Proposed Rule2025-11268
Finding of Failure To Attain; Air Plan Approval; Indiana; Huntington County Sulfur Dioxide Attainment Plan
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
June 18, 2025
Issuing agencies
Environmental Protection Agency
Abstract
The Environmental Protection Agency (EPA) is proposing to find that the Huntington County, Indiana nonattainment area failed to attain the 2010 Sulfur Dioxide (SO<INF>2</INF>) National Ambient Air Quality Standard (NAAQS) by the applicable attainment date of April 9, 2023. EPA is also proposing to approve revisions into the Indiana State Implementation Plan (SIP) intended to provide for attainment of the 2010 SO<INF>2</INF> NAAQS for the Huntington County nonattainment area. These SIP submissions include Indiana's attainment demonstration and other planning elements required under the Clean Air Act (CAA), and a Commissioner's Order containing enforceable emission limits. Further, EPA is proposing to find that the provisions of Indiana's SIP submittal adequately provide for attainment of the NAAQS and that the plan meets all other applicable CAA requirements.
Full Text
<html>
<head>
<title>Federal Register, Volume 90 Issue 116 (Wednesday, June 18, 2025)</title>
</head>
<body><pre>
[Federal Register Volume 90, Number 116 (Wednesday, June 18, 2025)]
[Proposed Rules]
[Pages 25968-25975]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2025-11268]
-----------------------------------------------------------------------
ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 52
[EPA-R05-OAR-2023-0564; FRL-12835-01-R5]
Finding of Failure To Attain; Air Plan Approval; Indiana;
Huntington County Sulfur Dioxide Attainment Plan
AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed rule.
-----------------------------------------------------------------------
SUMMARY: The Environmental Protection Agency (EPA) is proposing to find
that the Huntington County, Indiana nonattainment area failed to attain
the 2010 Sulfur Dioxide (SO<INF>2</INF>) National Ambient Air Quality
Standard (NAAQS) by the applicable attainment date of April 9, 2023.
EPA is also proposing to approve revisions into the Indiana State
Implementation Plan (SIP) intended to provide for attainment of the
2010 SO<INF>2</INF> NAAQS for the Huntington County nonattainment area.
These SIP submissions include Indiana's attainment demonstration and
other planning elements required under the Clean Air Act (CAA), and a
Commissioner's Order containing enforceable emission limits. Further,
EPA is proposing to find that the provisions of Indiana's SIP submittal
adequately provide for attainment of the NAAQS and that the plan meets
all other applicable CAA requirements.
DATES: Comments must be received on or before July 18, 2025.
ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R05-
OAR-2023-0564 at <a href="https://www.regulations.gov">https://www.regulations.gov</a>, or via email to
<a href="/cdn-cgi/l/email-protection#24455656450a574556454c644154450a434b52"><span class="__cf_email__" data-cfemail="d8b9aaaab9f6abb9aab9b098bda8b9f6bfb7ae">[email protected]</span></a>. For comments submitted at <a href="http://Regulations.gov">Regulations.gov</a>, follow
the online instructions for submitting comments. Once submitted,
comments cannot be edited or removed from the docket. EPA may publish
any comment received to its public docket. Do not submit to EPA's
docket at <a href="https://www.regulations.gov">https://www.regulations.gov</a> any information you consider to
be Confidential Business Information (CBI), Proprietary Business
Information (PBI), or other information whose disclosure is restricted
by statute. Multimedia submissions (audio, video, etc.) must be
accompanied by a written comment. The written comment is considered the
official comment and should include discussion of all points you wish
to make. EPA will generally not consider comments or comment contents
located outside of the primary submission (i.e., on the web, cloud, or
other file sharing system). For additional submission methods, please
contact the person identified in the FOR FURTHER INFORMATION CONTACT
section. For the full EPA public comment policy, information about CBI,
PBI, or multimedia submissions, and general guidance on making
effective comments, please visit <a href="https://www.epa.gov/dockets/commenting-epa-dockets">https://www.epa.gov/dockets/commenting-epa-dockets</a>.
FOR FURTHER INFORMATION CONTACT: Liz Selbst, Air and Radiation Division
(AR-18J), Environmental Protection Agency, Region 5, 77 West Jackson
Boulevard, Chicago, Illinois 60604, (312) 886-4746,
<a href="/cdn-cgi/l/email-protection#83f0e6efe1f0f7ade6efeaf9e2e1e6f7ebc3e6f3e2ade4ecf5"><span class="__cf_email__" data-cfemail="ea998f8688999ec48f8683908b888f9e82aa8f9a8bc48d859c">[email protected]</span></a>. The EPA Region 5 office is open from 8:30
a.m. to 4:30 p.m., Monday through Friday, excluding Federal holidays.
SUPPLEMENTARY INFORMATION: Throughout this document whenever ``we,''
``us,'' or ``our'' is used, we mean EPA.
I. Background
On June 22, 2010 (75 FR 35520), EPA published a revised primary
SO<INF>2</INF> NAAQS, establishing a new one-hour standard of 75 parts
per billion (ppb). On August 21, 2015 (80 FR 51052), EPA issued the
Data Requirements Rule (DRR), which required State air agencies to
characterize air quality around sources that emitted 2,000 tons per
year (tpy) or more of SO<INF>2</INF>.
[[Page 25969]]
EPA has identified the U.S. Mineral Wool facility, also known as
``Isolatek,'' as an emissions source that may have been contributing to
violations of the 2010 SO<INF>2</INF> NAAQS based on air quality
modeling conducted by EPA and used in support of the DRR. Isolatek is
located in the Huntington County, Indiana nonattainment area for the
2010 SO<INF>2</INF> NAAQS. EPA's air quality modeling, conducted in
2015 using estimated actual emissions from the Isolatek facility, found
that the 3-year average of the annual 99th percentile of daily maximum
one-hour average SO<INF>2</INF> concentrations exceeded the 75 ppb
level of the NAAQS. EPA's March 15, 2016, response to the initial
submittal of DRR sources from the Indiana Department of Environmental
Management (IDEM) is included in the docket for this rulemaking.
Evidence of IDEM's selection of the modeling pathway to characterize
air quality in the area surrounding the Isolatek facility on June 30,
2016, is also included in the docket for this rulemaking.
The Isolatek facility is the only listed DRR source in the
Huntington area and there is no approved SO<INF>2</INF> monitoring
network to characterize air quality in its vicinity. IDEM did not
include updated air quality information for the Huntington area in its
letter of designations recommendations for the 2010 SO<INF>2</INF>
NAAQS. Therefore, during the initial area designations process, EPA
relied on the prior EPA air quality modeling, which indicated that the
Huntington area may have been violating the 2010 SO<INF>2</INF> NAAQS,
and which led EPA to include Isolatek on the list of sources subject to
DRR requirements. On August 22, 2017, EPA notified IDEM that we
intended to designate the Huntington area as nonattainment, based on
the best information available to EPA at the time of designation, which
was EPA's air quality modeling indicating that the area may have been
violating the 2010 SO<INF>2</INF> NAAQS.
On January 9, 2018, EPA finalized the third round of initial area
designations for the 2010 SO<INF>2</INF> NAAQS. Based on prior air
quality modeling information, EPA designated Huntington Township, a
partial area of Huntington County, Indiana, which includes the Isolatek
facility, as nonattainment for the 2010 SO<INF>2</INF> NAAQS with an
effective date of April 9, 2018 (83 FR 1098). Pursuant to CAA section
192(a), 42 U.S.C. 7514a(a), EPA established an attainment date of no
later than five years after the effective date of the nonattainment
area designation, which was April 9, 2023.
II. Proposed Finding of Failure To Attain the 2010 One-Hour SO2 NAAQS
CAA section 179(c)(1) requires EPA to determine whether a
nonattainment area attained an ambient air quality standard by the
applicable attainment date based on the area's air quality as of the
attainment date. As stated in EPA's April 23, 2014, ``Guidance for 1-
Hour SO<INF>2</INF> Nonattainment Area SIP Submissions'' (``April 2014
SO<INF>2</INF> guidance''), EPA may consider ambient monitoring data,
air quality dispersion modeling, and/or a demonstration that the
control strategy in the SIP has been fully implemented when determining
the attainment status of SO<INF>2</INF> nonattainment areas.
Under EPA regulations in 40 CFR 50.17, the 2010 SO<INF>2</INF>
standard is met at a monitoring site (or in the case of dispersion
modeling, at an ambient air quality receptor location) when the three-
year average of the annual 99th percentile of daily maximum one-hour
average concentrations is less than or equal to 75 ppb, as determined
in accordance with appendix T of 40 CFR part 50 (40 CFR 50.17(a)-(b)).
Design values are calculated by computing the three-year average of the
annual 99th percentile daily maximum one-hour average concentrations.
When calculating one-hour primary standard design values based on
modeling, the modeled concentration is compared to the one-hour
SO<INF>2</INF> NAAQS of 196.4 micrograms per cubic meter. An
SO<INF>2</INF> one-hour primary standard design value is valid if it
encompasses three consecutive calendar years of complete monitoring
data or modeling data. See appendix T of 40 CFR part 50.
As of this action, and as of the statutory attainment date of April
9, 2023, there is no approved SO<INF>2</INF> monitoring network in the
Huntington area. The best air quality information available to EPA to
characterize air quality in the area on the attainment date was the air
quality modeling that was used to support the DRR. As part of the
State's SO<INF>2</INF> attainment plan for this area, IDEM submitted
control measures on November 6, 2023, that included enforceable
allowable emissions limits for the Isolatek facility (see Section III,
``Proposed Approval of Indiana's SIP Submittal,'' of this preamble for
discussion of the control strategy). On February 12, 2024, IDEM
supplemented the November 6, 2023, SIP submittal with Commissioner's
Order 2023-Air-02, which revised Commissioner's Order 2023-Air-01,
which had been included in the November 6, 2023, submittal. In this
notice of proposed rulemaking, we are referring to the updated Order
2023-Air-02 as the ``Commissioner's Order,'' which established
compliance requirements for the one-hour SO<INF>2</INF> emissions
limits, which were effective on March 1, 2024. In other words, the
control measures that EPA is proposing to approve in the following
section of this action were not in place as of the statutory attainment
date of April 9, 2023. Therefore, based on EPA's air quality modeling
used to support the DRR, EPA has determined that the area may have been
violating the 2010 SO<INF>2</INF> NAAQS prior to full implementation of
the control strategy. EPA is proposing to find that, as of the
applicable attainment date of April 9, 2023, the Huntington area failed
to attain the 2010 SO<INF>2</INF> NAAQS by the attainment date.
The consequences for an SO<INF>2</INF> nonattainment area that
fails to attain a NAAQS by the applicable attainment date are set forth
in CAA section 179(d). Under section 179(d), a State must submit a SIP
revision for the area meeting the requirements of CAA sections 110 and
172, the latter of which requires, among other elements, a
demonstration of attainment and reasonable further progress and
contingency measures. In addition, under CAA section 179(d)(2), the SIP
revision must include such additional measures as EPA may reasonably
prescribe, including all measures that can be feasibly implemented in
the area in light of technological achievability, costs, and any non-
air quality and other air quality-related health and environmental
impacts. The State is required to submit the SIP revision within one
year after EPA publishes a final action in the Federal Register
determining that the nonattainment area failed to attain the
SO<INF>2</INF> NAAQS.
In section III. of this preamble, EPA is proposing to approve
IDEM's revised SO<INF>2</INF> attainment plan for the Huntington area,
which was submitted to EPA on November 6, 2023, and supplemented on
February 15, 2024. (Both submittals occurred after the statutory
attainment date of April 9, 2023). The proposed approval is based on
air quality modeling demonstrating that the area is currently attaining
the NAAQS as a result of the implemented control measures in the
State's SIP and the compliance requirements established in the
Commissioner's Order. If EPA subsequently takes final action to approve
the subject SIP submittals, EPA is proposing to find that these SIP
revisions, as approved, satisfy the State's obligation under CAA
section 179(d) to submit a SIP revision to address the proposed finding
that the
[[Page 25970]]
area failed to timely attain the 2010 SO<INF>2</INF> NAAQS.
Under CAA sections 172(a)(2), 179(d)(3), the new attainment date
for each primary NAAQS nonattainment area is the date by which
attainment can be achieved as expeditiously as practicable, but no
later than five years after EPA publishes a final action in the Federal
Register determining that the nonattainment area failed to attain the
SO<INF>2</INF> NAAQS. In this action, we are proposing to approve
IDEM's SIP revision and proposing to find that the control measures
identified in IDEM's November 6, 2023, and February 15, 2024, SIP
revisions satisfy the CAA requirement to achieve attainment of the 2010
SO<INF>2</INF> NAAQS as expeditiously as practicable (see Section III).
Therefore, if the proposed Finding of Failure to Attain (FFA) is
finalized, this will establish a new attainment date for the
Huntington, IN area of no later than five years after the effective
date of the final FFA. However, in the following section, EPA is
proposing to approve Indiana's SIP and, if finalized, the approved SIP
would fulfill the new SIP submission requirement triggered by the
finalization of this FFA. We are proposing that the new SIP submission
requirement will be met by the SIP we are acting on below in this
unique circumstance because control measures are now in place and
effective, the area is attaining the 2010 primary SO<INF>2</INF> NAAQS,
and the State has submitted a complete and approvable attainment plan
with all required planning elements. The new attainment date
established 5 years after the date of the effective date of the final
FFA also requires contingency measures under CAA section 172(c)(9). EPA
is proposing to find that IDEM's comprehensive SO<INF>2</INF>
enforcement program, as described in Section III.D.5 of this preamble,
satisfies the CAA section 172(c) requirements for contingency measures.
III. Proposed Approval of Indiana's SIP Submittal
A. Indiana's Requirement To Submit a SIP Revision
On November 3, 2020 (85 FR 69504), EPA issued a finding that
Indiana had failed to submit a SIP provision to satisfy certain
nonattainment area planning requirements of the CAA for the 2010
SO<INF>2</INF> NAAQS. The effective date of the Finding of Failure to
Submit was December 3, 2020. Indiana was required to submit a SIP
provision in response to the Finding of Failure to Submit under CAA
section 179(a). This finding started a sanctions clock for EPA to issue
Nonattainment New Source Review (NNSR) sanctions and highway sanctions
for Huntington Township under CAA section 179(b). EPA imposed NNSR
offset sanctions that were effective on June 3, 2022, and imposed
highway sanctions that were effective on December 3, 2022. This action
also started a Federal Implementation Plan (FIP) clock for EPA to fully
approve an SO<INF>2</INF> attainment SIP, or issue a FIP, for the
Huntington, Indiana area within two years, by December 3, 2022, under
CAA section 110(c).
On November 6, 2023, IDEM submitted State rules for EPA approval as
revisions to the Indiana SIP intended to provide for attainment of the
2010 SO<INF>2</INF> NAAQS in the Huntington area. The revisions
included an Attainment Demonstration, Reasonably Available Control
Measures/Reasonably Available Control Technology (RACM/RACT)
requirements, Reasonable Further Progress (RFP) provisions, Contingency
Measures, Emissions Inventories for 2017 Base Year and 2023 Attainment
Year, and NNSR Certification. On November 27, 2023, EPA issued a
completeness determination for the November 6, 2023, SIP submittal,
which terminated all sanctions for this area and which is available in
the docket for this rulemaking. On February 15, 2024, IDEM submitted a
supplemental SIP revision including updated compliance methods
(contained in the revised Commissioner's Order 2023-Air-02, as
previously described in this action) for the Attainment Demonstration
for the Huntington, Indiana SO<INF>2</INF> nonattainment area. In this
notice of proposed rulemaking, EPA is proposing to find that this
supplement satisfies the CAA sections 110(a)(2)(A) and 172(c)(6)
requirements to provide enforceable emissions limitations and control
measures as part of an attainment demonstration. As mentioned in the
previous section, under CAA section 179(d), States must submit a SIP
provision within one year of EPA publishing a finding of failure to
attain by the attainment date for any nonattainment area. The
submission must include a demonstration of attainment, reasonable
further progress and contingency measures, and other measures EPA may
reasonably prescribe. Assuming EPA finalizes the proposed finding of
failure to attain and the proposed approval of Indiana's SIP
submissions, EPA is also proposing to find that IDEM's November 6,
2023, and February 15, 2024, SIP submissions fully satisfy the State's
obligation under CAA section 179(d). Lastly, EPA is proposing to
terminate the FIP clock that was triggered by EPA's November 3, 2020,
Finding of Failure to Submit for Huntington County.
B. Requirements for SO2 Nonattainment Area Plans
Nonattainment area SO<INF>2</INF> SIPs must meet the applicable
requirements of the CAA, and specifically CAA sections 110, 172, 191
and 192. EPA's regulations governing nonattainment area SIPs are set
forth at 40 CFR part 51, with specific procedural requirements and
control strategy requirements contained in subparts F and G,
respectively. Soon after Congress enacted the 1990 amendments to the
CAA, EPA issued comprehensive guidance on SIPs in a document entitled
the ``General Preamble for the Implementation of Title I of the Clean
Air Act Amendments of 1990,'' published at 57 FR 13498 (April 16, 1992)
(General Preamble). Among other things, the General Preamble addressed
SO<INF>2</INF> SIPs and fundamental principles for SIP control
strategies. Id. at 13545-49, 13567-68.
In the April 2014 SO<INF>2</INF> guidance, EPA described the
statutory requirements for a complete nonattainment area SIP, which
include: an accurate emissions inventory of current emissions for all
sources of SO<INF>2</INF> within the nonattainment area; an attainment
demonstration; enforceable emissions limitations and control measures;
demonstration of RFP; implementation of RACM (including RACT); NNSR
provisions; and adequate contingency measures for the affected area.
In order for EPA to fully approve a SIP as meeting the requirements
of CAA sections 110, 172 and 191-192 and EPA's regulations at 40 CFR
part 51, the SIP for the affected area needs to demonstrate to EPA's
satisfaction that each of the aforementioned requirements have been
met. Under CAA section 110(l) EPA may not approve a SIP that would
interfere with any applicable requirement concerning NAAQS attainment
and RFP, or any other applicable requirement; and, under section 193,
no control requirement in effect (or required to be adopted by an
order, settlement, agreement, or plan in effect before November 15,
1990), in any area which is a nonattainment area for any air pollutant,
may be modified in any manner unless the modification ensures
equivalent or greater emission reductions of such air pollutant.
C. Review of Modeled Attainment Plan
This section describes EPA's evaluation of the air quality
dispersion modeling IDEM provided as part of its SIP submission. EPA is
proposing to
[[Page 25971]]
approve Indiana's attainment plan on the basis that this modeling is
technically sound and appropriate and provides for attainment of the
2010 SO<INF>2</INF> NAAQS.
1. Model Selection and General Model Inputs
IDEM followed EPA guidance at 40 CFR part 51, appendix W, and
selected EPA's regulatory dispersion model, AERMOD, to model
SO<INF>2</INF> emissions impacts in the Huntington, Indiana
nonattainment area. IDEM used the set of regulatory default options in
AERMOD version 22112 to develop the attainment demonstration discussed
in this section. Version 22112 was the current version of AERMOD at the
time the air quality modeling report was submitted (October 6, 2023) as
part of the attainment demonstration (see section 5.0 and appendix A1
of the attainment demonstration) and the most recent update to AERMOD
since then did not include any bug fixes or other model code changes
that would impact the modeled concentrations in the modeled attainment.
AERMOD was conducted with the use of rural dispersion coefficients,
based on a land use analysis of a 3-kilometer radius from the Isolatek
facility showing that only 17.2% of the nearby land was classified as
urban. IDEM used an appropriate downwash algorithm for stacks that did
not meet EPA's Good Engineering Practice (GEP) stack height policy,
which is further described in this section. This is consistent with
established practice for use of AERMOD in determining NAAQS compliance
for SIP revisions. EPA proposes to find that selection of the default
AERMOD options and use of the rural dispersion coefficient are both
technically appropriate.
IDEM's attainment demonstration uses a modeling domain reflecting
the geographic extent of the Huntington nonattainment area. The
Thermafiber, Paperworks, and Real Alloy facilities in Wabash County,
the Steel Dynamics facility in Whitely County, the FXI facility in
Allen County, and the Teijin Automotive Technologies facility within
the Huntington nonattainment area were explicitly modeled as nearby
sources in the modeling demonstration. The Teijin Automotive
Technologies facility is located 5.6 kilometers from Isolatek. The rest
of the nearby sources explicitly modeled in the attainment
demonstration are located 27-37 kilometers away from the Isolatek
facility. Nearby sources, though not evaluated for an emission limit,
are those sources in the vicinity of the source(s) under consideration
for emissions limits that are not adequately represented by ambient
monitoring data. Consistent with EPA's DRR modeling for the Huntington
area, IDEM determined that the primary source of SO<INF>2</INF>
emissions in the area is the Isolatek facility, which is the primary
source of violations of the 2010 SO<INF>2</INF> NAAQS in the
nonattainment area. EPA's evaluation of IDEM's modeling of the Isolatek
source is discussed further in Section III.C.3-4 of this preamble.
The receptor network fully encompasses the Huntington nonattainment
area. IDEM used four nested receptor grids with different densities and
included a fenceline receptor grid with 50-meter spacing. The fine
Cartesian grid contains receptors spaced at 100-meter intervals
extending to approximately three kilometers away from the center of the
facility. The extended fine Cartesian grid contains receptors spaced at
250-meter intervals starting approximately three kilometers away from
the center of the facility and extend to five kilometers away from the
center of the facility. The medium Cartesian grid contains receptors
spaced at 500-meter intervals starting approximately five kilometers
away from the center of the facility and extend to ten kilometers away
from the center of the facility. The coarse Cartesian grid contains
receptors spaced at 750-meter intervals starting approximately ten
kilometers away from the center of the facility and extend to twenty
kilometers away from the center of the facility. The receptors
projected to have maximum modeled concentrations were all contained
within the 100-meter spacing fine receptor grid. EPA proposes to find
that the receptor density is consistent with standard modeling guidance
for adequately capturing and resolving SO<INF>2</INF> concentration
maxima.
IDEM's selection of terrain data corresponds to the geographic area
represented by the Huntington Township nonattainment area, as well as
the locations of nearby facilities influencing SO<INF>2</INF>
concentrations in the area. U.S. Geological Survey (USGS) National
Elevation Dataset (NED) data were obtained in an appropriate format for
use in AERMAP (version 18081) and used for generating the necessary
terrain inputs. Elevations from the NED data were determined for all
sources and structures, and both elevations and representative hill
heights were determined for receptors. EPA proposes to find that these
selections are technically appropriate and consistent with established
practice in determining NAAQS compliance for SIP revisions.
EPA's appendix W guidance requires States to evaluate whether
physical structures may affect the dispersion of emissions from stack
sources. Stacks that are constructed to heights lower than specified
GEP height and within the ``zone of influence'' of a nearby structure
have plumes that are potentially subject to the effects of downwash
which would affect dispersion and modeled concentrations in the
building wake, near to the source. IDEM used EPA's Building Profile
Input Program with PRIME algorithm (BPIPPRM) to generate direction-
specific building parameters for modeling building wake effects. The
location and height of each stack and flare to be evaluated, and the
locations and heights of nearby structures, were processed in BPIPPRM
(version 04274) to produce the building downwash parameters required by
AERMOD. The actual release heights of all stacks were less than the
calculated GEP value. Therefore, all stacks at the Isolatek facility
were modeled at their actual release heights and were subject to
downwash effects. EPA is proposing to determine that IDEM's application
of the modeling guidance is appropriate for addressing stacks subject
to downwash effects.
2. Meteorological Data
Procedures for selecting and developing meteorological data have
been provided in appendix W, as well as in the document ``Regional
Meteorological Data Processing Protocol, EPA Region 5 and States,''
which is available in the docket for this action. These documents
describe selection criteria for surface meteorological data that
address the representativeness of the meteorological data collection
site to the emission source/receptor impact area. There are two
specific criteria to be considered: (1) the suitability of
meteorological data for the study area, and (2) the similarity of
surface conditions and surroundings at the emission source/receptor
impact area compared to surface characteristics at the location of the
meteorological instrumentation tower.
IDEM used five years of surface meteorological data from the Fort
Wayne National Weather Service (NWS) and upper air meteorological data
from Wilmington, Ohio for the period of 2017-2021. This data set was
determined to be representative of the nonattainment area's airshed and
was the most current data set available when the modeling analysis was
conducted. IDEM pre-processes meteorological data and provides the
datasets for modeling
[[Page 25972]]
applicants on their website.\1\ AERMINUTE (version 15272) was used to
process two-minute averaged ASOS (Automated Surface Observing System)
wind data (reported every minute) from Fort Wayne and used the EPA
recommended 0.5 meters per second calm wind threshold. Surface
characteristic data such as albedo, Bowen ratio, and surface roughness
were calculated using the non-regulatory surface characteristics
preprocessor AERSURFACE. The one-minute ASOS wind data and surface
characteristics were processed together with the surface and upper air
meteorological data using AERMET (version 19191 for the years 2017-2020
and version 21112 for the year 2021) to prepare the meteorological data
for input into AERMOD. Two different versions of AERMET were used as
the 2017-2020 data set was previously processed by IDEM when the year
2021 was processed and the differences between AERMET versions 19191
and 21112 would not have resulted in significant changes in
meteorological parameters. The Fort Wayne NWS wind rose shows the
frequency of the wind direction every ten degrees for each of the wind
speed ranges for the five-year modeled period and demonstrates that the
prevailing winds are from the southwest and west-southwest at the Fort
Wayne NWS station. EPA proposes to find that the meteorological data
set IDEM selected for the air quality modeling to support its SIP
submission was technically appropriate.
---------------------------------------------------------------------------
\1\ <a href="https://www.in.gov/idem/airquality/modeling/air-dispersion-meteorological-data/">https://www.in.gov/idem/airquality/modeling/air-dispersion-meteorological-data/</a>.
---------------------------------------------------------------------------
3. Emissions Limits and Modeled Emissions Data
As EPA identified at the time of promulgating the DRR, the primary
source affecting nonattainment and contributing to violations of the
2010 SO<INF>2</INF> NAAQS in Huntington County was the Isolatek
facility. EPA has not identified any other sources in the area that may
have been contributing to violations of the 2010 SO<INF>2</INF> NAAQS.
IDEM's SIP submission establishes permanent and enforceable emissions
limits for this facility through a Commissioner's Order. IDEM reviewed
detailed engineering analyses for multiple control options at the
Isolatek facility, as described in section 5.8 of the SIP submittal.
Construction for the control measures selected at the facility,
including increasing the cupola stack height, enclosing screenhouses,
and building a new elevated stack, was completed in November 2022. Data
from stack testing conducted in December 2022 and January 2023 were
used to establish the emission limits necessary to provide for
attainment of the 2010 one-hour SO<INF>2</INF> NAAQS. The attainment
demonstration incorporates hourly modeled emission rate limits,
contained in the Commissioner's Order, of 160.0 pounds per hour (lbs/
hr) for Cupola units EU #1 and EU #2, exhausting to shared Stack #1,
and 20.0 lbs/hr for blow chambers EU #3 and EU #4, exhausting to Screen
Houses CE #3 and CE #4, which exhaust to Stack #3 at the Isolatek
facility.
IDEM's modeled demonstration of attainment of the 2010
SO<INF>2</INF> NAAQS relies on Isolatek meeting the one-hour
SO<INF>2</INF> emissions limit established in the Commissioner's Order.
For EPA to approve an attainment plan that relies on establishing
emissions limits, EPA must determine that the limits are quantifiable,
fully enforceable, replicable, and accountable. See General Preamble at
13567-68. IDEM's February 6, 2024, SIP submission includes an IDEM
Commissioner's Order that establishes a compliance date of March 1,
2024, for the emissions limits included in the revised SIP. In addition
to requiring compliance with the hourly SO<INF>2</INF> emissions limits
and defining stack testing parameters, this order also specifies that
Isolatek must incorporate reporting and recordkeeping requirements into
its part 70 Operating Permit within 90 days of EPA's approval of the
SIP submission. Isolatek must report monthly average hourly
SO<INF>2</INF> emissions from Cupola #1 and Cupola #2 and monthly
average hourly SO<INF>2</INF> emissions from Blow Chamber #3 and Blow
Chamber #4 on a quarterly basis to IDEM and must report any exceedances
of the SO<INF>2</INF> emissions limits. Based on these requirements,
EPA is proposing to find that the emissions limits in IDEM's SIP
revision will become permanent and enforceable upon EPA's approval of
the SIP submission.
Using the source-specific one-hour average emissions rates for
Isolatek that are established in the SIP submission, IDEM demonstrated
that the highest 4th high one-hour maximum daily SO<INF>2</INF>
concentration, averaged across five years for the entire area defined
by the receptor grid, is 195.9 micrograms per cubic meter and occurred
approximately 175 meters northeast of the fenceline receptor grid. As
the maximum modeled concentrations occurred within a one kilometer
radius of Isolatek, receptors were not placed inside the fencelines of
the other explicitly modeled nearby sources to determine the ambient
impacts from Isolatek. Based on this modeling, EPA proposes to conclude
that the permanent and enforceable emission limits for Isolatek provide
for attainment of the 2010 SO<INF>2</INF> NAAQS of 75 ppb (or 196.4
micrograms per cubic meter) in the Huntington nonattainment area.
4. Background Concentrations
IDEM's demonstration providing for modeled attainment of the 2010
SO<INF>2</INF> NAAQS is based on a combination of facility-specific
emission rates and monitored background concentrations. Regional
sources not explicitly modeled in AERMOD, but which contribute to
ambient SO<INF>2</INF> loadings within the nonattainment area, are
represented via background monitoring data. IDEM identified background
concentration estimates from the Lima, Ohio monitor as the most
representative site in the vicinity of the modeling domain. The Lima,
OH SO<INF>2</INF> monitor is located approximately 74 miles east-
southeast of Isolatek and is the closest monitor within the region. The
hour-by-season averaged SO<INF>2</INF> background values for 2019-2021
at this monitor range from 0.33 ppb to 1.33 ppb. EPA proposes to
conclude that the background concentrations used in IDEM's modeled
attainment demonstration are appropriate and consistent with EPA
modeling guidance.
5. Summary of Results
EPA's DRR modeling indicated that the Isolatek facility was
contributing to violations of the 2010 SO<INF>2</INF> NAAQS in the
Huntington area. IDEM evaluated control options for the nonattainment
area and established emissions limits for the Isolatek facility.
Construction of the relevant control projects was completed in November
2022, with a compliance date to codify the emissions limits as
permanent and enforceable on March 1, 2024. IDEM's modeling
demonstrated that the one-hour average hourly SO<INF>2</INF> emissions
limits contained in the SIP revision yielded a highest 4th high one-
hour daily maximum SO<INF>2</INF> concentration of 195.9 micrograms per
cubic meter which is below the 2010 SO<INF>2</INF> NAAQS level of 196.4
micrograms per cubic meter.
EPA is proposing to conclude that IDEM's modeling is a technically
sound demonstration that the Isolatek facility, as the primary source
contributing to violations of the 2010 SO<INF>2</INF> NAAQS, has been
properly addressed in the State's attainment plan. EPA proposes to find
that IDEM's modeling appropriately provides for attainment of the 2010
SO<INF>2</INF> NAAQS.
[[Page 25973]]
D. Review of Other Plan Requirements
1. Emissions Inventory
CAA section 172(c)(3) requires States to provide a comprehensive,
accurate, and current inventory of actual emissions from all sources of
SO<INF>2</INF> in the nonattainment area, as well as any sources
located outside the nonattainment area which may affect attainment in
the area. The emissions inventory and source emission rate data for an
area serve as the foundation for air quality modeling and other
analyses that enable States to: (1) estimate the degree to which
different sources within a nonattainment area contribute to violations
within the affected area; and (2) assess the prospects for attaining
the standard based on alternative control measures. EPA's April 2014
SO<INF>2</INF> Guidance includes requirements for submitting emissions
inventories that are representative of base year conditions and a
projection to the attainment year.
IDEM provided a comprehensive, accurate, and current inventory of
emissions of SO<INF>2</INF> in Huntington County. The 2017 base year
inventory was developed using data from the National Emissions
Inventory (NEI) and included point sources, nonpoint sources, non-road
mobile sources, and on-road mobile sources. County level emissions data
are summarized in Table 1 for the 2017 base year. The data indicate the
largest contribution to SO<INF>2</INF> emissions in the nonattainment
area is from non-EGU point sources. IDEM compiled actual SO<INF>2</INF>
emissions, as reported, shown in Table 2, from the two non-EGU point
sources in Huntington County. Isolatek reports annual emissions to
IDEM; Teijin Automotive Technologies reports to IDEM on a triennial
basis. IDEM did not find evidence of any other large sources near the
nonattainment area that may have been impacting air quality in the
Huntington area. EPA is proposing to determine that IDEM's list of
sources with potential to cause nonattainment of the NAAQS is thorough
and complete.
Table 1--Huntington County SO2 Emissions Data by Sector for 2017
------------------------------------------------------------------------
Huntington Huntington
County Township
Sector Emissions Emissions
(tons per (tons per
year) year)
------------------------------------------------------------------------
On-road................................. 4.48 0.07
Non-road................................ 0.75 0.42
Area.................................... 10.81 6.05
Point EGU............................... 0.00 0.00
Point Non-EGU........................... 176.23 176.23
Total................................... 192.27 182.77
------------------------------------------------------------------------
Table 2--Actual Reported SO2 Emissions From Non-EGU Point Sources in
Huntington County, 2011-2020
------------------------------------------------------------------------
Actual (Reported) SO2
emissions (tpy) by Facility
-------------------------------
Year Teijin
Isolatek Automotive
Technologies
------------------------------------------------------------------------
2011.................................... 219.89 ..............
2012.................................... 224.3 ..............
2013.................................... 176.14 0.026
2014.................................... 164.36 ..............
2015.................................... 180.53 0.03
2016.................................... 184.21 ..............
2017.................................... 176.2 ..............
2018.................................... 192.88 0.03
2019.................................... 188.29 ..............
2020.................................... 181.33 ..............
------------------------------------------------------------------------
IDEM's projected emissions for the 2023 attainment year are based
on the attainment modeling described previously in this notice in
Section III.C. As noted in EPA's evaluation of the attainment modeling
demonstration, the source emission rate data for Isolatek is calculated
by the maximum allowable hourly emissions limit established in the SIP
revision. Projected county level emissions data by sector are
summarized in Table 3 for the 2023 attainment year.
Table 3--Projected Huntington County SO2 Emissions Data by Sector for
2023
------------------------------------------------------------------------
Huntington
County
Sector Emissions
(tons per
year)
------------------------------------------------------------------------
On-road................................................. 0.05
Non-road................................................ 0.24
Area.................................................... 3.41
Point EGU............................................... 0.00
Point Non-EGU........................................... 788.43
Total................................................... 792.13
------------------------------------------------------------------------
2. RACM/RACT and Emissions Limitations and Control Measures
Section 172(c)(1) of the CAA requires States to adopt and submit
all RACM, including RACT, as needed to attain the standards as
expeditiously as practicable. Section 172(c)(6) requires the SIP to
contain enforceable emission limits and control measures necessary to
provide for timely attainment of the standard.
The Isolatek facility, identified by EPA as the largest source of
SO<INF>2</INF> emissions contributing to violations of the 2010
SO<INF>2</INF> NAAQS in Huntington, Indiana, was required by the State
to increase the height of its stack, enclose
[[Page 25974]]
screenhouses, and build a new elevated stack. These emissions control
projects were completed in November 2022. Together with the permanent
and enforceable hourly average emissions limits in IDEM's
Commissioner's Order, EPA is proposing to find that the control
measures implemented at the Isolatek facility provide for attainment of
the 2010 SO<INF>2</INF> NAAQS. Because CAA section 172(c) does not
require the State to impose emissions control measures for
SO<INF>2</INF> nonattainment areas beyond the emissions reductions
necessary to provide for attainment, EPA is proposing to find that the
control measures implemented at the Isolatek facility satisfy the
requirements of CAA section 172(c)(1) to reduce emissions from existing
sources in the area as expeditiously as practicable. EPA is proposing
to determine that the State's plan satisfies the applicable CAA
requirements for RACM and RACT.
3. Nonattainment New Source Review (NNSR)
EPA approved Indiana's NNSR rules on October 7, 1994 (94 FR 24837).
These rules, which are contained in the SIP, provide for review of
SO<INF>2</INF> sources undergoing construction or major modification in
nonattainment areas such as the Huntington Township area. Although
these rules predated promulgation of the 2010 SO<INF>2</INF> standard,
they are written in a manner such that new sources within areas that
become designated nonattainment for the new standard, such as the
Huntington Township area, become subject to these nonattainment new
source review requirements. Therefore, EPA is proposing to determine
that this CAA requirement has been met for this area.
4. RFP
CAA section 172(c)(2) requires Indiana's SO<INF>2</INF> Attainment
Plan SIP for Huntington, Indiana to provide for reasonable further
progress toward attainment. For SO<INF>2</INF> SIPs, which address a
small number of affected sources, requiring expeditious compliance with
attainment emission limits can address the RFP requirement. Isolatek
completed construction of the new stack and other emissions control
projects by November 2022. Furthermore, Isolatek was required by the
Commissioner's Order to comply with enforceable and permanent control
measures by March 1, 2024.
In this action, EPA is proposing to approve the hourly average
SO<INF>2</INF> emissions limits that Isolatek was required to comply
with, per the Commissioner's Order, into Indiana's SIP as permanent and
enforceable. EPA is proposing to conclude that the requirements in the
State's plan, including establishing hourly SO<INF>2</INF> emission
limits for the Isolatek facility, represent implementation of control
measures as expeditiously as practicable. This plan provides for
attainment of the 2010 SO<INF>2</INF> NAAQS. Accordingly, EPA proposes
to find that IDEM's plan provides for RFP.
5. Contingency Measures
Section 172(c)(9) of the CAA requires that nonattainment plans
include additional measures which will take effect if an area fails to
meet RFP or fails to attain the standard by the attainment date. As
noted previously, EPA guidance describes special features of
SO<INF>2</INF> planning that influence the suitability of alternative
means of addressing the requirement in CAA section 172(c)(9) for
contingency measures for SO<INF>2</INF>. An appropriate means of
satisfying this requirement for SO<INF>2</INF> nonattainment area
planning is for the State to have a comprehensive SO<INF>2</INF>
enforcement program that identifies sources of violations of the
SO<INF>2</INF> NAAQS and for the State to undertake aggressive follow-
up for compliance and enforcement. IDEM's plan provides for satisfying
the contingency measure requirement in this manner for sources in the
State. IDEM provided example measures that may be considered if
enforcement of violations of the NAAQS is required, such as requiring
alternative fuels, requiring installation of additional control
technologies, or requiring the source to reduce operating hours. EPA is
proposing to concur with this approach and proposes to approve IDEM's
plan for meeting the contingency measures requirement in this manner.
IV. What action is EPA proposing?
EPA is proposing to find, under section 179 of the CAA, that the
Huntington County, Indiana nonattainment area failed to attain the 2010
SO<INF>2</INF> NAAQS by the applicable attainment date of April 9,
2023, and that Indiana is therefore subject to the requirement under
section 179 to submit a revision to its SIP to provide for attainment
in that area no later than five years from the date of any final
determination that the area failed to attain. See section 179(c)-(d).
EPA is also proposing to approve Indiana's November 6, 2023, SIP
attainment plan submittal and February 15, 2024, supplemental SIP
revision for the Huntington County SO<INF>2</INF> nonattainment area as
fulfilling this requirement to provide for attainment of the 2010
SO<INF>2</INF> NAAQS by the attainment date, in this unique
circumstance because control measures are now in place and effective,
the area is attaining the 2010 SO<INF>2</INF> NAAQS, and the State has
submitted a complete and approvable attainment plan with all required
planning elements. EPA is proposing to determine that IDEM has
appropriately demonstrated that the plan provides for attainment of the
2010 SO<INF>2</INF> NAAQS in the Huntington County, Indiana
nonattainment area and that the plan meets the other applicable
requirements under CAA sections 172, 191, and 192. The proposed
approval of IDEM's SO<INF>2</INF> attainment plan, if finalized, would
also terminate the FIP clock that was triggered by EPA's November 3,
2020, Finding of Failure to Submit for the Huntington County area. EPA
is soliciting public comments for 30 days following the publication of
this proposed action in the Federal Register and will take these
comments into consideration in our final action.
V. 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, 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);
[[Page 25975]]
<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 EPA or an Indian Tribe has
demonstrated that a Tribe has jurisdiction. In those areas of Indian
country, the rulemaking does not have Tribal implications and will not
impose substantial direct costs on Tribal governments or preempt Tribal
law as specified by Executive Order 13175 (65 FR 67249, November 9,
2000).
List of Subjects in 40 CFR Part 52
Environmental protection, Air pollution control, Incorporation by
reference, Intergovernmental relations, Reporting and recordkeeping
requirements, Sulfur oxides.
Dated: June 9, 2025.
Anne Vogel,
Regional Administrator, Region 5.
[FR Doc. 2025-11268 Filed 6-17-25; 8:45 am]
BILLING CODE 6560-50-P
</pre><script data-cfasync="false" src="/cdn-cgi/scripts/5c5dd728/cloudflare-static/email-decode.min.js"></script></body>
</html>Indexed from Federal Register on June 18, 2025.
This is legal information, not legal advice. Laws vary by jurisdiction and change frequently. Always verify current law with official sources and consult a licensed attorney in your jurisdiction for advice on your specific situation.