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 Environmental Protection Agency 40 CFR Part 52
[EPA-R09-OAR-2022-0131; FRL-9739-01-R9]
 AGENCY: Environmental Protection Agency (EPA).
 ACTION: Proposed rule.
 SUMMARY: The Environmental Protection Agency (EPA) is proposing to approve, under the Clean Air Act (CAA or “Act”), revisions to the Nevada State Implementation Plan (SIP) concerning the base year emissions inventory requirements for the Las Vegas Valley ozone nonattainment area located within Clark County for the 2015 ozone national ambient air quality standards (NAAQS or “standards”).
 DATES: Any comments must arrive by July 13, 2022.
 ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R09-OAR-2022-0131 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: Lindsay Wickersham, Air Planning Office (AIR-2), EPA Region IX, (415) 947-4192, 
                        *Wickersham.Lindsay@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. Clark County's Emissions Inventory A. Base Year Emissions Inventory for the Las Vegas Valley 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.[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. In February 2018, Clark County submitted a recommendation based on 2015-2017 monitoring data, requesting that the Las Vegas Valley be designated nonattainment for the 2015 ozone NAAQS.[2]
                    
                     The EPA approved the request and designated the Las Vegas Valley in Clark County as a “Marginal” ozone nonattainment zone for the 2015 ozone NAAQS effective August 3, 2018.[3] 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.[4]
                    
                     The SRR established implementation requirements for the 2015 ozone NAAQS, including requirements for base year emissions inventories under CAA section 182(a)(1). 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. 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 (NOX), 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 NOX
                    . 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. NOX
                     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 the following: establishing baseline emissions levels, calculating emissions reduction targets needed to attain the NAAQS and to achieve reasonable further progress (RFP) toward attainment of an ozone standard,[5]
                    
                     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. 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 
                    ( print page 35706)
                    baseline year for RFP plans as required by 40 CFR 51.1310(b).[6]
                    
                     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.[7]
                    
                     States may use an alternative base year 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. Based on the EPA's 2017 guidance on emissions inventory development, the selected ozone season should be representative of the conditions leading to nonattainment.[8] B. State Submittals On October 15, 2020, the Nevada Department of Environmental Protection (NDEP) submitted a revision to the Nevada SIP titled, “Revision to the Nevada State Implementation Plan for the 2015 Ozone NAAQS: Emissions Inventory and Emissions Statement Requirements” (“2020 Clark County EI”).[9]
                    
                     The 2020 Clark County EI includes a 2017 base year emissions inventory for the Las Vegas Valley nonattainment area, developed by the Clark County Department of Environment and Sustainability (CCDES), and supporting documentation regarding the development of the base year emissions inventory. CCDES provided supplementary information (SI) to the 2020 Clark County EI addressing comments and questions raised by the EPA following receipt of CCDES's prior submittal on February 10, 2022, February 14, 2022, and on March 30, 2022.[10]
                    
                     Together these three supplementary exchanges are known as the “2020 Clark County SI.” In this action, we are evaluating and proposing action on the 2020 Clark County EI and the 2020 Clark County SI that we will collectively refer to as the “2020 Clark County SIP Submittal.” C. Public Notice and Hearing Requirements Sections 110(a)(1) and 110(l) of the CAA 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 by operation of law six months after the date of submittal. 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 Clark County SIP Submittal includes documentation of the public review process CCDES followed prior to its submittal to the EPA as revisions to the SIP. Appendix B of the 2020 Clark County EI includes documentation of notices of opportunity for public hearing and comment on the SIP submittal. CCDES posted these notices on CCDES Facebook and Twitter pages, sent them by email to interested parties, and posted them on CCDES and Clark County websites. Included in Appendix B of the 2020 Clark County EI are agendas and meeting summaries from two Board of Commissioners meetings, setting and conducting the public hearing. Public comment reports included in Appendix B indicate that CCDES received no comments during the 30-day public review period. II. Clark County's Emissions Inventory The 2020 Clark County SIP Submittal addresses the emissions inventory requirement in CAA section 182(a)(1). The submittal provides documentation of a 2017 base year inventory of emissions of NOX
                     and VOCs. 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 Clark County area. The emissions inventory submittal includes emissions estimates for the following source categories: point sources, nonpoint sources, onroad mobile sources, nonroad mobile sources, commercial and federal aviation, and biogenic sources. Point sources are large, stationary (
                    *i.e.,*
                     non-mobile) sources of emissions that release pollutants. Nonpoint sources, also referred to as “area” sources, are the sources of air pollutants that fall below point source reporting levels or are too small or too numerous to be identified individually, such as small-scale industrial or residential operations that use emission-generating materials or processes. Nonroad mobile sources are not certified for highway use and include equipment that can either move under their own power or can be moved from site to site.[11]
                    
                     Onroad mobile sources are motor vehicles traveling on local highways and roads. Biogenic sources emit pollutants produced by natural sources including vegetation and soils. Commercial and federal aviation consists of emissions from aircraft and airport ground support equipment for commercially run facilities and federally owned facilities respectively. CCDES employed 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 SIP submittal. A. Base Year Emissions Inventory for the Las Vegas Valley Nonattainment Area The emissions inventory included in the 2020 Clark County SIP Submittal was developed by CCDES. The Clark County ozone nonattainment area for the 2015 NAAQS consists of Hydrographic Area 212, also referred to by CCDES as the Las Vegas Valley.[12]
                    
                     CCDES selected the month of July to estimate ozone season day emissions of NOX
                     and VOC from sources in the Las Vegas Valley.[13] 
 
 In the 2020 Clark County SIP Submittal, the point source inventory includes all Title V stationary sources and all sources with the potential to emit at least 10 tons of VOCs or 25 tons of NOX
                     in 2017. All sources emitting less than these thresholds were included in the nonpoint source category. CCDES identified 110 stationary point sources meeting this point source definition in the Las Vegas Valley.[14] CCDES calculates actual emissions from point sources using data collected from annual source emissions reports, permit files and associated technical support documents (TSD), direct on-site measurements (
                    *e.g.,*
                     continuous emission monitors (CEMS)), or calculated using EPA emission factors (
                    *e.g.,*
                     AP-42) and activities data.[15] Nonpoint source emissions within the Las Vegas Valley were estimated using the 2017 NEI emissions estimates for Clark County. To generate the sub-county emissions from the Las Vegas Valley, the Sparse Matrix Operator Kernel Emissions (SMOKE) model was run with a 4-km grid spacing over the nonattainment area for July to generate ozone season weekday emissions estimates using annual nonpoint emissions data.[16]
                    
                     Ancillary files developed by the EPA for version 1 of the 2016 modeling platform were used when running SMOKE.[17]
                    
                     The nonpoint inventory includes different emissions sectors: locomotive, residential wood combustion, agriculture livestock, and other nonpoint sources.[18] Nonroad mobile sources in the Las Vegas Valley emissions inventory encompass a wide variety of equipment types that are not certified for highway use and can either move under their own power or can be moved from site to site.[19]
                    
                     CCDES estimated nonroad emissions within the Las Vegas Valley using the 2017 NEI emissions estimates for Clark County that were generated using the nonroad module of the EPA's Motor Vehicle Emission Simulator (version MOVES2014b), which was the latest model available at the time the inventory was developed.[20]
                    
                     To generate the sub-county emissions from the Las Vegas Valley, the SMOKE model was run with a 4-km grid spacing over the nonattainment area for July to generate ozone season weekday emissions estimates using monthly nonroad emissions data.[21]
                    
                     Ancillary data files used when running SMOKE were developed by the EPA for version 1 of the 2016 modeling platform and had a base year of 2016 for use in photochemical modeling.[22] Onroad mobile sources in the Las Vegas Valley emissions inventory consist of cars, trucks, buses, motorcycles, and other motor vehicles that travel on local and highway roads. CCDES developed a Clark County-specific MOVES input database for 2017 using the latest available information. Key inputs for MOVES included in this database were annual vehicle miles traveled (VMT), vehicle population by source type, fleet age distributions, fuel parameters, inspection and maintenance programs, hoteling activity, and ambient temperature and humidity data. Sources for these inputs include the 2018 Clark County vehicle classification study, the Nevada Department of Motor Vehicle registration database, the Nevada Department of Transportation's (NDOT) annual Highway Performance Monitoring System reports, data from the Regional Transportation Council, the online magazine 
                    *Schoolbusfleet,*
                     meteorological data collected at McCarran International Airport, the Coordinated Research Council's vehicle identification number decoding project and default model input files. To generate sub-county data from this database, CCDES assumed the population within the Las Vegas Valley to be 95 percent of the total population of Clark County [23]
                    
                     and used Las Vegas Valley specific annual VMT data for each vehicle source type as provided by NDOT. CCDES estimated emissions from onroad mobile sources using MOVES2014b in inventory mode to generate sub-county data for the Las Vegas Valley. Biogenic sources included in this inventory include crops, lawn grass, vegetation, soil, and forests. Emissions from biogenic sources in the Las Vegas Valley area were calculated using the Biogenic Emissions Inventory System Version 3.61 (BEIS 3.61) embedded in SMOKE 4.7. BEIS requires inputs of meteorological and landcover data. CCDES utilized 12-kilometer data collected from the 2016 version 1 Weather Research and Forecasting model, and the newly released Biogenic Emissions Landcover Database version 5 (BELD5).[24] Emissions from commercial aviation within the Las Vegas Valley encompasses three facilities: McCarran International Airport, North Las Vegas Airport, and Henderson Executive Airport. Emissions inventories were developed using the Federal Aviation Administration's Aviation Environmental Design Tool (AEDT) Version 3b. The Clark County Department of Aviation used default meteorology in AEDT with correction factors to account for differences in meteorology and activity data between the model's default design day of October and a typical July weekday. The 2020 Clark County SI shows corrected tons per day (tpd) values adjusted with correction factors for all three airports compared to the values provided in the 2020 Clark County EI. These corrected values are included in Table 2 below. Emissions from federally controlled aviation sources within Las Vegas Valley consist entirely of emissions from Nellis Air Force Base. Actual emissions from aircraft operations were obtained from EPA's 2017 NEI Data. CCDES employed quality assurance and quality control (QA/QC) measures 
                    ( print page 35708)
                    throughout the development of the 2020 Clark County emissions inventory. Point source emissions calculations were checked by CCDES compliance staff against the permitting Technical Support Document (TSD).[25]
                    
                     These reviewed and corrected emissions data are used in the emissions inventories. Nonroad and nonpoint emissions outcomes were compared to those from the NEI and other counties for reasonableness and consistency and were checked for spatial distributions with gridded emissions maps.[26]
                    
                     Onroad emissions had a variety of input sources and thus implemented multiple types of QA/QC practices outlined in the 2020 Clark County SI. Emissions data collected for the 2017 NEI was subject to QA/QC from the EPA and was compared by CCDES to other counties in Nevada and to other years for consistency and reasonableness.[27]
                    
                     CCDES's QA/QC measures are described in further detail in the 2020 Clark County SI. Estimates of 2017 ozone season day emissions of NOX
                     and VOC in the Las Vegas Valley are summarized in Table 2 below. Table 2—2017 Ozone Season Day Emissions for the Las Vegas Valley Nonattainment Area
Source category
PollutantNO
                            X
                              
                             (tpd)
VOC 
                             (tpd)Point
2.94
1.25Nonpoint
6.94
59.49Commercial Aviation
a
                             11.40
1.70Federal Aviation
0.50
0.24On-road Mobile
38.76
27.25Nonroad Mobile
36.58
23.96Biogenic
0.86
124.19Area Total
97.98
238.07Sources: 2020 Clark County EI section 9, 2020 Clark County SI.**Note:**a
                         Corrected value provided from 2020 Clark County SI, Section e.
 III. EPA's Evaluation Based on the documentation included in Clark County'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 Clark County SIP Submittal became complete by operation of law on April 15, 2021, pursuant to CAA section 110(k)(1)(B). The EPA has reviewed Clark County'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 base year emissions inventories represent the most recent calendar year for which a consistent and comprehensive statewide inventory was available. The selection of 2017 as the base year for the Las Vegas Valley emissions inventory is therefore consistent with the requirement for selection of RFP baseline years under 40 CFR 51.1310(b). We find that for the Las Vegas Valley emissions inventory Clark County 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). Clark County's submittals document the procedures used by CCDES to estimate ozone season day emissions for each of the major source types. Documentation of emissions estimation procedures in the 2020 Clark County SIP Submittal demonstrate that CCDES followed acceptable procedures to develop emissions estimates. The 2020 Clark County SIP Submittal also describes the specific QA/QC measures implemented to ensure the accuracy and integrity of data throughout the development of the emissions inventory. Based upon the documentation of emissions estimation techniques and QA/QC procedures employed to develop the emissions inventories in the submittal, we find that the 2020 Clark County SIP Submittal contains comprehensive, accurate, current inventories of actual emissions from all sources in the Las Vegas Valley nonattainment area. The EPA therefore proposes to approve the base year inventories of NOX
                     and VOC emissions for the Las Vegas Valley ozone nonattainment area for the 2015 ozone NAAQS submitted by Nevada 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 Clark County SIP Submittal as meeting the ozone-related base year emissions inventory requirement for the Las Vegas Valley nonattainment area for the 2015 ozone NAAQS. The emissions inventory we are proposing to approve into the SIP is summarized in Table 2. We are proposing to approve this emissions inventory because it contains comprehensive, accurate, and current inventories of actual emissions for all relevant sources in accordance with CAA sections 172(c)(3) and 182(a)(1). 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 
                    ( print page 35709)
                    as meeting federal requirements and does not impose additional requirements beyond those imposed by state law. For that reason, this proposed action: Is not a “significant regulatory action” subject to review by the Office of Management and Budget under Executive Orders 12866 (58 FR 51735, October 4, 1993) and 13563 (76 FR 3821, January 21, 2011);
                Does not impose an information collection burden under the provisions of the Paperwork Reduction Act (44 U.S.C. 3501 
                    *et seq.*);
                Is certified as not having a significant economic impact on a substantial number of small entities under the Regulatory Flexibility Act (5 U.S.C. 601 
                    *et seq.*);
                Does not contain any unfunded mandate or significantly or uniquely affect small governments, as described in the Unfunded Mandates Reform Act of 1995 (Pub. L. 104-4);
                Does not have federalism implications as specified inExecutive Order 13132 (64 FR 43255, August 10, 1999);
                Is not an economically significant regulatory action based on health or safety risks subject toExecutive Order 13045 (62 FR 19885, April 23, 1997);
                Is not a significant regulatory action subject toExecutive 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 underExecutive 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 Las Vegas Tribe of Paiute Indians of the Las Vegas Indian Colony have areas of Indian country located within the Las Vegas Valley 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: June 6, 2022. Martha Guzman Aceves, Regional Administrator, Region IX.


# Footnotes

1.
    
                         80 FR 65292. Back to Citation
 2.
    
                         Letter dated February 23, 2018, from Greg Lovato, Administrator, Nevada Division of Environmental Protection, to Alexis Strauss, Acting Regional Administrator, EPA Region IX. Back to Citation
 3.
    
                         83 FR 25776, 25819. Back to Citation
 4.
    
                         83 FR 62998. Back to Citation
 5.
    
                         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 Clark County base year emissions inventory SIPs for the 2015 ozone NAAQS, the Clark County area was designated Marginal nonattainment for the 2015 ozone NAAQS and were therefore not required to demonstrate RFP toward attainment of the 2015 ozone NAAQS. Back to Citation
 6.
    
                         40 CFR 51.1315(a). Back to Citation
 7.
    
                         83 FR 62998, 63034. Back to Citation
 8.
    
                         EPA, “Emissions Inventory Guidance for Implementation of Ozone and Particulate Matter National Ambient Air Quality Standards (NAAQS) and Regional Haze Regulations” (May 2017), 75. Back to Citation
 9.
    
                         Letter dated October 8, 2020, from Greg Lovato, Administrator, Nevada Division of Environmental Protection, to Elizabeth Adams, Director, Air Division, EPA Region IX. Transmitted via US EPA's State Planning Electronic Collaboration System (SPeCS) on October 15, 2020. Back to Citation
 10.
    
                         Email dated February 10, 2022, from Zheng Li, CCDES, to Lindsay Wickersham, EPA Region IX, Subject: “RE: Introduction and Qs on 2015 O3 EI.”; Email dated February 14, 2022, from Araceli Pruett, CCDES to Lindsay Wickersham, EPA Region IX, Subject: “RE: Introduction and Qs on 2015 O3 EI.,” with attachment, “20220203 EPA Request for Add'l Info on 2015 O3 EI.docx.”; Email Dated March 30, 2022, from Araceli Pruett, CCDES to Lindsay Wickersham, EPA Region IX, Subject: “RE: A few questions: ERCs, QA, etc.,” with attachment, “20220329 EPA Request for Add'l Info on 2015 O3 EI.docx.” Back to Citation
 11.
    
                         Locomotive emissions are included in the nonpoint category. Aircraft and airport ground support equipment are included in the aviation categories. Back to Citation
 12.
    
                         See 83 FR 25776, 25819 (June 4, 2018) (providing a description of the boundaries of the Clark County nonattainment area for the 2015 ozone NAAQS); see also Figure 1-1 in 2020 Clark County EI for a map of the nonattainment area. Back to Citation
 13.
    
                         In Clark County, the highest ambient ozone concentrations generally occur during the months 
                        
                        of the year when the highest temperatures occur—typically from May through September. For SIP planning purposes, CCDES selected weekdays in the month of July as the basis to estimate typical summertime weekday emissions, as is precedent for Clark County SIPs. See 86 FR 43461, 43464 (August 9, 2021). Back to Citation
 14.
    
                         All point sources identified in the Las Vegas Valley are permitted by the CCDES Division of Air Quality and required to submit annual emissions reports under Section 12.9 of the Clark County Air Quality Regulations (AQR). These annual emission reports were used to identify individual stationary point sources within the Las Vegas Valley for this emissions inventory. Back to Citation
 15.
    
                         On-site measurements are collected from emission units that are required to have CEMS, as outlined in Section 12.10 of the Clark County AQR. All other point sources emissions were calculated based on emissions factors in the permit and activity data. Back to Citation
 16.
    
                         For a map of the modeled area, see 2020 Clark County EI, Figure 1-1, A-4; Characterized by Source Classification Code (SCC) in the FF10 Flat data file; EPA, “Technical Support Document (TSD) Preparation of Emissions Inventories for the 2016v1 North American Emissions Modeling Platform” (March 2021), 123. Back to Citation
 17.
    
                         Files and technical support documents available at 
                        *https://www.epa.gov/​air-emissions-modeling/​2016v1-platform.* Back to Citation
 18.
    
                         See 2020 Clark County SI Section C for detailed emissions from each emission sector. Back to Citation
 19.
    
                         Locomotive, aircraft, and airport ground support equipment are not included in this category. Back to Citation
 20.
    
                         EPA, “Policy Guidance on the Use of MOVES3 for State Implementation Plan Development, Transportation Conformity, General Conformity, and Other Purposes” (November 2020), 7. Back to Citation
 21.
    
                         Characterized by Source Classification Code (SCC) in the FF10 Flat data file; EPA, “Technical Support Document (TSD) Preparation of Emissions Inventories for the 2016v1 North American Emissions Modeling Platform” (March 2021), 123. Back to Citation
 22.
    
                         Files and technical support documents available at 
                        *https://www.epa.gov/​air-emissions-modeling/​2016v1-platform.* Back to Citation
 23.
    
                         The EPA has previously accepted this assumption for other plans submitted regarding Las Vegas (see 
                        *e.g.,*79 FR 60078). The human population of the Las Vegas Valley is around 96.7 percent. Sensitivity analysis showed that the values in MOVES was not sensitive to a 1.67 percent change. Back to Citation
 24.
    
                         BELD5 includes version 8.0 of the Forest Inventory and Analysis, which has better agreement with measured foliage biomass to improve VOC emissions estimates. Back to Citation
 25.
    
                         CCDES, “Emissions Inventory Report Review and Audit Process” (March 2021). Back to Citation
 26.
    
                         Gridded emissions map shown in 2020 Clark County SI, Section (b)(iii) and Section (c)(iii). Back to Citation
 27.
    
                         EPA, “2017 National Emissions Inventory Summary of Quality Assurance Information” (January 2022). Back to Citation


[FR Doc. 2022-12609 Filed 6-10-22; 8:45 am] BILLING CODE 6560-50-P