Document ID: EPA-R07-OAR-2022-0531-0006
Agency: epa
Document Type: Rule
Title: Air Quality State Implementation Plans; Approvals and Promulgations: Missouri; Control of Sulfur Dioxide Emissions
Posted Date: 2023-01-04T05:00Z

[Federal Register Volume 88, Number 2 (Wednesday, January 4, 2023)]
[Rules and Regulations]
[Pages 291-297]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-28139]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R07-OAR-2022-0531; FRL-9976-02-R7]

Air Plan Disapproval; Missouri; Control of Sulfur Dioxide 
Emissions

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: The Environmental Protection Agency (EPA) is taking final 
action to disapprove revisions to the Missouri State Implementation 
Plan (SIP)

[[Page 292]]

submitted by Missouri on March 7, 2019. In its submission, Missouri 
requested rescinding a regulation addressing sulfur compounds from the 
SIP and replacing it with a new regulation that establishes 
requirements for units emitting sulfur dioxide (SO2). The 
EPA is disapproving the SIP revision because the state has not 
demonstrated that the removal of SO2 emission limits for the 
Evergy-Hawthorn (Hawthorn, formerly Kansas City Power & Light-Hawthorn) 
and Ameren Labadie (Labadie) power plants from the SIP would not 
interfere with National Ambient Air Quality Standard (NAAQS) attainment 
and reasonable further progress (RFP), or any other applicable 
requirement of the Clean Air Act (CAA). This disapproval action is 
being taken under the CAA to maintain the stringency of the SIP and 
preserve air quality.

DATES: The final rule is effective on February 3, 2023.

ADDRESSES: The EPA has established a docket for this action under 
Docket ID No. EPA-R07-OAR-2022-0531. All documents in the docket are 
listed on the https://www.regulations.gov web site. Although listed in 
the index, some information is not publicly available, i.e., CBI or 
other information whose disclosure is restricted by statute. Certain 
other material, such as copyrighted material, is not placed on the 
internet and will be publicly available only in hard copy form. 
Publicly available docket materials are available through https://www.regulations.gov or please contact the person identified in the FOR 
FURTHER INFORMATION CONTACT section for additional information.

FOR FURTHER INFORMATION CONTACT: Wendy Vit, Environmental Protection 
Agency, Region 7 Office, Air Quality Planning Branch, 11201 Renner 
Boulevard, Lenexa, Kansas 66219; telephone number: (913) 551-7697; 
email address: [email protected].

SUPPLEMENTARY INFORMATION: Throughout this document ``we,'' ``us,'' and 
``our'' refer to the EPA.

Table of Contents

I. What is being addressed in this document?
II. What is the EPA's analysis of the SIP revisions?
III. Have the requirements for approval of a SIP revision been met?
IV. The EPA's Responses to Comments
V. What action is the EPA taking?
VI. Statutory and Executive Order Reviews

I. What is being addressed in this document?

    The EPA is disapproving a submission from Missouri requesting to 
revise the SIP by removing 10 Code of State Regulations (CSR) 10-6.260 
``Restriction of Emission of Sulfur Compounds'' and replacing it with a 
new state regulation, 10 CSR 10-6.261 ``Control of Sulfur Dioxide 
Emissions'' (effective date March 30, 2019). Missouri submitted its 
request on March 7, 2019. 10 CSR 10-6.260 was originally approved into 
the SIP at 40 CFR 52.1320(c) in 1998 (63 FR 45727, August 27, 1998) and 
has been revised several times.\1\ 10 CSR 10-6.261 has not been 
approved into the SIP. Missouri's analysis of the requested SIP 
revisions can be found in the technical support document (TSD) 
submitted to the EPA on May 4, 2022, which is included in this docket. 
The EPA proposed to disapprove these SIP revisions on July 8, 2022 (87 
FR 40759). A summary of the EPA's analysis of Missouri's requested SIP 
revisions is in section II of this document, and additional detail can 
be found in section II of the proposal.
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    \1\ See 71 FR 12623 (March 13, 2006), 73 FR 35071 (June 20, 
2008), and 78 FR 69995 (November 22, 2013).
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II. What is the EPA's analysis of the SIP revisions?

    In order for the EPA to fully approve a SIP revision, the state 
must demonstrate that the SIP revision meets the requirements of CAA 
section 110(l), 42 U.S.C. 7410(l). Under CAA section 110(l), the EPA 
may not approve a SIP revision that would interfere with any applicable 
requirement concerning NAAQS attainment and RFP, or any other 
applicable requirement of the CAA. The EPA interprets section 110(l) 
such that states have two main options to make this noninterference 
demonstration. First, a state could demonstrate that emission 
reductions removed from the SIP are substituted with new control 
measures that achieve equivalent or greater emission reductions/air 
quality benefit. Thus, the SIP revision would not interfere with the 
area's ability to continue to attain or maintain the affected NAAQS or 
other CAA requirements. The EPA further interprets section 110(l) as 
requiring such substitute measures to be quantifiable, permanent, 
surplus, and enforceable.\2\ For section 110(l) purposes, ``permanent'' 
means the state cannot modify or remove the substitute measure without 
EPA review and approval. Additionally, when a control measure that was 
previously approved into the SIP is relied on as a substitute, the 
emission reductions must be ``surplus,'' meaning they cannot otherwise 
be relied on for attainment/maintenance or Rate of Progress/Reasonable 
Further Progress requirements. Second, another option for the 
noninterference demonstration is for a state to develop an air quality 
analysis showing that, even without the control measure or with the 
control measure in its modified form, the area (as well as interstate 
and intrastate areas downwind) can continue to attain and maintain the 
affected NAAQS. For this air quality analysis option, the state could 
conduct air quality modeling or develop an attainment or maintenance 
demonstration based on the EPA's most recent technical guidance.
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    \2\ In addition, if a new substitute control measure is relied 
on in a CAA section 110(l) noninterference demonstration, the new 
substitute measure should be contemporaneous to the time the 
emission reductions from the removed/modified measure cease 
occurring. Because the substitute control measures discussed in this 
action are existing measures, not new measures, whether or not they 
are contemporaneous is not a consideration in this disapproval 
action.
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    Missouri's proposed SIP revisions would remove SO2 
emission limits for the Hawthorn and Labadie power plants from the SIP. 
The Hawthorn SO2 emission limit is a 30-day rolling average 
limit of 0.12 pounds/million British thermal units (lb/MMBtu) contained 
in Table I of 10 CSR 10-6.260 in the SIP. The Labadie SO2 
emission limit is a daily average of 4.8 lb/MMBtu found at 10 CSR 10-
6.260 (3)(B)3.A.(II) in the SIP. As discussed in detail in its TSD, 
Missouri contends that there are substitute measures of comparable or 
greater stringency to these SO2 emission limits for Hawthorn 
and Labadie, and therefore argues that removal of these limits from the 
SIP would satisfy CAA section 110(l) requirements without the need for 
an air quality analysis showing that removing the measures will not 
interfere with NAAQS attainment or other applicable requirements.
    We disagree with Missouri's analysis and rationale for removing the 
Hawthorn and Labadie SO2 emission limits from the SIP. The 
substitute SO2 emission limit for Hawthorn is an equivalent 
SO2 emission limit contained in a Prevention of Significant 
Deterioration (PSD) permit. Although the Hawthorn PSD permit is 
federally enforceable, it is not approved into the SIP and could be 
later modified without requiring EPA approval, and therefore the 
substitute measure is not considered permanent.
    For Labadie, the substitute SO2 emission limit is a 
facility-wide SO2 emission limit of 40,837 pounds per hour 
(lb/hr) contained in a Consent Agreement that the EPA approved into the 
SIP at 40 CFR 52.1320(d) as part of the maintenance plan for the 
Jefferson County, Missouri nonattainment area

[[Page 293]]

when the area was redesignated to attainment for the 1-hour 
SO2 NAAQS (87 FR 4508, January 28, 2022). 10 CSR 10-6.261 
does not include any of the limits contained in the Consent Agreement. 
The proposal details our analysis showing that the 4.8 lb/MMBtu limit, 
which applies to each of Labadie's four units individually, is more 
stringent than the 40,847 lb/hr limit in the Consent Agreement under 
certain operating scenarios. As an example, our analysis shows that 
Labadie could exceed the 4.8 lb/MMBtu limit but still comply with the 
Consent Agreement limit when a single unit is operating at 100% load. 
Furthermore, because the SO2 emission limit for Labadie 
contained in the already SIP-approved Consent Agreement is being relied 
upon for the purpose of maintaining the 1-hour SO2 NAAQS in 
the Jefferson County area, it cannot be considered surplus. In 
addition, Missouri has not provided an air quality analysis 
demonstrating their proposed SIP revisions related to the Labadie 
SO2 emission limits will not interfere with NAAQS attainment 
or other applicable requirements.

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

    As explained above, because the EPA's approval of Missouri's 
requested SIP revisions would not be consistent with CAA section 
110(l), we are disapproving the submission. However, the state 
submission 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 of the revisions from August 1, 2018, to October 4, 2018, 
and held a public hearing on September 27, 2018. The state received and 
addressed four comments from three entities, which included the EPA. 
The state did not make changes to 10 CSR 10-6.261 as a result of 
comments received prior to submitting to the EPA.

IV. The EPA's Responses to Comments

    The public comment period on the EPA's proposed rule opened July 8, 
2022, the date of its publication in the Federal Register, and closed 
on August 8, 2022. During this period, the EPA received comments from 
one commenter, the Missouri Department of Natural Resources (MoDNR), 
which are addressed below.
    Comment 1: The commenter states that the EPA's proposed action is 
inconsistent with the plain text of CAA section 110(l). The commenter 
argues that Missouri's SIP does not rely on either of the limits in 
question for demonstrating attainment, maintenance, or RFP for any 
NAAQS, and therefore, removal of the limits will not interfere with any 
of these SIP requirements. The commenter contends that the EPA's 
proposed disapproval injects new language into CAA section 110(l) 
requiring states to prove a submitted SIP revision could never 
interfere with attainment, RFP, or other applicable requirements. On 
the contrary, according to the commenter, the plain text of the CAA 
requires the EPA to prove the revision would interfere with applicable 
CAA requirements. The commenter concludes that because the EPA made no 
attempt to demonstrate the SIP revision would interfere with any of 
these requirements, the EPA's basis for disapproval lacks a necessary 
finding that interference would occur.
    Response to Comment 1: States have primary responsibility for air 
quality within their jurisdictions by submitting SIPs and SIP revisions 
that specify the manner in which the NAAQS will be achieved and 
maintained. 42 U.S.C. 7407(a); Concerned Citizens of Bridesburg v. EPA, 
836 F.2d 777, 779 (3d Cir. 1987) (The ``states have the primary 
authority for establishing a specific plan . . . for achieving and 
maintaining acceptable levels of air pollutants in the atmosphere.''). 
After the EPA promulgates the NAAQs, or a revision thereof, each state 
must submit to the EPA a SIP for the ``implementation, maintenance, and 
enforcement'' of the standard. 42 U.S.C. 7410(a)(1). The contents of 
SIPs and the requirements they must fulfill with respect to each NAAQS 
depend upon the designations and classifications of an area. States 
must formally adopt SIPs or SIP revisions through state-level notice-
and-comment rulemaking. Id. Sec.  7410(a)(2).
    The EPA's role is to review the SIP or SIP revision. The EPA 
``shall'' approve the SIP or SIP revision if it meets the minimum 
requirements of the CAA. Id. section 7410(k)(3); Train v. Nat. Res. 
Def. Council, Inc., 21 U.S. 60, 79 (1975). The EPA cannot disapprove 
state regulations that form a SIP or SIP revision because the EPA 
decides that the regulations should be more stringent, as long as the 
SIP meets the CAA requirements. See Union Elec Co. v. EPA, 427 U.S. 
246, 265 (1976); Duquesne Light Co. v. EPA, 166 F.3d 609, 611, 613 (3d 
Cir. 1999).
    CAA section 110(l), 42 U.S.C. 7410(l), provides in relevant part, 
that ``[t]he Administrator shall not approve a revision of a plan if 
the revision would interfere with any applicable requirement concerning 
attainment.'' The EPA has consistently interpreted CAA section 110(l) 
as permitting approval of a SIP revision as long as ``emissions in the 
air are not increased,'' thereby preserving ``status quo air quality.'' 
Ky. Res. Council, Inc. v. EPA, 467 F.3d. 986, 991, 996 (6th Cir. 2006); 
see also Indiana v. EPA, 796 F.3d 803, 805 (7th Cir. 2015) (same); Ala. 
Env't Council v. EPA, 711 F.3d 1277, 1292-93 (11th Cir. 2013) (same); 
Galveston-Houston Ass'n for Smog Prevention v. EPA, 289 F. App'x 745, 
754 (5th Cir. 2008) (same). CAA section 110(l) is an 
``antibacksliding'' provision that does not impose substantive 
obligations, but instead erects a ``high threshold for removing 
controls from a SIP.'' S. Coast Air Quality Mgmt. Dist. v. EPA, 472 
F.3d 882, 900 (D.C. Cir. 2006), decision clarified on denial of reh'g 
on other grounds, 489 F.3d 1245 (D.C. Cir. 2007) (emphasis added); see 
also Indiana, 796 F.3d at 806 (describing CAA section 110(l) as an 
``antibacksliding'' provision).
    The EPA implements this interpretation of CAA section 110(l) by 
approving SIP revisions if they do not allow an increase of net 
emissions. In doing so, ``the level of rigor needed for any CAA 
[section 110(l)] demonstration will vary depending on the nature and 
circumstances of the revision.'' \3\ Where the EPA anticipates that a 
SIP revision may increase emissions, it typically requires that a state 
either (1) submit an air quality analysis to demonstrate that the 
revision would not interfere with any applicable requirement or (2) 
substitute equivalent or greater emissions reductions in order to 
preserve status quo air quality. See 86 FR 48908, September 1, 2021, at 
48910 and 86 FR 60170, November 1, 2021, at 60172; see also Ky. Res. 
Council, 467 F. 3d at 995 (denying petition challenging SIP revision 
approval under CAA section 110(l) where the revision would not increase 
net emissions).
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    \3\ See Approval and Promulgation of Air Quality Implementation 
Plans; Pennsylvania; Reasonably Available Control Technology 
Determinations for Case-by-Case Sources Under the 1997 and 2008 8-
Hour Ozone National Ambient Air Quality Standards, Final Rule, 86 FR 
48908, September 1, 2021, at 48910. Also see Air Plan Approval; 
Pennsylvania; Reasonably Available Control Technology Determinations 
for Case-by-Case Sources Under the 2008 8-Hour Ozone National 
Ambient Air Quality Standards, Final Rule, 86 FR 60170, November 1, 
2021, at 60172.
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    As described in the proposal, the substitute SO2 
emission limit for Hawthorn is contained in a PSD permit that is not 
SIP-approved and therefore is not considered permanent. For Labadie, 
the substitute SO2 emission limit in the SIP-approved 
Consent Agreement is less stringent in certain operating scenarios

[[Page 294]]

than the limit in 10 CSR 10-6.260 in the SIP and does not result in 
surplus emission reductions. Because the substitute limit is less 
stringent, Missouri would need to provide an air quality analysis 
showing that removing the 4.8 lb/MMBtu limit from the SIP will not 
interfere with any CAA requirement including but not limited to NAAQS 
attainment, and of most relevance, the current 1-hour SO2 
NAAQS, or alternatively provide substitute emissions reductions that 
are equivalent or greater to protect air quality.
    Comment 2: The commenter states that CAA section 110(l) requires 
the EPA to make a finding that removal of the Hawthorn SO2 
limit would result in an emission increase that would interfere with an 
applicable CAA requirement. The commenter says the EPA cannot show that 
removal of the Hawthorn limit from the rule would result in any 
emissions increase and therefore the EPA lacks the basis for 
disapproving the SIP due to its concerns about Hawthorn. The commenter 
says Hawthorn's limit has not been changed in over 20 years since the 
permit was issued, and there is no cause to believe this permit limit 
would ever be relaxed. In addition, the commenter notes that Hawthorn's 
permit was issued under SIP-approved state new source review (NSR) 
rule, 10 CSR 10-6.060 ``Construction Permits Required,'' which 
incorporates by reference federal PSD requirements. The commenter 
further contends that removing an emission limit from a major source 
like Hawthorn in a future permitting action would trigger the PSD 
permit review process, in which case the facility would be subject to a 
more recent New Source Performance Standard requirement for 
SO2, as well as NAAQS impact and Best Available Control 
Technology analyses, which would likely result in a SO2 
limit that is equal to, if not more stringent than, the limit in the 
SIP-approved rule.
    Response to Comment 2: As stated in the proposal, the disapproval 
is not based on an expectation that Hawthorn emissions would increase 
if the limit were removed from the SIP. Rather, our rationale is based 
on Missouri's reliance on a substitute measure that is not SIP-
approved.\4\ The equivalent SO2 emission limit in Hawthorn's 
federally enforceable PSD permit is not considered permanent because it 
is not contained in the Missouri SIP and could be modified without 
requiring EPA approval. While the EPA can provide comments on PSD 
permits during the state's public notice period, Missouri can issue or 
modify PSD permits that are not in the SIP without EPA approval 
pursuant to SIP-approved NSR rule, 10 CSR 10-6.060, and the State's 
federally approved permitting program. Because substitute emission 
reduction measures must be not only enforceable but also permanent to 
be used for 110(l) analysis purposes, it would be inconsistent with CAA 
section 110(l) to approve the removal of a SIP-approved limit based on 
a permit that is not SIP-approved.
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    \4\ See CAA section 110(a)(2)(D) (``Each such [SIP] shall . . . 
contain adequate provisions . . .''). See also CAA section 
110(a)(2)(A); Committee for a Better Arvin v. EPA, 786 F.3d 1169, 
1175-1176 (9th Cir. 2015) (holding that measures relied on by a 
state to meet CAA requirements must be included in the SIP).
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    Comment 3: The commenter states that 10 CSR 10-6.260 in the SIP 
includes a footnote to Table I in 10 CSR 10-6.260 stating the emission 
limit comes from the PSD permit and is implemented in accordance with 
the terms of the permit. The commenter says it is unclear why EPA 
allowed for all the enforceable requirements for implementation of the 
limit in 10 CSR 10-6.260 to be dictated by the permit itself, but now 
indicates it is not acceptable to rely on the permit conditions due to 
their lack of permanence.
    Response to Comment 3: In order for a source-specific permit limit 
to be practically enforceable, the permit must specify (1) a 
technically accurate limitation and the portions of the source subject 
to the limitation; (2) the time period for the limitation (e.g., 
hourly, daily, monthly, annually); and (3) the method to determine 
compliance including appropriate monitoring, record keeping and 
reporting.\5\ Through regulations and policies, the EPA has long 
interpreted the CAA to require monitoring, record keeping, reporting 
and other compliance assurance measures in SIPs. As stated previously, 
the substitute SO2 emission limit for Hawthorn must be SIP-
approved to ensure that it cannot be removed or modified without EPA 
approval. It follows that the associated monitoring, record keeping, 
and reporting provisions that make the limit practically enforceable 
must also be approved into the SIP, otherwise these enforceability 
provisions could be modified without EPA approval.
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    \5\ The EPA guidelines on ``practical enforceability'' 
considerations are contained in a January 25, 1995 memorandum from 
the EPA's Office of Enforcement and Compliance Assurance (OECA) 
entitled ``Guidance on Enforceability Requirements for Limiting 
Potential to Emit through SIP and Sec.  112 Rules and General 
Permits.''
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    After carefully reviewing our previous actions pertaining to 10 CSR 
10-6.260, we have discovered that monitoring, record keeping, and 
reporting provisions associated with the Hawthorn SO2 limit 
that should have been included in the SIP were not in fact included. 
However, this previous omission from the State's prior submissions does 
not justify or allow for the subsequent removal of the numerical limit 
and averaging period from the approved SIP. In light of the continued 
omission from the SIP of monitoring, reporting and recordkeeping 
provisions associated with Hawthorn's approved SO2 emission 
limit, the EPA is not taking final action on its proposed determination 
that there is no deficiency in the SIP.
    Comment 4: The commenter notes that in January of 2022, the EPA 
redesignated the Jackson County, Missouri SO2 nonattainment 
area to attainment (87 FR 4812, January 31, 2022). The commenter 
explains that a separate 24-hour average SO2 limit for 
Hawthorn from the same PSD permit was relied on in the modeling 
demonstration for the Jackson County maintenance plan and 
redesignation. Hawthorn's 24-hour SO2 limit is also not SIP-
approved. The commenter questions why the EPA allowed the use of a non-
SIP approved permit limit in a maintenance demonstration (which 
directly concerns attainment), but now indicates it is not acceptable 
to remove a limit from the SIP when the equivalent limit exists in the 
permit.
    Response to Comment 4: To redesignate a nonattainment area to 
attainment, CAA section 107(d)(3)(E)(iii) specifies that the air 
quality improvement must be due to permanent and enforceable reductions 
in emissions. The Jackson County redesignation to attainment for the 1-
hour SO2 NAAQS was based on Missouri's demonstration that 
the air quality improvement resulted from permanent and enforceable 
emission reductions at the Vicinity Energy-Kansas City (Vicinity) steam 
plant.\6\ The State's demonstration for the Jackson County 
redesignation did not rely on SO2 emission reductions at the 
Hawthorn power plant.
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    \6\ See 87 FR 4812, January 31, 2022. Vicinity switched from 
burning coal to natural gas in its boilers. The fuel switch was made 
permanent and enforceable via a Consent Agreement approved into the 
SIP at 40 CFR 52.1320(d).
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    Hawthorn is located approximately two kilometers outside of the 
Jackson County nonattainment area boundary. In Missouri's modeling 
demonstration supporting the redesignation, the state included Hawthorn 
as a ``nearby source'' in accordance with Table 8-1 in

[[Page 295]]

40 CFR part 51, appendix W, which allows the source to be modeled at 
its maximum allowable emission limit or federally enforceable permit 
limit with adjustments based on actual operations. It was acceptable 
for Missouri to model Hawthorn as a nearby source using a federally 
enforceable PSD limit that was not SIP-approved rather than as a 
``stationary point source subject to SIP emissions limit evaluation for 
compliance with ambient standards'' under Appendix W Table 8-1 because 
(1) Hawthorn was not relied on for the state's maintenance 
demonstration that air quality improvements resulted from permanent and 
enforceable SO2 emission reductions, and (2) Hawthorn is 
located outside of the former nonattainment area boundary.
    Comment 5: The commenter provided a summary of Labadie's total 
monthly SO2 emissions allowed under the unit-specific 4.8 
lb/MMBtu limit contained in 10 CSR 10-6.260 and the facility-wide 
Consent Agreement limit of 40,837 lb/hr. Based on this summary, the 
commenter concludes that the Consent Agreement limit reduces Labadie's 
allowable facility-wide SO2 emissions by 66 percent and is 
therefore more stringent, making the older 4.8 lb/MMBtu limit obsolete. 
The commenter further states that an air quality modeling analysis 
comparing the stringencies of the two limits would show the Consent 
Agreement limit is nearly three times more protective than the 4.8 lb/
MMBtu limit.
    Response to Comment 5: As demonstrated in Missouri's modeling 
analysis supporting the redesignation of Jefferson County to attainment 
for the 1-hour SO2 NAAQS, the Consent Agreement limit of 
40,837 lb/hr was set at a level that addresses Labadie's contributions 
to the Jefferson County SO2 nonattainment area.\7\ However, 
that analysis does not demonstrate that the Consent Agreement limit is 
protective of the 1-hour SO2 NAAQS in all locations, 
including locations outside the Jefferson County area, nor does it 
demonstrate that removal of the 4.8 lb/MMBtu limit would not interfere 
with any applicable requirements consistent with an air quality 
analysis under CAA section 110(l).
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    \7\ Labadie is located approximately 36 kilometers outside of 
the Jefferson County nonattainment area boundary to the northwest.
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    As described previously, where the EPA anticipates that a SIP 
revision may allow an increase in emissions, the EPA typically requires 
that a state either substitute equivalent or greater emissions 
reductions or submit an air quality analysis demonstrating that the 
revision would not interfere with any applicable requirement. In this 
case, to compare the stringencies of the two different SO2 
emission limits (the Consent Agreement limit of 40,837 lb/hr versus 4.8 
lb/MMBtu), the limits must first be converted so that they are in 
equivalent units of measure (i.e., both limits expressed as either lb/
MMBtu or lb/hr) and apply to the same number of emission units (i.e., 
both limits expressed on either a facility-wide basis or an individual 
unit basis). This analysis requires making assumptions about the number 
of units that are operating, as well as the heat input rate and load of 
the individual units in operation. As discussed in the proposal, there 
are potential operating scenarios in which individual units at Labadie 
could exceed an SO2 rate of 4.8 lb/MMBtu while total 
facility-wide SO2 emissions remain in compliance with the 
40,837 lb/hr limit. Examples include a single unit operating at 100% 
load or two units operating at approximately 50% load, among other 
scenarios. Because the SO2 limit of 4.8 lb/MMBtu can be 
shown to be exceeded in some situations, we conclude that the limit in 
the Consent Agreement is not more stringent. For this reason, an air 
quality analysis demonstrating that removal of the 4.8 lb/MMBtu limit 
from the SIP would be protective of the 1-hour SO2 NAAQS is 
needed.
    An air quality analysis for the requested SIP revisions may need to 
take into account multiple operating scenarios because dispersion of 
SO2 emissions from one or two units at Labadie may be 
different from four units with the same mass of SO2 
emissions.\8\ As an example, one scenario could be based on a 
concentrated SO2 plume from a single stack consisting of 
mass emissions totaling 40,847 lb/hr from one of Labadie's units 
operating at an SO2 rate at or above 4.8 lb/MMBtu. Other 
potential operating scenarios may also need to be included in the air 
quality analysis (e.g., two of Labadie's units operating at 50% load 
emitting from two separate stacks or from the dual flue stack) in order 
to demonstrate that the removal of the 4.8 lb/MMBtu limit is protective 
of the 1-hour SO2 NAAQS in all areas. An air quality 
modeling demonstration comparing the stringencies of the two limits, as 
suggested in the comment, is not sufficient for CAA section 110(l) 
purposes.
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    \8\ Labadie units 1 and 2 are each routed to separate, 
individual stacks. Labadie units 3 and 4 are vented through two 
flues contained in a single stack.
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    Comment 6: The commenter notes that the EPA's basis for stating the 
Consent Agreement limit is not always more stringent than the older 4.8 
lb/MMBtu limit is based on a scenario where only one unit at the 
facility is operating during a day. The commenter states that while 
this is technically true, if the facility were to take advantage of the 
facility-wide Consent Agreement limit in this way, it would prevent the 
operation of any of the other three units that day. The commenter 
states that conversely, the 4.8 lb/MMBtu limit does not prevent 
additional units from operating if one of the units hits the maximum 
allowable rate. The commenter concludes that even under the EPA's 
hypothetical scenario, the Consent Agreement limit is still more 
stringent and more protective than the 4.8 lb/MMBtu limit.
    Response to Comment 6: As discussed above, our analysis based on 
multiple potential operating scenarios shows that the 4.8 lb/MMBtu 
limit is more stringent than the Consent Agreement limit in some cases. 
Consistent with CAA section 110(l), in order to support removal of the 
4.8 lb/MMBtu limit from the SIP, Missouri would need to provide an air 
quality analysis showing that the 1-hour SO2 NAAQS would be 
protected in all areas under these operating scenarios if the 4.8 lb/
MMBtu limit were removed from the SIP. Alternatively, Missouri could 
demonstrate that the various operating scenarios assumed for Labadie 
are prohibited by permanent and enforceable measures to be included in 
the SIP.
    Comment 7: The commenter analyzed daily and hourly emissions data 
from the EPA's Clean Air Markets Division (CAMD) database and concluded 
there was not a single day in the last five years when only one unit at 
Labadie was operating. Based on this analysis, the commenter states 
there were only 55 days over this period where the facility operated 
two units, which shows how unlikely EPA's assumed scenario is in 
reality.
    Response to Comment 7: The commenter's analysis of operations at 
Labadie focuses on recent data from CAMD, which does not necessarily 
reflect how the Labadie plant will be operated in the future. For 
instance, Ameren Missouri's Integrated Resource Plan, filed in 2020 and 
updated in 2021 and 2022, states that two of the four units currently 
operating at Labadie are anticipated to be retired by the end of

[[Page 296]]

2036.\9\ It is plausible that with only two remaining coal units in 
operation at Labadie, situations where only a single unit is operating 
on a given day may occur more frequently in the future. Without an air 
quality analysis showing that the 1-hour SO2 NAAQS would be 
protected in all areas in this and potentially other operating 
scenarios as discussed above, we cannot approve removal of the 4.8 lb/
MMBtu limit from the SIP.
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    \9\ See https://www.ameren.com/missouri/company/environment-and-sustainability/integrated-resource-plan.
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    Comment 8: The commenter provided an analysis of the highest daily 
average SO2 emission rate in lb/MMBtu for each of the 
Labadie boilers during the past five years. Based on this analysis, the 
commenter concluded that the highest daily average SO2 
emission rate of any of the four boilers during the past five years is 
0.78 lb/MMBtu, which is 16 percent of the 4.8 lb/MMBtu limit. The 
commenter contends that this shows the 4.8 lb/MMBtu limit is not a 
controlling limit, as there is not a single day in the past five years 
where the facility did not operate with at least an 80 percent 
compliance margin with this limit.
    Response to Comment 8: We agree that Labadie's boilers have 
operated at actual SO2 lb/MMBtu rates well below the 4.8 lb/
MMBtu limit in recent years based on CAMD data. However, there is no 
permanent and enforceable limit or requirement in place to prevent a 
switch to a higher sulfur coal at Labadie, which potentially allows 
individual units to emit an SO2 rate as high as 4.8 lb/MMBtu 
or more.
    Comment 9: The commenter noted that because 10 CSR 10-6.261 is a 
state enforceable rule, while 10 CSR 10-6.260 remains federally 
enforceable until it is removed from the SIP, operating permits issued 
by the state must include conditions from both of these regulations for 
facilities meeting the applicability criteria. For this reason, 
according to the commenter, the state's air permitting staff must spend 
time explaining why both rules must be evaluated for permitting 
purposes, a common question that arises with nearly every permit 
application. The commenter concludes that this disapproval action 
extends the time required for issuing operating permits and takes away 
time that permit authors could be spending on priority initiatives such 
as eliminating the permit backlog.
    Response to Comment 9: As discussed in greater detail above, the 
EPA is disapproving Missouri's SIP submission because the state has not 
demonstrated that the removal of SO2 emission limits for the 
Hawthorn and Labadie power plants from the SIP would not interfere with 
NAAQS attainment, RFP, or any other applicable requirement of the CAA 
as required under CAA section 110(l). This comment is beyond the scope 
of this disapproval action.

V. What action is the EPA taking?

    The EPA is disapproving a SIP submission from Missouri that would 
rescind 10 CSR 10-6.260 ``Restriction of Emission of Sulfur Compounds'' 
and replace it with 10 CSR 10-6.261 ``Control of Sulfur Dioxide 
Emissions.'' By disapproving these revisions, 10 CSR 10-6.260 will be 
retained in the SIP, along with the already SIP-approved Consent 
Agreement. The EPA has determined that Missouri's proposed SIP 
revisions do not meet the requirements of the Clean Air Act because the 
revisions would remove permanent and enforceable emission limits, 
thereby relaxing the stringency of the SIP. Furthermore, Missouri has 
not shown that the proposed SIP revision related to removal of the 
Labadie 4.8 lb/MMBtu limit would not have an adverse impact on air 
quality.
    Under section 179(a) of the CAA, final disapproval of a submittal 
that addresses a requirement of part D, title I of the CAA (CAA 
sections 171-193) or is required in response to a finding of 
substantial inadequacy as described in CAA section 110(k)(5) (SIP Call) 
starts a sanctions clock. The Missouri SIP submission being disapproved 
was not submitted to meet either of these requirements. Therefore, this 
disapproval will not trigger mandatory sanctions under CAA section 179. 
In addition, CAA section 110(c)(1) provides that EPA must promulgate a 
Federal Implementation Plan (FIP) within two years after either finding 
that a State has failed to make a required submission or disapproving a 
SIP submission in whole or in part, unless EPA approves a SIP revision 
correcting the deficiencies within that two-year period. With respect 
to the disapproval of Missouri's SIP submission, in our proposed action 
we concluded that any FIP obligation resulting from this disapproval 
would be satisfied by finalization of our proposed determination that 
there is no deficiency in the SIP to correct.\10\ We are not taking 
final action on making that determination, however. Specifically, 
although the previously approved SO2 emission limits 
discussed in this rulemaking will remain in the SIP and remain 
federally enforceable, as discussed above we have discovered that 
monitoring, recordkeeping and reporting requirements associated with 
the SO2 limit for Hawthorn were not previously approved into 
the SIP. This omission precludes our finalizing the proposed 
determination that there is no deficiency in the SIP to correct, and 
consequently does not eliminate the EPA's duty to promulgate a FIP 
within two years after disapproving the current SIP submission unless 
the EPA approves a SIP revision correcting the deficiencies within that 
two-year period. If the EPA were to take such an action, it would be 
done through a separate rulemaking process, including a notice of 
proposed rulemaking with the opportunity for the public to review and 
comment.
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    \10\ The EPA's obligation under CAA section 110(c)(1) to issue a 
FIP following a SIP disapproval is not limited to ``required'' plan 
submissions. However, the EPA can avoid promulgating a FIP if the 
Agency finds that there is no ``deficiency'' in the SIP for a FIP to 
correct. Association of Irritated Residents vs. United States 
Environmental Protection Agency, 632 F.3d 584 (9th Cir. 2011).
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VI. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review and Executive 
Order 13563: Improving Regulation and Regulatory Review

    This action is not a significant regulatory action and was 
therefore not submitted to the Office of Management and Budget for 
review.

B. Paperwork Reduction Act (PRA)

    This action does not impose an information collection burden under 
the PRA because it does not contain any information collection 
activities.

C. Regulatory Flexibility Act (RFA)

    I certify that this action will not have a significant economic 
impact on a substantial number of small entities under the RFA. This 
action merely disapproves a SIP submission as not meeting the CAA.

D. Unfunded Mandates Reform Act (UMRA)

    This action does not contain any unfunded mandate as described in 
UMRA, 2 U.S.C. 1531-1538, and does not significantly or uniquely affect 
small governments. The action imposes no enforceable duty on any state, 
local or tribal governments or the private sector.

E. Executive Order 13132: Federalism

    This action does not have federalism implications. It will not have 
substantial direct effects on the states, on the relationship between 
the national government and the states, or on the distribution of power 
and

[[Page 297]]

responsibilities among the various levels of government.

F. Executive Order 13175: Consultation and Coordination With Indian 
Tribal Governments

    This action does not have tribal implications as specified in 
Executive Order 13175. This action does not apply on any Indian 
reservation land, any other area where the EPA or an Indian tribe has 
demonstrated that a tribe has jurisdiction, or non-reservation areas of 
Indian country. Thus, Executive Order 13175 does not apply to this 
action.

G. Executive Order 13045: Protection of Children From Environmental 
Health Risks and Safety Risks

    The EPA interprets Executive Order 13045 as applying only to those 
regulatory actions that concern environmental health or safety risks 
that the EPA has reason to believe may disproportionately affect 
children, per the definition of ``covered regulatory action'' in 
section 2-202 of the Executive Order. This action is not subject to 
Executive Order 13045 because it merely disapproves a SIP submission as 
not meeting the CAA.

H. Executive Order 13211, Actions That Significantly Affect Energy 
Supply, Distribution or Use

    This action is not subject to Executive Order 13211, because it is 
not a significant regulatory action under Executive Order 12866.

I. National Technology Transfer and Advancement Act

    This rulemaking does not involve technical standards.

J. Executive Order 12898: Federal Actions To Address Environmental 
Justice in Minority Populations and Low-Income Populations

    The EPA believes the human health or environmental risk addressed 
by this action will not have potential disproportionately high and 
adverse human health or environmental effects on minority, low-income 
or indigenous populations. This action merely disapproves a SIP 
submission as not meeting the CAA.

K. Congressional Review Act

    This action is subject to the Congressional Review Act, and the EPA 
will submit a rule report to each House of the Congress and to the 
Comptroller General of the United States. This action is not a ``major 
rule'' as defined by 5 U.S.C. 804(2).

L. CAA Section 307(b)(1)

    Under section 307(b)(1) of the CAA, petitions for judicial review 
of this action must be filed in the United States Court of Appeals for 
the appropriate circuit by March 6, 2023. Filing a petition for 
reconsideration by the Administrator of this final rule does not affect 
the finality of this action for the purposes of judicial review nor 
does it extend the time within which a petition for judicial review may 
be filed, and shall not postpone the effectiveness of such rule or 
action. This action may not be challenged later in proceedings to 
enforce its requirements (see section 307(b)(2)).

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: December 20, 2022.
Meghan A. McCollister,
Regional Administrator, Region 7.
[FR Doc. 2022-28139 Filed 1-3-23; 8:45 am]
BILLING CODE 6560-50-P