Air Plan Approval; Illinois; Alton Township 2010 Sulfur Dioxide Redesignation and Maintenance Plan, 81409-81416 [2024-23164]

Agencies

• ENVIRONMENTAL PROTECTION AGENCY

[Federal Register Volume 89, Number 195 (Tuesday, October 8, 2024)]
[Proposed Rules]
[Pages 81409-81416]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-23164]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 52 and 81

[EPA-R05-OAR-2023-0498; FRL-12265-01-R5]


Air Plan Approval; Illinois; Alton Township 2010 Sulfur Dioxide 
Redesignation and Maintenance Plan

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to 
redesignate the Alton Township nonattainment area in Madison County, 
Illinois to attainment for the 2010 sulfur dioxide (SO2) 
National Ambient Air Quality Standard (NAAQS). EPA is also proposing to 
approve Illinois' maintenance plan for the area. Illinois submitted the 
request for approval on October 2, 2023. Additionally, EPA is proposing 
to determine the Alton Township area attained the 2010 SO2 
NAAQS by the September 12, 2021, attainment date, fulfilling EPA's 
obligation under the Clean Air Act (CAA) to determine whether the area 
attained the relevant NAAQS standard within six months of the 
attainment date.

DATES: Comments must be received on or before November 7, 2024.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R05-
OAR-2023-0498 at https://www.regulations.gov, or via email to 
[email protected]. For comments submitted at Regulations.gov, follow 
the online instructions for submitting comments. Once submitted, 
comments cannot be edited or removed from the docket. EPA may publish 
any comment received to its public docket. Do not submit to EPA's 
docket at https://www.regulations.gov any information you consider to 
be Confidential Business Information (CBI), Proprietary Business 
Information (PBI), or other information whose disclosure is restricted 
by statute. Multimedia submissions (audio, video, etc.) must be 
accompanied by a written comment. The written comment is considered the 
official comment and should include discussion of all points you wish 
to make. EPA will generally not consider comments or comment contents 
located outside of the primary submission (i.e. on the web, cloud, or 
other file sharing system). For additional submission methods, please 
contact the person identified in the FOR FURTHER INFORMATION CONTACT 
section. For the full EPA public comment policy, information about CBI, 
PBI, or multimedia submissions, and general guidance on making 
effective comments, please visit https://www.epa.gov/dockets/commenting-epa-dockets.

FOR FURTHER INFORMATION CONTACT: Cecilia Magos, Air and Radiation 
Division (AR18J), Environmental Protection Agency, Region 5, 77 West 
Jackson Boulevard, Chicago, Illinois 60604, (312) 886-7336, 
[email protected]. The EPA Region 5 office is open from 8:30 a.m. 
to 4:30 p.m., Monday through Friday, excluding Federal holidays.

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

[[Page 81410]]

I. Background and Redesignation Requirements

    On June 22, 2010 (75 FR 35520), EPA revised the primary 
SO2 NAAQS, establishing a new health-based 1-hour standard 
of 75 parts per billion (ppb). EPA promulgated designations for this 
standard in four rounds. On September 18, 2015, Illinois submitted its 
recommendations to EPA to designate certain areas of the State as part 
of the Round 2 designations. Illinois recommended a portion of southern 
Alton Township in Madison County be designated as nonattainment for the 
2010 SO2 NAAQS. EPA concurred with Illinois' analysis and 
published a final action designating the area as nonattainment for the 
2010 SO2 NAAQS effective September 12, 2016 (81 FR 45039).
    Illinois submitted an attainment plan for the Alton Township 
nonattainment area on December 3, 2018. Under section 192(a) of the 
CAA, these plans are required to demonstrate that areas will attain the 
NAAQS as expeditiously as practicable, but no later than five years 
from the effective date of designation. The plan included modeling from 
emissions associated with the Alton Steel Inc. (Alton Steel) facility 
in Alton, Illinois, and emissions from the Ameren Missouri-Sioux Energy 
Center (Ameren-Sioux) power plant in Missouri, located about 13 
kilometers west-northwest of the nonattainment area. The modeled 
emissions showed the nonattainment status of the area was mainly 
attributed to these two SO2 sources. Unlike the Round 2 
designations modeling, the Alton Township attainment demonstration did 
not include the Wood River Power Station among the sources modeled due 
to the retirement of the facility in June 2016 and its demolition in 
February 2021. On March 14, 2019, after Illinois' submission of the 
attainment plan, the Illinois Environmental Protection Agency issued 
Construction Permit #18020009 for the Alton Steel facility to operate a 
new ladle metallurgy facility (LMF) stack, removing the downfacing 
vents that were contributing to modeled nonattainment at the facility. 
EPA included additional dispersion modeling to supplement Illinois' 
attainment demonstration to demonstrate that the emission limits 
required by the Illinois SIP and submitted for EPA approval provide for 
modeled concentrations meeting the 2010 SO2 NAAQS. EPA 
approved Illinois' attainment plan revision on February 21, 2023 (88 FR 
10464). Additionally, under section 179(c)(1) of the CAA, EPA is 
required to determine whether a nonattainment area attained a standard 
by the applicable attainment date based on the area's air quality as of 
the attainment date. EPA is to issue this determination within six 
months of the attainment date. Thus, EPA had a mandatory duty under CAA 
section 179(c) to determine by March 12, 2022, whether the Alton 
Township area attained by September 12, 2021. As an additional action, 
EPA is proposing to determine the Alton Township area did attain the 
2010 SO2 NAAQS by the attainment date of September 12, 2021.
    On October 2, 2023, Illinois submitted a redesignation request and 
maintenance plan for the Alton Township nonattainment area for the 2010 
SO2 NAAQS. Additionally, on March 31, 2022, Missouri adopted 
into its SIP a Consent Agreement between the Missouri Department of 
Natural Resources' Air Pollution Control Program and Ameren-Sioux, 
APCP-2021-018. EPA approved the revision to incorporate the Ameren-
Sioux Consent Agreement on November 16, 2022 (87 FR 68634), 
establishing an enforceable SO2 emissions limit for two 
coal-fired boilers at the facility. See Appendix B of the State's 
submittal included in the public docket of this action--Ameren-Sioux 
Consent Agreement. The submitted redesignation request and maintenance 
plan includes the Construction Permit issued to Alton Steel and the 
Consent Agreement issued to Ameren-Sioux approved into the Missouri SIP 
(87 FR 68634, November 16, 2022) with accepted SO2 emissions 
limits. While the Ameren-Sioux facility is not in the Alton Township 
nonattainment area, Illinois included this facility in their modeling 
due to its close proximity to the nonattainment area and high 
SO2 emissions, using information provided by the Missouri 
Department of Natural Resources. EPA's supplemental modeling with the 
updated limit of 7,342 pounds per hour (lbs/hr) averaged over a 24-hour 
block period for the Ameren-Sioux facility outlined in the Consent 
Agreement, provided for attainment of the 2010 SO2 NAAQS, 
and thus is included in Illinois' submittal.
    Under section 107(d)(3)(E) of the CAA, EPA may not promulgate a 
redesignation of a nonattainment area (or portion thereof) unless:
    1. EPA has determined that the area has attained the NAAQS;
    2. EPA has fully approved the applicable implementation plan for 
the area under section 110(k) of the CAA;
    3. EPA has determined that improvement in air quality is due to 
permanent and enforceable reductions in emissions resulting from 
implementation of the applicable implementation plan and applicable 
Federal air pollution control regulations and other permanent and 
enforceable reductions;
    4. EPA has fully approved a maintenance plan for the area under 
section 175A of the CAA; and
    5. The State containing such area has met all requirements 
applicable to the area under section 110 of the CAA and part D.

II. Evaluation of Illinois' Redesignation Request and Maintenance Plan

    On October 2, 2023, Illinois submitted a redesignation request for 
the Alton Township 2010 SO2 nonattainment area to attainment 
and a SIP revision containing a maintenance plan for the area.
    EPA's evaluation of Illinois' redesignation request and maintenance 
plan was based on consideration of the five redesignation criteria 
provided under CAA section 107(d)(3)(E).

Criteria (1)--The Alton Township SO2 Nonattainment Area Has Attained 
the 2010 SO2 NAAQS

    In accordance with CAA section 107(d)(3)(E)(i), for redesignation 
of a nonattainment area to attainment, the CAA requires EPA to 
determine that the area has attained the applicable NAAQS. An area is 
attaining the 2010 SO2 NAAQS at an ambient air quality 
monitoring site, in accordance with 40 CFR 50.17 and appendix T of part 
50, when the three-year average of the annual (99th percentile) of the 
daily maximum 1-hour average concentrations is less than or equal to 75 
ppb. As stated in EPA's April 23, 2014, ``Guidance for 1-Hour 
SO2 Nonattainment Area SIP Submissions'' (``April 2014 
SO2 Guidance''), there are two components needed to support 
an attainment determination: (1) a review of representative air quality 
monitoring data located in the area of maximum concentration; and (2) a 
further analysis, where there are no monitors, using air quality 
dispersion modeling, which will generally be needed to estimate 
SO2 concentrations throughout the nonattainment area to 
demonstrate that the entire area is attaining the applicable NAAQS, 
based on current actual emissions or the fully implemented control 
strategy.\1\ The April 2014 SO2 Guidance further states that 
dispersion modeling should be

[[Page 81411]]

conducted to estimate SO2 concentrations throughout the 
nonattainment area using actual emissions and meteorological 
information for the most recent 3 calendar years. EPA considered 
Illinois' modeling analyses submitted in the State's attainment plan 
which incorporated reductions in allowable emissions without the LMF 
stack changes to Alton Steel, which showed Alton Steel was the 
principal contributor to the highest modeled violations. Subsequently, 
EPA considered the modeling analyses with changes to the LMF exhaust 
configuration as described in Illinois' Construction Permit issued to 
Alton Steel. This analysis determined that after changes to the LMF 
exhaust stack in Alton Steel, the analysis still modeled violations of 
the 2010 SO2 NAAQS that were primarily due to the Ameren-
Sioux facility. New SO2 emission limits were established 
under the Ameren-Sioux Consent Agreement (87 FR 68634, November 16, 
2022), and EPA conducted supplementary modeling that incorporated both 
of these new limits and the changes to the LMF exhaust stack at Alton 
Steel. The supplementary modeling showed design values that are below 
the 2010 SO2 NAAQS for the Alton Township area.
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    \1\ EPA's ``Guidance for 1-Hour Sulfur Dioxide (SO2) 
Nonattainment Area State Implementation Plans (SIP) Submissions'' 
can be found at https://www.epa.gov/so2-pollution/guidance-1-hour-sulfur-dioxide-so2-nonattainment-area-state-implementation-plans-sip.
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    The April 2014 SO2 Guidance provides an extensive 
discussion of EPA's view that appropriately set comparably stringent 
limits based on averaging times as long as 30 days can be found to 
provide for attainment of the 2010 SO2 NAAQS. The April 2014 
SO2 Guidance also offers specific recommendations for 
determining an appropriate longer-term average limit. Illinois' plan 
applies 1-hour average emission limits to Alton Steel. However, 
Illinois' attainment plan also considers the impact of an additional 
facility, Ameren-Sioux, that is subject to a 24-hour block average 
limit. In response, EPA provided additional discussion of its rationale 
for approving the use of longer-term average limits in plans designed 
to provide for attainment. More detail on EPA's analysis of the 
attainment plan for the Alton Township area can be found in the 
attainment plan approval (88 FR 10464, February 21, 2023).
    Under 40 CFR 50.17(b), the 2010 SO2 NAAQS is met at an 
ambient air quality monitoring site when the three-year average of the 
annual (99th percentile) daily maximum 1-hour average concentrations is 
less than or equal to 75 ppb, as determined in accordance with appendix 
T of 40 CFR part 50, at all relevant monitoring sites in the subject 
area. In a year with 365 days of valid monitoring data, the 99th 
percentile would be the fourth highest daily maximum 1-hour value. 
Attainment demonstrations for the 2010 SO2 NAAQS should 
demonstrate future attainment and maintenance of the NAAQS in the 
entire area designated as nonattainment (i.e., not just at the 
violating monitor) by using air quality dispersion modeling (see 
appendix W to 40 CFR part 51) to show that the mix of sources and 
enforceable control measures and emission rates in an identified area 
will not lead to a violation of the 2010 SO2 NAAQS. 
Illinois' redesignation request for the Alton Township nonattainment 
area relied upon the demonstration of attainment based on air 
dispersion modeling, which Illinois submitted to EPA as part of its 
December 2018 attainment SIP submittal. For a short-term (i.e., 1-hour) 
standard, dispersion modeling, using allowable emissions and addressing 
stationary sources in the affected area (and in some cases those 
sources located outside the nonattainment area which may affect 
attainment in the area), is technically appropriate, efficient, and 
effective in demonstrating attainment in nonattainment areas because it 
takes into consideration combinations of meteorological and emission 
source operating conditions that may contribute to peak ground-level 
concentrations of SO2.
    Preferred air quality models for use in regulatory applications are 
described in appendix A of EPA's Guideline on Air Quality Models (40 
CFR part 51, appendix W). In 2005, EPA promulgated AERMOD as the 
Agency's preferred near-field dispersion modeling for a wide range of 
regulatory applications addressing stationary sources (for example, in 
estimating SO2 concentrations) in all types of terrain based 
on extensive developmental and performance evaluation. To support the 
SIP for bringing the Alton area into attainment of the 2010 
SO2 NAAQS, EPA assisted Illinois by conducting a modeling 
demonstration of the Alton area with updated emissions data relied upon 
in the model and by correcting the source characterization. Because 
Illinois' submittal predated the updated SO2 emissions limit 
at the Ameren-Sioux facility necessary to model attainment in the area, 
EPA updated the emissions data at Ameren-Sioux in the supplemental 
model and corrected any other deficiencies in the emissions data. 
Additional updates and modifications in EPA's modeling analysis 
included: updated AERMOD version from version 18081 to 21112 (the most 
recent available version at the time), updated stack parameters to 
current operating conditions, and adjusted emission rates for the 
Ameren-Sioux facility to account for longer-term average limits. EPA 
used Illinois' receptor grid, meteorological surface and upper air 
stations, model settings, and some source parameters to develop the 
modeling demonstration. See Alton SO2 Nonattainment Plan 
TSD, 87 FR 80509 (December 30, 2022). EPA used AERMOD version 21112, 
the most recent version of the AERMOD Modeling System available at the 
time, for the modeling analysis. In the time since the modeling was 
conducted by Illinois and later supplemented by EPA using AERMOD 
version 21112, EPA has released two AERMOD version updates. AERMOD 
22112 was released in 2022 to replace the regulatory version 21112 and 
was a routine release that does not include any scientific updates to 
the regulatory formulation of AERMOD as described in appendix W.\2\ In 
2023, AERMOD 23132 replaced the regulatory version 22112 which included 
small bug fixes and enhancements.\3\ Currently, AERMOD 23132 is the 
most recent available version. However, EPA does not require Illinois 
to use the current AERMOD version as Illinois used the AERMOD version 
that was most recent at the time it was developing the SIP and 
determining SO2 emission limits.
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    \2\ See AERMOD Modeling System Transmittal Memorandum (v22112) 
https://gaftp.epa.gov/Air/aqmg/SCRAM/models/preferred/aermod/AERMOD_22112_Transmittal_Memo.pdf.
    \3\ See AERMOD Modeling System Transmittal Memorandum (v23132) 
https://gaftp.epa.gov/Air/aqmg/SCRAM/models/preferred/aermod/AERMOD_23132_Transmittal_Memo.pdf.
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    Illinois' modeled demonstration of attainment for the Alton 
Township area was discussed in detail in EPA's proposed approval of the 
Alton Township SO2 attainment plan. See 87 FR 80509, 
(December 30, 2022). Illinois' original modeling submitted included 
Ameren-Sioux maximum allowable emissions and the reconfigured LMF stack 
emissions for Alton Steel, which yielded a maximum predicted 99th 
percentile 1-hour average concentration of 298.5 micrograms per cubic 
meter ([micro]g/m\3\). EPA conducted a supplemental modeling run to 
evaluate the reconfigured stack requirements at Alton Steel in 
combination with Ameren-Sioux's updated 7,342 lbs SO2/hr 24-
hour block limit found in the Missouri SIP (87 FR 68634, November 16, 
2022). EPA's modeling demonstrated that the Alton area showed a design 
value of 74.9 ppb (196.2 [micro]g/m\3\) with the revised SO2 
emission limits that will provide for attainment based on the new 
requirements for Alton Steel and

[[Page 81412]]

Ameren-Sioux, which are both permanently and federally enforceable. As 
mentioned above, the changes at the Alton Steel facility were 
construction changes to the LMF stack parameters to be completed by 
July 31, 2019, modifying the dispersion of emissions, and they did not 
alter existing operating emission limit conditions that the 
reconfigured LMF stack was already subject to and approved for in the 
approved attainment plan. Stack test results of the LMF at the Alton 
Steel facility prior to construction of the modified LMF stack show 
compliance with the permitted values, as do updated stack test results 
of the LMF stack upon construction completion as shown in Table 1. EPA 
concluded that Illinois' modeling is a suitable demonstration that its 
requirements in the Construction Permit for Alton Steel and all other 
Illinois sources in the nonattainment area were properly addressed in 
the attainment plan. EPA's supplemental modeling demonstrated that the 
updated 24-hour block limit for Ameren-Sioux of 7,342 lbs/hr in 
combination with updated emissions at Alton Steel provide for 
attainment and is the primary basis to conclude that the area is 
attaining the 2010 SO2 NAAQS.
    EPA has also considered additional information which supports its 
proposed determination that the area has attained the NAAQS, including 
annual SO2 emissions from the Alton Steel facility shown in 
Table 2. The annual tons per year emissions at the Alton facility show 
a decreasing trend overall. Annual SO2 emissions from the 
Ameren-Sioux facility found in Table 2 also show a decreasing trend 
overall. EPA included data from the Ameren-Sioux facility showing that 
hourly emissions with a 24-hour average, are at or below the newly 
established limit of 7,342 lbs/hr, and have been since 2017. These data 
are included in the docket of this action.\4\ In this action, EPA is 
proposing to find that the Alton Township area has attained and will 
continue to attain the 2010 SO2 NAAQS with respect to the 
redesignation criteria under CAA section 107(d)(3)(E)(i).
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    \4\ See Ameren Sioux (MO) Facility Emissions Data 2016-2023.xlsx 
in the docket.

                 Table 1--Alton Steel-LMF SO2 Emission Unit Stack Test Results for 2017 and 2020
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              Permit limit                      2017               2020                      Units
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0.10...................................              >0.05               0.06  Lbs/ton.
11.20..................................              >2.86               5.40  Lbs/hr.
37.50..................................              >4.75              23.70  Ton/yr.
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                                                         Table 2--Facility Annual SO2 Emissions
                                                                        [In tons]
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                                                      2016         2017         2018         2019         2020         2021         2022         2023
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Alton Steel Inc.................................        41.90        45.39        51.43        49.20        44.62        21.80        16.33        14.83
Ameren Sioux....................................     3,182.70     2,722.27     2,276.18     2,119.18     1,199.51     1,972.73     1,676.36       901.89
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    Additionally, with respect to nonattainment area requirements under 
CAA section 179(c), EPA is proposing to determine the Alton Township 
area attained the 2010 SO2 NAAQS by the area's attainment 
date of September 12, 2021. This is based on the information provided 
above, including the stack construction date in 2019 and emissions data 
shown to be below emission limits during and after the attainment 
period. Because this a separate CAA requirement, EPA may choose to 
finalize this determination separately, as this is not a redesignation 
criterion, but rather, just relying on the same set of facts.

Criteria (2) and Criteria (5)--Illinois Has Met All Applicable 
Requirements Under CAA Section 110 and Part D of the CAA, and EPA Has 
Fully Approved the Applicable Implementation Plan Under CAA Section 
110(k)

    For redesignating a nonattainment area to attainment under a NAAQS, 
a State must have met all applicable requirements (CAA section 
107(d)(3)(E)(v)), and EPA must have fully approved the applicable 
implementation plan (CAA section 107(d)(3)(E)(ii)). EPA's long-standing 
interpretation of the CAA is that not every requirement under CAA 
section 110 and part D are applicable for purposes of CAA section 
107(d)(3)(E)(ii) and (v). The Agency's interpretation of the statute 
limiting evaluation of section 110 and part D requirements to only 
those that are applicable for purposes of redesignation was first 
articulated shortly after the passage of the 1990 CAA Amendments in 
Agency guidance documents, and has been consistently applied in notice-
and-comment redesignation actions over the last three decades.
    Many of the section 110 elements that are unrelated to an area's 
SO2 attainment status are not applicable requirements for 
purposes of redesignation. The area will still be subject to these 
requirements after the area is redesignated to attainment of the 2010 
SO2 NAAQS. For example, the CAA section 110(a)(2)(D) 
interstate transport requirements for a State are not linked with a 
nonattainment area's designation and classification in that State, and 
continue to apply to States regardless of the designation status of 
areas within that State. However, even though many of the section 110 
requirements are not applicable for purposes of redesignation, EPA has 
in any case approved most elements of Illinois' section 110 
infrastructure SIP. See infrastructure SIP approval, 79 FR 62042 
(October 16, 2014); revisions to Prevention of Significant 
Deterioration (PSD) and Nonattainment New Source Review (NSR) programs, 
87 FR 20715 (April 8, 2022); State board requirements, 84 FR 49671 
(September 23, 2019); and emission limits of pollutants relevant to the 
2010 SO2 NAAQS, 80 FR 29535 (May 22, 2015).
    EPA also proposes to determine that Illinois has met and EPA has 
fully approved those part D requirements that are applicable for 
purposes of redesignation. Part D is comprised of the general 
nonattainment area plan requirements in subpart 1 (section 172) as well 
as pollutant specific subparts, including section 191 (or subpart 5), 
which applies to areas designated

[[Page 81413]]

nonattainment for SO2, nitrogen dioxide, or lead. While some 
nonattainment planning requirements are not applicable for purposes of 
CAA section 107(d)(3)(E)(ii) and (v) for areas that are attaining the 
NAAQS, Illinois has in any case submitted a complete attainment plan 
and EPA has fully approved that plan, including emissions inventories, 
Reasonably Available Control Technology/Reasonably Available Control 
Measures, Reasonable Further Progress (RFP), and contingency measures.
    On February 21, 2023 (88 FR 10464), EPA approved Illinois' 
attainment SIP for the Alton Township area including the operation of a 
new LMF stack at Alton Steel and revised emission limits for Ameren-
Sioux, which are the main SO2 sources affecting the Alton 
Township area. In that action, EPA found that Illinois had satisfied 
requirements for providing for attainment of the 2010 SO2 
NAAQS in the Alton Township area. The adopted SO2 SIP 
regulations for Alton Steel and Ameren-Sioux are contained in the 
Construction Permit for Alton Steel and the Ameren-Sioux Consent 
Agreement, respectively. Illinois has shown that it maintains an active 
enforcement program to ensure ongoing compliance with these 
requirements. Illinois' programs for NSR and PSD will address emissions 
from potential new sources in the area (57 FR 59928, December 17, 1992; 
60 FR 49780, September 27, 1995; 68 FR 25504, May 13, 2003). Missouri 
also maintains an active enforcement program under the Revised Statutes 
of Missouri section 643.080 to ensure ongoing compliance.
    In its attainment plan, Illinois chose 2017 for its base year 
emissions inventory as comprehensive data were available and updated 
that year, satisfying the requirements of section 172(c)(3) of the CAA. 
Illinois additionally examined whether any large sources beyond 10 
kilometers of the nonattainment area might also have significant air 
quality impacts in the area, resulting in the addition of Ameren-Sioux 
to the inventory. Illinois' SO2 emissions data identified 
Alton Steel and Ameren-Sioux as the main contributors to the 
nonattainment status for the Alton Township area.
    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 
requirements 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.) or the Federal Transit Act 
(49 U.S.C. 1601) (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 EPA promulgated pursuant to its authority under the 
CAA. EPA's longstanding interpretation of the CAA is that because CAA 
section 176(c) conformity requirements continue to apply after areas 
are redesignated to attainment, whether or not the area has met that 
requirement is not a prerequisite to getting redesignated. In addition, 
based on EPA's April 2014 SO2 Guidance, transportation 
conformity only applies to SO2 SIPs if transportation-
related emissions of SO2 as a precursor are a significant 
contributor to a fine particulate matter (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, neither of which apply to the Alton Township 
area. EPA concluded that highway and transit vehicles are not 
significant sources of SO2 in this area. As a result, 
transportation conformity determinations are not required in the Alton 
Township SO2 maintenance area. Therefore, transportation 
plans, transportation improvement programs and projects are presumed to 
conform to applicable implementation plans for SO2. With 
respect to general conformity, Federal agencies are still required to 
address general conformity in the Alton Township SO2 
maintenance area.
    Based on the above findings, EPA is proposing to find that Illinois 
has met the applicable requirements of section 110 and part D of title 
I of the CAA for purposes of the redesignation of the Alton Township 
nonattainment area, and EPA has fully approved the applicable 
implementation plan for such area.

Criteria (3)--The Air Quality Improvement in Alton Township SO2 
Nonattainment Area Is Due to Permanent and Enforceable Emission 
Reductions

    To redesignate an area from nonattainment to attainment, section 
107(d)(3)(E)(iii) of the CAA requires EPA to determine that the air 
quality improvement in the area is due to permanent and enforceable 
reductions in emissions resulting from the implementation of the SIP 
and applicable Federal air pollution control regulations and other 
permanent and enforceable emission reductions. Illinois' attainment 
plan incorporates the Alton Steel Construction Permit (88 FR 10464, 
February 21, 2023) which requires the operation of a new LMF stack and 
does not change any existing requirements that apply to the furnace in 
the LMF, including the permitted emission unit limits which the Alton 
Steel facility was already subject to. The permit approved the 
construction of a new LMF stack to be finalized no later than July 31, 
2019. The facility continues to meet existing SO2 emission 
limits that do not exceed 0.10 pound per ton of steel produced, 11.20 
lbs/hr, and 37.50 tons per year as shown in Table 1 above. EPA has 
included these emission limits and source configuration requirements in 
the approval of Illinois' SIP on February 21, 2023 (88 FR 10464), which 
will also render them federally enforceable. For Ameren-Sioux, a new 
limit was approved into the Missouri SIP establishing a more stringent 
limit of 7,342 lbs/hr averaged over a 24-hour block period. EPA 
approved Ameren-Sioux's new limit in a different rulemaking on November 
16, 2022 (87 FR 68634). The updated EPA modeling in Illinois' 
attainment plan approval (88 FR 10464, February 21, 2023) included the 
change in emissions at both Alton Steel and Ameren-Sioux and showed 
attainment of the 2010 SO2 standard throughout the Alton 
Township area. EPA is proposing to find, consistent with our approval 
of the State's attainment plan, that the modeling results demonstrate 
attainment and continued maintenance of the 2010 SO2 NAAQS 
and that the air quality improvement in the Alton Township 
nonattainment area is due to permanent and enforceable reductions in 
emissions.

Criteria (4)--The Alton Township SO2 Nonattainment Area Has a Fully 
Approved Maintenance Plan Pursuant to Section 175A

    As a part of a State's maintenance plan, the air agency should 
develop an attainment emissions inventory to identify the level of 
emissions in the affected area which is sufficient to attain and 
maintain the SO2 NAAQS.\5\ In its redesignation request, 
Illinois provided an emissions inventory for SO2 in the 
nonattainment area for 2022, one of the years making up the attaining 
design value. Total actual emissions in the Alton Township area for the 
2022 attainment year were 2,691.88 tons. This level of emissions, in 
combination with modifications at the Alton Steel facility,

[[Page 81414]]

are sufficient to maintain the NAAQS. In its attainment plan, Illinois 
reported that total actual SO2 emissions for the 
nonattainment area from 2017, a year during which the area was not 
attaining the NAAQS, were 4,280.97 tons. Construction of a new LMF 
stack at the Alton Steel facility to replace four downward facing 
vents, as well as the Consent Order limit of 7,342 lbs/hr averaged over 
a 24-hour block period accepted by the Ameren-Sioux power plant, led to 
decreases in actual SO2 emissions by over 1,580 tons in the 
Alton Township area between 2017 and 2022. Previously, EPA's modeling 
for the Alton Township area based on maximum allowable levels at Alton 
Steel and updated limits on Ameren-Sioux already incorporated into the 
Illinois SIP and Missouri SIP respectively, resulted in a design value 
of 74.9 ppb, below the SO2 NAAQS. See Alton SO2 
Nonattainment Plan TSD, 87 FR 80509 (December 30, 2022).
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    \5\ See April 2014 SO2 Guidance, page 66.
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    Section 175A of the CAA 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 ten years after the nonattainment 
area is redesignated 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 
ten years following the initial ten-year period. To address the 
possibility of future NAAQS violations, the maintenance plan must 
contain contingency measures, which EPA deems necessary to ensure 
prompt correction of any future 2010 SO2 NAAQS violations.
    Specifically, the maintenance plan should address five 
requirements: the attainment emissions inventory, maintenance 
demonstration, monitoring, verification of continued attainment, and a 
contingency plan. EPA is proposing to determine that Illinois' 
redesignation request of October 2, 2023, contains its maintenance plan 
and all the necessary components, which Illinois has committed to 
review eight years after the redesignation.
    As a part of a State's maintenance plan, the air agency should 
develop an attainment emissions inventory to identify the level of 
emissions in the affected area which is sufficient to attain and 
maintain the SO2 NAAQS.\6\ In its redesignation request, 
Illinois provided an emissions inventory for SO2 in the 
nonattainment area for 2022, one of the years making up the attaining 
design value. Total actual emissions in the Alton Township area for the 
2022 attainment year were 2,691.88 tons. This level of emissions, in 
combination with modifications at the Alton Steel facility, are 
sufficient to maintain the NAAQS. In its attainment plan, Illinois 
reported that total actual SO2 emissions for the 
nonattainment area from 2017, a year during which the area was not 
attaining the NAAQS, were 4,280.97 tons. Construction of a new LMF 
stack at the Alton Steel facility to replace four downward facing 
vents, as well as the Consent Order limit of 7,342 lbs/hr averaged over 
a 24-hour block period accepted by the Ameren-Sioux power plant, led to 
decreases in actual SO2 emissions by over 1,580 tons in the 
Alton Township area between 2017 and 2022. Previously, EPA's modeling 
for the Alton Township area based on maximum allowable levels at Alton 
Steel and updated limits on Ameren-Sioux already incorporated into the 
Illinois SIP and Missouri SIP respectively, resulted in a design value 
of 74.9 ppb, below the SO2 NAAQS. See Alton SO2 
Nonattainment Plan TSD, 87 FR 80509 (December 30, 2022).
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    \6\ See April 2014 SO2 Guidance, page 66.
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    EPA's ``Procedures for Processing Requests to Redesignate Areas to 
Attainment'' (Calcagni Memo) \7\ describes two ways for a State to 
demonstrate maintenance of the NAAQS 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 rate will not 
cause a violation of the standard. In both instances, the demonstration 
should be for a period of 10 years following the redesignation. 
Furthermore, the plan should contain a summary of air quality 
concentrations resulting from control measures implemented where 
modeling is relied upon to demonstrate maintenance. Illinois' 
maintenance demonstration consists of the attainment SIP air quality 
modeling analysis showing that the emissions reductions now in effect 
in the Alton Township area will provide for attainment of the 2010 
SO2 NAAQS. The permanent and enforceable SO2 
emission reductions described above ensure that the area emissions will 
be equal to or less than the emission levels that were evaluated in the 
air quality modeling analysis, and Illinois' enforceable emission 
requirements will ensure that the Alton Township area SO2 
emission limits are met continuously.
---------------------------------------------------------------------------

    \7\ Calcagni, John, Director, Air Quality Management Division, 
EPA Office of Air Quality Planning and Standards, ``Procedures for 
Processing Requests to Redesignate Areas to Attainment,'' September 
4, 1992.
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    By providing actual emissions data from Alton Steel and Ameren-
Sioux, the main sources of SO2, from a time period when the 
area was not meeting the NAAQS and from a time period when the area was 
attaining the NAAQS, Illinois demonstrates a 52 percent and 38 percent 
reduction in actual annual SO2 emissions at Alton Steel and 
Ameren-Sioux, respectively. Illinois' submittal shows that actual 
annual Alton Steel SO2 emissions in 2022 were 48 percent of 
the actual emissions in 2017 and shows actual annual 2022 Ameren-Sioux 
SO2 emissions were 62 percent of the actual emissions in 
2017. EPA's modeling described in the Criteria 4 section above, shows 
by modeling that modified LMF exhaust configuration at Alton Steel in 
addition to the newly imposed consent agreement SO2 limits 
for Ameren-Sioux, which are federally enforceable, result in the area 
maintaining attainment of the SO2 NAAQS.
    For continuing verification, Illinois has committed to track the 
emissions and compliance status of the major facilities in the Alton 
Township area so that future emissions will not exceed the allowable 
emissions-based attainment inventory. All major sources in Illinois are 
required to submit annual emissions data, which the State uses to 
update its emission inventories as required by the CAA. The Alton Steel 
facility must submit annual compliance certifications to ensure the 
facility is meeting its SIP limits and the facility must submit a semi-
annual Monitoring Report to the Illinois EPA, Air Compliance Section, 
summarizing required monitoring done and identifying all instances of 
deviation from the permit.
    Illinois has also committed to continue operating an ``appropriate 
air quality monitoring network to verify maintenance of the attainment 
status'' of the Alton Township area. However, the closest monitor to 
the Alton area is the East St. Louis monitor (AQS ID: 17-163-0010, 
coordinates: 38.61203-90.16048) approximately 30 kilometers south of 
the Alton Steel facility. As such, Illinois commits to providing EPA 
with annual emissions report of the newly constructed Alton Steel LMF 
stack as part of Illinois' annual network plan submittal to provide 
ongoing verification of attainment. The Ameren-Sioux facility is 
subject to annual emissions data reporting under EPA's Federal 
emissions trading programs and,

[[Page 81415]]

therefore, data are readily accessible via EPA's Clean Air Markets 
Program Division's database.\8\
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    \8\ See Ameren-Sioux emissions data at https://campd.epa.gov/data/custom-data-download.
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    Section 175A(d) of the CAA provides that a maintenance plan must 
contain contingency provisions that will promptly correct any violation 
of the 2010 SO2 NAAQS after the area is redesignated to 
attainment (Calcagni Memo). 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). Unlike CAA section 
172(c)(9), section l75A of the CAA does not explicitly require that 
contingency measures must take effect without further action by the air 
agency in order for the maintenance plan to be approved. However, the 
maintenance plan's contingency plan would become an enforceable part of 
the SIP and should ensure that contingency measures are adopted and 
implemented as expeditiously as practicable once they are triggered.\9\ 
In the ``General Preamble for the Implementation of Title I of the 
Clean Air Act Amendments of 1990,'' published on April 16, 1992 (57 FR 
13498), EPA provides further discussion of contingency measures for 
SO2. This guidance States that in many cases, attainment 
revolves around compliance of a single source or a small set of sources 
with emission limits shown to provide for attainment. Although this 
guidance applies to contingency measures under section 172(c)(9), EPA 
applies a similar policy with respect to contingency measures for 
SO2 required in maintenance plans under section 175A(d). The 
requirement to submit contingency measures in accordance with section 
175A of the CAA can be adequately addressed for SO2 by the 
operation of a comprehensive enforcement program,\10\ which can quickly 
identify and address sources that might be causing exceedances of the 
NAAQS. Illinois' enforcement program is active and capable of prompt 
action to remedy compliance issues. Illinois commits to ongoing 
compliance and enforcement of the control measures contained in the 
federally enforceable Construction Permit issued to Alton Steel 
approved and incorporated into the Illinois' attainment SIP approval 
(88 FR 10464, February 21, 2023). Illinois also has the necessary 
resources in the event of violations to enforce its permit provisions 
and rules. Illinois has the authority to expeditiously adopt, 
implement, and enforce any subsequent emission control measures deemed 
necessary to correct any future SO2 violations. Illinois 
commits to adopting and implementing such corrective actions as 
necessary to address violations of the 2010 SO2 NAAQS. 
Another contingency measure option is the implementation of a PSD 
program for new or modified existing sources of SO2, which 
includes requirements for Best Available Control Technology, in the 
Alton nonattainment area once redesignated to attainment. The Ameren-
Sioux Consent Agreement has been adopted into the Missouri SIP and 
includes monitoring, recordkeeping, and reporting requirements that 
will be used to confirm ongoing compliance incorporated into the 
Missouri SIP (87 FR 68634, November 16, 2022). Based on the foregoing, 
EPA proposes to find that Illinois has addressed the contingency 
measure requirement.
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    \9\ See April 2014 SO2 Guidance, page 74.
    \10\ See April 2014 SO2 Guidance, page 41-42.
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    EPA is proposing to find that Illinois' maintenance plan adequately 
addresses the five basic components of a maintenance plan necessary to 
maintain the SO2 NAAQS in the Alton Township nonattainment 
area. Therefore, EPA proposes to find that the redesignation and 
maintenance plan SIP revision submitted by Illinois for the 2010 
SO2 Alton Township nonattainment area meets the requirements 
of section 175A of the CAA and proposes to approve this plan.

III. What action is EPA taking?

    EPA is proposing to redesignate the Alton Township area from 
nonattainment to attainment for the 2010 SO2 NAAQS in 
accordance with Illinois' October 2, 2023, request. EPA has determined 
that the area is attaining the 2010 SO2 NAAQS and that the 
improvement in air quality is due to permanent and enforceable 
SO2 emission reductions in the area. EPA is also proposing 
to approve Illinois' maintenance plan, which is designed to ensure that 
the area will continue to maintain attainment of the 2010 
SO2 NAAQS. Additionally, EPA is proposing to determine the 
Alton Township area attained the 2010 SO2 NAAQS by the 
September 12, 2021, attainment date addressing EPA's obligation under 
CAA section 179(c).

IV. Environmental Justice Concerns

    To identify environmental burdens and potentially susceptible 
populations in the Alton Township area, EPA performed a screening-level 
analysis using EPA's environmental justice (EJ) screening and mapping 
tool (EJScreen).\11\ The results of EPA's screening analysis are being 
provided for informational and transparency purposes, and EPA did not 
rely on these findings in its action on Illinois' submissions. EPA 
utilized the EJScreen tool to review environmental and demographic 
data, which provides an assessment of individual demographic groups of 
the populations living within the Alton Township area in Madison 
County. The tool output report is contained in the docket for this 
action. Due to the localized nature of SO2, EPA considered a 
1.5-mile radius of the Alton Steel facility in its assessment. EPA's 
screening-level analysis indicates that communities affected by this 
action score above the national percent average for the EJScreen 
``Demographic Index'', which is the average of an area's percent 
minority and percent low-income populations, i.e., the two demographic 
indicators explicitly named in Executive Order 12898. Additionally, the 
results indicate that the area scores below the 80th percentile (in 
comparison to the nation as a whole) for 8 out of the 13 EJ indexes 
established by EPA, which include a combination of environmental and 
demographic information. The Alton Township area scored at or above the 
80th percentile for the ozone, toxic releases to the air, lead paint, 
RMP facility proximity, and wastewater discharge indexes. The analysis 
was done for the purpose of providing additional context and 
information about this rulemaking to the public, and not as a basis of 
the action. Due to the nature of the action being taken here, this 
action is expected to have a neutral to positive impact on the air 
quality of the affected area.
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    \11\ See https://www.epa.gov/ejscreen.
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V. Statutory and Executive Order Reviews

    Under the CAA, redesignation of an area to attainment and the 
accompanying approval of a maintenance plan are actions that affect the 
status of a geographical area and do not impose any additional 
regulatory requirements on sources beyond those imposed by State law. A 
redesignation to attainment does not in and of itself create any new 
requirements, but rather results in the applicability of requirements 
contained in the CAA for

[[Page 81416]]

areas that have been redesignated to attainment. Moreover, 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, 
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 these reasons, 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 14094 (88 FR 21879, April 11, 2023);
     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 subject to Executive Order 13045 (62 FR 19885, 
April 23, 1997) because it approves a State program;
     Is not a significant regulatory action subject to 
Executive 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 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).
    Executive Order 12898 (Federal Actions to Address Environmental 
Justice in Minority Populations and Low-Income Populations, 59 FR 7629, 
February 16, 1994) directs Federal agencies to identify and address 
``disproportionately high and adverse human health or environmental 
effects'' of their actions on communities with EJ concerns to the 
greatest extent practicable and permitted by law. EPA defines EJ as 
``the fair treatment and meaningful involvement of all people 
regardless of race, color, national origin, or income with respect to 
the development, implementation, and enforcement of environmental laws, 
regulations, and policies.'' EPA further defines the term fair 
treatment to mean that ``no group of people should bear a 
disproportionate burden of environmental harms and risks, including 
those resulting from the negative environmental consequences of 
industrial, governmental, and commercial operations or programs and 
policies.''
    Illinois did not include an evaluation of EJ considerations as part 
of its SIP submittal; the CAA and applicable implementing regulations 
neither prohibit nor require such an evaluation. EPA performed an EJ 
analysis, as is described above in the section titled, ``Environmental 
Justice Considerations.'' The analysis was done for the purpose of 
providing additional context and information about this rulemaking to 
the public, and not as a basis of the action. Due to the nature of the 
action being taken here, this action is expected to have a neutral to 
positive impact on the air quality of the affected area. In addition, 
there is no information in the record upon which this decision is based 
inconsistent with the stated goal of E.O. 12898 of achieving EJ for 
communities with EJ concerns.

List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Incorporation by 
reference, Intergovernmental relations, Reporting and recordkeeping 
requirements, Sulfur oxides.

    Dated: October 2, 2024.
Debra Shore,
Regional Administrator, Region 5.
[FR Doc. 2024-23164 Filed 10-7-24; 8:45 am]
BILLING CODE 6560-50-P