[Federal Register Volume 80, Number 146 (Thursday, July 30, 2015)]
[Proposed Rules]
[Pages 45477-45491]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[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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[[Page 45478]]

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

[[Page 45479]]

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

[[Page 45480]]

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,

[[Page 45481]]

(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).

[[Page 45482]]



   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

[[Page 45483]]

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

[[Page 45484]]

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,

[[Page 45485]]

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

[[Page 45486]]

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)........................

[[Page 45487]]

 
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

[[Page 45488]]

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

[[Page 45489]]

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

[[Page 45490]]

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

[[Page 45491]]

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