SUPPLEMENTARY INFORMATION:

Throughout this document whenever “we,” “us,” or “our” is used, we mean the EPA.

Table of Contents

I. What is the EPA proposing?

II. What is the background for this action?

III. What is the EPA's evaluation of Illinois' VOC and NO_X RACT determinations?

A. Certifying existing sections of 35 IAC part 219 as VOC RACT for Chicago and Metro-East

B. Permits for One Source Covered by the Oil and Natural Gas Industry CTG

C. Negative Declarations

D. 35 IAC 217

E. RACT Due Diligence

IV. What action is the EPA taking?

V. Incorporation by Reference.

I. What is the EPA proposing?

The EPA is proposing to approve 35 IAC parts 218 and 217 as satisfying the Moderate ozone nonattainment area VOC RACT requirements of Clean Air Act (CAA) section 182(b)(2), and the corresponding NO_X RACT requirements stemming from sections 182(b) and 182(f), respectively, for the Chicago, IL nonattainment area under the 2015 ozone standard. The EPA is also proposing to approve 35 IAC parts 219 and 217 as satisfying the Moderate area VOC and NO_X RACT requirements for the Metro-East nonattainment area under the 2015 ozone standard. For both nonattainment areas, the EPA is also proposing to approve 35 IAC part 217 as satisfying the Serious area NO_X RACT requirements from CAA sections 182(c) and 182(f). The Serious area VOC RACT requirements will be addressed in a separate action. On December 18, 2024, Illinois submitted attainment plans for both ozone nonattainment areas containing certifications that 35 IAC parts 218 and 219 satisfy the Moderate VOC RACT requirements and supplemented the submittal on August 13, 2025. On May 12, 2025, Illinois also submitted SIP revisions to 35 IAC part 217 to satisfy the Moderate and Serious NO_X RACT requirements.^[1]

II. What is the background for this action?

Emissions of VOCs and NO_X contribute to the production of ground-level ozone, or smog, which harms human health and the environment. The EPA defines RACT as the lowest emission limit that a particular source is capable of meeting by the application of control technology that is reasonably available considering technological and economic feasibility. See Memorandum from Roger Strelow, Assistant Administrator for Air and Waste Management, EPA, to Regional Administrators, EPA, “Guidance for Determining Acceptability of SIP Regulations in Non-Attainment Areas” (December 9, 1976); see also 44 FR 53761, 53762 (September 17, 1979). Control Techniques Guidelines (CTGs) provide recommendations to inform State, local, and Tribal air agencies as to what constitutes RACT for categories of VOC sources. CAA sections 182(b)(2) and 182(f), in combination, require States to implement RACT in ozone nonattainment areas classified as Moderate (and higher). Specifically, these areas are required to implement RACT for all major sources of VOC and NO_X (based on potential to emit at least 100 tons per year (tpy)) and for all VOC sources covered by a CTG. Air agencies can use the recommendations in the CTG and consider all recent relevant information to inform their own determination as to what constitutes RACT. If there are no sources covered by a certain CTG within a nonattainment area, a State may submit a negative declaration, in place of regulatory requirements, to apply RACT for that category of sources.

The EPA's SIP Requirements Rule for the 2008 ozone NAAQS indicates that States may meet RACT through the establishment of new or more stringent requirements that meet RACT control levels, through a certification that previously adopted RACT controls for a prior ozone NAAQS continue to represent adequate RACT control levels for the 2008 ozone NAAQS, or with a combination of these two approaches. See80 FR 12264, 12278-79 (March 6, 2015). As previously stated, a State may submit a negative declaration in instances where there are no sources covered by a particular CTG. The EPA's SIP Requirements Rule for the 2015 ozone NAAQS retains the existing general 2008 RACT requirements for purposes of the 2015 ozone NAAQS. See83 FR 62998, 63001-02, and 63007 (December 6, 2018).

Effective August 3, 2018 (83 FR 25776), the EPA designated the Illinois portions of the Chicago and Metro-East St. Louis areas as Marginal nonattainment areas for the 2015 ozone NAAQS. The Illinois portion of the Chicago nonattainment area includes Cook, DuPage, Kane, Lake, McHenry, and Will counties, as well as Aux Sable and Goose Lake Townships in Grundy County, and Oswego Township in Kendall County. The Illinois portion of Metro-East nonattainment area includes Madison, St. Clair, Monroe counties in Illinois, and St. Louis, St. Louis City, St. Charles, and Jefferson counties, as well as Boles Township in Franklin County in Missouri. On October 7, 2022 (87 FR 60897), the EPA determined that the Chicago and Metro-East areas failed to attain the 2015 ozone NAAQS by the August 3, 2021, attainment date, resulting in the reclassification of the areas from Marginal to Moderate ozone nonattainment. In that action, the EPA established January 1, 2023, as the due date for the State to submit all Moderate area nonattainment plan SIP requirements applicable to newly reclassified areas. More recently, on December 17, 2024 (89 FR 101901), the EPA determined that both areas did not attain the standards by the Moderate attainment date; therefore, the areas were reclassified to Serious ozone nonattainment. This action addresses the Moderate area VOC and both Moderate and Serious NO_X RACT SIP submissions for the Chicago and Metro-East nonattainment areas under the 2015 ozone standard. Serious VOC RACT for both nonattainment areas will be addressed in a separate action.

III. What is the EPA's evaluation of Illinois' VOC and NOX RACT determinations?

The EPA previously determined that 35 IAC parts 218 and 219 VOC regulations met Moderate RACT for requirements associated with the 2008 ozone NAAQS and incorporated them into the Illinois SIP. See action dated May 20, 2022 (87 FR 30828) for Chicago, and March 23, 2012 (77 FR 16940) for Metro-East. For certain categories of sources, Illinois is certifying that the previously adopted RACT regulations and controls contained in 35 IAC parts ( printed page 50748) 218 and 219 for VOCs continue to satisfy RACT requirements under the 2015 ozone NAAQS. Illinois has also adopted new RACT regulations in 35 IAC 217 for NO_X. The new NO_X regulations apply to both the Chicago and Metro-East, Illinois 2015 ozone nonattainment areas.

A. Certifying Existing Sections of 35 IAC Part 219 as VOC RACT for Chicago and Metro-East

The EPA approved 35 IAC parts 218 and 219 into the Illinois SIP under previous ozone standards. For this action, the EPA and Illinois performed RACT due diligence ^[2] analyses to determine what level of controls can be established as RACT. These analyses are provided in both the Chicago and Metro-East submittals and are described in detail in section III, subsection E of this preamble. The EPA has not identified any new control technologies that are reasonably available considering technological and economic feasibility for these sources since our last approval, and, therefore, the EPA is proposing to determine that the controls for the CTG categories covered in 35 IAC parts 218 and 219 still represent RACT for implementing the 2015 ozone standard in both Illinois nonattainment areas.

B. Permits for One Source Covered by the Oil and Natural Gas Industry CTG

Illinois identified one source located in the Metro-East nonattainment area that is covered by the EPA's 2016 CTG for the Oil and Natural Gas Industry. Instead of adopting categorical RACT rules for the source, Illinois requested that the EPA approve the source specific federally enforceable permit for the Flint Hills Resources Pine Bend facility (Pine Bend) for incorporation into the Illinois SIP. The EPA is proposing to approve this permit into the SIP to fulfill the RACT requirements for the Metro-East nonattainment area for the category of sources covered by the Oil and Gas CTG.

Pine Bend contains four crude oil storage tanks. The 2016 CTG recommends a 95% reduction of VOC emissions from these tanks. In 2024, the EPA issued updated New Source Performance Standards (NSPS) at 40 CFR part 60, subpart Kb. The 2024 NSPS Standards of Performance for Storage Vessels for Petroleum Liquids requires an external floating roof, a fixed roof, or a vapor recovery system to reduce VOC emissions by at least 95% for these tanks. Since the Pine Bend State permit requires the source to utilize an external floating roof, which is equivalent to or better than a vapor recovery system and reduces VOC emissions by at least 95%, the permit is equivalent to, or better than, the CTG recommendation as well as the newer NSPS, and we are not aware of any other relevant information to inform this determination. Therefore, the EPA is proposing to approve the Illinois EPA Federally Enforceable State Operating Permit No. 83100026 into the SIP as satisfying RACT for Pine Bend in the Metro-East nonattainment area under the 2015 ozone standard.

C. Negative Declarations

For the Chicago nonattainment area, Illinois submitted Negative Declarations for the following CTG categories: Ship Building and Ship Repair Industry; Natural Gas/Gasoline Processing Plants; Aerospace Manufacturing and Rework Facilities; High-Density Polyethylene, Polypropylene, and Polystyrene Resins; Vegetable Oil Processing; Industrial Wastewater; and Oil and Natural Gas Industry. Illinois performed searches for facilities meeting each of these CTG categories in the Chicago nonattainment area for the 2015 ozone standard and determined that there are no sources subject to any of these CTGs in this nonattainment area.

For the Metro-East nonattainment area, Illinois submitted Negative Declarations for the following CTG categories: Ship Building and Ship Repair Industry; Natural Gas/Gasoline Processing Plants; Aerospace Manufacturing and Rework Facilities; High-Density Polyethylene, Polypropylene, and Polystyrene Resins; Vegetable Oil Processing; and Industrial Wastewater. Illinois conducted searches for facilities meeting each of these CTG categories in the Metro-East nonattainment area for the 2015 ozone standard and determined that there are no sources subject to any of these CTGs in this nonattainment area.

The EPA reviewed the information submitted by Illinois related to these negative declarations and agrees with the State's determinations that no covered sources for these CTGs exist in the relevant nonattainment areas. As such, the EPA is proposing to approve these negative declarations as meeting RACT.

D. 35 IAC 217

To satisfy the requirements under CAA sections 172 and 182 to adopt NO_X RACT regulations with respect to the 2015 ozone standard, Illinois amended 35 IAC 217. CAA section 182(f) defines a major stationary source in a Moderate ozone or a Serious ozone nonattainment area as one that directly emits, or has the potential to emit, 100 tpy or more of NO_X or 50 tpy or more of NO_X, respectively.

These NO_X RACT rules establish non-CTG RACT general provisions, including updated measurement methods for NO_X, added predictive emission monitoring system (PEMS) to the abbreviations used in this part, removed or updated outdated materials, and added a Federal regulation governing combustion tuning requirements. Illinois EPA's amendments also include federally enforceable NO_X emissions limitations and testing and monitoring requirements for the following NO_X source categories: any industrial boiler, process heater, glass melting furnace, cement kiln, lime kiln, iron and steel reheat, annealing, or galvanizing furnace, aluminum reverberatory or crucible furnace, or fossil fuel-fired stationary boiler that emits NO_X in an amount equal to or greater than 15 tpy and that is located at a source in the Chicago or Metro-East ozone nonattainment area that has the potential to emit NO_X in an amount equal to or greater than 50 tpy.

Illinois' submittal also included provisions for an emissions averaging plan, which is a type of Economic Incentive Program (EIP), as an alternative method to satisfying NO_X RACT requirements. CAA section 182(g)(4) required the EPA to promulgate rules for EIPs, which the EPA did on April 7, 1994.^[3] In 2001 EPA issued further guidance on discretionary EIPs.^[4] The EPA's 1994 rule allows sources subject to RACT requirements to attain RACT-level emissions reductions in the aggregate, but directs States, to the extent practicable, to require increased emissions reductions beyond those that would be achieved through a traditional RACT program. The EPA's 2001 EIP guidance provides for a presumptive approach for complying with RACT requirements though an EIP. For areas needing and lacking an approved attainment demonstration, the 2001 EIP guidance specifies that this requirement can be met through an additional 10% reduction in emissions. Illinois' rules utilize this presumptive approach, specifying that, for sources opting to comply through averaging, an additional 10 percent emissions reduction is required. Source participation in Illinois' EIP is voluntary ( printed page 50749) as a source can meet the RACT requirements of Illinois' proposed rules by instead complying with the NOx limits applicable to each unit.

The EPA is proposing that the emissions limits for NO_X sources satisfy Moderate and Serious RACT requirements as they are equal to or more stringent than NO_X requirements for similar sources in other States' rules as discussed in section III, subsection E of this preamble.

E. RACT Due Diligence

As part of its December 18, 2024, and May 12, 2025, submittals, Illinois certified that the RACT requirements for Moderate CTG and non-CTG VOC and NO_X sources and Serious CTG and non-CTG NO_X sources in the Chicago and Metro-East 2015 ozone nonattainment areas have been fulfilled. Illinois conducted its RACT analysis for VOC and NO_X by: (1) Identifying all categories of CTG and major non-CTG sources of VOC and NO_X emissions within both nonattainment areas; (2) Listing the Illinois State regulation that implements or exceeds RACT requirements for that CTG or non-CTG category; and (3) Submitting negative declarations when there are no CTG applicable sources within the Chicago and Metro-East areas.

The EPA performed a supplemental due diligence analysis for the Illinois VOC and NO_X RACT submittals for the Chicago and Metro-East nonattainment areas under the 2015 ozone standard. In the EPA's December 2025 Technical Support Document (available in the docket), the EPA details the basis for concluding that Illinois' current VOC and new NO_X regulations fulfill RACT through comparison with RACT rules developed by other States, CTG guidance documents and applicable ACT documents. The EPA evaluated the relevant RACT rules in various States including some other EPA Region 5 States (Ohio, Michigan, Indiana, Wisconsin) and other States located in EPA Regions 1, 2, 6, 8, and 9 (Maine, Vermont, California, Colorado, Texas, Arizona, New Jersey, Connecticut, and New York). The EPA found Illinois' rules to be generally consistent with or more stringent than control measures in other States' regulations, CTGs, and non-CTGs. The EPA has not identified any new control technologies that are reasonably available considering technological and economic feasibility for these sources. Based upon our findings, the EPA proposes to determine that Illinois' rules represent Moderate level VOC and NO_X RACT as well as Serious NO_X RACT.

IV. What action is the EPA taking?

The EPA is proposing to approve 35 IAC parts 218 and 219 as satisfying the Moderate area VOC RACT requirements of CAA section 182(b)(2) for both the Chicago and Metro-East nonattainment areas under the 2015 ozone standard. The EPA is also proposing to approve revisions to 35 IAC part 217 as satisfying the Moderate and Serious NO_X RACT requirements of 182(b)(2), 182(c), and 182(f)of the CAA for the Chicago and Metro-East nonattainment areas under the 2015 ozone standard.

V. Incorporation by Reference

In this rulemaking, The EPA is proposing to include in a final EPA rule regulatory text that includes incorporation by reference. In accordance with requirements of 1 CFR 51.5, the EPA is proposing to incorporate by reference Illinois rules 35 IAC parts 218 and 219, effective December 9, 2024, and 35 IAC 217, effective April 23, 2025, discussed in section III of this preamble. The EPA is also proposing to incorporate by reference Illinois Operating Permit 83100026 for the Flint Hills Pine Bend facility, issued June 20, 2024. The EPA has made, and will continue to make, these documents generally available through www.regulations.gov and at the EPA Region 5 Office (please contact the person identified in the FOR FURTHER INFORMATION CONTACT section of this preamble for more information).

VI. Statutory and Executive Order Reviews

Under the CAA, the Administrator is required to approve a SIP submission that complies with the provisions of the CAA 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 underExecutive Order 12866 (58 FR 51735, October 4, 1993);
• Is not anExecutive Order 14192 (90 FR 9065, February 6, 2025) regulatory action because this action is not significant under Executive Order 12866;
• 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 inExecutive Order 13132 (64 FR 43255, August 10, 1999);
• Is not subject toExecutive Order 13045 (62 FR 19885, April 23, 1997) because it approves a State program;
• Is not a significant regulatory action subject toExecutive Order 13211 (66 FR 28355, May 22, 2001); and
• Is not subject to requirements of section 12(d) of the National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 note) because application of those requirements would be inconsistent with the CAA.

In addition, 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 rulemaking 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).

91 FR 50746