Proposed Rule2021-27796

Clean Air Plans; 2012 Fine Particulate Matter Serious Nonattainment Area Requirements; San Joaquin Valley, California

Primary source

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Published
December 29, 2021

Issuing agencies

Environmental Protection Agency

Abstract

The Environmental Protection Agency (EPA or "Agency") proposes to approve portions of two state implementation plan (SIP) revisions submitted by the State of California to meet Clean Air Act (CAA or "Act") requirements for the 2012 annual fine particulate matter (PM<INF>2.5</INF>) national ambient air quality standards (NAAQS or "standards") in the San Joaquin Valley (SJV) Serious nonattainment area. Specifically, the EPA proposes to approve the State's Serious area plan for the 2012 annual PM<INF>2.5</INF> NAAQS, submitted May 10, 2019, for all Serious PM<INF>2.5</INF> area requirements (except contingency measures), including emissions inventories, best available control measures, demonstrations of attainment and reasonable further progress, quantitative milestones, and motor vehicle emission budgets. We may, however, reconsider this proposal if, based on new information or public comments, we find that the State has not satisfied the statutory criteria for a Serious area PM<INF>2.5</INF> attainment plan. The EPA also proposes to disapprove the portions of the State's Serious area plan, and the contingency provisions of a third SIP submission regarding residential wood burning, that pertain to the Serious area contingency measurement requirements for the 2012 annual PM<INF>2.5</INF> NAAQS.

Full Text

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<title>Federal Register, Volume 86 Issue 247 (Wednesday, December 29, 2021)</title>
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[Federal Register Volume 86, Number 247 (Wednesday, December 29, 2021)]
[Proposed Rules]
[Pages 74310-74352]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2021-27796]



[[Page 74309]]

Vol. 86

Wednesday,

No. 247

December 29, 2021

Part IV





Environmental Protection Agency





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40 CFR Part 52





Clean Air Plans; 2012 Fine Particulate Matter Serious Nonattainment 
Area Requirements; San Joaquin Valley, California; Proposed Rule

Federal Register / Vol. 86 , No. 247 / Wednesday, December 29, 2021 / 
Proposed Rules

[[Page 74310]]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R09-OAR-2021-0884; FRL-9292-01-R9]


Clean Air Plans; 2012 Fine Particulate Matter Serious 
Nonattainment Area Requirements; San Joaquin Valley, California

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA or ``Agency'') 
proposes to approve portions of two state implementation plan (SIP) 
revisions submitted by the State of California to meet Clean Air Act 
(CAA or ``Act'') requirements for the 2012 annual fine particulate 
matter (PM<INF>2.5</INF>) national ambient air quality standards (NAAQS 
or ``standards'') in the San Joaquin Valley (SJV) Serious nonattainment 
area. Specifically, the EPA proposes to approve the State's Serious 
area plan for the 2012 annual PM<INF>2.5</INF> NAAQS, submitted May 10, 
2019, for all Serious PM<INF>2.5</INF> area requirements (except 
contingency measures), including emissions inventories, best available 
control measures, demonstrations of attainment and reasonable further 
progress, quantitative milestones, and motor vehicle emission budgets. 
We may, however, reconsider this proposal if, based on new information 
or public comments, we find that the State has not satisfied the 
statutory criteria for a Serious area PM<INF>2.5</INF> attainment plan. 
The EPA also proposes to disapprove the portions of the State's Serious 
area plan, and the contingency provisions of a third SIP submission 
regarding residential wood burning, that pertain to the Serious area 
contingency measurement requirements for the 2012 annual 
PM<INF>2.5</INF> NAAQS.

DATES: Any comments must arrive by January 28, 2022.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R09-
OAR-2021-0884, at <a href="https://www.regulations.gov">https://www.regulations.gov</a>. For comments submitted 
at <a href="http://Regulations.gov">Regulations.gov</a>, follow the online instructions for submitting 
comments. Once submitted, comments cannot be edited or removed from 
<a href="http://Regulations.gov">Regulations.gov</a>. The EPA may publish any comment received to its public 
docket. Do not submit electronically any information you consider to be 
Confidential Business Information (CBI) or other information whose 
disclosure is restricted by statute. Multimedia submissions (audio, 
video, etc.) must be accompanied by a written comment. The written 
comment is considered the official comment and should include 
discussion of all points you wish to make. The EPA will generally not 
consider comments or comment contents located outside of the primary 
submission (i.e., on the web, cloud, or other file sharing system). For 
additional submission methods, please contact the person identified in 
the FOR FURTHER INFORMATION CONTACT section. For the full EPA public 
comment policy, information about CBI or multimedia submissions, and 
general guidance on making effective comments, please visit <a href="https://www.epa.gov/dockets/commenting-epa-dockets">https://www.epa.gov/dockets/commenting-epa-dockets</a>.

FOR FURTHER INFORMATION CONTACT: Rory Mays, Air Planning Office (AIR-
2), EPA Region IX, (415) 972-3227, <a href="/cdn-cgi/l/email-protection#593438202a772b362b20193c2938773e362f"><span class="__cf_email__" data-cfemail="b0ddd1c9c39ec2dfc2c9f0d5c0d19ed7dfc6">[email&#160;protected]</span></a>.

SUPPLEMENTARY INFORMATION: Throughout this document, ``we,'' ``us,'' 
and ``our'' refer to the EPA.

Table of Contents

I. Background for Proposed Action
II. Summary and Completeness Review of Applicable SIP Submissions
    A. San Joaquin Valley 2018 PM<INF>2.5</INF> Plan
    B. Valley State SIP Strategy
    C. Rule 4901 Contingency Provision
III. Clean Air Act Requirements for PM<INF>2.5</INF> Serious Area 
Plans
IV. Review of the San Joaquin Valley PM<INF>2.5</INF> Serious Area 
Plan
    A. Emissions Inventory
    B. PM<INF>2.5</INF> Precursors
    C. Air Quality Modeling
    D. Best Available Control Measures
    E. Nonattainment New Source Review Requirements Under CAA 
Section 189(e)
    F. Attainment Demonstration
    G. Reasonable Further Progress and Quantitative Milestones
    H. Contingency Measures
    I. Motor Vehicle Emission Budgets
V. Summary of Proposed Actions and Request for Public Comment
VI. Statutory and Executive Order Reviews

I. Background for Proposed Action

    On January 15, 2013, the EPA strengthened the primary annual NAAQS 
for particulate matter with a diameter of 2.5 microns or less 
(PM<INF>2.5</INF>) by lowering the level from 15.0 micrograms per cubic 
meter ([micro]g/m\3\) to 12.0 [micro]g/m\3\ (``2012 annual 
PM<INF>2.5</INF> NAAQS'').\1\ The EPA established these standards after 
considering substantial evidence from numerous health studies 
demonstrating that serious health effects are associated with exposures 
to PM<INF>2.5</INF> concentrations above these levels.
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    \1\ 78 FR 3086 and 40 CFR 50.18. The EPA first established NAAQS 
for PM<INF>2.5</INF> on July 18, 1997 (62 FR 38652), including 
annual standards of 15.0 [micro]g/m\3\ based on a 3-year average of 
annual mean concentrations and 24-hour (daily) standards of 65 
[micro]g/m\3\ based on a 3-year average of 98th percentile 24-hour 
concentrations (40 CFR 50.7) (``1997 PM<INF>2.5</INF> NAAQS''). In 
addition, on October 17, 2006, the EPA strengthened the 24-hour 
(daily) NAAQS for PM<INF>2.5</INF> by lowering the level from 65 
[micro]g/m\3\ to 35 [micro]g/m\3\ (``2006 24-hour PM<INF>2.5</INF> 
NAAQS''). 71 FR 61144 and 40 CFR 50.13. Unless otherwise noted, all 
references to the PM<INF>2.5</INF> standards in this notice, 
including all instances of ``2012 annual PM<INF>2.5</INF> NAAQS,'' 
are to the 2012 primary annual NAAQS of 12.0 [micro]g/m\3\ codified 
at 40 CFR 50.18.
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    Epidemiological studies have shown statistically significant 
correlations between elevated PM<INF>2.5</INF> levels and premature 
mortality. Other important health effects associated with 
PM<INF>2.5</INF> exposure include aggravation of respiratory and 
cardiovascular disease (as indicated by increased hospital admissions, 
emergency room visits, absences from school or work, and restricted 
activity days), changes in lung function, and increased respiratory 
symptoms. Individuals particularly sensitive to PM<INF>2.5</INF> 
exposure include older adults, people with heart and lung disease, and 
children.\2\ Sources can emit PM<INF>2.5</INF> directly into the 
atmosphere as a solid or liquid particle (``primary PM<INF>2.5</INF>'' 
or ``direct PM<INF>2.5</INF>'') or it can form in the atmosphere 
(``secondary PM<INF>2.5</INF>'') as a result of various chemical 
reactions among precursor pollutants such as nitrogen oxides 
(NO<INF>X</INF>), sulfur oxides (SO<INF>X</INF>), volatile organic 
compounds (VOC), and ammonia (NH<INF>3</INF>).\3\
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    \2\ 78 FR 3086, 3088.
    \3\ EPA, Air Quality Criteria for Particulate Matter, No. EPA/
600/P-99/002aF and EPA/600/P-99/002bF, October 2004.
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    Following promulgation of a new or revised NAAQS, the EPA is 
required by CAA section 107(d) to designate areas throughout the nation 
as attaining or not attaining the NAAQS. On January 15, 2015, the EPA 
designated and classified the SJV as Moderate nonattainment for the 
2012 annual PM<INF>2.5</INF> NAAQS.\4\ The EPA has approved the State's 
demonstration that it was impracticable to attain the 2012 annual 
PM<INF>2.5</INF> NAAQS by the outermost December 31, 2021 Moderate area 
attainment date and related plan elements addressing the Moderate area 
requirements for the 2012 annual PM<INF>2.5</INF> NAAQS, except for the 
contingency measure element, which the EPA disapproved.\5\ In that same 
action, the EPA reclassified the SJV as a Serious nonattainment area 
for these NAAQS.
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    \4\ 80 FR 2206 (codified at 40 CFR 81.305).
    \5\ 86 FR 67343 (November 26, 2021).
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    On December 27, 2021, the effective date of the SJV's 
reclassification as a Serious PM<INF>2.5</INF> nonattainment area, the 
SJV will become subject to a new statutory attainment date no later 
than the end of the tenth calendar year following designation (i.e., 
December

[[Page 74311]]

31, 2025) and the requirement to submit a Serious area plan satisfying 
the requirements of CAA Title I, part D, including the requirements of 
subpart 4, for the 2012 annual PM<INF>2.5</INF> NAAQS.\6\ As explained 
in the EPA's final reclassification action, the Serious area plan for 
the SJV must include, among other things, provisions to assure that, 
under CAA section 189(b)(1)(B), the best available control measures 
(BACM) for the control of direct PM<INF>2.5</INF> and PM<INF>2.5</INF> 
precursors shall be implemented no later than four years after the area 
is reclassified and a demonstration (including air quality modeling) 
that the plan provides for attainment as expeditiously as practicable 
but no later than December 31, 2025, or by the most expeditious 
alternative date practicable and no later than December 31, 2030, in 
accordance with the requirements of CAA sections 189(b) and 188(e). As 
described in our final action reclassifying the SJV as a Serious 
PM<INF>2.5</INF> nonattainment area, California must adopt and submit a 
SIP submission addressing the Serious nonattainment area requirements 
for the 2012 annual PM<INF>2.5</INF> NAAQS within 18 months (i.e., by 
June 27, 2023), for emissions inventories, BACM, and nonattainment new 
source review (NSR), and by December 31, 2023, for the attainment 
demonstration and related planning requirements.
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    \6\ Id. at 67347.
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    The SJV PM<INF>2.5</INF> 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.\7\ The area is home to four million people and is the 
nation's leading agricultural region. Stretching over 250 miles from 
north to south and averaging 80 miles wide, it is partially enclosed by 
the Coast Mountain range to the west, the Tehachapi Mountains to the 
south, and the Sierra Nevada range to the east. The CAA assigns primary 
responsibility to the state for developing plans to attain the NAAQS. 
Under State law, California divides this responsibility between the San 
Joaquin Valley Unified Air Pollution Control District (SJVUAPCD or 
District) and the California Air Resources Board (CARB) in preparing 
attainment plans. Authority for regulating sources under state 
jurisdiction in the SJV is split between the District, which has 
responsibility for regulating stationary and most area sources, and 
CARB, which has responsibility for regulating most mobile sources.
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    \7\ For a precise description of the geographic boundaries of 
the SJV PM<INF>2.5</INF> nonattainment area, see 40 CFR 81.305.
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II. Summary and Completeness Review of Applicable SIP Submissions

    The EPA is proposing action on portions of three SIP revisions 
submitted by CARB to meet the Serious nonattainment area requirements 
for the 2012 annual PM<INF>2.5</INF> NAAQS in the SJV. Specifically, 
the EPA is proposing to act on those portions of the following two plan 
submissions that pertain to the Serious area requirements for the 2012 
annual PM<INF>2.5</INF> NAAQS: The ``2018 Plan for the 1997, 2006, and 
2012 PM<INF>2.5</INF> Standards,'' adopted by the SJVUAPCD on November 
15, 2018, and by CARB on January 24, 2019 (``2018 PM<INF>2.5</INF> 
Plan''); \8\ and the ``San Joaquin Valley Supplement to the 2016 State 
Strategy for the State Implementation Plan,'' adopted by CARB on 
October 25, 2018 (``Valley State SIP Strategy'').
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    \8\ The 2018 PM<INF>2.5</INF> Plan was developed jointly by CARB 
and the District.
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    We refer to the relevant portions of these SIP submissions 
collectively in this proposal as the ``SJV PM<INF>2.5</INF> Plan'' or 
``Plan.'' The SJV PM<INF>2.5</INF> Plan addresses attainment plan 
requirements for multiple PM<INF>2.5</INF> NAAQS in the SJV, including 
the Serious area attainment plan requirements for the 2012 annual 
PM<INF>2.5</INF> NAAQS. CARB submitted the SJV PM<INF>2.5</INF> Plan to 
the EPA as a revision to the California SIP on May 10, 2019.\9\ It 
became complete by operation of law on November 10, 2019.\10\
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    \9\ Letter dated May 9, 2019, from Richard W. Corey, Executive 
Officer, CARB, to Mike Stoker, Regional Administrator, EPA Region 
IX. Previously, in separate rulemakings, the EPA has finalized 
action on the portions of the SJV PM<INF>2.5</INF> Plan that pertain 
to the 1997 annual PM<INF>2.5</INF> NAAQS, the 2006 24-hour 
PM<INF>2.5</INF> NAAQS, and the Moderate area plan for the 2012 
annual PM<INF>2.5</INF> NAAQS. See 86 FR 67329 (November 26, 2021) 
(final rule regarding the 1997 annual PM<INF>2.5</INF> NAAQS); 85 FR 
44192 (July 22, 2020) (final rule regarding the 2006 24-hour 
PM<INF>2.5</INF> NAAQS, except contingency measures); and 86 FR 
67343 (final rule regarding the Moderate area plan for the 2012 
annual PM<INF>2.5</INF> NAAQS and contingency measures for the 2006 
24-hour PM<INF>2.5</INF> NAAQS). The EPA has also separately 
proposed action on the portions of the SJV PM<INF>2.5</INF> Plan 
that pertain to the 1997 24-hour PM<INF>2.5</INF> NAAQS. 86 FR 53150 
(September 24, 2021).
    \10\ We note that, with respect to plans previously required for 
the 1997, 2006, and 2012 PM<INF>2.5</INF> NAAQS, including the 
Moderate area plan only for the 2012 annual PM<INF>2.5</INF> NAAQS, 
the EPA had made findings of failure to submit effective January 7, 
2019, that triggered sanctions clocks. 83 FR 62720 (December 6, 
2018). Following the May 10, 2019 submission of the 2018 
PM<INF>2.5</INF> Plan and Valley State SIP Strategy, the EPA 
affirmatively determined that the SIP submissions addressed the 
deficiency that was the basis for such findings, resulting in the 
termination of the associated sanctions clocks. Letter dated June 
24, 2020, from Elizabeth Adams, Director, Air and Radiation 
Division, EPA Region IX, to Richard W. Corey, Executive Officer, 
CARB. However, neither the findings nor completeness determination 
applied to the Serious area plan for the 2012 annual 
PM<INF>2.5</INF> NAAQS as it was not yet required.
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    In addition, the EPA is proposing action on the portion of a third 
SIP submission that pertains to SJVUAPCD Rule 4901, as amended by the 
District on June 20, 2019, and submitted to the EPA on July 19, 2019 
(``Rule 4901 Contingency Provision''). The EPA has already taken final 
action on the rule modification for this submission.\11\ In this action 
we are evaluating the submission for purposes of addressing the 
contingency measures requirement in the SJV for the 2012 annual 
PM<INF>2.5</INF> NAAQS.
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    \11\ 85 FR 44206 (July 22, 2020) (final approval of District 
Rule 4901); 85 FR 1131, 1132-33 (January 9, 2020) (proposed approval 
of District Rule 4901). Completeness review for this submission was 
conducted and described in that action. See also 86 FR 67329 
(removing the contingency provision from the SIP).
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    CAA sections 110(a)(1) and (2) and 110(l) require each state to 
provide reasonable public notice and opportunity for public hearing 
prior to the adoption and submission of a SIP or SIP revision to the 
EPA. To meet this requirement, every SIP submission should include 
evidence that adequate public notice was given and that an opportunity 
for a public hearing was provided consistent with the EPA's 
implementing regulations in 40 CFR 51.102.
    CAA section 110(k)(1)(B) requires the EPA to determine whether a 
SIP submission is complete within 60 days of receipt. This section also 
provides that any plan that the EPA has not affirmatively determined to 
be complete or incomplete will become complete by operation of law six 
months after the date of submission. The EPA's SIP completeness 
criteria are found in 40 CFR part 51, Appendix V.

A. San Joaquin Valley 2018 PM2.5 Plan

    The following portions of the 2018 PM<INF>2.5</INF> Plan and 
related support documents address the Serious area requirements for the 
2012 annual PM<INF>2.5</INF> NAAQS in the SJV: (i) Chapter 4 
(``Attainment Strategy for PM<INF>2.5</INF>''); (ii) Chapter 7 
(``Demonstration of Federal Requirements for the 2012 PM<INF>2.5</INF> 
Standard''); \12\ (iii) numerous appendices to the 2018 
PM<INF>2.5</INF> Plan; (iv) CARB's ``Staff Report, Review of the San 
Joaquin Valley 2018 Plan for the 1997, 2006, and 2012 PM<INF>2.5</INF> 
Standards,'' release date December 21, 2018 (``CARB

[[Page 74312]]

Staff Report''); \13\ and (v) the State's and District's board 
resolutions adopting the 2018 PM<INF>2.5</INF> Plan (CARB Resolution 
19-1 and SJVUAPCD Governing Board Resolution 18-11-16).\14\ The 
SJVUAPCD Governing Board Resolution 18-11-16 includes emission 
reduction commitments on which the SJV PM<INF>2.5</INF> Plan 
relies.\15\
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    \12\ Chapter 5 (``Demonstration of Federal Requirements for the 
1997 PM<INF>2.5</INF> Standard'') and Chapter 6 (``Demonstration of 
Federal Requirements for the 2006 PM<INF>2.5</INF> Standard'') of 
the 2018 PM<INF>2.5</INF> Plan pertain to the 1997 PM<INF>2.5</INF> 
NAAQS and 2006 24-hour PM<INF>2.5</INF> NAAQS, respectively.
    \13\ The CARB Staff Report includes CARB's review of, among 
other things, the 2018 PM<INF>2.5</INF> Plan's control strategy and 
attainment demonstration. Letter dated December 11, 2019, from 
Richard W. Corey, Executive Officer, CARB to Mike Stoker, Regional 
Administrator, EPA Region IX, transmitting the CARB Staff Report.
    \14\ CARB Resolution 19-1, ``2018 PM<INF>2.5</INF> 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<INF>2.5</INF> 
Standards,'' November 15, 2018.
    \15\ SJVUAPCD Governing Board Resolution 18-11-16, paragraph 6, 
10-11.
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    The appendices to the 2018 PM<INF>2.5</INF> Plan, in order of their 
evaluation in this proposed rule, include: (i) App. B (``Emissions 
Inventory''); (ii) App. A (``Ambient PM<INF>2.5</INF> Data Analysis''); 
(iii) a plan precursor demonstration and clarifications, including App. 
G (``Precursor Demonstration'') and Attachment A (``Clarifying 
information for the San Joaquin Valley 2018 Plan regarding model 
sensitivity related to ammonia and ammonia controls'') to the CARB 
Staff Report; (iv) control strategy appendices, including App. C 
(``Stationary Source Control Measure Analyses''), App. D (``Mobile 
Source Control Measures Analyses''), and App. E (``Incentive-Based 
Strategy''); (v) modeling appendices, including App. J (``Modeling 
Emission Inventory''), App. K (``Modeling Attainment Demonstration''), 
and App. L (``Modeling Protocol''); (vi) App. H (``RFP, Quantitative 
Milestones, and Contingency''); and (vii) App. I (``New Source Review 
and Emission Reduction Credits''). The 2018 PM<INF>2.5</INF> Plan 
addresses motor vehicle emission budget requirements in the 
``Transportation Conformity'' section of App. D (pages D-119 to D-131). 
The 2018 PM<INF>2.5</INF> Plan also includes an Executive Summary, 
Introduction (Ch. 1), chapters on ``Air Quality Challenges and Trends'' 
(Ch. 2) and ``Health Impacts and Health Risk Reduction Strategy'' (Ch. 
3), and an appendix on ``Public Education and Technology Advancement'' 
(App. F).
    The District provided public notice and opportunity for public 
comment prior to its November 15, 2018 public hearing on and adoption 
of the 2018 PM<INF>2.5</INF> Plan.\16\ 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<INF>2.5</INF> Plan.\17\ 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.\18\ Therefore, we 
reaffirm that the 2018 PM<INF>2.5</INF> 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<INF>2.5</INF> Plan became 
complete by operation of law on November 10, 2019, pursuant to CAA 
section 110(k)(1)(B).
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    \16\ SJVUAPCD, ``Notice of Public Hearing for Adoption of 
Proposed 2018 PM<INF>2.5</INF> Plan for the 1997, 2006, and 2012 
Standards,'' October 16, 2018, and SJVUAPCD Governing Board 
Resolution 18-11-16.
    \17\ CARB, ``Notice of Public Meeting to Consider the 2018 
PM<INF>2.5</INF> State Implementation Plan for the San Joaquin 
Valley,'' December 21, 2018, and CARB Resolution 19-1.
    \18\ 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<INF>2.5</INF> Plan, App. M (``Summary of Significant 
Comments and Responses'').
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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 SJV and Los Angeles-South Coast Air Basin 
(``South Coast'') ozone nonattainment areas.\19\ 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<INF>X</INF> emission reductions and 0.1 tpd of direct 
PM<INF>2.5</INF> emission reductions in the SJV by 2025 from source 
categories under the regulatory authority of CARB. The resolution 
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<INF>2.5</INF> NAAQS for 
the SJV and to return to the Board with a commitment to achieve 
additional emission reductions from mobile sources.\20\
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    \19\ The EPA has approved certain commitments made by CARB in 
the 2016 State Strategy for purposes of attaining the ozone NAAQS in 
the SJV and South Coast ozone nonattainment areas. See, e.g., 84 FR 
3302 (February 12, 2019) and 84 FR 52005 (October 1, 2019).
    \20\ CARB Resolution 17-7, ``2016 State Strategy for the State 
Implementation Plan,'' March 23, 2017, 6-7.
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    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<INF>2.5</INF> 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.\21\
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    \21\ Letter dated May 9, 2019, from Richard W. Corey, Executive 
Officer, CARB, to Mike Stoker, Regional Administrator, EPA Region 
IX, 2.
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    The Valley State SIP Strategy includes an Introduction (Ch. 1), a 
chapter on ``Measures'' (Ch. 2), and a ``Supplemental State Commitment 
from the Proposed State Measures for the Valley'' (Ch. 3). Much of the 
content of the Valley State SIP Strategy is reproduced in Chapter 4 
(``Attainment Strategy for PM<INF>2.5</INF>'') of the 2018 
PM<INF>2.5</INF> Plan.\22\ The Valley State SIP Strategy also includes 
CARB Resolution 18-49, which, among other things, commits CARB to 
achieve specific amounts of NO<INF>X</INF> and PM<INF>2.5</INF> 
emission reductions by specific years, for purposes of attaining the 
PM<INF>2.5</INF> NAAQS in the SJV.\23\
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    \22\ 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<INF>2.5</INF> Plan, Chapter 4.
    \23\ CARB Resolution 18-49, ``San Joaquin Valley Supplement to 
the 2016 State Strategy for the State Implementation Plan,'' October 
25, 2018, 5.
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    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.\24\ 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.\25\ 
Therefore, we reaffirm 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, pursuant to 
CAA section 110(k)(1)(B).
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    \24\ 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.
    \25\ 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).
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C. Rule 4901 Contingency Provision

    Lastly, the 2018 PM<INF>2.5</INF> Plan addresses the contingency 
measure requirements for the 2012 annual PM<INF>2.5</INF> NAAQS by 
reference to, among other things, a District contingency measure, and

[[Page 74313]]

emissions estimates for the year following the attainment year for use 
in evaluating whether the emissions reductions from the contingency 
measure are sufficient.\26\ With respect to the District contingency 
measure, the 2018 PM<INF>2.5</INF> Plan calls for the District to amend 
District Rule 4901 (``Wood Burning Fireplaces and Wood Burning 
Heaters'') to include a provision in the rule with a trigger that would 
activate the requirements of the contingency measure should the EPA 
issue a determination or final rulemaking that the SJV failed to meet a 
regulatory requirement necessitating implementation of a contingency 
measure.
---------------------------------------------------------------------------

    \26\ 2018 PM<INF>2.5</INF> Plan, App. H (revised February 11, 
2020), H-24 to H-26.
---------------------------------------------------------------------------

    In response to the commitment made in the 2018 PM<INF>2.5</INF> 
Plan, in June 2019 the District adopted amendments to Rule 4901, 
including a new provision (codified as section 5.7.3 of the amended 
rule) that is structured to function as a contingency measure. On July 
19, 2019, CARB submitted the amended rule to the EPA for approval.\27\ 
The EPA took final action to approve the amended Rule 4901 (including 
the new section 5.7.3) into the California SIP, but in our approval we 
noted that we were not evaluating the contingency measure in section 
5.7.3 of revised Rule 4901 for compliance with all requirements of the 
CAA and the EPA's implementing regulations that apply to such 
measures.\28\ Rather, we approved the new provision (section 5.7.3) 
into the SIP as part of our approval of the entire amended rule as SIP 
strengthening because the provision strengthens the rule by providing a 
possibility of additional curtailment days and thus potentially 
additional emissions reductions. We indicated that we would evaluate 
whether section 5.7.3, in conjunction with other submitted provisions, 
meets the statutory and regulatory requirements for contingency 
measures in a future action.\29\ In this document, we are evaluating 
District Rule 4901, and in particular section 5.7.3, in the context of 
our action on the contingency measure element in the 2018 
PM<INF>2.5</INF> Plan for the 2012 annual PM<INF>2.5</INF> NAAQS.
---------------------------------------------------------------------------

    \27\ Letter dated July 19, 2019, from Richard W. Corey, 
Executive Officer, CARB, to Mike Stoker, Regional Administrator, EPA 
Region IX.
    \28\ 85 FR 44206 (July 22, 2020) (final approval of District 
Rule 4901); 85 FR 1131, 1132-33 (January 9, 2020) (proposed approval 
of District Rule 4901).
    \29\ The EPA subsequently removed section 5.7.3 of Rule 4901 
from the California SIP. 86 FR 67329 (final rule on 1997 annual 
PM<INF>2.5</INF> NAAQS portion of the SJV PM<INF>2.5</INF> Plan, 
including final disapproval of the contingency measures element for 
those NAAQS).
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III. Clean Air Act Requirements for PM2.5 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: \30\
---------------------------------------------------------------------------

    \30\ 81 FR 58010, 58074-58075 (August 24, 2016).
---------------------------------------------------------------------------

    (1) A comprehensive, accurate, current inventory of actual 
emissions from all sources of PM<INF>2.5</INF> and PM<INF>2.5</INF> 
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<INF>2.5</INF> and all PM<INF>2.5</INF> precursors 
shall be implemented no later than four years after the area is 
reclassified (CAA section 189(b)(1)(B)), unless the state elects to 
make an optional precursor demonstration that the EPA approves 
authorizing the state not to regulate one or more of these pollutants;
    (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, 2025, for the SJV for the 2012 
annual PM<INF>2.5</INF> NAAQS) (CAA sections 188(c)(2) and 
189(b)(1)(A)(i));
    (4) Plan provisions that require reasonable further progress (RFP) 
(CAA section 172(c)(2));
    (5) Quantitative milestones which are to be achieved every three 
years until the area is redesignated attainment and which demonstrate 
RFP toward attainment by the applicable date (CAA section 189(c));
    (6) Provisions to assure that control requirements applicable to 
major stationary sources of PM<INF>2.5</INF> also apply to major 
stationary sources of PM<INF>2.5</INF> precursors, except where the 
state demonstrates to the EPA's satisfaction that such sources do not 
contribute significantly to PM<INF>2.5</INF> levels that exceed the 
standard in the area (CAA section 189(e));
    (7) Contingency measures to be implemented if the area fails to 
meet RFP or to attain by the applicable attainment date (CAA section 
172(c)(9)); and
    (8) A revision to the nonattainment new source review (NSR) program 
to lower the applicable ``major stationary source'' \31\ thresholds 
from 100 tons per year (tpy) to 70 tpy (CAA section 189(b)(3)).
---------------------------------------------------------------------------

    \31\ 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<INF>2.5</INF>. CAA section 189(b)(3) and 40 CFR 
51.165(a)(1)(iv)(A)(1)(vii) and (viii) (defining ``major stationary 
source'' in serious PM<INF>2.5</INF> nonattainment areas).
---------------------------------------------------------------------------

    A state's Serious area plan 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 state's Serious area plan must meet the 
general requirements applicable to all SIP submissions under section 
110 of the CAA, including the requirement to provide necessary 
assurances that the implementing agencies have adequate personnel, 
funding, and authority under section 110(a)(2)(E); and the requirements 
concerning enforcement provisions in section 110(a)(2)(C).
    The EPA provided its preliminary views on the CAA's requirements 
for particulate matter plans under part D, title I of the Act in the 
following guidance documents: (1) ``State Implementation Plans; General 
Preamble for the Implementation of Title I of the Clean Air Act 
Amendments of 1990'' (``General Preamble''); \32\ (2) ``State 
Implementation Plans; General Preamble for the Implementation of Title 
I of the Clean Air Act Amendments of 1990; Supplemental'' (``General 
Preamble Supplement''); \33\ 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'').\34\ More recently, in an August 24, 
2016 final rule entitled, ``Fine Particulate Matter National Ambient 
Air Quality Standards: State Implementation Plan Requirements'' 
(``PM<INF>2.5</INF> 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<INF>2.5</INF> standards.\35\ We discuss these 
regulatory requirements and interpretations of the Act as appropriate 
in our evaluation of the State's submissions below.
---------------------------------------------------------------------------

    \32\ 57 FR 13498 (April 16, 1992).
    \33\ 57 FR 18070 (April 28, 1992).
    \34\ 59 FR 41998 (August 16, 1994).
    \35\ 81 FR 58010.

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[[Page 74314]]

IV. Review of the San Joaquin Valley PM2.5 Serious Area Plan

A. Emissions Inventory

1. Requirements for Emissions Inventories
    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<INF>2.5</INF> nonattainment areas, including Serious area 
requirements, in the PM<INF>2.5</INF> SIP Requirements Rule and 
codified these requirements in 40 CFR 51.1008.\36\ The EPA has also 
issued guidance concerning emissions inventories for PM<INF>2.5</INF> 
nonattainment areas.\37\
---------------------------------------------------------------------------

    \36\ Id. at 58078-58079.
    \37\ EPA, ``Emissions Inventory Guidance for Implementation of 
Ozone and Particulate Matter National Ambient Air Quality Standards 
(NAAQS) and Regional Haze Regulations,'' May 2017 (``Emissions 
Inventory Guidance''), available at <a href="https://www.epa.gov/air-emissions-inventories/air-emissions-inventory-guidance-implementation-ozone-and-particulate">https://www.epa.gov/air-emissions-inventories/air-emissions-inventory-guidance-implementation-ozone-and-particulate</a>.
---------------------------------------------------------------------------

    The base year emissions inventory should provide a state's best 
estimate of actual emissions from all sources of the relevant 
pollutants in the area, i.e., all emissions that contribute to the 
formation of a particular NAAQS pollutant. For the PM<INF>2.5</INF> 
NAAQS, the base year inventory must include direct PM<INF>2.5</INF> 
emissions, separately reported filterable and condensable 
PM<INF>2.5</INF> emissions,\38\ and emissions of all chemical 
precursors to the formation of secondary PM<INF>2.5</INF>: Nitrogen 
oxides (NO<INF>X</INF>), sulfur dioxide (SO<INF>2</INF>), volatile 
organic compounds (VOC), and ammonia (NH<INF>3</INF>).\39\ In addition, 
the emissions inventory base year for a Serious PM<INF>2.5</INF> 
nonattainment area must be one of the three years for which monitored 
data were used to reclassify the area to Serious, or another 
technically appropriate year justified by the state in its Serious area 
plan submission.\40\
---------------------------------------------------------------------------

    \38\ The Emissions Inventory Guidance identifies the types of 
sources for which the EPA expects states to provide condensable PM 
emission inventories. Emissions Inventory Guidance, section 4.2.1 
(``Condensable PM Emissions''), 63-65.
    \39\ 40 CFR 51.1008.
    \40\ 40 CFR 51.1008(b)(1).
---------------------------------------------------------------------------

    A state's SIP submission must include documentation explaining how 
it calculated emissions data for the inventory. In estimating mobile 
source emissions, a state should use the latest emissions models and 
planning assumptions available at the time it developed the submission. 
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<INF>2.5</INF> Plan was 
EMFAC2014.\41\ Following CARB's submission of the Plan, the EPA 
approved EMFAC2017, the latest revision to this motor vehicle emissions 
model for SIP purposes.\42\ 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.\43\
---------------------------------------------------------------------------

    \41\ 80 FR 77337 (December 14, 2015). EMFAC is short for 
EMission FACtor. The EPA announced the availability of the EMFAC2014 
motor vehicle emissions model, effective on the date of publication 
in the Federal Register, for use in state implementation plan 
development and transportation conformity in California. We note 
that CARB's use of EMFAC2014 in developing the emission inventories 
for the Serious area plan for the 2012 annual PM<INF>2.5</INF> NAAQS 
preceded the requirement to adopt and submit such Serious area plan.
    \42\ 84 FR 41717 (August 15, 2019).
    \43\ The EPA released an update to AP-42 in January 2011 that 
revised the equation for estimating paved road dust emissions based 
on an updated data regression that included new emission tests 
results. 76 FR 6328 (February 4, 2011). CARB used the revised 2011 
AP-42 methodology in developing on-road mobile source emissions. 
``Miscellaneous Process Methodology 7.9 Entrained Road Travel, Paved 
Road Dust,'' CARB, November 2016.
---------------------------------------------------------------------------

    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.\44\ These future emissions projections are 
necessary components of the attainment demonstration required under CAA 
section 189(b)(1) and the demonstration of RFP required under section 
172(c)(2).\45\ Emissions projections for future years (which are 
referred to in the Plan as ``forecasted inventories'') should account 
for, among other things, the ongoing effects of economic growth and 
adopted emissions control requirements. The state's SIP submission 
should include documentation to explain how it calculated the emissions 
projections. Where a state chooses to allow new major stationary 
sources or major modifications to use emission reductions credits 
(ERCs) that were generated through shutdown or curtailed emissions 
units occuring before the base year of an attainment plan, the 
projected emissions inventory used to develop the attainment 
demonstration must explicitly include the emissions from such 
previously shutdown or curtailed emissions units.\46\
---------------------------------------------------------------------------

    \44\ 40 CFR 51.1008 and 51.1012. Also, see Emissions Inventory 
Guidance, section 3 (``SIP Inventory Requirements and 
Recommendations'').
    \45\ 40 CFR 51.1004, 51.1008, 51.1011, and 51.1012.
    \46\ 40 CFR 51.165(a)(3)(ii)(C)(1).
---------------------------------------------------------------------------

Summary of State's Submission
    The State included summaries of the planning emissions inventories 
for direct PM<INF>2.5</INF> and all PM<INF>2.5</INF> precursors 
(NO<INF>X</INF>, SO<INF>X</INF>,\47\ VOC,\48\ and ammonia) and the 
documentation for the inventories for the SJV PM<INF>2.5</INF> 
nonattainment area in Appendix B (``Emissions Inventory'') and Appendix 
I (``New Source Review and Emission Reduction Credits'') of the 2018 
PM<INF>2.5</INF> Plan. In addition, Appendix J (``Modeling Emission 
Inventory'') contains inventory documentation specific to the air 
quality modeling inventories. These portions of the 2018 
PM<INF>2.5</INF> Plan contain annual average daily emission inventories 
for 2013 through 2028 projected from the 2012 actual emissions 
inventory,\49\ including the 2013 base year, the 2019 and 2022 RFP 
milestone years, the 2025 Serious area attainment year, and a 2028 
post-attainment RFP year. The State used both the annual average and 
the winter average daily inventories to evaluate emission sources for 
the 2012 annual PM<INF>2.5</INF> NAAQS in the 2018 PM<INF>2.5</INF> 
Plan.\50\
---------------------------------------------------------------------------

    \47\ The SJV PM<INF>2.5</INF> Plan generally uses ``sulfur 
oxides'' or ``SO<INF>X</INF>'' in reference to SO<INF>2</INF> as a 
precursor to the formation of PM<INF>2.5</INF>. We use 
SO<INF>X</INF> and SO<INF>2</INF> interchangeably throughout this 
notice.
    \48\ The SJV PM<INF>2.5</INF> Plan generally uses ``reactive 
organic gasses'' or ``ROG'' in reference to VOC as a precursor to 
the formation of PM<INF>2.5</INF>. We use ROG and VOC 
interchangeably throughout this notice.
    \49\ 2018 PM<INF>2.5</INF> Plan, App. B, B-18.
    \50\ Id. at App. B, B-19. The base year inventory is from 
CEIDARS and future year inventories were estimated using CEPAM, 
version 1.05.
---------------------------------------------------------------------------

    The State selected 2013 for the base year emission inventory, 
building on the 2012 actual emissions inventory and considering 
available air quality data, trends, and field studies.\51\ 
Specifically, the State worked with local air districts and selected 
2012 for the actual emissions inventory as it aligned with the 2012 
data collection year of the Multiple Air Toxics Exposure Study IV 
(MATES IV) \52\ of the South Coast Air Quality Management District 
(SCAQMD) and to maintain consistency across various California air 
quality plans.\53\ The State then projected the

[[Page 74315]]

2013 base year emissions inventory (also referred to as the planning 
emissions inventory), presented in Appendix B of the Plan, from that 
2012 actual emission inventory. Regarding the modeling emissions 
inventory, developed from the base year emissions inventory, the State 
conducted its base case modeling using 2013 for several reasons: 
Analysis of air quality trends, adjusted for meteorology, that 
indicated 2013 as a year conducive to ozone and PM<INF>2.5</INF> 
formation; availability of research-grade measurements of two 
significant pollution episodes in the DISCOVER-AQ field study of 
January to February 2013; and the relatively high design values for 
2013, making it a conservative choice for attainment modeling.\54\
---------------------------------------------------------------------------

    \51\ Id. at App. L, 11-12.
    \52\ Additional information on the MATES IV study performed in 
2012 is available at: <a href="https://www.aqmd.gov/home/air-quality/air-quality-studies/health-studies/mates-iv">https://www.aqmd.gov/home/air-quality/air-quality-studies/health-studies/mates-iv</a>. SCAQMD performed the 
subsequent MATES V study in 2018 and issued the MATES V final report 
in August 2021. See <a href="https://www.aqmd.gov/home/air-quality/air-quality-studies/health-studies/mates-v">https://www.aqmd.gov/home/air-quality/air-quality-studies/health-studies/mates-v</a>, and ``MATES V, Multiple Air 
Toxics Exposure Study in the South Coast AQMD, Final Report,'' 
SCAQMD, August 2021.
    \53\ 2018 PM<INF>2.5</INF> Plan, App. B, B-18.
    \54\ Id. at App. L, 12. The State presents further information 
in the ``APPENDIX: San Joaquin Valley PM<INF>2.5</INF> SIP (2018)'' 
of Appendix L, and highlights that 2013 was one of the worst years 
in the decade preceding 2018 for PM<INF>2.5</INF> pollution in the 
SJV, underscoring its use as a conservative base year for modeling 
attainment of the 2012 annual PM<INF>2.5</INF> NAAQS. 2018 
PM<INF>2.5</INF> Plan, Ch. 7, 7-6.
---------------------------------------------------------------------------

    In addition, simultaneously with submission of the 2018 
PM<INF>2.5</INF> Plan, the State submitted the Moderate area plan for 
the SJV for the 2012 annual PM<INF>2.5</INF> NAAQS, adopted by the 
District in 2016, that similarly used 2013 for the base year emissions 
inventory (``2016 PM<INF>2.5</INF> Plan''). In that plan, the State 
included a modeling demonstration that it would be impracticable for 
the SJV to attain the 2012 annual PM<INF>2.5</INF> NAAQS by the 
outermost Moderate area attainment date of December 31, 2021.\55\ The 
modeling demonstration used three overlapping design value periods 
covering 2010-2014 and the 2013 base year emissions inventory to model 
the ambient air quality in 2021.
---------------------------------------------------------------------------

    \55\ 2016 PM<INF>2.5</INF> Plan, Ch. 2, section 2.3 (``Summary 
of Modeling Results'') and App. A (``Air Quality Modeling''). The 
EPA has summarized the State's impracticability demonstration in 
greater detail in our proposed rule on the 2016 PM<INF>2.5</INF> 
Plan. 86 FR 49100, 49113 (September 1, 2021).
---------------------------------------------------------------------------

    The State developed base year inventories in the 2018 
PM<INF>2.5</INF> Plan for stationary sources using actual emissions 
reports made by facility operators. The State developed the base year 
emissions inventories for area sources using the most recent models and 
methodologies available at the time the State was developing the 2018 
PM<INF>2.5</INF> Plan.\56\ The 2018 PM<INF>2.5</INF> Plan includes 
background, methodology, and inventories of condensable and filterable 
PM<INF>2.5</INF> emissions from stationary point and non-point 
combustion sources that are expected to generate condensable 
PM<INF>2.5</INF>.\57\ It provides filterable and condensable emissions 
estimates, expressed as annual PM<INF>2.5</INF> emissions (tons per 
year), for all of the identified source categories for the years 
relevant for the 2012 annual PM<INF>2.5</INF> NAAQS Serious area plan 
requirements, including the 2013 base year, the 2019 and 2022 RFP 
years, the 2025 Serious area attainment year, and a 2028 post-
attainment RFP year.
---------------------------------------------------------------------------

    \56\ 2018 PM<INF>2.5</INF> Plan, App. B, section B.2 
(``Emissions Inventory Summary and Methodology'').
    \57\ Id. at App. B, B-42 to B-44.
---------------------------------------------------------------------------

    CARB used EMFAC2014, which was the EPA-approved model at the time 
CARB developed and submitted the inventories, to estimate on-road motor 
vehicle emissions based on transportation activity data from the 2014 
Regional Transportation Plans adopted by the transportation planning 
agencies in the SJV.\58\ Re-entrained paved road dust emissions were 
calculated using a CARB methodology consistent with the EPA's AP-42 
road dust methodology.\59\ CARB also provided emissions inventories for 
non-road equipment, including aircraft, trains, recreational boats, 
construction equipment, and farming equipment, among others. CARB uses 
a suite of category-specific models to estimate non-road emissions for 
many categories and, where a new model was not available, used the 
OFFROAD2007 model.\60\
---------------------------------------------------------------------------

    \58\ Id. at App. B, B-37. We note that the vehicle miles 
traveled data used in the 2018 PM<INF>2.5</INF> Plan's emissions 
inventory is from the final 2017 Federal Transportation Improvement 
Program from each of the SJV's eight metropolitan planning 
organizations.
    \59\ Id. at App. B, B-28.
    \60\ Id. at App. B, B-38 through B-40. 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.
---------------------------------------------------------------------------

    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.\61\ 
In the 2018 PM<INF>2.5</INF> Plan, the District provides for use of 
pre-base year ERCs as offsets by accounting for such ERCs in the 
projected emissions inventory for the 2025 attainment year.\62\ The 
Plan identifies growth factors, control factors, and estimated offset 
use between 2013 and 2025, for direct PM<INF>2.5</INF>, NO<INF>X</INF>, 
SO<INF>X</INF>, and VOC emissions by source category and lists all pre-
base year ERCs issued by the District for PM<INF>10</INF>,\63\ 
NO<INF>X</INF>, SO<INF>X</INF>, and VOC emissions by facility.\64\
---------------------------------------------------------------------------

    \61\ Id. at App. B, B-19.
    \62\ Id. at App. I, I-1 through I-5.
    \63\ Particulate matter with a diameter of 10 microns or less.
    \64\ 2018 PM<INF>2.5</INF> Plan, App. I, tables I-1 through I-5.
---------------------------------------------------------------------------

    Table 1 provides a summary of the 2018 PM<INF>2.5</INF> Plan's 
winter (24-hour) average inventories in tpd of direct PM<INF>2.5</INF> 
and PM<INF>2.5</INF> precursor emissions for the 2013 base year. Table 
2 provides a summary of the 2018 PM<INF>2.5</INF> Plan's annual average 
inventories of direct PM<INF>2.5</INF> and PM<INF>2.5</INF> precursor 
emissions for the 2013 base year. For purposes of this proposal, these 
annual average inventories provide bases primarily for our evaluation 
of the precursor demonstration, control measure analysis, attainment 
demonstration, RFP demonstration, and motor vehicle emissions budgets 
(``budgets'') in the 2018 PM<INF>2.5</INF> Plan with respect to the 
Serious area attainment plan requirements for the 2012 annual 
PM<INF>2.5</INF> NAAQS.

  Table 1--San Joaquin Valley Winter Average Emissions Inventory for Direct PM2.5 and PM2.5 Precursors for the
                                                 2013 Base Year
                                                      [tpd]
----------------------------------------------------------------------------------------------------------------
                                   Direct PM2.5
            Category                                    NOX             SOX             VOC           Ammonia
----------------------------------------------------------------------------------------------------------------
Stationary Sources..............             8.5            35.0             6.9            86.6            13.9
Area Sources....................            41.4            11.5             0.5           156.8           291.5
On-Road Mobile Sources..........             6.4           188.7             0.6            51.1             4.4
Non-Road Mobile Sources.........             4.4            65.3             0.3            27.4             0.0
                                 -------------------------------------------------------------------------------
    Totals \a\..................            60.8           300.5             8.4           321.9           309.8
----------------------------------------------------------------------------------------------------------------
Source: 2018 PM2.5 Plan, Appendix B, tables B-1 through B-5.

[[Page 74316]]

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


  Table 2--San Joaquin Valley Annual Average Emissions Inventory for Direct PM2.5 and PM2.5 Precursors for the
                                                 2013 Base Year
                                                      [tpd]
----------------------------------------------------------------------------------------------------------------
                                   Direct PM2.5
            Category                                    NOX             SOX             VOC           Ammonia
----------------------------------------------------------------------------------------------------------------
Stationary Sources..............             8.8            38.6             7.2            87.1            13.9
Area Sources....................            41.5             8.1             0.3           153.4           310.9
On-Road Mobile Sources..........             6.4           183.1             0.6            49.8             4.4
Non-Road Mobile Sources.........             5.8            87.4             0.3            33.8             0.0
                                 -------------------------------------------------------------------------------
    Totals \a\..................            62.5           317.2             8.5           324.1           329.2
----------------------------------------------------------------------------------------------------------------
Source: 2018 PM2.5 Plan, Appendix B, tables B-1 through B-5.
\a\ Totals reflect disaggregated emissions and may not add exactly as shown here due to rounding.

EPA Evaluation and Proposed Action
    The inventories in the 2018 PM<INF>2.5</INF> Plan include the 
latest version of California's mobile source emissions model, 
EMFAC2014, that the EPA had approved at the time the State made the SIP 
submissions, and the EPA's most recent AP-42 methodology for paved road 
dust. The inventories comprehensively address all source categories in 
the SJV PM<INF>2.5</INF> nonattainment area and are consistent with the 
EPA's inventory guidance.
    In accordance with 40 CFR 51.1008(b)(1), the EPA has evaluated the 
State's justification for using 2013 for the base year emissions 
inventory as a technically appropriate inventory year for the 2012 
annual PM<INF>2.5</INF> NAAQS Serious area plan for the SJV. In 
particular, the State describes the technical bases for the selection 
of 2013 for the modeling emissions inventory, explaining that 2013 was 
conducive to PM<INF>2.5</INF> formation in the SJV; the important 
DISCOVER-AQ field study measured two significant pollution episodes in 
the SJV in January to February 2013; and the 2013 design values (across 
monitoring sites) were relatively high in comparison to other recent 
years,\65\ making it a conservative choice for future air quality 
projections for RFP and attainment of the 2012 annual PM<INF>2.5</INF> 
NAAQS. We agree that these points make 2013 both a conservative year 
for modeling future air quality and one that aligns the comprehensive, 
accurate, and recent emissions inventory at the time the State 
developed and submitted the 2018 PM<INF>2.5</INF> Plan with empirical 
data from the DISCOVER-AQ field study.
---------------------------------------------------------------------------

    \65\ EPA design value workbook dated May 24, 2021, 
``pm25_designvalues_2018_2020_final_05_24_21.xlsx,'' worksheets 
``Table3a.''
---------------------------------------------------------------------------

    The EPA's approval of the State's demonstration that it was 
impracticable to attain the 2012 annual PM<INF>2.5</INF> NAAQS by 2021 
and reclassification of the SJV to Serious for the 2012 annual 
PM<INF>2.5</INF> NAAQS was based foremost on the State's modeled 
demonstration.\66\ While we also considered the 2018-2020 design values 
(across monitoring sites) as part of our evaluation, such ambient air 
quality data was not available in 2017-2018 when CARB and the District 
were developing the 2018 PM<INF>2.5</INF> Plan.
---------------------------------------------------------------------------

    \66\ 86 FR 67343, 67345. See also, 86 FR 49100, 49117-49118 
(proposed rule on State's Moderate area plan).
---------------------------------------------------------------------------

    Therefore, the EPA proposes to find the State's justification for 
selecting 2013 for the base year emissions inventory to be technically 
appropriate, consistent with 40 CFR 51.1008(b)(1). Furthermore, the 
2013 base year represents actual annual average emissions of all 
sources within the nonattainment area. Direct PM<INF>2.5</INF> and 
PM<INF>2.5</INF> precursors are included in the inventories, and 
filterable and condensable direct PM<INF>2.5</INF> emissions are 
identified separately.
    With respect to future year baseline projections, we have reviewed 
the growth and control factors estimated by the State and propose to 
find them acceptable and thus conclude that the future baseline 
emissions projections in the 2018 PM<INF>2.5</INF> Plan reflect 
appropriate calculation methods and the latest planning assumptions at 
the time the State and District were developing the Plan and its 
emissions inventory. Also, as a general matter, the EPA will approve a 
SIP submission that takes emissions reduction credit for a control 
measure only where the EPA has approved the measure as part of the SIP. 
Thus, for example, to take credit for the emissions reductions from 
newly adopted or amended District rules for stationary and area 
sources, the related rules must be approved by the EPA into the SIP.
    In our rulemaking on the State's attainment plan for the 2006 24-
hour PM<INF>2.5</INF> NAAQS in the SJV, we reviewed the baseline 
measures identified as 2018 PM<INF>2.5</INF> Plan baseline controls to 
ensure that the measures that are relied upon in the plan are submitted 
and approved as part of the California SIP.\67\ We reaffirm that the 
stationary and area source baseline measures in the 2018 
PM<INF>2.5</INF> Plan are approved into the SIP and support the 
emissions reductions for future years in the SJV, with two exceptions 
discussed in section IV.F.3.a of the proposed rule that would not 
materially affect the attainment demonstration in the Plan. With 
respect to mobile sources, the EPA has acted in recent years to approve 
CARB mobile source regulations into the state-wide portion of the 
California SIP.\68\ We therefore propose to find that the future year 
baseline projections in the 2018 PM<INF>2.5</INF> Plan are properly 
supported by SIP-approved stationary, area, and mobile source 
measures.\69\
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    \67\ EPA Region IX, ``Technical Support Document, General 
Evaluation, San Joaquin Valley PM<INF>2.5</INF> Plan for the 2006 
PM<INF>2.5</INF> NAAQS,'' February 2020 (``EPA's General Evaluation 
TSD''). Table V-A of EPA's General Evaluation TSD shows District 
rules with post-2013 compliance dates that are reflected in the 
future year baseline inventories of the 2018 PM<INF>2.5</INF> Plan, 
along with information on the EPA's approval of these rules.
    \68\ See, e.g., 81 FR 39424 (June 16, 2016), 82 FR 14447 (March 
21, 2017), and 83 FR 23232 (May 18, 2018).
    \69\ The baseline emissions projections in the 2018 
PM<INF>2.5</INF> Plan assume implementation of CARB's zero emissions 
vehicle (ZEV) sales mandate and greenhouse gas (GHG) standards, 
based on the EMFAC2014 model that was the current EPA-approved model 
available at the time of the SIP's development and the assumptions 
that were available at that time. On September 27, 2019, the U.S. 
Department of Transportation and the EPA (the Agencies) issued the 
joint action known as the ``Safer Affordable Fuel-Efficient (SAFE) 
Vehicles Rule Part One: One National Program'' (``SAFE I'') that, 
among other things, withdrew the EPA's 2013 waiver of preemption of 
CARB's ZEV sales mandate and vehicle GHG standards. 84 FR 51310 
(September 27, 2019). See also proposed SAFE rule at 83 FR 42986 
(August 24, 2018). On April 30, 2020 (85 FR 24174), the Agencies 
issued a notice of final rulemaking for the ``The Safer Affordable 
Fuel-Efficient (SAFE) Vehicles Rule for Model Years 2021-2026 
Passenger Cars and Light Trucks'' (``SAFE II''), establishing the 
federal fuel economy and GHG vehicle emissions standards based on 
the August 2018 SAFE proposal. The effect of both SAFE final rules 
(SAFE I and SAFE II) on the on-road vehicle mix in the SJV 
nonattainment area and on the resulting vehicular emissions is 
expected to be minimal during the timeframe addressed in this SIP 
revision. Therefore, we anticipate the SAFE final rules would not 
materially change the demonstration of attainment of the 2012 annual 
PM<INF>2.5</INF> NAAQS in the SJV by the Serious area attainment 
date of December 31, 2025.

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[[Page 74317]]

    For these reasons, we are proposing to approve the 2013 base year 
emissions inventory in the 2018 PM<INF>2.5</INF> Plan as meeting the 
requirements of CAA section 172(c)(3) and 40 CFR 51.1008. We are also 
proposing to find that the future year baseline inventories in the 2018 
PM<INF>2.5</INF> Plan satisfy the requirements of 40 CFR 51.1008(b)(2) 
and 51.1012(a)(2) and provide an adequate basis for the control 
measure, attainment, and RFP demonstrations for the 2012 annual 
PM<INF>2.5</INF> NAAQS in the 2018 PM<INF>2.5</INF> Plan.

B. PM2.5 Precursors

Requirements for Control of PM<INF>2.5</INF> Precursors
    The provisions of subpart 4 of part D, title I of the CAA do not 
define the term ``precursor'' for purposes of PM<INF>2.5</INF>, nor do 
they explicitly require the control of any specifically identified PM 
precursor. The statutory definition of ``air pollutant'' in CAA section 
302(g), however, provides that the term ``includes any precursors to 
the formation of any air pollutant, to the extent the Administrator has 
identified such precursor or precursors for the particular purpose for 
which the term `air pollutant' is used.'' The EPA has identified 
NO<INF>X</INF>, SO<INF>2</INF>, VOC, and ammonia as precursors to the 
formation of PM<INF>2.5</INF>.\70\ Accordingly, the attainment plan 
requirements of subpart 4 apply to emissions of all four precursor 
pollutants and direct PM<INF>2.5</INF> from all types of stationary, 
area, and mobile sources, except as otherwise provided in the Act 
(e.g., in CAA section 189(e)).
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    \70\ 81 FR 58010, 58018.
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    Section 189(e) of the Act requires that the control requirements 
for major stationary sources of direct PM<INF>10</INF> (which includes 
PM<INF>2.5</INF>) also apply to major stationary sources of 
PM<INF>10</INF> precursors, except where the Administrator determines 
that such sources do not contribute significantly to PM<INF>10</INF> 
levels that exceed the standard in the area. Section 189(e) contains 
the only express exception to the control requirements under subpart 4 
(e.g., requirements for reasonably available control measures (RACM), 
reasonably available control technology (RACT), BACM, BACT, most 
stringent measures (MSM), and nonattainment 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<INF>2.5</INF> 
precursors from other source categories in a given nonattainment area 
is not necessary. For example, under the EPA's longstanding 
interpretation of the control requirements that apply to stationary and 
mobile sources of PM<INF>10</INF> precursors in the nonattainment area 
under CAA section 172(c)(1) and subpart 4,\71\ a state may demonstrate 
in a SIP submission that control of a certain precursor pollutant is 
not necessary in light of its insignificant contribution to ambient 
PM<INF>10</INF> levels in the nonattainment area.\72\
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    \71\ General Preamble, 13539-13542.
    \72\ Courts have upheld this approach to the requirements of 
subpart 4 for PM<INF>10</INF>. See, e.g., Assoc. of Irritated 
Residents v. EPA, et al., 423 F.3d 989 (9th Cir. 2005).
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    Under the PM<INF>2.5</INF> 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<INF>2.5</INF> levels that exceed 
the standard in the area.\73\ If the EPA determines that the 
contribution of the precursor to PM<INF>2.5</INF> levels in the area is 
not significant and approves the demonstration, the state is not 
required to control emissions of the relevant precursor from existing 
sources in the attainment plan.\74\
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    \73\ 40 CFR 51.1006(a)(1).
    \74\ Id.
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    In addition, in May 2019, the EPA issued the ``PM<INF>2.5</INF> 
Precursor Demonstration Guidance'' (``PM<INF>2.5</INF> Precursor 
Guidance''), which provides recommendations to states for analyzing 
nonattainment area PM<INF>2.5</INF> emissions and developing such 
optional precursor demonstrations, consistent with the PM<INF>2.5</INF> 
SIP Requirements Rule.\75\ The EPA developed recommended contribution 
thresholds to help assess whether a precursor significantly contributes 
to PM<INF>2.5</INF> levels above the NAAQS. The thresholds are based on 
the size of PM<INF>2.5</INF> differences that are distinguishable 
statistically in monitored data. If the chemical component of 
PM<INF>2.5</INF> ambient concentrations corresponding to emissions of a 
precursor (e.g., the concentration of sulfate, which corresponds to 
SO<INF>2</INF> emissions) is below the threshold, that is evidence that 
the precursor does not significantly contribute. If the precursor fails 
this concentration-based test, the State can use a sensitivity-based 
test, in which the modeled sensitivity or response of ambient 
PM<INF>2.5</INF> concentrations to changes in emissions of the 
precursor is estimated and then compared to the threshold. In addition 
to comparing the concentration or modeled response to the threshold, 
the State can consider other information in assessing whether the 
precursor significantly contributes. The EPA's recommended annual 
average contribution threshold for the annual PM<INF>2.5</INF> NAAQS is 
0.2 [mu]g/m\3\.\76\
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    \75\ ``PM<INF>2.5</INF> Precursor Demonstration Guidance,'' EPA-
454/R-19-004, May 2019, including Memo dated May 30, 2019, from 
Scott Mathias, Acting Director, Air Quality Policy Division and 
Richard Wayland, Director, Air Quality Assessment Division, Office 
of Air Quality Planning and Standards (OAQPS), EPA to Regional Air 
Division Directors, Regions 1-10, EPA. The PM<INF>2.5</INF> 
Precursor Guidance builds upon the draft version of the guidance, 
released on November 17, 2016 (``Draft PM<INF>2.5</INF> Precursor 
Guidance''), which CARB referenced in developing its precursor 
demonstration in the SJV PM<INF>2.5</INF> Plan. ``PM<INF>2.5</INF> 
Precursor Demonstration Guidance, Draft for Public Review and 
Comments,'' EPA-454/P-16-001, November 17, 2016, including Memo 
dated November 17, 2016, from Stephen D. Page, Director, OAQPS, EPA 
to Regional Air Division Directors, Regions 1-10, EPA.
    \76\ PM<INF>2.5</INF> Precursor Guidance, 17.
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    We are evaluating the 2018 PM<INF>2.5</INF> Plan with respect to 
the Serious area attainment plan requirements in accordance with the 
presumption embodied within subpart 4 that the State must address all 
PM<INF>2.5</INF> precursors in its 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<INF>2.5</INF> levels that exceed the PM<INF>2.5</INF> NAAQS 
in the nonattainment area. In reviewing any determination by the State 
to exclude a PM<INF>2.5</INF> precursor from the required evaluation of 
potential control measures, we consider both the magnitude of the 
precursor's contribution to ambient PM<INF>2.5</INF> concentrations in 
the nonattainment area and the sensitivity of ambient PM<INF>2.5</INF> 
concentrations in the area to reductions in emissions of that precursor 
in accordance with the PM<INF>2.5</INF> Precursor Guidance.
Summary of State's Submission
    The State's precursor demonstration and conclusions are found in 
Chapter 7 (``Demonstration of Federal Requirements for 2012 
PM<INF>2.5</INF> Standard'') and Appendix G (``Precursor 
Demonstration'') of the 2018 PM<INF>2.5</INF> Plan. CARB also provides 
clarifying information on its precursor assessment, including an 
Attachment A to its letter transmitting the 2018 PM<INF>2.5</INF> Plan 
to the

[[Page 74318]]

EPA \77\ and further clarifications in five email transmittals.\78\
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    \77\ Letter dated May 9, 2019, from Richard W. Corey, Executive 
Officer, CARB, to Michael Stoker, Regional Administrator, EPA Region 
IX, Attachment A (``Clarifying information for the San Joaquin 
Valley 2018 Plan regarding model sensitivity related to ammonia and 
ammonia controls'').
    \78\ Email dated June 20, 2019, ``RE: SJV model disbenefit from 
SO<INF>X</INF> reduction,'' from Jeremy Avise, CARB, to Scott 
Bohning, EPA Region IX, with attachment (``CARB's June 2019 
Precursor Clarification''); email dated September 19, 2019, ``FW: 
SJV species responses,'' from Jeremy Avise, CARB, to Scott Bohning, 
EPA Region IX, with attachments (``CARB's September 2019 Precursor 
Clarification''); email dated October 18, 2019, from Laura Carr, 
CARB, to Scott Bohning, Jeanhee Hong, and Rory Mays, EPA Region IX, 
with attachment ``Clarifying Information on Ammonia'' (``CARB's 
October 2019 Precursor Clarification''); 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'').
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    The State estimates that anthropogenic emissions of NO<INF>X</INF>, 
ammonia, SO<INF>X</INF>, and VOC will decrease by 64 percent (%), 1%, 
6%, and 9%, respectively, between 2013 and 2025.\79\ The 2018 
PM<INF>2.5</INF> Plan provides both concentration-based and 
sensitivity-based analyses of precursor contributions to ambient 
PM<INF>2.5</INF> concentrations in the SJV. Based on these analyses, 
the State concludes that emissions of NO<INF>X</INF> (as well as direct 
PM<INF>2.5</INF>) contribute significantly to ambient PM<INF>2.5</INF> 
levels that exceed the PM<INF>2.5</INF> NAAQS in the SJV but ammonia, 
SO<INF>X</INF>, and VOC do not contribute significantly to such 
exceedances.
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    \79\ 2018 PM<INF>2.5</INF> Plan, Ch. 7, 7-5 and Table 7-2. We 
also note that a copy of the contents of the 2018 PM<INF>2.5</INF> 
Plan, App. G appears in the CARB Staff Report, App. C4 (``Precursor 
Demonstrations for Ammonia, SO<INF>X</INF>, and ROG'').
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    We summarize the State's analyses and conclusions for ammonia, 
SO<INF>X</INF>, and VOC in the following paragraphs. For a more 
detailed summary of the precursor demonstration in the Plan, please 
refer to two EPA technical support documents (TSDs): The first covers 
all the precursors and the second one specifically addresses ammonia. 
The first TSD is the EPA's ``Technical Support Document, EPA Evaluation 
of PM<INF>2.5</INF> Precursor Demonstration, San Joaquin Valley 
PM<INF>2.5</INF> Plan for the 2006 PM<INF>2.5</INF> NAAQS,'' February 
2020 (``EPA's PM<INF>2.5</INF> Precursor TSD''), which provides the 
EPA's summary of the State's precursor analyses for all four 
PM<INF>2.5</INF> precursors. Most of our analysis in the EPA's 
PM<INF>2.5</INF> Precursor TSD is applicable to the portion of the Plan 
pertaining to the Serious area plan for the 2012 annual 
PM<INF>2.5</INF> NAAQS. For example, the State's precursor 
demonstration used 2015 annual average concentration data for its 
concentration-based analysis, examined both 24-hour and annual average 
sensitivities of ambient PM<INF>2.5</INF> concentrations to reductions 
in each precursor in 2013, 2020, and 2024, and presented information on 
research studies and emission trends that are relevant for assessing 
the sensitivity of both 24-hour average and annual average ambient 
PM<INF>2.5</INF> concentrations to emission reductions of each 
PM<INF>2.5</INF> precursor. Our evaluation of such factors, as 
described in the EPA's PM<INF>2.5</INF> Precursor TSD, is similarly 
applicable for the 2012 annual PM<INF>2.5</INF> NAAQS.
    With respect to ammonia emission reductions, the EPA's 
PM<INF>2.5</INF> Precursor TSD summarizes the State's analysis of 24-
hour average sensitivity of ambient PM<INF>2.5</INF> concentrations 
across monitoring sites and years (see Table 2 of the EPA's 
PM<INF>2.5</INF> Precursor TSD). The EPA's second TSD, ``Technical 
Support Document, EPA Evaluation of Ammonia Precursor Demonstration, 
San Joaquin Valley Moderate Area PM<INF>2.5</INF> Plan for the 2012 
PM<INF>2.5</INF> NAAQS,'' August 2021 (``EPA's Ammonia Precursor 
TSD''), summarizes the annual average sensitivity of ambient 
PM<INF>2.5</INF> concentrations to ammonia emission reductions (see 
Table 2 of the EPA's Ammonia Precursor TSD) and provides further 
summary and context with respect to the State's ammonia precursor 
demonstration for the 2012 annual PM<INF>2.5</INF> NAAQS.
    For ammonia, SO<INF>X</INF>, and VOC, CARB assesses the 2015 annual 
average concentration of each precursor in ambient PM<INF>2.5</INF> at 
Bakersfield, for which the necessary speciated PM<INF>2.5</INF> data 
was available and where the highest PM<INF>2.5</INF> design values have 
been recorded in most years, and compares those concentrations to the 
recommended annual average contribution threshold of 0.2 [mu]g/
m\3\.\80\ CARB concludes that the 2015 annual average contributions of 
ammonia, SO<INF>X</INF>, and VOC are 5.2 [mu]g/m\3\, 1.6 [mu]g/m\3\ and 
6.2 [mu]g/m\3\, respectively.
---------------------------------------------------------------------------

    \80\ 2018 PM<INF>2.5</INF> Plan, App. G, 3. The 2018 
PM<INF>2.5</INF> Plan presents a graphical representation of annual 
average ambient PM<INF>2.5</INF> 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<INF>2.5</INF> Plan, Ch. 3, 3-3 to 3-4.
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    For ammonia, SO<INF>X</INF>, and VOC, the State modeled the 
sensitivity of ambient PM<INF>2.5</INF> to 30% and 70% reductions in 
anthropogenic emissions of each precursor pollutant for modeled years 
2013, 2020, and 2024. The year 2013 is the 2018 PM<INF>2.5</INF> Plan's 
base year; 2020 is the modeled attainment year for the 1997 
PM<INF>2.5</INF> NAAQS; and 2024 is the modeled attainment year for the 
2006 24-hour PM<INF>2.5</INF> NAAQS. For the 2012 annual 
PM<INF>2.5</INF> NAAQS, the modeled attainment year is 2025, but the 
State did not conduct precursor sensitivity modeling for that 
additional year. Instead the State assumed that 2024 and 2025 would 
have very similar results; \81\ and results for 2024 were used as a 
proxy for those of 2025. Emissions totals for those two years are 
within 0.2% of each other for all pollutants, except that 
NO<INF>X</INF> emissions are 3% lower in 2025.\82\ Depending on the 
analysis year and percentage precursor emission reduction, the 
sensitivity of ambient PM<INF>2.5</INF> to reductions in annual average 
precursor emissions ranges from 0.08 [mu]g/m\3\ to 2.30 [mu]g/m\3\ for 
ammonia; from -0.05 [mu]g/m\3\ to 0.15 [mu]g/m\3\ for SO<INF>X</INF>; 
and from -0.50 [mu]g/m\3\ to 0.40 [mu]g/m\3\ for VOC.\83\
---------------------------------------------------------------------------

    \81\ Id. at Ch. 7, 7-7, and App. G, 10.
    \82\ 2018 PM<INF>2.5</INF> Plan, App. B. As discussed below, the 
lower NO<INF>X</INF> emissions in 2025 compared to 2024 mean that 
the PM<INF>2.5</INF> response to ammonia reductions would be lower 
than those stated in the Plan's precursor demonstration; using 2024 
results is more conservative than using 2025 results.
    \83\ Id. at App. G, tables 2 through 7 for ammonia, tables 8 and 
9 for SO<INF>X</INF>, and tables 10 through 15 for VOC.
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    For ammonia, the modeled sensitivity of ambient PM<INF>2.5</INF> 
levels to a 30% or 70% emission reduction exceeds 0.2 [mu]g/m\3\ in 
certain years at specific monitoring sites. As discussed in section 
IV.B.3.a of this proposed rule, for the 30% reduction results for 2024, 
upon which the State primarily relied, 2 out of 15 monitoring sites 
have responses above the threshold and the ambient PM<INF>2.5</INF> 
response declines substantially from 2020 to 2024, with the decline 
being generally larger for the sites with the highest projected 
PM<INF>2.5</INF> levels. In contrast, for SO<INF>X</INF> and VOC, the 
modeled sensitivity of ambient PM<INF>2.5</INF> levels to a 30% or 70% 
emission reduction in either precursor is below 0.2 [mu]g/m\3\ in all 
model scenarios except one, including a disbenefit (i.e., ambient 
PM<INF>2.5</INF> levels increase when precursor emissions are reduced) 
at some monitoring sites for both precursors. For 2013, the State's 
modeling shows an ambient PM<INF>2.5</INF> change greater than 0.2 
[mu]g/m\3\ at 7 out of 15 monitoring sites in response to a 70% VOC 
emission reduction. According to the State, however, such sensitivity 
results do not reflect the current atmospheric chemistry in the SJV 
given the projected emission reductions from 2013 to 2024 for all four 
PM<INF>2.5</INF> precursors, especially for VOC and NO<INF>X</INF>, as 
further described in this proposed rule.

[[Page 74319]]

    The State supplemented the sensitivity analysis, particularly for 
ammonia, with consideration of additional information such as emission 
trends, the appropriateness of future year versus base year 
sensitivity, available emission controls, and the severity of 
nonattainment.\84\ These factors were identified in the then-available 
Draft PM<INF>2.5</INF> Precursor Guidance, as well as in the final 
PM<INF>2.5</INF> Precursor Guidance, as factors that may be relevant to 
a sensitivity-based contribution analysis.\85\
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    \84\ Id. at App. G, 5.
    \85\ PM<INF>2.5</INF> Precursor Guidance, 18-19 (consideration 
of additional information), 31 (available emission controls), and 
35-36 (appropriateness of future year versus base year sensitivity).
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    The State notes that a 53% reduction in (baseline) NO<INF>X</INF> 
emissions is projected to occur between 2013 and 2024,\86\ so the 
conditions in the early years will not persist and the future year is 
more representative of the Valley's ambient conditions than earlier 
years. The 2018 PM<INF>2.5</INF> Plan's precursor demonstration also 
presents a review of District agricultural rules that control VOC 
emissions and also provide ammonia co-benefits. The State concludes 
that a 30% reduction is a reasonable upper bound on the ammonia 
reductions to model. Finally, the 2018 PM<INF>2.5</INF> Plan's 
precursor demonstration presents extensive support for the State's 
conclusion regarding an ambient excess of ammonia relative to 
NO<INF>X</INF>, i.e., that particulate ammonium nitrate formation is 
NO<INF>X</INF>-limited, and will become increasingly NO<INF>X</INF>-
limited as NO<INF>X</INF> reductions increase into the future.
---------------------------------------------------------------------------

    \86\ 2018 PM<INF>2.5</INF> Plan, App. G, 8.
---------------------------------------------------------------------------

EPA Evaluation and Proposed Action
    The EPA has evaluated the State's precursor demonstration in the 
2018 PM<INF>2.5</INF> Plan, as well as other relevant information 
available to the EPA, consistent with the PM<INF>2.5</INF> SIP 
Requirements Rule and the recommendations in the PM<INF>2.5</INF> 
Precursor Guidance. Based on this evaluation, the EPA agrees with the 
State's conclusion that NO<INF>X</INF> emissions contribute 
significantly to ambient PM<INF>2.5</INF> levels that exceed the 2012 
annual PM<INF>2.5</INF> NAAQS in the SJV and that NO<INF>X</INF> 
emission sources, therefore, remain subject to control requirements 
under subparts 1 and 4 of part D, title I of the Act. Additionally, for 
the reasons provided in the following paragraphs, the EPA proposes to 
approve the State's comprehensive precursor demonstrations for ammonia, 
SO<INF>X</INF>, and VOC based on a conclusion that emissions of these 
precursor pollutants do not contribute significantly to ambient 
PM<INF>2.5</INF> levels that exceed the 2012 annual PM<INF>2.5</INF> 
NAAQS in the SJV.
    The State based its analyses on the latest available data and 
studies concerning ambient PM<INF>2.5</INF> formation in the SJV from 
precursor emissions. For the required concentration-based analysis, the 
State assessed the absolute annual average contribution of each 
precursor to ambient PM<INF>2.5</INF> (i.e., in 2015). Given that the 
absolute concentrations in 2015 were above the EPA's recommended 
contribution thresholds for both the 24-hour and annual average 
PM<INF>2.5</INF> NAAQS, the State proceeded to a sensitivity-based 
analysis, consistent with the PM<INF>2.5</INF> SIP Requirements Rule.
    For the sensitivity-based analysis, the State performed its 
analyses based on the EPA's recommended approach--i.e., for each 
modeled year and level of precursor emissions reduction (in 
percentages), the State estimated the ambient PM<INF>2.5</INF> response 
using the procedure recommended in the PM<INF>2.5</INF> Precursor 
Guidance, and compared the result to the EPA's recommended contribution 
threshold. In particular, the State considered the EPA's recommended 
range of emission reductions (30% to 70%) for the 2013 base year, 2020 
(an interim year), and the 2024 future year, and quantified the 
estimated response of ambient PM<INF>2.5</INF> concentrations to 
precursor emission changes in the SJV.
    The State's emissions projections in the 2018 PM<INF>2.5</INF> Plan 
show that baseline emissions of each of these precursors will decrease 
from the 2013 base year to both 2021 and 2025. These decreases are 
included in the State's modeled projections of ambient PM<INF>2.5</INF> 
levels in the SJV for purposes of demonstrating attainment and RFP. The 
State's sensitivity analyses are consistent with these projections, in 
accordance with the EPA's recommendations in the PM<INF>2.5</INF> 
Precursor Guidance.\87\
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    \87\ PM<INF>2.5</INF> Precursor Guidance, 35.
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    In the subsections that follow, we summarize our evaluation of the 
State's precursor demonstrations for ammonia, SO<INF>X</INF>, and VOC 
for purposes of the 2012 annual PM<INF>2.5</INF> NAAQS in the SJV.
(a) Ammonia Precursor Demonstration
    In the 2018 PM<INF>2.5</INF> Plan, CARB estimates the ambient 
PM<INF>2.5</INF> response to both a 30% and a 70% emissions reduction 
in 2013, 2020, and 2024. We have evaluated CARB's sensitivity-based 
contribution analyses for 2013, 2020, and 2024 (in the 2018 
PM<INF>2.5</INF> Plan) and CARB's determination that 2024 results are 
representative of conditions in the SJV for purposes of a sensitivity-
based analysis, as discussed in the following paragraphs. The EPA's 
PM<INF>2.5</INF> Precursor Guidance explicitly provides for 
consideration of a future year, such as the attainment year.\88\ We 
consider it appropriate for the State to take into account additional 
information as part of its evaluation of whether the ammonia 
contribution is significant and to rely on the responses to the 30% 
modeled ammonia emissions reduction in its precursor demonstration for 
ammonia. The State primarily relied on the 30% reduction results after 
concluding that 30% was a reasonable upper bound on potential ammonia 
reductions, based on past research on ammonia emissions and potential 
control options for agricultural sources. The EPA agrees that this is a 
reasonable upper bound on ammonia emissions reductions to use in the 
precursor demonstration, as discussed in EPA's approval of the 
precursor demonstration for the 2006 24-hour PM<INF>2.5</INF> 
NAAQS.\89\ We provide a detailed evaluation of the State's precursor 
demonstration for ammonia emissions in the EPA's Ammonia Precursor TSD.
---------------------------------------------------------------------------

    \88\ Id.
    \89\ 85 FR 17382 (March 27, 2020), 17395; EPA's PM<INF>2.5</INF> 
Precursor TSD, 13.
---------------------------------------------------------------------------

    The precursor demonstration in the 2018 PM<INF>2.5</INF> Plan 
indicates that the ambient response to a 30% ammonia emission reduction 
would exceed the EPA's recommended contribution threshold of 0.2 [mu]g/
m\3\ for 14 out of 15 monitoring sites in the 2013 analysis year, and 
at 9 out of 15 for the 2020 analysis year. For the 2024 analysis year, 
2 of the 15 sites would exceed the contribution threshold, Madera and 
Hanford. In absolute terms, the ambient PM<INF>2.5</INF> response 
declines from 0.24 [mu]g/m\3\ in 2020 to 0.12 [mu]g/m\3\ in 2024 at 
Bakersfield-Planz, the highest concentration site. The Madera and 
Hanford responses decline, respectively, from 0.36 to 0.21 [mu]g/m\3\, 
and from 0.42 to 0.26 [mu]g/m\3\. The average response over all 
monitoring sites declines from 0.23 [mu]g/m\3\ to 0.14 [mu]g/m\3\, with 
the decline being generally larger for the sites with the highest 
projected PM<INF>2.5</INF> levels.
    While the Madera and Hanford responses to ammonia reductions are 
above the contribution threshold, additional information about these 
locations leads the EPA to give these responses lower weight in the 
overall assessment of whether ammonia contributes significantly to 
PM<INF>2.5</INF> levels. The State notes that the 2013 base year Madera 
monitored concentrations are

[[Page 74320]]

biased high,\90\ which would lead to model estimates of the response to 
ammonia reductions that are biased high (because for model projections, 
relative responses of the model to emissions changes are applied to 
monitored concentrations). While the State did not discuss the evidence 
for this in detail in its 2018 PM<INF>2.5</INF> Plan, it is consistent 
with an analysis of Madera measured concentrations that the State 
provided in a prior PM<INF>2.5</INF> plan for the SJV.\91\ The EPA has 
previously discussed that the Madera data for the limited period of 
2011 to 2013 are not representative for purposes of an attainment 
demonstration.\92\
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    \90\ 2018 PM<INF>2.5</INF> Plan, App. G, 14.
    \91\ ``Assessment of the Representativeness of 2011 
PM<INF>2.5</INF> Beta Attenuation Monitor Data from Madera,'' in 
``Staff Report, ARB Review of San Joaquin Valley PM<INF>2.5</INF> 
State Implementation Plan,'' adopted by CARB on May 21, 2015, App. 
A, ``Weight of Evidence Analysis.''
    \92\ 81 FR 6936, 6971 (February 9, 2016). The conclusion that 
2011-2013 Madera data was biased high was based on it not fitting 
the north-south concentration gradient historically seen in 
relations to other monitors, a comparison to data from a second 
monitor at the same site, and the return to the historic pattern 
after adjustments were made to instrument operation after checking 
its zero point. The data is considered valid in the EPA's Air 
Quality System (AQS) for purposes of assessing whether the NAAQS is 
met. However, the EPA considered it to be anomalously high for that 
period, and not representative for use in modeling. Adjusted 
substituted data from nearby monitors had concentrations about 10% 
lower, and were accepted by the EPA for the demonstration of 
attainment of the 1997 annual PM<INF>2.5</INF> NAAQS.
---------------------------------------------------------------------------

    For the 2018 PM<INF>2.5</INF> Plan precursor demonstration, 
Madera's ambient PM<INF>2.5</INF> response in 2024 to a 30% ammonia 
emissions reduction was 0.21 [mu]g/m\3\, just 5% above EPA's 
recommended contribution threshold of 0.2 [mu]g/m\3\. Because the 2024 
modeling starting point was a base design value using monitored 
concentrations from 2010-2014, if more typical Madera concentrations 
were used, it is likely that the 2024 Madera response to ammonia 
reductions would be below the contribution threshold. Moreover, given 
the NO<INF>X</INF> emission reductions that are projected to continue 
from 2024 to 2025, the EPA expects that PM<INF>2.5</INF> sensitivity to 
ammonia reductions would decrease from the 0.21 [mu]g/m\3\ unadjusted 
value in 2024 to a lower value in 2025, likely decreasing even the 
unadjusted, biased-high value to below the threshold.
    There is also information suggesting that the Hanford response to 
ammonia reductions may be lower than indicated in the State's 2018 
PM<INF>2.5</INF> Plan precursor demonstration. An independent study 
using aircraft and surface data from the winter 2013 DISCOVER-AQ \93\ 
campaign, a key period in the 2018 PM<INF>2.5</INF> Plan's 2013 base 
year, found that the Community Multiscale Air Quality (CMAQ) model 
underestimated ammonia at Hanford by roughly a factor of five; Hanford 
is just outside a region with high ammonia emissions in the model 
(western Tulare County).\94\ If the model's ammonia concentrations were 
higher to better match observations, then there would be relatively 
more ammonia per NO<INF>X</INF>; ammonia then would be less of a 
limiting factor for particulate ammonium nitrate formation and the 
model response to ammonia reductions would be lower. This phenomenon is 
described more fully below.
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    \93\ NASA, ``Deriving Information on Surface conditions from 
COlumn and VERtically Resolved Observations Relevant to Air 
Quality,'' described at <a href="https://www.nasa.gov/mission_pages/discover-aq/index.html">https://www.nasa.gov/mission_pages/discover-aq/index.html</a>.
    \94\ Kelly, J.T. et al. 2018, ``Modeling 
NH<INF>4</INF>NO<INF>3</INF> over the San Joaquin Valley during the 
2013 DISCOVER-AQ campaign,'' Journal of Geophysical Research: 
Atmospheres, 123, 4727-4745, <a href="https://doi.org/10.1029/2018JD028290">https://doi.org/10.1029/2018JD028290</a> at 
4733. The paper notes that, despite the ammonia underestimation, 
model performance was good for particulate ammonium nitrate and the 
ammonium nitrate was not sensitive to the ammonia underestimate 
since its formation was NO<INF>X</INF>-limited.
---------------------------------------------------------------------------

    The 2018 PM<INF>2.5</INF> Plan did not include an evaluation of 
model performance for ammonia per se (just for particulate ammonium), 
but in supplemental transmittals \95\ CARB described the results of two 
analyses confirming the likely underestimation of ammonia. CARB 
compared CMAQ model predictions of ammonia with the 2013 DISCOVER-AQ 
aircraft measurements and found that ammonia was underpredicted, and 
noted that this would result in the PM<INF>2.5</INF> response to 
ammonia reductions being overpredicted. CARB also compared 2017 
satellite measurements of ammonia with CMAQ model predictions and found 
that modeled ammonia concentrations were half of the magnitude of the 
satellite observations at some locations, and the modeled average in 
the SJV was about 25% less than observed. CARB concluded that the model 
tends to overpredict the sensitivity of ammonium nitrate formation to 
ammonia emission reductions. CARB also speculated that the 
underprediction could be partly be explained by the underestimation of 
ammonia emissions using current methodologies.\96\ If modeled ammonia 
concentrations were closer to observations, e.g., via increased 
emissions in the model, then the modeled response to ammonia precursor 
reductions would be lower than shown in the 2018 PM<INF>2.5</INF> 
Plan's precursor demonstration. An increase in modeled ambient ammonia 
(such as via a larger emissions estimate) would also make the model 
response more consistent with the evidence from the ambient measurement 
studies that are discussed next.
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    \95\ CARB's April 19, 2021, Precursor Clarification and CARB's 
April 26, 2021, Precursor Clarification.
    \96\ As discussed in EPA's Ammonia Precursor TSD, there is 
evidence that ammonia emisions are underestimated, based on 
comparsons between satellite measurements and what would be expected 
from emissions inventories.
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    As additional information for assessing the contribution of ammonia 
to PM<INF>2.5</INF>, the State discussed evidence from multiple ambient 
measurement studies.\97\ The studies suggest a very low ambient 
sensitivity to ammonia, based on measured excess ammonia relative to 
NO<INF>X</INF>, the abundance of particulate nitrate relative to 
gaseous NO<INF>X</INF>, and the large abundance of ammonia relative to 
nitric acid. The studies all conclude that there is a large amount of 
ammonia left over after reacting with NO<INF>X</INF>, so that ammonia 
emission reductions would be expected mainly to reduce the amount of 
ammonia excess, rather than to reduce the particulate amonium nitrate. 
These ambient studies provide strong evidence independent of the 
modeling that PM<INF>2.5</INF> would respond only weakly to ammonia 
emissions reductions.
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    \97\ 2018 PM<INF>2.5</INF> Plan, 6-7, and App. G, G-9 to G-10; 
the CARB 2018 Staff Report, App. C, 12-15; and Submittal Letter, 
Attachment A. These studies are also discussed in the EPA's 
PM<INF>2.5</INF> Precursor TSD.
---------------------------------------------------------------------------

    Another consideration is that the PM<INF>2.5</INF> benefit of 
ammonia emission reductions is projected to decline steeply over time. 
In selecting the analysis year for a precursor demonstration, we 
believe it is appropriate to consider changes in atmospheric chemistry 
that may occur between the base or current year and the attainment year 
because the changes may ultimately affect the nonattainment area's 
progress toward expeditious attainment. The PM<INF>2.5</INF> Precursor 
Guidance explicitly states that a future year may be used, and that 
there are a multitude of considerations in choosing the analysis 
year.\98\ The ``anticipated growth or loss of sources . . . or trends 
in ambient speciation data and precursor emissions'' \99\ are among the 
``facts and circumstances of the area'' \100\ to consider in 
determining the significance of a precursor. The Guidance states that a 
future year could be more appropriate if it better represents the 
period that sources will operate in. As discussed in more detail below, 
the 2024 model results better

[[Page 74321]]

represent the period that ammonia sources will operate in, because of 
the steep decline in NO<INF>X</INF> emissions projected to occur by 
2024 and 2025. We consider it reasonable for the State to focus on the 
ambient PM<INF>2.5</INF> response to ammonia emission reductions in 
2024, rather than an earlier year, as the modeled response in 2024 in 
the SJV better reflects the potential benefit of ammonia control 
measures for purposes of expeditious attainment of the 2012 annual 
PM<INF>2.5</INF> NAAQS.
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    \98\ PM<INF>2.5</INF> Precursor Guidance, 35.
    \99\ Id. at 18.
    \100\ PM<INF>2.5</INF> SIP Requirements Rule, 40 CFR 
51.1006(a)(1)(ii).
---------------------------------------------------------------------------

    The State's precursor demonstration in the 2018 PM<INF>2.5</INF> 
Plan shows that ambient sensitivity to ammonia emission reductions in 
the SJV declines steeply over time. Between 2020 and 2024, the modeled 
response to a 30% ammonia emission reduction declines by 50% at the 
Bakersfield-Planz monitoring site, which has the highest projected 
PM<INF>2.5</INF> level, and by 37% averaged over all monitoring 
sites.\101\ As noted above, in absolute terms, the ambient 
PM<INF>2.5</INF> response declines from 0.24 [mu]g/m\3\ in 2020 to 0.12 
[mu]g/m\3\ in 2024 at Bakersfield-Planz, which has the highest 
projected PM<INF>2.5</INF> design value, and from 0.23 [mu]g/m\3\ to 
0.14 [mu]g/m\3\ as averaged over all monitoring sites, with the decline 
being generally larger for the sites with the highest projected 
PM<INF>2.5</INF> levels. Thus, between 2020 and 2024, the number of 
sites at which modeled sensitivity exceeds the 0.2 [mu]g/m\3\ threshold 
declines from 9 out of 15 down to 1 or 2 out of 15.\102\ As discussed 
above, ammonia sensitivity declines because of the shifting atmospheric 
chemistry caused by NO<INF>X</INF> emissions decreases. NO<INF>X</INF> 
emissions are projected to decrease 27% between 2020 and 2024 due to 
baseline measures (e.g., existing motor vehicle controls). The 
decreased NO<INF>X</INF> emissions will make ammonia more abundant 
relative to NO<INF>X</INF>, and even less of a limiting factor on 
PM<INF>2.5</INF> formation. In other words, the model response in the 
future year 2024 gives a more realistic assessment of the potential 
effect of ammonia controls than past or current conditions. Between 
2024 and 2025, the attainment year, NO<INF>X</INF> emissions are 
projected to decrease by an additional 3.5% from 2024 levels,\103\ so 
that the response to ammonia reductions in the attainment year would be 
lower than the 2024 results reported in the Plan.
---------------------------------------------------------------------------

    \101\ Extrapolating the 2018 PM<INF>2.5</INF> Plan results to 
2025, the percent declines are 55% and 40%, respectively, which are 
larger still than those for 2024.
    \102\ 2018 PM<INF>2.5</INF> Plan, App. G, tables 4 and 5, G-11. 
As discussed above, the response for the Madera site is likely below 
the contribution threshold since its monitored concentrations are 
biased high.
    \103\ Annual average NO<INF>X</INF> emissions are projected to 
decrease from 148.9 tpd in 2024 to 143.7 tpd in 2025. 2018 
PM<INF>2.5</INF> Plan, App. B, Table B-2.
---------------------------------------------------------------------------

    Finally, based on the 2024 sensitivity results,\104\ if ammonia 
emissions were reduced by 30%, the area's projected 12.0 [mu]g/m\3\ 
design value, occurring at the Bakersfield-Planz monitoring site, would 
be reduced by 0.12 [mu]g/m\3\, which would not be considered 
significant (it is below the EPA's recommended threshold of 0.2 [mu]g/
m\3\).
---------------------------------------------------------------------------

    \104\ 2018 PM<INF>2.5</INF> Plan, App. G, tables 5 and 7, 11-12. 
The response to 2025 ammonia reductions would be lower than the 
values stated in the text, due to the effect of declining 
NO<INF>X</INF> emissions.
---------------------------------------------------------------------------

    In sum, we conclude that the State quantified the sensitivity of 
ambient PM<INF>2.5</INF> levels to reductions in ammonia emissions 
using appropriate modeling technique; the modeled response to ammonia 
reductions is likely lower than reported; and the State's choice of 
2024 and 2025 as the reference points for purposes of evaluating the 
sensitivity of ambient PM<INF>2.5</INF> levels to ammonia emission 
reductions is well-supported. Based on all of these considerations, the 
EPA proposes to approve the State's demonstration that ammonia 
emissions do not contribute significantly to ambient PM<INF>2.5</INF> 
levels that exceed the 2012 annual PM<INF>2.5</INF> NAAQS in the SJV.
(b) SO<INF>X</INF> Precursor Demonstration
    In the 2018 PM<INF>2.5</INF> Plan, CARB estimated the 2013 ambient 
PM<INF>2.5</INF> response to a 30% SO<INF>X</INF> emission reduction to 
range from -0.01 [mu]g/m\3\ to 0.07 [mu]g/m\3\ and estimated the 
ambient PM<INF>2.5</INF> response to a 70% SO<INF>X</INF> emission 
reduction to range from -0.05 [mu]g/m\3\ to 0.15 [mu]g/m\3\.\105\ The 
State also provides an emissions trend chart that shows SO<INF>X</INF> 
emissions to be steady at approximately 8 tpd from 2013 through 2024. 
Given that the relative levels of estimated SO<INF>X</INF> and ammonia 
emissions over that timeframe remain similar, the State concludes that 
the 2013 sensitivities are also representative of future years.\106\ 
The State also provides the ambient PM<INF>2.5</INF> responses in 2013, 
2020, and 2024 to 30% and 70% reductions in SO<INF>X</INF> emissions, 
all of which are below the 0.2 [mu]g/m\3\ contribution threshold.\107\
---------------------------------------------------------------------------

    \105\ Id. at App. G, 15-16, tables 8 and 9.
    \106\ 2018 PM<INF>2.5</INF> Plan, App. G, 15. The State includes 
modeling of 30% and 70% reductions of SO<INF>X</INF> only for 2013, 
finding that the sensitivity of ambient PM<INF>2.5</INF> to such 
changes were below the EPA's recommended threshold, and that the 
2020 and 2024 results would differ little from 2013 due to the 
similarity of emissions conditions over time. App. G, 17. CARB's 
September 2019 Precursor Clarification provides the 2020 and 2024 
sensitivity results, which are indeed very close to those for 2013.
    \107\ CARB's September 2019 Precursor Clarification.
---------------------------------------------------------------------------

    We note that the 2018 PM<INF>2.5</INF> Plan's sensitivity estimates 
for 2013 are well below that threshold for both the 30% and 70% 
emission reduction scenarios and even negative for certain monitoring 
sites. Given those results and the steady SO<INF>X</INF> emission 
levels over 2013 to 2025 (as opposed to increases), the EPA agrees with 
the State's conclusion that the 2013 modeled sensitivities provide a 
sufficient basis for the SO<INF>X</INF> precursor demonstration. The 
supplemental results provided by the State for 2020 and 2024 support 
this conclusion.
    Therefore, on the basis of these modeled ambient PM<INF>2.5</INF> 
responses to SO<INF>X</INF> emission reductions in the SJV, and the 
facts and circumstances of the area, the EPA proposes to approve the 
State's demonstration that SO<INF>X</INF> emissions do not contribute 
significantly to ambient PM<INF>2.5</INF> levels that exceed the 2012 
annual PM<INF>2.5</INF> NAAQS in the SJV.
(c) VOC Precursor Demonstration
    In the 2018 PM<INF>2.5</INF> Plan, the State found that the ambient 
PM<INF>2.5</INF> response to VOC emission reductions were generally 
below the EPA's recommended contribution threshold of 0.2 [mu]g/m\3\, 
and predicted an increase in ambient PM<INF>2.5</INF> levels in 
response to VOC reductions (i.e., a disbenefit) at 2 out of 15 
monitoring sites in 2020, and 11 out of 15 sites in 2024. Only for a 
70% emission reduction for the 2013 base year did the State predict the 
ambient PM<INF>2.5</INF> response to be above the threshold at a 
majority of sites.\108\
---------------------------------------------------------------------------

    \108\ 2018 PM<INF>2.5</INF> Plan, App. G, 18-19, tables 10 and 
11.
---------------------------------------------------------------------------

    We note that the 2018 PM<INF>2.5</INF> Plan's sensitivity estimates 
for 2020 and 2024 are well below that threshold for both the 30% and 
70% emission reduction scenarios, and even negative for certain 
monitoring sites. The State also provides an emissions trend chart that 
shows VOC emissions are projected to decrease by about 30 tpd, or 9% 
between 2013 and 2020 as well as between 2013 and 2024, and concludes 
that 2013 sensitivity results are not representative into the future 
and that the 2020 and 2024 results are representative.\109\ Finally, 
the State concludes that VOC emissions do not contribute significantly 
to PM<INF>2.5</INF> levels that exceed the 2012 annual PM<INF>2.5</INF> 
NAAQS.
---------------------------------------------------------------------------

    \109\ Id. at App. G, 19-20.
---------------------------------------------------------------------------

    The EPA has evaluated and agrees with the State's determination in 
the 2018 PM<INF>2.5</INF> Plan that the projected 2024 year is more 
representative of conditions in the SJV for sensitivity-based analyses 
and that VOC reductions in 2024 would mostly result in a

[[Page 74322]]

disbenefit to ambient PM<INF>2.5</INF> levels, seen at 11 of 15 
monitoring sites. The EPA agrees that the 9% VOC emissions decrease 
from 2013 to 2024 supports reliance on the 2024 modeling results. 
Furthermore, there is projected to be a large decrease in 
NO<INF>X</INF> emissions over this period, as described in section 
IV.B.2 of this proposed rule, that affects the atmospheric chemistry 
with respect to ambient PM<INF>2.5</INF> formation from VOC emissions. 
The 9% VOC emission reductions and the vast majority of NO<INF>X</INF> 
emissions reductions are expected to result from baseline measures 
already in effect. Therefore, we conclude that it is reasonable to rely 
on future year 2024 modeled responses to VOC reductions. The EPA also 
concludes that the State provided a reasonable explanation for the VOC 
reduction disbenefit and evidence that it occurs in the SJV; as 
discussed in the EPA's PM<INF>2.5</INF> Precursor TSD, VOC reductions 
led to less peroxyacetyl nitrate formation, and so to greater 
availability of nitrate to form particulate ammonium nitrate.\110\
---------------------------------------------------------------------------

    \110\ EPA's PM<INF>2.5</INF> Precursor TSD, 22.
---------------------------------------------------------------------------

    For these reasons, we propose to approve the State's demonstration 
that VOC emissions do not contribute significantly to ambient 
PM<INF>2.5</INF> levels that exceed the 2012 annual PM<INF>2.5</INF> 
NAAQS in the SJV.

C. Air Quality Modeling

1. Requirements for Air Quality Modeling
    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<INF>2.5</INF> NAAQS by the 
applicable attainment date. As noted in sections I and II of this 
proposed rule, the outermost statutory Serious area attainment date for 
the 2012 annual PM<INF>2.5</INF> NAAQS in the SJV is December 31, 2025.
    The PM<INF>2.5</INF> SIP Requirements Rule explains that Serious 
area plans under CAA section 189(b) must include a demonstration 
(including air quality modeling) that the control strategy provides for 
attainment of the PM<INF>2.5</INF> NAAQS as expeditiously as 
practicable.\111\ 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), and any other emissions controls that are needed for 
expeditious attainment of the NAAQS.
---------------------------------------------------------------------------

    \111\ 40 CFR 51.1011(b)(1); 81 FR 58010, 58087.
---------------------------------------------------------------------------

    The EPA's PM<INF>2.5</INF> modeling guidance \112\ (``Modeling 
Guidance'' and ``Modeling Guidance Update'') recommends that states use 
a photochemical model, such as the CMAQ model, to simulate a base case, 
with meteorological and emissions inputs reflecting a base case year to 
replicate concentrations monitored in that year. The Modeling Guidance 
recommends the following procedures for states to use in attainment 
demonstrations. The model should undergo a performance evaluation to 
ensure that it satisfactorily reproduces the concentrations monitored 
in the base case year. The model may then be used to simulate emissions 
occurring in other years required for an attainment plan, namely the 
base year (which may differ from the base case year) and future 
year.\113\ The Modeling Guidance recommends that the modeled response 
to the emission changes between the base and future years be used to 
calculate relative response factors (RRFs). The modeled RRFs are then 
applied to the monitored design value in the base year to estimate the 
projected design value in the future year, which can be compared 
against the NAAQS. In the recommended procedure, the RRFs are 
calculated for each chemical species component of PM<INF>2.5</INF>, 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 
PM<INF>2.5</INF> design value must first be split into its species 
components, using available chemical species measurements. The Modeling 
Guidance provides additional detail on the recommended approach.\114\
---------------------------------------------------------------------------

    \112\ Memorandum dated November 29, 2018, from Richard Wayland, 
Air Quality Assessment Division, OAQPS, EPA, to Regional Air 
Division Directors, EPA, Subject: ``Modeling Guidance for 
Demonstrating Air Quality Goals for Ozone, PM<INF>2.5</INF>, and 
Regional Haze,'' (``Modeling Guidance''), and Memorandum dated June 
28, 2011, from Tyler Fox, Air Quality Modeling Group, OAQPS, EPA, to 
Regional Air Program Managers, EPA, Subject: ``Update to the 24 Hour 
PM<INF>2.5</INF> NAAQS Modeled Attainment Test,'' (``Modeling 
Guidance Update'').
    \113\ In this section, we use the terms ``base case,'' ``base 
year'' or ``baseline,'' and ``future year'' as described in section 
2.3 of the EPA's Modeling Guidance. The ``base case'' modeling 
simulates measured concentrations for a given time period, using 
emissions and meteorology for that same year. The modeling ``base 
year'' (which can be the same as the base case year) is the 
emissions starting point for the plan and for projections to the 
future year, both of which are modeled for the attainment 
demonstration. Modeling Guidance, 37-38. Note that CARB sometimes 
uses ``base year'' synonymously with ``base case'' and ``reference 
year'' instead of ``base year.''
    \114\ Modeling Guidance, section 4.4, ``What is the Modeled 
Attainment Tests for the Annual Average PM<INF>2.5</INF> NAAQS.''
---------------------------------------------------------------------------

2. Summary of State's Submission
    The 2018 PM<INF>2.5</INF> Plan includes a modeled demonstration 
projecting that the SJV will attain the 2012 annual PM<INF>2.5</INF> 
NAAQS by December 31, 2025. The Plan's primary discussion of the 
photochemical modeling appears in Appendix K (``Modeling Attainment 
Demonstration'') of the 2018 PM<INF>2.5</INF> Plan. The State briefly 
summarizes the area's air quality problem in Chapter 2.2 (``Air Quality 
Challenges and Trends'') and summarizes the modeling results in Chapter 
7.4 (``Attainment Demonstration and Modeling'') of the 2018 
PM<INF>2.5</INF> Plan. The State provides a conceptual model of 
PM<INF>2.5</INF> formation in the SJV as part of the modeling protocol 
in Appendix L (``Modeling Protocol''). Appendix J (``Modeling Emission 
Inventory'') describes emission input preparation procedures. The State 
presents additional relevant information in Appendix C (``Weight of 
Evidence Analysis'') of the CARB 2018 Staff Report, which includes 
ambient trends and other data in support of the demonstration of 
attainment by 2025.
3. EPA Evaluation and Conclusion
    CARB's air quality modeling approach investigated the many 
interconnected facets of modeling ambient PM<INF>2.5</INF> in the SJV, 
including model input preparation, model performance evaluation, use of 
the model output for the numerical NAAQS attainment test, and modeling 
documentation. Specifically, this required the development and 
evaluation of a conceptual model, modeling protocol, episode (i.e., 
base year) selection, modeling domain, CMAQ model selection, initial 
and boundary condition procedures, meteorological model choice and 
performance, modeling emissions inventory preparation procedures, model 
performance, attainment test procedure, and adjustments to baseline air 
quality for modeling. These analyses are generally consistent with the 
EPA's recommendations in the Modeling Guidance.
    The model performance evaluation in section 5.2 (``CMAQ Model 
Evaluation'') of Appendix K of the 2018 PM<INF>2.5</INF> Plan included 
statistical and graphical measures of model performance.
    The EPA's evaluation of the modeling for the 2012 annual 
PM<INF>2.5</INF> NAAQS incorporates the evaluation that the EPA 
previously did for other NAAQS in the

[[Page 74323]]

2018 PM<INF>2.5</INF> Plan. The EPA previously evaluated and approved 
the modeling conducted for the 2006 24-hour PM<INF>2.5</INF> NAAQS as 
part of the 2018 PM<INF>2.5</INF> Plan; see the EPA's ``Technical 
Support Document, EPA Evaluation of Air Quality Modeling, San Joaquin 
Valley PM<INF>2.5</INF> Plan for the 2006 PM<INF>2.5</INF> NAAQS,'' 
February 2020 (``EPA's 2006 NAAQS Modeling TSD'') accompanying that 
action for details.\115\ The conclusions in the EPA's 2006 NAAQS 
Modeling TSD focused on the 2006 24-hour PM<INF>2.5</INF> NAAQS; in 
this notice we extend the evaluation with information specific to the 
2012 annual PM<INF>2.5</INF> NAAQS.
---------------------------------------------------------------------------

    \115\ The model performance is discussed further in section J 
(``Air Quality Model Performance'') of the EPA's 2006 NAAQS Modeling 
TSD.
---------------------------------------------------------------------------

    Most aspects of the 2018 PM<INF>2.5</INF> Plan modeling and the 
EPA's evaluation of it are the same for the 24-hour and the annual 
averaging times, and the EPA has found them adequate. These include the 
modeling protocol, choice of model, meteorological modeling, modeling 
emissions inventory, choice of model, modeling domain, and procedures 
for model performance evaluation. One aspect that differs between the 
24-hour and annual averaging times is the specific calculation 
procedure for estimating a future design value. In the procedure 
recommended in the Modeling Guidance for both averaging times, the 
model is used to calculate RRFs, the ratio of modeled future 
concentrations to base year concentrations, and the RRF is applied to 
monitored base year concentrations; this is done for each monitor, 
PM<INF>2.5</INF> species, and calendar quarter. But for the 24-hour 
averaging time, the recommended procedure uses the highest individual 
concentration days in each quarter, whereas for the annual average, it 
uses the average of all days in each quarter. For the current action on 
the 2018 PM<INF>2.5</INF> Plan, the EPA considers that the State 
procedures \116\ for estimating future design values for the 2012 
annual PM<INF>2.5</INF> NAAQS generally followed the EPA's 
recommendations and are adequate.
---------------------------------------------------------------------------

    \116\ 2018 PM<INF>2.5</INF> Plan, App. K, 18.
---------------------------------------------------------------------------

    Another modeling aspect that can differ between 24-hour and annual 
average is the focus of the model performance evaluation on the 
respective averaging times. For the 24-hour average, it is especially 
important that modeled concentrations on the highest days are 
comparable to those on the highest monitored days because calculation 
of the design value for the 24-hour PM<INF>2.5</INF> NAAQS uses the 
98th percentile concentrations. For the annual average, peak 
concentrations continue to be important, but lower concentration days 
are also important because all days are included in the average. Under- 
and over-predictions on non-peak days may average out and have little 
overall effect on the modeled annual concentration, but systematic 
underprediction on non-peak days could lead to model underprediction of 
the annual average concentration. This problem of model bias is 
mitigated by the use of the model in a relative sense as recommended in 
the Modeling Guidance. In the RRF, model bias ``cancels out'' to a 
degree since it would be present in both its numerator (future year) 
and its denominator (base year). Applying the RRF to monitored base 
year concentration in this way anchors the final model prediction to 
real-world concentrations. Further, the Modeling Guidance recommends 
that RRFs be calculated on a quarterly basis, to better account for 
emissions sources and atmospheric chemistry that differ between the 
seasons.
    The 2018 PM<INF>2.5</INF> Plan did not include a separate model 
performance evaluation for the 24-hour and annual PM<INF>2.5</INF> 
averaging times; the State used statistical and graphical analyses 
applicable to both. The EPA evaluated the modeling for the 2012 annual 
PM<INF>2.5</INF> NAAQS using that same information, much of which has 
already been discussed in the EPA's 2006 NAAQS Modeling TSD. For the 
most part, in the EPA's 2006 NAAQS Modeling TSD, the EPA did not 
distinguish between the two averaging times either, but drew 
conclusions for the 24-hour averaging time rather than the annual 
averaging time. That TSD did note a relatively large negative 
normalized bias (underprediction) in the ammonium and nitrate 
performance statistics \117\ for the 2nd quarter for monitoring sites 
in Bakersfield, Fresno, and Visalia; and we add here that the 3rd 
quarter has similar negative bias. Underprediction of total 
PM<INF>2.5</INF> in the 2nd and 3rd quarters is also evident in time 
series plots for most monitoring sites, though by only a small amount 
for several monitoring sites.\118\ The RRF procedure removes much of 
this bias, so the underprediction in the model performance evaluation 
does not translate into an underpredicted 2025 design value. The EPA's 
2006 NAAQS Modeling TSD noted that because those quarters have 
projected concentrations that are less than half of those in the 1st 
and 4th, this may have a small influence on annual average 
concentrations. It has still less influence on the 24-hour average, 
because peak 24-hour concentrations typically occur in winter, i.e., in 
the 1st and 4th quarters. For example, the worst quarterly 
underprediction for nitrate was a for quarter 3, and occurred when 
quarterly total PM<INF>2.5</INF> concentration was 9.4 [mu]g/m\3\. By 
contrast, for quarter 1 nitrate had a small overprediction, and 
occurred when quarterly total PM<INF>2.5</INF> concentration was 21.1 
[mu]g/m\3\. That is, nitrate predictions have more bias during the 
quarters with low PM<INF>2.5</INF> concentrations. This is apparent 
from the Plan's ``bugle'' plot for the four monitors with speciated 
data.\119\ Large (negative) values of bias in nitrate predictions occur 
for the lowest quarterly nitrate concentrations. For the higher 
concentrations that most affect the annual average, nitrate fractional 
bias has a mixture of positive and negative values. For total 
PM<INF>2.5</INF>, fractional bias has a similar seasonal pattern to 
that of nitrate, with underprediction during quarter 2 and quarter 3 
when quarterly PM<INF>2.5</INF> concentration values are in the 5-10 
[mu]g/m\3\ range, and small bias when quarterly concentrations are in 
the 20-30 [mu]g/m\3\ range. For the overall annual average, performance 
is good relative to that seen in other modeling studies with lower 
values of bias and error for multiple performance statistics for 
nitrate, as well as for the other PM<INF>2.5</INF> species and total 
PM<INF>2.5</INF>.\120\
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    \117\ Id. at App. K, 48ff, tables 20 through 23.
    \118\ Id. at App. K, 131ff, Supplemental materials, Figures 
S.41-S.52.
    \119\ Id. at App. K, 53, Figure 13.
    \120\ Id. at App. K, 54, Figure 14.
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    The high PM<INF>2.5</INF> concentration days are generally captured 
by the model, even though some are underpredicted in December at 
certain monitoring sites such as Fresno. Overall, the modeled site 
maxima are comparable to the measurements. Also, the frequency of high 
and low days generally matches observations so the annual as well as 
the daily model performance is acceptable.
    The EPA evaluated, in our rulemaking with respect to the 2006 24-
hour PM<INF>2.5</INF> NAAQS in the SJV, the State's choice of model and 
the extensive discussion in the 2018 PM<INF>2.5</INF> Plan about 
modeling procedures, tests, and performance analyses.\121\ We consider 
the State's analyses consistent with the EPA's guidance on modeling for 
PM<INF>2.5</INF> attainment planning purposes. Based on these reviews, 
we propose to find that the modeling in the 2018 PM<INF>2.5</INF> Plan 
is adequate for the purposes of supporting

[[Page 74324]]

the State's RFP demonstration and the attainment demonstration.
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    \121\ For a more detailed summary of the State's air quality 
modeling in the 2018 PM<INF>2.5</INF> Plan with respect to the 2006 
24-hour PM<INF>2.5</INF> NAAQS, rather than the 2012 annual 
PM<INF>2.5</INF> NAAQS, please refer to the EPA's 2006 NAAQS 
Modeling TSD.
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D. Best Available Control Measures

1. Statutory and Regulatory Requirements
    Section 189(b)(1)(B) of the Act requires for any serious 
PM<INF>2.5</INF> nonattainment area that the state submit provisions to 
assure that the best available control measures (BACM) for the control 
of PM<INF>2.5</INF> and PM<INF>2.5</INF> 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<INF>2.5</INF> SIP Requirements Rule to mean ``any technologically 
and economically feasible control measure that can be implemented in 
whole or in part within 4 years after the date of reclassification of a 
Moderate PM<INF>2.5</INF> nonattainment area to Serious and that 
generally can achieve greater permanent and enforceable emissions 
reductions in direct PM<INF>2.5</INF> emissions and/or emissions of 
PM<INF>2.5</INF> 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).'' \122\
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    \122\ 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.
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    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.\123\ 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.\124\ If RACM and RACT level controls of emissions have been 
insufficient to reach attainment, the CAA contemplates the 
implementation of more stringent controls, controls on more sources, or 
other adjustments to the control strategy necessary to attain the NAAQS 
in the area.
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    \123\ 81 FR 58010, 58081 and General Preamble Addendum, 42011, 
42013.
    \124\ Id. and General Preamble Addendum, 42009-42010.
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    Consistent with longstanding guidance provided in the General 
Preamble Addendum, the preamble to the PM<INF>2.5</INF> SIP 
Requirements Rule discusses the following steps for determining BACM 
and BACT:
    1. Develop a comprehensive emission inventory of the sources of 
PM<INF>2.5</INF> and PM<INF>2.5</INF> 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.\125\
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    \125\ 81 FR 58010, 58083-58085.
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    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.\126\
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    \126\ 40 CFR 51.1010(a)(3) and 81 FR 58010, 58041-58042.
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    Once these analyses are complete, the state must use this 
information to develop enforceable control measures and submit them to 
the EPA for evaluation as SIP provisions to meet the basic requirements 
of CAA section 110 and any other applicable substantive provisions of 
the Act. The EPA is using these steps as guidelines in the evaluation 
of the BACM and BACT measures and related analyses in the SJV 
PM<INF>2.5</INF> Plan.
2. Summary of State's Submission
    As discussed in section IV.A of this proposed rule, Appendix B of 
the 2018 PM<INF>2.5</INF> Plan contains the planning inventories for 
direct PM<INF>2.5</INF> and all PM<INF>2.5</INF> precursors 
(NO<INF>X</INF>, SO<INF>X</INF>, VOC, and ammonia) for the SJV 
nonattainment area together with documentation to support these 
inventories. Each inventory includes emissions from stationary, area, 
on-road, and non-road emission sources, and the State specifically 
identifies the condensable component of direct PM<INF>2.5</INF> for 
relevant stationary and area source categories. As discussed in section 
IV.B of this proposed rule concerning precursors, the State's analysis 
indicates that the Plan should control emissions of PM<INF>2.5</INF> 
and NO<INF>X</INF> in order to reach attainment. Accordingly, the State 
evaluated potential controls for those pollutants in the analysis of 
what is necessary to meet the BACM (including BACT) requirements.
    For stationary and area sources, the District identifies the 
sources of direct PM<INF>2.5</INF> and NO<INF>X</INF> in the SJV that 
are subject to District emission control measures and provides its 
evaluation of these regulations for compliance with BACM requirements 
in Appendix C of the 2018 PM<INF>2.5</INF> 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<INF>2.5</INF> and 
NO<INF>X</INF> emission sources, and control measures implemented in 
other ozone and PM<INF>2.5</INF> nonattainment areas in California and 
other states.\127\ Based on these analyses, the District concludes that 
all best available control measures for stationary and area sources are 
in place in the SJV for NO<INF>X</INF> and directly emitted 
PM<INF>2.5</INF> for purposes of meeting the BACM/BACT requirement for 
the 2012 annual PM<INF>2.5</INF> NAAQS.
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    \127\ 2018 PM<INF>2.5</INF> Plan, Ch. 4, section 4.3.1.
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    For mobile sources, CARB identifies the sources of direct 
PM<INF>2.5</INF> and NO<INF>X</INF> in the SJV that are subject to the 
State's emission control measures and provides its evaluation of these 
regulations for compliance with BACM requirements in Appendix D of the 
2018 PM<INF>2.5</INF> Plan. Appendix D describes CARB's process for 
determining BACM, including identification of the sources of direct 
PM<INF>2.5</INF> and NO<INF>X</INF> in the SJV, 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.\128\ CARB 
further discusses its current mobile source control program and 
additional mobile source measures in the Valley State SIP Strategy. 
Appendix D of the 2018 PM<INF>2.5</INF> 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 SJV.\129\ Based on these analyses, CARB 
concludes that all best available control measures for mobile sources 
are in place in the SJV for NO<INF>X</INF> and directly emitted 
PM<INF>2.5</INF> for purposes of meeting the BACM/BACT requirement for 
the 2012 annual PM<INF>2.5</INF> NAAQS.
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    \128\ Id. at App. D, Ch. II.
    \129\ Id. at App. D, D-127 and D-128.

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[[Page 74325]]

3. EPA Evaluation and Proposed Action
    The first step in determining BACM is to develop a comprehensive 
emissions inventory of the sources of direct PM<INF>2.5</INF> and 
relevant PM<INF>2.5</INF> precursors that can be used with modeling to 
determine the effects of these sources on ambient PM<INF>2.5</INF> 
levels. Based on our review of the emission inventories provided in 
Appendix B of the 2018 PM<INF>2.5</INF> Plan and the State's and 
District's identification of the sources subject to control in Appendix 
C and Appendix D, the EPA proposes to find that the Plan appropriately 
identifies all sources of direct PM<INF>2.5</INF> and NO<INF>X</INF> 
that are subject to evaluation for potential control consistent with 
the requirements of subpart 4 of part D, title I of the Act.
    The remaining steps are to identify potential control measures for 
each source category, determine whether available control measures or 
technologies are technologically and economically feasible for 
implementation in the area, and determine the earliest date by which 
those control measures or technologies found to be feasible can be 
implemented, in whole or in part.\130\
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    \130\ 81 FR 58010, 58083-58085. The EPA's recommended steps for 
a BACM demonstration are substantively similar to the required steps 
for an MSM demonstration in 40 CFR 51.1010(b).
---------------------------------------------------------------------------

    We provide an evaluation of many of the District's control measures 
for stationary sources and area sources in section III of the EPA's 
``Technical Support Document, EPA Evaluation, San Joaquin Valley 
Serious Area Plan for the 2012 Annual PM<INF>2.5</INF> NAAQS,'' 
December 2021 (``EPA's 2012 Annual PM<INF>2.5</INF> TSD'').
    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<INF>2.5</INF> 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.\131\
---------------------------------------------------------------------------

    \131\ 2018 PM<INF>2.5</INF> Plan, App. D, Table 17.
---------------------------------------------------------------------------

    Appendix D of the 2018 PM<INF>2.5</INF> Plan describes the current 
efforts of the eight local jurisdiction MPOs to implement cost-
effective TCMs in the SJV.\132\ TCMs are projects that reduce air 
pollutants from transportation sources by reducing vehicle use, traffic 
congestion, or vehicle miles traveled. The eight MPOs in the SJV 
currently implement TCMs 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<INF>2.5</INF> NAAQS, 
provides a standardized process for distributing 20% 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.\133\ 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 SJV.\134\
---------------------------------------------------------------------------

    \132\ Id. at App. D, D-127 and D-128.
    \133\ Id. at App. D, D-127.
    \134\ Id. and SJVUAPCD, ``2016 Ozone Plan for 2008 8-Hour Ozone 
Standard'' (adopted June 16, 2016), App. D, Attachment D, tables D-
10 to D-17.
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    We have reviewed the State's and District's analysis and 
determination in the SJV PM<INF>2.5</INF> Plan that their baseline 
mobile, stationary, and area source control measures meet the 
requirements for BACM for sources of direct PM<INF>2.5</INF> and 
applicable PM<INF>2.5</INF> plan precursors (i.e., NO<INF>X</INF>) for 
purposes of the 2012 annual PM<INF>2.5</INF> 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 24-hour PM<INF>2.5</INF> NAAQS.\135\ We 
conclude that the evaluation processes followed by CARB and the 
District in the SJV PM<INF>2.5</INF> Plan to identify potential BACM 
were generally consistent with the requirements of the PM<INF>2.5</INF> 
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 the eight MPOs are 
implementing all reasonable TCMs in the SJV and propose to find that 
these TCMs implement BACM for transportation sources.
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    \135\ 85 FR 44192. The EPA provides a more detailed evaluation 
of many of the District's control measures for stationary and area 
sources in two supporting documents: The EPA's ``Technical Support 
Document, EPA Evaluation of BACM/MSM, San Joaquin Valley 
PM<INF>2.5</INF> Plan for the 2006 PM<INF>2.5</INF> NAAQS,'' 
February 2020; and the EPA's ``Response to Comments Document for the 
EPA's Final Action on the San Joaquin Valley Serious Area Plan for 
the 2006 PM<INF>2.5</INF> NAAQS,'' June 2020.
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    For the foregoing reasons, we propose to find that the SJV 
PM<INF>2.5</INF> Plan provides for the implementation of BACM for 
sources of direct PM<INF>2.5</INF> and NO<INF>X</INF> as expeditiously 
as practicable in accordance with the requirements of CAA section 
189(b)(1)(B), and in satisfaction of the Serious area plan requirements 
for the 2012 annual PM<INF>2.5</INF> NAAQS.

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

    Section 189(e) of the CAA specifically requires that the control 
requirements applicable to major stationary sources of direct 
PM<INF>2.5</INF> also apply to major stationary sources of 
PM<INF>2.5</INF> precursors, except where the Administrator determines 
that such sources do not contribute significantly to PM<INF>2.5</INF> 
levels that exceed the standards in the area.\136\ The control 
requirements applicable to major stationary sources of direct 
PM<INF>2.5</INF> in a Serious PM<INF>2.5</INF> nonattainment area 
include, at minimum, the requirements of a nonattainment NSR permit 
program meeting the requirements of CAA sections 172(c)(5) and 
189(b)(3). The publication of our final action to reclassify the SJV 
area as Serious nonattainment for the 2012 annual PM<INF>2.5</INF> 
NAAQS established a deadline of June 27, 2023, for the State to submit 
nonattainment NSR SIP revisions addressing the requirements of CAA 
sections 189(b)(3) and 189(e) of the Act for the 2012 annual 
PM<INF>2.5</INF> NAAQS.\137\
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    \136\ General Preamble, 13539 and 13541-13542.
    \137\ 86 FR 67343, 67347.
---------------------------------------------------------------------------

    California submitted nonattainment NSR SIP revisions to address the 
subpart 4 requirements for the Serious area attainment plan for SJV on 
November 20, 2019.\138\ We will act on that submission through a 
separate rulemaking, as appropriate.
---------------------------------------------------------------------------

    \138\ Letter dated November 15, 2019, from Richard W. Corey, 
Executive Officer, CARB, to Michael Stoker, Regional Administrator, 
EPA Region IX.
---------------------------------------------------------------------------

F. Attainment Demonstration

1. Requirements for Attainment Demonstration
    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 relevant PM<INF>2.5</INF> NAAQS by 
the applicable attainment date. The PM<INF>2.5</INF> SIP Requirements 
Rule explains that Serious area attainment plans under CAA sections 
189(b) must include a demonstration (including air quality modeling) 
that the control

[[Page 74326]]

strategy provides for attainment of the PM<INF>2.5</INF> NAAQS as 
expeditiously as practicable.\139\ 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 determined to be RACM, RACT, and 
additional reasonable measures, and BACM, BACT, and additional feasible 
measures), and any other emissions controls that are needed for 
expeditious attainment of the NAAQS.\140\ The regulatory requirements 
for Serious area plans are codified at 40 CFR 51.1010 (control strategy 
requirements) and 40 CFR 51.1011(b) (attainment demonstration and 
modeling requirements).
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    \139\ 40 CFR 51.1011(b)(1); 81 FR 58010, 58087-58088.
    \140\ 40 CFR 51.1010(a); 81 FR 58010, 58089-58090.
---------------------------------------------------------------------------

2. Summary of State's Submission
    The SJV PM<INF>2.5</INF> Plan includes a modeled demonstration 
projecting attainment of the 2012 annual PM<INF>2.5</INF> NAAQS in the 
SJV by December 31, 2025, based on emission reductions from 
implementation of baseline control measures and the development, 
adoption, and implementation of additional control measures to meet 
specific enforceable commitments. We have summarized the State's air 
quality modeling for demonstrating attainment in section IV.C.2 of this 
proposed rule. Table 3 shows the 2013 base year and 2025 projected 
future year annual PM<INF>2.5</INF> design values at monitoring sites 
in the SJV. 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 (for 2010-2012, 2011-2013, and 2012-2014), to 
minimize the influence of year-to-year variability. The highest 2025 
projected design value is 12.0 [mu]g/m\3\ at the Bakersfield-Planz and 
Madera monitoring sites, consistent with demonstrating attainment of 
the 12.0 [mu]g/m\3\ level of the 2012 annual PM<INF>2.5</INF> 
NAAQS.\141\
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    \141\ As discussed in section IV.B.3.a of this proposed rule, 
the State notes that Madera concentrations are biased high. 2018 
PM<INF>2.5</INF> Plan, App. G, 14.

  Table 3--Base Year and Projected Attainment Year Annual PM2.5 Design
          Values at Monitoring Sites in the San Joaquin Valley
------------------------------------------------------------------------
                                      2013 Base design   2025 Projected
           Monitoring site              value ([mu]g/     design value
                                            m\3\)         ([mu]g/m\3\)
------------------------------------------------------------------------
Bakersfield-Planz...................              17.2              12.0
Madera..............................              16.9              12.0
Hanford.............................              16.5              10.5
Visalia.............................              16.2              11.5
Clovis..............................              16.1              11.4
Bakersfield-California..............              16.0              11.0
Fresno-Garland......................              15.0              10.4
Turlock.............................              14.9              11.1
Fresno-Hamilton & Winery............              14.2              10.0
Stockton............................              13.1              10.6
Merced-S. Coffee....................              13.1               9.6
Modesto.............................              13.0               9.9
Merced-M Street.....................              11.0               8.6
Manteca.............................              10.1               8.0
Tranquility.........................               7.7               5.5
------------------------------------------------------------------------
Source: 2018 PM2.5 Plan, Table 7-3.

    The SJV PM<INF>2.5</INF> Plan's control strategy to reduce 
emissions from sources of NO<INF>X</INF> and direct PM<INF>2.5</INF> is 
presented in Chapter 4 (``Attainment Strategy for PM<INF>2.5</INF>'') 
\142\ and related supporting information in the Plan's control strategy 
appendices, including Appendix C (``Stationary Source Control Measure 
Analyses''), Appendix D (``Mobile Source Control Measures Analyses''), 
and Appendix E (``Incentive-Based Strategy''). Most of the projected 
emission reductions are achieved by baseline measures--i.e., the 
combination of State and District measures adopted prior to the State's 
and District's adoption of the Plan--that will achieve ongoing emission 
reductions from the 2013 base year to the 2025 projected attainment 
year.
---------------------------------------------------------------------------

    \142\ Consistent with the State and District's determination 
that ammonia, SO<INF>X</INF>, and VOC do not contribute 
significantly to PM<INF>2.5</INF> levels exceeding the NAAQS in the 
SJV, the Plan's control strategy focuses on reductions in emissions 
of direct PM<INF>2.5</INF> and NO<INF>X</INF>. CARB Staff Report, 
12. Nonetheless, the Plan projects the following annual average 
emission reductions from the 2013 base year to 2025: 0.5 tpd 
reductions in SO<INF>X</INF> (5.9%), 30.0 tpd reductions in VOC 
(9.3%), and 4.9 tpd reductions in ammonia (1.5%). 2018 
PM<INF>2.5</INF> Plan, App. B, tables B-3, B-4, and B-5.
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    The remainder of the emission reductions are to be achieved by 
additional measures to meet enforceable commitments, including 
potential regulatory and incentive-based measures and, as necessary, 
substitute measures.\143\ In the Valley State SIP Strategy and the 2018 
PM<INF>2.5</INF> Plan, CARB and the District, respectively, included 
commitments to take action on specific measures by specific years or to 
develop substitute measures (referred to as ``control measure 
commitments'') and to achieve specified amounts of NO<INF>X</INF> and 
direct PM<INF>2.5</INF> emission reductions by certain dates (referred 
to as ``aggregate tonnage commitments'').\144\ We refer to these 
complementary commitments herein as ``aggregate commitments.''
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    \143\ In this proposed rule, the term ``substitute measures'' 
means additional control measures that were not identified in CARB 
and the District's original control measure commitments in adopting 
the Valley State SIP Strategy and the 2018 PM<INF>2.5</INF> Plan, 
respectively. The ``substitute'' aspect primarily relates to 
emission reductions (i.e., providing emission reductions where any 
adopted measure achieves less emission reductions than originally 
estimated, and/or providing emission reductions in lieu of any 
originally planned measure that is not adopted). They are also 
sometimes referred to as ``alternative measures'' in the SJV 
PM<INF>2.5</INF> Plan and adopting resolutions.
    \144\ CARB Resolution 18-49 and SJVUAPCD Governing Board 
Resolution 18-11-16, paragraph 6.

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[[Page 74327]]

    CARB's control measure commitments include 12 regulatory measures 
and 3 incentive-based measures with implementation anticipated to start 
no later than 2024.\145\ The District's control measure commitments 
include nine regulatory measures and three incentive-based measures 
with implementation anticipated to start no later than 2024.\146\ We 
provide further detail on CARB and the District's control measure 
commitments both in sections IV.F.3.b and IV.F.3.c of this proposed 
rule and in section IV.A of the EPA's 2012 Annual PM<INF>2.5</INF> TSD.
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    \145\ Valley State SIP Strategy, Table 7. The schedule of 
proposed SIP measures in Table 7 includes two additional CARB 
measures: The second phase of the Advanced Clean Cars Program (``ACC 
2'') and the ``Cleaner In-Use Agricultural Equipment'' measures. 
However, these measures are not scheduled for implementation until 
2026 and 2030, respectively, which is after the January 1, 2025 
implementation deadline under 40 CFR 51.1011(b)(5) for control 
measures necessary for attainment by December 31, 2025. Therefore, 
we are not reviewing these measures as part of the control strategy 
to attain the 2012 annual PM<INF>2.5</INF> NAAQS in the SJV.
    \146\ 2018 PM<INF>2.5</INF> Plan, Ch. 4, tables 4-3 and 4-5.
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    CARB's aggregate tonnage commitments are ``to achieve the aggregate 
emissions reductions outlined in the Valley State SIP Strategy of 32 
tpd of NO<INF>X</INF> and 0.9 tpd of PM<INF>2.5</INF> emissions 
reductions in the San Joaquin Valley by 2024 and 2025.'' \147\ The 
Valley State SIP Strategy explains that CARB's overall commitment is to 
``achieve the total emission reductions necessary to attain the federal 
air quality standards, reflecting the combined reductions from the 
existing control strategy and new measures'' and that ``if a particular 
measure does not get its expected emissions reductions, the State is 
still committed to achieving the total aggregate emission reductions.'' 
\148\
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    \147\ CARB Resolution 18-49.
    \148\ 2018 PM<INF>2.5</INF> Plan, Ch. 4, 4-29.
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    The District's aggregate tonnage commitments are to ``achieve the 
aggregate emissions reductions of 1.88 tpd of NO<INF>X</INF> and 1.3 
tpd of PM<INF>2.5</INF> by 2024/2025'' through adoption and 
implementation of these measures or, if the total emission reductions 
from these rules or measures are less than these amounts, ``to adopt, 
submit, and implement substitute rules and measures that achieve 
equivalent reductions in emissions of direct PM<INF>2.5</INF> or 
PM<INF>2.5</INF> precursors'' in the same implementation 
timeframes.\149\
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    \149\ SJVUAPCD Governing Board Resolution 18-11-16, paragraph 6.
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    CARB and the District's aggregate tonnage commitments sum to 33.88 
tpd NO<INF>X</INF> and 2.2 tpd direct PM<INF>2.5</INF> emission 
reductions. We provide further detail on CARB and the District's 
aggregate tonnage commitments in sections IV.F.3.b and IV.F.3.d of this 
proposed rule and in section IV.B of the EPA's 2012 Annual 
PM<INF>2.5</INF> TSD.
    We note that the SJV PM<INF>2.5</INF> Plan generally relies on 
annual average emission inventory and control strategy estimates, 
consistent with the annual average form of the 2012 annual 
PM<INF>2.5</INF> NAAQS. Table 4 provides a summary of the 2013 base 
year emissions and the reductions from baseline measures, additional 
State measures, and additional District measures that the Plan projects 
will result in attainment of the 2012 annual PM<INF>2.5</INF> NAAQS in 
the SJV by December 31, 2025.\150\
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    \150\ Emission reductions from baseline measures are calculated 
as the sum of all stationary, area, and mobile source emission 
reductions from 2013 to 2025 in App. B of the 2018 PM<INF>2.5</INF> 
Plan.

   Table 4--Summary of the SJV PM2.5 Plan's Annual Average Emission Reductions To Attain the 2012 Annual PM2.5
                                           NAAQS by December 31, 2025
----------------------------------------------------------------------------------------------------------------
                                                                                                    % of 2013-
                                                                  % of 2013 base   Direct PM2.5      base year
                                                     NOX (tpd)       year NOX          (tpd)           PM2.5
                                                                     emissions                       emissions
----------------------------------------------------------------------------------------------------------------
A....................  2013 Base Year Emissions.           317.2  ..............            62.5  ..............
B....................  Baseline Measure Emission           173.5            54.7             4.2             6.7
                        Reductions (2013-2025).
C....................  Additional CARB Measures.              32            10.1             0.9             1.4
D....................  Additional District                  1.88             0.6             1.3             2.1
                        Measures.
E....................  Total 2013-2025 Emission           207.38            65.4             6.4            10.2
                        Reductions (B+C+D).
----------------------------------------------------------------------------------------------------------------
Source: 2018 PM2.5 Plan, Appendix B, tables B-1 and B-2, and Ch. 4, tables 4-3 and 4-7.

3. EPA Evaluation and Proposed Action
    The EPA must make several findings in order to approve the modeled 
attainment demonstration in an attainment plan SIP submission. First, 
we must find that the attainment demonstration's technical bases, 
including the emissions inventories and air quality modeling, are 
adequate. As discussed in section IV.A of this proposed rule, the EPA 
proposes to approve the emissions inventories on which the State based 
the SJV PM<INF>2.5</INF> Plan's attainment demonstration and related 
provisions. Furthermore, as discussed in section IV.C of this proposed 
rule, the EPA has evaluated the State's choice of model and the 
extensive discussion in the Modeling Protocol about modeling 
procedures, tests, and performance analyses. We consider the analyses 
consistent with the EPA's guidance on modeling for PM<INF>2.5</INF> 
attainment planning purposes. Based on these reviews, we propose to 
find that the modeling in the Plan is adequate for the purposes of 
supporting the RFP demonstration and demonstration of attainment by 
2025, and thus propose to approve the air quality modeling. For further 
detail, see the EPA's February 2020 Modeling TSD.
    Second, we must find that the attainment plan SIP submission 
provides for expeditious attainment through the timely implementation 
of the control strategy, including RACM, BACM, and any other emission 
controls that are needed for expeditious attainment. In the EPA's final 
rule on the SJV Moderate area plan for the 2012 annual PM<INF>2.5</INF> 
NAAQS, the EPA approved the State's demonstration of RACM (including 
RACT) and additional reasonable measures for all sources of direct 
PM<INF>2.5</INF> and NO<INF>X</INF>, under CAA section 189(a)(1)(C) and 
40 CFR 51.1009 for purposes of the 2012 annual PM<INF>2.5</INF> 
NAAQS.\151\ As discussed in section IV.C of this proposed rule, the EPA 
now proposes to approve the SJV PM<INF>2.5</INF> Plan's demonstration 
of BACM (including BACT) under CAA section 189(b)(1)(B).
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    \151\ Our approval of the State's demonstration of RACM and 
additional reasonable measures was informed by the State's control 
stringency demonstrations in both the Moderate area plan (2016 
PM<INF>2.5</INF> Plan) and the Serious area plan (2018 
PM<INF>2.5</INF> Plan) for the 2012 annual PM<INF>2.5</INF> NAAQS in 
the SJV. 86 FR 49100, 49115-49116.
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    Third, the EPA must find that the emissions reductions that are 
relied on

[[Page 74328]]

for attainment in the SIP submission are creditable. As discussed in 
subsections IV.F.3.a through IV.F.3.e of this proposed rule, the SJV 
PM<INF>2.5</INF> Plan relies principally on already adopted and 
approved rules to achieve the emissions reductions needed to attain the 
2012 annual PM<INF>2.5</INF> NAAQS in the SJV by December 31, 2025. The 
balance of the reductions that the State has modeled to achieve 
attainment by this date is currently represented by enforceable 
commitments that account for 13.8% of the NO<INF>X</INF> and 8.0% of 
the direct PM<INF>2.5</INF> emissions reductions needed for attainment.
    The EPA may accept enforceable commitments in lieu of adopted 
control measures in attainment demonstrations when the circumstances 
warrant it and the commitments meet three criteria the EPA has 
established for this purpose. The EPA is proposing to find that 
circumstances here warrant the consideration of enforceable commitments 
and that the three criteria are met: (1) The commitments constitute a 
limited portion of the required emissions reductions, (2) both the 
State and the District have demonstrated their capability to meet their 
commitments, and (3) the commitments are for an appropriate timeframe. 
We therefore propose to approve the State's reliance on these 
enforceable commitments in its attainment demonstration.
    Based on these evaluations, we propose to determine that the SJV 
PM<INF>2.5</INF> Plan provides for attainment of the 2012 annual 
PM<INF>2.5</INF> NAAQS by December 31, 2025, consistent with the 
requirements of CAA sections 189(b)(1)(A). We present the basis for 
this proposed determination in subsections IV.F.3.a through IV.F.3.e of 
this proposal and provide further detail of our evaluation of baseline 
measures and the additional measures and aggregate commitments in 
sections II and IV, respectively, of the EPA's 2012 Annual 
PM<INF>2.5</INF> TSD. In the following subsections we first address the 
baseline measures that are in effect in the SJV; we then describe the 
control measure and aggregate tonnage commitments submitted with the 
Plan; next, we evaluate progress that the State and District have made 
since submission of the Plan, on both the control measures and the 
aggregate tonnage commitments; finally we apply the three-factor test 
for reliance on enforceable commitments to demonstrate attainment.
(a) Baseline Measures
    Baseline measures will provide the majority of emissions reductions 
needed to attain the 2012 annual PM<INF>2.5</INF> NAAQS in the SJV, 
amounting to approximately 83.7% of the total NO<INF>X</INF> emission 
reductions and 65.6% of the total direct PM<INF>2.5</INF> emission 
reductions necessary to attain.\152\
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    \152\ The EPA calculated these percentages as follows: Annual 
average baseline NO<INF>X</INF> reductions from 2013 to 2025 are 
173.5 tpd of 207.38 tpd modeled to result in attainment (83.7%) and 
annual average baseline direct PM<INF>2.5</INF> reductions are 4.1 
tpd of 6.3 tpd modeled to result in attainment (65.1%). 2018 
PM<INF>2.5</INF> Plan, Ch. 4 and App. B.
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    In the 2018 PM<INF>2.5</INF> Plan, the State explains that mobile 
sources emit over 85% of the NO<INF>X</INF> in the SJV and that CARB 
has adopted and amended regulations to reduce public exposure to diesel 
particulate matter, which includes direct PM<INF>2.5</INF>, and 
NO<INF>X</INF>, 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.'' 
\153\
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    \153\ 2018 PM<INF>2.5</INF> Plan, Ch. 4, 4-9 and Valley State 
SIP Strategy, 4. For CARB's analysis of its mobile source measures 
for BACM and MSM, see 2018 PM<INF>2.5</INF> Plan, App. D, including 
analyses for on-road light-duty vehicles and fuels (starting page D-
17), on-road heavy-duty vehicles and fuels (starting page D-35), and 
non-road sources (starting page D-64).
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    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 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 multiple mobile source 
regulations for which waivers or authorizations have been issued as 
revisions to the California SIP.\154\
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    \154\ See, e.g., 81 FR 39424, 82 FR 14447, and 83 FR 23232.
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    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.\155\
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    \155\ See, e.g., 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), and revisions to the California 
on-road reformulated gasoline and diesel fuel regulations, 75 FR 
26653 (May 12, 2010).
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    As to stationary sources, in the 2018 PM<INF>2.5</INF> Plan, the 
State explains that stringent regulations adopted for prior attainment 
plans continue to reduce emissions of NO<INF>X</INF> and direct 
PM<INF>2.5</INF>.\156\ Specifically, Table 4-1 of the 2018 
PM<INF>2.5</INF> Plan (``District Rules Reducing PM and NO<INF>X</INF> 
Emissions in the Valley'') identifies 33 District measures that limit 
NO<INF>X</INF> and direct PM<INF>2.5</INF> emissions.\157\ The EPA has 
approved each of the identified measures into the California SIP,\158\ 
with two exceptions.
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    \156\ 2018 PM<INF>2.5</INF> Plan, Ch. 4, 4-3. For the District's 
analysis of its stationary source measures for BACM and MSM, see 
2018 PM<INF>2.5</INF> Plan, App. C.
    \157\ Id. at Ch. 4, Table 4-1.
    \158\ See EPA Region IX's website for information on District 
control measures that have been approved into the California SIP, 
available at: <a href="https://www.epa.gov/sips-ca/epa-approved-san-joaquin-valley-unified-air-district-regulations-california-sip">https://www.epa.gov/sips-ca/epa-approved-san-joaquin-valley-unified-air-district-regulations-california-sip</a>.
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    First, the District amended Rule 4905 (``Natural Gas-fired, Fan-
type, Residential Central Furnaces'') on June 21, 2018, to extend the 
period during which manufacturers may pay emission fees in lieu of 
meeting the rule's NO<INF>X</INF> emission limits.\159\ CARB submitted 
the amended rule to the EPA on November 21, 2018. However, the District 
amended Rule 4905 once more on October 15, 2020, to further extend the 
period during which manufacturers of weatherized furnaces may pay 
emission fees in lieu of meeting the rule's NO<INF>X</INF> emission 
limits.\160\ CARB submitted the rule as amended October 15, 2020, to 
the EPA on December 30, 2020, and simultaneously withdrew the rule as 
amended June 21, 2018.\161\ The EPA has not yet proposed any action on 
this submission.
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    \159\ SJVUAPCD, Final Draft Staff Report, ``Proposed Amendments 
to Rule 4905 (Natural Gas-fired, Fan-type Central Furnaces),'' 2.
    \160\ SJVUAPCD, ``Item Number X: Adopt Proposed Amendments to 
Rule 4905 (Natural Gas-Fired, Fan-Type Furnaces),'' October 15, 
2020, 3, including Final Draft Staff Report, ``Proposed Amendments 
to Rule 4905 (Natural Gas-Fired, Fan-Type Furnaces).''
    \161\ Letter dated December 28, 2020, from Richard W. Corey, 
Executive Officer, CARB, to John Busterud, Regional Administrator, 
EPA Region IX.
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    The EPA approved a prior version of Rule 4905 into the California 
SIP on March 29, 2016.\162\ 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 emission limits, emission reductions associated with 
the rule's emission limits would not be creditable in any attainment 
plan without additional documentation.\163\ Until the District submits 
the necessary documentation to credit emission reductions achieved by 
Rule 4905

[[Page 74329]]

toward an attainment control strategy, this rule is not creditable for 
SIP purposes. The 2018 PM<INF>2.5</INF> Plan indicates that the 
District attributed annual average emission reductions of 0.31 tpd 
NO<INF>X</INF> between 2013 and 2025 to Rule 4905.\164\ These emission 
reductions would not materially affect the attainment demonstration in 
the SJV PM<INF>2.5</INF> Plan.
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    \162\ 81 FR 17390 (March 29, 2016) (approving Rule 4905 as 
amended January 22, 2015).
    \163\ EPA Region IX, ``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.
    \164\ 2018 PM<INF>2.5</INF> Plan, App. C, C-290.
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    Second, the 2018 PM<INF>2.5</INF> 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.\165\ Appendix C of the 2018 PM<INF>2.5</INF> Plan 
indicates, however, that the emissions inventory for incineration of 
combustible refuse is 0.00 tpd of NO<INF>X</INF> and 0.00 tpd direct 
PM<INF>2.5</INF> from 2013 through 2025.\166\ 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<INF>2.5</INF> Plan.
---------------------------------------------------------------------------

    \165\ The EPA does not have any pending SIP submission for Rule 
4203.
    \166\ 2018 PM<INF>2.5</INF> Plan, App. C, C-46.
---------------------------------------------------------------------------

    In sum, although Table 4-1 of the 2018 PM<INF>2.5</INF> Plan 
identifies two baseline measures that are not creditable for SIP 
purposes at this time, we conclude that the total emission reductions 
attributed to these two measures in the future baseline inventories 
would not materially affect the attainment demonstration in the Plan.
(b) Additional Measures and Aggregate Commitments
    The SJV PM<INF>2.5</INF> Plan identifies a series of additional 
CARB and District commitments to achieve emission reductions through 
additional control measures beyond baseline measures that will 
contribute to expeditious attainment of the 2012 annual 
PM<INF>2.5</INF> NAAQS. As discussed in section IV.F.2 of this proposed 
rule, for mobile sources, CARB's commitment identifies a list of 12 
State regulatory measures and 3 incentive-based measures that CARB has 
committed to propose to its Board for consideration by specific 
years.\167\ For stationary sources, the District's commitment 
identifies a list of nine regulatory measures and three incentive-based 
measures that the District has committed to propose to its Board for 
consideration by specific years.\168\ The Plan contains CARB and the 
District's estimates of the emission reductions that would be achieved 
by each of these additional measures, if adopted.\169\
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    \167\ CARB Resolution 18-49, Attachment A and Valley State SIP 
Strategy, Table 7 (``State Measures and Schedule for the San Joaquin 
Valley'').
    \168\ SJVUAPCD Governing Board Resolution 18-11-16 and 2018 
PM<INF>2.5</INF> Plan, Table 4-4 (``Proposed Regulatory Measures'') 
and Table 4-5 (``Proposed Incentive-Based Measures'').
    \169\ 2018 PM<INF>2.5</INF> Plan, Ch. 4, Table 4-3 (''Emission 
Reductions from District Measures'') and Table 4-9 (''San Joaquin 
Valley Expected Emission Reductions from State Measures'') and 
Valley State SIP Strategy, Table 8 (``San Joaquin Valley Expected 
Emission Reductions from State Measures'').
---------------------------------------------------------------------------

    CARB's commitments are contained in CARB Resolution 18-49 (October 
25, 2018) and the Valley State SIP Strategy and consist of two parts: A 
control measure commitment and a tonnage commitment. First, CARB has 
committed to ``begin the measure's public process and bring to the 
Board for consideration the list of proposed SIP measures outlined in 
the Valley State SIP Strategy and included in Attachment A, according 
to the schedule set forth.'' \170\ By email dated November 12, 2019, 
CARB confirmed that it intended to begin the public process on each 
measure by discussing the proposed regulation or program at a public 
meeting (workshop, working group, or Board hearing) or in a publicly-
released document and to then propose the regulation or program to its 
Board.\171\ Second, CARB has committed ``to achieve the aggregate 
emissions reductions outlined in the Valley State SIP Strategy of 32 
tpd of NO<INF>X</INF> and 0.9 tpd of PM<INF>2.5</INF> emissions 
reductions in the San Joaquin Valley by 2024 and 2025.'' \172\ The 
Valley State SIP Strategy explains that CARB's overall commitment is to 
``achieve the total emission reductions necessary to attain the federal 
air quality standards, reflecting the combined reductions from the 
existing control strategy and new measures'' and that ``if a particular 
measure does not get its expected emissions reductions, the State is 
still committed to achieving the total aggregate emission reductions.'' 
\173\
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    \170\ CARB Resolution 18-49, 5.
    \171\ Email dated November 12, 2019, from Sylvia Vanderspek, 
CARB to Anita Lee, EPA Region IX, ``RE: SJV PM<INF>2.5</INF> 
information'' (attaching ``Valley State SIP Strategy Progress'') and 
CARB Staff Report, 14.
    \172\ CARB Resolution 18-49, 5.
    \173\ Valley State SIP Strategy, 7.
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    The District's commitments are contained in SJVUAPCD Governing 
Board Resolution 18-11-16 (November 15, 2018) and Chapter 4 of the 2018 
PM<INF>2.5</INF> Plan and similarly consist of two parts: A control 
measure commitment and a tonnage commitment. First, the District has 
committed to ``take action on the rules and measures committed to in 
Chapter 4 of the Plan by the dates specified therein, and to submit 
these rules and measures, as appropriate, to CARB within 30 days of 
adoption for transmittal to EPA as a revision to the [SIP].'' \174\ By 
email dated November 12, 2019, the District confirmed that it intended 
to take action on the listed rules and measures by beginning the public 
process on each measure, i.e., discussing the proposed regulation or 
program at a public meeting, including a workshop, working group, or 
Board hearing, or in a publicly-released document, and then proposing 
the rule or measure to the SJVUAPCD Governing Board.\175\ Second, the 
District has committed to ``achieve the aggregate emissions reductions 
of 1.88 tpd of NO<INF>X</INF> and 1.3 tpd of PM<INF>2.5</INF> by 2024/
2025'' through adoption and implementation of these measures or, if the 
total emission reductions from these rules or measures are less than 
these amounts, ``to adopt, submit, and implement substitute rules and 
measures that achieve equivalent reductions in emissions of direct 
PM<INF>2.5</INF> or PM<INF>2.5</INF> precursors'' in the same 
implementation timeframes.\176\
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    \174\ SJVUAPCD Governing Board Resolution 18-11-16, 10-11.
    \175\ Email dated November 12, 2019, from Jon Klassen, SJVUAPCD 
to Wienke Tax, EPA Region IX, ``RE: follow up on aggregate 
commitments in SJV PM<INF>2.5</INF> plan'' (attaching ``District 
Progress in Implementing Commitments with 2018 PM<INF>2.5</INF> 
Plan'').
    \176\ SJVUAPCD Governing Board Resolution 18-11-16, 10-11.
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(c) Progress on Control Measure Commitments
    In October 2021, CARB and the District provided the ``Progress 
Report and Technical Submittal for the 2012 PM<INF>2.5</INF> Standard 
San Joaquin Valley'' (2021 Progress Report) to describe their progress 
to date in developing and adopting the additional measures identified 
in their control measure commitments. The 2021 Progress Report provides 
status updates on the substance of each measure and the timing of board 
consideration for both adopted and remaining control measure 
commitments.\177\ It also provides a side-by-side comparison of the 
original emission reduction estimates in the SJV PM<INF>2.5</INF> Plan 
for each control measure commitment and updated emission reduction 
estimates for each based on technical analyses for adopted measures and 
draft measures and/or

[[Page 74330]]

documentation in development for forthcoming regulations.\178\
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    \177\ ``Progress Report and Technical Submittal for the 2012 
PM<INF>2.5</INF> Standard San Joaquin Valley,'' October 19, 2021. 
Transmitted to the EPA by letter dated October 20, 2021, from 
Richard W. Corey, Executive Officer, CARB, to Deborah Jordan, Acting 
Regional Administrator, EPA Region IX. See sections of 2021 Progress 
Report entitled ``Progress in Implementing District Measures'' and 
``Progress in Implementing CARB Measures.''
    \178\ 2021 Progress Report, tables 2 and 3.
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    Together, as of December 2021, CARB and the District together have 
adopted 18 measures of the 27 control measure commitments in the SJV 
PM<INF>2.5</INF> Plan and have begun the public process on 5 of the 
remaining control measure commitments. For CARB's portion, CARB has 
adopted 10 of the 15 measures in its commitment (including one 
incentive-based measure) and begun the public process on 3 of its 
remaining 5 measures. The adopted measures include, for example, the 
Heavy-Duty Vehicle Inspection and Maintenance Program (``Heavy-Duty I/
M''), the California Heavy-Duty Low-NO<INF>X</INF> Engine Standard, the 
Small Off-Road Engines (SORE) regulation, and the Accelerated Turnover 
of Agricultural Equipment Incentive Projects (``Agricultural Equipment 
Incentive Measure''). For the District's portion of the control measure 
commitments, the District has adopted 8 of the 12 measures in its 
commitment (including one incentive-based measure) and begun the public 
process on two of the remaining four measures. The adopted measures 
include, for example, amendments to Rule 4311 (``Flares''), Rule 4702 
(``Internal Combustion Engines''), and Rule 4901 (``Woodburning 
Fireplaces and Wood Burning Heaters'') (Hot-spot strategy), and the 
Residential Wood Burning Devices Incentive Projects measure.
    Accordingly, the EPA considers that, although CARB and the District 
have not met the commitment deadlines for several measures, as 
discussed further in this proposed rule, they have nonetheless made 
substantial progress in developing and adopting the regulatory measures 
listed in their respective control measure commitments. We provide 
further detail on CARB and the District's control measure commitments 
in section IV.A of the EPA's 2012 Annual PM<INF>2.5</INF> TSD 
(including tables IV-A and IV-B regarding CARB and the District's 
control measure commitments, respectively).
    Regarding the remaining nine measures not yet proposed for board 
consideration, we note that one measure, Rule 4550 (``Conservation 
Management Practices''), has an action year of 2022 in the 2018 
PM<INF>2.5</INF> Plan (i.e., it is not yet due for board consideration) 
and that four regulatory measures and four incentive-based measures are 
overdue.
    The four overdue regulatory measures are: The Zero-Emission Airport 
Ground Support Equipment measure; the Zero-Emission Off-Road Forklift 
Regulation Phase 1 measure; the Low-emission Diesel Fuel Requirement; 
and Rule 4692 (``Commercial Under-fired Charbroiling (Hot-spot 
Strategy)''). While they have not proposed these measures to their 
respective boards, CARB and the District timely began the public 
process on each of the four measures. CARB anticipates board 
consideration of the diesel fuel measures in 2022 and the forklift 
measure as early as 2022 and continues to develop the airport ground 
support equipment measure. The District adopted the ``Commercial 
Underfired Charbroiling Emission Reduction Strategy'' on December 17, 
2020, and continues to evaluate potential amendments to Rule 4692 in 
the near future.\179\
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    \179\ Id. at 8-9, 20-22, and tables 2 and 3.
---------------------------------------------------------------------------

    The four overdue incentive-based control measures are for the 
Accelerated Turnover of Trucks and Buses Incentive Projects, the 
Accelerated Turnover of Off-road Equipment Incentive Projects, the 
Agricultural Operation Internal Combustion Engines Incentive Projects, 
and the Commercial Under-fired Charbroiling Incentive Projects. CARB 
and the District continue to invest in reducing emissions from these 
sources, as well as other incentive programs not named among the 27 
control measure commitments, such as those for nut harvesting and 
landscape maintenance equipment.\180\ However, while CARB and the 
District have discussed the proposed programs at certain board 
hearings,\181\ the EPA is not aware that CARB or the District have 
started public process for the four incentive-based control measure 
commitments as enforceable measures to be submitted for inclusion as 
control measures in the California SIP.
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    \180\ CARB, ``Long-Term Heavy-Duty Investment Strategy, 
Including Fiscal Year 2020-21 Three-Year Recommendations for Low 
Carbon Transportation Investments,'' (App. D to CARB's ``Proposed 
Fiscal Year 2021-22 Funding Plan for Clean Transportation 
Incentives''), release date October 8, 2021; and SJVUAPCD, 
``Comprehensive Annual Financial Report, Fiscal Year Ended June 30, 
2020,'' release date December 23, 2020. See also, 2021 Progress 
Report, 3 and 15.
    \181\ For example, CARB staff discussed the Accelerated Turnover 
of Trucks and Buses Incentive Measure at its annual 2020 update to 
the CARB Board. CARB presentation, ``Update on the 2018 
PM<INF>2.5</INF> SIP for the San Joaquin Valley,'' October 22, 2020. 
District staff discussed and adopted an emission reductions strategy 
for commercial under-fired charbroiling, including incentives, in 
December 2020. SJVUAPCD, ``Item Number 11: Adopt Proposed Commercial 
Under-Fired Charbroiling Emission Reduction Strategy,'' December 17, 
2020.
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    Notwithstanding being overdue in presenting these incentive-based 
measures for board consideration, CARB and the District state that they 
continue to assess and/or prepare the formal documentation for the 
emission reductions from such incentive-based measures that could be 
applied towards the aggregate tonnage commitments.\182\ For heavy-duty 
trucks and off-road equipment, CARB acknowledges that many of the 
project lives do not span the attainment year \183\ and, thus, while 
these projects accelerate emission reductions and benefit communities 
in the SJV, the projects that qualify for SIP credit may be limited for 
the purposes of the 2012 annual PM<INF>2.5</INF> NAAQS Serious area 
attainment demonstration. Overall, the EPA anticipates that emission 
reductions from such projects that qualify for SIP credit (``SIP-
creditable emission reductions'') may be smaller than originally 
anticipated in the SJV PM<INF>2.5</INF> Plan.
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    \182\ 2021 Progress Report, 15 and 24.
    \183\ Id. at 24 and 32. Generally, mobile source incentive 
projects implemented under the Carl Moyer program are under contract 
only during the ``project life'' and may not be credited with SIP 
emission reductions after the project life ends. EPA Region IX 
``Technical Support Document for EPA's Rulemaking for the California 
State Implementation Plan California Air Resources Board Resolution 
19-26 San Joaquin Valley Agricultural Equipment Incentive Measure,'' 
February 2020, 12-13.
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    CARB and the District point to certain measures that they 
anticipate will provide more emission reductions than the original 
emission reduction estimates (e.g., larger emission reductions from 
Heavy-Duty I/M due to new 2019 state law requirements and new roadside 
emissions monitoring) and the addition of the two substitute measures 
(the Agricultural Burning Phase-out Measure (adopted) and the In-Use 
Locomotive Measure (anticipated for CARB board consideration in 2022)) 
as compensating for incentive-based measures that may result in less 
emission reductions than originally projected.\184\ In its annual 
update to the Board on September 23, 2021, CARB staff explained that, 
in light of the progress to-date on committed-to regulatory measures 
and these two substitute measures, fewer incentive-based emission 
reductions would be needed to demonstrate attainment of the 2012 annual 
PM<INF>2.5</INF> NAAQS.\185\ We further discuss the role of adopted 
measures, measures not yet proposed for board consideration (including 
incentive-based measures), and the substitute measures in the following 
section of this proposed rule.
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    \184\ 2021 Progress Report, 30-31.
    \185\ CARB, ``Valley PM<INF>2.5</INF> Implementation Update and 
SIP Amendment,'' September 23, 2021, slides 22-25. Slide 25 
illustrates a large decrease in the expected funding need from 
approximately $5 billion over 2018-2025 to approximately $1 billion 
over 2021-2025.

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[[Page 74331]]

(d) Progress on Aggregate Tonnage Commitments
    As described in section IV.F.2 of this proposed rule, to attain the 
2012 annual PM<INF>2.5</INF> NAAQS in the SJV, CARB committed to 
achieve 32 tpd of NO<INF>X</INF> and 0.9 tpd of PM<INF>2.5</INF> 
emissions reductions, and the District committed to achieve 1.88 tpd of 
NO<INF>X</INF> and 1.3 tpd of PM<INF>2.5</INF> emissions reductions by 
2025. These aggregate tonnage commitments sum to 33.88 tpd 
NO<INF>X</INF> and 2.2 tpd direct PM<INF>2.5</INF>.
    As described in sections IV.F.3.b and IV.F.3.c of this proposed 
rule, CARB and the District have committed to achieve these reductions 
via the 27 control measure commitments, or such other substitute 
measures as may be necessary, to achieve the aggregate tonnage 
commitments for NO<INF>X</INF> and direct PM<INF>2.5</INF>. Because the 
State's efforts are ongoing, different control measures are at 
different stages of rule development, rule adoption, submission to the 
EPA, and EPA evaluation and rulemaking. For the purpose of our analysis 
of the State's progress toward achieving its aggregate tonnage 
commitments, we propose to credit reductions from rules that the EPA 
has approved into the SIP, or that EPA has proposed for approval into 
the SIP at the time of this notice. We begin by explaining these 
measures and summing the total reductions from such measures that can 
be credited to CARB and the District's aggregate commitments. For many 
remaining measures, although reductions are not formally SIP credited 
at this time, CARB and the District have made substantial progress 
toward achieving SIP approval, or otherwise advanced their analysis of 
the reductions they are likely to achieve in certain areas since the 
adoption of the Plan. Much of this progress is summarized in the 2021 
Progress Report. After detailing the creditable emission reductions 
achieved in approved rules and rules proposed for approval, we next 
address the State's progress on emission reductions from its remaining 
rule development efforts.
    Of the 18 measures adopted to date, as well as the adoption of an 
important substitute measure (the Agricultural Burning Phase-out 
Measure), the State has submitted 9 measures as revisions to the 
California SIP as of November 2021. The EPA has proposed or finalized 
action on four of these submitted measures, including three with large 
associated emission reductions of direct PM<INF>2.5</INF> and/or 
NO<INF>X</INF> in the SJV, as follows.\186\
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    \186\ The additional measures submitted as SIP revisions for 
which the EPA has not proposed action include: The Innovative Clean 
Transit measure (submitted February 13, 2020); Rules 4311, 4306, and 
4320 (submitted March 12, 2021); and Rule 4702 (submitted October 
15, 2021).
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    First, on July 22, 2020, the EPA published its final approval of 
the District's 2019 amendment to Rule 4901 \187\ and concurrently 
credited this measure with annual average emission reductions of 0.2 
tpd direct PM<INF>2.5</INF> towards the District's PM<INF>2.5</INF> 
tonnage commitment for 2024.\188\ As described in the EPA's March 27, 
2020 proposed rule, this amount of SIP credit corresponded to a 75% 
compliance rate (referred to as a ``rule effectiveness rate''), 
consistent with the EPA's guidance on wood burning curtailment 
programs,\189\ rather than a higher 100% rule effectiveness rate used 
in the District's original calculations.\190\ In the 2021 Progress 
Report, the State notes this conclusion in the EPA's July 22, 2020 
final rule approving this measure into the SIP and now estimates 
emission reductions of 0.2 tpd direct PM<INF>2.5</INF> from this 
measure.\191\ Consistent with the EPA's July 22, 2020 final rule, we 
propose to credit this measure with annual average emission reductions 
of 0.2 tpd direct PM<INF>2.5</INF> for 2025 (i.e., to subtract 0.2 tpd 
from the reductions of direct PM<INF>2.5</INF> emissions that the 
District is required to achieve with its PM<INF>2.5</INF> tonnage 
commitment).
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    \187\ 85 FR 44206.
    \188\ 85 FR 44192, 44204.
    \189\ ``Strategies for Reducing Wood Smoke,'' EPA-456/B-13-01, 
March 2013, 42.
    \190\ 85 FR 17382, 17415.
    \191\ 2021 Progress Report, 7 and Table 3.
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    Second, on March 24, 2020, the EPA published its proposal to 
approve the Agricultural Equipment Incentive Measure into the 
California SIP,\192\ including projects funded through the Carl Moyer 
Memorial Air Quality Standards Attainment Program (``Carl Moyer''), 
Funding Agricultural Replacement Measures for Emission Reductions 
(FARMER), and Natural Resources Conservation Service (NRCS) programs. 
The measure includes commitments by CARB to monitor, assess, and report 
on emission reductions, and to achieve emission reductions of 5.1 tpd 
NO<INF>X</INF> and 0.3 tpd direct PM<INF>2.5</INF> from the 2025 
baseline inventory in the 2018 PM<INF>2.5</INF> Plan by December 31, 
2024.\193\ The EPA finalized a partial approval of this measure on 
December 16, 2021, wherein the EPA credited 4.83 tpd NO<INF>X</INF> and 
0.24 tpd direct PM<INF>2.5</INF> towards CARB's tonnage commitments for 
2024 (for attaining the 2006 24-hour PM<INF>2.5</INF> NAAQS), and 
calculated 4.46 tpd NO<INF>X</INF> and 0.26 tpd direct PM<INF>2.5</INF> 
for 2025 (for attaining the 2012 annual PM<INF>2.5</INF> NAAQS).\194\
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    \192\ 85 FR 16588.
    \193\ EPA Region IX ``Technical Support Document for EPA's 
Rulemaking for the California State Implementation Plan California 
Air Resources Board Resolution 19-26 San Joaquin Valley Agricultural 
Equipment Incentive Measure,'' February 2020, 4-5, 24-25, and 31.
    \194\ EPA Region IX, ``Air Plan Approval; San Joaquin Valley 
Unified Air Pollution Control District,'' final rule signed December 
16, 2021. The EPA deferred action on the NRCS portion of the 
Agricultural Equipment Incentive Measure.
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    Under longstanding guidance, the EPA has recommended presumptive 
limits on the amounts of emission reductions from certain voluntary and 
other nontraditional measures that may be credited in a SIP. 
Specifically, for voluntary mobile source emission reduction programs, 
the EPA has identified a presumptive limit of 3% of the additional 
emission reductions (beyond reductions from baseline measures) required 
to attain the appropriate NAAQS, and for any particular SIP submittal 
to demonstrate attainment or maintenance of the NAAQS or progress 
toward attainment (RFP), 3% of the specific statutory requirement.\195\ 
The EPA may, however, approve measures for SIP credit in amounts 
exceeding the presumptive limits where a clear and convincing 
justification is made by the State as to why a higher limit should 
apply in a given case.\196\
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    \195\ EPA, ``Guidance on Incorporating Voluntary Mobile Source 
Emission Reduction Programs in State Implementation Plans (SIPs),'' 
October 24, 1997, 5.
    \196\ EPA, ``Incorporating Emerging and Voluntary Measures in a 
State Implementation Plan (SIP),'' October 4, 2004, 9; see also EPA, 
``Guidance on Incorporating Bundled Measures in a State 
Implementation Plan,'' August 16, 2005, 8, n.6, and EPA, ``Diesel 
Retrofit and Replacement Projects: Quantifying and Using Their 
Emission Benefits in SIPs and Conformity: Guidance for State and 
Local Air and Transportation Agencies,'' March 2018, 12.
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    According to the State, the SJV's topography and meteorology 
present significant challenges for air quality. As stated in the 2018 
PM<INF>2.5</INF> Plan, ``the surrounding mountains trap pollution and 
block airflow'' and ``[t]emperature inversions, while present to some 
degree throughout the year, can last for days during the winter, 
holding in nighttime accumulations of pollutants.'' \197\ In addition, 
the State notes that the population of the area continues to grow at a 
rate higher than the statewide growth rate, leading to increased 
vehicular traffic along major highways that run through the SJV.\198\ 
Given these unique challenges, both the State and District continue to 
implement both traditional and non-traditional emission reduction 
strategies to attain the PM<INF>2.5</INF> standards in the SJV,

[[Page 74332]]

including regulatory programs, incentive programs, and rigorous 
outreach and education efforts.\199\
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    \197\ 2018 PM<INF>2.5</INF> Plan, Ch. 2, 2-1.
    \198\ Id. at Ch. 2, 2-4.
    \199\ Id. at Ch. 2, 2-2.
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    Over the past several decades, the State and District have 
developed and implemented several comprehensive plans to address 
attainment of the NAAQS for ozone and particulate matter.\200\ These 
attainment plans have resulted in CARB and District's adoption of 
numerous regulations for stationary, area, and mobile sources, many of 
which are among the most stringent control measures in the nation. 
Given the air quality needs of the area, the numerous control measures 
that both the State and District have adopted and implemented in the 
San Joaquin Valley to date, the State's and District's successful 
implementation of the Carl Moyer program over the last two decades, and 
our experience to date quantifying emission reductions achieved through 
this program,\201\ we believe it is appropriate to allow the State to 
rely on the Agricultural Equipment Incentive Measure to achieve 13.2% 
(4.46 tpd) of the additional NO<INF>X</INF> reductions and 11.8% (0.26 
tpd) of the additional direct PM<INF>2.5</INF> reductions necessary for 
the area to attain the 2012 annual PM<INF>2.5</INF> NAAQS by the end of 
2025.\202\ Moreover, all Carl Moyer and FARMER projects are subject to 
detailed contract provisions that CARB may enforce against the grantee 
at any time during the contract term, a program feature that further 
supports the State's reliance on the Agricultural Equipment Incentive 
Measure for emission reductions exceeding the EPA's presumptive 
limits.\203\
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    \200\ See, e.g., 69 FR 30005 (May 26, 2004) (approving plan to 
attain the 1987 

[…truncated; see source link]
Indexed from Federal Register on December 29, 2021.

This is legal information, not legal advice. Laws vary by jurisdiction and change frequently. Always verify current law with official sources and consult a licensed attorney in your jurisdiction for advice on your specific situation.