[Federal Register Volume 83, Number 126 (Friday, June 29, 2018)]
[Rules and Regulations]
[Pages 30553-30570]
[FR Doc No: 2018-13942]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R06-OAR-2017-0435; FRL-9979-15--Region 6]

Approval and Promulgation of Implementation Plans; Arkansas;
Revisions to Minor New Source Review Program

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: Pursuant to the Federal Clean Air Act (CAA or the Act), the
Environmental Protection Agency (EPA) is approving revisions to the
Arkansas State Implementation Plan (SIP) minor New Source Review (NSR)
program submitted on July 26, 2010, and March 24, 2017, including
supplemental information provided on November 30, 2015, May 26, 2016,
July 5, 2017, July 27, 2017, and March 16, 2018. Specifically, we are
proposing to approve revisions that revise the minor NSR permitting
thresholds and de minimis levels, as well as, additional non-
substantive revisions contained in those submittals. This final action
is consistent with the requirements of section 110 of the CAA.

DATES: This rule is effective on July 30, 2018.

ADDRESSES: The EPA has established a docket for this action under
Docket ID No. EPA-R06-OAR-2017-0435. All documents in the docket are
listed on the http://www.regulations.gov website. Although listed in
the index, some information is not publicly available, e.g.,
Confidential Business Information or other information whose disclosure
is restricted by statute. Certain other material, such as copyrighted
material, is not placed on the internet and will be publicly available
only in hard copy form. Publicly available docket materials are
available either electronically through http://www.regulations.gov or
in hard copy at the EPA Region 6, 1445 Ross Avenue, Suite 700, Dallas,
Texas 75202-2733.

FOR FURTHER INFORMATION CONTACT: Ashley Mohr,<PHONE_NUMBER>,
[email protected].

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

I. Background

    The background for this action is discussed in detail in our
September 18, 2017 proposal (82 FR 43506). In that document we proposed
to approve revisions to the Arkansas SIP submitted on July 26, 2010,
and March 24, 2017, including supplemental information submitted on
November 30, 2015, May 26, 2016, July 5, 2017, July 27, 2017, and March
16, 2018. The revisions addressed in our proposal included revisions to
the Arkansas minor NSR permitting thresholds and de minimis levels, as
well as, additional revisions to the minor NSR provisions that are
considered to be non-substantive.
    We received one set of comments on the proposal. The full text of
the comment letter received during the public comment period, which
closed on October 18, 2017, is included in the publicly posted docket
associated with this action at www.regulations.gov. Below the EPA
provides a summary of the comments received and corresponding
responses.

II. Response to Comments

    Comment: The commenter stated that the revised minor NSR rule fails
to provide legally enforceable procedures to ensure new sources that
could interfere with NAAQS attainment or maintenance or violate the
control strategy won't be allowed to construct. More specifically, they
stated that the minor NSR program does not explain how ``actual
emissions'' are to be determined for a new source with no operational
history. To the extent that Arkansas Department of Environmental
Quality (ADEQ) determined applicability for new sources based on
projected actual emissions, then the rule could ultimately allow
sources with emissions greater than the permitting thresholds to
construct without a permit and without evaluation of air quality
impacts by a new source underestimating emission factors and/or
operating parameters and exceeding those projected emissions after its
construction. Therefore, the commenter stated it is unclear what size
of sources could ultimately end up exempt from Arkansas' minor NSR
program. The commenter claims that because of the noted deficiencies
there is a problem with any attempt to determine whether the revised
minor NSR rule's applicability thresholds are set to the appropriate
level to ensure the state meets the applicable federal requirements
found in CAA section 110(a)(2)(C) and 40 CFR 51.160(b).
    Response: This comment is not relevant to our current rulemaking.
As shown in Section IV of the Technical Support Document that
accompanied our proposed approval action, our rulemaking only addresses
revisions to the permitting thresholds values contained in Reg. 19.401.
The applicability determination for the minor NSR program and its
reliance on ``actual emissions'' was not revised by Arkansas as part of
the July 26, 2010, or May 24, 2017 SIP revision submittals. Therefore,
the applicability determination as originally SIP-approved October 16,
2000 (65 FR 61103) remains unchanged, is not a part of this rulemaking,
and any comment on it is not relevant to the current rulemaking.
    While the comments regarding the applicability determination basis
are not relevant to this rulemaking, we will respond to the commenter's
assertion that any attempt to determine if the revised minor NSR
permitting thresholds meet the referenced federal requirements is
problematic. We do not agree with this statement. As outlined in our
proposed rulemaking, we evaluated several analyses submitted by
Arkansas in support of the revised thresholds, including an emissions
inventory analysis, a monitoring trends analysis, and a modeling
analysis. Based on our evaluation of those analyses along with the SIP
revisions submittals documentation (found in the Technical Support
Document (TSD)), we find that the proposed thresholds will meet
applicable federal requirements and not interfere with NAAQS attainment
or maintenance or violate the control strategy. As required by Reg.
19.401, a source with actual emissions greater than the applicability
thresholds would be required to obtain a permit and is subject to
enforcement action if the source fails to do so. The emissions from a
new source to be compared with the permitting thresholds would be based
on controlled emission factors and projected operations (hours of
operation and/or amounts of material processed). This approach allows
permitting applicability to be based on emissions that are close to
actual emissions. The regulation specifically does not allow
construction and operation of sources with actual emissions in excess
of the thresholds, and any source that did underestimate their
emissions and exceed the emissions thresholds would be in violation of
the regulations and beyond the scope of the analyses conducted to
demonstrate the regulation's compliance with applicable federal
requirements for minor NSR programs.
    Comment: The commenter stated that the rule exempting de minimis
changes at existing sources from permitting fails to provide legally
enforceable procedures to ensure that modified sources that could
interfere with NAAQS attainment or maintenance or violate the control
strategy won't be allowed to construct. More specifically, they stated
a physical change or change in the method of operation at a source with
no existing permit has no existing ``permitted rates'' to compare
``proposed permitted rates'' to, and the rule does not explain how
applicability is determined in such cases and the rule does not clearly
say that it applies only to sources with existing permits. In addition,
the commenter stated that Reg. 19 does not clearly require a permit
application for de minimis changes. Therefore, they claim that de
minimis exemptions rule does not meet the requirements of 40 CFR
51.160(a) of providing legally enforceable procedures.
    Response: We do not agree that the applicability of the de minimis
changes rule to existing sources with no permits is unclear. The de
minimis change provisions are found in paragraph C of Reg. 19.407 of
Arkansas' ``Minor Source Review'' regulation (Reg. 19, Chapter 4). Reg.
19.407 is titled ``Permit Amendments'' and as stated in our original
2000 approval of Reg. 19.407 (65 FR 26795; finalized at 65 FR 61103),
this section describes the procedures for amending a permit. Because
Reg. 19.407 describes permit amendments, including de minimis changes,
these provisions are not applicable to a source that does not have a
permit. Existing sources with no existing permit would be subject to
the minor NSR permitting thresholds found in Reg. 19.401 under the
``General Applicability'' section to determine if the source was
subject to minor NSR permitting requirements. In addition to the
clarity provided in the rule itself, the current ``Air Application
Instructions for Registrations, Minor Source Permits, or Title V
Permits'' made available on ADEQ's air permitting website also
indicates that de minimis applications are for ``small modifications to
a permit.'' (Pg. 5) \1\ Page 12 of the application instructions
reiterates the applicability of the de

minimis rule and states that a de minimis application ``applies to
facilities having a current air permits [sic].'' Much like the de
minimis change provisions in the rule, it is clear based on ADEQ's
current air permit application guidance that the de minimis change rule
only applies to existing permitted facilities and not new facilities.
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    \1\ Air Application Instructions available online at: https://www.adeq.state.ar.us/downloads/WebDatabases/Air/PermitData/Forms%20and%20Instructions/Form%20and%20Instructions/Air_Permit_Application_Forms_Instructions.pdf.
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    The portion of the comment raised regarding permit application
requirements for de minimis changes is not relevant to our current
rulemaking. As shown in Section IV of the Technical Support Document
that accompanied our proposed action, our rulemaking only addresses
revisions related to de minimis changes that are found in Reg.
19.407(C)(2)(a) and (b). Permit application requirements, which are
found in Reg. 19.404, are currently SIP-approved and were not revised
as part of the July 26, 2010, or May 24, 2017 SIP revision submittals
under review in this rulemaking. Similarly, Reg. 19.407(C)(7) was not
revised in the 2010 or 2017 SIP revision submittals. Therefore, the
SIP-approved Reg. 19.404 and Reg. 19.407(C)(7) provisions as most-
recently approved on October 16, 2000 (65 FR 61103) and April 12, 2007
(72 FR 18394), respectively, remain unchanged and are not part of this
rulemaking and any comment on those provisions is not relevant.
    Comment: The commenter claims that Arkansas has failed to
adequately justify the basis for its revised emission thresholds for
exempting new sources and de minimis changes from its minor NSR
program. They state that 40 CFR 51.160(e) requires states to identify
the types and sizes of sources subject to its minor NSR program and to
explain the basis for determining which facilities are subject to
review. ADEQ's justification for the emission thresholds adopted in its
minor NSR program for Reg. 19, Chapter 4, was essentially that these
tons per year thresholds were the same thresholds identified as ``de
minimis'' under major NSR permitting programs. However, there has been
no analysis with current modeling techniques that the major NSR
significance levels are adequate to ensure a modified source won't
interfere with the attainment or maintenance of all of the various
current NAAQS, which differ in stringency from the NAAQS applicable at
the time the PSD significant emission rates were developed. The
commenter also stated that the AERMOD (dispersion) modeling results,
which they believe underestimate actual impacts, indicate that the
pollutant concentrations resulting from the emissions exempt from
permitting based on the revised thresholds are significantly higher
than 4% of the NAAQS, which was a threshold for the EPA's analyses from
1980, 1987, and 2008 for demonstrating that the significant emission
levels were de minimis to the PSD program.
    Response: We do not agree with this comment. Although ADEQ did
include the data referenced by the commenter in their initial 2010 SIP
revision submittal, the basis for ADEQ's findings regarding the
appropriateness of the revised thresholds was different and they also
provided additional analyses to demonstrate the scope of the exempt
sources and modifications resulting from the revised minor NSR
permitting thresholds and de minimis change levels and to demonstrate
that the revised thresholds will not interfere with attainment or
maintenance of the NAAQS. These analyses were included in their
entirety in the March 24, 2017 SIP revision submittal and included: (1)
An emissions inventory analysis that determined the percentage of the
total statewide emissions that were to be exempt under the revised
minor NSR permitting thresholds and de minimis change levels; (2) a
monitoring trends analysis that included a review of the current status
of ambient air quality, as well as, the impacts of the revised
thresholds on ambient concentration monitoring trends in the state of
Arkansas; and (3) a modeling analysis that included photochemical and
dispersion modeling analyses that evaluated the impacts of the revised
thresholds through model predicted results. The air quality modeling
analysis report included in Appendix D of the March 24, 2017 SIP
submittal describes the modeling approach used by ADEQ as part of the
demonstration showing that the revised minor NSR permitting thresholds
and de minimis change levels will not adversely impact the current
NAAQS. Based on our review of the modeling analysis, which did use
current air quality modeling techniques, and the other analyses
completed by ADEQ, we found that the impacts resulting from the revised
minor NSR permitting thresholds and de minimis levels would not
interfere with the state's ability to maintain compliance with the
NAAQS.
    As discussed in the Technical Support Document accompanying our
proposed action, ADEQ conducted both regional scale photochemical
modeling using CMAQ and local-scale dispersion modeling using AERMOD to
examine the predicted impacts from sources or de minimis changes that
would be exempt from minor NSR permitting based on the revised
thresholds.\2\ ADEQ employed this combined modeling approach in an
effort to look at both regional and local scale impacts from emissions
equal to the revised thresholds for VOC, NOX,
SO2, CO, PM10, and PM2.5. In both the
regional- and local-scale modeling analyses, ADEQ modeled hypothetical
sources with emissions equal to the minor NSR permitting and de minimis
change thresholds and stack parameters set equal to median values based
on the 2011 National Emissions Inventory (NEI) for Arkansas sources. As
part of photochemical modeling, the maximum CMAQ-derived impacts on
daily maximum 8-hour ozone, 24-hour PM2.5, annual average
PM2.5, 1-hour NO2, 1-hour SO2, and 24-
hour PM10 were calculated. The statewide maximum impacts for
each day resulting from the hypothetical sources was added to the
unmodified future year concentration for each day and grid cell. The
resulting concentrations represented the worst-case ambient
concentrations including impacts from the threshold emission increases
at any location in Arkansas. These worst-case ambient concentrations
were then used to calculate relative response factors (RRFs) to
estimate future design values (FDVs) at both monitored and unmonitored
locations throughout Arkansas.\3\ \4\ The FDVs were compared with FDVs
without the thresholds increase impacts, as well as, the NAAQS in an
effort to determine whether emissions increases less than the minor NSR
thresholds would cause or

contribute to NAAQS violations or potentially interfere with NAAQS
maintenance. Similar to the regional-scale photochemical modeling, the
hypothetical sources modeling in the near-field dispersion modeling
analysis were modeled with emission rates equal to the minor NSR
permitting thresholds and de minimis levels and stack parameters were
set equal to median stack parameter based on the 2011 NEI data. The
maximum AERMOD-derived impacts on daily maximum 1-hr NO2,
annual average NO2, daily maximum 1-hour SO2,
daily maximum 1-hour CO, daily maximum 8-hour average CO, and 24-hour
average PM10 were calculated for each air quality control
region. The daily AERMOD-derived concentrations were added to the CMAQ-
derived concentrations for the same location, using the CMAQ values as
``background.'' ADEQ stated that the values determined for the
statewide daily maximum impacts are expected to represent the near-
field concentrations assuming worst-case impacts from threshold
emission increases at a range of locations through Arkansas. The daily
maximum worst case AERMOD impacts were added to the unmodified future
year concentration for each day and grid cell. The resulting
concentrations represented the worst-case ambient concentrations
including impacts from the threshold emission increases at any location
in Arkansas. Similar to the CMAQ-only modeling analysis, the worse-case
modeled impacts were used to calculate RRFs and FDVs. The calculated
FDVs were compared with the original unmodified FDVs and the NAAQS in
order to examine the potential impacts of the proposed minor NSR
threshold emissions on NAAQS attainment and maintenance. The modeling
conducted by Arkansas utilized current air quality modeling techniques
to demonstrate that the predicted impacts resulting from emissions at
or below the revised minor NSR permitting thresholds and de minimis
change levels, which happen to be equal in magnitude to the major NSR
significance levels, will not interfere with the attainment or
maintenance of the NAAQS current in effect at the time of the
analysis--including those that were not applicable at the time the PSD
significant emission rates were developed.
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    \2\ See Pages 31-32 of the EPA's Technical Support Document
dated August 24, 2017, which discusses the air quality modeling
analyses that were completed by ADEQ in support of the submitted SIP
revisions. In addition to the TSD, additional details regarding the
modeling analyses are located in the modeling report submitted as
part of the March 24, 2017 SIP revisions submittal, which outlines
modeling tools and techniques utilized by Arkansas along with the
results from the modeling analyses. (ADEQ's modeling report located
in the ``ADEQ 2010 Minor NSR Permitting Thresholds and De Minimis
Levels SIP Revision--Technical Support Document'' dated November
2015,)
    \3\ A RRF is the ratio of future case modeled concentrations to
base case modeled concentrations, which is used to quantify the
relative impacts of the emissions added to the model. In the
photochemical modeling conducted by ADEQ, the base case modeled
concentrations are taken from the 2015 modeling without the
hypothetical sources added while the future case modeling results
are taken from the 2015 modeling plus the 8 modeled hypothetical
sources. Therefore, the RRFs calculated in this modeling analysis
quantify the relative impacts from the additional emissions from the
hypothetical sources that would be exempt from permitting based on
the new thresholds/de minimis levels.
    \4\ RRFs can be used to estimate FDVs, which are determined by
applying the RRF ratios to monitored design values from the base
year taken from ambient monitoring data.
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    Further, the entirety of the additional analyses provided by ADEQ
in the March 24, 2017 SIP revision submittal, including the NAAQS non-
interference modeling demonstration, was the basis of the EPA's finding
that the revised thresholds were approvable. As such, a linkage to the
PSD significant emission rate values and/or comparison of modeled
impacts to percentage thresholds relied upon during the EPA's
development of the significant emission rates in 1980, 1987, and 2008
for the PSD program was not applicable to our proposed approval of the
revised minor NSR permitting thresholds and de minimis levels.
Elsewhere in this final rulemaking, we have addressed the comments
specifically made regarding the modeling techniques used by Arkansas
and restated our finding that those techniques were reasonable and
appropriate for the NAAQS non-interference demonstration required by
CAA section 110(l).
    Comment: The commenter stated that modified major sources exempted
from major source permitting under the PSD program will also be exempt
from minor source permitting under Arkansas' de minimis changes rule
and that the revised minor NSR program will not pick up the slack and
ensure protection of the NAAQS as was intended when EPA promulgated the
2002 revisions to the major source NSR rules.
    Response: The commenter is incorrect that modifications to existing
PSD major sources, which are exempt from PSD permitting, would be
exempt from minor source permitting under the de minimis change rule.
As discussed below, any change at an existing major NSR source (PSD
source) is prohibited from using the de minimis change process because
the de minimis change rule at Reg. 19.407(C) is located in Chapter 4 of
Reg. 19, which does not apply to PSD sources or any modifications at
those sources.
    The SIP-approved Arkansas NSR program is comprised of two types of
review: ``Minor Source Review'' and ``Major Source Review''. Arkansas
operates a so-called ``merged, one permit'' system, which is divided
into these two types of review based on whether a source is required to
obtain a title V operating permit. As such, ``Minor Source Review'',
which is contained in Reg. 19, Chapter 4, applies only to those sources
that are not subject to title V permitting and require only a title I
NSR authorization.\5\ All sources that are subject to title V, which
would include PSD sources, are subject to ``Major Source Review'' under
Reg. 26 provisions incorporated by reference in Reg. 19, Chapter 11.
Therefore, all permitting at PSD sources, including all modifications,
would be subject to Reg. 19, Chapter 11 ``Major Source Review'' under
the Arkansas NSR permitting program and cannot use the de minimis
change provisions, which are limited to ``Minor Source Review'' in
Chapter 4. Only those non-title V sources that are minor under the SIP-
approved definition of minor source may qualify for the de minimis
change exemption found in Reg. 19.407(C). As discussed in our proposed
rulemaking and the accompanying TSD, the emissions inventory analysis
for the de minimis changes found that the scope of changes expected to
qualify for the de minimis change exemption is very small with
emissions associated with those exempted changes making up a fraction
of a percent of statewide emissions. The range of percentage of
statewide emissions for the pollutants determined in the emissions
inventory analysis for de minimis changes was 0.0005% to 0.019%. At
these levels it would require over 50 times the NOX
emissions authorized in 2016 to approach 1% of the statewide emissions
and over 300 times the emissions for the other pollutants.
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    \5\ As stated in our original SIP approval of Chapter 4, ``[a]
minor source is any source which does not meet the requirements of a
major source. The Act in section 302(j) defines the terms ``major
stationary source'' and ``major emitting facility'' as ``any
stationary facility of source of air pollutants which directly
emits, or has the potential to emit, one hundred tons per year of
more of any air pollutant (including any major emitting facility or
source of fugitive emissions of any such pollutant, as determined by
rule by the Administrator).''
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    The state did not rely solely on the emissions inventory analysis
to demonstrate NAAQS compliance. This emissions inventory analysis was
coupled with additional analyses specifically looking at ambient
concentrations (monitoring trends analysis) and potential ambient
impacts (modeling analysis) that were completed by ADEQ as part of the
110(l) demonstration. The results from the modeling analysis indicate
that while the addition of the exempt emissions did result in slight
increases in the model predicted impacts, it did not violate the NAAQS.
As such, the modeling analysis portion of the 110(l) demonstration
shows that revised minor NSR program will continue to ensure NAAQS
protection.
    EPA's intent at the time of promulgation of the 2002 revisions to
the major source NSR rules is not relevant here. What is relevant here
is the approvability of these revisions in the context of the current
regulatory framework as promulgated. The commenter has not cited any
ambiguous regulatory language in order to justify an examination of
EPA's intent. In the absence of any ambiguity in regulatory language it
is not necessary to address EPA's intent here as there is no dispute
regarding interpretation on the applicable rules.

    Comment: The commenter stated that EPA has previously required
minor NSR programs to use much smaller emission thresholds than the
major modification significant impact levels and gave the example of
the Montana minor NSR program includes a de minimis increase exemption
threshold of 5 TPY, which was approved by EPA, after a 15 TPY threshold
that was initially set by Montana was not approved by EPA into the SIP.
    Response: In the case of Montana, which was referenced by the
commenter, the state did not provide an adequate demonstration to
support the approval of the 15 TPY exemption threshold that was
initially established by the state into the SIP. The state later
revised the threshold to 5 TPY and submitted this threshold for SIP
approval along with an analysis to show that the 5 TPY exemption would
not interfere with NAAQS attainment or maintenance or violate the
control strategy. Based on the revised submittal and supporting
information, EPA approved the lower threshold of 5 TPY into the Montana
SIP. Our proposed approval of the de minimis change levels in Arkansas
does not contradict the previous Montana approval. In fact, our
proposed approval mirrors the Montana SIP approval in that we requested
analyses from Arkansas as part of the 110(l) demonstration for the
revised de minimis change levels and our approval is based on those
analyses as documented in the proposed rulemaking. Specifically, we
found that Arkansas' documentation adequately demonstrates that these
revised thresholds will not interfere with NAAQS compliance. Our
approval of one de minimis exemption threshold level in one state does
not preclude the approval of a different threshold in another state.
Each state's universe of minor NSR sources, meteorology, and ambient
air quality conditions are unique and influence the types of exemptions
that would not interfere with the minor NSR program's ability to meet
the applicable federal requirements.
    Comment: The commenter stated that the de minimis change rule
contradicts with how applicability is determined under PSD permitting
requirements and thus fails to ensure projects that should be required
to obtain a PSD permit will not be instead considered a de minimis
change under Reg. 19.407(C). They also state that EPA must disapprove
the current submittal and require Arkansas to revise its de minimis
rule and relevant definitions rule to clearly state that changes that
are considered major modifications under the PSD permitting regulations
cannot be considered as de minimis changes. Without such language
clearly stated, the Arkansas minor NSR program could allow sources that
would otherwise be subject to PSD permitting to improperly avoid major
source PSD permitting requirements for a major modification. The
commenter also states that EPA must disapprove the version of Reg.
19.407(C) currently approved into the SIP which EPA has reopened with
this action to the extent the provisions could interfere with
compliance with the PSD permitting regulations.
    Response: We agree with the commenter that changes that are
considered major modifications under the PSD permitting regulations
cannot be considered as de minimis changes. However, the commenter is
incorrect that the revisions to the de minimis change provisions will
interfere with proper implementation of the PSD permitting
requirements. As previously stated in our responses, the de minimis
change rules contained in Chapter 4 of Reg. 19 cannot be used for any
changes at PSD sources/modifications. Therefore, our proposed approval
of revisions to Chapter 4, including the de minimis change rule, will
not impact PSD permitting implementation. Changes that are considered
major would be subject to permitting under Reg. 26 is incorporated by
reference in Chapter 11, which utilizes an actual-to-projected actual
test for modifications to existing units and an actual-to-potential
test for new units, are not exempted from the requirements of Chapter
11 by the provisions we are approving in this rulemaking. As noted in
Section IV of the TSD, we are not taking action on any portion of
Chapter 11 and the requirements of that chapter, which mainly
incorporate by reference the requirements of the federal PSD program at
40 CFR 52.21, remain in effect.
    Regarding the commenter's statement that EPA should take action to
disapprove Reg. 19.407(C) as it is currently approved into the SIP,
aside from the revisions to 407(C)(2)(a) and 407(C)(2)(b) which are
clearly annotated in Section IV of the TSD, the other portions of Reg.
19.407 are not being revised by our current rulemaking.\6\ Therefore,
the other SIP-approved portions of Reg. 19.407 will remain unchanged by
our rulemaking. As previously stated in our responses, any comment on
provisions that are not being revised as part of our rulemaking is
irrelevant to this action. Further, our current rulemaking does not
reopen the current SIP-approved and unchanged provisions for any
action, including disapproval.
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    \6\ Reg. 407(C)(2)(a) and (b) contain the de minimis change
emissions and air quality impacts thresholds.
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    Comment: The commenter stated that because the minor NSR revisions
could allow for increased deterioration in air quality over PSD
baseline concentration the EPA cannot approve such a SIP revision
without a demonstration that it will not cause or contribute to a
violation of the applicable PSD increment. The commenter listed the
following as chances for increased deterioration resulting from the SIP
revision: (1) The minor NSR SIP revisions submitted by ADEQ allow for
an increase in allowable emission rates to occur under the de minimis
provisions of Reg. 19.407(C)(7); (2) Reg. 19.417 allows sources
currently holding permits pursuant to Reg. 19 but whose emissions are
below the permitting thresholds to submit a registration request under
Reg. 18.315, which is a state-only rule and not part of the SIP, and
request that their permit containing federally enforceable requirements
be terminated; and (3) to the extent ADEQ ensures compliance with the
PSD increment as part of its minor NSR program, the relaxation in the
sizes of sources and modifications subject to minor NSR permitting also
could allow increased deterioration of air quality above baseline
concentration. The commenter also stated that the modeling analysis
provided by ADEQ to support approval of the minor NSR relaxations
included violations of the Class I and Class II PM10
increments that were predicted due to the increased emissions
thresholds that would exempt from minor NSR review under the proposed
SIP revision, which indicates that an unpermitted source pursuant to
the expanded exemptions from Arkansas' minor NSR could cause an
exceedance of the PM10 increment. The commenter also stated
that pursuant to CAA section 110(l) and 40 CFR 51.166(a)(2), EPA cannot
approve a SIP submittal which admittedly allows a violation of the PSD
increments.
    Response: We agree with the commenter that the revisions to the
Arkansas minor NSR program do allow larger increases in allowable
emissions to be authorized via the de minimis change rule by increasing
the de minimis change thresholds. We also agree that the revisions
allow currently permitted sources with emissions that fall between the
old minor NSR permitting thresholds and the revised permitting
thresholds to submit a registration under Reg. 18.315 and request that
their Reg. 19 permit be

terminated. However, the applicable legal test for determining
approvability of these revisions, which revise the minor NSR program so
that it becomes less stringent, is the requirement of CAA section
110(l), EPA cannot approve a revision to the SIP if it interferes with
applicable requirements of the Act. The PSD increment requirement found
at 40 CFR 51.166(a)(2) is inapplicable here because it is required to
be met by a major source/major modification application, not a minor
NSR permitting application. The major source/major modification
application must show that the PSD increment is not violated and the
applicant's modeling must include the emissions from all of the nearby
minor sources, as well as any other nearby major sources. If the major
source/major modification modeling shows the PSD increment will be
violated by the proposed construction/modification, then the major
source/major modification must reduce its requested emissions or obtain
reductions from the other sources impacting the increment. Because the
burden of not violating the PSD increment is placed on the source
subject to PSD, the PSD increment requirement does not apply to a minor
NSR permitting SIP. As stated previously in our responses to the
commenter, the PSD increment requirements are contained in the PSD
rules under 40 CFR 51.166 and apply only to sources subject to PSD.
They do not apply to minor sources. Therefore, an increment analysis
would only be required to be completed as part of a PSD permitting
action (Reg. 19, Chapter 9) and would be a separate analysis than that
completed as part of the NAAQS demonstration. Further, the air quality
modeling that was conducted by Arkansas was conducted for NAAQS
compliance demonstration purposes as part of the 110(l) non-
interference demonstration. (See the March 24, 2017 SIP Revision
Submittal, Appendix D--Air Quality Modeling Analysis of Minor Source
Permit Thresholds.) Because the PSD increment analysis and NAAQS
analysis serve separate and distinct purposes, these analyses use
different modeling approaches and often different model inputs.
Therefore, a modeling demonstration conducted for NAAQS compliance
cannot be relied upon to make a modeled PSD increment analysis
determination, such as if a PSD increment violation exists. Therefore,
we do not agree with the commenter that the NAAQS modeling indicates
that the proposed SIP revision allows a violation of the PSD
increments. We also do not agree that the modeled PM10
impacts exceed the referenced increments because the state's modeling
analysis did not include a PSD increment analysis for comparison with
the PSD increments to determine if a predicted exceedance occurred. In
addition, we reiterate that a PSD increment analysis is not necessary
as part of a 110(l) analysis to support revisions to a minor NSR
permitting program, since the federal PSD increment analysis
requirement at 40 CFR 51.166(a)(2) is not applicable to minor NSR
programs.
    Comment: The commenter stated that a comparison of emissions that
could be exempt from the relaxed minor NSR with total statewide
emissions across the state of more than 53,000 square miles does not
give any indication of whether the exempted emissions would interfere
with attainment or maintenance of the NAAQS or increments. As such, the
commenter stated that the emissions comparison analysis does not
provide information relevant to whether the relaxations to Arkansas'
minor NSR program will interfere with attainment or maintenance of the
NAAQS or any other CAA requirement.
    Response: We do not agree with the commenter that the emissions
inventory analysis for the emissions exempt from minor NSR permitting
based on the revised permitting thresholds does not provide information
that is relevant to the 110(l) analysis. This analysis serves to
determine the scope, or portion of emissions that would not undergo
minor NSR permitting requirements relative to the statewide emissions.
The approach to determine the scope is independent of the physical size
of the state since the emissions inventory analysis was conducted to
compare exempt emissions with the statewide emissions inventory. As
detailed in our proposed rulemaking the scope of emissions anticipated
to be exempt from minor NSR permitting by the revised permitting
thresholds was minimal. The pollutant-based emissions inventory
analysis showed that the scope of emissions exempt from permitting
based on the revised permitting thresholds ranged from 0.006% to 0.125%
of the total statewide emissions. This analysis clearly demonstrates
that the magnitude of emissions that would be exempt from minor NSR
permitting program makes up an extremely small portion of the statewide
emissions. The state did not rely solely on the emissions inventory
analysis to demonstrate NAAQS compliance. This emissions inventory
analysis was coupled with additional analyses specifically looking at
ambient concentrations (monitoring trends analysis) and potential
ambient impacts (modeling analysis) that were completed by ADEQ as part
of the 110(l) demonstration. The modeling trends analysis looked
specifically at the current status of ambient air quality and the
trends in ambient concentrations since the 2008 state adoption and on-
going implementation of the revised minor NSR permitting thresholds.
The modeling analysis examined the potential impacts of the exempt
emissions on ambient air quality via local and regional air quality
modeling. (See the March 24, 2017 SIP Revisions Submittal Appendix C--
2010 Minor NSR Permitting Thresholds and De Minimis Levels SIP
Technical Support Document and Appendix D--Air Quality Modeling
Analysis of Minor Source Permitting Thresholds. Monitoring analysis is
discussed on pages 3-17 of Appendix C. Modeling analysis is discussed
on pages 17-25 of Appendix C and pages 1-35 of Appendix D.) Regarding
interference with increments, we previously responded regarding the
non-applicability of PSD increment requirements to the 110(l) analysis
completed for this rulemaking.
    Comment: The commenter stated that ADEQ's emissions analysis was
incomplete because it analyzed sources with allowable emissions less
than the emission thresholds of Reg. 19.401 when the exemptions for new
sources are not based on ``allowable emissions,'' but instead are based
on ``actual emissions.'' The commenter also claimed the analysis was
incomplete because it does not project total emissions that might be
exempt from minor NSR in the future and instead reflects on sources
that may request permits to be revoked because they are no longer
subject to minor NSR permitting requirements found in Reg. 19, Chapter
4.
    Response: We do not agree with the commenter that the emissions
inventory analysis conducted for the permitting thresholds exemptions
was incomplete. In their analysis, ADEQ compiled a complete list of all
currently permitted minor NSR sources and determined which currently
permitted sources would not be required to obtain a permit based on the
revised permitting thresholds. It is important to note that this
analysis included the review of all currently permitted facilities in
the minor NSR program which spanned the entirety of the program--
meaning all active minor NSR permits that had been issued by ADEQ. EPA
originally SIP-approved the Arkansas construction permitting
requirements in October

1976 (effective November 1976).\7\ This means that ADEQ looked at all
minor NSR permits that had ever been issued and were still active. To
determine the percentage of emissions exempt from permitting, the
permitted emission rates were totaled for each pollutant and compared
with the total emissions from the statewide emissions inventory. The
state's analysis based on the permitted allowable emissions is more
conservative than the use of actual emissions for those permitted
sources since they represent the maximum permit allowable emissions for
the particular source. In most cases, the actual emissions would be
less than the allowable emissions because of actual operations at less
than maximum levels during a given calendar year and because of non-
operational periods that may have taken place. If the state had further
refined their analysis to determine the historical actual emissions
emitted by the currently permitted sources which would not be required
to be permitted under the new thresholds and compared the total actual
emissions with the total statewide emissions inventory, the actual
emissions would be expected to make up an even smaller fraction of the
total statewide emissions.
---------------------------------------------------------------------------

    \7\ EPA originally approved the Arkansas requirements for
permitting the construction of new and modified sources, which were
contained in the Regulation of Plan (ROP) Section 4--Permits, on
October 5, 1976, effective November 4, 1976. (41 FR 43904) EPA later
approved the recodification of the permitting requirements for minor
sources from ROP Section 4 into Regulation 19, Chapter 4--Minor
Source Review on October 26, 2000, effective November 15, 2000. (65
FR 61103)
---------------------------------------------------------------------------

    As stated above, Arkansas conducted the emissions review as a part
of the 110(l) demonstration to determine the scope of emissions that
were previously subject to minor NSR permitting that would be exempt
from permitting under the revised thresholds. As stated above, Arkansas
reviewed their entire minor NSR permitting universe, which included all
active permits that had historically been issued by ADEQ, to determine
the currently permitted emissions that would be exempt from minor NSR
permitting under the revised permitting thresholds.\8\ They found that
the magnitude of currently permitted emissions that would be exempt
from minor NSR permitting was a fraction of a percent of the total
emissions in the statewide emissions inventory. (The range of
calculated percentages by pollutant was 0.006% to 0.125%.) While
emissions will be exempt in the future, the emissions inventory
analysis shows the percentage of statewide emissions that were exempt
from permitting for the entire minor NSR program based on the revised
permitting thresholds indicates that the magnitude of emissions exempt
from minor NSR permitting in the future will continue to make up a
small fraction of the total statewide emissions. In addition, the
state's regulations require that a source exempt from minor NSR
permitting based on the new revised permitting thresholds but with
emissions greater than the previous thresholds obtain a registration in
accordance with Reg. 18.315, which allows ADEQ to keep track of the
sources exempt as a result of the new thresholds. In addition to the
emissions inventory analysis, Arkansas provided additional analyses,
both monitoring and modeling, to further show the limited potential
impacts of the revised minor NSR permitting thresholds. The monitoring
analysis examined statewide ambient air quality data since the adoption
of the revised minor NSR permitting thresholds in 2008 for CO,
NOX, SO2, VOC, and PM10, including the
examination of trends in design values (DVs). Since adoption of the
revised thresholds, the DVs remain unchanged or show downward
thresholds since the 2008 adoption of revised thresholds.\9\ The
modeling analysis included regional-scale photochemical and local-scale
air dispersion modeling to examine the potential impacts from emissions
exempt from minor NSR permitting based on the revised thresholds. (See
the March 24, 2017 SIP Revision Submittal, Appendix D--Air Quality
Modeling Analysis of Minor Source Permit Thresholds.) As expected, both
the regional and local modeling indicated some increases in model
predicted concentration as a result of adding the exempt emissions into
the modeled emissions inventory. However, for all pollutants and
averaging period, the resulting ambient concentrations were less than
the corresponding NAAQS. As stated in our proposed rulemaking, we find
that the analyses submitted by Arkansas as part of the 110(l)
demonstration show that the revised thresholds will not interfere with
attainment or maintenance of the NAAQS.\10\
---------------------------------------------------------------------------

    \8\ Ibid.
    \9\ The Springdale ozone monitor was the only exception and
showed increased DVs since 2008. ADEQ did further evaluation of the
Springdale monitor and determined that the increase in the monitored
ozone DVs at this monitor are likely due to the increase in mobile
emissions in the Fayetteville-Springdale-Rogers MSA as a result of
rapid population growth in that area (population grew by over 65,000
people in the 2007-2014 timeframe. The monitoring trends analysis
included in the March 24, 2017 SIP submittal indicated that the
2012-2014 DV at the Springdale monitor was 67 ppb (as compared with
the 2008 and 2015 O3 NAAQS of 75 and 70 ppb,
respectively).
    \10\ EPA's review of the monitoring and modeling analyses is
detailed in Pages 27-33 of the Technical Support Document that
accompanied our proposed rulemaking and if available in the docket.
---------------------------------------------------------------------------

    Comment: The commenter stated that the emissions inventory analysis
of the de minimis increases allowed (based on the 2016 de minimis
approvals) is not persuasive because, the increased de minimis
thresholds have not yet been approved as part of the SIP, and thus it
is not reasonable to assume that all sources that might take advantage
of this rule did take advantage of this rule in 2016. The commenter
also states that because the revised minor NSR permitting thresholds
and de minimis levels have not been approved as part of the SIP, the
state cannot infer anything in the monitoring trends analysis regarding
the impacts of the revised minor NSR rules on air pollutant
concentrations from reviewing past monitoring data and trends since it
is likely that sources would be unwilling to rely on the revised values
prior to SIP approval.
    Response: We do agree with the commenter's claims that the SIP
approval status of the revised minor NSR permitting thresholds and de
minimis change levels impacts the validity or persuasiveness of the
data included in the emissions inventory and monitoring trends
analyses. While the revised de minimis change rule provisions are not
approved into the current Arkansas SIP, they are adopted by the state
into the state regulations and thereby state law. The CAA requires
states to adopt, after reasonable notice and public hearings, revised
regulations for submission to EPA as SIP revisions. (See CAA
110(a)(1)). Since adoption of the revised permitting thresholds and de
minimis change levels into their states regulations, Arkansas has been
implementing those revised levels through the issuance of Reg. 18
registrations and de minimis change approvals. Lookback information
regarding the historical de minimis change approvals was specifically
cited in the emissions inventory analysis portion of the 110(l)
demonstration. The calendar year (CY2016) de minimis change approvals
included approval issued based on the revised thresholds that were
adopted as state law December 2008 (effective January 2009). ADEQ has
subsequently provided more information regarding the number of Reg. 18
registrations (issued to those sources exempt from minor NSR permitting
with emissions that fall within the old and revised permitting

thresholds) submitted and de minimis change approvals issued since the
adoption of the revised regulations. This additional lookback
information clearly indicates that sources have been utilizing the
revised thresholds--75 registrations have been submitted since the
permitting thresholds were revised and 476 de minimis change actions
have taken place since 2010.\11\ Because state law requires that if a
source used either the minor NSR permitting thresholds or de minimis
changes levels to avoid minor NSR permitting the source must submit the
required registration (in accordance with Reg. 19.417 and Reg. 18.315)
or obtain the required approval (in accordance with Reg. 19.407(C)(6)),
a source not accounted for in the lookback information provided by ADEQ
would have been, and still is, in violation of state law. Furthermore,
ADEQ has indicated that since the adoption of the revised minor NSR
permitting thresholds and de minimis change levels, they are not aware
of any instance where a source has been unwilling to utilize the
revised thresholds because of the status of the revisions with respect
to the SIP.\12\ Based on the historical information provided, we find
that the data included in the emissions inventory and monitoring trends
analyses is valid and reflects the reality and do not agree with the
commenter that nothing can be inferred from those analyses regarding
the impacts of the revised minor NSR permitting thresholds and de
minimis levels. Following adoption of the revised permitting thresholds
and de minimis change levels in 2008, Arkansas began implementing the
revised provisions (at the owner or operator's own risk of federal
enforcement) to exempt qualifying sources from minor NSR permitting
requirements. The persuasiveness of data used in the monitoring trends
analysis is not dependent on the SIP approval status.
---------------------------------------------------------------------------

    \11\ The number of Reg. 18 registrations submitted and de
minimis change actions provided via emails received from Ms. Tricia
Treece, ADEQ, on July 5, 2017.
    \12\ Information regarding source inquiries to utilize SIP-
approved thresholds instead of revised thresholds provided during
telephone discussion between Ms. Ashley Mohr, EPA, and Mr. Thomas
Rheaume and Ms. Tricia Treece, ADEQ, on March 16, 2018.
---------------------------------------------------------------------------

    Comment: The commenter stated that the de minimis exemption is
based on a comparison of allowable emissions increases, thus it could
allow larger increases in actual emissions than the tpy emissions
thresholds in Reg. 19.407(C). Thus, the commenter states that any
analysis, including the emissions inventory analysis, presented by ADEQ
about the thresholds is not sufficient to ensure that the actual
emissions increases allowed by the de minimis exemption will not
threaten NAAQS attainment or maintenance or otherwise interfere with
the control strategy. Similarly, the commenter also stated that the
photochemical modeling also did not model the true increase in
emissions that could be allowed--the actual emissions increases
resulting from a de minimis change could be significantly higher than
the de minimis levels and the actual emissions from a new source could
exceed projected actuals that were used as a basis to exempt the source
from permitting.
    Response: We do not agree with the commenter that the emissions
inventory analysis and modeling analysis provided by ADEQ is not
sufficient to support the proposed revisions to the de minimis change
levels. Also, we do not agree with the commenters that the analysis
provided by Arkansas did not model the true increase in emissions that
could be allowed under Arkansas' relaxed minor NSR program (i.e., those
emissions exempt from minor NSR permitting requirements based on the
revised permitting thresholds and de minimis change levels) under the
revised minor NSR program. As stated in our proposed rulemaking, the de
minimis change levels listed in Reg. 19.407(C)(2)(a) are the maximum
increases in permitted emission rates that can be exempt from minor NSR
permitting requirements via the de minimis change rule. As such, to
demonstrate that the proposed SIP revision resulting in revised de
minimis change levels will not interfere with NAAQS compliance, it is
reasonable that the 110(l) demonstration should evaluate the projected
impacts resulting from the maximum emission increases allowed by the
revised rule (i.e., the de minimis change levels). As documented in the
modeling report submitted as part of the March 24, 2017 SIP revision
submittal, Arkansas did follow this approach in their 110(l)
demonstration and evaluated the impacts resulting from emission rates
equal to the de minimis change levels. (See the March 24, 2017 SIP
Revision Submittal, Appendix D--Air Quality Modeling Analysis of Minor
Source Permit Thresholds.) When a source seeks authorization for a
proposed change at a facility via the de minimis change provision, they
are requesting authorization specifically for the increase in the
permitting emission rates. The previously permitted emission rates
underwent a previous minor NSR permitting review and were demonstrated
to be in compliance with the NAAQS. Evaluation of emissions accounted
for in the pre-de minimis change permitted emission rates, which were
previously authorized and evaluated for NAAQS compliance under an
existing permit, are beyond the scope of the 110(l) analysis for the
revised de minimis change levels. Therefore, a NAAQS demonstration
associated with the potential impacts from a de minimis change should
be based on the magnitude of increases in the permitted emission rates,
which are being authorized via the de minimis change rule. With respect
to the photochemical modeling, the purpose of the modeling analysis
submitted by Arkansas was to demonstrate that those emissions exempt
from permitting based on the revised thresholds would not cause a NAAQS
violation.
    In the case of a new source that has actual emissions in excess of
the minor NSR permitting thresholds without an issued permit
authorizing those emissions, the source would be in violation of the
minor NSR permitting requirements contained in Reg. 19, Chapter 4, and
they could be subject to an enforcement action. For example, if a
source was initially constructed as a seasonal source with emission
below the de minimis levels, it is exempt from permitting. However, if
the source's actual emissions rise above those levels without first
obtaining a permit, it would be in violation of minor NSR. It is
reasonable (for the purposes of demonstrating compliance with 110(l))
to assume a new source would be required to obtain a permit to
authorize the emissions and demonstrate they will not cause or
contribute to a violation of a NAAQS if they have actual emissions
above the minor NSR permitting thresholds. Therefore, the scenarios
involving potentially violating sources are not a reasonable scenario
to be included in an analysis conducted to support the minor NSR
permitting thresholds.
    In the case of a de minimis change, the emissions exempt from minor
NSR permitting by the de minimis change rule are the increases in the
permitted emission rates. For the de minimis revisions to be approvable
the analysis should demonstrate that the increases in the permitted
emissions will not cause a NAAQS violation. By modeling the minor NSR
permitting thresholds and de minimis change levels for each pollutant,
Arkansas did evaluate the prospective impacts associated with the
emission levels that could qualify for exemption from minor NSR
permitting requirements under the revised rule.

    Comment: The commenter stated that the analysis of the de minimis
increases allowed (based on the 2016 de minimis approvals) is not
persuasive because 2016 only reflects one year of implementation and
this rule will be in effect for the foreseeable future.
    Response: We do not agree with the commenter that the emissions
inventory analysis for the de minimis changes is not persuasive because
it is limited to 2016. CY2016 provides a portion of time when the
revised thresholds were being relied upon by owners and operators in
Arkansas. The review of emissions associated with de minimis changes
limited to CY2016 found that the 2016 emissions inventory analysis
shows the percentage of statewide emissions exempt by the de minimis
change levels in the range of 0.0005 to 0.019%. While the analysis was
limited to one calendar year, as discussed in our proposal, at these
percentage levels it would require over 50 times the NOX
emissions authorized in 2016 to approach 1% of the statewide emissions
and over 300 times the emissions for the other pollutants. In addition,
this analysis conservatively did not account for any emissions
decreases occurring as part of the approved de minimis changes. In
addition, the analysis for 2016 was conservative in that it did not
account for emissions decreases that did occur as part of the de
minimis changes. We believe that additional analysis beyond one
calendar year is unnecessary because the CY2016 data, that did not
account for any associated emissions decreases, shows that exempt
emissions makes up such a small fraction (much less than 1% for all
pollutants) of the total statewide emissions.
    Comment: The commenter restates that a comparison of emissions that
could be exempt from minor NSR permitting based on the revised de
minimis change levels with total statewide emissions does not give any
indication of whether the exempt emissions would interfere with
attainment or maintenance of the NAAQS because of the various factors
(such as: Stack parameters, operational stages, topography, and
meteorology) that dictate ambient impacts. Because of the variability
of these factors between sources, the commenter stated that the fact
that two sources have similar annual emissions is not a rational basis
to claim that they have similar ambient impacts.
    Response: We do agree with the commenter that a variety of factors
may dictate ambient impacts, and that reliance on the state's emissions
inventory analysis does not demonstrate non-interference with the
NAAQS. Instead, the emissions inventory analysis serves to determine
the scope, or portion, of emissions that would not undergo minor NSR
permitting based on the revised thresholds. However, the state did not
only rely upon the emissions inventory analysis to demonstrate NAAQS
compliance. The state addressed ambient concentrations and potential
ambient impacts by looking specifically at the current status of
ambient air quality, the historical ambient air quality trends since
adoption in 2008 and the on-going implementation of the revised de
minimis levels, and the potential impacts of the exempt emissions on
ambient air quality via local dispersion (AERMOD) and regional
photochemical (CMAQ) air quality modeling. As previously discussed in
our responses, the monitoring analysis shows that since the adoption
and implementation of the revised permitting thresholds and de minimis
change levels the overall trends in DVs are either unchanged or
decreasing. Meanwhile, the local and regional modeling analyses show
that model predicted concentrations resulting from the addition of the
emissions exempt from permitting remain less than the NAAQS. (See the
March 24, 2017 SIP Revision Submittal, Appendix D--Air Quality Modeling
Analysis of Minor Source Permit Thresholds.) While the emissions
inventory analysis served to determine the scope, or portion of
emissions that would not undergo minor NSR permitting requirements
based on the revised de minimis change levels relative to the statewide
emissions, the monitoring and modeling analyses completed as part of
the 110(l) analysis accounted for the various factors cited by the
commenter in evaluating the impacts of the revised de minimis levels.
Specifically, the results from the air quality modeling analyses were
impacted by the following factors, which are included as air quality
model inputs: Emissions, stack parameters, topography and meteorology.
    Comment: The commenter stated that there are numerous other factors
that came into play during the same timeframe that could cause
pollutant concentrations to decrease in the timeframe right after the
December 2008 adoption of the minor NSR rule relaxations, including:
The Great Recession began in 2007 and continued through 2009; natural
gas prices dropped significantly and renewable sources of power
generation became more competitive, reducing demand for coal-fired
power plants which was replaced by gas turbines and renewables; various
vehicle emission and liquid fuel standards came into effect; and less
fuel efficient vehicles were replaced with more fuel efficient
vehicles. The commenter stated that these factors make it very
difficult for ADEQ to infer anything regarding the relaxations to its
minor NSR program through the review of how air monitoring design
values have changed over time.
    Response: We agree that the monitoring data reflects not only the
impacts of the revised thresholds and de minimis levels, but other
factors such as those cited by the commenter as well. However, the
monitoring analysis does show that since Arkansas' adoption in 2008 and
ongoing implementation of the revised values, the monitored ambient
concentration data shows no NAAQS issues along with overall decreasing
trends in DVs for some pollutants indicative of improved air quality
since 2008. The monitoring analysis submitted by Arkansas spanned eight
years of ambient data (2007-2014, which includes and extends beyond the
time period referenced as ``the Great Recession'' by the commenter).
The 8-year period covered in the ambient monitoring study is a
reasonable and representative period of time to examine the impacts of
the revised thresholds while also accounting for the variability in the
other factors that may contribute to ambient concentrations. Further,
we would like to point out that a NAAQS demonstration, including
demonstrations of non-interference with attainment or maintenance of
the NAAQS under section 110(l), should reflect ambient air quality as a
whole, which would take into account the impacts on ambient
concentrations resulting from the revised minor NSR regulations, as
well as, the other factors mentioned by the commenter. As shown in the
referenced monitoring analysis, the resulting ambient concentrations
including the impacts from the minor NSR program revisions do not
indicate NAAQS compliance issues. As stated in our proposal, the
monitoring trends analysis is one part of the demonstration provided by
Arkansas that supports the finding that the revised permitting
thresholds and de minimis levels will not adversely impact NAAQS
attainment or maintenance. In addition to the monitoring analysis, the
modeling analysis is an important element of the NAAQS compliance
demonstration and as discussed in our proposed rulemaking and previous
responses, the modeling results indicate that the addition of the
emissions exempt from minor NSR permitting requirements will

not interfere with NAAQS compliance. (See the March 24, 2017 SIP
Revision Submittal, Appendix D--Air Quality Modeling Analysis of Minor
Source Permit Thresholds.)
    Comment: The commenter stated that because the state does not have
a monitoring network that covers all pollutants and all areas of the
state where industrial sources are constructing and operating, a review
of the monitoring data from Arkansas monitors provides an incomplete
picture of the NAAQS attainment status around the state.
    Response: We do not agree that Arkansas' submittal provided an
incomplete picture of NAAQS attainment around the state. The ambient
monitoring analysis was one part of the demonstration provided by the
state to meet the 110(l) requirement. The monitoring trends analysis
discussion included in Appendix C of the March 24, 2017 SIP revision
submittal includes a figure showing the Arkansas Ambient Air Monitoring
Network. This network includes ambient monitoring for the NAAQS \13\ at
monitoring sites located throughout the state in accordance with
federal requirements.\14\ The State of Arkansas' ambient air monitoring
network is reviewed each year to ensure the air quality surveillance
system continues to meet applicable requirements. The most recent
review of the ambient air monitoring network for Arkansas, the 2017
Annual Monitoring Network Plan, was reviewed and approved by EPA on
October 3, 2017, as meeting the requirements of 40 CFR and its
appendices. The analysis of the available monitoring data does provide
valuable information about the current ambient air quality in the
state, and the historical trends analysis of the data shows that since
the adoption in 2008 and the ongoing implementation of the revised
exemption thresholds, ambient air quality has not been adversely
impacted. In fact, as discussed in our proposed rulemaking, for several
pollutants the ambient air quality has shown continued improvements
since the state adoption and implementation of the revised thresholds.
This information was supplemented by the additional analyses conducted
by Arkansas, one of which specifically addresses the comment regarding
the completeness of the picture of attainment status around the state.
As discussed in our proposed rulemaking, Arkansas completed a modeling
analysis to determine the potential impacts from sources exempt from
permitting based on the revised minor NSR permitting thresholds and de
minimis change levels, which included statewide modeling. (See the
March 24, 2017 SIP Revision Submittal, Appendix D--Air Quality Modeling
Analysis of Minor Source Permit Thresholds.) Arkansas conducted
photochemical modeling to support the revised thresholds based on a
previous statewide modeling effort conducted for the 2008 base year and
the 2008/2015 future year scenarios. For the minor NSR thresholds
analysis, the future year (2015) emissions inventory was modified to
include eight hypothetical point sources that were distributed
throughout the state's Air Quality Control Regions. The emission rates
for each of the hypothetical sources were set equal to the revised
minor NSR permitting thresholds and de minimis levels. The statewide
maximum impacts for each day resulting from the hypothetical sources
was added to the unmodified future year concentration for each day and
grid cell. The resulting concentrations represented the maximum ambient
concentrations including impacts from the threshold emission increases
at any location located throughout Arkansas. While the results from the
photochemical modeling showed that while the addition of the
hypothetical source emissions may increase the predicted concentrations
within most grid cells, the calculated FDVs were still less than each
of the NAAQS at each monitoring site. (See the March 24, 2017 SIP
Revision Submittal, Appendix D--Air Quality Modeling Analysis of Minor
Source Permit Thresholds.)
---------------------------------------------------------------------------

    \13\ EPA has set National Ambient Air Quality Standards for six
principal pollutants, called criteria pollutants: Carbon Monoxide
(CO), Lead (Pb), Nitrogen Dioxide (NO2), Ozone
(O3), Particulate Matter (PM), and Sulfur Dioxide
(SO2), as indicated in 40 CFR part 50 and appendices.
    \14\ See 40 CFR part 58 and its appendices for federal
requirements related to measuring ambient air quality and for
reporting ambient air quality data and related information.
---------------------------------------------------------------------------

    Comment: The commenter stated that it is not appropriate to rely on
a modeling assessment intended to estimate future pollutant
concentrations out to 2015 to assess whether Arkansas' relaxed minor
NSR program will interfere with attainment or maintenance of the NAAQS.
The commenter based their statement on the possibility that some of the
rules that were relied on for the 2015 emission inventories could go
away, the possibility of an economic boom in the state, the possibility
of growth in a certain type of industry, or a combination of these
events, which in turn could result in the approval of this SIP
relaxation interfering with attainment or maintenance of the NAAQS in
the future despite the CMAQ (photochemical) modeling predictions for
2015.
    Response: We do not agree with the commenter that the use of the
future year (FY) modeling for 2015 is not appropriate.\15\ Arkansas
submitted several analyses as part of the 110(l) demonstration, with
the modeling assessment being one part of the demonstration submitted
to support the proposed revisions to the Arkansas SIP. As such, our
determination regarding the approvability of the SIP revisions relied
on the combined demonstration and not just one element. Regarding the
use of the future year modeling, Arkansas used this modeling in
combination with the baseline modeling to determine RRFs both with and
without the hypothetical exempt sources to calculate FDVs) \16\ \17\
\18\ These FDVs were used to compare and contrast those DVs and
determine the potential impacts of the exempt sources. This approach
allowed for a quantitative comparison to determine what potential
impacts would be expected from the

additional emissions associated with sources and/or de minimis changes
that would be exempt from minor NSR permitting requirements based on
the revised thresholds. The quantitative comparison provided
information regarding relative difference in impacts both with and
without the newly exempt emissions compared with the NAAQS. When
conducting future year modeling, informed assumptions must be made and
some of these assumptions may differ from the actual real world
conditions present when the future year becomes the present.\19\
However, it is important to note that the future year modeling approach
was conducted in order to quantify the relative change in ambient
concentrations resulting from the added potential impacts from the
newly exempt sources using RRFs. Specifically, this analysis results in
the calculation of FDVs both with and without the hypothetical source
emissions and the difference between the FDVs represents the modeled
predicted impacts from those emissions on ambient concentrations. The
results of this quantitative comparison of ambient impacts with and
without the newly exempt sources are not expected to deviate
significantly, even with actual real world conditions potentially being
different than the assumed modeled conditions, since the analysis
focused on the relative impacts of the addition of the hypothetical
source emissions. We believe that the future year modeling approach
used by Arkansas that focused on the quantitative difference in the
relative ambient impacts with and without the hypothetical sources is
reasonable and informative for a 110(l) demonstration in that it
specifically evaluated the impacts from newly exempt emissions based on
revised minor NSR permitting thresholds and de minimis levels. The
concerns raised by the commenter regarding the state's ability to
predict the exact conditions of a future year do not change our
determination that this approach is reasonable. In fact, the inclusion
of informed assumptions in a future year modeling analysis is not only
reasonable, but also necessary, since neither we nor Arkansas can know
with any certainty what emissions and/or sources may change in the
future. The inclusion of informed assumptions in the modeling analysis
provides a reasonable estimate of future levels, given the inability to
foresee the future. If ADEQ modified or removed any SIP-approved
regulations (as relied upon to make these assumptions) and relax the
SIP and render them substantially inadequate to attain or maintain the
relevant NAAQ's standard, EPA has the authority to publish a SIP call
Federal Register notice requiring the state to adopt and submit a
110(l) justification for the relaxation. Regarding the commenter's
concern with potential boom in industrial growth, those sources seeking
a construction permit, such as a PSD permit, would have to demonstrate
NAAQS compliance as part of their permit application modeling. As such,
we find that the state's analysis based on future year photochemical
modeling, along with the additional modeling, monitoring, and emissions
inventory analyses, demonstrate that the revised thresholds are not
expected to adversely impact the state's ability to attain and maintain
the NAAQS.
---------------------------------------------------------------------------

    \15\ Arkansas's initial statewide criteria pollutant modeling
was conducted prior to 2015 using base case years of 2005 and 2008
and a future year of 2015. The final modeling report detailing this
initial modeling entitled ``Criteria Pollutant Modeling Analysis for
Arkansas'' dated July 28, 2014 was included in the March 24, 2017
SIP revision submittal. Arkansas relied upon the 2015 modeling
scenario from this statewide modeling as the baseline scenario in
the minor NSR permitting thresholds and de minimis change levels
modeling. They modified the 2015 emissions inventory to include the
hypothetical source to represent the addition of emissions from a
newly exempt emissions source based on the revised thresholds in
order to examine the potential impacts and sensitivity of model
predicted ambient concentrations to the exempt emissions.
    \16\ A RRF is the ratio of future case modeled concentrations to
base case modeled concentrations, which is used to quantify the
relative impacts of the emissions added to the model. In the
photochemical modeling conducted by ADEQ, the base case modeled
concentrations are taken from the 2015 modeling without the
hypothetical sources added while the future case modeling results
are taken from the 2015 modeling plus the 8 modeled hypothetical
sources. Therefore, the RRFs calculated in this modeling analysis
quantify the relative impacts from the additional emissions from the
hypothetical sources that would be exempt from permitting based on
the new thresholds/de minimis levels.
    \17\ RRFs can be used to estimate FDVs, which are determined by
applying the RRF ratios to monitored design values from the base
year taken from ambient monitoring data.
    \18\ Arkansas applied the RRFs derived from the 2015 baseline
and 2015 baseline with hypothetical sources modeling analyses to
calculated FDVs at all ambient monitoring locations for each
pollutant. The difference between these FDVs represents the impacts
from the hypothetical source emissions on ambient air quality.
Appendix D of the March 24, 2017 SIP revision submittal contains the
details of this analysis including the calculated RRFs and FDVs.
    \19\ The methodology used by Arkansas to develop the modeled
future year 2015 emissions inventory is detailed in Section 3.6 of
the ``Criteria Pollutant Modeling Analysis for Arkansas'' report
provided in Appendix D of the March 24, 2017 SIP revision submittal.
The 2015 emissions inventory was assumed equal to the 2014 emissions
inventory with no further adjustments that were prepared based on as
part of the EPA's 2005-based platform, which included future year
cases developed from it, that was used in the Final Transport Rule
modeling (available at ftp://ftp.epa.gov/EmisInventory/2005v4_2/).
Arkansas did adjust the emissions inventory to include a new
facility (AEP Service Corporations' John W. Turk, Jr. facility
located in southwestern Arkansas.
---------------------------------------------------------------------------

    Comment: The commenter stated that photochemical modeling submitted
by Arkansas in support of the SIP revisions does not give a rational
picture of the effect the SIP relaxations could have on air quality in
Arkansas. The commenter stated that first, there could clearly be more
than 8 sources, which was the number of sources included in the
photochemical modeling, exempt from permitting under the revised minor
NSR rules. The commenter also stated that the photochemical modeling
did not model the worst case conditions such as terrain, stack height,
stack temperature and velocity.
    Response: While we agree with the commenters that the potential
number of exemptions resulting from the revised rule may not be limited
to 8 sources, we do not agree with their assessment that the modeling
analysis was limited to the impacts from only those 8 sources. Arkansas
submitted statewide modeling that accounted for cumulative impacts from
the 8 hypothetical sources along with the emissions contained in the
statewide emissions inventory. (See the March 24, 2017 SIP Revision
Submittal, Appendix D--Air Quality Modeling Analysis of Minor Source
Permit Thresholds.) The 8 modeled sources were distributed throughout
the state's Air Quality Control Regions. The modeling results showed
the impacts of the addition of these eight hypothetical sources to the
predicted ambient concentrations. In addition, the modeling
extrapolated for the maximum modeled impacts from the hypothetical
sources applied at each modeled grid cell throughout the state. In
addition to examining the modeled impacts from these 8 hypothetical
sources in their chosen locations in the Air Quality Control Regions,
the modeling analysis conducted by Arkansas also looked at the impacts
of sources with emissions equal to the revised thresholds throughout
the state. This analysis was accomplished by determining the statewide
maximum modeled impacts in the photochemical modeling for each day
resulting from the hypothetical sources and adding those impacts to the
unmodified future year concentration for each day and grid cell. This
approach allowed the examination of the maximum predicted hypothetical
source impacts combined at different geographic/topographic locations
along with looking at those impacts combined with a variety of
cumulative source inventory impacts throughout the state. It is
impossible for the state to project each source that may be exempt
under the revised rule and unreasonable to expect the inclusion of
every potentially exempt source within an air quality modeling
analysis. We determined that the approach used by Arkansas to include a
number of hypothetical sources throughout the state and to examine the
combined impacts of these sources with background emissions sources at
each modeled grid cell in Arkansas provides information and a rational
picture regarding the potential impacts of newly exempt emissions
throughout the state. By modeling these 8 hypothetical sources with
emission rates equal to the revised thresholds, the state's approach
provided for the examination of the actual model predicted impacts at
locations within each Air Quality Control Region from the maximum level
of emissions that could be exempt from permitting for a source based on
the revised minor NSR permitting thresholds and de minimis change
levels. As a second step, the approach to apply the daily maximum
modeled impacts from the hypothetical sources to each grid cell for
each day in the modeled period provided for the examination of the
impacts of the exempt emissions at each grid cell throughout the state.
In the case of the minor NSR program revisions proposed by Arkansas,
the state developed a 110(l) demonstration comprised of air quality
modeling, as well as an emissions inventory analysis and a monitoring
trends analysis. As stated in our proposed rulemaking, we found in

combination that the modeling analysis along with the other analyses
submitted by the state demonstrated that the proposed revisions would
not interfere with NAAQS attainment or maintenance. Based on our
review, we find the analysis conducted and the methods used to be
appropriate and sufficient to support the proposed SIP revisions,
especially for exemptions from minor NSR permitting requirements that
are expected to make up fractional percentages (<1% for all pollutants)
of the total emissions in the statewide emissions inventory--as
documented in the state supplied emissions inventory analysis.
    Regarding the commenter's statement regarding the modeling of
worst-case conditions, we do not agree with the commenter. The modeling
of the worst case conditions such as terrain, stack height, stack
temperature and velocity is inappropriate for assessing whether the
relaxed applicability to Arkansas' minor NSR rule would violate the
NAAQs. The hypothetical sources included in the 110(l) demonstration
modeling were meant to represent the exempt emissions that could occur
from a variety of sources and were being modeled to examine the
potential impacts from exempt emissions as part of the demonstration of
non-interference with attainment or maintenance of the NAAQS under CAA
section 110(l). Arkansas determined representative values to be used as
model inputs for the hypothetical sources by reviewing real world stack
parameters available through their emissions inventory data. Based on
their review, the state chose the average stack conditions from the
emissions inventory data as the representative inputs for the modeled
hypothetical sources. As stated in the modeling report included in the
March 24, 2017 SIP revision submittal and in our proposed rulemaking,
the state modeled the hypothetical sources with the maximum emissions
exempt by the rule (i.e., emissions equal to the thresholds values),
even though not all exempt sources would have those emissions levels.
    The use of the worst case conditions (as referenced by the
commenter) is typically applied in modeling for an existing source or a
proposed source of known type/size and location as part of a case-by-
case NSR modeling analysis, such as a modeling analysis completed as
part of a PSD permit action. In the case of the modeling analysis
conducted by Arkansas to support the proposed SIP revisions, the state
was examining the potential impacts of emissions exempt from minor NSR
permitting by adding hypothetical exempt sources to represent those
added emissions in the modeled emissions inventory. The modeling
conducted by Arkansas as part of the 110(l) demonstration modeling
serves a different purpose, and therefore is inherently different than
PSD permit modeling. PSD permit modeling is conducted as part of the
source analysis PSD requirement (40 CFR 51.21(k)) to examine the
impacts from the construction or major modification of a specific,
known PSD source where model inputs are based on the actual design and
operational parameters of the emission points located at the source.
That said, we do not agree that the modeling analysis conducted by
Arkansas did not take terrain into account. As discussed previously in
this response, at least one of the modeled hypothetical sources was
located in each of the AQCRs. This allowed the examination of model
predicted impacts across the different geographic and topographic areas
in the state, including those areas in NW Arkansas with more elevated/
complex terrain (1 source located in AQCR 17 and 2 sources located in
AQCR 21), which are expected to have higher impacts. As discussed in
our evaluation of the photochemical modeling conducted by Arkansas, the
model predicted impacts from the hypothetical sources did not indicate
any model predicted violations of the NAAQS for any pollutant or
averaging period. The photochemical modeling approach was one element
of the 110(l) demonstration provided by the state to support the
proposed SIP revisions. The approaches used by Arkansas in their
modeling demonstration to determine the potential impacts from the
newly exempt emissions were reasonable and appropriate for 110(l)
analysis being conducted to demonstrate non-interference, especially
considering the small amounts of emissions expected to be exempt from
minor NSR permitting based on the revised rule relative to the current
statewide emissions.
    Comment: The commenter stated that the photochemical modeling gave
no justification for where it located the sources within the state and
it is not clear if the sources were located in areas where the source's
plume could cause high concentrations due to nearby elevated terrain or
in areas where there are other significant sources of air pollutants to
determine the cumulative impacts.
    Response: We do not agree with the commenter that no justification
was provided for the location of the hypothetical sources within the
photochemical modeling. Arkansas did state that they placed at least
one source in each of their Air Quality Control Regions. They also
stated that the sources were typically located in or near more urban
areas of the state. A figure was included in the modeling report
showing the location of the modeled sources relative to the populated
areas in the state, which are also more likely to have larger
``background'' emissions within the modeled emissions inventory. (See
the March 24, 2017 SIP Revision Submittal, Appendix C--2010 Minor NSR
Permitting Thresholds and De Minimis Levels SIP Technical Support
Document, Figure 19.) The chosen locations allowed for the examination
of impacts throughout the various regions of the state, focused on the
more populated areas. As stated in our previous response, two of the
modeled hypothetical sources were included in the areas in NW Arkansas
with more elevated/complex terrain (1 source located in AQCR 17 and 2
sources located in AQCR 21). Additionally, the modeling approach used
by the state in their 110(l) demonstration included a separate analysis
to specifically examine the model predicted concentrations at each grid
cell throughput the state when the maximum modeled impacts from the
hypothetical sources were applied. This approach allowed the
examination of the maximum hypothetical source impacts combined at
different geographic locations along with looking at those impacts
combined with a variety of cumulative source inventory impacts
throughout the state.
    Comment: The commenter stated that the photochemical modeling did
not attempt to take into account the cumulative impacts of exempt
sources or modifications, and it did not include the possibility of
multiple exempt sources locating nearby each other, nor did the
modeling attempt to model more than one exemption at a single or
multiple sources over time.
    Response: As discussed previously in our responses, we do not agree
that cumulative impacts analysis was not conducted as part of the
state's modeling analysis. The photochemical modeling analysis combined
the impacts from the hypothetical sources with the impacts of
background emissions inventory sources via emissions inventory model
inputs.\20\ Further, this cumulative impacts analysis was conducted in
such a way

as to examine the maximum modeled impacts from the hypothetical sources
with the impacts from the background emissions inventory sources at
each grid cell in the state. Regarding the cumulative impacts from
multiple exempt sources potentially located nearby each other, the
modeling report included in the March 24, 2017 SIP revision submittal
stated that ``since the modeled impacts occur within or nearby the
source location, cumulative effects from multiple sources in multiple
grid cells are expected to be small.'' Based on the 110(l)
demonstration provided by Arkansas, which included modeling that looked
at cumulative impacts from hypothetical exempt sources and the
background emissions sources inventory, we do not find the revised
thresholds to adversely impact the NAAQS.
---------------------------------------------------------------------------

    \20\ As discussed in Arkansas's ``2010 Minor NSR Permitting
Thresholds and De Minimis Levels SIP Technical Support Document''
(Appendix C to March 24, 2017 SIP revision submittal), the CMAQ
photochemical modeling requires as input, hourly, gridded pollutant
emissions from both anthropogenic and biogenic sources.
---------------------------------------------------------------------------

    Comment: The commenter stated that there is no indication that the
modeling took into account variability of emission rates over time to
account for the very likely possibility that an exempt source could
emit at higher rates over shorter periods of time rather than emitting
at a consistent level.
    Response: It is unreasonable to expect the type of modeling
conducted by Arkansas to examine the potential impacts of a small
subset of minor sources that make up much less than 1% of the total
emissions in the statewide emissions inventory (less than or equal to
0.125% of the statewide emissions for minor NSR permitting thresholds;
less than or equal to 0.019% of the statewide emissions for de minimis
change levels) to include variable emissions modeling. The evaluation
of impacts from variable emission rates is typically associated with
modeling an existing source or a proposed source of known type/size and
operation as part of a case-by-case NSR modeling analysis (such as the
modeling conducted for PSD permitting). As stated in our previous
responses, the modeling analysis conducted by Arkansas as part of the
SIP revision submittal was completed as part of a 110(l) demonstration
for the purposes of determining the potential impacts of the revised
missions exempt from minor NSR permitting by adding hypothetical exempt
sources to represent those added emissions in the modeled emissions
inventory. Modeling conducted as part of the 110(l) demonstration is
conducted to determine whether a SIP revision will interfere with
attainment or maintenance of the NAAQS, any required milestone, or any
other requirement of the Act. Because the modeled sources were
hypothetical in nature, source-specific information including emission
rates and their potential variability, cannot be available, nor does it
need to be. As stated in the modeling report included in the March 24,
2017 SIP revision submittal and in our proposed rulemaking, in the
modeling analysis the hypothetical source emission rates were set equal
to the revised minor NSR permitting thresholds and de minimis change
levels to examine the potential impacts resulting from the newly exempt
emissions. (See the March 24, 2017 SIP Revision Submittal, Appendix D--
Air Quality Modeling Analysis of Minor Source Permit Thresholds.) The
approaches used by Arkansas in their modeling demonstration to
determine the potential impacts from the newly exempt emissions were
reasonable and appropriate for the type of analysis being conducted,
especially considering the relatively small amount of emissions
expected to be exempt from minor NSR permitting based on the revised
rule compared to statewide emissions.
    Comment: The commenter stated that because presumably the same
emission rates, stack parameters, and sources locations were modeled
with AERMOD (dispersion model) as were modeled in the CMAQ
photochemical modeling. Therefore, they stated that all of the prior
comments raised with the CMAQ (photochemical) modeling also apply to
the AERMOD (dispersion) modeling results. The commenter also stated
that there is no indication that the air dispersion modeling accounted
for impacts from startup, shutdown and malfunction emissions.
    Response: The comments raised on the CMAQ photochemical modeling
were addressed above. Those responses would also apply to the AERMOD
dispersion modeling, with some slight clarifications due to the
inherent differences between photochemical and dispersion modeling
analyses. We provide the following clarification related to the
comments raised on cumulative impacts analyses since the CMAQ
photochemical modeling and AERMOD dispersion modeling have different
approaches to account for cumulative impacts because the models differ
on how off-site background sources emissions inventories are
represented and how impacts are determined. As discussed in the
modeling report included in the March 24, 2017 SIP revisions submittal,
the CMAQ photochemical modeled concentrations/impacts from the
background emissions inventory sources were included as background
values in the AERMOD dispersion modeling and added to the AERMOD
dispersion modeled concentrations from the hypothetical sources to
determine cumulative impacts from the exempt emissions and the off-site
emissions. (See the March 24, 2017 SIP Revision Submittal, Appendix D--
Air Quality Modeling Analysis of Minor Source Permit Thresholds.)
Although these approaches differ because of the nature of the modeling
system used, both the CMAQ photochemical and AERMOD dispersion modeling
analyses include the cumulative impacts of the hypothetical sources
plus the background emissions inventory sources.
    Regarding the modeling of impacts from startup, shutdown and
malfunction emissions, the evaluation of impacts from routine and/or
predictable startup and shutdown emissions would be associated with
modeling an existing source or a proposed source of known type/size and
operation as part of a case-by-case NSR modeling analysis, such as PSD
permit modeling.\21\ The routine and predictable startups and shutdowns
are permitted emissions which are accounted for in the emissions
inventory. As stated in our previous responses, the hypothetical
sources included in the 110(l) demonstration modeling were meant to
represent the exempt emissions that could occur from a variety of
sources and were being modeled to examine the potential impacts from
exempt emissions. Because the modeled sources were hypothetical in
nature, information regarding source inputs including a small subset of
their emissions such as source-specific startup, shutdown and
malfunction emissions, was not available, nor should it be. Further,
the emissions expected to be exempt from minor NSR permitting based on
the revised permitting thresholds and de minimis levels made up much
less than 1% of the total statewide emissions (less than or equal to
0.125% of the statewide emissions for minor NSR permitting thresholds;
less than or equal to 0.019% of the statewide emissions for de minimis
change levels) meaning that the startup, shutdown and malfunctions
being a small subset of total emissions would make up an even smaller
fraction of the statewide emissions. The commenter's expectation for
this type of analysis is unreasonable on the basis that these emissions
make up such a small fraction of the statewide emissions (that is, a
small subset of the total exempt emissions that are

anticipated to make up much less than 1% of the statewide emissions).
As stated in the modeling report included in the March 24, 2017 SIP
revision submittal and in our proposed rulemaking, the hypothetical
source emission rates were set equal to the revised minor NSR
permitting thresholds and de minimis change levels to examine the
potential impacts resulting from the newly exempt emissions. The
approaches used by Arkansas in their modeling demonstration to
determine the potential impacts from the newly exempt emissions were
reasonable and appropriate for the type of analysis being conducted,
especially considering the relatively small amount of emissions
expected to be exempt from minor NSR permitting based on the revised
rule compared to statewide emissions.
---------------------------------------------------------------------------

    \21\ Any emissions resulting from unplanned startup or shutdown
activities or from malfunctions, and therefore not accounted for in
the NSR permit authorization, would be considered violations of the
SIP unless these emissions limits are reflected in a NSR SIP or a
SIP rule.
---------------------------------------------------------------------------

    Comment: The commenter stated that the dispersion modeling did not
include the modeling of line sources and that fugitive PM10
emissions often cause increment and NAAQS violations. Therefore, the
commenter claims that the AERMOD (dispersion) modeling does not reflect
reasonable worst case impacts that could occur due to the sources and
de minimis changes exempt from minor NSR based on the SIP revisions.
    Response: As discussed in our previous responses, the worst case
impacts conditions (or potential worst case source type in the case of
this comment) referenced by the commenter are typically associated with
case-by-case NSR modeling of an existing source or a proposed source
with known stack/emission characteristics (such as, modeling associated
with a PSD permit action). This would also be the case for the modeling
of line sources mentioned by the commenter. The 110(l) demonstration
modeling conducted by Arkansas in support of the SIP revisions has a
different purpose and associated requirements than case-by-case NSR
modeling. As discussed in our earlier response to the comment raised
regarding worst case stack parameters, Arkansas relied on real world
stack parameters available in their emissions inventory data to
determine representative stack parameters to represent emissions newly
exempt from minor NSR permitting via the inclusion of hypothetical
sources in their modeling analyses. Specifically, they reviewed the
stack parameters and determined the average stack parameters included
as hypothetical point sources with emissions set equal to the minor NSR
permitting thresholds and de minimis change levels. Because the modeled
sources were hypothetical in nature, source-specific information
including whether or not any portion of the emissions were fugitive in
nature (such as road emissions) versus stack emissions, cannot be
available, nor does it need to be. Modeling of hypothetical sources
with emissions rates set equal to the revised minor NSR permitting and
de minimis change thresholds ensures that the analysis accounts for the
maximum amount of emissions that would be exempt from minor NSR
permitting based on the revisions. The approaches used by Arkansas in
their modeling demonstration and their reliance on representative stack
parameters to determine the potential impacts from the newly exempt
emissions were reasonable and appropriate for the type of analysis
being conducted, especially considering the relatively small fraction
of emissions expected to be exempt from minor NSR permitting based on
the revised rule compared with statewide emissions.
    Comment: The commenter stated that the revised Arkansas NSR program
conflicts with the requirements of section 110(2)(C). More
specifically, the commenter stated that the de minimis change
exemptions will exempt most if not all modifications at existing major
stationary sources from minor NSR permitting. They indicate that this
is in direct contrast with the intention for the new source review
program required by CAA section 110(a)(2)(C) and 40 CFR 51.160 to be a
backstop on threats to attainment or maintenance of the NAAQS posed by
new source growth that is not planned for in existing SIP rules.
    Response: We do not agree with the commenter that the de minimis
exemptions will exempt most if not all modifications at existing major
stationary sources from minor NSR permitting. As previously stated in
our responses, the SIP-approved Arkansas NSR program is comprised of
two types of review: ``Minor Source Review'' and ``Major Source
Review''. Arkansas operates a so-called ``merged, one permit'' system,
which is divided into these two types of review based on whether a
source is required to obtain a title V operating permit. As such,
``Minor Source Review'', which is contained in Reg. 19, Chapter 4,
applies only to those sources that are not subject to title V
permitting and require only a title I minor NSR authorization.\22\ Any
source that would be a major source for purposes of PSD review would
also be a major source subject to title V permitting. Compare 40 CFR
52.21(b)(1) (establishing major source thresholds of 100 and 250 tons
per year) with Reg. 26, Chapter 2 (defining major sources to include,
inter alia, any source with the potential to emit 100 tons per year).
Therefore, any source subject to title V, which would include any new
PSD major source and/or any modification to an existing PSD major
source, cannot utilize the de minimis change exemption found at Reg.
19.407(C). Instead, all modifications at title V sources that are not
be subject to Reg. 19, Chapter 9 would instead be subject to the
``Major Source Review'' requirements found in Reg. 26 and incorporated
by reference in Reg. 19, Chapter 11 and cannot use the de minimis
change provisions, which are limited to ``Minor Source Review'' in
Chapter 4 of Reg. 19. The revisions addressed in our proposed
rulemaking are limited to ``Minor Source Review'' under Chapter 4 of
Reg. 19 and do not impact ``Major Source Review'' in Chapter 11, which
has already been approved into the SIP as part of Arkansas' minor NSR
program, most recent approval on March 4, 2015 (See 80 FR 11573), and
which contains the permitting requirement provisions applicable to the
modifications not subject to Reg. 19, Chapter 9 at all title V sources,
including all of the sources referenced by the commenter.
---------------------------------------------------------------------------

    \22\ As stated in our original SIP approval of Chapter 4, ``[a]
minor source is any source which does not meet the requirements of a
major source. The Act in section 302(j) defines the terms ``major
stationary source'' and ``major emitting facility'' as ``any
stationary facility of source of air pollutants which directly
emits, or has the potential to emit, one hundred tons per year of
more of any air pollutant (including any major emitting facility or
source of fugitive emissions of any such pollutant, as determined by
rule by the Administrator).'' ''
---------------------------------------------------------------------------

    Comment: The commenter stated that the NSR program required by CAA
section 110(a)(2)(C) and 40 CFR 51.160 is intended to be a backstop on
threats to attainment or maintenance of the NAAQS posed by new sources
growth that is not planned for in existing SIP rules. Because of the
commenter's assessment that NSR program is an important part of the
SIP, they stated that EPA cannot approve exemptions from a minor NSR
program unless it is shown that the exemptions are truly de minimis to
the purposes of the program.
    Response: We agree that the NSR program is an important part of the
SIP but this does not mean that under the CAA and the minor NSR SIP
rules, EPA cannot approve exemptions from a minor NSR program.
Consequently, what is relevant is whether or not the revisions to the
Arkansas minor NSR program are approvable under the plain reading of
the applicable statute and rules. There is no regulatory or statutory

prohibition that prohibits the types and/or sizes of sources that could
be exempt from the minor NSR program. In fact, the minor NSR SIP rules
at 40 CFR 51.160(e) only require that the minor NSR program include
procedures that ``identify types and sizes of facilities, buildings,
structures, or installations which will be subject to review under this
section. [and] The plan must discuss the basis for determining which
facilities will be subject to review.'' These rules furthermore require
that the plan must ensure that the issuance of minor NSR permits not
result in a violation of the control strategy or interfere with the
attainment or maintenance of a national standard. The CAA at section
110((a)(2)((C) requires regulation of the modification or construction
of any stationary source within the area as necessary (emphasis added)
to assure that the standards are achieved. As such, the CAA at section
110((a)(2)(C) and the minor NSR SIP rules found at 40 CFR 51.160-165,
as well as case law,\23\ allow exemptions from a minor NSR permitting
program. In cases such as this, where the minor NSR SIP is being
revised, the state must also demonstrate that the revisions meet the
requirements of CAA section 110(l). Similar to the provisions of the
Act and rules discussed above, section 110(l) requires that EPA cannot
approve revisions to the Arkansas minor NSR SIP unless EPA finds that
the changes would not interfere with any applicable requirement
concerning attainment and reasonable further progress, as well as any
other applicable statutory requirement. The clear reading of the Act
and the EPA rules are that EPA can approve exemptions to the Arkansas
minor NSR SIP program as long as it finds these exemptions will not
interfere with attainment or maintenance of a NAAQS or other control
strategy. Consistent with what is allowed, Arkansas has identified
revised permitting thresholds and de minimis change levels to serve as
the exemption thresholds for their minor NSR permitting program. To
support the revised exemption thresholds, Arkansas provided analyses to
define the scope of the exemptions and to demonstrate that these
revised thresholds will not adversely impact NAAQS maintenance or
attainment. The analyses, which were submitted as part of the March 24,
2017 SIP revision submittal, included: (1) An emissions inventory
analysis that determined the percentage of the statewide total
emissions inventory that would be newly exempt by the revised
thresholds; (2) a monitoring analysis that included a review of the
current status of ambient air quality in the state along with a review
of the trends in monitoring data since the state adopted and
implemented the revised thresholds; and (3) a modeling analysis that
examined the impacts of the exempt emissions on ambient concentrations.
The analyses provided by Arkansas in the SIP revision submittals show
that the minor NSR permitting exemptions resulting from the revised
rule were limited in scope and comprised much less than 1% of the total
emissions in the statewide emissions inventory and that the impacts
from the newly exempt emissions would not adversely impact NAAQS
maintenance or attainment, as part of their 110(l) demonstration. The
EPA's review of these analyses and our finding that the proposed SIP
revisions were approvable were detailed in the proposed rulemaking and
the Technical Support Document accompanying the rulemaking.
---------------------------------------------------------------------------

    \23\ Alabama Power Company, et al., Petitioners,* v. Douglas M.
Costle, As Administrator, Environmental Protection Agency, et al.,
Respondents,* Sierra Club, et al., Intervenors.*, 636 F.2d 323 (D.C.
Cir. 1980).
---------------------------------------------------------------------------

    Comment: The commenter stated that the results from the state's
AERMOD (dispersion) modeling show that the exemptions are not ``de
minimis.'' The commenter also states that the EPA must not approve the
revised program because it will interfere with the requirements that
SIPs include programs to ensure that new and modified sources not be
allowed to construct or modify if they would interfere with attainment
or maintenance of the NAAQS.
    Response: Our proposed rulemaking specifically addressed the scope
of the exemptions resulting from the revised minor NSR permitting
thresholds and de minimis levels. As discussed in our proposal,
Arkansas provided an analysis to quantify the amount of emissions that
would be expected to be exempt from minor NSR permitting requirements
relative to total emissions from the statewide emissions inventories.
For all pollutants, the exempt emissions for both the permitting
thresholds and de minimis levels made up a fraction of 1% of the
statewide emissions. Therefore, we find that the scope of emissions
expected to be exempt from minor NSR permitting as a result of the
revised minor NSR program thresholds and de minimis change levels is
extremely limited. Regarding the commenter's claim that the revised
program will interfere with NAAQS attainment or maintenance, the 110(l)
demonstration submitted by Arkansas in support of the proposed
revisions to the SIP specifically addressed the anticipated impacts on
the NAAQS through both a review of the current status of ambient air
quality in Arkansas and an evaluation the impacts of the revised
thresholds on ambient air quality via air monitoring and air modeling
data. As discussed in our proposed rulemaking, based on the ambient
monitoring trend analysis, the implementation of the revised minor NSR
permitting thresholds and de minimis levels following state adoption of
the revisions in 2008 and ongoing implementation have not negatively
impacted ambient air quality or interfered with the attainment of the
NAAQS. In fact, for several pollutants the ambient air quality has
shown continued improvements via decreases in monitored DVs during this
period; and currently Arkansas does not have any areas classified as
nonattainment for any NAAQS. Our proposal also summarized the air
quality modeling results that Arkansas submitted as part of the SIP
revisions. The modeling analysis included an evaluation of both
statewide regional-scale (photochemical) and local-scale impacts. (See
the March 24, 2017 SIP Revision Submittal, Appendix D--Air Quality
Modeling Analysis of Minor Source Permit Thresholds.) The photochemical
modeling was designed to specifically examine ozone and
PM2.5, the model also simulates NO2,
SO2, and PM10 so the results for those pollutants
were also examined. The maximum photochemical modeling derived impacts
including the hypothetical source emissions on daily maximum 8-hr
ozone, 24-hr PM2.5, and annual average PM2.5 for
any location in Arkansas was calculated. The maximum impacts including
hypothetical source emissions on daily maximum 1-hr NO2 and
SO2 and 24-hr average PM10 was also calculated.
These maximum impacts were added to the baseline modeled predicted
concentrations for each day and grid cell for the future year
simulation. The resultant model predicted concentrations represented
the future year concentrations assuming the worst-case impacts from the
threshold emission increases at any location within the modeling grid.
These model results were used in conjunction with the baseline modeling
results to calculate the RRFs necessary to estimate FDVs. The FDVs were
used to examine whether emission increases less than or equal to the
revised thresholds will cause or contribute to a NAAQS violation or
interfere with NAAQS maintenance. To further examine the potential
near-field impacts

from new or existing sources with emission increases less than or equal
to the revised permitting and de minimis change thresholds, a
dispersion modeling analysis was conducted. The dispersion model was
applied for the same hypothetical sources used in the photochemical
modeling with emissions set to the revised thresholds. The dispersion
model was applied for one year for NOX, SO2, CO,
and PM10. For each source location, daily concentrations
(for the receptor with the maximum annual average value) taken from the
dispersion modeling were added to the photochemical model -derived
concentrations for that same location. In this manner, the
photochemical modeling values were used as ``background''. The
statewide daily maximum impact (maximum over all locations/AQCRs)
obtained were expected to represent the near-field future-year
concentrations assuming worst-case impacts from threshold emission
increases at a range of locations throughout the state. Similar to the
photochemical modeling, these maximum impacts were added to the
baseline modeled predicted concentrations for each day and grid cell
for the future year simulation. The resultant model predicted
concentrations represented the future year concentrations assuming the
worst-case impacts from the threshold emission increases at any
location within the modeling grid. The resultant concentrations were
used in conjunction with the baseline modeling results to calculate the
RRFs necessary to estimate FDVs. Once again, the FDVs were used to
examine if the emissions under the revised threshold values would
cause/contribute to a NAAQS violation and/or interfere with NAAQS
attainment. Both the photochemical and dispersion modeling results did
show that the addition of exempt emissions via modeled hypothetical
sources may result in some increases in ambient concentrations.
However, as discussed in the TSD accompanying our proposed rulemaking,
the FDVs calculated as part of the regional-scale modeling analysis
that were based on the maximum modeled impacts from the hypothetical
source were less than the NAAQS for each pollutant and averaging
period.\24\ Similarly, the results from the near-field dispersion
modeling also showed the modeled impacts from the hypothetical sources
combined with background concentrations were all less than their
corresponding NAAQS.\25\ Based on our evaluation of these analyses
conducted by ADEQ to support the revised minor NSR permitting
thresholds and de minimis levels, we find that the increased levels
will not interfere with attainment or maintenance of the NAAQS.
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    \24\ For more detailed discussion regarding the regional-scale
photochemical modeling results see Pages 29-31 of EPA's Technical
Support Document dated August 24, 2017, available in the electronic
docket for this rulemaking.
    \25\ For more detailed discussion regarding the near-field
dispersion modeling results see Pages 31-32 of the EPA's Technical
Support Document dated August 24, 2017, including Table V.5 which
contains the maximum and average AERMOD concentrations both with and
without the CMAQ-derived background concentrations that were
determined in ADEQ's nearfield hypothetical source analysis.
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    Comment: The commenter stated that EPA does not cite to the
specific rule that states that ``de minimis changes are still required
to meet minor NSR requirements contained in Reg. 19, Chapter 4
including a demonstration that the proposed modification will not
interfere with the NAAQS on a case-by-case basis'' and that the EPA's
claim that this requirement remains is without merit. The commenter
stated that EPA may be assuming that Reg. 19.402 applies since a permit
revision is implied by Reg. 19.407(C)(6), it is not clear that this
requirement applies to what appears to be an administrative amendment
to a source's permit if it makes a de minimis change. The commenter
also states that ADEQ made it clear that it does not plan to require or
base any decision for de minimis changes on air quality modeling, and
without conducting modeling, they will not be able to ensure that the
proposed modification will not interfere with attainment or maintenance
of a NAAQS on a case-by-case basis. So, the commenter stated that it is
unlikely that ADEQ considered Reg. 19.402 as applying to de minimis
permit changes.
    Response: We do not agree that our proposed rulemaking did not
include a citation to the specific rule related to a case-by-case
demonstration of non-interference with the NAAQS that is applicable to
de minimis changes. We also do not agree that our statement that de
minimis changes must still meet minor NSR requirements is without
merit. Our position that de minimis changes must include a
demonstration that the proposed modification will not interfere with
the NAAQS on a case-by-case basis is based on the applicability of Reg.
19.405(A)(1) to these changes. Further, the provisions in the de
minimis change rule indicate that de minimis changes include an
application submittal/review process at Reg. 19.407(C)(5) at it
references applications for de minimis changes. In addition to the rule
language, the current ``Air Application Instructions for Registrations,
Minor Source Permits, or Title V Permits'' made available on ADEQ's air
permitting website indicate that the forms are to be used for de
minimis changes.\26\ As such, we do not agree with the commenter that
EPA assuming the de minimis changes include an application process
without a basis. Further we do not agree with the commenter, that our
proposed rulemaking did not clearly state the specific rule regarding
the referenced technical review requirement to demonstrate NAAQS
compliance for a de minimis change. In our proposed rulemaking, we
specifically stated that the requirement found at Reg. 19.405(A)(1)
requires ADEQ must ensure as part of their technical review of de
minimis change applications that the source will be modified to operate
without interfering with NAAQS attainment or maintenance.\27\ The de
minimis change rule found at Reg. 19.407(C)(2) of the current Arkansas
SIP exempts qualified proposed changes at an existing source from minor
NSR permitting requirements, including public notice. The exemption
only exempts the de minimis change from minor NSR permitting
requirements and not all applicable minor NSR requirements. Therefore,
the exemption does not exempt the change from the technical review
requirements found at Reg. 19.405(A). Reg. 19.405(A) applies to the
review of applications submitted under Chapter 4 of Reg. 19, where the
de minimis change rule is located, and requires that on an application-
by-application basis ADEQ must ensure as part of their technical review
that the source will be modified to operate without interfering with
NAAQS attainment or maintenance. Our approval of the de minimis change
level revisions does not revise or in any way change the applicability
of the SIP-approved technical review requirements found in Reg.
19.405(A), or any other applicable minor NSR requirements, to de
minimis changes. It is important to note that the Reg. 19.405(A)
technical review requirements do not specify that modeling be completed
to demonstrate that the source will be constructed/modified without
interfering with attainment or maintenance of the NAAQS. The EPA minor
NSR SIP rules found in 40 CFR 51.160-165 do not

require modeling either. We do not agree with the commenter that
without conducting modeling, ADEQ cannot ensure that a de minimis
change will not interfere with attainment or maintenance of a NAAQS on
a case-by-case basis. Case-by-case modeling, such as air dispersion
modeling, is one of the methods that is commonly used to meet NAAQS
requirements, but it is not the only method. Depending on the source
and the proposed de minimis change, as part of their technical review
ADEQ could alternatively utilize past modeling analyses, such as the
statewide modeling that was included as part of the 110(l)
demonstration in the March 24, 2017 SIP revision submittal, or existing
ambient monitoring data or emissions inventory data relevant to the
proposed change to make a determination regarding NAAQS compliance. In
addition, the SIP-approved provision found at Reg. 19.407(C)(1)(b)
specifies that ``a proposed change to a facility will be considered De
Minimis if: . . . the change will result in a trivial environmental
impact.'' Our rulemaking does not revise or in any way change this
provision.
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    \26\ Air Application Instructions available online at: https://www.adeq.state.ar.us/downloads/WebDatabases/Air/PermitData/Forms%20and%20Instructions/Form%20and%20Instructions/Air_Permit_Application_Forms_Instructions.pdf.
    \27\ See 82 FR 43508.
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    Comment: The commenter stated that EPA has not evaluated whether
the SIP revision satisfies CAA section 193. They state that because the
revisions allow ADEQ to relax emission limits via de minimis changes
and for previously permitting sources to terminate the existing permit
and replace with a registration, EPA's review should include an
evaluation pursuant to CAA section 193 of whether these relaxations
would allow for the relaxation of any control requirements in effect
before November 15, 1990, in any nonattainment area, in which case
equivalent or greater emissions reductions.
    Response: We do not agree with the commenter that this rulemaking
is subject to CAA section 193. Section 193 applies to nonattainment
areas only and provides that ``[n]o control requirement in effect, or
required to be adopted by an order, settlement agreement, or plan in
effect before the date of the enactment of the Clean Air Act Amendments
of 1990 in area for any air pollutant may be modified after such
enactment in any manner unless the modifications insures equivalent or
greater emission reductions of such air pollutant.'' The proposed rule
does not change control requirements in nonattainment areas, of which
Arkansas currently has none. Therefore, EPA did not address section 193
in the proposed approval action, since it does not apply. In the
future, should an area become designated as nonattainment, Arkansas
when developing the required nonattainment NSR permitting program would
have to ensure that this program applied the Act's thresholds, which
might require Arkansas to revise its minor NSR SIP program.

III. Final Action

    In this action, EPA is approving revisions to the minor NSR
permitting program as submitted as revisions to the Arkansas SIP on
July 26, 2010, and March 24, 2017, including supplemental information
submitted on November 30, 2015, May 26, 2016, July 5, 2017, July 27,
2017, and March 16, 2018. Our approval includes the following revisions
to the Arkansas SIP:
     Revisions to Reg. 19.401 (submitted 07/26/2010 and 03/24/
2017);
     Revisions to Reg. 19.407(C)(2)(a) and (b) (submitted 07/
26/2010 and 03/24/2017); and
     Revisions to Reg. 19.417(A) and (B) (submitted 07/26/
2010).
    As previously stated in our proposed rulemaking, this final action
does not remove or modify the existing federal and state requirements
that each NSR permit action issued by ADEQ include an analysis
completed by the Department and their determination that the proposed
construction or modification authorized by the permit action will not
interfere with attainment or maintenance of a national ambient air
quality standard.

IV. Incorporation by Reference

    In this rule, the EPA is finalizing regulatory text that includes
incorporation by reference. In accordance with requirements of 1 CFR
51.5, the EPA is finalizing the incorporation by reference of the
revisions to the Arkansas regulations as described in the Final Action
section above. The EPA has made, and will continue to make, these
materials generally available through www.regulations.gov and at the
EPA Region 6 Office (please contact Ashley Mohr for more information).
Therefore, these materials have been approved by EPA for inclusion in
the SIP, 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 in the next update to the SIP compilation.

V. Statutory and Executive Order Reviews

    Under the Clean Air Act, 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, the EPA's role is to approve state
choices, provided that they meet the criteria of the Clean Air Act.
Accordingly, this action merely approves state law as meeting Federal
requirements and does not impose additional requirements beyond those
imposed by state law. For that reason, this action:
     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);
     Is not an Executive Order 13771 (82 FR 9339, February 2,
2017) regulatory action because SIP approvals are exempted under
Executive Order 12866;
     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, 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).

In addition, the SIP is not approved to apply on any Indian reservation
land or in any other area where EPA or an Indian tribe has demonstrated