# Clean Air Plans; 2006 Fine Particulate Matter Nonattainment Area Requirements; San Joaquin Valley, California > Briefs, arguments, decisions, and more. URL: https://www.frixlaw.com/law-library/documents/fr%3A2020-05914 ## Record - **Collection:** Federal Register - **Document type:** Proposed Rule - **Published:** March 27, 2020 - **Citation:** 85 FR 17382 ## Text ENVIRONMENTAL PROTECTION AGENCY 40 CFR Part 52 [EPA-R09-OAR-2019-0318; FRL-10006-40-Region 9] Clean Air Plans; 2006 Fine Particulate Matter Nonattainment Area Requirements; San Joaquin Valley, California AGENCY: Environmental Protection Agency (EPA). ACTION: Proposed rule. SUMMARY: The Environmental Protection Agency (EPA or “Agency”) proposes to approve portions of two state implementation plan (SIP) revisions submitted by the State of California to meet Clean Air Act (CAA or “Act”) requirements for the 2006 fine particulate matter (PM 2.5 ) national ambient air quality standards (NAAQS or “standards”) in the San Joaquin Valley (SJV) Serious nonattainment area. Specifically, the EPA proposes to approve those portions of the “2018 Plan for the 1997, 2006, and 2012 PM 2.5 Standards” and the “San Joaquin Valley Supplement to the 2016 State Strategy for the State Implementation Plan” that pertain to the 2006 PM 2.5 NAAQS and address CAA requirements for Serious PM 2.5 nonattainment areas. The EPA also proposes to approve inter-pollutant trading ratios for use in transportation conformity analyses for the 2006 PM 2.5 NAAQS. As part of this action, the EPA proposes to grant an extension of the Serious area attainment date for the 2006 PM 2.5 NAAQS in the San Joaquin Valley from December 31, 2019, to December 31, 2024 based on a proposed determination that the State has satisfied the statutory criteria for this extension. We may, however, reconsider this proposal or deny California's request for extension of the attainment date if, based on new information or public comments, we find that the State has not satisfied the statutory criteria for this extension. DATES: Any comments must arrive by April 27, 2020. ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R09-OAR-2019-0318, 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. FOR FURTHER INFORMATION CONTACT: Rory Mays, Air Planning Office (AIR-2), EPA Region IX, (415) 972-3227, mays.rory@epa.gov. SUPPLEMENTARY INFORMATION: Throughout this document, “we,” “us,” and “our” refer to the EPA. Table of Contents I. Background II. Summary and Completeness Review of the San Joaquin Valley PM 2.5 Plan A. 2018 PM 2.5 Plan B. Valley State SIP Strategy III. Clean Air Act Requirements for PM 2.5 Serious Area Plans A. Requirements for PM 2.5 Serious Area Plans B. Requirements for Extension of a Serious Area Attainment Date IV. Review of the San Joaquin Valley PM 2.5 Serious Area Plan and Extension Application A. Emissions Inventory B. PM 2.5 Precursors C. Best Available Control Measures and Most Stringent Measures D. Extension of Serious Area Attainment Date Under CAA Section 188(e) E. Reasonable Further Progress and Quantitative Milestones F. Motor Vehicle Emission Budgets G. Major Stationary Source Control Requirements Under CAA Section 189(e) V. Summary of Proposed Actions and Request for Public Comment VI. Statutory and Executive Order Reviews I. Background On October 17, 2006, the EPA strengthened the 24-hour (daily) NAAQS for particles less than or equal to 2.5 micrometers (µm) in diameter (PM 2.5 ) by lowering the level from 65 micrograms (µg) per cubic meter (m 3 ) to 35 µg/m 3 . 1 The 24-hour standards are based on a three-year average of 98th percentile 24-hour PM 2.5 concentrations. The EPA established these standards after considering substantial evidence from numerous health studies demonstrating that serious health effects are associated with exposures to PM 2.5 concentrations above these levels. 1 71 Federal Register (FR) 61144 (October 17, 2006) and 40 CFR 50.13. In promulgating the 2006 PM 2.5 NAAQS, the EPA retained the level of the 1997 annual average PM 2.5 NAAQS of 15.0 µg/m 3 . 62 FR 36852 (July 18, 1997) and 40 CFR 50.7. Subsequently, the EPA strengthened the primary annual PM 2.5 NAAQS by lowering the level to 12.0 µg/m 3 while retaining the secondary annual PM 2.5 NAAQS at the level of 15.0 µg/m 3 . 78 FR 3086 (January 15, 2013) and 40 CFR 50.18. In this preamble, all references to the PM 2.5 NAAQS, unless otherwise specified, are to the 2006 24-hour standards (35 µg/m 3 ) as codified in 40 CFR 50.13. Epidemiological studies have shown statistically significant correlations between elevated PM 2.5 levels and premature mortality. Other important health effects associated with PM 2.5 exposure include aggravation of respiratory and cardiovascular disease (as indicated by increased hospital admissions, emergency room visits, absences from school or work, and restricted activity days), changes in lung function and increased respiratory symptoms, and new evidence for more subtle indicators of cardiovascular health. Individuals particularly sensitive to PM 2.5 exposure include older adults, people with heart and lung disease, and children. 2 2 EPA, Air Quality Criteria for Particulate Matter, No. EPA/600/P-99/002aF and EPA/600/P-99/002bF, October 2004. PM 2.5 can be emitted directly into the atmosphere as a solid or liquid particle (primary PM 2.5 or direct PM 2.5 ) or can be formed in the atmosphere as a result of various chemical reactions from precursor emissions of nitrogen oxides, sulfur oxides, volatile organic compounds, and ammonia (secondary PM 2.5 ). 3 3 81 FR 58010, 58011 (August 24, 2016). Following promulgation of a new or revised NAAQS, the EPA is required under CAA section 107(d) to designate areas throughout the nation as attaining or not attaining the NAAQS. Effective December 14, 2009, the EPA finalized initial air quality designations for the 2006 PM 2.5 NAAQS, using air quality monitoring data for the three-year periods of 2005-2007 and 2006-2008. 4 The EPA designated the San Joaquin Valley as a nonattainment area for the 2006 PM 2.5 NAAQS. 5 On June 2, 2014, the EPA classified the San Joaquin Valley as a Moderate nonattainment area for these NAAQS, thereby establishing December 31, 2015 as the latest permissible attainment date for the area under section 188(c)(1) of the CAA. 6 Effective February 19, 2016, the EPA reclassified the San Joaquin Valley as a Serious nonattainment area for these NAAQS. 7 Shortly thereafter, the EPA approved the State's demonstration that it was impracticable to attain the 2006 PM 2.5 NAAQS by the December 31, 2015 Moderate area attainment date and related plan elements addressing the Moderate area requirements for the 2006 PM 2.5 NAAQS. 8 4 74 FR 58688 (November 13, 2009). 5 Id. (codified at 40 CFR 81.305). The most recent 24-hour design value (2016-2018) for the San Joaquin Valley is 65 µg/m 3 . EPA design value workbook dated July 18, 2019, worksheet “Table 1b.” 6 79 FR 31566 (June 2, 2014). The EPA promulgated these PM 2.5 nonattainment area classifications in response to a 2013 decision of the Court of Appeals for the D.C. Circuit remanding the EPA's prior implementation rule for the PM 2.5 NAAQS and directing the EPA to repromulgate implementation rules pursuant to subpart 4 of part D, title I of the Act. Natural Resources Defense Council v. EPA, 706 F.3d 428 (D.C. Cir. 2013). 7 81 FR 2993 (January 20, 2016). 8 81 FR 59876 (August 31, 2016). Upon reclassification as a Serious PM 2.5 nonattainment area, the San Joaquin Valley became subject to a new statutory attainment date no later than the end of the tenth calendar year following designation ( i.e., December 31, 2019) and the requirement to submit a Serious area plan satisfying the requirements of CAA Title I, part D, including the requirements of subpart 4, for the 2006 PM 2.5 NAAQS. 9 As explained in the EPA's final reclassification action, the Serious area plan for the San Joaquin Valley must include, among other things, provisions to assure that, under CAA section 189(b)(1)(B), the best available control measures (BACM) for the control of direct PM 2.5 and PM 2.5 precursors shall be implemented no later than four years after the area is reclassified and a demonstration (including air quality modeling) that the plan provides for attainment as expeditiously as practicable and no later than the applicable attainment date. The EPA established an August 21, 2017 deadline for California to adopt and submit a SIP submission addressing the Serious nonattainment area requirements for the 2006 PM 2.5 NAAQS. 10 The EPA also noted that California may choose to submit a request for an extension of the December 31, 2019, Serious area attainment date pursuant to CAA section 188(e) simultaneously with its submission of a Serious area plan for the area. 11 9 81 FR 2993, 2998. 10 Id. at 3000 and 81 FR 42263 (June 29, 2016) (codified at 40 CFR 52.247(f)). 11 81 FR 2993, 2998. As described further in section III.B of this preamble, CAA section 188(e) allows the EPA to extend the attainment date for a Serious area by up to five years if attainment by the Serious area attainment date is impracticable. However, before the Agency may grant an extension of the attainment date, the State must first: (1) Apply to the EPA for an extension of the PM 2.5 attainment date beyond 2019, (2) demonstrate that attainment by 2019 is impracticable, (3) have complied with all requirements and commitments applying to the area in its implementation plan, (4) demonstrate to the Administrator's satisfaction that its Serious area plan includes the most stringent measures that are achieved in practice in any state and are feasible for the area, and (5) submit SIP revisions containing a demonstration of attainment by the most expeditious alternative date practicable. The San Joaquin Valley PM 2.5 nonattainment area encompasses over 23,000 square miles and includes all or part of eight counties: San Joaquin, Stanislaus, Merced, Madera, Fresno, Tulare, Kings, and the valley portion of Kern. 12 The area is home to four million people and is the nation's leading agricultural region. Stretching over 250 miles from north to south and averaging 80 miles wide, it is partially enclosed by the Coast Mountain range to the west, the Tehachapi Mountains to the south, and the Sierra Nevada range to the east. The San Joaquin Valley Unified Air Pollution Control District (SJVUAPCD or District) has primary responsibility for developing plans to provide for attainment of the NAAQS in this area. The District works cooperatively with the California Air Resources Board (CARB) in preparing attainment plans. Authority for regulating sources under state jurisdiction in the San Joaquin Valley is split between the District, which has responsibility for regulating stationary and most area sources, and CARB, which has responsibility for regulating most mobile sources. 12 For a precise description of the geographic boundaries of the San Joaquin Valley PM 2.5 nonattainment area, see 40 CFR 81.305. On November 16, 2018, CARB submitted to the EPA substantial portions of the Serious area plan for the 2006 PM 2.5 NAAQS following CARB's adoption of one component of the plan on October 25, 2018 and the SJVUAPCD's adoption of a second component of it on November 15, 2018. 13 Because CARB had not yet adopted this submission in its entirety, the EPA determined that it did not meet the EPA's completeness requirements for SIP submissions under 40 CFR part 51, Appendix V, section 2.1. 14 The EPA's incompleteness findings became effective on January 7, 2019, and triggered clocks for the application of emissions offset sanctions for new or modified major stationary sources in the San Joaquin Valley 18 months after the effective date of the findings and highway funding sanctions six months thereafter, unless the EPA affirmatively determines that the State has submitted a complete SIP addressing the deficiency that was the basis for these findings, consistent with CAA section 179(b) and the EPA's sanctions sequencing rule in 40 CFR 52.31. 15 These findings also triggered the obligation under CAA section 110(c) on the EPA to promulgate a federal implementation plan no later than two years after the effective date of the findings, unless the State has submitted, and the EPA has approved, the required SIP submittal. 16 13 Letter dated November 16, 2018, from Kurt Karperos, Deputy Executive Officer, CARB, to Mike Stoker, Regional Administrator, EPA Region IX. 14 83 FR 62720 (December 6, 2018). The EPA made these findings in response to a court order issued in Committee for a Better Arvin, et al., v. Andrew Wheeler, et al., Case No. 18-cv-05700-RS (N.D. Cal., October 24, 2018). 15 83 FR 62720, 62723. 16 Id. II. Summary and Completeness Review of the San Joaquin Valley PM 2.5 Plan The EPA is proposing action on portions of two SIP revisions submitted by CARB to meet the Serious nonattainment area requirements for the 2006 24-hour PM 2.5 NAAQS in the San Joaquin Valley. Specifically, the EPA is proposing to act on those portions of the following two plan submissions that pertain to the 2006 24-hour PM 2.5 NAAQS: The “2018 Plan for the 1997, 2006, and 2012 PM 2.5 Standards,” adopted by the SJVUAPCD on November 15, 2018, and by CARB on January 24, 2019 (“2018 PM 2.5 Plan”) 17 ; and the “San Joaquin Valley Supplement to the 2016 State Strategy for the State Implementation Plan,” adopted by CARB on October 25, 2018 (“Valley State SIP Strategy”). We refer to the relevant portions of these SIP submissions collectively as the “SJV PM 2.5 Plan” or “Plan.” The SJV PM 2.5 Plan addresses the Serious area attainment plan requirements for the 2006 24-hour PM 2.5 NAAQS in the San Joaquin Valley and includes a request under CAA section 188(e) for an extension of the Serious area attainment date for the area for this NAAQS. CARB submitted the SJV PM 2.5 Plan to the EPA as a revision to the SIP on May 10, 2019. 18 17 The 2018 PM 2.5 Plan was developed jointly by CARB and the District. 18 Letter dated May 9, 2019, from Richard Corey, Executive Officer, CARB, to Mike Stoker, Regional Administrator, EPA Region 9. The EPA is not, at this time, proposing to act on those portions of the “2018 Plan for the 1997, 2006, and 2012 PM 2.5 Standards” or the “San Joaquin Valley Supplement to the 2016 State Strategy for the State Implementation Plan” that pertain to the 1997 PM 2.5 NAAQS, the 2012 PM 2.5 NAAQS, or Serious area contingency measures. We intend to act on these portions of the submitted SIP revisions in subsequent rulemakings. CAA sections 110(a)(1) and (2) and 110(l) require each state to provide reasonable public notice and opportunity for public hearing prior to the adoption and submission of a SIP or SIP revision to the EPA. To meet this requirement, every SIP submission should include evidence that adequate public notice was given and that an opportunity for a public hearing was provided consistent with the EPA's implementing regulations in 40 CFR 51.102. CAA section 110(k)(1)(B) requires the EPA to determine whether a SIP submission is complete within 60 days of receipt. This section also provides that any plan that the EPA has not affirmatively determined to be complete or incomplete will become complete by operation of law six months after the date of submission. The EPA's SIP completeness criteria are found in 40 CFR part 51, Appendix V. A. 2018 PM 2.5 Plan The following portions of the 2018 PM 2.5 Plan and related support documents address the Serious area requirements for the 2006 PM 2.5 NAAQS in the San Joaquin Valley: (i) Chapter 4 (“Attainment Strategy for PM 2.5 ”); (ii) Chapter 6 (“Demonstration of Federal Requirements for the 2006 PM 2.5 Standard: Serious Plan and Extension Request”); 19 (iii) numerous appendices to the 2018 PM 2.5 Plan; (iv) CARB's “Staff Report, Review of the San Joaquin Valley 2018 Plan for the 1997, 2006, and 2012 PM 2.5 Standards,” release date December 21, 2018 (“CARB Staff Report”); 20 and (v) the State's and District's board resolutions adopting the 2018 PM 2.5 Plan (CARB Resolution 19-1 and SJVUAPCD Governing Board Resolution 18-11-16). 21 The SJVUAPCD Governing Board Resolution 18-11-16 includes emission reduction commitments on which the SJV PM 2.5 Plan relies. 22 19 Chapter 5 (“Demonstration of Federal Requirements for the 1997 PM 2.5 Standard”) and Chapter 7 (“Demonstration of Federal Requirements for the 2012 PM 2.5 Standard”) of the 2018 PM 2.5 Plan pertain to the 1997 PM 2.5 NAAQS and 2012 PM 2.5 NAAQS, respectively. The EPA intends to act on these portions of the 2018 PM 2.5 Plan in separate rulemakings. 20 The CARB Staff Report includes CARB's review of, among other things, the 2018 PM 2.5 Plan's control strategy and attainment demonstration. Letter dated December 11, 2019 from Richard Corey, Executive Officer, CARB to Mike Stoker, Regional Administrator, EPA Region IX, transmitting the CARB Staff Report [on the 2018 PM 2.5 Plan]. 21 CARB Resolution 19-1, “2018 PM 2.5 State Implementation Plan for the San Joaquin Valley,” January 24, 2019, and SJVUAPCD Governing Board Resolution 18-11-16, “Adopting the [SJVUAPCD] 2018 Plan for the 1997, 2006, and 2012 PM 2.5 Standards,” November 15, 2018. 22 SJVUAPCD Governing Board Resolution 18-11-16, paragraph 6, 10-11. The appendices to the 2018 PM 2.5 Plan, in order of their evaluation in this preamble, include: (i) App. B (“Emissions Inventory”); (ii) App. A (“Ambient PM 2.5 Data Analysis”); (iii) a plan precursor demonstration and clarifications, including App. G (“Precursor Demonstration”) and Attachment A (“Clarifying information for the San Joaquin Valley 2018 Plan regarding model sensitivity related to ammonia and ammonia controls”) to the CARB Staff Report; (iv) control strategy appendices, including App. C (“Stationary Source Control Measure Analyses”), App. D (“Mobile Source Control Measures Analyses”), and App. E (“Incentive-Based Strategy”); (v) modeling appendices, including App. J (“Modeling Emission Inventory”), App. K (“Modeling Attainment Demonstration”), and App. L (“Modeling Protocol”); (vi) App. H (“RFP, Quantitative Milestones, and Contingency”); and (vii) App. I (“New Source Review and Emission Reduction Credits”). The 2018 PM 2.5 Plan addresses motor vehicle emission budget (MVEB) requirements in the “Transportation Conformity” section of App. D (pages D-119 to D-131). The 2018 PM 2.5 Plan also includes an Executive Summary, Introduction (Ch. 1), chapters on “Air Quality Challenges and Trends” (Ch. 2) and “Health Impacts and Health Risk Reduction Strategy” (Ch. 3), and an appendix on “Public Education and Technology Advancement” (App. F). The District provided public notice and opportunity for public comment prior to its November 15, 2018 public hearing on and adoption of the 2018 PM 2.5 Plan. 23 CARB also provided public notice and opportunity for public comment prior to its January 24, 2019 public hearing on and adoption of the 2018 PM 2.5 Plan. 24 The SIP submission includes proof of publication of notices for the respective public hearings. It also includes copies of the written and oral comments received during the State's and District's public review processes and the agencies' responses thereto. 25 Therefore, we find that the 2018 PM 2.5 Plan meets the procedural requirements for public notice and hearing in CAA sections 110(a) and 110(l) and 40 CFR 51.102. The 2018 PM 2.5 Plan became complete by operation of law on November 10, 2019. The sanctions clocks that were triggered by our December 6, 2018 findings that the State had failed to submit complete SIP submissions addressing the statutory requirements that apply to areas designated nonattainment for the PM 2.5 NAAQS, however, will continue to run until the EPA affirmatively determines, by letter to the Governor of California, that CARB has submitted a complete SIP submission addressing the identified deficiencies. 26 23 SJVUAPCD, “Notice of Public Hearing for Adoption of Proposed 2018 PM 2.5 Plan for the 1997, 2006, and 2012 Standards,” October 16, 2018, and SJVUAPCD Governing Board Resolution 18-11-16. 24 CARB, “Notice of Public Meeting to Consider the 2018 PM 2.5 State Implementation Plan for the San Joaquin Valley,” December 21, 2018, and CARB Resolution 19-1. 25 CARB, “Board Meeting Comments Log,” March 29, 2019; J&K Court Reporting, LLC, “Meeting, State of California Air Resources Board,” January 24, 2019 (transcript of CARB's public hearing), and 2018 PM 2.5 Plan, App. M (“Summary of Significant Comments and Responses”). 26 83 FR 62720 (citing required process for termination of sanctions clocks in 40 CFR 52.31(d)(5)). B. Valley State SIP Strategy CARB developed the “Revised Proposed 2016 State Strategy for the State Implementation Plan” (“2016 State Strategy”) to support attainment planning in the San Joaquin Valley and Los Angeles-South Coast Air Basin (“South Coast”) ozone nonattainment areas. 27 In its resolution adopting the 2016 State Strategy (CARB Resolution 17-7), the Board found that the 2016 State Strategy would achieve 6 tons per day (tpd) of NO X emission reductions and 0.1 tpd of direct PM 2.5 emission reductions in the San Joaquin Valley by 2025 and directed CARB staff to work with the SJVUAPCD to identify additional reductions from sources under District regulatory authority as part of a comprehensive plan to attain the PM 2.5 standards for the San Joaquin Valley and to return to the Board with a commitment to achieve additional emission reductions from mobile sources. 28 27 The EPA has approved certain commitments made by CARB in the 2016 State Strategy for purposes of attaining the ozone NAAQS in the San Joaquin Valley and South Coast ozone nonattainment areas. See, e.g., 84 FR 3302 (February 12, 2019) and 84 FR 52005 (October 1, 2019). 28 CARB Resolution 17-7, “2016 State Strategy for the State Implementation Plan,” March 23, 2017, 6-7. CARB responded to this resolution by developing and adopting the “San Joaquin Valley Supplement to the 2016 State Strategy for the State Implementation Plan” (“Valley State SIP Strategy”) to support the 2018 PM 2.5 Plan. The State's May 10, 2019 SIP submission incorporates by reference the Valley State SIP Strategy as adopted by CARB on October 25, 2018 and submitted to the EPA on November 16, 2018. 29 29 Letter dated May 9, 2019, from Richard Corey, Executive Officer, CARB, to Mike Stoker, Regional Administrator, EPA Region 9, 2. The Valley State SIP Strategy includes an Introduction (Ch. 1), a chapter on “Measures” (Ch. 2), and a “Supplemental State Commitment from the Proposed State Measures for the Valley” (Ch. 3). Much of the content of the Valley State SIP Strategy is reproduced in Chapter 4 (“Attainment Strategy for PM 2.5 ”) of the 2018 PM 2.5 Plan. 30 The Valley State SIP Strategy also includes CARB Resolution 18-49, which, among other things, commits CARB to achieve specific amounts of NO X and PM 2.5 emission reductions by specific years, for purposes of attaining the PM 2.5 NAAQS in the San Joaquin Valley. 31 30 For example, Table 2 (proposed mobile source measures and schedule), Table 3 (emissions reductions from proposed mobile source measures), and Table 4 (summary of emission reduction measures) of the Valley State SIP Strategy correspond to Tables 4-8, 4-9, and 4-7, respectively, of the 2018 PM 2.5 Plan, Chapter 4. 31 CARB Resolution 18-49, “San Joaquin Valley Supplement to the 2016 State Strategy for the State Implementation Plan,” October 25, 2018, 5. CARB provided the required public notice and opportunity for public comment prior to its October 25, 2018 public hearing on and adoption of the Valley State SIP Strategy. 32 The SIP submission includes proof of publication of the public notice for this public hearing. It also includes copies of the written and oral comments received during the State's public review process and CARB's responses thereto. 33 Therefore, we find that the Valley State SIP Strategy meets the procedural requirements for public notice and hearing in CAA sections 110(a) and 110(l) and 40 CFR 51.102. 32 CARB, “Notice of Public Meeting to Consider the San Joaquin Valley Supplement to the 2016 State Strategy for the State Implementation Plan,” September 21, 2018, and CARB Resolution 18-49. 33 CARB, “Board Meeting Comments Log,” November 2, 2018 and compilation of written comments; and J&K Court Reporting, LLC, “Meeting, State of California Air Resources Board,” October 25, 2018 (transcript of CARB's public hearing). The Valley State SIP Strategy became complete by operation of law on November 10, 2019. The sanctions clocks that were triggered by our December 6, 2018 findings that the State had failed to submit complete SIP submissions addressing the statutory requirements that apply to areas designated nonattainment for the PM 2.5 NAAQS, however, will continue to run until the EPA affirmatively determines, by letter to the Governor of California, that CARB has submitted a complete SIP submission addressing the identified deficiencies. 34 34 83 FR 62720 (citing required process for termination of sanctions clocks in 40 CFR 52.31(d)(5)). III. Clean Air Act Requirements for PM 2.5 Serious Area Plans A. Requirements for PM 2.5 Serious Area Plans Upon reclassification of a Moderate nonattainment area as a Serious nonattainment area under subpart 4 of part D, title I of the CAA, the Act requires the state to make a SIP submission that addresses the following Serious nonattainment area requirements: 35 35 81 FR 58010, 58074-58075. (1) A comprehensive, accurate, current inventory of actual emissions from all sources of PM 2.5 and PM 2.5 precursors in the area (CAA section 172(c)(3)); (2) Provisions to assure that the best available control measures (BACM), including best available control technology (BACT), for the control of direct PM 2.5 and PM 2.5 precursors shall be implemented no later than four years after the area is reclassified (CAA section 189(b)(1)(B)); (3) A demonstration (including air quality modeling) that the plan provides for attainment as expeditiously as practicable but no later than the end of the tenth calendar year after designation as a nonattainment area ( i.e., December 31, 2019, for the San Joaquin Valley for the 2006 PM 2.5 NAAQS), or where the state is seeking an extension of the attainment date under section 188(e), a demonstration that attainment by such date is impracticable and that the plan provides for attainment by the most expeditious alternative date practicable that is no more than five years later (CAA sections 188(c)(2) and 189(b)(1)(A)); (4) Plan provisions that require reasonable further progress (RFP) (CAA section 172(c)(2)); (5) Quantitative milestones which are to be achieved every three years until the area is redesignated attainment and which demonstrate RFP toward attainment by the applicable date (CAA section 189(c)); (6) Provisions to assure that control requirements applicable to major stationary sources of PM 2.5 also apply to major stationary sources of PM 2.5 precursors, except where the state demonstrates to the EPA's satisfaction that such sources do not contribute significantly to PM 2.5 levels that exceed the standard in the area (CAA section 189(e)); (7) Contingency measures to be implemented if the area fails to meet RFP or to attain by the applicable attainment date (CAA section 172(c)(9)); and (8) A revision to the nonattainment new source review (NSR) program to lower the applicable “major stationary source” 36 thresholds from 100 tons per year (tpy) to 70 tpy (CAA section 189(b)(3)). 36 For any Serious area, the terms “major source” and “major stationary source” include any stationary source that emits or has the potential to emit at least 70 tons per year of PM 2.5 . CAA section 189(b)(3) and 40 CFR 51.165(a)(1)(iv)(A)( 1 )( vii ) and ( viii ) (defining “major stationary source” in serious PM 2.5 nonattainment areas). Serious area plans must also satisfy the requirements for Moderate area plans in CAA section 189(a), to the extent the state has not already met those requirements in the Moderate area plan submitted for the area. In addition, the Serious area plan must meet the general requirements applicable to all SIP submissions under section 110 of the CAA, including the requirement to provide necessary assurances that the implementing agencies have adequate personnel, funding, and authority under section 110(a)(2)(E); and the requirements concerning enforcement provisions in section 110(a)(2)(C). The EPA provided its preliminary views on the CAA's requirements for particulate matter plans under part D, title I of the Act in the following guidance documents: (1) “State Implementation Plans; General Preamble for the Implementation of Title I of the Clean Air Act Amendments of 1990” (“General Preamble”); 37 (2) “State Implementation Plans; General Preamble for the Implementation of Title I of the Clean Air Act Amendments of 1990; Supplemental” (“General Preamble Supplement”); 38 and (3) “State Implementation Plans for Serious PM-10 Nonattainment Areas, and Attainment Date Waivers for PM-10 Nonattainment Areas Generally; Addendum to the General Preamble for the Implementation of Title I of the Clean Air Act Amendments of 1990” (“General Preamble Addendum”). 39 More recently, in an August 24, 2016 final rule entitled, “Fine Particulate Matter National Ambient Air Quality Standards: State Implementation Plan Requirements” (“PM 2.5 SIP Requirements Rule”), the EPA established regulatory requirements and provided further interpretive guidance on the statutory SIP requirements that apply to areas designated nonattainment for the PM 2.5 standards. 40 We discuss these regulatory requirements and interpretations of the Act as appropriate in our evaluation of the SJV PM 2.5 Plan below. 37 57 FR 13498 (April 16, 1992). 38 57 FR 18070 (April 28, 1992). 39 59 FR 41998 (August 16, 1994). 40 81 FR 58010 (August 24, 2016). B. Requirements for Extension of a Serious Area Attainment Date Under section 188(e) of the Act, a state may apply to the EPA for a single extension of the Serious area attainment date by up to five years, which the EPA may grant if the state satisfies certain conditions. Before the EPA may extend the attainment date for a Serious area under section 188(e), the state must: (1) Apply for an extension of the attainment date beyond the statutory attainment date; (2) demonstrate that attainment by the statutory attainment date is impracticable; (3) demonstrate that it has complied with all requirements and commitments pertaining to the area in the implementation plan; (4) demonstrate to the satisfaction of the Administrator that the plan for the area includes the “most stringent measures” that are included in the implementation plan of any state or are achieved in practice in any state, and can feasibly be implemented in the area; and (5) submit a demonstration of attainment by the most expeditious alternative date practicable. 41 41 CAA section 188(e) and 40 CFR 51.1005(b). For a discussion of EPA's interpretation of the requirements of section 188(e), see the preamble to the PM 2.5 SIP Requirements Rule, 81 FR 58010, 58094-58097, and the General Preamble Addendum, 59 FR 41998, 42002. A state must seek an extension of the Serious area attainment date at the same time it submits the Serious area attainment plan, if the state cannot demonstrate attainment by the otherwise applicable statutory attainment date. 42 42 40 CFR 51.1005(b)(2). Under the PM 2.5 SIP Requirements Rule, a state seeking an extension of the Serious area attainment date under section 188(e) must submit a Serious area attainment plan that meets the following requirements: (1) Base year and attainment projected emissions inventory requirements in 40 CFR 51.1008(b); (2) the most stringent measure requirement in 40 CFR 51.1005(b)(1)(iii) and 51.1010(b), and best available control measures not previously submitted; (3) attainment demonstration and modeling requirements in 40 CFR 51.1011 and 40 CFR 51.1005(b)(1)(i); (4) reasonable further progress requirements in 40 CFR 51.1012; (5) quantitative milestone requirements in 40 CFR 51.1013; (6) contingency measure requirements in 40 CFR 51.1014; and (7) nonattainment new source review plan requirements pursuant to 40 CFR 51.165. 43 43 40 CFR 51.1005(b)(2). With respect to contingency measures and nonattainment new source review plan provisions, the EPA interprets section 51.1005(b)(2) to require submission of complete plan provisions addressing these requirements but not to require the EPA to approve such provisions before granting a section 188(e) extension request. 81 FR 58010, 58094-58095. In addition to establishing specific preconditions for an extension of the Serious area attainment date, section 188(e) provides that the EPA may consider a number of factors in determining whether to grant an extension and the appropriate length of time for any such extension. These factors are: (1) The nature and extent of nonattainment in the area, (2) the types and numbers of sources or other emitting activities in the area (including the influence of uncontrollable natural sources and trans-boundary emissions from foreign countries), (3) the population exposed to concentrations in excess of the standard in the area, (4) the presence and concentrations of potentially toxic substances in the mix of particulate emissions in the area, and (5) the technological and economic feasibility of various control measures. 44 Notably, neither the statutory requirements nor the discretionary factors identified in section 188(e) include the specific ambient air quality conditions in section 188(d)(2), which must be met for an area to qualify for an extension of a Moderate area attainment date. 44 CAA section 188(e). We evaluate the state's request for an extension of the Serious area attainment date in accordance with these statutory criteria and regulatory requirements, as described below. Step 1: Demonstrate that attainment by the statutory Serious area attainment date is impracticable. Section 188(e) authorizes the EPA to grant a state request for an extension of the Serious area attainment date if, among other things, attainment by the date established under section 188(c) would be impracticable. In order to demonstrate impracticability, the plan must show that the implementation of BACM and BACT (and additional feasible measures) on relevant source categories will not bring the area into attainment by the statutory Serious area attainment date. 45 For the San Joaquin Valley, the Serious area attainment date for the 2006 PM 2.5 NAAQS under section 188(c)(2) was December 31, 2019. 46 BACM, including BACT, is the required level of control for a Serious area that must be in place before the Serious area attainment date. Therefore, we interpret the Act as requiring that a state provide for at least the implementation of BACM, including BACT, before it can claim that is impracticable to attain by the statutory deadline. The statutory provision for demonstrating impracticability requires that the demonstration be based on air quality modeling. 47 45 81 FR 58010, 58094. 46 Under CAA section 188(c)(2), the attainment date for a Serious area “shall be as expeditiously as practicable but no later than the end of the tenth calendar year beginning after the area's designation as nonattainment. . . .” The EPA designated the San Joaquin Valley as nonattainment for the 2006 PM 2.5 NAAQS effective December 14, 2009. 74 FR 58688. Therefore, the latest permissible attainment date under section 188(c)(2), for purposes of the 2006 PM 2.5 NAAQS in this area, is December 31, 2019. 47 CAA section 189(b)(1)(A). Step 2: Comply with all requirements and commitments in the applicable implementation plan. A second precondition for an extension of the Serious area attainment under section 188(e) is a showing that the state has complied with all requirements and commitments pertaining to that area in the implementation plan. We interpret this criterion to mean that the state has implemented the control measures and commitments in the SIP revisions it has submitted to address the applicable requirements in CAA sections 172 and 189 for PM 2.5 nonattainment areas. For a Serious area attainment date extension request being submitted simultaneously with the initial Serious area attainment plan for the area, the EPA interprets section 188(e) not to require the area to have a fully approved Moderate area attainment plan, and to allow for extension of the attainment date if the area has complied with all Moderate area requirements and commitments pertaining to that area in the state's submitted Moderate area implementation plan. 48 This interpretation is based on the plain language of section 188(e), which requires the state to comply with all requirements and commitments pertaining to the area in the implementation plan. 49 48 81 FR 58010, 58095. 49 The Ninth Circuit Court of Appeals upheld this interpretation of section 188(e) in Vigil v. Leavitt, 366 F.3d 1025, amended at 381 F.3d 826 (9th Cir. 2004). Step 3: Demonstrate the inclusion of the most stringent measures. A third precondition for an extension of the Serious area attainment under section 188(e) is for the state to demonstrate to the satisfaction of the Administrator that the plan for the area includes the most stringent measures that are included in the implementation plan of any state, or are achieved in practice in any state, and can feasibly be implemented in the area. The EPA has defined the term “most stringent measure” (MSM) as “any permanent and enforceable control measure that achieves the most stringent emissions reductions in direct PM 2.5 emissions and/or emissions of PM 2.5 plan precursors from among those control measures which are either included in the SIP for any other NAAQS, or have been achieved in practice in any state, and that can feasibly be implemented in the relevant PM 2.5 NAAQS nonattainment area.” 50 The Act does not specify an implementation deadline for MSM, but because the clear intent of section 188(e) is to minimize the length of any attainment date extension, the EPA has interpreted the Act to require implementation of MSM as expeditiously as practicable and no later than one year before the extended Serious area attainment date identified by the state in its extension request. 51 50 40 CFR 51.1000 and 81 FR 58010, 58096-58097; see also General Preamble Addendum, 42010 and 65 FR 19964, 19968 (April 13, 2000). 51 81 FR 58010, 58097. An MSM demonstration must satisfy the requirements of the PM 2.5 SIP Requirements Rule as described in the preamble to the rule, as follows: 52 52 40 CFR 51.1010(b) and 81 FR 58010, 58095-58097. (1) Update the emission inventory to identify all sources of direct PM 2.5 and all PM 2.5 precursor emissions in the nonattainment area; (2) Identify all potential MSM to reduce emissions from sources of direct PM 2.5 and PM 2.5 plan precursors that are approved into any state implementation plan or used in practice in any state; (3) Compare the potential MSM for each relevant source category to the measures, if any, already adopted for that source category in the nonattainment area to determine whether such potential MSM would further reduce emissions and, where the state chooses to reject a measure from further consideration, demonstrate that it is not technologically or economically feasible to implement the measure in whole or in part within five years after the applicable attainment date for the area; and (4) Adopt and implement all potential MSM identified through this process that collectively will achieve attainment as expeditiously as practicable and no later than five years after the applicable attainment date, except those measures for which the state has provided reasoned justification for rejection, based on technological or economic feasibility. The level of control required under the MSM standard may depend on how well other areas have chosen to control their sources. If a source category has not been well controlled in other areas, MSM could theoretically result in a low level of control. This contrasts with BACM and BACT, which represent the “best” level of control feasible for an area, regardless of whether it has been implemented elsewhere. Thus, in some cases the MSM requirement may result in no more controls or emission reductions than those that result from implementing BACM and BACT. However, given the strategy in the nonattainment provisions of the Act to offset longer attainment timeframes with more stringent emission control requirements, we interpret the MSM provision so as to increase the potential that it will result in additional controls beyond the set of measures adopted as BACM and BACT. Accordingly, states are required to reanalyze any measures that were rejected during the state's BACM and BACT analysis to see if they have become feasible in the area given the longer attainment date sought under CAA section 188(e) and changes that have occurred in the interim that improve the feasibility of such measures. 53 MSM may also involve increasing the coverage of measures that were previously adopted as BACM and BACT. 54 53 Id. 54 Id. at 58096. Notably, the “to the satisfaction of the Administrator” qualifier on the MSM requirement indicates that Congress granted the EPA considerable discretion in determining whether a plan in fact includes MSM, recognizing that the overall intent of section 188(e) is that the Agency grant as short an extension as practicable, consistent with the objective of expeditious attainment of the NAAQS. For this reason, the EPA will apply greater scrutiny to the evaluation of MSM for source categories that contribute the most to the PM 2.5 problem in the SJV and less scrutiny to source categories that contribute less to the PM 2.5 problem. Step 4: Demonstrate attainment by the most expeditious alternative date practicable. Section 189(b)(1)(A) requires that the Serious area plan demonstrate attainment, using air quality modeling, by the most expeditious date practicable after the statutory Serious area attainment date. 55 Evaluation of a modeled attainment demonstration consists of two parts: Evaluation of the technical adequacy of the modeling itself and evaluation of the control measures that are relied on to demonstrate attainment. The EPA's determination of whether the plan provides for attainment by the most expeditious date practicable depends on whether the plan provides for implementation of BACM and BACT no later than the statutory implementation deadline, MSM as expeditiously as practicable and no later than one year before the extended attainment date requested by the state, and any other technologically and economically feasible measures that will result in attainment as expeditiously as practicable. 55 Id. at 58097. Step 5: Apply for an attainment date extension. Finally, the state must apply in writing to the EPA for an extension of a Serious area attainment date, and this request must accompany the modeled attainment demonstration showing attainment by the most expeditious alternative date practicable. Additionally, the state must provide the public reasonable notice and opportunity for a public hearing on the attainment date extension request before submitting it to the EPA, in accordance with the requirements for SIP revisions in CAA section 110. IV. Review of the San Joaquin Valley PM 2.5 Serious Area Plan and Extension Application A. Emissions Inventory 1. Statutory and Regulatory Requirements CAA section 172(c)(3) requires that each SIP include a comprehensive, accurate, current inventory of actual emissions from all sources of the relevant pollutant or pollutants in the nonattainment area. The EPA discussed the emissions inventory requirements that apply to PM 2.5 nonattainment areas, including Serious area requirements, in the PM 2.5 SIP Requirements Rule and codified these requirements in 40 CFR 51.1008. 56 The EPA has also issued guidance concerning emissions inventories for PM 2.5 nonattainment areas. 57 56 81 FR 58010, 58078-58079. 57 “Emissions Inventory Guidance for Implementation of Ozone and Particulate Matter National Ambient Air Quality Standards (NAAQS) and Regional Haze Regulations,” U.S. EPA, May 2017 (“Emissions Inventory Guidance”), available at https://www.epa.gov/air-emissions-inventories/air-emissions-inventory-guidance-implementation-ozone-and-particulate. The base year emissions inventory should provide a state's best estimate of actual emissions from all sources of the relevant pollutants in the area, i.e., all emissions that contribute to the formation of a particular NAAQS pollutant. For the PM 2.5 NAAQS, the base year inventory must include direct PM 2.5 emissions, separately reported filterable and condensable PM 2.5 emissions, 58 and emissions of all chemical precursors to the formation of secondary PM 2.5 : nitrogen oxides (NO X ), sulfur dioxide (SO 2 ), volatile organic compounds (VOC), and ammonia (NH 3 ). 59 In addition, the emissions inventory base year for a Serious PM 2.5 nonattainment area must be one of the three years for which monitored data were used to reclassify the area to Serious, or another technically appropriate year justified by the state in its Serious area SIP submission. 60 58 The Emissions Inventory Guidance identifies the types of sources for which the EPA expects states to provide condensable PM emission inventories. Emissions Inventory Guidance, section 4.2.1 (“Condensable PM Emissions”), 63-65. 59 40 CFR 51.1008. 60 40 CFR 51.1008(b)(1). A state's SIP submission must include documentation explaining how it calculated emissions data for the inventory. In estimating mobile source emissions, a state should use the latest emissions models and planning assumptions available at the time the SIP is developed. The latest EPA-approved version of California's mobile source emission factor model for estimating tailpipe, brake, and tire wear emissions from on-road mobile sources that was available during the State's and District's development of the SJV PM 2.5 Plan was EMFAC2014. 61 Following CARB's submission of the Plan, the EPA approved EMFAC2017, the latest revision to this mobile source emissions model, and established grace periods during which EMFAC2014 may continue to be used for transportation conformity purposes ( i.e., new regional emissions analyses and CO, PM 10 , and PM 2.5 hot-spot analyses). 62 States are also required to use the EPA's “Compilation of Air Pollutant Emission Factors” (“AP-42”) road dust method for calculating re-entrained road dust emissions from paved roads. 63 64 61 80 FR 77337 (December 14, 2015). EMFAC is short for EM ission FAC tor. The EPA announced the availability of the EMFAC2014 model, effective on the date of publication in the Federal Register , for use in state implementation plan development and transportation conformity in California. Upon that action, EMFAC2014 was required to be used for all new regional emissions analyses and CO, PM 10 , and PM 2.5 hot-spot analyses that were started on or after December 14, 2017, which was the end of the grace period for using the prior mobile source emissions model, EMFAC2011. 62 84 FR 41717 (August 15, 2019). The grace period for new regional emissions analyses begins on August 15, 2019 and ends on August 16, 2021, while the grace period for hot-spot analyses begins on August 15, 2019 and ends on August 17, 2020. 84 FR 41717, 41720. 63 The EPA released an update to AP-42 in January 2011 that revised the equation for estimating paved road dust emissions based on an updated data regression that included new emission tests results. 76 FR 6328 (February 4, 2011). CARB used the revised 2011 AP-42 methodology in developing on-road mobile source emissions; see https://www.arb.ca.gov/ei/areasrc/fullpdf/full7-9_2016.pdf. 64 AP-42 has been published since 1972 as the primary source of the EPA's emission factor information. https://www.epa.gov/air-emissions-factors-and-quantification/ap-42-compilation-air-emissions-factors. It contains emission factors and process information for more than 200 air pollution source categories. A source category is a specific industry sector or group of similar emitting sources. The emission factors have been developed and compiled from source test data, material balance studies, and engineering estimates. In addition to the base year inventory submitted to meet the requirements of CAA section 172(c)(3), the state must also submit a projected attainment year inventory and emissions projections for each RFP milestone year. 65 These future emissions projections are necessary components of the attainment demonstration required under CAA section 189(a)(1) and (b)(1) and the demonstration of RFP required under section 172(c)(2). 66 Emissions projections for future years (which are referred to in the Plan as “forecasted inventories”) should account for, among other things, the ongoing effects of economic growth and adopted emissions control requirements. The state's SIP submission should include documentation to explain how the emissions projections were calculated. Where a state chooses to allow new major stationary sources or major modifications to use emission reductions credits (ERCs) that were generated through shutdown or curtailed emissions units occuring before the base year of an attainment plan, the projected emissions inventory used to develop the attainment demonstration must explicitly include the emissions from such previously shutdown or curtailed emissions units. 67 65 40 CFR 51.1008 and 51.1012. Also, see Emissions Inventory Guidance, section 3 (“SIP Inventory Requirements and Recommendations”). 66 40 CFR 51.1004, 51.1008, 51.1011, and 51.1012. 67 40 CFR 51.165(a)(3)(ii)(C)( 1 ). 2. Summary of State's Submission Summaries of the planning emissions inventories for direct PM 2.5 and PM 2.5 precursors (NO X , SO X , 68 VOC, 69 and ammonia) and the documentation for the inventories for the San Joaquin Valley PM 2.5 nonattainment area are located in Appendix B (“Emissions Inventory”) and Appendix I (“New Source Review and Emission Reduction Credits”) of the 2018 PM 2.5 Plan. 68 The SJV PM 2.5 Plan generally uses “sulfur oxides” or “SO X ” in reference to SO 2 as a precursor to the formation of PM 2.5 . We use SO X and SO 2 interchangeably throughout this notice. 69 The SJV PM 2.5 Plan generally uses “reactive organic gasses” or “ROG” in reference to VOC as a precursor to the formation of PM 2.5 . We use ROG and VOC interchangeably throughout this notice. CARB and District staff worked together to develop the emissions inventories for the San Joaquin Valley PM 2.5 nonattainment area. The District worked with operators of the stationary facilities in the nonattainment area to develop the stationary source emissions estimates. The responsibility for developing estimates for the area sources such as agricultural burning and paved road dust was shared by the District and CARB. CARB staff developed the emissions inventories for both on-road and non-road mobile sources. 70 70 The EPA regulations refer to “non-road” vehicles and engines whereas CARB regulations refer to “Other Mobile Sources” or “off-road” vehicles and engines. These terms refer to the same types of vehicles and engines. We refer herein to such vehicles and engines as “non-road” sources. The Plan includes winter (24-hour) average and annual average daily planning inventories for the 2013 base year, which were modeled from the 2012 emissions inventory, and estimated emissions for forecasted years from 2017 through 2028 for the attainment and RFP demonstrations for the 1997, 2006, and 2012 PM 2.5 NAAQS. 71 Today we are proposing action on those winter average and annual average emissions inventories necessary to support the attainment plan and section 188(e) extension request for the 2006 PM 2.5 NAAQS— i.e., the 2013 base year inventory, forecasted inventories for the RFP milestone years of 2017, 2020, 2023, and 2026, and the forecasted 2024 attainment year inventory. Each inventory includes emissions from stationary, area, on-road, and non-road sources. 71 2018 PM 2.5 Plan, App. B, B-18 to B-19. The winter average daily planning inventory corresponds to the months of November through April, when daily, ambient PM 2.5 concentrations are typically highest. The base year inventory is from the California Emissions Inventory Development and Reporting System (CEIDARS) and future year inventories were estimated using the California Emission Projection Analysis Model (CEPAM), 2016 SIP Baseline Emission Projections, version 1.05. The base year inventories for stationary sources were developed using actual emissions reports made by facility operators. The State developed the base year emissions inventory for area sources using the most recent models and methodologies available at the time the State was developing the Plan. 72 The Plan also includes background, methodology, and inventories of condensable and filterable PM 2.5 emissions from stationary point and non-point combustion sources that are expected to generate condensable PM 2.5 . 73 CARB used EMFAC2014 to estimate on-road motor vehicle emissions based on transportation activity data from the 2014 Regional Transportation Plan (2014 RTP) adopted by the transportation planning agencies in the San Joaquin Valley. 74 Re-entrained paved road dust emissions were calculated using a CARB methodology consistent with the EPA's AP-42 road dust methodology. 75 72 2018 PM 2.5 Plan, App. B, section B.2 (“Emissions Inventory Summary and Methodology”). 73 Id. at B-42 to B-44. 74 Id. at B-37. 75 Id. at B-28. CARB developed the emissions forecasts by applying growth and control profiles to the base year inventory. CARB's mobile source emissions projections take into account predicted activity rates and vehicle fleet turnover by vehicle model year and adopted controls. 76 In addition, the Plan states that the District is providing for use of pre-base year ERCs as offsets by accounting for such ERCs in the projected 2025 emissions inventory. 77 The 2018 PM 2.5 Plan identifies growth factors, control factors, and estimated offset use between 2013 and 2025 for direct PM 2.5 , NO X , SO X , and VOC emissions by source category and lists all pre-base year ERCs issued by the District for PM 10 , NO X , SO X , and VOC emissions, by facility. 78 76 Id. at B-18, B-19. 77 2018 PM 2.5 Plan, App. I, I-1 through I-5. 78 Id. at App. I, Tables I-1 through I-5. Table 1 provides a summary of the winter (24-hour) average inventories in tons per day (tpd) of direct PM 2.5 and NO X emissions for the 2013 base year. Table 2 provides a summary of annual average inventories of direct PM 2.5 and NO X emissions for the 2013 base year. These annual average inventories provide the basis for the control measure analysis and the RFP and attainment demonstrations in the SJV PM 2.5 Plan. Table 1—San Joaquin Valley Winter Average Emissions Inventory for Direct PM 2.5 and PM 2.5 Precursors for the 2013 Base Year [tpd] Category Direct PM 2.5 NO X SO X VOC Ammonia Stationary Sources 8.5 35.0 6.9 86.6 13.9 Area Sources 41.4 11.5 0.5 156.8 291.5 On-Road Mobile Sources 6.4 188.7 0.6 51.1 4.4 Non-Road Mobile Sources 4.4 65.3 0.3 27.4 0.0 Totals a 60.8 300.5 8.4 321.9 309.8 Source: 2018 PM 2.5 Plan, Appendix B, Tables B-1 through B-5. a Totals reflect disaggregated emissions and may not add exactly as shown here due to rounding. Table 2—San Joaquin Valley Annual Average Emissions Inventory for Direct PM 2.5 and PM 2.5 Precursors for the 2013 Base Year [tpd] Category Direct PM 2.5 NO X SO X VOC Ammonia Stationary Sources 8.8 38.6 7.2 87.1 13.9 Area Sources 41.5 8.1 0.3 153.4 310.9 On-Road Mobile Sources 6.4 183.1 0.6 49.8 4.4 Non-Road Mobile Sources 5.8 87.4 0.3 33.8 0.0 Totals a 62.5 317.2 8.5 324.1 329.2 Source : 2018 PM 2.5 Plan, Appendix B, Tables B-1 through B-5. a Totals reflect disaggregated emissions and may not add exactly as shown here due to rounding. 3. EPA's Evaluation and Proposed Action The inventories in the 2018 PM 2.5 Plan are based on the most current and accurate information available to the State and District at the time they were developing the Plan and inventories, including the latest version of California's mobile source emissions model that had been approved by the EPA at the time, EMFAC2014. The inventories comprehensively address all source categories in the San Joaquin Valley PM 2.5 nonattainment area and are consistent with the EPA's inventory guidance. In accordance with 40 CFR 51.1008(b)(1), the 2013 base year is one of the three years for which monitored data were used for reclassifying the San Joaquin Valley to Serious for the 2006 PM 2.5 NAAQS, 79 and it represents actual annual average emissions of all sources within the nonattainment area. Direct PM 2.5 and PM 2.5 precursors are included in the inventories, and filterable and condensable direct PM 2.5 emissions are identified separately. 79 81 FR 2993, 2994. With respect to future year baseline projections, we have reviewed the growth and control factors and find them acceptable and thus conclude that the future baseline emissions projections in the 2018 PM 2.5 Plan reflect appropriate calculation methods and the latest planning assumptions. Also, as a general matter, the EPA will approve a SIP submission that takes emissions reduction credit for a control measure only where the EPA has approved the measure as part of the SIP. Thus, for example, to take credit for the emissions reductions from newly-adopted or amended District rules for stationary sources, the related rules must be approved by the EPA into the SIP. See the EPA's “Technical Support Document, General Evaluation, San Joaquin Valley PM 2.5 Plan for the 2006 PM 2.5 NAAQS,” February 2020 (“EPA's General Evaluation TSD”). Table III-A of EPA's General Evaluation TSD shows District rules with post-2013 compliance dates that are reflected in the future year baseline inventories, along with information on the EPA's approval of these rules, and shows that stationary source emissions reductions assumed by the SJV PM 2.5 Plan for future years are supported by rules approved as part of the California SIP for the San Joaquin Valley. With respect to mobile sources, the EPA has taken action in recent years to approve CARB mobile source regulations into the state-wide portion of the California SIP. We therefore find that the future year baseline projections in the 2018 PM 2.5 Plan are properly supported by SIP-approved stationary and mobile source measures. 80 80 The future year emissions projections in the SJV PM 2.5 Plan assume implementation of CARB's Zero Emissions Vehicle (ZEV) sales mandate and greenhouse gas (GHG) standards. On September 27, 2019, the U.S. Department of Transportation and the EPA issued a notice of final rulemaking for the Safer Affordable Fuel-Efficient (SAFE) Vehicles Rule Part One: One National Program that, among other things, withdrew the EPA's 2013 waiver of preemption for the ZEV sales mandate and GHG standards. 84 FR 51310. See also proposed SAFE rule at 83 FR 42986 (August 24, 2018). However, the agencies' final rule withdrawing the 2013 waiver did not include final action on the federal fuel economy and GHG vehicle emissions standards from the SAFE proposal. If the fuel economy and GHG standards are finalized prior to our final rulemaking on the SJV PM 2.5 Plan, we will evaluate and address, as appropriate, the impact of the SAFE action on our proposed action. For these reasons, we are proposing to approve the 2013 base year emissions inventory in the 2018 PM 2.5 Plan as meeting the requirements of CAA section 172(c)(3) and 40 CFR 51.1008. We are also proposing to find that the forecasted inventories in the Plan provide an adequate basis for the BACM, MSM, RFP, and attainment demonstrations in the SJV PM 2.5 Plan. B. PM 2.5 Precursors 1. Statutory and Regulatory Requirements The composition of PM 2.5 is complex and highly variable due in part to the large contribution of secondary PM 2.5 to total fine particle mass in most locations, and to the complexity of secondary particle formation processes. A large number of possible chemical reactions, often non-linear in nature, can convert gaseous SO 2 , NO X , VOC, and ammonia to PM 2.5 , making them precursors to PM 2.5 . 81 Formation of secondary PM 2.5 may also depend on atmospheric conditions, including solar radiation, temperature, and relative humidity, and the interactions of precursors with preexisting particles and with cloud or fog droplets. 82 81 “Air Quality Criteria for Particulate Matter” (EPA/600/P-99/002aF), EPA, October 2004, Ch. 3. 82 “Regulatory Impact Analysis for the Final Revisions to the National Ambient Air Quality Standards for Particulate Matter” (EPA/452/R-12-005), EPA, December 2012), 2-1. Under subpart 4 of part D, title I of the CAA and the PM 2.5 SIP Requirements Rule, each state containing a PM 2.5 nonattainment area must evaluate all PM 2.5 precursors for regulation unless, for any given PM 2.5 precursor, the state demonstrates to the Administrator's satisfaction that such precursor does not contribute significantly to PM 2.5 levels that exceed the NAAQS in the nonattainment area. 83 The provisions of subpart 4 do not define the term “precursor” for purposes of PM 2.5 , nor do they explicitly require the control of any specifically identified PM 2.5 precursor. The statutory definition of “air pollutant,” however, provides that the term “includes any precursors to the formation of any air pollutant, to the extent the Administrator has identified such precursor or precursors for the particular purpose for which the term `air pollutant' is used.” 84 The EPA has identified SO 2 , NO X , VOC, and ammonia as precursors to the formation of PM 2.5 . 85 Accordingly, the attainment plan requirements of subpart 4 apply to emissions of all four precursor pollutants and direct PM 2.5 from all types of stationary, area, and mobile sources, except as otherwise provided in the Act ( e.g., CAA section 189(e)). 83 81 FR 58010, 58017-58020. 84 CAA section 302(g). 85 81 FR 58010, 58015. Section 189(e) of the Act requires that the control requirements for major stationary sources of direct PM 10 also apply to major stationary sources of PM 10 precursors, except where the Administrator determines that such sources do not contribute significantly to PM 10 levels that exceed the standard in the area. Section 189(e) contains the only express exception to the control requirements under subpart 4 [ e.g., requirements for reasonably available control measures (RACM) and reasonably available control technology (RACT), BACM and BACT, MSM, and NSR] for sources of direct PM 2.5 and PM 2.5 precursor emissions. Although section 189(e) explicitly addresses only major stationary sources, the EPA interprets the Act as authorizing it also to determine, under appropriate circumstances, that regulation of specific PM 2.5 precursors from other source categories in a given nonattainment area is not necessary. 86 For example, under the EPA's longstanding interpretation of the control requirements that apply to stationary, area, and mobile sources of PM 10 precursors in the nonattainment area under CAA section 172(c)(1) and subpart 4, 87 a state may demonstrate in a SIP submission that control of a certain precursor pollutant is not necessary in light of its insignificant contribution to ambient PM 10 levels in the nonattainment area. 88 86 Id. at 58018-58019. 87 General Preamble, 57 FR 13498, 13539-42. 88 Courts have upheld this approach to the requirements of subpart 4 for PM 10 . See, e.g., Assoc. of Irritated Residents v. EPA, et al., 423 F.3d 989 (9th Cir. 2005). Under the PM 2.5 SIP Requirements Rule, a state may elect to submit to the EPA a “comprehensive precursor demonstration” for a specific nonattainment area to show that emissions of a particular precursor from all existing sources located in the nonattainment area do not contribute significantly to PM 2.5 levels that exceed the standard in the area. 89 If the EPA determines that the contribution of the precursor to PM 2.5 levels in the area is not significant and approves the demonstration, the state is not required to control emissions of the relevant precursor from existing sources in the attainment plan. 90 89 40 CFR 51.1006(a)(1). 90 Id. In addition, in May 2019, the EPA issued the “PM 2.5 Precursor Demonstration Guidance” (“PM 2.5 Precursor Guidance”), which provides recommendations to states for analyzing nonattainment area PM 2.5 emissions and developing such optional precursor demonstrations, consistent with the PM 2.5 SIP Requirements Rule. 91 The PM 2.5 Precursor Guidance builds upon the draft version of the guidance, released on November 17, 2016 (“Draft PM 2.5 Precursor Guidance”), which CARB referenced in developing its precursor demonstration in the SJV PM 2.5 Plan. 92 The EPA's recommendations in the PM 2.5 Precursor Guidance are generally consistent with those in the Draft PM 2.5 Precursor Guidance, with some exceptions, including that the EPA's recommended contribution threshold for the 24-hour PM 2.5 NAAQS changed from 1.3 µg/m 3 in the draft guidance to 1.5 µg/m 3 in the final guidance. 91 “PM 2.5 Precursor Demonstration Guidance,” EPA-454/R-19-004, May 2019, including Memo dated May 30, 2019 from Scott Mathias, Acting Director, Air Quality Policy Division and Richard Wayland, Director, Air Quality Assessment Division, Office of Air Quality Planning and Standards (OAQPS), EPA to Regional Air Division Directors, Regions 1-10, EPA. 92 “PM 2.5 Precursor Demonstration Guidance, Draft for Public Review and Comments,” EPA-454/P-16-001, November 17, 2016, including Memo dated November 17, 2016 from Stephen D. Page, Director, OAQPS, EPA to Regional Air Division Directors, Regions 1-10, EPA. We are evaluating the SJV PM 2.5 Plan in accordance with the presumption embodied within subpart 4 that all PM 2.5 precursors must be addressed in the State's evaluation of potential control measures, unless the State adequately demonstrates that emissions of a particular precursor or precursors do not contribute significantly to ambient PM 2.5 levels that exceed the PM 2.5 NAAQS in the nonattainment area. In reviewing any determination by the State to exclude a PM 2.5 precursor from the required evaluation of potential control measures, we consider both the magnitude of the precursor's contribution to ambient PM 2.5 concentrations in the nonattainment area and the sensitivity of ambient PM 2.5 concentrations in the area to reductions in emissions of that precursor. 93 93 40 CFR 51.1006(a)(1)(i) and (ii). 2. Summary of State's Submission The State presents a brief summary of its PM 2.5 precursor analysis in Chapter 6 of the 2018 PM 2.5 Plan and the full precursor demonstration in Appendix G of the 2018 PM 2.5 Plan. 94 CARB also provided clarifying information on its precursor assessment, including an Attachment A to its letter transmitting the SJV PM 2.5 Plan to the EPA 95 and further clarifications in three email transmittals. 96 94 A copy of the contents of App. G appears in the CARB Staff Report, App. C4 (“Precursor Demonstrations for Ammonia, SO X , and ROG”). 95 Letter dated May 9, 2019, from Richard Corey, Executive Officer, CARB, to Michael Stoker, Regional Administrator, EPA Region IX, Attachment A (“Clarifying information for the San Joaquin Valley 2018 Plan regarding model sensitivity related to ammonia and ammonia controls”). 96 Email dated June 20, 2019, “RE: SJV model disbenefit from SO X reduction,” from Jeremy Avise, CARB, to Scott Bohning, EPA Region IX, with attachment (“CARB's June 2019 Precursor Clarification”); email dated September 19, 2019, “FW: SJV species responses,” from Jeremy Avise, CARB, to Scott Bohning, EPA Region IX, with attachments (“CARB's September 2019 Precursor Clarification”); and email dated October 18, 2019, from Laura Carr, CARB to Scott Bohning, Jeanhee Hong, and Rory Mays, EPA Region IX, with attachment “Clarifying Information on Ammonia” (“CARB's October 2019 Precursor Clarification”). The Plan provides both concentration-based and sensitivity-based analyses of precursor contributions to ambient PM 2.5 concentrations in the San Joaquin Valley. These analyses led the State to conclude that direct PM 2.5 and NO X emissions contribute significantly to ambient PM 2.5 levels that exceed the PM 2.5 NAAQS in the San Joaquin Valley while ammonia, SO X , and VOC do not contribute significantly to such exceedances, as discussed below. 97 We summarize the State's analysis and conclusions below. For a more detailed summary of the precursor demonstration in the Plan, please refer to the EPA's “Technical Support Document, EPA Evaluation of PM 2.5 Precursor Demonstration, San Joaquin Valley PM 2.5 Plan for the 2006 PM 2.5 NAAQS,” February 2020 (“EPA's PM 2.5 Precursor TSD”). 97 Direct PM 2.5 emissions are considered a primary source of ambient PM 2.5 ( i.e., no further formation in the atmosphere is required), and therefore is not considered a precursor pollutant under subpart 4, which may differ from a more generalized understanding of what contributes to ambient PM 2.5 . For direct PM 2.5 and NO X , the State modeled the sensitivity of ambient PM 2.5 in the San Joaquin Valley to a 30 percent (%) reduction in anthropogenic emissions of each pollutant in 2013, 2020, and 2024. 98 The State concluded that direct PM 2.5 and NO X emissions reductions will continue to have a significant impact on annual and 24-hour PM 2.5 design values in the San Joaquin Valley, with NO X reductions being particularly important. 99 Consistent with this conclusion, the State focused the control strategy and attainment demonstration on these two pollutants, as described in section IV.D of this preamble. 98 SJV PM 2.5 Plan, Ch. 6, 6-11 to 6-12. CARB modeled the impacts of both NO X reductions and direct PM 2.5 reductions but the direct PM 2.5 results were used only as a point of comparison, as direct PM 2.5 emissions must be regulated in all PM 2.5 nonattainment areas. 99 Id. Ch. 6, 6-12; and 2018 PM 2.5 Plan, App. G, 2. CARB presents its sensitivity analysis for emission reductions in direct PM 2.5 and NO X in the Plan's attainment demonstration appendix. 2018 PM 2.5 Plan, App. K, Table 46 (annual average design values) and Table 50 (24-hour average design values). For ammonia, SO X , and VOC, CARB assessed the 2015 annual average concentration of each precursor in ambient PM 2.5 at Bakersfield, for which the necessary speciated PM 2.5 data is available and where the highest PM 2.5 design values have been recorded in most years, and compared those concentrations to the recommended annual average contribution threshold of 0.2 µg/m 3 from the Draft PM 2.5 Precursor Guidance, which was available at the time the State developed the SIP. 100 The contributions of ammonia, SO X , and VOC were 5.2 µg/m 3 , 1.6 µg/m 3 and 6.2 µg/m 3 , respectively. 100 SJV PM 2.5 Plan, App. G, 3. The Plan does not present a concentration-based analysis for the 24-hour average concentrations in the San Joaquin Valley. Instead, CARB relied on the annual average concentration based analysis as an interim step to the sensitivity-based analysis, for which CARB assessed the sensitivity of both 24-hour average and annual average ambient PM 2.5 concentrations to precursor emission reductions. Separately, the Plan presents a graphical representation of annual average ambient PM 2.5 components ( i.e., crustal particulate matter, elemental carbon, organic matter, ammonium sulfate, and ammonium nitrate) for 2011-2013 for Bakersfield, Fresno, and Modesto. SJV PM 2.5 Plan, Ch. 3, 3-3 to 3-4. Given that these levels are well above the EPA's recommended contribution threshold in the Draft PM 2.5 Precursor Guidance, CARB then modeled the sensitivity of ambient PM 2.5 in the San Joaquin Valley to 30% and 70% reductions in anthropogenic emissions of each precursor pollutant in 2013 (the Plan's base year), 2020 (the modeled attainment year for the 1997 PM 2.5 NAAQS), and 2024 (the modeled attainment year for the 2006 PM 2.5 NAAQS). 101 CARB supplemented the sensitivity analysis with consideration of additional information, including factors identified in the Draft PM 2.5 Precursor Guidance, such as emission trends, the appropriateness of future year versus base year sensitivity, available emission controls, and the severity of nonattainment. 102 The final version of the PM 2.5 Precursor Guidance confirms the relevance of these factors in a sensitivity analysis. 103 101 SJV PM 2.5 Plan, Ch. 6, 6-11 to 6-12. 102 Id. at App. G, 5. 103 PM 2.5 Precursor Guidance, 18-19 (consideration of additional information), 31 (available emission controls), and 35-36 (appropriateness of future year versus base year sensitivity). The State's sensitivity-based analysis used the same modeling platform as that used for the Plan's attainment demonstration. The State modeled the sensitivity of ambient PM 2.5 concentrations in San Joaquin Valley to 30% and 70% emission reductions in 2013, 2020, and 2024 for each of ammonia, SO X , and VOC. The State estimated base case (2013, 2020, and 2024) design values for PM 2.5 using Relative Response Factors and calculated the ammonia precursor contribution for a given year and for each sensitivity scenario (30% and 70% emissions reductions) as the difference between its base case design value and the design value for each sensitivity scenario. 104 104 This procedure is the procedure recommended by the EPA. PM 2.5 Precursor Guidance, 37. We summarize the State's sensitivity-based analysis and additional information in the sections that follow for ammonia, SO X , and VOC. a. Ammonia For ammonia, the State compared the 24-hour precursor contributions to 1.3 µg/m 3 , the recommended contribution threshold in the Draft PM 2.5 Precursor Guidance. For a modeled 30% ammonia emission reduction, the ambient PM 2.5 responses in 2013 ranged from 0.9 to 3.3 µg/m 3 across 15 monitoring sites, with a majority of sites above the 1.3 µg/m 3 contribution threshold (and also above the 1.5 µg/m 3 contribution threshold in the final PM 2.5 Precursor Guidance), whereas the PM 2.5 responses in 2024 were all below both recommended thresholds. For a modeled 70% ammonia emission reduction, the ambient PM 2.5 responses in 2013 ranged from 3.5 to 12.4 µg/m 3 , with all monitoring sites above the 1.3 µg/m 3 threshold (and above the 1.5 µg/m 3 threshold), and the PM 2.5 responses in 2024 ranged from 1.2 to 3.0 µg/m 3 , with most sites above both recommended thresholds. For further detail, please see the EPA's PM 2.5 Precursor TSD, Table 2, and the 2018 PM 2.5 Plan, Appendix G, Tables 2, 3, 5, and 7. The State bases its ammonia precursor determination on the sensitivity analysis for the 2024 attainment year with a 30% ammonia emission reduction. These respectively reflect its assessment of research studies and the Plan's projected emission reductions, and on its assessment of available emission controls. As explained in the PM 2.5 Precursor Guidance, precursor responses may be above the recommend contribution threshold and yet not contribute significantly to levels that exceed the standard in the area. Therefore, as recommended by the EPA, the State considered additional information to consider whether its identified PM 2.5 responses constituted a significant contribution to ambient PM 2.5 in the San Joaquin Valley. The additional information included research studies, emission trends, and information to support the State's conclusion that a 30% ammonia emission reduction represented a reasonable upper bound on the ammonia emission reductions to model in estimating its contribution to ambient PM 2.5 levels. We summarize this additional information below and provide a more detailed evaluation in the EPA's PM 2.5 Precursor TSD. The State describes previous research that supports its finding that ammonium nitrate PM 2.5 formation in the San Joaquin Valley is NO X -limited rather than ammonia-limited. 105 Essentially, ammonia is so abundant that even with large ammonia emission reductions there would still be enough ammonia to combine with the available NO X to readily form particulate ammonium nitrate. Therefore, ammonia emissions reductions would lead to only small decreases in PM 2.5 concentrations. In contrast, because emissions of NO X are less abundant ( i.e., more limited relative to emissions of ammonia after normalizing for their differing molecular weights), the PM 2.5 concentrations in the atmosphere are more responsive to reductions in NO X than to reductions of ammonia. Hence, the area is considered NO X -limited. The State points to the conclusions of Lurmann et al. based on ambient measurements during the winter 2000-2001 CRPAQS (California Regional Particulate Air Quality Study) intensive field study. 106 That study found that most areas of the San Joaquin Valley were NO X -limited with respect to ammonium nitrate formation. And since that time, large additional NO X emission reductions have occurred, which would increase the degree to which ammonium nitrate formation in the San Joaquin Valley is NO X -limited. Based on more recent aircraft-borne measurements during the 2013 DISCOVER-AQ campaign, 107 the State similarly concluded that ammonium nitrate formation is NO X -limited based on the large amount of “excess ammonia,” which is defined as the amount of measured ammonia left over if all the nitrate and sulfate present were to combine with available ammonia to form particulate. 108 The CARB Staff Report describes these conclusions in more detail and lists results from multiple other recent studies with similar conclusions. 109 105 2018 PM 2.5 Plan, App. G, G-9 to G-10; CARB Staff Report, App. C, 12-15; and Attachment A to CARB's submittal letter of May 9, 2019. 106 Frederick W. Lurmann, Steven G. Brown, Michael C. McCarthy, and Paul T. Roberts, “Processes Influencing Secondary Aerosol Formation in the San Joaquin Valley during Winter,” Journal of the Air & Waste Management Association, (2006), 56:12, 1679-1693, DOI: 10.1080/10473289.2006.10464573. 107 “Deriving Information on Surface conditions from COlumn and VERtically Resolved Observations Relevant to Air Quality”, https://www.nasa.gov/mission_pages/discover-aq/index.html. 108 2018 PM 2.5 Plan, App. G, Figure 2. 109 CARB Staff Report, App. C, 12. Regarding emission trends, the CARB Staff Report presents an emission inventory-based argument on the relative insensitivity of PM 2.5 to ammonia reductions. 110 CARB compared the size of the ammonia and NO X emission inventories in tons per day, after normalizing for their differing molecular weights, and found that ammonia was roughly three times as abundant as NO X in 2013 and is projected to be about six times as abundant in 2025, due to the continuing decline in NO X emissions (while ammonia emissions are generally constant into the future). 111 While the State recognized that this is only a “first-level assessment,” it provides additional support for the State's conclusion that NO X , and not ammonia, is the limiting precursor for ammonium nitrate formation, and that the ammonium nitrate portion of ambient PM 2.5 would be expected to be relatively insensitive to ammonia emission reductions. This is also consistent with the ammonia sensitivity modeling for the San Joaquin Valley, which showed that PM 2.5 concentrations will be less sensitive to ammonia reductions as NO X emissions go down in the future ( i.e., the PM 2.5 impacts were much smaller in the 2024 future modeled case compared to the 2013 base year). 110 Id. App. C, 15. 111 Annual average ammonia emissions are projected to decrease 4.6 tpd (1.4%) from 2013 to 2024. 2018 PM 2.5 Plan, App. B, Table B-5. The State finds that NO X emissions in the San Joaquin Valley are projected to decrease by 53% from 2013 to 2024 while ammonia emissions are projected to remain relatively flat, thereby increasing the relative abundance of ammonia. 112 Based on the Plan's emission reduction projections combined with the research study conclusions, the State relies on the modeled responses for the 2024 future year, rather than the 2013 base year, stating that the future year NO X emissions are more representative of San Joaquin Valley emission conditions. 113 The State references the Draft PM 2.5 Precursor Guidance, which notes that it may be appropriate to model future conditions that are more representative of current atmospheric conditions and those conditions expected closer to the attainment date. The State concludes states that this in fact applies to the San Joaquin Valley. 114 112 2018 PM 2.5 Plan, App. G, 8-9. 113 Id. App. G, 9. 114 Id (referencing Draft PM 2.5 Precursor Guidance, 33). See also PM 2.5 Precursor Guidance, 35. With respect to the State's selection of 30% as an upper bound on the ammonia reductions to model, the State described its review of the most important ammonia source categories in the San Joaquin Valley, existing control measures that affect ammonia emissions from these sources, additional mitigation options for these sources, and information provided in the PM 2.5 Precursor Guidance about ammonia reductions achieved nationwide from 2011 to 2017. 115 The primary sources of ammonia emissions identified in the 2018 PM 2.5 Plan are: (1) Confined animal facilities (CAFs), (2) agricultural fertilizer, (3) biosolids, animal manure, and poultry litter operations, and (4) organic material composting operations. 116 CAFs are subject to District Rule 4570; biosolids, animal manure, and poultry litter operations are subject to District Rule 4565; and organic material composting operations are subject to District Rule 4566. Although these District rules explicitly apply only to VOC emissions from these sources, the State concludes that these rules also reduce ammonia emissions. Appendix C of the 2018 PM 2.5 Plan cites a number of scientific studies that address the correlation between VOC and ammonia emissions from these emission sources. 117 Based on these evaluations, the State concludes that ammonia control measures achieving even the low end of the range (30%) are not feasible for implementation in the San Joaquin Valley and that it is therefore reasonable to treat a 30% ammonia reduction as an upper bound for modeling in the precursor demonstration. 115 2018 PM 2.5 Plan, App. G, 13 and App. C, section C-25 and email dated October 18, 2019, from Laura Carr, CARB to Scott Bohning, EPA Region IX, attaching document entitled “Clarifying Information on Ammonia.” 116 2018 PM 2.5 Plan, App. C, section C-25. 117 Id. at C-314 and following. In sum, the State's sensitivity analysis presents a range of PM 2.5 responses to ammonia emission reductions depending on base year versus future year and depending on the scale of emission reductions that may be possible. The Plan provides the State's bases for finding that the sensitivity result for 2024 better represents conditions in the San Joaquin Valley than the 2013 base year and for finding a 30% ammonia reduction to be a reasonable upper bound for modeled ammonia emission reductions in assessing the ammonia contribution. Based on these analyses, the State concludes that ammonia does not contribute significantly to levels above the 2006 PM 2.5 NAAQS in the San Joaquin Valley. b. SO X For SO X , the State compared the 24-hour precursor contributions to the recommended draft contribution threshold of 1.3 µg/m 3 in the Draft PM 2.5 Precursor Guidance. For modeled SO X emission reductions of 30% and 70%, the ambient PM 2.5 responses in 2013 ranged from −1.4 to +0.5 µg/m 3 across 15 monitoring sites, which all fall below the 1.3 µg/m 3 draft contribution threshold, and hence also below the contribution threshold of 1.5 µg/m 3 in the final version of the PM 2.5 Precursor Guidance. The response was below zero at most monitoring sites, indicating an increase, rather than decrease, in ambient PM 2.5 in response to SO X emission reductions ( i.e., a disbenefit). Only the Stockton and Manteca sites had slightly positive responses to 30 and 70% emission reductions, and the Tranquillity site also had a slightly positive response only to a 30% reduction. For 2024, the response ranged from −0.3 µg/m 3 to +0.3 µg/m 3 ; these are also all below the contribution threshold, with most sites showing a disbenefit from SO X reductions. For further detail, please see EPA's PM 2.5 Precursor TSD, Table 3, and the 2018 PM 2.5 Plan, Appendix G, Tables 8 and 9. CARB also included additional information regarding emission trends and an evaluation of the SO X emission reduction disbenefit. We summarize this additional information below and provide a more detailed evaluation in the EPA's PM 2.5 Precursor TSD. In terms of emission trends, the State found that SO X emissions decreased from 2013 to 2014 and then very gradually rise to 8.0 tpd in 2024. 118 On the basis of SO X emissions being very similar in 2020 and 2024 (7.8 tpd and 8.0 tpd, respectively), the State concluded that the 2020 and 2024 sensitivity results were redundant. Comparing the ambient responses in 2013 and 2024, the State found that the responses were slightly less negative or, for a small number of sites, slightly more positive in 2024, but still no more than 0.6 µg/m 3 in response to a 70% SO X emission reduction. This supports the State's conclusion as to the overall disbenefit of reducing SO X emissions. 118 2018 PM 2.5 Plan, App. G, Figure 4. To explain the SO X emission reduction disbenefit, CARB refers to the non-linearity of inorganic aerosol thermodynamics, as described in a study by West et al. 119 That paper discusses how, under certain conditions, reducing SO X could free ammonia to combine with nitrate, increasing overall PM 2.5 mass. To investigate this issue further, CARB conducted simulations with the ISORROPIA inorganic aerosol thermodynamic equilibrium model used within the Community Multiscale Air Quality (CMAQ) model and provided clarifications to the EPA. 120 In essence, CARB states that for some conditions typical of San Joaquin Valley, ISORROPIA switches to a different chemical regime in which the disbenefit occurs. CARB states that it is not known how well this model behavior reflects the actual atmosphere, but CARB accepts the results because is it a well-known and widely used chemical model. 119 2018 PM 2.5 Plan, App. K, section 5.6 (“PM 2.5 Precursor Sensitivity Analysis”); and West, J.J., Ansari, A.S., Pandis, S.N., 1999, Marginal PM 2.5 : Nonlinear aerosol mass response to sulfate reductions in the eastern United States, Journal of the Air & Waste Management Association, 49, 1415-1424. https://doi.org/10.1080/10473289.1999.10463973. 120 CARB's June 2019 Precursor Clarification. Based on the small and mostly negative modeled response of ambient PM 2.5 to SO X emission reductions, and based on its scientific understanding of sulfate interactions with other molecules in the air, the State concludes that SO X does not contribute significantly to ambient PM 2.5 levels that exceed the 2006 PM 2.5 NAAQS in the San Joaquin Valley. c. VOC For VOC, CARB compared the 24-hour precursor contributions to the EPA's recommended draft contribution threshold of 1.3 µg/m 3 . For a modeled 30% VOC emission reduction, the ambient PM 2.5 responses in 2013 ranged from 0.1 to 1.9 µg/m 3 across 15 monitoring sites, with two sites above the 1.3 µg/m 3 draft contribution threshold. 121 The PM 2.5 responses to a 70% VOC emission reduction in 2013 ranged from 0.2 µg/m 3 to 4.8 µg/m 3 , including responses above the 1.3 µg/m 3 draft contribution threshold at a majority of sites. For a modeled 30% VOC emission reduction, the ambient PM 2.5 responses in 2024 ranged from −0.4 to 0.0 µg/m 3 , with all monitoring sites below the 1.3 µg/m 3 draft contribution threshold, and hence also below the contribution threshold of 1.5 µg/m 3 that was finalized the PM 2.5 SIP Requirements Rule. The PM 2.5 responses to a 70% VOC emission reduction in 2024 ranged from −1.0 to 0.0 µg/m 3 , with all monitoring sites below the 1.3 µg/m 3 draft contribution threshold. In other words, CARB models a decrease in ambient PM 2.5 levels in 2013 in response to either a 30% or 70% VOC emission reduction, whereas CARB models an increase in ambient PM 2.5 levels in 2024 in response to either a 30% or 70% reduction in VOC emissions, i.e., a disbenefit. For further detail, please see EPA's PM 2.5 Precursor TSD, Table 4, and the 2018 PM 2.5 Plan, Appendix G, Tables 10, 11, 13, and 15. 121 We note that one site (Visalia) has a modeled response above the EPA's final recommended contribution threshold of 1.5 µg/m 3 and one additional site (Bakersfield-California Avenue) has a modeled response below the 1.5 µg/m 3 threshold but above the EPA's draft threshold of 1.3 µg/m 3 . CARB then considered additional information to consider whether these PM 2.5 responses constituted a significant contribution to ambient PM 2.5 in the San Joaquin Valley, including emission trends and an assessment of the modeled disbenefit of VOC emission reductions in 2024. CARB bases its precursor determination on sensitivity analysis for the 2024 attainment year, reflecting its assessment of the Plan's projected emission reductions. We summarize this additional information below and present greater detail in the EPA's PM 2.5 Precursor TSD. Regarding emission trends, CARB found that VOC emissions would decrease approximately 30 tpd (or 9%) from 2013 to 2024. 122 The State concludes that the formation of ambient PM 2.5 from VOC may therefore differ in base and future years and that the sensitivity analysis for 2013 is not representative of current or future conditions. 122 2018 PM 2.5 Plan, App. G, 19 and Figure 5. CARB explained the modeled disbenefit of VOC reductions as follows: Emissions of VOC and NO X react in the atmosphere to form organic nitrate species, such as peroxyacetyl nitrate (PAN), meaning that some portion of the NO X emissions is not available to react with ammonia to form ammonium nitrate. In other words, VOC emissions are a “sink” for NO X emissions. Reducing VOC emissions therefore reduces the formation of organic nitrates, so the sink is smaller and nitrate molecules are freed to react with ammonia to form particulate ammonium nitrate. 123 The State further explored the VOC disbenefit based on a 2016 CARB modeling assessment provided in Appendix A (“Air Quality Modeling”) of the “2016 Moderate Area Plan for the 2012 PM 2.5 Standard” for the San Joaquin Valley (“2016 PM 2.5 Plan”), which CARB submitted to the EPA as a SIP revision on May 10, 2019. 124 123 2018 PM 2.5 Plan, App. K, 72 (citing Meng, Z., D. Dabdub, D., Seinfeld, J.H., Chemical Coupling Between Atmospheric Ozone and Particulate Matter, Science 277, 116 (1997). DOI: 10.1126/science.277.5322.116). 124 2016 PM 2.5 Plan, App. A, A-57. See also 2018 PM 2.5 Plan, App. K, section 5.6 (“PM 2.5 Precursor Sensitivity Analysis”), 71-72. Based on its sensitivity-based analysis of VOC emission reductions in the 2013 base and 2024 future years, VOC emission trends, and the scientific understanding of atmospheric VOC chemistry in the San Joaquin Valley, CARB concludes that VOC emissions do not contribute significantly to PM 2.5 levels that exceed the 2006 PM 2.5 NAAQS in the San Joaquin Valley. 3. EPA's Evaluation and Proposed Action The EPA has evaluated the State's precursor demonstration consistent with the PM 2.5 SIP Requirements Rule and the recommendations in the PM 2.5 Precursor Guidance. Based on this evaluation, the EPA agrees that NO X emissions contribute significantly to ambient PM 2.5 levels that exceed the 2006 PM 2.5 NAAQS in the San Joaquin Valley and that NO X emission sources, therefore, remain subject to control requirements under subparts 1 and 4 of part D, title I of the Act. For the reasons provided below, the EPA proposes to approve the State's demonstration that ammonia, SO X , and VOC emissions do not contribute significantly to ambient PM 2.5 levels that exceed the 2006 PM 2.5 NAAQS in the San Joaquin Valley. Regarding the State's analytical approach, the EPA finds that the State based its analyses on the latest available data and studies concerning ambient PM 2.5 formation in the San Joaquin Valley from precursor emissions. Regarding the required concentration-based analysis, the EPA finds that the State assessed the absolute annual average contribution of each precursor in ambient PM 2.5 ( i.e., in 2015). On the basis of the absolute concentrations being well above the EPA's recommended contribution thresholds for both the 24-hour and annual average NAAQS, the State proceeded with its sensitivity-based analysis, which is an acceptable progression of analyses under the PM 2.5 SIP Requirements Rule. 125 125 For further discussion of the EPA's evaluation of the State's concentration-based analysis, see EPA's PM 2.5 Precursor TSD, sections entitled “Concentration-based analysis” within the EPA's evaluation for each of ammonia, SO X , and VOC. With respect to the sensitivity-based analysis, we find that the State performed its analyses in a straightforward application of the EPA's recommended approach— i.e., for each modeled year and percent precursor emission reduction, the State estimated the ambient PM 2.5 response using the procedure recommended in the PM 2.5 Precursor Guidance, and compared the result to the recommended contribution threshold. The EPA also finds that the performance of the photochemical model was adequate for use in estimating the ambient PM 2.5 responses, as discussed in section J (“Air Quality Model Performance”) of the EPA's “Technical Support Document, EPA Evaluation of Air Quality Modeling, San Joaquin Valley PM 2.5 Plan for the 2006 PM 2.5 NAAQS,” February 2020 (“EPA's Modeling TSD”). The State considered the EPA's recommended range of emission reductions (30% to 70%) for the 2013 base year, an interim year (2020), and the projected 2024 attainment year for the 2006 PM 2.5 NAAQS, and quantified the estimated response of ambient PM 2.5 concentrations to precursor emission changes for the first time in a PM 2.5 SIP submission for the San Joaquin Valley. The EPA finds that such quantification and CARB's consideration of additional information provide an informed basis on which to make a determination as to whether ammonia, SO X , and VOC do or do not contribute significantly to ambient PM 2.5 levels that exceed the 2006 PM 2.5 NAAQS in the San Joaquin Valley. Therefore, we turn to our evaluation of the State's determination for each of these three precursor pollutants. a. Ammonia For ammonia, as detailed above, CARB estimated the ambient PM 2.5 response to both a 30% and a 70% emission reduction. We find that it was appropriate for the State to consider additional information to interpret those results to determine whether the ammonia contribution is significant. We have evaluated CARB's determination that the projected 2024 attainment year is more representative of conditions in the San Joaquin Valley for sensitivity-based analyses and that 30% is a reasonable upper bound for ammonia emission reductions to assess the precursor contribution, as discussed below. The State provided ample information from scientific studies based on ambient measurements to help assess the estimated sensitivity of ambient PM 2.5 to ammonia reductions. Conclusions based on ambient data are particularly relevant because they provide direct evidence of the chemical state of the atmosphere, and are not dependent on modeled estimates of emissions or ambient PM 2.5 concentrations. Measurements represent the “real world” result of the pollutants' differing geographic distributions, the various meteorological and chemical factors influencing their conversion to particulate, and their removal from the atmosphere by deposition and other processes. The observed abundance of ammonia relative to nitric acid, and the positive amount of chemically excess ammonia, both provide strong evidence that ammonia is not the limiting pollutant for particulate ammonium nitrate formation. They also support the State's conclusion that PM 2.5 is likely to be insensitive to ammonia emission reductions. We note that the model response to precursor reductions may be unrealistically large. There is some evidence that ammonia emissions may be underestimated based on direct measurements of ammonia emissions flux during two measurement campaigns, as discussed in the EPA's PM 2.5 Precursor TSD. If ammonia emissions were higher in the modeling, then ammonia would be more abundant relative to nitrate and particulate nitrate formation would be more NO X -limited, and less sensitive to ammonia reductions. This would make the model response more consistent with the ambient measurement studies, which suggest a very low sensitivity to ammonia. The ammonia contribution to PM 2.5 levels above the standard may therefore be less than estimated by the State modeling. The 2024 year modeling incorporates lower NO X emissions and so has a larger abundance of ammonia relative to nitrate, more similar to the studies' ambient measurements. The 2024 response to ammonia reductions may thus be more reliable than the 2013 and 2020 responses, and may be more representative of current atmospheric conditions despite its use of emission projections for a future year. The relative sizes of the ammonia and NO X precursor emission inventories after accounting for their differing molecular weights are a rough indicator of which is the limiting pollutant for production of ammonium nitrate, because it forms from a one-to-one ratio of molecules derived from each precursor ( i.e., one ammonium nitrate forms from one ammonium and one nitrate). However, unlike measurements and photochemical modeling, a simple emissions ratio does not account for the various processes mentioned above; it just assumes all the emitted molecules find each other and fully react. The State found ammonia to be roughly three times as abundant as NO X currently after accounting for their differing molecular weights, and even more so in the future. The EPA repeated the exercise to account for SO X as well, and found that the ratio of total ammonia to that needed to react with both nitrate and sulfate ranged from 2.7 in 2013 to 5.6 in 2028. These are about the same as the CARB NO X -only results, because SO X emissions are very small relative to those of NO X and ammonia ( e.g., in 2013, winter daily emissions were 8.4 tpd SO X , vs. 300.5 tpd for NO X and 309.8 tpd for ammonia). 126 These observations support the State's finding that PM 2.5 is expected to be relatively insensitive to ammonia reductions, though it is not definitive. 126 2018 PM 2.5 Plan, App. B, Tables B-2, B-3, and B-4. The State also concludes that there are continuing large decreases in NO X emissions in the San Joaquin Valley from 2013 to 2024, including 53% reductions from baseline measures and 10-11% reductions from additional new measures, while ammonia emissions are projected to remain roughly constant ( i.e., decreasing 1-2%). 127 In conjunction with the ambient evidence that ammonia is already chemically overabundant relative to NO X in the San Joaquin Valley, this shows that in the future the overabundance will become even greater, and thus ambient PM 2.5 would be even less responsive to ammonia reductions. This adds conservatism to the State's conclusions about ammonia insensitivity based on the scientific studies. 127 For further discussion of the SJV PM 2.5 Plan's control strategy, see section IV.D.4.b of this preamble. While the base year for an attainment plan for a given nonattainment area is generally more representative of current conditions, the EPA believes that either a base year or a future year may be used for modeling an ambient PM 2.5 response to precursor emission reductions, provided the state explains how the choice of analysis year and associated assumptions are appropriate. 128 The State relied on 2024 model responses mainly on the grounds that large NO X emissions reductions will occur during 2013-2024, so that the 2024 results will continue to be representative, unlike earlier model years. These reductions are the result of regulations put in place by past air quality planning decisions, and they will occur regardless of decisions about additional NO X or ammonia controls in the SJV PM 2.5 Plan. In assessing the effect of potential ammonia reductions, the EPA believes it is reasonable to account for these NO X reductions and the effect that ammonia reductions would have in the attainment year and after. In addition, as noted above, the greater abundance of ammonia relative to NO X in the 2024 year modeling is more consistent with recent ambient measurements, and may make the 2024 responses more representative of current atmospheric conditions than the other model years for assessing sensitivity to ammonia reductions. Therefore, in consideration of the scientific studies and emission trends, including the projected large amount of NO X emission reductions through the attainment period, the EPA agrees that the modeled 2024 year is acceptable and representative of conditions in the San Joaquin Valley. 128 PM 2.5 Precursor Guidance, 35-36. In the context of interpreting the full set of modeling results for ammonia emissions reductions, the EPA also considered the State's conclusion that the absence of available ammonia controls for sources in the San Joaquin Valley supports its decision to treat a 30% reduction as a reasonable upper bound on the ammonia emission reductions to model in estimating the precursor contribution. As the State correctly notes, the 30% to 70% range recommended by the EPA is based on historical NO X and SO X emission reductions, and changes in ammonia emission levels nationally from 2011 to 2017 ranged from a 9% decrease to a 6% increase. 129 The State's descriptions of both the past research relied upon to develop existing rules that apply to ammonia emission sources and ongoing research show that it has considered the availability of ammonia controls both in the past and in the present context, and that the State has a basis for its conclusion that 30% is a reasonable upper bound on achievable reductions for ammonia. 129 PM 2.5 Precursor Guidance, Table 2, page 30. In sum, we find that the State quantified the sensitivity of ambient PM 2.5 levels to reductions in ammonia using appropriate modeling techniques, which performed well, and that the State's choice of 2024 as the reference point for purposes of evaluating the sensitivity of ambient PM 2.5 levels to ammonia emission reductions is well-supported. We also find that the State adequately documented its bases for using a 30% reduction in ammonia emissions as an upper bound in the modeling to assess ambient sensitivity to ammonia emission reductions. Based on all of these considerations, the EPA proposes to approve the State's demonstration that ammonia emissions do not contribute significantly to ambient PM 2.5 levels that exceed the 2006 PM 2.5 NAAQS in the San Joaquin Valley. b. SO X For SO X , the State found that the ambient PM 2.5 responses to SO X emission reductions were below the EPA's recommended contribution threshold of 1.3 µg/m 3 in the Draft PM 2.5 Precursor Guidance (and below the EPA's recommended threshold of 1.5 µg/m 3 in the (final) PM 2.5 Precursor Guidance) and, indeed, that for most sites there would be an increase in ambient PM 2.5 levels in response to such reductions ( i.e., a disbenefit). The EPA has evaluated the State's determination as to this disbenefit and the State's resulting conclusion as to the precursor's significance. Because the results of the sensitivity analysis were all below the EPA's recommended 24-hour contribution thresholds at both the 30% and 70% emission reductions, and in both the 2013 base year and 2024 attainment year, it is not necessary to distinguish between the timing and scale of emission reductions with respect to the response of ambient PM 2.5 levels, as in the ammonia evaluation where the results diverged according to scale and timing of modeled emission reductions. The EPA's PM 2.5 Precursor TSD contains additional detail on the EPA's evaluation of SO X as a PM 2.5 precursor, including the unexpected disbenefit of reducing SO X emissions. Accordingly, we find that the State's decision to rely on the 2013 sensitivity modeling results for a 30% SO X reduction is acceptable. Therefore, on the basis of the modeled ambient PM 2.5 response to both a 30% and 70% reduction in SO X emissions in 2013, and the facts and circumstances of the area, the EPA proposes to approve the State's demonstration that SO X emissions do not contribute significantly to ambient PM 2.5 levels that exceed the 2006 PM 2.5 NAAQS in the San Joaquin Valley. c. VOC For VOC, the State found that the ambient PM 2.5 response to VOC emission reductions were generally below the EPA's recommended contribution threshold of 1.3 µg/m 3 in the Draft PM 2.5 Precursor Guidance (and below the EPA's recommended threshold of 1.5 µg/m 3 in the final PM 2.5 Precursor Guidance), and often predicted an increase in ambient PM 2.5 levels in response to such reductions ( i.e., a disbenefit), except for a 70% emission reduction for the 2013 base year, where the State predicted the ambient PM 2.5 response to be above both recommended thresholds at a majority of sites. The EPA has evaluated and agrees with the State's determination that the projected 2024 attainment year is more representative of conditions in the San Joaquin Valley for sensitivity-based analyses and that VOC reductions in 2024 would mostly result in a disbenefit to ambient PM 2.5 levels, as well as the State's resulting conclusion as to whether VOC's contribution is significant. Regarding emission trends, the EPA agrees that the 9% VOC emissions decrease from 2013 to 2024 favors reliance on the 2024 modeling results. Furthermore, there is a large decrease in NO X emissions over this period, as discussed in the EPA's evaluation of ammonia in section IV.B.3.a of this preamble, which affects the atmospheric chemistry with respect to ambient PM 2.5 formation from VOC emissions. The 9% VOC emission reductions and the vast majority of NO X emissions will result from baseline measures that are projected to occur, even absent any further action by the State. We therefore find it reasonable to rely on future year 2024 modeled responses to VOC reductions. The EPA also finds that the State provided a reasonable explanation for the VOC reduction disbenefit and evidence that it occurs in the San Joaquin Valley. For all of these reasons, we propose to approve the State's demonstration that VOC emissions do not contribute significantly to ambient PM 2.5 levels that exceed the 2006 PM 2.5 NAAQS in the San Joaquin Valley. C. Best Available Control Measures and Most Stringent Measures 1. Statutory and Regulatory Requirements Section 189(b)(1)(B) of the Act requires for any serious PM 2.5 nonattainment area that the state submit provisions to assure that the best available control measures (BACM) for the control of PM 2.5 and PM 2.5 precursors shall be implemented no later than four years after the date the area is reclassified as a serious area. The EPA has defined BACM in the PM 2.5 SIP Requirements Rule to mean “any technologically and economically feasible control measure that can be implemented in whole or in part within 4 years after the date of reclassification of a Moderate PM 2.5 nonattainment area to Serious and that generally can achieve greater permanent and enforceable emissions reductions in direct PM 2.5 emissions and/or emissions of PM 2.5 plan precursors from sources in the area than can be achieved through the implementation of RACM on the same source(s). BACM includes best available control technology (BACT).” 130 130 40 CFR 51.1000 (definitions). In longstanding guidance, the EPA has similarly defined BACM to mean, “among other things, the maximum degree of emissions reduction achievable for a source or source category, which is determined on a case-by-case basis considering energy, environmental, and economic impacts.” General Preamble Addendum, 42010, 42013. The EPA generally considers BACM a control level that goes beyond existing RACM-level controls, for example by expanding the use of RACM controls or by requiring preventative measures instead of remediation. 131 Indeed, as implementation of BACM and BACT is required when a Moderate nonattainment area is reclassified as Serious due to its inability to attain the NAAQS through implementation of “reasonable” measures, it is logical that “best” control measures should represent a more stringent and potentially more costly level of control. 132 If RACM and RACT level controls of emissions have been insufficient to reach attainment, the CAA contemplates the implementation of more stringent controls, controls on more sources, or other adjustments to the control strategy necessary to attain the NAAQS in the area. 131 81 FR 58010, 58081 and General Preamble Addendum, 42011, 42013. 132 Id. and General Preamble Addendum, 42009-42010. Consistent with longstanding guidance provided in the General Preamble Addendum, the preamble to the PM 2.5 SIP Requirements Rule discusses the following steps for determining BACM and BACT: (1) Develop a comprehensive emission inventory of the sources of PM 2.5 and PM 2.5 precursors; (2) Identify potential control measures; (3) Determine whether an available control measure or technology is technologically feasible; (4) Determine whether an available control measure or technology is economically feasible; and (5) Determine the earliest date by which a control measure or technology can be implemented in whole or in part. 133 133 81 FR 58010, 58083-58085. The EPA allows consideration of factors such as physical plant layout, energy requirements, needed infrastructure, and workforce type and habits when considering technological feasibility. For purposes of evaluating economic feasibility, the EPA allows consideration of factors such as the capital costs, operating and maintenance costs, and cost effectiveness ( i.e., cost per ton of pollutant reduced by a measure or technology) associated with the measure or control. 134 134 40 CFR 51.1010(a)(3) and 81 FR 58010, 58041-58042. Once these analyses are complete, the state must use this information to develop enforceable control measures and submit them to the EPA for evaluation as SIP provisions to meet the basic requirements of CAA section 110 and any other applicable substantive provisions of the Act. The EPA is using these steps as guidelines in the evaluation of the BACM and BACT measures and related analyses in the SJV PM 2.5 Plan. Because the EPA reclassified the San Joaquin Valley as Serious nonattainment for the 2006 PM 2.5 NAAQS effective February 19, 2016, 135 the date four years after reclassification is February 19, 2020. In this case, however, the Serious area attainment date for the 2006 PM 2.5 NAAQS in the San Joaquin Valley under section 188(c) is no later than December 31, 2019, and to qualify for an extension of this date under section 188(e), the state must, among other things, demonstrate that implementation of BACM and BACT for relevant source categories will not bring the area into attainment by this date. Given these circumstances, the EPA is evaluating the Plan's control strategy for implementation of BACM and BACT as expeditiously as practicable and no later than December 31, 2019. 136 135 81 FR 2993. 136 CAA section 189(b)(1)(B) establishes an outermost deadline (“no later than four years after the date the area is reclassified”) and does not preclude an earlier implementation deadline for BACM where necessary to satisfy the attainment requirements of the Act. In addition, before the EPA may extend the attainment date for a Serious nonattainment area under CAA section 188(e), the state must, among other things, demonstrate to the satisfaction of the Administrator that the plan for the area includes the most stringent measures (MSM) that are included in the implementation plan of any state or are achieved in practice in any state, and can feasibly be implemented in the area. The state must implement MSM as expeditiously as practicable and no later than the beginning of the year containing the attainment date identified by the state in its extension request, i.e., in this case, by January 1, 2024, because the State is seeking an extension of the attainment date to December 31, 2024, under section 188(e). 137 Section III.B of this preamble contains a more detailed discussion of the MSM requirement in CAA section 188(e). 137 40 CFR 51.1011(b)(5) (requiring implementation of all control measures needed for attainment as expeditiously as practicable and no later than the beginning of the year containing the applicable attainment date). 2. Summary of State's Submission As discussed in section IV.A of this proposed rule, Appendix B of the 2018 PM 2.5 Plan contains the planning inventories for direct PM 2.5 and all PM 2.5 precursors (NO X, SO X, VOC, and ammonia) for the San Joaquin Valley nonattainment area together with documentation to support these inventories. Each inventory includes emissions from stationary, area, on-road, and non-road emission sources, and the State specifically identifies the condensable component of direct PM 2.5 for relevant stationary and area source categories. As discussed in section IV.B of this preamble, the State's analysis indicates that the Plan should control emissions of PM 2.5 and NO X in order to reach attainment. Accordingly, the Plan evaluates potential controls for those pollutants in the analysis of what is necessary to meet the BACM (including BACT) and MSM requirements. For stationary and area sources, the District identifies the sources of direct PM 2.5 and NO X in the San Joaquin Valley that are subject to District emission control measures and provides its evaluation of these regulations for compliance with BACM and MSM requirements in Appendix C of the 2018 PM 2.5 Plan. As part of its process for identifying candidate BACM and MSM and considering the technical and economic feasibility of additional control measures, the District reviewed the EPA's guidance documents on BACM, additional guidance documents on control measures for direct PM 2.5 and NO X emission sources, and control measures implemented in other ozone and PM 2.5 nonattainment areas in California and other states. 138 138 2018 PM 2.5 Plan, Chapter 4, section 4.3.1. For mobile sources, CARB identifies the sources of direct PM 2.5 and NO X in the San Joaquin Valley that are subject to the State's emission control measures and provides its evaluation of these regulations for compliance with BACM and MSM requirements in Appendix D of the 2018 PM 2.5 Plan. Appendix D describes CARB's process for determining BACM and MSM, including identification of the sources of direct PM 2.5 and NO X in the San Joaquin Valley, identification of potential control measures for such sources, assessment of the stringency and feasibility of the potential control measures, and adoption and implementation of feasible control measures. 139 CARB further discusses its current mobile source control program and additional mobile source measures in the Valley State SIP Strategy. Appendix D of the 2018 PM 2.5 Plan also describes the current efforts of the eight local jurisdiction metropolitan planning organizations (MPOs) to implement cost-effective transportation control measures (TCMs) in the San Joaquin Valley. 140 139 Id. at App. D, Ch. II. 140 Id. at App. D, D-127 and D-128. 3. EPA's Evaluation and Proposed Action As discussed in sections III.B and IV.D of this preamble, the EPA has established a process for evaluating potential BACM (including BACT) in serious area plans and a similar process for evaluating MSM. Because of the substantial overlap in the source categories and controls evaluated for BACM and those evaluated for MSM, we present our evaluation of the SJV PM 2.5 Plan's provisions for including MSM alongside our evaluation of the Plan's provisions for implementing BACM and BACT for each identified source category. The first step in determining BACM and MSM is to develop a comprehensive emissions inventory of the sources of direct PM 2.5 and relevant PM 2.5 precursors that can be used with modeling to determine the effects of these sources on ambient PM 2.5 levels. Based on our review of the emission inventories provided in Appendix B of the 2018 PM 2.5 Plan and the State's and District's identification of the sources subject to control in Appendix C and Appendix D, the EPA is proposing to find that the Plan appropriately identifies all sources of direct PM 2.5 and NO X that are subject to evaluation for potential control consistent with the requirements of subpart 4 of part D, title I of the Act. The remaining steps are to identify potential control measures for each source category, determine whether available control measures or technologies are technologically and economically feasible for implementation in the area, and determine the earliest date by which those control measures or technologies found to be feasible can be implemented, in whole or in part. 141 141 81 FR 58010, 58083-58085. The EPA's recommended steps for a BACM demonstration are substantively similar to the required steps for an MSM demonstration in 40 CFR 51.1010(b). We discuss below key components of the BACM and MSM evaluations provided by the District, CARB, and the local jurisdiction MPOs in the SJV PM 2.5 Plan in accordance with these steps. We provide a more detailed evaluation of many of the District's control measures for stationary and area sources in the EPA's “Technical Support Document, EPA Evaluation of BACM/MSM, San Joaquin Valley PM 2.5 Plan for the 2006 PM 2.5 NAAQS,” February 2020 (“EPA's BACM/MSM TSD”), together with recommendations for possible future improvements to these rules. a. District Measures for Stationary and Area Sources Open Burning SJVUAPCD Rule 4103 (“Open Burning”), as amended April 15, 2010, is designed to minimize impacts of smoke and other air pollutants from open burning of agricultural waste and other materials. 142 The rule rest [Text truncated at 120,000 characters. The full text is on the page linked above.] --- Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/fr%3A2020-05914. Public record. Not legal advice.