[Federal Register Volume 86, Number 156 (Tuesday, August 17, 2021)]
[Proposed Rules]
[Pages 45947-45950]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-17546]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R05-OAR-2020-0385; FRL-8826-01-R5]


Air Plan Approval; Michigan; Sulfur Dioxide Clean Data 
Determination for St. Clair

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to make 
a determination that the St. Clair sulfur dioxide (SO2) 
nonattainment area has attained the 2010 primary SO2 
National Ambient Air Quality Standard (2010 SO2 NAAQS). If 
finalized, this determination would suspend certain requirements for 
the nonattainment area for as long as the area continues to attain the 
2010 SO2 NAAQS.

DATES: Comments must be received on or before September 16, 2021.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R05-
OAR-2020-0385 at http://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 http://www2.epa.gov/dockets/commenting-epa-dockets.

FOR FURTHER INFORMATION CONTACT: Mary Portanova, Environmental 
Engineer, Control Strategies Section, Air Programs Branch (AR18J), 
Environmental Protection Agency, Region 5, 77 West Jackson Boulevard, 
Chicago, Illinois 60604, (312) 353-5954 [email protected]. The EPA 
Region 5 office is open from 8:30 a.m. to 4:30 p.m., Monday through 
Friday, excluding Federal holidays and facility closures due to COVID-
19.

SUPPLEMENTARY INFORMATION: Throughout this document whenever ``we,'' 
``us,'' or ``our'' is used, we mean EPA.

I. Background

    The St. Clair area was designated nonattainment for the 2010 
SO2 NAAQS on July 12, 2016 (81 FR 45039), based on air 
quality modeling showing violations of the standard. The two 
SO2-emitting facilities in the St. Clair area are DTE 
Energy-Belle River (Belle River plant) and DTE Energy-St. Clair (St. 
Clair plant), which are both coal-fired power plants. The nonattainment 
area consists of a portion of southeastern St. Clair County, Michigan, 
located northeast of Detroit. The nonattainment area shares a border 
with Ontario, Canada along the St. Clair River. (See the area's 
complete boundary description at 40 CFR 81.323).
    The Michigan Department of Environment, Great Lakes, and Energy 
(EGLE) was required to prepare a nonattainment State Implementation 
Plan (NA SIP) by March 12, 2018 to bring the St. Clair area into 
attainment by the attainment date of September 12, 2021, but EGLE did 
not submit a complete NA SIP for the St. Clair area by the March 12, 
2018 deadline. On September 20, 2019 (84 FR 49462), EPA issued a 
finding of failure to submit (FFS) a SIP required for attainment of the 
2010 SO2 NAAQS.
    EGLE has informed EPA that DTE intends to close the St. Clair plant 
in 2022, and use a new natural gas power plant, already under 
construction, to generate electric power in its place. This plant 
closure and replacement is expected to result in a large SO2 
emission reduction for the area, but the expected SO2 
reductions would not occur in time to be a timely element of the 
required 2018 NA SIP for the St. Clair area. Nevertheless, the 
September 20, 2019 FFS resulted in the initiation of an 18-month clock 
toward imposition of sanctions for the state under CAA section 179, 
unless an approvable SO2 SIP is submitted and deemed 
complete by EPA. (See 40 CFR 52.31(d)(5)). In addition, the FFS started 
a two-year clock by which EPA is required under CAA section 110(c) to 
promulgate a Federal Implementation Plan (FIP) for the area, unless the 
state submits and

[[Page 45948]]

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 
EPA's 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 EGLE's request would suspend the 
requirement for the state to submit certain planning elements otherwise 
required under CAA section 172(c) 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 
172(c)(3) and a nonattainment new source review (NNSR) program required 
by CAA section 172(c)(5), in order to avoid sanctions. EGLE submitted 
the St. Clair area's 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, 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 EPA's 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 EPA's 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 area's 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 area's nonattainment designation. Clean data 
determinations are not redesignations to attainment. For EPA to 
redesignate an area to attainment, the area must meet the requirements 
of CAA section 107(d)(3) and demonstrate maintenance as required by CAA 
section 175A.

III. Analysis of EGLE's Request

    EGLE's 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 EPA's ''SO2 NAAQS 
Designations Source-Oriented Monitoring Technical Assistance Document'' 
(SO2 Monitoring TAD) and the modeling provided by the state 
should follow EPA's ``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).
    EGLE's 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

[[Page 45949]]

maximum SO2 concentrations have been predicted at or near 
this location. The other monitor, known as the Mills monitor, is sited 
3 km west of the Belle River plant, so that it can capture the worst-
case combined impacts when winds are blowing from the St. Clair plant 
toward the Belle River plant.
    EPA reviewed the ambient air monitoring data for the 2017-2019 
period, which were the three most recent full calendar years of data 
available. Ambient and quality assurance data for these two monitoring 
sites are recorded in EPA's AQS database. EGLE and EPA have reviewed 
the data and have determined that this data meets completeness and data 
quality indicators confirm that the data is suitable to be used in 
support of a clean data determination for the St. Clair area.
    The data cited by EGLE in its request show attainment of the 2010 
SO2 NAAQS at both monitors for the 2017-2019 time period, 
with three-year average 99th percentile daily maximum 1-hour 
concentrations (design values) of 54 and 45 parts per billion (ppb), 
which are below the 2010 SO2 NAAQS of 75 ppb. Data for 2020 
indicate that the monitors have continued to show attainment. Table 1 
shows the 2017-2020 SO2 monitoring results for the St. Clair 
area monitors.

                                              Table 1--2017-2020 Monitored SO2 Values in the St. Clair Area
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                                                                           Annual 99th percentile (ppb)                      2017-2019       2018-2020
                         Monitor                         ----------------------------------------------------------------  design value    design value
                                                               2017            2018            2019            2020            (ppb)           (ppb)
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Mills Monitor...........................................              46              50              40              29              45              40
Remer Monitor...........................................              51              65              45              25              54              45
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    EPA also reviewed the dispersion modeling analysis for the St. 
Clair area which EGLE submitted on July 24, 2020. The SO2 
Modeling TAD outlines modeling approaches for SO2 NAAQS 
attainment status designations and states that, for the purposes of 
modeling to characterize air quality for use in SO2 
designations, EPA recommends using a minimum of the most recent three 
years of actual emissions data and concurrent meteorological data to 
allow the modeling to simulate what a monitor would observe.
    EGLE's analysis followed the Modeling TAD and modeled the impacts 
of the Belle River and St. Clair plants in the St. Clair nonattainment 
area. EGLE used the actual 2017-2019 hourly SO2 emissions 
for the Belle River and St. Clair plants as measured by continuous 
emissions monitor (CEM) data. EGLE also characterized the buildings at 
the two plants using the AERMOD component BPIPPRM, to address building 
downwash. There were no additional nearby sources that were expected to 
produce a significant SO2 concentration gradient in the 
nonattainment area.
    To model the St. Clair nonattainment area, EGLE used EPA's AERMOD 
model, version 19191, with meteorological data for 2017-2019 from the 
Oakland County International Airport (Pontiac), located 75 km to the 
west of the St. Clair plants. This meteorological data set is 
considered to be representative of the St. Clair area. The area was 
modeled as rural, based on local land use characteristics. Terrain 
information was included in the modeling analysis. The nonattainment 
area is flat and mostly residential or agricultural. The river valley 
is not deep, although some wind channeling could occur. The 
geographical and topographical features of the area are not considered 
to significantly impact air pollution transport. The St. Clair modeling 
analysis used a nested receptor grid with resolution from 50 meters 
near the facilities to 100 meters in the central portion, and then 250 
meters to the edge of the modeling domain, 10 km from the power plants.
    For a background concentration for the modeling analysis, EGLE used 
monitored SO2 data from Michigan's SO2 monitor in 
Port Huron, located 21 km to the north of the St. Clair plants. The 
Port Huron monitor has an SO2 design value of 67 ppb for 
2017-2019. EGLE determined its background concentration using a 
temporally varying approach to characterize background SO2 
emissions, based on the 99th percentile monitored concentrations by 
season and hour of day. In this analysis, EGLE used data measured when 
winds were blowing from wind direction sectors which were chosen to 
avoid double-counting emissions from the St. Clair and Belle River 
plants and to avoid overestimating impacts from sources which are 
located in Canada, 3-5 km east of Port Huron but 15-20 km from the St. 
Clair area. The Modeling TAD provides for this approach. At such 
distances, the Canadian sources are not expected to provide a 
significant concentration gradient in the St. Clair area. The modeling 
analysis' results match well with the monitored values near the St. 
Clair plants, which suggests that the modeling analysis is not missing 
significant additional ambient contributions at those locations. 
Therefore, EPA concurs with the background values EGLE used in its 
analysis. The background concentrations for the St. Clair modeling 
analysis were determined to vary from 1.3 to 6.5 ppb, with an average 
value of 2.4 ppb.
    The state's modeling resulted in a three-year maximum predicted 
99th percentile daily maximum 1-hour concentration of 64.4 ppb, 
including background. This design value was predicted at a receptor 
located very near the St. Clair plant. As the predicted design value is 
below the 2010 SO2 NAAQS of 75 ppb, the state's modeling 
demonstrates attainment of the 2010 SO2 NAAQS.
    EGLE's modeling results for receptors placed at the two 
SO2 monitors' locations matched well with the actual 
monitored design values. The model's predicted design value at the 
Remer monitor location was 47.7 ppb, compared to the monitored design 
value of 45 ppb, and the model's predicted design value at the Mills 
monitor location was 52.7 ppb, compared to the monitored design value 
of 54 ppb. The location of the maximum modeled 99th percentile 
concentration was less than half a kilometer from the Remer monitor, 
which lends support to EPA's expectation that the Remer monitor is 
located in the area of expected maximum concentrations. Other areas of 
predicted high concentrations were at approximately the same distance 
to the northwest and west of the power plants as the Mills monitor, 
again lending support to EPA's expectation that the Mills monitor 
location is also representative of areas of high expected 
concentrations.
    After reviewing EGLE's July 24, 2020 submittal, EPA proposes to 
find that the St. Clair area has attained the 2010 SO2 NAAQS 
and satisfies the requirements of the Clean Data Policy.

[[Page 45950]]

IV. What action is EPA taking?

    EPA is proposing to approve EGLE's request for a Clean Data 
Determination for the St. Clair nonattainment area in St. Clair County, 
Michigan. Finalizing this determination would suspend the requirements 
for EGLE to submit an attainment demonstration and other associated 
nonattainment planning requirements for so long as the St. Clair 
nonattainment area continues to attain the 2010 SO2 NAAQS. 
This proposed action is consistent with EPA's long-held interpretation 
of CAA requirements.
    Finalizing this action would not constitute a redesignation of the 
St. Clair area to attainment of the 2010 SO2 NAAQS under 
section 107(d)(3) of the CAA. The St. Clair area will remain designated 
nonattainment for the 2010 SO2 NAAQS until such time as EPA 
determines that the area meets the CAA requirements for redesignation 
to attainment and takes action to redesignate the area.

V. Statutory and Executive Order Reviews

    This action proposes to make a clean data determination for the St. 
Clair area for the 2010 SO2 NAAQS based on air quality data 
which would result in the suspension of certain Federal requirements 
and does not impose any additional requirements. For that reason, this 
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
     Does not provide EPA with the discretionary authority to 
address, as appropriate, disproportionate human health or environmental 
effects, using practicable and legally permissible methods, under 
Executive Order 12898 (59 FR 7629, February 16, 1994).
    In addition, the SIP is not approved to apply on any Indian 
reservation land or in any other area where EPA or an Indian tribe has 
demonstrated that a tribe has jurisdiction. In those areas of Indian 
country, the rule does not have tribal implications and will not impose 
substantial direct costs on tribal governments or preempt tribal law as 
specified by Executive Order 13175 (65 FR 67249, November 9, 2000).

List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Incorporation by 
reference, Intergovernmental relations, Sulfur oxides.

    Dated: August 9, 2021.
Cheryl Newton,
Acting Regional Administrator, Region 5.
[FR Doc. 2021-17546 Filed 8-16-21; 8:45 am]
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