQS. Under the Clean Data Policy, for a nonattainment area that can demonstrate attainment of the standard before implementing CAA
nonattainment measures, EPA interprets the requirements of the CAA that are specifically designed to help an area achieve attainment, such as attainment demonstrations, implementation of reasonably available control measures, including reasonably available control technology RACM/RACT, reasonable further progress RFP demonstrations, emissions limitations and control measures as necessary to provide for attainment, and contingency measures, to be suspended for so long as air quality continues to meet the standard.
See the May 10, 1995 memorandum from John S. Seitz, Director, Office of Air Quality Planning and Standards, entitled, Reasonable Further Progress,
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Attainment Demonstration, and Related Requirements for Ozone Nonattainment areas Meeting the Ozone National Ambient Air Quality Standard. In an April 23, 2014 memorandum from Steve Page, Director of the EPAs Office of Air Quality Planning and Standards, to the EPA Air Division Directors entitled, Guidance for 1-hr SO2 Nonattainment Area SIP Submissions 2014 SO2
Nonattainment Area Guidance, EPA
provides guidance and a rationale for the application of the Clean Data Policy to the 2010 1-hour primary SO2
NAAQS.
A state may notify EPA that it believes a nonattainment area is attaining the 2010 SO2 NAAQS and request a clean data determination under EPAs Clean Data Policy. EPA will determine whether the area has attained the 2010
SO2 NAAQS based on available information, including available air quality monitoring data and air quality dispersion modeling information for the affected area. If the determination of attainment is granted, then requirements for the area such as a nonattainment SIP
submittal or reasonable further progress measures are suspended for so long as the area continues to attain the NAAQS.
Provided the area has submitted a complete EI and NNSR program, sanctions for failing to timely submit a SIP are also suspended for so long as the area remains in attainment.
However, the suspension of the obligations to submit attainment planning related SIPs is only appropriate where the area remains in attainment of the NAAQS. EPA is proposing to require EGLE to submit annual statements by July 1 to EPA, to address whether the St Clair area has continued to attain the 2010 SO2
NAAQS. EPA expects that these statements could include such information as available air quality monitoring data or an assessment of changes in facility emissions or operations and whether these changes warrant updated modeling. If EPA does not receive credible information indicating that the area continues to attain the SO2 NAAQS, EPA will propose to rescind the St. Clair areas clean data determination, the finalization of which would lift the suspension of its attainment planning requirements and would reinstate the sanctions and FIP clocks with their original deadlines.
The determination of attainment under the Clean Data Policy does not serve to alter the areas nonattainment designation. Clean data determinations are not redesignations to attainment. For EPA to redesignate an area to attainment, the area must meet the
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requirements of CAA section 107d3
and demonstrate maintenance as required by CAA section 175A.
III. Analysis of EGLEs Request EGLEs July 24, 2020 request for a clean data determination included local monitoring data and a dispersion modeling analysis for the St. Clair nonattainment area. The 2014 SO2
Nonattainment Area Guidance states that when air agencies provide monitoring and/or modeling to support clean data determinations, the monitoring data provided by the state should follow EPAs SO2 NAAQS
Designations Source-Oriented Monitoring Technical Assistance Document SO2 Monitoring TAD and the modeling provided by the state should follow EPAs SO2 NAAQS
Designations Modeling Technical Assistance Document SO2 Modeling TAD.
The Monitoring TAD was provided by EPA to assist states in siting monitors to characterize ambient air quality impacted by significant SO2 sources, with the goal to identify peak SO2
concentrations attributable to those sources. Collaboration with other stakeholders such as affected industry was encouraged in the Monitoring TAD.
The Monitoring TAD suggests that existing industry monitoring operations could be found to meet the necessary requirements to produce data of appropriate quality for comparison to the NAAQS. Industrial monitors should be appropriately sited and operated in a manner largely equivalent to those monitors operated elsewhere in the State and Local Air Monitoring Stations SLAMS network, meeting applicable criteria in 40 CFR part 58, appendices A, C, and E and reporting their data to the Air Quality Subsystem AQS.
EGLEs July 24, 2020 submittal included three years of monitoring data from two industrial monitors located in the St. Clair nonattainment area, near the power plants. DTE installed the two SO2 monitors in the St. Clair nonattainment area in 2016 to evaluate SO2 impacts from the two facilities. The monitors were sited using dispersion modeling to help identify the locations of predicted maximum SO2
concentrations. Considering the monitor siting guidance in the Monitoring TAD, EPA believes that these monitors locations adequately represent the locations of potential maximum SO2
impacts from the two power plants. One monitor, known as the Remer monitor, is sited near the St. Clair River, between and slightly north of the two power plants, about one kilometer km from each plant. Previously modeled
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