ENVIRONMENTAL PROTECTION AGENCY
                40 CFR Part 52
                [EPAR09OAR20210638; FRL910101R9]
                Clean Air Plans; Base Year Emissions Inventories for the 2015 Ozone Standards; Arizona; Phoenix-Mesa and Yuma Nonattainment Areas
                
                    AGENCY:
                    Environmental Protection Agency (EPA).
                
                
                    ACTION:
                    Proposed rule.
                
                
                    SUMMARY:
                    The Environmental Protection Agency (EPA) is proposing to approve, under the Clean Air Act (CAA), revisions to the Arizona State Implementation Plan (SIP) concerning the base year emissions inventory requirements for the Phoenix-Mesa ozone nonattainment area (Phoenix-Mesa) and Yuma ozone nonattainment area (Yuma) for the 2015 ozone national ambient air quality standards (NAAQS or standard).
                
                
                    DATES:
                    Any comments must arrive by November 22, 2021.
                
                
                    ADDRESSES:
                    
                        Submit your comments, identified by Docket ID No. EPAR09OAR20210638 at 
                        https://www.regulations.gov.
                         For comments submitted at 
                        Regulations.gov
                        , follow the online instructions for submitting comments. Once submitted, comments cannot be edited or removed from 
                        Regulations.gov
                        . The EPA may publish any comment received to its public docket. Do not submit electronically any information you consider to be Confidential Business Information (CBI) or other information whose disclosure is restricted by statute. Multimedia submissions (audio, video, etc.) must be accompanied by a written comment. The written comment is considered the official comment and should include discussion of all points you wish to make. The EPA will generally not consider comments or comment contents located outside of the primary submission (
                        i.e.,
                         on the web, cloud, or other file sharing system). For additional submission methods, please contact the person identified in the 
                        FOR FURTHER INFORMATION CONTACT
                         section. 
                        
                        For the full EPA public comment policy, information about CBI or multimedia submissions, and general guidance on making effective comments, please visit 
                        https://www.epa.gov/dockets/commenting-epa-dockets.
                         If you need assistance in a language other 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:
                    
                        Ben Leers, Air Planning Office (AIR2), EPA Region IX, (415) 9474279, 
                        Leers.Ben@epa.gov.
                    
                
            
            
                SUPPLEMENTARY INFORMATION:
                Throughout this document, we, us, and our refer to the EPA.
                Table of Contents
                
                    I. Background
                    A. Emissions Inventories
                    B. State Submittals
                    C. Public Notice and Hearing Requirements
                    II. Arizona's Emissions Inventories
                    A. Baseline Emissions Inventory for the Phoenix-Mesa Nonattainment Area
                    B. Baseline Emissions Inventory for the Yuma Nonattainment Area
                    III. EPA's Evaluation
                    IV. Proposed Action and Request for Public Comment
                    V. Statutory and Executive Order Reviews
                
                I. Background
                
                    On October 26, 2015, the EPA promulgated a revised 8-hour ozone NAAQS of 0.070 parts per million (ppm).
                    1
                    
                     In accordance with section 107(d) of the CAA, the EPA must designate an area nonattainment if it is violating the NAAQS or if it is contributing to a violation of the NAAQS in a nearby area.
                
                
                    
                        1
                         80 FR 65292 (October 26, 2015).
                    
                
                
                    The EPA designated two areas in Arizona as nonattainment for the 2015 ozone NAAQS on June 4, 2018, effective August 3, 2018.
                    2
                    
                     The Phoenix-Mesa nonattainment area (including Gila, Maricopa, and Pinal counties) and Yuma nonattainment area (including Yuma County) were classified as Marginal ozone nonattainment.
                
                
                    
                        2
                         83 FR 25776.
                    
                
                A. Emissions Inventories
                
                    Sections 172(c)(3) and 182(a)(1) of the CAA require states to develop and submit, as a SIP revision, base year emissions inventories for all areas designated as nonattainment for an ozone NAAQS. The EPA finalized the 2015 ozone NAAQS SIP Requirements Rule (SRR) on December 6, 2018. The SRR established implementation requirements for the 2015 ozone NAAQS, including requirements for base year emissions inventories under CAA section 182(a)(1).
                    3
                    
                     The SRR for the 2015 ozone NAAQS is codified at 40 CFR part 51, subpart CC, and the emissions inventory requirements are codified at 40 CFR 51.1315.
                
                
                    
                        3
                         83 FR 62998.
                    
                
                
                    An emissions inventory for ozone is an estimation of actual emissions of air pollutants that contribute to the formation of ozone in an area. Ozone is a gas that is formed by the reaction of volatile organic compounds (VOC) and oxides of nitrogen (NO
                    X
                    ), referred to as ozone precursors, in the atmosphere in the presence of sunlight. Therefore, an emissions inventory for ozone focuses on the emissions of VOC and NO
                    X
                    . VOC is emitted by many types of sources, including power plants, industrial sources, on-road and off-road mobile sources, smaller stationary sources collectively referred to as area sources, and biogenic sources. NO
                    X
                     is primarily emitted by combustion sources, both stationary and mobile.
                
                
                    Emissions inventories provide emissions data that inform a variety of air quality planning tasks, including establishing baseline emissions levels, calculating emissions reduction targets needed to attain the NAAQS and to achieve reasonable further progress (RFP) toward attainment of the ozone standard,
                    4
                    
                     determining emissions inputs for ozone air quality modeling analyses, and tracking emissions over time to determine progress toward achieving air quality and emissions reduction goals.
                
                
                    
                        4
                         The RFP requirements specified in CAA section 182(b)(1) apply to all areas classified as Moderate or higher ozone nonattainment. At the time of submittal of the Phoenix-Mesa and Yuma base year emissions inventory SIPs for the 2015 ozone NAAQS, the Phoenix-Mesa and Yuma areas were designated Marginal nonattainment for the 2015 ozone NAAQS and were therefore not required to demonstrate RFP toward attainment of the 2015 ozone NAAQS.
                    
                
                
                    For the 2015 ozone NAAQS, states are required to submit ozone season day emissions estimates for an inventory calendar year to be consistent with the baseline year for RFP plans as required by 40 CFR 51.1310(b).
                    5
                    
                     Under 40 CFR 51.1310(b), for the 2015 ozone NAAQS, the RFP baseline year is the most recent calendar year for which a complete triennial inventory is required to be submitted to the EPA under 40 CFR 51 subpart A.
                    6
                    
                     States may use an alternative baseline emissions inventory provided that the year selected corresponds with the year of the effective date of designation as nonattainment for that NAAQS. Ozone season day emissions are defined in 40 CFR 51.1300(q) as the average day's emissions for a typical ozone season work weekday. Under the definition in 40 CFR 51.1300(q), states are required to select the months in the ozone season and the days in the work week to be represented. Per EPA's 2017 guidance on emissions inventory development, the selected ozone season should be representative of the conditions leading to nonattainment.
                    7
                    
                
                
                    
                        5
                         40 CFR 51.1315(a).
                    
                
                
                    
                        6
                         83 FR 62998, 63034.
                    
                
                
                    
                        7
                         EPA, Emissions Inventory Guidance for Implementation of Ozone and Particulate Matter National Ambient Air Quality Standards (NAAQS) and Regional Haze Regulations (May 2017), 75.
                    
                
                B. State Submittals
                On July 8, 2020, the Arizona Department of Environmental Quality (ADEQ) submitted a revision to the Arizona SIP titled Maricopa Association of Governments (MAG) 2020 Eight-Hour Ozone Plan (2020 Phoenix-Mesa SIP Submittal). The 2020 Phoenix-Mesa SIP Submittal includes a 2017 baseline emissions inventory for Phoenix-Mesa developed by the Maricopa Association of Governments (MAG) and supporting documentation regarding the development of the baseline emissions inventory.
                
                    On July 29, 2020, ADEQ submitted a revision to the Arizona SIP titled Marginal Ozone Plan for the Yuma Nonattainment Area, including a 2017 baseline emissions inventory for Yuma and supporting documentation regarding the development of the emissions inventory. The July 29, 2020 submittal did not include final amendments to the emissions statement rule in Arizona Administrative Code R182327 and did not adequately satisfy the public notice requirements under 40 CFR 51.102. On December 22, 2020, ADEQ withdrew the July 29, 2020 submittal and submitted as a revision to the Arizona SIP another plan, also titled Marginal Ozone Plan for the Yuma Nonattainment Area. On July 1, 2021, Arizona provided a technical supplement to the Marginal Ozone Plan for the Yuma Nonattainment Area addressing comments and questions raised by the EPA following receipt of ADEQ's prior submittals.
                    8
                    
                     Arizona's December 22, 2020 submittal and the July 1, 2021 supplement are collectively referred to herein as the 2020 Yuma SIP Submittal. Where specifically 
                    
                    referring to information provided in Arizona's supplement to the 2020 Yuma SIP Submittal, we refer to the July 1, 2021 supplement as the 2021 Yuma SIP Supplement.
                
                
                    
                        8
                         Letter dated June 30, 2021, from Joseph Martini, Manager, Air Quality Improvement Planning Section, Air Quality Division, Arizona Department of Environmental Quality, to Ben Leers, Air Planning Office, Air Division, EPA Region IX. Transmitted via email dated July 1, 2021, from Farah Esmaeili, Environmental Senior Engineer, Technical Analysis Unit, Air Quality Division, Arizona Department of Environmental Quality to Ben Leers.
                    
                
                In this action, we are evaluating and proposing action on the 2020 Phoenix-Mesa SIP Submittal and the 2020 Yuma SIP Submittal.
                C. Public Notice and Hearing Requirements
                CAA sections 110(a)(1) and 110(l) and 40 CFR 51.102 require states to provide reasonable notice and an opportunity for a public hearing prior to adoption of SIP revisions. Section 110(k)(1)(B) requires the EPA to determine whether a SIP submittal is complete within 60 days of receipt. Any plan that the EPA does not affirmatively determine to be complete or incomplete will become complete six months after the day of submittal by operation of law. A finding of completeness does not approve the submittal as part of the SIP, nor does it indicate that the submittal is approvable. It does start a 12-month clock for the EPA to act on the SIP submittal (see CAA section 110(k)(2)).
                The 2020 Phoenix-Mesa SIP Submittal and 2020 Yuma SIP Submittal each document the public review process followed prior to their submittal to the EPA as revisions to the SIP.
                
                    Appendix B of the 2020 Phoenix-Mesa SIP Submittal includes documentation of notices of opportunity for public hearing and comment on the SIP submittal. The notices for opportunity for public hearing and comment on the SIP submittal were posted in 
                    The Arizona Republic,
                     sent by email to interested parties, and posted on MAG's website. Also included in Appendix B of the 2020 Phoenix-Mesa SIP Submittal is a responsiveness summary indicating that no comments or requests for public hearing were received during the 30-day public review period.
                
                
                    Appendix B of the 2020 Yuma SIP Submittal includes documentation of a notice of public comment period and hearing on the SIP submittal posted in 
                    The Arizona Republic
                     on October 9, 2020, and October 10, 2020. Appendix B of the 2020 Yuma SIP Submittal also contains documentation of the November 12, 2020 public hearing on the SIP submittal including a sign-in sheet, transcript, signed certification that the public hearing was held, and a compilation of comments received and ADEQ's responses to comments.
                
                II. Arizona's Emissions Inventories
                
                    The 2020 Phoenix-Mesa SIP Submittal and 2020 Yuma SIP Submittal each address the emissions inventory requirement in CAA section 182(a)(1). Each submittal provides documentation of a 2017 base year inventory of emissions of NO
                    X
                     and VOC. The 2017 base year emissions inventory was the most recent triennial emissions inventory in the National Emissions Inventory (NEI) at the time the emissions inventories were prepared for the Phoenix-Mesa and Yuma areas.
                
                
                    Each emissions inventory submittal includes emissions estimates for the following source categories: Point sources, nonpoint sources, nonroad mobile sources, onroad mobile sources, and biogenic sources. Point sources are generally large, stationary (
                    i.e.,
                     non-mobile) sources of air pollutants. MAG's and ADEQ's specific interpretations of the point source definition are described in sections II.A and II.B of this notice, respectively. Nonpoint sources, also referred to as area sources, are the sources of air pollutants that are typically too small or too numerous to be categorized as point or mobile sources, such as residential combustion or consumer products. Nonroad mobile sources, also referred to as off-highway mobile sources, include nonroad engines and nonroad vehicles. Onroad mobile sources, also referred to as highway mobile sources, are motor vehicles traveling on local highways and roads. Biogenic sources emit pollutants produced by natural sources including vegetation and soils.
                
                
                    ADEQ and MAG each used a combination of top-down estimation techniques (
                    i.e.,
                     allocation of regional emissions estimates to a smaller, defined geographic area) and bottom-up estimation techniques (
                    i.e.,
                     development of source or source category emissions estimates using emissions factors, models, etc.) to develop the emissions inventories in their respective SIP submittals. Specific estimation techniques for each source category are described in sections II.A and II.B of this notice.
                
                A. Baseline Emissions Inventory for the Phoenix-Mesa Nonattainment Area
                
                    The emissions inventory included in the 2020 Phoenix-Mesa SIP Submittal was developed by MAG. The Phoenix-Mesa area includes Maricopa County and portions of Gila and Pinal Counties.
                    9
                    
                     MAG selected the months of June through August to estimate ozone season day emissions of NO
                    X
                     and VOC from sources in the Phoenix-Mesa area.
                    10
                    
                
                
                    
                        9
                         See 83 FR 25776, 2578425785, for a detailed description of the boundaries of the Phoenix-Mesa nonattainment area for the 2015 ozone NAAQS.
                    
                
                
                    
                        10
                         A detailed justification for MAG's selection of months in the ozone season is provided in Appendix F of the 2020 Phoenix-Mesa SIP Submittal.
                    
                
                
                    In the 2020 Phoenix-Mesa SIP Submittal, MAG defines point sources consistent with the point source definition put forth in EPA's air emissions reporting requirements (AERR).
                    11
                    
                     MAG identified 19 stationary sources meeting the point source definition in the Phoenix-Mesa area. As noted in the 2020 Phoenix-Mesa SIP Submittal, while some stationary sources in Maricopa County are permitted by ADEQ, no ADEQ-permitted facilities meet the point source definition, and such sources are instead categorized as area sources. All point sources in the Phoenix-Mesa area are located in Maricopa County and are permitted by the Maricopa County Air Quality District (MCAQD). MAG identified point sources in the Phoenix-Mesa area via the MCAQD electronic permit system database. MAG calculated emissions from point sources using annual source emissions reports, MCAQD investigation reports, permit files and logs, or telephone contacts with sources. Point source emissions calculations in the Phoenix-Mesa area also considered rule effectiveness, a factor that may be applied to emissions inventory estimates to account for regulatory programs which may be less than 100 percent effective.
                
                
                    
                        11
                         Under the AERR, a point source is a facility that is a major source under 40 CFR part 70 for one or more of the pollutants for which reporting is required by CAA section 51.15(a)(1), but not with regard to emissions of hazardous air pollutants. 80 FR 8787 (February 19, 2015). For major source emissions thresholds by pollutant, see 40 CFR 51.30.
                    
                
                
                    In the point source category, MAG also accounted for actual and potential voluntary emissions reductions at point sources in the Phoenix-Mesa area. Major new sources and major modifications in the Phoenix-Mesa area must offset the emissions of NO
                    X
                     and VOC generated by the new source or modification as a condition for approval of permit applications. These emissions offsets are generally obtained from existing sources located in the vicinity of the proposed source or modification in the form of emissions reduction credits (ERCs). The rules governing the generation and use of ERCs in the Phoenix-Mesa area area are outlined in MCAQD Rule 240. In the 2017 base year inventory, MAG included certified ERCs available in the Arizona Emissions Bank in the point source category totals. MAG also included potential (
                    i.e.,
                     not yet certified) sources of ERCs for NO
                    X
                     and VOC in the 
                    
                    base year inventory in order to maintain the availability of these emissions in the periodic inventory, provided that sufficient documentation can be secured to confirm the emissions reductions in the future.
                
                MAG estimated county-level emissions from nonpoint sources using a variety of tools, techniques, and assumptions depending on each nonpoint source subcategory. MAG's nonpoint source emissions estimates were informed by EPA's 2017 nonpoint emissions methodology and operator instructions, source-submitted annual emissions reports, and scaling up via the use of per-employee emissions factors. For each nonpoint source subcategory, county-level emissions estimates were allocated to the Phoenix-Mesa area using one of five representative variables: Employment, population, land use, general aviation operations, and location data. Each nonpoint source emissions calculation and allocation method is described in detail in the 2020 Phoenix-Mesa SIP Submittal.
                
                    Nonroad mobile source subcategories in the Phoenix-Mesa emissions inventory include agricultural equipment (
                    e.g.,
                     tractors, combines, and balers), recreational equipment (
                    e.g.,
                     all-terrain vehicles and off-road motorcycles), aircraft, and locomotives, among others. For most nonroad mobile source subcategories, MAG estimated emissions using the latest available version of EPA's Motor Vehicle Emission Simulator (MOVES2014b). Inputs to MOVES2014b included default model input files, National Oceanic and Atmospheric Administration (NOAA) National Centers for Environmental Information (NCEI) local climatological data, 2017 fuel specifications and vapor recovery program effectiveness from the Arizona Department of Agriculture Weights & Measures Services Division, and local data from a 2003 survey performed for ADEQ by ENVIRON. For aircraft and airport equipment, MAG estimated emissions using the Federal Aviation Administration (FAA) Aviation Environmental Design Tool version 2d (AEDT 2d). Inputs to AEDT 2d included local aircraft activity data from the FAA Operations Network, 
                    AirNav.com
                    , and base personnel at Luke Air Force Base. Additionally, MAG utilized aircraft fleet mix profiles from the FAA Traffic Flow Management System Counts database, verification of AirNav.com data using the FAA 5010 Airport Master Records database, and general aviation airport survey data conducted by MAG in 2017. Emissions from locomotives were estimated using survey data from the three railroad companies operating in Maricopa County (
                    i.e.,
                     Burlington Northern Santa Fe, Union Pacific, and Amtrak) and emissions factors published by ENVIRON and the EPA.
                
                Emissions from onroad mobile sources in the Phoenix-Mesa area were calculated using MOVES2014b. For onroad mobile sources, MOVES2014b requires local data inputs relating to vehicle inspection and maintenance programs, meteorological data, vehicle populations, source type age distributions, annual vehicle miles traveled, and alternative vehicle and fuel technologies, among others. MAG cited numerous sources and assumptions for local data inputs, including vehicle registration data from the Arizona Department of Transportation, meteorological data from the NOAA NCEI, and the MAG Transportation Modeling Group.
                Emissions from biogenic sources in the Phoenix-Mesa area were calculated using the Model of Emissions of Gases and Aerosols from Nature (MEGAN) version 2.1. MEGAN requires inputs of land cover and meteorological data. MAG utilized 1-kilometer eight-day average leaf area index from the National Aeronautics and Space Administration's Moderate Resolution Imaging Spectroradiometer satellite observations, plant functional type (PFT) data from the National Land Cover Dataset, and emission factors derived from PFT distributions. MAG processed meteorological data from the Weather Research and Forecasting model version 3.9 with the Meteorology-Chemistry Interface Processor (MCIP). The model outputs from MCIP were further processed using the MEGAN component program called MET2MGN for input to MEGAN.
                MAG employed quality assurance and quality control (QA/QC) measures throughout the development of the Phoenix-Mesa emissions inventory. Point source emissions reports undergo automated QA/QC upon submission to MCAQD's database as well as manual QA/QC performed by air quality planning staff. Area source emissions calculations are peer-reviewed by air quality planners to ensure calculations can be reproduced. Other QA/QC procedures performed by MAG include review of files by personnel not involved in the development of the inventory as well as comparison of the 2017 inventory to 2014 and 2011 inventories. MAG's QA/QC procedures are described in detail in the 2020 Phoenix-Mesa SIP submittal.
                
                    Estimates of 2017 ozone season day emissions of NO
                    X
                     and VOC in the Phoenix-Mesa area are summarized in Table 1 below.
                
                
                    Table 12017 Ozone Season Day Emissions
                    Phoenix-Mesa Ozone Nonattainment Area
                    
                        Pollutant
                        
                            Ozone season day emissions
                            (pounds per day)
                        
                        Point
                        Nonpoint
                        
                            Nonroad
                            mobile
                        
                        
                            Onroad
                            mobile
                        
                        Biogenic
                        Area total
                    
                    
                        
                            NO
                            X
                        
                        24,277
                        32,880
                        112,100
                        140,154
                        5,896
                        315,307
                    
                    
                        VOC
                        8,625
                        209,885
                        63,661
                        112,746
                        1,283,539
                        1,678,457
                    
                    
                        Source:
                         2020 Phoenix-Mesa SIP Submittal, Appendix A, 11.
                    
                
                B. Baseline Emissions Inventory for the Yuma Nonattainment Area
                
                    The emissions inventory included in the 2020 Yuma SIP Submittal was developed by ADEQ. The Yuma area consists of approximately 52 square miles within Yuma County in and around the city of Yuma, Arizona.
                    12
                    
                     ADEQ selected the months of April through October to estimate ozone season day emissions of NO
                    X
                     and VOC from sources in the Yuma area.
                    13
                    
                
                
                    
                        12
                         See 83 FR 25776, 25785 for a detailed description of the boundaries of the Yuma nonattainment area for the 2015 ozone NAAQS.
                    
                
                
                    
                        13
                         ADEQ's selection of the months in the ozone season is consistent with documentation provided by ADEQ along with its initial nonattainment boundary recommendations for the 2015 ozone NAAQS. See the technical support document 
                        
                        Phoenix-Mesa and Yuma Nonattainment Areas; Intended Area Designations for the 2015 Ozone National Ambient Air Quality Standards, included in the docket for EPA's initial designations for the 2015 ozone NAAQS under docket ID EPAHQOAR20170548.
                    
                
                
                ADEQ obtained emissions estimates for point sources in the Yuma area from the 2017 NEI and from source-submitted annual emissions inventory reports required for all sources holding a minor permit in Arizona. All point sources listed in the 2017 NEI and geographically located in the Yuma ozone nonattainment area were included in the point source category in the 2020 Yuma SIP Submittal. ADEQ also included minor point sources holding permits in the Yuma ozone nonattainment area in the point source category.
                Emissions from Yuma area nonpoint sources (also referred to as area sources in the 2020 Yuma SIP Submittal) were estimated predominantly using data from the 2017 NEI. The 2017 NEI includes emissions estimates for numerous area source subcategories on the county level. For most nonpoint source subcategories, ADEQ allocated county-level emissions estimates from the 2017 NEI to the Yuma area based on population, industrial employment, land area, crop land area, or railroad length. Emissions calculation methods used for the remaining nonpoint source subcategories include per-person emissions factors included in 2017 NEI documentation, information from permits, and information from source-submitted annual reports.
                ADEQ estimated emissions from nonroad mobile sources in the Yuma area by allocating emissions from 2017 NEI data using representative factors including population, cropland area, and railroad length. Nonroad mobile source categories addressed in the 2020 Yuma SIP submittal include: Agricultural equipment; commercial equipment; construction and mining equipment; industrial equipment; lawn and garden equipment; logging equipment; recreational equipment; pleasure craft; and locomotives. Of the eight private and public airports identified by ADEQ in Yuma County, none are located within the Yuma ozone nonattainment area. Therefore, ADEQ assumed zero nonroad mobile source emissions from airports.
                
                    Emissions from onroad mobile sources in the Yuma area were calculated using MOVES2014b. In the 2020 Yuma SIP Submittal, ADEQ listed MOVES2014b inputs for source type, road type, fuel type, and process type. ADEQ notes in the 2020 Yuma SIP Submittal that the Yuma area is located adjacent to a major trucking and travel corridor, and freight haulers and tractor trailers are primary producers of VOC and NO
                    X
                     emissions in the Yuma area.
                
                ADEQ estimated emissions from biogenic sources in the Yuma area using biogenic emissions data from the 2017 NEI. County-level biogenic emissions from the 2017 NEI were allocated to the Yuma area using the ratio of land area in the Yuma ozone nonattainment area to the land area within Yuma County. As described in the 2020 Yuma SIP Submittal, ozone season day biogenic emissions were estimated by summing the biogenic emissions in the Yuma area for each month in the ozone season (April through October) and dividing by the number of days in the ozone season (213 days).
                
                    ADEQ engaged numerous QA/QC procedures in the development of the 2020 Yuma SIP Submittal. ADEQ prepared an inventory preparation plan (IPP) and incorporated feedback from the EPA on the IPP to identify and follow suitable estimation methodologies. Procedures outlined in ADEQ's EPA-reviewed quality assurance project plan were followed to conduct QA/QC on emissions estimates submitted by sources.
                    14
                    
                     In general, ADEQ conducted peer and management review of the technical support document to the 2020 Yuma SIP Submittal and underlying calculations. A detailed description of ADEQ's QA/QC procedures is included in the 2020 Yuma SIP Submittal.
                
                
                    
                        14
                         ADEQ's Annual Permitted Source Emissions Inventories Quality Assurance Project Plan (October 2020) is included in the docket for this rulemaking.
                    
                
                The 2021 Yuma SIP Supplement provides clarification on emissions inventory details including selection of ozone season months, handling of seasonal emissions distribution, consideration of weekday emissions schedules, and ADEQ's QA/QC process. Based on input from the EPA regarding the consideration of weekday emissions schedules and of the ozone season in the Yuma nonattainment area, ADEQ made corrections to some of its ozone season day emissions estimates compared to the values provided in the original 2020 Yuma SIP Suibmittal. All changes to estimations of ozone season day emissions are described in detail in the 2021 Yuma SIP Supplement.
                
                    Estimates of 2017 ozone season day emissions of NO
                    X
                     and VOC in the Yuma area are summarized in Table 2 below.
                
                
                    Table 22017 Ozone Season Day Emissions
                    Yuma Ozone Nonattainment Area
                    
                        Pollutant
                        
                            Ozone season day emissions
                            (pounds per day)
                        
                        Point
                        Nonpoint
                        
                            Nonroad
                            mobile
                        
                        Onroad mobile
                        Biogenic
                        Area total
                    
                    
                        
                            NO
                            X
                        
                        1,113
                        1,275
                        2,158
                        10,402
                        38
                        14,986
                    
                    
                        VOC
                        138
                        15,007
                        2,737
                        5,527
                        2,849
                        26,259
                    
                    
                        Source:
                         2021 Yuma SIP Supplement, 6.
                    
                
                III. EPA's Evaluation
                Based on the documentation included in Arizona's submittals, the EPA finds that the submittals satisfy the procedural requirements of sections 110(a)(1) and 110(l) of the Act requiring states to provide reasonable notice and an opportunity for public hearing prior to adoption of SIP revisions. The 2020 Phoenix-Mesa SIP Submittal became complete by operation of law on January 8, 2021, and the 2020 Yuma SIP Submittal became complete by operation of law on June 22, 2021, pursuant to section 110(k)(1)(B).
                
                    The EPA has reviewed Arizona's submittals for consistency with CAA sections 172(c)(3) and 182(a)(1) and the requirements for emissions inventories under the EPA's implementing regulations for the 2015 ozone NAAQS at 40 CFR 51.1315. The 2017 baseline emissions inventories represent the 
                    
                    most recent calendar year for which a consistent and comprehensive statewide inventory was available. The selection of a 2017 baseline year for the Phoenix-Mesa and Yuma emissions inventories is therefore consistent with the requirement for selection of RFP baseline years under 40 CFR 51.1310(b). We find that the Phoenix-Mesa and Yuma emissions inventories appropriately estimated the average day's emissions for a typical weekday in the ozone season, consistent with the definition of ozone season day emissions under 40 CFR 51.1300(q).
                
                Arizona's submittals document the procedures used by MAG and ADEQ to estimate ozone season day emissions for each of the major source types. Documentation of emissions estimation procedures in the 2020 Phoenix-Mesa SIP Submittal and 2020 Yuma SIP Submittal demonstrate that MAG and ADEQ followed acceptable procedures to develop emissions estimates. The 2020 Phoenix-Mesa SIP Submittal and 2020 Yuma SIP Submittal each also describe the specific QA/QC measures implemented to ensure the accuracy and integrity of data throughout the development of each respective emissions inventory.
                
                    Based upon the documentation of emissions estimation techniques and QA/QC procedures employed to develop the emissions inventories in each submittal, we find that the 2020 Phoenix-Mesa SIP Submittal and 2020 Yuma SIP Submittal contain comprehensive, accurate, current inventories of actual emissions from all sources in the Phoenix-Mesa and Yuma ozone nonattainment areas, respectively. The EPA thereby proposes to approve the baseline inventories of NO
                    X
                     and VOC emissions for the Phoenix-Mesa and Yuma ozone nonattainment areas for the 2015 ozone NAAQS submitted by Arizona pursuant to 40 CFR 51.1315 and CAA sections 172(c)(3) and 182(b)(1) .
                
                IV. Proposed Action and Request for Public Comment
                We are proposing to approve the 2020 Phoenix-Mesa SIP Submittal and 2020 Yuma SIP Submittal as meeting the ozone-related baseline emissions inventory requirement for the Phoenix-Mesa and Yuma ozone nonattainment areas for the 2015 ozone NAAQS. The emissions inventories we are proposing to approve into the SIP are summarized in tables 1 and 2 of this notice. We are proposing to approve the emissions inventories because they contain comprehensive, accurate, and current inventories of actual emissions for all relevant sources in accordance with CAA sections 172(c)(3) and 182(a). The EPA is soliciting public comments on the issues discussed in this proposed rule. We will accept comments from the public on this proposal for the next 30 days.
                V. Statutory and Executive Order Reviews
                Under the Clean Air Act, the Administrator is required to approve a SIP submission that complies with the provisions of the Act and applicable federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in reviewing SIP submissions, the EPA's role is to approve state choices, provided that they meet the criteria of the Clean Air Act. Accordingly, this proposed action merely proposes to approve state plans as meeting federal requirements and does not impose additional requirements beyond those imposed by state law. For that reason, this proposed action:
                 Is not a significant regulatory action subject to review by the Office of Management and Budget under Executive Orders 12866 (58 FR 51735, October 4, 1993) and 13563 (76 FR 3821, January 21, 2011);
                
                     Does not impose an information collection burden under the provisions of the Paperwork Reduction Act (44 U.S.C. 3501 
                    et seq.
                    );
                
                
                     Is certified as not having a significant economic impact on a substantial number of small entities under the Regulatory Flexibility Act (5 U.S.C. 601 
                    et seq.
                    );
                
                 Does not contain any unfunded mandate or significantly or uniquely affect small governments, as described in the Unfunded Mandates Reform Act of 1995 (Pub. L. 1044);
                 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 Clean Air Act; 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. The Fort McDowell Yavapai Nation, the Gila River Indian Community of the Gila River Indian Reservation, the Tohono O'odham Nation of Arizona, and the Salt River Pima Maricopa Indian Community of the Salt River Reservation have areas of Indian country located within the Phoenix-Mesa nonattainment area for the 2015 ozone NAAQS. The Cocopah Tribe of Arizona and the Quechan Tribe of the Fort Yuma Indian Reservation have areas of Indian country located within the Yuma nonattainment area for the 2015 ozone NAAQS. In those areas of Indian country, the proposed rule does not have tribal implications and will not impose substantial direct costs on tribal governments or preempt tribal law as specified by Executive Order 13175 (65 FR 67249, November 9, 2000).
                
                    List of Subjects in 40 CFR Part 52
                    Environmental protection, Air pollution control, Incorporation by reference, Intergovernmental relations, Ozone, Reporting and recordkeeping requirements, Volatile organic compounds.
                
                
                    Authority:
                    
                        42 U.S.C. 7401 
                        et seq.
                    
                
                
                    Dated: October 9, 2021.
                    Deborah Jordan,
                    Acting Regional Administrator, Region IX.
                
            
            [FR Doc. 202122662 Filed 102121; 8:45 am]
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