Clean Air Plans; California; San Joaquin Valley Moderate Area Plan and Reclassification as Serious Nonattainment for the 2012 PM2.5 NAAQS; Contingency Measures for the 2006 PM2.5 NAAQS

Federal RegisterSep 1, 2021

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 52 and 81

[EPA-R09-OAR-2021-0543; FRL-8846-01-R9]

Clean Air Plans; California; San Joaquin Valley Moderate Area Plan and Reclassification as Serious Nonattainment for the 2012 PM

2.5

NAAQS; Contingency Measures for the 2006 PM

2.5

NAAQS

AGENCY:

Environmental Protection Agency (EPA).

ACTION:

Proposed rule.

SUMMARY:

The Environmental Protection Agency (EPA) proposes to take action on portions of four state implementation plan (SIP) revisions submitted by California to address Clean Air Act (CAA or “Act”) requirements for the 2012 fine particulate matter (PM

2.5

) national ambient air quality standards (NAAQS or “standards”) and for the 2006 PM

2.5

NAAQS in the San Joaquin Valley (SJV) PM

2.5

nonattainment area. Specifically, the EPA proposes to approve all but the contingency measure element of the submitted Moderate area plan for the 2012 PM

2.5

NAAQS, as updated by the submitted Serious area plan and related Valley State SIP Strategy, as meeting all applicable Moderate area plan requirements for the 2012 PM

2.5

NAAQS and to approve 2022 motor vehicle emissions budgets for use in transportation conformity analyses for the 2012 PM

2.5

NAAQS. The EPA proposes to disapprove the contingency measure element with respect to the “Moderate” area requirements for the 2012 PM

2.5

NAAQS. The EPA also proposes to reclassify the SJV PM

2.5

nonattainment area, including reservation areas of Indian country and any other area of Indian country within it where the EPA or a tribe has demonstrated that the tribe has jurisdiction, as a “Serious” nonattainment area for the 2012 PM

2.5

NAAQS based on the EPA's determination that the area cannot practicably attain the standard by the applicable Moderate area attainment date of December 31, 2021. Upon final reclassification of the SJV as a Serious area for this NAAQS, California would be required to submit a Serious area plan for the area that includes a demonstration of attainment by the applicable Serious area attainment date, which is no later than December 31, 2025, or by the most expeditious alternative date practicable. However, we note that California has already submitted such Serious area plan that the EPA will address in a separate rulemaking. Lastly, the EPA is proposing to disapprove the contingency measure element in the Serious area plan for the 2006 PM

2.5

NAAQS.

DATES:

Any comments on this proposal must be received by October 1, 2021.

ADDRESSES:

Submit your comments, identified by Docket ID No. EPA-R09-OAR-2021-0543 at

https://www.regulations.gov,

or via email to

mays.rory@epa.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

. For either manner of submission, 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 (

e.g.,

audio or video) must be accompanied by a written comment. The written comment is considered the official comment and should include discussion of all points you wish to make. The EPA will generally not consider comments or comment contents located outside of the primary submission (

i.e.,

on the web, cloud, or other file sharing system). For additional submission methods, please contact the person identified in the

FOR FURTHER INFORMATION CONTACT

section. For the full EPA public comment policy, information about CBI or multimedia submissions, and general guidance on making effective comments, please visit

https://www.epa.gov/dockets/commenting-epa-dockets.

If you need assistance in a language other than English or if you are a person with disabilities who needs a reasonable accommodation at no cost to you, please contact the person identified in the

FOR FURTHER INFORMATION CONTACT

section.

FOR FURTHER INFORMATION CONTACT:

Rory Mays, Air Planning Office (AIR-2), EPA Region IX, by phone at (415) 972-3227 or email at

mays.rory@epa.gov.

SUPPLEMENTARY INFORMATION:

Throughout this document, “we,” “us,” or “our” refer to the EPA.

Table of Contents

I. Background for Proposed Action

II. Summary of San Joaquin Valley 2016 and 2018 PM

2.5

Plans

A. 2016 PM

2.5

Plan Summary

B. 2018 PM

2.5

Plan Summary

C. Procedural Requirements for SIPs and SIP Revisions

III. Clean Air Act Requirements for Moderate PM

2.5

Nonattainment Area Plans

IV. Review of San Joaquin Valley Plans for Moderate Area Requirements

A. Emissions Inventory

B. PM

2.5

Precursors

C. Air Quality Modeling

D. Reasonably Available Control Measures and Control Strategy

E. Nonattainment New Source Review Requirements Under CAA Section 189(e)

F. Demonstration That Attainment by Moderate Area Attainment Date Is Impracticable

G. Reasonable Further Progress and Quantitative Milestones

H. Contingency Measures

I. Motor Vehicle Emissions Budgets

V. Reclassification as Serious Nonattainment and Serious Area SIP Requirements

A. Reclassification as Serious and Applicable Attainment Date

B. Clean Air Act Requirements for Serious Area Plans

C. Statutory Deadline for Submission of Serious Area Plan

VI. Reclassification of Areas of Indian Country

VII. Review of Contingency Measure Element for the 2006 PM

2.5

NAAQS

A. Requirements for Contingency Measures

B. Summary of State's Contingency Measure Element for 2006 PM

2.5

NAAQS

C. EPA Evaluation and Proposed Action

VIII. Summary of Proposed Actions and Request for Public Comment

IX. Statutory and Executive Order Reviews

I. Background for Proposed Action

On January 15, 2013, the EPA strengthened the primary annual NAAQS for particulate matter with a diameter of 2.5 microns or less (PM

2.5

) by lowering the level from 15.0 micrograms per cubic meter (µg/m

) to 12.0 µg/m

(“2012 PM

2.5

NAAQS”).

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.

78 FR 3086 and 40 CFR 50.18. The EPA first established NAAQS for PM

2.5

on July 18, 1997 (62 FR 38652), including annual standards of 15.0 µg/m

based on a 3-year average of annual mean concentrations and 24-hour (daily) standards of 65 µg/m

based on a 3-year average of 98th percentile 24-hour concentrations (40 CFR 50.7) (“1997 PM

2.5

NAAQS”). In addition, on October 17, 2006, the EPA strengthened the 24-hour (daily) NAAQS for PM

2.5

by lowering the level from 65 µg/m

to 35 µg/m

(“2006 PM

2.5

NAAQS”). 71 FR 61144 and 40 CFR 50.13. Unless otherwise noted, all references to the PM

2.5

standards in this notice are to the 2012 annual NAAQS of 12.0 µg/m

codified at 40 CFR 50.18.

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. Individuals particularly sensitive to PM

2.5

exposure include older adults, people with heart and lung disease, and children.

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 (“secondary PM

2.5

”) as a result of various chemical reactions among precursor pollutants such as nitrogen oxides (NO

), sulfur oxides (SO

), volatile organic compounds (VOC), and ammonia (NH

78 FR 3086, 3088.

EPA, Air Quality Criteria for Particulate Matter, No. EPA/600/P-99/002aF and EPA/600/P-99/002bF, October 2004.

Following promulgation of a new or revised NAAQS, the EPA is required by CAA section 107(d) to designate areas throughout the nation as attaining or not attaining the NAAQS. Under subpart 4 of part D of title I of the CAA and applicable implementing regulations, the EPA designates areas found to be violating the PM

2.5

NAAQS, and areas with emissions that contribute to such violations, as nonattainment and classifies them initially as Moderate.

States with Moderate areas have to attain the NAAQS as expeditiously as practicable, but not later than the end of the sixth calendar year after the date of designation.

The EPA reclassifies as Serious those Moderate areas that cannot practicably attain the NAAQS by the latest statutory attainment date and those areas that fail to attain the NAAQS by the applicable attainment date. States with Serious areas are subject to more stringent SIP revision requirements and must attain the NAAQS as expeditiously as practicable, but not later than the end of the tenth calendar year after designation.

CAA section 188(a) and 40 CFR 51.1002(a).

CAA section 188(c)(1) and 40 CFR 51.1004(a)(1)(i).

On January 15, 2015, the EPA designated and classified the SJV as Moderate nonattainment for the 2012 PM

2.5

NAAQS.

With respect to the 1997 PM

2.5

NAAQS and the 2006 PM

2.5

NAAQS, the SJV is designated nonattainment and is classified as Serious.

The SJV 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.

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. Under State law, 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 these plans. Authority for regulating sources under state jurisdiction in the SJV 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 and some categories of consumer products.

80 FR 2206 (codified at 40 CFR 81.305).

See the tables of area designations for the 1997 and 2006 PM

2.5

NAAQS in 40 CFR 81.305.

For a precise description of the geographic boundaries of the SJV PM

2.5

nonattainment area, see 40 CFR 81.305.

States with areas designated as nonattainment are required to submit SIP revisions that address various requirements, including the requirement to demonstrate attainment of the NAAQS as expeditiously as practicable but no later than the maximum attainment date established in the CAA or EPA's implementing regulations. However, states with Moderate PM

2.5

nonattainment areas may submit an impracticability demonstration, in lieu of a modeled attainment demonstration, if the state can establish that the area cannot practicably attain a particular PM

2.5

NAAQS by the outermost statutory Moderate area attainment date.

40 CFR 51.1002(b)(1).

On May 10, 2019, CARB made two SIP submissions intended to address the attainment plan requirements for areas designated as nonattainment for the 2012 PM

2.5

NAAQS.

First, the “2016 Moderate Area Plan for the 2012 PM

2.5

Standard” (“2016 PM

2.5

Plan”) addresses the Moderate area attainment plan requirements and includes a demonstration of impracticability of attaining the 2012 PM

2.5

NAAQS in the SJV by the latest permissible Moderate area attainment date of December 31, 2021. In this document, the EPA is proposing action on all portions of the 2016 PM

2.5

Plan. Second, the “2018 Plan for the 1997, 2006, and 2012 PM

2.5

Standards” (“2018 PM

2.5

Plan”) addresses the Serious area attainment plan requirements for the 2012 PM

2.5

NAAQS, in anticipation of the reclassification of SJV from Moderate to Serious for that PM

2.5

NAAQS. The 2018 PM

2.5

Plan incorporates by reference the “San Joaquin Valley Supplement to the 2016 State Strategy for the State Implementation Plan” (“Valley State SIP Strategy”), a related plan adopted by CARB on October 25, 2018, and submitted to the EPA with the 2018 PM

2.5

Plan on May 10, 2019. For the purposes of this action, the relevant portion of the Valley State SIP Strategy includes the control measure commitments associated with the quantitative milestones for 2019 and 2022.

CARB submitted the two plans electronically on May 10, 2019, as an attachment to a letter dated May 9, 2019, from Richard W. Corey, Executive Officer, CARB, to Mike Stoker, Regional Administrator, EPA Region IX.

The 2018 PM

2.5

Plan updates several elements in the 2016 PM

2.5

Plan, including the base year emissions inventory, plan precursor demonstration, controls analysis, reasonable further progress (RFP) and quantitative milestones, and motor vehicle emission budgets (MVEBs or “budgets”). In this document, the EPA is proposing action on those portions of the 2018 PM

2.5

Plan that apply to the Moderate area plan requirements for the 2012 PM

2.5

NAAQS. However, the EPA is not, at this time, proposing to act on those portions of the 2018 PM

2.5

Plan that are not relevant to our evaluation of compliance with Moderate area plan requirements for 2012 PM

2.5

NAAQS, such as the best available control measures (BACM) demonstration, control strategy commitments, attainment demonstration, RFP demonstration and quantitative milestones for later years, and MVEBs for later years.

The 2018 PM

2.5

Plan also addresses attainment plan requirements for areas classified as Serious for the 2006 PM

2.5

NAAQS. In 2020, we approved those portions of the 2018 PM

2.5

Plan that pertain to the 2006 PM

2.5

NAAQS, excluding the contingency measures element for the 2006 PM

2.5

NAAQS.

In this document, we are proposing action on the portion of the 2018 PM

2.5

Plan that addresses the contingency measure requirement for the 2006 PM

2.5

NAAQS.

85 FR 44192 (July 22, 2020).

Lastly, the 2018 PM

2.5

Plan addresses the contingency measure requirement for the 2006 PM

2.5

NAAQS by reference to, among other things, a District contingency measure, and emissions estimates for the year following the attainment year for use in evaluating whether the emissions reductions from the contingency measure are

sufficient.

With respect to the District contingency measure, the 2018 PM

2.5

Plan calls for the District to amend District Rule 4901 (“Wood Burning Fireplaces and Wood Burning Heaters”) to include a requirement in the rule with a trigger that would activate the requirement should the EPA issue a final rulemaking that SJV failed to meet a regulatory requirement necessitating implementation of a contingency measure.

2018 PM

2.5

Plan, App. H (revised February 11, 2020), H-24 to H-26.

In response to the commitment made in the 2018 PM

2.5

Plan, in June 2019 the District adopted amendments to Rule 4901, including a new provision (codified as section 5.7.3 of the amended rule) that is a contingency measure. On July 19, 2019, CARB submitted the amended rule to the EPA for approval.

We have already taken final action to approve the amended Rule 4901 (including the new section 5.7.3) into the California SIP, but in our approval we noted that we were not evaluating the contingency measure in section 5.7.3 of revised Rule 4901 for compliance with all requirements of the CAA and the EPA's implementing regulations that apply to such measures.

Rather, we approved the new provision (section 5.7.3) into the SIP as part of our approval of the entire amended rule because the provision strengthens the rule by providing a possibility of additional curtailment days and thus potentially additional emissions reductions. We indicated that we would evaluate whether section 5.7.3, in conjunction with other submitted provisions, meets the statutory and regulatory requirements for contingency measures in a future action. In this document, we are evaluating District Rule 4901, and in particular section 5.7.3, in the context of our action on the contingency measure element in the 2016 PM

2.5

Plan for the 2012 PM

2.5

NAAQS and the contingency measure element in the 2018 PM

2.5

Plan for the 2006 PM

2.5

NAAQS.

Letter dated July 19, 2019, from Richard W. Corey, Executive Officer, CARB, to Mike Stoker, Regional Administrator, EPA Region IX.

85 FR 44206 (July 22, 2020) (final approval of District Rule 4901); 85 FR 1131, 1132-33 (January 9, 2020) (proposed approval of District Rule 4901).

II. Summary of San Joaquin Valley 2016 and 2018 PM

2.5

Plans

A. 2016 PM

2.5

Plan Summary

The SJVUAPCD Governing Board adopted the 2016 PM

2.5

Plan on September 15, 2016, and CARB adopted the plan on January 24, 2019.

CARB submitted the plan to the EPA on May 10, 2019.

SJVUAPCD Governing Board Resolution 16-9-10, September 15, 2016, and CARB Resolution 19-1, January 24, 2019.

The 2016 PM

2.5

Plan is organized into three chapters, five appendices, and two attachments. Chapter 1 (“Introduction”) provides general background, including discussion of the federal PM

2.5

standards, PM

2.5

pollution and health effects in the SJV, challenges to attaining the standards, and the District's public process. Chapter 2 (“Impracticability Demonstration and Request for Reclassification”) presents CARB and the District's demonstration, based on air quality modeling, that attaining the 2012 PM

2.5

NAAQS by the latest permissible attainment date of December 31, 2021, is impracticable, and a request for reclassification to Serious. Chapter 3 (“Demonstration of Federal Clean Air Act Requirements”) describes how the 2016 PM

2.5

Plan addresses the federal requirements for Moderate PM

2.5

nonattainment areas, including a plan precursor demonstration, reasonably available control measures, RFP, quantitative milestones, contingency measures, stationary source permitting, and transportation conformity. The 2016 PM

2.5

Plan includes the following five technical appendices:

• Appendix A (“Air Quality Modeling”) provides the State's photochemical air quality modeling in support of the plan's impracticability demonstration and precursor demonstration;

• Appendix B (“Emissions Inventory”) presents the base year and future year emissions inventory for direct PM

2.5

, NO

, ammonia, SO

, and VOC;

• Appendix C (“SIP Creditable Incentive-Based Emission Reductions”) provides a demonstration of NO

emission reductions from heavy-duty off-road vehicle engine vehicle replacements under the 2011 Carl Moyer Guidelines in support of the plan's Moderate contingency measure element;

• Appendix D (“New Source Review and Emission Reduction Credits”) discusses the use of emission reduction credits (ERCs) in the context of the plan; and

• Appendix E (“Summary of Significant Comments and Responses”) summarizes significant comments received during the District's 2016 public review period and the District's responses thereto.

In addition, the 2016 PM

2.5

Plan includes Attachment 1 (“Stationary and Area Source Control Measure Analyses”) and Attachment 2 (“Mobile Source Control Measure Analyses”), which together resubmit the State's 2015 analyses that the District's stationary and area source control measures and CARB's mobile source control measures represent BACM and most stringent measures (MSM).

Lastly, on December 13, 2019, CARB submitted the following two additional documents that CARB had prepared for the 2016 PM

2.5

Plan and made available for public review along with the plan, but had inadvertently omitted them from the May 10, 2019 SIP submission to the EPA:

(i) The “Staff Report, ARB Review of the San Joaquin Valley 2016 Moderate Area Plan for the 2012 PM

2.5

Standard,” released September 16, 2016 (“CARB 2016 Staff Report”), that provides CARB's staff review of the 2016 PM

2.5

Plan, including brief summaries for each of the Moderate area plan requirements; and (ii) the “Modeling Emission Inventory for the PM

2.5

State Implementation Plan in the San Joaquin Valley,” August 23, 2016 (“2016 Modeling Emissions Inventory”) that describes the development of the 2016 PM

2.5

Plan's modeling emissions inventory, estimation of the 2013 base year emissions inventory, the methodology used to develop the base year and baseline emissions inventory, and quality assurance of the modeling emissions inventory.

Letter dated December 11, 2019, from Richard W. Corey, Executive Officer, CARB, to Mike Stoker, Regional Administrator, EPA Region IX, with enclosures.

B. 2018 PM

2.5

Plan Summary

The SJVUAPCD Governing Board adopted the 2018 PM

2.5

Plan on November 15, 2018, and CARB adopted the plan on January 24, 2019.

CARB submitted the 2018 PM

2.5

Plan to the EPA on May 10, 2019, concurrently with the 2016 PM

2.5

Plan.

SJVUAPCD Governing Board Resolution 18-11-16, November 15, 2018, and CARB Resolution 19-1, January 24, 2019.

The following portions of the 2018 PM

2.5

Plan and related support documents apply to the Moderate area attainment plan requirements for the 2012 PM

2.5

NAAQS in the SJV: (i) Chapter 4 (“Attainment Strategy for PM

2.5

”); (ii) Chapter 7 (“Demonstration of Federal Requirements for the 2012 PM

2.5

Standard”);

(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 2018 Staff Report”);

and (v) the State's and District's board resolutions adopting the 2018 PM

2.5

Plan.

Chapter 5 (“Demonstration of Federal Requirements for the 1997 PM

2.5

Standard”) and Chapter 6 (“Demonstration of Federal Requirements for the 2006 PM

2.5

Standard”) of the 2018 PM

2.5

Plan pertain to the 1997 PM

2.5

NAAQS and 2006 PM

2.5

NAAQS, respectively. The EPA has acted on

Chapter 6 in our rulemaking for the 2006 PM

2.5

NAAQS. See 80 FR 44192 (July 22, 2020). The EPA has proposed to act on Chapter 5 as part of a separate rulemaking on the 1997 annual PM

2.5

NAAQS. See 86 FR 38652 (July 22, 2021).

The CARB 2018 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 W. Corey, Executive Officer, CARB, to Mike Stoker, Regional Administrator, EPA Region IX, transmitting the CARB 2018 Staff Report [on the 2018 PM

2.5

Plan].

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.

The appendices to the 2018 PM

2.5

Plan, in order of their evaluation in this proposal, include the following: (i) Appendix (“App.”) B (“Emissions Inventory”); (ii) 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 2018 Staff Report; (iii) control strategy appendices, including App. C (“Stationary Source Control Measure Analyses”) and App. D (“Mobile Source Control Measures Analyses”); and (iv) App. H (“RFP, Quantitative Milestones, and Contingency”). The 2018 PM

2.5

Plan addresses requirements for MVEBs in the “Transportation Conformity” section of App. D.

See 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 appendices on “Public Education and Technology Advancement” (App. F), “Ambient PM

2.5

Data Analysis” (App. A), “New Source Review and Emission Reduction Credits” (App. I) and “Summary of Significant Comments and Responses” (App. M), as well other chapters and appendices that are primarily relevant to the Serious area plan requirements, including App. E (“Incentive-Based Strategy”), App. J (“Modeling Emission Inventory”), App. K (“Modeling Attainment Demonstration”), and App. L (“Modeling Protocol”).

Lastly, on February 11, 2020, CARB submitted, via the EPA State Planning Electronic Collaboration System, a revised version of App. H (“RFP, Quantitative Milestones, and Contingency”) that replaces the version submitted with the 2018 PM

2.5

Plan on May 10, 2019. All references to App. H of the 2018 PM

2.5

Plan in this proposed rule are to the revised version of Appendix H submitted February 11, 2020.

C. Procedural Requirements for SIPs and SIP Revisions

Sections 110(a)(1) and (2) and 110(l) of the CAA require each state to provide reasonable public notice and an opportunity for a public hearing prior to the adoption and submittal 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 an opportunity for a public hearing was provided consistent with the EPA's implementing regulations in 40 CFR 51.102.

Both the District and CARB satisfied applicable statutory and regulatory requirements for reasonable public notice and hearing prior to adoption and submission of the 2016 PM

2.5

Plan and the 2018 PM

2.5

Plan. The District provided public notice and opportunity for public comment prior to its September 15, 2016 public hearing on and adoption of the 2016 PM

2.5

Plan.

CARB also provided public notice and opportunity for public comment prior to its October 20, 2016 public hearing,

where the 2016 PM

2.5

Plan was tabled.

SJVUAPCD, “Notice of Public Hearing, Adopt the Proposed 2016 Moderate Area Plan for the 2012 PM

2.5

Standard,” August 16, 2016, and SJVUAPCD Governing Board Resolution 16-9-10.

CARB, “Notice of Public Meeting to Consider the 2016 PM

2.5

State Implementation Plan for the San Joaquin Valley,” September 20, 2016.

Subsequently, 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.

CARB also provided public notice and opportunity for public comment prior to its January 24, 2019 public hearing,

when CARB adopted the 2016 PM

2.5

Plan and the 2018 PM

2.5

Plan.

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.

27 28

Therefore, we find that the 2016 PM

2.5

Plan and the 2018 PM

2.5

Plan meet the procedural requirements for public notice and hearing in CAA sections 110(a) and 110(l) and 40 CFR 51.102.

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.

CARB, “Notice of Public Meeting to Consider the 2018 PM

2.5

State Implementation Plan for the San Joaquin Valley,” December 21, 2018.

CARB Resolution 19-1. See also J&K Court Reporting, LLC, “Meeting, State of California Air Resources Board,” October 20, 2016 (transcript of CARB's public hearing), 186-190.

For the 2016 PM

2.5

Plan: CARB, “Board Meeting Comments Log,” available at

https://www.arb.ca.gov/lispub/comm/bccommlog.php?listname=sjvpmplan2016

(accessed August 20, 2021); J&K Court Reporting, LLC, “Meeting, State of California Air Resources Board,” October 16, 2016 (transcript of CARB's public hearing), available at

https://ww3.arb.ca.gov/board/mt/2016/mt102016.pdf

(accessed December 29, 2020); and 2016 PM

2.5

Plan, App. E (“Summary of Significant Comments and Responses”), noting that no comments were received during the District's 2016 public review.

For the 2018 PM

2.5

Plan: 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”).

We present our evaluation of the 2016 PM

2.5

Plan (and 2018 PM

2.5

Plan as applicable to the Moderate area attainment plan requirements for the 2012 PM

2.5

NAAQS) in Section IV of this proposed rule. We present our evaluation of the 2018 PM

2.5

Plan as applicable to the contingency measure requirements for the 2006 PM

2.5

NAAQS in section VII of this proposed rule.

III. Clean Air Act Requirements for Moderate PM

2.5

Nonattainment Area Plans

With respect to the statutory requirements for particulate matter (PM) attainment plans, the general nonattainment area planning requirements of title I, part D of the CAA are found in subpart 1, and the attainment planning requirements specifically for PM are found in subpart 4.

The EPA has a longstanding general guidance document that interprets the 1990 amendments to the CAA, commonly referred to as the General Preamble for the Implementation of Title I of the Clean Air Act Amendments of 1990 (“General Preamble”).

The General Preamble addresses the relationship between the subpart 1 and subpart 4 requirements and provides recommendations to states for meeting certain statutory requirements for PM attainment plans. As explained in the General Preamble, specific requirements applicable to Moderate area attainment plan SIP submissions for the PM NAAQS are set forth in subpart 4 of part

D, title I of the Act, but such SIP submissions must also meet the general attainment planning provisions in subpart 1 of part D, title I of the Act, to the extent these provisions “are not otherwise subsumed by, or integrally related to,” the more specific subpart 4 requirements.

The EPA provided further guidance to States on PM plan submissions in the Addendum to the General Preamble (“General Preamble Addendum”).

General Preamble, 57 FR 13498 (April 16, 1992).

Id. at 13538.

59 FR 41998 (August 16, 1994).

To implement the PM

2.5

NAAQS, the EPA has also promulgated the “Fine Particle Matter National Ambient Air Quality Standard: State Implementation Plan Requirements; Final Rule” (“PM

2.5

SIP Requirements Rule”).

The PM

2.5

SIP Requirements Rule establishes regulatory requirements and provides additional guidance applicable to attainment plan submissions for the PM

2.5

NAAQS, including the 2012 annual PM

2.5

NAAQS and the 2006 24-hour PM

2.5

NAAQS, addressed in this section and section VII, respectively, of this proposed rule.

81 FR 58010 (August 24, 2016).

The general subpart 1 statutory requirements for attainment plans include the following: (i) The section 172(c)(1) requirement for reasonably available control measures (RACM)/reasonably available control technology (RACT) and attainment demonstrations; (ii) the section 172(c)(2) requirement to RFP; (iii) the section 172(c)(3) requirement for emissions inventories; (iv) the section 172(c)(5) requirement for a nonattainment new source review (NNSR) permitting program; and (v) the section 172(c)(9) requirement for contingency measures.

The more specific subpart 4 statutory requirements for Moderate PM

2.5

nonattainment areas include the following: (i) The section 189(a)(1)(A) and 189(e) NNSR permit program requirements; (ii) the section 189(a)(1)(B) requirement for attainment demonstrations; (iii) the section 189(a)(1)(C) requirement for RACM; and (iv) the section 189(c) requirements for RFP and quantitative milestones. Under subpart 4, states with Moderate PM

2.5

nonattainment areas must provide for attainment in the area as expeditiously as practicable but no later than the latest permissible attainment date under CAA section 188(c),

i.e.,

December 31, 2021, for the 2012 PM

2.5

NAAQS in the SJV, unless the EPA determines, per section 188(b)(1), that the area cannot practicably attain the NAAQS by the Moderate area attainment date.

In addition, under subpart 4, direct PM

2.5

and all precursors to the formation of PM

2.5

are subject to control unless the EPA approves a demonstration from the state establishing that a given precursor does not contribute significantly to PM

2.5

levels that exceed the PM

2.5

NAAQS in the area.

Generally, under CAA section 188(c), the latest permissible attainment date for a Moderate nonattainment area is the end of the sixth calendar year after the area's designation as nonattainment. Because the EPA designated and classified the San Joaquin Valley as a Moderate nonattainment area for the 2012 PM

2.5

NAAQS effective April 15, 2015 (80 FR 2206, 2217-2218), the latest permissible attainment date for these NAAQS in the San Joaquin Valley is December 31, 2021.

40 CFR 51.1006 and 51.1009.

IV. Review of San Joaquin Valley Plans for Moderate Area Requirements

A. Emissions Inventory

1. Requirements for Emissions Inventories

Section 172(c)(3) of the CAA 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. We refer to this inventory as the “base year inventory.” The EPA has established regulatory requirements for base year and other emissions inventories in the PM

2.5

SIP Requirements Rule

and issued guidance concerning emissions inventories for PM

2.5

nonattainment areas.

40 CFR 51.1008.

81 FR 58010, 58078-58079 and “Emissions Inventory Guidance for Implementation of Ozone and Particulate Matter National Ambient Air Quality Standards (NAAQS) and Regional Haze Regulations,” 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 emissions inventory must include direct PM

2.5

emissions, separately reported filterable and condensable PM

2.5

emissions,

and emissions of all chemical precursors to the formation of secondary PM

2.5

: NO

, SO

, VOC, and ammonia.

In addition, the emissions inventory base year for a Moderate PM

2.5

nonattainment area must be one of the three years (

i.e.,

2011-2013) for which monitored data were used to designate the area as nonattainment, or another technically appropriate year justified by the state in its Moderate area attainment plan submission.

The Emissions Inventory Guidance identifies the types of sources for which the EPA expects states to provide condensable PM emissions inventories. Emissions Inventory Guidance, section 4.2.1 (“Condensable PM Emissions”), 63-65.

40 CFR 51.1008.

40 CFR 51.1008(a)(1)(i).

In its SIP submission, a state must include documentation explaining how it calculated emissions data. In estimating mobile source emissions, a state should use the latest emissions models and planning assumptions available at the time it develops the SIP submission. 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.

40 41

At the time the 2016 PM

2.5

Plan and 2018 PM

2.5

Plan were developed, California was required to use EMFAC2014 to estimate tailpipe and brake and tire wear emissions of PM

2.5

, NO

, SO

, and VOC from on-road mobile sources.

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 emissions tests results. (76 FR 6328, February 4, 2011). CARB used the revised 2011 AP-42 methodology in developing on-road mobile source emissions.

AP-42 has been published since 1972 as the primary source of the EPA's emission factor information. 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.

The EMFAC model (short for EMission FACtor) is a computer model developed by CARB. The EPA approved and announced the availability of EMFAC2014 for use in SIP development and transportation conformity in California on December 14, 2015 (80 FR 77337). The EPA's approval of the EMFAC2014 emissions model for SIP and conformity purposes was effective on the date of publication in the

Federal Register

. On August 15, 2019, the EPA approved and announced the availability of EMFAC2017, the latest update to the EMFAC model for use by state and local governments to meet CAA requirements (84 FR 41717). EMFAC2017 was not available to the State and District at the time they were developing the 2016 PM

2.5

Plan and had only recently been submitted to the EPA on July 20, 2018, prior to the adoption of the 2018 PM

2.5

Plan.

In addition to the base year inventory submitted to meet the requirements of CAA section 172(c)(3), a state must also submit future “baseline inventories” for the projected attainment year, each RFP milestone year, and any other year of significance for meeting applicable CAA requirements.

By baseline inventories we mean projected emissions inventories for future years that account for, among other things, the ongoing

effects of economic growth and adopted emission control requirements. The SIP submission should include documentation to explain how the state calculated the emissions projections.

40 CFR 51.1008(a)(2) and 51.1012(a)(2); see also Emissions Inventory Guidance.

2. Summary of State's Emissions Inventories

Within the 2016 PM

2.5

Plan, the annual average planning inventories for direct PM

2.5

and all PM

2.5

precursors (NO

, ammonia, SO

and VOC) for the SJV PM

2.5

nonattainment area, together with documentation for the inventories, are found in Appendix B (“Emissions Inventory”). In addition, Appendix A (“Air Quality Modeling”) contains inventory documentation specific to the air quality modeling inventories. These portions of the 2016 PM

2.5

Plan contain annual average daily emission inventories for 2013 thru 2022 projected from the 2012 actual emissions inventory,

including the 2013 base year, the 2019 RFP baseline year, the 2021 Moderate area attainment year, and the 2022 post-attainment RFP year. The winter average daily inventory is used to evaluate sources of emissions for attainment of the 2012 PM

2.5

NAAQS in the 2016 PM

2.5

Plan.

The 2016 PM

2.5

Plan generally uses “sulfur oxides” or “SO

” in reference to SO

as a precursor to the formation of PM

2.5

. We use SO

and SO

interchangeably throughout this notice.

2016 PM

2.5

Plan, App. B, B-18.

The 2016 PM

2.5

Plan includes annual average and winter day average inventories for PM

2.5

planning purposes. The winter average daily planning inventory corresponds to the months of November through April, when daily, ambient PM

2.5

concentrations are typically highest. 2016 PM

2.5

Plan, App. B, B-19. 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) version 1.04.

Similarly, within the 2018 PM

2.5

Plan, the annual average planning inventories for direct PM

2.5

and all PM

2.5

precursors, together with documentation for the inventories, are found in Appendix B (“Emissions Inventory”). In addition, Appendix J (“Modeling Emission Inventory”) contains inventory documentation specific to the air quality modeling inventories. These portions of the 2018 PM

2.5

Plan contain annual average daily emission inventories for 2013 thru 2028 projected from the 2012 actual emissions inventory,

including the 2013 base year, the 2019 and 2022 RFP baseline years, the 2025 Serious area attainment year, and the 2028 post-attainment RFP year. Both the annual average and the winter average daily inventories are used to evaluate sources of emissions for attainment of the 2012 PM

2.5

NAAQS in the 2018 PM

2.5

Plan.

2018 PM

2.5

Plan, App. B, B-18.

2018 PM

2.5

Plan, App. B, B-19. The base year inventory is from CEIDARS and future year inventories were estimated using CEPAM, 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 inventories for area sources using the most recent models and methodologies available at the time the State was developing the 2016 PM

2.5

Plan and 2018 PM

2.5

Plan.

Importantly, CARB and the District updated the emissions inventory in the 2018 PM

2.5

Plan using the latest available activity data and emission methodologies available at the time of plan development. The 2013 base year, annual average emissions inventories for most source categories did not change or only changed plus or minus 0.1 tons per day (tpd) between the two plans.

However, the base year emissions inventory from several important source categories were smaller in the 2018 PM

2.5

Plan relative to the 2016 PM

2.5

Plan based on the latest information. These include a 1.2 tpd decrease in direct PM

2.5

emissions from residential fuel combustion based on a 2016 emissions inventory methodology update,

a 0.4 tpd decrease in direct PM

2.5

emissions from farming operations based on updated estimates by the California Department of Conservation of harvested acreage in 2010-2020 rather than 2000-2009,

and a 0.9 tpd decrease in NO

emissions from trains based on updated locomotive data from 2016 on Class I and Class II railroads.

Overall, for the 2013 base year, total emissions of both direct PM

2.5

and NO

were 0.9 tpd smaller in the 2018 PM

2.5

Plan relative to the 2016 PM

2.5

Plan.

2016 PM

2.5

Plan, App. B, section B.3 (“Emissions Inventory Summary and Methodology”), and 2018 PM

2.5

Plan, App. B, section B.2 (“Emissions Inventory Summary and Methodology”).

For example, paved road dust direct PM

2.5

emissions decreased 0.1 tpd while off-road equipment NO

emissions increased by 0.1 tpd between the 2016 and 2018 PM

2.5

Plans.

2018 PM

2.5

Plan, App. B, B-26.

2018 PM

2.5

Plan, App. B, B-27.

2018 PM

2.5

Plan, App. B, B-34.

Furthermore, the 2016 PM

2.5

Plan's emissions inventory does not separately report filterable and condensable PM

2.5

emissions. However, the 2018 PM

2.5

Plan 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

It provides filterable and condensable emissions estimates, expressed as annual PM

2.5

emissions (tons per year), for all of the identified source categories for the years applicable to the Moderate area timeframe, including the 2013 base year, the 2019 RFP year, the 2021 Moderate area attainment year, and the 2022 post-attainment RFP year, as well as subsequent years.

2018 PM

2.5

Plan, App. B, B-42 to B-44. The EPA has approved the emissions inventory submission for the 2006 PM

2.5

NAAQS in the SJV, including the filterable and condensable PM

2.5

inventories. 85 FR 44192 (July 22, 2020) (final rule); and 85 FR 17382, 17389 (March 27, 2020) (proposed rule).

CARB used EMFAC2014 to estimate on-road motor vehicle emissions based on transportation activity data from the 2014 Regional Transportation Plan adopted by the transportation planning agencies in the SJV.

Re-entrained paved road dust emissions were calculated using a CARB methodology consistent with the EPA's AP-42 road dust methodology.

CARB also provided emissions inventories for off-road equipment, including aircraft, trains, recreational boats, construction equipment, and farming equipment, among others. CARB uses a suite of category-specific models to estimate off-road emissions for many categories and, where a new model was not available, used the OFFROAD2007 model.

2016 PM

2.5

Plan, App. B, B-33; and 2018 PM

2.5

Plan, App. B, B-37. We note that the vehicle miles traveled data used in the 2018 PM

2.5

Plan's emissions inventory is from the final 2017 Federal Transportation Improvement Program from each of the SJV's eight metropolitan planning organizations.

2016 PM

2.5

Plan, App. B, B-26; and 2018 PM

2.5

Plan, App. B, B-28.

2016 PM

2.5

Plan, App. B, B-33 through B-35; and 2018 PM

2.5

Plan, App. B, B-38 through B-40.

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.

In the 2016 PM

2.5

Plan and 2018 PM

2.5

Plan, the District provides for use of pre-base year ERCs as offsets by accounting for such ERCs in the projected emissions inventory for the 2022 RFP year and the projected 2025 attainment year, respectively.

The plans identify growth factors, control factors, and estimated offset use between 2013 and 2022, and between 2013 and 2025, for direct PM

2.5

, NO

, SO

, and VOC emissions by source category and lists all pre-base year ERCs

issued by the District for PM

, SO

, and VOC emissions, by facility.

2016 PM

2.5

Plan, App. B, B-19; and 2018 PM

2.5

Plan, App. B, B-19.

2016 PM

2.5

Plan, App. D, D-1 through D-5; and 2018 PM

2.5

Plan, App. I, I-1 through I-5.

Particulate matter with a diameter of 10 microns or less.

2016 PM

2.5

Plan, App. D, tables D-1 through D-5; and 2018 PM

2.5

Plan, App. I, tables I-1 through I-5.

Table 1 provides a summary of the 2018 PM

2.5

Plan's winter (24-hour) average inventories in tpd of direct PM

2.5

and PM

2.5

precursor emissions for the 2013 base year. Table 2 provides a summary of 2018 PM

2.5

Plan's annual average inventories of direct PM

2.5

and PM

2.5

precursor emissions for the 2013 base year. For purposes of this proposal, these annual average inventories provide bases primarily for our evaluation of the precursor demonstration, control measure analysis, impracticability demonstration, RFP demonstration, and MVEBs in the 2018 PM

2.5

Plan with respect the Moderate area requirements.

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

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

62.5

317.2

8.5

324.1

329.2

Source:

2018 PM

2.5

Plan, Appendix B, tables B-1 through B-5.

Totals reflect disaggregated emissions and may not add exactly as shown here due to rounding.

3. EPA Evaluation and Proposed Action

Consistent with the requirement that inventories be based on the most current and accurate information available to the State and District at the time they were developing the plans and inventories, our evaluation for the SJV for the 2012 PM

2.5

NAAQS relies primarily on the emissions inventories in the 2018 PM

2.5

Plan. The inventories in the 2018 PM

2.5

Plan include the latest version of California's mobile source emissions model, EMFAC2014, that had been approved by the EPA at the time, and the EPA's most recent AP-42 methodology for paved road dust. The inventories comprehensively address all source categories in the SJV PM

2.5

nonattainment area and are consistent with the EPA's inventory guidance.

In accordance with 40 CFR 51.1008(a), the 2013 base year is one of the three years for which monitored data were used for designating the area, and it represents 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.

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 2016 PM

2.5

Plan and 2018 PM

2.5

Plan reflect appropriate calculation methods and the latest planning assumptions at the time the State and District were developing the plans and inventories. 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 and area sources, the related rules must be approved by the EPA into the SIP.

Given the State's impracticability demonstration for attaining the 2012 PM

2.5

NAAQS in the SJV by the outermost Moderate area attainment date, the 2016 PM

2.5

Plan describes the District rules achieving post-2013 emission reductions that contribute towards attaining the NAAQS.

In our rulemaking on the State's attainment plan for the 2006 PM

2.5

NAAQS in the SJV, we reviewed the baseline measures identified as 2018 PM

2.5

Plan baseline controls to ensure that the measures that are relied upon in the plan have been submitted and approved as part of the California SIP.

That set of 2018 PM

2.5

Plan baseline measures includes all

those baseline measures identified in the 2016 PM

2.5

Plan's RFP demonstration as achieving emission reductions post-2013. Based on that review, we confirm that the stationary and area source baseline measures in the 2016 PM

2.5

Plan and 2018 PM

2.5

Plan are approved into the SIP and support the emissions reductions for future years in the SJV. With respect to mobile sources, the EPA has acted 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 2016 PM

2.5

Plan and 2018 PM

2.5

Plan are properly supported by SIP-approved stationary, area, and mobile source measures.

2016 PM

2.5

Plan, Table 3-2. This includes District rules for open burning; boilers, steam generators, and process heaters; flares; glass melting furnaces; stationary internal combustion engines; and residential wood burning.

EPA, “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 V-A of EPA's General Evaluation TSD shows District rules with post-2013 compliance dates that are reflected in the future year baseline inventories of the 2018 PM

2.5

Plan, along with information on the EPA's approval of these rules.

See,

e.g.,

81 FR 39424 (June 16, 2016), 82 FR 14447 (March 21, 2017), and 83 FR 23232 (May 18, 2018).

The baseline emissions projections in the 2016 PM

2.5

Plan assume implementation of CARB's zero emissions vehicle (ZEV) sales mandate and greenhouse gas (GHG) standards, based on the approved EMFAC2014 model and assumptions that were available at the time of the SIP's development. On September 27, 2019, the U.S. Department of Transportation and the EPA (the Agencies) issued a notice of final rulemaking for the “Safer Affordable Fuel-Efficient (SAFE) Vehicles Rule Part One: One National Program” (“SAFE I”) that, among other things, withdrew the EPA's 2013 waiver of preemption of CARB's ZEV sales mandate and vehicle GHG standards. 84 FR 51310 (September 27, 2019). See also proposed SAFE rule at 83 FR 42986 (August 24, 2018). In response to SAFE I, CARB developed EMFAC off-model adjustment factors to account for anticipated changes in on-road emissions. On March 12, 2020, the EPA informed CARB that the EPA considers these adjustment factors to be acceptable for future use. See letter dated March 12, 2020, from Elizabeth J. Adams, EPA Region IX, to Steven Cliff, CARB. On April 30, 2020 (85 FR 24174), the Agencies issued a notice of final rulemaking for the “The Safer Affordable Fuel-Efficient (SAFE) Vehicles Rule for Model Years 2021-2026 Passenger Cars and Light Trucks” (“SAFE II”), establishing the federal fuel economy and GHG vehicle emissions standards based on the August 2018 SAFE proposal. The effect of both SAFE final rules (SAFE I and SAFE II) on the on-road vehicle mix in the SJV nonattainment area and on the resulting vehicular emissions is expected to be minimal during the timeframe addressed in this SIP revision. Therefore, we anticipate the SAFE final rules would not materially change the demonstration that it is impracticable for the SJV 2012 PM

2.5

Moderate area to attain by the Moderate area attainment date of December 31, 2021.

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 future year baseline inventories in the 2016 PM

2.5

Plan and 2018 PM

2.5

Plan satisfy the requirements of 40 CFR 51.1008(a)(2) and 51.1012(a)(2) and provide an adequate basis for the control measure, RFP, and impracticability demonstrations in the 2016 PM

2.5

Plan and 2018 PM

2.5

Plan, respectively.

B. PM

2.5

Precursors

1. Requirements for Control of PM

2.5

Precursors

The provisions of subpart 4 of part D, title I of the CAA do not define the term “precursor” for purposes of PM

2.5

, nor do they explicitly require the control of any specifically identified PM precursor. The statutory definition of “air pollutant” in CAA section 302(g), 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.” The EPA has identified NO

, SO

, VOC, and ammonia as precursors to the formation of PM

2.5

. 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.,

in CAA section 189(e)).

Section 189(e) of the Act requires that the control requirements for major stationary sources of direct PM

(which includes PM

2.5

) also apply to major stationary sources of PM

precursors, except where the Administrator determines that such sources do not contribute significantly to PM

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 RACM, RACT, BACM, best available control technology (BACT), MSM, and NNSR) 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. For example, under the EPA's longstanding interpretation of the control requirements that apply to stationary and mobile sources of PM

precursors in the nonattainment area under CAA section 172(c)(1) and subpart 4,

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

levels in the nonattainment area.

General Preamble, 13539-13542.

Courts have upheld this approach to the requirements of subpart 4 for PM

. See,

e.g., Assoc. of Irritated Residents

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.

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.

40 CFR 51.1006(a)(1).

Id.

We are evaluating the 2016 PM

2.5

Plan and 2018 PM

2.5

Plan with respect to the Moderate area requirements 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.

2. Summary of State's Precursor Demonstrations

The State presents analyses of PM

2.5

precursors in both the 2016 PM

2.5

Plan and the 2018 PM

2.5

Plan and primarily relies on sensitivity-based contribution analyses to determine whether each PM

2.5

plan precursor contributes significantly to ambient PM

2.5

levels that exceed the 2012 PM

2.5

NAAQS. We summarize below key points from the State's analyses and conclusions for each pollutant, focusing on the three precursors (ammonia, SO

, and VOC) that the State concludes do not contribute significantly to PM

2.5

levels that exceed the 2012 PM

2.5

NAAQS in the SJV.

In the 2016 PM

2.5

Plan, the State's precursor demonstration and conclusions are found in section 2.3 (“Summary of Modeling Results”), section 3.3 (“Precursor

Demonstration”), and Appendix A (“Air Quality Modeling”). The State estimates that baseline anthropogenic emissions of NO

, ammonia, SO

, and VOC will decrease by 38 percent (%), 1%, 2%, and 8%, respectively, between 2013 and 2021.

The State does not present a concentration-based analysis of the contribution of each precursor to ambient PM

2.5

concentrations, but does estimate PM

2.5

component concentrations in the 2013 base year across all SJV monitoring sites.

The concentrations indicate that each precursor may have a significant impact on PM

2.5

levels.

The State presents a sensitivity-based precursor analysis using the modeled response of ambient PM

2.5

concentrations to a 15% increase or decrease in the future baseline emissions of each precursor in 2025 (the latest permissible attainment year if the area is reclassified to Serious for the 2012 PM

2.5

NAAQS).

For each precursor, the State then takes the difference between the PM

2.5

concentrations from the 15% increase and the 15% decrease to estimate the ambient PM

2.5

response to a 30% change in the precursor, and reviews the resulting change at each monitor to see whether any response exceeds a threshold of 0.2 µg/m

2016 PM

2.5

Plan, 2-4 and Table 2-1.

Id. at Table 2-4.

Using the species assignments recommended in the Draft Precursor Demonstration Guidance (on page 21) the relevant concentrations are as follows: For NO

, the nitrate and associated ammonium is up to 7.1 µg/m

; for SO

, sulfate is up to 1.7 µg/m

; for ammonia, the sum of ammonium and nitrate is up to 7.1 µg/m

; for VOC the only available concentration is for “OM” (organic matter), which is up to 8.7 µg/m

, and is likely much higher than the secondary organic aerosol that is relevant for VOC as a PM

2.5

precursor. All these values are well above the 0.2 µg/m

threshold.

2016 PM

2.5

Plan, App. A, section 5.4 (“Precursor Sensitivity Analysis”).

For the annual PM

2.5

NAAQS, the EPA generally expects that a precursor demonstration showing that the air quality impact of a given precursor at all relevant locations does not exceed a contribution threshold of 0.2 μg/m

will be adequate to exempt sources of that precursor from control requirements. PM

2.5

Precursor Guidance, 17.

The responses range from 0.5 µg/m

to 1.5 µg/m

for NO

; from 0.1 µg/m

to 0.2 µg/m

for ammonia; from 0.1 µg/m

to 0.2 µg/m

for SO

; and from -0.1 µg/m

to 0.1 µg/m

for VOC.

The State concludes that emissions of NO

(as well as direct PM

2.5

) contribute significantly to ambient PM

2.5

levels that exceed the PM

2.5

NAAQS but ammonia, SO

, and VOC do not contribute significantly to such exceedances.

The 2016 PM

2.5

Plan, Appendix A, section 5.5 (“Discussion of Precursor Sensitivity”) includes additional discussion of ammonia's and VOC's role in the formation of ammonium nitrate and VOC's role in the formation of secondary organic aerosols.

2016 PM

2.5

Plan, App. A, tables 24, 26, 28, and 27, respectively.

Id. at 2-6 and 3-3, and App. A, A-52. We note that 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

In the 2018 PM

2.5

Plan, the State's precursor demonstration and conclusions are found in Chapter 7 (“Demonstration of Federal Requirements for 2012 PM

2.5

Standard”) and Appendix G (“Precursor Demonstration”). CARB also provides clarifying information on its precursor assessment, including an Attachment A to its letter transmitting the 2018 PM

2.5

Plan to the EPA

and further clarifications in four email transmittals.

Letter dated May 9, 2019, from Richard W. 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”).

Email dated June 20, 2019, “RE: SJV model disbenefit from SO

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”); 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”); and email dated April 26, 2021, from Laura Carr, CARB, to Scott Bohning, EPA Region IX, Subject: “RE: Ammonia update,” with attachment “Ammonia in San Joaquin Valley” (“CARB's April 26, 2021, Precursor Clarification”).

The State estimates that anthropogenic emissions of NO

, ammonia, SO

, and VOC will decrease by 64%, 1%, 6%, and 9%, respectively, between 2013 and 2025.

The 2018 PM

2.5

Plan provides both concentration-based and sensitivity-based analyses of precursor contributions to ambient PM

2.5

concentrations in the SJV. Based on these analyses, the State concludes that emissions of NO

(as well as direct PM

2.5

) contribute significantly to ambient PM

2.5

levels that exceed the PM

2.5

NAAQS in the SJV but ammonia, SO

, and VOC do not contribute significantly to such exceedances.

2018 PM

2.5

Plan, Ch. 7, 7-5 and Table 7-2. Notably, the estimated 64% reduction in NO

from 2013 to 2025 (per the 2018 PM

2.5

Plan) is much larger than the estimated 38% reduction in NO

from 2013 to 2021 (per the 2016 PM

2.5

Plan), reflecting both additional years of reductions and additional reductions anticipated from the 2018 PM

2.5

Plan control strategy. We also note that a copy of the contents of the 2018 PM

2.5

Plan, App. G appears in the CARB 2018 Staff Report, App. C4 (“Precursor Demonstrations for Ammonia, SO

, and ROG”).

While these analyses are primarily designed to evaluate the role of precursors in attaining the 2006 24-hour PM

2.5

NAAQS by 2024 and the 2012 annual PM

2.5

NAAQS by 2025, they are important to the consideration of precursors for the State's Moderate area plan because they are based on updated data (

e.g.,

updated emissions inventories, as discussed in section IV.A of this proposed rule), use an updated methodology to evaluate the sensitivity of ambient PM

2.5

to a range of precursor emission reductions, consistent with the EPA's guidance, and best reflect the State's understanding of the control strategies being implemented in the SJV.

We summarize the State's analyses and conclusions in the following paragraphs. For ammonia, SO

, and VOC, CARB assesses 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 compares those concentrations to the recommended annual average contribution threshold of 0.2 µg/m

from the EPA's “Draft PM

2.5

Precursor Guidance”

available at the time the State developed the SIP.

The 2015 annual average contributions of ammonia, SO

, and VOC are 5.2 µg/m

, 1.6 µg/m

and 6.2 µg/m

, respectively.

“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.

2018 PM

2.5

Plan, App. G, 3. The 2018 PM

2.5

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. 2018 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, the State models the sensitivity of ambient PM

2.5

in the SJV to reductions in each precursor pollutant. For direct PM

2.5

and NO

, the State models the sensitivity of ambient PM

2.5

in the SJV to a 30% reduction in anthropogenic emissions of each pollutant in 2013, 2020, and 2024.

The State concludes that direct PM

2.5

and NO

emissions reductions will continue to have a significant impact on annual

and 24-hour PM

2.5

design values in the SJV, with NO

reductions being particularly important.

2018 PM

2.5

Plan, Ch. 7, 7-7. The sensitivity-based analysis used the same modeling platform as that used for the 2018 PM

2.5

Plan's attainment and RFP demonstrations. CARB modeled the impacts of both NO

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.

Id. Ch. 7, 7-7; and 2018 PM

2.5

Plan, App. G, 2. CARB presents its sensitivity analysis for emission reductions in direct PM

2.5

and NO

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

, and VOC, the State then models the sensitivity of ambient PM

2.5

to 30% and 70% reductions in anthropogenic emissions of each precursor pollutant in 2013 (the 2018 PM

2.5

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, and proxy for the modeled attainment year of 2025 for the 2012 PM

2.5

NAAQS).

Depending on the analysis year and percentage precursor emission reduction, the sensitivity of ambient PM

2.5

to reductions in annual average precursor emissions ranges from 0.08 µg/m

to 2.30 µg/m

for ammonia; from −0.05 µg/m

to 0.15 µg/m

for SO

; and from −0.50 µg/m

to 0.40 µg/m

for VOC.

2018 PM

2.5

Plan, Ch. 7, 7-7. The 2018 PM

2.5

Plan precursor demonstration assumes that 2025 attainment year sensitivities are very similar to those modeled in 2024. 2018 PM

2.5

Plan, App. G, 10. We note that the State only modeled 30% and 70% reductions in SO

for 2013, finding that the sensitivity of ambient PM

2.5

to such changes were below the EPA's recommended threshold.

Id. at App. G, tables 2 through 7 for ammonia, tables 8 and 9 for SO

, and tables 10 through 15 for VOC.

For ammonia, the modeled sensitivity of ambient PM

2.5

levels to a 30% or 70% emission reduction exceed 0.2 µg/m

in certain years at specific monitoring sites. We provide a detailed summary of these modeling results and our evaluations thereof in the “Technical Support Document, EPA Evaluation of Ammonia Precursor Demonstration, San Joaquin Valley Moderate Area PM

2.5

Plan for the 2012 PM

2.5

NAAQS,” August 2021 (“EPA's Ammonia Precursor TSD”). In contrast, for SO

and VOC, the modeled sensitivity of ambient PM

2.5

levels to a 30% or 70% emission reduction in either precursor is below 0.2 µg/m

, including a disbenefit at certain monitoring sites (

i.e.,

ambient PM

2.5

level increase), in all scenarios except one. For 2013, the State's modeling shows an ambient PM

2.5

change greater than 0.2 µg/m

in response to a 70% VOC emission reduction. According to the State, however, such sensitivity results do not reflect the atmospheric chemistry in the SJV given the projected emission reductions from 2013 to 2024 for all four PM

2.5

precursors, especially for VOC and NO

For a more detailed summary of the State's precursor demonstration in the 2018 PM

2.5

Plan for the 2006 24-hour PM

2.5

NAAQS, see 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 24-hour PM

2.5

Precursor TSD”).

The State supplements the sensitivity analysis, particularly for ammonia, 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.

The PM

2.5

Precursor Guidance confirms that these factors may be relevant to a sensitivity-based contribution analysis.

2018 PM

2.5

Plan, App. G, 5.

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).

For ammonia, the State notes that a 53% reduction in (baseline) NO

emissions is projected to occur between 2013 and 2024,

so the conditions in the early years will not persist and the future year (2024) is more representative of the Valley's ambient conditions than earlier years. The 2018 PM

2.5

Plan's precursor demonstration also presents a review of District agricultural rules that control VOC emissions and also provide ammonia co-benefits. The State concludes that a 30% reduction is a reasonable upper bound on the ammonia reductions to model. Finally, the 2018 PM

2.5

Plan's precursor demonstration presents extensive support for the State's conclusion regarding an ambient excess of ammonia relative to NO

i.e.,

that particulate ammonium nitrate formation is NO

-limited, beyond that presented in the 2016 PM

2.5

Plan's precursor demonstration.

2018 Plan, App. G, 8.

3. EPA Evaluation and Proposed Action

The EPA has evaluated the State's precursor demonstrations in the 2016 PM

2.5

Plan, as supplemented and updated by the precursor demonstrations in the 2018 PM

2.5

Plan, as well as other relevant information available to the EPA, 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 with the State's conclusion that NO

emissions contribute significantly to ambient PM

2.5

levels that exceed the 2012 PM

2.5

NAAQS in the SJV and that NO

emission sources, therefore, remain subject to control requirements under subparts 1 and 4 of part D, title I of the Act. Additionally, for the reasons provided in the following paragraphs, the EPA proposes to approve the State's comprehensive precursor demonstrations for ammonia, SO

, and VOC based on a conclusion that emissions of these precursor pollutants do not contribute significantly to ambient PM

2.5

levels that exceed the 2012 PM

2.5

NAAQS in the SJV.

The State based its analyses on the latest available data and studies concerning ambient PM

2.5

formation in the SJV from precursor emissions. For the required concentration-based analysis, the State assessed the absolute annual average contribution of each precursor to ambient PM

2.5

(

i.e.,

in 2015). Given the absolute concentrations in 2015 were above the EPA's recommended contribution thresholds for both the 24-hour and annual average PM

2.5

NAAQS, the State proceeded to a sensitivity-based analysis, consistent with the PM

2.5

SIP Requirements Rule.

For the sensitivity-based analysis, the State performed its analyses in a straightforward application of the EPA's recommended approach—

i.e.,

for each modeled year and level of emissions reduction (in percentages), 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 EPA's recommended contribution threshold.

The EPA finds that the performance of the photochemical models were adequate for use in estimating the ambient PM

2.5

responses.

In particular, for the 2018 PM

2.5

Plan precursor demonstration, the State considered the EPA's recommended range of emission reductions (30% to 70%) for the 2013 base year, 2020 (an interim year), and 2024 (as a proxy for the projected 2025 attainment year for the 2012 PM

2.5

NAAQS), and quantified

the estimated response of ambient PM

2.5

concentrations to precursor emission changes in the SJV.

For the 2016 PM

2.5

Plan precursor demonstration, CARB modeled a 15% increase and 15% decrease in a precursor and took the difference between the resulting PM

2.5

concentrations to estimate the ambient PM

2.5

response to a 30% change in the precursor, rather than a straight 30% reduction, which would be expected to slightly understate the response, as described in the EPA's Ammonia Precursor TSD. Nevertheless, this is a reasonable approach and the State consulted with the EPA on whether this approach using then-available modeling runs would be acceptable.

For the 2018 PM

2.5

Plan, the model performance is discussed further 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”). See further discussion in section IV.C of this proposed rule.

The State's emissions projections in the 2016 PM

2.5

Plan and the 2018 PM

2.5

Plan show that baseline emissions of each of these precursors will decrease from the 2013 base year to 2021 and 2025, respectively (

i.e.,

none of these pollutants is projected to increase). These decreases are included in the State's modeled projections of ambient PM

2.5

levels in the SJV for purposes of demonstrating attainment and RFP. The State's sensitivity analyses are consistent with these projections, in accordance with the EPA's recommendations in the PM

2.5

Precursor Guidance.

2.5

Precursor Guidance, 35.

In the subsections that follow, we summarize below our evaluation of the State's precursor demonstrations for ammonia, SO

, and VOC for purposes of the 2012 PM

2.5

NAAQS in the SJV.

a. Ammonia Precursor Demonstration

In the 2016 PM

2.5

Plan, CARB estimates the ambient PM

2.5

response to a 30% reduction in emissions in 2025 and, in the 2018 PM

2.5

Plan, CARB estimates the ambient PM

2.5

response to both a 30% and a 70% emission reduction in 2013, 2020, and 2024. We have evaluated CARB's sensitivity-based contribution analyses for 2013, 2020, and 2024 (in the 2018 PM

2.5

Plan) and for 2025 (in the 2016 PM

2.5

Plan), and CARB's determination that 2024, as a proxy for the projected attainment year of 2025, is more representative of conditions in the SJV for purposes of a sensitivity-based analysis, as discussed in the following paragraphs. We find it appropriate for the State to consider additional information as part of its evaluation of whether the ammonia contribution is significant and to rely on the responses to the 30% modeled ammonia emissions reduction in its precursor demonstration for ammonia. We provide a detailed evaluation of the State's precursor demonstration for ammonia emissions in the EPA's Ammonia Precursor TSD.

As part of its analysis in the 2016 PM

2.5

Plan, CARB estimates that the ambient PM

2.5

response to a 30% reduction in ammonia emissions would range from 0.1 µg/m

to 0.2 µg/m

in 2025 with 3 of 16 monitoring sites having a response of 0.2 µg/m

. However, the precursor demonstration in the 2018 PM

2.5

Plan indicates that the ambient response to a 30% ammonia emission reduction would exceed the EPA's recommended contribution threshold of 0.2 µg/m

at a number of monitoring sites, primarily in the 2013 and 2020 analysis years. For example, the sensitivity results for a 30% reduction in ammonia emission reductions in 2020 (the closest analysis year to 2021), show that the ambient PM

2.5

response at 9 of 15 monitoring sites would exceed the 0.2 µg/m

threshold. We consider two lines of reasoning provided by the State to support its conclusion that ammonia emissions do not contribute significantly to ambient PM

2.5

levels that exceed the 2012 PM

2.5

NAAQS in the SJV.

First, multiple researchers have suggested that ammonia emissions are underestimated in the SJV by a factor of two to five or more.

This conclusion is based on comparing ambient and satellite measurements to model results that incorporate estimates of ammonia emissions and comparing monitoring or modeling results to what would be expected based on the size(s) of the ammonia and other precursor (

e.g.,

) emission inventories. In a supplemental transmittal,

CARB described the results of two analyses confirming the likely underestimation of ammonia emissions. CARB compared Community Multiscale Air Quality (CMAQ) model predictions of ammonia with the 2013 DISCOVER-AQ

aircraft measurements and found that ammonia was underpredicted, and noted that this would result in the response to ammonia reductions being overpredicted. CARB also compared 2017 satellite measurements of ammonia with CMAQ model predictions and found that modeled ammonia concentrations were half of the magnitude of the satellite observations at some locations, and the modeled average in the SJV was about 25% less than observed. As a result of the likely ammonia emissions underestimation, the modeled response to ammonia precursor reductions in the 2018 PM

2.5

Plan's precursor demonstration may be unrealistically large.

See,

e.g.,

Parrish, D., “Synthesis of Policy Relevant Findings from the CalNex 2010 Field Study, Final Report to the Research Division of the California Air Resources Board,” 2014, 63,

https://www.esrl.noaa.gov/csd/projects/calnex/

; and Kelly, J.T.

et al.

2018, “Modeling NH

over the San Joaquin Valley during the 2013 DISCOVER-AQ campaign,” Journal of Geophysical Research: Atmospheres, 123, 4727-4745,

https://doi.org/10.1029/2018JD028290 at 4731.

See also the EPA's Ammonia Precursor TSD for further discussion of ammonia research studies.

CARB's April 26, 2021, Precursor Clarification.

NASA, “Deriving Information on Surface conditions from COlumn and VERtically Resolved Observations Relevant to Air Quality,” available at

https://www.nasa.gov/mission_pages/discover-aq/index.html.

If ammonia emissions were increased in the modeling to correct the likely underestimation, then modeled ammonia would be more abundant relative to nitrate; particulate nitrate formation would be more NO

-limited, and less responsive to ammonia reductions; and the modeled response to ammonia reductions would be lower than is reported in the 2018 PM

2.5

Plan's precursor demonstration and likely below the EPA's recommended contribution threshold at most monitors in 2021.

In addition, an upward revision in the ammonia emission estimate would make the model response more consistent with the ambient measurement studies discussed in the submittal.

The relevant studies suggest a very low ambient sensitivity to ammonia, based on measured excess ammonia relative to NO

, the abundance of particulate nitrate relative to gaseous NO

, and the large abundance of ammonia relative to nitric acid.

The studies all conclude that there is a large amount of ammonia left over after reacting with NO

, so that ammonia emission reductions would be expected mainly to reduce the amount of ammonia excess, rather than to reduce the particulate amonium nitrate.

2018 PM

2.5

Plan, 6-7, and App. G, G-9 to G-10; the CARB 2018 Staff Report, App. C, 12-15; and Submittal Letter, Attachment A.

Lurmann et al. 2006, “Processes Influencing Secondary Aerosol Formation in the San Joaquin Valley during Winter,”

Journal of the Air & Waste Management Association

(1995) 56(12):1679-93,

https://doi.org/10.1080/10473289.2006.10464573

; Markovic

et al.,

2014, “Measurements and modeling of the inorganic chemical composition of fine particulate matter and associated precursor gases in California's San Joaquin Valley during CalNex 2010,”

Journal of Geophysical Research—Atmospheres,

119, 6853-6866,

https://doi.org/10.1002/2013JD021408.

CalNex, or California Research at the Nexus of Air Quality and Climate Change, was a NOAA-sponsored field study during summer 2010.

https://www.esrl.noaa.gov/csd/projects/calnex/.

Based on these evaluations, we find that a correction to the likely underestimation of the ammonia emission inventory would likely result in a modeled response to ammonia reductions below the 0.2 µg/m

contribution threshold in 2021.

Second, the air quality benefit of ammonia emission reductions is projected to decline steeply over time and both the Moderate and Serious area plans for the 2012 PM

2.5

NAAQS for the SJV have been submitted to the EPA. While a concentration-based analysis is the initial step for a precursor demonstration under the PM

2.5

SIP Requirements Rule,

a precursor

demonstration may then proceed to a sensitivity-based contribution analysis

to consider how sensitive ambient PM

2.5

levels would be to emissions reductions. Precursor concentration alone does not account for complications of meteorology and chemistry; ambient PM

2.5

may be relatively insensitive to emissions reductions and, in some circumstances, emissions reductions may even result in increased ambient PM

2.5

i.e.,

show a “disbenefit.”

100

40 CFR 51.1006 (a)(1)(i).

40 CFR 51.1006 (a)(1)(ii).

100

An example of a disbenefit is “sulfate replacement,” which can occur at intermediate ammonia levels when there is not enough ammonia to fully react with the SO

and NO

present. Reducing SO

emissions reduces ambient particulate ammonium sulfate. For each ammonium sulfate, two ammonium ions are freed; both can combine with a nitrate, forming two particulate ammonium nitrate molecules. The net result of the SO

emissions decrease is then an increase in ambient PM

2.5

concentration. See also the EPA's 24-hour PM

2.5

Precursor TSD, 17-18; 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.

In selecting the analysis year for a precursor demonstration, we find it appropriate to consider changes in atmospheric chemistry that may occur between the base or current year and the attainment year because the changes may ultimately affect the nonattainment area's progress toward expeditious attainment. Based on these considerations, we find it reasonable for the State to focus on the ambient PM

2.5

response to ammonia emission reductions in 2024, rather than an earlier year, as the modeled response in 2024 in the SJV better reflects the potential benefit of ammonia control measures for purposes of expeditious attainment of the 2012 PM

2.5

NAAQS. We consider the precursor demonstration in the 2018 PM

2.5

Plan as part of this evaluation, because the 2018 PM

2.5

Plan contains a Serious area attainment plan for the 2012 PM

2.5

NAAQS based on modeled emissions projections for 2024 and 2025 that are relevant to our evaluation of the ammonia precursor demonstration in the 2016 PM

2.5

Plan. The 2018 PM

2.5

Plan provides updated analyses with comprehensive modeling and additional information beyond that provided in the 2016 PM

2.5

Plan, and the 2024 model results in the 2018 PM

2.5

Plan corroborate the 2025 model results in the 2016 PM

2.5

Plan.

The State's precursor demonstrations in the 2016 PM

2.5

Plan and the 2018 PM

2.5

Plan show that ambient sensitivity to ammonia emission reductions in the SJV declines steeply over time. Between 2020 and 2024, the modeled response to a 30% ammonia emission reduction declines by 50% at the Bakersfield-Planz monitoring site, which has the highest projected PM

2.5

level, and by 37% averaged over all monitoring sites. In absolute terms, the ambient PM

2.5

response declines from 0.24 µg/m

in 2020 to 0.12 µg/m

in 2024 at Bakersfield-Planz, and from 0.23 µg/m

to 0.14 µg/m

as averaged over all monitoring sites, with the decline being generally larger for the sites with the highest projected PM

2.5

levels. Thus, between 2020 and 2024, the number of sites at which modeled sensitivity exceeds the 0.2 µg/m

threshold declines from 9 of 15 to 1 or 2 of 15.

101 102

As discussed above, ammonia sensitivity declines because of the shifting atmospheric chemistry caused by NO

emissions decreases. NO

emissions are projected to decrease 27% between 2020 and 2024 due to baseline measures (

e.g.,

existing motor vehicle controls). The decreased NO

emissions will make ammonia more abundant relative to NO

, and even less of a limiting factor on PM

2.5

formation. In other words, the model response in the future attainment year 2024 gives a more realistic assessment of the potential effect of ammonia controls than past or current conditions.

101

2018 PM

2.5

Plan, App. G, tables 4 & 5, G-11. The result for the Madera site is unclear since its monitored concentrations are biased high.

102

For 2025, the 2016 PM

2.5

Plan states there are no sites are above the contribution threshold. The sensitivities show similar declines from 2020 to 2025 of 58% for the monitoring site with the highest projected PM

2.5

level and 46% averaged over all monitoring sites. Because only a single decimal place is provided for 2025, the percent declines are more approximate. Extrapolating the 2018 PM

2.5

Plan results to 2025, the percent declines are 55% and 40%, respectively, which are comparable to those for 2024.

Moreover, given the likely underestimate in ammonia emissions in the SJV, 2024 modeling results may be more representative even of current conditions than 2020 modeling results. For example, if 2013 ammonia emissions are underestimated by a factor of three, as suggested by the CalNex summary report,

103

then the 2013 ratio of ammonia to NO

emissions of 1.04 should be about 3.1, instead. The emissions ratio of ammonia to NO

in 2024 is 2.2, which is closer to 3.1 than the emissions ratio of ammonia to NO

in 2020, which is 1.6.

104

Using 2024 modeling results partly compensates for the likely ammonia emissions underestimation.

103

Parrish, D., “Synthesis of Policy Relevant Findings from the CalNex 2010 Field Study, Final Report to the Research Division of the California Air Resources Board,” 2014, 63,

https://www.esrl.noaa.gov/csd/projects/calnex/.

104

2018 PM

2.5

Plan, App. B, tables B-2 (“NO

”) and B-5 (“Ammonia”), annual average tpd, Grand Total for San Joaquin Valley, B-7 and B-16. The ammonia to NO

ratio is 329.2/317.2 = 1.04 in 2013; 325.9/203.3 = 1.6 in 2020; and 324.6/148.9 = 2.2 in 2024.

Finally, the decision on whether to control ammonia does not affect the attainment year for the 2012 annual PM

2.5

NAAQS. From the 2020 sensitivity results,

105

a 30% reduction in ammonia emissions would reduce the projected PM

2.5

level in 2021

106

by 0.24 µg/m

. The design value would decrease from a 2020 baseline value of 14.6 µg/m

down to 14.3 µg/m

. The State uses a 30% ammonia emission reduction as an upper bound in the modeling but shows that even a 70% ammonia emission reduction would reduce the design value to only 13.8 µg/m

. The result of a 30% or even a 70% ammonia emission reduction, if those were possible, would still be well above the NAAQS level of 12.0 µg/m

. Attainment would remain impracticable in 2021. A decision to evaluate and possibly adopt additional ammonia controls in the 2016 PM

2.5

Plan would not remove the need for a Serious area plan identifying a later attainment year for the 2012 PM

2.5

NAAQS.

105

2018 PM

2.5

Plan, App. G, tables 4 and 6.

106

Sensitivity for the year 2021 is being represented by model results for 2020. Given the declining NO

emissions and corresponding decline in ammonia sensitivity, the actual PM

2.5

response to ammonia reductions for 2021 would be lower than stated.

Such reductions would also have little effect in 2025. Based on the 2024 sensitivity results,

107

if ammonia emissions were reduced by 30%, the area's 12.0 µg/m

design value would be reduced by 0.12 µg/m

, which would not be considered significant (it is below the EPA's recommended threshold of 0.2 µg/m

). A 70% reduction might lower the design value by 0.36 µg/m

to 11.7 µg/m

. Conceivably that could result in attainment of the 2012 PM

2.5

NAAQS in 2024 rather than 2025, but it is not clear whether reductions of that magnitude are feasible.

107

2018 PM

2.5

Plan, App. G, tables 5 and 7, 11-12. The response to 2025 ammonia reductions would be lower than the values stated in the text, due to the effect of declining NO

emissions.

In sum, we find that the State quantified the sensitivity of ambient PM

2.5

levels to reductions in ammonia emissions using appropriate modeling techniques that performed well; there is likely an underestimation of ammonia emissions in the SJV and, if corrected, the modeled response to ammonia reductions would be lower than reported; and the State's choice of 2024 and 2025 as the reference points for purposes of evaluating the sensitivity of

ambient PM

2.5

levels to ammonia emission reductions is well-supported. 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 2012 PM

2.5

NAAQS in the SJV.

b. SO

Precursor Demonstration0.05

As described in section IV.B.2 of this proposed rule, in the 2016 PM

2.5

Plan, CARB estimated the ambient PM

2.5

response to a 30% reduction in SO

emissions in 2025 to range from 0.1 µg/m

to 0.2 µg/m

, with half the monitoring sites having a response of 0.2 µg/m

. In the 2018 PM

2.5

Plan, CARB estimated the 2013 ambient PM

2.5

response to a 30% SO

emission reduction to range from −0.01 µg/m

to 0.07 µg/m

and estimated the ambient PM

2.5

response to a 70% SO

emission reduction to range from −0.05 µg/m

to 0.15 µg/m

108

The State also provides an emissions trend chart that shows SO

emissions to be steady at approximately 8 tpd from 2013 through 2024. Given that the relative levels of SO

and ammonia emissions over that timeframe remain similar, the State concludes that the 2013 sensitivities are also representative of future years.

109

The State also provides the ambient PM

2.5

responses in 2013, 2020, and 2024 to 30% and 70% reductions in SO

emissions, all of which are below the 0.2 µg/m

contribution threshold.

110

108

2018 PM

2.5

Plan, App. G, 15-16, tables 8 and 9.

109

2018 PM

2.5

Plan, App. G, 15.

110

CARB's September 2019 Precursor Clarification.

We note that the 2016 PM

2.5

Plan's sensitivity estimates for 2025 are at or below the EPA's recommended contribution threshold of 0.2 µg/m

, and that the 2018 PM

2.5

Plan's sensitivity estimates for 2013 are well below that threshold for both the 30% and 70% emission reduction scenarios and even negative for certain monitoring sites. Given that the latter precursor demonstration was based on updated data and an updated methodology, and the steady SO

emission levels over 2013 to 2025 (as opposed to increases), the EPA agrees with the State's conclusion that the 2013 modeled sensitivities provide a sufficient basis for the SO

precursor demonstration. The supplemental results provided by the State for 2020 and 2024 support this conclusion.

Therefore, on the basis of these modeled ambient PM

2.5

responses to SO

emission reductions in the SJV, and the facts and circumstances of the area, the EPA proposes to approve the State's demonstration that SO

emissions do not contribute significantly to ambient PM

2.5

levels that exceed the 2012 PM

2.5

NAAQS in the SJV.

c. VOC Precursor Demonstration

In the 2016 PM

2.5

Plan, CARB estimated the ambient PM

2.5

response to a 30% difference in VOC emissions in 2025 to range from −0.1 µg/m

to 0.1 µg/m

. In the 2018 PM

2.5

Plan, the State found that the ambient PM

2.5

response to VOC emission reductions were generally below the EPA's recommended contribution threshold of 0.2 µg/m

, 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.

111

2018 PM

2.5

Plan, App. G, 18-19, tables 10 and 11.

We note that the 2016 PM

2.5

Plan's sensitivity estimates for 2025 are at or below the EPA's recommended contribution threshold of 0.2 µg/m

, and that the 2018 PM

2.5

Plan's sensitivity estimates for 2020 and 2024 are well below that threshold for both the 30% and 70% emission reduction scenarios, and even negative for certain monitoring sites. The State also provides an emissions trend chart that shows VOC emissions are projected to decrease by about 30 tpd, or 9% between 2013 and 2020 as well as between 2013 and 2024, and concludes that 2013 sensitivity results are not representative into the future and that the 2020 and 2024 results are representative.

112

Finally, the State concludes that VOC emissions do not contribute significantly to PM

2.5

levels that exceed the 2012 PM

2.5

NAAQS.

112

2018 PM

2.5

Plan, App. G, 19-20.

The EPA has evaluated and agrees with the State's determination in the 2018 PM

2.5

Plan that the projected 2024 attainment year is more representative of conditions in the SJV for sensitivity-based analyses and that VOC reductions in 2024 would mostly result in a disbenefit to ambient PM

2.5

levels. The EPA agrees that the 9% VOC emissions decrease from 2013 to 2024 supports reliance on the 2024 modeling results. Furthermore, there is a large decrease in NO

emissions over this period, as described in section IV.B.2 of this proposed rule, that 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

emissions reductions are expected to result from baseline measures already in effect. Therefore, we 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 SJV; as discussed in 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 2006 NAAQS Precursor TSD”), VOC reductions led to less peroxyacetyl nitrate formation, and greater availability of nitrate to form particulate ammonium nitrate.

113

EPA's 2006 NAAQS Precursor TSD, 22.

For 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 2012 PM

2.5

NAAQS in the SJV.

C. Air Quality Modeling

1. Requirements for Air Quality Modeling

Section 189(a)(1)(B) of the CAA requires each state in which a Moderate area is located to submit a plan that includes a demonstration (including air quality modeling) of either (i) attainment of the PM

2.5

NAAQS by the applicable attainment date, or (ii) attainment by that date is impracticable. The 2016 PM

2.5

Plan includes a demonstration that attainment by the Moderate attainment date is impracticable.

The EPA's PM

2.5

modeling guidance

114

(“Modeling Guidance” and “Modeling Guidance Update”) recommends that a photochemical model, such as the Comprehensive Air Quality Model with Extensions or CMAQ, be used to simulate a base case, with meteorological and emissions inputs reflecting a base case year, to replicate concentrations monitored in that year. The model application to the base year undergoes a performance evaluation to ensure that it satisfactorily corroborates the concentrations monitored in that year. The model may then be used to simulate emissions occurring in other years required for a

plan, namely the base year (which may differ from the base case year) and future year.

115

The modeled response to the emission changes between those years is used to calculate relative response factors (RRFs) that are applied to the design value in the base year to estimate the projected design value in the future year for comparison against the NAAQS. Separate RRFs are estimated for each chemical species component of PM

2.5

, and for each quarter of the year, to reflect their differing responses to seasonal meteorological conditions and emissions. Because each species is handled separately, before applying an RRF, the base year design value must be speciated using available chemical species measurements—that is, each day's measured PM

2.5

concentration must be split into its species components. The Modeling Guidance provides additional detail on the recommended approach.

116

114

Memorandum dated November 29, 2018, from Richard Wayland, Air Quality Assessment Division, Office of Air Quality Planning and Standards (OAQPS), EPA, to Regional Air Division Directors, EPA, Subject: “Modeling Guidance for Demonstrating Air Quality Goals for Ozone, PM

2.5

, and Regional Haze,” (“Modeling Guidance”), and Memorandum dated June 28, 2011 from Tyler Fox, Air Quality Modeling Group, OAQPS, EPA, to Regional Air Program Managers, EPA, Subject: “Update to the 24 Hour PM

2.5

NAAQS Modeled Attainment Test,” (“Modeling Guidance Update”).

115

In this section, we use the terms “base case,” “base year” or “baseline,” and “future year” as described in section 2.3 of the EPA's Modeling Guidance. The “base case” modeling simulates measured concentrations for a given time period, using emissions and meteorology for that same year. The modeling “base year” (which can be the same as the base case year) is the emissions starting point for the plan and for projections to the future year, both of which are modeled for the attainment demonstration. Modeling Guidance, 37-38. Note that CARB sometimes uses “base year” synonymously with “base case” and “reference year” instead of “base year.”

116

Modeling Guidance, section 4.4, “What is the Modeled Attainment Tests for the Annual Average PM

2.5

NAAQS.”

The EPA has not issued modeling guidance specific to impracticability demonstrations but believes that a state seeking to make such a demonstration generally should provide air quality modeling similar to that required for an attainment demonstration.

117

The main difference is that for an impracticability demonstration, the implementation of the SIP control strategy (including RACM) does not result in attainment of the standard by the Moderate area attainment date.

117

81 FR 58010, 58048.

For an attainment demonstration, a thorough review of all modeling inputs and assumptions (including consistency with EPA guidance) is especially important because the modeling must ultimately support a conclusion that the plan (including its control strategy) will provide for timely attainment of the applicable NAAQS. In contrast, for an impracticability demonstration, the end point is a reclassification to Serious, which triggers the requirement for a new Serious area attainment plan with a new air quality modeling analysis, and a new control strategy.

118

Thus, the Serious area planning process would provide an opportunity to refine the modeling analysis and/or correct any technical shortcomings in the impracticability demonstration. Therefore, the burden of proof will generally be lower for an impracticability demonstration compared to an attainment demonstration.

119

118

CAA section 189(b)(1).

119

81 FR 58010, 58049.

2. Summary of State's Air Quality Modeling

In the 2016 PM

2.5

Plan, the State discussed its air quality modeling in section 2.3 (“Summary of Modeling Results”) and Appendix A (“Air Quality Modeling”) and concludes that it is not practicable to attain the 2012 PM

2.5

NAAQS in the SJV by December 31, 2021. The State used CMAQ (version 5.02) to model three simulations: A 2013 base year to demonstrate that the model reasonably reproduced observed PM

2.5

concentrations, a 2013 reference base year simulation that excluded exceptional events such as wildfires, and a 2021 future year based on the reference year but using projected 2021 emissions. For the base year simulation, CARB conducted photochemical modeling with the CMAQ model using inputs developed from routinely available meteorological and air quality data, as well as more detailed and extensive data from the DISCOVER-AQ field study conducted in January to February 2013.

The State then generated site- and species-specific RRFs for the ammonium ion, nitrate ion, sulfate ion, organic carbon, elemental carbon, and a combined grouping of other primary PM

2.5

material for the 2021 future year simulation and calculated future year design values by multiplying the species- and site-specific RRFs by the corresponding quarterly mean component concentrations. The State summed the quarterly mean components to determine quarterly mean PM

2.5

concentrations, which it subsequently averaged to determine the annual design values. The future year design values reflect the weighted quarterly average concentration from the projections of five years of data. The State projected future year annual PM

2.5

design values for the 2021 Moderate area attainment year for the 2012 PM

2.5

NAAQS.

The 2021 baseline simulation used emission levels projected from the 2013 base year that reflect all control measures adopted by the time of the 2016 PM

2.5

Plan's development that would be implemented by December 31, 2021. This simulation indicates that the 2012 annual PM

2.5

standard will not be met in the SJV in 2021. The projected 2021 control scenario design value is 14.8 µg/m

at Bakersfield-Planz, which is typically the monitoring site that records the highest PM

2.5

levels in the SJV.

The 2018 PM

2.5

Plan includes a modeled demonstration projecting that the SJV will attain the 2012 annual PM

2.5

NAAQS by December 31, 2025. It also includes a modeled demonstration projecting attainment of the 1997 annual PM

2.5

NAAQS by December 31, 2020, with a design value of 14.6 µg/m

at Bakersfield-Planz. While the plan does not explicitly have a demonstration of impracticability of attaining the 2012 PM

2.5

NAAQS by 2021, the latter projections of annual PM

2.5

concentrations in 2020 provides additional information on which to judge the practicability of attaining by 2021 in that it is the closest analysis year available and represents modeling based on updated data. These projections lend support for the 2016 PM

2.5

Plan indication that the 2012 annual PM

2.5

standard will not be met in the SJV in 2021.

The Plan's primary discussion of the photochemical modeling appears in Appendix K (“Modeling Attainment Demonstration”) of the 2018 PM

2.5

Plan. The State briefly summarizes the area's air quality problem in Chapter 2.2 (“Air Quality Challenges and Trends”) and summarizes the modeling results in Chapter 6.4 (“Attainment Demonstration and Modeling”) of the 2018 PM

2.5

Plan. The State provides a conceptual model of PM

2.5

formation in the SJV as part of the modeling protocol in Appendix L (“Modeling Protocol”). Appendix J (“Modeling Emission Inventory”) describes emission input preparation procedures. The State presents additional relevant information in Appendix C (“Weight of Evidence Analysis”) of the CARB 2018 Staff Report, which includes ambient trends and other data in support of the demonstration of attainment by 2025.

3. EPA Evaluation and Conclusion

CARB's air quality modeling approach investigated the many interconnected facets of modeling ambient PM

2.5

in the SJV, including model input preparation, model performance evaluation, use of the model output for the numerical NAAQS attainment test, and modeling documentation. Specifically, this required the development and evaluation of a conceptual model, modeling protocol, episode (

i.e.,

base

year) selection, modeling domain, CMAQ model selection, initial and boundary condition procedures, meteorological model choice and performance, modeling emissions inventory preparation procedures, model performance, attainment test procedure, and adjustments to baseline air quality for modeling. These analyses are generally consistent with the EPA's recommendations in the Modeling Guidance.

The model performance evaluation in section 5.2 (“CMAQ Model Evaluation”) of both Appendix A of the 2016 PM

2.5

Plan and Appendix K of the 2018 PM

2.5

Plan included statistical and graphical measures of model performance.

The EPA previously evaluated and approved the modeling conducted for the 2006 24-hour PM

2.5

NAAQS as part of the 2018 PM

2.5

Plan; see 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 2006 NAAQS Modeling TSD”) accompanying that action for details.

120

The conclusions in the EPA's 2006 NAAQS Modeling TSD focused on the 24-hour PM

2.5

NAAQS; in this notice we extend the evaluation with information specific to the annual PM

2.5

NAAQS. Unless otherwise noted, the discussion applies to both the modeling in both the 2016 PM

2.5

Plan (Appendix A) and 2018 PM

2.5

Plan (Appendix K), since they followed the same model platform development procedures, and had identical meteorological inputs, very similar emissions inputs, and very similar model performance.

120

The model performance is discussed further in section J (“Air Quality Model Performance”) of the EPA's 2006 NAAQS Modeling TSD.

Most aspects of the 2018 PM

2.5

Plan modeling and the EPA's evaluation of it are the same for the 24-hour and the annual averaging times, and the EPA has found them adequate. These include the modeling protocol, choice of model, meteorological modeling, modeling emissions inventory, choice of model, modeling domain, and procedures for model performance evaluation. One aspect that differs between the 24-hour and annual averaging times is the specific calculation procedure for estimating a future design value. In the Modeling Guidance, for both averaging times, the model is used to calculate RRFs, the ratio of modeled future concentrations to base year concentrations, and the RRF is applied to monitored base year concentrations. This is done for each monitor, PM

2.5

species, and calendar quarter. But for the 24-hour averaging time, the procedure uses the highest individual concentration days in each quarter, whereas for the annual average, it uses the average of all days in each quarter. The EPA previously found that the procedures used in the 2018 PM

2.5

Plan for the 24-hour PM

2.5

NAAQS generally followed the EPA's recommendations and were adequate. For the current action, the EPA finds that State procedures

121

for estimating future design values for the annual PM

2.5

NAAQS generally followed the EPA's recommendations and are adequate.

121

2018 PM

2.5

Plan, App. K, 18.

Another modeling aspect that can differ between 24-hour and annual average is the focus of the model performance evaluation on the respective averaging times. For the 24-hour average, it is especially important that modeled concentrations on the highest days are comparable to those on the highest monitored days, since calculation of the design value for the 24-hour PM

2.5

NAAQS uses the 98th percentile concentrations,

i.e.,

the top 2%. For the annual average, peak concentrations continue to be important, but lower concentration days are also important since all days are included in the average. Under- and over-predictions on non-peak days may average out and have little overall effect on the modeled annual concentration, but systematic underprediction on non-peak days could lead to model underprediction of the annual average concentration. This problem of model bias is mitigated by the use of the model in a relative sense as recommended in the Modeling Guidance. In the RRF, model bias “cancels out” to a degree since it would be present in both its numerator (future year) and its denominator (base year); and applying the RRF to monitored base year concentration anchors the final model prediction to unbiased real-world concentrations. Further, RRFs are calculated on a quarterly basis, so the bias correction can better account for emissions sources and atmospheric chemistry that differ between the seasons.

The 2018 PM

2.5

Plan did not have a separate model performance evaluation for the 24-hour and annual PM

2.5

averaging times; it used statistical and graphical analyses applicable to both. For the most part, the EPA's 2006 NAAQS Modeling TSD did not distinguish between the two averaging times either but drew conclusions for the 24-hour averaging time rather than the annual averaging time. It did note a large negative bias (underprediction) in the ammonium and nitrate performance statistics

122

for the 2nd quarters for monitoring sites in Bakersfield, Fresno, and Visalia; and we add here that the 3rd quarter has similar negative bias. The negative model bias in the 2016 PM

2.5

Plan was slightly better than in the 2018 PM

2.5

Plan,

i.e.,

the underprediction was slightly less. Underprediction of total PM

2.5

in the 2nd and 3rd quarters is also evident in time series plots for most monitoring sites, though by only a small amount for several monitoring sites.

123

The EPA's 2006 NAAQS Modeling TSD noted that since those quarters have concentrations that are less than half of those in the 1st and 4th, this may not be much of a concern for the annual average. (It is of less concern for the 24-hour average, since peak 24-hour concentrations occur in winter,

i.e.,

in the 1st and 4th quarters.) As noted above, the RRF procedure removes much of this bias, so the underprediction in the model performance evaluation does not directly translate into an underpredicted 2020 design value. In addition, the 2018 PM

2.5

Plan shows that annual model performance for each PM

2.5

species is quite good relative to that seen in other modeling studies, for multiple performance statistics.

124

122

2016 PM

2.5

Plan, App. A 48

ff,

tables 15 through 18; 2018 PM

2.5

Plan, App. K, 48

ff,

tables 20 through 23.

123

2016 PM

2.5

Plan, App. A, 107

ff,

Supplemental materials, Figures S.37-S.52; 2018 PM

2.5

Plan, App. K, 131

ff,

Supplemental materials, Figures S.41-S.52.

124

2016 PM

2.5

Plan, App. A, 46, Figure 13; 2018 PM

2.5

Plan, App. K, 54, Figure 14.

The high days are generally captured by the model, even though some are underpredicted in December at certain monitoring sites such as Fresno. Overall, the modeled site maxima are comparable to the measurements; also, the frequency of high and low days generally matches observations so the annual as well as the daily model performance is acceptable.

The EPA evaluated the State's choice of model for the impracticability demonstration and the extensive discussion in the 2016 PM

2.5

Plan about modeling procedures, tests, and performance analyses, as well as the State's modeling choices, procedures, test, and performance analyses in the 2018 PM

2.5

Plan.

125

We find the State's analyses consistent with the EPA's guidance on modeling for PM

2.5

attainment planning purposes. Based on these reviews, we find that the modeling in the 2016 PM

2.5

Plan and 2018 PM

2.5

Plan is adequate for the purposes of supporting the RFP demonstration and the demonstration of impracticability in the 2016 PM

2.5

Plan.

125

For a more detailed summary of the State's air quality modeling in the 2018 PM

2.5

Plan with respect to the 2006 24-hour PM

2.5

NAAQS, rather than the 2012 annual PM

2.5

NAAQS, please refer to the EPA's 2006 NAAQS Modeling TSD.

D. Reasonably Available Control Measures and Control Strategy

1. Requirements for RACM/RACT and Control Strategies

The general subpart 1 attainment plan requirement for RACM/RACT is described in CAA section 172(c)(1), which requires that attainment plan submissions “provide for the implementation of all reasonably available control measures as expeditiously as practicable (including such reductions in emissions from existing sources in the area as may be obtained through the adoption, at a minimum, of reasonably available control technology)” and provide for attainment of the NAAQS.

The attainment planning requirements specific to PM

2.5

under subpart 4 likewise impose an obligation upon states with nonattainment areas classified as Moderate to develop attainment plans that require RACM/RACT on sources of direct PM

2.5

and all PM

2.5

plan precursors. CAA section 189(a)(1)(C) requires that Moderate area PM

2.5

SIPs contain provisions to assure that RACM/RACT are implemented no later than four years after designation of the area. The EPA reads CAA section 172(c)(1) and 189(a)(1)(C) together to require that attainment plans for Moderate nonattainment areas provide for the implementation of RACM/RACT for existing sources of PM

2.5

and those PM

2.5

precursors subject to control in the nonattainment area as expeditiously as practicable but no later than four years after designation.

126

This interpretation is consistent with guidance provided in the General Preamble, 13540.

The PM

2.5

SIP Requirements Rule defines RACM as “any technologically and economically feasible measure that can be implemented in whole or in part within 4 years after the effective date of designation of a PM

2.5

nonattainment area and that achieves permanent and enforceable reductions in direct PM

2.5

emissions and/or PM

2.5

plan precursor emissions from sources in the area. RACM includes reasonably available control technology (RACT).”

127

The EPA has historically defined RACT as the lowest emission limitation that a particular stationary source is capable of meeting by the application of control technology that is reasonably available considering technological and economic feasibility.

128

127

81 FR 58010, 58035.

128

General Preamble, 13541 and 57 FR 18070, 18073-18074.

Under the PM

2.5

SIP Requirements Rule, those control measures that otherwise meet the definition of RACM but “can only be implemented in whole or in part during the period beginning 4 years after the effective date of designation of a nonattainment area and no later than the end of the sixth calendar year following the effective date of designation of the area” must be adopted and implemented as “additional reasonable measures.”

129

40 CFR 51.1000, 51.1009(a)(4)(i)(B), and 51.1009(a)(4)(ii)(B).

States must provide written justification in a SIP submission for eliminating potential control options from further review on the basis of technological or economic infeasibility.

130

An evaluation of technological feasibility may include consideration of factors such as a source's process and operating conditions, raw materials, physical plant layout, and non-air quality and energy impacts (

e.g.,

increased water pollution, waste disposal, and energy requirements).

131

An evaluation of economic feasibility may include consideration of factors such as cost per ton of pollution reduced (cost-effectiveness), capital costs, and operating and maintenance costs.

132

Absent other indications, the EPA presumes that it is reasonable for similar sources to bear similar costs of emission reductions. Economic feasibility of RACM/RACT is thus largely informed by evidence that other sources in a source category have in fact applied the control technology, process change, or measure in question in similar circumstances.

133

130

40 CFR 51.1009(a)(3).

131

40 CFR 51.1009(a)(3); see also 57 FR 18070, 18073-18074.

132

Id.

133

57 FR 18070, 18074.

Consistent with these requirements, CARB and SJVUAPCD must implement RACM, including RACT, for sources of direct PM

2.5

and PM

2.5

plan precursors no later than April 15, 2019, and must implement additional reasonable measures for these sources no later than December 31, 2021.

2. Summary of State's Control Strategy

The RACM/RACT evaluation for sources of direct PM

2.5

and NO

emissions in the SJV area is presented in Chapter 3 of the 2016 PM

2.5

Plan and in Attachment 1 and Attachment 2 to the 2016 PM

2.5

Plan. Attachment 1 to the 2016 PM

2.5

Plan contains (1) a copy of the BACM/BACT and MSM control strategy evaluation for stationary and area sources that the District adopted on April 16, 2015, as part of its “2015 Plan for the 1997 PM

2.5

Standard” (“2015 PM

2.5

Plan”), and (2) a copy of the RACM/RACT control strategy evaluation for stationary and area sources that the District adopted on June 16, 2016, as part of its “2016 Plan for the 2008 8-Hour Ozone Standard” (“2016 Ozone Plan”).

134

Attachment 2 to the 2016 PM

2.5

Plan contains (1) a copy of the BACM/BACT and MSM control strategy evaluation for mobile sources that CARB adopted on May 21, 2015, as part of the 2015 PM

2.5

Plan, and (2) a copy of the RACM/RACT control strategy evaluation for mobile sources that CARB adopted on July 21, 2016, as part of the 2016 Ozone Plan.

135

134

2016 PM

2.5

Plan, Attachment 1 (comprising 2015 PM

2.5

Plan, App. C (“BACM and MSM for Stationary and Area Sources”)) and 2016 Ozone Plan, App. C (“Stationary and Area Source Control Strategy Evaluations”). See also SJVUAPCD Governing Board Resolution 15-4-7A, April 16, 2015 (adopting the 2015 PM

2.5

Plan) and SJVUAPCD Governing Board Resolution 16-6-20, June 16, 2016 (adopting the 2016 Ozone Plan).

135

2016 PM

2.5

Plan, Attachment 2 (comprising 2015 PM

2.5

Plan, App. D (“BACM and MSM for Mobile Sources (Provided by ARB)”) and 2016 Ozone Plan, App. D (“Mobile Source Control Strategy”). See also CARB Resolution 15-9, May 21, 2015 (adopting the 2015 PM

2.5

Plan) and CARB Resolution 16-8, July 21, 2016 (adopting the 2016 Ozone Plan).

The 2015 PM

2.5

Plan and 2016 Ozone Plan contain comprehensive analyses to identify potential emission reduction opportunities for sources of direct PM

2.5

and NO

emissions and to determine whether additional measures would be technologically and economically feasible for implementation in the SJV.

136

The District states in the 2016 PM

2.5

Plan that it has not identified any new emission control technologies that could further reduce emissions in the SJV area, that the cost of technologies recently found not to be cost-effective has not changed, and that potential additional measures remain economically infeasible, consistent with the analyses and conclusions in the 2015 PM

2.5

Plan and the 2016 Ozone Plan.

137

Based on these analyses, the District concludes that the 2016 PM

2.5

Plan satisfies the RACM/RACT requirement for stationary and area sources of direct PM

2.5

and NO

emissions. The 2018 PM

2.5

Plan, submitted May 10, 2019, supplements these analyses by providing updated evaluations of potential control measures for sources of direct PM

2.5

and NO

emissions and the District's rationale for finding that additional

control measures are not technologically and economically feasible for implementation in the SJV.

138

136

2016 PM

2.5

Plan, Ch. 3, 3-5 to 3-6.

137

Id.

138

2018 PM

2.5

Plan, App. C (“Stationary Source Control Measure Analyses”).

With respect to mobile sources, the 2016 PM

2.5

Plan states that CARB has implemented the most stringent mobile source emissions control program in the nation, including emission standards for new vehicles, in-use programs for exiting vehicles and fleets, cleaner fuels, and incentive programs to accelerate penetration of cleanest vehicles.

139

CARB states that its analyses of these mobile source control measures are presented in the 2015 PM

2.5

Plan and the 2016 Ozone Plan (included as Attachment 2 to the 2016 PM

2.5

Plan) and states that there are no additional reasonably available control measures that would advance attainment of the PM

2.5

NAAQS in the SJV.

140

Based on these analyses, CARB concludes that the 2016 PM

2.5

Plan satisfies the RACM/RACT requirement for mobile sources of direct PM

2.5

and NO

emissions. The 2018 PM

2.5

Plan, submitted May 10, 2019, supplements these analyses by providing updated evaluations of CARB's mobile source control measures and its rationale for finding that additional control measures are not technologically and economically feasible for implementation in the SJV at this time.

141

139

2016 PM

2.5

Plan, 3-6.

140

CARB 2016 Staff Report, 13.

141

2018 PM

2.5

Plan, App. D (“Mobile Source Control Measure Analyses”).

Finally, with respect to transportation control measures (TCMs), the 2016 PM

2.5

Plan states that the eight county metropolitan planning organizations (MPOs) of the SJV (“SJV MPOs”) identified and evaluated all TCMs during development of the plan.

142

The plan states that the SJV MPOs implement TCMs in CAA section 108(f) consistent with the Congestion Mitigation and Air Quality cost effectiveness policy when developing each MPO's Regional Transportation Plan. In 2016 the Valley MPOs revisited the minimum cost effectiveness standard for TCMs during the development of the MPOs' 2017 Federal Transportation Improvement Program.

143

The District concludes that the Valley MPOs are implementing all reasonable TCMs under the MPOs' jurisdictions and that adoption of additional TCMs would not expedite attainment of the 2012 PM

2.5

NAAQS in the SJV.

144

The 2018 PM

2.5

Plan, submitted May 10, 2019, supplements these analyses by providing an updated discussion of the transportation control measures being implemented in the SJV.

145

142

2016 PM

2.5

Plan, 3-6.

143

2016 PM

2.5

Plan, 3-23 to 3-24. See also 2016 PM

2.5

Plan, Attachment 2, App. D, section D.2.2 (D-16 through D-18) and Attachment D (“Adopted Transportation Control Measures”).

144

2016 PM

2.5

Plan, 3-6.

145

2018 PM

2.5

Plan, App. D, D-127 to D-128 (noting that the MPOs revisited the minimum cost effectiveness standard during the development of their 2018 Regional Transportation Plans and 2019 Federal Transportation Improvement Program and concluded that they were implementing all reasonable transportation control measures).

3. EPA's Evaluation and Proposed Action

We have reviewed the State and District's demonstrations in the 2016 PM

2.5

Plan concerning RACM/RACT and additional reasonable measures for mobile, stationary, and area sources of direct PM

2.5

and one PM

2.5

plan precursor (

i.e.,

) in the SJV. Our evaluation relies primarily on our previous evaluations of the State and District rules in connection with our February 12, 2019 approval of the SJV RACM demonstration for the 2008 ozone NAAQS (for NO

emission sources)

146

and in connection with our July 22, 2020 approval of the State and District's demonstrations to meet the BACM (including BACT) and MSM requirements for the 2006 PM

2.5

NAAQS.

147

We provide a detailed discussion of these evaluations in the technical support document for this proposed rule.

148

Based on these reviews, we propose to find that the District's rules provide for the implementation of RACM and additional reasonable measures

149

for stationary and area sources of direct PM

2.5

and NO

and that CARB's current program implements RACM and additional reasonable measures for mobile sources of direct PM

2.5

and NO

emissions for purposes of the 2012 PM

2.5

NAAQS in the SJV.

146

84 FR 3302.

147

85 FR 44192 (final rule approving 2018 PM

2.5

Plan as meeting, inter alia, BACM/BACT and MSM requirements for 2006 PM

2.5

NAAQS). Because the RACM/RACT and additional reasonable measure control strategy in the 2016 PM

2.5

Plan is very similar to the BACM/BACT and MSM control strategy in the 2018 PM

2.5

Plan, and because the State's and District's control measure evaluations in the 2016 PM

2.5

Plan substantially overlap with their BACM/BACT and MSM control evaluations in the 2018 PM

2.5

Plan, we rely primarily on our evaluation of the State's and District's BACM/BACT and MSM control measure evaluations in the 2018 PM

2.5

Plan (see proposed rule, 85 FR 17382 (March 27, 2020) and final rule, 85 FR 44192) to support our evaluation of the RACM/RACT and additional reasonable measure control strategy in the 2016 PM

2.5

Plan.

148

EPA, Region IX, Air Division, “Technical Support Document, EPA Evaluation of RACM/RACT and Additional Reasonable Measures, San Joaquin Valley Moderate Area Plan for the 2012 PM

2.5

NAAQS,” August 2021.

149

The 2018 PM

2.5

Plan identifies Rule 4901 (“Wood Burning Fireplaces and Wood Burning Heaters”), as amended June 20, 2019, as an additional reasonable measure that is scheduled for implementation beginning in 2020. 2018 PM

2.5

Plan, Table 4-4 (“Proposed Regulatory Measures”). The EPA approved Rule 4901 into the California SIP on July 22, 2020. 85 FR 44206 (final rule approving Rule 4901) and 85 FR 44192 (determination that Rule 4901 implements BACM and MSM for residential wood burning).

With respect to transportation controls, we find that the SJV MPOs have well-established TCM development programs in which TCMs are continuously identified, reviewed, and evaluated throughout the transportation planning process. Overall, we believe that the programs developed and administered by CARB and the SJV MPOs provide for the implementation of RACM and additional reasonable measures for sources of direct PM

2.5

and NO

in the SJV.

For these reasons, we propose to find that the 2016 PM

2.5

Plan provides for the implementation of RACM and additional reasonable measures for all sources of direct PM

2.5

and NO

as expeditiously as practicable, for purposes of implementing the 2012 PM

2.5

NAAQS in the SJV in accordance with the requirements of CAA section 189(a)(1)(C) and 40 CFR 51.1009.

E. Nonattainment New Source Review Requirements Under CAA Section 189(e)

Section 189(e) of the CAA specifically requires that the control requirements applicable to major stationary sources of direct PM

2.5

also apply to major stationary sources of PM

2.5

precursors, except where the Administrator determines that such sources do not contribute significantly to PM

2.5

levels that exceed the standards in the area.

150

The control requirements applicable to major stationary sources of direct PM

2.5

in a Moderate PM

2.5

nonattainment area include, at a minimum, the requirements of an NNSR permit program meeting the requirements of CAA sections 172(c)(5) and 189(a)(1)(A). In the PM

2.5

SIP Requirements Rule, we established a deadline for states to submit NNSR plan revisions to implement the PM

2.5

NAAQS 18 months after an area is initially designated and classified as a Moderate nonattainment area.

151

150

General Preamble, 13539 and 13541-13542.

151

81 FR 58010, 58115.

California submitted NNSR SIP revisions for the SJV to address the subpart 4 requirements for Moderate PM

2.5

nonattainment areas on May 19,

2011.

152

The EPA fully approved these SIP revisions on September 17, 2014.

153

California also submitted NNSR SIP revisions for the SJV to address the subpart 4 requirements for Moderate and Serious PM

2.5

nonattainment areas on November 20, 2019. The EPA is evaluating this SIP submission and will act on it in a separate rulemaking. Accordingly, in this action, the EPA is not addressing the NNSR control requirements that apply to major stationary sources of direct PM

2.5

and PM

2.5

precursors in the SJV under CAA section 189(e).

152

Letter dated May 19, 2011, from Robert D. Fletcher, Deputy Executive Officer, CARB, to Jared Blumenfeld, Regional Administrator, EPA Region IX.

153

79 FR 55637.

F. Demonstration That Attainment by Moderate Area Attainment Date Is Impracticable

1. Requirements for Attainment/Impracticability of Attainment Demonstrations

Section 189(a)(1)(B) of the CAA requires that each Moderate area attainment plan include a demonstration that the plan provides for attainment by the applicable Moderate area attainment date or, alternatively, that attainment by such date is impracticable. This provision explicitly requires that a demonstration of attainment be based on air quality modeling but does not require such modeling for an impracticability demonstration. Although the EPA expects that most impracticability demonstrations will also be supported by air quality modeling, it may be possible in some cases to support an impracticability demonstration with ambient PM

2.5

data and other relevant non-modeling information.

154

81 FR 58010, 58048 and 58049.

Section 188(c) of the CAA states, in relevant part, that the Moderate area attainment date “shall be as expeditiously as practicable but no later than the end of the sixth calendar year after the area's designation as nonattainment . . . .” For the SJV, which was initially designated as nonattainment for the 2012 PM

2.5

standard effective April 15, 2015, the applicable Moderate area attainment date under section 188(c) for this standard is as expeditiously as practicable but no later than December 31, 2021.

In SIP submissions that demonstrate impracticability, the state should document how its required control strategy in the attainment plan represents the application of RACM/RACT and additional reasonable measures, at minimum, to existing sources. The EPA believes it is appropriate to require adoption of all available control measures that are reasonable,

i.e.,

technologically and economically feasible, in areas that do not demonstrate timely attainment, even where those measures cannot be implemented within the 4-year timeframe for implementation of RACM/RACT under CAA section 189(a)(1)(C). The impracticability demonstration will then be based on a showing that the area cannot attain by the applicable attainment date, notwithstanding implementation of the required controls.

2. Summary of State's Impracticability Demonstration

The 2016 PM

2.5

Plan includes a demonstration, based on air quality modeling, that even with the implementation of RACM/RACT and additional reasonable measures for all appropriate sources, attainment by December 31, 2021, is not practicable. The impracticability demonstration is included in Appendix A of the 2016 PM

2.5

Plan. As described in section IV.C.2 of this proposed rule, the projected 2021 control scenario design value is 14.8 µg/m

at Bakersfield-Planz, which is typically the monitoring site that records the highest PM

2.5

levels in the SJV.

As further described in section IV.C.2 of this proposed rule, the 2018 PM

2.5

Plan includes a modeled demonstration that projects annual PM

2.5

concentrations in 2020 that provides additional information on which to judge the practicability of attaining by 2021 in that it is the closest analysis year available and represents modeling based on updated data. These projections lend support for the 2016 PM

2.5

Plan conclusion that the 2012 annual PM

2.5

standard will not be met in the SJV in 2021.

Table 3 shows the projected annual PM

2.5

concentrations at the four PM

2.5

monitoring sites in the SJV that are equipped with comprehensive particulate matter species characterization, as well as Bakersfield-Planz, given that it is the site with the highest annual PM

2.5

concentrations in the base year and projected future year. From the 2016 PM

2.5

Plan, the projections are for 2021 (latest permissible Moderate area attainment year); from the 2018 PM

2.5

Plan, the projections are for 2020 (the analysis year closest to 2021).

Table 3—Projected Annual PM

2.5

Concentrations at Selected Monitoring Sites in the San Joaquin Valley

[µg/m

]

Site location

2016 PM

2.5

Plan

2013

2021

Difference

(2013-2021)

2018 PM

2.5

Plan

2013

2020

Difference

(2013-2021)

Bakersfield-Planz

17.3

14.8

−2.5

17.2

14.6

−2.6

Bakersfield-California Ave

16.0

13.6

−2.4

16.0

13.5

−2.5

Visalia North Church

16.2

13.7

−2.5

16.2

13.5

−2.7

Fresno-Garland

15.0

12.9

−2.1

15.0

12.4

−2.6

Modesto-14th St

13.0

11.2

−1.8

13.0

11.0

−2.0

Sources

: 2016 PM

2.5

Plan, Table 2-2, and 2018 PM

2.5

Plan, App. K, Table 25.

3. EPA Evaluation and Proposed Action

The impracticability demonstration in the 2016 PM

2.5

Plan is based on air quality modeling that is generally consistent with applicable EPA guidance. We find the modeling adequate to support the impracticability demonstration in the plan, as discussed in section IV.C.3 of this notice. Similarly, the attainment modeling demonstration in the 2018 PM

2.5

Plan is generally consistent with applicable EPA guidance and provides additional support that it is impracticable to attain the 2012 PM

2.5

NAAQS by 2021.

We have also evaluated the State's control measure demonstration, which relies on its BACM/MSM

demonstration, as updated by the 2018 PM

2.5

Plan, and find that it provides for the expeditious implementation of all RACM/RACT and additional reasonable measures that may feasibly be implemented at this time, consistent with the requirements of CAA sections 172(c)(1) and 189(a)(1)(C) for the 2012 PM

2.5

NAAQS in the SJV, as discussed in section IV.D of this notice.

Finally, we have reviewed available monitored data to assess the practicability of attaining by 2021. Specifically, the certified 2018-2020 annual average design value for SJV is 17.6 µg/m

(at Bakersfield-Planz), with exceedances of the 12.0 µg/m

standard throughout the area.

155

We note that the SJV may have experienced higher than normal PM

2.5

concentrations in 2018 and 2020 due to wildfires in the surrounding areas during the summer and fall months.

156

This monitored data similarly supports the State's demonstration that it is impracticable to attain the 2012 PM

2.5

NAAQS by the end of 2021.

155

EPA design value workbook dated May 24, 2021, “pm25_designvalues_2018_2020_final_05_24_21.xlsx,” worksheets “Table 1a” and “Table 5a.” The certified design value includes all available data; no data flagged for exceptional events have been excluded. The EPA's Air Quality System (AQS) contains ambient air pollution data collected by federal, state, local, and tribal air pollution control agencies from thousands of monitors. More information is available at:

https://www.epa.gov/aqs.

See also EPA, 2010-2020 AQS Design Value Report, AMP480, June 30, 2021.

156

Concentrations at all 17 monitors in the SJV with data spanning 2018 to 2020 are significantly higher in 2018 and 2020 relative to concentrations in 2019, possibly due to the wildfires in those years. 86 FR 38652, 38665, Table 5 (July 22, 2021) (proposed rule on the 2018 PM

2.5

Plan for the 1997 annual PM

2.5

NAAQS of 15.0 µg/m

). Notwithstanding the potential effect of wildfires, ambient PM

2.5

levels in the SJV remain well above the 2012 PM

2.5

NAAQS standard of 12.0 µg/m

Based on this evaluation, we propose to approve the State's demonstration in the 2016 PM

2.5

Plan that attainment of the 2012 PM

2.5

NAAQS in the SJV by the Moderate area attainment date of December 31, 2021, is impracticable, consistent with the requirements of CAA section 189(a)(1)(B)(ii). On this basis, we also propose to reclassify the SJV as a Serious nonattainment area, which would trigger requirements for the State to submit a Serious area attainment plan consistent with the requirements of subparts 1 and 4 of part D, title I of the Act (as described in section V of this notice).

G. Reasonable Further Progress and Quantitative Milestones

1. Requirements for Reasonable Further Progress and Quantitative Milestones

Section 172(c)(2) of the CAA states that all nonattainment area plans shall require RFP. In addition, CAA section 189(c) requires that all PM

2.5

nonattainment area plans include quantitative milestones that the state must achieve every three years until the area is redesignated to attainment and that demonstrate RFP. Section 171(1) defines RFP as “such annual incremental reductions in emissions of the relevant air pollutant as are required by [Part D] or may reasonably be required by the Administrator for the purpose of ensuring attainment of the applicable [NAAQS] by the applicable date.” Neither subpart 1 nor subpart 4 of part D, title I of the Act requires a set percentage of emission reductions that states must achieve in any given year for purposes of satisfying the RFP requirement.

For purposes of the PM

2.5

NAAQS, the EPA has interpreted the RFP requirement to require that nonattainment area plans show annual incremental emission reductions sufficient to maintain generally linear progress toward attainment by the applicable deadline.

157

As discussed in the EPA's guidance in the General Preamble Addendum,

158

requiring linear progress in reductions of direct PM

2.5

and any individual precursor in a PM

2.5

plan may be appropriate in the following situations:

157

59 FR 41998, 42015.

158

Id.

• The pollutant is emitted by a large number and range of sources,

• the relationship between any individual source or source category and overall air quality is not well known,

• a chemical transformation is involved (

e.g.,

secondary particulate contributes significantly to PM

2.5

levels over the standard), and/or

• the emission reductions necessary to attain the PM

2.5

standard are inventory-wide.

159

Id.

The General Preamble Addendum indicates that requiring linear progress may be less appropriate in other situations, such as in situations where:

• there are a limited number of sources of direct PM

2.5

or a precursor,

• the relationships between individual sources and air quality are relatively well defined, and/or

• the emission control systems utilized (

e.g.,

at major point sources) will result in a swift and dramatic emission reductions.

In nonattainment areas characterized by any of these latter conditions, RFP may be better represented as stepwise progress as controls are implemented and achieve significant reductions soon thereafter. For example, if an area's nonattainment problem can be attributed to a few major sources, the EPA's guidance indicates that “RFP should be met by `adherence to an ambitious compliance schedule' which is likely to periodically yield significant emission reductions of direct PM

2.5

or a PM

2.5

precursor.”

160

Id.

Attainment plans for the PM

2.5

NAAQS must include detailed schedules for compliance with emission regulations in the nonattainment area and provide corresponding emissions projections for each applicable milestone year that represent generally linear or stepwise progress in reducing emissions on an annual basis.

161

In reviewing an attainment plan under subpart 4, the EPA considers whether the annual incremental emission reductions to be achieved are reasonable in light of the statutory objective of timely attainment. Although early implementation of the most cost-effective control measures is often appropriate, states should consider both cost-effectiveness and pollution reduction effectiveness when developing implementation schedules for control measures and may implement measures that are more effective at reducing PM

2.5

earlier to provide greater public health benefits.

162

161

40 CFR 51.1012(a) and 59 FR 41998, 42016.

162

Id.

The PM

2.5

SIP Requirements Rule establishes specific regulatory requirements for purposes of satisfying the Act's RFP requirements and provides related guidance in the preamble to the rule. Specifically, under the PM

2.5

SIP Requirements Rule, each PM

2.5

attainment plan must contain an RFP analysis that includes, at a minimum, the following four components: (1) An implementation schedule for control measures; (2) RFP projected emissions for direct PM

2.5

and all PM

2.5

plan precursors for each applicable milestone year, based on the anticipated control measure implementation schedule; (3) a demonstration that the control strategy and implementation schedule will achieve reasonable progress toward attainment between the base year and the attainment year; and (4) a demonstration that by the end of the calendar year for each milestone date for the area, pollutant emissions will be at levels that reflect either generally linear progress or stepwise progress in reducing emissions on an annual basis between the base year and the

attainment year.

163

States should estimate the RFP projected emissions for each quantitative milestone year by sector on a pollutant-by-pollutant basis.

164

In an area that cannot practicably attain the PM

2.5

standard by the applicable Moderate area attainment date, full implementation of a control strategy that satisfies the Moderate area control requirements represents RFP towards attainment.

165

163

40 CFR 51.1012(a).

164

81 FR 58010, 58056.

165

Id. at 58056, 58057.

Section 189(c) requires that attainment plans include quantitative milestones that demonstrate RFP. The purpose of the quantitative milestones is to allow for periodic evaluation of the area's progress towards attainment of the NAAQS consistent with RFP requirements. Because RFP is an annual emission reduction requirement and the quantitative milestones are to be achieved every three years, when a state demonstrates compliance with the quantitative milestone requirement, it will demonstrate that RFP has been achieved during each of the relevant three years. Quantitative milestones should provide an objective means to evaluate progress toward attainment meaningfully,

e.g.,

through imposition of emission controls in the attainment plan and the requirement to quantify those required emission reductions. The CAA also requires states to submit milestone reports (due 90 days after each milestone), and these reports should include calculations and any assumptions made by the state concerning how RFP has been met,

e.g.,

through quantification of emission reductions to date.

166

The Act requires states to include RFP and quantitative milestones even for areas that cannot practicably attain.

166

General Preamble Addendum, 42016-42017.

The CAA does not specify the starting point for counting the three-year periods for quantitative milestones under CAA section 189(c). In the General Preamble and General Preamble Addendum, the EPA interpreted the CAA to require that the starting point for the first three-year period be the due date for the Moderate area plan submission.

167

Consistent with this longstanding interpretation of the Act, the PM

2.5

SIP Requirements Rule requires that each plan for a Moderate PM

2.5

nonattainment area contain quantitative milestones to be achieved no later than milestone dates 4.5 years and 7.5 years from the date of designation of the area.

168

Because the EPA designated the SJV nonattainment for the 2012 PM

2.5

NAAQS effective April 15, 2015,

169

the applicable quantitative milestone dates for purposes of this NAAQS in the SJV are October 15, 2019, and October 15, 2022. Following reclassification of the SJV as Serious for the 2012 PM

2.5

standard, later milestones would be addressed by the Serious area plan.

170

167

General Preamble, 13539 and General Preamble Addendum, 42016.

168

40 CFR 51.1013(a)(1).

169

80 FR 2206.

170

General Preamble Addendum, 42016.

2. Summary of State's Reasonable Further Progress Demonstrations and Quantitative Milestones

a. 2016 PM

2.5

Plan RFP and Quantitative Milestones

The RFP demonstration and quantitative milestones are discussed in section 3.5 of the 2016 PM

2.5

Plan. The plan estimates that emissions of direct PM

2.5

and NO

will generally decline from the 2013 base year and states that emissions of each of these pollutants will remain at or below the levels needed to show “generally linear progress” through 2022, the Moderate area post-attainment milestone year for the 2012 PM

2.5

NAAQS.

171

The Plan's emissions inventory shows that direct PM

2.5

and NO

are emitted by a large number and range of sources in the SJV and that the emission reductions needed for these pollutants are inventory-wide.

172

The Plan states that all RACM and RACT for stationary, area, and mobile sources have been identified and adopted, and identifies the District rules achieving emission reductions post-2013 in Table 3-2 and CARB regulations contributing to attainment in Table 3-3.

171

2016 PM

2.5

Plan, Table 3-6. We note that Appendix B (“Emissions Inventory”) of the plan indicates that emissions of ammonia, SO

, and VOC will also generally decline from the 2013 base year, but the RFP plan does not address these three precursor pollutants given the State's conclusion that they do not contribute significantly to PM

2.5

levels that exceed the 2012 PM

2.5

NAAQS in the SJV. 2016 PM

2.5

Plan, 3-10.

172

2016 PM

2.5

Plan, App. B.

Table 3-6 of the 2016 PM

2.5

Plan presents target RFP emission levels, based on linear emission reductions from 2013 through 2022, and the RFP projected emissions, based on the plan's baseline emissions inventory and control strategy (

i.e.,

RACM/RACT and additional reasonable measures) for each quantitative milestone year (2019 and 2022).

173

We reproduce Table 3-6, in part, along with the plan's 2013 base year inventory from Table 3-5, in Table 4. Based on these analyses, the District and CARB conclude that their adopted control strategy will achieve sufficient reductions in emissions of direct PM

2.5

and NO

to result in emission levels at or below the RFP and quantitative milestone target emission levels for 2019 and 2022.

174

173

Table 3-6 identifies only emission levels for milestone years that must be addressed by the Moderate area plan (

i.e.,

2019 and 2022).

174

2016 PM

2.5

Plan, 3-10, and CARB 2016 Staff Report, 13.

Table 4—2016 PM

2.5

Plan: Annual PM

2.5

Emissions Inventory for Base Year and Moderate Area Plan Milestone Years

[Annual average, tpd]

Pollutant

2013 baseline

2019 RFP target

emissions level

2019 projected

emissions level

2022 RFP target

emissions level

2022 projected

emissions level

Direct PM

2.5

63.4

60.8

60.2

59.5

318.1

229.5

219.4

185.2

Source:

2016 PM

2.5

Plan, tables 3-5 and 3-6. We corrected the 2019 RFP Target Emissions Level for NO

in Table 3-6 to reflect the value in Table 3-5 that was transcribed incorrectly as 229.1 tpd.

The 2016 PM

2.5

Plan documents the State's conclusion that all RACM/RACT and additional reasonable measures for these pollutants are being implemented as expeditiously as practicable and identifies projected levels of direct PM

2.5

and NO

emissions that reflect full implementation of the State, District, and SJV MPOs' RACM/RACT and additional reasonable measure control strategy for these pollutants.

175

The control strategy that provides the basis for these emission projections is described in attachments 1 and 2 of the 2016 PM

2.5

Plan.

175

2016 PM

2.5

Plan, 3-5 through 3-7; see also evaluation of RACM/RACT and additional reasonable control measures in section IV.D of this proposed rule.

For quantitative milestones, the 2016 PM

2.5

Plan identifies 2019 and 2022 as the applicable milestone years and includes milestones to track the State's and District's implementation of control measures and to document updated emissions data.

176

For 2019, the milestone includes a “list of measures in the SIP control strategy and key implementation requirements,” including compliance milestones in CARB's Truck and Bus Regulation and in the District's Rule 4901 on residential wood burning. For 2022, the milestone includes a “list of measures in the SIP control strategy and key implementation requirements,” including compliance milestones in CARB's Truck and Bus Regulation.

176

2016 PM

2.5

Plan, 3-13.

b. 2018 PM

2.5

Plan RFP and Quantitative Milestones

Appendix H of the 2018 PM

2.5

Plan provides the State's updated RFP demonstration and quantitative milestones, based on updated data (

e.g.,

updated emissions inventories, as discussed in section IV.A of this proposed rule) for the 2019 and 2022 milestone years. Following the identification of a transcription error in the RFP tables of Appendix H, the State submitted a revised version of Appendix H that corrects the transcription error and provides additional information on the RFP demonstration.

177

Given the State's conclusions that ammonia, SO

, and VOC emissions do not contribute significantly to PM

2.5

levels that exceed the 2012 PM

2.5

NAAQS in the SJV, as discussed in section IV.B of this proposed rule, the RFP demonstration provided by the State addresses emissions of direct PM

2.5

and NO

178

Similarly, the State developed quantitative milestones based upon the 2018 PM

2.5

Plan's strategy for reducing emissions of direct PM

2.5

and NO

179

177

Appendix H to 2018 PM

2.5

Plan, submitted February 11, 2020, via the EPA State Planning Electronic Collaboration System. This revised version of Appendix H replaces the version submitted with the 2018 PM

2.5

Plan on May 10, 2019. All references to Appendix H in this proposed rule are to the revised version of Appendix H submitted February 11, 2020.

178

2018 PM

2.5

Plan, App. H, H-1.

179

Id. at H-23 to H-24 (for State milestones) and H-20 to H-21 (for District milestones).

Like the 2016 PM

2.5

Plan, the 2018 PM

2.5

Plan estimates that emissions of direct PM

2.5

and NO

will generally decline from the 2013 base year to the 2022 RFP milestone year and beyond, and that direct PM

2.5

and NO

are emitted by a large number and range of sources in the SJV. The 2018 PM

2.5

Plan relies on the same set of identified control measures as the 2016 PM

2.5

Plan to demonstrate RFP through 2022,

i.e.,

the baseline measures reflected in each plan's emissions inventory.

180

2018 PM

2.5

Plan, App. H, H-4 to H-15.

In addition to these baseline measures, the 2018 PM

2.5

Plan's control strategy includes specific control measure commitments for purposes of attaining the 2012 PM

2.5

NAAQS by 2025, including commitments by the State and District to develop and propose to their respective boards specific regulatory and incentive-based measures identified in the plan by specific years leading up to 2025, including 2019 and 2022.

181

Although the attainment demonstration does not rely on these control measure commitments for emission reductions until 2024,

182

the RFP and quantitative milestone elements of the 2018 PM

2.5

Plan rely on these control measure commitments to demonstrate that the plan requires RFP toward attainment.

183

181

CARB Resolution 18-49 (October 25, 2018), 5; 2018 PM

2.5

Plan, Ch. 4, Table 4-8; email dated November 12, 2019, from Sylvia Vanderspek, CARB to Anita Lee, EPA Region IX, “RE: SJV PM

2.5

inform

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