Document ID: EPA-R07-OAR-2017-0416-0001
Agency: epa
Document Type: Proposed Rule
Title: Approval of Iowa’s Air Quality Implementation Plan;  Muscatine Sulfur Dioxide Nonattainment Area
Posted Date: 2017-08-24T04:00Z

[Federal Register Volume 82, Number 163 (Thursday, August 24, 2017)]
[Proposed Rules]
[Pages 40086-40103]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2017-17736]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R07-OAR-2017-0416; FRL-9966-60-Region 7]

Approval of Iowa's Air Quality Implementation Plan; Muscatine 
Sulfur Dioxide Nonattainment Area

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to 
approve the State Implementation Plan (SIP) revision, which the State 
of Iowa (the state) submitted to the EPA on May 26, 2016, for attaining 
the 1-hour sulfur dioxide (SO2) primary National Ambient Air 
Quality Standard (NAAQS) for the Muscatine nonattainment area. This 
plan (herein called a ``nonattainment plan'') includes the state's 
attainment demonstration and other elements required under Clean Air 
Act (CAA) sections 172, 191, and 192. In addition to an attainment 
demonstration, the plan addresses the requirement for meeting 
reasonable further progress (RFP) toward attainment of the NAAQS, 
reasonably available control measures and reasonably available control 
technology (RACM/RACT), base-year and projection-year emission 
inventories, and contingency measures. The EPA proposes to conclude 
that the state has appropriately demonstrated that the plan provisions 
provide for attainment of the 2010 1-hour primary SO2 NAAQS 
in the Muscatine nonattainment area by the applicable attainment date 
and that the plan meets the other applicable requirements under CAA 
sections 172, 191, and 192.

DATES: Comments must be received on or before September 25, 2017.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R07-
OAR-2017-0416 to https://www.regulations.gov. Follow the online 
instructions for submitting comments. Once submitted, comments cannot 
be edited or removed from Regulations.gov. 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 https://www2.epa.gov/dockets/commenting-epa-dockets.

FOR FURTHER INFORMATION CONTACT: Tracey Casburn, Environmental 
Protection Agency, Air Planning and Development Branch, 11201 Renner 
Boulevard, Lenexa, Kansas 66219 at (913) 551-7016, or by email at 
casburn.tracey@epa.gov.

SUPPLEMENTARY INFORMATION: Throughout this document whenever ``we,'' 
``us,'' and ``our'' is used, we mean the EPA.
    Organization of this document. The following outline is provided to 
aid in locating information in this preamble.

Table of Contents

I. Why was Iowa required to submit an SO2 plan for the 
Muscatine area?
II. Requirements for SO2 Nonattainment Area Plans
III. Attainment Demonstration and Longer Term Averaging
IV. Review of Modeled Attainment Plan
    A. Model Selection
    B. Meteorological Data
    C. Emissions Data
    D. Emission Limits
    1. Enforceability
    2. Longer Term Averaging
    E. Background Concentrations
    F. Summary of Results
    1. Phase 1--Preliminary Analysis
    2. Phase 2--Control Strategy Development
V. Review of Other Plan Requirements
    A. Emissions Inventory and the Quantification of Emissions
    B. RACM/RACT

[[Page 40087]]

    C. Nonattainment New Source Review (NNSR)
    D. Reasonable Further Progress (RFP)
    E. Contingency Measures
VI. Additional Elements of the State's Submittal
    A. Compliance With Section 110(a)(2) of the CAA
    B. Equivalent Techniques
VII. EPA's Proposed Action
VIII. Incorporation by Reference
IX. Statutory and Executive Order Reviews

I. Why was Iowa required to submit an SO2 plan for the 
Muscatine area?

    On June 22, 2010, the EPA promulgated a new 1-hour primary 
SO2 NAAQS of 75 parts per billion (ppb), which is met at an 
ambient air quality monitoring site when the 3-year average of the 
annual 99th percentile of 1-hour daily maximum concentrations does not 
exceed 75 ppb, as determined in accordance with appendix T of 40 CFR 
part 50. See 75 FR 35520, codified at 40 CFR 50.17(a)-(b). On August 5, 
2013, the EPA designated 29 areas of the country as nonattainment for 
the 2010 SO2 NAAQS, including the Muscatine area in the 
State of Iowa. See 78 FR 47191, codified at 40 CFR part 81, subpart C. 
These area designations were effective October 4, 2013. Section 191 of 
the CAA directs states to submit SIPs for areas designated as 
nonattainment for the SO2 NAAQS to the EPA within 18 months 
of the effective date of the designation, i.e., by no later than April 
4, 2015. These SIPs must demonstrate that the respective areas will 
attain the NAAQS as expeditiously as practicable, but no later than 5 
years from the effective date of designation, which is October 4, 2018.
    On March 18, 2016, the EPA published an action that the State of 
Iowa failed to submit the required SO2 nonattainment plan 
for the Muscatine area by the SIP submittal deadline. See 81 FR 14736. 
This finding initiated a deadline under CAA section 179(a) for the 
potential imposition of new source and highway funding sanctions. 
However, pursuant to Iowa's submittal of May 26, 2016, and the SIP 
becoming complete by operation of law on November 26, 2016, the 
sanctions under section 179(a) will not be imposed. Additionally, under 
CAA section 110(c), the finding triggers a requirement that the EPA 
promulgate a Federal Implementation Plan (FIP) within two years of the 
finding unless, by that time (a) the state has made the necessary 
complete submittal and (b) EPA has approved the submittal as meeting 
applicable requirements. This FIP obligation will not apply if EPA 
makes final the approval action proposed here by March 18, 2018.
    The remainder of this preamble describes the requirements that 
nonattainment SIPs must meet in order to obtain EPA approval, provides 
a review of the state's plan with respect to these requirements, and 
describes the EPA's proposed action on the plan.

II. Requirements for SO2 Nonattainment Area Plans

    Nonattainment SIPs must meet the applicable requirements of the 
CAA, and specifically CAA sections 172, 191 and 192. The EPA's 
regulations governing nonattainment SIPs are set forth at 40 CFR part 
51, with specific procedural requirements and control strategy 
requirements residing at 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 
SO2 SIPs and fundamental principles for SIP control 
strategies. Id., at 13545-49, 13567-68. On April 23, 2014, the EPA 
issued recommended guidance for meeting the statutory requirements in 
SO2 SIPs, in a document entitled, ``Guidance for 1-Hour 
SO2 Nonattainment Area SIP Submissions,'' (April 2014 
guidance) available at https://www.epa.gov/sites/production/files/2016-06/documents/20140423guidance_nonattainment_sip.pdf. In this guidance 
the EPA described the statutory requirements for a complete 
nonattainment area SIP, which includes: An accurate emissions inventory 
of current emissions for all sources of SO2 within the 
nonattainment area; an attainment demonstration; demonstration of RFP; 
implementation of RACM (including RACT); new source review (NSR) and, 
adequate contingency measures for the affected area.
    In order for the 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 sections 110(l) and 193, the EPA may not approve a 
SIP that would interfere with any applicable requirement concerning 
NAAQS attainment and RFP, or any other applicable requirement, and no 
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 it insures equivalent or greater emission 
reductions of such air pollutant.

III. Attainment Demonstration and Longer Term Averaging

    CAA section 172(c)(1) directs states with areas designated as 
nonattainment to demonstrate that the submitted plan provides for 
attainment of the NAAQS. 40 CFR part 51, subpart G further delineates 
the control strategy requirements that SIPs must meet, and EPA has long 
required that all SIPs and control strategies reflect four fundamental 
principles of quantification, enforceability, replicability, and 
accountability. General Preamble, at 13567-68. SO2 
attainment plans must consist of two components: (1) Emission limits 
and other control measures that assure implementation of permanent, 
enforceable and necessary emission controls, and (2) a modeling 
analysis which meets the requirements of 40 CFR part 51, appendix W 
which demonstrates that these emission limits and control measures 
provide for timely attainment of the primary SO2 NAAQS as 
expeditiously as practicable, but by no later than the attainment date 
for the affected area. In all cases, the emission limits and control 
measures must be accompanied by appropriate methods and conditions to 
determine compliance with the respective emission limits and control 
measures and must be quantifiable (i.e., a specific amount of emission 
reduction can be ascribed to the measures), fully enforceable 
(specifying clear, unambiguous and measureable requirements for which 
compliance can be practicably determined), replicable (the procedures 
for determining compliance are sufficiently specific and non-subjective 
so that two independent entities applying the procedures would obtain 
the same result), and accountable (source specific limits must be 
permanent and must reflect the assumptions used in the SIP 
demonstrations).
    The EPA's April 2014 guidance recommends that the emission limits 
be expressed as short-term average limits (e.g., addressing emissions 
averaged over one or three hours), but also describes the option to 
utilize emission limits with longer averaging times of up to 30 days so 
long as the state meets various suggested criteria. See 2014 guidance, 
pp. 22 to 39. The guidance recommends that--should states and sources 
utilize longer averaging times--

[[Page 40088]]

the longer term average limit should be set at an adjusted level that 
reflects a stringency comparable to the 1-hour average limit at the 
critical emission value shown to provide for attainment that the plan 
otherwise would have set.
    The April 2014 guidance provides an extensive discussion of the 
EPA's rationale for concluding that appropriately set comparably 
stringent limitations based on averaging times as long as 30 days can 
be found to provide for attainment of the 2010 SO2 NAAQS. In 
evaluating this option, the EPA considered the nature of the standard, 
conducted detailed analyses of the impact of use of 30-day average 
limits on the prospects for attaining the standard, and carefully 
reviewed how best to achieve an appropriate balance among the various 
factors that warrant consideration in judging whether a state's plan 
provides for attainment. Id. at pp. 22 to 39. See also id. at 
Appendices B, C, and D.
    As specified in 40 CFR 50.17(b), the 1-hour primary SO2 
NAAQS is met at an ambient air quality monitoring site when the 3-year 
average of the annual 99th percentile of daily maximum 1-hour 
concentrations is less than or equal to 75 parts per billion. In a year 
with 365 days of valid monitoring data, the 99th percentile would be 
the fourth highest daily maximum 1-hour value. The 2010 SO2 
NAAQS, including this form of determining compliance with the standard, 
was upheld by the U.S. Court of Appeals for the District of Columbia 
Circuit in Nat'l Envt'l Dev. Ass'n's Clean Air Project v. EPA, 686 F.3d 
803 (D.C. Cir. 2012). Because the standard has this form, a single 
exceedance does not create a violation of the standard. Instead, at 
issue is whether a source operating in compliance with a properly set 
longer term average could cause exceedances, and if so the resulting 
frequency and magnitude of such exceedances, and in particular whether 
the EPA can have reasonable confidence that a properly set longer term 
average limit will provide that the average fourth highest daily 
maximum value will be at or below 75 ppb. A synopsis of how EPA judges 
whether such plans ``provide for attainment,'' based on modeling of 
projected allowable emissions and in light of the NAAQS' form for 
determining attainment at monitoring sites, follows.
    For plans for SO2 based on 1-hour emission limits, the 
standard approach is to conduct modeling using fixed emission rates. 
The maximum emission rate that would be modeled to result in attainment 
(i.e., in an ``average year'' \1\ shows three, not four days with 
maximum hourly levels exceeding 75 ppb) is labeled the ``critical 
emission value.'' The modeling process for identifying this critical 
emissions value inherently considers the numerous variables that affect 
ambient concentrations of SO2, such as meteorological data, 
background concentrations, and topography. In the standard approach, 
the state would then provide for attainment by setting a continuously 
applicable 1-hour emission limit at this critical emission value.
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    \1\ An ``average year'' is used to mean a year with average air 
quality. While 40 CFR 50 appendix T provides for averaging three 
years of 99th percentile daily maximum values (e.g., the fourth 
highest maximum daily concentration in a year with 365 days with 
valid data), this discussion and an example below uses a single 
``average year'' in order to simplify the illustration of relevant 
principles.
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    The EPA recognizes that some sources have highly variable 
emissions, for example due to variations in fuel sulfur content and 
operating rate, that can make it extremely difficult, even with a well-
designed control strategy, to ensure in practice that emissions for any 
given hour do not exceed the critical emission value. The EPA also 
acknowledges the concern that longer term emission limits can allow 
short periods with emissions above the ``critical emissions value,'' 
which, if coincident with meteorological conditions conducive to high 
SO2 concentrations, could in turn create the possibility of 
a NAAQS exceedance occurring on a day when an exceedance would not have 
occurred if emissions were continuously controlled at the level 
corresponding to the critical emission value. However, for several 
reasons, the EPA believes that the approach recommended in its April 
2014 guidance document suitably addresses this concern. First, from a 
practical perspective, the EPA expects the actual emission profile of a 
source subject to an appropriately set longer term average limit to be 
similar to the emission profile of a source subject to an analogous 1-
hour average limit. The EPA expects this similarity because it has 
recommended that the longer term average limit be set at a level that 
is comparably stringent to the otherwise applicable 1-hour limit 
(reflecting a downward adjustment from the critical emissions value) 
and that takes the source's emissions profile into account. As a 
result, the EPA expects either form of emission limit to yield 
comparable air quality.
    Second, from a more theoretical perspective, the EPA has compared 
the likely air quality with a source having maximum allowable emissions 
under an appropriately set longer term limit, as compared to the likely 
air quality with the source having maximum allowable emissions under 
the comparable 1-hour limit. In this comparison, in the 1-hour average 
limit scenario, the source is presumed at all times to emit at the 
critical emission level, and in the longer term average limit scenario, 
the source is presumed occasionally to emit more than the critical 
emission value but on average, and presumably at most times, to emit 
well below the critical emission value. In an ``average year,'' 
compliance with the 1-hour limit is expected to result in three 
exceedance days (i.e., three days with hourly values above 75 ppb) and 
a fourth day with a maximum hourly value at 75 ppb. By comparison, with 
the source complying with a longer term limit, it is possible that 
additional exceedances would occur that would not occur in the 1-hour 
limit scenario (if emissions exceed the critical emission value at 
times when meteorology is conducive to poor air quality). However, this 
comparison must also factor in the likelihood that exceedances that 
would be expected in the 1-hour limit scenario would not occur in the 
longer term limit scenario. This result arises because the longer term 
limit requires lower emissions most of the time (because the limit is 
set well below the critical emission value), so a source complying with 
an appropriately set longer term limit is likely to have lower 
emissions at critical times than would be the case if the source were 
emitting as allowed with a 1-hour limit.
    As a hypothetical example to illustrate these points, suppose a 
source that always emits 1000 pounds of SO2 per hour, which 
results in air quality at the level of the NAAQS (i.e., results in a 
design value of 75 ppb). Suppose further that in an ``average year,'' 
these emissions cause the 5 highest maximum daily average 1-hour 
concentrations to be 100 ppb, 90 ppb, 80 ppb, 75 ppb, and 70 ppb. Then 
suppose that the source becomes subject to a 30-day average emission 
limit of 700 pounds per hour. It is theoretically possible for a source 
meeting this limit to have emissions that occasionally exceed 1000 
pounds per hour, but with a typical emissions profile emissions would 
much more commonly be between 600 and 800 pounds per hour. In this 
simplified example, assume a zero background concentration, which 
allows one to assume a linear relationship between emissions and air 
quality. (A nonzero background concentration would make the mathematics 
more difficult but would give similar results.) Air quality

[[Page 40089]]

will depend on what emissions happen on what critical hours, but 
suppose that emissions at the relevant times on these 5 days are 800 
pounds/hour, 1100 pounds per hour, 500 pounds per hour, 900 pounds per 
hour, and 1200 pounds per hour, respectively. (This is a conservative 
example because the average of these emissions, 900 pounds per hour, is 
well over the 30-day average emission limit.) These emissions would 
result in daily maximum 1-hour concentrations of 80 ppb, 99 ppb, 40 
ppb, 67.5 ppb, and 84 ppb. In this example, the fifth day would have an 
exceedance that would not otherwise have occurred, but the third and 
fourth days would not have exceedances that otherwise would have 
occurred. In this example, the fourth highest maximum daily 
concentration under the 30-day average would be 67.5 ppb.
    This simplified example illustrates the findings of a more 
complicated statistical analysis that EPA conducted using a range of 
scenarios using actual plant data. As described in appendix B of EPA's 
April 2014 SO2 nonattainment planning guidance, the EPA 
found that the requirement for lower average emissions is highly likely 
to yield better air quality than is required with a comparably 
stringent 1-hour limit. Based on analyses described in appendix B of 
its April 2014 guidance, the EPA expects that an emission profile with 
maximum allowable emissions under an appropriately set comparably 
stringent 30-day average limit is likely to have the net effect of 
having a lower number of exceedances and better air quality than an 
emission profile with maximum allowable emissions under a 1-hour 
emission limit at the critical emission value. This result provides a 
compelling policy rationale for allowing the use of a longer averaging 
period, in appropriate circumstances where the facts indicate this 
result can be expected to occur.
    The question then becomes whether this approach--which is likely to 
produce a lower number of overall exceedances even though it may 
produce some unexpected exceedances above the critical emission value--
meets the requirement in section 110(a)(1) and 172(c)(1) for state 
implementation plans to ``provide for attainment'' of the NAAQS. For 
SO2, as for other pollutants, it is generally impossible to 
design a nonattainment plan in the present that will guarantee that 
attainment will occur in the future. A variety of factors can cause a 
well-designed attainment plan to fail and unexpectedly not result in 
attainment, for example if meteorology occurs that is more conducive to 
poor air quality than was anticipated in the plan. Therefore, in 
determining whether a plan meets the requirement to provide for 
attainment, the EPA's task is commonly to judge not whether the plan 
provides absolute certainty that attainment will in fact occur, but 
rather whether the plan provides an adequate level of confidence of 
prospective NAAQS attainment. From this perspective, in evaluating use 
of a 30-day average limit, EPA must weigh the likely net effect on air 
quality. Such an evaluation must consider the risk that occasions with 
meteorology conducive to high concentrations will have elevated 
emissions leading to exceedances that would not otherwise have 
occurred, and must also weigh the likelihood that the requirement for 
lower emissions on average will result in days not having exceedances 
that would have been expected with emissions at the critical emissions 
value. Additional policy considerations, such as in this case the 
desirability of accommodating real world emissions variability without 
significant risk of violations, are also appropriate factors for the 
EPA to weigh in judging whether a plan provides a reasonable degree of 
confidence that the plan will lead to attainment. Based on these 
considerations, especially given the high likelihood that a 
continuously enforceable limit averaged over as long as 30 days, 
determined in accordance with the EPA's April 2014 guidance, will 
result in attainment, the EPA believes as a general matter that such 
limits, if appropriately determined, can reasonably be considered to 
provide for attainment of the 2010 SO2 NAAQS.
    The April 2014 guidance offers specific recommendations for 
determining an appropriate longer term average limit. The recommended 
method starts with determination of the 1-hour emission limit that 
would provide for attainment (i.e., the critical emission value), and 
applies an adjustment factor to determine the (lower) level of the 
longer term average emission limit that would be estimated to have a 
stringency comparable to the otherwise necessary 1-hour emission limit. 
This method uses a database of continuous emission data reflecting the 
type of control that the source will be using to comply with the SIP 
emission limits, which (if compliance requires new controls) may 
require use of an emission database from another source. The 
recommended method involves using these data to compute a complete set 
of emission averages, computed according to the averaging time and 
averaging procedures of the prospective emission limitation. In this 
recommended method, the ratio of the 99th percentile among these long 
term averages to the 99th percentile of the 1-hour values represents an 
adjustment factor that may be multiplied by the candidate 1-hour 
emission limit to determine a longer term average emission limit that 
may be considered comparably stringent.\2\ The April 2014 guidance also 
addresses a variety of related topics, such as the potential utility of 
setting supplemental emission limits, such as mass-based limits, to 
reduce the likelihood and/or magnitude of elevated emission levels that 
might occur under the longer term emission rate limit.
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    \2\ For example, if the critical emission value is 1000 pounds 
of SO2 per hour, and a suitable adjustment factor is 
determined to be 70 percent, the recommended longer term average 
limit would be 700 pounds per hour.
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    Preferred air quality models for use in regulatory applications are 
described in appendix A of the EPA's Guideline on Air Quality Models 
(40 CFR part 51, appendix W (appendix W)). In 2005, the EPA promulgated 
the American Meteorological Society/Environmental Protection Agency 
Regulatory Model (AERMOD) as the Agency's preferred near-field 
dispersion modeling for a wide range of regulatory applications 
addressing stationary sources (for example in estimating SO2 
concentrations) in all types of terrain based on extensive 
developmental and performance evaluation. Supplemental guidance on 
modeling for purposes of demonstrating attainment of the SO2 
standard is provided in appendix A to the April 2014 guidance. Appendix 
A provides extensive guidance on the modeling domain, the source 
inputs, assorted types of meteorological data, and background 
concentrations. Consistency with the recommendations in this guidance 
is generally necessary for the attainment demonstration to offer 
adequately reliable assurance that the plan provides for attainment.
    As stated previously, attainment demonstrations for the 2010 1-hour 
primary SO2 NAAQS must demonstrate future attainment and 
maintenance of the NAAQS in the entire area designated as nonattainment 
(i.e., not just at the violating monitor) by using air quality 
dispersion modeling (see appendix W to 40 CFR part 51) to show that the 
mix of sources and enforceable control measures and emission rates in 
an identified area will not lead to a violation of the SO2 
NAAQS. For a short-term (i.e., 1-hour) standard, the EPA believes that 
dispersion modeling, using allowable emissions and addressing 
stationary sources in the

[[Page 40090]]

affected area (and in some cases those sources located outside the 
nonattainment area which may affect attainment in the area) is 
technically appropriate, efficient and effective in demonstrating 
attainment in nonattainment areas because it takes into consideration 
combinations of meteorological and emission source operating conditions 
that may contribute to peak ground-level concentrations of 
SO2.
    The meteorological data used in the analysis should generally be 
processed with the most recent version of AERMET. Estimated 
concentrations should include ambient background concentrations, should 
follow the form of the standard, and should be calculated as described 
in section 2.6.1.2 of the August 23, 2010 clarification memo 
``Applicability of Appendix W Modeling Guidance for the 1-hr 
SO2 National Ambient Air Quality Standard'' (U. S. EPA, 
2010a) (August 2010 1-hour SO2 clarification memo).

IV. Review of Modeled Attainment Plan

    The following discussion evaluates various features of the modeling 
that Iowa used in its attainment demonstration.

A. Model Selection

    Iowa's attainment demonstration used the most current version of 
AERMOD available during each phase of its analysis (i.e., the 
determining sources culpable to nonattainment phase and the control 
strategy phase). As previously stated, AERMOD is the preferred model 
for this application. The final control strategy modeling analysis 
utilized version 15181. The state asserts that all analyses were 
conducted with EPA's regulatory default options and considering EPA's 
guidance documents including the August 2010 1-hour SO2 
clarification memo; the ``Additional Clarification Regarding 
Application of Appendix W Modeling Guidance for the 1-hour 
NO2 National Ambient Air Quality Standard'' memo (March 2011 
1-hour NO2 clarification memo); and the December 2013 
SO2 Modeling Technical Assistance Document (TAD).\3\ The 
receptor grid was centered on the Musser Park monitor, and extended out 
to the edges of the nonattainment area.\4\ Those portions of the fence 
lines of the facilities being evaluated that fell outside of the 
nonattainment area were omitted from the analysis. Finer grid spacing 
of 50 meters was used to resolve modeled impacts around other nearby 
individual facilities included in the analyses, but finer grid spacing 
was applied only around sources within the confines of the 
nonattainment area. Receptors were excluded from areas within the 
property boundaries of each facility in the analysis. The most recent 
version of AERMAP (11103) was used to import terrain and source 
elevations from the National Elevation Dataset (NED). All building 
downwash analyses were conducted using the most recent version (04274) 
of EPA's Building Profile Input Program with Plume Rise Enhancements 
(BPIP-Prime). EPA finds the selection and use of these inputs to 
AERMOD, AERMAP and BPIP-Prime to be appropriate and in accordance with 
appendix W and applicable EPA guidance, such as the TAD.\5\
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    \3\ SO2 NAAQS Designations Modeling Technical 
Assistance Document, December 2013.
    \4\ The Musser Park monitor was the violating monitor utilized 
during the designations process.
    \5\ The state utilized the December 2013 version of the modeling 
TAD when completing its technical analysis. The modeling TAD has 
been revised since then; the TAD was revised in February 2016 and 
then again in August 2016.
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B. Meteorological Data

    Modeling for the Muscatine 1-hr SO2 nonattainment SIP 
was conducted using the surface station and upper air data from the 
Davenport airport, and used consecutive years from 2008-2012.\6\ This 
represents the most recent, readily available 5-year period at the time 
of the initial analysis per section 8.3.1.2 of 40 CFR part 51 appendix 
W. The most current version of AERMET available during each phase of 
the analysis was used. The final control strategy analysis utilized 
data processed with AERMET version 14134. The state utilized AERMINUTE 
to process 1-minute ASOS wind data to generate hourly average winds for 
input to AERMET. EPA finds the selection and use of these inputs to 
AERMET to be appropriate and in accordance with appendix W and 
applicable EPA guidance, such as the TAD.
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    \6\ A detailed analysis to support the use of the Davenport 
meteorological data from the Davenport airport was previously 
approved by EPA for use in the PM2.5 Muscatine SIP 
analysis. See 79 FR 46742. EPA finds use of the Davenport airport 
site meteorological data to be appropriate for the 2010 1-hr 
SO2 Muscatine SIP.
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C. Emissions Data

    The state utilized information from the technical support document 
(TSD) it submitted to EPA during the nonattainment boundary 
recommendations to inform which sources needed to be included in its 
nonattainment SIP modeling.\7\ The nonattainment boundary analysis 
demonstrated that industrial sources along the Mississippi River have a 
role in causing or contributing to monitored exceedances at the Musser 
Park monitor. Based on this analysis, all major sources of 
SO2 emissions within the nonattainment area- Grain 
Processing Corporation (GPC), Muscatine Power and Water (MPW), and 
Monsanto- were included in the nonattainment SIP control strategy 
analysis.
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    \7\ https://www.epa.gov/sulfur-dioxide-designations/so2-designations-round-1-iowa-state-recommendation-and-epa-response and 
provided in the docket of this rulemaking.
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    As described in the state's nonattainment SIP, GPC is the largest 
source of SO2 within the nonattainment area. GPC is a corn 
wet milling facility that processes grain into industrial, beverage, 
and fuel-grade ethanol, as well as a variety of grain based food 
products, industrial products, and animal feeds. Early in the corn wet 
milling process the grain is soaked (steeped) in large tanks where 
sulfur containing compounds are added to the steep water to reduce 
bacterial growth and help break down the kernels. The sulfur content in 
the steep water is generally low but does lead to SO2 
emissions from a variety of downstream processes. The state asserts 
that 96 percent of the SO2 emissions at GPC is generated by 
six coal-fired boilers.
    MPW is a municipal electric generating station. MPW produces steam 
through the combustion of fossil fuels, generally coal, and uses the 
steam to produce electricity. The largest sources of SO2 
operated at MPW are three coal-fired boilers, Units 7, 8, and 9, 
serving generators with nameplate capacities of 25, 937, and 175.5 
megawatts (MW), respectively. An auxiliary boiler operated at MPW is 
not capable of burning coal but has the potential to emit 
SO2 when firing on distillate fuel oil.
    Monsanto is a manufacturer and formulator of herbicides for 
agricultural use and also produces intermediates for herbicide 
manufacturing and formulation. A coal-fired boiler (Boiler #8) used for 
the production of on-site heat and power is the largest SO2 
source at Monsanto.
    The state excluded four facilities located within the nonattainment 
area from the its nonattainment SIP modeling analysis: HNI 
Corporation--North Campus (HNI North); H.J. Heinz, L.P. (H.J. Heinz); 
Union Tank Car Co. (Union Tank); and HNI Corporation--Central Campus 
(HNI Central). As shown in the state's nonattainment SIP, the 
cumulative actual emissions from these sources is relatively low; the 
sources emitted a combined 0.14 tons of SO2 per year (tpy) 
in 2011. See section V.A. Emissions Inventory in this

[[Page 40091]]

preamble for the 2011 emissions data from these sources. Additionally, 
if the state were to consider the maximum fuel capacity of a source 
like Heinz that has two boilers that burn natural gas, it is unlikely 
that the SO2 emissions would be sufficient enough to cause a 
significant concentration gradient. The TAD indicates that ``other'' 
sources in the area not causing significant concentration gradients in 
the vicinity of the source(s) of interest, should be included in the 
modeling via monitored background concentrations. The EPA agrees with 
the state's recommendation that these facilities do not need to be 
explicitly modeled and that they are adequately characterized in the 
background SO2 concentrations. See section IV.E. Background 
Concentrations in this preamble for more detailed information regarding 
the determination of the background concentration.
    The state also evaluated several major sources of SO2 
emissions located outside of the nonattainment area boundary- 
MidAmerican Energy Louisa Generating Station (LGS), Gerdau Ameristeel 
(Gerdau), SSAB and Linwood and Lafarge. Linwood and Lafarge, located in 
Scott County, are approximately 20 km away from the nonattainment area. 
The selection of the Davenport monitor to represent background likely 
accounts for the emissions from Linwood and Lafarge.\8\ As such, 
Linwood and Lafarge were excluded from further consideration. See 
section IV.E. Background Concentrations in this preamble for additional 
information.
---------------------------------------------------------------------------

    \8\ According to information provided by the state in its 
nonattainment SIP, the Davenport monitor is located in Scott County, 
approximately 11 km from Linwood and Lafarge, and likely accounts 
for the emissions from Lafarge and Linwood.
---------------------------------------------------------------------------

    All included emission units were modeled using their actual stack 
parameters and site layout. There were no stacks above formula GEP 
(good engineering practice) height. There were stacks greater than 65 
meters at GPC, MPW, and LGS and each of those stacks were adjacent to 
tall buildings making the formula height taller than the actual stack 
height. Therefore, each of those stacks were modeled at their actual 
stack heights.
    Per EPA's April 2014 guidance, the use of allowable emissions and 
the modeling of intermittent emissions (for sources such as emergency 
generators and startup/shutdown emissions), for the purpose of modeling 
for SO2 attainment demonstrations, should follow the 
recommendations in EPA's March 2011 1-hour NO2 clarification 
memo (even though it was specific to NO2). The state's 
nonattainment SIP indicates that it addressed modeling intermittent 
sources in according with EPA's March 2011 1-hour NO2 
clarification memo, and as such all emission units that operate 
intermittently (e.g., emergency engines and fire pumps) were excluded 
from the analysis. Additionally, emission units that were limited to 
burning a specific fuel occasionally were modeled at emission rates 
that represent the fuel that is burned during normal operations. For 
example, the two auxiliary boilers (EP2 and EP3) operated by LGS are 
limited to burning fuel oil for no more than 48 hours per year. EP2 and 
EP3 burn natural gas during normal operations therefore, EP2 and EP3 
were modeled at emission rates associated with burning natural gas. EPA 
agrees with the state that it is appropriate to exclude these 
intermittent emissions (e.g., emergency engines and fire pumps) in the 
analysis and modeling the fuel burned during normal operations, as it 
is consistent with appendix W and the TAD.
    The state's nonattainment SIP acknowledges that, although 
SO2 emissions in and near the nonattainment area are 
principally attributable to point sources, a comprehensive emissions 
inventory should include an assessment of the other source sectors. The 
state asserted that it accomplished this by using estimates of air 
emissions for the onroad, nonroad, and nonpoint (area) sources from 
EPA's 2011 National Emissions Inventory (NEI) datasets. According to 
the state's sector summary analyses using EPA's SCC (source 
classification code) full detail data files from the 2011 NEI (version 
2, dated March 4, 2015), approximately 2.64 tons of SO2 were 
emitted by onroad mobile sources in all of Muscatine County (this 
includes areas within and outside of the nonattainment area). Nonroad 
mobile sources (which include non-road equipment, locomotives, 
commercial marine vessels, and aircraft) contributed approximately 1.99 
tpy of SO2. Again, that estimate includes nonroad mobile 
sources across all of Muscatine County.
    The state asserts that nonpoint (area) SO2 emissions 
were also relatively low, at approximately 18.73 tpy. Of that total, 
roughly half (8.92 tons) was associated with emissions mostly from 
prescribed fires. As with the mobile sectors, the nonpoint totals also 
represent sums across all of Muscatine County. The EPA agrees with the 
state's proposal that onroad, nonroad, and nonpoint sources in and near 
the Muscatine nonattainment area are adequately represented by 
background concentrations included in modeling analysis and that 
further consideration of these sectors is unnecessary. See section 
IV.E. Background Concentrations and section V. A. Emissions Inventory 
in this preamble for more detailed information.

D. Emission Limits

    Section 172(c)(6) of the CAA requires that the state's 
nonattainment plan include enforceable emission limitations, and such 
other control measures, means or techniques (including economic 
incentives such as fees, marketable permits, and auctions of emission 
rights), as well as schedules and timetables for compliance, as may be 
necessary or appropriate to provide for attainment of such standard in 
such area by the applicable attainment date. See General Preamble at 
13567-68.
    Part of the review of state's attainment plan must address the use 
of these limits, both with respect to the general suitability of using 
such limits for the purpose of meeting the requirements of CAA Sec.  
172(c)(6) with respect to whether the particular limits included in the 
plan have been suitably demonstrated to provide for attainment. The 
first subsection that follows addresses the enforceability of the 
limits in the plan, and the second subsection that follows addresses in 
the limits in particular the longer term average limits (i.e., the 21-
day average limit for MPW).
1. Enforceability
    As specified in section 172(c)(6) and section 110(a)(2)(A) of the 
CAA and 75 FR 35520, emission limitations, control measures and other 
elements in the SIP must be enforceable by the state and EPA. Working 
with GPC, MPW, and Monsanto the state developed an implementable 
control strategy designed to ensure expeditious attainment of the 1-hr 
SO2 NAAQS. The control strategy establishes source-specific 
control measures that include more stringent SO2 emissions 
limits, new control devices, and process changes. The state's 
nonattainment SIP includes these control measures with specific 
timetables for implementation, establishes minimum performance 
criteria, and provides schedules for completing verification processes. 
See section V. B. RACM/RACT in this preamble for additional 
information. New air construction permits issued to GPC, MPW, and 
Monsanto include emissions limits, timetables for compliance, and 
enforcement criteria and are the enforceable documents included in the 
state's nonattainment SIP that EPA is proposing to approve. As noted in 
the nonattainment SIP, the

[[Page 40092]]

state has the authority to implement each of the permits. Each permit 
includes notification, reporting, and recordkeeping requirements. The 
facilities must, for example, notify the state when they initiate and 
when they complete construction. Each permit also contains performance 
testing (emissions testing) obligations with specific schedules, 
methods, and frequencies for compliance. Each performance test must be 
approved by the state and a testing protocol must be submitted to the 
state in advance of the compliance demonstration. Results of the tests 
must be submitted in writing to the state in the form of a 
comprehensive report within six weeks of the completion of any testing. 
Additionally, GPC, MPW, and Monsanto are major sources under the Title 
V operating permit program and must submit semi-annual monitoring 
reports by September 30 and March 31, and an annual compliance 
certification by March 31, of each year. The state also inspects Title 
V sources at a minimum of every two years. In summary, the state has a 
comprehensive program to identify sources of violations and to 
undertake follow-up for compliance and enforcement.
    As noted in the state's May 26, 2016, submittal letter, Iowa was 
included in the agency's Response to Petition for Rulemaking; 
Restatement and Update of EPA's SSM Policy Applicable to SIPs; Findings 
of Substantial Inadequacy; and SIP Calls To Amend Provisions Applying 
to Excess Emissions During Periods of Startup, Shutdown and Malfunction 
(SSM SIP call) published June 12, 2015, (80 FR 33839). In the SSM SIP 
call, subrule 567--Iowa Administrate Code (IAC) 24.1(1) was found to be 
``substantially inadequate'' because it provides that excess emissions 
during periods of startup and shutdown are not a violation of an 
emission standard if good practices for minimizing emissions are 
followed. Each construction permit the state requested be included in 
the SIP apart if its control strategy contains SSM language from the 
subrule that is subject to the SIP call (Condition 6 of each permit). 
As such the state is requested that EPA not act on permit Condition 6 
of the included permits. EPA agrees that it would not be appropriate to 
approve Condition 6 of each permit into the SIP and propose the 
condition's exclusion.
    EPA is proposing to determine that these control measures, and the 
permits that contain them, satisfy CAA Sec.  110(a)(2)(A) and 172(c)(6) 
requirements and 75 FR 35520. It should be noted that the emission 
limit established for MPW in the control strategy of the state's 
nonattainment plan relies on a pound/hour (lb/hr) limit expressed an 
averaging time (e.g. as 21-day average) across multiple units.\9\ In 
accordance with EPA policy, the 21-day average limit is set at a lower 
level than the emission rate used in the attainment demonstration; the 
relationship between these two values is discussed in more detail in 
the following section.
---------------------------------------------------------------------------

    \9\ The MPW permit included as appendix C to the nonattainment 
SIP specifies that compliance with the emission standard of 1153 lb/
hr of SO2 shall be demonstrated through the use a 
Continuous Emissions Monitoring System (CEMS) and shall be 
determined on a 21-day rolling average bases. The limit includes 
startup, shutdown and malfunction emissions. Compliance with the 
emission limit shall be demonstrated using the formula found in 
Permit Condition 15.8. The emission limit became effective January 
1, 2017.
---------------------------------------------------------------------------

2. Longer Term Averaging
    As discussed in the April 2014 guidance, and in section III. 
Attainment Demonstration and Longer Term Averaging in this preamble, 
EPA has recommended that averaging times in SIP emission limits should 
not exceed the applicable NAAQS averaging time, in this case 1-hour, 
however, EPA has acknowledged that a 1-hr emission rate limit may be 
difficult to achieve at some facilities. As such EPA provided guidance 
for establishing longer term averaging limits based on a supportable 
downward adjustment of the critical emissions value. The critical 
emissions value is the 1-hr averaged emission rate that dispersion 
modeling predicts would attain the NAAQS.
    The control strategy included in the state's nonattainment SIP 
allows MPW to meet a compliance formula based on a 21-day averaging 
period across multiple units running alone or in combination. The 
formula incorporates a weighting function derived from the modeling 
results of the individual units (Units 7, 8 and 9), and downward 
adjustments of the critical emissions values. A separate downward 
adjustment was calculated for each unit using five years of unit-
specific CEMS data, 2010-2014; the state considered this data to be 
representative of the boilers' operations into the future, and reflect 
the fact that each unit is emitting from a separate stack. The 1-hour 
emissions value of 1,153 lbs/hr used in the formula incorporates the 
adjustment to a longer term limit according to the ratio of the 99th 
percentile 21-day average emission rate to the 99th percentile 1-hr 
emission rates from the CEMS data. Because the 1,153 lbs/hr value was 
derived from all 3 units operating together additional model runs were 
needed to ensure the formula was protective under other operating 
scenarios, with combinations of one or two units operating. The formula 
provides flexibility for MPW to run their three coal units alone or in 
combination in such a way that the NAAQS will be protected at all 
times. Because the units have different dispersion characteristics, the 
formula weighs each unit's individual emissions such that the critical 
modeled value in the formula is always protected.
    To determine the longer term average limit, the state determined 
the individual variability of each unit from the 2010-2014 CEMS data as 
described above. The variability value ratios of the 99th percentile 
21-day average and 99th percentile hourly values were 0.71, 0.90, 0.63 
for the three units respectively. The state determined a critical value 
for each of these units individually using their respective variability 
and stack characteristics. In the first modeling scenario (the ``All'' 
run) the state determined the hourly critical values for Units 7,8,9 as 
250 lbs/hr, 1000 lbs/hr, and 120 lbs/hr respectively, so 1,370 lbs/hr 
total from the 3 units. Applying the individual unit variability, the 
equivalent 21 day limits would be 177.5 lbs/hr, 900.0 lbs/hr, and 75.6 
lbs/hr respectively which when added together is 1,153 lbs/hr, the 
value that becomes the basis of the compliance formula. The state then 
modeled 7 combinations of emissions scenarios using the individual unit 
stack characteristics that all demonstrated compliance with the NAAQS 
and accounted for individual variability of each unit. These scenarios 
consisted of 3 model runs where the individual units were operating 
alone and 4 model runs with various combinations of units operating. 
Each run had its own hourly critical modeled value demonstrating 
compliance and these 7 runs formed the basis for the weights in the 
formula to ensure 1,153 lbs/hr was always protective of all the 
individual critical values modeled. This provided modeled emission 
rates such that a weighted formula could be derived such that any 
combination of emissions from the three individual units would always 
be at or below the value of 1,153 lbs/hr as expressed in the formula. 
Because the stacks have different dispersion characteristics and the 
modeled scenarios have different critical emission values, the formula 
derived contains different weights or multipliers for each unit's 
actual hourly emissions, but the weights are such that no individual 
unit operating alone or a combination of units will cause a NAAQS 
violation as long as the formula criteria as expressed in the permit 
are

[[Page 40093]]

met.\10\ Table 1 shows that during each operational scenario at MPW, 
combined with the control strategies for GPC and Monsanto, the current 
maximum allowable permitted emission rates from LGS, and background 
concentrations, will result in attainment of the 1-hour SO2 
NAAQS.
---------------------------------------------------------------------------

    \10\ The formula for MPW, as specified in their permit is as 
follows:
    ``The owner or operator shall maintain a file of computations to 
show the total hourly emission level for SO2. The owner 
or operator shall use the total hourly SO2 emission rates 
to calculate and record the average SO2 emission rate for 
each calendar day. Effective January 1, 2017, the owner or operator 
shall use the daily average SO2 emission rates to 
demonstrate compliance with the 21-day rolling average as calculated 
below: SO2 = 2.03*(Unit 7) + 0.84*(Unit 8) + 1.22*(Unit 
9) Where, SO2 = total emissions, in pounds per hour, of 
sulfur dioxide from Unit 7, Unit 8 and Unit 9
    Unit 7 = 24-hour average sulfur dioxide emission rate, lb/hr, 
for Unit 7
    Unit 8 = 24-hour average sulfur dioxide emission rate, lb/hr, 
for Unit 8
    Unit 9 = 24-hour average sulfur dioxide emission rate, lb/hr, 
for Unit 9.

  Table 1--Cumulative Modeling Results With Each MPW Operating Scenario
------------------------------------------------------------------------
                                            Cumulative      1-hour SO2
         MPW operating scenario            model result    NAAQS ([mu]g/
                                            ([mu]g/m3)          m3)
------------------------------------------------------------------------
All.....................................          182.76             196
U9 Off..................................          182.71  ..............
U8 Off..................................          183.66  ..............
U7 Off..................................          182.88  ..............
U7 Only.................................          183.96  ..............
U8 Only.................................          181.86  ..............
U9 Only.................................          187.78  ..............
------------------------------------------------------------------------

    Based on a review of the state's submittal, the EPA believes that 
the 21-day average limit for MPW provides a suitable alternative to 
establishing a 1-hour average emission limit for this source. The state 
has used a suitable data base in an appropriate manner and has thereby 
applied an appropriate adjustment, yielding an emission limit formula 
that has comparable stringency to the 1-hour average limit that the 
state determined would otherwise have been necessary to provide for 
attainment. While the 21-day average limit allows occasions in which 
emissions may be higher than the level that would be allowed with the 
1-hour limit, the state's limit compensates by requiring average 
emissions to be lower than the level that would otherwise have been 
required by a 1-hour average limit. For reasons described above and 
explained in more detail in EPA's April 2014 guidance, EPA finds that 
appropriately set longer term average limits provide a reasonable basis 
by which nonattainment plans may provide for attainment. Based on its 
review of this general information as well as the particular 
information in state's plan, the EPA finds that the 21-day average 
limit formula for MPW in combination with other limitations in the 
state's plan, will provide for attainment of the NAAQS.

E. Background Concentrations

    The state reviewed its statewide SO2 monitoring network 
to determine an appropriate background monitoring location- the 
Davenport SO2 monitoring site. As noted by the state, the 
ideal background location chosen represents the contributions from all 
sources not explicitly modeled. Because the monitoring locations in 
Muscatine, IA are impacted significantly by sources that were included 
in the modeling analysis, those monitors were eliminated as an option 
to represent the background concentrations in the area. Of the 
remaining monitor locations, two are situated adjacent to 
industrialized areas (Cedar Rapids and Clinton), and, as such, would 
likely be an overestimate of the concentrations caused by background 
sources. The state determined that the Des Moines and Lake Sugema 
monitors were impacted by less SO2 emissions than what would 
be represented by the background for the Muscatine nonattainment area--
and, as such, would likely be an underestimation of the concentrations 
of SO2 caused by background sources.\11\
---------------------------------------------------------------------------

    \11\ The Des Moines monitor is approximately 5 km from the 
nearest SO2 source. The county emissions are 
approximately 163 tpy. The Lake Sugema monitor is more than 10 km 
away from the nearest SO2 source. The state's 
nonattainment SIP indicates that are no reported major or minor 
sources of SO2 emissions in the county.
---------------------------------------------------------------------------

    The state determined that the Davenport SO2 monitoring 
location was appropriate for estimating background concentrations for 
the following reasons: (1) The Davenport monitor is the nearest 
location to the nonattainment area (other than those monitors located 
in Muscatine already excluded); (2) the Davenport monitor is near a 
moderately industrialized area, but is not situated adjacent to those 
sources of emissions; (3) the Davenport monitor is in a county with a 
moderate amount of SO2 emissions; and (4) using the 
Davenport monitor is consistent with the meteorological data used for 
the analysis. For these reasons the state believed that the Davenport 
monitoring location could account for the sources screened out of the 
control strategy such as emissions from natural sources, major and 
minor point sources not included in the analysis, mobile (onroad and 
nonroad) sources, and nonpoint sources.
    The state utilized temporally varying background concentrations by 
hour and season from the Davenport SO2 monitoring location 
to account for contributions to the predicted impacts from background 
SO2 sources. To account for seasonal and diurnal variations 
in the background levels, the state based the background concentration 
on the average diurnal and seasonal concentration pattern observed at 
the Davenport monitor during the years 2011-2013. For the years 2011-
2013, the 99th percentile monitor concentration was calculated for each 
hour of the day by season and then averaged across the three years.\12\
---------------------------------------------------------------------------

    \12\ The EPA's SO2 National Ambient Air Quality 
Standards Designations Modeling TAD describes an appropriate 
methodology of calculating temporally varying background monitored 
concentrations by hour of day and season (excluding periods when the 
source in question is expected to impact the monitored 
concentration). The methodology is to use the 99th percentile 
concentration for each hour of the day by season and average across 
3 years, excluding periods when the dominant source(s) are 
influencing the monitored concentration (i.e., 99th percel1tile, or 
4th highest, concentrations for hour l for January or winter, 99th 
percentile concentrations for hour 2 for January or winter, etc.).
---------------------------------------------------------------------------

    The state also averaged the 2011-2013 design values for Cedar 
Rapids, Davenport, Des Moines, and Lake Sugema to determine if that 
number,

[[Page 40094]]

10.5 ppb, would be appropriate as background. The state called this the 
Tier 1 value. The Tier 1 value of 10.5 ppb is higher than all but one 
of the seasonal/diurnal concentrations. This shows that the use of the 
Tier 1 value for all hours and seasons would have been too high to 
represent the variable background concentrations. The EPA agrees with 
the state's proposal that the method of using temporally varying 
background monitor concentrations by hour and season from the Davenport 
monitoring location, as it is calculated from the 99th percentile, is 
appropriate.

F. Summary of Results

    The modeling analysis was conducted in two phases. The first phase 
(Phase 1) of the analysis was a screening analysis to determine the 
sources that needed to be included in the control strategy analysis. 
The second phase (Phase 2) of the analysis was used to develop the 
control strategy and included all significant sources identified in 
Phase 1.
1. Phase 1--Preliminary Analysis
    This phase was accomplished by modeling actual emissions from GPC, 
MPW, Monsanto, and LGS and allowable emissions from SSAB and Gerdau and 
then determining the percentage of predicted NAAQS exceedances within 
the nonattainment area to which each facility significantly 
contributed. In this way, the state determined that GPC contributed to 
100 percent of the NAAQS exceedances, MPW contributed to approximately 
25 percent of the NAAQS exceedances, Monsanto contributed to 
approximately 1 percent of the NAAQS exceedances, and LGS contributed 
to approximately 5 percent of the NAAQS exceedances. Both SSAB and 
Gerdau each modeled less than a 1 percent contribution to the NAAQS 
exceedance days within the nonattainment area. Therefore, only GPC, 
MPW, Monsanto and LGS were determined to have enough potential 
contribution to NAAQS exceedances to be evaluated further.\13\
---------------------------------------------------------------------------

    \13\ The LGS facility is located immediately south of the 
nonattainment area. During the designations process, this source was 
shown to be insignificant during predicted exceedances at the Musser 
Park monitor, but as it was possible that the source could cause a 
concentration gradient in the vicinity of the southern portion of 
the nonattainment area, it was included in the analysis.
---------------------------------------------------------------------------

    The state then further subdivided the sources by classifying the 
significant contributors as either a primary or a secondary 
contributor. If the facility's significant contribution to the 
predicted NAAQS exceedance was greater than or equal to half of the 
total concentration (minus background) it was considered a primary 
contributor. If the facility's contribution was less than half of the 
total concentration, but still more than the Significant Impact Level 
(SIL) it was considered a secondary contributor.\14\
---------------------------------------------------------------------------

    \14\ Per EPA's August 23, 2010, ``Guidance Concerning the 
Implementation of the 1-hour SO2 NAAQS for the Prevention 
of Significant Deterioration Program'', the SIL is 3 ppb. The EPA 
plans ``to undertake rulemaking to adopt a 1-hour SO2 SIL 
value. However, until such time as a 1-hour SO2 SIL is 
defined in the PSD regulations, we are providing an interim SIL of 3 
ppb, which we intend to use as a screening tool for completing the 
required air quality analyses for the new 1-hour SO2 SIL 
NAAQS under the federal PSD program at 40 CFR 52.21. We are also 
making the interim SIL available to States with EPA-approved 
implementation plans containing a PSD program to use at their 
discretion.'' The SIL remains an interim SIL until rulemaking is 
complete.
---------------------------------------------------------------------------

    GPC was identified as a primary contributor to all predicted NAAQS 
exceedances within the nonattainment area. GPC's max potential 
contribution was estimated as 3,180 [micro]g/m\3\ (or approximately 
1,223 ppb).\15\ GPC's contribution to the predicted NAAQS exceedance 
was greater than or equal to half of the total concentration (minus 
background) 100 percent of the time.
---------------------------------------------------------------------------

    \15\ To convert from [micro]g/m\3\ to ppb, the [micro]g/m\3\ 
value was divided by 2.6.
---------------------------------------------------------------------------

    MPW, Monsanto and LGS were identified as secondary contributors. 
MPW's max potential contribution was estimated as 107 [micro]g/m\3\ (or 
approximately 41 ppb). MPW's contribution to the predicted NAAQS 
exceedance was less than half of the total concentration, but still 
more than SIL (minus background) 26 percent of the time. Monsanto's max 
potential contribution was estimated as 28 [micro]g/m\3\ (or 
approximately 11 ppb). Monsanto's contribution to the predicted NAAQS 
exceedance was less than half of the total concentration, but still 
more than SIL (minus background) less than 1 percent of the time. LGS's 
maximum potential contribution was estimated as 59 [micro]g/m\3\ (or 
approximately 22.7 ppb). LGS's contribution to the predicted NAAQS 
exceedance was less than half of the total concentration, but still 
more than SIL (minus background) 2 percent of the time. As such, only 
GPC, MPW, Monsanto and LGS were included in the second phase of the 
analysis.
2. Phase 2--Control Strategy Development
    Sources identified in Phase 1 (GPC, MPW, Monsanto, and LGS) as 
being significant contributors were modeled at their maximum permitted 
allowable emission rates. Using the process summarized below, more 
restrictive maximum permitted emission rates were developed where 
necessary to ensure modeled attainment.
    To start its Phase 2 analysis, the state provided GPC with a model 
input file that included its emission units as well as the exceedance 
receptors to which it contributed. The state's nonattainment SIP 
submittal indicates that GPC reviewed the input data for accuracy and 
then mitigated all modeled exceedances caused by the GPC facility 
alone.
    The remaining facilities (MPW, Monsanto, and LGS) were then added 
to the analysis with their maximum permitted allowable emission rates 
and the cumulative impacts were determined across the entire 
nonattainment area. According to the state's nonattainment SIP 
submittal, the remaining predicted exceedances were then discussed with 
Monsanto and MPW. As a result of those discussions, additional control 
measures were developed for those facilities and are incorporated in 
construction permits submitted as part of the SIP revision. See section 
V.B. in this preamble for more information regarding the control 
measures.
    Monsanto proposed to decrease the emission rate for Boiler 8 at its 
facility to mitigate exceedances just north of its property. MPW 
proposed multiple model scenarios with combined operation of Units 7, 
8, and 9. Regardless of the operational scenario, the unit/units were 
modeled at an equation cap of 1,153 lb/hr SO2. The model 
results varied depending on which combination of boilers was running. 
Each of the modeling scenarios (with background included) resulted in 
concentrations below the 1-hour SO2 NAAQS. The highest 
modeled SO2 concentration was 187.87 ug/m\3\ which included 
the operation of just Unit 9 at MPW. See section IV.D.2. Longer Term 
Averaging limits, in this preamble, for more discussion of the equation 
used to determine compliance with the NAAQS for each MPW modeling 
scenario.
    These results indicate that the controls established in the 
construction permits for MPW, GPC and Monsanto result in attainment of 
the NAAQS, and as such, additional controls were not necessary for LGS 
in order for the area to attain. 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/196.4 ug/m\3\. Based upon monitoring data discussed in section 
V.B. RACM/RACT in this preamble, EPA expects that the Muscatine area 
will attain by the attainment date, August 5, 2018.

[[Page 40095]]

V. Review of Other Plan Requirements

A. Emissions Inventory and the Quantification of Emissions

    Section 172(c)(3) of the CAA requires that the state's 
nonattainment plan include a comprehensive, accurate, current inventory 
of actual emissions from all sources of the relevant pollutant or 
pollutants in such area, including such periodic revisions as the 
Administrator may determine necessary to assure that the requirements 
of this part are met. Section 172(c)(4) of the CAA requires that the 
state's nonattainment plan expressly identify and quantify the 
emissions, if any, of any such pollutant or pollutants which will be 
allowed, in accordance with section 703(a)(1)(B) of the CAA, from the 
construction and operation of major new or modified stationary sources 
in each such area. The plan shall demonstrate to the satisfaction of 
the Administrator that the emissions quantified for this purpose will 
be consistent with the achievement of reasonable further progress and 
will not interfere with attainment of the applicable National Ambient 
Air Quality Standard by the applicable attainment date.
    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 expected improvement in air quality 
within the nonattainment area due to the adoption and implementation of 
control measures. As noted above, the state must develop and submit to 
EPA a comprehensive, accurate and current inventory of actual emissions 
from all sources of SO2 emissions in each nonattainment 
area, as well as any sources located outside the nonattainment area 
which may affect attainment in the area. See the April 2014 guidance. 
Additional emission inventory information was discussed in section IV.C 
Emissions Data in this preamble. A brief summary is provided later in 
this action.
    The base year inventory establishes a baseline that is used to 
evaluate emissions reductions achieved by the control strategy and to 
assess reasonable further progress requirements. The state's 
nonattainment SIP noted that, at the time, the most recent and 
available triennial inventory year was 2011 and the stated found that 
it served as a suitable base year. Table 2 provides the 2011 
SO2 emissions inventory data for sources within and outside 
of the nonattainment the area (data have been rounded to the nearest 
whole number).

       Table 2--Base Line Emission Inventory for the Muscatine, IA
                           Nonattainment Area
------------------------------------------------------------------------
                                                             2011 SO2
                                         Facility            emissions
                                                               (tpy)
------------------------------------------------------------------------
           Base Line Emissions Inventory for the Muscatine NAA
------------------------------------------------------------------------
Inside of the NAA..............  Grain Processing                 10,810
                                  Corporation.
                                 Muscatine Power and               2,374
                                  Water.
                                 Monsanto...............             537
                                 HNI Corp.--North Campus              <1
                                 HNI Corp.--Central                   <1
                                  Campus.
                                 H.J. Heinz L.P.........              <1
                                 Union Tank Car Co......              <1
Outside of the NAA.............  Louisa Generating                 7,304
                                  Station.
All of Muscatine County........  Onroad Mobile..........               3
                                 Nonroad Mobile.........               2
                                 Area Sources...........              10
                                 Fires..................               9
                                                         ---------------
    Total......................  .......................          21,049
------------------------------------------------------------------------

    Although not part of the state's discussion of its 2011 baseline 
emissions inventory, the state's nonattainment SIP also provides 2013 
SO2 data for Gerdau and SSAB in Muscatine County and Linwood 
and Lafarge in Scott County. However, the state provided this as a sum 
for the sources by county (e.g., the sum of Gerdau and SSAB was 254 tpy 
and the sum of Linwood and Lafarge was 1,539 tpy). Gerdau and SSAB are 
approximately 8-9 km away from the nonattainment boundary and Linwood 
and Lafarge are approximately 20 km away from the nonattainment area 
boundary.
    As already noted, the state's nonattainment SIP must identify and 
quantify the emissions which will be allowed from the construction and 
operation of major new or modified stationary sources in the area (see 
CAA Sec.  172(c)(4)). The state must demonstrate that such emissions 
will be consistent with RFP requirements and will not interfere with 
attainment of the 1-hr SO2 NAAQS. These requirements are met 
by the states preconstruction permitting program and implementation of 
the Nonattainment New Source Review Rules (NNSR). See section C. 
Nonattainment New Source Review in this preamble for more information.
    According to EPA's April 2014 SO2 guidance, the SIP 
should also include a projected attainment year inventory that includes 
estimated emissions for all emission sources of SO2 that 
were determined to have an impact on the affected nonattainment area 
for the year in which the area is expected to attain the standard, 
consistent with the attainment demonstration. The inventory should 
reflect projected emissions for the attainment year for all 
SO2 sources in the nonattainment area. The state's 
nonattainment SIP provided a projected inventory only for the 
controlled sources, as provided in table 3. The inventory was developed 
assuming each SO2 source operates 8,760 hours per year at 
its permitted maximum allowable emission rate.\16\
---------------------------------------------------------------------------

    \16\ The projections don't consider operational, physical, 
supply/demand, or other factors that typically curb actual emissions 
to values below the maximum permitted allowable rate. There is 
potential for the actual attainment-year emissions to be lower than 
those in Table 2.

[[Page 40096]]

 Table 3--Projected Allowable Annual SO2 Emissions From Control Strategy
                                 Sources
------------------------------------------------------------------------
                                                               2018 SO2
                                                               emissions
                          Facility                               (tpy)
 
------------------------------------------------------------------------
           Projected 2018 Emissions for the Controlled Sources
------------------------------------------------------------------------
Grain Processing Corporation................................         167
Muscatine Power and Water...................................       5,051
Monsanto....................................................       1,196
------------------------------------------------------------------------

    The EPA is proposing to determine that the state has met the 
requirements of CAA Sec.  172(c)(3) and 172(c)(4).

B. RACM/RACT

    CAA Sec.  172(c)(1) requires that the state's nonattainment plan 
provide for the implementation of all RACM as expeditiously as 
practicable (including such reductions in emissions from existing 
sources in the area as may be obtained through the adoption, at a 
minimum, of RACT) and shall provide for attainment of the NAAQS. The 
state's plan for attaining the 1-hour SO2 NAAQS in the 
Muscatine nonattainment area is based on a variety of control measures 
at GPC, MPW and Monsanto. Those measures were included in the state's 
nonattainment SIP as construction permits.\17\
---------------------------------------------------------------------------

    \17\ Appendix B, C and D of the state's nonattainment SIP 
contain the Federally enforceable air construction permits that 
define RACM/RACT requirements. The RACM/RACT limits taken to comply 
with the NAAQS are specifically noted in each permit via footnotes 
in the permits.
---------------------------------------------------------------------------

    To ensure the SO2 NAAQS is attained, GPC must install 
additional scrubbers, comply with new and more stringent SO2 
emission limits, and implement process modifications designed to ), 
andreduce SO2 emissions across numerous downstream sources. 
Table 4-1 of the state's nonattainment SIP lists all the sources 
included in the control strategy, contains descriptions of the control 
measures, and provides effective dates. Source specific permitted 
allowable emission rates, compliance and monitoring obligations, 
reporting and recordkeeping requirements, and implementation deadlines 
(where not immediately effectively upon permit issuance) are detailed 
in each construction permit included with the SIP submittal (appendix B 
of the state's nonattainment plan). The GPC control strategy includes 
measures at 52 emission points (EP) at the facility. In summary, those 
measures include EP0001.0 (Power House Boilers 1-4 and 6-7) is subject 
to a more stringent SO2 emission limit based on natural gas 
combustion; EP546.0 is subject to a more stringent, source-specific 
SO2 limit of .0034 lb/hr; a requirement to continue to add 
sodium bisulfate to the steep water instead of sulfur dioxide in order 
to reduce SO2 emissions from the steeping operations and 
downstream processes; the establishment of source specific 
SO2 emission limits at 43 EPs and the required installation 
of scrubbers on EP015.0 (Germ Drier Nos. 1 and 2), EP097.0 (Germ Drier 
No. 3), EP126.0 (Germ Drier No. 4), EP200N (Corn Steep Tank Nos. 1-30 
and the North Wet Corn Drag), EP200S (Corn Steep Tank Nos. 31-62 and 
the South Wet Corn Drag), and EP279.0 (Wet Milling Nos. 1-6). The state 
expects the installation of the scrubbers to reduce SO2 
emissions by up to 90 percent from those units.\18\
---------------------------------------------------------------------------

    \18\ The state's estimation of a 90 percent reduction in 
SO2 emissions is based off of the control efficiency 
readily achieved by the types of scrubbers being installed.
---------------------------------------------------------------------------

    While the scrubber installations will not be completed by January 
1, 2017, the desired target date discussed in EPA's April 2014 
guidance, the scrubbers will be operational as expeditiously as 
practicable. Based on permitted requirements, three of the six new 
scrubbers must be in operation no later than August 30, 2017, with the 
final scrubber operational by March 31, 2018. The installation 
timetable accommodates factors such as demolition and construction 
schedules, structural modifications, ductwork design, and the addition 
of scrubber water treatment capacity. The state asserts in its 
nonattainment plan that the scrubber installation timeline will not 
delay or prevent timely attainment of the 1-hr SO2 NAAQS.
    It should also be noted that, on July 14, 2015, GPC converted all 
of its coal-fired boilers to natural gas. The state estimates that the 
fuel switch will result in a 96 percent reduction in the facility's 
total SO2 emissions. In terms of 2011 data, this fuel switch 
eliminated 10,374 tons of SO2 emissions. The state believes, 
and the EPA agrees, that the fuel conversion from coal to natural gas 
in GPC's boilers has significantly reduced measured ambient 
SO2 concentrations in Muscatine, as noted in Table 4. Based 
on existing air quality improvements the state projects that monitored 
attainment will be achieved by the attainment date. Appendix B of the 
state's nonattainment SIP contains the Federally enforceable air 
construction permits that define GPC's RACM/RACT requirements.

                                                                    Table 4--Air Monitoring Data From the Musser Park Monitor
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                Design values (ppb)                     99th Percentile daily max 1-hr SO2 concentrations (ppb)
-------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                     -----------------------------------------------------------
              Monitor location                     1-hr SO2 NAAQS (ppb)         2011-2013     2012-2014     2013-2015     2014-2016     2011      2012      2013      2014      2015      2016
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Musser Park.................................  75............................          217           194           158           113       248       224       179       180       116        45
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

    MPW is subject to several Federal programs that directly or 
indirectly affect SO2 emissions, including the Acid Rain 
provisions of title IV of the CAA, the Cross State Air Pollution Rule 
(CSAPR), and the CAA section 112 Maximum Achievable Control Technology 
regulations more commonly known as the Mercury and Air Toxics 
Standards. However, the state did not rely on these Federal programs 
alone to address SO2 emissions. Instead, as per the states 
control strategy, MPW will comply with new SO2 emission 
limits that provide for attainment of the NAAQS. The control measures, 
described in table 4-2 of the state's nonattainment SIP, account for 
seven possible operating scenarios involving the three coal-fired 
boilers (Units 7, 8, and 9). Permit No. 74-A-175-S3, issued to the 
facility in 2013, shows the SO2 emission limit for Units 7 
and 8 was a combined maximum of 2,772 lb/hr. Permit No. 80-A-191-P2, 
issued to the facility in 2013, shows the SO2 emission limit 
for Unit 9 was 0.56 lb/MMBtu (a maximum daily average). Permit No. 80-
A-191-P4, issued to the facility in 2016 as part of the control 
strategy of

[[Page 40097]]

the state's nonattainment SIP, shows the combined SO2 
emissions from Units 7-9 must be less than 1,153 lbs/hr.
    The control strategy for MPW also addresses emission reductions 
from EP60 (Auxiliary Boiler). A permit issued to the facility in 2013, 
Permit No. 13-A-152, for the Auxiliary Boiler required that 
SO2 emissions be limited to limited 0.44 lbs/MMBtu 
(expressed as the average of 3 runs) when burning fuel oil, and to 500 
ppm by volume when burning natural gas or propane.\19 20\ The permit 
issued to the facility in 2016, as part of the control strategy, Permit 
No. 13-A-152-S1, requires that the SO2 emissions be limited 
to 0.45 lb/hr and that the sulfur content of the distillate fuel oil 
combusted in the unit not exceed 15 ppm. Appendix C of the state's 
nonattainment SIP contains the Federally enforceable air construction 
permits that define MPW's RACM/RACT requirements. These permits are 
effective January 1, 2017.
---------------------------------------------------------------------------

    \19\ The unit's 0.44 lbs/MMBtu emission rate is a Lowest 
Achievable Emission Rate (LAER).
    \20\ The limit of 500 ppm by volume is from state rule.
---------------------------------------------------------------------------

    The control measures developed for Monsanto, described in table 4-3 
of the state's nonattainment SIP, establish lower emission limits on 
two sources--EP-195 (Boiler #8) and EP-234 (CAC Process Flare). The 
Boiler #8 control strategy includes a more stringent SO2 
emission limit. A 2007 permit issued to the facility Permit No. 82-A-
092-P9, limited the unit's SO2 emissions to 292.5 lb/hr. The 
permit issued to the facility in 2015, Permit No. 82-A-092-P11, as part 
of the control strategy, limits the unit's SO2 emissions to 
273 lb/hr.\21\
---------------------------------------------------------------------------

    \21\ The unit also has a 1.95 lbs/MMBtu based on a 3-hr rolling 
average limit is a Best Available Control Technology limit.
---------------------------------------------------------------------------

    The control strategy for the CAC Process Flare includes new 
SO2 emission limit that restricts the unit's fuel use to 
natural gas only. A 2012 permit issued to the facility, Permit No. 88-
A-001-S2, limited the unit's SO2 emissions to 500 ppm by 
volume. The permit issued to the facility in 2015, Permit No. 88-A-001-
S3, as part of the control strategy, limits the unit to burning only 
natural gas and the unit's SO2 emissions to 0.02 lb/hr. 
Appendix D of the state's nonattainment SIP contains the Federally 
enforceable air construction permits that define Monsanto's RACM/RACT 
requirements. These permits are effective May 13, 2015.
    The state has determined that these measures suffice to provide for 
attainment the attainment date, August 5, 2018. EPA concurs and 
proposes to conclude that the state has satisfied the requirement in 
CAA Sec.  172(c)(1) to adopt and submit all RACM as needed to attain 
the standards as expeditiously as practicable.

C. Nonattainment New Source Review (NNSR)

    Section 172(c)(5) requires that the state's nonattainment plan 
provisions shall require permits for the construction and operation of 
new or modified major stationary sources anywhere in the nonattainment 
area, in accordance with section CAA Sec.  173. EPA approved the 
state's nonattainment new source review rules on May 15, 2014 (79 FR 
27763). These rules provide for appropriate new source review for 
SO2 sources undergoing construction or major modification in 
the Muscatine nonattainment area without need for modification of the 
approved rules. Therefore, EPA concludes that the requirements of CAA 
Sec.  172(c)(5) have been met.

D. Reasonable Further Progress (RFP)

    Section 172(c)(2) requires that nonattainment plans include 
provisions addressing reasonable further progress (RFP). Reasonable 
further progress is defined in CAA Sec.  171(1) as: ``. . . such annual 
incremental reductions in emissions of the relevant air pollutant as 
are required by this part [part D] or may reasonably be required by the 
Administrator for the purpose of ensuring attainment of the applicable 
national ambient air quality standard by the applicable date.''
    As discussed in EPA's April 2014 guidance, this definition is most 
appropriate for pollutants that are emitted by numerous and diverse 
sources, where the relationship between any individual source and 
overall air quality is not explicitly quantified, and where NAAQS 
attainment requires inventory-wide emissions reductions. The 
SO2 NAAQS presents special circumstances because there are 
usually a limited number of well-defined sources affecting the area's 
air quality and any emission control measures commonly result in swift 
improvements that typically occur in one step. As noted in the state's 
nonattainment SIP, the EPA has interpreted that RFP is best construed 
as ``adherence to an ambitious compliance schedule'' in previous 
rulemaking.\22\
---------------------------------------------------------------------------

    \22\ See 74 FR 13547 (April 16, 1992).
---------------------------------------------------------------------------

    As previously noted in section V.B. RACT/RACM, in this preamble, 
the SO2 emission limits and application of control 
technologies established for Monsanto (effective on May 13, 2015), MPW 
(effective January 1, 2017) and for GPC occur on reasonable timelines.
    The state asserts that this plan requires that affected sources 
implement appropriate control measures as expeditiously as practicable 
in order to ensure attainment of the standard by the applicable 
attainment date. The state concluded that its plan therefore provides 
for RFP in accordance with the approach to RFP described in EPA's 
guidance. EPA concurs and proposes to conclude that the plan provides 
for RFP as required by CAA Sec.  172(c)(2).

E. Contingency Measures

    Section 172(c)(9) of the CAA requires that the state's 
nonattainment plan provide for the implementation of specific measures 
to be undertaken if the area fails to make reasonable further progress, 
or to attain the national primary ambient air quality standard by the 
attainment date applicable under this part. Such measures shall be 
included in the plan revision as contingency measures to take effect in 
any such case without further action by the State or the Administrator.
    EPA's April 2014 guidance describes special features of 
SO2 planning that influence the suitability of alternative 
means of addressing the requirement in section 172(c)(9) for 
contingency measures for SO2, such that in particular an 
appropriate means of satisfying this requirement is for the state to 
have a comprehensive enforcement program that identifies sources of 
violations of the SO2 NAAQS and to undertake an aggressive 
follow-up for compliance and enforcement.
    The state's nonattainment SIP provides that, after full 
implementation of the control strategy, contingency measures will be 
triggered if monitored ambient air quality records 1-hr SO2 
NAAQS violation in the nonattainment area, or if the nonattainment area 
fails to meet RFP. If triggered, the state will evaluate culpabilities 
for the violation and will plan to complete the investigation within 3 
months of the trigger. Where the investigation concludes unequivocally 
that SO2 emissions from one of the three sources in the 
control strategy is the cause of the recorded 1-hr SO2 NAAQS 
violation or failure to achieve RFP, the state will conduct a 
compliance evaluation and establish orders for the abatement or control 
of air pollution or make changes to the GPC, MPW, or Monsanto 
construction permits. Orders or construction permits will be issued 
within approximately 9 months of completion of the investigation and 
could include fuel switches, addition of

[[Page 40098]]

controls, curtailment of production, reducing boiler operating loads, 
or other appropriate measures necessary to mitigate the violation.
    EPA proposes to approve the state's plan for meeting the 
contingency measure requirement of CAA Sec.  172(c)(9).

VI. Additional Elements of the State's Submittal

A. Compliance With Section 110(a)(2) of the CAA

    Section 172(c)(7) of the CAA requires nonattainment SIPs to meet 
the applicable provisions of CAA Sec.  110(a)(2). While the provisions 
of 110(a)(2) address various topics, EPA's past determinations suggest 
that only the Sec.  110(a)(2) criteria which are linked with a 
particular area's designation and classification are relevant to Sec.  
172(c)(7). This nonattainment SIP submittal satisfies all applicable 
CAA Sec.  110(a)(2) criteria, as evidenced by the state's nonattainment 
new source review program which addresses 110(a)(2)(I), the included 
control strategy, and the associated emissions limits which are 
relevant to 110(a)(2)(A). In addition, on July 26, 2013, Iowa submitted 
to EPA an infrastructure SIP to demonstrate that the state has the 
necessary plans, programs, and statutory authority to implement the 
requirements of section 110 of the CAA as they pertain to the 2010 1-hr 
SO2 NAAQS. EPA will take action on the state's 
SO2 infrastructure SIP in a separate rulemaking. The EPA is 
proposing to conclude that the state has meet the requirements of CAA 
Sec.  172(c)(7).

B. Equivalent Techniques

    Section 172(c)(8) of the CAA states that upon application by any 
state, the Administrator may allow the use of equivalent modeling, 
emission inventory, and planning procedures, unless the Administrator 
determines that the proposed techniques are, in the aggregate, less 
effective than the methods specified by the Administrator.
    The state's nonattainment SIP indicates that it followed existing 
regulations, guidance, and standard practices when conducting modeling, 
preparing the emissions inventories, and implementing its planning 
procedures. Therefore, the state did not use or request approval of 
alternative or equivalent techniques as allowed under of the CAA and 
the EPA is proposing to conclude that the state's nonattainment SIP 
meets the requirements of CAA Sec.  172(c)(8).

VII. EPA's Proposed Action

    The EPA is proposing to approve the nonattainment SIP submission, 
which the state submitted to EPA on May 26, 2016, for attaining the 
2010 1-hour SO2 NAAQS for the Muscatine nonattainment area 
and for meeting other nonattainment area planning requirements. This 
SO2 attainment plan includes the state's attainment 
demonstration for the Muscatine nonattainment area. The nonattainment 
area plan also addresses requirements for RFP, RACT/RACM, base-year and 
projection-year emission inventories, and contingency measures.
    The EPA has determined that the state's nonattainment plan meets 
applicable requirements of the section 172 of the CAA (107(c)(1) 
through (9). EPA's analysis is discussed in this proposed rulemaking.
    The EPA is taking public comments for thirty days following the 
publication of this proposed action in the Federal Register. We will 
take all comments into consideration in our final action.

VIII. Incorporation by Reference

    In this rule, EPA is proposing to include in a final EPA rule 
regulatory text that includes incorporation by reference. In accordance 
with requirements of 1 CFR 51.5, EPA is proposing to incorporate by 
reference the Iowa Regulations described in the amendments to 40 CFR 
part 52 set forth below. EPA has made, and will continue to make, these 
materials generally available through https://www.regulations.gov and/
or at the EPA Region 7 Office (please contact the person identified in 
the For Further Information Contact section of this preamble for more 
information).
    Therefore, these materials have been approved by EPA for inclusion 
in the State implementation plan, have been incorporated by reference 
by EPA into that plan, are fully Federally enforceable under sections 
110 and 113 of the CAA as of the effective date of the final rulemaking 
of EPA's approval, and will be incorporated by reference by the 
Director of the Federal Register in the next update to the SIP 
compilation.\23\
---------------------------------------------------------------------------

    \23\ 62 FR 27968 (May 22, 1997).
---------------------------------------------------------------------------

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 Act 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 
proposed 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 proposed action:
     Is not a significant regulatory action subject to review 
by the Office of Management and Budget under Executive Orders 12866 (58 
FR 51735, October 4, 1993) and 13563 (76 FR 3821, January 21, 2011);
     Does not impose an information collection burden under the 
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
     Is certified as not having a significant economic impact 
on a substantial number of small entities under the Regulatory 
Flexibility Act (5 U.S.C. 601 et seq.);
     Does not contain any unfunded mandate or significantly or 
uniquely affect small governments, as described in the Unfunded 
Mandates Reform Act of 1995 (Pub. L. 104-4);
     Does not have Federalism implications as specified in 
Executive Order 13132 (64 FR 43255, August 10, 1999);
     Is not an economically significant regulatory action based 
on health or safety risks subject to Executive Order 13045 (62 FR 
19885, April 23, 1997);
     Is not a significant regulatory action subject to 
Executive Order 13211 (66 FR 28355, May 22, 2001);
     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; and
     Does not provide EPA with the discretionary authority to 
address, as appropriate, disproportionate human health or environmental 
effects, using practicable and legally permissible methods, under 
Executive Order 12898 (59 FR 7629, February 16, 1994).
    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 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 in 40 CFR Part 52

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

[[Page 40099]]

    Dated: August 9, 2017.
Edward H. Chu,
Acting Regional Administrator, Region 7.
    For the reasons stated in the preamble, EPA proposes to amend 40 
CFR part 52 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. Amend Sec.  52.820 by:
0
a. In the table in paragraph (d), adding entries ``(112)'' through 
``(169)'' in numerical order; and
0
b. In the table in paragraph (e), adding an entry ``(47)'' in numerical 
order.
    The additions 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 date   EPA approval date        Explanation
----------------------------------------------------------------------------------------------------------------
 
                                                  * * * * * * *
(112) Grain Processing           Permit No. 95-A-          12/10/15  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     374-S4.                             publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(113) Grain Processing           Permit No. 15-A-          12/10/15  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     078.                                publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(114) Grain Processing           Permit No. 79-A-          12/10/15  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     194-S2.                             publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(115) Grain Processing           Permit No. 71-A-          12/10/15  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     067-S4.                             publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(116) Grain Processing           Permit No. 75-A-          12/10/15  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     087-S1.                             publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(117) Grain Processing           Permit No. 72-A-          12/10/15  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     199-S2.                             publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(118) Grain Processing           Permit No. 74-A-          12/10/15  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     014-S1.                             publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(119) Grain Processing           Permit No. 74-A-          12/10/15  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     015-S2.                             publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(120) Grain Processing           Permit No. 75-A-            7/6/15  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     353-S2.                             publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(121) Grain Processing           Permit No. 79-A-          12/10/15  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     195-S2.                             publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(122) Grain Processing           Permit No. 80-A-          12/10/15  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     149-S5.                             publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].

[[Page 40100]]

 
(123) Grain Processing           Permit No. 80-A-          12/10/15  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     150-S5.                             publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(124) Grain Processing           Permit No. 85-A-          12/10/15  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     031-S2.                             publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(125) Grain Processing           Permit No. 85-A-          12/10/15  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     032-S2.                             publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(126) Grain Processing           Permit No. 85-A-          12/10/15  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     038-P1.                             publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(127) Grain Processing           Permit No. 85-A-          12/10/15  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     135-P1.                             publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(128) Grain Processing           Permit No. 90-A-            7/6/15  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     111-S1.                             publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(129) Grain Processing           Permit No. 91-A-          12/10/15  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     068-S2.                             publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(130) Grain Processing           Permit No. 93-A-          12/10/15  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     110-P1.                             publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(131) Grain Processing           Permit No. 92-A-            7/6/15  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     383-S2.                             publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(132) Grain Processing           Permit No. 92-A-            7/6/15  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     385-S1.                             publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(133) Grain Processing           Permit No. 94-A-          12/10/15  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     055-S1.                             publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(134) Grain Processing           Permit No. 94-A-          12/10/15  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     061-S1.                             publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(135) Grain Processing           Permit No. 02-A-            7/6/15  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     781-S2.                             publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(136) Grain Processing           Permit No. 02-A-            7/6/15  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     782-S2.                             publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].

[[Page 40101]]

 
(137) Grain Processing           Permit No. 09-A-          12/10/15  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     482-S2.                             publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(138) Grain Processing           Permit No. 10-A-          12/10/15  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     563-S1.                             publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(139) Grain Processing           Permit No. 15-A-           3/25/16  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     200.                                publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(140) Grain Processing           Permit No. 15-A-           3/25/16  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     201.                                publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(141) Grain Processing           Permit No. 15-A-          12/10/15  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     202.                                publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(142) Grain Processing           Permit No. 15-A-           2/15/16  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     203.                                publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(143) Grain Processing           Permit No. 15-A-           2/15/16  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     204.                                publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(144) Grain Processing           Permit No. 15-A-           2/15/16  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     205.                                publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(145) Grain Processing           Permit No. 15-A-           2/15/16  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     206.                                publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(146) Grain Processing           Permit No. 15-A-           2/15/16  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     207.                                publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(147) Grain Processing           Permit No. 15-A-          12/10/15  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     208.                                publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(148) Grain Processing           Permit No. 15-A-          12/10/15  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     209.                                publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(149) Grain Processing           Permit No. 15-A-           2/15/16  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     480.                                publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(150) Grain Processing           Permit No. 15-A-           2/15/16  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     481.                                publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].

[[Page 40102]]

 
(151) Grain Processing           Permit No. 15-A-           2/15/16  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     482.                                publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(152) Grain Processing           Permit No. 15-A-           2/15/16  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     483.                                publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(153) Grain Processing           Permit No. 15-A-           1/26/16  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     213.                                publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(154) Grain Processing           Permit No. 15-A-           2/15/16  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     484.                                publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(155) Grain Processing           Permit No. 15-A-           2/15/16  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     485.                                publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(156) Grain Processing           Permit No. 15-A-           2/15/16  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     486.                                publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(157) Grain Processing           Permit No. 15-A-          12/10/15  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     326.                                publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(158) Grain Processing           Permit No. 03-A-            7/6/15  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     471-S1.                             publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(159) Grain Processing           Permit No. 05-A-           2/15/16  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     926-S4.                             publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(160) Grain Processing           Permit No. 06-A-          12/10/15  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     1261-S1.                            publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(161) Grain Processing           Permit No. 11-A-            7/6/15  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     338-S1.                             publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(162) Grain Processing           Permit No. 15-A-          12/10/15  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     354.                                publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(163) Grain Processing           Permit No. 15-A-          12/10/15  [date of final      2010 1-hr SO2 NAAQ
 Corporation.                     199.                                publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(164) Muscatine Power and Water  Permit No. 13-A-            3/2/16  [date of final      2010 1-hr SO2 NAAQ
                                  152-S1.                             publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].

[[Page 40103]]

 
(165) Muscatine Power and Water  Permit No. 74-A-            3/2/16  [date of final      2010 1-hr SO2 NAAQ
                                  175-S4.                             publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(166) Muscatine Power and Water  Permit No. 95-A-            3/2/16  [date of final      2010 1-hr SO2 NAAQ
                                  373-P3.                             publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(167) Muscatine Power and Water  Permit No. 80-A-            3/2/16  [date of final      2010 1-hr SO2 NAAQ
                                  191-P3.                             publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(168) Monsanto.................  Permit No. 82-A-           5/13/15  [date of final      2010 1-hr SO2 NAAQ
                                  092-P11.                            publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
(169) Monsanto.................  Permit No. 88-A-           5/13/15  [date of final      2010 1-hr SO2 NAAQ
                                  001-S3.                             publication in      Nonattainment Plan;
                                                                      the Federal         Condition 6 of the
                                                                      Register] and       permit is not part of
                                                                      [Federal Register   the SIP; EPA-R07-OAR-
                                                                      citation].          2017-0416; FRL-XXXX-
                                                                                          Region 7].
----------------------------------------------------------------------------------------------------------------

    (e)* * *

                                   EPA-Approved Iowa Nonregulatory Provisions
----------------------------------------------------------------------------------------------------------------
                                     Applicable
   Name of nonregulatory SIP        geographic or         State       EPA approval date        Explanation
           provision             nonattainment area  submittal date
----------------------------------------------------------------------------------------------------------------
 
                                                  * * * * * * *
(47) 2010 1-hr SO2 National      A portion of               5/26/16  [date of final      EPA-R07-OAR-2017-0416;
 Ambient Air Quality Standard     Muscatine County.                   publication in      FRL-XXXX-Region 7].
 Nonattainment Plan.                                                  the Federal
                                                                      Register] and
                                                                      [Federal Register
                                                                      citation].
----------------------------------------------------------------------------------------------------------------

* * * * *

[FR Doc. 2017-17736 Filed 8-23-17; 8:45 am]
 BILLING CODE 6560-50-P