Federal Register / Vol. 86, No. 122 / Tuesday, June 29, 2021 / Proposed Rules 34177 

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, Infrastructure, 

Intergovernmental relations, Ozone. 

Dated: June 22, 2021. 

Edward H. Chu, 

Acting Regional Administrator, Region 7. 

For the reasons stated in the 

preamble, the EPA proposes to amend 

40 CFR part 52 as set forth below: 

PART 52—APPROVAL AND 

PROMULGATION OF 

IMPLEMENTATION PLANS 

■ 1. The authority citation for part 52 

continues to read as follows: 

Authority: 42 U.S.C. 7401 et seq. 

Subpart Q—Iowa 

■ 2. In § 52.820, the table in paragraph 

(e) is amended by adding the entry 

‘‘(54)’’ in numerical order to read as 

follows: 

§ 52.820 Identification of plan. 

* * * * * 

(e) * * * 

EPA-APPROVED IOWA NONREGULATORY PROVISIONS

Name of 

nonregulatory 

SIP provision 

Applicable 

geographic 

or nonattainment area 

State 

submittal 

date 

EPA approval date Explanation 

*******

(54)Section 110(a)(2) Infrastructure Requirements for 

the 2015 O3 NAAQS.

Statewide ....... 11/30/18 [Date of publication of the final 

rule in the Federal Register], [Federal Register citation of the final rule].

[EPA–R07–OAR–2021–0378; FRL–10024– 

86–Region 7]. 

This action proposes to approve the following 

CAA elements: 110(a)(2)(A), (B), (C), 

(D)(i)(II)—prongs 3 and 4, (D)(ii), (E), (F), 

(G), (H), (J), (K), (L), and (M). 

110(a)(2)(D)(i)(I)—prongs 1 and 2 will be 

addressed in a separate action. 110(a)(2)(I) 

is not applicable. 

[FR Doc. 2021–13824 Filed 6–28–21; 8:45 am] 

BILLING CODE 6560–50–P 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Parts 52 and 81 

[EPA–R07–OAR–2021–0391; FRL–10025– 

26–Region 7] 

Air Plan Approval; Missouri 

Redesignation Request and 

Associated Maintenance Plan for the 

Jefferson County 2010 SO2 1-Hour 

NAAQS Nonattainment Area 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Proposed rule. 

SUMMARY: On December 27, 2017, the 

State of Missouri submitted a request for 

the Environmental Protection Agency 

(EPA) to redesignate the Jefferson 

County, Missouri, 2010 1-hour sulfur 

dioxide (SO2) National Ambient Air 

Quality Standard (NAAQS) 

nonattainment area to attainment and to 

approve a State Implementation Plan 

(SIP) revision containing a maintenance 

plan for the area. The State provided 

supplemental information on: May 15, 

2018; February 7, 2019; February 25, 

2019; and April 9, 2021. In response to 

these submittals, the EPA is proposing 

to take the following actions: Approve 

the State’s plan for maintaining 

attainment of the 2010 1-hour SO2

primary standard in the area; and 

approve the State’s request to 

redesignate the Jefferson County SO2

nonattainment area to attainment for the 

2010 1-hour SO2 primary standard. 

DATES: Comments must be received on 

or before July 29, 2021. 

ADDRESSES: You may send comments, 

identified by Docket ID No. EPA–R07– 

OAR–2021–0391 to https://

www.regulations.gov. Follow the online 

instructions for submitting comments. 

Instructions: All submissions received 

must include the Docket ID No. for this 

rulemaking. Comments received will be 

posted without change to https://

www.regulations.gov/, including any 

personal information provided. For 

detailed instructions on sending 

comments and additional information 

on the rulemaking process, see the 

‘‘Written Comments’’ heading of the 

SUPPLEMENTARY INFORMATION section of 

this document. 

FOR FURTHER INFORMATION CONTACT: 

Ashley Keas, Environmental Protection 

Agency, Region 7 Office, Air Quality 

Planning Branch, 11201 Renner 

Boulevard, Lenexa, Kansas 66219 at 

(913) 551–7629 or by email at 

keas.ashley@epa.gov. 

SUPPLEMENTARY INFORMATION: 

Throughout this document ‘‘we,’’ ‘‘us,’’ 

and ‘‘our’’ refer to the EPA. 

Table of Contents 

I. Written Comments 

II. Have the requirements for approval of a 

SIP revision been met? 

III. What is the background for the EPA’s 

proposed actions? 

IV. What are the criteria for redesignation? 

V. What is the EPA’s analysis of the request? 

VI. What are the actions the EPA is proposing 

to take? 

VII. Environmental Justice Concerns 

VIII. Incorporation by Reference 

IX. Statutory and Executive Order Reviews 

I. Written Comments 

Submit your comments, identified by 

Docket ID No. EPA–R07–OAR–2021– 

0391, at https://www.regulations.gov. 

Once submitted, comments cannot be 

edited or removed from regulations.gov. 

The 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. The 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 


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1See 75 FR 35520. 

2See 40 CFR 50.17. 

3 40 CFR part 50, appendix T, section 3(b). 

4CAA section 107(d)(1)(A)(i). 

5 78 FR 47191 (August 5, 2013), codified at 40 

CFR 81.326. 

6See 82 FR 28605. 

7The State or Local Air Monitoring Station 

(SLAMS) was moved from Main Street to Mott 

Street in 2011 with EPA approval. The Mott Street 

SLAMS location was selected to characterize source 

specific (both SO2 and lead) emissions from the Doe 

Run Herculaneum primary lead smelter. 

8See 82 FR 42945. 

additional submission methods, the full 

EPA public comment policy, 

information about CBI or multimedia 

submissions, and general guidance on 

making effective comments, please visit 

https://www.epa.gov/dockets/ 

commenting-epa-dockets. 

II. Have the requirements for approval 

of a SIP revision been met? 

The State submission has met the 

public notice requirements for SIP 

submissions in accordance with 40 CFR 

51.102. The submission also satisfied 

the completeness criteria of 40 CFR part 

51, appendix V. The State provided 

public notice on the December 2017 SIP 

submittal from July 31, 2017 to 

September 7, 2017 and held a public 

hearing on August 31, 2017. The State 

received and addressed nineteen 

combined comments from a total of five 

sources. The State revised the 

maintenance plan based on public 

comment prior to submitting to the EPA. 

On April 9, 2021, Missouri submitted 

a supplement to the SIP revision to the 

EPA consisting of an addendum to the 

Consent Agreement between Ameren 

and Missouri. The Consent Agreement 

addendum incorporates monitoring, 

reporting and recordkeeping 

requirements needed to make the 

emissions limits contained in the 

Consent Agreement practically 

enforceable. Missouri held a public 

hearing for this SIP supplement on 

January 28, 2021 and made the 

supplement available for public review 

and comment from December 28, 2020 

through February 4, 2021. Missouri 

received supportive comments from 

Ameren. 

In addition, as explained above (and 

in more detail in the technical support 

document which is included in the 

docket for this action), the revision 

meets the substantive SIP requirements 

of the CAA, including section 110 and 

implementing regulations. 

III. What is the background for the 

EPA’s proposed actions? 

On June 2, 2010, the EPA revised the 

primary SO2 NAAQS, establishing a 

new 1-hour standard of 75 parts per 

billion (ppb).1 Under the EPA’s 

regulations at 40 CFR part 50, the 2010 

1-hour SO2 NAAQS is met at a 

monitoring site when the 3-year average 

of the annual 99th percentile of daily 

maximum 1-hour average 

concentrations is less than or equal to 

75 ppb (based on the rounding 

convention in 40 CFR part 50, appendix 

T).2 Ambient air quality monitoring data 

for the 3-year period must meet a data 

completeness requirement. A year meets 

data completeness requirements when 

all four quarters are complete, and a 

quarter is complete when at least 75 

percent of the sampling days for each 

quarter have complete data. A sampling 

day has complete data if 75 percent of 

the hourly concentration values, 

including State-flagged data affected by 

exceptional events which have been 

approved for exclusion by the 

Administrator, are reported.3

Upon promulgation of a new or 

revised NAAQS, the CAA requires the 

EPA to designate as nonattainment any 

area that does not meet (or that 

contributes to ambient air quality in a 

nearby area that does not meet) the 

NAAQS.4 On August 5, 2013, the EPA 

designated a portion of Jefferson 

County, Missouri, as nonattainment for 

the 2010 1-hour primary SO2 NAAQS, 

effective October 4, 2013.5 The 

designation was based on 2008–2010 

monitoring data in Herculaneum, 

Missouri, which monitored violations of 

the standard (see section III of this 

document for additional monitoring 

information). This action established an 

attainment date five years after the 

effective date for the areas designated as 

nonattainment for the 2010 SO2 NAAQS 

(i.e., by October 4, 2018). The State was 

also required to submit a SIP for the 

Jefferson County SO2 nonattainment 

area to the EPA that meets the 

requirements of CAA sections 110, 

172(c) and 191–192 within 18 months 

following the October 4, 2013, effective 

date of designation (i.e., by April 4, 

2015). The State of Missouri submitted 

the ‘‘Nonattainment Area Plan for the 

2010 1-Hour Sulfur Dioxide National 

Ambient Air Quality Standard Jefferson 

County Sulfur Dioxide Nonattainment 

Area’’ on June 5, 2015, and 

subsequently withdrew the plan on 

March 30, 2018, following several 

intervening steps discussed later in this 

section. 

On February 2, 2016, the State 

submitted a request asking the EPA to 

determine that the Jefferson County SO2

nonattainment area attained the 2010 1- 

hour primary SO2 NAAQS per the EPA’s 

Clean Data Policy. The clean data policy 

represents the EPA’s interpretation that 

certain planning-related requirements of 

part D of the Act, such as the attainment 

demonstration, reasonably available 

control measures (RACM), and 

reasonable further progress (RFP), are 

suspended for areas that are in fact 

attaining the NAAQS. A determination 

of attainment, or clean data 

determination, does not constitute a 

formal redesignation to attainment. If 

the EPA subsequently determines that 

an area is no longer attaining the 

standard, those requirements that were 

suspended by the clean data 

determination are once again due. 

On June 23, 2017, the EPA published 

a notice of proposed rulemaking to 

approve the State’s request for a clean 

data determination. The proposal was 

based on 2014–2016 monitoring data— 

the Mott Street monitor design value 

(dv) was 23 parts per billion (ppb)—and 

modeling data (a mix of 2013–2015 

actual and allowable emissions).6 7 After 

considering public comments received, 

the EPA published a Notice of Final 

Rulemaking (NFRM) approving the 

State’s request for a clean data 

determination in the Federal Register 

on September 13, 2017.8

On December 27, 2017, the State 

submitted a request for redesignation of 

the Jefferson County SO2 nonattainment 

area to attainment and a SIP revision 

containing a 10-year maintenance plan 

for the area. On May 15, 2018, the State 

submitted a clarifying letter that 

Appendix A (containing the emissions 

inventory for the area) and Appendix B 

(containing a Consent Agreement for 

certain sources in the area) of the SIP 

submittal should be considered part of 

the SIP revision request. On February 7, 

2019, and February 25, 2019, the State 

submitted supplemental modeling 

information to the EPA. On April 9, 

2021, the State submitted an addendum 

to the Consent Agreement which 

contains the emissions limits and 

monitoring, reporting, and 

recordkeeping requirements needed to 

determine compliance with the 

emissions limits for the covered sources. 

This proposal document discusses the 

EPA’s review of the redesignation 

request, the maintenance plan 

(including Consent Agreement and 

addendum), and the supplemental 

information and provides support for 

the EPA’s proposed approval of the 

request to redesignate the area to 

attainment and for proposed approval of 

the 10-year maintenance plan. 

Additional analysis of the redesignation 

request, 10-year maintenance plan, 

Consent Agreement and addendum, and 

supplemental modeling information is 


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9The TSD discusses the EPA’s review of the CAA 

section 107(d)(3)(E) redesignation criteria: (i) A 

determination of attainment; (iii) a determination 

that the improvement in air quality is due to 

permanent and enforceable reductions in emissions; 

and (iv) a fully approved maintenance plan as well 

CAA section 175A maintenance plan criteria: (1) 

Attainment inventory; (2) maintenance 

demonstration; and (3) continued monitoring. The 

EPA’s review of the remaining redesignation and 

maintenance plan criteria are sufficiently addressed 

in the preamble language to the NPRM. 

10See 57 FR 13498. 

11See 57 FR 18070. 

12https://www.epa.gov/sites/production/files/ 

2016-06/documents/20140423guidance_

nonattainment_sip.pdf. 

13See 2014 SO2 Guidance, at 56. 

provided in a Technical Support 

Document (TSD) included in the docket 

to this proposed rulemaking.9

IV. What are the criteria for 

redesignation? 

The CAA provides the requirements 

for redesignating a nonattainment area 

to attainment. Specifically, section 

107(d)(3)(E) of the CAA allows for 

redesignation of a nonattainment area 

provided that: (1) The Administrator 

determines that the area has attained the 

applicable NAAQS; (2) the 

Administrator has fully approved the 

applicable implementation plan for the 

area under section 110(k); (3) the 

Administrator determines that the 

improvement in air quality is due to 

permanent and enforceable reductions 

in emissions resulting from 

implementation of the applicable SIP 

and applicable federal air pollutant 

control regulations and other permanent 

and enforceable reductions; (4) the 

Administrator has fully approved a 

maintenance plan for the area as 

meeting the requirements of section 

175A; and (5) the State containing such 

area has met all requirements applicable 

to the area under section 110 and part 

D of the CAA. 

V. What is the EPA’s analysis of the 

request? 

The EPA’s evaluation of Missouri’s 

redesignation request and maintenance 

plan is based on consideration of the 

five redesignation criteria provided 

under CAA section 107(d)(3)(E) and 

relevant guidance. On April 16, 1992, 

the EPA provided guidance on 

redesignation in the General Preamble 

for the Implementation of title I of the 

CAA Amendments of 1990 and 

supplemented this guidance on April 

28, 1992.10 11 The EPA has provided 

further guidance on processing 

redesignation requests in several 

guidance documents. For the purposes 

of this action, the EPA will be 

referencing two of these documents: (1) 

The September 4, 1992 memo 

‘‘Procedures for Processing Requests to 

Redesignate Areas to Attainment’’ 

(Calcagni Memo); and (2) the EPA’s 

April 23, 2014 memorandum ‘‘Guidance 

for 1-Hour SO2 Nonattainment Area SIP 

Submissions’’ (2014 SO2 Guidance).12

Criterion (1)—The Jefferson County SO2

Nonattainment Area Has Attained the 

2010 1-Hour SO2 NAAQS 

For redesignating a nonattainment 

area to attainment, the CAA requires the 

EPA to determine that the area has 

attained the applicable NAAQS (CAA 

section 107(d)(3)(E)(i)). The EPA 

determined that the area attained the 

2010 1-hour SO2 NAAQS in its 

September 2017 NFRM approving the 

State’s request for a clean data 

determination meeting the requirements 

of CAA section 107(d)(3)(E)(i). That 

determination was primarily based on a 

modeling analysis of recent actual 

emissions for sources in and around the 

nonattainment area. As described 

further in the TSD for this action, the 

Supplemental modeling submitted by 

Missouri in February 2019 to support 

the redesignation request and 

maintenance plan is based on a 

modeling demonstration of permanent 

and enforceable emissions at sources in 

the nonattainment area that similarly 

demonstrates the area is attaining the 

standard. Therefore, the EPA’s 

determination that the area had 

achieved clean data is consistent with 

the proposed action to redesignate the 

area. 

Following the EPA’s determination 

that the area had achieved clean data, 

the EPA reviewed quality assured 

monitoring data recorded in the EPA’s 

Air Quality System (AQS) from the Mott 

Street monitoring station. The 3-year, 

2018–2020 design value for the Mott 

Street monitor is 14 ppb and continues 

to meet the 2010 1-hour SO2 NAAQS, as 

shown in Table 1. If the 3-year design 

value violates the NAAQS prior to the 

EPA acting in response to the State’s 

request, the EPA will not take final 

action to approve the redesignation 

request.13 As discussed in more detail 

later in this section, Missouri has 

committed to continue monitoring in 

this area in accordance with 40 CFR part 

58. 

TABLE 1—2015–2020 MOTT STREET MONITOR DATA (PARTS PER BILLION (ppb)); 99TH PERCENTILE (99%) AND 3-YEAR

DESIGN VALUE (dv) 

Site 

2015 

99th 

% 

2016 

99th 

% 

2017 

99th 

% 

2018 

99th 

% 

2019 

99th 

% 

2020 

99th 

% 

2015–2017 

dv 

2016–2018 

dv 

2017–2019 

dv 

2018–2020 

dv 

Mott Street ............................................ 38 13 18 12 12 17 23 14 14 14 

Criterion (2)—Missouri Has a Fully 

Approved SIP Under Section 110(k); 

and Criterion (5)—Missouri Has Met All 

Applicable Requirements Under Section 

110 and Part D of Title I of the CAA 

For redesignating a nonattainment 

area to attainment under a NAAQS, the 

CAA requires the EPA to determine that 

the State has met all applicable 

requirements for that NAAQS under 

section 110 and part D of title I of the 

CAA (CAA section 107(d)(3)(E)(v)) and 

that the State has a fully approved SIP 

under section 110(k) for that NAAQS for 

the area (CAA section 107(d)(3)(E)(ii)). 

The EPA proposes to find that Missouri 

has met all applicable SIP requirements 

for purposes of redesignation for the 

Jefferson County SO2 nonattainment 

area under section 110 of the CAA 

(general SIP requirements). 

Additionally, the EPA proposes to find 

that the Missouri SIP satisfies the 

criterion that it meets applicable SIP 

requirements for purposes of 

redesignation under part D of title I of 

the CAA in accordance with section 

107(d)(3)(E)(v). Further, the EPA 

proposes to determine that the SIP is 

fully approved with respect to all 

requirements applicable for the 2010 1- 

hour SO2 NAAQS for purposes of 

redesignation in accordance with 

section 107(d)(3)(E)(ii). In proposing to 

make these determinations, the EPA 

ascertained which requirements are 

applicable to the Jefferson County SO2

nonattainment area and, if applicable, 

that they are fully approved under 

section 110(k). 


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14See Reading, Pennsylvania, proposed and final 

rulemakings (61 FR 53174–53176, October 10, 

1996), (62 FR 24826, May 7, 2008); ClevelandAkron-Loraine, Ohio, final rulemaking (61 FR 

20458, May 7, 1996); and Tampa, Florida, final 

rulemaking at (60 FR 62748, December 7, 1995). See 

also the discussion on this issue in the Cincinnati, 

Ohio, redesignation (65 FR 37890, June 19, 2000), 

and in the Pittsburgh, Pennsylvania, redesignation 

(66 FR 50399, October 19, 2001). 

15See 57 FR 13498. 

16See 57 FR 13498, 13564. 

17 Id. 

18NRDC v. EPA, 571 F.3d 1245, 1252 (D.C. Cir. 

2009); Sierra Club v. EPA, 294 F.3d 155, 162 (D.C. 

Cir. 2002); Sierra Club v. EPA, 314 F.3d 735, 744 

(5th Cir. 2002); Sierra Club v. EPA, 375 F.3d 537 

(7th Cir. 2004). But see Sierra Club v. EPA, 793 F.3d 

656 (6th Cir. 2015). 

19Calcagni Memo at 6. 

a. The Jefferson County SO2

Nonattainment Area Has Met All 

Applicable Requirements Under Section 

110 and Part D of the CAA 

General SIP requirements. General SIP 

elements and requirements are 

delineated in section 110(a)(2) of title I, 

part A of the CAA. These requirements 

include, but are not limited to, the 

following: Submittal of a SIP that has 

been adopted by the State after 

reasonable public notice and hearing; 

provisions for establishment and 

operation of appropriate procedures 

needed to monitor ambient air quality; 

implementation of a source permit 

program; provisions for the 

implementation of part C requirements 

(Prevention of Significant Deterioration 

(PSD)) and provisions for the 

implementation of part D requirements 

(New Source Review (NSR) permit 

programs); provisions for air pollution 

modeling; and provisions for public and 

local agency participation in planning 

and emissions control rule 

development. 

Section 110(a)(2)(D) requires that SIPs 

contain certain measures to prevent 

sources in a State from significantly 

contributing to air quality problems in 

another State. To implement this 

provision, the EPA has required certain 

States to establish programs to address 

the interstate transport of air pollutants. 

The section 110(a)(2)(D) requirements 

for a State are not linked with a 

nonattainment area’s designation and 

classification in that State. The EPA 

believes that the requirements linked 

with a nonattainment area’s designation 

and classifications are the relevant 

measures to evaluate in reviewing a 

redesignation request. The transport SIP 

submittal requirements, where 

applicable, continue to apply to a State 

regardless of the designation of any one 

area in the State. Thus, the EPA does 

not believe that the CAA’s interstate 

transport requirements should be 

construed to be applicable requirements 

for purposes of redesignation. 

In addition, the EPA believes other 

section 110 elements that are neither 

connected with nonattainment plan 

submissions nor linked with an area’s 

attainment status are applicable 

requirements for purposes of 

redesignation. The area will still be 

subject to these requirements after the 

area is redesignated. The section 110 

and part D requirements which are 

linked with an area’s designation and 

classification are the relevant measures 

to evaluate in reviewing a redesignation 

request. This approach is consistent 

with the EPA’s existing policy on 

applicability (i.e., for redesignations) of 

conformity and oxygenated fuels 

requirements, as well as with section 

184 ozone transport requirements.14

Title I, part D, applicable SIP 

requirements. Section 172(c) of the CAA 

sets forth the basic requirements of 

attainment plans for nonattainment 

areas that are required to submit them 

pursuant to section 172(b). Subpart 5 of 

part D, which includes section 191 and 

192 of the CAA, establishes 

requirements for SO2, nitrogen dioxide 

and lead nonattainment areas. A 

thorough discussion of the requirements 

contained in sections 172(c) can be 

found in the General Preamble for 

Implementation of Title I.15

Section 172 and subpart 5 

requirements. Section 172(c)(1) requires 

the plans for all nonattainment areas to 

provide for the implementation of all 

RACM as expeditiously as practicable 

and to provide for attainment of the 

NAAQS. The EPA interprets this 

requirement to impose a duty on all 

nonattainment areas to consider all 

available control measures and to adopt 

and implement such measures as are 

reasonably available for implementation 

in each area as components of the area’s 

attainment demonstration. Under 

section 172, States with nonattainment 

areas must submit plans providing for 

timely attainment and meeting a variety 

of other requirements. 

The EPA’s longstanding interpretation 

of the nonattainment planning 

requirements of section 172 is that once 

an area is attaining the NAAQS, those 

requirements are not ‘‘applicable’’ for 

purposes of CAA section 107(d)(3)(E)(ii) 

and (v) and therefore need not be 

approved into the SIP before the EPA 

can redesignate the area. In the 1992 

General Preamble for Implementation of 

Title I, the EPA set forth its 

interpretation of applicable 

requirements for purposes of evaluating 

redesignation requests when an area is 

attaining a standard.16 The EPA noted 

that the requirements for RFP and other 

measures designed to provide for 

attainment do not apply in evaluating 

redesignation requests because those 

nonattainment planning requirements 

‘‘have no meaning’’ for an area that has 

already attained the standard.17 This 

interpretation was also set forth in the 

Calcagni Memo. The EPA’s 

understanding of section 172 also forms 

the basis of its Clean Data Policy, which 

was articulated with regard to the 2010 

1-hour SO2 NAAQS in the EPA’s 2014 

SO2 Guidance, and suspends a State’s 

obligation to submit most of the 

attainment planning requirements that 

would otherwise apply, including an 

attainment demonstration and planning 

SIPs to provide for RFP, RACM, and 

contingency measures under section 

172(c)(9). Courts have upheld the EPA’s 

interpretation of section 172(c)(1) for 

‘‘reasonably available’’ control measures 

and control technology as meaning only 

those controls that advance attainment, 

which precludes the need to require 

additional measures where an area is 

already attaining.18

Therefore, because the Jefferson 

County SO2 nonattainment area is 

currently attaining the 2010 1-hour SO2

NAAQS, no additional measures are 

needed to provide for attainment, and 

section 172(c)(1) requirements for an 

attainment demonstration and RACM 

are not part of the ‘‘applicable 

implementation plan’’ required to have 

been approved prior to redesignation 

per CAA section 107(d)(3)(E)(ii) and (v). 

The other section 172 requirements that 

are designed to help an area achieve 

attainment—the section 172(c)(2) 

requirement that nonattainment plans 

contain provisions promoting 

reasonable further progress, the 

requirement to submit the section 

172(c)(9) contingency measures, and the 

section 172(c)(6) requirement for the SIP 

to contain control measures necessary to 

provide for attainment of the NAAQS— 

are also not required to be approved as 

part of the ‘‘applicable implementation 

plan’’ for purposes of satisfying CAA 

section 107(d)(3)(E)(ii) and (v). 

Section 172(c)(3) requires submission 

and approval of a comprehensive, 

accurate, and current inventory of actual 

emissions. The requirement for an 

emissions inventory can be satisfied by 

meeting the inventory requirements of 

the maintenance plan.19 However, when 

the State withdrew its attainment plan 

for the area in March 2018, it did not 

withdraw the baseline emissions 

inventory submitted with that plan. On 

November 23, 2018, the EPA published 

a notice of proposed rulemaking in the 

Federal Register proposing to approve 

that the State met the section 172(c)(3) 


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20See 83 FR 59348. 

21See 84 FR 3703. 

22See 80 FR 31844. 

23See 78 FR 57267. 

24See Wall v. EPA, 265 F.3d 426 (6th Cir. 2001) 

(upholding this interpretation); see also 60 FR 

62748 (December 7, 1995) (redesignation of Tampa, 

Florida). 

25See 40 CFR 93.102(b)(1), (2)(v). 

26See EPA’s final Technical Support Document 

(TSD) for the Jefferson County SO2 Nonattainment 

Area, in the docket for EPA’s initial round of 2010 

SO2 designations at EPA–HQ–OAR–2012–0233– 

0318. 

27Case No. 4:10–cv–01895–JCH on December 21, 

2011. 

requirement to submit an emissions 

inventory for the Jefferson County SO2

nonattainment area.20 On February 13, 

2019, the EPA published a final 

rulemaking in the Federal Register 

approving the State’s emissions 

inventory for the Jefferson County SO2

nonattainment area.21

Section 172(c)(4) requires the 

identification and quantification of 

allowable emissions for major new and 

modified stationary sources to be 

allowed in an area, and section 172(c)(5) 

requires source permits for the 

construction and operation of new and 

modified major stationary sources 

anywhere in the nonattainment area. 

The State has an approved 

nonattainment NSR program.22

Regardless, the State has demonstrated 

that the Jefferson County SO2

nonattainment area will be able to 

maintain the NAAQS without part D 

NSR in effect. Missouri’s PSD program 

will be in effect in the Jefferson County 

SO2 nonattainment area upon 

redesignation to attainment. 

Section 172(c)(7) requires the SIP to 

meet the applicable provisions of 

section 110(a)(2). As noted above, the 

EPA believes the Missouri SIP meets the 

requirements of section 110(a)(2) 

applicable for purposes of 

redesignation. 

Section 176 conformity requirements. 

Section 176(c) of the CAA requires 

States to establish criteria and 

procedures to ensure that federally 

supported or funded projects conform to 

the air quality planning goals in the 

applicable SIP. The requirement to 

determine conformity applies to 

transportation plans, programs, and 

projects that are developed, funded, or 

approved under title 23 of the United 

States Code (U.S.C.) and the Federal 

Transit Act (transportation conformity) 

as well as to all other federally 

supported or funded projects (general 

conformity). State transportation 

conformity SIP revisions must be 

consistent with federal conformity 

regulations relating to consultation, 

enforcement, and enforceability that the 

EPA promulgated pursuant to its 

authority under the CAA. 

Missouri has an approved general 

conformity SIP.23 Moreover, the EPA 

interprets the conformity SIP 

requirements as not applying for 

purposes of evaluating a redesignation 

request under section 107(d) because, 

like other requirements listed above, 

State conformity rules are still required 

after redesignation and federal 

conformity rules apply where State 

rules have not been approved.24

As noted in the 2014 SO2 Guidance, 

transportation conformity is required 

under CAA section 176(c) to ensure that 

federally supported highway and transit 

project activities are consistent with 

(‘‘conform to’’) the purpose of the SIP. 

Transportation conformity applies to 

areas that are designated nonattainment, 

and those areas redesignated to 

attainment (‘‘maintenance areas’’ with 

plans developed under CAA section 

175A) for transportation-related criteria 

pollutants. Due to the relatively small, 

and decreasing, amounts of sulfur in 

gasoline and on-road diesel fuel, the 

EPA’s conformity rules provide that 

they do not apply to SO2 unless either 

the EPA Regional Administrator or the 

director of the State air agency has 

found that transportation-related 

emissions of SO2 as a precursor are a 

significant contributor to a PM2.5

nonattainment problem, or if the SIP has 

established an approved or adequate 

budget for such emissions as part of the 

RFP, attainment or maintenance 

strategy.25 Neither the EPA nor Missouri 

has made such a finding for 

transportation related emissions of SO2

for the Jefferson County SO2

nonattainment area. 

For these reasons, the EPA proposes 

to find that Missouri has satisfied all 

applicable requirements for purposes of 

redesignation of the Jefferson County 

SO2 nonattainment area under section 

110 and part D of title I of the CAA. 

b. The Jefferson County SO2

Nonattainment Area Has a Fully 

Approved Applicable SIP Under Section 

110(k) of the CAA 

The EPA has fully approved the 

applicable Missouri SIP for the Jefferson 

County SO2 nonattainment area under 

section 110(k) of the CAA for all 

requirements applicable for purposes of 

redesignation. As indicated above, the 

EPA believes that the section 110 

elements that are neither connected 

with nonattainment plan submissions 

nor linked to an area’s attainment status 

are not applicable requirements for 

purposes of redesignation. The EPA has 

approved all part D requirements 

applicable under the 2010 SO2 NAAQS, 

as identified above, for purposes of this 

redesignation. 

Criterion (3)—The Air Quality 

Improvement in the Jefferson County 

SO2 Nonattainment Area Is Due to 

Permanent and Enforceable Reductions 

in Emissions 

For redesignating a nonattainment 

area to attainment, the CAA requires the 

EPA to determine that the air quality 

improvement in the area is due to 

permanent and enforceable reductions 

in emissions resulting from 

implementation of the SIP, applicable 

federal air pollution control regulations, 

and other permanent and enforceable 

reductions (CAA section 

107(d)(3)(E)(iii)). The EPA proposes to 

find that Missouri has demonstrated 

that the observed air quality 

improvement in the Jefferson County 

SO2 nonattainment area is due to 

permanent and enforceable reductions 

in emissions. Specifically, the EPA 

considers the shutdown of the Doe Run 

Herculaneum primary lead smelter (lead 

smelter), identified as the key 

contributor to the SO2 NAAQS 

violations at the Mott Street monitor, to 

be both permanent and enforceable.26

As stated on page 10 of the Calcagni 

Memo, ‘‘Emission reductions from 

source shutdowns can be considered 

permanent and enforceable to the extent 

that those shutdowns have been 

reflected in the SIP and all applicable 

permits have been modified 

accordingly.’’ The lead smelter was 

limited to the terms of a consent decree 

entered by Doe Run, Missouri, and the 

EPA in the United States District Court 

in the Eastern District of Missouri (2011 

Consent Decree).27 On December 31, 

2013, pursuant to the terms of the 2011 

Consent Decree, the lead smelter 

permanently ceased operations of the 

sintering plant. The 2011 Consent 

Decree also required the lead smelter to 

permanently cease smelting operations 

and retire the blast furnaces by April 30, 

2014; the lead smelter ceased operation 

of the blast furnaces on December 31, 

2013, concurrently with the cessation of 

operation of the sintering plant. In 

addition, the Consent Decree required 

Doe Run to surrender air permits for the 

emission units required to be 

permanently shut down by the Consent 

Decree. Given the well-established 

correlation of much lower SO2

emissions at the Mott Street monitor 

during periods when the lead smelter 

has been shut down, the EPA 


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28See 2014 SO2 Guidance, at 66. 

anticipates that the SO2 NAAQS will 

continue to be attained. See Table 1 for 

recent monitoring data trends at this 

monitor. 

Additionally, the State entered into a 

Consent Agreement with Ameren 

Missouri (Ameren), included as 

Appendix B to the maintenance plan 

submission, limiting the SO2 emissions 

from three Ameren facilities. One 

facility, Ameren-Rush Island Energy 

Center (Rush Island), is located within 

the nonattainment area boundary. The 

other two facilities, Ameren Meramec 

Energy Center (Meramec) and Ameren 

Labadie Energy Center (Labadie) are 

located outside of the nonattainment 

area boundary. The Consent Agreement 

emission limits are provided in Table 2. 

TABLE 2—AMEREN/MISSOURI CONSENT AGREEMENT SO2 EMISSION LIMITS

Source 

Emission limit 

per source 

(pounds per hour) 

Averaging time 

Labadie .............................................................................................................................................. 40,837 24-hr block average. 

Meramec ............................................................................................................................................ 7,371 24-hr block average. 

Rush Island ....................................................................................................................................... 13,600 24-hr block average. 

Because it is located inside of the 

Jefferson County SO2 nonattainment 

area, the State modeled Rush Island at 

a constant emission rate of 14,600 lbs 

SO2/hr for every hour of the year in all 

five years (2013–2017) of the modeling 

analysis. This modeled emission rate 

corresponds to the facility’s enforceable 

24-hour block average limit for hourly 

SO2 emissions of 13,600 lbs SO2/hr 

when accounting for variability. The 

State modeled Meramec and Labadie as 

nearby sources in accordance with the 

code of federal regulations (CFR) 40 CFR 

part 51, appendix W, Guideline on Air 

Quality Models. That is, the State 

modeled Meramec and Labadie’s 

permitted/allowable emission rate from 

the Consent Agreement with actual 

temporally varying heat input levels. 

Please see the TSD for details of the 

modeling inputs and additional 

discussion of the air quality modeling. 

The modeling results demonstrate 

attainment and project continued 

maintenance of the NAAQS, and the 

TSD also contains discussion of the 

EPA’s review of the modeling. 

Therefore, the EPA is proposing to 

find that the air quality improvement in 

the Jefferson County SO2 nonattainment 

area is due to permanent and 

enforceable reductions in emissions. 

Criterion (4)—The Jefferson County SO2

Nonattainment Area Has a Fully 

Approved Maintenance Plan Pursuant 

to Section 175A of the CAA 

To redesignate a nonattainment area 

to attainment, the CAA requires the EPA 

to determine that the area has a fully 

approved maintenance plan pursuant to 

section 175A of the CAA (CAA section 

107(d)(3)(E)(iv)). In conjunction with its 

request to redesignate the Jefferson 

County SO2 nonattainment area to 

attainment for the 2010 1-hour SO2

NAAQS, the State submitted a SIP 

revision to provide for the maintenance 

of the 2010 1-hour SO2 NAAQS for at 

least 10 years after the effective date of 

redesignation to attainment. The EPA is 

proposing to find that this maintenance 

plan for the area meets the requirements 

for approval under section 175A of the 

CAA. 

a. What is required in a maintenance 

plan? 

CAA section 175A sets forth the 

elements of a maintenance plan for 

areas seeking redesignation from 

nonattainment to attainment. Under 

section 175A, the plan must 

demonstrate continued attainment of 

the applicable NAAQS for at least 10 

years after the Administrator approves a 

redesignation request to attainment. 

Eight years after the redesignation, the 

State must submit a revised 

maintenance plan demonstrating that 

attainment will continue to be 

maintained for the 10 years following 

the initial 10-year period. To address 

the possibility of future NAAQS 

violations, the maintenance plan must 

contain contingency measures as the 

EPA deems necessary to assure prompt 

correction of any future 2010 1-hour 

SO2 violations. The Calcagni Memo 

provides further guidance on the 

content of a maintenance plan, 

explaining that a maintenance plan 

should address five requirements: The 

attainment emissions inventory, 

maintenance demonstration, 

monitoring, verification of continued 

attainment, and a contingency plan. As 

is discussed more fully later in this 

section, the EPA is proposing to 

determine that Missouri’s maintenance 

plan includes all the necessary 

components and is thus proposing to 

approve it as a revision to the Missouri 

SIP. 

b. Attainment Emissions Inventory 

As part of a State’s maintenance plan, 

the air agency should develop an 

attainment inventory to identify the 

level of emissions in the affected area 

which is enough to attain and maintain 

the SO2 NAAQS.28 The EPA is 

proposing to approve that Missouri has 

met this requirement through modeling 

of permanent and enforceable emissions 

limits that will result in continued 

attainment and maintenance of the 

NAAQS. Missouri also provided 

emissions inventories as part of the 

maintenance plan. Specifically, 

Missouri selected 2014 as the 

attainment emissions inventory year for 

developing an emissions inventory for 

SO2 in the nonattainment area through 

2030. Please see the TSD included in 

the docket for this action for details of 

the base year, attainment year and 

future year emissions inventories and 

the EPA’s review of these inventories. 

The TSD also details the EPA’s review 

of the modeling demonstration provided 

by Missouri which forms the basis for 

the EPA’s approval of this maintenance 

plan requirement. 

c. Maintenance Demonstration 

The Calcagni memo describes two 

ways for a State to demonstrate 

maintenance of the NAAQS for a period 

of at least 10 years following the 

redesignation of the area: (1) The State 

can show that future emissions of a 

pollutant will not exceed the level of the 

attainment inventory, or (2) the State 

can model to show that the future mix 

of sources and emission rates will not 

cause a violation of the standard. The 

memo goes on to say that areas that are 

required to model to demonstrate 

attainment of the standard should 

complete the same level of modeling to 

demonstrate that the permanent and 

enforceable emissions are enough to 

maintain the standard. The State 

performed several modeling iterations to 

demonstrate that the standard will be 

maintained. In its February 7, 2019, and 

February 25, 2019, supplemental 


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29See Missouri’s 2019 Ambient Monitoring 

Network Plan contained in the docket for this 

action. 30The industrial monitors are not classified as 

SLAMS nor as Data Requirements Rule monitors. 31The Consent Agreement is included as 

Appendix B of the maintenance plan. 32The EPA approved the State’s 2019 Ambient 

Monitoring Network Plan via letter dated January 8, 

2021. Missouri’s 2019 Plan and the EPA’s approval 

letter are included in the docket for this action. 

33However, the EPA notes that the industrial 

source monitors are operated in accordance with an 

approved industrial source monitoring quality 

assurance project plan (QAPP) and quality 

management plan (QMP). The relevant QAPP and 

QMP documents are included in the docket for this 

action. The QMP outlines the quality assurance 

audits to be conducted by Missouri staff to ensure 

the industrial monitoring data is collected in a 

manner equivalent to SLAMS and may be used to 

determine NAAQS compliance. See Missouri’s 2016 

Ambient Monitoring Network Plan contained in the 

docket for this action for more information. 

34The EPA promulgated the DRR August 21, 

2015. The DRR requires air agencies to characterize 

air quality, either by monitoring or modeling, 

around sources that emit 2,000 tons per year (tpy) 

or more of SO2. The requirement for air quality 

characterization near a source may be avoided by 

adopting enforceable emission limits that ensure 

that the source will not emit more than 2,000 tpy 

of SO2. On January 15, 2016, the State submitted 

a final list identifying the sources in the State 

around which SO2 air quality will be characterized. 

Rush Island was not included in the list because it 

is within the Jefferson County SO2 nonattainment 

area. Starting in 2016, Missouri’s annual monitoring 

network plans state that monitoring around Rush 

Island is being conducted by agreement between the 

State and Ameren. 

35Any change in the operational status or 

location of the Mott Street monitor must be 

approved by the Regional Administrator in 

accordance with the requirements of 40 CFR part 

58. 

36The EPA would also need to approve the 

monitor changes as part of the State’s annual 

monitoring network plan. 

37See 2014 SO2 Guidance at 67–68. 

38The EPA last determined that Missouri’s SIP 

was sufficient to meet the requirements of section 

110(a)(2)(E)(i) of the CAA on March 22, 2018 (83 

FR 12496). 

modeling, Missouri has demonstrated 

maintenance by modeling all sources 

inside of the nonattainment area at their 

permanent, enforceable, allowable 

emission rates, nearby sources at their 

permanent, enforceable, allowable 

emission rates (with actual operating 

conditions for 2013–2017), and other 

sources addressed through the use of a 

background concentration. The EPA 

proposes that the supplemental 

modeling provided by Missouri 

demonstrates the standard will be 

attained and maintained for at least 10 

years following redesignation of the 

area, consistent with the second method 

outlined in the Calcagni memo by 

which a State may demonstrate 

maintenance of the NAAQS. Please see 

the TSD for details of the modeling 

inputs, results and the EPA’s review of 

them. The EPA is proposing to approve 

Missouri’s maintenance plan including 

the supplemental modeling and a 

background concentration revised by 

the EPA as meeting the maintenance 

demonstration requirement. 

d. Monitoring Network 

Missouri has committed to continue 

operating the ‘‘appropriate SO2 network 

in the Jefferson County nonattainment 

area’’ in accordance with the 

requirements of 40 CFR part 58, and 

approved annual monitoring network 

plans, to verify the attainment status of 

the area. The State committed to quality 

assure the data in accordance with 40 

CFR part 58 and submit the data to the 

EPA’s air quality system (AQS). The 

maintenance plan, consistent with the 

State’s 2019 annual ambient monitoring 

network plan, indicate that the Mott 

Street monitor is the only SLAMS or 

SLAMS like monitor operational in the 

nonattainment area.29

There are also three industrial source 

monitors located around Rush Island.30

These monitors are required per the 

Consent Agreement between Ameren 

and the State.31 The Consent Agreement 

required the monitors to start operation 

by December 2015 and operate 12 

consecutive quarters (3 years). The 

industrial source monitors have also 

been identified in the State’s annual 

ambient monitoring network plans since 

2015.32 The Consent Agreement also 

requires certain responses by Ameren if 

elevated monitoring values are recorded 

at any of the industrial source monitors. 

The maintenance plan and Consent 

Agreement requires Ameren to operate 

the industrial source monitors for a 

minimum of 12 consecutive quarters. 

The maintenance plan and Consent 

Agreement do not establish that the 

monitors must be operated as SLAMSlike monitors which would make them 

subject to the discontinuation 

requirements of 40 CFR part 58.33

However, because the EPA is proposing 

to approve the requirement to operate 

the industrial source monitors, and that 

the contingency measures may be 

triggered by data recorded by these 

industrial source monitors, as contained 

in the Consent Agreement, into the SIP, 

the monitors must operate until the EPA 

approves a revision to the SIP to remove 

the monitoring requirements. 

Because the industrial source 

monitors were not identified by the 

State as necessary to meet the 

requirements of the Data Requirements 

Rule (DRR) they are not subject to the 

requirements of 40 CFR 51.1203(c).34

The 2018 annual monitoring network 

plan commits the State to ‘‘continuing 

to work with Ameren to collect quality 

assured SO2 ambient air quality data 

and meteorological data near the Rush 

Island power station to provide 

quantifiable and useful information to 

supplement the ongoing 1-hour SO2

NAAQS implementation process.’’ 

Because there is no regulatory 

obligation, or commitment from Ameren 

or the State to operate the industrial 

source monitors as SLAMS-like or for 

the duration of the maintenance period, 

the EPA is proposing to approve that the 

State is meeting its obligation to 

continue monitoring in the area, and 

verify ongoing attainment and 

maintenance, via operation of the Mott 

Street SLAMS monitor and that 

Missouri’s maintenance plan meets the 

‘‘Monitoring Network’’ requirement.35

However, as previously noted, because 

the EPA is proposing to approve the 

Consent Agreement into the SIP, 

continued operation of the industrial 

source monitors will be required until 

the EPA approves a revision to the SIP 

to remove the monitoring 

requirements.36 The available recent 

monitoring data from these industrial 

monitors is included in the TSD 

associated with this action. 

e. Verification of Continued Attainment 

Each air agency should ensure that it 

has the legal authority to implement and 

enforce all measures necessary to attain 

and maintain the 2010 SO2 NAAQS. 

The air agency’s submittal should 

indicate how it will track the progress 

of the maintenance plan for the area 

either through air quality monitoring or 

modeling.37

Missouri has the legal authority to 

enforce and implement the maintenance 

plan for the Jefferson County 2010 SO2

nonattainment area. This includes the 

authority to adopt, implement, and 

enforce any subsequent emissions 

control contingency measures 

determined to be necessary to correct 

future SO2 attainment problems.38 As 

noted, the State will track the progress 

of the maintenance plan by continuing 

to operate the Mott Street monitor. 

Additionally, the State committed to 

provide future inventory updates to 

track emissions during the 10-year 

maintenance period. State Regulation 10 

CSR 10–6.110, Reporting Emission Data, 

Emission Fees, and Process Information, 

(which is SIP approved) requires that all 

installations with a construction or 

operating permit report its annual 

emissions to the State. The methods for 

calculating and reporting emissions are 

detailed in each installation’s applicable 

permit. The data collected on emissions 

inventory questionnaires from permitted 

sources form the basis of the point 

source emissions inventory that is 


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39This information is available to the EPA or 

members of the public upon request from the State 

of Missouri. 

40See Missouri’s 2015 and 2016 annual 

monitoring network plans contained in the docket 

for this action for more information about the siting 

of the monitors around Rush Island. 

compiled annually.39 In addition, in 

compliance with the EPA’s Air 

Emissions Reporting Requirements [80 

FR 8787], Missouri develops a 

comprehensive emissions inventory of 

point, area, and mobile sources every 3 

years. This triennial inventory compiled 

by the State is contained in the EPA’s 

national emissions inventory (NEI) 

which is made publicly available every 

3 years. For these reasons, the EPA is 

proposing to find that Missouri’s 

maintenance plan meets the 

‘‘Verification of Continued Attainment’’ 

requirement. 

f. Contingency Measures in the 

Maintenance Plan 

Section 175A of the CAA requires that 

a maintenance plan include such 

contingency measures as the EPA deems 

necessary to assure that the State will 

promptly correct a violation of the 

NAAQS that occurs after redesignation. 

The maintenance plan should identify 

the contingency measures to be adopted, 

a schedule and procedure for adoption 

and implementation, and a time limit 

for action by the State. A State should 

also identify specific indicators to be 

used to determine when the 

contingency measures need to be 

implemented. The maintenance plan 

must also include a requirement that a 

State will implement all measures with 

respect to control of the pollutant that 

were contained in the SIP before 

redesignation of the area to attainment 

in accordance with section 175A(d). 

The contingency plan includes a 

triggering mechanism to determine 

when contingency measures are needed 

and a process of developing and 

implementing appropriate control 

measures. The triggering mechanisms 

contained in the maintenance plan and 

Consent Agreement are based on 

monitoring data from the Mott Street 

monitor and the industrial source 

monitors around the Ameren Rush 

Island facility. The EPA finds it 

appropriate to rely on monitoring data 

to trigger the contingency plan because 

the Mott Street monitor is being relied 

upon to demonstrate continued 

maintenance in the area as discussed in 

the Monitoring Network section of this 

document. Additionally, the industrial 

source monitors were sited consistent 

with relevant EPA guidance to capture 

maximum impacts from the Rush Island 

plant.40 Because the Rush Island plant 

is the largest remaining source in the 

maintenance area, the EPA agrees that 

monitoring around the Rush Island 

plant would be the best indicator of any 

potential future air quality issues in the 

maintenance area and thereby 

represents a reasonable triggering 

mechanism for the State’s contingency 

plan. 

The State listed two types of triggers 

of its contingency plan. The first, a 

‘‘warning level response,’’ will be 

triggered by a 99th percentile of daily 

maximum 1-hour average SO2

concentrations greater than 79 ppb in a 

single calendar year in the Jefferson 

County maintenance area. The second, 

an ‘‘action level response,’’ will be 

triggered if a violation of the NAAQS is 

recorded in the Jefferson County 

maintenance area, specifically if the 3- 

year average of annual 99th percentile 

daily maximum 1-hour concentrations 

is 76 ppb or higher. 

If the warning level response is 

triggered, a study must be completed to 

determine whether the monitored SO2

value indicates a trend toward higher 

concentrations in the Jefferson County 

maintenance area. The study will 

evaluate whether the trend, if any, is 

likely to continue. The study shall be 

completed as expeditiously as possible, 

but no later than 24 months after the 

State has determined that a warning 

level response has been triggered. It 

should be noted that the EPA does not 

require a State to implement 

contingency measures when occasional 

exceedances are recorded. 

If the action level response is 

triggered and is not found to be due to 

an exceptional event as defined at 40 

CFR part 50.1(j), measures to address 

the violation shall be implemented as 

expeditiously as possible, but no later 

than 24 months after quality assured 

ambient data that has been entered into 

the AQS database indicating that this 

trigger has occurred. If a new measure 

or control is already promulgated and 

scheduled to be implemented at the 

federal or State level, and that measure 

or control is determined to be enough to 

address the upward trend in ambient 

SO2 concentrations within the 

maintenance area, additional local 

measures may be unnecessary. 

Furthermore, Missouri will submit to 

the EPA an analysis demonstrating the 

proposed action level response 

measures are adequate to return the area 

to attainment. Contingency measures 

considered will be based on an analysis 

of the cause of the elevated ambient SO2

concentrations from the entity(ies) 

likely to be contributing to the elevated 

concentrations. Measures may include 

improvements to existing control 

devices, addition of secondary control 

devices or improvements in 

housekeeping and maintenance, among 

other measures. It is not possible to 

develop a comprehensive list of 

contingency measures that can address 

all possible violations until the cause of 

the elevated concentrations is known. 

Any contingency measures 

implemented will require a compliance 

plan and expeditious compliance 

timeline from the entity(ies) involved. 

The EPA is proposing to find that 

Missouri’s maintenance plan meets the 

‘‘Contingency Measures’’ requirement. 

In addition to the contingency plan 

contained in the maintenance plan, the 

Consent Agreement contains specific 

contingency plan triggers and 

requirements for Ameren. Specifically, 

the Consent Agreement requires that 

Ameren perform an air quality analysis 

if any elevated monitoring values are 

recorded (one occurrence of a measured 

SO2 concentration that exceeds 75 ppb 

for one hour) at any of the three 

industrial source monitors. Ameren 

must submit this air quality analysis 

including the monitored information 

and any relevant operational 

information to Missouri within a 

specified time frame. 

If through discussion of the air quality 

analysis, it is established that the 

elevated monitoring values were 

attributable to Ameren Rush Island, 

Ameren would provide the State with 

proposed potential mitigation measures, 

SO2 emissions limitations, and a 

compliance schedule. 

The EPA proposes to conclude that 

the maintenance plan adequately 

addresses the five basic components of 

a maintenance plan: The attainment 

emissions inventory, maintenance 

demonstration, monitoring, verification 

of continued attainment, and a 

contingency plan. Therefore, the EPA 

proposes to find that the maintenance 

plan SIP revision submitted by Missouri 

for the Jefferson County 2010 SO2

nonattainment area meets the 

requirements of section 175A of the 

CAA and proposes to approve the plan. 

VI. What are the actions the EPA is 

proposing to take? 

The EPA is proposing to approve the 

maintenance plan for the Jefferson 

County 2010 SO2 1-hour NAAQS 

nonattainment area into the Missouri 

SIP (as compliant with CAA section 

175A). The maintenance plan 

demonstrates that the area will continue 

to maintain the 2010 1-hour SO2

NAAQS and includes a process to 

develop contingency measures to 

remedy any future violations of the 2010 


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1-hour SO2 NAAQS and procedures for 

evaluation of potential violations. 

Additionally, the EPA is proposing to 

determine that the Jefferson County 

2010 SO2 1-hour NAAQS nonattainment 

area has met the criteria under CAA 

section 107(d)(3)(E) for redesignation 

from nonattainment to attainment for 

the 2010 1-hour SO2 NAAQS. On this 

basis, the EPA is proposing to approve 

Missouri’s redesignation request for the 

area. Final approval of Missouri’s 

redesignation request would change the 

legal designation of the portion of 

Jefferson County designated 

nonattainment at 40 CFR part 81 to 

attainment for the 2010 1-hour SO2

NAAQS. 

VII. Environmental Justice Concerns 

When the EPA establishes a new or 

revised NAAQS, the CAA requires the 

EPA to designate all areas of the U.S. as 

either nonattainment, attainment, or 

unclassifiable. Area designations 

address environmental justice concerns 

by ensuring that the public is properly 

informed about the air quality in an 

area. If an area is designated in 

nonattainment of the NAAQS, the CAA 

provides for the EPA to redesignate the 

area to attainment upon a demonstration 

by the state authority that air quality is 

attaining the NAAQS and will continue 

to maintain the NAAQS in order to 

ensure that all those residing, working, 

attending school, or otherwise present 

in those areas are protected, regardless 

of minority and economic status. 

VIII. Incorporation by Reference 

In this document, the EPA is 

proposing to amend regulatory text that 

includes incorporation by reference. In 

accordance with the requirements of 1 

CFR 51.5, the EPA is proposing to 

incorporate by reference the Missouri 

State Implementation Plan described in 

the proposed amendments to 40 CFR 

part 52 set forth below. The EPA has 

made, and will continue to make, these 

materials generally available through 

www.regulations.gov and at the EPA 

Region 7 Office (please contact the 

person identified in the FOR FURTHER

INFORMATION CONTACT section of this 

preamble for more information). 

IX. Statutory and Executive Order 

Reviews 

Under the Clean Air Act (CAA), the 

Administrator is required to approve a 

SIP submission that complies with the 

provisions of the Act and applicable 

Federal regulations. 42 U.S.C. 7410(k); 

40 CFR 52.02(a). Thus, in reviewing SIP 

submissions, the EPA’s role is to 

approve State choices, if they meet the 

criteria of the CAA. Accordingly, this 

action merely approves State law as 

meeting Federal requirements and does 

not impose additional requirements 

beyond those imposed by State law. 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 the 

National Technology Transfer and 

Advancement Act (NTTA) because this 

rulemaking does not involve technical 

standards; and 

• This action does not have 

disproportionately high and adverse 

human health or environmental effects 

on minority populations, low-income 

populations and/or indigenous peoples, 

as specified in Executive Order 12898 

(59 FR 7629, February 16, 1994). The 

analysis for this determination is 

contained in Section VII of this action, 

‘‘Environmental Justice Concerns.’’ 

The SIP is not approved to apply on 

any Indian reservation land or in any 

other area where the 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 

40 CFR Part 52 

Environmental protection, Air 

pollution control, Incorporation by 

reference, Maintenance plan, 

Redesignation, Sulfur oxides. 

40 CFR Part 81 

Environmental protection, Air 

pollution control, Designations, 

Redesignation, Intergovernmental 

relations, Reporting and recordkeeping 

requirements, Sulfur oxides. 

Dated: June 22, 2021. 

Edward H. Chu, 

Acting Regional Administrator, Region 7. 

For the reasons stated in the 

preamble, the EPA proposes to amend 

40 CFR parts 52 and 81 as set forth 

below: 

PART 52—APPROVAL AND 

PROMULGATION OF 

IMPLEMENTATION PLANS 

■ 1. The authority citation for part 52 

continues to read as follows: 

Authority: 42 U.S.C. 7401 et seq. 

Subpart AA—Missouri 

■ 2. In § 52.1320: 

■ a. The table in paragraph (d) is 

amended by adding the entry ‘‘(34)’’ in 

numerical order. 

■ b. The table in paragraph (e) is 

amended by adding the entry ‘‘(79)’’ in 

numerical order. 

The additions read as follows: 

§ 52.1320 Identification of plan. 

* * * * * 

(d) * * * 


lotter on DSK11XQN23PROD with PROPOSALS1
34186 Federal Register / Vol. 86, No. 122 / Tuesday, June 29, 2021 / Proposed Rules 

EPA-APPROVED MISSOURI SOURCE-SPECIFIC PERMITS AND ORDERS

Name of source Order/permit No. State effective 

date EPA approval date Explanation 

*******

(34) Ameren Missouri ............. Consent Agreement and Addendum No. APCP–2015– 

034.

12/14/2020 [Date of publication of the 

final rule in the Federal 

Register], [Federal Register citation of the final 

rule].

(e) * * * 

EPA-APPROVED MISSOURI NONREGULATORY SIP PROVISIONS

Name of nonregulatory SIP 

revision 

Applicable 

geographic or 

nonattainment area 

State submittal 

date EPA approval date Explanation 

*******

(79) Jefferson County 1-hour 

SO2 NAAQS Maintenance Plan 

and Supplemental Modeling 

Analyses.

Jefferson County 12/27/17; 5/15/ 

18; 2/7/19; 2/ 

25/19; and 4/ 

9/21 

[Date of publication of the final 

rule in the Federal Register], 

[Federal Register citation of 

the final rule] 

This action approves the Maintenance Plan and the Supplemental Modeling Analyses for 

the Jefferson County area. 

■ 3. In § 52.1343, add paragraph (c) to 

read as follows: 

§ 52.1343 Control strategy: Sulfur dioxide. 

* * * * * 

(c) Redesignation to attainment. EPA 

has determined, as of [date of 

publication of the final rule in the 

Federal Register], that the Jefferson 

County 2010 SO2 nonattainment area is 

redesignated to attainment of the 2010 

SO2 1-hour National Ambient Air 

Quality Standard (NAAQS) in 

accordance with the requirements of 

Clean Air Act (CAA) section 107(d)(3) 

and has approved its maintenance plan 

and supplemental modeling 

demonstration analyses as meeting the 

requirements of CAA section 175A. 

PART 81—DESIGNATION OF AREAS 

FOR AIR QUALITY PLANNING 

PURPOSES 

■ 4. The authority citation for part 81 

continues to read as follows: 

Authority: 42 U.S.C. 7401, et seq. 

Subpart C—Section 107 Attainment 

Status Designations 

■ 5. In § 81.326, revise the entry 

‘‘Jefferson County, MO’’ in the table 

entitled ‘‘Missouri—2010 Sulfur 

Dioxide NAAQS [Primary]’’ to read as 

follows: 

§ 81.326 Missouri. 

* * * * * 

MISSOURI—2010 SULFUR DIOXIDE NAAQS 

[Primary] 

Designated area 1

Designation 

Date 2 Type 

*******

Jefferson County, MO [Date 30 days after date of publication of 

the final rule in the Federal Register] 

Attainment. 

Jefferson County (part): ........................................................................................

That portion within Jefferson County described by connecting the following 

four sets of UTM coordinates moving in a clockwise manner: 

(Herculaneum USGS Quadrangle) 718360.283 4250477.056, 

729301.869 4250718.415, 729704.134 4236840.30, 718762.547 

4236558.715. 

(Festus USGS Quadrangle) 718762.547 4236558.715, 729704.134 

4236840.30, 730066.171 4223042.637, 719124.585 4222680.6. 

(Selma USGS Quadrangle) 729704.134 4236840.30, 730428.209 

4236840.3, 741047.984 4223283.996, 730066.171 4223042.637. 

(Valmeyer USGS Quadrangle) 729301.869 4250718.415, 731474.096 

4250798.868, 730428.209 4236840.3, 729704.134 4236840.30. 

*******

1 Includes any Indian country in each county or area, unless otherwise specified. EPA is not determining the boundaries of any area of Indian 

country in this table, including any area of Indian country located in the larger designation area. The inclusion of any Indian country in the designation area is not a determination that the state has regulatory authority under the Clean Air Act for such Indian country. 2This date is April 9, 2018, unless otherwise noted. 


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Federal Register / Vol. 86, No. 122 / Tuesday, June 29, 2021 / Proposed Rules 34187 

1Additionally, TCEQ submitted a petition for 

reconsideration on December 11, 2017, and on 

December 19, 2017, Vistra Energy provided 

additional information regarding facility 

retirements and the deployment of additional SO2

monitors to support its February 2017 petition for 

reconsideration and administrative stay. 

2https://www.epa.gov/sites/production/files/ 

2018-09/documents/3143_signed_response.pdf. 

3The EPA recently found that Texas has failed to 

submit State Implementation Plans to satisfy certain 

nonattainment planning requirements of the CAA 

for portions of Freestone and Anderson Counties, 

Rusk and Panola Counties, and Titus County. See 

85 FR 48111. 

4Additionally, as detailed in a separate document 

published elsewhere in this issue of the Federal 

Register that has been signed concurrently along 

with this withdrawal notice, the EPA is also now 

denying the administrative petitions from Vistra 

Energy and TCEQ. See https://www.regulations.gov 

under Docket ID No. EPA–HQ–OAR–2014–0464. 

* * * * * 

[FR Doc. 2021–13693 Filed 6–28–21; 8:45 am] 

BILLING CODE 6560–50–P 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Part 81 

[EPA–HQ–OAR–2014–0464; FRL–10024–28– 

OAR] 

Error Correction of the Area 

Designations for the 2010 1-Hour 

Sulfur Dioxide (SO2) Primary National 

Ambient Air Quality Standard (NAAQS) 

in Freestone and Anderson Counties, 

Rusk and Panola Counties, and Titus 

County in Texas 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Proposed rule; withdrawal. 

SUMMARY: The Environmental Protection 

Agency (EPA) is withdrawing its August 

22, 2019, proposed rule, which 

proposed both to determine that the 

EPA made an error in the area 

designations for the 2010 Sulfur Dioxide 

(SO2) Primary National Ambient Air 

Quality Standard (NAAQS) for portions 

of Freestone and Anderson Counties, 

Rusk and Panola Counties, and Titus 

County in Texas, and to correct the 

proposed error by modifying the 

designations of those areas to 

unclassifiable. The EPA is withdrawing 

the proposed rule because the EPA, 

informed in part by technical 

information received during the public 

comment period on the proposed rule 

that further supports the EPA’s initial 

designations of these areas, no longer 

believes the bases identified in the 

proposed error correction support the 

proposed conclusion that an error 

correction is appropriate. 

DATES: As of June 29, 2021, the 

proposed rule published at 84 FR 43757 

on August 22, 2019, is withdrawn. 

FOR FURTHER INFORMATION CONTACT: 

Corey Mocka, U.S. Environmental 

Protection Agency, Office of Air Quality 

Planning and Standards, Air Quality 

Policy Division, 109 T.W. Alexander 

Drive, Mail Code C539–04, Research 

Triangle Park, NC 27711; phone 

number: (919) 541–5142; email address: 

mocka.corey@epa.gov. 

SUPPLEMENTARY INFORMATION: 

I. Background 

On December 13, 2016, the EPA 

designated portions of Freestone and 

Anderson Counties, Rusk and Panola 

Counties, and Titus County in Texas as 

nonattainment for the 2010 1-hour 

primary SO2 NAAQS (81 FR 89870, 

codified at 40 CFR 81.344) (‘‘Round 2 

Supplement’’). On February 13, 2017, 

Vistra Energy, which owns SO2

emissions sources in each of the three 

areas, sent the EPA a petition for 

reconsideration, purportedly pursuant 

to Clean Air Act (CAA) section 

307(d)(7)(B) and the Administrative 

Procedure Act 5 U.S.C. 553(e), and for 

administrative stay of the EPA’s 

nonattainment designations for portions 

of Freestone and Anderson Counties 

(‘‘Big Brown Steam Electric Station 

area’’), Rusk and Panola Counties 

(‘‘Martin Lake Electrical Station area’’), 

and Titus County (‘‘Monticello Steam 

Electric Station area’’). On March 15, 

2017, the Texas Commission on 

Environmental Quality (TCEQ) also 

submitted a request for an 

administrative stay of the Round 2 

Supplement final designations for these 

areas in Texas.1 On September 21, 2017, 

the EPA initially responded to Vistra 

Energy’s February 2017 petition for 

reconsideration by indicating an intent 

to undertake an administrative action 

with notice and comment to revisit the 

nonattainment designations for the three 

areas, but explained that pending 

completion of such action, the 

nonattainment designations remained in 

effect.2 3

The EPA published a proposed rule in 

the Federal Register on August 22, 

2019, titled ‘‘Error Correction of the 

Area Designations for the 2010 1-Hour 

Sulfur Dioxide (SO2) Primary National 

Ambient Air Quality Standard (NAAQS) 

in Freestone and Anderson Counties, 

Rusk and Panola Counties, and Titus 

County in Texas’’ (84 FR 43757) 

(‘‘Proposed Error Correction’’). Under 

the EPA’s CAA authority at section 

110(k)(6) to correct errors in acting on 

state implementation plans (SIPs) or in 

issuing designations, redesignations, 

classifications or reclassifications, the 

EPA proposed that in designating these 

areas as nonattainment under CAA 

sections 107(d)(1)(A)(i), (d)(1)(B)(ii), and 

(d)(2)(A), it erred in not giving greater 

weight to Texas’s preference to 

characterize air quality through 

monitoring, and to steps undertaken by 

Texas to begin monitoring in these three 

areas, when considering all available 

information; in relying on available air 

quality analyses in making the initial 

designations that the EPA recognized 

included certain limitations; or a 

combination of these two issues. 

Therefore, to correct these proposed 

errors, the EPA also proposed that the 

previously designated nonattainment 

areas in Freestone and Anderson 

Counties, Rusk and Panola Counties, 

and Titus County in Texas each be 

revised to reflect an unclassifiable 

designation under CAA section 

107(d)(1)(A)(iii). The EPA has not 

finalized the Proposed Error Correction 

and is not doing so in this action. 

Instead, the EPA is now withdrawing 

the Proposed Error Correction.4

II. Reasons for Withdrawing the 

Proposed Error Correction 

A. Additional Air Quality Modeling 

In the Proposed Error Correction, the 

EPA proposed that it erred in relying on 

available air quality modeling submitted 

by Sierra Club in making the initial 

nonattainment designations for these 

three areas. The EPA explained in the 

proposed action that the modeling 

submitted by Sierra Club (‘‘December 

2015’’ and ‘‘March 2016’’ modeling), 

which purported to show 

nonattainment, was developed in 

accordance with the general 

recommendations on modeling 

provided by the EPA but stated that the 

modeling contained ‘‘key limitations 

and uncertainties.’’ We made this 

statement in the Proposed Error 

Correction despite also acknowledging 

that we had explained in the record for 

the Round 2 Supplement that 

individually these key limitations and 

uncertainties would not significantly 

change modeled results or, in many 

cases, could result in underestimation of 

SO2 concentrations. In the Proposed 

Error Correction, the EPA also stated 

that given the possible collective 

significance of these issues and, in the 

case of the areas around the Martin Lake 

and Monticello facilities, given that the 

maximum modeled concentrations are 

within about 10 percent of the 2010 SO2

NAAQS, we were less confident in our 

prior statements that potential 

adjustments to the Sierra Club modeling 

would not result in modeled values near 


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