```

[Federal Register Volume 86, Number 114 (Wednesday, June 16, 2021)]
[Rules and Regulations]
[Pages 31927-31939]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-12431]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R09-OAR-2020-0589; FRL-10024-21-Region 9]

Air Plan Approval; Arizona; Stationary Sources; New Source Review 
Updates

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

-----------------------------------------------------------------------

SUMMARY: The Environmental Protection Agency (EPA) is taking final 
action to approve revisions to the Arizona Department of Environmental 
Quality's (ADEQ) portion of the Arizona State Implementation Plan (SIP) 
that were submitted to the EPA by the ADEQ. These revisions concern the 
ADEQ's SIP-approved rules for the issuance of New Source Review (NSR) 
permits for stationary sources under the Clean Air Act (CAA or Act). 
This action updates the ADEQ's NSR rules in the Arizona SIP and 
corrects the remaining deficiencies in the ADEQ's NSR program that we 
identified as the basis for our limited disapprovals in final 
rulemaking actions in 2015 and 2016. Additionally, we are finding that 
the ADEQ's SIP-approved NSR permitting program meets requirements for 
visibility protection for major stationary sources under the Act and 
are removing the Federal Implementation Plans (FIPs) for the ADEQ 
related to these visibility protection requirements.

DATES: This rule is effective on July 16, 2021.

ADDRESSES: The EPA has established a docket for this action under 
Docket ID No. EPA-R09-OAR-2020-0589. All documents in the docket are 
listed on the https://www.regulations.gov website. Although listed in 
the index, some information is not publicly available, e.g., 
Confidential Business Information (CBI) or other information the 
disclosure of which is restricted by statute. Certain other material, 
such as copyrighted material, is not placed on the internet and will be 
publicly available only in hard copy form. Publicly available docket 
materials are available through https://www.regulations.gov, or please 
contact the person identified in the FOR FURTHER INFORMATION CONTACT 
section for additional availability information. If you need assistance 
in a language other

[[Page 31928]]

than English or if you are a person with disabilities who needs a 
reasonable accommodation at no cost to you, please contact the person 
identified in the FOR FURTHER INFORMATION CONTACT section.

FOR FURTHER INFORMATION CONTACT: Lisa Beckham, EPA Region IX, 75 
Hawthorne St., San Francisco, CA 94105. By phone: (415) 972-3811 or by 
email at [email protected].

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

Table of Contents

I. Proposed Action
II. Public Comments and EPA Responses
III. EPA Action
IV. Incorporation by Reference
V. Statutory and Executive Order Reviews

Definitions

    For this document, we are giving meaning to certain words or 
initials as follows:
    (i) The words or initials Act or CAA mean or refer to the Clean Air 
Act, unless the context indicates otherwise.
    (ii) The initials ADEQ mean or refer to the Arizona Department of 
Environmental Quality.
    (iii) The initials Ag BMP mean or refer to the State of Arizona's 
Agricultural Best Management Practices program.
    (iv) The initials ARS mean or refer to the Arizona Revised 
Statutes.
    (v) The initials CBI mean or refer to confidential business 
information.
    (vi) The initials CFR mean or refer to the Code of Federal 
Regulations.
    (vii) The initials CO mean or refer to carbon monoxide.
    (viii) The words EPA, we, us or our mean or refer to the United 
States Environmental Protection Agency.
    (ix) The initials FIP mean or refer to Federal Implementation Plan.
    (x) The initials MMBtu/hr mean or refer to million British thermal 
units per hour.
    (xi) The initials NAAQS mean or refer to the National Ambient Air 
Quality Standards.
    (xii) The initials NESHAP mean or refer to the National Emission 
Standards for Hazardous Air Pollutants.
    (xiii) The initials NNSR mean or refer to Nonattainment New Source 
Review.
    (xiv) The initials NOX mean or refer to oxides of nitrogen.
    (xv) The initials NSPS mean or refer to New Source Performance 
Standards.
    (xvi) The initials NSR mean or refer to New Source Review.
    (xvii) The initials PM2.5 mean or refer to particulate 
matter with an aerodynamic diameter of less than or equal to 2.5 
micrometers, or fine particulate matter.
    (xviii) The initials PM10 mean or refer to particulate 
matter with an aerodynamic diameter of less than or equal to 10 
micrometers.
    (xix) The initials PSD mean or refer to Prevention of Significant 
Deterioration.
    (xx) The initials SER mean or refer to significant emission rate.
    (xxi) The initials SIP mean or refer to State Implementation Plan.
    (xxii) The initials SO2 mean or refer to sulfur dioxide.
    (xxiii) The words State or Arizona mean the State of Arizona, 
unless the context indicates otherwise.
    (xxiv) The initials TSD mean or refer to the technical support 
document for this action unless the context indicates otherwise.

I. Proposed Action

    On December 23, 2020 (85 FR 83868), the EPA proposed to approve 
revisions to the ADEQ portion of the Arizona SIP consisting of several 
rule revisions and demonstrations submitted by the ADEQ related to the 
ADEQ's CAA NSR permitting program.
    First, we proposed to approve a July 22, 2020 SIP submittal from 
the ADEQ that contains rule revisions and other demonstrations 
primarily intended to correct deficiencies in the ADEQ's minor NSR 
program (referred to hereinafter as the ``2020 Minor NSR submittal''). 
The deficiencies being corrected by the 2020 Minor NSR submittal were 
identified in a November 2, 2015 \1\ final limited approval and limited 
disapproval action by the EPA (referred to hereinafter as the EPA's 
``2015 NSR action'').\2\ Our 2015 NSR action was the result of an 
extensive review of the ADEQ's NSR program, in response to a 
comprehensive NSR program update submitted by the ADEQ to the EPA in a 
2012 SIP revision (referred to hereinafter as the ``2012 NSR SIP 
submittal''). The 2012 NSR SIP submittal represented the ADEQ's first 
comprehensive update to its SIP-approved NSR program since the 1980s. 
Our review of the 2012 NSR SIP submittal for compliance with CAA 
requirements therefore included all aspects of the ADEQ's minor NSR, 
Prevention of Significant Deterioration (PSD), and nonattainment NSR 
(NNSR) permitting programs, including NSR-related visibility 
requirements for major stationary sources. In a May 4, 2018 final 
rule,\3\ we approved revisions to the ADEQ's NSR program, submitted to 
the EPA in 2017, that corrected a large portion of the deficiencies 
identified in our 2015 NSR action, primarily related to the PSD and 
NNSR programs (referred to hereinafter as the ``2018 Major NSR 
action''). Thus, the 2020 Minor NSR submittal that is the subject of 
our present action addresses the remaining deficiencies from our 2015 
NSR action.
---------------------------------------------------------------------------

    \1\ 80 FR 67319 (Nov. 2, 2015).
    \2\ In the 2015 NSR action, we also finalized other actions, 
including a partial disapproval related to the fine particulate 
matter (PM2.5) significant monitoring concentration, and 
limited approvals, without corresponding limited disapprovals, 
related to section 189(e) of the Act.
    \3\ 83 FR 19631 (May 4, 2018).
---------------------------------------------------------------------------

    Second, our December 23, 2020 proposed action also included our 
proposed approval of a March 29, 2019 SIP submittal, and a January 14, 
2020 supplemental submittal, from the ADEQ. These two submittals are 
intended to resolve an ADEQ NNSR program deficiency related to the 
permitting of ammonia as a precursor to PM2.5 in the West 
Central Pinal and Nogales PM2.5 nonattainment areas (the 
March 29, 2019 submittal and January 14, 2020 supplement are 
collectively referred to hereinafter as the ``Ammonia PM2.5 
NSR submittal''). In a June 22, 2016 \4\ final limited disapproval rule 
action, we had identified additional deficiencies in the ADEQ's NNSR 
program related to PM2.5 precursors (referred to hereinafter 
as the EPA's ``2016 PM2.5 precursor action''). In our 2018 
Major NSR action, in addition to approving rule revisions to the ADEQ's 
NSR program, the EPA conditionally approved \5\ the ADEQ's NNSR program 
pursuant to CAA section 110(k)(4) solely with respect to ammonia as a 
precursor to PM2.5 under section 189(e) of the Act.\6\ We 
found in our 2018 Major NSR action that the ADEQ's SIP revisions 
otherwise resolved the deficiencies identified in our 2016 
PM2.5 precursor action.\7\ In addition to resolving the 
deficiency that was the basis for our conditional approval for ammonia 
as a precursor to PM2.5 under CAA section 189(e), the 
Ammonia PM2.5 NSR submittal also includes other

[[Page 31929]]

minor and technical rule revisions to the ADEQ's NSR program that we 
proposed to approve in our December 23, 2020 proposed action.\8\
---------------------------------------------------------------------------

    \4\ 81 FR 40525 (June 22, 2016).
    \5\ 83 FR 19631, 19634. The conditional approval was based upon 
a December 6, 2017 letter from the State committing to submit a SIP 
revision to the EPA consisting of rule revisions and/or 
demonstrations that would correct the deficiencies related to 
ammonia as a precursor to PM2.5 under the NNSR program 
requirements in CAA section 189(e). See 83 FR 19631, 19633-19634.
    \6\ Concurrent with our proposed conditional approval action in 
2018, we made an interim final determination that the State of 
Arizona had satisfied the requirements of part D of the CAA 
permitting program for areas under the jurisdiction of ADEQ with 
respect to PM2.5 precursors under section 189(e). See 83 
FR 1195 (January 10, 2018) and 83 FR 1212 (January 10, 2018). The 
effect of our interim final determination was that the imposition of 
sanctions that had been triggered were deferred.
    \7\ See 83 FR 19631, 19633-19634.
    \8\ The ADEQ's January 14, 2020 submittal requested that 
specific paragraphs from certain revised rules be added to the 
Arizona SIP. The 2020 Minor NSR submittal clarified that the ADEQ 
requests that the entirety of each revised rule (with one exception) 
be included in the SIP, rather than only the selected paragraphs 
identified in the earlier submittal.
---------------------------------------------------------------------------

    Finally, our December 23, 2020 proposal also included our proposed 
determination that the ADEQ's SIP-approved NSR program meets the 
visibility requirements for major NSR programs in 40 CFR 51.307. 
Accordingly, we proposed to update 40 CFR 52.145(b) to remove the 
existing visibility FIPs \9\ for those stationary sources subject to 
the ADEQ's permitting jurisdiction.
---------------------------------------------------------------------------

    \9\ The visibility FIPs are implemented at 40 CFR 52.27 for 
attainment areas and 40 CFR 52.28 for nonattainment areas.
---------------------------------------------------------------------------

    The EPA's proposal and technical support document (TSD) for this 
rulemaking action have more information about the content of the ADEQ's 
SIP submittals (collectively referred to hereinafter as the ``2019-20 
NSR submittals''), the deficiencies in the ADEQ's NSR program that are 
being corrected, and our rationale for proposing approval.
    The rules that the EPA proposed to approve into the ADEQ's portion 
of the Arizona SIP are listed in Table 1 of this notice, and the 
existing SIP-approved rules that we proposed to remove or supersede 
from the SIP are listed in Table 2 of this notice. The rules are from 
the Arizona Administrative Code, Title 18--Environmental Quality, 
Chapter 2--Department of Environmental Quality--Air Pollution Control, 
Articles 1, 3, and 4.\10\ These rules apply to all areas and stationary 
sources in Arizona for which the ADEQ has permitting jurisdiction. The 
ADEQ has permitting jurisdiction for the following stationary source 
categories in all areas of Arizona: Smelting of metal ores, coal-fired 
electric generating stations, petroleum refineries, Portland cement 
plants, and portable sources. The ADEQ also has permitting jurisdiction 
for major and minor sources in the following counties: Apache, Cochise, 
Coconino, Gila, Graham, Greenlee, La Paz, Mohave, Navajo, Santa Cruz, 
Yavapai, and Yuma. Finally, the ADEQ has permitting jurisdiction over 
major sources in Pinal County (currently delegated to Pinal County Air 
Quality Control District) and any source in Maricopa, Pima, or Pinal 
County for which the ADEQ asserts jurisdiction.
---------------------------------------------------------------------------

    \10\ One older rule provision that we are removing from the 
Arizona SIP, listed in Table 2, was from the Arizona Administrative 
Code, Title 9, Chapter 3, Article 2.
    \11\ This rule contains a new provision stating that a 
particular revised subsection, R18-2-101(131)(f), will take effect 
on the effective date of the EPA Administrator's action approving it 
as part of the Arizona SIP. Therefore, the revised version of R18-2-
101(131)(f) would become effective on the effective date of our 
approval of the current submittal of R18-2-101.

                                            Table 1--Submitted Rules
----------------------------------------------------------------------------------------------------------------
                                                                                                       State
                       Rule                                             Title                     effective date
----------------------------------------------------------------------------------------------------------------
R18-2-101, except (20)............................  Definitions.................................   \11\ 2/1/2020
R18-2-301.........................................  Definitions.................................        2/1/2020
R18-2-302.........................................  Applicability; Registration; Classes of            3/21/2017
                                                     Permits.
R18-2-302.01......................................  Source Registration Requirements............        2/1/2020
R18-2-304.........................................  Permit Application Processing Procedures....        2/1/2020
R18-2-306.........................................  Permit Contents.............................       3/21/2017
R18-2-306.01......................................  Permits Containing Voluntarily Accepted            3/21/2017
                                                     Emission Limitations and Standards.
R18-2-317.........................................  Facility Changes Allowed Without Permit             8/7/2012
                                                     Revisions--Class I.
R18-2-317.01......................................  Facility Changes that Require a Permit              8/7/2012
                                                     Revision--Class II.
R18-2-317.02......................................  Procedures for Certain Changes that Do Not          8/7/2012
                                                     Require a Permit Revision--Class II.
R18-2-319.........................................  Minor Permit Revisions......................       3/21/2017
R18-2-320.........................................  Significant Permit Revisions................       3/21/2017
R18-2-334.........................................  Minor New Source Review.....................        2/1/2020
R18-2-406.........................................  Permit Requirements for Sources Located in          2/1/2020
                                                     Attainment and Unclassifiable Areas.
----------------------------------------------------------------------------------------------------------------

                                   Table 2--Rules To Be Removed or Superseded
----------------------------------------------------------------------------------------------------------------
                                                                                                     Federal
                    Rule                                Title               EPA approval date        Register
                                                                                                     citation
----------------------------------------------------------------------------------------------------------------
R18-2-101..................................  Definitions................  May 4, 2018..........     83 FR 19631
R18-2-301..................................  Definitions................  November 2, 2015.....     80 FR 67319
R18-2-302..................................  Applicability;               November 2, 2015.....     80 FR 67319
                                              Registration; Classes of
                                              Permits.
R18-2-302.01...............................  Source Registration          November 2, 2015.....     80 FR 67319
                                              Requirements.
R18-2-304..................................  Permit Application           November 2, 2015.....     80 FR 67319
                                              Processing Procedures.
R18-2-306..................................  Permit Contents............  November 2, 2015.....     80 FR 67319
R18-2-306.01...............................  Permits Containing           November 2, 2015.....     80 FR 67319
                                              Voluntarily Accepted
                                              Emission Limitations and
                                              Standards.
R18-2-319..................................  Minor Permit Revisions.....  November 2, 2015.....     80 FR 67319
R18-2-320..................................  Significant Permit           November 2, 2015.....     80 FR 67319
                                              Revisions.
R18-2-334..................................  Minor New Source Review....  November 2, 2015.....     80 FR 67319
R18-2-406..................................  Permit Requirements for      May 4, 2018..........     83 FR 19631
                                              Sources Located in
                                              Attainment and
                                              Unclassifiable Areas.
R9-3-217, paragraph A......................  Attainment Areas;            April 23, 1982.......     47 FR 17483
                                              Classification and
                                              Standards.
----------------------------------------------------------------------------------------------------------------

[[Page 31930]]

II. Public Comments and EPA Responses

    The EPA's proposal provided for a 30-day public comment period. We 
received one set of comments from Arizona Center for Law in the Public 
Interest and the Center for Biological Diversity (``the commenters''). 
Below, we summarize the comments received and provide our responses. 
The full text of the comments is available in the docket for this 
action.
    Comment: The commenters state that the ADEQ's minor NSR program is 
inadequate because it does not regulate ammonia and volatile organic 
compounds (VOCs) as PM2.5 precursors. The commenters argue 
that the EPA's approval of the 2020 Minor NSR submittal will interfere 
with attainment of the PM2.5 National Ambient Air Qualtiy 
Standard (NAAQS) in areas under the ADEQ's jurisdiction that are 
designated nonattainment for PM2.5. The commenters argue 
that this also means that the submittal does not comply with CAA 
section 110(l) and Appendix V to 40 CFR part 51. Further, the 
commenters argue that the 2020 Minor NSR submittal is insufficient 
because it does not include a modeling demonstration that the 
regulation of VOCs or ammonia is unnecessary to ensure protection of 
the PM2.5 NAAQS.
    Response: As an initial matter, we note that the commenters' 
argument that the ADEQ's minor NSR program must regulate VOCs and 
ammonia as precursors to PM2.5 in PM2.5 
nonattainment areas where the ADEQ has jurisdiction does not address 
the specific revisions to the ADEQ's minor NSR program that are the 
focus of the EPA's current action. As explained in section I of this 
SUPPLEMENTARY INFORMATION section, the EPA previously undertook an 
extensive review of the ADEQ's NSR program (minor NSR, PSD, and NNSR) 
in 2015 to ensure that the program met all Clean Air Act requirements. 
In our 2015 NSR action, we found that the ADEQ's updated program 
largely met Clean Air Act requirements, but we identified a number of 
specific deficiencies in our final action that needed to be corrected 
in order for ADEQ to gain full approval from the EPA. Most of the 
identified deficiencies were corrected and submitted to the EPA for 
approval in 2017 and were approved in our 2018 Major NSR action. We are 
currently acting on the ADEQ's 2019-20 NSR submittals that correct the 
remaining deficiencies that we identified as the bases for our final 
limited disapproval in our 2015 NSR action and that formed the basis 
for the conditional approval in our 2018 Major NSR action. The EPA 
found in our 2015 NSR action that the ADEQ's minor NSR program met all 
the requirements for a minor NSR program in CAA section 110(a)(2)(C) 
and 40 CFR 51.160-51.164 with the exception of specific deficiencies 
that the ADEQ is now addressing with the 2020 Minor NSR submittal. In 
light of the recent and extensive review and approval by the EPA of the 
ADEQ's NSR program, we find that the commenters' concerns regarding 
PM2.5 precursors in the ADEQ's minor NSR program are not 
germane to the deficiencies with the ADEQ's minor NSR program that we 
identified previously and that we are addressing in this action. 
Nevertheless, we will explain why we disagree with the commenters that 
the ADEQ's minor NSR program must regulate VOCs and ammonia as 
precursors to PM2.5 in the areas where the ADEQ has 
permitting jurisdiction, and why we disagree that the EPA's approval of 
these revisions to the ADEQ's SIP-approved minor NSR program is 
inconsistent with CAA section 110(l) and Appendix V to 40 CFR part 51.
    The commenters are concerned that this action will interfere with 
attainment of the PM2.5 NAAQS in designated PM2.5 
nonattainment areas under the ADEQ's permitting jurisdiction because 
the ADEQ's minor NSR program and the 2020 Minor NSR submittal do not 
specifically regulate ammonia and VOC as precursors to PM2.5 
in the ADEQ's minor NSR program.\12\ As a result, the commenters 
conclude, the 2020 Minor NSR submittal does not meet CAA section 110(l) 
and section 2.2(d) of Appendix V to 40 CFR part 51. To support their 
concerns, the commenters point generally to examples of operations that 
can emit ammonia and VOC, and imply that the method to demonstrate that 
this action complies with CAA section 110(l) and section 2.2(d) of 
Appendix V to 40 CFR part 51 is through a modeling demonstration that 
they assert is required by section 2.2(e) of Appendix V to 40 CFR part 
51.
---------------------------------------------------------------------------

    \12\ The ADEQ's SIP-approved minor NSR program expressly 
regulates oxides of nitrogen (NOX) and sulfur dioxide 
(SO2) as PM2.5 precursors at R18-2-101(123).
---------------------------------------------------------------------------

    To evaluate the commenters' concerns, it is important to understand 
the requirements in the Act governing how permitting authorities must 
address precursors in NSR programs for nonattainment areas. Part D of 
title I of the Act contains specific requirements for the development 
of an NNSR program for major sources (and major modifications) in 
nonattainment areas. Among other requirements, in a PM2.5 
nonattainment area, the NNSR program must apply to major sources of 
direct PM2.5 emissions and to major sources of 
PM2.5 precursors, unless the EPA determines that such 
precursor sources do not contribute significantly to PM2.5 
levels that exceed the standard in the nonattainment area. See CAA 
section 189(e). For purposes of the NNSR program, the EPA has 
identified NOX, SO2, VOCs, and ammonia as 
precursors to PM2.5. See 40 CFR 51.165(a)(1)(xxxvii)(C)(2). 
Our proposed action explained that we have determined that the ADEQ's 
NNSR program for PM2.5 fully satisfies CAA section 189(e), 
and the commenters do not dispute this. The requirements of CAA section 
189(e) do not, however, apply to NSR permitting under the minor NSR 
program.
    The Act's requirements for minor NSR programs are far less 
prescriptive in general than those applicable for NSR programs 
regulating proposed new major sources and major modifications. CAA 
section 110(2)(a)(C), which governs minor NSR programs, requires the 
``regulation of the modification and construction of any stationary 
source within the areas covered by the plan as necessary to assure that 
national ambient air quality standards are achieved.'' (emphasis added) 
The EPA's implementing regulations for minor NSR programs require that 
such programs include legally enforceable procedures that enable the 
state to determine whether the construction or modification of sources 
will result in a violation of applicable portions of the control 
strategy or interference with attainment or maintenance of the NAAQS, 
and, if so, to prevent such construction or modification. See 40 CFR 
51.160(a)-(b). States are not required to regulate the construction of 
all new or modified stationary sources under their minor NSR programs; 
rather, the procedures must identify the types and sizes of sources 
regulated under the state's minor NSR program, and the state's plan 
must discuss the basis for determining which sources will be subject to 
review. 40 CFR 51.160(e).\13\ Thus, the Act provides considerable 
discretion for permitting authorities to develop minor NSR programs 
determined ``necessary'' to assure the NAAQS are achieved in their 
respective geographic areas. Consistent with CAA section 110(a)(2)(C) 
and the implementing regulations governing minor NSR programs at 40 CFR 
51.160-

[[Page 31931]]

51.164, the EPA has determined, as explained in our proposal, that the 
ADEQ's program now meets the relevant requirements for a minor NSR 
program.
---------------------------------------------------------------------------

    \13\ The EPA's implementing regulations also include other 
largely procedural requirements for minor NSR programs at 40 CFR 
51.160-51.164.
---------------------------------------------------------------------------

    In response to the commenter's specific concerns here, we consider 
the two PM2.5 nonattainment areas in Arizona--Nogales and 
West Central Pinal. Regarding the Nogales area, where the ADEQ has 
minor NSR permitting jurisdiction, the ADEQ's 2020 Minor NSR submittal 
explains that ``[t]he Nogales PM2.5 nonattainment area was 
found to have attained the 2006 24-hour PM2.5 NAAQS in 
2017.'' \14\ Further, while the ADEQ's minor NSR program does not 
specifically regulate VOC as a PM2.5 precursor, minor 
sources of VOC are, in fact, regulated by the ADEQ's minor NSR program 
at a source-wide permitting threshold of 20 tons per year. The 2020 
Minor NSR submittal contains an analysis showing that this permitting 
threshold is expected to cover at least 86% of VOC emissions in areas 
subject to ADEQ permitting jurisdiction.\15\ For the West Central Pinal 
PM2.5 nonattainment area, the Pinal County Air Quality 
Control District, not the ADEQ, has primary permitting jurisdiction for 
minor sources. Accordingly, the ADEQ's minor NSR permitting program 
generally does not apply in the West Central Pinal PM2.5 
nonattainment area.\16\
---------------------------------------------------------------------------

    \14\ 2020 Minor NSR submittal at 19; section 4.4.3.2. See also 
82 FR 21711 (May 10, 2017) (EPA determination of attainment by the 
attainment date).
    \15\ 2020 Minor NSR submittal at 16; Table 4-2.
    \16\ We also note that the ADEQ's March 29, 2019 SIP revision 
related to ammonia as a PM2.5 precursor provides results 
from a 2010 ADEQ study that determined the speciation of 
PM2.5 emissions in the West Central Pinal nonattainment 
area. The study showed that 90% of PM2.5 emissions in the 
West Central Pinal nonattainment area originate from direct 
PM2.5 sources, and less than 10% from PM2.5 
precursors. March 29, 2019 SIP submittal at 11; Table 3-3.
---------------------------------------------------------------------------

    Although the commenters mention certain types of operations that 
may emit ammonia and VOCs, the commenters do not provide information or 
explanation that demonstrates that the ADEQ's regulating those 
pollutants as precursors to PM2.5 in the PM2.5 
nonattainment areas under the ADEQ's jurisdiction as part of the ADEQ's 
minor NSR program is necessary to achieve the PM2.5 NAAQS in 
any such areas. As explained above, the only PM2.5 
nonattainment area where the ADEQ has primary jurisdiction for minor 
sources, the Nogales area, is already attaining the PM2.5 
NAAQS. Moreover, in addition to regulating direct PM2.5 
emissions, the ADEQ's minor NSR program regulates emissions of 
NOX and SO2 as PM2.5 precursors and 
regulates VOC emissions in general. In light of the information 
described above, we find that the ADEQ's determination to not regulate 
sources of ammonia and VOCs as PM2.5 precursors in its minor 
NSR program in the PM2.5 nonattainment areas under its 
jurisdiction is reasonable and not necessary to ensure that the 
PM2.5 NAAQS are achieved.
    The commenters also indicate that the EPA's approval of the 2020 
Minor NSR submittal conflicts with the requirement in CAA section 
110(l) that the EPA ``shall not approve a revision of a plan if the 
revision would interfere with any applicable requirement concerning 
attainment and reasonable further progress. . .or any other applicable 
requirement of this chapter.'' Our December 23, 2020 proposed approval 
contained our analysis that our action met these requirements of CAA 
section 110(l): ``We have determined that our action on the 2019-20 NSR 
submittals would, as described herein, strengthen the applicable SIP. 
This action is primarily intended to correct numerous deficiencies in 
the ADEQ's NSR program and provides other revisions to enhance and 
update the program. Accordingly, this action will not interfere with 
attainment and reasonable further progress, or any other applicable 
requirement.'' \17\ The commenters did not address this analysis or 
explain how this action to correct deficiencies in the ADEQ's minor NSR 
program will interfere with any applicable requirement concerning 
attainment and reasonable further progress or any other CAA requirement 
in the PM2.5 nonattainment areas under the ADEQ's 
jurisdiction that are of concern to the commenter. This action 
strengthens the overall SIP and does not relax any SIP requirements 
related to attaining the PM2.5 NAAQS in Arizona.
---------------------------------------------------------------------------

    \17\ 85 FR 83868, 83876 (Dec. 23, 2020).
---------------------------------------------------------------------------

    The commenters make the related argument that the ADEQ's SIP 
revision does not satisfy section 2.2(d) of Appendix V to 40 CFR part 
51 because it does not regulate VOCs and ammonia as precursors to 
PM2.5 and therefore interferes with attainment of the 
PM2.5 NAAQS in areas under ADEQ's jurisdiction that are 
designated nonattainment for PM2.5.\18\ As described above, 
the 2019-20 SIP submittals contain sufficient information to support 
our conclusion that the ADEQ's decision not to specifically regulate 
VOC and ammonia as PM2.5 precursors for its minor NSR 
program is acceptable and will not interfere with attainment of the 
PM2.5 NAAQS.
---------------------------------------------------------------------------

    \18\ The commenters reference the portion of section 2.2(d) that 
requires SIP submittals to ``demonstrat[e] that the national ambient 
air quality standards, prevention of significant deterioration 
increments, reasonable further progress demonstration, and 
visibility, as applicable, are protected if the plan is approved and 
implemented.'' See 40 CFR part 51, Appendix V, section 2.2(d).
---------------------------------------------------------------------------

    Lastly, in response to the commenter's argument that the ADEQ 
should have included a modeling demonstration relating to ammonia and 
VOC as PM2.5 precursors to meet the requirements of section 
2.2(e) of Appendix V to 40 CFR part 51, the commenters have not 
accurately characterized these requirements.\19\ We do not interpret 
section 2.2(e) of Appendix V to require that every SIP submittal 
contain a modeling demonstration, as implied by the commenters. 
Instead, when a modeling demonstration is necessary and is therefore 
included in a submittal to support the SIP revision, then the submittal 
must also contain the underlying modeling information outlined in 
section 2.2(e). We find that section 2.2(e) of Appendix V is not 
applicable to the 2020 Minor NSR submittal because modeling was not 
used to support this SIP revision nor was a modeling demonstration 
required in this instance.
---------------------------------------------------------------------------

    \19\ Section 2.2(e) of Appendix V requires that a SIP submittal 
include the ``[m]odeling information required to support the 
proposed revision, including input data, output data, models used, 
justification of model selections, ambient monitoring data used, 
meteorological data used, justification for use of offsite data 
(where used), modes of models used, assumptions, and other 
information relevant to the determination of adequacy of the 
modeling analysis.''
---------------------------------------------------------------------------

    Comment: The commenters consider the ADEQ's minor NSR thresholds of 
one-half the ``significant'' emission rates (SERs) in the PSD program 
\20\ to be arbitrary and unsupported by modeling or other evidence 
demonstrating protection of the NAAQS, in violation of CAA section 
110(l) and sections 2.2(d) and (e) in Appendix V to 40 CFR part 51. The 
commenters argue that merely comparing the percentage of emissions 
regulated by the ADEQ's program to other programs does not address 
whether thresholds are ``protective of the NAAQS''. The commenters 
assert that the ADEQ misplaced focus on the contributions of current 
sources in nonattainment areas under its jurisdiction and whether those 
areas are now violating the NAAQS. Instead, the ADEQ should have 
focused on ensuring that additional sources (or new modifications of 
existing sources) do not jeopardize attainment or maintenance of the 
NAAQS in the future.
---------------------------------------------------------------------------

    \20\ See 40 CFR 51.166(b)(23)(i).
---------------------------------------------------------------------------

    Response: We respectfully disagree with the commenters that the 
ADEQ has not provided an adequate rationale for

[[Page 31932]]

its permitting exemption thresholds for minor sources in nonattainment 
areas and minor sources of PM2.5 in attainment areas under 
CAA section 110(l) and Appendix V to 40 CFR part 51.
    First, we note that with the exception of the thresholds for 
PM2.5 sources, in our 2015 NSR action, the EPA previously 
approved the ADEQ's permitting thresholds for minor NSR as they apply 
in attainment areas, and, accordingly, those thresholds were not 
changed as part of the 2020 Minor NSR submittal. The EPA's prior 
approval was based on the ADEQ's demonstration that the emissions from 
the sources and projects to be exempted from its minor NSR program 
under these thresholds were inconsequential to attainment or 
maintenance of the NAAQS.\21\ However, in our 2015 NSR action, we also 
determined that the ADEQ had not provided a rationale for the 
PM2.5 permitting exemption threshold, nor had it provided an 
adequate rationale for why the permitting exemption thresholds were 
appropriate for nonattainment areas. \22\ In this action, we are 
considering only the 2020 Minor NSR submittal and the ADEQ's rationale 
for its permitting exemption thresholds as they apply to minor sources 
in nonattainment areas, and to minor sources of PM2.5 in 
attainment areas.
---------------------------------------------------------------------------

    \21\ In reviewing the ADEQ's minor NSR program under 40 CFR 
51.160(e), we considered it appropriate for the ADEQ to exclude 
emissions from its NSR program if such emissions would be 
``inconsequential to attainment or maintenance of the NAAQS.'' 80 FR 
67319, 67325. This was the same standard that the EPA used in 
developing the permitting thresholds for its minor NSR program for 
Indian country. 76 FR 38748, 38758 (Jul. 1, 2011).
    \22\ Id.
---------------------------------------------------------------------------

    The commenters specifically take issue with the ADEQ's comparing 
the percentage of emissions regulated by its NSR program to the 
percentage of emissions regulated by other NSR programs, and assert 
that the ADEQ's approach should focus more on future sources of 
emissions and ensuring that such sources do not jeopardize the NAAQS. 
As described below, the ADEQ's approach did not rest solely on 
comparing its permitting thresholds to other programs, and we find that 
the approach ensures that the ADEQ's minor NSR program reviews the 
necessary sources to ensure attainment and maintenance of the NAAQS.
    Prior to 2012, the ADEQ's minor NSR program required permitting of 
non-major sources with potential emissions of a criteria pollutant at 
or above the SERs from the PSD program reflected in 40 CFR 
51.166(b)(23)(i). To address concerns raised by the EPA regarding these 
historic permitting thresholds, the ADEQ assessed other potential lower 
permitting thresholds for its minor NSR program and ultimately selected 
revised, lower thresholds. In 2012, the ADEQ chose to use a method 
similar to the method that the EPA used to develop permitting 
thresholds under its minor NSR program applicable in Indian country, 
known as the ``Tribal Minor NSR rule.'' \23\ To inform its selection of 
minor NSR permitting thresholds in developing the Tribal Minor NSR 
rule, the EPA conducted a source distribution analysis using data from 
the National Emissions Inventory. The EPA's analysis concluded that the 
percentage of emissions that would be exempt from minor NSR under the 
Tribal Minor NSR rule's thresholds would be small (less than 1.5% of 
total emissions for each pollutant), while the program's permitting 
thresholds would require only 14-58% of stationary sources (varying 
based on the individual pollutant) to obtain permits or register under 
the Tribal Minor NSR rule. The EPA's analysis determined that this 
approach provided ``evidence that sources with emissions below the 
proposed minor NSR thresholds will be inconsequential to attainment and 
maintenance of the NAAQS.'' \24\ We stated that the permitting 
thresholds for the minor NSR program applicable in Indian country are 
``not intended to establish a new set of minimum criteria that a Tribe 
or a state would need to follow in developing its own minor source 
permitting program.'' \25\ Nevertheless, the approach taken by the EPA 
in developing the thresholds in the Tribal Minor NSR rule represents 
one approach that EPA has found to be appropriate in establishing such 
thresholds.
---------------------------------------------------------------------------

    \23\ 76 FR 38748 (July 1, 2011).
    \24\ 71 FR 48695, 48701-48703 (Aug. 21, 2006).
    \25\ 76 FR 38748, 38754.
---------------------------------------------------------------------------

    To assess potential thresholds for its minor NSR program, the ADEQ 
applied a similar approach to a local data set. During the stakeholder 
process, the ADEQ proposed two alternative scenarios for its revised 
minor NSR thresholds: One that generally used one half of the PSD SERs 
(Scenario 1) and one that generally used one quarter of the PSD SERs 
(Scenario 2). The ADEQ's analysis looked at the percentage of emissions 
that would be regulated at the two thresholds and concluded that ``both 
scenarios result in a relatively large percentage of emissions being 
subject to regulation compared to the percentage of sources brought 
into the program.'' The results of the analysis showed that using 
Scenario 2 for the minor NSR emission thresholds rather than Scenario 1 
would result in significantly more coverage of carbon monoxide (CO) and 
SO2 emissions under the ADEQ's minor NSR program. However, 
the ADEQ reasoned that stationary source emissions of CO are generally 
dwarfed by mobile source emissions and do not contribute significantly 
to nonattainment of the CO NAAQS. Also, the ADEQ reasoned that in the 
areas within Arizona that are subject to its minor NSR program, the 
sources that could contribute to noncompliance with the SO2 
NAAQS are well-defined and consist of large industrial sources already 
subject to the permitting program. The ADEQ concluded, based on the 
above considerations, that for purposes of minor NSR, use of the 
Scenario 2 thresholds would not offer any substantial benefits over 
Scenario 1, and set numerical exemption thresholds for the pollutants 
in its minor NSR program that equate to one half of the PSD SERs.\26\
---------------------------------------------------------------------------

    \26\ See Appendix A of the ADEQ's 2012 NSR SIP submittal at 
1547-1549 for a detailed discussion of the ADEQ's approach and 
analysis. See also, the Technical Support Document for the EPA's 
Notice of Proposed Rulemaking, Revision to the Arizona State 
Implementation Plan for the Arizona Department of Environmental 
Quality, March 2015 (``EPA's 2015 TSD'') at 22-25. The ADEQ's 
``permitting exemption thresholds'' are found at R18-2-101(101). The 
thresholds are ton per year values set for various pollutants that 
determine when a permit or registration is required for new sources 
and when minor NSR review is triggered for modifications. If 
potential source-wide emissions from all regulated pollutants are 
below the permitting exemption thresholds, then the source is 
``exempt'' from the ADEQ's permitting and registration program.
---------------------------------------------------------------------------

    In response to the EPA's determination in our 2015 NSR action that 
the ADEQ needed to justify the chosen permitting thresholds for 
PM2.5 and to further justify the thresholds as they apply in 
nonattainment areas, in its 2020 Minor NSR submittal, the ADEQ 
continued to build on its prior analyses supporting the current 
permitting thresholds in its minor NSR program.\27\ First, the ADEQ 
updated its prior source distribution analysis to use the National 
Emissions Inventory, the same data set that the EPA used for its 
analysis for the Tribal Minor NSR program, and to include 
PM2.5 emissions. The analysis shows that the ADEQ's NSR 
program is expected to cover approximately 98% of PM2.5 
emissions in counties where the ADEQ has minor source permitting 
jurisdiction and approximately 96% of PM2.5 emissions in 
PM2.5 nonattainment areas where the ADEQ has minor source 
permitting jurisdiction. Further, the

[[Page 31933]]

ADEQ considered the types of emission sources in each of the 
nonattainment areas where it has minor source permitting jurisdiction 
that contribute to nonattainment. For example, the Hayden and Miami 
SO2 nonattainment areas are attributable to the copper 
smelters operating in each area, and the Nogales nonattainment area for 
particular matter with an aerodynamic diameter less than or equal to 10 
microns (``PM10'') is attributable to paved road dust, 
construction, and residential wood burning. As we summarized in the TSD 
for our December 23, 2020 proposed action, ``[t]his discussion shows 
that minor sources are not currently significant contributors to the 
nonattainment issues in these areas.'' \28\
---------------------------------------------------------------------------

    \27\ See 2020 Minor NSR submittal at 14-20 for the full 
discussion.
    \28\ Technical Support Document for EPA's Notice of Proposed 
Rulemaking: Air Plan Approval; Arizona; Stationary Sources; New 
Source Review Updates, November 2020 (``EPA's 2020 TSD'') at 15.
---------------------------------------------------------------------------

    In consideration of the information summarized in this response, we 
disagree with the commenters that the ADEQ's approach to revising its 
minor source permitting thresholds for PM2.5 and in 
designated nonattainment areas where it has minor source permitting 
jurisdiction was arbitrary and unsupported. We find that the ADEQ has 
provided sufficient evidence that its NSR program will apply to the 
vast majority of emissions where the ADEQ has permitting jurisdiction, 
including in Arizona's nonattainment areas, and including 
PM2.5 emissions in attainment areas.\29\ As a result, we 
conclude that those emissions exempted from the ADEQ's NSR program 
under its minor NSR permitting exemption thresholds will be 
inconsequential to attainment and maintenance of the NAAQS.
---------------------------------------------------------------------------

    \29\ The ADEQ's program requires permitting or registration for 
new and existing sources. While a NAAQS review is generally only 
triggered for new sources or modifications, the ADEQ's permitting of 
existing sources provides additional protection that such sources 
are also complying with all other applicable CAA requirements.
---------------------------------------------------------------------------

    While we agree with the commenters' general proposition that the 
NSR program focuses on the review of new sources and modifications to 
existing sources, we disagree that this means that the rationale and 
analysis provided by the ADEQ to support its permitting exemption 
thresholds is inadequate. The commenters have not suggested or provided 
an alternative analysis that they believe would be appropriate to 
demonstrate the insufficiency of the minor NSR thresholds at issue, 
other than a generic reference to ``modeling.'' We find the ADEQ's 
rationale persuasive and find that the ADEQ has demonstrated that the 
permitting thresholds it has established by considering local 
conditions will capture the types and sizes of sources that are 
necessary for review to ensure such sources will not interfere with 
attainment and maintenance of the NAAQS in the areas where the ADEQ has 
minor NSR permitting jurisdiction.\30\ Thus, the additional analysis 
and information provided by the ADEQ in the 2020 Minor NSR submittal is 
sufficient for demonstrating that the permitting thresholds for minor 
sources in nonattainment areas and minor sources of PM2.5 in 
attainment areas meet the requirements of CAA section 110(l) and 
Appendix V to 40 CFR part 51 \31\ and will not interfere with 
attainment and maintenance of the NAAQS.
---------------------------------------------------------------------------

    \30\ The NSR program is only one aspect of the CAA requirements 
that must be implemented to ensure attainment and maintenance of the 
NAAQS. The NSR program is generally intended to allow for increases 
in emissions if it can be demonstrated that the increases will not 
interfere with attainment. Among other CAA programs, the 
comprehensive set of requirements found in CAA title I, part D are 
designed to ensure that State and local authorities with 
jurisdiction over nonattainment areas require the necessary 
reductions to reach attainment.
    \31\ As explained above, the commenters do not accurately 
characterize the SIP submittal completeness criteria in Section 
2.2(e) of Appendix V to 40 CFR part 51 as it relates to modeling. We 
find that section 2.2(e) is not applicable to the 2020 Minor NSR 
submittal because it did not contain modeling to support the SIP 
revision, nor is modeling required in this instance.
---------------------------------------------------------------------------

    Comment: The commenters assert that the 2020 Minor NSR submittal 
fails to demonstrate under 40 CFR 51.160(e) that review of 
``agricultural equipment used in normal farm operations'' under the 
ADEQ's minor NSR program is not needed for the ADEQ's program to meet 
federal NSR requirements for attainment and maintenance of the NAAQS or 
review for compliance with the control strategy. The commenters take 
issue with several aspects of the ADEQ's rationale, that we discuss in 
detail below, and further conclude that this exemption violates CAA 
section 110(l) and sections 2.2(d) and (e) of Appendix V to 40 CFR part 
51.
    Response: As discussed below, we respectfully disagree with the 
commenters that the 2020 Minor NSR submittal does not demonstrate that 
the State's exemption for ``agricultural equipment used in normal farm 
operations'' in its NSR program is approvable under 40 CFR 51.160(e). 
The ADEQ's submittal demonstrates that regulation of these exempt 
sources under its minor NSR program is not needed for ADEQ's program to 
meet federal NSR requirements for attainment and maintenance of the 
NAAQS or review for compliance with the control strategy. As the ADEQ 
has explained in detail, this exemption could potentially apply only to 
a very narrow group of minor sources that would not otherwise be exempt 
from minor NSR review under exemptions already approved by the EPA in 
our 2015 NSR action. Further, the ADEQ retains authority to require a 
permit even for the sources that will fit within this exemption if it 
determines that doing so is necessary to protect the NAAQS or 
enforcement of the control strategy. For these reasons, we also 
disagree that the exemption violates CAA section 110(l) and section 
2.2(d) of Appendix V to 40 CFR part 51.\32\
---------------------------------------------------------------------------

    \32\ As noted previously, the commenters do not accurately 
characterize section 2.2(e) of Appendix V, which requires that SIP 
submittals include certain information that supports modeling when 
modeling is otherwise required to be conducted for a SIP revision. 
The CAA does not require all SIP submittals to contain modeling, and 
modeling was not included in or required to support the 2020 Minor 
NSR submittal. Therefore, we continue to find that section 2.2(e) of 
Appendix V is not applicable to the 2020 Minor NSR submittal in 
general, nor does it apply specifically to the ADEQ's demonstration 
supporting the exemption of agricultural equipment used in normal 
farm operations.
---------------------------------------------------------------------------

    The State of Arizona exempts ``agricultural equipment used in 
normal farm operations'' from the general requirement to obtain an air 
permit.\33\ The ADEQ's permitting regulations implement this exemption 
by exempting ``agricultural equipment used in normal farm operations'' 
from the requirement to obtain a registration or permit at R18-2-
302(C). R18-2-302(C) makes clear that this exemption does not apply if 
the source is a ``major source'' or if ``operation without a permit 
would result in a violation of the [Clean Air] Act.'' R18-2-302(C)(2) 
also clarifies that ``agricultural equipment used in normal farm 
operations'' does not include equipment classified as a source that 
requires a permit under title V of the Act or that is subject to a 
standard under 40 CFR parts 60, 61, or 63.
---------------------------------------------------------------------------

    \33\ See ARS 49-426(B), which states, in part, in reference to 
the State law requirements for obtaining air permits: ``The 
provisions of this section shall not apply to motor vehicles, to 
agricultural vehicles or agricultural equipment used in normal farm 
operations, or to fuel burning equipment which, at a location or 
property other than a one or two family residence, is rated at less 
than one million British thermal units per hour.'' (emphasis added)
---------------------------------------------------------------------------

    We identified this exemption as one of the bases for our limited 
disapproval of the ADEQ's 2012 NSR SIP submittal in our 2015 NSR action 
because the submittal did not adequately justify the exemption as 
required by 40 CFR 51.160(e),\34\ and it was unclear how the

[[Page 31934]]

exemption in state law applied in the context of the ADEQ's NSR 
program.\35\ In response to this limited disapproval, the ADEQ provided 
a detailed discussion of the exemption in the 2020 Minor NSR submittal. 
As summarized below, the ADEQ's 2020 Minor NSR submittal demonstrates 
that the exemption is only available to a limited set of minor sources 
not otherwise exempt under exemptions we have already approved into the 
Arizona SIP as part of the ADEQ's NSR program, and the program's 
potential exemption of such sources would be inconsequential to 
attainment and maintenance of the NAAQS.
---------------------------------------------------------------------------

    \34\ See 40 CFR 51.160(e): ``The procedures must identify types 
and sizes of facilities, buildings, structures, or installations 
which will be subject to review under this section. The plan must 
discuss the basis for determining which facilities will be subject 
to review.''
    \35\ See section 5.2.2.3 of the EPA's 2015 TSD at 26-27 and 80 
FR 67319, 67323.
---------------------------------------------------------------------------

    First, the 2020 Minor NSR submittal clarified that the exemption at 
R18-2-302(C) represents the ADEQ's interpretation of the agricultural 
exemption in Arizona Revised Statutes (ARS) section 49-426(B):

    This rule represents ADEQ's official implementation and 
interpretation of the statutory exemption under its rulemaking 
authority in ARS Sec. Sec.  49-425 and 49-426(B). The rule has been 
recognized as valid by the Arizona Attorney General in its opinion 
supporting the state's Title V program in 1993.\36\ In approving 
Arizona's Title V program in 1996, EPA deferred to this opinion but 
stated that it would revisit this issue if ``a successful legal 
challenge to [the regulatory exemption] occurs.'' \37\ In the 
subsequent 23 years, there has been no such challenge.
---------------------------------------------------------------------------

    \36\ Attorney General's Opinion, 2 (Nov. 15, 1993), Appendix D 
of the 2020 Minor NSR submittal.
    \37\ 61 FR 55910, 55915 (Oct. 30, 1996).

Section 4.2.1 of the 2020 Minor NSR submittal at 10.
    Second, the ADEQ confirmed that the ADEQ interprets its permitting 
requirements such that its permitting determinations (including for the 
registration program component of its minor NSR program) are made on a 
source-wide basis. As a result, if ``agricultural equipment used in 
normal farm operations'' is located at the same stationary source as 
equipment that requires a permit, then the ADEQ's permit requirements, 
and potentially NSR, extend to the entire source and all of its 
pollutant-generating activities, including any equipment that might 
otherwise meet the definition of ``agricultural equipment used in 
normal farm operations''. These two clarifications mean that the 
agricultural equipment exemption is potentially available only to a 
subset of minor sources. See section 4.2.2 of the 2020 Minor NSR 
submittal at 10-11.
    While the term ``normal farm operations'' is not specifically 
defined by statute or rule, the ADEQ stated that the State of Arizona's 
Agricultural Best Management Practices (Ag BMP) program for commercial 
farming operations in PM10 nonattainment areas provides 
guidance on the State's interpretation of the types of activities that 
constitute normal farm operations. This includes activities such as 
tillage, planting, and harvesting; areas of a commercial farm that are 
not normally in crop production (i.e., fallow); areas of a commercial 
farm that are normally in crop production; significant agricultural 
earthmoving activities; traffic over unpaved access connections or 
unpaved roads or feed lanes; animal waste handling and transporting; 
arenas, corrals, and pens; and canals. The ADEQ stated that it 
interprets the normal farm operations exemption as applicable to the 
types of equipment used for these activities and to crop and feed 
processing equipment that produces only fugitive emissions. In the 
ADEQ's experience, farm emissions tend to consist almost exclusively of 
fugitive dust generated by the disturbance of soils. It is important to 
note that the ADEQ's current SIP-approved NSR program already exempts 
fugitive emissions,\38\ at R18-2-302(F), in determining whether a 
stationary source is subject to minor NSR permitting requirements. See 
sections 4.2.3 and 4.2.4 of the 2020 Minor NSR submittal at 11-12.\39\ 
As a result, most of the sources that would meet the definition of 
``agricultural equipment used in normal farm operations'' would be 
sources of fugitive emissions that are already exempt from minor NSR 
under the ADEQ's SIP-approved minor NSR program.
---------------------------------------------------------------------------

    \38\ Fugitive emissions are defined in the ADEQ's SIP-approved 
regulations at R18-2-101(59) as ``those emissions which could not 
reasonably pass through a stack, chimney, vent, or other 
functionally equivalent opening.'' See section 4.2 of the 2020 Minor 
NSR submittal at 9, n.14.
    \39\ See also 80 FR 67319, 67320, Table 1.
---------------------------------------------------------------------------

    The ADEQ also recognized that it is possible for equipment used in 
normal farm operations to be a part of a stationary source that 
produces stack (i.e., non-fugitive) emissions greater than the ADEQ's 
permitting exemption thresholds, and it may also be possible for normal 
farm operations themselves to be configured in such a way as to produce 
stack emissions. However, the ADEQ believes that, in most cases, such a 
stationary source would not qualify for the permitting exemption 
because equipment used in normal farm operations ``does not include 
equipment classified as a source that requires a permit under Title V 
of the Act, or that is subject to a standard under 40 CFR 60, 61, or 
63.'' Because the ADEQ determines permit applicability on a source-wide 
basis, if a stationary source that engaged in normal farm operations 
qualified as a CAA title V source or included equipment subject to a 
New Source Performance Standard (NSPS) or National Emission Standard 
for Hazardous Air Pollutants (NESHAP) in 40 CFR parts 60, 61, or 63, 
then the entire source would require a permit, and potentially be 
subject to minor NSR if its emissions were above the ADEQ's minor NSR 
permitting exemption thresholds. In the ADEQ's experience, most 
permitted sources include one or more pieces of equipment subject to an 
NSPS, such as a boiler, stationary engine, or fuel storage tank. The 
ADEQ concluded that it is likely that if equipment used in normal farm 
operations were collocated with equipment with stack emissions 
exceeding the permitting exemption thresholds, at least some of that 
equipment would be subject to an NSPS, and therefore the normal farm 
operations exemption would not apply. See section 4.2.5 of the 2020 
Minor NSR submittal at 12-13.
    Finally, the ADEQ explained that under R18-2-302(C), equipment used 
in normal farm operations is not exempt if ``operation [of the 
equipment] without a permit would result in a violation of the Act,'' 
which provides a final safeguard for its NSR program. In a situation 
where agricultural equipment used in normal farm operations with stack 
emissions above the permitting exemption thresholds used the exemption 
to avoid permitting, the ADEQ would invoke this provision as necessary 
to ensure that any such source does not endanger attainment or 
maintenance of the NAAQS or enforcement of the control strategy. The 
ADEQ explained that whenever it becomes aware of such a source through 
citizen complaint, inspection of the facility under the Ag BMP program, 
inspection of a nearby or related facility, notice from a building 
permit agency, or other means, the ADEQ will evaluate the facility 
using the methodology in R18-2-302.01(C) to determine whether it should 
be subject to permitting and minor NSR. See section 4.2.5 of the 2020 
Minor NSR submittal at 13.
    In our proposed action, we found that the ADEQ had demonstrated 
that its exemption for agricultural equipment used in normal farm 
operations is extremely limited in scope, and the potential sources 
exempted from permitting would be inconsequential to attainment and 
maintenance of the

[[Page 31935]]

NAAQS. We stated that our determination was based on the ADEQ's 
interpretation of the narrow manner in which the exemption applies, the 
limited types of operations that are considered to be ``normal farm 
operations,'' and the ADEQ's retention of authority to address any 
potentially exempt sources that may endanger attainment or maintenance 
of the NAAQS or enforcement of the control strategy. We agreed that the 
vast majority of these operations are likely already exempted from the 
ADEQ's SIP-approved minor NSR program under the general exemption for 
excluding fugitive emissions in permitting applicability 
determinations. We concluded that the ADEQ's basis and explanation for 
the exemption from minor NSR review for agricultural equipment used in 
normal farm operations was acceptable.\40\
---------------------------------------------------------------------------

    \40\ 85 FR 83868, 83873.
---------------------------------------------------------------------------

    The commenters question certain aspects of the ADEQ's explanation 
and the EPA's rationale for approving the agricultural exemption as 
described above. First, the commenters disagree with the ADEQ's 
explanation of the permit exemption not being applicable to sources 
that are subject to a standard under 40 CFR parts 60, 61, or 63 or that 
are title V sources. The commenters do not see how this interpretation, 
which they say results in a ``blanket'' exemption for minor sources 
from permitting, is protective of the NAAQS. In response, this 
explanation simply clarifies the scope of the exemption by confirming 
that major sources and sources subject to a standard under 40 CFR parts 
60, 61, or 63 cannot use the exemption. We disagree with the commenters 
that this interpretation by the ADEQ results in a ``blanket'' exemption 
for minor sources. Among other things, we note that sources that are 
subject to a standard under 40 CFR parts 60, 61, or 63 are often minor 
sources. The ADEQ has clarified that if any aspect of a stationary 
source is subject to one of these federal standards, then the entire 
stationary source, including any ``agricultural equipment used in 
normal farm operations,'' becomes subject to the ADEQ's permitting 
program.\41\
---------------------------------------------------------------------------

    \41\ The commenters also state that ``the fact that no one has 
challenged [R18-2-302(C)] does not mean a challenge could not occur 
in the future.'' This concern appears to address the ADEQ's 
reference to the fact that the Arizona Attorney General issued an 
opinion recognizing the validity of this exemption in support of the 
State's Title V program in 1993. See section 4.2.1 of the 2020 Minor 
NSR submittal at 10. As the ADEQ explained, the EPA stated in 1996 
that it would defer to this opinion of the Arizona Attorney General 
in the absence of a successful legal challenge to the regulation. 
The commenters did not otherwise explain how this concern affects 
the approvability of the 2020 Minor NSR submittal.
---------------------------------------------------------------------------

    Second, the commenters take issue with the ADEQ's explanation that 
it expects the overwhelming majority of emissions from ``agricultural 
equipment used in normal farm operations'' to be fugitive emissions. 
The commenters assert that the fact that most of these exempted 
emissions are expected to be fugitive does not explain how the 
exemption is protective of the NAAQS. In response, it is important to 
understand the context for this explanation from the ADEQ. In our 2015 
NSR action, as part of our limited approval and limited disapproval of 
the ADEQ's NSR program, the EPA approved of the ADEQ minor NSR 
program's treatment of fugitive emissions in determining when a permit 
is required. The ADEQ's minor NSR program requires fugitive emissions 
to be included in permit applicability determinations for certain 
industrial source categories listed in R18-2-101(23), such as Portland 
cement plants, primary lead smelters, primary copper smelters, and 
fossil-fuel-fired steam electric plants; and for sources which, as of 
August 7, 1980, were being regulated under section 111 or 112 of the 
Act. Fugitive emissions are not included in permit applicability 
determinations for any other minor sources; however, fugitive emissions 
are reviewed in minor NSR permit actions for any source triggering 
review because of non-fugitive emissions. See R18-2-101(12), R18-2-
101(128), and R18-2-302(F). In our 2015 NSR action, we approved the 
ADEQ's minor NSR program under 40 CFR 51.160(e), including its 
treatment of sources of fugitive emissions, with the exception of the 
specific limited disapproval issues that we identified and that the 
ADEQ is addressing in the 2020 Minor NSR submittal. See section 5.2.2.3 
of the EPA's 2015 TSD at 26-27; 80 FR 67319, 67323, 67332. In its 2020 
Minor NSR submittal, the ADEQ is clarifying that the overwhelming 
majority of sources that could potentially use the agricultural 
equipment permit exemption are fugitive emissions sources that the EPA 
already approved for exemption from determining whether a permit is 
required, in our 2015 action. As a result, the agricultural equipment 
exemption does not create an additional large category of sources 
exempt from minor NSR permitting.
    The commenters, however, further argue that fugitive dust emissions 
from agricultural equipment are primarily addressed through the State's 
Ag BMP program, and that ``experience with the Ag BMP program in both 
Maricopa County and Pinal County has demonstrated that it is wholly 
inadequate to ensure compliance with the PM10 NAAQS.'' The 
commenters are concerned that the two PM10 nonattainment 
areas in Maricopa and Pinal counties continue to violate the NAAQS 
despite the adoption of the Ag BMP program. The commenters point to 
recent exceedances of the PM10 NAAQS in the Phoenix planning 
area (which covers portions of Maricopa and Pinal counties) and the 
fact that the West Pinal nonattainment area did not attain the 
PM10 standard by the attainment date and was recently 
reclassified to serious nonattainment for PM10. While the 
nonattainment issues in these areas are concerning, it is important to 
recognize that the Maricopa County Air Quality Department and Pinal 
County Air Quality Control District, rather than the ADEQ, have 
original jurisdiction for permitting minor sources in these areas of 
Arizona,\42\ thus the ADEQ's minor NSR program would generally be 
inapplicable in these areas. Given that the ADEQ's minor NSR program 
does not generally extend to sources in the Phoenix and West Pinal 
PM10 nonattainment areas, the commenters' concerns about the 
use of the Ag BMP program to address fugitive dust in the Phoenix and 
West Pinal PM10 nonattainment areas do not indicate that the 
ADEQ's regulation of exempt agricultural equipment used in normal farm 
operations in other areas that are within the ADEQ's minor NSR 
permitting jurisdiction is necessary for attainment and maintenance of 
the NAAQS.\43\
---------------------------------------------------------------------------

    \42\ See the ADEQ's July 2, 2014 supplement to the 2012 NSR SIP 
submittal at 8-9.
    \43\ We note that the commenters' general concerns about the 
sufficiency of the Arizona Ag BMP program in the Phoenix and West 
Pinal PM10 nonattainment areas are outside the scope of 
this action on revisions to the ADEQ's minor NSR program.
---------------------------------------------------------------------------

    Third, the commenters question the ADEQ's statement that ``[i]n the 
overwhelming majority of the remaining cases, equipment used in normal 
farm operations will be located at a stationary source that either 
qualifies as a title V source or includes equipment subject to a new 
source performance standard (NSPS)''. The commenters believe that the 
ADEQ has not supported this claim. The commenters are also concerned 
because they claim that the NSPS standards do not apply during periods 
of startup, shutdown, and malfunction, while the NAAQS apply at all 
times. We disagree that the ADEQ did not support this claim. Section 
4.2.5 of the 2020 Minor NSR submittal provides the

[[Page 31936]]

ADEQ's rationale.\44\ For example, the submittal explains that, in the 
ADEQ's experience, most permitted sources include one or more pieces of 
equipment subject to an NSPS, such as boilers, stationary engines, or 
fuel storage tanks. The ADEQ clarified that a stationary source subject 
to such a standard could not make use of the agricultural equipment 
exemption.
---------------------------------------------------------------------------

    \44\ 2020 Minor NSR submittal at 12-13.
---------------------------------------------------------------------------

    The ADEQ's submittal further explains that under section 111 of the 
Clean Air Act, EPA is required to maintain a list of, and adopt NSPS 
for, all categories of sources that cause or significantly contribute 
to ``air pollution which may reasonably be anticipated to endanger 
public health or welfare.'' The ADEQ notes that, consistent with the 
breadth of this charge, the EPA has adopted standards for dozens of 
common sources of criteria pollutants, criteria pollutant precursors, 
greenhouse gases, and other pollutants. The ADEQ reasons that it is 
therefore likely that if equipment used in normal farm operations were 
collocated with equipment with stack emissions exceeding the permitting 
exemption thresholds, at least some of that equipment would be subject 
to an NSPS, and the exemption would not apply.\45\
---------------------------------------------------------------------------

    \45\ Section 4.2.5 of the 2020 Minor NSR submittal at 12; see 
also the detailed discussion in section 4.2.5 of the 2020 Minor NSR 
submittal at 12-13.
---------------------------------------------------------------------------

    We believe the ADEQ's explanation to be sufficiently supported 
based on the ADEQ's knowledge and experience with the pollutant-
generating activities it oversees.\46\
---------------------------------------------------------------------------

    \46\ On the issue of the NSPS standards not applying during 
periods of startup, shutdown, or malfunction (we disagree with this 
broad categorization), while the NAAQS do, we believe the commenters 
misunderstand how the ADEQ's permitting program works and how the 
normal farm operations exemption would apply to a source that 
includes equipment subject to an NSPS. The ADEQ does not allow 
stationary sources to use the agricultural equipment exemption to 
avoid NSR review if the stationary source is also subject to a 
standard under 40 CFR parts 60, 61, or 63. This means that the 
entire stationary source becomes subject to the ADEQ's permitting 
program, including potential NAAQS reviews for new or modified 
sources, if even a single piece of equipment is subject to an NSPS. 
The way the various NSPS apply in general during periods of startup, 
shutdown, or malfunction is not germane to the scope of the normal 
farm operations exemption.
---------------------------------------------------------------------------

    Finally, the commenters challenge the ADEQ's statement that ``[i]n 
the few, if any, cases where equipment used in normal farm operations 
is located at a non-title V source that has stack emissions above the 
permitting exemption thresholds but does not include NSPS or NESHAP 
equipment, ADEQ retains the authority to require a permit to the extent 
necessary to assure protection of the NAAQS and the control strategy.'' 
\47\ The commenters express concern because they are unclear on how the 
ADEQ would know that a permit is needed or that there is a potential 
NAAQS issue if sources aren't required to submit applications for 
review. We understand the commenters' concern on this issue, because 
the NSR program is intended to require review of sources prior to 
construction or modification to ensure that sources and modifications 
are constructed in a manner that will not cause or contribute to a 
NAAQS violation. However, our approval of the ADEQ's agricultural 
equipment exemption under 40 CFR 51.160(e) is based on the totality of 
the information presented by the ADEQ in the 2020 Minor NSR submittal. 
The ADEQ has demonstrated that the exemption creates a narrow category 
of sources that may be exempt from minor NSR review, as compared to the 
program we have already approved. However, in the potential instances 
where a stationary source is otherwise not required to obtain a permit 
in advance, the ADEQ has clarified that it has the authority to later 
require a permit and limit operations to protect the NAAQS. That is, 
minor sources defined as agricultural equipment used in normal farm 
operations cannot operate in a manner that would interfere with 
attainment and maintenance of the NAAQS by relying on the permitting 
exemption in State law.
---------------------------------------------------------------------------

    \47\ 2020 Minor NSR submittal at 9.
---------------------------------------------------------------------------

    In sum, the ADEQ has provided a detailed and well-supported 
rationale for its exemption of ``agricultural equipment used in normal 
farm operations'' from its minor NSR program, and demonstrated that any 
potentially exempted sources are inconsequential to attainment and 
maintenance of the NAAQS. Further, because the exemption will not 
interfere with the NAAQS, it is consistent with CAA section 110(l) and 
section 2.2(d) of Appendix V to 40 CFR part 51.
    Comment: The commenters state that the ADEQ failed to justify the 
exemption for certain small stationary fuel burning equipment rated at 
less than one million British thermal units per hour (MMBtu/hr) found 
in Arizona state law. The commenters are concerned that the ADEQ's 
rationale does not justify the exemption or ensure protection of the 
NAAQS, as the ADEQ did not present modeling or other evidence in 
support of the exemption or to support that this equipment would not 
otherwise require a permit.
    Response: We disagree with the commenters that the ADEQ has not 
adequately justified the Arizona state law exemption for small fuel 
burning equipment (those rated at less than 1 MMBtu/hr) in ARS section 
49-426(B) within the context of its NSR program. The ADEQ's 2020 Minor 
NSR submittal provides an analysis of the state law exemption because 
the EPA identified it as a limited disapproval issue in our 2015 NSR 
action. In our 2015 NSR action, we found that the ADEQ's 2012 NSR 
submittal did not describe how the state law exemption for small fuel 
burning equipment applied in the context of its NSR program. Further, 
to the extent the ADEQ's NSR program exempts some sources from minor 
NSR review under the state law exemption, we found that the ADEQ needed 
to provide an adequate justification under 40 CFR 51.160(e).\48\
---------------------------------------------------------------------------

    \48\ See section 5.2.2.3 of the EPA's 2015 TSD at 26-27; 80 FR 
67319, 67323.
---------------------------------------------------------------------------

    In the 2020 Minor NSR submittal, the ADEQ confirmed that it 
interprets the exemption as (1) being available only to those 
stationary sources that consists ``solely of equipment with a 
cumulative heat input rate'' of less than 1 MMBtu/hr, and (2) having 
already been effectively SIP-approved by the EPA because all such 
equipment falls under the ADEQ's existing SIP-approved exemption for 
``categorically exempt activities'' at R18-2-302(C)(1) and R18-2-
101(23).\49\
---------------------------------------------------------------------------

    \49\ See section 4.3 of the 2020 Minor NSR submittal at 13-14.
---------------------------------------------------------------------------

    As explained by the ADEQ in the 2020 Minor NSR submittal, the EPA 
reviewed the ADEQ's permitting and registration exemption for 
``categorically exempt activities'' in our 2015 NSR action. R18-2-
302(C) provides that a stationary source that consists solely of a 
single ``categorically exempt activity'' plus any combination of 
trivial activities \50\ does not require a permit or registration, 
unless the source is a major source or operation without a permit would 
result in a violation of the Act. The ADEQ defines a ``categorially 
exempt activity'' at R18-2-101(24) and it includes various categories 
of smaller fuel-burning equipment. For example, one category is ``any 
combination of diesel-, natural gas- or gasoline-fired engines with 
cumulative power equal to or less than 145 horsepower'' and another is 
``any combination of boilers with a cumulative maximum design heat 
input capacity of less than 10 million Btu/hr.'' The ADEQ explained in 
its 2012 NSR SIP submittal how the cumulative heat input or power 
rating

[[Page 31937]]

for each category of equipment was determined by estimating the worst-
case potential emissions for the category and ensuring that such 
emissions would be below the ADEQ's permitting exemption 
thresholds.\51\ With this clarification, we approved of the 
``categorically exempt activities'' in the 2015 NSR action.\52\ To 
illustrate this concept, the 2020 Minor NSR submittal also contains a 
sample calculation for a boiler burning No. 6 fuel oil with a heat 
input rating of 10 MMBtu/hr. The sample calculation shows that 
potential emissions of NOX from such equipment would be 16.1 
tons per year and below the ADEQ's 20 tpy minor NSR permitting 
exemption threshold for NOX. Accordingly, the smaller fuel-
burning equipment, rated less than 1 MMBtu/hr, that is exempt under ARS 
section 49-426(B) would have emissions well below the ADEQ's approved 
permitting exemption thresholds, and therefore would not otherwise 
require a permit or registration under the ADEQ's program. The ADEQ 
explains that the purpose of the exemption for categorically exempt 
activities is to allow such low-emitting small fuel-burning 
installations, which would not in any case require a permit, to avoid 
having to perform unnecessary emissions calculations.\53\
---------------------------------------------------------------------------

    \50\ Trivial activities under the ADEQ's permitting program are 
defined R18-2-101(146).
    \51\ See Appendix A to the 2012 NSR SIP submittal at 1570 and 
1571.
    \52\ EPA's 2015 TSD at 25.
    \53\ Section 4.3 of 2020 Minor NSR submittal at 13-14.
---------------------------------------------------------------------------

    Given the rationale provided by the ADEQ, and our prior review and 
approval under 40 CFR 51.160(e) of the ADEQ's exemption of 
``categorically exempt activities'' under its minor NSR program, we 
disagree with the commenters that the ADEQ has not adequately justified 
the state law exemption.\54\ The ADEQ has demonstrated that fuel 
burning equipment rated less than 1 MMBtu/hr is equipment that falls 
within the existing SIP-approved category of ``categorically exempt 
activities,'' and also that it is equipment that would otherwise not 
require a permit or registration compared to the ADEQ's approved \55\ 
permitting thresholds. In sum, the state law exemption for small 
fueling burning equipment has previously been determined by the EPA to 
be inconsequential to attainment and maintenance of the NAAQS, and the 
commenters have not provided information demonstrating why they believe 
this exemption is not protective of the NAAQS, or otherwise provided 
information that calls into question our previous approval of the 
ADEQ's exemption for categorically exempt activities under 40 CFR 
51.160(e).
---------------------------------------------------------------------------

    \54\ The commenters specifically identified ``modeling'' as an 
example of the type of evidence to support this exemption. Modeling 
was not required to make this demonstration.
    \55\ In our 2015 NSR action, we approved of the ADEQ's 
``permitting exemption thresholds'' for each regulated pollutant, 
except PM2.5, and our approval of the thresholds was 
limited to their application in attainment areas. With today's 
action, we are now also approving the thresholds as they apply to 
PM2.5 and nonattainment areas.
---------------------------------------------------------------------------

    Comment: The ADEQ states that its NSR program applies to the areas 
of the State where the ADEQ has permitting jurisdiction (all counties 
in Arizona other than Maricopa, Pima, and Pinal, except where the ADEQ 
asserts jurisdiction). The commenters state that the ADEQ should 
explain whether the minor NSR programs in Maricopa, Pima, and Pinal 
counties are SIP-approved and meet all CAA requirements. To the extent 
they do not, the ADEQ should fix any deficiencies with the 2020 Minor 
NSR submittal.
    Response: As the commenters note, the 2020 Minor NSR submittal, and 
the requirements therein relating to the ADEQ's minor NSR permitting 
program, are applicable only to those portions of the Arizona SIP where 
the ADEQ has minor NSR permitting jurisdiction. The EPA reviewed the 
ADEQ's submitted SIP revision and determined that it complies with all 
relevant CAA requirements for approval into the Arizona SIP. In 
addition, this revision will correct several outstanding deficiencies 
in the ADEQ's minor NSR program that were previously identified by the 
EPA. The commenters' questions about the sufficiency of the minor NSR 
permitting programs for other areas and sources within Arizona that are 
within the jurisdiction of Maricopa, Pima, and Pinal counties, and 
which are not covered by ADEQ's minor NSR program, are not germane to 
the EPA's current SIP action on the 2020 Minor NSR submittal. The CAA 
does not require that the ADEQ (or the EPA) address all components of 
the minor NSR program implemented by all permitting authorities in 
Arizona in any particular SIP action.

III. EPA Action

    No comments changed our assessment of our proposed action. 
Therefore, as authorized in section 110(k)(3) of the Act, the EPA is 
approving the ADEQ's 2019-20 NSR submittals, specifically including the 
2020 Minor NSR submittal and the Ammonia PM2.5 NSR 
submittal. We find that the ADEQ has corrected all remaining 
deficiencies identified as the bases for our final limited disapproval 
of the ADEQ's NSR program in our 2015 NSR action and the basis for our 
conditional approval of the ADEQ's NNSR program in our 2018 Major NSR 
action. Thus, the issues that formed the basis for our final limited 
disapproval in 2015 of the ADEQ's minor NSR, PSD, and NNSR programs and 
our conditional approval in 2018 of the ADEQ's NNSR program are now 
fully resolved. Our final action updates the ADEQ's SIP-approved NSR 
program, corrects previously identified deficiencies, and recognizes 
that the ADEQ's NSR program also satisfies the CAA visibility 
requirements in 40 CFR 51.307. Additionally, the sanctions and 
sanctions clocks triggered by our 2016 PM2.5 precursor 
action for the West Pinal and Nogales PM2.5 nonattainment 
areas will be permanently terminated on the effective date of this 
final approval action.
    This action approves the rules listed in Table 1 of this notice 
into the ADEQ portion of the Arizona SIP and removes or supersedes the 
rules listed in Table 2 of this notice from the ADEQ portion of the 
Arizona SIP. We are also revising 40 CFR 52.119 to remove the 
conditional approval of the State's plan related to ammonia as a 
PM2.5 precursor, as we are now fully approving this 
component of the State's plan. Finally, in conjunction with the EPA's 
SIP approval of the ADEQ's visibility program for sources subject to 
the ADEQ's PSD and NNSR programs, we are revising 40 CFR 52.145(b) to 
remove the visibility FIP at 40 CFR 52.27, as well as the visibility 
FIP at 40 CFR 52.28 for those stationary sources subject to the ADEQ's 
permitting jurisdiction, as these FIPs are no longer applicable.

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 ADEQ 
rules described in the amendments to 40 CFR part 52 set forth below. 
Therefore, these materials have been approved by the EPA for inclusion 
in the SIP, have been incorporated by reference by the 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 the EPA's 
approval, and will be incorporated by reference in the next update to 
the SIP compilation.\56\ The EPA has made, and will continue to make, 
these documents available through https://www.regulations.gov and at 
the EPA Region IX Office (please contact the person identified in the 
FOR FURTHER

[[Page 31938]]

INFORMATION CONTACT section of this preamble for more information).
---------------------------------------------------------------------------

    \56\ 62 FR 27968 (May 22, 1997).
---------------------------------------------------------------------------

    Also in this document, as described in the amendments to 40 CFR 
part 52 set forth below, the EPA is removing provisions from the EPA-
approved rules for the ADEQ portion of the Arizona SIP, which is 
incorporated by reference in accordance with the requirements of 1 CFR 
part 51.

V. Statutory and Executive Order Reviews

    Under the CAA, the Administrator is required to approve a SIP 
submission that complies with the provisions of the 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 Act. Accordingly, this 
proposed action merely proposes to approve state law as meeting federal 
requirements and does not impose additional requirements beyond those 
imposed by state law. For that reason, this proposed action:
     Is not a ``significant regulatory action'' subject to 
review by the Office of Management and Budget under Executive Orders 
12866 (58 FR 51735, October 4, 1993) and 13563 (76 FR 3821, January 21, 
2011);
     Is not an Executive Order 13771 (82 FR 9339, February 3, 
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, as described in the Unfunded 
Mandates Reform Act of 1995 (Pub. L. 104-4);
     Does not have federalism implications as specified in 
Executive Order 13132 (64 FR 43255, August 10, 1999);
     Is not an economically significant regulatory action based 
on health or safety risks subject to Executive Order 13045 (62 FR 
19885, April 23, 1997);
     Is not a significant regulatory action subject to 
Executive Order 13211 (66 FR 28355, May 22, 2001);
     Is not subject to requirements of section 12(d) of the 
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 
note) because application of those requirements would be inconsistent 
with the CAA; and
     Does not provide the EPA with the discretionary authority 
to address disproportionate human health or environmental effects with 
practical, appropriate, 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 the EPA or an Indian tribe 
has demonstrated that a tribe has jurisdiction. In those areas of 
Indian country, the rule does not have tribal implications and will not 
impose substantial direct costs on tribal governments or preempt tribal 
law as specified by Executive Order 13175 (65 FR 67249, November 9, 
2000).

List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Carbon monoxide, 
Incorporation by reference, Intergovernmental relations, Nitrogen 
dioxide, Ozone, Particulate matter, Sulfur dioxide, Reporting and 
recordkeeping requirements, Volatile organic compounds.

    Authority:  42 U.S.C. 7401 et seq.

    Dated: June 8, 2021.
Deborah Jordan,
Acting Regional Administrator, Region IX.

    Accordingly, EPA amends Part 52, Chapter I, Title 40 of the Code of 
Federal Regulations as follows:

PART 52--APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS

0
1. The authority citation for part 52 continues to read as follows:

    Authority:  42 U.S.C. 7401 et seq.

Subpart D--Arizona

Sec.  52.119   [Amended]

0
2. In Sec.  52.119, remove and reserve paragraph (a).

0
3. In Sec.  52.120, paragraph (c), Table 2 is amended:
0
a. Under the heading ``Title 9, Chapter 3'', by removing the center 
heading ``Article 2'' and the entry for ``R9-3-217, paragraph A'';
0
b. Under the heading ``Title 18, Chapter 2, Article 1 (General)'', by 
revising the entry for ``R18-2-101 (except 20)'';
0
c. Under heading ``Title 18, Chapter 2, Article 3 (Permits and Permit 
Revisions)'', by:
0
i. Revising the entries for ``R18-2-301,'' ``R18-2-302,'' ``R18-2-
302.01,'' ``R18-2-304,'' ``R18-2-306,'' ``R18-2-306.01'';
0
ii. Adding, in numerical order, entries for ``R18-2-317,' ``R18-2-
317.01,'' and ``R18-2-317.02''; and
0
iii. Revising the entries for ``R18-2-319,'' ``R18-2-320,'' and ``R18-
2-334''; and
0
d. Under the heading ``Title 18, Chapter 2, Article 4 (Permit 
Requirements for New Major Sources and Major Modifications to Existing 
Major Sources)'', by revising the entry for ``R18-2-406.''
    The additions and revisions read as follows:

Sec.  52.120  Identification of plan.

* * * * *
    (c) * * *

                                    Table 2--EPA-Approved Arizona Regulations
----------------------------------------------------------------------------------------------------------------
                                                                                                   Additional
       State citation          Title/subject       State effective date     EPA approval date     explanation
----------------------------------------------------------------------------------------------------------------
 
                                                  * * * * * * *
----------------------------------------------------------------------------------------------------------------
                                               Article 1 (General)
----------------------------------------------------------------------------------------------------------------
R18-2-101 (except 20)......  Definitions......  February 1, 2020..........  [INSERT Federal    Submitted on July
                                                                             Register           22, 2020.
                                                                             CITATION], June
                                                                             16, 2021.
 

[[Page 31939]]

 
                                                  * * * * * * *
----------------------------------------------------------------------------------------------------------------
                                    Article 3 (Permits and Permit Revisions)
----------------------------------------------------------------------------------------------------------------
R18-2-301..................  Definitions......  February 1, 2020..........  [INSERT Federal    Submitted on July
                                                                             Register           22, 2020.
                                                                             CITATION], June
                                                                             16, 2021.
R18-2-302..................  Applicability;     March 21, 2017............  [INSERT Federal    Submitted on July
                              Registration;                                  Register           22, 2020.
                              Classes of                                     CITATION], June
                              Permits.                                       16, 2021.
R18-2-302.01...............  Source             February 1, 2020..........  [INSERT Federal    Submitted on July
                              Registration                                   Register           22, 2020.
                              Requirements.                                  CITATION], June
                                                                             16, 2021.
 
                                                  * * * * * * *
R18-2-304..................  Permit             February 1, 2020..........  [INSERT Federal    Submitted on July
                              Application                                    Register           22, 2020.
                              Processing                                     CITATION], June
                              Procedures.                                    16, 2021.
R18-2-306..................  Permit Contents..  March 21, 2017............  [INSERT Federal    Submitted on July
                                                                             Register           22, 2020.
                                                                             CITATION], June
                                                                             16, 2021.
R18-2-306.01...............  Permits            March 21, 2017............  [INSERT Federal    Submitted on July
                              Containing                                     Register           22, 2020.
                              Voluntarily                                    CITATION], June
                              Accepted                                       16, 2021.
                              Emission
                              Limitations and
                              Standards.
 
                                                  * * * * * * *
R18-2-317..................  Facility Changes   August 7, 2012............  [INSERT Federal    Submitted on July
                              Allowed Without                                Register           22, 2020.
                              Permit                                         CITATION], June
                              Revisions--Class                               16, 2021.
                              I.
R18-2-317.01...............  Facility Changes   August 7, 2012............  [INSERT Federal    Submitted on July
                              that Require a                                 Register           22, 2020.
                              Permit Revision--                              CITATION], June
                              Class II.                                      16, 2021.
R18-2-317.02...............  Procedures for     August 7, 2012............  [INSERT Federal    Submitted on July
                              Certain Changes                                Register           22, 2020.
                              that Do Not                                    CITATION], June
                              Require a Permit                               16, 2021.
                              Revision--Class
                              II.
R18-2-319..................  Minor Permit       March 21, 2017............  [INSERT Federal    Submitted on July
                              Revisions.                                     Register           22, 2020.
                                                                             CITATION], June
                                                                             16, 2021.
R18-2-320..................  Significant        March 21, 2017............  [INSERT Federal    Submitted on July
                              Permit Revisions.                              Register           22, 2020.
                                                                             CITATION], June
                                                                             16, 2021.
 
                                                  * * * * * * *
R18-2-334..................  Minor New Source   February 1, 2020..........  [INSERT Federal    Submitted on July
                              Review.                                        Register           22, 2020.
                                                                             CITATION], June
                                                                             16, 2021.
----------------------------------------------------------------------------------------------------------------
     Article 4 (Permit Requirements for New Major Sources and Major Modifications to Existing Major Sources)
----------------------------------------------------------------------------------------------------------------
 
                                                  * * * * * * *
R18-2-406..................  Permit             February 1, 2020..........  [INSERT Federal    Submitted on July
                              Requirements for                               Register           22, 2020.
                              Sources Located                                CITATION], June
                              in Attainment                                  16, 2021.
                              and
                              Unclassifiable
                              Areas.
 
                                                  * * * * * * *
----------------------------------------------------------------------------------------------------------------

* * * * *

0
4. In Sec.  52.145, revise paragraph (b) to read as follows:

Sec.  52.145   Visibility protection.

* * * * *
    (b) Regulations for visibility new source review. The provisions of 
Sec.  52.28 are hereby incorporated and made part of the applicable 
plan for the State of Arizona only for those stationary sources under 
the permitting jurisdiction of the Pima County Department of 
Environmental Quality or the Maricopa County Air Quality Department. 
The provisions of Sec.  52.28 also remain the applicable plan for any 
Indian reservation lands, and any other area of Indian country where 
the EPA or an Indian tribe has demonstrated that a tribe has 
jurisdiction, located within the State of Arizona.
* * * * *
[FR Doc. 2021-12431 Filed 6-15-21; 8:45 am]
BILLING CODE 6560-50-P
```