Air Plan Approval; Missouri; Ameren Sioux Sulfur Dioxide Consent Agreement

AGENCY:

Environmental Protection Agency (EPA).

ACTION:

Proposed rule.

SUMMARY:

The Environmental Protection Agency (EPA) is proposing approval of source-specific revisions to the Missouri State Implementation Plan (SIP) received on April 21, 2022. In the submission, Missouri requests that the EPA incorporate into the SIP an additional sulfur dioxide (SO₂) emissions limit for the Ameren Missouri (Ameren)—Sioux Energy Center (Sioux). Specifically, the EPA is proposing to approve, into the SIP, an additional SO₂ emissions limit and associated operating restrictions, monitoring, recordkeeping, reporting (MRR) and testing compliance requirements established in a consent agreement as permanent and enforceable SO₂ control measures.

DATES:

Comments must be received on or before October 3, 2022.

ADDRESSES:

You may send comments, identified by Docket ID No. EPA-R07-OAR-2022-0722 to 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 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:

Jason Heitman, Environmental Protection Agency, Region 7 Office, Air Quality Planning Branch, 11201 Renner Boulevard, Lenexa, Kansas 66219; telephone number: (913) 551-7664; email address: heitman.jason@epa.gov.

SUPPLEMENTARY INFORMATION:

Throughout this document “we,” “us,” and “our” refer to the EPA.

Table of Contents

I. Written Comments

II. What is the background for this proposed action?

III. Have the requirements for approval of a SIP revision been met?

IV. What did Missouri submit in the source-specific SIP revision for Ameren Sioux?

V. What is the EPA's analysis of Missouri's source-specific SIP revision?

VI. What action is the EPA proposing?

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-2022-0722, at 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 additional submission methods, the full EPA public comment policy, information about CBI or multimedia submissions, and general guidance on making effective comments, please visit www.epa.gov/dockets/commenting-epa-dockets.

II. What is the background for this proposed action?

The Ameren Sioux facility is located in St. Charles County, Missouri, along the Mississippi River, just north of the City of St. Louis. The EPA designated the area surrounding Ameren Sioux as attainment/unclassifiable for the 2010 1-hour SO₂ NAAQS in early 2018 (83 FR 1098, January 9, 2018). Unlike with a nonattainment designation, a designation of attainment/unclassifiable does not impose any new SO₂ planning requirements on the Missouri Department of Natural Resources (MoDNR) for Ameren Sioux in Missouri's SIP.

Ameren Sioux operates two coal-fired boilers that generate electricity for use in the region. In 2010, Ameren Sioux installed wet flue-gas desulfurization control technology at their two boilers. The existing enforceable SO₂ emissions limit in the Missouri SIP for Sioux is much higher than recent actual emissions and therefore does not reflect operation of the control technology. This control technology reduced the actual SO₂ emissions at Ameren Sioux by nearly 90 percent.

Ameren Sioux is required to operate a continuous emission monitoring system (CEMS) for SO₂ on both of their boilers. This allows for the reporting of actual hourly emissions levels coming from the two boilers at the facility. The Consent Agreement included in this proposed SIP revision also requires the use of their CEMS to demonstrate compliance with the additional enforceable limit in the Consent Agreement.

III. 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 this SIP revision from December 27, 2021 to February 3, 2022 and received one comment. In addition, the revision meets the substantive SIP requirements of the CAA, including section 110 and implementing regulations.

IV. What did Missouri submit in the source-specific SIP revision for Ameren Sioux?

The SO₂ emissions limit and averaging time included in the Consent Agreement for Ameren Sioux are provided in Table 1. The limit is listed as a facility-wide limit, but only applies to Boilers 1 and 2 at the facility.

Ameren will maintain all hourly data and computations related to demonstrating compliance with the 24-hour block average emissions limit and keep this data for a period of at least five years. Ameren shall report on compliance with the emissions limit in Table 1 on the same schedule as the annual compliance certification required in accordance with the operating permits issued under 40 CFR part 70.

V. What is the EPA's analysis of Missouri's source-specific SIP revision?

The EPA is proposing to determine that the limit in the Consent Agreement is practically enforceable through the following analysis. The Consent Agreement requires Ameren to determine compliance with the emissions restrictions by use of the SO₂ CEMS installed on Boilers 1 and 2 at Sioux. The CEMS will be operated in accordance with 40 CFR part 75. The limit in the Consent Agreement is based on 24-hour block averages. The total pounds of SO₂ emitted during each calendar day, as measured by the CEMS, is first summed for the subject units, then divided by the number of actual operating hours in that day. If this is less than or equal to the limit in Table 1, the facility is in compliance with the emissions limit. Only hours that meet the primary equipment hourly operating requirements of 40 CFR 75.10(d) are used in calculating the daily 24-hour block average. For example, if the source only meets 40 CFR 75.10(d) operational requirements for one hour in a particular 24-hour block period, the compliance with the emissions limit would be calculated by the total emissions divided by the one hour of operation that meets 40 CFR 75.10(d). Therefore, any day with at least one hour that meets operational requirements will have a calculated block average that will be used to demonstrate compliance with the emissions limit.

While the Consent Agreement may be terminated under state law by mutual agreement by both parties at the current time, this action, once finalized, would approve that Agreement into the SIP. At that point the requirements of the Consent Agreement would be permanent and federally enforceable and would remain applicable until Missouri submits a SIP revision and the EPA approves that revision. That revision would be subject to CAA section 110(l), i.e., the state must demonstrate that the revision would not interfere with the attainment or maintenance of any NAAQS.

VI. What action is the EPA proposing?

The EPA is proposing to approve Missouri's April 21, 2022, source-specific SIP revision into the Missouri SIP. This revision includes a specific SO₂ emissions limit and associated operating restrictions, MRR, and testing compliance requirements for the Ameren Sioux Facility as contained in Consent Agreement number APCP-2021-018. A copy of the Consent Agreement is included in the docket for this rulemaking.

The purpose of the Consent Agreement is to provide for the new SO₂ emissions limit at Ameren Sioux to be credited as an additional permanent and federally enforceable measure in Missouri's SIP. Ameren has voluntarily agreed to enter into this Consent Agreement to strengthen Missouri's SIP.

The Consent Agreement includes a facility-wide 24-hour block average emissions limit. The additional SO₂ emissions limit that the EPA proposes to approve is in addition to the SO₂ requirements currently in the SIP for Ameren Sioux. Incorporating an additional specific SO₂ limit and associated operating restrictions, MRR, and testing compliance parameters for Ameren Sioux into the Missouri SIP would establish this additional specific SO₂ limit and associated operating and compliance parameters as permanent and federally enforceable control measures and strengthen the Missouri SIP.

The purpose of this rulemaking is to act on Missouri's request to approve into the SIP an additional specific facility-wide SO₂ limit (listed in Table 1), and associated operating, MRR, and testing requirements established in a Consent Agreement, thereby making this limit permanent and federally enforceable to strengthen the Missouri SIP.

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. In this action, the EPA is proposing to approve an additional emissions limit for a source into the Missouri SIP.

The EPA utilized the EJSCREEN tool to evaluate environmental and demographic indicators within the area. The tool outputs report is contained in the docket for this action. While the EPA's EJSCREEN tool demonstrates that demographic indicators are consistent or lower than national averages, there are vulnerable populations in the area including low-income populations and persons over 64 years of age.

Based on the information presented in this document, this proposed action does not result in disproportionately high and adverse human health or environmental effects on minority populations, low-income populations and/or indigenous peoples.

VIII. Incorporation by Reference

In this document, the EPA is proposing to include regulatory text in an EPA final rule that includes incorporation by reference. In accordance with requirements of 1 CFR 51.5, the EPA is proposing to incorporate by reference the Missouri Consent Agreement discussed in section VI of this preamble and as set forth below in the proposed revision to 40 CFR part 52. 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, provided that 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 basis 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 proposed 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
• Reporting and recordkeeping requirements
• Sulfur oxides

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 AA—Missouri

2. In § 52.1320, the table in paragraph (d) is amended by adding the entry “(37)” in numerical order to read as follows: