[Federal Register Volume 80, Number 202 (Tuesday, October 20, 2015)]
[Proposed Rules]
[Pages 63639-63662]
[FR Doc No: 2015-26315]

Vol. 80

Tuesday,

No. 202

October 20, 2015

Part II

Environmental Protection Agency

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40 CFR Parts 52 and 81

Approval and Promulgation of Implementation Plans; Designation of Areas
for Air Quality Planning Purposes; California; South Coast Moderate
Area Plan and Reclassification as Serious Nonattainment for the 2006
PM2.5 NAAQS; Proposed Rule

Federal Register / Vol. 80 , No. 202 / Tuesday, October 20, 2015 /
Proposed Rules

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 52 and 81

[EPA-R09-OAR-2015-0204; FRL-9935-61-Region 9]

Approval and Promulgation of Implementation Plans; Designation of
Areas for Air Quality Planning Purposes; California; South Coast
Moderate Area Plan and Reclassification as Serious Nonattainment for
the 2006 PM2.5 NAAQS

AGENCY: U.S. Environmental Protection Agency.

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to
approve state implementation plan (SIP) revisions submitted by
California to address Clean Air Act (CAA or Act) requirements for the
2006 24-hour fine particulate matter (PM2.5) national
ambient air quality standards (NAAQS) in the Los Angeles-South Coast
Air Basin (South Coast) Moderate PM2.5 nonattainment area.
These SIP revisions are the 2012 PM2.5 Plan, submitted
February 13, 2013, and the 2015 Supplement, submitted March 4, 2015.
The EPA is also proposing to reclassify the South Coast
PM2.5 nonattainment area, including reservation areas of
Indian Country and any other area of Indian Country within it where the
EPA or a tribe has demonstrated that the tribe has jurisdiction, as a
Serious nonattainment area for the 2006 PM2.5 NAAQS based on
EPA's determination that the area cannot practicably attain this
standard by the applicable Moderate area attainment date of December
31, 2015. Upon final reclassification as a Serious area, California
will be required to submit a Serious area plan including a
demonstration that the plan provides for attainment of the 2006
PM2.5 NAAQS by the applicable Serious area attainment date,
which is no later than December 31, 2019, or by the most expeditious
alternative date practicable, in accordance with the requirements of
part D of Title I of the CAA.

DATES: Any comments must arrive by November 19, 2015.

ADDRESSES: Submit comments, identified by docket number EPA-R09-OAR-
2015-0204, by one of the following methods:
     Federal eRulemaking Portal: www.regulations.gov. Follow
the on-line instructions.
     Email<EMAIL_ADDRESS>     Mail or deliver: Wienke Tax, Office of Air Planning (AIR-
2), U.S. Environmental Protection Agency Region 9, 75 Hawthorne Street,
San Francisco, CA 94105.
    Instructions: All comments will be included in the public docket
without change and may be made available online at www.regulations.gov,
including any personal information provided, unless the comment
includes Confidential Business Information (CBI) or other information
whose disclosure is restricted by statute. Information that you
consider CBI or otherwise protected should be clearly identified as
such and should not be submitted through www.regulations.gov or email.
The www.regulations.gov Web site is an ``anonymous access'' system, and
the EPA will not know your identity or contact information unless you
provide it in the body of your comment. If you send email directly to
the EPA, your email address will be automatically captured and included
as part of the public comment. If the EPA cannot read your comments due
to technical difficulties and cannot contact you for clarification, the
EPA may not be able to consider your comment.
    Docket: The index to the docket (docket number EPA-R09-OAR-2015-
0204) for this proposed rule is available electronically on the
www.regulations.gov Web site and in hard copy at EPA Region 9, 75
Hawthorne Street, San Francisco, California 94105. While all documents
in the docket are listed in the index, some information may be publicly
available only at the hard copy location (e.g., copyrighted material),
and some may not be publicly available at either location (e.g., CBI).
To inspect the hard copy materials, please schedule an appointment
during normal business hours with the contact listed in the FOR FURTHER
INFORMATION CONTACT section below.

FOR FURTHER INFORMATION CONTACT: Wienke Tax, Air Planning Office (AIR-
2), U.S. Environmental Protection Agency, Region 9,<PHONE_NUMBER>,
<EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION: Throughout this document, ``we,'' ``us,''
and ``our'' refer to the EPA.

Table of Contents

I. Background for Proposed Actions
II. Clean Air Act Requirements for Moderate PM2.5
Nonattainment Area Plans
III. Clean Air Act Procedural Requirements for SIP Submittals
IV. Review of the South Coast 2012 PM2.5 Plan and 2015
Supplement
    A. Emissions Inventory
    B. Air Quality Modeling
    C. PM2.5 Precursors
    D. Reasonably Available Control Measures/Reasonably Available
Control Technology
    E. Major Stationary Source Control Requirements Under CAA
Section 189(e)
    F. Adopted Control Strategy
    G. Demonstration that Attainment by the Moderate Area Attainment
Date is Impracticable
    H. Reasonable Further Progress and Quantitative Milestones
    I. Contingency Measures
    J. Motor Vehicle Emission Budgets
    K. General Conformity Budgets
V. Proposed Reclassification as Serious Nonattainment and Serious
Area SIP Requirements
VI. Reclassification of Reservation Areas of Indian Country
VII. Summary of Proposed Actions and Request for Public Comment
VIII. Statutory and Executive Order Reviews

I. Background for Proposed Actions

    On October 17, 2006, the EPA revised the 24-hour national ambient
air quality standards (NAAQS or standard) for PM2.5,
particulate matter with a diameter of 2.5 microns or less, to provide
increased protection of public health by lowering its level from 65
micrograms per cubic meter ([micro]g/m\3\) to 35 [micro]g/m\3\ (40 CFR
50.13).\1\ Epidemiological studies have shown statistically significant
correlations between elevated PM2.5 levels and premature
mortality. Other important health effects associated with
PM2.5 exposure include aggravation of respiratory and
cardiovascular disease (as indicated by increased hospital admissions,
emergency room visits, absences from school or work, and restricted
activity days), changes in lung function and increased respiratory
symptoms. Individuals particularly sensitive to PM2.5
exposure include older adults, people with heart and lung disease, and
children (78 FR 3086 at 3088, January 15, 2013). PM2.5 can
be emitted directly into the atmosphere as a solid or liquid particle
(``primary PM2.5'' or ``direct PM2.5'') or can be
formed in the atmosphere as a result of various chemical reactions
among precursor pollutants such as nitrogen oxides, sulfur oxides,
volatile organic

compounds, and ammonia (``secondary PM2.5'').\2\
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    \1\ See 71 FR 61224 (October 17, 2006). The EPA set the first
NAAQS for PM2.5 on July 18, 1997 (62 FR 36852), including
annual standards of 15.0 [micro]g/m\3\ based on a 3-year average of
annual mean PM2.5 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). In 2012, the EPA
revised the annual standard to lower its level to 12 [micro]g/m\3\
(78 FR 3086, January 15, 2013, codified at 40 CFR 50.18). Unless
otherwise noted, all references to the PM2.5 standard in
this notice are to the 2006 24-hour standard of 35 [micro]g/m\3\
codified at 40 CFR 50.13.
    \2\ See EPA, Regulatory Impact Analysis for the Final Revisions
to the National Ambient Air Quality Standards for Particulate Matter
(EPA-452/R-12-005, December 2012), p. 2-1.
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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 November 13, 2009, the EPA
designated the South Coast as nonattainment for the 2006
PM2.5 standard of 35 [micro]g/m\3\ (74 FR 58688, November
13, 2009). This designation became effective on December 14, 2009 (40
CFR 81.305). The South Coast area is also designated nonattainment for
the 1997 annual and 24-hour PM2.5 standards.\3\ On June 2,
2014, the EPA classified the South Coast area as Moderate nonattainment
for both the 1997 PM2.5 standards and the 2006
PM2.5 standard under subpart 4 of part D, title I of the Act
(79 FR 31566).
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    \3\ See 70 FR 944 (January 5, 2005) and 40 CFR 81.305. In
November 2007, California submitted the 2007 PM2.5 Plan
to provide for attainment of the 1997 PM2.5 standards in
the South Coast. In November 2011, the EPA approved all but the
contingency measures in the 2007 PM2.5 Plan (76 FR 69928,
November 9, 2011). In November 2011 and April 2013, the State
submitted a revised contingency measure plan, which the EPA approved
on October 29, 2013 (78 FR 64402, October 29, 2013).
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    The South Coast PM2.5 nonattainment area is home to
about 17 million people, has a diverse economic base, and contains one
of the highest-volume port areas in the world. For a precise
description of the geographic boundaries of the South Coast
PM2.5 nonattainment area, see 40 CFR 81.305.
    Ambient PM2.5 levels in the South Coast have declined
considerably in the past 15 years to levels just above the 2006
PM2.5 NAAQS. For the 2011-2013 period, the 24-hour
PM2.5 design value for the area, based on monitored readings
at the Mira Loma monitor, is 36 ug/m3.\4\
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    \4\ See EPA, Air Quality System Report dated September 28, 2015
in the docket for today's action. ``Design value'' means the
calculated concentration according to the applicable appendix of 40
CFR part 50 for the highest site in an attainment or nonattainment
area (40 CFR 58.1).
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    The local air district with primary responsibility for developing a
plan to attain the 2006 PM2.5 NAAQS in this area is the
South Coast Air Quality Management District (District or SCAQMD). The
District works cooperatively with the California Air Resources Board
(CARB) in preparing these plans. Authority for regulating sources under
state jurisdiction in the South Coast 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.

II. Clean Air Act Requirements for PM2.5 Moderate
Nonattainment Area Plans

    In April 2007, the EPA issued the Clean Air Fine Particle
Implementation Rule (``2007 PM2.5 Implementation Rule'') to
assist states with the development of SIPs to meet the Act's attainment
planning requirements for the 1997 PM2.5 standards (72 FR
20583, April 25, 2007, codified at 40 CFR part 51, subpart Z). This
rule was premised on the EPA's prior interpretation of the Act as
allowing for implementation of the PM2.5 NAAQS solely
pursuant to the general nonattainment area provisions in subpart 1 of
part D, title I of the CAA (``subpart 1'') and not the more specific
provisions for particulate matter nonattainment areas in subpart 4 of
part D, title I of the Act (``subpart 4''). Among other things, the
2007 PM2.5 Implementation Rule included nationally-
applicable presumptions regarding the need to evaluate and potentially
control emissions of certain PM2.5 precursors.\5\
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    \5\ Specifically, in 40 CFR 51.1002(c), the EPA provided, among
other things, that a state was ``not required to address VOC [and
ammonia] as . . . PM2.5 attainment plan precursor[s] and
to evaluate sources of VOC [and ammonia] emissions in the State for
control measures,'' unless the State or the EPA provided an
appropriate technical demonstration showing that emissions from
sources of these pollutants ``significantly contribute'' to
PM2.5 concentrations in the nonattainment area (40 CFR
51.1002(c)(3) and (4) and 72 FR 20586 at 20589-97 (April 25, 2007)).
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    In March of 2012, the EPA issued a guidance document to aid states
in preparing SIPs to meet the Act's attainment planning requirements
for the 2006 24-hour PM2.5 standard.\6\ The 2012 guidance
was based, in large part, on the requirements in the 2007
PM2.5 Implementation Rule, which the EPA based solely upon
the statutory requirements of subpart 1.
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    \6\ See Memorandum, dated March 2, 2012 (withdrawn June 6,
2013), from Stephen D. Page, Director, Office of Air Quality
Planning and Standards, to EPA Regional Air Directors, Regions I-X
re: ``Implementation Guidance for the 2006 24-Hour Fine Particle
(PM2.5) National Ambient Air Quality Standards (NAAQS)''
(``2012 Guidance'') Available at: http://epa.gov/ttn/naaqs/pm/pm25_guide.html.
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    California had three years from the December 14, 2009 effective
date of the South Coast's designation as nonattainment for the 2006
PM2.5 standard to submit a SIP for the South Coast that
addressed the applicable requirements of the Act.\7\ On December 19,
2012, the District adopted the Final 2012 Air Quality Management Plan
(AQMP), which addressed attainment of the 2006 PM2.5 NAAQS,
among other CAA requirements. We refer herein to the portions of the
2012 AQMP that address attainment of the 2006 PM2.5 NAAQS as
the ``2012 PM2.5 Plan.'' On January 25, 2013, CARB adopted
the 2012 PM2.5 Plan as an element of the California SIP and
submitted it to the EPA on February 13, 2013.\8\
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    \7\ See CAA section 172(b) and 40 CFR 51.1002(a).
    \8\ See letter dated February 13, 2013, from James N. Goldstene,
Executive Officer, CARB, to Jared Blumenfeld, Regional
Administrator, EPA Region 9,, with attachments, and CARB Board
Resolution 13-3.
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    On January 4, 2013, several weeks after the District's adoption of
the Plan, the U.S. Court of Appeals for the DC Circuit issued its
decision in a challenge to the EPA's 2007 PM2.5
Implementation Rule (NRDC v. EPA, 706 F.3d 428 (D.C. Cir. 2013)). In
NRDC, the court held that the EPA erred in implementing the 1997
PM2.5 standards solely pursuant to the general
implementation requirements of subpart 1, without also considering the
requirements specific to particulate matter nonattainment areas in
subpart 4.\9\ The court reasoned that the plain meaning of the CAA
requires implementation of the 1997 PM2.5 standards under
subpart 4 because PM2.5 particles fall within the statutory
definition of PM10 and are thus subject to the same
statutory requirements as PM10. The court remanded the 2007
PM2.5 Implementation Rule in its entirety, including the
presumptions concerning VOC and ammonia in 40 CFR 51.1002, and
instructed the EPA ``to repromulgate these rules pursuant to Subpart 4
consistent with this opinion.''
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    \9\ The NRDC decision also remanded the EPA's 2008 final rule to
implement the nonattainment New Source Review (NNSR) permitting
requirements for PM2.5 (73 FR 28231, May 16, 2008) which,
like the 2007 PM2.5 Implementation Rule, was premised on
the requirements of subpart 1. Today's proposal does not address
requirements for NNSR programs.
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    Consistent with the NRDC decision, on June 2, 2014 (79 FR 31566),
the EPA published a final rule classifying all areas currently
designated nonattainment for the 1997 and/or 2006 PM2.5
standards as ``Moderate'' under subpart 4 and establishing a deadline
of December 31, 2014 for states to submit any attainment-related and
nonattainment new source review (NNSR) SIP elements required for these
areas pursuant to subpart 4. The EPA provided its rationale for these
actions in both the proposed and final classification/deadline
rule.\10\
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    \10\ See 79 FR 69806, 69809 (November 21, 2013) and 79 FR 31566,
31568 (June 2, 2014).
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    On February 6, 2015, the District adopted the ``Supplement to the
24-Hour PM2.5 State Implementation Plan for the South Coast
Air Basin'' (``2015

Supplement'' or ``Supplement'') as a revision to the 2012
PM2.5 Plan. The District adopted the Supplement to address
subpart 4 requirements for the 2006 PM2.5 standard to the
extent that these requirements were not adequately addressed in the
2012 PM2.5 Plan. CARB submitted the Supplement to the EPA on
March 4, 2015. The Supplement includes information on the
implementation of reasonably available controls for ammonia sources in
the South Coast and the District's demonstration that the 2012
PM2.5 Plan and 2015 Supplement satisfy the requirements of
subpart 4. As a consequence of the NRDC decision, we are reviewing the
2012 PM2.5 Plan and 2015 Supplement for compliance with the
applicable requirements of both subpart 1 and subpart 4.
    The EPA provided its preliminary views on the CAA's requirements
for particulate matter plans under part D, title I of the Act in
``State Implementation Plans; General Preamble for the Implementation
of Title I of the Clean Air Act Amendments of 1990'' (57 FR 13498,
April 16, 1992) (``General Preamble'') and ``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'' (59 FR 41998, August 16, 1994) (``Addendum''). The General
Preamble at 13538 discusses the relationship of subpart 1 and subpart 4
SIP requirements, and notes that attainment plans for moderate
nonattainment areas must meet the general provisions in subpart 1 to
the extent that these provisions are not otherwise ``subsumed by, or
integrally related to, the more specific [subpart 4] requirements.''
Some subpart 1 provisions have no subpart 4 equivalent (e.g., the
emission inventories (CAA section 172(c)(3)) and contingency measures
(CAA section 172(c)(9)) and for these provisions, subpart 1 continues
to govern. Other provisions of subpart 1 are subsumed or superseded by
more specific requirements in subpart 4 (e.g., certain provisions
concerning attainment dates).
    Additionally, in a proposed rule published March 23, 2015 (80 FR
15340), the EPA provided further interpretive guidance on the statutory
SIP requirements that apply to areas designated nonattainment for the
PM2.5 standards (hereafter ``Proposed PM2.5
Implementation Rule''). We discuss these preliminary interpretations of
the Act as appropriate in our evaluation of the 2012 PM2.5
Plan and 2015 Supplement in section IV of this proposed rule.

III. Clean Air Act Procedural Requirements for SIP Submittals

    We are proposing action on two California SIP submittals. The first
is the ``2012 PM2.5 Plan,'' submitted on February 13, 2013,
and the second is the 2015 Supplement, submitted on March 4,
2015.11 12
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    \11\ See footnote 8.
    \12\ See Letter dated March 4, 2015 from Richard W. Corey,
Executive Officer, California Air Resources Board, to Jared
Blumenfeld, Regional Administrator EPA Region 9, with attachments,
and CARB Resolution 15-3.
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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 submittal of a SIP or SIP revision. To meet
this requirement, every SIP submittal should include evidence that
adequate public notice was given and an opportunity for a public
hearing was provided consistent with the EPA's implementing regulations
in 40 CFR 51.102.
    Both the District and CARB satisfied applicable statutory and
regulatory requirements for reasonable public notice and hearing prior
to adoption and submittal of the 2012 PM2.5 Plan. The
District conducted public workshops, provided public comment periods,
and held a public hearing prior to the adoption of the 2012
PM2.5 Plan on December 7, 2012.\13\ CARB provided the
required public notice and opportunity for public comment prior to its
January 25, 2013 public hearing on the 2012 PM2.5 Plan.\14\
The SIP submittal includes proof of publication of notices for these
public hearings. We find, therefore, that the 2012 PM2.5
Plan meets the procedural requirements for public notice and hearing in
CAA sections 110(a) and 110(l).
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    \13\ See 2012 PM2.5 Plan, Public hearing notices,
SCAQMD Governing Board Resolution 12-19, ``A Resolution of the South
Coast Air Quality Management District (AQMD or District) Governing
Board Certifying the Final Program Environmental Impact Report for
the 2012 Air Quality Management Plan (AQMP), adopting the Draft
final 2012 AQMP, to be referred to after Adoption as the Final 2012
AQMP, and to be submitted into the California State Implementation
Plan,'' December 7, 2012.
    \14\ See CARB Resolution 13-3, ``South Coast Air Basin 2012
PM2.5 and Ozone State Implementation Plans,'' January 25,
2013.
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    The District adopted the 2015 Supplement after reasonable public
notice and hearing.\15\ CARB adopted the Supplement for submittal as a
SIP revision at its February 19, 2015 Board meeting after reasonable
public notice.\16\
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    \15\ See Notice of Public Hearing to Adopt Supplemental Document
to the 2012 PM2.5 Plan for the 2006 PM2.5 Standard.
    \16\ See CARB, Notice of Public Meeting to Consider a Minor
Revision to the South Coast 2012 PM2.5 State
Implementation Plan, and CARB Board Resolution 15-2, February 19,
2015.
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    CAA section 110(k)(1)(B) requires the EPA to determine whether a
SIP submittal 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 submittal. The EPA's SIP completeness criteria
are found in 40 CFR part 51, Appendix V. A completeness review allows
us to determine if the submittal includes all the necessary items and
information we need to evaluate and act on it for substantive
compliance with applicable requirements.
    The February 13, 2013 submittal of the 2012 PM2.5 Plan
became complete by operation of law on August 13, 2014. The 2015
Supplement became complete by operation of law on September 4, 2015
(see our Technical Support Document (TSD) at section I.B).

IV. Review of the South Coast 2012 PM2.5 Plan and 2015
Supplement

    We summarize our evaluation of the 2012 PM2.5 Plan and
2015 Supplement below. Our detailed evaluation can be found in the TSD
for this proposal which is available online at www.regulations.gov in
docket number EPA-R09-OAR-2015-0204, on EPA Region 9's Web site at
http://www.epa.gov/region9/air/actions/southcoast/#PM25, or from the
EPA contact listed at the beginning of this notice.

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] area . . .
.'' By requiring an accounting of actual emissions from all sources of
the relevant pollutants in the area, this section provides for the base
year inventory to include all emissions that contribute to the
formation of a particular NAAQS pollutant. For the 2006 24-hour
PM2.5 NAAQS, this includes direct PM2.5 as well
as the main chemical precursors to the formation of secondary
PM2.5: NOX, SO2, VOC, and ammonia
(NH3). Primary PM2.5 includes condensable and
filterable particulate matter.

    A state should include in its SIP submittal documentation
explaining how the emissions data were calculated. In estimating mobile
source emissions, a state should use the latest emissions models and
planning assumptions available at the time the SIP is developed. At the
time the 2012 PM2.5 Plan and 2015 Supplement were developed,
California was required to use EMFAC2011 to estimate tailpipe and brake
and tire wear emissions of PM2.5, NOX,
SO2, and VOC from on-road mobile sources (78 FR 14533, March
6, 2013). States are required to use the EPA's AP-42 road dust method
for calculating re-entrained road dust emissions from paved roads (76
FR 6328, February 4, 2011).
    In addition to the base year inventory submitted to meet the
requirements of CAA section 172(c)(3), the state must also submit
future ``baseline inventories'' for the projected attainment year and
each reasonable further progress (RFP) milestone year, and any other
year of significance for meeting applicable CAA requirements. By
``baseline inventories'' (also referred to as ``projected baseline
inventories''), we mean projected emissions inventories for future
years that account for, among other things, the ongoing effects of
economic growth and adopted emissions control requirements. The SIP
submission should include documentation explaining how the emissions
projections were calculated.
2. Emissions Inventories in the 2012 PM2.5 Plan
    The annual average planning inventories for direct PM2.5
and all PM2.5 precursors (NOX, SOX,
VOC, and ammonia) for the South Coast PM2.5 nonattainment
area together with documentation for the inventories are found in
Chapter 3 and Appendices III and V of the South Coast 2012
PM2.5 Plan and in Attachment A to the 2015 Supplement.
Additional inventory documentation specific to the air quality modeling
is in Appendix V. Annual average inventories are provided for the 2008
base year, and for future years 2014 and the PM2.5
attainment year of 2015. (Additional years such as 2017, 2019, 2023 and
2030 are also provided, but these inventories are largely for the
purposes of ozone attainment.) Baseline inventories reflect all control
measures adopted by the District prior to June 2012 and by CARB prior
to August 2011. Growth factors used to project these baseline
inventories are derived mainly from data obtained from the Southern
California Association of Governments (SCAG), the metropolitan planning
organization (MPO) for the Los Angeles area (2012 PM2.5
Plan, page 3-1).
    Each inventory includes emissions from point, area, on-road, and
non-road sources. Stationary sources include point and area sources.
Point sources in the South Coast air basin that emit 4 tons per year or
more of VOC, NOX, SOX or PM report annual
emissions to the District. Point source emissions for the 2008 base
year emission inventory were based on emissions reported from the
SCAQMD's Annual Emissions Reporting Program.\17\ Area sources include
smaller emissions sources distributed across the nonattainment area.
CARB and the District estimate emissions for about 400 area source
categories using activity information and emission factors. Activity
data may come from national survey data or reports (e.g., from the DOE
Energy Information Administration) or local sources such as the
Southern California Gas Company, paint suppliers, and District
databases. Emission factors can be based on a number of sources
including source tests, compliance reports, and EPA's AP-42.\18\
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    \17\ See http://www.aqmd.gov/home/regulations/compliance/annual-emission-reporting.
    \18\ AP-42 is EPA's Compilation of Air Pollutant Emission
Factors, and has been published since 1972 as the primary source of
EPA's emission factor information. It contains emission factors and
process information for more than 200 air pollution source
categories. A source category is a specific industry sector or group
of similar emitting sources. The emission factors have been
developed and compiled from source test data, material balance
studies, and engineering estimates.
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    Emissions inventories are constantly being revised and improved.
Between the finalization of the South Coast 2007 AQMP and the
development of the 2012 PM2.5 Plan, the District added new
area source categories such as liquefied petroleum gas (LPG)
transmission losses, storage tank and pipeline cleaning and degassing,
and architectural colorants to the inventories in the 2012
PM2.5 Plan. We provide more detail on these updates and
revisions in section II.A. of the TSD.
    The on-road mobile inventories use EMFAC2011 for estimating motor
vehicle emissions (2012 PM2.5 Plan, p. 3-1).\19\ Since
EMFAC2011 was released in 2011, CARB has adopted additional regulations
to control air pollution from mobile sources. For the 2012
PM2.5 Plan, the State adjusted EMFAC2011 emissions estimates
for the advanced clean cars program, reformulated gasoline rules, and
Smog Check program to reflect these new measures (2012 PM2.5
Plan, p. 3-5). Re-entrained paved road dust emissions were calculated
using EPA's AP-42 road dust methodology (2012 PM2.5 Plan,
Appendix III, p. III-1-13 and 2015 Supplement, Attachment B). SCAG, the
MPO for the Los Angeles area, provided transportation activity data
from the adopted 2012 Regional Transportation Plan (RTP).
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    \19\ EMFAC2011 was approved for use in SIPs and conformity on
March 6, 2013 (see 78 FR 14533).
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    Off-road emissions such as construction, mining, gardening and
agricultural equipment emissions were calculated using CARB's 2011 In-
Use Off-Road Fleet Inventory Model. The off-road equipment population
was adjusted due to the recession, and equipment hours of use were
adjusted based on reported activity. Equipment load factors were
updated using a 2009 academic study and information provided by engine
manufacturers. External adjustments were made to CARB's off-road
emissions estimates for locomotives, large-spark ignition engines, and
nonagricultural internal combustion engines. CARB also calculated
emissions from ocean-going vessels, commercial harbor craft,
locomotives, and cargo handling equipment. Locomotive emissions reflect
EPA regulations effective in 2008 and adjustments due to economic
activity. The District estimated aircraft emissions. Future emissions
forecasts are based largely on growth forecasts (demographic and
economic information) from SCAG.
    A summary of the Plan's 2008 base year inventory and the 2014
projected inventory is provided in Table 1 below. For a more detailed
discussion of the inventories, see the 2012 PM2.5 Plan,
Appendix III.

  Table 1--Summary of Emissions for the South Coast PM2.5 Nonattainment
                                  Area
                    [Annual average in tons per day]
------------------------------------------------------------------------
                                               2008            2014
------------------------------------------------------------------------
                              Direct PM2.5
------------------------------------------------------------------------
Stationary and Area Sources.............              48              50
On-Road Mobile Sources..................              19              12
Off-Road Mobile Sources.................              13               8
                                         -------------------------------
    Total...............................              80              70
------------------------------------------------------------------------
                             Nitrogen Oxides
------------------------------------------------------------------------
Stationary and Area Sources.............              92              77
On-Road Mobile Sources..................             462             272
Off-Road Mobile Sources.................             204             157
                                         -------------------------------
    Total...............................             758             506
------------------------------------------------------------------------
                             Sulfur Dioxide
------------------------------------------------------------------------
Stationary and Area Sources.............              14              12
On-Road Mobile Sources..................               2               2
Off-Road Mobile Sources.................              38               4
                                         -------------------------------
    Total...............................              54              18
------------------------------------------------------------------------
                       Volatile Organic Compounds
------------------------------------------------------------------------
Stationary and Area Sources.............             257             234
On-Road Mobile Sources..................             209             117
Off-Road Mobile Sources.................             127             100
                                         -------------------------------
    Total...............................             593             451
------------------------------------------------------------------------
                                 Ammonia
------------------------------------------------------------------------
Stationary and Area Sources.............            88.7            85.6
On-Road Mobile Sources..................            19.9            16.5
Off-Road Mobile Sources.................             0.1             0.1
                                         -------------------------------
    Total...............................           108.9           102.1
------------------------------------------------------------------------
Source: South Coast 2012 PM2.5 Plan, Chapter 3, Tables 3-2A, 3-4A,
  Appendix III, Table III-1-5, and 2008 ammonia inventory from Appendix
  V, Table V-4-2.

3. Evaluation and Proposed Action
    The emissions inventories in the 2012 PM2.5 Plan were
made available to the public for comment and were subject to public
hearing at both the District and State levels. See SCAQMD Governing
Board Resolution 12-19, p. 3 and CARB Resolution 13-3, p. 4.
    The inventories in the South Coast 2012 PM2.5 Plan and
2015 Supplement are based on the most current and accurate information
available to the State and District at the time the 2012
PM2.5 Plan and its inventories were being developed,
including the latest EPA-approved version of California's mobile source
emissions model, EMFAC2011, and the EPA's most recent AP-42 methodology
for paved road dust. The inventories comprehensively address all source
categories in the South Coast and were developed consistent with the
EPA's inventory guidance. For these reasons, we are proposing to
approve the 2008 base year emissions inventory in the 2012
PM2.5 Plan as meeting the requirements of CAA section
172(c)(3). We also propose to find that the baseline inventories in the
Plan provide an adequate basis for the reasonably available control
measure (RACM), RFP, and impracticability demonstrations in the 2012
PM2.5 Plan.

B. Air Quality Modeling

1. Requirements for Air Quality Modeling
    CAA section 189(a)(1)(B) requires each State in which a Moderate
area is located to submit a plan that includes a demonstration either
(i) that the plan will provide for attainment by the applicable
attainment date, or (ii) that attainment by that date is impracticable.
The 2012 PM2.5 Plan, 2015 Supplement, and July 28, 2015
letter include a demonstration that attainment by the Moderate
attainment date is impracticable.
    Air quality modeling is used to establish attainment emissions
targets, the combination of emissions of PM2.5 and
PM2.5 precursors that the area can accommodate and still
attain the standard, and to assess whether the proposed control
strategy will result in attainment of the standard. Air quality
modeling is performed for a base year and compared to air quality
monitoring data collected during that year in order to determine model
performance. Once the performance is determined to be acceptable,
future year changes to the emissions inventory are simulated with the
model to determine the relationship between emissions reductions and
changes in ambient air quality. To project future design values, the
model response to emission reductions, in the form of Relative Response
Factors (RRFs), is applied to monitored design values from the base
year.

    For demonstrating attainment, the EPA's recommendations for model
input preparation, model performance evaluation, use of the model
output for the attainment demonstration, and modeling documentation are
described in Guidance on the Use of Models and Other Analyses for
Demonstrating Attainment of Air Quality Goals for Ozone, PM2.5, and
Regional Haze, EPA-454/B-07-002, April 2007 (``Modeling Guidance''), as
amended by ``Update to the 24 Hour PM2.5 NAAQS Modeled
Attainment Test,'' Memorandum dated June 28, 2011, from Tyler Fox, Air
Quality Modeling Group, Office of Air Quality Planning and Standards,
EPA to Regional Air Program Managers, EPA (``Modeling Guidance
Update'').\20\ As discussed below, the Modeling Guidance recommends
supplemental air quality analyses. These may be used as part of a
Weight of Evidence analysis (WOEA), which assesses attainment
projections by considering evidence other than the main air quality
modeling attainment test.
---------------------------------------------------------------------------

    \20\ The EPA modeling guidance is available on EPA's SCRAM Web
site, Web page: http://www.epa.gov/scram001/guidance_sip.htm; direct
links: http://www.epa.gov/scram001/guidance/guide/final-03-pm-rh-guidance.pdf and http://www.epa.gov/ttn/scram/guidance/guide/Update_to_the_24-hour_PM25_Modeled_Attainment_Test.pdf.
---------------------------------------------------------------------------

    The EPA has not issued modeling guidance specific to
impracticability demonstrations but believes that a state seeking to
make such a demonstration generally should provide air quality modeling
similar to that required for an attainment demonstration. The main
difference is that for an impracticability demonstration, the
implementation of the SIP control strategy (including RACM) does not
result in attainment of the standard by the Moderate area attainment
date.
    For an attainment demonstration, a thorough review of all modeling
inputs and assumptions (including consistency with EPA guidance) is
especially important, since the modeling must ultimately support a
conclusion that the plan (including its control strategy) will provide
for timely attainment of the applicable NAAQS. In contrast, for an
impracticability demonstration, the end point is a reclassification to
Serious, which triggers the requirement for a new Serious Area
attainment plan with a new air quality modeling analysis, and a new
control strategy. See CAA section 189(b)(1). Thus, the Serious Area
planning process would provide an opportunity to refine the modeling
analysis and/or correct any technical shortcomings in the
impracticability demonstration. Therefore, the burden of proof will
generally be lower for an impracticability demonstration compared to an
attainment demonstration.
 2. Air Quality Modeling in the 2012 PM2.5 Plan
    The 2012 PM2.5 Plan and 2015 Supplement contain a
demonstration of attainment by the Moderate area attainment date, which
is December 31, 2015. SCAQMD developed a modeling protocol for the 2012
PM2.5 Plan, which EPA reviewed during the District's
development of the Plan. The Plan discusses air quality modeling in
Chapter 5, ``Future Air Quality,'' and in detail in Appendix V,
``Modeling and Attainment Demonstrations.'' The 2012 PM2.5
Plan's attainment demonstration was based on photochemical modeling
with the Community Multiscale Air Quality (CMAQ) model, using routinely
available meteorological and air quality data as input. The 2012
PM2.5 Plan and the 2015 Supplement contain an unmonitored
area analysis as well as a weight of evidence (WOE) demonstration. The
WOE demonstration in the 2015 Supplement accounts to some extent for
the effect of the drought on ambient PM2.5 levels in the
South Coast.
    In a letter dated July 28, 2015, the SCAQMD requested that EPA
reclassify the South Coast Air Basin as Serious nonattainment for the
2006 24-hour PM2.5 NAAQS based on monitoring data indicating
that attainment is not practicable by the Moderate area attainment
date, which is December 31, 2015.\21\ The SCAQMD also requested that
the EPA treat the 2012 PM2.5 Plan and 2015 Supplement,
together with the air quality data provided in the July 28, 2015
letter, as a demonstration that the area cannot practicably attain by
the Moderate area attainment date.
---------------------------------------------------------------------------

    \21\ See letter dated July 28, 2015, from Barry R. Wallerstein,
Executive Officer, SCAQMD, to Elizabeth Adams, Acting Director, Air
Division, US Environmental Protection Agency, Region 9.
---------------------------------------------------------------------------

    Based on the request from the SCAQMD, the modeled attainment
demonstration provided in the Plan, the 2015 Supplement, and the
monitoring data provided in the July 28, 2015 letter, we are evaluating
the State's submittal as a demonstration that attainment by the
Moderate area attainment date is impracticable. We provide a more
detailed evaluation of the air quality modeling in the Plan in section
II.B. of our TSD.
3. Conclusion on Air Quality Modeling
    Given the Plan's extensive discussion of modeling procedures,
tests, and performance analyses consistent with EPA's guidance in the
Modeling Protocol, and the good model performance, EPA finds that the
modeling is adequate for purposes of supporting the RACM demonstration,
the RFP demonstration, and the demonstration of impracticability in the
2012 PM2.5 Plan and Supplement.

C. PM2.5 Precursors

1. Requirements for the Control of PM2.5 Precursors
    The composition of PM2.5 is complex and highly variable
due in part to the large contribution of secondary PM2.5 to
total fine particle mass in most locations, and to the complexity of
secondary particle formation processes. A large number of possible
chemical reactions, often non-linear in nature, can convert gaseous
SO2, NOX, VOC and ammonia to PM2.5,
making them precursors to PM2.5.\22\ Formation of secondary
PM2.5 may also depend on atmospheric conditions, including
solar radiation, temperature, and relative humidity, and the
interactions of precursors with preexisting particles and with cloud or
fog droplets.\23\
---------------------------------------------------------------------------

    \22\ EPA, Air Quality Criteria for Particulate Matter (EPA/600/
P-99/002aF, October 2004), Chapter 3.
    \23\ EPA, Regulatory Impact Analysis for the Final Revisions to
the National Ambient Air Quality Standards for Particulate Matter
(EPA-452/R-12-005, December 2012), p. 2-1.
---------------------------------------------------------------------------

    The 2007 PM2.5 Implementation Rule contained rebuttable
presumptions concerning the four PM2.5 precursors applicable
to attainment plans and control measures related to those plans. See 40
CFR 51.1002(c). Although the rule included presumptions that states
should address SO2 and NOX emissions in their
attainment plans, it also included presumptions that regulation of VOCs
and ammonia was not necessary. Specifically, in 40 CFR 51.1002(c), the
EPA provided, among other things, that a state was ``not required to
address VOC [and ammonia] as . . . PM2.5 attainment plan
precursor[s] and to evaluate sources of VOC [and ammonia] emissions in
the state for control measures,'' unless the state or the EPA provided
an appropriate technical demonstration showing that emissions from
sources of these pollutants ``significantly contribute'' to
PM2.5 concentrations in the nonattainment area. 40 CFR
51.1002(c)(3), (4); see also 2007 PM2.5 Implementation Rule,
72 FR 20586 at 20589-97 (April 25, 2007).
    In NRDC, however, the D.C. Circuit remanded the EPA's 2007
PM2.5 Implementation Rule in its entirety, including the
presumptions concerning VOC and ammonia in 40 CFR 51.1002. See NRDC v.
EPA, 706 F.3d 428 (D.C.

Cir. 2013). Although the court expressly declined to decide the
specific challenge to these presumptions (see 706 F.3d at 437, n. 10
(D.C. Cir. 2013)), the court cited CAA section 189(e) \24\ to support
its observation that ``[a]mmonia is a precursor to fine particulate
matter, making it a precursor to both PM2.5 and
PM10'' and that ``[f]or a PM10 nonattainment area
governed by subpart 4, a precursor is presumptively regulated.'' 706
F.3d at 436, n. 7 (citing CAA section 189(e)). Consistent with the NRDC
decision, EPA now interprets the Act to require that under subpart 4, a
state must evaluate all PM2.5 precursors for regulation
unless the state provides a demonstration adequate to rebut the
presumption for a particular precursor in a particular nonattainment
area.
---------------------------------------------------------------------------

    \24\ Section 189(e) of the CAA states that ``[t]he control
requirements applicable under plans in effect under this part for
major stationary sources of PM10 shall also apply to
major stationary sources of PM10 precursors, except where
the Administrator determines that such sources do not contribute
significantly to PM10 levels which exceed the standard in
the area.''
---------------------------------------------------------------------------

    The provisions of subpart 4 do not define the term ``precursor''
for purposes of PM2.5, nor do they explicitly require the
control of any specifically identified particulate matter (PM)
precursor. The statutory definition of ``air pollutant,'' however,
provides that the term ``includes any precursors to the formation of
any air pollutant, to the extent the Administrator has identified such
precursor or precursors for the particular purpose for which the term
`air pollutant' is used.'' CAA section 302(g). The EPA has identified
SO2, NOX, VOC, and ammonia as precursors to the
formation of PM2.5. Accordingly, the attainment plan
requirements of subpart 4 presumptively apply to emissions of all four
precursor pollutants and direct PM2.5 from all types of
stationary, area, and mobiles sources, except as otherwise provided in
the Act (e.g. CAA section 189(e)).
    Section 189(e) of the Act requires that the control requirements
for major stationary sources of direct PM10 also apply to
major stationary sources of PM10 precursors, except where
the Administrator determines that such sources do not contribute
significantly to PM10 levels that exceed the standard in the
area. Section 189(e) contains the only express exception to the control
requirements under subpart 4 (e.g., requirements for RACM and RACT,
BACM and BACT, most stringent measures, and NSR) for sources of direct
PM2.5 and PM2.5 precursor emissions. Although
section 189(e) explicitly addresses only major stationary sources, the
EPA interprets the Act as authorizing it to also determine, under
appropriate circumstances, that regulation of certain PM2.5
precursors from other source categories in a given nonattainment area
is not necessary. For example, under the EPA's longstanding
interpretation of the control requirements that apply to stationary,
area, and mobile sources of PM10 precursors area-wide under
CAA section 172(c)(1) and subpart 4 (see General Preamble, 57 FR 13498
at 13539-42), a state may demonstrate in a SIP submittal that control
of a certain precursor pollutant is not necessary in light of its
insignificant contribution to ambient PM2.5 levels in the
nonattainment area.\25\
---------------------------------------------------------------------------

    \25\ Courts have upheld this approach to the requirements of
subpart 4 for PM10. See, e.g., Assoc. of Irritated
Residents v. EPA, et al., 423 F.3d 989 (9th Cir. 2005).
---------------------------------------------------------------------------

    We are evaluating the South Coast PM2.5 Plan in
accordance with the presumption embodied within subpart 4 that all
PM2.5 precursors must be addressed in the state's evaluation
of potential control measures, unless the state adequately demonstrates
that emissions of a particular precursor do not contribute
significantly to ambient PM2.5 levels that exceed the
PM2.5 NAAQs in the nonattainment area.
2. Evaluation of Precursors in 2012 PM2.5 Plan and 2015
Supplement
    The 2012 PM2.5 Plan and 2015 Supplement discuss the five
primary pollutants that contribute to the mass of the ambient aerosol
(i.e., ammonia, NOX, SOX, VOC, and directly
emitted PM2.5), and states that various combinations of
reductions in these pollutants could all provide a path to clean
air.\26\ The Plan assesses and presents the relative value of each ton
of precursor emission reductions, considering the resulting ambient
microgram per cubic meter improvements in PM2.5 air
quality.\27\ As presented in the weight of evidence discussion, trends
of PM2.5 and NOX emissions suggest a direct
response between lower emissions of PM2.5 and NOX
and improved air quality. The CMAQ simulations in the Plan provide a
set of response factors for direct PM2.5, NOX,
SOX and VOCs, based on improvements to ambient 24-hour
PM2.5 levels resulting from reductions of each pollutant.
The contribution of ammonia emissions is embedded as a component of the
SOX and NOX factors since ammonium nitrate and
ammonium sulfate are the resultant particulate species formed in the
atmosphere.
---------------------------------------------------------------------------

    \26\ 2012 PM2.5 Plan, Appendix V, p. V-5-51 and
Appendix V, Attachment 8, Relative Contributions of Precursor
Emissions Reductions to Simulated Controlled Future-Year 24-hour
PM2.5 Concentrations.
    \27\ 2012 PM2.5 Plan, Appendix V, Attachment 8,
Relative Contributions of Precursor Emissions Reductions to
Simulated Controlled Future-Year 24-hour PM2.5
Concentrations.
---------------------------------------------------------------------------

    The 2012 PM2.5 Plan and 2015 Supplement describe how
reductions in NOX, SO2, VOC and ammonia emissions
contribute to attainment of the PM2.5 standard in the South
Coast area and contain the District's evaluation of available control
measures for all four of these PM2.5 precursor pollutants,
in addition to direct PM2.5, consistent with the regulatory
presumptions under subpart 4. The 2015 Supplement also contains a
discussion of the nonattainment New Source Review (NNSR) control
requirements applicable to major stationary sources under CAA section
189(e) (see 2015 Supplement at Attachment E), which we are not
addressing in this proposal.\28\ We discuss the state's evaluation of
potential control measures for direct PM2.5, NOX,
SO2, VOC and ammonia in section IV.D of this rulemaking,
``Reasonably Available Control Measures/Reasonably Available Control
Technology.''
---------------------------------------------------------------------------

    \28\ In a separate rulemaking to approve revisions to SCAQMD's
nonattainment New Source Review (NNSR) program, the EPA determined
that the control requirements applicable under the SCAQMD SIP to
major stationary sources of direct PM2.5 also apply to
major stationary sources of NOX, SOX, and VOC,
and that major stationary sources of ammonia do not contribute
significantly to PM2.5 levels which exceed the
PM2.5 standards in the area. See 80 FR 24821, May 1,
2015. This rulemaking addressed the control requirements of CAA
section 189(e) only for NNSR purposes and not for attainment
planning purposes under subpart 1 and 4 of part D, title I of the
Act.
---------------------------------------------------------------------------

D. Reasonably Available Control Measures/Reasonably Available Control
Technology

1. Requirements for RACM/RACT
    The general subpart 1 attainment plan requirement for RACM and RACT
is described in CAA section 172(c)(1), which requires that attainment
plan submissions ``provide for the implementation of all reasonably
available control measures as expeditiously as practicable (including
such reductions in emissions from existing sources in the area as may
be obtained through the adoption, at a minimum, of reasonably available
control technology) and shall provide for attainment'' of the NAAQS.
The attainment planning requirements specific to PM2.5 under
subpart 4 likewise impose upon states an obligation to develop
attainment plans that require RACM on sources of direct
PM2.5 and those PM2.5 precursors determined to be
subject to the RACM/

RACT requirement. CAA section 189(a)(1)(C) requires that Moderate area
PM2.5 SIPs contain provisions to assure that RACM are
implemented by no later than 4 years after designation of the area. The
EPA reads CAA sections 172(c)(1) and 189(a)(1)(C) together to require
that attainment plans for Moderate nonattainment areas must provide for
the implementation of RACM and RACT for existing sources of
PM2.5 and PM2.5 precursors in the nonattainment
area as expeditiously as practicable but no later than 4 years after
designation.\29\ As part of the RACM/RACT analysis, all available
controls should be evaluated, and reasonable controls should be
adopted.
---------------------------------------------------------------------------

    \29\ This interpretation is consistent with guidance provided in
the General Preamble at 13540.
---------------------------------------------------------------------------

    The terms RACM and RACT are not specifically defined in the Act,
nor do the provisions of subpart 4 specify how states are to meet the
RACM and RACT requirements. In longstanding guidance, however, the EPA
has interpreted the RACM requirement to include any potential control
measure for a point, area, on-road and non-road emission source that is
technologically and economically feasible (General Preamble at 13540).
The EPA has historically defined RACT as the lowest emission limitation
that a particular stationary source is capable of meeting by the
application of control technology (e.g., devices, systems, process
modifications, or other apparatus or techniques that reduce air
pollution) that is reasonably available considering technological and
economic feasibility. See General Preamble at 13541 and 57 FR 18070,
18073-74 (April 28, 1992).
    An evaluation of technological feasibility should include
consideration of factors such as a source's process and operating
conditions, raw materials, physical plant layout, and non-air quality
and energy impacts (e.g., increased water pollution, waste disposal,
and energy requirements) (57 FR 18070, 18073).
    An evaluation of economic feasibility should include consideration
of factors such as cost per ton of pollution reduced (cost-
effectiveness), capital costs, and annualized cost (57 FR 18070,
18074). Absent other indications, the EPA presumes that it is
reasonable for similar sources to bear similar costs of emissions
reductions. Economic feasibility of RACM and RACT is thus largely
informed by evidence that other sources in a source category have in
fact applied the control technology, process change, or measure in
question in similar circumstances. Id.
2. RACM/RACT Analysis in the 2012 PM2.5 Plan and 2015
Supplement
    The 2012 PM2.5 Plan and 2015 Supplement's RACM/RACT
evaluation for direct PM2.5, NOX, VOC,
ammonia, and SOX sources is presented in Appendix
VI and in Attachment D to the 2015 Supplement. SCAG's RACM analysis for
mobile sources is detailed in the 2012 PM2.5 Plan, Appendix
IV-C (``Regional Transportation Strategies and Control Measures'').
CARB's RACM evaluation for mobile sources is included in Appendix VI of
the 2012 PM2.5 Plan.
    The evaluation of potential controls is presented by pollutant and
then by rule type/source category. For stationary and area source
categories, the comparison to recently-issued EPA CTGs is broken down
by the current District rule or rules that apply to that source
category. See 2012 PM2.5 Plan, Appendix VI, and 2015
Supplement, Attachment D.
    For the 2012 PM2.5 Plan, the District, CARB and SCAG
each undertook a process to identify and evaluate potential measures
that could contribute to expeditious attainment of the PM2.5
standards in the South Coast nonattainment area. We describe these
processes below.
    The District conducted a multi-step process to identify candidate
RACM measures for the South Coast 2012 PM2.5 Plan that are
technologically and economically feasible. The first step was to
conduct a 2012 Air Quality Technology Symposium in September of 2011.
Technical experts from a wide variety of areas and the public were
invited to provide new and innovative concepts to assist the South
Coast area with attaining the PM and ozone NAAQS. The District also
conducted ongoing outreach to engage stakeholders in the process. The
following concepts were proposed as a result of these efforts:
     Promote zero or near-zero emission technologies and
provide incentives for mobile source and goods movement equipment
upgrades,
     further reduce VOC emissions from coatings, solvents, and
various consumer products focusing on reformulations or alternatives to
VOC-based solvents,
     conduct a technology review for NOX RECLAIM,
and further reduce NOX emissions through the use of low
NOX burners, fuel cells, biogas, and distributed power
generation,
     address energy-climate change and co-benefits, the need
for electricity storage, or new fossil-fueled peaking plants, to
compensate for fluctuation in renewable energy supply, and use outreach
to promote energy efficiency, influence consumer behavior, expand
carpools, increase gas taxes, and promote multiagency collaboration.
    The second step in the District's RACM process was to look at the
EPA's list of suggested control measures for PM2.5
nonattainment areas described in the 2007 PM2.5
Implementation Rule. The District summarized the results of this
analysis in Table VI-3 in Appendix VI of the 2012 PM2.5
Plan. This analysis shows that the District either has a pre-existing
rule or has developed a control measure for the 2012 PM2.5
Plan to address each of EPA's suggested types of measures.
    The third step in the District's RACM process involved analyzing
the District's rules for compliance with the RACT standard. The results
of this analysis are summarized in Table VI-4, Appendix VI (page VI-10)
of the 2012 PM2.5 Plan. The District further supplemented
these analyses in the 2015 Supplement, Attachment D, Tables D-4 to D-8
to address RACM and RACT requirements for direct PM2.5 and
all PM2.5 precursors, and to provide reasoned justifications
for control measures that were not adopted. A few examples of RACT-
level rules in the South Coast include Rules 1146 and 1146.1, which
control NOX from industrial and institutional boilers, Rule
1113.3, greenwaste composting, which in addition to providing a RACT
level of control, also controls fugitives, Rule 1171, Solvent Cleaning,
and Rule 1130, Graphic Arts.\30\
---------------------------------------------------------------------------

    \30\ The technical support documents for EPA's rulemaking
actions on these rules are available at: http://yosemite.epa.gov/r9/
r9sips.nsf/AgencyProvision/5F5287B726E9E6F488257D790004839A/$file/
1146+and+1146+1+June+2014.pdf?OpenElement, http://yosemite.epa.gov/r9/r9sips.nsf/AgencyProvision/5AD85F69581DEB9388257AC50057D806?OpenDocument, http://yosemite.epa.gov/r9/r9sips.nsf/AgencyProvision/F65EA6DB0E3F7F06882579210082BE8C?OpenDocument, and http://
yosemite.epa.gov/r9/r9sips.nsf/AgencyProvision/
865FFD6DBAC8018F88257E82007BA257/$file/
1130+Jun+2015.pdf?OpenElement.
---------------------------------------------------------------------------

    As part of these evaluations, the District compared its SIP rules
with current rules, regulations and control measures implemented in
other nonattainment areas. Specifically, the District re-evaluated all
of its source category-specific rules and compared the requirements in
these rules to more than 100 rules from four other air districts in
California (San Joaquin Valley, Sacramento Metropolitan, Ventura, and
San Francisco Bay Area), the Dallas-Fort Worth and Houston-Galveston
areas in Texas, New York, and New Jersey. A summary of this analysis is
presented in the 2012 PM2.5 Plan, Appendix VI, Table VI-5
and in the 2015 Supplement, Attachment D.

Table VI-5 identifies those rules from other areas that, based on the
District's review, may be more stringent in some respects than South
Coast rules. With respect to South Coast Rules 1115, 1130, and 1168,
the Plan states the District's intention to provide further analyses at
a later time. See 2012 PM2.5 Plan, Appendix VI, p. VI-9.
Attachment D to the 2015 Supplement includes an updated RACM/RACT
analysis with additional information on RACM for ammonia sources. The
2015 Supplement also states that the District will further evaluate
Rule 1115 and Rule 1168, and notes that Rule 1130 was recently amended
to address the applicable CTG. See 2015 Supplement, Attachment D, Table
D-1 on p. D-5.
    According to the District, several of the requirements in South
Coast Rule 1115, Motor Vehicle Assembly Line Coating Operations, are
not as stringent as the recommendations in the 2008 EPA CTG for a few
coating processes emitting >15 lbs/day. The two facilities subject to
Rule 1115, however, have very small emissions, a total of about 0.02
tpd of VOC.\31\ See 2015 Supplement, Attachment D, page D-29. In
December 2009, we approved Rule 1168, Adhesive and Sealant
Applications, as satisfying VOC RACT requirements under CAA section
182(b)(2) (see 74 FR 67821, December 21, 2009). In 2014, the District
amended South Coast Rule 1130, Graphic Arts, to reduce fountain
solution VOC content to 16-85 g/L with optional control device
efficiency of 90-95%, consistent with the EPA's current CTG
recommendations. On July 14, 2015, the EPA approved the revised South
Coast Rule 1130 as satisfying VOC RACT requirements under CAA section
182(b)(2). (See 80 FR 40915.)
---------------------------------------------------------------------------

    \31\ We note that 0.02 tpd is about 0.0044 percent of the total
VOC inventory of 451 tpd for 2014. See section II.A of the TSD. See
email correspondence from Joseph Cassmassi, SCAQMD, to Stanley Tong,
US EPA Region 9, dated November 25, 2014 in the docket for today's
action.
---------------------------------------------------------------------------

    The RACM analyses and demonstrations conducted by CARB and SCAG for
transportation and mobile source control measures are included in
Appendix IV-C and its Attachment as well as the Attachment to Appendix
VI of the 2012 PM2.5 Plan. CARB has unique authority under
the CAA to adopt standards for most categories of on- and off-road
engines and vehicles, subject in most instances to a waiver or
authorization by EPA under CAA section 209. The State of California has
been a leader in the development of some of the most stringent control
measures nationwide for on-road and off-road mobile sources and the
fuels that power them. As part of its 2007 State Strategy as revised in
2009 and 2011 to support attainment plans in California for
PM2.5 and 8-hour ozone, CARB undertook an extensive public
consultation process to identify potential SIP measures. New measures
adopted by CARB focused on cleaning up the in-use fleet, and increasing
the stringency of emissions standards for a number of engine
categories, fuels, and consumer products. CARB continues to expand its
mobile source program to further reduce emission of direct
PM2.5 and PM2.5 precursors. For example, in
January 2012, CARB adopted the Advanced Clean Car program.\32\
---------------------------------------------------------------------------

    \32\ See 78 FR 2112 (January 9, 2013).
---------------------------------------------------------------------------

    SCAG focused its analysis on transportation control measures (TCMs)
in the 2012-2035 Regional Transportation Plan/Sustainable Communities
Strategy (RTP/SCS), and the analysis and results are described in
Appendix IV-C of the 2012 PM2.5 Plan, ``Regional
Transportation Strategy and Control Measures.'' This evaluation
considered transportation-related measures identified in section 108(f)
of the CAA and measures adopted in other nonattainment areas of the
country. SCAG provided a justification for measures that were
determined to be infeasible for implementation in the South Coast
nonattainment area. See 2012 PM2.5 Plan, Appendix IV-C.
    The inventory for ammonia, provided in Appendix V of the 2012
PM2.5 Plan, indicates that the largest sources of ammonia
include fuel combustion, waste disposal, miscellaneous sources,
industrial sources, livestock, composting, domestic pets, and on-road
mobile emissions. See Table 2 below (referencing 2012 PM2.5
Plan at Appendix V, page V-4-2). The 2012 PM2.5 Plan and
2015 Supplement identify five measures that control ammonia emissions
sources in the South Coast. The five rules are Rule 223, Emissions
Reduction Permits from Large Confined Animal Feeding Operations
(adopted June 2, 2006); Rule 1105.1, Reductions of PM-10 and Ammonia
Emissions from Fluid Catalytic Cracking Units (adopted November 7,
2003); Rule 1127, Emissions Reductions from Livestock Waste (adopted
August 6, 2004); Rule 1133.2, Emission Reductions from Co-Composting
Operations (adopted January 10, 2003); and Rule 1133.3, Emission
Reductions from Greenwaste Composting Operations (adopted July 8,
2011).

        Table 2--South Coast Ammonia Emissions Inventory for 2008
                                  [tpd]
------------------------------------------------------------------------
                                                               Ammonia
                      Source category                         emissions
------------------------------------------------------------------------
Livestock..................................................         18.6
Soil.......................................................          1.8
Domestic...................................................         25.1
Landfill...................................................          3.6
Composting.................................................         17.8
Fertilizer.................................................          1.5
Sewage Treatment...........................................          0.2
Wood Combustion............................................          0.1
Industrial.................................................         20.2
On-Road Mobile.............................................         19.9
Off-road Mobile............................................          0.1
                                                            ------------
    Total..................................................        108.9
------------------------------------------------------------------------
Source: 2012 PM2.5 Plan, Appendix V, Table V-4-2.

     Rule 223, Emissions Reduction Permits from Large Confined
Animal Feeding Operations (LCAF), is a work practice rule to control
VOC and ammonia emissions from LCAFs. It requires operators and/or
owners to implement management practices (e.g., feed according to
National Research Council of the National Academy of Sciences
guidelines, clean manure from corrals at least four times per year,
land incorporate manure within 72-hours of removal, and allow liquid
manure to stand in field no more than 24 hours after irrigation) for
different components of the CAF operation, such as feeding, milking
parlors, housing/bedding, manure management and land application.
    The EPA approved Rule 223 into the SIP on July 13, 2015 (see 80 FR
39966).
     Rule 1105.1, Reductions of PM10 and Ammonia
Emissions from Fluid Catalytic Cracking Units (FCCU), is designed to
limit PM10 and ammonia emissions from fluid catalytic
cracking units at oil refineries. The rule sets emission limits for
PM10 and ammonia slip that result from the combination of
FCCU emissions and ammonia injection used with electrostatic
precipitators (ESP) to control FCCU emissions. Once in the atmosphere,
ammonia emissions react with other compounds to produce secondary PM.
The rule requires oil refineries to implement control technologies to
meet the emissions limits including but not limited to dry and wet
ESPs, sulfur oxide reducing agents, selective catalytic reduction,
selective non-catalytic reduction, and wet gas scrubbers. The EPA
approved this rule into the SIP on January 4, 2006 (see 71 FR 241).
     Rule 1127, Emissions Reductions from Livestock Waste,
requires dairies (and other types of dairy-cattle

operations) to implement specific best management practices for manure
management and disposal, and sets requirements for approving a facility
as a manure processing operation. Specific requirements for ammonia
include cleaning manure from corrals at least four times a year,
disposing of manure only at approved manure processing operations, and
applying it on agricultural land approved for that purpose. The EPA
approved this rule into the SIP on May 23, 2013 (see 78 FR 30768).
     Rule 1133.2, Emission Reductions from Co-Composting
Operations, requires all new or existing co-composting operations to
compost in an enclosure that meets certain technical requirements
(e.g., inward face velocity of air through each opening shall be at
least 100 feet per minute unless the opening contains closure seals),
cure using an aeration system operating under negative pressure for no
less than 90 percent of blower operating cycle, and vent the exhaust to
an emission control system with a control efficiency for both VOC and
ammonia of at least 80 percent, by weight, or submit a compliance plan
for new operations that demonstrates an overall emission reduction for
both VOC and ammonia of 80 percent, by weight, based on emission
factors specified in the rule. For existing operations, the required
emission reduction is 70 percent, by weight, for both ammonia and VOC.
Rule 1133.2 also specifies required compliance plan elements. The EPA
approved this rule into the SIP on July 21, 2004 (see 69 FR 43518).
     Rule 1133.3, Emission Reductions from Greenwaste
Composting Operations, requires all new or existing greenwaste
(includes foodwaste) composting facilities to cover, water and turn
active phase compost piles according to specific requirements (e.g.,
cover for seven days, turn only when top of pile is sufficiently wet,
based on test method) to minimize VOC and ammonia emissions. If total
foodwaste throughput exceeds 5,000 tons per year, any active pile with
more than 10 percent foodwaste must be controlled by a device with an
overall system control efficiency of 80 percent, by weight, each for
VOC and ammonia emissions. The EPA approved this rule into the SIP on
November 29, 2012 (see 77 FR 71129).
    In addition, for livestock waste, the 2012 PM2.5 Plan
and 2015 Supplement indicate the District will evaluate control measure
BCM-04, Further Ammonia Reductions from Livestock Waste, as a potential
ammonia control measure. Phase I of this control measure, scheduled for
the 2015-2016 timeframe, involves a technology assessment. The
technology assessment will evaluate the technical and economic
feasibility of applying sodium bisulfate (SBS) at local dairies in the
South Coast. SBS application has been shown to be an effective method
for reducing ammonia from fresh manure. (See 2012 PM2.5
Plan, Appendix IV, page IV-A-32). The 2015 Supplement states that rule
development will follow if controls are determined to be technically
feasible and cost-effective. See 2015 Supplement, page F-1 and Table F-
1.
    We are proposing to reclassify the South Coast from Moderate to
Serious nonattainment for the 2006 PM2.5 standard. A final
reclassification to Serious will trigger the requirement in CAA section
189(b)(1)(B) for the submittal of a SIP providing for the
implementation of Best Available Control Measures (BACM),\33\ among
other things, within 18 months. As part of the District's development
of a BACM control strategy for direct PM2.5 and those
precursors subject to evaluation for potential controls in the South
Coast (NOX, SO2, VOC, and ammonia), we encourage
the District to consider additional measures previously identified by
the EPA and the public in comments on the 2012 PM2.5 Plan,
2015 Supplement, and other individual rules and plans, as well as other
potential innovative measures for reducing emissions. As part of this
process, we suggest that the District consult with other state/local
agencies and environmental and industry stakeholders.
---------------------------------------------------------------------------

    \33\ The EPA defines BACM as, 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. See Addendum at 42010,
42014. BACM must be implemented for all categories of sources in a
serious PM2.5 nonattainment area unless the State
adequately demonstrates that a particular source category does not
contribute significantly to nonattainment of the PM2.5
standard. See id. At 42011, 42012.
---------------------------------------------------------------------------

Condensable Fraction of Direct PM2.5 Emissions
    EPA's 2007 PM2.5 implementation rule states that
``[a]fter January 1, 2011, for purposes of establishing emissions
limits under 51.1009 and 51.1010, States must establish such limits
taking into consideration the condensable fraction of direct
PM2.5 emissions.'' 40 CFR 51.1002(c). The South Coast 2012
PM2.5 Plan and 2015 Supplement rely on several SIP-approved
rules regulating direct PM emissions as part of the PM2.5
control strategy (e.g., Wood Burning Fireplaces (Rule 445, adopted
March 7, 2008, most recently revised May 3, 2013), Wood Stoves and
Under-Fired Charbroilers (Rule 1138, adopted November 14, 1997), and
Particulate Matter (PM) Control Devices (Rule 1155, adopted December 4,
2009)). See 2015 Supplement, Attachment F, Table F-1 and letter dated
July 25, 2014 transmitting South Coast Rule 1155 to EPA. As part of our
action on any rules that regulate direct PM2.5 emissions, we
evaluate the emission limits in the rule to ensure that they
appropriately address CPM, as required by 40 CFR 51.1002(c). We note
that the SIP-approved version of Rule 1138 requires testing according
to the District's Protocol, which requires measurement of both
condensable and filterable PM in accordance with SCAQMD Test Method
5.1. See Rule 1138 (adopted Nov. 14, 1997, approved July 11, 2011, see
66 FR 36170), paragraph (c)(1) and (g) and SCAQMD Protocol paragraph
3.1.\34\ We also note that the SIP-approved version of Rule 1155
requires measurement of both condensable and filterable PM in
accordance with SCAQMD Test Methods 5.1, 5.2, or 5.3 as applicable. See
Rule 1155 (adopted Dec. 4, 2009, approved March 16, 2015, see 80 FR
13495), paragraph (e)(6).\35\
---------------------------------------------------------------------------

    \34\ See SCAQMD Protocol, Determination of Particulate and
Volatile Organic Compound Emissions from Restaurant Operations,
November 14, 1997 (available at http://yosemite.epa.gov/R9/
R9Testmethod.nsf/0/3D4DEB4D21AB4AAF882570AD005DFF69/$file/
SC%20Rest%20emiss.pdf).
    \35\ See SCAQMD Test Method 5.1, Determination of Particulate
Matter Emissions from Stationary Sources Using a Wet Impingement
Train, March 1989; SCAQMD Test Method 5.2, Determination of
Particulate Matter Emissions from Stationary Sources Using Heated
Probe and Filter, March 1989; and SCAQMD Test Method 5.3,
Determination of Particulate Matter Emissions from Stationary
Sources Using an in-Stack Filter, October 2005.
---------------------------------------------------------------------------

3. Evaluation and Proposed Action
    We find that the process followed in the 2012 PM2.5 Plan
and 2015 Supplement to identify RACM/RACT is generally consistent with
the EPA's recommendations in the General Preamble. The process included
compiling a comprehensive list of potential control measures for
sources of direct PM2.5, NOX, VOC,
SO2, and ammonia in the South Coast. This list included
measures suggested in public comments on the Plan. See 2012
PM2.5 Plan, Appendices VI and IV-C. As part of this process,
the District, CARB, and SCAG evaluated potential controls for all
relevant source categories for economic and technological feasibility,
and provided justifications for the rejection of certain identified
measures. Id. After completing this evaluation, the District stated its
intent to analyze

potential rule improvements with respect to rules 1115, 1130, and 1168.
See 2012 PM2.5 Plan, Chapter 4 and Appendices VI, IV-A, and
IV-C, and 2015 Supplement, Attachment D. Since submittal of the 2012
PM2.5 Plan in February 2013, the District has strengthened,
adopted and submitted Rule 1130, which EPA approved on July 14, 2015
(see 80 FR 40915). EPA approved Rule 1168 as satisfying VOC RACT on
December 21, 2009 (see 74 FR 67821). With respect to Rule 1115, as
noted above, the emissions inventory for these sources is very small.
    We have reviewed the District's determination in the 2012
PM2.5 Plan and 2015 Supplement that its stationary and area
source control measures represent RACM/RACT for direct
PM2.5, NOX, VOC, ammonia and SO2. Our
rulemaking actions on District rules generally provide the bases for
our conclusions that the emission limits and/or other control
requirements in the rules represent a RACT level of control, at
minimum, for the relevant source categories.\36\ We also reviewed the
potential additional control measures that the District considered,
including those identified by public commenters during the State/
District rulemaking processes, and believe that the District adequately
justified its conclusions with respect to each of these measures.
---------------------------------------------------------------------------

    \36\ A full list of the District's rules, including citations to
our most recent action on each rule can be found in Appendix A to
this TSD.
---------------------------------------------------------------------------

    Finally, we have reviewed the analysis of current and potentially
available controls for both on-road and off-road mobile sources in
Appendices IV-C and VI, as well as the Attachment to Appendix VI. As we
have noted in previous actions on South Coast plans,\37\ California is
a leader in the development and implementation of stringent control
measures for on-road and off-road mobile sources. Its current program
addresses the full range of mobile sources in the South Coast through
regulatory programs for both new and in-use vehicles and through
incentive grant programs. See 2012 PM2.5 Plan, Appendix III,
Table III-1-3. The District has also adopted measures to reduce
emissions from mobile sources including its Surplus Opt-in for
NOX (SOON) rule (Rule 2449) and on-road mobile sources
including its employer trip reduction rule (Rule 2202) and has a well-
funded incentive grants program focused on mobile sources. See 2012
PM2.5 Plan, Chapter 4. Overall, we believe that the State,
District, and MPO programs provide for the implementation of RACM for
emissions of direct PM2.5 and PM2.5 precursors
from mobile sources in the South Coast.
---------------------------------------------------------------------------

    \37\ See the proposed approvals of the South Coast 2007 [8-hour]
Ozone Plan at 76 FR 57872, 57879 (September 16, 2011) and the 2007
AQMP addressing the 1997 PM2.5 NAAQS at 76 FR 41562.
41570 (July 14, 2011).
---------------------------------------------------------------------------

    For the foregoing reasons, we propose to find that the 2012
PM2.5 Plan and 2015 Supplement provide for the
implementation of all RACM/RACT that can be implemented prior to the
applicable Moderate area attainment date as required by CAA sections
189(a)(1)(C) and 172(c)(1), and to approve the RACM/RACT demonstration
in the South Coast 2012 PM2.5 Plan and 2015 Supplement.\38\
---------------------------------------------------------------------------

    \38\ The 2012 PM2.5 Plan is the latest in a series of
air quality plans and control strategies that the District, CARB and
SCAG have developed to provide for attainment of the NAAQS in the
South Coast. These plans include the 2003 PM10 Plan
(approved 70 FR 69081 (November 14, 2005)); the 2003 Extreme [1-
hour] Ozone Attainment Plan (approved 74 FR 10176 (March 8, 2009);
the 2007 [8-hour] Ozone Plan (approved 77 FR 12674 (March 1, 2012));
the 2007 State Strategy for the 1997 Ozone and PM2.5
standards (approved 76 FR 69928 (November 9, 2011)); the 2007
PM2.5 SIP as revised in 2009 and 2011 (approved 66 FR
69928 (November 9, 2011)); and the RACT SIP submitted in 2007
(approved 73 FR 76947 (December 18, 2008)). In each of our
rulemakings on these Plans, we approved a RACM and/or RACT
demonstration that addressed one or more PM2.5
precursors.
---------------------------------------------------------------------------

E. Major Stationary Source Control Requirements Under CAA Section
189(e)

    CAA section 189(e) specifically requires that the control
requirements applicable to major stationary sources of direct
PM2.5 also apply to major stationary sources of
PM2.5 precursors, except where the Administrator determines
that such sources do not contribute significantly to PM2.5
levels that exceed the standard in the area (see General Preamble at
13539 and 13541 to 42). The control requirements applicable to major
stationary sources of direct PM2.5 and PM2.5
precursors in a Moderate PM2.5 nonattainment area include,
at minimum, the requirements of a nonattainment new source review
(NNSR) permit program meeting the requirements of CAA section 172(c)(5)
(see CAA 189(a)(1)(A)).
    In a separate rulemaking to approve revisions to SCAQMD's NNSR
permit program, the EPA evaluated the District's discussion of control
requirements applicable to major stationary sources (Attachment E of
the 2015 Supplement) and determined that the District's SIP-approved
NNSR program satisfies the requirements of CAA section 189(e) for
direct PM2.5 and all PM2.5 precursors.\39\
Accordingly, in this action, the EPA is not addressing the NNSR control
requirements that apply to major stationary sources of direct
PM2.5 and PM2.5 precursors in the South Coast
area under CAA section 189(e).
---------------------------------------------------------------------------

    \39\ See n. 29, supra.
---------------------------------------------------------------------------

F. Adopted Control Strategy

1. Requirements for Control Strategies
    CAA section 110(a)(2)(A) provides that each SIP ``shall include
enforceable emission limitations and other control measures, means or
techniques . . . as well as schedules and timetables for compliance, as
may be necessary or appropriate to meet the applicable requirement of
the Act.'' Section 172(c)(6) of the Act, which applies to nonattainment
area SIPs, is virtually identical to section 110(a)(2)(A).\40\ Measures
necessary to meet RACM/RACT and the additional control requirements
under section 172(c)(6) must be adopted by the State in an enforceable
form (General Preamble at 13541) and submitted to the EPA for approval
into the SIP under CAA section 110.
---------------------------------------------------------------------------

    \40\ The language in sections 110(a)(2)(A) and 172(c)(6) is
quite broad, allowing a SIP to contain any enforceable ``means or
techniques'' that EPA determines are ``necessary or appropriate'' to
meet CAA requirements, such that the area will attain as
expeditiously as practicable, but no later than the designated date.
Furthermore, the express allowance for ``schedules and timetables''
demonstrates that Congress understood that all required controls
might not be in place when a SIP is approved.
---------------------------------------------------------------------------

    Commitments approved by the EPA under CAA section 110(k)(3) are
enforceable by the EPA and citizens under CAA sections 113 and 304,
respectively. In the past, the EPA has approved enforceable commitments
and courts have enforced actions against states that failed to comply
with them.\41\ Additionally, if a state fails to meet its commitments,
the EPA may make a finding of failure to implement the SIP under CAA
section 179(a)(4), which starts an 18-month period for the state to
correct the non-implementation before mandatory sanctions are imposed.
---------------------------------------------------------------------------

    \41\ E.g., American Lung Ass'n of N.J. v. Kean, 670 F. Supp.
1285 (D.N.J. 1987), aff'd, 871 F.2d 319 (3rd Cir. 1989); NRDC, Inc.
v. N.Y. State Dept. of Env. Cons., 668 F. Supp. 848 (S.D.N.Y. 1987);
Citizens for a Better Env't v. Deukmejian, 731 F. Supp. 1448, recon.
granted in par, 746 F. Supp. 976 (N.D. Cal. 1990); Coalition for
Clean Air v. South Coast Air Quality Mgt. Dist., No. CV 97-6916-HLH,
(C.D. Cal. Aug. 27, 1999).
---------------------------------------------------------------------------

    Once the EPA determines that circumstances warrant use of an
enforceable commitment, the EPA considers three factors in determining
whether to approve the use of an enforceable commitment to meet a CAA
requirement: (a) Does the commitment address a limited portion of the
CAA-required program; (b) is the state

capable of fulfilling its commitment; and (c) is the commitment for a
reasonable and appropriate period of time.\42\
---------------------------------------------------------------------------

    \42\ The U.S. Court of Appeals for the Fifth Circuit upheld the
EPA's interpretation of CAA section 110(a)(2)(A) and 172(c)(6) and
the Agency's use and application of the three factor test in
approving enforceable commitments in the Houston-Galveston ozone SIP
in BCCA Appeal Group et al. v. EPA et al., 355 F.3d 817 (5th Cir.
2003).
---------------------------------------------------------------------------

2. Control Strategy in the 2012 PM2.5 Plan and 2015
Supplement
    For purposes of evaluating the 2012 PM2.5 Plan and 2015
Supplement, we have divided the measures relied on to satisfy the
applicable control requirements into two categories: Baseline measures
and control strategy measures.
    As the term is used here, baseline measures are federal, State, and
District rules and regulations adopted prior to June of 2012 for
District rules, and prior to August of 2011 for CARB rules (i.e., prior
to the development of 2012 PM2.5 Plan) that continue to
achieve emissions reductions through the current attainment year of
2015 and beyond.\43\ The Plan describes many of these measures in
Chapter 4 and in Appendices III, IV-B, IV-C and VI. Reductions from
these baseline measures are incorporated into the baseline inventory
and reductions from the District measures in the plan are individually
quantified in Appendix III, Table III-2-2B. According to the Plan,
these measures provide most of the emissions reductions projected to
occur between the base year of 2008 and the Moderate area attainment
date of 2015. See 2012 PM2.5 Plan, Chapter 4, and Appendix
V, and 2015 Supplement Attachment A; see also Appendix A of the TSD.
---------------------------------------------------------------------------

    \43\ These measures are typically rules that have compliance
dates that occur after the adoption date of a plan and mobile source
measures that achieve reductions as older engines are replaced
through attrition (e.g., through fleet turnover).
---------------------------------------------------------------------------

    Control strategy measures are the new rules, rule revisions,
commitments, and other measures that provide the additional increment
of emissions reductions needed beyond the baseline measures to provide
for attainment (when applicable), to demonstrate RFP, to meet the RACM/
RACT requirement, or to provide for contingency measures.
    The District included several new measures in the 2012
PM2.5 Plan and 2015 Supplement to provide for attainment of
the 2006 PM2.5 NAAQS. First, the District committed to
adopt, submit, and implement amendments to two District rules (Rule 444
and Rule 445) to reduce direct PM2.5 emissions from open
burning and residential wood burning activities. See 2012
PM2.5 Plan, p. 4-8, Table 4-2 and SCAQMD Governing Board
Resolution 12-19 (Dec. 7, 2012), p. 8, as revised by 2015 Supplement,
Attachment F, Table F-1 and SCAQMD Governing Board Resolution 15-2
(Feb. 19, 2015). Second, the District committed to achieve 11.7 tpd of
direct PM2.5 emission reductions by 2015, either from these
two amended rules or from substitute measures as necessary to address
any shortfall in emission reductions. Id. Third, the District committed
to carry out technology assessments to address emissions from under-
fired charbroilers and livestock waste in 2015-2016 and 2017,
respectively. Id. Finally, the District committed to adopt revisions to
its NOX RECLAIM program to achieve an additional 2 tpd of
NOX emission reductions in 2015, as a contingency measure,
and to adopt backstop measures related to ports and port-related
facilities in 2015. Id. Following the State's submittal of the 2012
PM2.5 Plan to the EPA in 2013, the District adopted
amendments to Rule 444 and Rule 445 and on June 11, 2013, the District
submitted these revised rules to the EPA for SIP approval, consistent
with its commitments in the Plan. These measures and commitments are
listed in Table 3 below.

                    Table 3--SCAQMD 2012 PM2.5 Plan and 2015 Supplement Specific Commitments
----------------------------------------------------------------------------------------------------------------
                                                                            Implementation         Emission
      Rule No.        Measure number and description     Adoption date           date             reductions
----------------------------------------------------------------------------------------------------------------
444.................  Further Reductions from Open    2013...............              2013  4.6 tpd PM2.5
                       Burning \44\.
445.................  Further Reductions from         2013...............              2013  7.1 tpd PM2.5
                       Residential Wood Burning \45\.
1138................  Emissions Reductions from       2017...............               N/A  TBD
                       Under-fired Charbroilers.
1127................  Further Ammonia Emissions From  2015-2016                         N/A  TBD
                       Livestock Waste.                Technology
                                                       Assessment.
2002................  Further NOX Reductions from     2015...............               N/A  2 tpd NOX
                       RECLAIM.
4001................  Backstop Measures for Indirect  2015...............               N/A  N/A
                       Sources of Emissions from
                       Ports and Port-related
                       Facilities.
----------------------------------------------------------------------------------------------------------------
Source: 2012 PM2.5 Plan, Chapter 4, Table 4-2, as amended by 2015 Supplement, Attachment F, Table F-1.

3. Evaluation and Conclusions
    The Plan provides for the majority of the emissions reductions
necessary for attainment to be achieved from baseline measures. These
reductions come from a combination of District, State and federal
stationary and mobile source measures.\46\ Over the past four decades,
the District has adopted or revised almost 100 prohibitory rules that
limit emissions of NOX, SO2, ammonia, VOC, and
particulate matter from stationary sources. See Appendix A of this TSD.
The vast majority of these rules are currently SIP-approved and as
such, their emissions reductions are fully creditable in attainment-
related SIPs. The District's most recent amendments to Rule 444 and
Rule 445 further tighten the District's control strategy for direct
PM2.5 emissions. California has also adopted standards for
many categories of on- and off-road vehicles and engines as well as
standards for gasoline and diesel fuels.
---------------------------------------------------------------------------

    \44\ Approved on September 26, 2013, see 78 FR 59249.
    \45\ Ibid.
    \46\ These federal measures include EPA's national emissions
standards for heavy duty diesel trucks (66 FR 5001 (January 18,
2001)), certain new construction and farm equipment (Tier 2 and 3
non-road engines standards, 63 FR 56968 (October 23, 1998) and Tier
4 diesel non-road engine standards, 69 FR 38958 (June 29, 2004)),
and locomotives (63 FR 18978 (April 16, 1998) and 73 FR 37045 (June
30, 2008)). States are allowed to rely on reductions from federal
measures in attainment and RFP demonstrations and for other SIP
purposes.
---------------------------------------------------------------------------

    The State's mobile source measures fall into two categories:
Measures for which the State has obtained or has applied to obtain a
waiver of federal pre-emption under CAA section 209 (``section 209
waiver measures'' or ``waiver measures'') and those for which the State
is not required to obtain a waiver (``non-waiver measures'' or ``SIP
measures'').
    Under the CAA, the EPA is charged with establishing national
emission limits for mobile sources. States are

generally preempted from establishing such limits except for
California, which can establish these limits subject to EPA waiver or
authorization under CAA section 209 (referred to herein as ``waiver
measures''). Over the years, the EPA has issued waivers or
authorizations for many mobile source regulations adopted by CARB.
California attainment and maintenance plans rely on emissions
reductions from implementation of the waiver measures through use of
emissions models such as EMFAC, and the South Coast 2012
PM2.5 Plan is no exception.
    Historically, the EPA has allowed California to take credit for
such ``waiver'' measures even though the waiver measures themselves
(i.e., CARB's regulations) have not been adopted and approved as part
of the California SIP. However, a recent decision by the Ninth Circuit
Court of Appeals held that EPA's longstanding practice in this regard
was at odds with the CAA requirement that state and local emissions
limits relied upon to meet the NAAQS be enforceable by the EPA or
private citizens through adoption and approval of such limits in the
SIP.\47\
---------------------------------------------------------------------------

    \47\ See Committee for a Better Arvin v. EPA, 786 F.3d 1169 (9th
Cir. 2015).
---------------------------------------------------------------------------

    In response to the court's decision, CARB has adopted the necessary
waiver measures as revisions to the California SIP and submitted them
to EPA for approval.\48\ EPA intends to propose action on these waiver
measures in a separate rulemaking. Once approved as part of the SIP,
the measures will be enforceable by the EPA or private citizens under
the CAA. In today's action, the EPA is proposing to approve certain
elements of the 2012 PM2.5 Plan and 2015 Supplement in part
based on our expectation that these waiver measures will soon become
federally enforceable as a result of our approval of the measures as
part of the SIP.
---------------------------------------------------------------------------

    \48\ See letter dated August 14, 2015, from Richard W. Corey,
Executive Officer, California Air Resources Board, to Jared
Blumenfeld, Regional Administrator, EPA Region 9.
---------------------------------------------------------------------------

    Non-waiver measures include improvements to California's inspection
and maintenance (I/M) program, SmogCheck, and cleaner burning gasoline
and diesel regulations as well as the District's stationary source and
mobile source rules. See TSD at Appendix A for a list of District rules
and EPA actions on them.
    As discussed above, we generally consider three factors in
determining whether to approve the use of enforceable commitments to
meet a CAA requirement. In this case, however, the 2012
PM2.5 Plan and 2015 Supplement do not rely on either the
rule amendment commitments or the emission reduction commitments in its
impracticability demonstration, RACM demonstration, RFP demonstration,
or quantitative milestones, or to meet any other CAA requirement.
Therefore, we do not need to apply this three-factor test before
proposing to approve the District's commitments into the SIP. Approval
of these commitments will strengthen the SIP and contribute to the
SIP's purpose of ``eliminating or reducing the severity and number of
violations of the [PM2.5 NAAQS] and achieving expeditious
attainment of such standards.'' See CAA 176(c)(1)(A).
    We are proposing to approve the District's commitments to adopt and
implement specific control measures identified in Table 4-2 in the
South Coast 2012 AQMP (as amended March 4, 2015 by Table F-1 in
Attachment F of the 2015 Supplement) and to achieve specified
NOX emission reductions, to the extent that these
commitments have not yet been fulfilled. Specifically, we are proposing
to approve the District's commitments to: (1) Carry out a technology
assessment to address emissions from under-fired charbroilers by 2017,
(2) conduct a technology assessment for livestock waste by 2016, (3)
adopt revisions to its NOX RECLAIM program or other
enforceable control measures to achieve an additional 2 tpd of
NOX emission reductions in 2015, and (4) adopt backstop
measures for indirect sources of emissions from ports and port-related
facilities. See 2012 PM2.5 Plan, p. 4-8, Table 4-2 and
SCAQMD Governing Board Resolution 12-19 (Dec. 7, 2012), pp. 7-8, as
revised by 2015 Supplement, Attachment F, Table F-1 and SCAQMD
Governing Board Resolution 15-2 (Feb. 19, 2015), pp. 2-3.
    With respect to the commitments to adopt Rules 444 and 445 and to
achieve 11.7 tpd of direct PM2.5 emission reductions, the
District has satisfied these commitments by submitting the fully
adopted rules to EPA on June 11, 2013, together with technical
documentation to support its conclusion that these rules will achieve
11.7 tpd of direct PM2.5 emission reductions in 2015.\49\
The EPA approved Rule 444 and Rule 445 on September 26, 2013 (see 79 FR
59249).\50\
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    \49\ See ``Rule Evaluation Form,'' South Coast Rules 444 and
445, and South Coast Air Quality Management District, Draft Final
Staff Report, Proposed Amended Rule 445--Wood-Burning Devices,
Proposed Amended Rule 444--Open Burning, May 2013, pp. 15-16.
    \50\ See letter dated June 11, 2013, from Edie Chang, Deputy
Executive Officer, California Air Resources Board, to Jared
Blumenfeld, Regional Administrator, EPA Region 9, transmitting South
Coast Rules 444 and 445.
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G. Demonstration That Attainment by the Moderate Area Attainment Date
is Impracticable

1. Requirements for Attainment/Impracticability of Attainment
Demonstrations
    CAA section 189(a)(1)(B) requires that each Moderate area
attainment plan include a demonstration that the plan provides for
attainment by the latest applicable Moderate area deadline or,
alternatively, that attainment by the latest applicable attainment date
is impracticable. A demonstration that the plan provides for attainment
must be based on air quality modeling, and the EPA generally recommends
that a demonstration of impracticability also be based on air quality
modeling consistent with EPA's modeling guidance (General Preamble at
13538).\51\
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    \51\ For more information on the CAA's air quality modeling
requirements, please see section II.B of the TSD.
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    CAA section 188(c) states, in relevant part, that the Moderate area
attainment date ``shall be as expeditiously as practicable but no later
than the end of the sixth calendar year after the area's designation as
nonattainment. . . .'' For the South Coast area, which was initially
designated as nonattainment for the 2006 PM2.5 standard
effective December 14, 2009, the applicable Moderate area attainment
date under section 188(c) is as expeditiously as practicable but no
later than December 31, 2015.
    In SIP submissions to demonstrate impracticability, the State
should document that its required control strategy in the attainment
plan represents the application of RACM/RACT to existing sources. The
EPA believes it is appropriate to require adoption of all available
control measures that are reasonable (i.e., technologically and
economically feasible) in areas that do not demonstrate timely
attainment, even where those measures cannot be implemented within the
4-year timeframe for implementation of RACM under CAA section
189(a)(1)(C). The impracticability demonstration will then be based on
a showing that the area cannot attain by the applicable attainment
date, notwithstanding implementation of the required controls.
2. Impracticability Demonstration for the 2012 PM2.5 Plan
and 2015 Supplement
    By letter dated July 28, 2015, the District requested that the EPA
reclassify the South Coast Air Basin to

``Serious'' for the 2006 PM2.5 NAAQS. The letter provided
preliminary 2015 air quality monitoring data for the Mira Loma
monitoring station supporting a conclusion that attainment of the 2006
PM2.5 standard by December 31, 2015 in the South Coast is
impracticable.\52\
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    \52\ See letter dated July 28, 2015, from Barry R. Wallerstein,
Executive Officer, SCAQMD, to Elizabeth Adams, Acting Director, Air
Division, US Environmental Protection Agency, Region 9.
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    Based in part on the information contained in this letter and in
the 2012 PM2.5 Plan and Supplement, we have conducted an
analysis of recent PM2.5 monitoring data for the South Coast
PM2.5 nonattainment area.\53\ For this analysis, the EPA
used certified data for 2013, 2014 and preliminary data available for
2015.\54\ Although the State and District originally intended for the
2012 PM2.5 Plan and 2015 Supplement to demonstrate that the
area would attain the 2006 PM2.5 NAAQS by the Moderate area
attainment date of December 31, 2015, more recent monitoring data show
that 24-hour PM2.5 levels in the South Coast, with a current
design value (2012-2014) of 38 [micro]g/m\3\ at the Mira Loma
monitoring site, continue to be above the 35 [micro]g/m\3\ level of the
2006 PM2.5 standard, and the recent trends in the South
Coast's 24-hour PM2.5 levels are not consistent with a
projection of attainment by the end of 2015.
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    \53\ See Memorandum dated August 21, 2015 from Michael Flagg,
U.S. EPA, Region 9 Air Quality Analysis Office, to South Coast
Docket EPA-R09-OAR-2015-0204, Subject: Practicability of South Coast
2015 Attainment of the 2006 24-hour PM NAAQS (``Flagg Memo'').
    \54\ Some data in the 2nd, 3rd, and 4th quarter of 2014 may have
been impacted by a temporary lab closure and other issues at SCAQMD
and are under current review. As a precautionary measure, we
conducted an additional analysis on the impracticability of
attaining by December 31, 2015 that completely excluded these data.
The outcome of the analysis further supported the impracticability
of attainment by the applicable attainment date. See Attachment to
Flagg Memo, under ``24-hour practicability'' tab.
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    The EPA calculated the maximum allowed 2015 concentrations for all
monitors in the area, and compared them to the estimated 2015 98th
percentile. If the estimated 2015 98th percentile was greater than the
maximum allowed 2015 98th percentile concentration, the EPA considered
attainment at that monitoring site impracticable. For each monitor, the
EPA estimated the 2015 98th percentile from the 2015 data available in
AQS as of August 2015, based a number of assumptions.\55\ The EPA
assumed that the concentrations measured during the remainder of 2015
would be no higher than those already recorded, so the 98th percentile
could be chosen from among the already recorded data. This is a
conservative assumption for assessing the impracticability of
attainment, since future concentrations and 98th percentiles could be
higher than recorded values.
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    \55\ EPA also assumed that the sampling rate observed so far
would continue throughout the year; this yielded an estimate of the
number of total samples expected for 2015, and allowed for selection
of the corresponding rank of the daily data available to use as the
98th percentile in accordance with 40 CFR part 50, appendix N,
section 4.5.
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    The EPA's analysis showed that during 2015, two monitoring sites
(Rubidoux and Mira Loma-Van Buren) had estimated 98th percentiles
greater than the maximum allowed 98th percentile concentration for
2015, which indicates that attainment of the 2006 24-hour
PM2.5 NAAQS by the end of 2015 is impracticable.
    In a separate analysis, EPA assumed that Rubidoux and Mira Loma-Van
Buren collected a minimum of 351 daily samples (i.e. consistent with an
everyday sampling frequency) in 2015, which would allow for selection
of the 8th highest recorded value as the 98th percentile for 2015. This
assumption resulted in selection of the lowest 98th percentile value
possible for 2015, making the analysis more conservative than the
previous approach. Even under this assumption, both Rubidoux and Mira
Loma-Van Buren had estimated 2015 98th percentiles greater than the
maximum allowed 2015 98th percentile.
3. Evaluation and Proposed Action
    Our conservative assessment of recent PM2.5 air quality
data indicates that attainment of the 2006 PM2.5 standard in
the South Coast by December 31, 2015 is impracticable. We have also
evaluated the RACM/RACT demonstration in the 2012 PM2.5 Plan
and 2015 Supplement and find that it provides for the expeditious
implementation of all RACM that may feasibly be implemented at this
time, consistent with the requirements of CAA sections 172(c)(1) and
189(a)(1)(C) for the 2006 PM2.5 NAAQS in the South Coast.
See section II.D of this TSD. Implementation of this RACM/RACT control
strategy appears, however, to be insufficient to bring the South Coast
area into attainment by December 31, 2015.
    Based on this evaluation, we propose to approve the State's
demonstration in the 2012 PM2.5 Plan and 2015 Supplement
that attainment of the 2006 PM2.5 standard by the Moderate
area attainment date in the South Coast is impracticable, consistent
with the requirements of CAA section 189(a)(1)(B)(ii). Based on this
proposal, we propose to reclassify the South Coast as Serious
nonattainment, which would trigger requirements for the State to submit
a Serious area plan consistent with the requirements of subparts 1 and
4 of part D, Title I of the Act (see Section III of this TSD).

H. Reasonable Further Progress and Quantitative Milestones

1. Requirements for Reasonable Further Progress and Quantitative
Milestones
    CAA section 172(c)(2) requires nonattainment area plans to provide
for reasonable further progress (RFP). In addition, CAA section 189(c)
requires PM2.5 nonattainment area SIPs to include
quantitative milestones to be achieved every 3 years until the area is
redesignated to attainment and which demonstrate reasonable further
progress (RFP), as defined in CAA section 171(1). Section 171(1)
defines RFP as ``such annual incremental reductions in emissions of the
relevant air pollutant as are required by [Part D] or may reasonably be
required by the Administrator for the purpose of ensuring attainment of
the applicable [NAAQS] by the applicable date.'' Neither subpart 1 nor
subpart 4 of part D, title I of the Act requires that a set percentage
of emissions reductions be achieved in any given year for purposes of
satisfying the RFP requirement.
    RFP has historically been met by showing annual incremental
emission reductions sufficient generally to maintain at least linear
progress toward attainment by the applicable deadline (Addendum at
42015). As discussed in the Addendum, requiring linear progress in
reductions of direct PM2.5 and any individual precursor in a
PM2.5 plan may be appropriate in situations where:
     The pollutant is emitted by a large number and range of
sources,
     the relationship between any individual source or source
category and overall air quality is not well known,
     a chemical transformation is involved (e.g., secondary
particulate significantly contributes to PM2.5 levels over
the standard), and/or
     the emission reductions necessary to attain the
PM2.5 standard are inventory-wide. Id.
    The EPA's guidance in the Addendum at 42015 recommends that
requiring linear progress is less appropriate in other situations, such
as:
     Where there are a limited number of sources of direct
PM2.5 or a precursor,
     where the relationships between individual sources and air
quality are relatively well defined, and/or
     where the emission control systems utilized (e.g., at
major point sources)

will result in swift and dramatic emission reductions. Id.
    In nonattainment areas characterized by any of these latter
conditions, RFP may be better represented as step-wise progress as
controls are implemented and achieve significant reductions soon
thereafter. For example, if an area's nonattainment problem can be
attributed to a few major sources, EPA guidance indicates that ``RFP
should be met by `adherence to an ambitious compliance schedule' which
is likely to periodically yield significant emission reductions of
direct PM2.5 or a PM2.5 precursor'' (Addendum at
42015).
    Plans for PM2.5 nonattainment areas should include
detailed schedules for compliance with emission regulations in the area
and provide corresponding annual emission reductions to be realized
from each milestone in the schedule (Addendum at 42016). In reviewing
an attainment plan under subpart 4, EPA evaluates whether the annual
incremental emission reductions to be achieved are reasonable in light
of the statutory objective of timely attainment.
    Section 189(c) provides that the quantitative milestones submitted
by a state for an area also must be consistent with RFP for the area.
Thus, the EPA determines an area's compliance with RFP in conjunction
with determining its compliance with the quantitative milestone
requirement. Because RFP is an annual emission reduction requirement
and the quantitative milestones are to be achieved every 3 years, when
a state demonstrates an area's compliance with the quantitative
milestone requirement, it will demonstrate that RFP has been achieved
during each of the relevant 3 years. Quantitative milestones should
consist of elements that allow progress to be quantified or measured.
Specifically, states should identify and submit quantitative milestones
providing for the amount of emission reductions adequate to achieve the
NAAQS by the applicable attainment date (Addendum at 42016).
Implementation of control measures comprising the RFP plan may provide
a means for satisfying the quantitative milestone requirement (see
id.). The Act requires states to include RFP and quantitative
milestones even for areas that cannot practicably attain.
2. RFP Demonstration and Quantitative Milestones in the 2012
PM2.5 Plan and 2015 Supplement
    South Coast's 2012 PM2.5 Plan was originally developed
in accordance with the requirements of subpart 1 and the 2007
PM2.5 Implementation Rule (see 75 FR 20586, April 25, 2007),
which did not require a submittal of a separate RFP plan where the
State submits a plan demonstrating attainment within five years of the
date of designation (see 40 CFR 51.1009(b)). Because the 2012
PM2.5 Plan as originally adopted (in December 2012) included
the State's demonstration of attainment by December 14, 2014, which is
five years from the date of designation,\56\ the Plan does not include
a separate RFP demonstration.
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    \56\ Section 172(a)(2)(A) of the CAA states, in relevant part,
that the attainment date for a nonattainment area ``shall be the
date by which attainment can be achieved as expeditiously as
practicable, but no later than 5 years from the date such area was
designated nonattainment under section [107(d)].'' Because the EPA
designated South Coast as nonattainment for the 2006 24-hour
standard effective December 14, 2009 (74 FR 58688, November 13,
2009), under subpart 1 the area was required to attain this standard
no later than December 14, 2014.
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    Following the D.C. Circuit's January 2013 decision remanding the
2007 PM2.5 Implementation Rule (see NRDC v. EPA, 706 F.3d
428 (D.C. Cir. 2013)) and the EPA's June 2014 promulgation of Moderate
area classifications in the deadline and classifications rule (see 79
FR 31566, June 2, 2014), the District developed the 2015 Supplement to
address the applicable subpart 4 requirements for the 2006
PM2.5 NAAQS. By the time the State and District submitted
this Supplement to EPA in early 2015, less than a year remained before
the December 31, 2015 Moderate area attainment date applicable to the
area under subpart 4, and ambient air quality monitoring data indicated
the area was very close to attaining the 2006 PM2.5
standard. See 2015 Supplement, p. 4. Accordingly, the 2015 Supplement
does not contain a separate RFP or quantitative milestone
demonstration.
3. Evaluation and Proposed Action
    As a result of the NRDC decision remanding the 2007
PM2.5 Implementation Rule, the EPA has considered whether
the 2012 PM2.5 Plan and 2015 Supplement meet the RFP
requirement in section 172(c)(2) of the Act and proposes to find that
they do.
    The 2012 PM2.5 Plan demonstrates that all RACM/RACT are
being implemented as expeditiously as practicable and identifies
projected emission levels for 2014 that reflect full implementation of
the State's and District's RACM/RACT control strategy for the area.\57\
The Plan also shows steady reductions in direct PM2.5,
NOX, VOC, SOX, and ammonia emissions during the
2008-2014 period. Figures IIH-1 and IIH-2 show the emissions
trajectories for direct PM2.5 and each PM2.5
precursor addressed in the control strategy which indicate generally
linear reductions. We propose, therefore, to approve the 2012
PM2.5 Plan and 2015 Supplement as satisfying the requirement
for RFP in CAA section 172(c)(2) for the 2006 PM2.5
standard.
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    \57\ See 2012 PM2.5 plan at Chapter 4, pp. 4-4
through 4-13, Table 4-7, and Appendix III, Table III-2-2B
(``Emission Reductions (Tons per Day) in the Baseline by District
Rules'').
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    With respect to quantitative milestones, the EPA is proposing to
establish December 31, 2014 as the starting point for the first 3-year
period under CAA section 189(e) for the 2006 PM2.5 standard
in the South Coast. This date is the due date for the State's submittal
of attainment-related SIPs necessary to satisfy the Moderate area
requirements applicable to the South Coast area.\58\ Accordingly, the
first quantitative milestone date for the South Coast area would be
December 31, 2017 (3 years after December 31, 2014). Because this date
falls well after the applicable Moderate area attainment date for the
area, which is December 31, 2015, we propose to find that quantitative
milestones are not necessary in this particular Moderate area plan. If,
however, EPA either finalizes this proposal to reclassify the South
Coast area as Serious nonattainment for the 2006 PM2.5
standard or determines that the area has failed to attain by the
December 31, 2015 attainment date, the State and District will be
required to submit a Serious area plan that contains, among other
things, quantitative milestones that demonstrate RFP at each milestone
date, starting December 31, 2017 and at subsequent 3-year intervals
until the area is redesignated to attainment.
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    \58\ Subpart 4 requires states to submit attainment plans within
18 months after nonattainment designations (CAA 189(a)(2)). Due to
unusual circumstances, however, the EPA has by rule created a later
deadline for submittal of attainment plan submission date for the
2006 PM2.5 NAAQS in order to provide states a reasonable
amount of time to address the requirements of subpart 4 consistent
with the NRDC decision. See 79 FR 31566 (June 2, 2014).
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I. Contingency Measures

1. Requirements for Contingency Measures
    Under CAA section 172(c)(9), PM2.5 plans must include
contingency measures to be implemented if an area fails to meet RFP
(``RFP contingency measures'') and, where the SIP includes a
demonstration of attainment (as opposed to a demonstration of
impracticability), contingency measures to be implemented if an area
fails to attain the PM2.5 standards by the applicable
attainment date (``attainment

contingency measures''). Under subpart 4, however, the EPA interprets
section 172(c)(9) in light of the specific requirements for particulate
matter nonattainment areas. Section 189(b)(1)(A) differentiates between
attainment plans that provide for timely attainment and those that
demonstrate that attainment is impracticable. Where a SIP includes a
demonstration that attainment by the applicable attainment date is
impracticable, the state need only submit contingency measures to be
implemented if an area fails to meet RFP.\59\
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    \59\ The EPA does not interpret the requirement for failure-to-
attain contingency measures to apply to Moderate PM2.5
nonattainment areas that cannot practicably attain the NAAQS by the
statutory attainment date. Rather, the EPA believes it is
appropriate for the state to identify and adopt attainment
contingency measures as part of the Serious area attainment plan
that it will develop once the EPA reclassifies the area (Addendum at
42015).
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    The purpose of contingency measures is to continue progress in
reducing emissions while the SIP is being revised to meet the missed
RFP milestone or to provide for attainment.
    The principal requirements for contingency measures are:
     Contingency measures must be fully adopted rules or
control measures that are ready to be implemented quickly upon failure
to meet RFP or failure of the area to meet the standard by its
attainment date.
     The SIP should contain trigger mechanisms for the
contingency measures, specify a schedule for implementation, and
indicate that the measures will be implemented without further action
by the state or by the EPA. In general, we expect all actions needed to
effect full implementation of the measures to occur within 60 days
after the EPA notifies the state of a failure.
     The contingency measures should consist of control
measures for the area that are not relied on to demonstrate attainment
or RFP.
     The measures should provide for emissions reductions
equivalent to approximately one year of reductions needed for RFP
calculated as the overall level of reductions needed to demonstrate
attainment divided by the number of years from the base year to the
attainment year. (General Preamble at 13543 and Addendum at 42014).
2. Contingency Measures in the 2012 PM2.5 Plan and 2015
Supplement
    Contingency measures for failure to attain are described in Chapter
6, pages 6-7 to 6-13 of the 2012 PM2.5 Plan. The 2012
PM2.5 Plan and 2015 Supplement do not include contingency
measures for failure to meet RFP.
3. Evaluation and Proposed Action
    Because we are proposing to approve the State's demonstration that
attainment by the applicable Moderate area attainment date of December
31, 2015 is impracticable in the South Coast and to reclassify the area
to serious, contingency measures for failure to attain are not required
as part of this Moderate area plan. Upon reclassification of the South
Coast area as a Serious area, California will be required to adopt
attainment contingency measures as part of the Serious area attainment
plan for the 2006 PM2.5 NAAQS.
    We propose to find that the RFP contingency measure requirement for
any RFP milestone year prior to 2014 is now moot as applied to the
South Coast PM2.5 nonattainment area. The sole purpose of
RFP contingency measures is to provide continued progress if an area
fails to meet its RFP goal. Failure to meet any milestone year target
prior to 2014 would have required California to implement RFP
contingency measures in the South Coast and to revise the 2012
PM2.5 Plan to assure that it still provided for attainment
by the applicable attainment date of December 31, 2015. In this case,
however, the 2012 PM2.5 Plan and 2015 Supplement demonstrate
that actual emission levels in the years leading up to 2014 were
consistent with RFP for direct PM2.5 and all four precursor
pollutants (NOX, SOX, VOC and ammonia) regulated
in the 2012 PM2.5 Plan. Accordingly, RFP contingency
measures no longer have meaning or purpose, and therefore EPA proposes
to find that the requirement for them is now moot.

J. Motor Vehicle Emission Budgets

1. Requirements for Motor Vehicle Emissions Budgets
    CAA section 176(c) requires Federal actions in nonattainment and
maintenance areas to conform to the SIP's goals of eliminating or
reducing the severity and number of violations of the NAAQS and
achieving expeditious attainment of the standards. Conformity to the
SIP's goals means that such actions will not: (1) Cause or contribute
to violations of a NAAQS, (2) worsen the severity of an existing
violation, or (3) delay timely attainment of any NAAQS or any interim
milestone.
    Actions involving Federal Highway Administration (FHWA) or Federal
Transit Administration (FTA) funding or approval are subject to the
EPA's transportation conformity rule, codified at 40 CFR part 93,
subpart A. Under this rule, MPOs in nonattainment and maintenance areas
coordinate with state and local air quality and transportation
agencies, the EPA, FHWA, and FTA to demonstrate that an area's RTP and
transportation improvement program (TIP) conform to the applicable SIP.
This demonstration is typically done by showing that estimated
emissions from existing and planned highway and transit systems are
less than or equal to the motor vehicle emissions budgets (budgets)
contained in all control strategy SIPs. An attainment, maintenance, or
RFP SIP should include budgets for the attainment year, each required
RFP year, or the last year of the maintenance plan, as appropriate.
Budgets are generally established for specific years and specific
pollutants or precursors and must reflect all of the motor vehicle
control measures contained in the attainment and RFP demonstrations (40
CFR 93.118(e)(4)(v)).
    PM2.5 plans should identify motor vehicle emission
budgets for direct PM2.5 and all significant
PM2.5 precursors for each RFP milestone year and the
attainment year, if the plan demonstrates attainment. All direct
PM2.5 SIP budgets should include direct PM2.5
motor vehicle emissions from tailpipe, brake wear, and tire wear. A
state must also consider whether re-entrained paved and unpaved road
dust or highway and transit construction dust are significant