Proposed Rule2025-15983
Air Plan Approval; IA, Muscatine; 2010 1-Hour SO2 Maintenance Plan and Redesignation
Primary source
Metadata and text below are from the Federal Register, a public-domain U.S. government work. Always verify the official published version before relying on it for any legal matter.
Published
August 21, 2025
Issuing agencies
Environmental Protection Agency
Abstract
The Environmental Protection Agency (EPA) is proposing to redesignate the nonattainment area in Muscatine County, Iowa to attainment for the 2010 1-hour sulfur dioxide (SO<INF>2</INF>) National Ambient Air Quality Standard (NAAQS). The EPA is also proposing to approve Iowa's maintenance plan for the 2010 1-hour SO<INF>2</INF> NAAQS for the Muscatine nonattainment area and approve modifications to source-specific permits in the Iowa State Implementation Plan (SIP). The EPA's proposed approval of this rule revision is being done in accordance with the requirements of the Clean Air Act (CAA).
Full Text
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<title>Federal Register, Volume 90 Issue 160 (Thursday, August 21, 2025)</title>
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[Federal Register Volume 90, Number 160 (Thursday, August 21, 2025)]
[Proposed Rules]
[Pages 40797-40812]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2025-15983]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Parts 52 and 81
[EPA-R07-OAR-2025-0818; FRL-12901-01-R7]
Air Plan Approval; IA, Muscatine; 2010 1-Hour SO2 Maintenance
Plan and Redesignation
AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed rule.
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SUMMARY: The Environmental Protection Agency (EPA) is proposing to
redesignate the nonattainment area in Muscatine County, Iowa to
attainment for the 2010 1-hour sulfur dioxide (SO<INF>2</INF>) National
Ambient Air Quality Standard (NAAQS). The EPA is also proposing to
approve Iowa's maintenance plan for the 2010 1-hour SO<INF>2</INF>
NAAQS for the Muscatine nonattainment area and approve modifications to
source-specific permits in the Iowa State Implementation Plan (SIP).
The EPA's proposed approval of this rule revision is being done in
accordance with the requirements of the Clean Air Act (CAA).
[[Page 40798]]
DATES: Comments must be received on or before September 22, 2025.
ADDRESSES: You may send comments, identified by Docket ID No. EPA-R07-
OAR-2025-0818 to <a href="https://www.regulations.gov">https://www.regulations.gov</a>. Follow the online
instructions for submitting comments.
Instructions: All submissions received must include the Docket ID
No. for this rulemaking. Comments received will be posted without
change to <a href="https://www.regulations.gov">https://www.regulations.gov</a>, including any personal
information provided. For detailed instructions on sending comments and
additional information on the rulemaking process, see the ``Written
Comments'' heading of the SUPPLEMENTARY INFORMATION section of this
document.
FOR FURTHER INFORMATION CONTACT: Bethany Olson, Environmental
Protection Agency, Region 7 Office, Air Quality Planning Branch, 11201
Renner Boulevard, Lenexa, Kansas 66219; telephone number: (913) 551-
7905; email address: <a href="/cdn-cgi/l/email-protection#5c33302f3332723e3928343d32251c392c3d723b332a"><span class="__cf_email__" data-cfemail="c8a7a4bba7a6e6aaadbca0a9a6b188adb8a9e6afa7be">[email protected]</span></a>.
SUPPLEMENTARY INFORMATION: Throughout this document ``we,'' ``us,'' and
``our'' refer to the EPA.
Table of Contents
I. Written Comments
II. What is being addressed in this document?
III. Have the requirements for approval of a SIP revision been met?
IV. What is the background for the EPA's proposed actions?
V. What is the EPA's analysis of the redesignation request and
maintenance plan?
VI. What is the EPA's analysis of the SIP-approved permit
modifications?
VII. What action is the EPA proposing to take?
VIII. Incorporation by Reference
IX. Statutory and Executive Order Reviews
I. Written Comments
Submit your comments, identified by Docket ID No. EPA-R07-OAR-2025-
0818, at <a href="https://www.regulations.gov">https://www.regulations.gov</a>. Once submitted, comments cannot
be edited or removed from <a href="http://Regulations.gov">Regulations.gov</a>. The EPA may publish any
comment received to its public docket. Do not submit electronically any
information you consider to be Confidential Business Information (CBI)
or other information whose disclosure is restricted by statute.
Multimedia submissions (audio, video, etc.) must be accompanied by a
written comment. The written comment is considered the official comment
and should include discussion of all points you wish to make. The EPA
will generally not consider comments or comment contents located
outside of the primary submission (i.e., on the web, cloud, or other
file sharing system). For additional submission methods, the full EPA
public comment policy, information about CBI or multimedia submissions,
and general guidance on making effective comments, please visit <a href="https://www.epa.gov/dockets/commenting-epa-dockets">https://www.epa.gov/dockets/commenting-epa-dockets</a>.
II. What is being addressed in this document?
The EPA is proposing to approve a SIP revision and redesignation
request submitted on November 17, 2021, by the Iowa Department of
Natural Resources (IDNR). The EPA is proposing to take the following
three separate but related actions: (1) to add new or revised permits
for Muscatine area sources into the Iowa SIP and remove certain air
construction permits from the SIP; (2) to approve Iowa's maintenance
plan for the 2010 1-hour SO<INF>2</INF> NAAQS in the Muscatine area and
incorporate it into the SIP; and (3) to redesignate the Muscatine area
to attainment for the 2010 1-hour SO<INF>2</INF> NAAQS.
The EPA proposes to find that the State's submittal meets the
requirements for redesignation under the CAA and the revisions do not
interfere with any applicable requirement concerning attainment and
reasonable further progress. The full State submission is included in
the docket for this action.
III. Have the requirements for approval of a SIP revision been met?
The State submission has met the public notice requirements for SIP
submissions in accordance with 40 CFR 51.102. The submission also
satisfied the completeness criteria of 40 CFR part 51, appendix V. The
State provided public notice on this SIP submission from August 20,
2021, to September 20, 2021, and held a public hearing on September 20,
2021. IDNR received and responded to written comments from two sources,
and included the comments and responses in its submission. In addition,
as explained above and in more detail in the technical support document
(TSD) which is part of this document, the revision meets the
substantive SIP requirements of the CAA, including section 110 and
implementing regulations.
IV. What is the background for the EPA's proposed actions?
A. Nonattainment Designation
On June 2, 2010 (75 FR 35520), the EPA signed the revised the
primary SO<INF>2</INF> NAAQS, establishing a new 1-hour standard of 75
parts per billion (ppb). Under the EPA's regulations at 40 CFR part 50,
the 2010 1-hour SO<INF>2</INF> NAAQS is met at a monitoring site when
the 3-year average of the annual 99th percentile of daily maximum 1-
hour average concentrations is less than or equal to 75 ppb (based on
the rounding convention in 40 CFR part 50, appendix T).\1\ Ambient air
quality monitoring data for the 3-year period must meet a data
completeness requirement. A year meets data completeness requirements
when all four quarters are complete, and a quarter is complete when at
least 75 percent of the sampling days for each quarter have complete
data. A sampling day has complete data if 75 percent of the hourly
concentration values, including State-flagged data affected by
exceptional events which have been approved for exclusion by the
Administrator, are reported.\2\
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\1\ See 40 CFR 50.17.
\2\ 40 CFR part 50, appendix T, section 3(b).
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Following promulgation of a new or revised NAAQS, the EPA is
required by CAA section 107(d) to designate areas throughout the nation
as attaining or not attaining the NAAQS, or as unclassifiable. On
August 5, 2013, the EPA designated a portion of Muscatine County, Iowa,
as nonattainment for the 2010 primary 1-hour SO<INF>2</INF> NAAQS (78
FR 47191), effective October 4, 2013. The designation was based on air
quality monitoring data from 2009-2011 showing violations of the NAAQS.
Pursuant to CAA sections 172(a)(2) and 192(a), this action established
an attainment date five years after the effective date of the final
action designating the area as nonattainment for the 2010
SO<INF>2</INF> NAAQS (i.e., by October 4, 2018).
B. Relevant Historical SIP Actions
The EPA's 2013 SO<INF>2</INF> nonattainment designation triggered
an obligation for Iowa to submit a SIP for the Muscatine SO<INF>2</INF>
nonattainment area (NAA) addressing the requirements of CAA sections
110, 172(c) and 191-192 within 18 months following the October 4, 2013,
effective date of designation (i.e., by April 4, 2015). The EPA did not
receive an attainment SIP revision for the Muscatine NAA by the April
6, 2015 deadline and subsequently on March 18, 2016, the EPA published
a finding of failure to submit indicating that Iowa did not submit the
required SO<INF>2</INF> attainment plan (81 FR 14736).
Iowa submitted the required attainment plan submittal on May 26,
2016. The EPA proposed approval of Iowa's attainment plan on August 24,
2017 (82 FR 40086). The EPA published a supplemental notice of proposed
rulemaking (SNPRM) on January 9, 2018, and included additional
[[Page 40799]]
information in the docket in response to public comments suggesting
that insufficient information was provided in the docket to allow the
reviewer to fully evaluate the attainment plan and the EPA's proposed
approval (83 FR 997). The EPA published a second SNPRM on June 22,
2020, to provide additional detail regarding the technical support and
policy rationale for approving the attainment demonstration and control
strategy, as well as the underlying state permits as the enforceable
mechanism of the control strategy (85 FR 37405). The EPA issued a final
approval of Iowa's attainment plan on November 17, 2020 (85 FR 73218).
Iowa's approved 2016 attainment plan provided a modeled attainment
demonstration and satisfied the required nonattainment planning
requirements mentioned above for the Muscatine NAA. In accordance with
CAA title I, part D, subpart 1, the revision included a 2011 base-year
and projection-year emissions inventories, a control strategy and air
quality modeling demonstration, a reasonable available control
measures/reasonably available control technology (RACM/RACT) analysis,
a reasonable further progress (RFP) analysis, and contingency measures.
The plan also included nonattainment new source review (NNSR)
regulations previously approved by the EPA.\3\
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\3\ 79 FR 27763, May 15, 2014.
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As discussed in sections V. and VI., below, the attainment plan
included permit conditions to reduce SO<INF>2</INF> emissions at three
facilities in the NAA: Grain Processing Corporation (GPC), Muscatine
Power and Water (MPW), and Monsanto Company-Muscatine (Monsanto), now
Bayer CropScience LP.\4\ The conditions are contained in air
construction permits issued by IDNR and were approved into the SIP as
part of the attainment plan approval.\5\ The air construction permits
include specified RACT SO<INF>2</INF> emission limits, compliance
monitoring, and recordkeeping and reporting requirements at GPC, MPW,
and Monsanto. The RACT limits establish the maximum permitted allowable
emission rate for each emission point, and Iowa based its modeled
attainment demonstration on these conditions.
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\4\ The Monsanto facility in Muscatine is now under the
ownership of Bayer CropScience LP. This document retains use of the
Monsanto name for consistency with the Iowa submittal. Bayer
CropScience L.P. assumed all construction permits for Monsanto that
are relevant to this action.
\5\ 85 FR 73218, November 17, 2020.
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As a part of the EPA's approval of IDNR's attainment plan, air
construction permits for the three NAA sources were incorporated into
the Iowa SIP, including 52 GPC permits, four MPW permits, and two
Monsanto permits. The control strategy for each source is described
below.
GPC, a corn wet milling facility, was the largest source of
SO<INF>2</INF> within the NAA. At the time of the nonattainment
designation, GPC had six coal-fired boilers that generated a majority
of its SO<INF>2</INF> emissions, along with a sizeable list of diverse
sources identified in the 2016 attainment plan. GPC converted its coal-
fired boilers to only natural gas combustion in 2015 to comply with a
separate consent order with the State of Iowa. IDNR issued a final air
construction permit with a SO<INF>2</INF> limit that restricts these
boilers to firing on natural gas only. IDNR also issued air
construction permits to GPC that included process changes and the
installation of six new scrubbers to further reduce SO<INF>2</INF>
emissions.
MPW is a municipal electric generating station with three coal-
fired boilers (Units 7, 8, and 9) and an auxiliary boiler that is not
capable of burning coal but has the potential to emit SO<INF>2</INF>
when firing on distillate fuel oil. IDNR issued air construction
permits to MPW requiring a more stringent SO<INF>2</INF> emission limit
for Units 7, 8, and 9, and a more stringent SO<INF>2</INF> emission
limit for the auxiliary boiler when it is firing fuel oil.
Monsanto is a manufacturer and formulator of herbicides for
agricultural use and had one coal-fired boiler (Boiler #8). Iowa issued
final air construction permits to Monsanto that required a more
stringent SO<INF>2</INF> emission limit for Boiler #8, a new
SO<INF>2</INF> emission limit for the CAC Process Flare Burner,\6\ and
a new provision restricting its fuel use to natural gas only.
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\6\ This emission unit is part of the process that produces
chloro acetyl chloride (CAC), which is an herbicide intermediate
product.
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On November 17, 2021, Iowa submitted a revision to its SIP that
includes modifications to SIP-approved permits, includes a maintenance
plan for the 2010 1-hour primary SO<INF>2</INF> NAAQS, and requests
concurrent redesignation of the Muscatine NAA to attainment for the
2010 1-hour primary SO<INF>2</INF> NAAQS. The submitted permit
revisions replace some specific conditions that the EPA had previously
approved into the SIP for the purpose of demonstrating attainment of
the SO<INF>2</INF> standard pursuant to the nonattainment requirements
of sections 172, 191, and 192 of the CAA. This request is discussed in
more detail in section VI., below.
On January 26, 2022, the EPA proposed to determine that the
Muscatine NAA attained the 2010 1-hour SO<INF>2</INF> NAAQS by the
applicable attainment date of October 4, 2018 (87 FR 3958). The EPA
issued a final determination of attainment by the attainment date for
the 2010 1-hour SO<INF>2</INF> NAAQS on April 7, 2022 (87 FR 20329).
C. Redesignation to Attainment Criteria
The CAA outlines the requirements for redesignation of a
nonattainment area to attainment. Specifically, CAA section
107(d)(3)(E) allows for redesignation provided that the following
criteria have been met: (1) the EPA has determined that the applicable
NAAQS has been attained; (2) the applicable SIP has been fully approved
by the EPA under CAA section 110(k); (3) the EPA has determined that
the improvement in the area's air quality is due to permanent and
enforceable reductions in emissions; (4) the area has a fully approved
maintenance plan, including a contingency plan, under CAA section 175A;
and (5) the State has met all applicable requirements for the area
under CAA section 110 and part D. The EPA has provided direction for
how it would consider if these conditions have been met with respect to
the 2010 1-hour SO<INF>2</INF> NAAQS in the April 23, 2014 memorandum
``Guidance for 1-Hour SO<INF>2</INF> Nonattainment Area SIP
Submissions'' (2014 SO<INF>2</INF> Guidance).\7\
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\7\ Available in the docket for this action as 2014
SO<INF>2</INF> Guidance and at <a href="https://www.epa.gov/sites/default/files/2016-06/documents/20140423guidance_nonattainment_sip.pdf">https://www.epa.gov/sites/default/files/2016-06/documents/20140423guidance_nonattainment_sip.pdf</a>.
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D. Maintenance Plan Approval Criteria
CAA section 175A and additional EPA guidance, including the
September 4, 1992 memorandum ``Procedures for Processing Requests to
Redesignate Areas to Attainment'' (Calcagni Memo),\8\ identify the
required elements for an approvable maintenance plan for areas seeking
redesignation from nonattainment to attainment. Under CAA section 175A,
the plan must demonstrate continued attainment of the applicable NAAQS
for at least 10 years after the EPA approves a redesignation to
attainment. Eight years after the redesignation, the State must submit
a revised maintenance plan demonstrating that attainment will continue
to be maintained for an additional 10 years following the initial 10-
year period. To address the possibility of future NAAQS violations,
[[Page 40800]]
the maintenance plan must contain contingency measures, as the EPA
deems necessary, to assure prompt correction of any future violations
of the 2010 1-hour SO<INF>2</INF> NAAQS. The Calcagni Memo provides
further guidance on the content of a maintenance plan, explaining that
a maintenance plan should address five requirements: (1) an attainment
emissions inventory that identifies the level of emissions in the area
which is sufficient to attain the NAAQS; (2) a maintenance
demonstration that shows future emissions of a pollutant will not
exceed the level of the attainment inventory; (3) the continued
operation of a monitoring network that conforms to 40 CFR part 58; (4)
a means for verifying the continued attainment of the NAAQS; and (5) a
contingency plan to correct any violation of the NAAQS in the area
following redesignation of the area.
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\8\ Available in the docket for this action as Calcagni Memo and
at <a href="https://www.epa.gov/sites/default/files/2016-03/documents/calcagni_memo_-_procedures_for_processing_requests_to_redesignate_areas_to_attainment_090492.pdf">https://www.epa.gov/sites/default/files/2016-03/documents/calcagni_memo_-_procedures_for_processing_requests_to_redesignate_areas_to_attainment_090492.pdf</a>.
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V. What is the EPA's analysis of the redesignation request and
maintenance plan?
The EPA's evaluation of Iowa's redesignation request and
maintenance plan is based on consideration of the five redesignation
criteria provided under CAA section 107(d)(3)(E) and relevant guidance,
including the aforementioned 2014 SO<INF>2</INF> Guidance and Calcagni
Memo.
A. Criterion (1)--The Muscatine SO2 Nonattainment Area Has Attained the
2010 1-Hour SO2 NAAQS
CAA section 107(d)(3)(E)(i) requires that the EPA determine if a
nonattainment area has attained the applicable NAAQS in order to
redesignate the area to attainment. The 2014 SO<INF>2</INF> Guidance
stipulates that the EPA can interdependently consider two components to
support an attainment determination: air quality monitoring data and
air quality modeling data.\9\
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\9\ See 2014 SO<INF>2</INF> Guidance, at 62.
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The EPA made a determination of attainment by the attainment date
for the Muscatine NAA for the 2010 1-hour SO<INF>2</INF> NAAQS in its
April 7, 2022 NFRM (87 FR 20329). In that action, the EPA relied upon
SO<INF>2</INF> emissions data and trends, relevant air monitoring data
and trends, SO<INF>2</INF> monitoring data incorporated with local
meteorological data, as well as available modeling information in order
to make the determination of attainment under CAA section 179(c).
The EPA also reviewed quality assured monitoring data recorded in
the EPA's Air Quality System (AQS) in support of this action.
Monitoring data are evaluated in accordance with 40 CFR 50.17 using
data analysis procedures specified in 40 CFR part 50, appendix T. If
the 3-year design value in the area violates the NAAQS prior to the EPA
acting in response to the State's request, the EPA will not take final
action to approve the redesignation request.\10\ During the 2013-2024
data period, Iowa operated three SO<INF>2</INF> monitoring stations in
the Muscatine SO<INF>2</INF> NAA: Greenwood Cemetery (AQS ID 19-139-
0016); High School East Campus (AQS ID 19-139-0019); and Musser Park
(AQS ID 19-139-0020). All three monitoring sites are located within the
city limits of Muscatine in the nonattainment area. The 2022-2024 3-
year design value for the Muscatine NAA is 17 ppb and continues to meet
the 2010 1-hour SO<INF>2</INF> NAAQS of 75 ppb, as shown in table 1.
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\10\ See 2014 SO<INF>2</INF> Guidance, at 56.
Table 1--Muscatine Nonattainment Area SO2 Monitored Design Values
[ppb]
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Site 2011-2013 2012-2014 2013-2015 2014-2016 2015-2017 2016-2018 2017-2019 2018-2020 2019-2021 2020-2022 2021-2023 2022-2024
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Greenwood Cemetary.......................................... ......... 101 97 77 45 20 17 15 14 13 ......... .........
High School East Campus..................................... ......... ......... 128 84 42 22 21 18 18 14 13 13
Musser Park................................................. 217 194 158 113 65 34 25 20 21 25 21 17
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As shown in table 1, the design values in the Muscatine NAA have
significantly decreased since 2013. The 3-year design value for the
Muscatine NAA decreased by 90% from 2013 to present. The 2011-2013
design value for the area (composed of the 3-year average of the annual
99th percentile of 1-hour daily maximum SO<INF>2</INF> concentrations)
was 217 ppb, while the most recent design value was 17 ppb for 2022-
2024.
Iowa removed the Greenwood Cemetary Special Purpose Monitor (SPM)
in 2023. The Greenwood Cemetary monitor only had two complete quarters
in 2023 and, therefore, does not have a valid design value after 2022.
Changes to the SPM network do not require concurrence from the EPA.\11\
Iowa continues to operate the High School East Campus SPM and the
Musser Park State and Local Air Monitoring Stations (SLAMS) monitors.
As discussed in more detail later in this section, Iowa has committed
to continue monitoring in this area in accordance with 40 CFR part 58.
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\11\ See 40 CFR 58.20(f).
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According to the 1992 Calcagni Memo, for pollutants such as
SO<INF>2</INF> a small number of monitors is not typically
representative of area-wide air quality or areas of highest
concentration, and dispersion modeling is generally necessary to
evaluate comprehensively sources' impacts.\12\ Similarly, the 2014
SO<INF>2</INF> Guidance states that if there are air quality monitors
located in the area, but analyses show that none of the monitors are
located in the area of maximum concentration, then air quality
dispersion modeling should be conducted to estimate SO<INF>2</INF>
concentrations in the area.\13\ The EPA does not have conclusive
evidence to support that the Muscatine area monitors are sited in the
area of maximum ambient SO<INF>2</INF> concentrations. In the 2021 SIP
submission, Iowa states it is relying on the modeled attainment
demonstration included with the attainment plan to support the
determination of attainment. If the air agency has previously submitted
a modeled attainment demonstration using allowable emissions, no
further modeling is typically needed as long as the source
characteristics are still reasonably represented and the submission
includes a demonstration that the control strategy in the SIP has been
fully implemented.\14\ Because Iowa is requesting modifications to
source permits relied upon for the modeled attainment demonstration as
discussed in section VI, the State provided updated dispersion modeling
in its 2021 SIP submission. As described in the maintenance
demonstration section below, the 2021 SIP submission included updated
modeling for the maximum permitted allowable emissions in the Muscatine
area over a
[[Page 40801]]
5-year meteorological period. The EPA reviewed the updated
demonstration and finds it shows continued attainment of the 1-hour
SO<INF>2</INF> NAAQS. Section 3.3 of Iowa's 2021 SIP submission
includes a compliance analysis demonstrating that the 2016 attainment
plan has been fully implemented and that GPC, MWP, and Monsanto are in
compliance with the limits and conditions in the SIP.
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\12\ See Calcagni Memo, at 3.
\13\ See 2014 SO<INF>2</INF> Guidance, at 62-63.
\14\ Id.
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Therefore, the EPA's 2022 determination that the area had attained
the standard by the attainment date, along with the most recent air
quality monitoring data and the 2021 updated air quality modeling, are
consistent with this proposed action to redesignate the area. The EPA
proposes to find that Iowa has demonstrated that the requirements of
CAA section 107(d)(3)(E)(i) have been met. Additional details on the
EPA's review of the submitted air quality modeling and SO<INF>2</INF>
monitoring trends are contained in the EPA's TSD in the docket for this
action.
B. Criterion (2)--Iowa Has a Fully Approved SIP Under Section 110(k)
CAA section 107(d)(3)(E)(ii) requires that the EPA fully approve
the applicable implementation plan for the area under CAA section
110(k) in order to redesignate that area to attainment. The EPA has
fully approved the applicable Iowa SIP for the Muscatine NAA under
section 110(k) of the CAA for all requirements applicable for purposes
of redesignation. An area cannot be redesignated to attainment if a
required element of the SIP is the subject of a disapproval; a finding
of failure to submit, or failure to implement the SIP; or a partial,
conditional, or limited approval.\15\ As described above, the 2016
attainment plan received final EPA approval on November 17, 2020.\16\
The approved elements from the 2016 attainment plan include 2011 base-
year and projection-year emissions inventories, a control strategy and
air quality modeling demonstration, a reasonable available control
measures/reasonably available control technology (RACM/RACT) analysis,
a reasonable further progress (RFP) analysis, and contingency measures.
The plan also included nonattainment new source review (NNSR)
regulations previously approved by the EPA.\17\ The EPA proposes to
find that Iowa has demonstrated that the requirements of CAA section
107(d)(3)(E)(ii) have been met.
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\15\ See 2014 SO<INF>2</INF> Guidance, at 64.
\16\ 85 FR 73218, November 17, 2020.
\17\ 79 FR 27763, May 15, 2014.
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C. Criterion (3)--The Air Quality Improvement in the Muscatine SO2
Nonattainment Area Is Due to Permanent and Enforceable Reductions in
Emissions
For redesignating a nonattainment area to attainment, CAA section
107(d)(3)(E)(iii) requires the EPA to determine that the air quality
improvement in the area is due to permanent and enforceable reductions
in emissions resulting from implementation of the SIP, applicable
federal air pollution control regulations, and other permanent and
enforceable reductions.
The implementation of multiple permanent and federally enforceable
control measures at stationary point sources of SO<INF>2</INF>
identified in the EPA-approved 2016 attainment plan resulted in a
substantial decrease in SO<INF>2</INF> emissions, and consequently
lower ambient SO<INF>2</INF> concentrations in the Muscatine NAA. The
attainment SIP control strategy identified three significant sources of
SO<INF>2</INF> emissions within the nonattainment area: GPC, MPW, and
Monsanto. The control measures and RACT SO<INF>2</INF> emission limits
on these sources were implemented through air construction permits
issued by IDNR and approved into the SIP as part of the attainment plan
approval. Iowa's request includes revisions to specific SIP-approved
air permits relied upon for the attainment demonstration, and the EPA
is proposing to add new or revised permits for Muscatine area sources
into the Iowa SIP and remove certain air construction permits from the
SIP as a part of this action. The permit revisions are discussed in
more detail in section VI.
The air construction permits include specified control measures at
each source. GPC converted its coal-fired boilers to only natural gas
combustion in 2015 to comply with a separate consent order with the
State of Iowa. The permit includes an SO<INF>2</INF> limit that
restricts these boilers to firing on natural gas only. Additionally,
GPC implemented process changes to reduce SO<INF>2</INF> emissions from
steeping tanks and downstream processes, and installed six new
scrubbers. For MPW, the control strategy relied on a more stringent
SO<INF>2</INF> emission limit that works in conjunction with a
compliance formula across its three coal-fired boilers (Units 7, 8, and
9), and a more stringent SO<INF>2</INF> emission limit on the auxiliary
boiler when it is firing fuel oil. Monsanto converted Boiler #8 from
combusting primarily coal to natural gas only and the modified
construction permit contains a lower SO<INF>2</INF> RACT limit. Other
control measures at Monsanto include an SO<INF>2</INF> emission limit
for the CAC Process Flare Burner and a provision restricting its fuel
use to natural gas only. The permitted emission limits contained in the
air construction permits issued by IDNR are federally enforceable and
permanent because the permits are either approved into Iowa's SIP or
will be approved into the SIP if finalized as proposed in this action.
Permits approved into the State SIP cannot be altered without a formal
SIP revision.
Collectively, the implemented controls and lower permitted
SO<INF>2</INF> emissions rates at GPC, MPW, and Monsanto resulted in a
98% reduction of actual SO<INF>2</INF> annual emissions from 15,399
tons in 2013 to 236 tons in 2023.\18\ As this reduction comes from EPA-
approved SIP controls and permitted emission limits, the EPA finds the
air quality improvement in the Muscatine NAA to be due to permanent and
enforceable reductions in emissions. Additional details on area
emissions data for the Muscatine NAA are contained in the EPA's TSD for
this action. The EPA proposes to find that Iowa has demonstrated that
the requirements of CAA section 107(d)(3)(E)(iii) have been met.
---------------------------------------------------------------------------
\18\ See the EPA Region 7 TSD at pp. 7, available in the docket
for this action.
---------------------------------------------------------------------------
D. Criterion (4)--The Muscatine SO2 Nonattainment Area Has a Fully
Approved Maintenance Plan Pursuant to Section 175A of the CAA
To redesignate a NAA to attainment, CAA section 107(d)(3)(E)(iv)
requires the EPA to determine that the area has a fully approved
maintenance plan pursuant to CAA section 175A. The Calcagni Memo
provides further guidance on the content of a maintenance plan,
explaining that a maintenance plan should address five requirements:
the attainment emissions inventory, maintenance demonstration,
monitoring, verification of continued attainment, and a contingency
plan.\19\
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\19\ See Calcagni Memo, at pp. 8-12.
---------------------------------------------------------------------------
In conjunction with its request to redesignate the Muscatine NAA to
attainment for the 2010 1-hour primary SO<INF>2</INF> NAAQS, the State
submitted a SIP revision to provide for the maintenance of the 2010 1-
hour primary SO<INF>2</INF> NAAQS for at least 10 years after the
effective date of redesignation to attainment. The EPA's evaluation of
Iowa's maintenance plan is based on consideration of the elements
required under CAA section 175A and relevant guidance, including the
aforementioned 2014 SO<INF>2</INF> Guidance and Calcagni Memo.
[[Page 40802]]
1. Attainment Emissions Inventory
In a maintenance plan, states should develop an attainment
inventory to identify the level of emissions in the affected area which
is sufficient to attain and maintain the SO<INF>2</INF> NAAQS.\20\ This
inventory can be used as the basis for future, projected emission
inventories that are used to show the area will remain in attainment.
Iowa selected 2017 as the attainment year for developing the
SO<INF>2</INF> emissions inventory, which is within the attaining
design value period (i.e., 2015-2017). Iowa submitted an attainment
inventory based on maximum permitted allowable SO<INF>2</INF> emissions
for the four sources modeled in the maintenance plan: GPC, MPW,
Monsanto, and MidAmerican Energy's Louisa Generating Station (LGS).
Although LGS is located outside of the NAA, Iowa included it in its
model-based attainment and maintenance demonstrations to ensure that
the control strategy would be effective when including the
SO<INF>2</INF> emissions from this nearby source. The attainment
emissions inventory for modeled sources is provided in table 2.
---------------------------------------------------------------------------
\20\ See 2014 SO<INF>2</INF> Guidance, at 66.
Table 2--Attainment Emissions Inventory--Maximum Permitted Allowable Emissions for Modeled Sources
----------------------------------------------------------------------------------------------------------------
Maximum permitted
Location Facility name Facility ID allowable SO2 emissions
(tons per year)
----------------------------------------------------------------------------------------------------------------
Inside the NAA.......................... GPC........................ 70-01-004 175
MPW........................ 70-01-011 5,051
Monsanto................... 70-01-008 329
------------------------------------------
Total............................... ........................... .............. 5,555
----------------------------------------------------------------------------------------------------------------
Outside the NAA......................... LGS........................ 58-07-001 15,188
----------------------------------------------------------------------------------------------------------------
Iowa also provided actual SO<INF>2</INF> emissions for other point,
nonpoint, onroad, nonroad, and event (prescribed fire) sources from the
2017 National Emission Inventory (NEI). The NEI is a comprehensive,
triennial estimate of emissions. Iowa directly used other point source
and nonpoint emissions reported in the 2017 NEI, except for a
correction identified in section 7.1 of the submitted redesignation
request and maintenance plan. Iowa's plan states that the 2017 NEI
contains a known error in Iowa's nonpoint inventory that incorrectly
yields emissions from coal-fired industrial combustion sources, even
though all emissions from industrial coal combustion are accounted for
in the point source category. The erroneous nonpoint emissions were
excluded from Iowa's attainment emissions inventory. The emission
estimates provided for nonpoint, onroad, nonroad, or event sources
represent county-wide totals for all of Muscatine County, IA rather
than the partial Muscatine NAA. The attainment emissions inventory for
sources not explicitly modeled is provided in table 4 below.
The EPA proposes to find the attainment emissions inventory
provided in Iowa's maintenance plan to be acceptable. For additional
information regarding the development of the attainment emissions
inventory, please see section 7.1 of the 2021 State submittal in the
docket for this action.
2. Maintenance Demonstration
The Calcagni Memo describes two ways for a State to demonstrate
maintenance of the NAAQS for a period of at least 10 years 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 rates will not cause a violation of the standard.
The 2014 SO<INF>2</INF> Guidance says that where a state has submitted
an attainment plan that relies on air quality dispersion modeling using
maximum allowable emissions, the plan can generally be expected to
demonstrate that the standard will be maintained for the requisite 10
years and beyond without regard to any changes in operation rate of the
pertinent sources as long as those changes do not result in increases
in maximum allowable emissions.\21\ Iowa's demonstration meets both of
these criteria from the Calcagni Memo by providing modeling of updated
maximum allowable emissions and showing that emissions will not
increase in the future therefore demonstrating continued maintenance.
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\21\ See 2014 SO<INF>2</INF> Guidance, at 67.
---------------------------------------------------------------------------
Iowa provided updated dispersion modeling in its 2021 SIP
submission to demonstrate that the Muscatine NAA will continue to
attain and maintain the 2010 SO<INF>2</INF> NAAQS with the submitted
permit updates. The updated demonstration is based on the modeling
analysis used in the Muscatine attainment plan. Iowa modeled
SO<INF>2</INF> emissions from the three sources within the
nonattainment area: GPC, MPW, and Monsanto. Facilities outside the
nonattainment area that were also explicitly modeled include
MidAmerican Energy's Louisa Generating Station (LGS). While LGS is not
located within the nonattainment area, it is currently the largest
emitter of SO<INF>2</INF> in the Muscatine area and Iowa included it in
both the attainment demonstration and the updated demonstration to
ensure that the control strategy would be effective in the
nonattainment area with this nearby source. The updated demonstration
includes the following updates: permit updates (described above), newer
version of the American Meteorological Society (AMS)/EPA Regulatory
Model (AERMOD) modeling system, more recent 5-year meteorological
dataset, updated background concentration of 5 [mu]g/m\3\, updated
horizontal emissions point, receptors included along the levee near GPC
to reflect changes to public access, and updates to LGS's main boiler
stack temperature and flowrate. AERMOD is the preferred model for this
application, and Iowa's updated dispersion modeling used version 19191
which was the most current version of AERMOD available at the time of
the analysis.
The modeling demonstration is based on current maximum permitted
allowable SO<INF>2</INF> emissions at the four facilities. Iowa's
submission states the four facilities account for all the nearby
SO<INF>2</INF> sources not adequately characterized by the background
concentration. Iowa modeled seven scenarios to ensure that all
scenarios demonstrated continued attainment of the standard. The
scenarios vary depending upon which combination of
[[Page 40803]]
MPW's three coal-fired boilers are running.
The EPA reviewed the modeling analysis submitted by Iowa and finds
the revised control measures for GPC, MPW, and Monsanto continue to
provide for attainment of the 2010 SO<INF>2</INF> NAAQS. The EPA agrees
with the State's determination that its control strategy analysis
results in modeled concentrations throughout the nonattainment area
that are at or below 75 ppb or 196.4 [mu]g/m\3\, as shown in table 3.
The EPA's full review of the submitted modeling demonstration is
included in the TSD for this action. Iowa provided modeling files to
the EPA with its submission that are too large to post in the docket.
The state modeling files are available upon request from the contact
listed in the FOR FURTHER INFORMATION CONTACT section of this document.
Table 3--Cumulative Modeled SO2 Ambient Air Impacts Concentrations in
the Muscatine Area
[[mu]g/m\3\]
------------------------------------------------------------------------
Cumulative
MPW scenario model result
([mu]g/m\3\)
------------------------------------------------------------------------
All MPW Units........................................... 163.09
Unit 9 Off.............................................. 168.37
Unit 8 Off.............................................. 167.26
Unit 7 Off.............................................. 162.97
Unit 7 Only............................................. 166.92
Unit 8 Only............................................. 162.72
Unit 9 Only............................................. 177.53
------------------------------------------------------------------------
Any increase in maximum allowable SO<INF>2</INF> emissions for GPC,
MPW, and Monsanto would require a SIP revision to modify the air
construction permits incorporated into the SIP. Iowa stated that it
expects actual emissions from GPC, MPW, Monsanto, and LGS to remain
well below the permitted maximum allowable emission rates modeled in
the maintenance plan.\22\ The EPA's review of SO<INF>2</INF> emissions
trends contained in the TSD for this action support the conclusion that
SO<INF>2</INF> emissions in the Muscatine NAA are well below the
permitted maximum allowable rates used by Iowa in the submitted
modeling demonstration.
---------------------------------------------------------------------------
\22\ See Iowa's 2021 maintenance plan, section 7.2 Maintenance
Demonstration at 26.
---------------------------------------------------------------------------
Iowa also provided projected emissions inventories based on the
attainment inventory to further demonstrate that the area will continue
to remain in attainment during the maintenance period. Emissions
forecasts for the point-other, nonpoint, onroad, nonroad, and event
(prescribed fire) sectors were estimated by multiplying the 2017 NEI
data by population growth factors. Iowa developed growth factors for
2033 and two additional future years, 2035 and 2040, as shown in table
7-4 of the State submittal. The estimated growth factors are 1.0282 for
2033, 1.0297 for 2035, and 1.0309 for 2040. Iowa's emissions forecasts
for the point-other, nonpoint, onroad, nonroad, and event (prescribed
fire) sectors demonstrate nominal changes to annual SO<INF>2</INF>
emissions in the Muscatine NAA. Projected emissions forecasts for these
years, as well as the attainment year inventory, are available in table
4.
Table 4--Emissions Inventories for the Muscatine NAA
[Tons]
----------------------------------------------------------------------------------------------------------------
2017 NEI
Location Sector (attainment 2033 2035 2040
inventory) Forecast Forecast Forecast
----------------------------------------------------------------------------------------------------------------
Inside the NAA.................... Point-Other.......... 0.33 0.34 0.34 0.34
Muscatine County.................. Non-Point............ 6.96 7.16 7.17 7.18
On-Road.............. 3.17 3.25 3.26 3.26
Non-Road............. 0.51 0.53 0.53 0.53
Event (Prescribed 1.38 1.42 1.42 1.42
Fires).
------------------------------------------------------
Total......................... ..................... 12.36 12.71 12.72 12.74
------------------------------------------------------
Forecasted Growth from 2017... ..................... .............. 0.35 0.36 0.38
----------------------------------------------------------------------------------------------------------------
Iowa's emissions forecasts for the point-other, nonpoint, onroad,
nonroad, and event (prescribed fire) sectors demonstrate nominal
changes to annual SO<INF>2</INF> emissions in the Muscatine NAA. For
the year 2040, Iowa estimated that total SO<INF>2</INF> emissions from
those sectors would only grow by approximately 0.38 tons. This small
increase in annual emissions is not expected to impact ambient
SO<INF>2</INF> concentrations in the area, as further evidenced by
relatively large decreases in emissions from point sources in the area
described in the EPA's TSD for this action. The EPA proposes to find
the maintenance demonstration provided in Iowa's maintenance plan to be
acceptable.
3. Monitoring Network
The 2014 SO<INF>2</INF> Guidance indicates that once an area has
been redesignated to attainment, the state should continue to operate
an appropriate air quality monitoring network as provided under 40 CFR
part 58 to verify the attainment status of the area. IDNR has committed
to continued operation of its SO<INF>2</INF> monitoring network in the
Muscatine NAA to verify the attainment status and work with the EPA
through the air monitoring network review process, in accordance with
40 CFR 58.10. Iowa currently operates one SPM monitor and one SLAMS
monitor in the Muscatine NAA. SLAMS monitors cannot be discontinued
without concurrence from the EPA. The EPA proposes to find the
monitoring network information provided in Iowa's maintenance plan to
be acceptable.
4. Verification of Continued Attainment
The 2014 SO<INF>2</INF> Guidance states that each air agency should
ensure that it has the legal authority to implement and enforce all
measures necessary to attain and maintain the 2010 1-hour
SO<INF>2</INF> NAAQS. The air agency's submittal should indicate how it
will track the progress of the maintenance plan for the area either
through air quality monitoring or modeling.\23\
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\23\ See 2014 SO<INF>2</INF> Guidance, at 67-68.
---------------------------------------------------------------------------
IDNR has the legal authority to enforce and implement the
maintenance plan for the Muscatine 2010 SO<INF>2</INF>
[[Page 40804]]
nonattainment area. This includes the authority to adopt, implement,
and enforce any subsequent emissions control contingency measures
determined to be necessary to correct future SO<INF>2</INF> attainment
problems.\24\
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\24\ The EPA approved elements of Iowa's Infrastructure SIP
requirements for the 2010 SO<INF>2</INF> NAAQS to meet the
requirements of section 110(a)(2)(E)(i) of the CAA on March 22, 2018
(83 FR 12486).
---------------------------------------------------------------------------
As previously indicated, IDNR will continue to operate its
SO<INF>2</INF> monitoring network to verify the attainment status of
the Muscatine NAA. Monitored concentrations will serve as the primary
indicator for verifying continued attainment and will also act as the
triggering mechanism for contingency measures, as described in section
7.5 of the State submittal.
In addition, IDNR will use emissions data to verify continued
compliance with the permitted emission rates used for the model
demonstration in the maintenance plan. Iowa's submittal describes the
State's process for ensuring source compliance with the emissions
limits, stack testing, monitoring, and recordkeeping requirements
associated with the control measures in the SIP-approved construction
permits for GPC, MPW, and Monsanto. All three facilities are also
permitted under the Title V operating permit program. 567 IAC 22.108(5)
requires semi-annual reports and identification of all instances of
deviations from permit requirements, including the cause of the
deviation and any corrective or preventative measures taken.
In addition, in compliance with the EPA's Air Emissions Reporting
Requirements (80 FR 8787), Iowa develops a comprehensive emissions
inventory of point, area, and mobile sources every three years. This
triennial inventory compiled by the State is contained in the EPA's
NEI, which is made publicly available every three years. The EPA
proposes to find that the information provided in Iowa's maintenance
plan demonstrates the State has the legal authority to implement and
enforce all measures necessary to attain and to maintain the 2010 1-
hour SO<INF>2</INF> NAAQS.
5. Contingency Measures
Section 175A(d) of the CAA requires that a maintenance plan include
such contingency measures as the EPA deems necessary to assure that the
State will promptly correct a violation of the NAAQS that occurs after
redesignation. 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. In cases
where attainment revolves around compliance of a single source or a
small set of sources with emissions limits shown to provide for
attainment, the EPA interprets CAA section 175A's requirement for
``contingency provisions'' to mean that the state agency has a
comprehensive program to identify sources of violations of the
SO<INF>2</INF> NAAQS and to undertake aggressive follow-up for
compliance and enforcement, including expedited procedures for
establishing enforceable consent agreement pending the adoption of
revised SIPs.\25\ 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 continue to 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 CAA section 175A(d).
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\25\ See 2014 SO<INF>2</INF> Guidance, at 69.
---------------------------------------------------------------------------
IDNR has committed to continuing implementation of all measures
indicated in the 2016 attainment plan after redesignation of the
Muscatine NAA. Furthermore, the State developed additional contingency
provisions in the 2021 maintenance plan for added assurance that any
violation of the NAAQS that occurs after redesignation of the area to
attainment will promptly be corrected. The maintenance plan contains
triggering indicators for contingency measures, a schedule for
implementing these potential measures, and has specified multiple
potential options to correct any NAAQS violation. SO<INF>2</INF>
monitoring data will serve as the primary trigger for any responses to
prevent or correct a NAAQS violation in the Area. Iowa's contingency
plan establishes both warning level and action level responses with
specific triggering indicators for each. A warning level response will
occur if a certified annual 99th percentile daily maximum 1-hour
SO<INF>2</INF> concentration exceeds the 2010 1-hour SO<INF>2</INF>
NAAQS at any monitor site in the Muscatine NAA. IDNR will conduct a
study within six months to evaluate whether the trend, if any,
indicates increasing SO<INF>2</INF> concentrations in the Muscatine
NAA. Any necessary control measures developed in response to a caution
level trigger will be implemented as expeditiously as practicable with
the intention of preventing future violations of the NAAQS from
occurring.
An action level response will occur when the 1-hour design value,
based on the average of three consecutive years of 99th percentile
daily maximum 1-hour SO<INF>2</INF> concentrations, violates the 2010
1-hour SO<INF>2</INF> NAAQS at any monitor site in the Muscatine NAA.
In response, IDNR will evaluate additional control measures needed to
assure future attainment of the 2010 1-hour SO<INF>2</INF> NAAQS. IDNR
will establish orders, issue new air construction permits, or modify
existing permits within approximately nine months of completion of a
culpability investigation that identifies such actions as being
necessary to mitigate the NAAQS violation. IDNR will plan to complete
the culpability investigation no later than three months after the
action level response has been triggered. The contingency plan
identifies multiple potential control measures for either the caution
level response or the action level response including: fuel switches,
improvements to existing control devices, production curtailments,
reductions to operating loads, housekeeping and maintenance
improvements, or other appropriate measures necessary to mitigate the
elevated SO<INF>2</INF> levels.
The EPA is proposing to conclude that the maintenance plan
adequately addresses the five basic components of a maintenance plan:
the attainment emissions inventory; maintenance demonstration;
monitoring; verification of continued attainment; and a contingency
plan. Therefore, the EPA proposes to determine that the maintenance
plan for the Muscatine NAA meets the requirements of CAA section 175A
and is thus proposing to approve the maintenance plan into the Iowa
SIP.
E. Criterion (5)--Iowa Has Met All Applicable Requirements Under
Section 110 and Part D of Title I of the CAA
In accordance with section 107(d)(3)(E)(v) of the CAA, to
redesignate the Muscatine NAA to attainment, Iowa must meet all
requirements applicable for purposes of redesignation to the Muscatine
NAA under CAA section 110 (general SIP requirements) and part D of
title I of the CAA (SIP requirements for nonattainment areas).
1. Section 110 General Requirements for SIPs
Pursuant to CAA section 110(a)(1), whenever new or revised NAAQS
are promulgated, the CAA requires States to submit a plan (i.e., SIP)
for the implementation, maintenance, and enforcement of such NAAQS.
Section
[[Page 40805]]
110(a)(2) of title I of the CAA contains the general requirements for a
SIP, also known as ``infrastructure'' requirements. These requirements
include, but are not limited to, the following: Submittal of a SIP that
has been adopted by the State after reasonable public notice and
hearing; provisions for establishment and operation of appropriate
procedures needed to monitor ambient air quality; implementation of a
source permit program; provisions for the implementation of part C
requirements (Prevention of Significant Deterioration (PSD)) and
provisions for the implementation of part D requirements (New Source
Review (NSR) permit programs); provisions for air pollution modeling;
and provisions for public and local agency participation in planning
and emissions control rule development.
Section 110(a)(2)(D) requires that SIPs contain certain measures to
prevent sources in a State from significantly contributing to air
quality problems in another State. To implement this provision, the EPA
has required certain States to establish programs to address the
interstate transport of air pollutants. The section 110(a)(2)(D)
requirements for a state are not linked with a nonattainment area's
designation and classification in that State and are therefore not
applicable for purposes of an area's redesignation. The transport SIP
submittal requirements, where applicable, continue to apply to a state
regardless of the designation of any one area in the state.
In addition, other section 110 elements that are neither connected
with nonattainment plan submissions nor linked with an area's
attainment status are not applicable requirements for purposes of
redesignation. The area will still be subject to these requirements
after the area is redesignated. The section 110 and part D requirements
which are linked with an area's designation and classification are the
relevant measures to evaluate in reviewing a redesignation request.
This approach is consistent with the EPA's existing policy on
applicability (i.e., for redesignations) of conformity and oxygenated
fuels requirements, as well as with section 184 ozone transport
requirements.\26\
---------------------------------------------------------------------------
\26\ See Reading, Pennsylvania, proposed and final rulemakings
(61 FR 53174-53176, October 10, 1996), (62 FR 24826, May 7, 2008);
Cleveland-Akron-Loraine, Ohio, final rulemaking (61 FR 20458, May
7,1996); and Tampa, Florida, final rulemaking at (60 FR 62748,
December 7, 1995). See also the discussion on this issue in the
Cincinnati, Ohio, redesignation (65 FR 37890, June 19, 2000), and in
the Pittsburgh, Pennsylvania, redesignation (66 FR 50399, October
19, 2001).
---------------------------------------------------------------------------
The EPA approved elements of Iowa's July 19, 2013 SO<INF>2</INF>
infrastructure SIP submittal on March 22, 2018.\27\ As explained
previously, certain general requirements of CAA section 110(a)(2) are
statewide requirements that are not linked to the nonattainment status
of the Muscatine NAA and are therefore not ``applicable requirements''
for the purpose of reviewing Iowa's redesignation request.
Nevertheless, Iowa submitted and EPA approved the State's
SO<INF>2</INF> infrastructure SIP. The EPA proposes to conclude that
Iowa has satisfied the criterion of section 107(d)(3)(E)(v) related to
section 110(a)(2) of the CAA.
---------------------------------------------------------------------------
\27\ 83 FR 12486, March 22, 2018.
---------------------------------------------------------------------------
2. Part D Requirements
In addition to the CAA section 110 requirements, section
107(d)(3)(E)(v) requires that the state meet all the requirements
applicable to the nonattainment area ``under part D of this
subchapter'' for the nonattainment area to be redesignated. Both
section 107 and part D are within subchapter 1 of the CAA. Part D,
entitled ``Plan Requirements for Nonattainment Areas,'' consists of six
subparts, of which only subparts 1 and 5 are applicable to
SO<INF>2</INF> nonattainment areas. Subpart 1 (sections 171 through
179B) contains provisions that can apply to all nonattainment areas for
all criteria pollutants, while subpart 5 (sections 191 through 192)
contains additional provisions for SO<INF>2</INF>, NO<INF>X</INF>, or
lead nonattainment areas. The requirements applicable to this
redesignation are discussed below.
a. Subpart 1 Requirements
CAA section 172 requires states with nonattainment areas to submit
plans that provide for timely attainment of the NAAQS. More
specifically, CAA section 172(c) contains general requirements for
nonattainment plans. A thorough discussion of these requirements is
found in the General Preamble for Implementation of title I.\28\
---------------------------------------------------------------------------
\28\ 57 FR 13498, April 16, 1992.
---------------------------------------------------------------------------
As noted in the General Preamble, certain attainment-related
planning requirements under section 172(c) no longer have meaning for
an area that is already attaining the NAAQS, and therefore are not
applicable for purposes of redesignation. For example, for an area that
is already attaining the NAAQS, there would be nothing for the State to
provide to show reasonable further progress to attainment in that area.
Similarly, the CAA section 172 requirements for the attainment
demonstration, implementation of reasonably available control measures,
including reasonably available control technology, and contingency
measures that are triggered if an area fails to meet RFP or fails to
attain are also not applicable for purposes of redesignation.
Nevertheless, as discussed earlier, Iowa submitted and EPA approved an
attainment plan addressing the attainment planning requirements.\29\
---------------------------------------------------------------------------
\29\ 85 FR 73218, November 17, 2020.
---------------------------------------------------------------------------
With respect to CAA section 172(c)(3), Iowa was required to submit
an actual current emissions inventory with its attainment plan. Iowa
had submitted a base year inventory with its attainment plan SIP on May
26, 2016, and the EPA approved this element on November 17, 2020.\30\
---------------------------------------------------------------------------
\30\ Id.
---------------------------------------------------------------------------
Section 173 of the CAA includes requirements for permit programs
that are required in a nonattainment area for new sources as required
by section 172(c)(5), known as nonattainment new source review (NNSR).
However, the EPA has a longstanding interpretation that because the
NNSR permit program is replaced by the PSD permit program upon an
area's redesignation to attainment, nonattainment areas seeking
redesignation to attainment do not need a fully approved part D NNSR
program to be redesignated. A more detailed rationale for this view is
described in a memorandum from Mary Nichols, Assistant Administrator
for Air and Radiation, dated October 14, 1994, entitled, ``Part D New
Source Review Requirements for Areas Requesting Redesignation to
Attainment.'' \31\ Nevertheless, the EPA notes that the Iowa currently
has fully-approved NNSR and PSD programs in place at 567 IAC Chapter 31
and 567 IAC Chapter 33, respectively. Iowa's PSD program will become
applicable for SO<INF>2</INF> in the Muscatine NAA upon redesignation
to attainment.
---------------------------------------------------------------------------
\31\ Available at at <a href="https://www.epa.gov/sites/default/files/2015-07/documents/101494m.pdf">https://www.epa.gov/sites/default/files/2015-07/documents/101494m.pdf</a>.
---------------------------------------------------------------------------
CAA section 175A requires that states seeking redesignation of an
area to attainment submit a ``maintenance plan'' containing certain
elements. Iowa included a maintenance plan for the Muscatine NAA with
its November 17, 2021 redesignation request, which the EPA is proposing
to approve in conjunction with the redesignation, and it is discussed
in detail in section V., Criterion (4) of this document.
Section 176(c) of the CAA requires that Federal actions conform to
the air quality planning goals in the applicable SIP. The requirement
to determine conformity applies to transportation
[[Page 40806]]
plans, programs, and projects that are developed, funded, or approved
under title 23 of the United States Code and the Federal Transit Act
(transportation conformity) as well as to all other Federally-supported
or funded projects (general conformity). Section 176(c) of the CAA also
requires that states establish criteria and procedures to ensure that
Federally-supported or funded transportation plans, transportation
improvement programs (TIPs) and projects conform to the goals of the
applicable SIP. This is referred to as a transportation conformity SIP.
In the preamble to the January 1993 proposed transportation conformity
rule, the EPA stated that, ``Based on available emissions information,
the EPA believes highway and transit motor vehicles are not significant
sources of lead or sulfur dioxide. Therefore, transportation plans,
TIPs, and projects are presumed to conform to the applicable
implementation plans for these pollutants.'' \32\ In November 1993, the
EPA finalized its transportation conformity regulations. One section of
those regulations addressed the geographic applicability of the
transportation conformity regulations. The regulation stated at that
time that, ``The provisions of this subpart apply with respect to
emissions of the following criteria pollutants: Ozone, carbon monoxide,
nitrogen dioxide, and particles with an aerodynamic diameter less than
or equal to a nominal 10 micrometers (PM<INF>10</INF>).'' \33\ Based on
this provision, transportation conformity does not apply in
nonattainment or maintenance areas for SO<INF>2</INF>. Therefore, a
transportation conformity SIP is not required for SO<INF>2</INF>
nonattainment and maintenance areas and is not necessary for an
SO<INF>2</INF> nonattainment area to be redesignated to attainment, and
the EPA's transportation conformity rules do not apply to
SO<INF>2</INF> for the Muscatine NAA.
---------------------------------------------------------------------------
\32\ 58 FR 3776, January 11, 1993.
\33\ This provision has been revised to include particles with
an aerodynamic diameter less than or equal to a nominal 2.5
micrometers (PM<INF>2.5</INF>). See 40 CFR 93.102(b)(1).
---------------------------------------------------------------------------
Section 179(a) of the CAA addresses potential sanctions for the
failure of a State to submit certain required SIP elements by statutory
deadlines. The EPA is not aware of any missing or incomplete Muscatine
NAA planning elements subject to section 179(a) of the CAA.
b. Subpart 5 Requirements
The subpart 5 requirements, which consist of sections 191 and 192
of the CAA, are specific provisions applicable to SO<INF>2</INF>,
NO<INF>2</INF>, or lead nonattainment areas. Section 191 of the CAA
requires states with areas designated nonattainment for SO<INF>2</INF>,
NO<INF>2</INF>, or lead after November 15, 1990, to submit within 18
months of the designation an implementation plan meeting the
requirements of part D. The substance of the required plans is
established by section 172(c). As noted, Iowa submitted its attainment
plan and EPA approved that plan on November 17, 2020.\34\
---------------------------------------------------------------------------
\34\ 85 FR 73218, November 17, 2020.
---------------------------------------------------------------------------
Section 192 sets forth attainment dates for nonattainment areas
under section 191. For SO<INF>2</INF>, section 192(a) requires that
attainment plans provide for attainment of the primary standard as
expeditiously as possible, but no later than five years from the date
of the nonattainment designation. The EPA designated the Muscatine NAA
as nonattainment on August 5, 2013, with an attainment date of October
4, 2018.\35\ However, because the EPA is reviewing a redesignation
request under section 107(d)(3)(E), rather than a determination of
attainment under section 179(c), the determination of whether the Area
attained by the attainment date set forth in section 192 is not
applicable to this action proposing approval of Iowa's redesignation
request.
---------------------------------------------------------------------------
\35\ 78 FR 47191, August 5, 2013.
---------------------------------------------------------------------------
Based on the above, the EPA is proposing to find that Iowa has
satisfied the applicable requirements for the redesignation of the
Muscatine NAA under section 110 and part D of title I of the CAA.
VI. What is the EPA's analysis of the SIP-approved permit
modifications?
Iowa's 2021 redesignation request and maintenance plan for the
Muscatine NAA requests revisions to source-specific air construction
permits relied upon in the 2016 attainment plan. The State's model-
based attainment demonstration from its 2016 attainment plan, which the
EPA approved on November 17, 2020, was based on SO<INF>2</INF> controls
and emission limitations contained in final air construction permits
issued by IDNR and the EPA's approval action incorporated a total of 58
construction permits into the Iowa SIP. Iowa's 2021 submittal requests
that the EPA make several revisions to SIP-approved construction
permits for the three sources within the nonattainment area, and also
requests removal of twelve permits from the SIP for GPC. The 2021 SIP
submission also includes modeling to demonstrate that the Muscatine
area will continue to attain the 2010 SO<INF>2</INF> NAAQS as a result
of compliance with the revised permit limits.
As part of the 2021 submission, Iowa also requests to remove eight
permits for these three sources that were originally incorporated into
the Iowa SIP pursuant to the 1971 24-hour SO<INF>2</INF> primary
standard. In 1994, the EPA designated a portion of Muscatine County as
nonattainment. The state subsequently developed an attainment plan that
contained control measures for GPC, MPW, and Monsanto.\36\ The EPA
redesignated the area to attainment in 1998 (63 FR 13343, March 19,
1998) and approved the state's second 10-year maintenance plan on
August 1, 2007 (72 FR 41900). The underlying permit requirements
associated with those actions are no longer needed due to the
revocation of the 1971 24-hour and annual primary SO<INF>2</INF>
NAAQS.\37\
---------------------------------------------------------------------------
\36\ The attainment plan and permits were submitted in 1996
(revised in 1997) and approved by EPA on December 1, 1997 (62 FR
63454).
\37\ The 2010 primary SO<INF>2</INF> NAAQS revision (75 FR
35519, June 22, 2010) included provisions to revoke both the 24-hour
and annual average primary SO<INF>2</INF> standards. In Muscatine,
those standards ceased to apply on October 4, 2014, one year after
its designation for the 2010 1-hour SO<INF>2</INF> standard.
---------------------------------------------------------------------------
All of the permit changes requested by Iowa are summarized below
and in sections 5.1 Source Summary Tables and 9. Removal of Provisions
for the Revoked SO2 Standards of the State submittal included in the
docket for this action. The new and modified permits being incorporated
into the SIP are contained in Attachments 1 through 3 of the State
submittal in the docket for this action.
A. Removal of Permits From the Iowa SIP
Iowa requests to remove twelve GPC permits relied upon in the 2016
attainment plan for emission points (stacks) no longer in service. The
permit removals are described in table 5.
[[Page 40807]]
Table 5--GPC Permits for Removal From the Iowa SIP
------------------------------------------------------------------------
Permit No. Justification
------------------------------------------------------------------------
15-A-078........................ Two stacks removed from service and
79-A-194-S2..................... the emission units were vented to a
new stack with scrubbers and a SO2
RACT limit (see permit #17-A-298).
74-A-014-S1..................... Three stacks removed from service and
74-A-015-S2..................... the emission units were vented to a
79-A-195-S2..................... new stack with scrubbers and a SO2
RACT limit (see permit #17-A-299).
71-A-067-S4..................... Stack was removed from service and the
emission source was decommissioned.
15-A-202........................ Two stacks were removed from service
15-A-209........................ and the units were vented to an
existing emission point with a
scrubber (see permit #15-A-200-S1).
11-A-338-S1..................... Two stacks were removed from service
15-A-354........................ and the units were vented to an
existing emission point (see permit
#15-A-213-S2).
05-A-926-S4..................... One stack was removed from service and
some units were vented to a new stack
(see permit #17-A-112). Some units
were decommissioned.
75-A-087-S1..................... One stack was removed from service and
the emission units were vented to a
new stack with a SO2 RACT limit (see
#19-A-515-S1).
------------------------------------------------------------------------
Iowa also requests that EPA remove eight permits from the SIP due
to the revocation of the 24-hour and annual primary SO<INF>2</INF>
NAAQS. The permit removals are described in table 6.
Table 6--Permits for Removal From the Iowa SIP Due to the Revoked SO2 NAAQS
----------------------------------------------------------------------------------------------------------------
Facility Permit No. Justification
----------------------------------------------------------------------------------------------------------------
GPC.................................. 74-A-015-S.................. This emission point no longer exists.
79-A-194-S.................. This emission point no longer exists.
79-A-195-S.................. This emission point no longer exists.
95-A-374.................... Replaced by SIP-approved permit 95-A-374-
S4.*
MPW.................................. 74-A-175-S.................. Replaced by SIP-approved permit 74-A-175-
S4.*
95-A-373.................... Replaced by SIP-approved permit 95-A-373-
P3*; updating to 95-A-373-P4.
Monsanto............................. 76-A-161S3.................. In 2012, Boilers #6 and #7 were both
76-A-265S3.................. restricted to combusting only natural gas
and their SO2 limits were removed from the
modified permits.
----------------------------------------------------------------------------------------------------------------
* Approved by EPA on November 17, 2020 (85 FR 73218), as part of the DNR's attainment plan for the 1-hour SO2
NAAQS.
B. New Permits To Be Added to the Iowa SIP
Iowa requests to add five new permits into the SIP for the 2010 1-
hour SO<INF>2</INF> NAAQS. The new permits are for four new stacks and
one newly identified SO<INF>2</INF> emission source. The new permits
are summarized in table 7.
Table 7--GPC Permits To Be Added to the Iowa SIP
------------------------------------------------------------------------
Permit No. Justification
------------------------------------------------------------------------
17-A-298........................ New stack with scrubbers and a SO2
RACT limit.
17-A-299........................ New stack with scrubbers and a SO2
RACT limit.
17-A-112........................ New stack retains some existing units,
adds new units, and retains the
unchanged SO2 RACT limit from the
previous stack.
19-A-515-S1..................... New stack with a SO2 RACT limit.
18-A-136........................ Permit to establish a SO2 RACT limit
for a previously unidentified SO2
source.
------------------------------------------------------------------------
C. Modifications to Existing Permits in the Iowa SIP
Iowa also requests to modify twenty GPC permits, two MPW permits,
and one Monsanto permit in the Iowa SIP that were relied upon in the
2016 attainment plan. Several revisions to GPC permits establish a
Collection of Air Permits (CAP) which is a type of air construction
permit issued by IDNR that combines the requirements and conditions for
multiple emission points (and thus multiple permit numbers) into one
document. The permit modifications are described in table 8.
Table 8--Modifications to Existing Permits in the Iowa SIP
----------------------------------------------------------------------------------------------------------------
Description of
Facility Outdated permit No. Replacement permit No. modification
----------------------------------------------------------------------------------------------------------------
GPC...................... 80-A-149-S5 CAP: 80-A-149-S6 All requirements moved
GPC...................... 80-A-150-S5 CAP: 80-A-150-S6 into a CAP, SO2 RACT
limit unchanged.
GPC...................... 85-A-031-S2 CAP: 85-A-031-S5 All requirements moved
GPC...................... 85-A-032-S2 CAP: 85-A-032-S5 into a CAP, dispersion
parameters updated, RACT
limit changed from 0.014
to 0.017 lb/hr
(combined).
[[Page 40808]]
GPC...................... 91-A-068-S2 91-A-068-S3 Increase in operating
capacity, SO2 RACT limit
unchanged.
GPC...................... 92-A-383-S2 92-A-383-S3 Dispersion parameters
updated, SO2 RACT limit
unchanged.
GPC...................... 92-A-385-S1 92-A-385-S2 Dispersion parameters
updated, SO2 RACT limit
unchanged.
GPC...................... 94-A-055-S1 CAP: 94-A-055-S3 All requirements moved
GPC...................... 94-A-061-S1 CAP: 94-A-061-S3 into a CAP, dispersion
parameters updated, new
low emissions burner for
other pollutants, SO2
RACT limit unchanged.
GPC...................... 02-A-781-S2 02-A-781-S3 Permit update unrelated to
SO2.
GPC...................... 02-A-782-S2 02-A-782-S3 Permit update unrelated to
SO2.
GPC...................... 10-A-563-S1 10-A-563-S2 Dispersion parameters
updated, SO2 RACT limit
unchanged.
GPC...................... 15-A-200 15-A-200-S1 Added emission units
vented to this stack,
retained the sodium
bisulfate requirements,
SO2 RACT limit unchanged.
GPC...................... 15-A-201 15-A-201-S1 Additional equipment
(e.g., tanks, grinding &
separation equipment)
identified as SO2 sources
and vented here, scrubber
installed as previously
required, sodium
bisulfite requirements
retained, SO2 RACT limit
unchanged.
GPC...................... 15-A-213 15-A-213-S2 Added emission units
vented to this stack,
updated the dispersion
parameters, SO2 RACT
limit unchanged.
GPC...................... 15-A-486 15-A-486-S1 Additional equipment
permitted (adds
capacity), SO2 RACT limit
changed from 0.201 to
0.27 lb/hr.
GPC...................... 15-A-326 15-A-326-S1 Capacity restrictions
added, SO2 RACT limit
unchanged.
GPC...................... 03-A-471-S1 03-A-471-S3 Dispersion parameters
updated, SO2 RACT limit
unchanged.
GPC...................... 06-A-1261-S1 06-A-1261-S2 Permit update unrelated to
SO2.
GPC...................... 15-A-199 15-A-199-S1 Annual throughput revised,
SO2 RACT limit unchanged.
MPW...................... 95-A-373-P3 95-A-373-P4 Permit update unrelated to
SO2.
MPW...................... 80-A-191-P3 80-A-191-P4 Permit update unrelated to
SO2.
Monsanto................. 82-A-092-P11 82-A-092-P12 Converted Boiler #8 from
combusting primarily coal
to natural gas only,
updated the dispersion
parameters, and reduced
the SO2 RACT limit.
----------------------------------------------------------------------------------------------------------------
D. EPA Analysis of Permit Revisions
With the proposed revisions, Iowa's SIP will contain a total of 51
air construction permits for the 2010 SO<INF>2</INF> NAAQS. The total
number of GPC permits will be reduced from 52 to 45 permits. The total
number of MPW permits will remain at four and the total number of
Monsanto permits will remain at two.
The new and modified air construction permits include emission
limits, timetables for compliance, reporting, and recordkeeping
requirements. Each permit also contains performance testing (emissions
testing) obligations with specific schedules, methods, and frequencies
for compliance. Additionally, GPC, MPW, and Monsanto are major sources
under the Title V operating permit program and are subject to semi-
annual reports requirements.
The EPA reviewed the submitted permit revisions in accordance with
the anti-backsliding provisions of CAA section 110(l). With the
submitted permit revisions, the total maximum permitted allowable
emissions for the three facilities in the NAA were reduced from 6,414
tpy in the 2016 attainment plan to 5,555 tpy in the 2021 maintenance
plan. While some RACT limits were increased in the modified permits and
new RACT limits were added in new permits, the EPA finds the resulting
relatively small emissions increase is offset by larger emissions
reductions from the removal or modification of other permits. To
further demonstrate that the Muscatine NAA will continue to attain and
maintain the 2010 SO<INF>2</INF> NAAQS with the submitted permit
updates, Iowa also provided updated dispersion modeling based on the
maximum permitted allowable emissions in its 2021 SIP submission. As
discussed in the maintenance demonstration section above, the EPA
reviewed the modeling analysis submitted by Iowa and finds the revised
control measures for GPC, MPW, and Monsanto continue to provide for
attainment and maintenance of the 2010 SO<INF>2</INF> NAAQS.
For the removal of source-specific permits due to the revocation of
the 24-hour and annual primary SO<INF>2</INF> NAAQS, the anti-
backsliding provisions of CAA section 110(l) are satisfied by
replacement with the attainment plan, maintenance plan, and associated
permits for the more stringent 2010 1-hour SO<INF>2</INF> standard.
Accordingly, the emission limits approved into the SIP for the 1-hour
SO<INF>2</INF> NAAQS (through the permits incorporated into the SIP
either through the attainment or maintenance plan) are more stringent
than the prior emission limits for the revoked 24-hour or annual
primary SO<INF>2</INF> NAAQS. These permits were specifically for units
that either no longer operate or have more stringent limits in place.
For these reasons, the EPA proposes to find that the submitted
permit revisions in Iowa's 2021 SIP request will not interfere with any
applicable requirement concerning attainment and reasonable further
progress (as defined in section 171 of the CAA) or any other applicable
requirement of the CAA, as required under section 110(l) of the Act.
Accordingly, the EPA proposes to approve revisions to source-specific
permits to add five new permits, replace twenty-three revised permits,
and remove twenty permits for Muscatine area sources in the Iowa SIP as
detailed in sections 5.1 and 9 of the State submission. For new or
revised permits, the EPA is proposing to approve the entire permits
into the SIP, consistent with Iowa's request.
VII. What action is the EPA proposing to take?
The EPA is proposing to approve Iowa's redesignation request for
the Muscatine NAA. Final approval of the redesignation request would
change the legal designation of the portion of Muscatine County
designated nonattainment at 40 CFR 81.316 to attainment for the 2010 1-
hour primary SO<INF>2</INF> NAAQS. The EPA is also proposing to approve
Iowa's maintenance plan for the 2010 1-hour SO<INF>2</INF> NAAQS for
the Muscatine nonattainment area. Finally, the EPA is proposing to add
new or revised permits for Muscatine area sources into the Iowa SIP and
remove certain air construction permits from the SIP. The EPA is
processing this as a proposed action because we are soliciting comments
on this proposed
[[Page 40809]]
action. Final rulemaking will occur after consideration of any
comments.
VIII. Incorporation by Reference
In this document, the EPA is proposing to include regulatory text
in an EPA final rule that includes incorporation by reference. In
accordance with requirements of 1 CFR 51.5, the EPA is proposing to
delete Iowa permits #74-A-015-S, #79-A-194-S, #79-A-195-S, #95-A-374,
#74-A-175-S, #95-A-373, #76-A-161S3, #76-A-265S3, #15-A-078, #79-A-194-
S2, #71-A-067-S4, #75-A-087-S1, #74-A-014-S1, #74-A-015-S2, #79-A-195-
S2, #80-A-149-S5, #80-A-150-S5, #85-A-031-S2, #85-A-032-S2, #91-A-068-
S2, #92-A-383-S2, #92-A-385-S1, #94-A-055-S1, #94-A-061-S1, #02-A-781-
S2, #02-A-782-S2, #10-A-563-S1, #15-A-200, #15-A-201, #15-A-202, #15-A-
209, #15-A-213, #15-A-486, #15-A-326, #03-A-471-S1, #05-A-926-S4, #06-
A-1261-S1, #11-A-338-S1, #15-A-354, #15-A-199, #95-A-373-P3, #80-A-191-
P3, and #82-A-092-P11. The EPA is proposing to add incorporation by
reference of Iowa permits #17-A-298, #17-A-299, #19-A-515-S1, #18-A-
136, #17-A-112, #80-A-149-S6, #80-A-150-S6, #85-A-031-S5, #85-A-032-S5,
#91-A-068-S3, #92-A-383-S3, #92-A-385-S2, #94-A-055-S3, #94-A-061-S3,
#02-A-781-S3, #02-A-782-S3, #10-A-563-S2, #15-A-200-S1, #15-A-201-S1,
#15-A-213-S2, #15-A-486-S1, #15-A-326-S1, #03-A-471-S3, #06-A-1261-S2,
#15-A-199-S1, #95-A-373-P4, #80-A-191-P4, and #82-A-092-P12 discussed
in sections IV.-VII. of this preamble and as set forth below in the
proposed amendments to 40 CFR part 52. The EPA has made, and will
continue to make, these materials generally available through <a href="https://www.regulations.gov">https://www.regulations.gov</a> and at the EPA Region 7 Office (please contact the
person identified in the FOR FURTHER INFORMATION CONTACT section of
this preamble for more information).
IX. Statutory and Executive Order Reviews
Under the CAA, the Administrator is required to approve a SIP
submission that complies with the provisions of the CAA and applicable
Federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in
reviewing SIP submissions, the EPA's role is to approve state choices,
provided that they meet the criteria of the CAA. Accordingly, this
action merely approves state law as meeting Federal requirements and
does not impose additional requirements beyond those imposed by state
law. For that reason, this action:
<bullet> Is not a significant regulatory action subject to review
by the Office of Management and Budget under Executive Order 12866 (58
FR 51735, October 4, 1993);
<bullet> Is not subject to Executive Order 14192 (90 FR 9065,
February 6, 2025) because SIP actions are exempt from review under
Executive Order 12866;
<bullet> Does not impose an information collection burden under the
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
<bullet> 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.);
<bullet> 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);
<bullet> Does not have federalism implications as specified in
Executive Order 13132 (64 FR 43255, August 10, 1999);
<bullet> Is not subject to Executive Order 13045 (62 FR 19885,
April 23, 1997) because it approves a state program;
<bullet> Is not a significant regulatory action subject to
Executive Order 13211 (66 FR 28355, May 22, 2001); and
<bullet> Is not subject to requirements of section 12(d) of the
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272
note) because application of those requirements would be inconsistent
with the CAA.
In addition, the SIP is not approved to apply on any Indian
reservation land or in any other area where the EPA or an Indian Tribe
has demonstrated that a Tribe has jurisdiction. In those areas of
Indian country, the rule does not have Tribal implications and will not
impose substantial direct costs on Tribal governments or preempt Tribal
law as specified by Executive Order 13175 (65 FR 67249, November 9,
2000).
List of Subjects
40 CFR Part 52
Environmental protection, Air pollution control, Incorporation by
reference, Maintenance plan, Redesignation, Sulfur oxides.
40 CFR Part 81
Environmental protection, Air pollution control, Designations,
Intergovernmental relations, Redesignation, Reporting and recordkeeping
requirements, Sulfur oxides.
Dated: August 8, 2025.
James Macy,
Regional Administrator, Region 7.
For the reasons stated in the preamble, the EPA proposes to amend
40 CFR parts 52 and 81 as set forth below:
PART 52--APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS
0
1. The authority citation for part 52 continues to read as follows:
Authority: 42 U.S.C. 7401 et seq.
Subpart Q--Iowa
0
2. In Sec. 52.820:
0
a. The table in paragraph (d) is amended by:
0
i. Revising the entries ``(113),'' ``(114),'' ``(115),'' ``(116),''
``(118),'' ``(122),'' ``(123),'' ``(124),'' ``(125),'' ``(129),''
``(131),'' ``(132),'' ``(133),'' ``(134),'' ``(135),'' ``(136),''
``(138),'' ``(139),'' ``(140),'' ``(153),'' ``(156),'' ``(157),''
``(158),'' ``(160),'' ``(163),'' ``(166),'' ``(167),'' and ``(168)'';
and
0
ii. Removing and reserving entries ``(3),'' ``(4),'' ``(5),'' ``(6),''
``(7),'' ``(8),'' ``(9),'' ``(10),'' ``(119),'' ``(121),'' ``(141),''
``(148),'' ``(159),'' ``(161),'' and ``(162)''.
0
b. The table in paragraph (e) is amended by adding the entry ``(57)''
to the end of the table.
The revisions and addition read as follows:
Sec. 52.820 Identification of plan.
* * * * *
(d) * * *
EPA-Approved Iowa Source-Specific Orders/Permits
----------------------------------------------------------------------------------------------------------------
State
Name of source Order/permit No. effective EPA approval date Explanation
date
----------------------------------------------------------------------------------------------------------------
* * * * * * *
(3) Reserved
(4) Reserved
[[Page 40810]]
(5) Reserved
(6) Reserved
(7) Reserved
(8) Reserved
(9) Reserved
(10) Reserved
* * * * * * *
(113) Grain Processing 17-A-298 4/12/2018 [Date of publication 2010 1-hour SO2
Corporation. of the final rule in NAAQS Attainment
the Federal Plan; EPA-R07-
Register], 90 FR OAR-2025-0818;
[Federal Register FRL-12901-01-R7.
page where the
document begins of
the final rule].
(114) Grain Processing 17-A-299 4/12/2018 [Date of publication 2010 1-hour SO2
Corporation. of the final rule in NAAQS Attainment
the Federal Plan; EPA-R07-
Register], 90 FR OAR-2025-0818;
[Federal Register FRL-12901-01-R7.
page where the
document begins of
the final rule].
(115) Grain Processing 19-A-515-S1 12/22/2020 [Date of publication 2010 1-hour SO2
Corporation. of the final rule in NAAQS Attainment
the Federal Plan; EPA-R07-
Register], 90 FR OAR-2025-0818;
[Federal Register FRL-12901-01-R7.
page where the
document begins of
the final rule].
(116) Grain Processing 18-A-136 5/30/2018 [Date of publication 2010 1-hour SO2
Corporation. of the final rule in NAAQS Attainment
the Federal Plan; EPA-R07-
Register], 90 FR OAR-2025-0818;
[Federal Register FRL-12901-01-R7.
page where the
document begins of
the final rule].
* * * * * * *
(118) Grain Processing 17-A-112 5/2/2017 [Date of publication 2010 1-hour SO2
Corporation. of the final rule in NAAQS Attainment
the Federal Plan; EPA-R07-
Register], 90 FR OAR-2025-0818;
[Federal Register FRL-12901-01-R7.
page where the
document begins of
the final rule].
(119) Reserved
* * * * * * *
(121) Reserved
(122) Grain Processing 80-A-149-S6 2/21/2017 [Date of publication 2010 1-hour SO2
Corporation. of the final rule in NAAQS Attainment
the Federal Plan; EPA-R07-
Register], 90 FR OAR-2025-0818;
[Federal Register FRL-12901-01-R7.
page where the
document begins of
the final rule].
(123) Grain Processing 80-A-150-S6 2/21/2017 [Date of publication 2010 1-hour SO2
Corporation. of the final rule in NAAQS Attainment
the Federal Plan; EPA-R07-
Register], 90 FR OAR-2025-0818;
[Federal Register FRL-12901-01-R7.
page where the
document begins of
the final rule].
(124) Grain Processing 85-A-031-S5 5/19/2020 [Date of publication 2010 1-hour SO2
Corporation. of the final rule in NAAQS Attainment
the Federal Plan; EPA-R07-
Register], 90 FR OAR-2025-0818;
[Federal Register FRL-12901-01-R7.
page where the
document begins of
the final rule].
(125) Grain Processing 85-A-032-S5 5/19/2020 [Date of publication 2010 1-hour SO2
Corporation. of the final rule in NAAQS Attainment
the Federal Plan; EPA-R07-
Register], 90 FR OAR-2025-0818;
[Federal Register FRL-12901-01-R7.
page where the
document begins of
the final rule].
* * * * * * *
(129) Grain Processing 91-A-068-S3 11/4/2019 [Date of publication 2010 1-hour SO2
Corporation. of the final rule in NAAQS Attainment
the Federal Plan; EPA-R07-
Register], 90 FR OAR-2025-0818;
[Federal Register FRL-12901-01-R7.
page where the
document begins of
the final rule].
* * * * * * *
(131) Grain Processing 92-A-383-S3 10/11/2016 [Date of publication 2010 1-hour SO2
Corporation. of the final rule in NAAQS Attainment
the Federal Plan; EPA-R07-
Register], 90 FR OAR-2025-0818;
[Federal Register FRL-12901-01-R7.
page where the
document begins of
the final rule].
(132) Grain Processing 92-A-385-S2 10/11/2016 [Date of publication 2010 1-hour SO2
Corporation. of the final rule in NAAQS Attainment
the Federal Plan; EPA-R07-
Register], 90 FR OAR-2025-0818;
[Federal Register FRL-12901-01-R7.
page where the
document begins of
the final rule].
(133) Grain Processing 94-A-055-S3 5/13/2021 [Date of publication 2010 1-hour SO2
Corporation. of the final rule in NAAQS Attainment
the Federal Plan; EPA-R07-
Register], 90 FR OAR-2025-0818;
[Federal Register FRL-12901-01-R7.
page where the
document begins of
the final rule].
[[Page 40811]]
(134) Grain Processing 94-A-061-S3 5/13/2021 [Date of publication 2010 1-hour SO2
Corporation. of the final rule in NAAQS Attainment
the Federal Plan; EPA-R07-
Register], 90 FR OAR-2025-0818;
[Federal Register FRL-12901-01-R7.
page where the
document begins of
the final rule].
(135) Grain Processing 02-A-781-S3 2/8/2018 [Date of publication 2010 1-hour SO2
Corporation. of the final rule in NAAQS Attainment
the Federal Plan; EPA-R07-
Register], 90 FR OAR-2025-0818;
[Federal Register FRL-12901-01-R7.
page where the
document begins of
the final rule].
(136) Grain Processing 02-A-782-S3 2/8/2018 [Date of publication 2010 1-hour SO2
Corporation. of the final rule in NAAQS Attainment
the Federal Plan; EPA-R07-
Register], 90 FR OAR-2025-0818;
[Federal Register FRL-12901-01-R7.
page where the
document begins of
the final rule].
* * * * * * *
(138) Grain Processing 10-A-563-S2 7/25/2017 [Date of publication 2010 1-hour SO2
Corporation. of the final rule in NAAQS Attainment
the Federal Plan; EPA-R07-
Register], 90 FR OAR-2025-0818;
[Federal Register FRL-12901-01-R7.
page where the
document begins of
the final rule].
(139) Grain Processing 15-A-200-S1 4/12/2018 [Date of publication 2010 1-hour SO2
Corporation. of the final rule in NAAQS Attainment
the Federal Plan; EPA-R07-
Register], 90 FR OAR-2025-0818;
[Federal Register FRL-12901-01-R7.
page where the
document begins of
the final rule].
(140) Grain Processing 15-A-201-S1 4/12/2018 [Date of publication 2010 1-hour SO2
Corporation. of the final rule in NAAQS Attainment
the Federal Plan; EPA-R07-
Register], 90 FR OAR-2025-0818;
[Federal Register FRL-12901-01-R7.
page where the
document begins of
the final rule].
(141) Reserved
* * * * * * *
(148) Reserved
* * * * * * *
(153) Grain Processing 15-A-213-S2 12/22/2020 [Date of publication 2010 1-hour SO2
Corporation. of the final rule in NAAQS Attainment
the Federal Plan; EPA-R07-
Register], 90 FR OAR-2025-0818;
[Federal Register FRL-12901-01-R7.
page where the
document begins of
the final rule].
* * * * * * *
(156) Grain Processing 15-A-486-S1 11/4/2019 [Date of publication 2010 1-hour SO2
Corporation. of the final rule in NAAQS Attainment
the Federal Plan; EPA-R07-
Register], 90 FR OAR-2025-0818;
[Federal Register FRL-12901-01-R7.
page where the
document begins of
the final rule].
(157) Grain Processing 15-A-326-S1 3/4/2020 [Date of publication 2010 1-hour SO2
Corporation. of the final rule in NAAQS Attainment
the Federal Plan; EPA-R07-
Register], 90 FR OAR-2025-0818;
[Federal Register FRL-12901-01-R7.
page where the
document begins of
the final rule].
(158) Grain Processing 03-A-471-S3 5/30/2018 [Date of publication 2010 1-hour SO2
Corporation. of the final rule in NAAQS Attainment
the Federal Plan; EPA-R07-
Register], 90 FR OAR-2025-0818;
[Federal Register FRL-12901-01-R7.
page where the
document begins of
the final rule].
(159) Reserved
(160) Grain Processing 06-A-1261-S2 12/22/2020 [Date of publication 2010 1-hour SO2
Corporation. of the final rule in NAAQS Attainment
the Federal Plan; EPA-R07-
Register], 90 FR OAR-2025-0818;
[Federal Register FRL-12901-01-R7.
page where the
document begins of
the final rule].
(161) Reserved
(162) Reserved
(163) Grain Processing 15-A-199-S1 1/11/2021 [Date of publication 2010 1-hour SO2
Corporation. of the final rule in NAAQS Attainment
the Federal Plan; EPA-R07-
Register], 90 FR OAR-2025-0818;
[Federal Register FRL-12901-01-R7.
page where the
document begins of
the final rule].
* * * * * * *
(166) Muscatine Power and Water 95-A-373-P4 6/1/2016 [Date of publication 2010 1-hour SO2
of the final rule in NAAQS Attainment
the Federal Plan; EPA-R07-
Register], 90 FR OAR-2025-0818;
[Federal Register FRL-12901-01-R7.
page where the
document begins of
the final rule].
[[Page 40812]]
(167) Muscatine Power and Water 80-A-191-P4 6/1/2016 [Date of publication 2010 1-hour SO2
of the final rule in NAAQS Attainment
the Federal Plan; EPA-R07-
Register], 90 FR OAR-2025-0818;
[Federal Register FRL-12901-01-R7.
page where the
document begins of
the final rule].
(168) Monsanto................. 82-A-092-P12 11/1/2016 [Date of publication 2010 1-hour SO2
of the final rule in NAAQS Attainment
the Federal Plan; EPA-R07-
Register], 90 FR OAR-2025-0818;
[Federal Register FRL-12901-01-R7.
page where the
document begins of
the final rule].
* * * * * * *
----------------------------------------------------------------------------------------------------------------
(e) * * *
EPA-Approved Iowa NONREGULATORY PROVISIONS
----------------------------------------------------------------------------------------------------------------
Applicable State
Name of nonregulatory SIP geographic or submittal EPA approval date Explanation
provision nonattainment area date
----------------------------------------------------------------------------------------------------------------
* * * * * * *
(57) 2010 1-hour primary SO2 A portion of 11/17/2021 [Date of publication of EPA-R07-OAR-2025-0
NAAQS Maintenance Plan. Muscatine County. the final rule in the 818; FRL-12901-01-
Federal Register], 90 R7.
FR [Federal Register
page where the document
begins of the final
rule].
----------------------------------------------------------------------------------------------------------------
0
3. In Sec. 52.834, add paragraph (c) to read as follows:
Sec. 52.834 Control strategy: Sulfur dioxide.
* * * * *
(c) Redesignation to attainment. EPA has determined, as of [date of
publication of the final rule in the Federal Register], that the
Muscatine County 2010 SO<INF>2</INF> nonattainment area is redesignated
to attainment of the 2010 SO<INF>2</INF> 1-hour National Ambient Air
Quality Standard (NAAQS) in accordance with the requirements of Clean
Air Act (CAA) section 107(d)(3) and has approved its maintenance plan
and supplemental modeling demonstration analyses as meeting the
requirements of CAA section 175A.
PART 81--DESIGNATION OF AREAS FOR AIR QUALITY PLANNING PURPOSES
0
4. The authority citation for part 81 continues to read as follows:
Authority: 42 U.S.C. 7401, et seq.
Subpart C--Section 107 Attainment Status Designations
0
5. In Sec. 81.316, the table entitled ``Iowa--2010 Sulfur Dioxide
NAAQS [Primary]'' is amended by revising the entry ``Muscatine, IA'' to
read as follows:
Sec. 81.316 Iowa.
* * * * *
Iowa--2010 Sulfur Dioxide NAAQS
[Primary]
------------------------------------------------------------------------
Designation
Designated area \1\ ----------------------------------------
Date \2\ Type
------------------------------------------------------------------------
Muscatine, IA.................. [Date of Attainment.
Muscatine County (part):....... publication of
the final rule
in the Federal
Register].
Sections 1-3, 10-15, 22-
27, 34-36 of T77N, R3W
(Lake Township).
Sections 1-3, 10-15, 22-
27, 34-36 of T76N, R3W
(Seventy-six Township).
T77N, R2W
(Bloomington
Township).
T76N, R2W
(Fruitland
Township).
All sections except 1,
12, 13, 24, 25, 36 of
T77N, R1W (Sweetland
Township).
* * * * * * *
------------------------------------------------------------------------
\1\ Includes any Indian country in each county or area, unless otherwise
specified. EPA is not determining the boundaries of any area of Indian
country in this table, including any area of Indian country located in
the larger designation area. The inclusion of any Indian country in
the designation area is not a determination that the state has
regulatory authority under the Clean Air Act for such Indian country.
\2\ This date is April 9, 2018, unless otherwise noted.
[FR Doc. 2025-15983 Filed 8-20-25; 8:45 am]
BILLING CODE 6560-50-P
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</html>Indexed from Federal Register on August 21, 2025.
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