Partial Approval and Partial Disapproval of Air Quality Implementation Plans and Determination of Attainment by the Attainment Date; California; San Joaquin Valley Serious Area and Section 189(d) Plan for Attainment of the 1997 24-Hour PM2.5 NAAQS

Federal RegisterSep 24, 2021

Ask Donna

What actually matters in this document.

Text

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R09-OAR-2021-0261; FRL-8969-01-R9]

Partial Approval and Partial Disapproval of Air Quality Implementation Plans and Determination of Attainment by the Attainment Date; California; San Joaquin Valley Serious Area and Section 189(d) Plan for Attainment of the 1997 24-Hour PM

2.5

NAAQS

AGENCY:

Environmental Protection Agency (EPA).

ACTION:

Proposed rule.

SUMMARY:

The Environmental Protection Agency (EPA) is proposing to approve in part and disapprove in part portions of a state implementation plan (SIP) revision submitted by the State of California to meet Clean Air Act (CAA or “Act”) requirements for the 1997 24-hour fine particulate matter (PM

2.5

) national ambient air quality standards (NAAQS) in the San Joaquin Valley nonattainment area. Specifically, the EPA is proposing to approve all but the contingency measure element of the submitted SIP revision as meeting all applicable Serious area and CAA section 189(d) requirements for the 1997 24-hour PM

2.5

NAAQS and is proposing disapproval of the contingency measure element. The EPA is also proposing to determine that the San Joaquin Valley air quality planning area has attained the 1997 24-hour PM

2.5

NAAQS. This determination is based on sufficient, quality-assured, and certified data for 2018-2020. Based on our proposed finding that the San Joaquin Valley nonattainment area has attained the 1997 24-hour PM

2.5

NAAQS, we are proposing to determine that the requirement for contingency measures will no longer apply to the San Joaquin Valley nonattainment area for these NAAQS. Thus, the EPA is proposing to issue a protective finding for transportation conformity determinations for this proposed disapproval.

DATES:

Any comments on this proposal must be received by October 25, 2021.

ADDRESSES:

Submit your comments, identified by Docket ID No. EPA-R09-OAR-2021-0261 at

https://www.regulations.gov.

For comments submitted at

Regulations.gov

, follow the online instructions for submitting comments. Once submitted, comments cannot be edited or removed from

Regulations.gov

. The EPA may publish any comment received to its public docket. Do not submit electronically any information you consider to be Confidential Business Information (CBI) or other information whose disclosure is restricted by statute. Multimedia submissions (

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:

Ashley Graham, Air Planning Office (ARD-2), EPA Region IX, 75 Hawthorne Street, San Francisco, CA 94105, (415) 972-3877, or by email at

graham.ashleyr@epa.gov.

SUPPLEMENTARY INFORMATION:

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

Table of Contents

I. Background for Proposed Action

A. PM

2.5

NAAQS

B. San Joaquin Valley PM

2.5

Designations, Classifications, and SIP Revisions

II. Summary and Completeness Review of the San Joaquin Valley PM

2.5

Plan

A. 2018 PM

2.5

Plan

B. Valley State SIP Strategy

III. Clean Air Act Requirements for PM

2.5

Serious Area Plans and for Serious PM

2.5

Areas That Fail To Attain

A. Requirements for PM

2.5

Serious Area Plans

B. Requirements for Serious PM

2.5

Areas That Fail To Attain

IV. Review of the San Joaquin Valley PM

2.5

Plan for the 1997 24-Hour PM

2.5

NAAQS

A. Emissions Inventories

B. PM

2.5

Precursors

C. Attainment Plan Control Strategy

D. Attainment Demonstration and Modeling

E. Reasonable Further Progress and Quantitative Milestones

F. Contingency Measures

G. Motor Vehicle Emission Budgets

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

V. Determination of Attainment by the Attainment Date

A. Requirements for Attainment Determinations

B. Monitoring Network Considerations

C. Data Considerations and Proposed Determination

VI. Summary of Proposed Action and Request for Public Comment

VII. Statutory and Executive Order Reviews

I. Background for Proposed Action

A. PM

2.5

NAAQS

Under section 109 of the CAA, the EPA has established NAAQS for certain pervasive air pollutants (referred to as “criteria pollutants”) and conducts periodic reviews of the NAAQS to determine whether they should be revised or whether new NAAQS should be established.

On July 18, 1997, the EPA revised the NAAQS for particulate matter by establishing new NAAQS for particles with an aerodynamic diameter less than or equal to a nominal 2.5 micrometers (PM

2.5

The EPA established primary and secondary annual and 24-hour standards for PM

2.5

The annual primary and secondary standards were set at 15.0 micrograms per cubic meter (μg/m

), based on a three-year average of annual mean PM

2.5

concentrations, and the 24-hour primary and secondary standards were set at 65 μg/m

, based on the three-year average of the 98th percentile of 24-hour PM

2.5

concentrations at each monitoring site within an area.

Collectively, we refer herein to the 1997 24-hour and annual PM

2.5

NAAQS as the “1997 PM

2.5

NAAQS” or “1997 PM

2.5

standards.”

62 FR 38652.

For a given air pollutant, “primary” NAAQS are those determined by the EPA as requisite to protect the public health, allowing an adequate margin of safety, and “secondary” standards are those determined by the EPA as requisite to protect the public welfare from any known or anticipated adverse effects associated with the presence of such air pollutant in the ambient air. See CAA section 109(b).

40 CFR 50.7.

On October 17, 2006, the EPA revised the level of the 24-hour PM

2.5

NAAQS to 35 μg/m

and on January 15, 2013, the EPA revised the level of the primary annual PM

2.5

NAAQS to 12.0 μg/m

Even though the EPA lowered the 24-hour and annual PM

2.5

NAAQS, the 1997 24-hour PM

2.5

NAAQS remain in effect and the 1997 primary annual PM

2.5

NAAQS remains in effect in areas designated nonattainment for that NAAQS.

71 FR 61144.

78 FR 3086.

40 CFR 50.13(d).

The EPA established the 1997 PM

2.5

NAAQS 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. 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 dates), changes in lung function and increased respiratory symptoms, and new evidence for more subtle indicators of cardiovascular health. Individuals particularly sensitive to PM

2.5

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

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

Sources can emit PM

2.5

directly into the atmosphere as a solid or liquid particle (primary PM

2.5

or direct PM

2.5

), or PM

2.5

can form in the atmosphere (secondary PM

2.5

) as a result of various chemical reactions from precursor emissions of nitrogen oxides (NO

), sulfur oxides (SO

), volatile organic compounds, and ammonia.

For example, see 72 FR 20586, 20589 (April 25, 2007).

B. San Joaquin Valley PM

2.5

Designations, Classifications, and SIP Revisions

Following promulgation of a new or revised NAAQS, the EPA is required under CAA section 107(d) to designate areas throughout the nation as attaining or not attaining the NAAQS. Effective April 5, 2005, the EPA established the initial air quality designations for the 1997 24-hour and annual PM

2.5

NAAQS, using air quality monitoring data for the three-year periods of 2001-2003 and 2002-2004.

The EPA designated the San Joaquin Valley as nonattainment for both the 1997 24-hour PM

2.5

NAAQS (65 μg/m

) and the 1997 annual PM

2.5

NAAQS (15.0 μg/m

70 FR 944 (January 5, 2005).

40 CFR 81.305.

The San Joaquin Valley PM

2.5

nonattainment area encompasses over 23,000 square miles and includes all or part of eight counties: San Joaquin, Stanislaus, Merced, Madera, Fresno, Tulare, Kings, and the valley portion of Kern.

The area is home to four million people and is one of the nation's leading agricultural regions. 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 attainment plans. Authority for regulating sources under state jurisdiction in the San Joaquin Valley is split under State law between the District, which generally has responsibility for regulating stationary and area sources, and CARB, which generally has responsibility for regulating mobile sources.

For a precise description of the geographic boundaries of the San Joaquin Valley nonattainment area, see 40 CFR 81.305.

At the time of the initial designations for the 1997 PM

2.5

NAAQS, the EPA interpreted the CAA to require implementation of the NAAQS under the general nonattainment plan requirements of subpart 1.

Under subpart 1, states were required to submit nonattainment plan SIP submissions within three years of the effective date of designations, that, among other things, provided for implementation of reasonably available control measures (RACM), reasonable further progress (RFP), contingency measures, and a modeled attainment demonstration showing attainment of the NAAQS as expeditiously as practicable but no later than five years from the designation (in this instance, no later than April 5, 2010) unless the state justified an attainment date extension of up to five years.

72 FR 20586.

CAA sections 172(a)(2), 172(c)(1), 172(c)(2), and 172(c)(9).

Between 2007 and 2011, California submitted six SIP revisions to address nonattainment area planning requirements for the 1997 24-hour and annual PM

2.5

NAAQS in the San Joaquin Valley,

which we refer to collectively as the “2008 PM

2.5

Plan.” On November 9, 2011, the EPA approved the portions of the 2008 PM

2.5

Plan, as revised in 2009 and 2011, that addressed attainment of the 1997 24-hour and annual PM

2.5

NAAQS in the San Joaquin Valley PM

2.5

nonattainment area, except for the attainment contingency measures, which we disapproved.

We also granted the State's request to extend the attainment deadline for the 1997 PM

2.5

NAAQS in the San Joaquin Valley to April 5, 2015.

76 FR 69896, n. 2 (November 9, 2011).

Id. at 69924.

Id.

Following a January 4, 2013 decision of the U.S. Court of Appeals for the D.C. Circuit (“D.C. Circuit”) remanding the EPA's 2007 implementation rule for the 1997 PM

2.5

NAAQS,

the EPA published a final rule on June 2, 2014, classifying the San Joaquin Valley as a Moderate nonattainment area for the 1997 24-hour and annual PM

2.5

NAAQS under subpart 4, part D of title I of the Act.

In this action, the EPA acknowledged that states must meet both subpart 1 and subpart 4 requirements in nonattainment plan SIP submissions for the 1997 24-hour and annual PM

2.5

NAAQS and provided states with additional time to supplement or withdraw and resubmit any pending nonattainment plan SIP submissions.

Natural Resources Defense Council

EPA,

706 F.3d. 428 (D.C. Cir. 2013) (“

NRDC”

). In

NRDC,

the court held that the EPA erred in implementing the 1997 PM

2.5

standards solely pursuant to the general implementation requirements of subpart 1, without also considering the requirements specific to nonattainment areas for particles less than or equal to 10 µm in diameter (PM

) in subpart 4, part D of title I of the CAA. The court reasoned that the plain meaning of the CAA requires implementation of the 1997 PM

2.5

standards under subpart 4 because PM

2.5

falls within the statutory definition of PM

and is thus subject to the same statutory requirements as PM

. The court remanded the rule, without vacatur, and instructed the EPA “to repromulgate these rules pursuant to Subpart 4 consistent with this opinion.”

79 FR 31566.

Effective May 7, 2015, the EPA reclassified the San Joaquin Valley as a Serious nonattainment area for the 1997 PM

2.5

NAAQS based on the determination that the State could not practicably attain these NAAQS in the San Joaquin Valley nonattainment area by the latest statutory Moderate area attainment date,

i.e.,

April 5, 2015.

Upon reclassification as a Serious area, the State became subject to the requirement of CAA section 188(c)(2) to attain the 1997 PM

2.5

NAAQS, as expeditiously as practicable but no later than ten years after designation,

i.e.,

by no later than December 31, 2015. California submitted its 1997 PM

2.5

Serious area plan for the San Joaquin Valley in two submissions dated June 25, 2015 and August 13, 2015, including a request under section 188(e) to extend the attainment date for the 1997 24-hour PM

2.5

NAAQS by three years (to December 31, 2018) and to extend the attainment date for the 1997 annual PM

2.5

NAAQS by five years (to December 31, 2020). On February 9, 2016, the EPA proposed to approve most of the Serious area plan and to

grant the State's request for extensions of the December 31, 2015 attainment date.

However, on October 6, 2016, after considering public comments, the EPA denied California's request for these extensions of the attainment dates.

Consequently, on November 23, 2016, the EPA determined that the San Joaquin Valley had failed to attain the 1997 24-hour and annual PM

2.5

NAAQS by the December 31, 2015 Serious area attainment date.

This determination triggered a requirement for California to submit a new SIP submission for the 1997 24-hour and annual PM

2.5

NAAQS for the San Joaquin Valley that satisfies the requirements of CAA section 189(d). The statutory deadline for this additional SIP submission was December 31, 2016. The EPA did not finalize the actions proposed on February 9, 2016, with respect to the submitted Serious area plan.

80 FR 18528 (April 7, 2015).

81 FR 6936. California's request for extension of the Serious Area attainment date for the San Joaquin Valley accompanied its Serious Area attainment plan for the 1997 PM

2.5

NAAQS and related motor vehicle emission budgets, submitted June 25, 2015 and August 13, 2015, respectively.

81 FR 69396.

81 FR 84481.

81 FR 69396, 69400.

On December 6, 2018, the EPA determined that California had failed to submit a complete section 189(d) attainment plan for the 1997 24-hour and annual PM

2.5

NAAQS, among other required SIP submissions for the San Joaquin Valley, by the statutory deadlines.

This finding, which became effective on January 7, 2019, triggered clocks under CAA section 179(a) for the application of emissions offset sanctions 18 months after the finding, and highway funding sanctions 6 months thereafter, unless the EPA affirmatively determined that the State has made a complete SIP submission addressing the identified failure to submit deficiencies.

The finding also triggered the obligation under CAA section 110(c) for the EPA to promulgate a federal implementation plan no later than two years after the finding, unless the State has submitted, and the EPA has approved, the required SIP submission.

83 FR 62720.

Id. at 62723.

Id.

On May 10, 2019, CARB made SIP submissions intended to address the Serious area nonattainment plan and CAA section 189(d) requirements for the 1997 24-hour and annual PM

2.5

NAAQS, among other requirements for the 2006 and 2012 PM

2.5

NAAQS.

CARB clarified in its May 10, 2019 letter that these new SIP submissions superseded past submissions to the EPA that the agency had not yet acted on for the 1997 PM

2.5

NAAQS, including the 2015 Serious area attainment plan submissions. On June 24, 2020, the EPA issued a letter finding these submissions complete and terminating the sanctions clocks under CAA section 179(a).

The portions of these SIP submissions that pertain to the 1997 24-hour PM

2.5

NAAQS are the subject of this proposal.

Letter dated May 9, 2019, from Richard Corey, Executive Officer, CARB, to Mike Stoker, Regional Administrator, EPA Region 9. The letter clarifies that the 2018 PM

2.5

Plan supersedes past submittals to the EPA that the agency has not yet acted on for the 1997 PM

2.5

standards, including the

2015 Plan for the 1997 Standard

(submitted by CARB on June 25, 2015) and motor vehicle emission budgets (submitted by CARB August 13, 2015).

Letter dated June 24, 2020, from Elizabeth J. Adams, Director, Air and Radiation Division, EPA Region IX, to Richard Corey, Executive Officer, CARB, Subject: “RE: Completeness Finding for State Implementation Plan (SIP) Submissions for San Joaquin Valley for the 1997, 2006, and 2012 Fine Particulate Matter (PM

2.5

) National Ambient Air Quality Standards (NAAQS) and Termination of Clean Air Act (CAA) Sanction Clocks.”

II. Summary and Completeness Review of the San Joaquin Valley PM2

5 Plan

The EPA is proposing action on portions of two SIP submissions made by CARB to address nonattainment plan requirements for the 1997 24-hour PM

2.5

NAAQS in the San Joaquin Valley. Specifically, the EPA is proposing to act on those portions of the following two SIP submissions that pertain to the 1997 24-hour PM

2.5

NAAQS: (i) The “2018 Plan for the 1997, 2006, and 2012 PM

2.5

Standards,” adopted by the SJVUAPCD on November 15, 2018, and by CARB on January 24, 2019 (“2018 PM

2.5

Plan”);

and (ii) the “San Joaquin Valley Supplement to the 2016 State Strategy for the State Implementation Plan,” adopted by CARB on October 25, 2018 (“Valley State SIP Strategy”). CARB submitted the 2018 PM

2.5

Plan and Valley State SIP Strategy to the EPA as a revision to the California SIP on May 10, 2019.

We refer to these two SIP submissions collectively as the “SJV PM

2.5

Plan” or “Plan.”

The 2018 PM

2.5

Plan was developed jointly by CARB and the District.

Letter dated May 9, 2019, from Richard Corey, Executive Officer, CARB, to Mike Stoker, Regional Administrator, EPA Region 9. The EPA previously acted on those portions of the “2018 Plan for the 1997, 2006, and 2012 PM

2.5

Standards” and the “San Joaquin Valley Supplement to the 2016 State Strategy for the State Implementation Plan” that pertain to the 2006 PM

2.5

NAAQS (85 FR 44192, July 22, 2020), and proposed action on those portions pertaining to the 1997 annual PM

2.5

NAAQS (86 FR 38652, July 22, 2021) and 2012 annual PM

2.5

NAAQS (86 FR 49100, September 1, 2021). The EPA is not, at this time, taking any action on those portions that pertain to the 1997 annual PM

2.5

NAAQS or the 2012 annual PM

2.5

NAAQS. We intend to act on these portions of the submitted SIP revisions in subsequent rulemakings.

The SJV PM

2.5

Plan addresses the Serious area nonattainment plan and CAA section 189(d) requirements for the 1997 24-hour and annual PM

2.5

NAAQS in the San Joaquin Valley, including the State's demonstration that the area would attain the 1997 24-hour PM

2.5

NAAQS by December 31, 2020. In this proposal, the EPA is proposing action only on those portions of the SJV PM

2.5

Plan that pertain to the 1997 24-hour PM

2.5

NAAQS. The EPA is acting on the portions of the SJV PM

2.5

Plan that pertain to the 1997 annual PM

2.5

NAAQS and subsequent PM

2.5

NAAQS in separate rulemakings.

CAA sections 110(a)(1) and (2) and 110(l) require each state to provide reasonable public notice and opportunity for public hearing prior to the adoption and submission of a SIP or SIP revision to the EPA. To meet this requirement, every SIP submission must include evidence that the state provided adequate public notice and an opportunity for a public hearing consistent with the EPA's implementing regulations in 40 CFR 51.102.

CAA section 110(k)(1)(B) requires the EPA to determine whether a SIP submission is complete within 60 days of receipt. This section also provides that any plan that the EPA has not affirmatively determined to be complete or incomplete will become complete by operation of law six months after the date of submission. The EPA's SIP completeness criteria are found in 40 CFR part 51, Appendix V.

A. 2018 PM

2.5

Plan

The following portions of the 2018 PM

2.5

Plan and related support documents address both the Serious area nonattainment plan requirements in CAA section 189(b) and the CAA section 189(d) requirements for the 1997 24-hour PM

2.5

NAAQS in the San Joaquin Valley: (i) Chapter 4 (“Attainment Strategy for PM

2.5

”); (ii) Chapter 5 (“Demonstration of Federal Requirements for 1997 PM

2.5

Standards”);

(iii) numerous appendices to the 2018 PM

2.5

Plan; (iv)

CARB's “Staff Report, Review of the San Joaquin Valley 2018 Plan for the 1997, 2006, and 2012 PM

2.5

Standards,” release date December 21, 2018 (“CARB Staff Report”);

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

2.5

Plan (CARB Resolution 19-1 and SJVUAPCD Governing Board Resolution 18-11-16).

Chapter 6 (“Demonstration of Federal Requirements for the 2006 PM

2.5

Standard: Serious Plan and Extension Request”) and Chapter 7 (“Demonstration of Federal Requirements for the 2012 PM

2.5

Standard”) of the 2018 PM

2.5

Plan pertain to the 2006 PM

2.5

NAAQS and the 2012 PM

2.5

NAAQS, respectively. The EPA previously acted on those portions of the Plan that pertain to the 2006 PM

2.5

NAAQS (85 FR 44192), and proposed action on those portions pertaining to the 2012 annual PM

2.5

NAAQS (86 FR 49100). The EPA intends to take further action on those portions that pertain to the 2012 annual PM

2.5

NAAQS in separate rulemakings.

Letter dated December 11, 2019, from Richard Corey, Executive Officer, CARB, to Mike Stoker, Regional Administrator, EPA Region 9, transmitting the CARB Staff Report [on the 2018 PM

2.5

Plan]. The CARB Staff Report includes CARB's review of, among other things, the 2018 PM

2.5

Plan's control strategy and attainment demonstration.

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 that address the requirements for the 1997 24-hour PM

2.5

NAAQS include: (i) Appendix A (“Ambient PM

2.5

Data Analysis”); (ii) Appendix B (“Emissions Inventory”); (iii) Appendix C (“Stationary Source Control Measure Analyses”); (iv) Appendix D (“Mobile Source Control Measure Analyses”); (v) Appendix G (“Precursor Demonstration”); (vi) Appendix H (“RFP, Quantitative Milestones, and Contingency”);

(vii) Appendix I (“New Source Review and Emission Reduction Credits”); (viii) Appendix J (“Modeling Emission Inventory”); (ix) Appendix K (“Modeling Attainment Demonstration”); and (x) Appendix L (“Modeling Protocol”).

Appendix H to 2018 PM

2.5

Plan, submitted February 11, 2020 via the EPA State Planning Electronic Collaboration System. Following the identification of a transcription error in the RFP tables of Appendix H, on February 11, 2020, the State submitted a revised version of Appendix H that corrects the transcription error and provides additional information on the RFP demonstration. All references to Appendix H in this proposed rule are to the revised version submitted on February 11, 2020, which replaces the version submitted with the 2018 PM

2.5

Plan on May 10, 2019.

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 on and adoption of 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.

Therefore, we find that the 2018 PM

2.5

Plan meets the procedural requirements for public notice and hearing in CAA sections 110(a) and 110(l) and 40 CFR 51.102. The 2018 PM

2.5

Plan became complete by operation of law on November 10, 2019.

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, and CARB Resolution 19-1.

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, Appendix M (“Summary of Significant Comments and Responses”).

B. Valley State SIP Strategy

CARB developed the “Revised Proposed 2016 State Strategy for the State Implementation Plan” (“2016 State Strategy”) to support attainment planning in the San Joaquin Valley and Los Angeles-South Coast Air Basin (“South Coast”) ozone nonattainment areas.

In its resolution adopting the 2016 State Strategy (CARB Resolution 17-7), the Board found that the 2016 State Strategy would achieve 6 tons per day (tpd) of NO

emissions reductions and 0.1 tpd of direct PM

2.5

emissions reductions in the San Joaquin Valley by 2025 and directed CARB staff to work with the SJVUAPCD to identify additional reductions from sources under District regulatory authority as part of a comprehensive plan to attain all of the PM

2.5

NAAQS in the San Joaquin Valley and to return to the Board with a commitment to achieve additional emissions reductions from mobile sources.

The EPA has approved certain commitments made by CARB in the 2016 State Strategy for purposes of attaining the ozone NAAQS in the San Joaquin Valley and South Coast ozone nonattainment areas (see,

e.g.,

84 FR 3302 (February 12, 2019) and 84 FR 52005 (October 1, 2019)) and for attaining the 2006 PM

2.5

NAAQS in the San Joaquin Valley (85 FR 44192).

CARB Resolution 17-7, “2016 State Strategy for the State Implementation Plan,” March 23, 2017, 6-7.

CARB responded to this resolution by developing and adopting the “San Joaquin Valley Supplement to the 2016 State Strategy for the State Implementation Plan” (“Valley State SIP Strategy”) to support the 2018 PM

2.5

Plan. The State's May 10, 2019 SIP submission incorporates by reference the Valley State SIP Strategy as adopted by CARB on October 25, 2018 and submitted to the EPA on November 16, 2018.

Letter dated May 9, 2019, from Richard Corey, Executive Officer, CARB, to Mike Stoker, Regional Administrator, EPA Region 9.

The Valley State SIP Strategy includes an “Introduction” (Chapter 1), a chapter on “Measures” (Chapter 2), and a “Supplemental State Commitment from the Proposed State Measures for the Valley” (Chapter 3). Much of the content of the Valley State SIP Strategy is reproduced in Chapter 4 (“Attainment Strategy for PM

2.5

”) of the 2018 PM

2.5

Plan.

The Valley State SIP Strategy also includes CARB Resolution 18-49, which, among other things, commits CARB to achieve specific amounts of NO

and PM

2.5

emissions reductions by specific years, for purposes of attaining the PM

2.5

NAAQS in the San Joaquin Valley.

For example, Table 2 (proposed mobile source measures and schedule), Table 3 (emissions reductions from proposed mobile source measures), and Table 4 (summary of emission reduction measures) of the Valley State SIP Strategy correspond to tables 4-8, 4-9, and 4-7, respectively, of the 2018 PM

2.5

Plan, Chapter 4.

CARB Resolution 18-49, “San Joaquin Valley Supplement to the 2016 State Strategy for the State Implementation Plan,” October 25, 2018, 5.

CARB provided the required public notice and opportunity for public comment prior to its October 25, 2018 public hearing on and adoption of the Valley State SIP Strategy.

The SIP submission includes proof of publication of the public notice for this public hearing. It also includes copies of the written and oral comments received during the State's public review process and CARB's responses thereto.

Therefore, we find that the Valley State SIP Strategy meets the procedural requirements for public notice and hearing in CAA sections 110(a) and 110(l) and 40 CFR 51.102. The Valley State SIP Strategy became complete by operation of law on November 10, 2019.

CARB, “Notice of Public Meeting to Consider the San Joaquin Valley Supplement to the 2016 State Strategy for the State Implementation Plan,” September 21, 2018, and CARB Resolution 18-49.

CARB, “Board Meeting Comments Log,” November 2, 2018 and compilation of written comments; and J&K Court Reporting, LLC, “Meeting, State of California Air Resources Board,” October 25, 2018 (transcript of CARB's public hearing).

III. Clean Air Act Requirements for PM2

5 Serious Area Plans and for Serious PM2

5 Areas That Fail To Attain

A. Requirements for PM

2.5

Serious Area Plans

Upon reclassification of a Moderate nonattainment area as a Serious nonattainment area under subpart 4 of part D, title I of the CAA, the Act requires the state to make a SIP submission that addresses the following Serious nonattainment area requirements:

40 CFR 51.1003(b)(1); 81 FR 58010, 58074-58075 (August 24, 2016).

1. A comprehensive, accurate, current inventory of actual emissions from all sources of PM

2.5

and PM

2.5

precursors in the area (CAA section 172(c)(3));

2. Provisions to assure that the best available control measures (BACM), including best available control technology (BACT), for the control of direct PM

2.5

and PM

2.5

precursors shall be implemented no later than four years after the area is reclassified (CAA section 189(b)(1)(B));

3. A demonstration (including air quality modeling) that the plan provides for attainment as expeditiously as practicable but no later than the end of the tenth calendar year after designation as a nonattainment area (

i.e.,

December 31, 2015, for the San Joaquin Valley for the 1997 PM

2.5

NAAQS);

4. Plan provisions that require RFP (CAA section 172(c)(2));

5. Quantitative milestones that are to be achieved every three years until the area is redesignated attainment and that demonstrate RFP toward attainment by the applicable date (CAA section 189(c));

6. Provisions to assure that control requirements applicable to major stationary sources of PM

2.5

also apply to major stationary sources of PM

2.5

precursors, except where the state demonstrates to the EPA's satisfaction that such sources do not contribute significantly to PM

2.5

levels that exceed the standard in the area (CAA section 189(e));

As discussed in section IV.H, California submitted nonattainment NSR SIP revisions to address the subpart 4 requirements for the San Joaquin Valley Serious PM

2.5

nonattainment area on November 20, 2019. We are not proposing any action on this submission at this time. We will act on this submission through a separate rulemaking, as appropriate.

7. Contingency measures to be implemented if the area fails to meet RFP or to attain by the applicable attainment date (CAA section 172(c)(9)); and

8. A revision to the nonattainment new source review (NSR) program to lower the applicable “major stationary source”

thresholds from 100 tons per year (tpy) to 70 tpy (CAA section 189(b)(3)).

For any Serious area, the terms “major source” and “major stationary source” include any stationary source that emits or has the potential to emit at least 70 tons per year of PM

2.5

. CAA section 189(b)(3) and 40 CFR 51.165(a)(1)(iv)(A)(

)(

vii

) and (

viii

) (defining “major stationary source” in serious PM

2.5

nonattainment areas).

Serious area plans must also satisfy the requirements for Moderate area plans in CAA section 189(a), to the extent the state has not already met those requirements in the Moderate area plan submitted for the area.

In addition, the Serious area plan must meet the general requirements applicable to all SIP submissions under section 110 of the CAA, including the requirement to provide necessary assurances that the implementing agencies have adequate personnel, funding, and authority under section 110(a)(2)(E); and the requirements concerning enforcement provisions in section 110(a)(2)(C).

Because the EPA has not previously approved a SIP submission for the San Joaquin Valley as meeting the subpart 4 RACM Moderate area planning requirement under CAA section 189 for the 1997 24-hour PM

2.5

NAAQS, the EPA is evaluating relevant portions of the SJV PM

2.5

Plan for compliance with these requirements, in addition to the requirements of CAA sections 189(b) and 189(d).

B. Requirements for Serious PM

2.5

Areas That Fail To Attain

In the event that a Serious area fails to attain the PM

2.5

NAAQS by the applicable attainment date, CAA section 189(d) requires that “the State in which such area is located shall, after notice and opportunity for public comment, submit within 12 months after the applicable attainment date, plan revisions which provide for attainment of the . . . standard . . .” An attainment plan under section 189(d) must, among other things, demonstrate expeditious attainment of the NAAQS within the time period provided under CAA section 179(d)(3) and provide for annual reductions in emissions of direct PM

2.5

or a PM

2.5

plan precursor pollutant within the area of not less than five percent per year from the most recent emissions inventory for the area until attainment.

In addition to the requirement to submit control measures providing for a five percent reduction in emissions of certain pollutants on an annual basis, the EPA interprets CAA section 189(d) as requiring a state to submit an attainment plan that includes the same basic statutory plan elements that are required for other attainment plans.

CAA section 189(d), 40 CFR 51.1004(a)(3), 40 CFR 51.1010(c).

81 FR 58010, 58098.

Specifically, a state must submit to the EPA its plan to meet the requirements of CAA section 189(d) in the form of a complete attainment plan submission that includes the following elements:

40 CFR 51.1003(c)(1).

1. A comprehensive, accurate, current inventory of actual emissions from all sources of PM

2.5

and PM

2.5

precursors in the area;

2. A Serious area plan control strategy that ensures that BACM, including BACT, for the control of direct PM

2.5

and PM

2.5

precursors are implemented in the area;

3. Additional measures (beyond those already adopted in previous nonattainment plan SIP submissions for the area as RACM/RACT, BACM/BACT, and most stringent measures (MSM) (if applicable))

that provide for attainment of the NAAQS as expeditiously as practicable and, from the date of such submission until attainment, demonstrate that the plan will at a minimum achieve an annual five percent reduction in emissions of direct PM

2.5

or any PM

2.5

plan precursor;

MSM is applicable if the EPA has previously granted an extension of the attainment date under CAA section 188(e) for the nonattainment area and NAAQS at issue.

4. A demonstration (including air quality modeling) that the plan provides for attainment of the NAAQS at issue as expeditiously as practicable;

5. Plan provisions that require RFP;

6. Quantitative milestones that the state is to meet every three years until the area is redesignated attainment and that demonstrate RFP toward attainment by the applicable date;

7. Contingency measures to be implemented if the state fails to meet any requirement concerning RFP or quantitative milestones or to attain the NAAQS at issue by the applicable attainment date; and

8. Provisions to assure that control requirements applicable to major stationary sources of PM

2.5

, also apply to major stationary sources of PM

2.5

precursors, except where the state demonstrates to the EPA's satisfaction that such sources do not contribute significantly to PM

2.5

levels that exceed the NAAQS at issue in the area.

As discussed in section IV.H, California submitted nonattainment NSR SIP revisions to address the subpart 4 requirements for the San Joaquin Valley Serious PM

2.5

nonattainment area on November 20, 2019. We are not proposing any action on this submission at this time. We will act on this submission through a separate rulemaking, as appropriate.

A state's section 189(d) plan submission must demonstrate attainment as expeditiously as practicable, and no later than five years from the date of the EPA's determination that the area failed to attain, consistent with sections 179(d)(3) and 172(a)(2) of the CAA.

81 FR 84481, 84482.

A state with a Serious PM

2.5

nonattainment area that fails to attain the NAAQS by the applicable Serious area attainment date must also address any statutory requirements applicable to Moderate and Serious nonattainment area plans under CAA sections 172 and 189 of the CAA to the extent that those requirements have not already been met.

Because the EPA has not previously approved a SIP submission

for the San Joaquin Valley as meeting the subpart 4 RACM Moderate area planning requirements under CAA section 189 for the 1997 24-hour PM

2.5

NAAQS, the EPA is evaluating relevant portions of the SJV PM

2.5

Plan for compliance with this requirement. In addition, as discussed above, the EPA has not previously approved a SIP submission for the San Joaquin Valley as meeting the Serious area planning requirements under CAA section 189(b)(1) for the 1997 24-hour PM

2.5

NAAQS. Some Serious area planning requirements operate on a timeline that is based on the outermost statutory Serious area attainment date of the end of the tenth calendar year following the area's designation to nonattainment. Because section 189(d) requires a state to address any applicable Serious area requirements that the state has not already met in the area, and the section 189(d) obligations do not come into effect until an area has failed to attain the NAAQS by the Serious area attainment date, the EPA proposes that it should evaluate any previously unmet Serious area planning obligations based on the current, applicable attainment date appropriate under section 189(d), and not the original Serious area attainment date.

81 FR 58010, 58098.

The EPA provided its preliminary views on the CAA's requirements for particulate matter plans under part D, title I of the Act in the following guidance documents: (1) “State Implementation Plans; General Preamble for the Implementation of Title I of the Clean Air Act Amendments of 1990” (“General Preamble”);

(2) “State Implementation Plans; General Preamble for the Implementation of Title I of the Clean Air Act Amendments of 1990; Supplemental” (“General Preamble Supplement”);

and (3) “State Implementation Plans for Serious PM-10 Nonattainment Areas, and Attainment Date Waivers for PM-10 Nonattainment Areas Generally; Addendum to the General Preamble for the Implementation of Title I of the Clean Air Act Amendments of 1990” (“General Preamble Addendum”).

More recently, in an August 24, 2016 final rule entitled, “Fine Particulate Matter National Ambient Air Quality Standards: State Implementation Plan Requirements” (“PM

2.5

SIP Requirements Rule”), the EPA established regulatory requirements and provided further interpretive guidance on the statutory SIP requirements that apply to areas designated nonattainment for the PM

2.5

NAAQS.

We discuss these regulatory requirements and interpretations of the Act as appropriate in our evaluation of the SJV PM

2.5

Plan that follows.

57 FR 13498 (April 16, 1992).

57 FR 18070 (April 28, 1992).

59 FR 41998 (August 16, 1994).

81 FR 58010.

IV. Review of the San Joaquin Valley PM2

5 Plan for the 1997 24-Hour PM2

5 NAAQS

The EPA is evaluating the SJV PM

2.5

Plan against the Serious area requirements for the 1997 24-hour PM

2.5

NAAQS and the section 189(d) requirements for the 1997 24-hour PM

2.5

NAAQS, as laid out in section III of this proposal. Many requirements for both a Serious area plan and a section 189(d) plan are structured around the relevant statutory attainment date. The latest statutory Serious area attainment date for the San Joaquin Valley area was December 31, 2015.

On November 23, 2016, the EPA determined that the area failed to attain by the Serious area attainment date.

As discussed in section I.B, California submitted its Serious area plan for the 1997 24-hour PM

2.5

NAAQS in two submissions dated June 25, 2015 and August 13, 2015, including a request under section 188(e) to extend the attainment date for the 1997 24-hour PM

2.5

NAAQS by three years (to December 31, 2018). On October 6, 2016, the EPA denied the request for an extension, but did not finalize action on the Serious area plan submissions. Accordingly, the Serious area attainment date remained unchanged: As expeditiously as practicable but no later than December 31, 2015.

For the purposes of the section 189(d) requirements, the attainment date is the date by which a state can attain the NAAQS as expeditiously as practicable, but no later than five years from the publication date of the final determination of failure to attain.

As discussed in section IV.D, the SJV PM

2.5

Plan projected that attainment could be achieved in fewer than five years,

i.e.,

by December 31, 2020.

CAA section 179(d)(3); 81 FR 84481, 84482. The determination of failure to attain published on November 23, 2016.

When the State submitted the SJV PM

2.5

Plan in 2019, the State withdrew its previous Serious area plan that it had developed to meet the December 31, 2015 Serious area attainment date. Because the State submitted the SJV PM

2.5

Plan after the EPA's finding that the area had failed to attain by the applicable Serious area attainment date, the State could not demonstrate in the SJV PM

2.5

Plan that the area would attain by the Serious area attainment date, nor could it address other requirements based on this attainment date, such as RFP and quantitative milestones, because many of the relevant dates had already passed. As described in section III of this document, in a section 189(d) plan, a state must address any statutory requirements applicable to Moderate and Serious nonattainment area plans to the extent that it has not already met those requirements, but the EPA believes that it should base this evaluation on the current applicable attainment date under section 189(d). For example, it would be illogical to require a state to submit a Serious area modeled attainment demonstration that provided for attainment by December 31, 2015, after the EPA has already determined based on monitoring data that the state failed to attain by such date.

For the purposes of our evaluation of the Serious area plan requirements, although the State is required to submit a Serious area plan, and it must structure such a plan based on the Serious area attainment date, it would serve no purpose to evaluate the SJV PM

2.5

Plan against the now-passed Serious area attainment date by which the area has already failed to attain. For example, RFP and quantitative milestones normally are dependent upon the attainment date. Accordingly, because the State must still meet all Serious area plan requirements, even if doing so later in conjunction with the section 189(d) plan and its later attainment date, we will evaluate the State's compliance with the Serious area plan requirements in light of the later section 189(d) attainment date, as appropriate. Where the State in the SJV PM

2.5

Plan applies the section 189(d) attainment date to a Serious area requirement, we will note the statutory Serious area timeline and accept the submission in fulfillment of the State's Serious area plan obligation, but evaluate the submission in light of the section 189(d) attainment date.

A. Emissions Inventories

1. Statutory and Regulatory Requirements

CAA section 172(c)(3) requires that each SIP include a comprehensive, accurate, current inventory of actual emissions from all sources of the relevant pollutant or pollutants in the nonattainment area. The EPA discussed the emissions inventory requirements that apply to PM

2.5

nonattainment areas in the PM

2.5

SIP Requirements Rule and codified these requirements in 40 CFR 51.1008.

The EPA has also issued guidance concerning emissions

inventories for PM

2.5

nonattainment areas.

Id. at 58098-58099.

“Emissions Inventory Guidance for Implementation of Ozone and Particulate Matter National Ambient Air Quality Standards (NAAQS) and Regional Haze Regulations,” U.S. EPA, May 2017 (“Emissions Inventory Guidance”), available at

https://www.epa.gov/air-emissions-inventories/air-emissions-inventory-guidance-implementation-ozone-and-particulate.

The base year emissions inventory for a Serious area attainment plan or a CAA section 189(d) plan must provide a state's best estimate of actual emissions from all sources of the relevant pollutants in the area,

i.e.,

all emissions that contribute to the formation of a particular NAAQS pollutant. For the PM

2.5

NAAQS, the base year inventory must include direct PM

2.5

emissions, separately reported filterable and condensable PM

2.5

emissions,

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

2.5

i.e.,

nitrogen oxides (NO

), sulfur dioxide (SO

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

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(b)(1) and (c)(1).

The emissions inventory base year for a Serious area attainment plan must be one of the three years for which monitoring data were used to reclassify the area to Serious, or another technically appropriate year justified by the state in its Serious area SIP submission.

The emissions inventory base year for a Serious PM

2.5

nonattainment area subject to CAA section 189(d) must be one of the three years for which the EPA used monitored data to determine that the area failed to attain the PM

2.5

NAAQS by the applicable Serious area attainment date, or another technically appropriate year justified by the state in its Serious area SIP submission.

40 CFR 51.1008(b)(1).

40 CFR 51.1008(c)(1).

A state's SIP submission must include documentation explaining how it calculated emissions data for the inventory. In estimating mobile source emissions, a state should use the latest emissions models and planning assumptions available at the time the SIP is developed. The latest EPA-approved version of California's mobile source emission factor model for estimating tailpipe, brake, and tire wear emissions from on-road mobile sources that was available during the State's and District's development of the SJV PM

2.5

Plan was EMFAC2014.

Following CARB's submission of the Plan, the EPA approved EMFAC2017, the latest revision to this mobile source emissions model. 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.

80 FR 77337 (December 14, 2015). EMFAC is short for

ission

FAC

tor. The EPA announced the availability of the EMFAC2014 model, effective on the date of publication in the

Federal Register

for use in state implementation plan development and transportation conformity in California. Upon that action, EMFAC2014 was required to be used for all new regional emissions analyses and CO, PM

, and PM

2.5

hot-spot analyses that were started on or after December 14, 2017, which was the end of the grace period for using the prior mobile source emissions model, EMFAC2011.

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; see

https://www.arb.ca.gov/ei/areasrc/fullpdf/full7-9_2016.pdf.

AP-42 has been published since 1972 as the primary source of the EPA's emission factor information and is available at

https://www.epa.gov/air-emissions-factors-and-quantification/ap-42-compilation-air-emissions-factors.

It contains emission factors and process information for more than 200 air pollution source categories. A source category is a specific industry sector or group of similar emitting sources. The emission factors have been developed and compiled from source test data, material balance studies, and engineering estimates.

In addition to the base year inventory submitted to meet the requirements of CAA section 172(c)(3), the state must also submit a projected attainment year inventory and emissions projections for each RFP milestone year.

These future emissions projections are necessary components of the attainment demonstrations required under CAA sections 189(b)(1) and 189(d) and the demonstration of RFP required under section 172(c)(2).

Emissions projections for future years (referred to in the Plan as “forecasted inventories”) should account for, among other things, the ongoing effects of economic growth and adopted emissions control requirements. The state's SIP submission should include documentation to explain how the state calculated the emissions projections. Where a state chooses to allow new major stationary sources or major modifications to use emissions reduction credits (ERCs) that were generated through shutdown or curtailed emissions units occuring before the base year of an attainment plan, the projected emissions inventory used to develop the attainment demonstration must explicitly include the emissions from such previously shutdown or curtailed emissions units.

40 CFR 51.1008 and 51.1012. See also Emissions Inventory Guidance, section 3 (“SIP Inventory Requirements and Recommendations”).

40 CFR 51.1004, 51.1008, 51.1011, and 51.1012.

40 CFR 51.165(a)(3)(ii)(C)(1).

2. Summary of the State's Submission

The State included summaries of the planning emissions inventories for direct PM

2.5

and PM

2.5

precursors (NO

, SO

VOC,

and ammonia) and the documentation for the inventories for the San Joaquin Valley PM

2.5

nonattainment area in Appendix B (“Emissions Inventory”) and Appendix I (“New Source Review and Emission Reduction Credits”) of the 2018 PM

2.5

Plan.

The SJV 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 document.

The SJV PM

2.5

Plan generally uses “reactive organic gasses” or “ROG” in reference to VOC as a precursor to the formation of PM

2.5

. We use ROG and VOC interchangeably throughout this document.

CARB and District staff worked together to develop the emissions inventories for the San Joaquin Valley PM

2.5

nonattainment area. The District worked with operators of the stationary facilities in the nonattainment area to develop the stationary source emissions estimates. The responsibility for developing emissions estimates for area sources such as agricultural burning and paved road dust was shared by the District and CARB. CARB staff developed the emissions inventories for both on-road and non-road mobile sources.

The EPA regulations refer to “non-road” vehicles and engines whereas CARB regulations refer to “Other Mobile Sources” or “off-road” vehicles and engines. These terms refer to the same types of vehicles and engines. We refer herein to such vehicles and engines as “non-road” sources.

The Plan includes winter (24-hour) average and annual average daily emissions inventories for the 2013 base year, which CARB derived from the 2012 emissions inventory, and estimated emissions for forecasted years from 2017 through 2028 for the attainment and RFP demonstrations for the 1997, 2006, and 2012 PM

2.5

NAAQS.

In this proposal, we are proposing action on those winter average and annual average emissions inventories necessary to support the Serious area and CAA section 189(d) nonattainment plans for the 1997 24-

hour PM

2.5

NAAQS,

i.e.,

the 2013 base year inventory, forecasted inventories for the RFP milestone years of 2017, 2020 (attainment year), and 2023 (post-attainment milestone year), and additional forecasted emissions inventories for 2018 and 2019 to support the five percent annual emissions reduction demonstration as required by CAA section 189(d). Each inventory includes emissions from stationary, area, on-road, and non-road sources.

2018 PM

2.5

Plan, Appendix B, B-18 to B-19. The winter average daily planning inventory corresponds to the months of November through April, when daily, ambient PM

2.5

concentrations are typically highest. The base year inventory is from the California Emissions Inventory Development and Reporting System and future year inventories were estimated using the California Emission Projection Analysis Model (CEPAM), 2016 SIP Baseline Emission Projections, version 1.05.

CARB developed the base year inventories for stationary sources using actual emissions reports from facility operators. The State developed the base year emissions inventory for area sources using the most recent models and methodologies available at the time the State was developing the Plan.

The Plan also includes background, methodology, and inventories of condensable and filterable PM

2.5

emissions from stationary point and non-point combustion sources that are expected to generate condensable PM

2.5

CARB used EMFAC2014 to estimate on-road motor vehicle emissions based on transportation activity data from the 2014 Regional Transportation Plan (2014 RTP) adopted by the transportation planning agencies in the San Joaquin Valley.

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

2018 PM

2.5

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

Id. at B-42 to B-44.

Id. at B-37.

Id. at B-28.

CARB developed the emissions forecasts by applying growth and control profiles to the base year inventory. CARB's mobile source emissions projections take into account predicted activity rates and vehicle fleet turnover by vehicle model year and adopted controls.

In addition, the Plan states that the District is providing for use of pre-base year ERCs as offsets by accounting for such ERCs in the projected 2025 emissions inventory.

The 2018 PM

2.5

Plan identifies growth factors, control factors, and estimated offset use between 2013 and 2025 for direct PM

2.5

, NO

, SO

, and VOC emissions by source category and lists all pre-base year ERCs issued by the District for PM

, NO

, SO

, and VOC emissions, by facility.

Id. at B-18 and B-19.

2018 PM

2.5

Plan, Appendix I, I-1 to I-5.

Id. at tables I-1 to I-5.

Table 1 provides a summary of the winter (24-hour) average inventories in tons per day (tpd) of direct PM

2.5

and PM

2.5

precursors for the 2013 base year. Table 2 provides a summary of annual average inventories of direct PM

2.5

and PM

2.5

precursors for the 2013 base year. These annual average inventories provide the basis for the control measure analysis and the RFP and attainment demonstrations in the SJV PM

2.5

Plan.

Table 1—San Joaquin Valley Winter Average Emissions Inventory for Direct PM

2.5

and PM

2.5

Precursors for the 2013 Base Year (

tpd

)

Category

Direct PM

2.5

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 to B-5.

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

3. The EPA's Review of the State's Submission

We have reviewed the emissions inventories in the SJV PM

2.5

Plan that pertain to the 1997 24-hour PM

2.5

NAAQS and the emissions inventory estimation methodologies used by California for consistency with CAA requirements and the EPA's guidance. We find that the inventories are based on the most current and accurate information available to the State and District at the time they were developing the Plan and inventories, including the latest version of California's mobile source emissions model that had been approved by the EPA at the time, EMFAC2014. The inventories comprehensively address all source categories in the San Joaquin Valley PM

2.5

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

In accordance with 40 CFR 51.1008(b)(1), the 2013 base year is one of the three years of monitored data with which the EPA reclassified the San Joaquin Valley area to Serious. Furthermore, in accordance with 40 CFR 51.1008(c)(1), the 2013 base year is one of the three years of monitored data with which the EPA determined that the San Joaquin Valley area failed to attain the PM

2.5

NAAQS by the applicable Serious area attainment date for the

1997 24-hour PM

2.5

NAAQS.

The 2013 base year emissions inventories represent actual annual average emissions of all sources within the nonattainment area, direct PM

2.5

and PM

2.5

precursors are included in the inventories, and filterable and condensable direct PM

2.5

emissions are identified separately.

81 FR 84481, 84482.

With respect to future year emissions projections, we have reviewed the growth and control factors and find them acceptable and thus conclude that the future baseline emissions projections, which reflect ongoing emissions reductions from existing (

i.e.,

“baseline”) control measures as discussed in section IV.C.2.a, in the SJV PM

2.5

Plan reflect appropriate calculation methods and the latest planning assumptions. Also, as a general matter, the EPA will approve a SIP submission that takes emissions reduction credit for a control measure only where the EPA has approved the measure as part of the SIP. Thus, for example, to take credit for the emissions reductions from newly adopted or amended District rules for stationary sources, the related rules must be approved by the EPA into the SIP. Table 1 of the EPA's “Technical Support Document, San Joaquin Valley PM

2.5

Plan for the 1997 24-hour PM

2.5

NAAQS,” August 2021 (“EPA's 1997 24-hour PM

2.5

TSD”) shows District rules with post-2013 compliance dates that are reflected in the future year baseline inventories, along with information on the EPA's approval of these rules, and shows that stationary source emissions reductions assumed by the SJV PM

2.5

Plan for future years are supported by rules approved as part of the California SIP for the San Joaquin Valley. With respect to mobile sources, the EPA has taken action in recent years to approve CARB mobile source regulations into the state-wide portion of the California SIP. We therefore find that the future year baseline projections in the SJV PM

2.5

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

The baseline emissions projections in the 2018 PM

2.5

Plan assume implementation of CARB's Zero Emissions Vehicle (ZEV) sales mandate and greenhouse gas (GHG) standards. On September 27, 2019, the U.S. Department of Transportation and the EPA (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 for the ZEV sales mandate and vehicle GHG standards. 84 FR 51310. 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 titled:

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 San Joaquin Valley 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 attainment, RFP, or five percent reductions demonstrations for the 1997 24-hour PM

2.5

NAAQS in the SJV PM

2.5

Plan.

For these reasons, we are proposing to approve the 2013 base year emissions inventories in the SJV PM

2.5

Plan for the 1997 24-hour PM

2.5

NAAQS as meeting the requirements of CAA section 172(c)(3) and 40 CFR 51.1008 for purposes of both the Serious area and the CAA section 189(d) attainment plans. We are also proposing to find that the forecasted inventories in the Plan for the years 2017, 2018, 2019, 2020, and 2023 provide an adequate basis for the BACM, RFP, and the modeled attainment demonstration analyses in the SJV PM

2.5

Plan.

B. PM

2.5

Precursors

1. Statutory and Regulatory Requirements

The composition of PM

2.5

is complex and highly variable due in part to the large contribution of secondary PM

2.5

to total fine particle mass in most locations, and to the complexity of secondary particle formation processes. A large number of possible chemical reactions, often non-linear in nature, can convert gaseous NO

, SO

, VOC, and ammonia to PM

2.5

, making them precursors to PM

2.5

Formation of secondary PM

2.5

may also depend on atmospheric conditions, including solar radiation, temperature, and relative humidity, and the interactions of precursors with preexisting particles and with cloud or fog droplets.

“Air Quality Criteria for Particulate Matter” (EPA/600/P-99/002aF), EPA, October 2004, Chapter 3.

“Regulatory Impact Analysis for the Final Revisions to the National Ambient Air Quality Standards for Particulate Matter” (EPA/452/R-12-005), EPA, December 2012), 2-1.

Under subpart 4 of part D, title I of the CAA and the PM

2.5

SIP Requirements Rule, each state containing a PM

2.5

nonattainment area must evaluate all PM

2.5

precursors for regulation unless, for any given PM

2.5

precursor, the state demonstrates to the Administrator's satisfaction that such precursor does not contribute significantly to PM

2.5

levels that exceed the NAAQS in the nonattainment area.

The provisions of subpart 4 do not define the term “precursor” for purposes of PM

2.5

, nor do they explicitly require the control of any specifically identified PM

2.5

precursor. The statutory definition of “air pollutant,” however, provides that the term “includes any precursors to the formation of any air pollutant, to the extent the Administrator has identified such precursor or precursors for the particular purpose for which the term `air pollutant' is used.”

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.,

CAA section 189(e)).

81 FR 58010, 58017-58020.

CAA section 302(g).

81 FR 58010, 58015.

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

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 and RACT, BACM and BACT, MSM, and new source review (NSR)). 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, area, 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 because it does not contribute significantly to ambient PM

levels in the nonattainment area and is not needed for attainment.

Id. at 58018-58019.

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, then the state is not required to control emissions of the relevant precursor from sources in the attainment plan.

40 CFR 51.1006(a)(1).

Id.

In addition, in May 2019, the EPA issued the “Fine Particulate Matter (PM

2.5

) Precursor Demonstration Guidance” (“PM

2.5

Precursor Guidance”),

which provides recommendations to states for analyzing nonattainment area PM

2.5

emissions and developing such optional precursor demonstrations, consistent with the PM

2.5

SIP Requirements Rule. The PM

2.5

Precursor Guidance builds upon the draft version of the guidance, released on November 17, 2016 (“Draft PM

2.5

Precursor Guidance”), which CARB referenced in developing its precursor demonstration in the SJV PM

2.5

Plan.

The EPA's recommendations in the PM

2.5

Precursor Guidance are generally consistent with those in the Draft PM

2.5

Precursor Guidance, with some exceptions, including that the EPA's recommended contribution threshold for the 24-hour PM

2.5

NAAQS changed from 1.3 µg/m

in the draft guidance to 1.5 µg/m

in the final guidance.

“PM

2.5

Precursor Demonstration Guidance,” EPA-454/R-19-004, May 2019, including memorandum dated May 30, 2019 from Scott Mathias, Acting Director, Air Quality Policy Division and Richard Wayland, Director, Air Quality Assessment Division, Office of Air Quality Planning and Standards (OAQPS), EPA to Regional Air Division Directors, Regions 1-10, EPA.

“PM

2.5

Precursor Demonstration Guidance, Draft for Public Review and Comments,” EPA-454/P-16-001, November 17, 2016, including memorandum dated November 17, 2016 from Stephen D. Page, Director, OAQPS, EPA to Regional Air Division Directors, Regions 1-10, EPA.

For the 24-hour 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 1.5 μg/m

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

2.5

Precursor Guidance, 17.

We are evaluating the 1997 24-hour PM

2.5

NAAQS portion of the SJV PM

2.5

Plan in accordance with the presumption embodied within subpart 4, that states address all PM

2.5

precursors in the 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 and are not necessary for attainment. In reviewing any determination by a 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 the State's Submission

The State presents a brief summary of its PM

2.5

precursor analysis in Chapter 5 of the 2018 PM

2.5

Plan and the full precursor demonstration in Appendix G (“Precursor Demonstration”) of the 2018 PM

2.5

Plan.

100

CARB presents additional modeling results in Appendix K (“Modeling Attainment Demonstration”), section 5.6 (“PM

2.5

Precursor Sensitivity Analysis”). CARB also provided clarifying information on its precursor assessment, including an Attachment A to its letter transmitting the 2018 PM

2.5

Plan to the EPA

101

and further clarifications in five email transmittals.

102

The CARB Staff Report contains additional discussion of the role of ammonia in the formation of ammonium nitrate and the role of VOC in the formation of ammonium nitrate and secondary organic aerosol.

103

100

A copy of the contents of Appendix G appears in the CARB Staff Report, Appendix C4 (“Precursor Demonstrations for Ammonia, SO

, and ROG”).

101

Letter dated May 9, 2019, from Richard Corey, Executive Officer, CARB, to Michael Stoker, Regional Administrator, EPA Region 9, Attachment A (“Clarifying information for the San Joaquin Valley 2018 Plan regarding model sensitivity related to ammonia and ammonia controls”).

102

Email dated June 20, 2019, from Jeremy Avise, CARB, to Scott Bohning, EPA Region IX, Subject: “RE: SJV model disbenefit from SO

reduction,” with attachment (“CARB's June 2019 Precursor Clarification”); email dated September 19, 2019, from Jeremy Avise, CARB, to Scott Bohning, EPA Region IX, Subject: “FW: SJV species responses,” 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, Subject: “Clarifying information on ammonia,” with attachment “Clarifying Information on Ammonia” (“CARB's October 2019 Precursor Clarification”); email dated April 19, 2021, from Laura Carr, CARB, to Rory Mays, EPA Region IX, Subject: “Ammonia update,” with attachment “Update on Ammonia in the San Joaquin Valley” (“CARB's April 19, 2021 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”).

103

CARB Staff Report, Appendix C, 9-16. The CARB Staff Report, Appendix C4 (“Precursor Demonstrations for Ammonia, SO

, and ROG”) is very similar to the contents of Appendix G of the 2018 PM

2.5

Plan.

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 San Joaquin Valley. The State supplemented the sensitivity analysis, particularly for ammonia, with additional information, including factors identified in the PM

2.5

Precursor Guidance, such as emissions trends, the appropriateness of future year versus base year sensitivity, available emissions controls, and the severity of nonattainment.

104

These analyses led CARB to conclude that direct PM

2.5

and NO

emissions contribute significantly to ambient PM

2.5

levels that exceed the PM

2.5

NAAQS in the San Joaquin Valley while ammonia, SO

, and VOC do not contribute significantly to such exceedances.

105

We summarize the State's analysis and conclusions below. For a more detailed summary of the precursor demonstration in the Plan, please refer to the EPA's “Technical Support Document, EPA Evaluation of PM

2.5

Precursor Demonstration, San Joaquin Valley PM

2.5

Plan for the 2006 PM

2.5

NAAQS,” February 2020 (“EPA's February 2020 Precursor TSD”).

104

2.5

Precursor Guidance, 18-19 (consideration of additional information), 31 (available emissions controls), and 35-36 (appropriateness of future year versus base year sensitivity).

105

Direct PM

2.5

emissions are considered a primary source of ambient PM

2.5

(

i.e.,

no further formation in the atmosphere is required), and therefore is not considered a precursor pollutant under subpart 4, which may differ from a more generalized understanding of what contributes to ambient PM

2.5

For direct PM

2.5

and NO

, CARB modeled the sensitivity of ambient PM

2.5

in the San Joaquin Valley to a 30 percent reduction in anthropogenic emissions of each pollutant in 2013, 2020, and 2024.

106

The State concluded that direct PM

2.5

and NO

emissions reductions will continue to have a significant impact on 24-hour PM

2.5

design values in the San Joaquin Valley, with NO

reductions being particularly important.

107

Consistent with this conclusion, the State focused the control strategy and attainment demonstration on these two pollutants,

as described in section IV.C of this preamble.

106

2018 PM

2.5

Plan, Chapter 5, 5-7 to 5-8. CARB modeled the effects 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.

107

Id. at 5-8; and 2018 PM

2.5

Plan, Appendix G, 2. CARB presents its sensitivity analysis for emissions reductions in direct PM

2.5

and NO

in the Plan's attainment demonstration appendix. 2018 PM

2.5

Plan, Appendix K, Table 47 (annual average design values) and Table 48 (24-hour average design values).

For ammonia, SO

, and VOC, CARB assessed the 2015 annual average concentration of each precursor in ambient PM

2.5

at Bakersfield, for which the necessary speciated PM

2.5

data are available and where the highest PM

2.5

design values have been recorded in most years, and compared those concentrations to the recommended annual average contribution threshold of 0.2 µg/m

from the Draft PM

2.5

Precursor Guidance, which was available at the time the State developed the SIP.

108

The contributions of ammonia, SO

, and VOC were 5.2 µg/m

, 1.6 µg/m

, and 6.2 µg/m

, respectively. Given that these levels are well above the EPA's 0.2 µg/m

recommended contribution threshold, the State proceeded with a sensitivity-based analysis.

108

2018 PM

2.5

Plan, Appendix G, 3. The Plan does not present a concentration-based analysis for the 24-hour average concentrations in the San Joaquin Valley. Instead, CARB relied on the annual average concentration-based analysis as an interim step to the sensitivity-based analysis, for which CARB assessed the sensitivity of both 24-hour average and annual average ambient PM

2.5

concentrations to precursor emissions reductions. Separately, the Plan presents a graphical representation of annual average ambient PM

2.5

components (

i.e.,

crustal particulate matter, elemental carbon, organic matter, ammonium sulfate, and ammonium nitrate) for 2011-2013 for Bakersfield, Fresno, and Modesto. 2018 PM

2.5

Plan, Chapter 3, 3-3 to 3-4.

CARB's sensitivity-based analysis used the same Community Multiscale Air Quality (CMAQ) modeling platform as that used for the Plan's attainment demonstration. The State modeled the sensitivity of ambient PM

2.5

concentration in the San Joaquin Valley to 30 percent and 70 percent emissions reductions in 2013, 2020, and 2024 for each of ammonia, SO

, and VOC. The State estimated baseline (2013, 2020, and 2024) design values for PM

2.5

using relative response factors (RRFs) and calculated the ammonia, SO

, and VOC precursor contribution for a given year and for each sensitivity scenario (30 percent and 70 percent emissions reductions) as the difference between its baseline design value and the design value for each sensitivity scenario.

109

This procedure is the procedure recommended by the EPA. PM

2.5

Precursor Guidance, 37.

We summarize the State's sensitivity-based analysis and additional information in the sections that follow for ammonia, SO

, and VOC.

a. Ammonia

For ammonia, the State compared the 24-hour precursor contributions to 1.3 µg/m

, the recommended contribution threshold in the Draft PM

2.5

Precursor Guidance. For a modeled 30 percent ammonia emissions reduction, the ambient PM

2.5

responses in 2013 ranged from 0.9 to 3.3 µg/m

across 15 monitoring sites, with a majority of sites above the 1.3 µg/m

contribution threshold (and also above the 1.5 µg/m

contribution threshold in the final PM

2.5

Precursor Guidance). PM

2.5

responses in 2020 ranged from 0.5 to 1.9 µg/m

, with four sites at or above the 1.3 µg/m

contribution threshold, including one site above the 1.5 µg/m

contribution threshold in the final PM

2.5

Precursor Guidance. In 2024, all modeled responses were below both recommended contribution thresholds. For a modeled 70 percent ammonia emissions reduction, the ambient PM

2.5

responses in 2013 ranged from 3.5 to 12.4 µg/m

, with all monitoring sites above the 1.3 µg/m

threshold (and above the 1.5 µg/m

threshold), the PM

2.5

responses in 2020 ranged from 1.6 to 6.4 µg/m

, and the PM

2.5

responses in 2024 ranged from 1.2 to 3.0 µg/m

, with most sites above both recommended thresholds. For further detail, please see the EPA's February 2020 Precursor TSD, Table 2, and the 2018 PM

2.5

Plan, Appendix G, tables 2 through 7. In summary, for a 30 percent ammonia reduction, a majority of sites have PM

2.5

responses above the contribution threshold in the 2013 modeling, decreasing to a single site above the contribution threshold for 2020, and no sites above the contribution threshold for 2024. For a 70 percent reduction, all sites are above the contribution threshold in the 2013 and 2020 modeling, and a majority of sites are above the contribution threshold in 2024.

The State based its ammonia precursor determination on the sensitivity analysis for the future years, using a 30 percent ammonia emissions reduction. These choices respectively reflect its assessment of research studies and the Plan's projected emissions reductions, and on its assessment of available emissions controls. As explained in the PM

2.5

Precursor Guidance, precursor responses may be above the recommended contribution threshold and yet not contribute significantly to levels that exceed the standard in the area. Therefore, as recommended by the EPA, the State considered additional information to examine whether the identified PM

2.5

responses constituted a significant contribution to ambient PM

2.5

in the San Joaquin Valley. The additional information included research studies, emissions trends, and information to support the State's conclusion that a 30 percent ammonia emissions reduction represented a reasonable upper bound on the ammonia emissions reductions to model in estimating its contribution to ambient PM

2.5

levels. We summarize this additional information below and provide a more detailed evaluation in the EPA's February 2020 Precursor TSD.

The State describes previous research that supports its finding that ammonium nitrate PM

2.5

formation is the San Joaquin Valley is NO

-limited rather than ammonia-limited.

110

Essentially, ammonia is so abundant in the San Joaquin Valley that even with large ammonia emissions reductions there would still be enough ammonia to combine with the available NO

to readily form particulate ammonium nitrate. Therefore, ammonia emissions reductions would lead to only small decreases in PM

2.5

concentrations. In contrast, because emissions of NO

are less abundant in the San Joaquin Valley (

i.e.,

more limited relative to emissions of ammonia after normalizing for their differing molecular weights), the PM

2.5

concentrations in the atmosphere are more responsive to reductions in NO

than to reductions of ammonia. Thus, these analyses indicate that the area is NO

-limited.

110

2018 PM

2.5

Plan, Appendix G, 9-10; CARB Staff Report, Appendix C, 12-15; and Attachment A to CARB's May 9, 2019 submittal letter.

The State also points to the conclusions of a study conducted by Lurmann et al., based on ambient measurements during the winter 2000-2001 California Regional Particulate Air Quality Study intensive field study.

111

That study found that most areas of the San Joaquin Valley were NO

-limited with respect to ammonium nitrate formation. Since that time, large additional NO

emissions reductions have occurred, which would increase the degree to which ammonium nitrate formation in the San Joaquin Valley is NO

-limited. Based on more recent aircraft-borne measurements during the 2013 DISCOVER-AQ campaign,

112

the State similarly concluded that ammonium nitrate formation is NO

-limited based on the large amount of “excess ammonia,” which is defined as the amount of measured ammonia left over if all the nitrate and sulfate present

were to combine with available ammonia to form particulate.

113

The CARB Staff Report describes these conclusions in more detail and lists results from multiple other recent studies with similar conclusions.

114

Finally, in a supplemental submittal, CARB described the results of two analyses confirming the likely underestimation of ammonia emissions in the modeled emissions inventory inputs.

115

CARB compared CMAQ model predictions of ammonia with the 2013 DISCOVER-AQ aircraft measurements and found 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 valley-wide average was about 25 percent less than observed. Because the modeling performs well for the various PM

2.5

components, as well as for ozone and NO

116

the CARB finding of CMAQ model underpredictions for ammonia is consistent with an underestimation of ammonia emissions inventory input to the model.

111

Frederick W. Lurmann, Steven G. Brown, Michael C. McCarthy, and Paul T. Roberts, “Processes Influencing Secondary Aerosol Formation in the San Joaquin Valley during Winter,” Journal of the Air & Waste Management Association, (2006), 56:12, 1679-1693, DOI: 10.1080/10473289.2006.10464573.

112

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

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

113

2018 PM

2.5

Plan, Appendix G, Figure 2.

114

CARB Staff Report, Appendix C, 12.

115

CARB's April 26, 2021 Precursor Clarification.

116

EPA's February 2020 Modeling TSD, 21.

Regarding emissions trends, the CARB Staff Report presents an emissions inventory-based argument on the relative insensitivity of PM

2.5

to ammonia reductions.

117

CARB compared the size of the ammonia and NO

emissions inventories in tons per day, after normalizing for their differing molecular weights, and found that ammonia was roughly three times as abundant as NO

in 2013 and is projected to be about six times as abundant in 2025, due to the continuing decline in NO

emissions (while ammonia emissions are generally constant into the future).

118

While the State recognized that this is only a “first-level assessment,” it provides additional support for the State's conclusion that NO

, and not ammonia, is the limiting precursor for ammonium nitrate formation, and that the ammonium nitrate portion of ambient PM

2.5

would be expected to be relatively insensitive to ammonia emissions reductions. This is also consistent with the ammonia sensitivity modeling for the San Joaquin Valley, which showed that PM

2.5

concentrations will be less sensitive to ammonia reductions as NO

emissions go down in the future (

i.e.,

the PM

2.5

impacts were much smaller in the 2020 and 2024 future modeled cases compared to the 2013 base year).

117

CARB Staff Report, Appendix C, 15.

118

Annual average ammonia emissions are projected to decrease 4.6 tpd (1.4 percent) from 2013 to 2024. 2018 PM

2.5

Plan, Appendix B, Table B-5.

The State projected that NO

emissions in the San Joaquin Valley would decrease by 36 percent from 2013 to 2020, and by 53 percent from 2013 to 2024, while ammonia emissions would remain relatively flat, thereby increasing the relative abundance of ammonia.

119

Based on the Plan's emissions reduction projections combined with the research study conclusions, the State relies on the modeled responses for the future years, rather than the 2013 base year, stating that the future year NO

emissions are more representative of San Joaquin Valley emissions conditions.

120

The State references the Draft PM

2.5

Precursor Guidance, which notes that it may be appropriate to model future conditions that are more representative of current atmospheric conditions and those conditions expected closer to the attainment date. The State concludes that this in fact applies to the San Joaquin Valley.

121

119

2018 PM

2.5

Plan, Appendix G, 8-9.

120

Id. at 9.

121

Id (referencing Draft PM

2.5

Precursor Guidance, 33). See also PM

2.5

Precursor Guidance, 35.

With respect to the State's selection of 30 percent as an upper bound on the ammonia reductions to model, the State described its review of the most important ammonia source categories in the San Joaquin Valley, existing control measures that affect ammonia emissions from these sources, additional mitigation options for these sources, and information provided in the PM

2.5

Precursor Guidance about ammonia reductions achieved nationwide from 2011 to 2017.

122

The primary sources of ammonia emissions identified in the 2018 PM

2.5

Plan are: (1) Confined animal facilities (CAFs); (2) agricultural fertilizer; (3) biosolids, animal manure, and poultry litter operations; and (4) organic material composting operations.

123

CAFs are subject to District Rule 4570; biosolids, animal manure, and poultry litter operations are subject to District Rule 4565; and organic material composting operations are subject to District Rule 4566. Although these District rules explicitly apply only to VOC emissions from these sources, the State concludes that these rules also reduce ammonia emissions. Appendix C of the 2018 PM

2.5

Plan cites several scientific studies that address the correlation between VOC and ammonia emissions from these emissions sources.

124

Based on these evaluations, the State concludes that ammonia control measures achieving even the low end of the range (30 percent) are not feasible for implementation in the San Joaquin Valley and that it is therefore reasonable to treat a 30 percent ammonia reduction as an upper bound for modeling in the precursor demonstration.

122

2018 PM

2.5

Plan, Appendix G and Appendix C, section C-25, and CARB's October 2019 Precursor Clarification.

123

2018 PM

2.5

Plan, Appendix C, section C-25.

124

Id. at C-314 and following.

In summary, the State's sensitivity analysis presents a range of PM

2.5

responses to ammonia emissions reductions depending on base year versus future year, and on the scale of emissions reductions that may be possible. The Plan provides the State's bases for finding that the future year sensitivity results better represent conditions in the San Joaquin Valley than the 2013 base year and for finding a 30 percent ammonia reduction to be a reasonable upper bound for modeled ammonia emissions reductions in assessing the ammonia contribution. Based on these analyses, the State concludes that ammonia does not contribute significantly to ambient PM

2.5

levels above the 1997 24-hour PM

2.5

NAAQS in the San Joaquin Valley.

b. SO

For SO

, the State compared the 24-hour precursor contributions to the recommended draft contribution threshold of 1.3 µg/m

in the Draft PM

2.5

Precursor Guidance. For modeled SO

emissions reductions of 30 percent and 70 percent, the ambient PM

2.5

responses in 2013 ranged from −1.4 to 0.5 µg/m

across 15 monitoring sites, which all fall below the 1.3 µg/m

draft contribution threshold, and hence also below the contribution threshold of 1.5 µg/m

in the final version of the PM

2.5

Precursor Guidance.

125

The response was below zero at most monitoring sites, indicating an increase, rather than a decrease, in ambient PM

2.5

in response to SO

emissions reductions (

i.e.,

a disbenefit). Only the Stockton and Manteca sites had slightly positive responses to 30 percent and 70 percent emissions reductions, and the Tranquillity site also had a slightly positive response only to a 30 percent reduction. For the 15 sites, in 2020, the responses to 30 percent and 70 percent emissions reductions ranged from −1.3 µg/m

0.5 µg/m

while for 2024, the responses ranged from −1.1 µg/m

to 0.6 µg/m

; these are also all below the contribution threshold, with most sites showing a disbenefit from SO

reductions.

126

The Stockton, Manteca, and Tranquillity sites showed the same pattern of slight benefits as for 2013.

127

For further detail, please see the EPA's February 2020 Precursor TSD, Table 3 and the 2018 PM

2.5

Plan, Appendix G, tables 8 and 9 and Appendix K, tables 46, 48, and 50.

125

2018 PM

2.5

Plan, Appendix G, Table 8 and Table 9.

126

CARB's September 2019 Precursor Clarification, 2020 analysis tables 15 and 16, and 2024 analysis tables 15 and 16.

127

2018 PM

2.5

Plan, Appendix K, Table 48 and Table 50.

CARB also included additional information regarding emissions trends and an evaluation of the SO

emissions reduction disbenefit. We summarize this additional information below and provide a more detailed evaluation in the EPA's February 2020 Precursor TSD.

In terms of emissions trends, the State found that SO

emissions decreased from 2013 to 2014 and then were expected to very gradually rise to 7.8 tpd in 2020 and 8.0 tpd in 2024.

128

Given that projected SO

emissions are very similar in 2020 and 2024, the State concluded that the 2020 and 2024 sensitivity results were redundant. Comparing the ambient responses in 2013 and 2024, the State found that the responses were slightly less negative or, for a small number of sites, slightly higher in 2024, but still no more than 0.6 µg/m

in response to a 70 percent SO

emissions reduction.

129

This supports the State's conclusion as to the overall disbenefit of reducing SO

emissions.

128

2018 PM

2.5

Plan, Appendix G, Figure 4.

129

CARB's September 2019 Precursor Clarification, 2013 analysis Table 16 and 2024 analysis Table 16.

To explain the SO

emissions reduction disbenefit that is observed in some cases, CARB refers to the non-linearity of inorganic aerosol thermodynamics, as described in a study by West et al.

130

That paper discusses how, under certain conditions, reducing SO

could free ammonia to combine with nitrate, increasing overall PM

2.5

mass. To investigate this issue further, CARB conducted simulations with the ISORROPIA inorganic aerosol thermodynamic equilibrium model used within the CMAQ model and provided clarifications to the EPA.

131

In essence, CARB states that for some conditions typical of San Joaquin Valley, ISORROPIA switches to a different chemical regime in which the disbenefit occurs. CARB states that it is not known how well this model behavior reflects the actual atmosphere, but CARB accepts the results because it is a well-known and widely used chemical model.

130

2018 PM

2.5

Plan, Appendix K, section 5.6 (“PM

2.5

Precursor Sensitivity Analysis”); and West, J.J., Ansari, A.S., Pandis, S.N., 1999, Marginal PM

2.5

: Nonlinear aerosol mass response to sulfate reductions in the eastern United States,

Journal of the Air & Waste Management Association,

49, 1415-1424.

https://doi.org/10.1080/10473289.1999.10463973.

131

CARB's June 2019 Precursor Clarification.

Based on the small and mostly negative modeled response of ambient PM

2.5

to SO

emissions reductions, and based on its scientific understanding of sulfate interactions with other molecules in the air, the State concludes that SO

does not contribute significantly to ambient PM

2.5

levels that exceed the 1997 24-hour PM

2.5

NAAQS in the San Joaquin Valley.

c. VOC

For VOC, CARB compared the 24-hour precursor contributions to the EPA's recommended draft contribution threshold of 1.3 µg/m

. For a modeled 30 percent VOC emissions reduction, the ambient PM

2.5

responses in 2013 ranged from 0.1 to 1.9 µg/m

across 15 monitoring sites, with two sites above the 1.3 µg/m

draft contribution threshold.

132

133

The 2020 responses ranged from −0.1 to 0.6 µg/m

, with all monitoring sites below the 1.3 µg/m

draft contribution threshold, and hence also below the contribution threshold of 1.5 µg/m

that was finalized in the final PM

2.5

Precursor Guidance. The 2024 responses ranged from −0.4 to 0.0 µg/m

, with all monitoring sites below both the draft and final contribution thresholds. For a 70 percent VOC emissions reduction, the PM

2.5

responses in 2013 ranged from 0.2 to 4.8 µg/m

, including responses above both contribution thresholds at a majority of sites. The 2020 response ranged from −0.2 to 1.5 µg/m

, with one site at the final contribution threshold. The 2024 response ranged from −1.0 to 0.0 µg/m

with monitoring sites below both the contribution thresholds. In other words, in response to either a 30 percent or a 70 percent reduction in VOC emissions, CARB models a decrease in ambient PM

2.5

levels at all sites for 2013, whereas for 2020, there were just small decreases in ambient PM

2.5

levels at most sites and an increase at one site, and for 2024 there were increases in PM

2.5

at all sites,

i.e.,

a disbenefit. For further detail, please see the EPA's February 2020 Precursor TSD, Table 4, and the 2018 PM

2.5

Plan, Appendix G, tables 10 through 15.

132

2018 PM

2.5

Plan, Appendix G, Table 10.

133

We note that one site (Visalia) has a modeled response above the EPA's final recommended contribution threshold of 1.5 µg/m

and one additional site (Bakersfield-California Avenue) has a modeled response below the 1.5 µg/m

threshold but above the EPA's draft threshold of 1.3 µg/m

CARB then considered additional information to assess whether these PM

2.5

responses constituted a significant contribution to ambient PM

2.5

in the San Joaquin Valley, including emissions trends and an assessment of the modeled disbenefit of VOC emissions reductions. Regarding emissions trends, CARB found that VOC emissions would decrease approximately 30 tpd (or 9 percent) from 2013 to 2024, with approximately 28 out of the 30 tpd reduction taking place by 2020.

134

The State concludes that the formation of ambient PM

2.5

from VOC may therefore differ in base and future years and that the sensitivity analysis for 2013 is not representative of current or future conditions.

134

2018 PM

2.5

Plan, Appendix G, 19 and Figure 5.

CARB explained the modeled disbenefit of VOC reductions as follows: Emissions of VOC and NO

react in the atmosphere to form organic nitrate species, such as peroxyacetyl nitrate (PAN), meaning that some portion of the NO

emissions is not available to react with ammonia to form ammonium nitrate. In other words, VOC emissions are a “sink” for NO

emissions. Reducing VOC emissions therefore reduces the formation of organic nitrates, so the sink is smaller and nitrate molecules are freed to react with ammonia to form particulate ammonium nitrate.

135

The State further explored the VOC disbenefit based on a 2016 CARB modeling assessment provided in Appendix A (“Air Quality Modeling”) of the “2016 Moderate Area Plan for the 2012 PM

2.5

Standard” for the San Joaquin Valley (“2016 PM

2.5

Plan”), which CARB submitted to the EPA as a SIP revision on May 10, 2019.

136

135

2018 PM

2.5

Plan, Appendix K, 72 (citing Meng, Z., D. Dabdub, D., Seinfeld, J.H., Chemical Coupling Between Atmospheric Ozone and Particulate Matter,

Science

277, 116 (1997). DOI: 10.1126/science.277.5322.116).

136

2016 PM

2.5

Plan, Appendix A, A-57. See also 2018 PM

2.5

Plan, Appendix K, section 5.6 (“PM

2.5

Precursor Sensitivity Analysis”), 71-72.

Based on its sensitivity-based analysis of VOC emissions reductions, VOC emissions trends, and the scientific understanding of VOC chemistry in the San Joaquin Valley, CARB concludes that VOC emissions do not contribute significantly to PM

2.5

levels that exceed the 1997 24-hour PM

2.5

NAAQS in the San Joaquin Valley.

3. The EPA's Review of the State's Submission

The EPA has evaluated the State's precursor demonstration consistent with the PM

2.5

SIP Requirements Rule and the recommendations in the PM

2.5

Precursor Guidance. Based on this evaluation, the EPA agrees that NO

emissions contribute significantly to ambient PM

2.5

levels that exceed the 1997 24-hour PM

2.5

NAAQS in the San Joaquin Valley and that NO

emissions sources, therefore, remain subject to control requirements under subparts 1 and 4 of the part D, title I of the Act. For the reasons provided below, the EPA proposes to approve the State's demonstration that ammonia, SO

, and VOC emissions do not contribute significantly to ambient PM

2.5

levels that exceed the 1997 24-hour PM

2.5

NAAQS in the San Joaquin Valley.

Regarding the State's analytical approach, the EPA finds that the State based its analyses on the latest available data and studies concerning ambient PM

2.5

formation in the San Joaquin Valley from precursor emissions. Regarding the required concentration-based analysis, the EPA finds that the State assessed the absolute annual average contribution of each precursor in ambient PM

2.5

(

i.e.,

in 2015). On the basis of the absolute concentrations being well above the EPA's recommended contribution thresholds for both the 24-hour and annual average NAAQS, the State proceeded with its sensitivity-based analysis, which is the recommended sequence under the final PM

2.5

Precursor Guidance.

137

For further discussion of the EPA's evaluation of the State's concentration-based analysis, see the EPA's February 2020 Precursor TSD, sections entitled “Concentration-based analysis” within the EPA's evaluation for each of ammonia, SO

, and VOC.

With respect to the sensitivity-based analysis, we find that the State performed its analyses following the steps of the EPA's recommended approach—

i.e.,

for each modeled year and percent precursor emissions reduction, the State estimated the ambient PM

2.5

response using the procedure recommended in the PM

2.5

Precursor Guidance and compared the result to the recommended contribution threshold. The EPA also finds that the performance of the photochemical model was adequate for use in estimating the ambient PM

2.5

responses, as discussed in section J (“Air Quality Model Performance”) of the EPA's “Technical Support Document, EPA Evaluation of Air Quality Modeling, San Joaquin Valley PM

2.5

Plan for the 2006 PM

2.5

NAAQS,” February 2020 (“EPA's February 2020 Modeling TSD”). The State considered the EPA's recommended range of emissions reductions (30 percent to 70 percent) for the 2013 base year, the projected 2020 attainment year for the 1997 24-hour PM

2.5

NAAQS, and the projected 2024 attainment year for the 2006 PM

2.5

NAAQS, and quantified the estimated response of ambient PM

2.5

concentrations to precursor emissions changes for the first time in a PM

2.5

SIP submission for the San Joaquin Valley. The EPA finds that such quantification and CARB's consideration of additional information provide an informed basis on which to make a determination as to whether ammonia, SO

, and VOC do or do not contribute significantly to ambient PM

2.5

levels that exceed the 1997 24-hour PM

2.5

NAAQS in the San Joaquin Valley.

138

Therefore, we turn to our evaluation of the State's determination for each of these three precursor pollutants.

138

The State did not evaluate the 2015 Serious area attainment year. Because the year has passed and the area failed to attain by the Serious area attainment date, we will evaluate the precursor analysis for the Serious area plan based on the current section 189(d) projected attainment date of December 31, 2020.

a. Ammonia

For ammonia, as detailed above, CARB estimated the ambient PM

2.5

response to both a 30 percent and a 70 percent emissions reduction. We find that it was appropriate for the State to consider additional information to interpret those results to determine whether the ammonia contribution is significant. The primary conclusion demonstrated by the State's analysis of additional information is that ammonium nitrate formation is NO

-limited. As discussed in more detail below, we agree with this conclusion. We have evaluated CARB's determination that a projected future year is more representative of conditions in the San Joaquin Valley for sensitivity-based analyses and that 30 percent is a reasonable upper bound for ammonia emissions reductions to assess the precursor contribution, as discussed below.

The State provided ample information from scientific studies based on ambient measurements to help assess the estimated sensitivity of ambient PM

2.5

to ammonia reductions. Conclusions based on ambient data are particularly relevant because they provide direct evidence of the chemical state of the atmosphere and are not dependent on modeled estimates of emissions or modeled ambient PM

2.5

concentrations. Measurements represent the “real world” result of the pollutants' differing geographic distributions, the various meteorological and chemical factors influencing their conversion to particulate, and their removal from the atmosphere by deposition and other processes. The observed abundance of ammonia relative to nitric acid, and the positive amount of chemically excess ammonia, both provide strong evidence that ammonia is not the limiting pollutant for particulate ammonium nitrate formation. They also support the State's conclusion that PM

2.5

concentrations are insensitive to ammonia emissions reductions.

The relative amount of ammonia and NO

emissions is one of the most critical factors in determining the sensitivity of ambient PM

2.5

to ammonia reductions. We note that the model response to precursor reductions may be unrealistically large due to the underestimation of ammonia emissions and therefore of the ratio of ammonia to NO

emissions. There is evidence that ammonia emissions may be underestimated based on direct measurements of ammonia emissions flux during two measurement campaigns, as discussed in the EPA's February 2020 Precursor TSD. If ammonia emissions were higher in the modeling, then ammonia would be more abundant relative to nitrate and particulate nitrate formation would be more NO

-limited and less sensitive to ammonia reductions. This would make the model response more consistent with the ambient measurement studies, which suggest a very low sensitivity to ammonia. This evidence indicates that ammonia contribution to PM

2.5

levels above the standard is likely to be less than estimated by the State's modeling in each of the three years. In comparison to the 2013 and 2020 modeling, the modeling for the year 2024 incorporates lower NO

emissions and so has a larger abundance of ammonia relative to nitrate, more similar to the studies' ambient measurements. Thus, the 2024 response to ammonia reductions is likely to be more reliable than the 2013 and 2020 responses and appears to be more representative of current atmospheric conditions despite the use of emissions projections for a future year.

The relative sizes of the ammonia and NO

precursor emissions inventories after accounting for their differing molecular weights are a rough indicator of which pollutant is the limiting pollutant for production of ammonium nitrate because ammonium nitrate forms from a one-to-one ratio of molecules derived from each precursor (

i.e.,

one ammonium nitrate forms from one

ammonium and one nitrate). However, unlike measurements and photochemical modeling, a simple emissions ratio does not account for various processes mentioned above; it assumes all the emitted molecules find one another and react. The State found ammonia to be roughly three times as abundant as NO

in 2013 after accounting for their differing molecular weights, and even more abundant in future years. The EPA repeated the exercise to account for SO

and found that the ratio of total ammonia to the ammonia needed to react with both nitrate and sulfate ranged from 2.7 in 2013 to 5.6 in 2028. These results are approximately the same as the CARB NO

-only results because SO

emissions are very small relative to NO

and ammonia emissions (

e.g.,

in 2013, winter daily emissions were 8.4 tpd of SO

versus 300.5 tpd of NO

and 309.8 tpd of ammonia).

139

These observations support the State's finding that PM

2.5

is expected to be relatively insensitive to ammonia reductions, though they are not definitive on their own.

139

2018 PM

2.5

Plan, Appendix B, tables B-2, B-3, and B-4.

The State also points to large decreases or projected decreases in NO

emissions in the San Joaquin Valley from 2013 to 2024, including a 36 percent reduction from baseline measures by 2020, and a 53 percent reduction by 2024, while CARB projects that ammonia emissions will remain roughly constant (

i.e.,

decreasing 1-2 percent). In conjunction with the ambient evidence that ammonia is already chemically overabundant relative to NO

in the San Joaquin Valley, this indicates that the overabundance will become even greater in the future, and thus ambient PM

2.5

is expected to be even less responsive to ammonia reductions. This adds conservatism to the State's conclusions about ammonia sensitivity based on the scientific studies.

While the base year for an attainment plan for a given nonattainment area is generally more representative of current conditions, there can be situations in which is it more appropriate to use future conditions representative of when sources will operate, and the EPA believes that states may use either a base year or a future year for modeling an ambient PM

2.5

response to precursor emissions reductions, provided the state explains how the choice of analysis year and associated assumptions are appropriate.

140

The 2013 modeled responses cannot be considered current at the present time, in comparison to the 2020 results. Large NO

emissions reductions have occurred from 2013-2020 and are projected to continue to occur on through 2024, continuing to decrease the ratio of NO

to ammonia. In light of this ongoing trend, and the ambient data indicating that models underestimate ammonia, the EPA believes that future year results, which more accurately reflect the expected NO

to ammonia ratio, will continue to be representative, unlike the 2013 base year. These reductions are the result of regulations put in place by past air quality planning decisions and they will occur regardless of the actions that are being proposed herein. In assessing the effect of potential ammonia reductions, the EPA believes it is reasonable to account for these NO

reductions. In addition, as noted above, the greater abundance of ammonia relative to NO

in the 2024 year modeling is more consistent with recent ambient measurements, which suggest that the 2024 responses are more representative of current atmospheric conditions than the other model years for assessing sensitivity to ammonia reductions. Therefore, in consideration of the scientific studies and emissions trends, including the projected large amount of NO

emissions reductions through the attainment period, the EPA agrees that use of a future year is appropriate. Given the available research and ambient data, we conclude that the modeled 2024 year is the most representative of conditions in the San Joaquin Valley.

140

2.5

Precursor Guidance, 35-36.

Even if we were to set aside the more representative 2024 modeling, in the 2020 modeled responses, only the Bakersfield-Planz site is above the contribution threshold, at 1.9 µg/m

. A single value above the threshold is not determinative, particularly in light of the additional information provided above, indicating that the modeled values overestimate the contribution of ammonia to ambient PM

2.5

levels, and that the trend continues toward less contribution in the future as the ratio of NO

to ammonia continues to drop. Moreover, the monitored 2020 design value is attaining the 1997 24-hour PM

2.5

NAAQS because, as discussed above and in section V of this proposal, at the current time there are not PM

2.5

levels above the NAAQS. This is further evidence that the single 2020 modeled response above the contribution threshold is not a significant contribution to PM

2.5

levels in excess of the NAAQS, even if the 2020 modeling were considered representative.

In the context of interpreting the full set of modeling results for ammonia emissions reductions, the EPA also considered the State's conclusion that the absence of available ammonia controls for sources in the San Joaquin Valley supports its decision to treat a 30 percent reduction as a reasonable upper bound on the ammonia emissions reductions to model in estimating the precursor contribution. As the State correctly notes, the 30 percent to 70 percent range recommended by the EPA is based on historical NO

and SO

emissions reductions, and changes in ammonia emissions levels nationally from 2011 to 2017 ranged from a 9 percent decrease to a 6 percent increase.

141

The State's descriptions of past research relied upon to develop existing rules that apply to ammonia emissions sources, as well as ongoing research, show that it has considered the availability of ammonia controls both in the past and present context, and that the State has a basis for its conclusion that 30 percent is a reasonable upper bound on achievable reductions for ammonia.

141

Id. at 30, Table 2.

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

2.5

levels to reductions in ammonia using appropriate modeling techniques that performed well, and that the State's analysis and use of future year sensitivity data, both 2020 and 2024, is well-supported. We also find that the State adequately documented its basis for using a 30 percent reduction in ammonia emissions as an upper bound in the modeling to assess ambient sensitivity to ammonia emissions reductions. Based on 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 1997 24-hour PM

2.5

NAAQS in the San Joaquin Valley.

b. SO

For SO

, the State found that the ambient PM

2.5

responses to SO

emissions reductions were below the EPA's recommended contribution threshold of 1.3 µg/m

in the Draft PM

2.5

Precursor Guidance (and below the EPA recommended threshold of 1.5 µg/m

in the final PM

2.5

Precursor Guidance), and that for most sites there would be an increase in ambient PM

2.5

levels in response to SO

reductions (

i.e.,

a disbenefit). The EPA has evaluated the State's analysis of this disbenefit and resulting conclusion regarding significance.

Because the results of the sensitivity analysis were all below the EPA's recommended 24-hour contribution thresholds at both the 30 percent and 70

percent emissions reductions, and in both the 2013 base year and 2020 (and 2024) future year, it is not necessary to distinguish between the timing and scale of emissions reductions with respect to the response of ambient PM

2.5

levels as in the ammonia evaluation where the results diverged according to scale and timing of modeled emissions reductions. The EPA's February 2020 Precursor TSD contains additional detail on the EPA's evaluation of SO

as a PM

2.5

precursor, including the disbenefit associated with a reduction in SO

emissions. Accordingly, we find that the State's decision to rely on the 2013 sensitivity modeling results for a 30 percent SO

reduction is acceptable.

Therefore, on the basis of the modeled ambient PM

2.5

response to both a 30 percent and 70 percent reduction in SO

emissions in 2013, and on 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 1997 24-hour PM

2.5

NAAQS in the San Joaquin Valley.

c. VOC

For VOC, the State found that the ambient PM

2.5

response to VOC emissions reductions were generally below the EPA's recommended contribution threshold of 1.3 µg/m

in the Draft PM

2.5

Precursor Guidance and below the EPA's recommended threshold of 1.5 µg/m

in the final PM

2.5

Precursor Guidance, and often predicted an increase in ambient PM

2.5

levels in response to such reductions (

i.e.,

a disbenefit), except for a 70 percent emissions reduction for the 2013 base year, where the State predicted the ambient PM

2.5

response to be above both recommended thresholds at a majority of sites. The EPA has evaluated and agrees with the State's determination that the modeling for future years is more representative of conditions in the San Joaquin Valley than the 2013 modeling for sensitivity-based analyses and the State's resulting conclusion as to whether the contribution from VOC emissions is significant.

Regarding emissions trends, the EPA agrees that the 8.6 percent decrease in VOC emissions from 2013 to 2020 and the 9.2 percent projected decrease from 2013 to 2024 favors reliance on the future year modeling results. Furthermore, there is a large decrease in NO

emissions over this period, as discussed in the EPA's evaluation of ammonia, which affects the atmospheric chemistry with respect to ambient PM

2.5

formation from VOC emissions. The 9 percent VOC emissions reductions and the NO

emissions reductions are projected to result from implementation of existing baseline measures. We therefore find it reasonable to rely on future year 2020 or 2024 modeled responses to VOC emissions reductions, and both years show a disbenefit from VOC emissions reductions. The EPA also finds that the State provided a reasonable explanation for the VOC reduction disbenefit and evidence that it occurs in the San Joaquin Valley.

For 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 1997 24-hour PM

2.5

NAAQS in the San Joaquin Valley.

C. Attainment Plan Control Strategy

1. Statutory and Regulatory Requirements

Section 189(b)(1)(B) of the Act requires for any Serious PM

2.5

nonattainment area that the state submit provisions to assure that BACM for the control of PM

2.5

and PM

2.5

precursors shall be implemented no later than four years after the date the area is reclassified as a Serious area. The EPA has defined BACM in the PM

2.5

SIP Requirements Rule to mean “any technologically and economically feasible control measure that . . . can achieve greater permanent and enforceable emissions reductions of direct PM

2.5

emissions and/or emissions of PM

2.5

plan precursors from sources in the area than can be achieved through the implementation of RACM on the same source(s). BACM includes best available control technology (BACT).”

142

40 CFR 51.1000 (definitions). In longstanding guidance, the EPA has similarly defined BACM to mean, “among other things, the maximum degree of emissions reduction achievable for a source or source category, which is determined on a case-by-case basis considering energy, environmental, and economic impacts.” General Preamble Addendum, 42010, 42013.

Because the 2015 Serious area attainment date has passed, and the EPA found that the area failed to attain by the Serious area attainment date, we are evaluating the submission for compliance with the BACM/BACT requirements now, in conjunction with the State's SIP submission intended to meet both the Serious area plan and section 189(d) plan requirements.

The EPA generally considers BACM a control level that goes beyond existing RACM-level controls, for example by expanding the use of RACM controls or by requiring preventative measures instead of remediation.

143

Indeed, as implementation of BACM and BACT is required when a Moderate nonattainment area is reclassified as Serious due to its inability to attain the NAAQS through implementation of “reasonable” measures, it is logical that “best” control measures should represent a more stringent and potentially more costly level of control.

144

If RACM and RACT level controls of emissions have been insufficient to reach attainment, the CAA contemplates the implementation of more stringent controls, controls on more sources, or other adjustments to the control strategy are necessary to attain the NAAQS in the area.

143

81 FR 58010, 58081 and General Preamble Addendum, 42011, 42013.

144

Id. and General Preamble Addendum, 42009-42010.

Under the PM

2.5

SIP Requirements Rule, those control measures that otherwise meet the definition of BACM/BACT but “can only be implemented in whole or in part beginning four years after reclassification” are referred to as “additional feasible measures.”

145

In accordance with the requirements of CAA section 172(c)(6), a Serious area plan must include any additional feasible measures to control emissions of direct PM

2.5

and PM

2.5

precursors that are necessary and appropriate to provide for attainment of the relevant NAAQS as expeditiously as practicable and no later than the applicable attainment date.

146

145

40 CFR 51.1000, 40 CFR 51.1010(a)(4)(ii).

146

Because the Serious area attainment year has passed and the area failed to attain by the Serious area attainment date, we will evaluate the BACM/BACT and additional feasible measure analysis for the Serious area plan with respect to the current section 189(d) projected attainment date of December 31, 2020.

Consistent with longstanding guidance provided in the General Preamble Addendum, the preamble to the PM

2.5

SIP Requirements Rule discusses the following steps for determining BACM and BACT and additional feasible measures:

(1) Develop a comprehensive emissions inventory of the sources of PM

2.5

and PM

2.5

precursors;

(2) Identify potential control measures;

(3) Determine whether an available control measure or technology is technologically feasible;

(4) Determine whether an available control measure or technology is economically feasible; and

(5) Determine the earliest date by which a control measure or technology can be implemented in whole or in part.

147

81 FR 58010, 58083-58085.

The EPA allows consideration of factors such as physical plant layout,

energy requirements, needed infrastructure, and workforce type and habits when considering technological feasibility. For purposes of evaluating economic feasibility, the EPA allows consideration of factors such as the capital costs, operating and maintenance costs, and cost effectiveness (

i.e.,

cost per ton of pollutant reduced by a measure or technology) associated with the measure or control.

148

40 CFR 51.1010(a)(3) and 81 FR 58010, 58041-58042.

Once these analyses are complete, the state must use this information to develop enforceable control measures and submit them to the EPA for evaluation as SIP revisions to meet the basic requirements of CAA section 110 and any other applicable substantive provisions of the Act. The EPA is using these steps as guidelines in the evaluation of the BACM and BACT measures and related analyses in the SJV PM

2.5

Plan. Furthermore, because the EPA has not previously taken action to approve the California SIP as meeting the subpart 4 Moderate area planning requirements under CAA section 189 for the 1997 24-hour PM

2.5

NAAQS for the San Joaquin Valley area, the EPA is reviewing the SJV PM

2.5

Plan for compliance with those requirements.

149

The EPA does not normally conduct a separate evaluation to determine whether a Serious area plan's measures also meet the RACM requirements. As explained in the General Preamble Addendum, we interpret the BACM requirement as generally subsuming the RACM requirement—

i.e.,

if we determine that the measures are indeed the “best available,” we have necessarily concluded that they are “reasonably available.” (General Preamble Addendum, 42010). Therefore, a separate analysis to determine if the measures represent a RACM level of control is not necessary. A proposed approval of a Plan's provisions concerning implementation of BACM is also a proposed finding that the Plan provides for the implementation of RACM.

The overarching requirement for the CAA section 189(d) attainment control strategy is that it provides for attainment of the NAAQS as expeditiously as practicable.

150

The control strategy must include any additional measures (beyond those already adopted in previous nonattainment plans for the area as RACM/RACT or BACM/BACT) that are needed for the area to attain expeditiously. This includes reassessing any measures previously rejected during the development of any Moderate area or Serious area attainment plan control strategy.

151

The state must also demonstrate that it will, at a minimum, achieve an annual five percent reduction in emissions of direct PM

2.5

or any PM

2.5

plan precursor from sources in the area, based on the most recent emissions inventory for the area.

152

150

81 FR 58010, 58100.

151

40 CFR 50.1010(c)(2)(ii).

152

CAA section 189(d) and 40 CFR 51.1010(c).

In the PM

2.5

SIP Requirements Rule, the EPA clarified its interpretation of the statutory language in CAA section 189(d) requiring a state to submit a new attainment plan to achieve annual reductions “from the date of such submission until attainment,” to mean annual reductions beginning from the due date of such submission until the new projected attainment date for the area based on the new or additional control measures identified to achieve at least five percent emissions reductions annually.

153

This interpretation is intended to make clear that even if a state is late in submitting its CAA section 189(d) plan, the area must still achieve its annual five percent emissions reductions beginning from the date by which the state was required to make its CAA section 189(d) submission, not by some later date. Because the deadline for California to submit a section 189(d) plan for the 1997 PM

2.5

NAAQS in the San Joaquin Valley was December 31, 2016, one year after the December 31, 2015 attainment date for these NAAQS under CAA section 188(c)(2), the starting point for the five percent emissions reduction requirement under section 189(d) for this area is 2017.

153

81 FR 58010, 58101.

2. Summary of the State's Submission and the EPA's Evaluation and Proposed Action

a. Control Strategy

For the Serious area and section 189(d) plan requirements for the 1997 24-hour PM

2.5

NAAQS the State based the control strategy in the SJV PM

2.5

Plan on ongoing emissions reductions from baseline control measures.

154

As we use the term here, baseline measures are State and District regulations adopted prior to the development of the SJV PM

2.5

Plan that continue to achieve emissions reductions through the projected 2020 attainment year for the 1997 24-hour PM

2.5

NAAQS and beyond. The State describes the baseline measures in the 2018 PM

2.5

Plan in Chapter 4,

155

Appendix C (“Stationary Source Control Measure Analyses”), and Appendix D (“Mobile Source Control Measure Analyses”). The State incorporates reductions generated by these baseline measures into the projected baseline inventories and reductions resulting from District measures are individually quantified in Appendix C.

154

Because the 2015 Serious area attainment date has passed, and the EPA found that the area failed to attain by the Serious area attainment date, we are evaluating the control strategy for the Serious area requirements based on the timeline associated with the current section 189(d) projected attainment date of December 31, 2020.

155

2018 PM

2.5

Plan, Chapter 4, Table 4-2.

In the 2018 PM

2.5

Plan, CARB indicates that mobile sources emit over 85 percent of the NO

emissions in the San Joaquin Valley and that CARB has adopted and amended regulations to reduce public exposure to diesel particulate matter, which includes direct PM

2.5

and NO

, from “fuel sources, freight transport sources like heavy-duty diesel trucks, transportation sources like passenger cars and buses, and non-road sources like large construction equipment.”

156

2018 PM

2.5

Plan, Chapter 4, 4-9. For CARB's BACM analysis for mobile source measures, see 2018 PM

2.5

Plan, Appendix D, including analyses for on-road light-duty vehicles and fuels (starting on page D-17), on-road heavy-duty vehicles and fuels (starting on page D-35), and non-road sources (starting on page D-64).

Given the need for substantial emissions reductions from mobile and area sources to meet the NAAQS in California nonattainment areas, the State of California has developed stringent control measures for on-road and non-road mobile sources and the fuels that power them. California has unique authority under CAA section 209 (subject to a waiver or authorization as applicable by the EPA) to adopt and implement new emissions standards for many categories of on-road vehicles and engines and new and in-use non-road vehicles and engines. The EPA has approved many such mobile source regulations for which it has issued waiver authorizations as revisions to the California SIP.

157

For example, see 81 FR 39424 (June 16, 2016); 82 FR 14446 (March 21, 2017); and 83 FR 23232 (May 18, 2018).

CARB's mobile source program extends beyond regulations that are subject to the waiver or authorization process set forth in CAA section 209 to include standards and other requirements to control emissions from in-use heavy-duty trucks and buses, gasoline and diesel fuel specifications, and many other types of mobile sources. Generally, these regulations have also been submitted and approved as revisions to the California SIP.

158

For example, see the EPA's approval of standards and other requirements to control emissions from in-use heavy-duty diesel trucks (77 FR 20308, April 4, 2012), revisions to the California on-road reformulated gasoline and diesel fuel regulations (75 FR 26653, May 12, 2010), and revisions to the California motor vehicle inspection and maintenance program (75 FR 38023, July 1, 2010).

As to stationary and area sources, the SJV PM

2.5

Plan indicates that regulations adopted for prior attainment plans

continue to reduce emissions of NO

and direct PM

2.5

159

Specifically, Table 4-1 of the 2018 PM

2.5

Plan identifies 33 District measures that limit NO

and direct PM

2.5

emissions.

160

The EPA has approved each of the identified measures into the California SIP,

161

with two exceptions.

159

2018 PM

2.5

Plan, Chapter 4, 4-3. For the District's BACM analysis of stationary and area source measures, see 2018 PM

2.5

Plan, Appendix C.

160

2018 PM

2.5

Plan, Chapter 4, Table 4-1.

161

See EPA Region IX's website for information on District control measures that have been approved into the California SIP, available at:

https://www.epa.gov/sips-ca/epa-approved-san-joaquin-valley-unified-air-district-regulations-california-sip.

First, the District amended Rule 4905 (“Natural Gas-fired, Fan-type, Residential Central Furnaces”) on October 15, 2020, to extend the period during which manufacturers may pay emissions fees in lieu of meeting the rule's NO

emissions limits.

162

CARB submitted the amended rule to the EPA on December 30, 2020,

163

and the EPA has not yet proposed any action on this submission. The EPA approved a prior version of Rule 4905 into the California SIP on March 29, 2016.

164

As part of that rulemaking, the EPA noted that because of the option in Rule 4905 to pay mitigation fees in lieu of compliance with emissions limits, emissions reductions associated with the rule's emissions limits would not be creditable in any attainment plan without additional documentation.

165

Until the District submits the necessary documentation to credit emissions reductions achieved by Rule 4905 toward an attainment control strategy, this rule is not creditable for SIP purposes. The Plan indicates that the District attributed 0.06 tpd of NO

reductions between 2013 and 2020 to Rule 4905.

166

These emissions reductions have de minimis impacts on the attainment demonstration for the 1997 24-hour PM

2.5

NAAQS in the SJV PM

2.5

Plan.

162

SJVUAPCD, Final Draft Staff Report with Appendix for Proposed Amendments to Rule 4905, “Adopt Proposed Amendments to Rule 4905 (Natural Gas-fired, Fan-type Central Furnaces),” 2.

163

Letter dated December 28, 2020, from Richard W. Corey, Executive Officer, CARB, to John Busterud, Regional Administrator, EPA Region 9. CARB's submittal letter formally withdrew a previously amended version of Rule 4905 adopted by the District on June 21, 2018 and submitted to the EPA by CARB on November 21, 2018.

164

81 FR 17390 (March 29, 2016) (approving Rule 4905 as amended January 22, 2015).

165

EPA, Region IX Air Division, “Technical Support Document for EPA's Proposed Rulemaking for the California State Implementation Plan (SIP), San Joaquin Valley Unified Air Pollution Control District's Rule 4905, Natural Gas-Fired, Fan-Type Central Furnaces,” October 5, 2015, n. 8.

166

2018 PM

2.5

Plan, Appendix C, C-290.

Second, the 2018 PM

2.5

Plan lists Rule 4203 (“Particulate Matter Emissions from Incineration of Combustible Refuse”) as a baseline measure. This rule has not been approved into the California SIP.

167

Appendix C of the 2018 PM

2.5

Plan indicates, however, that the emissions inventory for incineration of combustible refuse is 0.00 tpd of NO

and 0.00 direct PM

2.5

from 2013 through 2020.

168

Thus, although the District included this rule as a baseline measure, there are no meaningful reductions associated with this rule that would affect the attainment demonstration in the SJV PM

2.5

Plan.

167

The EPA does not have any pending SIP submission for Rule 4203.

168

2018 PM

2.5

Plan, Appendix C, C-46.

In sum, although Table 4-1 of the 2018 PM

2.5

Plan identifies two baseline measures that are not creditable for SIP purposes at this time, we find that the total emissions reductions attributed to these measures in the future baseline inventories have de minimis effects on the attainment demonstration in the Plan.

b. Best Available Control Measures

We are evaluating the State's BACM demonstration for the 1997 24-hour PM

2.5

NAAQS against the section 189(b)(1)(B) Serious area plan BACM requirement, and the section 189(d) plan requirement to address all Serious area plan requirements that the State has not already met. Because we have already found that the State failed to attain the 1997 24-hour PM

2.5

NAAQS in the San Joaquin Valley area by the Serious area attainment date, and because we have not previously found that the state has met the BACM requirement for purposes of the 1997 24-hour PM

2.5

NAAQS, we are evaluating the State's submission against the Serious area BACM requirement in light of the section 189(d) control plan timeline. The State's BACM demonstration is presented in Appendix C (“Stationary Source Controls”) and Appendix D (“Mobile Source Control Measure Analyses”) of the 2018 PM

2.5

Plan.

169

As discussed in section IV.A of this proposed rule, Appendix B (“Emissions Inventory”) of the 2018 PM

2.5

Plan contains the planning inventories for direct PM

2.5

and all PM

2.5

precursors (NO

, SO

, VOC, and ammonia) for the San Joaquin Valley nonattainment area together with documentation to support these inventories. Each inventory includes emissions from stationary, area, on-road, and non-road emissions sources, and the State specifically identifies the condensable component of direct PM

2.5

for relevant stationary source and area source categories. As discussed in section IV.B of this proposed rule, the State concludes that the Plan should control emissions of PM

2.5

and NO

to reach attainment. Accordingly, the BACM and BACT evaluation in the Plan addresses potential controls for sources of those pollutants.

169

Appendices C and D also present an MSM analysis for the purposes of meeting a precondition for an extension of the Serious area attainment date under CAA section 188(e) for the 2006 PM

2.5

NAAQS. The San Joaquin Valley area is not subject to the MSM requirement for the 1997 24-hour PM

2.5

NAAQS. Thus, the EPA is evaluating the Plan's control strategy for implementation of BACM and BACT only.

For stationary and area sources, the District identifies the sources of direct PM

2.5

and NO

in the San Joaquin Valley that are subject to District emissions control measures and provides its evaluation of these regulations for compliance with BACM requirements in Appendix C of the 2018 PM

2.5

Plan. As part of its process for identifying candidate BACM and considering the technical and economic feasibility of additional control measures, the District reviewed the EPA's guidance documents on BACM, additional guidance documents on control measures for direct PM

2.5

and NO

emissions sources, and control measures implemented in other ozone and PM

2.5

nonattainment areas in California and other states.

170

The District also provides an analysis of several SIP-approved VOC regulations that, according to the District, also provide ammonia co-benefits.

171

Based on these analyses, the District concludes that all best available control measures for stationary and area sources are in place in the San Joaquin Valley for NO

and directly emitted PM

2.5

for purposes of meeting the BACM/BACT requirement for the 1997 24-hour PM

2.5

NAAQS. We provide an evaluation of many of the District's control measures for stationary sources and area sources in section III of the EPA's 1997 24-hour PM

2.5

TSD together with recommendations for possible future improvements to these rules.

170

2018 PM

2.5

Plan, Chapter 4, section 4.3.1.

171

2018 PM

2.5

Plan, Appendix C., section C.25.

For mobile sources, CARB identifies the sources of direct PM

2.5

and NO

in the San Joaquin Valley that are subject to the State's emissions control measures and provides its evaluation of these regulations for compliance with BACM requirements in Appendix D of the 2018 PM

2.5

Plan. Appendix D describes CARB's process for determining BACM, including identification of the sources of direct PM

2.5

and NO

in the San Joaquin

Valley, identification of potential control measures for such sources, assessment of the stringency and feasibility of the potential control measures, and adoption and implementation of feasible control measures.

172

2018 PM

2.5

Plan, Appendix D, Chapter II.

Mobile source categories for which CARB has primary responsibility for reducing emissions in California include most new and existing on- and non-road engines and vehicles and motor vehicle fuels. The SJV PM

2.5

Plan's BACM demonstration provides a general description of CARB's key mobile source programs and regulations and a comprehensive table listing on-road and non-road mobile source regulatory actions taken by CARB since 1985.

173

Id. at Table 17.

Appendix D of the 2018 PM

2.5

Plan also describes the current efforts of the eight local jurisdiction metropolitan planning organizations (MPOs) to implement cost-effective transportation control measures (TCMs) in the San Joaquin Valley.

174

TCMs are projects that reduce air pollutants from transportation sources by reducing vehicle use, traffic congestion, or vehicle miles traveled. TCMs are currently being implemented in the San Joaquin Valley as part of the Congestion Mitigation and Air Quality cost effectiveness policy adopted by the eight local jurisdiction MPOs and in the development of each Regional Transportation Plan (RTP). The Congestion Mitigation and Air Quality policy, which is included in a number of the District's prior attainment plan submissions for the ozone and PM

2.5

NAAQS, provides a standardized process for distributing 20 percent of the Congestion Mitigation and Air Quality funds to projects that meet a minimum cost effectiveness threshold beginning in fiscal year 2011. The MPOs revisited the minimum cost effectiveness standard during the development of their 2018 RTPs and 2019 Federal Transportation Improvement Program and concluded that they were implementing all reasonable transportation control measures.

175

Appendix D of the District's “2016 Ozone Plan for 2008 8-Hour Ozone Standard,” adopted June 16, 2016, contains a listing of adopted TCMs for the San Joaquin Valley.

176

174

Id. at D-127 and D-128.

175

Id. at D-127.

176

Id. and SJVUAPCD, “2016 Ozone Plan for 2008 8-Hour Ozone Standard” (adopted June 16, 2016), Appendix D, Attachment D, tables D-10 to D-17.

We have reviewed the State's and District's analysis and determination in the SJV PM

2.5

Plan that their baseline mobile, stationary, and area source control measures meet the requirements for BACM for sources of direct PM

2.5

and applicable PM

2.5

plan precursors (

i.e.,

) for purposes of the 1997 24-hour PM

2.5

NAAQS. In our review, we considered our evaluation of the State's and District's rules in connection with our approval of the demonstrations for BACM (including BACT) and MSM for the 2006 PM

2.5

NAAQS.

177

We find that the evaluation processes followed by CARB and the District in the SJV PM

2.5

Plan to identify potential BACM were generally consistent with the requirements of the PM

2.5

SIP Requirements Rule, the State's and District's evaluation of potential measures is appropriate, and the State and District have provided reasoned justifications for their rejection of potential measures based on technological or economic infeasibility. We also agree with the District's conclusion that all reasonable TCMs are being implemented in the San Joaquin Valley and propose to find that these TCMs implement BACM for transportation sources.

177

85 FR 44192.

For the foregoing reasons, we propose to find that the SJV PM

2.5

Plan provides for the implementation of BACM for sources of direct PM

2.5

and NO

as expeditiously as practicable in accordance with the requirements of CAA section 189(b)(1)(B), and in satisfaction of both the Serious area and section 189(d) plan requirements.

c. Section 189(d) Five Percent Requirement

The SJV PM

2.5

Plan's demonstration of annual five percent reductions in NO

emissions is in section 5.2 of the 2018 PM

2.5

Plan. As shown in Table 3, the demonstration uses the 2013 base year inventory as the starting point from which the five percent per year emissions reductions are calculated and uses 2017 as the year from which the reductions start. The target required reduction in 2017 is five percent of the base year (2013) inventory, which is a reduction of approximately 15.9 tpd of NO

, and the targets for subsequent years are additional reductions of five percent per year until the 2020 attainment year. The projected emissions inventories reflect NO

emissions reductions achieved by baseline control measures and the demonstration shows that these NO

emissions reductions are greater than the required five percent per year.

Table 3—2017-2020 Annual Five Percent Emissions Reductions Demonstration for the San Joaquin Valley

Year

% Reduction

from 2013

base year

5% Target

(tpd NO

)

CEPAM

inventory v1.05

(tpd NO

)

Meets 5%?

2013 (base year)

317.3

2017

301.3

233.4

Yes.

2018

285.5

221.5

Yes.

2019

269.6

214.5

Yes.

2020

253.8

203.3

Yes.

Source:

2018 PM

2.5

Plan, Table 5-2.

The EPA proposes to find that the State's use of 2017 as the starting point from which the five percent per year emissions reductions should begin is reasonable and consistent with the CAA. As discussed in section IV.C.1 of this document, the EPA interprets the language under CAA section 189(d) to require a state to submit a new attainment plan to achieve annual reductions “from the date of such submission until attainment.” The 2018 PM

2.5

Plan was not submitted until May 10, 2019. However, the Serious area attainment deadline for the San Joaquin Valley nonattainment area for the 1997 PM

2.5

NAAQS was December 31, 2015.

178

Accordingly, a plan submittal

to meet the requirements under section 189(d) was due by December 31, 2016, and reductions were required to occur as of that date. The decline in emissions from 2017 to 2020 shows that reductions did, in fact, occur within the required timeframe. Furthermore, the State's demonstration shows that NO

emissions reductions from 2017 to 2020 are greater than the required five percent per year. Thus, the EPA proposes to find that the SJV PM

2.5

Plan meets the CAA 189(d) requirement to provide for an annual reduction in PM

2.5

or PM

2.5

precursor emissions of not less than five percent of the amount of such emissions reported in the most recent inventory prepared for the area.

178

80 FR 18528.

D. Attainment Demonstration and Modeling

1. Statutory and Regulatory Requirements

Section 189(b)(1)(A) of the CAA requires that each Serious area plan include a demonstration (including air quality modeling) that the plan provides for attainment of the PM

2.5

NAAQS by the applicable attainment date. As discussed in section IV of this proposal, given that the outermost statutory Serious area attainment date for the San Joaquin Valley area (

i.e.,

December 31, 2015) has passed and that the EPA has already found that the SJV area failed to attain by that date, the EPA must evaluate the State's plan for attainment by a later attainment date. Given that the finding of failure to attain triggered the State's obligation to submit a new plan meeting the requirements of section 189(d), the EPA is evaluating the SJV PM

2.5

Plan in light of the outermost attainment date required in section 189(d). That section requires that the attainment date be as expeditious as practicable, but not later than five years following the EPA's finding that the area failed to attain the NAAQS by the applicable Serious area attainment date. In this case, the State projected such attainment by December 31, 2020,

i.e.,

by the relevant statutory date.

The PM

2.5

SIP Requirements Rule explains that the same general requirements that apply to Moderate and Serious area plans under CAA sections 189(a) and 189(b) should apply to plans developed pursuant to CAA section 189(d)—

i.e.,

the plan must include a demonstration (including air quality modeling) that the control strategy provides for attainment of the PM

2.5

NAAQS as expeditiously as practicable.

179

For purposes of determining the attainment date that is as expeditious as practicable, the state must conduct future year modeling that takes into account emissions growth, known controls (including any controls that were previously determined to be RACM/RACT or BACM/BACT), the five percent per year emissions reductions required by CAA section 189(d), and any other emissions controls that are needed for expeditious attainment of the NAAQS.

179

40 CFR 51.1011(b)(1); 81 FR 58010, 58102.

The EPA's PM

2.5

modeling guidance

180

(“Modeling Guidance” and “Modeling Guidance Update”) recommends that a photochemical model, such as the Comprehensive Air Quality Model with Extensions (CAMx) or Community Multiscale Air Quality Model (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.

181

The modeled response to the emissions 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 should be speciated using available chemical species measurements—that is, each day's measured PM

2.5

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

182

180

Memorandum dated November 29, 2018, from Richard Wayland, Air Quality Assessment Division, Office of Air Quality Planning and Standards, 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, Office of Air Quality Planning and Standards, EPA, to Regional Air Program Managers, EPA, Subject: “Update to the 24 Hour PM

2.5

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

181

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.

182

Modeling Guidance, section 4.5, “What is the Recommended Modeled Attainment Test for the 24-Hour NAAQS.”

2. Summary of the State's Submission

As discussed in section IV.C, the SJV PM

2.5

Plan includes a modeled demonstration projecting that the San Joaquin Valley would attain the 1997 24-hour PM

2.5

NAAQS by December 31, 2020, based on ongoing emissions reductions from baseline control measures. 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 and February of 2013.

183

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 (“Air Quality Challenges and Trends”) and the modeling results in Chapter 5.3 (“Attainment Demonstration and Modeling”) of the 2018 PM

2.5

Plan. The State provides a conceptual model of PM

2.5

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

183

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.

CARB's air quality modeling approach investigated the many inter-connected facets of modeling ambient PM

2.5

in the San Joaquin Valley, 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, adjustments to baseline air quality for modeling, the 2020 attainment test, and an unmonitored area analysis. CARB's supplemental weight of evidence analysis further supports the Plan's demonstration of attainment by the end of 2020. These analyses are generally consistent with the EPA's recommendations in the Modeling Guidance.

The model performance evaluation in Appendix K includes statistical and graphical measures of model performance. The magnitude and timing of predicted concentrations of total PM

2.5

, as well as of its ammonium and nitrate components, generally match the occurrence of elevated PM

2.5

levels in the measured observations. A comparison to other recent modeling efforts shows good model performance on bias, error, and correlation with measurements, for total PM

2.5

and for most of its chemical components. The Weight of Evidence Analysis shows the downward trend in NO

emissions along with a 70 percent decrease between 1999 and 2017 in the number of days above the 1997 24-hour PM

2.5

NAAQS.

184

The analysis also shows decreases in daily PM

2.5

concentrations during winter, and in the frequency of high PM

2.5

concentrations generally.

185

Available ambient air quality data show that total PM

2.5

and ammonium nitrate concentrations have declined over the 2004-2017 period, despite some increases from time to time.

186

These trends show that there has been an improvement in air quality due to emissions reductions in the San Joaquin Valley, although that point is not fully reflected in the 98th percentile statistic, which is the basis for the regulatory design value.

184

Weight of Evidence Analysis, 27-28, Figure 14, and Figure 24.

185

Id. at Figure 16 and Figure 17.

186

Id. at Figure 21.

The State conducted three CMAQ

187

simulations: (1) A 2013 base year simulation to demonstrate that the model reasonably reproduced the observed PM

2.5

concentrations in the San Joaquin Valley; (2) a 2013 baseline year simulation that was the same as the 2013 base year simulation but excluded exceptional event emissions, such as wildfire emissions; and (3) a 2020 future year simulation that reflects projected emissions growth and reductions due to controls that have already been adopted and implemented.

188

187

CMAQ Version 5.0.2.

188

2018 PM

2.5

Plan, 5-5.

Table 4 shows the 2013 base year and 2020 projected future year 24-hour PM

2.5

design values at monitoring sites in the San Joaquin Valley. As recommended by the EPA's guidance, the 2013 base year design value for modeling purposes is a weighted average of three monitored design values, to minimize the influence of year-to-year variability. The highest 2020 projected design value is 47.6 µg/m

at the Bakersfield-California monitoring site, which is below the 65 µg/m

level of the 1997 24-hour PM

2.5

NAAQS.

Table 4—Projected Future 24-Hour PM

2.5

Design Values at Monitoring Sites in the San Joaquin Valley (µ

g/m

)

Monitoring site

2013 Base

This text is long and has been trimmed here. Open the source document for the complete record.

This is a copy of a public record, reproduced as it was published. It is not legal advice, and it may not be the version a court would rely on. Check the official source before you cite it.