[Federal Register Volume 80, Number 146 (Thursday, July 30, 2015)]
[Proposed Rules]
[Pages 45477-45491]
[FR Doc No: 2015-18531]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 52 and 81

[EPA-R09-OAR-2015-0279; FRL-9930-98-Region 9]

Air Plan Approval; California; Mammoth Lakes; Redesignation
Request; PM10 Maintenance Plan

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to
approve, as a revision to the California State Implementation Plan
(SIP), California's request to redesignate the Mammoth Lakes
nonattainment area to attainment for the 1987 National Ambient Air
Quality Standard (NAAQS) for particulate matter of ten microns or less
(PM10). EPA is also proposing to approve the maintenance
plan for the Mammoth Lakes area and the associated motor vehicle
emissions budgets for use in transportation conformity determinations.
Finally, EPA is proposing to approve the attainment year emissions
inventory. EPA is proposing these actions because the SIP revision
meets the requirements of the Clean Air Act and EPA guidance for
maintenance plans and motor vehicle emissions budgets.

DATES: Any comments must arrive by August 31, 2015.

ADDRESSES: Submit comments, identified by docket number EPA-R09-OAR-
2015-0279 by one of the following methods:
    1. Federal eRulemaking Portal: http://www.regulations.gov. Follow
the online instructions.
    2. Email: wamsley.jerry@ epa.gov.
    3. Mail or deliver: Jerry Wamsley (Air-2), U.S. Environmental
Protection Agency Region IX, 75 Hawthorne Street, San Francisco, CA
94105-3901.
    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 http://www.regulations.gov or
email. http://www.regulations.gov is an ``anonymous access'' system,
and 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
EPA, your email address will be automatically captured and included as
part of the public comment. If EPA cannot read your comment due to
technical difficulties and cannot contact you for clarification, EPA
may not be able to consider your comment. Electronic files should avoid
the use of special characters, any form of encryption, and be free of
any defects or viruses.
    Docket: Generally, documents in the docket for this action are
available electronically at www.regulations.gov and in hard copy format
at EPA Region IX, 75 Hawthorne Street, San Francisco, California. While
all documents in the docket are listed at www.regulations.gov, some
information may be publicly available only at the hard copy location
(e.g., copyrighted material, large maps), and some may not be publicly
available in 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.

FOR FURTHER INFORMATION CONTACT: Jerry Wamsley, EPA Region IX, (415)
947-4111, wamsley.jerry@ epa.gov.

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

Table of Contents

I. Summary of Our Proposal
II. Background of This Action
    A. The PM10 National Ambient Air Quality Standard
    B. PM10 Planning Requirements Applicable to the
Mammoth Lakes Area
    C. Summary of the PM10 Attainment Plan for the
Mammoth Lakes Area
III. Procedural Requirements for the Adoption and Submittal of SIP
Revisions
IV. Substantive Requirements for Redesignation to Attainment of a
NAAQS
V. Our Evaluation of California's Redesignation Request for the
Mammoth Lakes PM10 Nonattainment Area
    A. Our Determination That the Area Has Attained the Applicable
NAAQS
    B. The Area Has a Fully Approved SIP Meeting Requirements
Applicable for Purposes of Redesignation Under Section 110 and Part
D of the Clean Air Act
    1. Basic SIP Requirements Under Section 110 of the Clean Air Act
    2. SIP Requirements Under Part D of the Clean Air Act
    a. Permits for New and Modified Major Stationary Sources
    b. Control of PM10 Precursor Pollutants
    c. General and Transportation Conformity Requirements
    C. The Area Must Show the Improvement in Air Quality Is Due to
Permanent and Enforceable Emission Reductions
    D. The Area Must Have a Fully Approved Maintenance Plan Under
Clean Air Act Section 175A
    1. Attainment and Projected Emissions Inventories
    2. Maintenance Demonstration
    3. Monitoring Network and Verifying Continued Attainment
    4. Contingency Provisions
    E. Transportation Conformity and Motor Vehicle Emissions Budgets
VI. Proposed Action and Request for Public Comment
VII. Statutory and Executive Order Reviews

I. Summary of Our Proposal

    EPA is proposing approval of the Mammoth Lakes PM10
redesignation and maintenance plan. We are proposing this action
because California's SIP revision meets the Clean Air Act (CAA)
requirements and EPA guidance concerning redesignations to attainment
of a National Ambient Air Quality Standard (NAAQS or standard) and
maintenance plans.
    First, under CAA section 107(d)(3)(D), EPA is proposing to approve
the State's request to redesignate the Mammoth Lakes PM10
nonattainment area to attainment for the PM10 NAAQS. Our
proposal is based on our conclusion that the area has met the five
criteria for redesignation under CAA section 107(d)(3)(E): (1) The area
has attained the PM10 NAAQS; (2) the required portions of
the SIP are fully approved for the area; (3) the improvement in ambient
air quality in the area is due to permanent and enforceable reductions
in PM10 emissions; (4) California has met all requirements
applicable to the Mammoth Lakes PM10 nonattainment area with
respect to section 110 and part D of the CAA; and, (5) the Mammoth
Lakes PM10 Maintenance Plan, as described below, meets the
requirements of CAA section 175A.
    Second, under section 110(k)(3) of the CAA, EPA is proposing to
approve as a revision to the SIP, the maintenance plan developed by the
Great Basin Unified Air Pollution Control District (GBUAPCD) entitled
``2014 Update Air Quality Maintenance Plan and Redesignation Request
for the Town of Mammoth Lakes'' (herein referred to as the Mammoth
Lakes PM10 Maintenance Plan), dated May 5, 2014, submitted
by California, through the California Air Resources Board (CARB), to
EPA on October 21, 2014.\1\ EPA is proposing to find that the Mammoth
Lakes PM10 Maintenance Plan meets the requirements in
section 175A of the CAA. The plan's maintenance demonstration shows
that the Mammoth Lakes area will continue to attain the PM10
NAAQS for at least 10 years beyond redesignation (i.e., through 2030).
The plan's contingency provisions incorporate a process for identifying
new or more stringent control measures in the event of a future
monitored violation. Finally, EPA is proposing to approve the plan's
2012 emission inventory as meeting the

requirements of CAA section 172 and 175A.
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    \1\ See Section III in this action for list of documents
submitted by the California. See the docket for this action for
copies of the submittal documents including the October 21, 2014
submittal letter from the State.
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    Third, EPA is proposing to approve the motor vehicle emission
budgets (budgets) in the Mammoth Lakes PM10 Maintenance Plan
because we find they meet the applicable transportation conformity
requirements under 40 CFR 93.118(e). With this Federal Register notice,
EPA is informing the public that we are reviewing the plan's budgets
for adequacy. With this action, we are starting the public comment
period on adequacy of the proposed budgets. Please see the DATES
section of this proposal for the closing date of the comment period.

II. Background of This Action

A. The PM10 National Ambient Air Quality Standard

    EPA sets the NAAQS for certain ambient air pollutants at levels
required to protect public health and welfare. Particulate matter with
an aerodynamic diameter less than or equal to a nominal ten
micrometers, or PM10, is one of the ambient air pollutants
for which EPA has established health-based standards. As discussed
below, we have promulgated and revised the PM10 NAAQS
several times.
    EPA revised the NAAQS for particulate matter on July 1, 1987,
replacing standards for total suspended particulates (TSP, particulate
less than 30 microns in diameter) with new standards applying only to
particulate matter up to 10 microns in diameter (PM10) (52
FR 24633). In 1987, EPA established two PM10 standards, an
annual standard and a 24-hour standard. An area attains the 24-hour
PM10 standard of 150 micrograms per cubic meter ([mu]g/m\3\)
when the expected number of days per calendar year with a 24-hour
concentration exceeding the standard (referred to as an exceedance), is
equal to or less than one.\2\ The annual PM10 standard is
attained when the expected annual arithmetic mean of the 24-hour
samples averaged over a three year period does not exceed 50 [mu]g/
m\3\. See 40 CFR 50.6 and 40 CFR part 50, Appendix K.
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    \2\ An exceedance is defined as a daily value that is above the
level of the 24-hour standard, 150 [mu]g/m\3\, after rounding to the
nearest 10 [mu]g/m\3\ (i.e., values ending in five or greater are to
be rounded up). Consequently, a recorded value of 154 [mu]g/m\3\
would not be an exceedance because it would be rounded to 150 [mu]g/
m\3\; whereas, a recorded value of 155 [mu]g/m\3\ would be an
exceedance because it would be rounded to 160 [mu]g/m\3\. See 40 CFR
part 50, Appendix K, section 1.0.
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    In a 2006 p.m. NAAQS revision, the 24-hour PM10
standards were retained but the annual standards were revoked,
effective December 18, 2006 (71 FR 61144, October 17, 2006). On January
15, 2013, EPA announced that it was again retaining the 24-hour
PM10 NAAQS as a 24-hour standard of 150 [mu]g/m\3\ (78 FR
3086). California's submittal of the Mammoth Lakes PM10
Maintenance Plan addresses the 1987 24-hour PM10 standard,
as originally promulgated, and as reaffirmed on January 15, 2013.

B. PM10 Planning Requirements Applicable to the Mammoth Lakes Area

    On the date of enactment of the 1990 CAA Amendments,
PM10 areas meeting the qualifications of section
107(d)(4)(B) of the amended Act, such as Mammoth Lakes, were designated
nonattainment by operation of law (56 FR 11101, March 15, 1991). See 40
CFR 81.305. Once an area is designated nonattainment, section 188 of
the CAA outlines the process for classification of the area and
establishes the area's attainment date. Consistent with section 188(a),
at the time of designation, all PM10 nonattainment areas
were initially classified as moderate by operation of law, including
the Mammoth Lakes PM10 nonattainment area.\3\
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    \3\ For the designated boundaries of the Mammoth Lakes
PM10 nonattainment area, see 40 CFR 81.305. The Mammoth
Lakes PM10 nonattainment area is located in the southern
portion of Mono County, California; see Figures 1-1 and 1-2 within
the Mammoth Lakes PM10 Maintenance Plan, pages 3 and 4.
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    The 1990 CAA established new planning requirements and attainment
deadlines for the PM10 NAAQS. A fundamental nonattainment
area requirement applicable to the Mammoth Lakes area is that the State
submit a SIP demonstrating attainment of the PM10 NAAQS.
This demonstration must be based upon enforceable control measures
producing emission reductions and emissions at or below the level
predicted to result in attainment of the PM10 NAAQS
throughout the nonattainment area (see CAA section 189(a)). As stated
in section 189(a)(1) of the CAA, the State was required to make the
following SIP submittals by November 15, 1991: The State had to submit
a SIP ensuring implementation of all reasonably available control
measures (RACM) no later than December 10, 1993, as required by CAA
section 189(a)(1)(C); and, the State had to submit a SIP providing for
expeditious attainment by the applicable attainment date, December 31,
1994, as required by CAA sections 188(c)(1)and 189(a)(1)(B).
    More specifically, Subparts 1 and 4 of part D, title 1 of the CAA
contain air quality planning requirements for PM10
nonattainment areas. Subpart 1 of part D, sections 172(c) and 176
contain general requirements for areas designated as nonattainment. The
subpart 1 requirements include, among other things, provisions for
RACM, reasonable further progress (RFP), emissions inventories,
contingency measures and conformity. Subpart 4 of part D contains
specific planning and scheduling requirements for PM10
nonattainment areas. Section 189(a), (c), and (e) detail requirements
that apply specifically to moderate PM10 nonattainment areas
such as Mammoth Lakes. These requirements include the following: (1) An
approved permit program for construction of new and modified major
stationary sources; (2) an attainment demonstration; (3) provisions for
RACM; (4) quantitative milestones demonstrating RFP toward attainment
by the applicable attainment date; and, (5) provisions to ensure that
the control requirements applicable to major stationary sources of
PM10 also apply to major stationary sources of
PM10 precursors except where the Administrator has
determined that such sources do not contribute significantly to
PM10 levels exceeding the NAAQS within the area.

C. Summary of the PM10 Attainment Plan for the Mammoth Lakes Area

    GBUAPCD adopted its moderate area Air Quality Management Plan for
PM10 in December 1990 (1990 AQMP). California submitted the
1990 AQMP for the Mammoth Lakes area on September 11, 1991 with an
addenda submitted on January 9, 1992. Subsequently, EPA approved the
1990 AQMP in 1996 (61 FR 32341, June 24, 1996). In our 1996 action, we
approved the following components of the 1990 AQMP: The emissions
inventory; its provision for implementation of RACM; and, the
demonstration of attainment. In support of the 1990 AQMP, the State
submitted two local rules: GBUAPCD Rule 431--Particulate Emissions; and
Town of Mammoth Lakes Municipal Code, Chapter 8.3, Particulate
Emissions Regulations. We also approved these rules, which control
PM10 emissions from entrained road dust and wood burning
fireplaces and appliances, into the SIP in our 1996 action (61 FR
32341). GBUAPCD Rule 431 was revised on December 4, 2006 and
subsequently approved into the SIP in 2007 (72 FR 61525, October 31,
2007).
    Because of the timing of the development of the 1990 AQMP, the plan
did not address subsequent SIP requirements such as contingency
measures and transportation conformity. We will review how these and
other CAA requirements, such as a permit

program for new and modified stationary sources, were met by the State
in section V, below.

III. Procedural Requirements for the Adoption and Submittal of SIP
Revisions

    The GBUAPCD governing Board adopted the ``2014 Air Quality
Maintenance Plan and Redesignation Request for the Town of Mammoth
Lakes'' on May 5, 2014 and forwarded it to CARB on May 22, 2014. CARB
held a Board Hearing on September 18, 2014 and adopted the Mammoth
Lakes PM10 Maintenance Plan.\4\ California submitted their
redesignation request and the Mammoth Lakes PM10 Maintenance
Plan to EPA on October 21, 2014.\5\
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    \4\ See Resolution 14-27, State of California, Air Resources
Board, ``Approval and Submittal of the Town of Mammoth Lakes
PM10 Maintenance Plan and Redesignation Request'', dated
September 18, 2014.
    \5\ See letter from Richard Corey, Executive Officer, CARB, to
Jared Blumenfeld, Regional Administrator, EPA Region 9, dated
October 21, 2014, with attachments.
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    CARB's SIP submittal includes the following documents: (1) A
submittal letter dated October 21, 2014, from Richard Corey, Executive
Officer, CARB to Jared Blumenfeld, Regional Administrator, U.S. EPA
Region 9 submitting the State's redesignation request and Mammoth Lakes
PM10 Maintenance Plan; (2) a transmittal letter dated May
22, 2014 from Duane Ono, Deputy Air Pollution Control Officer, GBUAPCD
to Richard Corey, Executive Officer, CARB; (3) May 22, 2014 Affidavit
from The Clerk of the GBUAPCD Board, providing Proof of Publication of
Public Notice for Public Hearing on ``2014 Update Air Quality
Maintenance Plan and Redesignation Request for the Town of Mammoth
Lakes'' and the May 5, 2014 GBUAPCD Board Hearing; (4) GBUAPCD Board
Order #140505-03 approving and adopting the Mammoth Lakes
PM10 Maintenance Plan, dated May 5, 2014; (5) CARB's August
8, 2014 Notice of Public Hearing for consideration of the adoption and
approval of the redesignation request and Mammoth Lakes PM10
Maintenance Plan and associated motor vehicle emissions budgets on
September 18, 2014; (6) ``2014 Update Air Quality Maintenance Plan and
Redesignation Request for the Town of Mammoth Lakes'' dated May 5,
2014; (7) CARB Board Resolution 14-27 adopting the redesignation
request and Mammoth Lakes PM10 Maintenance Plan; and, (8)
the CARB Staff Report, dated August 18, 2014, containing the motor
vehicle emissions budgets adopted at the CARB Board hearing. All of
these documents are available for review in the docket for today's
proposed rule.
    Sections 110(a)(1) and 110(l) of the Act require states to provide
reasonable notice and public hearing prior to adoption of SIP
revisions. CARB's submittal of the redesignation request and Mammoth
Lakes PM10 Maintenance Plan documents the public review
process followed by GBUAPCD in adopting the plan prior to transmittal
to CARB for subsequent submittal to EPA as a revision to the SIP. The
documentation listed above provides evidence that reasonable notice of
a public hearing was provided to the public and that a public hearing
was conducted prior to adoption.
    Both GBUAPCD and CARB satisfied applicable statutory and regulatory
requirements for reasonable public notice and hearing prior to adoption
of the SIP revisions. GBUAPCD conducted public workshops, and properly
noticed the public hearing at which the Mammoth Lakes PM10
Maintenance Plan was adopted. The SIP submittal included proof of
publication for notices of the public hearings of CARB and GBUAPCD.
Consequently, we conclude that the SIP submittals have met the public
notice and involvement requirements of section 110(a)(1) of the CAA.
Based on the documentation submitted with the Mammoth Lakes
PM10 Maintenance Plan, we find that the submittal satisfies
the procedural requirements of section 110(l) of the Act for revising
SIPs.
    CAA section 110(k)(1)(B) requires EPA to determine whether a SIP
submittal is complete within 60 days of receipt. This section also
provides that any plan that we have not affirmatively determined to be
complete or incomplete will become complete six months after the day of
submittal by operation of law. A completeness review allows us to
determine if the submittal includes all the necessary items and
information we need to act on it. We make completeness determinations
using criteria we have established in 40 CFR part 51, Appendix V.\6\
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    \6\ The completeness criteria fall into two categories:
administrative information and technical support information. The
administrative information provides documentation that the State has
followed required administrative procedures during the SIP-adoption
process; thus, ensuring that we have a legally-adopted SIP revision
before us. The technical support information provides us the
information we need to determine the impact of the proposed revision
on attainment and maintenance of the air quality standards.
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    We notify a state of our completeness determination by letter
unless the submittal becomes complete by operation of law. Once a SIP
submittal is determined to be complete, either by letter or by
operation of law, EPA is under a 12 month time clock for EPA to act on
the SIP submittal. See CAA section 110(k)(2). A finding of completeness
does not approve the submittal as part of the SIP nor does it indicate
that the submittal is approvable. The redesignation request and Mammoth
Lakes PM10 Maintenance Plan became complete by operation of
law on April 21, 2015.

IV. Substantive Requirements for Redesignation to Attainment of a NAAQS

    In section 107(d)(3)(E), the CAA establishes the requirements for
redesignating an area from nonattainment to attainment of a NAAQS. The
Administrator may not redesignate an area unless the following criteria
are met: (1) EPA determines that the area has attained the applicable
NAAQS; (2) EPA has fully approved the applicable implementation plan
for the area under Section 110(k) of the CAA; (3) EPA determines that
the improvement in air quality is due to permanent and enforceable
reductions; (4) EPA has fully approved a maintenance plan for the area
as meeting the requirements of Section 175A of the CAA; and, (5) the
State containing such an area has met all requirements applicable to
the area under section 110 and part D of the CAA. Section 110
identifies a comprehensive list of elements that SIPs must include, and
part D establishes the SIP requirements for nonattainment areas. Part D
is divided into six subparts. The generally-applicable nonattainment
SIP requirements are found in part D, subpart 1, and the particulate
matter-specific SIP requirements are found in part D, subpart 4.
    EPA provided guidance on redesignations to states in a 1992
document entitled ``State Implementation Plans; General Preamble for
the Implementation of Title I of the Clean Air Act Amendments of 1990''
(referred to herein as the ``General Preamble'').\7\ Additional
guidance was issued in a September 4, 1992 memorandum entitled
``Procedures for Processing Requests to Redesignate Areas to
Attainment'' from John Calcagni, Director, Air Quality Management
Division, EPA Office of Air Quality Planning and Standards,

(referred to herein as the Calcagni memorandum). Maintenance plan
submittals are SIP revisions. Consequently, under section 110(k) of the
Act, EPA is obligated to approve or disapprove a maintenance plan
depending on whether it meets the applicable CAA requirements for such
plans.
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    \7\ The General Preamble was first published at 57 FR 13498
(April 16, 1992) and supplemented at 57 FR 18070 (April 28, 1992).
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    As discussed in more detail below in section V, we have evaluated
the State's submittal and propose to approve CARB's request to
redesignate the Mammoth Lakes PM10 nonattainment area to
attainment for the PM10 NAAQS. Our proposal is based on our
conclusion that all the criteria under CAA section 107(d)(3)(E) have
been satisfied.

V. Our Evaluation of California's Redesignation Request for the Mammoth
Lakes PM10 Nonattainment Area

A. Our Determination That the Area Has Attained the Applicable NAAQS

    Section 107(d)(3)(E)(i) of the CAA requires that EPA determine that
the area has attained the NAAQS. Generally, EPA determines whether an
area's air quality is meeting the 24-hour PM10 NAAQS based
upon complete, quality-assured, and certified data gathered at
established state and local air monitoring stations (SLAMS) in the
nonattainment area, and entered into the EPA Air Quality System (AQS)
database.\8\ Data from air monitors operated by state, local, or tribal
agencies in compliance with EPA monitoring requirements must be
submitted to the AQS. These monitoring agencies certify annually that
these data are accurate to the best of their knowledge. Accordingly,
EPA relies primarily on data in AQS when determining the attainment
status of an area. See 40 CFR 50.6; 40 CFR part 50, appendices J and K;
40 CFR part 53; and, 40 CFR part 58, appendices A, C, D, and E.
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    \8\ For PM10, a complete set of data includes a
minimum of 75 percent of the scheduled PM10 samples per
quarter. See 40 CFR part 50, Appendix K, section 2.3(a). Because the
annual PM10 standard was revoked effective December 18,
2006, our action and determination discusses only attainment of the
24-hour PM10 standard; see 71 FR 61144, October 17, 2006.
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    GBUAPCD is responsible for assuring that the Mammoth Lakes
PM10 nonattainment area meets air quality monitoring
requirements. Both CARB and GBUAPCD submit annual monitoring network
plans to EPA. GBUAPCD's network plans describe the air quality
monitoring network they operate within the Mammoth Lakes nonattainment
area and discuss the status of the monitoring network, as required
under 40 CFR 58.10. In the Mammoth Lakes nonattainment area, GBUAPCD
operates an air quality monitoring station for PM10 in the
Gateway Center commercial area within the Town of Mammoth Lakes. As
required by 40 CFR part 58, the District conducts an annual review of
the air quality monitoring station that is forwarded to CARB and EPA
for evaluation. EPA regularly reviews these annual plans for compliance
with the applicable reporting requirements in 40 CFR part 58. With
respect to PM10, EPA has found that GBUAPCD's network plans
meet the applicable requirements of 40 CFR part 58.\9\ Also, GBUAPCD
annually certifies that the data it submits to AQS are complete and
quality-assured. All data has been certified by GBUAPCD for the period
under review, 2009 through 2014.\10\
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    \9\ See EPA letters to GBUAPCD reviewing the District's annual
network plans for the years 2009 to 2014, within the docket for this
action.
    \10\ For 2009 to 2014 annual certification letters see the
docket for this action, e.g., letter from Theodore D. Schade,
GBUAPCD, to Jared Blumenfeld, EPA Region IX, dated April 25, 2014.
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    From its 2007 Technical System Audit (TSA) of CARB, the Primary
Quality Assurance Organization (PQAO), EPA concluded that the ambient
air monitoring program operated by GBUAPCD in the Mammoth Lakes
nonattainment area currently meets or exceeds EPA requirements.\11\ A
TSA is an on-site review and inspection of a state or local ambient air
monitoring program to assess its compliance with established
regulations governing the collection, analysis, validation, and
reporting of ambient air quality data. See 40 CFR part 58, Appendix A,
Section 2.5.
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    \11\ See the Technical System Audit of Primary Quality Assurance
Organization, California Air Resources Board, dated August 18, 2008,
conducted by Air Quality Analysis Office, US EPA Region 9, within
the docket for this action.
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    EPA determines attainment of the 24-hour PM10 NAAQS by
calculating the expected number of exceedances of the standard in a
year. The 24-hour PM10 standard is attained when the
expected number of exceedances averaged over a three year period is
less than or equal to one at each monitoring site within the
nonattainment area. Generally, three consecutive years of complete,
quality-assured, and certified air quality data is sufficient to show
attainment of the 24-hour PM10 NAAQS. See 40 CFR part 50 and
appendix K. To demonstrate attainment of the 24-hour PM10
standard at a given monitoring site, the monitor must provide
sufficient data to perform the required calculations in 40 CFR part 50,
appendix K described above. The amount of data required varies with the
sampling frequency, data capture rate and the number of years of
record. In all cases, three years of representative monitoring data
must be complete meaning a minimum of 75 percent of scheduled
PM10 samples must be recorded during each calendar quarter
of the three year period under review. The purpose of these
calculations and data completeness review is to determine a valid
design value for making a determination of attainment for the
PM10 standard.
    At the Gateway Center monitoring site, GBUAPCD operates two
PM10 monitors. The first monitor is a Federal Reference
Method (FRM) monitor (POC 5) run at a sampling frequency of once every
three days. The second monitor is a Federal Equivalent Method (FEM)
continuous monitor (POC 6) run at a daily sampling frequency. The FEM/
POC 6 monitor is the primary monitor we will focus on in our
determination of attainment. Each monitor produces its own data stream,
and the data from the two monitors produce separate design values. Our
calculations show the highest design value for the Mammoth Lakes
Planning Area over the 2009 through 2014 timeframe is 0.7 expected
exceedances, as determined by data from the POC 6 monitor. Usually,
this design value would be sufficient to determine that the Mammoth
Lakes area has attained the PM10 NAAQS, but we found that
the POC 6 data failed to meet the 75 percent completeness standard in
the third quarter of 2012, showing a 61 percent completeness
record.\12\ Table 1 provides the design values or expected annual
exceedances of the PM10 standard for the Mammoth Lakes area
over the year 2009 through 2014 for both monitors.\13\
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    \12\ See AQS Design Value Reports dated April 30, 2015 and AQS
Raw Data Reports dated May 7, 2015 for completeness information. The
reports can be found in the docket for today's action.
    \13\ A design value is calculated using a specific methodology
from monitored air quality data and is used to compare an area's air
quality to a NAAQS. The methodologies for calculating expected
exceedances for the 24-hour PM10 NAAQS are found in 40
CFR part 50, Appendix K, Section 2.1(a).

   Table 1--Design Values and Annual Average Expected Exceedances of PM10 NAAQS in Mammoth Lakes Nonattainment
                                             Area, 2009 Through 2014
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                     Monitor                         2009-2011       2010-2012       2011-2013       2012-2014
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Gateway Center monitor, Site ID 06-051-0001 POC              0.0             0.0             0.0             0.0
 5..............................................
Gateway Center monitor, Site ID 06-051-0001 POC              0.0             0.0             0.7             0.7
 6..............................................
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Source: EPA Air Quality System, Design Value Report, April 30, 2015.

    Given the data completeness issue with the third quarter 2012 data
at POC 6, we conducted two analyses to determine if the missing data
could reasonably change the design value from attaining to violating
the PM10 NAAQS.\14\ In the first analysis, we compared the
POC 5 data with the POC 6 data over the 2009 through 2014 time period
to see if the data correlated closely enough to allow the POC 5 data to
represent the missing POC 6 data. We found that the data correlated
very well, and when POC 6 was not operating during the third quarter of
2012, the observed PM10 values at POC 5 were between 9 and
17 [mu]g/m\3\, well below the 150 [mu]g/m\3\ value of the
PM10 NAAQS. The two monitors differ, however, in the
frequency of their observations with POC 5 making observations one day
in three and POC 6 making daily observations. Consequently, our second
analysis examined whether exceedances may have reasonably occurred on
the days POC 5 was not collecting data.
---------------------------------------------------------------------------

    \14\ See ``Technical Support Document for the Determination of
Attainment and Redesignation of the Mammoth Lakes PM10
Nonattainment Area: Analyses Addressing 2012 Incomplete Data'',
April 30, 2015, in the docket for this action.
---------------------------------------------------------------------------

    To determine whether it is reasonable to assume that exceedances
did not occur on the days POC 5 was not sampling, we identified the
highest PM10 values over the 2009 through 2014 time period.
Looking at POC 6, the winter months, December, January, and February,
of 2009, 2010, 2011, and 2012 exhibit consistently elevated
PM10 concentrations and the highest annual concentrations at
Mammoth Lakes.\15\ Then, in 2013 and 2014, the highest 24-hour
PM10 concentrations at POC 6 were measured during the third
quarter of 2013 and 2014; see Table 2. Of these highest concentrations,
on two days, July 28, 2013 and July 29, 2013, concentrations were
higher than the 150 [mu]g/m\3\ standard.
---------------------------------------------------------------------------

    \15\ Gateway Center monitors POC 5 and POC 6 24-hour
concentration data and monthly mean summary statistics can be found
in the Air Quality System, Raw Data Report, dated May 7, 2015, in
the docket for today's action.

  Table 2--Five Highest PM10 Concentrations Observed at Mammoth Lakes Gateway Center Monitor From 2009 Through
                                            2014 and Wildfire Events
----------------------------------------------------------------------------------------------------------------
                                       Concentration
                Date                    ([mu]g/m\3\)                         Wildfire event
----------------------------------------------------------------------------------------------------------------
July 28, 2013......................                166  Aspen Fire--Exceptional Event Flag.
July 29, 2013......................                182  Aspen Fire--Exceptional Event Flag.
July 30, 2013......................                122  Aspen Fire.
August 1, 2013.....................                133  Aspen Fire.
August 2, 2014.....................                130  French Fire.
----------------------------------------------------------------------------------------------------------------
Source: EPA Air Quality System, Raw Data Report, May 7, 2015; all observations are from Site ID 06-051-0001, POC
  6.

    Further examination shows that the July 28, 2013 and July 29, 2013
exceedances measured at the Gateway Center monitoring site are flagged
as wildfire exceptional events within AQS; however, an exceptional
event demonstration package was not submitted for the two exceedances.
The Aspen Wildfire occurred near the Mammoth Lakes area over an
extended period from July 22, 2013 to September 8, 2013, burning 22,992
acres approximately 30 miles south southwest of Mammoth Lakes near
Mammoth Pool Reservoir on the upper San Joaquin River in the Sierra
National Forest; thus, reasonably accounting for four of the five
highest observed concentrations of PM10. In a similar
wildfire event, the French Fire burned from July 28, 2014 to August 18,
2014 consuming 13,838 acres west of and adjacent to the site of the
Aspen Fire; again, reasonably accounting for the August 2, 2014 high
concentration.\16\ As a check, we examined the 2013 and 2014 data for
the months with the highest average monthly concentration and confirmed
that in these two years, similar to 2009 through 2012, January and
December had the highest monthly average PM10 concentrations
observed. In sum, the high summertime third quarter concentrations
observed in 2013 and 2014 are related to wildfire events and are not
consistent with the remaining 2009 through 2014 data showing that the
winter months, December to February, is the period during which high
PM10 concentrations are most likely to be observed in
Mammoth Lakes. As noted earlier, the State has submitted complete data
for all first and fourth calendar quarters (i.e. winter season) during
the 2009 through 2014 time frame and no exceedance of the
PM10 NAAQS has occurred during these quarters. Also, no
exceedance occurred during the third quarter of the years 2009, 2010,
and 2011.
---------------------------------------------------------------------------

    \16\ For information concerning the Aspen wildfire, see the 2013
Cal Fire Large Fire List at www.cdfdata.fire.ca.gov/pub/cdf/images/incidentstatevents_250.pdf. For information concerning the French
wildfire, see the 2014 Cal Fire Large Fire List at
www.cdfdata.fire.ca.gov/pub/cdf/images/incidentstatevents_249.pdf.
For a map showing the relative location of the Aspen and French
wildfires, see www.wildfiretoday.com/2014/07/30/california-french-fire/.
---------------------------------------------------------------------------

    To summarize, it is reasonable to conclude that the missing third
quarter 2012 p.m.10 data would not have an effect on the design value
and would not overturn our determination of attainment for the
following reasons: (1) The only two exceedances and other high ambient
values in the last six years were due to wildfire events; (2) data from
the third quarters in 2009, 2010, and 2011 show no exceedances and do
not correspond with the observed summer time period of elevated
PM10 concentrations in 2013 and 2014; and, (3) the POC 5
data correlates well enough to be a valid representation of

the missing third quarter POC 6 data. Consequently, we are proposing to
find that the design values in Table 1 are accurate and representative
design values for the Mammoth Lakes nonattainment area with no expected
exceedances greater than 0.7 calculated over the 2009 through 2014
period. Twenty-four hour ambient PM10 levels in Mammoth
Lakes meet the requirement of no more than 1.0 expected annual average
exceedance over a three year period.
    Therefore, EPA proposes to determine that the Mammoth Lakes
PM10 nonattainment area has attained the 24-hour
PM10 standard and continues to attain the standard to date
based on the most recent available AQS data. In addition, preliminary
air quality data for 2015 show that the area is continuing to meet the
PM10 NAAQS. Before finalizing this proposal, EPA will
include a review of any available preliminary data for 2015.

B. The Area Has a Fully Approved SIP Meeting Requirements Applicable
for Purposes of Redesignation Under Section 110 and Part D of the Clean
Air Act

    Section 107(d)(3)(E)(ii) and (v) require EPA to determine that the
area has a fully-approved SIP under section 110(k) that meets all
applicable requirements under section 110 and part D for the purposes
of redesignation. EPA may rely on prior SIP approvals in approving a
redesignation request as well as any additional measures it may approve
in conjunction with a redesignation action.\17\
---------------------------------------------------------------------------

    \17\ See the following EPA guidance and court decisions:
Calcagni memorandum at p. 3; Southwestern Pennsylvania Growth
Alliance v. Browner, 144 F.3d 984, 989-90 (6th Cir. 1998). See 68 FR
25418 and 25426 (May 12, 2003) and citations therein concerning
EPA's reliance on added measures approved with an action on a
redesignation request.
---------------------------------------------------------------------------

1. Basic SIP Requirements Under Section 110 of the Clean Air Act
    The general SIP elements and requirements provided in section
110(a)(2) include, but are not limited to, the following: Submittal of
a SIP that has been adopted by the State after reasonable public notice
and hearing; provisions for establishment and operation of appropriate
procedures needed to monitor ambient air quality; implementation of a
source permit program; provision for the implementation of part C
requirements for prevention of significant deterioration (PSD)
provisions; provisions for the implementation of part D requirements
for nonattainment new source review (nonattainment NSR) permit
programs; provisions for air pollution modeling; and, provisions for
public and local agency participation in planning and emission control
rule development.
    We note that SIPs must be fully approved only with respect to the
applicable requirements for redesignations consistent with section
107(d)(3)(E)(ii) of the Act. The section 110 (and part D) requirements
that are linked to a particular nonattainment area's designation and
classification are the relevant measures to evaluate in reviewing a
redesignation request. Requirements that apply regardless of the
designation of any particular area in the State are not applicable
requirements for the purposes of redesignation, and the State will
remain subject to these requirements after the Mammoth Lakes
PM10 nonattainment area is redesignated to attainment. For
example, CAA section 110(a)(2)(D) requires that SIPs contain certain
measures to prevent sources in a State from significantly contributing
to air quality problems in another state, known as ``transport SIPs.''
Because the section 110(a)(2)(D) requirements for transport SIPs are
not linked to a particular nonattainment area's designation and
classification but rather apply regardless of the attainment status,
these are not applicable requirements for the purposes of redesignation
under section 107(d)(3)(E).
    Similarly, EPA believes that other section 110 (and part D)
requirements that are not linked to nonattainment plan submittals or to
an area's attainment status are not applicable requirements for
purposes of redesignation. EPA believes that the section 110 (and part
D) requirements relating to a particular nonattainment area's
designation and classification are the relevant measures to evaluate in
reviewing a redesignation request. This view is consistent with EPA's
existing policy on applicability of the conformity SIP requirement for
redesignations.\18\
---------------------------------------------------------------------------

    \18\ See discussion in 75 FR 36023 and 36026 (June 24, 2010).
---------------------------------------------------------------------------

    Regarding Mammoth Lakes, CARB and GBUAPCD have submitted and EPA
has approved provisions addressing the basic CAA section 110
provisions. The GBUAPCD portion of the approved California SIP contains
enforceable emissions limitations; requires monitoring, compiling, and
analyzing of ambient air quality data; requires preconstruction review
of new or modified stationary sources; provides for adequate funding,
staff, and associated resources necessary to implement its
requirements; and, provides the necessary assurances that the State
maintains responsibility for ensuring that the CAA requirements are
satisfied in the event that GBUAPCD is unable to meet its CAA
requirements. There are no outstanding or disapproved applicable
section 110 SIP submittals with respect to the State, the GBUAPCD, and
Mammoth Lakes.\19\ In sum, we propose to conclude that CARB and GBUAPD
have met all applicable SIP requirements under section 110 of the CAA
(General SIP Requirements) for the Mammoth Lakes nonattainment area for
purpose of redesignating the area to attainment of the PM10
NAAQS.
---------------------------------------------------------------------------

    \19\ The applicable California SIP for all nonattainment areas
can be found at: http://yosemite.epa.gov/r9/r9sips.nsf/Casips?readform&count=100&state=California.
---------------------------------------------------------------------------

2. SIP Requirements Under Part D of the Clean Air Act
    Subparts 1 and 4 of part D within title 1 of the CAA contain air
quality planning requirements for PM10 nonattainment areas.
Subpart 1 contains general requirements for all nonattainment areas of
any NAAQS pollutant, including PM10. Among other provisions,
the subpart 1 requirements include provisions for RACM, RFP, emissions
inventories, contingency measures, and conformity. Subpart 4 contains
specific planning and scheduling requirements for PM10
nonattainment areas. Section 189(a), (c), and (e) requirements apply
specifically to moderate PM10 nonattainment areas and
include: (1) An approved permit program for construction of new and
modified major stationary sources; (2) provisions for RACM; (3) an
attainment demonstration; (4) quantitative milestones demonstrating RFP
toward attainment by the applicable attainment date; and, (5)
provisions to ensure that the control requirements applicable to major
stationary sources of PM10 also apply to major stationary
sources of PM10 precursors except where the Administrator
has determined that such sources do not contribute significantly to
PM10 levels that exceed the NAAQS in the area.
    With respect to the subpart 4 requirements discussed above,
California submitted a moderate area PM10 plan, the 1990
AQMP, for the Mammoth Lakes nonattainment area on September 11, 1991.
This attainment plan was developed and adopted by the GBUAPCD on
December 12, 1990. The State submitted a revision to this plan on
January 9, 1992, also previously adopted by the GBUAPCD on November

6, 1991. This 1990 AQMP for the Mammoth Lakes PM10 Planning
Area relied on two control measures to reduce PM10 emissions
sufficient to meet the PM10 standard: GBUAPCD, Rule 431--
Particulate Emissions, adopted on November 6, 1991; and, Town of
Mammoth Lakes Municipal Code Chapter (TMLMCC) 8.30--Particulate Matter
Emissions Regulations, dated October 2, 1991. Both of these rules were
submitted with the 1990 AQMP so as to reduce emissions from the primary
sources of PM10 in the nonattainment area, fireplaces and
woodstoves, and re-suspended road dust and pulverized cinders from
motor vehicles driving on paved roads.
    EPA reviewed the 1990 AQMP and its companion control measures and
in 1996 approved the moderate area plan, GBUAPCD Rule 431, and TMLMCC
8.30, incorporating them into the SIP (61 FR 32341, June 24, 1996). In
this approval action, we made the following findings concerning the
1990 AQMP: The plan provided a comprehensive, accurate, and current
emissions inventory meeting the requirements of section 172(c)(3); the
plan provided for all RACM to be implemented by December 10, 1993, as
required by sections 172(c) and 189(a)(1)(C) of the Act; the plan
provided a demonstration of attainment by December 31, 1994, the
applicable attainment date, as required by section 189(a)(1)(B); and,
we found that precursor pollutants of PM10 do not contribute
significantly to PM10 levels in excess of the NAAQS.
Regarding RFP, our General Preamble provides that initial moderate
nonattainment areas, such as the Mammoth Lakes area, could meet the RFP
requirement by demonstrating attainment by the applicable attainment
date, December 31, 1994.\20\ As noted above, we approved the
demonstration of attainment as meeting section 189(a)(1)(B).
---------------------------------------------------------------------------

    \20\ See our discussion concerning RFP/quantitative milestones
in the General Preamble, (57 FR 13498 and 13539, April 16, 1992).
---------------------------------------------------------------------------

    The 1990 AQMP did not provide for motor vehicle emissions budgets
as required by section 176(c) of the Act because EPA's guidance and
regulations were not published at the time the plan was developed and
adopted. The maintenance plan has provided for motor vehicle emission
budgets. We review them later in this action and propose to approve
them.
    The 1990 AQMP as approved in 1996 did not address contingency
measures required by section 172(c)(9) of the CAA. Again, this was
because the 1990 AQMP was developed prior to EPA guidance on
contingency measures.
    Since our 1996 action on GBUAPCD Rule 431, the State has submitted
and EPA has approved into the SIP a subsequent revision to the rule (72
FR 61525, October 31, 2007). This 2006 amendment to Rule 431 eliminated
the operational exemption from no-burn day requirements granted to EPA-
certified devices. These EPA-certified devices comprise 84 percent of
the residential wood burning device inventory.\21\ Since 2007, all
wood-burning devices in the Mammoth Lakes nonattainment area have been
required to shut down on designated no-burn days, adding an additional
increment of emission reductions when no-burn days are called for under
the rule. In general, the 2006 revisions to GBUAPCD Rule 431 are
surplus to the rule provisions in the 1990 AQMP that represent the
control strategy that has resulted in the Mammoth Lakes area meeting
the PM10 standard. In this manner, GBUAPCD Rule 431
represents a pre-implemented contingency measure and fulfils the
requirements of section 172(c)(9).
---------------------------------------------------------------------------

    \21\ See Mammoth Lakes PM10 Maintenance Plan, Table
5-1, page 18.
---------------------------------------------------------------------------

    Separate and distinct from a finding of attainment of a standard,
EPA has taken the position that CAA requirements associated with
attainment of the NAAQS are not applicable for purposes of
redesignation. In the General Preamble, EPA has stated that section
172(c)(9) requirements are directed at ensuring reasonable further
progress and attainment by the applicable attainment date specified by
statute. These attainment related requirements no longer apply when an
area has attained a standard and is eligible to be redesignated to
attainment.\22\ The Calcagni memorandum states a similar position that
requirements for reasonable further progress and other measures needed
for attainment will not apply for redesignations because they only have
meaning and applicability where areas do not meet the NAAQS.\23\ While
the attainment related provisions of RFP and section 172(c)(9) are no
longer relevant in the context of redesignation, the maintenance plan
provisions in section 175A of the CAA require that such plans
incorporate contingency provisions sufficient for an area to
expeditiously regain attainment of a NAAQS. We review the contingency
provisions in the Mammoth Lakes PM10 Maintenance Plan later
in this action and propose to approve them.
---------------------------------------------------------------------------

    \22\ See the General Preamble at 57 FR 13498 and 13564, (April
16, 1992).
    \23\ See the Calcagni memorandum at page 6.
---------------------------------------------------------------------------

a. Permits for New and Modified Major Stationary Sources
    CAA sections 172(c)(5) and 189(a)(1)(A) require the State to submit
SIP revisions that establish certain requirements for new or modified
stationary sources in nonattainment areas, including provisions to
ensure that major new sources or major modifications of existing
sources of nonattainment pollutants incorporate the highest level of
control, referred to as the Lowest Achievable Emission Rate (LAER), and
that increases in emissions from such stationary sources are offset so
as to provide for reasonable further progress towards attainment in the
nonattainment area. The process for reviewing permit applications and
issuing permits for new or modified stationary sources in nonattainment
areas is referred to as ``nonattainment New Source Review''
(nonattainment NSR). With respect to the part D requirements for a
nonattainment NSR permit program for construction of new and modified
major stationary sources, EPA has previously approved the following
nonattainment NSR rules for GBUAPCD which apply within the Mammoth
Lakes nonattainment area: GBUAPCD Rule 209-A and 216.\24\
---------------------------------------------------------------------------

    \24\ For Rule 209-A, see 47 FR 26379, June 18, 1982, and for
Rule 216, see 41 FR 53661, December 8, 1976.
---------------------------------------------------------------------------

    Final approval of the NSR program, however, is not a prerequisite
to finalizing our proposed approval of the State's redesignation
request. EPA has determined in past redesignations that a NSR program
does not have to be approved prior to redesignation, provided that the
area demonstrates maintenance of the standard without part D NSR
requirements in effect. The rationale for this position is described in
a memorandum from Mary Nichols, Assistant Administrator for Air and
Radiation, dated October 14, 1994, entitled ``Part D NSR Requirements
for Areas Requesting Redesignation to Attainment.'' See the more
detailed explanations in the following redesignation rulemakings:
Detroit, MI (60 FR 12459, March 7, 1995); Cleveland-Akron-Lorrain, OH
(61 FR 20458, May 7, 1996); Louisville, KY (66 FR 53665, October 23,
2001); Grand Rapids, MI (61 FR 31831, June 21, 1996); and San Joaquin
Valley, CA (73 FR 22307, April 25, 2008 and 73 FR 66759, November 12,
2008).
    The requirements of the PSD program under Part C will apply to
PM10 once the area has been redesignated. Thus,

new major sources of PM10 emissions and major modifications
at major sources of PM10 as defined under 40 CFR 52.21 will
be required to obtain a PSD permit or include PM10 emissions
in their existing PSD permit. Currently, EPA is the PSD permitting
authority in the Mammoth Lakes nonattainment area under a federal
implementation plan; see 40 CFR 52.270(a)(3). GBUAPCD can implement the
federal PSD program, however, either through a delegation agreement
with EPA, or by making the necessary changes to its NSR rules and
submitting those revisions to EPA for a SIP-approved PSD rule.
b. Control of PM10 Precursor Pollutants
    Section 189(e) of the CAA requires that the control requirements
applicable under the part D SIP for major stationary sources of
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. As noted above, in our
approval action on the 1990 AQMP, we found that PM10
precursors do not contribute significantly to exceedances of the
PM10 standard in the Mammoth Lakes PM10 area (61
FR 32344, June 24, 1996). Using similar analytical techniques in
developing the Mammoth Lakes PM10 Maintenance Plan, GBUAPCD
confirmed that direct PM10 emissions are most likely to
cause or contribute to future violations of the NAAQS and addressed
these sources of direct PM10 in their maintenance plan
discussed below.
c. General and Transportation Conformity Requirements
    Section 176(c) of the CAA requires states to establish criteria and
procedures to ensure that federally supported or funded projects
conform to the air quality planning goals in the applicable SIP. The
requirement to determine conformity applies to transportation plans,
programs and projects developed, funded or approved under Title 23
U.S.C. and the Federal Transit Act (transportation conformity), as well
as to other federally-supported or funded projects (general
conformity). State conformity regulations must be consistent with
federal conformity regulations that the CAA required EPA to promulgate
relating to consultation, enforcement and enforceability.
    GBUAPCD's general conformity regulation, Regulation 13, was
submitted to EPA on October 5, 1994 and approved on April 23, 1999 (64
FR 19916).
    EPA has not approved a transportation conformity regulation for
Mammoth Lakes and the GBUAPCD. EPA believes, however, that it is
reasonable to interpret the conformity SIP requirements as not applying
for purposes of a redesignation request under section 107(d) because
state conformity rules are still required after redesignation, and
federal conformity rules apply where state rules have not been
approved.\25\
---------------------------------------------------------------------------

    \25\ See Wall v. EPA, 265 F. 3d 426 (6th Cir. 2001), upholding
this interpretation. Also, see 60 FR 62748 (December 7, 1995).
---------------------------------------------------------------------------

    In conclusion, if EPA finalizes today's proposal approving the
PM10 emissions inventory and motor vehicle emissions budgets
for the Mammoth Lakes PM10 nonattainment area, then EPA will
have determined the State has a fully-approved SIP meeting all
requirements applicable under section 110 and part D for the Mammoth
Lakes PM10 nonattainment area for purposes of redesignation,
per section 107(d)(3)(E)(v) of the CAA.

C. The Area Must Show the Improvement in Air Quality Is Due to
Permanent and Enforceable Emission Reductions

    Before redesignating an area to attainment of a NAAQS, section
107(d)(3)(E)(iii) of the CAA requires EPA to determine that the air
quality improvement in the Mammoth Lakes PM10 nonattainment
area is due to permanent and enforceable emission reductions resulting
from implementation of the applicable SIP and applicable federal air
pollution control regulations and other permanent and enforceable
regulations. Under this criterion, the State must reasonably be able to
attribute the improvement in air quality to emissions reductions that
are permanent and enforceable. Attainment resulting from temporary
reductions in emissions rates (e.g., reduced production or shutdown) or
unusually favorable meteorology would not qualify as an air quality
improvement due to permanent and enforceable emission reductions.\26\
As discussed earlier, EPA may rely on prior SIP approvals in approving
a redesignation request and any additional measures it may approve in
conjunction with a redesignation action. As noted earlier, GBUAPCD has
jurisdiction over air quality planning requirements for the Mammoth
Lakes PM10 nonattainment area and produced a moderate area
PM10 plan, the 1990 AQMP, and related rules designed to
reduce PM10 emissions in the Mammoth Lakes area so as to
meet the PM10 NAAQS.
---------------------------------------------------------------------------

    \26\ See the Calcagni memorandum, page 4.
---------------------------------------------------------------------------

    As discussed, GBUAPCD developed and California submitted the 1990
AQMP for the Mammoth Lakes nonattainment area on September 11, 1991.
The 1990 AQMP relied on two control measures to reduce PM10
emissions sufficient to meet the PM10 standard: GBUAPCD Rule
431--Particulate Emissions, adopted on November 6, 1991; and, Town of
Mammoth Lakes Municipal Code Chapter 8.30--Particulate Matter Emissions
Regulations, dated October 2, 1991. Both of these rules were
implemented so as to reduce emissions from the primary sources of
PM10 in the nonattainment area, fireplaces and woodstoves,
and re-suspended road dust and cinders from motor vehicles driving on
paved roads. In 1996, EPA approved the 1990 AQMP, GBUAPCD Rule 431, and
TMLMCC 8.30, incorporating them into the SIP (61 FR 32341, June 24,
1996). In this approval action, we found that the rules provided for
RACM and were sufficient to reduce PM10 to levels necessary
to meet the PM10 NAAQS. CARB cites figures from 1995 showing
that from 1990 to 1994 the percentage of cleaner burning EPA certified
wood burning devices in the area increased from 1 percent to 35
percent.\27\ Since 1994, the percentage of EPA-certified wood-burning
devices has increased to 84 percent in 2013.\28\ With regard to
entrained road dust PM10 emissions on paved roads, the
purchase and continued use of high efficiency vacuum street sweepers
have resulted in reducing PM10 emissions by as much as 68
percent from pre-1990 levels.\29\
---------------------------------------------------------------------------

    \27\ See ``Staff Report: Town of Mammoth Lakes PM10
Maintenance Plan and Redesignation Request,'' CARB, August 18, 2014,
page 5.
    \28\ See Mammoth Lakes PM10 Maintenance Plan, Table
5-1, page 18.
    \29\ See ``Staff Report: Town of Mammoth Lakes PM10
Maintenance Plan and Redesignation Request,'' CARB, August 18, 2014,
page 6.
---------------------------------------------------------------------------

    We are proposing to determine that the Mammoth Lakes area has
attained the PM10 standard continuously since 2009 according
to complete, quality-assured, and certified air quality data, per our
discussion in section V.A. of this proposal. In addition to our review
of air quality data supporting our proposed determination, the Mammoth
Lakes PM10 Maintenance Plan provided data showing that over
the period these two control measures were implemented and enforced,
1994 to the present, there have been no violations of the federal
PM10 standard.\30\ Also, see

Figures 4-1 and 4-2 of the Mammoth Lakes PM10 Maintenance
Plan showing how winter time average and peak ambient PM10
levels have fallen since 1990.
---------------------------------------------------------------------------

    \30\ See Table 2-1 in the Mammoth Lakes PM10
maintenance plan, page 10. We note that while the data record shows
falling PM10 levels and PM10 levels below the
NAAQS over the period of control measure implementation and
enforcement, the data record shown in Table 2-1 was not sufficient
to determine attainment of the PM10 NAAQS, until
recently. For instance, Table 2-1 shows periods where the
PM10 monitor was not operating and therefore not
providing a data record complete enough to determine attainment of
the PM10 NAAQS. See our prior discussion of data
requirements in our proposed determination that the area has
attained the PM10 standard in section V.A above.
---------------------------------------------------------------------------

    In conclusion, EPA is proposing to find that the improvement in
PM10 air quality for the Mammoth Lakes nonattainment area is
the result of permanent and enforceable reductions in emissions from
significant sources of PM10 in the area and, in accordance
with 107(d)(3)(E)(iii), is not the result of temporary reductions
(e.g., economic downturns or shutdowns) or unusually favorable
meteorology.

D. The Area Must Have a Fully Approved Maintenance Plan Under Clean Air
Act Section 175A

    Section 175A of the CAA describes the elements of a maintenance
plan for areas seeking redesignation from nonattainment to attainment.
We interpret this section of the CAA to require the following elements:
An attainment emissions inventory; a maintenance demonstration; a
monitoring network capable of verification of continued attainment
along with a commitment to do so; and, a contingency plan.\31\ Under
CAA section 175A, a maintenance plan must demonstrate continued
attainment of the relevant NAAQS for at least ten years after EPA
approves a redesignation to attainment. To address the possibility of
future NAAQS violations, the maintenance plan must contain contingency
provisions that EPA finds sufficient to correct promptly any violation
of the NAAQS that occurs after the area's redesignation. Based on our
review and evaluation provided below, we are proposing to approve the
Mammoth Lakes PM10 Maintenance Plan because it meets the
requirements of CAA section 175A.
---------------------------------------------------------------------------

    \31\ See Calcagni memorandum, pages 8 through 13.
---------------------------------------------------------------------------

    Before reviewing the Mammoth Lakes PM10 Maintenance Plan
and its components in more detail, it is important to provide a
description of the geography and the economy of the region. The Mammoth
Lakes area sits on the eastern slopes of the Sierra Nevada mountain
range on the western edge of the Long Valley Caldera in southwestern
Mono County, California. At the western boundary of the nonattainment
area, there is Mammoth Mountain at an elevation of 11,053 feet. From
the foot of Mammoth Mountain and the developed portion of the Town of
Mammoth Lakes at 7,891 feet elevation, the Mammoth Creek Valley slopes
to the east and down to the eastern edge of the PM10
nonattainment area near the Mammoth Lakes airport at 7,127 feet
elevation.\32\ Much of the area surrounding the Town of Mammoth Lakes
within and without the nonattainment area is public land, either
national forest or national monument lands.
---------------------------------------------------------------------------

    \32\ See Mammoth Lakes PM10 Maintenance Plan, Figures
1-1 and 1-2, page 3 and 4.
---------------------------------------------------------------------------

    The Town of Mammoth Lakes is the area's only population center and
the only incorporated community in Mono County with an estimated
permanent population of 8,234 in 2010.\33\ Within the Mammoth Lakes
PM10 nonattainment area and the boundaries of the Town of
Mammoth Lakes is the Mammoth Mountain ski area, west of the town
center. The ski area attracts 1.2 to 1.5 million visitors every winter,
swelling the Town of Mammoth Lakes population to approximately 35,000
people on a major winter weekend.\34\ The large number of winter time
visitors contribute to PM10 emissions from residential wood
burning and vehicle entrained dust from pulverized cinders that have
been applied to the paved roads to provide better vehicle traction on
snow-covered roads. In the 1990 AQMP and in the Maintenance Plan, these
two sources were determined to be the overwhelming contributors of
PM10 to potential exceedances of the NAAQS in the Mammoth
Lakes area.
---------------------------------------------------------------------------

    \33\ U. S. Census figure.
    \34\ See Mammoth Lakes PM10 Maintenance Plan at
Section 1.3, page 2.
---------------------------------------------------------------------------

1. Attainment and Projected Emissions Inventories
    Section 172(c)(3) of the CAA requires plan submittals to include a
comprehensive, accurate, and current inventory of emissions from all
sources in the nonattainment area. In demonstrating maintenance
according to CAA section 175A and the Calcagni memorandum, the State
should provide an attainment emissions inventory for the area so as to
identify the emissions level sufficient to attain the NAAQS. Where the
State has made an adequate demonstration that air quality has improved
as a result of the SIP, the attainment emissions inventory will
generally be an inventory of actual emissions at the time the area
attained the standard.\35\ A maintenance plan for the 24-hour
PM10 standard must include an inventory of emissions of
PM10 in the area to identify a level of emissions sufficient
to attain the 24-hour PM10 NAAQS. This inventory must be
consistent with EPA's most recent guidance on emissions inventories for
nonattainment areas available at the time and should represent
emissions during the time period associated with the monitoring data
showing attainment. The inventory must also be comprehensive, including
emissions from stationary point sources, area sources, and mobile
sources.
---------------------------------------------------------------------------

    \35\ EPA's primary guidance for evaluating these emissions
inventories is the document entitled, ``PM10 Emissions
Inventory Requirements,'' EPA, Office of Air Quality Planning and
Standards, EPA-454/R-94-033 (September 1994) which can be found at:
http://www.epa.gov/ttn/chief/eidocs/PM10eir.pdf.
---------------------------------------------------------------------------

    The Mammoth Lakes PM10 Maintenance Plan provides an
estimated daily PM10 emissions inventory for 2012 and 2030.
The year 2012 provides an appropriate attainment year inventory because
it is one of the years in the most recent three-year periods (2012
through 2014) in which attainment of the PM10 NAAQS was
monitored. Table 3 presents the PM10 emissions inventories
for 2012 and 2030 provided in the Mammoth Lakes PM10
Maintenance Plan.

  Table 3--2012 and 2030 Mammoth Lakes Nonattainment Area Peak 24 Hour
                             PM10 Emissions
                         [kilograms/winter day]
------------------------------------------------------------------------
             Source category                   2012            2030
------------------------------------------------------------------------
Residential Wood Combustion Sources.....             850             802
Entrained Road Dust Cinders/Paved Roads.           3,455           4,305
On-road Mobile Sources (exhaust, tire                 11              14
 and brake wear)........................

Stationary--Point Sources...............               8               8
                                         -------------------------------
    Total PM10..........................           4,324           5,129
------------------------------------------------------------------------
Source: Mammoth Lakes PM10 Maintenance Plan, Tables 5-7, 8-1, and 8-3,
  pages 22, 36, and 37.

    The Mammoth Lakes PM10 Maintenance Plan's emissions
inventory for sources within the Mammoth Lakes nonattainment area air
basin is subdivided into four subcategories: residential wood
combustion, entrained road dust and cinders, on-road mobile sources,
and stationary sources. Because the most consistently elevated values
of ambient PM10 concentrations occur in the winter, sources
like construction dust and fugitive dust from unpaved roads are not
accounted for in this inventory. In the Mammoth Lakes area,
construction activity is seasonal and inactive during the winter due to
the wet and cold climate. Similarly, unpaved roads are snow covered or
rarely used due to wet conditions; in either case, little fugitive dust
is generated by vehicle use on unpaved roads. As shown in Table 3,
direct PM10 emissions in the Mammoth Lakes area are
dominated by entrained road dust from paved roads and residential wood
combustion. The estimates for peak winter day PM10 emissions
incorporate the highest ski season visitors and vehicle miles traveled
(VMT) estimates in the calculation for both entrained paved road dust
and on-road mobile emissions. GBUAPCD used a chemical mass balance
(CMB) analysis to determine if PM10 precursors were
affecting PM10 values at the Gateway Center monitor/
receptor. CMB uses chemical profiles of emission sources to apportion
the monitored concentration between the various source types. The CMB
study showed that on representative days of high PM10
concentrations the total contribution of nitrates, sulfates, and
ammonium was approximately 1-2% of total mass collected. Consistent
with the large contributions from entrained road dust and residential
wood combustion the largest contributors to PM10
concentrations were organic carbon, elemental carbon, and soil.\36\
---------------------------------------------------------------------------

    \36\ See Mammoth Lakes PM10 Maintenance Plan,
Appendix G, ``Chemical Analysis of PM10 and
PM2.5 Filters from Mammoth Lakes'', Desert Research
Institute, May 21, 2013; see Table 3, page 3.
---------------------------------------------------------------------------

    GBUAPCD projects that overall, direct PM10 emissions
will increase from 2012 to 2030 because of a general and winter-time
tourist population increase due to build out of the Town of Mammoth
Lakes. While higher emitting wood combustion sources will be replaced
by cleaner burning devices or removed entirely, population growth and
resulting VMT growth will drive the predicted increase in entrained
road dust. The District's maintenance demonstration modeling and
supporting analyses indicate that despite the population and VMT
growth, the Mammoth Lakes nonattainment area will continue to attain
the federal 24-hour PM10 standard because of the relative
importance and continuing decline of residential wood combustion
emissions. The overall predicted result is a slight increase in ambient
PM10 levels over the 2012 to 2030 timeframe. We will review
the maintenance demonstration and 2030 predicted PM10
concentrations in greater detail in the next section of this action.
    In conclusion, GBUAPCD's selection of 2012 as the attainment year
inventory is appropriate since the area was determined to have attained
the NAAQS during the 2011 to 2013 period. Based on our review of the
Mammoth Lakes PM10 Maintenance Plan, we propose to find that
the emissions inventories for 2012 and 2030 are comprehensive, current,
and accurate in that they include estimates of PM10 from all
of the relevant source categories, residential wood combustion,
entrained road dust, on-road mobile sources, and stationary sources.
Therefore, we are proposing to approve the 2012 emissions inventory,
which serves as the Mammoth Lakes PM10 Maintenance Plan's
attainment year inventory, as satisfying the requirements of section
172(c)(3) of the CAA for the purposes of redesignation of the Mammoth
Lakes PM10 nonattainment area to attainment of the 24-hour
PM10 NAAQS.
2. Maintenance Demonstration
    Section 175A(a) of the CAA requires a demonstration of maintenance
of the NAAQS for at least 10 years after redesignation. Generally, a
State may demonstrate maintenance of the NAAQS by either showing that
future emissions of a pollutant or its precursors will not exceed the
level of the attainment inventory, or by modeling to show that the
future anticipated mix of sources and emission rates will not cause a
violation of the NAAQS. For areas that are required under the CAA to
submit modeled attainment demonstrations, the maintenance demonstration
should use the same type of modeling.\37\
---------------------------------------------------------------------------

    \37\ See Calcagni memorandum, page 9.
---------------------------------------------------------------------------

    In the Mammoth Lakes PM10 Maintenance Plan, GBUAPCD
chose to use modeling to demonstrate maintenance of the 24-hour
PM10 NAAQS and to show that the future anticipated mix of
sources and emission rates will not cause a violation of the NAAQS in
the Mammoth Lakes area. The maintenance demonstration builds upon the
previous 1990 AQMP attainment plan, and incorporates the specifics of
the Mammoth Lakes area, including geography, the winter-time peak
visitor population, and the contribution of the two major sources of
PM10, residential wood combustion and entrained dust from
paved roads. Below, we review the maintenance demonstration in more
detail.
    To be consistent with the 1990 AQMP attainment demonstration,
GBUAPCD limited the area modeled in the maintenance demonstration to
the Town of Mammoth Lakes boundary, somewhat smaller than the larger
nonattainment area boundary.\38\ This was done for two reasons. First,
the land east of the Town boundary is mostly public lands, is sparsely
populated, and is downhill from the PM10 monitoring station
located within the Town. Almost all of the human population and
developed land in the nonattainment area is situated and concentrated
within a smaller portion of the larger Township. The PM10
monitor/receptor at Gateway Center, providing much of the data for the
maintenance demonstration, is located there, too. Meteorologically, an
analysis of wind speeds and wind directions on high winter
PM10 days shows that hourly wind speeds are low (less than 2
meters/second) and

primarily from the west.\39\ In these near stagnant air mass
conditions, the observed wind direction and speed most likely result
from cold air flows moving downhill from higher to lower elevations. As
a result, on design days of likely high PM10 observations,
PM10 emissions east of the Town of Mammoth Lakes are
unlikely to affect the levels observed at the PM10 monitor/
receptor because those emissions would be moving away, further downhill
and to the east. Consequently, an in-Town emissions inventory is the
more appropriate inventory of PM10 sources contributing to
high PM10 values observed at the Gateway Center
PM10 monitor. This in-Town emissions inventory accounts for
78 percent of the total area emissions inventory described in the
preceding section of this notice.\40\ The excluded PM10
emissions are almost entirely entrained road dust produced east and
downhill from the PM10 monitor/receptor at Gateway Center in
the Town of Mammoth Lakes.
---------------------------------------------------------------------------

    \38\ See Mammoth Lakes PM10 Maintenance Plan, Figure
1-2, page 4.
    \39\ See Mammoth Lakes PM10 Maintenance Plan, Chapter
5.0 page 17.
    \40\ See Mammoth Lakes PM10 Maintenance Plan, Table
8-3, page 37.
---------------------------------------------------------------------------

    The second point of comparison with the 1990 AQMP attainment
demonstration and maintenance demonstration is the use of a chemical
mass balance (CMB) analysis to determine the emissions sources
affecting PM10 values at the monitor/receptor. CMB uses
chemical profiles of emission sources to apportion the monitored
concentration between the various source types. The 1990 AQMP's
attainment demonstration and emissions inventory showed that the
primary sources contributing to exceedances of the PM10
NAAQS were residential wood combustion and entrained dust from vehicle
traffic. Using a second CMB study and a new emissions inventory,
GBUAPCD confirmed that the same two sources continue to
disproportionately affect PM10 levels in the Mammoth Lakes
area.\41\ The 2013 CMB analysis done for the maintenance demonstration
also provides critical inputs for the linear rollback analysis
described next.
---------------------------------------------------------------------------

    \41\ See Mammoth Lakes PM10 Maintenance Plan, Chapter
6, page 23; Table 6-4, page 26; and Appendix G.
---------------------------------------------------------------------------

    The maintenance demonstration modeling is based on a linear
rollback methodology. In a linear rollback model, a fundamental
assumption is that the ambient concentration attributed to a given
source is proportional to emissions from that source. The rollback
model used by GBUAPCD incorporated the following parameters: A
background PM10 concentration of 5 [mu]g/m\3\; a
PM10 design value concentration of 99 [mu]g/m\3\ based on
2010 through 2012 observations at the Gateway Center monitoring site;
peak winter season VMT based on peak winter season visitor population
consistent with a 2025 Town build out under the 2007 Town of Mammoth
Lakes General Plan; and, in-Town peak winter PM10 emissions
estimated for residential wood combustion and entrained road dust on
paved roads.\42\ The maintenance demonstration analyzed two worst case
design day scenarios: (1) a day indicative of highest residential wood
smoke conditions; and, (2) a day indicative of highest entrained road
dust emissions.\43\ The proportionalities for residential wood sources
and entrained road dust used within the rollback model scenarios are
derived from the 2013 CMB source apportionment studies discussed in
Chapter 6 and Appendix G of the maintenance plan. In the first scenario
of highest residential wood smoke emissions, the predicted 2030
PM10 concentration was 100 [mu]g/m\3\.\44\ In the second
scenario of highest entrained road dust emissions, the predicted 2030
PM10 concentration was 104.8 [mu]g/m\3\.\45\ In either
scenario, PM10 concentrations are predicted to remain below
the PM10 NAAQS of 150 [mu]g/m\3\ and are slightly higher
than the 2010-2012 attainment design value concentration of 99 [mu]g/
m\3\.
---------------------------------------------------------------------------

    \42\ See the Mammoth Lakes PM10 Maintenance Plan,
Chapter 8, pages 36-42; Table 8-4, page 38; and, the Executive
Summary at page x for population and VMT discussion.
    \43\ See the Mammoth Lakes PM10 Maintenance Plan
Chapter 8.3, page 39, for calculations.
    \44\ See the Mammoth Lakes PM10 Maintenance Plan
Chapter 8.4, page 40, and Table 8-6, page 41.
    \45\ See the Mammoth Lakes PM10 Maintenance Plan
Chapter 8.4, page 40, and Table 8-7, page 42.
---------------------------------------------------------------------------

    To conclude, EPA proposes to find that the forecasted increases in
PM10 levels from 2012 to 2030 are consistent with the
control measures currently implemented and are not anticipated to
result in PM10 levels above the PM10 NAAQS, as
shown in the maintenance demonstration described above. Based on our
review of the information presented in the Mammoth Lakes
PM10 Maintenance Plan, we propose to find that the State has
shown that attainment of the PM10 standard will be
maintained in the Town of Mammoth Lakes and the larger Mammoth Lakes
area for at least 10 years after redesignation.
3. Monitoring Network and Verifying Continued Attainment
    Continued attainment of the NAAQS can be verified through operation
of an appropriate air quality monitoring network. The Calcagni
memorandum states that the maintenance plan should contain provisions
for continued operation of air quality monitors that will provide such
verification.\46\ GBUAPCD has committed to continue to operate an
appropriate air quality monitoring network in accordance with 40 CFR
part 58, to continue daily monitoring of PM10 at the
existing monitoring site so as to verify the ongoing attainment status
of the area.\47\ As we discussed in Section V.A. of this proposal,
GBUAPCD's monitoring network for PM10 and the Mammoth Lakes
PM10 monitors are part of an EPA-approved air quality
monitoring network.
---------------------------------------------------------------------------

    \46\ See Calcagni memorandum, page 11.
    \47\ See Mammoth Lakes PM10 Maintenance Plan, Chapter
9.2.2, page 45.
---------------------------------------------------------------------------

4. Contingency Provisions
    Under section 175A of the CAA, contingency provisions are required
for maintenance plans to correct promptly any violations of the NAAQS
that occur after the area is redesignated to attainment. These
contingency provisions must include a requirement that the State will
implement all measures with respect to the control of the air pollutant
concerned that were contained in the SIP for the area before
redesignation of the area to attainment. These contingency provisions
are distinguished from those generally required for nonattainment areas
under section 172(c)(9) because they are not required to be fully-
adopted measures that will take effect without further action by the
State before the maintenance plan can be approved. The contingency plan
is considered, however, to be an enforceable part of the SIP and should
ensure that the contingency measures are adopted expeditiously once
they are triggered by a specified event.
    The Calcagni memorandum states that the contingency provisions of
the maintenance plan should identify the measures to be adopted, a
schedule and procedure for adoption and implementation, and a time
limit for action by the State. The memo also states that the
contingency provisions should identify indicators or triggers which
will be used to determine when the contingency measures need to be
implemented. While the memo suggests inventory or monitoring
indicators, it states that contingency provisions will be evaluated on
a case-by-case basis.
    In several actions, EPA has long approved contingency provisions
that rely on reductions from measures that are already in place but are
over and above those relied on for attainment and

RFP under section 172(c)(9) of the CAA (62 FR 15844, April 3, 1997),
(62 FR 6627, December 18, 1997), (66 FR 30811, June 8, 2001), (66 FR
586 and 66 FR 634, January 3, 2001). This interpretation has been
upheld in LEAN v. EPA, 382 F.3d 575 (5th Cir. 2004), where the court
set forth its reasoning for accepting excess reductions from already
adopted measures as contingency measures.
    Our interpretation that excess emission reductions can
appropriately serve as section 172(c)(9) contingency measures is
equally applicable to section 175A(d) contingency measures. EPA has
approved maintenance plans under section 175A that included contingency
provisions relying on measures to be implemented prior to any post-
redesignation NAAQS violation (60 FR 27028, May 22, 1995) and (73 FR
66759, November 12, 2008).
    As required by section 175A of the CAA, GBUAPCD adopted a
contingency plan to address possible future PM10 air quality
problems. The contingency provisions in the Mammoth Lakes
PM10 Maintenance Plan are contained in Chapter 9.1.2 of the
plan. In the event of a violation of the PM10 NAAQS, the
District commits to adopt additional control measures to meet the
PM10 NAAQS within 18 months of the violation; the measures
cited may include reducing the ``no burn day'' trigger threshold, or
improving roadway clean-up procedures.\48\ Also, the District commits
to track the progress of the maintenance plan and the continuing
validity of its analyses and assumptions, such as an updated peak
winter day emissions inventory and an analysis of air quality
trends.\49\ Finally, the District commits to continued implementation
of plan's control measures, continued performance of ambient air
quality monitoring, as well as the progress reports described
previously.\50\
---------------------------------------------------------------------------

    \48\ See the Mammoth Lakes Maintenance Plan Chapter 9.1.2, page
44.
    \49\ See the Mammoth Lakes Maintenance Plan Chapter 9.2.1, pages
44-45.
    \50\ See the Mammoth Lakes Maintenance Plan Chapter 9.3, page
45.
---------------------------------------------------------------------------

    To summarize, given the commitments described above, EPA is
proposing to find that the Mammoth Lakes PM10 Maintenance
Plan is consistent with the maintenance plan contingency provision
requirements of the CAA and EPA guidance. The contingency provisions of
the maintenance plan contain tracking and triggering mechanisms to
determine when contingency measures are needed, and specific timelines
for action. Thus, we conclude that the contingency provisions of the
Mammoth Lakes PM10 Maintenance Plan are adequate to ensure
prompt correction of a violation of the PM10 NAAQS and
comply with section 175A(d) of the Act.

E. Transportation Conformity and Motor Vehicle Emissions Budgets

    Under section 176(c) of the CAA, transportation plans, programs and
projects in the nonattainment or maintenance areas that are funded or
approved under title 23 U.S.C. and the Federal Transit Laws (49 U.S.C.
chapter 53) must conform to the applicable SIP. In short, a
transportation plan and program conforms to the applicable SIP if the
emissions resulting from the implementation of that transportation plan
and program are less than or equal to the motor vehicle emissions
budgets (budgets) established in the SIP for the attainment year,
maintenance year and other years.\51\ The budgets serve as a ceiling on
emissions that would result from an area's planned transportation
system. The budget concept is explained in the preamble to the
transportation conformity rule (58 FR 62188, November 24, 1993). The
preamble describes how to establish budgets in the SIP and how to
revise the budgets.
---------------------------------------------------------------------------

    \51\ See 40 CFR part 93 for the federal conformity regulations
and 40 CFR 93.118 specifically for how budgets are used in
conformity.
---------------------------------------------------------------------------

    Maintenance plan submittals must specify the maximum emissions of
transportation-related PM10 and PM10 precursor
emissions allowed in the last year of the maintenance period, i.e., the
budgets.\52\ Budgets may also be specified for additional years during
the maintenance period. The submittal must also demonstrate that these
emissions levels, when considered with emissions from all other
sources, are consistent with maintenance of the NAAQS. For EPA to find
these emissions levels or budgets adequate and approvable, the
submittal must meet the conformity adequacy provisions of 40 CFR
93.118(e)(4) and (5).
---------------------------------------------------------------------------

    \52\ Transportation-related emissions of volatile organic
compounds (VOC) and/or oxides of nitrogen (NOX) emissions
must also be specified in PM10 areas if EPA or the state
finds that transportation-related emissions of one or both of these
precursors within the nonattainment area are a significant
contributor to the PM10 nonattainment problem and has so
notified the metropolitan planning organization (MPO) and the U.S.
Department of Transportation (DOT), or if the applicable SIP
revision or SIP revision submittal establishes an approved or
adequate budget for such emissions as part of the RFP, attainment or
maintenance strategy. See 40 CFR 93.102(b)(2)(iii). Neither of these
conditions apply to the Mammoth Lake PM10 nonattainment
area. Consequently, the Mammoth Lakes PM10 Maintenance
Plan establishes motor vehicle emissions budgets for PM10
only and does not include PM10 precursors.
---------------------------------------------------------------------------

    EPA's process for determining adequacy of a budget consists of
three basic steps: (1) Notifying the public of a SIP submittal; (2)
providing the public the opportunity to comment on the budget during a
public comment period; and, (3) making a finding of adequacy or
inadequacy. The process for determining the adequacy of a submitted
budget is codified at 40 CFR 93.118(f). EPA can notify the public by
either posting an announcement that EPA has received SIP budgets on
EPA's adequacy Web site (40 CFR 93.118(f)(1)), or via a Federal
Register notice of proposed rulemaking when EPA reviews the adequacy of
an implementation plan budget simultaneously with its review and action
on the SIP itself (40 CFR 93.118(f)(2)).\53\
---------------------------------------------------------------------------

    \53\ The availability of the SIP submittal with budgets can be
announced for public comment on EPA's adequacy Web site at http://www.epa.gov/otaq/stateresources/transconf/currsips.htm which
provides a 30-day public comment period. The public can then comment
directly on this Web site.
---------------------------------------------------------------------------

    Today, we are notifying the public that EPA will be reviewing the
adequacy of the 2012 and 2030 budgets in the Mammoth Lakes
PM10 Maintenance Plan. The public has a 30-day comment
period as described in the DATES section of this notice. After this
comment period, EPA will indicate whether the budgets are adequate via
the final rulemaking on this proposed action or on the adequacy Web
site, according to 40 CFR 93.118(f)(2)(iii). EPA's adequacy review is
provided in the subject Memorandum accompanying today's Federal
Register notice and included in the docket for this action.
    During GBUAPCD's 30-day comment period prior to the District Board
adopting the Mammoth Lakes PM10 Maintenance Plan, District
staff amended the budgets in a response to comments from EPA.
Consequently, the budget considered and adopted by the District Board
and transmitted to CARB was not the budget released to the general
public at the start of the District's public comment period. To fully
comply with public notice requirements for SIP revisions prior to
submittal by the State, CARB provided a full 30-day comment period and
public hearing for the GBUAPCD Board adopted version of the Mammoth
Lakes PM10 Maintenance Plan and the budgets contained
therein.\54\
---------------------------------------------------------------------------

    \54\ For the budgets as presented and adopted by CARB, see their
``Staff Report: Town of Mammoth Lakes PM10 Maintenance
Plan and Redesignation Request'', dated August 18, 2014 at Table 3,
page 10. For evidence of CARB's public notice and hearing see our
earlier discussion of procedural requirements and CARB's
documentation included in the docket for this action.
---------------------------------------------------------------------------

    The Mammoth Lakes PM10 Maintenance Plan submitted by the

State contains PM10 budgets for the entire Mammoth Lakes
PM10 nonattainment area for the years 2012 and 2030. The
PM10 budgets for the Mammoth Lakes nonattainment area are as
follows: 2012--3,466 kilograms per day; and, 2030--4,319 kilograms per
day.\55\ These budgets include direct PM10 emissions from
vehicle exhaust, tire and brake wear emissions, and entrained dust on
paved roads due to vehicle travel. See Table 4. These budgets do not
include road construction dust or fugitive dust from vehicle travel on
unpaved roads because emissions from these sources are minimal during
the winter; see our earlier review of the Mammoth Lakes PM10
Maintenance Plan emissions inventory. As noted in our emission
inventory review, PM10 precursors are a very small component
of the overall inventory and a negligible contribution to the budgets.
The on-road mobile source PM10 emissions (motor vehicle
exhaust, tire and brake wear) were calculated using the latest approved
emission factor model, EMFAC2011.\56\ The fugitive dust emissions for
paved roads were calculated using the latest version of the Compilation
of Air Pollutant Emission Factors (AP-42).\57\
---------------------------------------------------------------------------

    \55\ See the Mammoth Lakes PM10 Maintenance Plan
Chapter 10, page 47.
    \56\ See the Mammoth Lakes PM10 Maintenance Plan
Chapter 5.7, page 21. Also see 78 FR 14533 (March 6, 2013) for our
approval of EMFAC2011.
    \57\ January 2011 Version of AP42, Fifth Edition, Volume I,
Chapter 13.2.1 Miscellaneous Sources, Paved Roads: http://www.epa.gov/ttn/chief/ap42/ch13/final/c13s0201.pdf.

  Table 4--Mammoth Lakes PM10 Maintenance Plan 2012 and 2030 PM10 Motor
                        Vehicle Emissions Budgets
                             [Kilograms/day]
------------------------------------------------------------------------
             Source category                   2012            2030
------------------------------------------------------------------------
Entrained Road Dust Cinders/Paved Roads.           3,455           4,305
On-road Mobile Sources (tailpipe, tire                11              14
 and brake wear)........................
                                         -------------------------------
    Total Motor Vehicle Emissions Budget           3,466           4,319
------------------------------------------------------------------------
Peak 24-hour winter PM10 emissions calculated for the entire planning
  area.
Source: Mammoth Lakes PM10 Maintenance Plan, Tables 5-7, 8-1, and 8-3,
  pages 22, 36, and 37, respectively; also, see page 47.

    As previously discussed in our review of the maintenance
demonstration for the Mammoth Lakes PM10 Maintenance Plan,
for reasons related to the topography, economy, and winter time
meteorology of the Mammoth Lakes area, GBUAPCD modeled within the
maintenance demonstration an area equivalent to the Township of Mammoth
Lakes boundaries and smaller than the total nonattainment area.
Although EPA concurs with the rationale for using an in-town
PM10 emissions inventory in the maintenance demonstration,
EPA also modeled the total area emissions shown in Table 4 to ensure
that the higher estimated emissions do not, as we anticipate, cause or
contribute to future violations of the ambient 24-hour PM10
standard. Using the same methodology as the maintenance demonstration
and the modeling scenario of highest ambient contribution of entrained
road dust emissions, we found that the predicted 2030 ambient
PM10 concentration was 104.8 [mu]g/m\3\, well below the
standard and consistent with the concentration calculated in the
maintenance demonstration for the same scenario.\58\
---------------------------------------------------------------------------

    \58\ See the Mammoth Lakes Maintenance Plan, Chapter 8.3, page
39 for the maintenance demonstration methodology and model equation.
Also, see our prior discussion of the emissions inventory and
maintenance demonstration for model equation inputs, such as
background concentration and residential wood smoke emissions. For
our calculations, see the Memorandum regarding our documentation
supporting our budgets adequacy determination in the docket for this
action.
---------------------------------------------------------------------------

    Based on the information presented in the Mammoth Lakes
PM10 Maintenance Plan and our adequacy review to date, we
propose to approve the motor vehicle emissions budgets in the Mammoth
Lakes PM10 Maintenance Plan as meeting the requirements of
the CAA and EPA regulations. EPA has determined that the budgets are
consistent with control measures in the SIP and are consistent with
maintenance of the 24-hour PM10 standard within the Mammoth
Lakes area through 2030. The details of EPA's evaluation of the budget
for compliance with the budget adequacy criteria of 40 CFR 93.118(e)
are provided in a separate memorandum included within the docket for
this rulemaking.\59\ As noted earlier, the public comment period for
EPA's adequacy finding will be concurrent with the public comment
period for this proposed action on the Mammoth Lakes PM10
Maintenance Plan.
---------------------------------------------------------------------------

    \59\ See EPA memorandum titled, ``EPA's Adequacy Review of Motor
Vehicle Emissions Budgets in Mammoth Lakes PM10
Maintenance Plan'', dated July 1, 2015.
---------------------------------------------------------------------------

VI. Proposed Action and Request for Public Comment

    Based on our review of the Mammoth Lakes PM10
Maintenance Plan and redesignation request submitted by California, air
quality monitoring data, and other relevant materials contained on our
docket, EPA is proposing to find that the State has addressed all the
necessary requirements for redesignation of the Mammoth Lakes
nonattainment area to attainment of the PM10 NAAQS, pursuant
to CAA sections 107(d)(3)(E) and 175A.
    First, under CAA section 107(d)(3)(D), we are proposing to approve
the State's request, which accompanied the submittal of the Mammoth
Lakes PM10 Maintenance Plan, to redesignate the Mammoth
Lakes PM10 nonattainment area to attainment for the 24-hour
PM10 NAAQS. We are doing so based on our conclusion that the
area has met the five criteria for redesignation under CAA section
107(d)(3)(E): (1) The area has attained the 24-hour PM10
NAAQS; (2) the relevant portions of the SIP are fully approved; (3) the
improvement in air quality in the Mammoth Lakes area is due to
permanent and enforceable reductions in PM10 emissions; (4)
California has met all requirements applicable to the Mammoth Lakes
PM10 nonattainment area with respect to section 110 and part
D of the CAA; and, (5) our proposed approval of the Mammoth Lakes
PM10 Maintenance Plan, as part of this action.
    Second, under section 110(k)(3) of the CAA, EPA proposes to approve
the Mammoth Lakes PM10 Maintenance Plan and find that it
meets the requirements of Section 175A. We propose to find that the
maintenance demonstration shows that the area will continue to attain
the 24-hour PM10 NAAQS for at least 10 years beyond
redesignation (i.e., through 2030). We propose to find that the
Maintenance Plan provides a contingency process for identifying and
adopting new or more stringent control measures if a

monitored violation of the PM10 NAAQS occurs. Finally, we
are proposing to approve the 2012 emissions inventory as meeting
applicable requirements for emissions inventories in Section 172 of the
CAA.
    Last, we propose that the Maintenance Plan's motor vehicle
emissions budgets meet applicable CAA requirements for maintenance
plans and transportation conformity requirements under 40 CFR
93.118(e). With this action, we are starting the public comment period
on the adequacy of these proposed motor vehicle emissions budgets.
    We are soliciting comments on this proposed action. We will accept
comments from the public on this proposal for 30 days following
publication of this proposal in the Federal Register. We will consider
these comments before taking final action.

VII. Statutory and Executive Order Reviews

    Under the Clean Air Act, the Administrator is required to approve a
SIP submission that complies with the provisions of the Act and
applicable Federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a).
Thus, in reviewing SIP submissions, EPA's role is to approve State
choices, provided that they meet the criteria of the Clean Air Act.
Accordingly, this proposed action merely proposes to approve State law
as meeting Federal requirements and does not impose additional
requirements beyond those imposed by State law. For that reason, this
proposed action:
     Is not a ``significant regulatory action'' subject to
review by the Office of Management and Budget under Executive Order
12866 (58 FR 51735, October 4, 1993);
     does not impose an information collection burden under the
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
     is certified as not having a significant economic impact
on a substantial number of small entities under the Regulatory
Flexibility Act (5 U.S.C. 601 et seq.);
     does not contain any unfunded mandate or significantly or
uniquely affect small governments, as described in the Unfunded
Mandates Reform Act of 1995 (Pub. L. 104-4);
     does not have Federalism implications as specified in
Executive Order 13132 (64 FR 43255, August 10, 1999);
     is not an economically significant regulatory action based
on health or safety risks subject to Executive Order 13045 (62 FR
19885, April 23, 1997);
     is not a significant regulatory action subject to
Executive Order 13211 (66 FR 28355, May 22, 2001);
     is not subject to requirements of Section 12(d) of the
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272
note) because application of those requirements would be inconsistent
with the Clean Air Act; and,
     does not provide EPA with the discretionary authority to
address disproportionate human health or environmental effects with
practical, appropriate, and legally permissible methods under Executive
Order 12898 (59 FR 7629, February 16, 1994).
    In addition, this proposed action does not apply on any Indian
reservation land or in any other area where EPA or an Indian tribe has
demonstrated that a tribe has jurisdiction. In those areas of Indian
country, the rule does not have tribal implications and will not impose
substantial direct costs on tribal governments or preempt tribal law as
specified by Executive Order 13175 (65 FR 67249, November 9, 2000).

List of Subjects

40 CFR Part 52

    Environmental protection, Air pollution control, Incorporation by
reference, Intergovernmental relations, Particulate matter, Reporting
and recordkeeping requirements.

40 CFR Part 81

    Environmental protection, Air pollution control, National parks,
Wilderness areas.

    Authority:  42 U.S.C. 7401 et seq.

    Dated: July 10, 2015.
Jared Blumenfeld,
Regional Administrator, Region IX.
[FR Doc. 2015-18531 Filed 7-29-15; 8:45 am]
 BILLING CODE 6560-50-P