Proposed Rule
Air Plan Partial Approval and Partial Conditional Approval; South Carolina; Control of Oxides of Nitrogen and Source Testing Requirements
The full text was pulled automatically from the official source and is not Threadline News reporting; the annotations alongside it are.
Agency
Environmental Protection Agency (EPA).
Action
Proposed rule.
Summary
The U.S. Environmental Protection Agency (EPA or Agency) is proposing to partially approve and partially conditionally approve changes to South Carolina's State Implementation Plan (SIP) to revise source testing requirements and regulations prescribing control requirements for certain stationary sources of nitrogen oxides (NOX) submitted by the State of South Carolina, through the South Carolina Department of Environmental Services (SC DES), on October 1, 2007; July 27, 2016; September 5, 2017; April 24, 2020; and February 4, 2022. This action is being proposed pursuant to the Clean Air Act (CAA or Act).
Dates
Comments must be received on or before September 18, 2026.
Addresses
Submit your comments, identified by Docket ID No. EPA-R04- OAR-2025-0017 at https://www.regulations.gov. Follow the online instructions for submitting comments. 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 https://www.epa.gov/dockets/commenting-epa-dockets.
For further information contact
Faith Goddard, Multi-Air Pollutant Coordination Section, Air Planning and Implementation Branch, Air and Radiation Division, U.S. Environmental Protection Agency, Region 4, 61 Forsyth Street SW, Atlanta, Georgia 30303-8960. The telephone number is (404) 562-8757. Ms. Goddard can also be reached via electronic mail at [email protected].
Supplementary information
Notice of proposed rulemaking (NPRM) acronyms and abbreviations. The EPA uses multiple acronyms and terms in this NPRM. While this list may not be exhaustive, to ease the reading of this preamble and for reference purposes, the EPA defines the following terms and acronyms here:
CAA Clean Air Act CEMS Continuous Emissions Monitoring System CFR Code of Federal Regulations CHP Combined Heat and Power EPA Environmental Protection Agency FR Federal Register MMBtu Million British Thermal Units NAAQS National Ambient Air Quality Standard or Standards NESHAP National Emission Standard for Hazardous Air Pollutants NOX Nitrogen Oxides NNSR Nonattainment New Source Review NPRM Notice of Proposed Rulemaking NSPS New Source Performance Standards NSR New Source Review PEMS Predictive Emissions Monitoring System PPMV Parts per Million by Volume PSD Prevention of Significant Deterioration PTE Potential to Emit SIP State Implementation Plan
Table of Contents
I. Executive Summary A. What action is the EPA proposing? B. What is the legal authority and what are the requirements? II. Proposed Action III. Background A. Regulation 61-62.1, Section IV--Source Tests B. Regulation 61-62.5, Standard No. 5.2--Control of Oxides of Nitrogen (NOX) IV. The EPA's Evaluation of South Carolina's Submittals A. Regulation 61-62.1, Section IV--Source Tests B. Regulation 61-62.5, Standard No. 5.2--Control of Oxides of Nitrogen (NOX) 1. Section I--Applicability a. Subsection I(A) i. October 1, 2007, SIP Revision ii. July 27, 2016, SIP Revision b. Subsection I(B) i. October 1, 2007, SIP Revision ii. July 27, 2016, SIP Revision iii. February 4, 2022, SIP Revision 2. Section II--Definitions a. July 27, 2016, SIP Revision b. February 4, 2022, SIP Revision 3. Section III--Standard Requirements for New Affected Sources a. October 1, 2007, SIP Revision b. July 27, 2016, SIP Revision c. February 4, 2022, SIP Revision 4. Section IV--Monitoring, Record Keeping, and Reporting Requirements for New Affected Sources a. July 27, 2016, SIP Revision i. Monitoring Requirements 1. CEMS MRR Requirements 2. Parametric Monitoring Requirements 3. Manufacturer's Certification Requirements 4. Periodic Monitoring and/or Source Testing Requirements I. Aspects of Source Testing Provisions Proposed for Conditional Approval II. South Carolina's May 13, 2026, Conditional Approval Request III. The State's CAA Section 110(l) Demonstration IV. Summary of the EPA's Proposed Conditional Approval for Source Testing Provisions ii. Tune-Up Requirements iii. Other MRR Requirements b. February 4, 2022, SIP Revision i. CEMS MRR Requirements 1. Paragraphs IV(A)(1) and IV(C)(1) Proposed for Conditional Approval 2. South Carolina's May 13, 2026, Conditional Approval Request 3. The State's CAA Section 110(l) Demonstration 4. Summary of the EPA's Proposed Conditional Approval for Paragraphs IV(A)(1) and IV(C)(1) ii. Monitoring Requirements--Subsection IV(D) 1. Aspects of Subsection IV(D) Proposed for Conditional Approval 2. South Carolina's May 13, 2026, Conditional Approval Request 3. The State's CAA Section 110(1) Demonstration 4. Summary of the EPA's Proposed Conditional Approval for Paragraph IV(D) iii. Tune-Up Requirements iv. Other MRR Requirements 5. Section V--Standard Requirements for Existing Affected Sources 6. Section VI--Notification Requirements for Existing Affected Sources 7. Section VII--Tune-Up Requirements for Existing Sources a. July 27, 2016, SIP Revision b. February 4, 2022, SIP Revision V. Incorporation by Reference VI. Statutory and Executive Order Reviews
A. What action is the EPA proposing?
On October 1, 2007, July 27, 2016,\1\ September 5, 2017,\2\ and February 4, 2022,\3\ SC DES \4\ submitted SIP revisions that include changes to South Carolina's NOX control requirements in the South Carolina Code of Regulations Annotated (S.C. Code Ann. Regs.) Regulation 61-62.5, Air Pollution Control Standards, Standard No. 5.2, Control of Oxides of Nitrogen (NOX) (hereinafter "Regulation 61-62.5, Standard No. 5.2").\5\ Additionally, SC DES submitted a SIP revision on April 24, 2020, that includes changes to the State's source testing requirements in S.C. Code Ann. Regs. Regulation 61-62.1, Definitions and General Requirements, Section IV, Source Tests (hereinafter "Regulation 61-62.1, Section IV").\6\
\1\ The EPA received the July 27, 2016, SIP revision, dated July 25, 2016, on July 27, 2016. Therefore, the EPA considers July 27, 2016, to be the official SIP revision submission date and refers to that SIP revision in this NPRM as the "July 27, 2016," SIP revision. \2\ The EPA received the September 5, 2017, SIP revision, dated September 1, 2017, on September 5, 2017. Therefore, the EPA considers September 5, 2017, to be the official SIP revision submission date and refers to that SIP revision in this NPRM as the "September 5, 2017," SIP revision. \3\ The EPA received the February 4, 2022, SIP revision, dated February 3, 2022, on February 4, 2022. Therefore, the EPA considers February 4, 2022, to be the official SIP revision submission date and refers to that SIP revision in this NPRM as the "February 4, 2022," SIP revision. \4\ On July 1, 2024, the South Carolina Department of Health and Environmental Control (SC DHEC) was restructured into a health agency, the Department of Public Health, and an environmental agency, the Department of Environmental Services (SC DES). In a letter dated June 20, 2024, South Carolina represented to the EPA that all the functions, powers, and duties of the environmental divisions, offices, and programs of SC DHEC, including the authority to administer and enforce SIPs, are retained and continued in full force and effect under SC DES. This letter is in the rulemaking docket for this proposed action. The terms "State," "Department," and "SC DES" are used interchangeably throughout this Notice of Proposed Rulemaking (NPRM). \5\ The April 24, 2020, SIP revision originally transmitted changes to Regulation 61-62.5, Standard No. 5.2 from South Carolina's "2018 General Assembly Package" SIP revision. However, in the letter submittal to the February 4, 2022, SIP revision, SC DES re-submitted a substantively identical version of the April 24, 2020, SIP revision with respect to Regulation 61-62.5, Standard No. 5.2, except for a correction. In the 2022 letter, SC DES states that the April 24, 2020, SIP revision transmitted "a preexisting error" that was subsequently identified and removed in the Department's "2016 End of Year Revisions" in 2017, noting that the previously removed error reappeared in the subsequent April 24, 2020, 2018 General Assembly Package SIP Revision and was subsequently corrected. \6\ The October 1, 2007, July 27, 2016, September 5, 2017, and April 24, 2020, SIP revisions contain revisions to other provisions in the South Carolina SIP that are not addressed in this NPRM.
On May 13, 2026, SC DES submitted supplemental materials, including a
letter requesting that the EPA conditionally approve portions of the State's NOX control SIP revisions based on a commitment under CAA section 110(k)(4) to adopt and submit corrective revisions to portions of the SIP provisions currently before the EPA no later than one year after the EPA's conditional approval of South Carolina's submissions, should the EPA finalize this partial conditional approval as proposed. Additionally, the supplemental materials include a CAA section 110(l) demonstration to support the corrective changes that the State intends to submit in a corrective SIP revision. Section IV, below, provides the EPA's analysis of the State's non-interference demonstration. On May 13, 2026, SC DES also submitted to the EPA a letter addressing subsection III(A) as revised in the July 25, 2016, SIP revision and paragraph I(B)(3) and subsection II(K) as added and revised in the February 4, 2022, SIP revision, respectively, stating that "the specific text identified . . . is no longer before EPA at this time." Subsequently, on July 21, 2026,\7\ SC DES submitted a letter removing from the EPA's consideration one provision in Regulation 61- 62.5, Standard No. 5.2 for which the State, in its May 13, 2026, letter, requested conditional approval. This letter supersedes the May 13, 2026, request for conditional approval of paragraph I(B)(2). The July 21, 2026, letter removes from EPA consideration "I(B)(2), as submitted on July 25, 2016, and February 3, 2022." The States notes that in planned changes, the State will be "striking the referenced provision within Standard No. 5.2" and that "[t]herefore, the specific text . . . is not before the EPA at this time." \8\ The EPA is therefore proposing to approve or conditionally approve the remainder of the revised Regulation 61-62.5, Standard No. 5.2 provisions and Regulation 61-62.1, Section IV, in its entirety.
\7\ The EPA notes that the Agency received the letter, which is dated July 20, 2026, on July 21, 2026. For consistency, throughout this document we will refer to this as the July 21, 2026, letter. \8\ The State's letter received by the EPA on July 21, 2026, goes on to reiterate that I(B)(2), in addition to I(B)(3), II(K), and III(A), which were originally addressed in a May 13, 2026, letter are "no longer before EPA."
In this NPRM, the EPA is proposing to approve changes to South Carolina's regulations regarding source testing. Additionally, the EPA is proposing to approve portions of, and conditionally approve other portions of, the SIP submissions that make changes to South Carolina's NOX control rule requirements. Section IV, below, provides the EPA's analysis of the State's CAA section 110(l) non-interference demonstration for the provisions that the EPA is proposing to act on in this NPRM.
II. Proposed Action
The EPA is proposing to approve the changes to Regulation 61-62.1, Section IV, Source Tests, in the April 24, 2020, SIP revision, as detailed in Section IV of this NPRM. The EPA is proposing to approve these changes for the reasons discussed Section IV of this NPRM. The EPA is also proposing to approve the changes to Regulation 61- 62.5, Standard No. 5.2, Control of Oxides of Nitrogen (NOX), in the October 1, 2007, July 27, 2016, September 5, 2017, and February 4, 2022, SIP revisions,\11\ as detailed in Section IV of this NPRM, except for the portions of the SIP revisions consisting of the addition of and changes to certain provisions in Regulation 61-62.5, Standard No. 5.2, Section IV, which the EPA is proposing to conditionally approve, as described below. The EPA is proposing to approve the aforementioned changes to the SIP for the reasons discussed Section IV of this notice.
\11\ In this NPRM, the EPA is not proposing to approve the addition of and changes to paragraph I(B)(2); the addition of paragraph I(B)(3); the changes to subsection II(K); or the changes to subsection III(A), submitted in SIP revisions through February 4, 2022. The State removed the addition of paragraph I(B)(3) and changes to subsections II(K) and III(A) from Agency consideration in a letter dated May 13, 2026, and the addition of and changes to paragraph I(B)(2) in a letter submitted on July 21, 2026.
Finally, the EPA is proposing to conditionally approve the portions of the July 27, 2016, September 5, 2017, and February 4, 2022, SIP revisions consisting of the addition of and changes to certain provisions in Regulation 61-62.5, Standard No. 5.2, Section IV, Monitoring, Record Keeping, and Reporting Requirements for New Affected Sources. Specifically, the EPA is proposing to conditionally approve the following provisions submitted by the State in the July 27, 2016; September 5, 2017; and February 4, 2022, SIP revision submittals: paragraph IV(A)(1), specifically IV(A)(1)(a)-(d); subparagraph IV(A)(2)(a)-(c); subparagraph IV(B)(2)(a); subparagraph IV(B)(2)(b); paragraph IV(C)(1), specifically IV(C)(1)(a)-(d); subparagraph IV(C)(3)(c); subparagraph IV(C)(3)(d); the second prefatory paragraph of IV(D); subparagraph IV(D)(2)(a); and subparagraph IV(D)(2)(b). The EPA is proposing to conditionally approve the aforementioned changes to the SIP for the reasons discussed Section IV of this notice.