[Federal Register Volume 80, Number 189 (Wednesday, September 30, 2015)]
[Proposed Rules]
[Pages 58640-58658]
[FR Doc No: 2015-24854]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 52 and 81

[EPA-R09-OAR-2015-0633; FRL-9934-94-Region 9]

PM[bdi1][bdi0] Plans and Redesignation Request; Truckee Meadows,
Nevada; Deletion of TSP Area Designation

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to
approve two revisions to the Nevada state implementation plan (SIP).
The first revision provides a demonstration of implementation of best
available control measures (BACM) for control of particulate matter
with an aerodynamic diameter less than or equal to a nominal ten
micrometers (PM10) within Truckee Meadows. The second
revision is a plan that provides for the maintenance of the national
ambient air quality standard for PM10 in Truckee Meadows
through 2030, includes an emissions inventory consistent with
attainment, and establishes motor vehicle emissions budgets. In
connection with these proposed approvals, the EPA is proposing to
determine that major stationary sources of PM10 precursors
do not contribute significantly to elevated PM10 levels in
the area. Also, based in part on the proposed approvals of the BACM
demonstration and maintenance plan and proposed determination regarding
PM10 precursors, the EPA is proposing to approve the State
of Nevada's request for redesignation of the Truckee Meadows
nonattainment area to attainment for the PM10 standard.
Lastly, the EPA is proposing to delete the area designation for Truckee
Meadows for the revoked national ambient air quality standard for total
suspended particulate (TSP). The EPA is proposing these actions because
the SIP revisions meet the applicable statutory and regulatory
requirements for such plans and related motor vehicle emissions budgets
and because the area meets the Clean Air Act requirements for
redesignation of nonattainment areas to attainment.

DATES: Comments must be received on or before October 30, 2015.

ADDRESSES: Submit your comments, identified by Docket ID Number EPA-
R09-OAR-2015-0633, by one of the following methods:
    1. http://www.regulations.gov: Follow the on-line instructions for
submitting comments.
    2. Email<EMAIL_ADDRESS>    3. Mail or deliver: John Ungvarsky (AIR-2), U.S. Environmental
Protection Agency, Region IX, 75 Hawthorne Street, San Francisco, CA
94105-3901. Deliveries are only accepted during the Regional Office's
normal hours of operation.
    Instructions: All comments will be included in the public docket
without change and may be made available online at http://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 the EPA will not know your identity or
contact information unless you provide it in the body of your comment.
If you send email directly to EPA, your email address will be
automatically captured and included as part of the public comment. If
the EPA cannot read your comment due to technical difficulties and
cannot contact you for clarification, the EPA may not be able to
consider your comment.
    Docket: The index to the docket and documents in the docket for
this action are generally available electronically at
www.regulations.gov and in hard copy 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: John Ungvarsky, Air Planning Office
(AIR-2), U.S. Environmental Protection Agency,

Region IX,<PHONE_NUMBER><EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION: Throughout this document, whenever ``we,''
``us,'' or ``our'' is used, we mean the EPA. This supplementary
information section is arranged as follows:

Table of Contents

I. Background
II. The State's Submittals
III. Procedural Requirements for Adoption and Submittal of SIP
Revisions
IV. Clean Air Act Requirements for Redesignation to Attainment
V. Evaluation of the State's Redesignation Request for Truckee
Meadows
    A. The Area Has Attained the PM10 NAAQS
    B. The Area Has Met All Applicable Requirements for Purposes of
Redesignation Under Section 110 and Part D of the CAA and Has a
Fully Approved Applicable Implementation Plan Under Section 110(k)
of the CAA
    1. Basic SIP Requirements Under CAA Section 110
    2. SIP Requirements Under Part D
    a. Emissions Inventory
    b. Permits for New and Modified Stationary Sources
    c. Best Available Control Measures
    d. Control Requirements for PM10 Precursors
    e. Transportation Conformity
    3. Conclusion With Respect to Section 110 and Part D
Requirements
    C. The Improvement in Air Quality Is Due to Permanent and
Enforceable Reductions in Emissions
    D. The Area Has a Fully-Approved Maintenance Plan, Including a
Contingency Plan, Under CAA Section 175A
    1. Attainment Inventory
    2. Maintenance Demonstration
    3. Monitoring Network
    4. Verification of Continued Attainment
    5. Contingency Plan
    6. Transportation Conformity and Motor Vehicle Emissions Budgets
    7. Conclusion
VI. Proposed Deletion of TSP Designation for Truckee Meadows
    A. General Considerations
    B. Deletion of TSP Nonattainment Area Designation for Truckee
Meadows
VII. Proposed Actions and Request for Public Comment
VIII. Statutory and Executive Order Reviews

I. Background

    On April 30, 1971 (36 FR 8186), pursuant to section 109 of the
Clean Air Act (CAA), as amended in 1970, the EPA promulgated the
original national ambient air quality standards (NAAQS or
``standards'') for the ``criteria'' pollutants, which included carbon
monoxide, hydrocarbons, nitrogen dioxide, photochemical oxidant, sulfur
dioxide, and particulate matter.\1\ The NAAQS are set at concentrations
intended to protect public health and welfare. The original NAAQS for
particulate matter were defined in terms of a reference method that
called for measuring particulate matter up to a nominal size of 25 to
45 micrometers or microns. This fraction of total ambient particulate
matter is referred to as ``total suspended particulate'' or TSP. Within
nine months of promulgation of the original NAAQS, each state was
required under section 110 of the 1970 amended Act to adopt and submit
to the EPA a plan, referred to as a SIP, which provides for the
implementation, maintenance, and enforcement of each of the NAAQS
within each State. The State of Nevada submitted its SIP on January 28,
1972, and the EPA took action on it later that year. 37 FR 10842 (May
31, 1972).
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    \1\ Particulate matter is the generic term for a broad class of
chemically and physically diverse substances that exist as discrete
particles (liquid droplets or solids) over a wide range of sizes.
Particles originate from a variety of anthropogenic stationary and
mobile sources as well as from natural sources. Particles may be
emitted directly or form in the atmosphere by transformations of
gaseous emissions such as sulfur oxides (SOX), nitrogen
oxides (NOX), and volatile organic compounds (VOC). The
chemical and physical properties of particulate matter vary greatly
with time, region, meteorology, and source category. SOX,
NOX, and VOC are referred to as PM10
precursors. As discussed later in this proposed rule, precursor
emissions do not contribute significantly to elevated ambient
PM10 concentrations in Truckee Meadows.
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    Generally, SIPs were to provide for attainment of the NAAQS within
three years after EPA approval of the plan. However, many areas of the
country did not attain the NAAQS within the statutory period. In
response, Congress amended the Act in 1977 to establish a new approach,
based on area designations, for attaining the NAAQS. Under section
107(d) of the 1977 amended Act, states were to make recommendations for
all areas within their borders as attainment, nonattainment, or
unclassifiable for each of the NAAQS, including TSP, and the EPA was to
designate areas based on those recommendations, as modified if
appropriate. For the State of Nevada, the state recommended, and the
EPA approved, the use of hydrographic areas as the geographic basis for
designating air quality planning areas. 67 FR 12474 (March 19, 2002).
For the TSP NAAQS, the EPA designated a number of areas in Nevada as
``nonattainment,'' including Truckee Meadows \2\ (hydrographic area
(HA) #87). 43 FR 8962, at 9012 (March 3, 1978). The area designations
for air quality planning purposes within the State of Nevada are
codified at 40 CFR 81.329.
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    \2\ Truckee Meadows, also referred to as the ``Reno planning
area,'' lies in the far southern part of Washoe County. Washoe
County is located in the northwestern portion of Nevada and is
bordered by the State of California to the west and the State of
Oregon to the north. Within the State of Nevada, the counties of
Humboldt, Pershing, Storey, Churchill, Lyon, and the city of Carson
City bound Washoe County to the east and south. Located at an
average elevation of 4,500 feet above sea level, Truckee Meadows
encompasses a land area of approximately 200 square miles and is
surrounded by mountain ranges, which can lead to persistent
wintertime temperature inversions where a layer of cold air is
trapped in the valley. Warmer air above the inversion acts as a lid,
containing and concentrating air pollutants at ground level.
Approximately two-thirds of Washoe County's population lives in the
Truckee Meadows area. Anthropogenic activities, such as automobile
use and residential wood combustion, are also concentrated here.
Washoe County has experienced significant growth in population since
1990, with an increase in population from approximately 257,000 in
1990 to approximately 422,000 in 2011, an increase of 64 percent
over that 21-year period. The two major cities in Truckee Meadows
are Reno and Sparks.
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    As amended in 1977, the CAA required states to revise their SIPs by
January 1979 for all designated nonattainment areas. The various local
entities and the State of Nevada responded by developing and submitting
attainment plans for the TSP nonattainment areas, including Truckee
Meadows,\3\ and in 1981, the EPA approved these plans on condition that
the State submit, within a prescribed period of time, revisions to
correct certain deficiencies. 46 FR 21758 (April 14, 1981). In 1982, we
found that the state had submitted the required revisions correcting
the identified deficiencies, and we revoked the conditions placed on
our approval of the TSP plans. 47 FR 15790 (April 13, 1982).
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    \3\ The reference here is to the TSP portions of the Truckee
Meadows Air Quality Implementation Plan (December 6, 1978).
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    In 1987, the EPA revised the NAAQS for particulate matter,
eliminating TSP as the indicator for the NAAQS and replacing it with
the ``PM10'' indicator. 52 FR 24634 (July 1, 1987).
PM10 refers to particles with an aerodynamic diameter less
than or equal to a nominal 10 microns. At that time, EPA established
two PM10 standards: A 24-hour standard of 150 micrograms per
cubic meter ([micro]g/m\3\) and an annual standard of 50 [micro]g/
m\3\.\4\ We indicated in the preamble to our regulations implementing
the then-new PM10 NAAQS that we would consider

deletion of TSP area designations once the EPA had reviewed and
approved revised SIPs that include control strategies for the
PM10 NAAQS and once the EPA had promulgated PM10
increments for the prevention of significant deterioration (PSD)
program. 52 FR 24672, at 24682 (July 1, 1987).
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    \4\ In 2006, the EPA retained the 24-hour PM10
standard but revoked the annual PM10 standard. 71 FR
61144 (October 17, 2006). More recently, as part of the Agency's
periodic review of the NAAQS, EPA reaffirmed the 24-hour
PM10 NAAQS. 78 FR 3086 (January 15, 2013). See 40 CFR
50.6 (``National primary and secondary ambient air quality standards
for PM10'').
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    Under our regulations for implementing the revised particulate
matter NAAQS (i.e., the PM10 NAAQS), the EPA did not
designate areas as nonattainment, attainment, or unclassifiable but
categorized areas into three groups, referred to as Group I, Group II,
or Group III. Group I areas were those that had a probability of not
attaining the PM10 NAAQS (based on existing TSP data) of at
least 90%. Group I areas were required to submit SIP revisions that
contain full PM10 control strategies including a
demonstration of attainment. 52 FR 24672, at 24681 (July 1, 1987). We
identified the Las Vegas (HA #212) and Reno (HA #87, i.e., Truckee
Meadows) planning areas as Group I areas. 52 FR 29383 (August 7, 1987)
and 55 FR 45799 (October 31, 1990).
    The CAA was significantly amended in 1990. Under the 1990 amended
Act, Congress replaced the PM10 regulatory approach
established by the EPA in 1987 with the area designation concept and
designated former ``Group I'' areas and certain other areas as
nonattainment areas for PM10 by operation of law. See CAA
section 107(d)(4)(B). As former ``Group I'' areas, the Reno planning
area (i.e., Truckee Meadows) was designated as a nonattainment area for
PM10 by operation of law. 56 FR 11101 (March 15, 1991).
Truckee Meadows was initially classified as a ``Moderate''
PM10 nonattainment area with an applicable attainment date
of December 31, 1994, but despite improvements in ambient particulate
conditions, Truckee Meadows was later reclassified by operation of law
to ``Serious'' upon the EPA's determination that the area had failed to
attain the standard by the ``Moderate'' area attainment date (i.e.,
based on ambient PM10 data for the 1992-1994 period). 66 FR
1268 (January 8, 2001). States with ``Serious'' PM10
nonattainment areas were required under the CAA, as amended in 1990, to
submit revisions to their SIPs to, among other things, demonstrate
attainment of the PM10 standard as expeditiously as
practicable, but no later than December 31, 2001. See CAA section
188(c). Despite further improvements, Truckee Meadows failed to attain
the December 31, 2001 attainment date based on ambient PM10
data for the 1999-2001 period. Such areas are required to submit an
attainment plan under CAA section 189(d) (referred to as a ``Five
Percent'' plan), but the SIP submittal requirement for a Five Percent
plan for Truckee Meadows was suspended by a ``clean data''
determination by the EPA based on ambient PM10 data for the
2007-2009 period. 76 FR 21807 (April 19, 2011).
    The 1990 Act Amendments also provided for the continued transition
from TSP to PM10. Specifically, section 107(d)(4)(B) states
in relevant part: ``Any designation for particulate matter (measured in
terms of total suspended particulates) that the Administrator
promulgated pursuant to this subsection (as in effect immediately
before November 15, 1990) shall remain in effect for purposes of
implementing the maximum allowable increases in concentrations of
particulate matter (measured in terms of total suspended particulates)
pursuant to section 163(b) of this title, until the Administrator
determines that such designation is no longer necessary for that
purpose.''
    Section 166(f) of the 1990 amended Act authorizes the EPA to
replace the TSP increments with PM10 increments, and in
1993, the EPA promulgated the PM10 increments and revised
the PSD regulations accordingly. 58 FR 31622 (June 3, 1993). In our
June 1993 final rule, we indicated that the replacement of the TSP
increments with PM10 increments negates the need for the TSP
attainment or unclassifiable area designations to be retained. We also
indicated that we would delete such TSP designations in 40 CFR part 81
upon the occurrence of, among other circumstances, the EPA's approval
of a State's or local agency's revised PSD program containing the
PM10 increments. 58 FR 31622, at 31635 (June 3, 1993).
    In November 2002, we deleted the TSP attainment or unclassifiable
area designations throughout the State of Nevada, except for those in
Clark County. 67 FR 68769 (November 13, 2002). In April 2013, we
deleted the TSP attainment or unclassifiable area designations within
Clark County and also deleted the TSP nonattainment area designations
for all of the Nevada TSP nonattainment areas, except for Las Vegas
Valley and Truckee Meadows.\5\ 78 FR 22425 (April 16, 2013). In July
2014, we deleted the TSP nonattainment area designation for Las Vegas
Valley, and in today's proposed rule, we are proposing to delete the
TSP nonattainment area designation for Truckee Meadows.
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    \5\ In June 1992, the State of Nevada requested that we
reclassify the eight existing TSP nonattainment areas in Nevada to
``unclassifiable'' status. See letter from L.H. Dodgion,
Administrator, NDEP, to Daniel W. McGovern, Regional Administrator,
EPA Region IX, dated June 15, 1992. We believe that deletion of the
TSP nonattainment designations is administratively more efficient
than redesignation of the area to unclassifiable. As noted above, we
have already deleted seven of the TSP nonattainment area
designations and are proposing to delete the one for Truckee Meadows
herein.
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II. The State's Submittals

    The Nevada Division of Environmental Protection (NDEP) is the state
agency with overall responsibility for the Nevada SIP and is the
designated agency for submitting SIPs and SIP revisions to the EPA for
approval. The Washoe County District Board of Health (``Health
District''), which administers air quality programs through the Health
District's Air Quality Management Division (``WCAQMD''), is empowered
under state law to develop air quality plans within Washoe County. The
Health District is also empowered under state law to regulate
stationary sources within Washoe County with the exception of certain
types of power plants, which lie exclusively within the jurisdiction of
the NDEP. After it adopts an air quality plan for Washoe County, the
Health District submits the plan to NDEP for adoption as part of the
Nevada SIP and then for submittal to the EPA for approval.
    As noted above, the Health District adopted, and the EPA approved,
an air quality plan in the 1970s to provide for attainment of the TSP
standard in Truckee Meadows. Another plan was required for Truckee
Meadows in response to the area's classification as a ``Moderate''
nonattainment area for PM10 under the Clean Air Act
Amendments of 1990. On April 15, 1991, the NDEP submitted certain
District regulations intended to reduce PM10 emissions in
Truckee Meadows to the EPA. On October 30, 1991, the state submitted
``Nevada State Implementation Plan for the Truckee Meadows Air Basin,
Particulate Matter (PM10)'' (``1991 PM10
Attainment Plan''), a PM10 plan for the Truckee Meadows area
to address the requirements in CAA section 189(a) for ``Moderate''
PM10 nonattainment areas. The 1991 PM10
Attainment Plan included a demonstration that the attainment deadline
for the Truckee Meadows moderate nonattainment area (December 31, 1994)
was not practicably achievable, and carried forward the District
regulations that had been submitted previously on April 15, 1991. On
March 7, 1994, the NDEP submitted amended District regulations that
were intended to address deficiencies that the EPA had identified
through its review of the regulations submitted in April 1991 and the
1991 PM10 Attainment Plan submitted in October 1991.

    As noted above, in 2001, the EPA reclassified the Truckee Meadows
area to ``Serious'' nonattainment for the PM10 NAAQS,
triggering the requirement for a new attainment plan, and on August 5,
2002, the NDEP submitted a PM10 plan for Truckee Meadows to
address the requirements in CAA section 189(b) for ``Serious''
PM10 nonattainment areas. See ``Revisions to the Nevada
Particulate Matter (PM10) State Implementation Plan for the
Truckee Meadows Air Basin,'' August 2002 (``2002 PM10
Attainment Plan''). Generally, each subsequent air quality plan builds
upon the foundation established by earlier plans, and, in this
instance, the 2002 PM10 Attainment Plan built upon and
superseded the earlier ``Moderate'' area plans. The 2002
PM10 Attainment Plan included an analysis of BACM for the
Truckee Meadows area and regulations to control PM10
emissions from all significant PM10 sources identified in
that BACM analysis--i.e., street sanding and sweeping operations,
fugitive dust-generating activities, and residential wood combustion.
The District Regulations submitted as part of the 2002 PM10
Attainment Plan superseded those that had been submitted in April 1991
and those submitted in March 1994. The EPA has approved the various
District regulations submitted in connection with the 2002
PM10 Attainment Plan, but has not otherwise taken action on
the ``Moderate'' or ``Serious'' area attainment plans.
    In 2009, based on ambient PM10 monitoring data showing
that the area had attained the PM10 NAAQS, the WCAQMD
developed a maintenance plan, and the NDEP submitted the plan to the
EPA for approval along with a request to redesignate Truckee Meadows
from nonattainment to attainment for the PM10 standard. See
``Redesignation Request and Maintenance Plan for the Truckee Meadows
24-Hour PM10 Non-Attainment Area,'' May 28, 2009 (``2009
PM10 Maintenance Plan''). The 2009 PM10
Maintenance Plan included motor vehicle emissions budgets (MVEBs) for
the Truckee Meadows area, and the EPA found that MVEBs for
PM10 contained in the 2009 PM10 Maintenance Plan
were adequate for transportation conformity purposes. 75 FR 27776 (May
18, 2010). The WCAQMD subsequently revised the 2009 PM10
Maintenance Plan in response to the EPA's review of the plan, and on
November 7, 2014, the NDEP submitted a new maintenance plan,
``Redesignation Request and Maintenance Plan for the Truckee Meadows
24-Hour PM10 Non-Attainment Area,'' August 28, 2014 (``2014
PM10 Maintenance Plan'' or ``Plan'') for EPA approval. The
2014 PM10 Maintenance Plan supersedes the 2009
PM10 Maintenance Plan, and includes a revised maintenance
plan under CAA section 175A, an updated emissions inventory under CAA
section 172(c)(3), and revised MVEBs for the Truckee Meadows area.
    In this proposed rule, we are proposing to approve the 2014
PM10 Maintenance Plan, including the emissions inventory,
maintenance demonstration, and related MVEBs. Additionally, we are
proposing to approve the BACM demonstration from the 2002
PM10 Attainment Plan but consider the rest of the 2002
PM10 Attainment Plan to be superseded by the 2014
PM10 Maintenance Plan.

III. Procedural Requirements for Adoption and Submittal of SIP
Revisions

    Section 110(l) of the CAA requires states to provide reasonable
notice and public hearing prior to adoption of SIP revisions. In this
action, we are proposing action on the NDEP's submittal of the 2014
PM10 Maintenance Plan as a revision to the Nevada SIP. The
2014 PM10 Maintenance Plan contains evidence that reasonable
notice of a public hearing was provided to the public (via newspaper
advertisement) and that a public hearing was conducted prior to
adoption by the Health District. More specifically, the Plan provides
evidence that the Health District published a notice of the
availability of the draft 2014 PM10 Maintenance Plan and of
a public hearing to be held on August 28, 2014 in the Reno Gazette-
Journal on July 25, August 11, and August 22, 2014. Following adoption
by the Health District on August 28, 2014, the Health District
forwarded the 2014 PM10 Maintenance Plan to the NDEP. The
NDEP then submitted the SIP revision to the EPA for approval on
November 7, 2014.
    In this action, we also proposed to approve an element (i.e., the
BACM demonstration) of the 2002 PM10 Attainment Plan, and it
too contains evidence that reasonable notice of a public hearing was
provided to the public (via newspaper advertisement) and that a public
hearing was conducted. Following adoption by the Health District on
July 26, 2002, the Health District forwarded the 2002 PM10
Attainment Plan to the NDEP, which then submitted the SIP revision to
the EPA for approval. Thus, we find that both the 2014 PM10
Plan and the 2002 PM10 Plan satisfy the procedural
requirements of section 110(l) of the Act for revising SIPs.

IV. Clean Air Act Requirements for Redesignation to Attainment

    The CAA establishes the requirements for redesignating a
nonattainment area to attainment. Specifically, section 107(d)(3)(E)
allows for redesignation provided that the following criteria are met:
(1) the EPA determines that the area has attained the applicable NAAQS;
(2) the EPA has fully approved the applicable implementation plan for
the area under section 110(k); (3) the EPA determines that the
improvement in air quality is due to permanent and enforceable
reductions in emissions resulting from implementation of the applicable
SIP, applicable Federal air pollution control regulations, and other
permanent and enforceable reductions; (4) the EPA has fully approved a
maintenance plan for the area as meeting the requirements of CAA
section 175A; and (5) the State containing such area has met all
requirements applicable to the area under section 110 and part D of
title I of the CAA.
    The EPA provided guidance on redesignations in the form of a
General Preamble for the Implementation of Title I of the CAA
Amendments of 1990 published in the Federal Register on April 16, 1992
(57 FR 13498), as supplemented on April 28, 1992 (57 FR 18070)
(``General Preamble''). Other relevant EPA guidance documents include:
``Procedures for Processing Requests to Redesignate Areas to
Attainment,'' Memorandum from John Calcagni, Director, Air Quality
Management Division, EPA Office of Air Quality Planning and Standards,
September 4, 1992 (``Calcagni Memo''); ``Part D New Source Review (part
D NSR) Requirements for Areas Requesting Redesignation to Attainment,''
Memorandum from Mary D. Nichols, Assistant Administrator for Air and
Radiation, October 14, 1994 (``Nichols Memo''); and ``State
Implementation Plans for Serious PM10 Nonattainment Areas,
and Attainment Date Waivers for PM10 Nonattainment Areas
Generally; Addendum to the General Preamble for the Implementation of
Title I of the Clean Air Act Amendments of 1990,'' 59 FR 41998 (August
16, 1994) (``PM10 Addendum'').
    For the reasons set forth below in section V of this document, we
are proposing to approve the NDEP's request for redesignation of the
Truckee Meadows nonattainment area to attainment for the
PM10 NAAQS based on our conclusion that all of the criteria
under CAA section 107(d)(3)(E) have been satisfied.

V. Evaluation of the State's Redesignation Request for Truckee Meadows

A. The Area Has Attained the PM10 NAAQS

    Section 107(d)(3)(E)(i) of the CAA states that for an area to be
redesignated to attainment, the EPA must determine that the area has
attained the applicable NAAQS. In this case, the applicable NAAQS is
the PM10 NAAQS. As noted above, in 2011 (76 FR 21807, April
19, 2011), the EPA determined that Truckee Meadows had attained the
PM10 standard based on 2007-2009 ambient data; however, to
redesignate the area to attainment, it is necessary to update that
determination based on the most current information to ensure that the
area continues to attain the standard.
    We generally determine whether an area's air quality meets the
PM10 standard based upon the most recent period of complete,
quality-assured 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. Data from air monitors
operated by state/local agencies in compliance with EPA monitoring
requirements must be submitted to the EPA AQS database. Heads of
monitoring agencies annually certify that these data are accurate to
the best of their knowledge. Accordingly, the EPA relies primarily on
data in its AQS database when determining the attainment status of
areas. See 40 CFR 50.6; 40 CFR part 50, appendix J; 40 CFR part 53; 40
CFR part 58, appendices A, C, D and E. All data are reviewed to
determine the area's air quality status in accordance with 40 CFR part
50, appendix K.
    The PM10 standard is attained when the expected number
of days per calendar year with a 24-hour concentration in excess of the
standard (referred to herein as ``exceedance''),\6\ as determined in
accordance with 40 CFR part 50, appendix K, is equal to or less than
one.\7\ See 40 CFR 50.6 and 40 CFR part 50, appendix K. For purposes of
redesignation, the most recent three consecutive years of complete air
quality data are necessary to show attainment of the 24-hour standard
for PM10. See 40 CFR part 50, appendix K. A complete year of
air quality data, as referred to in 40 CFR part 50, appendix K,
includes all four calendar quarters with each quarter containing data
from at least 75 percent of the scheduled sampling days. Id.
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    \6\ An exceedance is defined as a daily value that is above the
level of the 24-hour standard (i.e., 150 [micro]g/m\3\) after
rounding to the nearest 10 [micro]g/m\3\ (i.e., values ending in 5
or greater are to be rounded up). Thus, a recorded value of 154
[micro]g/m\3\ would not be an exceedance since it would be rounded
to 150 [micro]g/m\3\ whereas a recorded value of 155 [micro]g/m\3\
would be an exceedance since it would be rounded to 160 [micro]g/
m\3\. See 40 CFR part 50, appendix K, section 1.0.
    \7\ The comparison with the allowable expected exceedance rate
of one per year is made in terms of a number rounded to the nearest
tenth (fractional values equal to or greater than 0.05 are to be
rounded up; e.g., an exceedance rate of 1.05 would be rounded to
1.1, which is the lowest rate for nonattainment). See 40 CFR part
50, appendix K, section 2.1(b).
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    The WCAQMD currently operates five SLAMS within the Truckee Meadows
PM10 nonattainment area, but operated six such stations over
most of the 2012-2014 period. The locations of the five current
PM10 monitors in Truckee Meadows are as follows. In the City
of Reno, the ``Reno3'' monitoring site is located in downtown Reno just
south of Interstate 80; the ``Plumb-Kit'' site is in a graveled area
close to residences, about half a mile west of Interstate 580 and the
Reno-Tahoe International Airport; and the ``Toll'' site is located
along State Route 341, at the corner of the Washoe County School
District parking lot. In South Reno, the ``South Reno'' monitoring site
is located in an unpaved, vegetated area at the northeast corner of the
Nevada Energy campus. In the City of Sparks, the ``Sparks'' monitoring
site is located along a paved parking lot about half a mile north of
Interstate 80. The sixth monitoring site, the ``Galletti'' site, which
was closed in mid-November 2014, was located in downtown Reno just
south of Interstate 80.\8\ The locations of the monitoring sites are
illustrated in figure 2-1 in the 2014 PM10 Maintenance Plan,
and are described in more detail in ``Washoe County Health District,
Air Quality Management Division, 2015 Ambient Air Monitoring Network
Plan,'' submitted to EPA Region IX July 1, 2015. All of the
PM10 monitor sites operate on a daily schedule using
continuous monitors. Id. at 3. Despite the closure of the ``Galletti''
site, the WCAQMD PM10 network continues to meet minimum
monitoring requirements per appendix D to 40 CFR part 58.
---------------------------------------------------------------------------

    \8\ The WCAQMD closed the ``Galletti'' site in mid-November 2014
as a result of emergency construction at the location of the site.
The EPA has approved WCAQMD's request to close the Galletti site,
due to lease issues beyond their control as well as siting issues.
See letter from Meredith Kurpius, Manager, Air Quality Analysis
Office, EPA Region IX, to Daniel Inouye, Chief, Monitoring and
Planning, WCAQMD, April 22, 2015.
---------------------------------------------------------------------------

    WCAQMD reports the PM10 data from its monitors to AQS on
a quarterly basis as required under the EPA's monitoring regulations.
The EPA has approved the WCAQMD's monitoring network as satisfying the
network design and data adequacy requirements of 40 CFR part 58.\9\ The
EPA's most recent audit of WCAQMD's ambient air monitoring program
found, generally, that the program is robust and meets EPA
requirements.\10\ As with any audit, the EPA uncovered some program
areas that can be improved, but none are cause for data invalidation.
The WCAQMD annually certifies that the data it submits to AQS are
complete and quality-assured. See, e.g., letter dated April 30, 2015,
from Daniel Inouye, Branch Chief, Monitoring and Planning, WCAQMD, to
Jared Blumenfeld, Regional Administrator, EPA Region IX, ``Re: CY2014
Ambient Air Monitoring Data Certification.''
---------------------------------------------------------------------------

    \9\ See letter from Meredith Kurpius, Manager, Air Quality
Analysis Office, EPA Region IX, to Daniel Inouye, Director, WCAQMD,
October 29, 2014.
    \10\ See letter from Deborah Jordan, Director, Air Division, EPA
Region IX, to Charlene Albee, Director, WCAQMD, August 19, 2014 and
enclosed report titled ``Technical System Audit Report, Washoe
County Health District Air Quality Management Division, Ambient Air
Monitoring Program (September 4-6, 2013),'' dated August 2014.
---------------------------------------------------------------------------

    Table 1 provides the highest measured PM10
concentrations and the number of expected exceedances in Truckee
Meadows during the 2010-2014 period. Table 1 shows generally that
Truckee Meadows has continued to attain the PM10 standard
since the EPA made the determination of attainment in 2011 based on
2007-2009 data; however, a determination of attainment requires a more
detailed examination of the data for the most recent three-year period.
For the purposes of this action, we are focusing our evaluation on the
most recent three-year period for which data is available, i.e., 2012-
2014.

                                       Table 1--Monitored PM10 Concentrations and Expected Exceedances (2010-2014)
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                     Maximum 24-hour  ([micro]g/m\3\)           Expected exceedances (calendar year)       Expected exceedances (3-year
 Monitoring site name and AQS ------------------------------------------------------------------------------------------            averages)
             No.                                                                                --------------------------------
                                 2010     2011     2012     2013     2014     2010     2011     2012     2013     2014   2010-2012  2011-2013  2012-2014
--------------------------------------------------------------------------------------------------------------------------------------------------------
Reno3 (32-031-0016)..........      142       64       46      121      134        0        0        0        0        0         0          0          0
South Reno (32-031-0020).....       52       63       61      133      106        0        0        0        0        0         0          0          0
Galletti (32-031-0022).......       87      113       77      131    * 159        0        0        0        0     ** 1         0          0     ** 0.3
Toll (32-031-0025)...........       34      121       85      144      121        0        0        0        0        0         0          0          0
Plumb-Kit (32-031-0030)......       77       71       92      127      136        0        0        0        0        0         0          0          0
Sparks (32-031-1005).........       55       76      100      100      135        0        0        0        0        0         0          0          0
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source: EPA AQS database. August 7, 2015. Values shown in bold type represent exceedances of the PM10 standard.
* The exceedance occurred on September 18, 2014 and has been flagged by WCAQMD as an exceptional event. While the EPA has not concurred on the
  exceedance as an exceptional event nor excluded it from our proposed determination of attainment, the Agency recognizes that the exceedance was
  monitored during a period when a significant regional wildfire (the King Fire) burned tens of thousands of acres in the Sierra Nevada Mountains east
  of Sacramento, generally upwind of Truckee Meadows.
** The Galletti site closed in mid-November 2014 as a result of emergency construction at the location of the site. The EPA approved the closure of the
  site in April 2015. The 2014 data is incomplete, however; the EPA has determined that the data remains valid for NAAQS comparison purposes.

    For the 2012-2014 period, with one exception, the AQS database
contains complete, quality-assured and certified data from the six
PM10 monitoring sites operating during this period within
Truckee Meadows. The one exception relates to the ``Galletti'' site,
which, as noted above, was closed in mid-November 2014 due to emergency
construction at the site, and for which the fourth quarter's 2014 data
is incomplete. However, we find that the data from the ``Galletti''
site, while incomplete in one quarter of one year of the 2012-2014
period, remain valid for PM10 NAAQS comparison purposes
based on the statistical analysis prepared by the WCAQMD in its March
5, 2015 request for approval for closure of the ``Galletti'' site. The
WCAQMD's statistical analysis demonstrates, using the annual maximum
24-hour concentrations from 2009-2013, that there is just over a 10
percent probability of exceeding 80 percent of the PM10
NAAQS at the ``Galletti'' site during the next three years (2014-2016),
and the EPA cited this statistical analysis in its approval of the
closure of the Galletti site.\11\
---------------------------------------------------------------------------

    \11\ See letter from Meredith Kurpius, Manager, Air Quality
Analysis Office, EPA Region IX, to Daniel Inouye, Chief, Monitoring
and Planning, WCAQMD, April 22, 2015, page 2.
---------------------------------------------------------------------------

    Based on our review of the quality-assured, certified, and complete
(or otherwise validated) PM10 data for the six
PM10 monitoring sites, we find that the expected number of
days per calendar year with an exceedance is less than 1.0 at all six
sites over the most recent three-year period (2012-2014). See table 1
above. Preliminary data for calendar year 2015 indicate that there has
been only one measured exceedance of the PM10 standard (on
February 6, 2015 at the Toll site), but this exceedance does not result
in a violation of the standard at that site given that it has no other
recorded exceedances since 2002. See table 1, above, and our proposed
determination of attainment at 76 FR 10817 (February 28, 2011). Thus,
we find that preliminary 2015 data is consistent with continued
attainment. As such, we find that Truckee Meadows is attaining the
PM10 standard and thereby meets the criterion for
redesignation in CAA section 107(d)(3)(E)(i).

B. The Area Has Met All Applicable Requirements for Purposes of
Redesignation Under Section 110 and Part D of the CAA and Has a Fully
Approved Applicable Implementation Plan Under Section 110(k) of the CAA

    Section 107(d)(3)(E)(ii) and (v) require the EPA to determine that
the area has a fully-approved applicable SIP under section 110(k) that
meets all applicable requirements under section 110 and part D for the
purposes of redesignation. The EPA may rely on prior SIP approvals in
approving a redesignation request, Calcagni Memo at 3; Wall v. EPA,
F.3d 416 (6th Cir. 2001), Southwestern Pennsylvania Growth Alliance v.
Browner, 144 F.3d 984, 989-990 (6th Cir. 1998), as well as any
additional measure it may approve in conjunction with a redesignation
action. See 68 FR 25426 (May 12, 2003) and citations therein. In this
instance, we are proposing to approve several part D elements as part
of this action [i.e., emissions inventory under CAA section 172(c)(3)
and the BACM demonstration under CAA section 189(b)(1)(B)]. With full
approval of those two elements, the Truckee Meadows portion of the
Nevada SIP will be fully approved under section 110(k) of the Act with
respect to all SIP elements that are applicable for the purposes of
redesignation of the area to attainment.
1. Basic SIP Requirements Under CAA Section 110
    The general SIP elements and requirements set forth 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; provisions for the implementation of part C
requirements for Prevention of Significant Deterioration (PSD);
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
applicable requirements for purposes of redesignation in accordance
with CAA section 107(d)(3)(E)(ii). 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 purposes of redesignation, and the state
will remain subject to these requirements after the nonattainment area
is redesignated to attainment.
    Thus, 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 attainment status, these are not applicable requirements
for purposes of redesignation under

CAA section 107(d)(3)(E). This policy is consistent with EPA's existing
policy on applicability of the conformity SIP requirement (i.e., for
redesignations). See discussion in 75 FR 36023, 36026 (June 24, 2010)
(proposed rule to redesignate Coso Junction, California, to attainment
for the PM10 NAAQS) and related citations.
    On numerous occasions over the past 40 years, NDEP has submitted,
and we have approved, provisions addressing the basic CAA section 110
provisions for Truckee Meadows. See, e.g., 37 FR 15080 (July 27, 1972);
77 FR 60915 (October 5, 2012); and 77 FR 64737 (October 23, 2012). The
Truckee Meadows portion of the Nevada SIP contains enforceable emission
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 the Health District is unable to meet its CAA
obligations.\12\ Based on our review of the Nevada SIP, we have
concluded that it meets the general SIP requirements under section
110(a)(2) of the CAA to the extent they are applicable for purposes of
redesignation of Truckee Meadows to attainment for the PM10
standard.
---------------------------------------------------------------------------

    \12\ The applicable Nevada SIP can be found at http://yosemite.epa.gov/r9/r9sips.nsf/allsips?readform&state=Nevada.
---------------------------------------------------------------------------

2. SIP Requirements Under Part D
    Subparts 1 and 4 of part D, title I of the CAA contain air quality
planning requirements for PM10 nonattainment areas. Subpart
1 contains general requirements for all nonattainment areas of any
pollutant, including PM10, governed by a NAAQS. The subpart
1 requirements include, in relevant part, provisions for implementation
of reasonably available control measures (RACM), a demonstrations of
reasonable further progress (RFP), emissions inventories, a program for
preconstruction review and permitting of new or modified major
stationary sources, contingency measures, conformity, and, for areas
that fail to attain the standard by the applicable attainment date, a
plan meeting the requirements of section 179(d).
    Subpart 4 contains specific SIP requirements for PM10
nonattainment areas. The requirements set forth in CAA section 189(a),
(c), and (e) apply specifically to ``Moderate'' PM10
nonattainment areas and include, in relevant part: (1) Provisions for
implementation of reasonably available control measures (RACM); (2)
quantitative milestones demonstrating RFP toward attainment by the
applicable attainment date; and (3) 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 EPA has determined that
such sources do not contribute significantly to PM10 levels
that exceed the NAAQS in the area. Under CAA section 189(b),
``Serious'' PM10 nonattainment areas, such as Truckee
Meadows, must meet the subpart 1 and ``Moderate'' area requirements
discussed above and, in addition, must develop and submit provisions to
assure the implementation of BACM for the control of PM10.
In addition, under CAA section 189(d), ``Serious'' PM10
nonattainment areas that fail to attain the standard by the applicable
attainment date, such as Truckee Meadows, must develop and submit plan
revisions which provide for attainment of the PM10 standard,
and from the date of such submission until attainment, for an annual
reduction in PM10 within the area of not less than 5 percent
of the amount of such emissions.
    However, we have determined that, in accordance with our Clean Data
Policy, the obligation to submit the following CAA requirements for
Truckee Meadows is not applicable for so long as the area continues to
attain the PM10 standard: The part D, subpart 4 obligations
to provide the RACM provisions of section 189(a)(1)(C), the RFP
provisions of section 189(c), the requirement for a section 189(d)
plan, the attainment demonstration, RACM, RFP and contingency measure
provisions of part D, subpart 1 contained in section 172 of the Act,
and requirements for additional plan previsions in section 179(d) of
the Act. 76 FR 21807 (April 19, 2011). As discussed above in section
V.A, Truckee Meadows has continued to attain the PM10
standard since the EPA's 2011 determination of attainment, which was
based on 2007-2009 data, and we are specifically proposing to determine
that the area currently meets the standard based on the most recent
three-year period (2012-2014). As such, the part D SIP submittal
requirements suspended by our 2011 ``clean data'' determination do not
apply for the purposes of evaluating Truckee Meadows' eligibility for
redesignation under CAA section 107(d)(3)(E)(v).\13\
---------------------------------------------------------------------------

    \13\ The suspended SIP planning requirements will cease to apply
to the Truckee Meadows area upon the effective date of redesignation
to attainment for the PM10 standard. For another
rulemaking action citing the ``clean data policy'' in the context of
evaluating a redesignation request of a PM10
nonattainment area under CAA section 107(d)(3)(E)(v), see 75 FR
36023, at 36027 (June 24, 2010) and 75 FR 54031 (September 3, 2010)
(proposed and final redesignation for Coso Junction, California).
See also, 40 CFR 51.918.
---------------------------------------------------------------------------

    Moreover, in the context of evaluating the area's eligibility for
redesignation, there is a separate and additional justification for
finding that requirements associated with attainment are not applicable
for purposes of redesignation. Prior to and independently of the Clean
Data Policy, and specifically in the context of redesignations, the EPA
interpreted attainment-linked requirements as not applicable for
purposes of redesignation. In the General Preamble, the EPA stated:

[t]he section 172(c)(9) requirements are directed at ensuring RFP
and attainment by the applicable date. These requirements no longer
apply when an area has attained the standard and is eligible for
redesignation. Furthermore, section 175A for maintenance plans * * *
provides specific requirements for contingency measures that
effectively supersede the requirements of section 172(c)(9) for
these areas. General Preamble, 57 FR 13498 at 13564 (April 16,
1992).

    See also Calcagni memorandum at 6 (``The requirements for
reasonable further progress and other measures needed for attainment
will not apply for redesignations because they only have meaning for
areas not attaining the standard.''). Thus, even if the requirements
associated with attainment had not previously been suspended, they
would not apply for purposes of evaluating whether an area that has
attained the standard qualifies for redesignation. The EPA has
enunciated this position since the General Preamble was published more
than twenty years ago, and it represents the Agency's interpretation of
what constitutes applicable requirements under section 107(d)(3)(E).
The Courts have recognized the scope of EPA's authority to interpret
``applicable requirements'' in the redesignation context. See Sierra
Club v. EPA, 375 F.3d 537 (7th Cir. 2004).
    The remaining applicable part D requirements for serious
PM10 nonattainment areas are: (1) An emissions inventory
under section 172(c)(3); (2) a permit program for the construction and
operation of new and modified major stationary sources of
PM10 under sections 172(c)(5) and

189(a)(1)(A), including a major source threshold of 70 tons per year as
required by section 189(b)(3); (3) provisions to assure implementation
of BACM for the control of PM10 under section 189(b)(1)(B);
(4) control requirements for major stationary sources of
PM10 precursors under section 189(e), except where the EPA
determines that such sources do not contribute significantly to
PM10 levels which exceed the standard in the area; and (5)
provisions to ensure that Federally supported or funded projects
conform to the air quality planning goals in the applicable SIP under
section 176(c). We discuss each of these requirements below.
a. Emissions Inventory
    Section 172(c)(3) of the Act requires the state to submit a
comprehensive, accurate, current inventory of actual emissions from all
sources of the relevant pollutant(s) in the nonattainment area,
including periodic updates as required by the EPA. We interpret the Act
such that the emission inventory requirement of section 172(c)(3) is
satisfied by the inventory requirement of the maintenance plan. See 57
FR 13498 at 13564 (April 16, 1992). In this action, the EPA is
proposing to approve the 2011 attainment inventory submitted in the
2014 PM10 Maintenance Plan as meeting the emission inventory
requirement under section 172(c)(3). See discussion below in section
V.D.1.
b. Permits for New and Modified Stationary Sources
    Sections 172(c)(5) and 189(a)(1)(A) of the CAA 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 or modified sources of
nonattainment pollutants comply with 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. For ``Moderate''
PM10 areas that are reclassified as ``Serious,'' such as
Truckee Meadows, the ``major source'' threshold is reduced from 100 to
70 tons per year of PM10. The process for reviewing permit
applications and issuing permits for new major sources or major
modifications to such sources in nonattainment areas is referred to as
``nonattainment New Source Review'' (``nonattainment NSR'' or simply
``NSR'').
    EPA-approved District regulations include rules for the review of
applications for new or modified stationary sources; however, the EPA
has not approved District regulations specifically meeting the NSR
requirements of sections 172(c)(5) and 189(a)(1)(A). However, the EPA
interprets section 107(d)(3)(E)(v) of the CAA such that final approval
of a NSR program is not a prerequisite to approving the state's
redesignation request. The 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. See generally Nichols Memo; see also
the more detailed explanations in the following redesignation
rulemakings: Detroit, Michigan (60 FR 12467-12468, March 7, 1996);
Cleveland-Akron-Lorrain, Ohio (61 FR 20458, 20469-20470, May 7, 1996);
Louisville, Kentucky (66 FR 53665, 53669, October 23, 2001); Grand
Rapids, Michigan (61 FR 31831, 31836-31837, June 21, 1996); and San
Joaquin Valley, California (73 FR 22307, 22313, April 25, 2008 and 73
FR 66759, 66766-67, November 12, 2008).
    The demonstration of maintenance of the standard in the 2014
PM10 Maintenance Plan relies on projections of future
emissions based on various growth factors. For the types of stationary
sources that are subject to District permitting requirements, future
emissions are projected based on employment growth projections and do
not take credit for future control technology requirements, such as
LAER, or for imposition of emissions offsets. See appendix B of the
2014 PM10 Maintenance Plan. Thus, we find that the
maintenance demonstration for the Truckee Meadows PM10
nonattainment area does not rely on an NSR program, and that the area
need not have a fully-approved nonattainment NSR program prior to
approval of the PM10 redesignation request.
    Once Truckee Meadows has been redesignated to attainment, the
requirements of the PSD program set forth at 40 CFR 52.21 will apply
with respect to PM10 (PSD already applies with respect to
the other pollutants in Truckee Meadows). See 40 CFR 52.1485. Thus, new
major sources of PM10 emissions and major modifications at
existing major sources, as defined in 40 CFR 52.21, will be required to
obtain a PSD permit before constructing. Currently, the WCAQMD has full
responsibility for implementing and enforcing the Federal PSD
regulations in 40 CFR 52.21 for sources within its jurisdiction
throughout Washoe County, including the Truckee Meadows area, under a
delegation agreement with the EPA. See ``Agreement for Delegation of
the Federal Prevention of Significant Deterioration (PSD) Program by
the United States Environmental Protection Agency, Region 9, to the
Washoe County District Health Department,'' dated March 13, 2008. The
NDEP has permitting jurisdiction over certain types of power plants
located anywhere within the State of Nevada, and if such a source were
to locate within Truckee Meadows, the PSD regulations at 40 CFR 52.21
would still apply but would be implemented and enforced by the NDEP,
which also administers the program through a delegation agreement with
the EPA.
c. Best Available Control Measures
    Section 189(b)(1)(B) of the Act requires for any ``Serious''
PM10 nonattainment area that the state submit provisions to
assure that BACM for the control of PM10 will be implemented
no later than four years after the date the area is classified (or
reclassified) as a ``Serious'' area. The PM10 Addendum (59
FR 41998, August 16, 1994) provides preliminary guidance on meeting
this BACM requirement. Even though the EPA previously determined that
Truckee Meadows is attaining the PM10 24-hour standard (76
FR 21807, April 19, 2011), the overall structure and purpose of title I
of the CAA Amendments of 1990, the standard suggested by the word
``best,'' and the differences in the statute between the requirements
for BACM as compared to those for RACM, lead the EPA to believe that,
unlike RACM, BACM are to be established generally independent of an
analysis of the attainment needs of the ``Serious'' area.
PM10 Addendum, at 42011. Thus, unlike RACM, BACM remains an
applicable requirement for the purposes of evaluating a redesignation
request even though the area is attaining the standard.
    The EPA defines BACM as, among other things, the maximum degree of
emissions reduction achievable for a source or source category, which
is determined on a case-by-case basis considering energy,
environmental, and economic impacts. See id. at 42010, 42013. BACM must
be implemented for all categories of sources in a ``Serious''
PM10 nonattainment area unless the state adequately
demonstrates that a particular source category does not contribute
significantly to nonattainment of the PM10 standard. See id.
at 42011, 42012. The PM10 Addendum discusses the following
steps for determining BACM:

     Inventory the sources of PM10 and
PM10 precursors \14\ and determine which source categories
are significant;
---------------------------------------------------------------------------

    \14\ As described further in section V.B.2.d of this document,
we find that PM10 precursors (NOX,
SOX, and VOC) do not significantly impact ambient
PM10 concentrations in Truckee Meadows.
---------------------------------------------------------------------------

     Evaluate alternative control techniques and their
technological feasibility; and evaluate the costs of control measures
or their economic feasibility.

See PM10 Addendum, at 42012-42014.

    BACM must be applied to each significant (i.e., non-de minimis)
source category. PM10 Addendum at 42011. In guidance, we
have established a presumption that a ``significant'' source category
is one that contributes 5 [micro]g/m\3\ or more of PM10 to a
location of a violation of the 24-hour standard. PM10
Addendum at 42011. However, whether the threshold should be lower than
this in any particular area depends upon the specific facts of that
area's nonattainment problem. Specifically, it depends on whether
requiring the application of BACM on source categories below a proposed
de minimis level would meaningfully expedite attainment. Once these
analyses are complete, the individual measures must then be converted
into a legally enforceable vehicle (e.g., a regulation or permit
process) to ensure BACM implementation. Also, the regulations or other
measures should meet the EPA's criteria regarding the enforceability of
SIPs and SIP revisions. CAA sections 172(c)(6) and 110(a)(2)(A). We use
these steps as guidelines in our evaluation of the BACM analysis in the
2002 PM10 Attainment Plan.
    The first step in the BACM analysis is to develop a detailed
emissions inventory of PM10 sources and source categories
that can be used in modeling to determine their impact on ambient air
quality. PM10 Addendum at 42012. The second step is to use
this inventory in air quality modeling to evaluate the impact on
PM10 concentrations over the standards of the various
sources and source categories to determine which are significant.
    The 2002 PM10 Attainment Plan contains a detailed
inventory of direct PM10 sources and source categories and,
based on the percent contributions of the various source categories to
the design day inventory, divides the design day concentration (of 215
[micro]g/m\3\) into source category components, as follows:

 Paved streets/reentrained dust/street sanding (142 [micro]g/
m\3\)
 Residential wood combustion (36 [micro]g/m\3\)
 Fugitive dust from construction activities (15 [micro]g/m\3\)
 Stationary/industrial processes (9 [micro]g/m\3\)
 Mobile on-road (4 [micro]g/m\3\)
 Mobile non-road (3 [micro]g/m\3\)
 Unpaved streets (2 [micro]g/m\3\)
 Other fuel combustion and miscellaneous Area (2 [micro]g/m\3\)
 Charbroilers (1 [micro]g/m\3\)

Based on the estimated contribution of the various source categories to
the design-day concentration, the following source categories are
considered significant, i.e., contribute 5 [micro]g/m\3\ or more to the
exceedance: (1) Paved streets/reentrained dust/street sanding, (2)
residential wood combustion, (3) fugitive dust from construction
activities, and (4) other stationary/industrial processes.\15\ We
believe that the 2002 PM10 Attainment Plan presents an
acceptable methodology to evaluate the impact of various
PM10 sources and source categories on PM10 levels
and to derive a comprehensive list of significant source categories.
---------------------------------------------------------------------------

    \15\ The stationary/industrial processes category includes a
disparate group of source subcategories (e.g., concrete production,
sand and gravel operations, asphalt production, etc.). For a
complete list of the subcategories included in the stationary/
industrial processes category, see table 1-2 in appendix B of the
2002 PM10 Attainment Plan.
---------------------------------------------------------------------------

    In preparing the list of candidate BACM to reduce emissions from
the various significant source categories, the WCAQMD reviewed our
guidance documents on BACM, other EPA documents on PM10
control, as well as PM10 plans and measures from other
``Serious'' PM10 areas in the United States. The WCAQMD also
evaluated controls proposed during public comment, sought input from
work groups (e.g., Road Sanding and Sweeping Working Group) and
requested review and comment by the EPA on individual measures to help
ensure that their adopted measures would constitute BACM. The processes
that the WCAQMD used to identify BACM are described in section V of the
2002 PM10 Attainment Plan. We believe that, based on the
description of the process in the 2002 PM10 Attainment Plan,
the WCAQMD appropriately screened the list of candidate BACM to
eliminate certain measures and appropriately identified and evaluated
potential BACM for the Truckee Meadows area consistent with our
guidance.
    Since 1988, the Health District has adopted and strengthened a
number of regulations to reduce PM10 emissions from the
significant source categories in Truckee Meadows. See 2002
PM10 Attainment Plan at 10-17. The District PM10
regulations were originally submitted to the EPA in 1991, but in the
wake of the reclassification of Truckee Meadows to ``Serious,'' the
Health District strengthened them to assure implementation of BACM. See
id. Each of the Health District regulations intended to implement BACM
was effective in Truckee Meadows on or before February 7, 2005 (i.e.,
within four years of the area's reclassification to serious
nonattainment on February 7, 2001), and the EPA has approved all of
these regulations as satisfying BACM control requirements.
    Specifically, we have approved the following Health District
regulations as satisfying BACM control requirements:
     District Regulation 040.005 (``Visible Air Contaminants'')
(72 FR 33397, June 18, 2007) (stationary/industrial processes);
     District Regulation 040.030, ``Dust Control'' (72 FR
25969, May 8, 2007) (fugitive dust from construction activities and
stationary/industrial processes);
     District Regulation 040.031, ``Street Sanding Operations''
(71 FR 14386, March 22, 2006) (paved streets/reentrained dust/street
sanding);
     District Regulation 040.032, ``Street Sweeping
Operations'' (71 FR 14386, March 22, 2006) (paved streets/reentrained
dust/street sanding);
     District Regulation 040.051, ``Wood Stove/Fireplace Insert
Emissions'' (72 FR 33397, June 18, 2007) (residential wood combustion);
and
     District Regulation 050.001, ``Emergency Episode Plan,''
(72 FR 33397, June 18, 2007) (residential wood combustion).\16\
---------------------------------------------------------------------------

    \16\ On August 22, 2013, the WCAQMD amended regulation 040.051,
and the amendment was submitted to the EPA on November 26, 2013. The
EPA is currently reviewing the submittal and preparing to act on it.
The 2014 PM10 Maintenance Plan does not rely on emissions
reductions from the amendments to the rule.
---------------------------------------------------------------------------

    Based on our prior approval of these regulations and our conclusion
that they cover all significant PM10 source categories in
the Truckee Meadows nonattainment area, we propose approval of the
WCAQMD's demonstration in Section V (``Control Strategies'') of the
2002 PM10 Attainment Plan as satisfying the requirement to
assure implementation of BACM under CAA section 189(b) (1) (B).\17\
---------------------------------------------------------------------------

    \17\ After BACM is applied to the significant source categories,
the significant categories still account for approximately 75
percent of the WCAQMD's remaining 2011 attainment year inventory of
daily emissions during the PM10 season (November,
December, and January). See 2014 PM10 Maintenance Plan at
Appendix C (``Truckee Meadows Projected PM10 Seasonal
Emissions (lbs/day)''). Based on a review of the remaining source
categories in the 2011 inventory, no new significant source
categories (i.e., above the de minimis threshold) were identified,
and, therefore, no additional sources are subject to BACM
requirements.

---------------------------------------------------------------------------

d. Control Requirements for PM10 Precursors
    Section 189(e) of the CAA requires that the control requirements
applicable under part D (of title I of the CAA) for major stationary
sources of PM10 also apply to major stationary sources of
PM10 precursors, except where the EPA determines that such
sources do not contribute significantly to PM10 levels which
exceed the standard in the area. In general, a major stationary source
in a PM10 ``Serious'' area includes any stationary source
that emits, or has the potential to emit, 70 tons per year of
PM10.
    The 1991 PM10 Attainment Plan concluded that major
stationary sources of PM10 precursors do not contribute
significantly to PM10 levels which exceed the standard in
Truckee Meadows based on technical study conducted by the Desert
Research Institute (DRI) intended to identify the sources of ambient
PM10 in Truckee Meadows. In its February 1988 report, PM
10 Source Apportionment the Truckee Meadows, Nevada, for
State Implementation Plan Development, Volume I: Modeling Methods and
Results, Final Report (``DRI Report''), submitted as appendix B to the
1991 PM10 Attainment Plan, the DRI performed over 300
chemical mass balance source apportionments on fine and coarse particle
fractions from three sites within the Truckee Meadows nonattainment
area. The source apportionments found that that the PM10
contribution from precursors (i.e., ammonium nitrates and ammonium
sulfates) was very small (i.e., approximately 5-6%) compared to the
contributions from wood/vegetative burning (i.e., residential wood
stoves and fireplaces), mobile source exhaust (e.g., diesel powered
vehicles), and geologic materials (e.g., road dust, sand/salt used for
deicing).
    We also note that more recent stationary source inventory data and
ambient PM2.5 speciation data for Truckee Meadows continue
to support the WCAQMD's 1991 conclusion regarding the (less-than-
significant) contribution to elevated ambient PM10
concentrations from major stationary sources of PM10
precursors. First, based on the 2011 Periodic Emissions Inventory,
there are no stationary sources in Truckee Meadows that emit more than
100 tons per year of NOX or SO2, and only two
such sources that emit more than 100 tons per year of VOC. Second,
ammonium nitrate and ammonium sulfate contributed only about 11% to the
total ambient PM10 based on the averages for the five
highest PM10 measurements collected during the winter of
2013 at the Reno3 monitoring site (which is the only site operated by
the WCAQMD with speciation capability).
    Based on the DRI Report and the more recent inventory and
monitoring data, we propose to make the finding authorized under CAA
section 189(e) and to determine that major sources of PM10
precursor emissions do not contribute significantly to PM10
levels which exceed the standard in the Truckee Meadows area.
e. Transportation Conformity
    Under the Clean Air Act, as amended in 1990, section 176(c) of the
CAA required the states to revise their SIPs to establish criteria and
procedures to ensure that federally supported or funded projects in
nonattainment and formerly nonattainment areas subject to a maintenance
plan (referred to as ``maintenance'' areas) ``conform'' to the air
quality planning goals in the applicable SIP. SIP revisions intended to
meet the conformity requirement in section 176(c) are referred to as
``conformity SIPs.'' 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''). In 2005, Congress amended
section 176(c), and under the amended conformity provisions, states are
no longer required to submit conformity SIPs for ``general
conformity,'' and the conformity SIP requirements for ``transportation
conformity'' have been reduced to include only those relating to
consultation, enforcement and enforceability. CAA section 176(c) (4)
(E).
    On July 31, 1995, the NDEP submitted the general and transportation
conformity procedures and criteria for Truckee Meadows as a revision to
the Nevada SIP. Given the 2005 amendments to the CAA, the NDEP has
withdrawn the earlier conformity SIP submittal, and on March 21, 2013,
submitted the Washoe County Transportation Conformity Plan as a
replacement for the earlier submittal. We have not taken action on the
March 21, 2013 SIP revision submittal. However, the EPA believes it is
reasonable to interpret the conformity SIP requirements as not applying
for purposes of a redesignation request under section 107(d) (3) (E)
(v) because state conformity rules are still required after
redesignation and Federal conformity rules apply where state rules have
not been approved. See Wall v. EPA, 265 F. 3d 426 (6th Cir. 2001),
upholding this interpretation. See also 60 FR 62748 (December 7, 1995).
3. Conclusion With Respect to Section 110 and Part D Requirements
    Therefore, based on the evaluation presented above, and based on
our proposed approval of the 2011 emissions inventory submitted as part
of the 2014 PM10 Maintenance Plan (see section V.D.1 of this
document), our proposed approval of the BACM demonstration submitted as
part of the 2002 PM10 Attainment Plan, and in light of our
proposed determination that major stationary sources of PM10
precursors do not contribute significantly to PM10
exceedances in the area, we find that that the state has met all
requirements applicable to the Truckee Meadows PM10
nonattainment area under section 110 and part D (of title I) of the CAA
and has therefore met the redesignation criterion set forth in CAA
section 107(d) (3) (E) (v).

C. The Improvement in Air Quality Is Due to Permanent and Enforceable
Reductions in Emissions

    Section 107(d)(3)(E)(iii) of the CAA requires the EPA, in order to
approve a redesignation to attainment, to determine that the
improvement in air quality is due to permanent and enforceable
reductions in emissions resulting from implementation of the applicable
SIP and applicable Federal air pollution control regulations and other
permanent and enforceable regulations. Improvement should not be a
result of temporary reductions (e.g., economic downturns or shutdowns)
or unusually favorable meteorology. Calcagni Memo at 4.
    PM10 levels in Truckee Meadows are driven primarily by
direct PM10 emissions from re-entrained dust from paved
roads, residential wood combustion, fugitive dust from construction
activities, and emissions from industrial sources. See 2002
PM10 Attainment Plan at 7; and appendix C to the 2014
PM10 Maintenance Plan. The peak PM10 season in
Truckee Meadows occurs during the winter months (i.e., November,
December, and January), due in large part to increased residential wood
combustion and application of sanding material to paved roads for
wintertime traction control. In addition,

because Truckee Meadows sits in a valley surrounded by mountain ranges,
cold winter nights create temperature inversions that trap pollutants
in a layer of cold air beneath a layer of warmer air above. 2014
PM10 Maintenance Plan at 13.
    The 2014 PM10 Maintenance Plan describes long-term air
quality improvements implemented in the Truckee Meadows area during the
1999 to 2011 time frame. The improvements in air quality occurred
despite substantial growth in population, economic activity, and
vehicle miles traveled (VMT) between 1990 and 2011, suggesting that the
air quality improvements were not due to temporary reductions in
emission rates or unusual meteorology but, instead, resulted from
implementation of federally-enforceable PM10 control
measures. The Plan describes the significant source categories of
PM10 emissions in the Truckee Meadows area and the SIP-
approved regulations that have significantly reduced PM10
emissions from these and other emission sources. According to the 2014
PM10 Maintenance Plan, SIP-approved regulations collectively
reduced daily PM10 emissions from residential wood
combustion and street sanding and sweeping, and construction activities
during the 2011 PM10 season by approximately 68 percent. See
table 4-1 of the 2014 PM10 Maintenance Plan.
    First, the 2014 PM10 Maintenance Plan cites the Health
District's residential wood combustion program (RWC) as a significant
source of emissions reductions in Truckee Meadows. The program relies
on two regulations as well as a public outreach program. District
Regulation 040.051, ``Wood Stove/Fireplace Insert Emissions,'' limits
PM10 emissions throughout Washoe County by, among other
things: (1) Establishing wood stove and fireplace insert control areas;
(2) requiring use of seasoned wood; (3) requiring the removal or
upgrade of existing solid fuel combustion devices upon the sale of real
estate; and (4) establishing a mandatory burning curtailment during
Stage 1 episodes.\18\ District Regulation 050.001, ``Emergency Episode
Plan,'' requires that the WCAQMD take certain actions when 24-hour
PM10 concentrations reach or are predicted to reach ``Stage
1'' levels (154 [micro]g/m\3\), such as: (1) Implementing procedures to
notify the public of potential health problems; (2) prohibiting all
open and prescribed burning; (3) prohibiting the use of permitted
incinerators, crematoriums, and pathological incinerators; (4)
prohibiting the use of solid fuel burning devices; and (5) activating
control plans for the largest PM10 sources in Washoe County.
2014 PM10 Maintenance Plan at 11.
---------------------------------------------------------------------------

    \18\ Regulation 040.051 defines ``Stage 1 alert'' by reference
to the Health District's Emergency Episode Plan (i.e., District
Regulation 050.001), which establishes a ``Stage 1 (alert)'' episode
criteria level of 154 [micro]g/m\3\. See District Regulation 040.051
at Section E.5 and Regulation 050.001 at Table 1.
---------------------------------------------------------------------------

    In addition, the WCAQMD implements a ``Keep it Clean, Know the
Code'' public outreach program (formerly known as the ``Green, Yellow,
Red'' program), which runs from November through February and which
consists in part of a daily burn code that provides the community a
recommendation on whether RWC will impact air quality in Washoe County.
The program also commits the WCAQMD to conduct an RWC survey at least
once every three years to track the effectiveness of the public
outreach program. The EPA has approved District Regulations 040.051 and
050.001, and the commitment to conduct the RWC survey as revisions of
the Nevada SIP, making them permanent and enforceable for the purposes
of CAA section 107(d)(3)(E)(iii). See 72 FR 33397 (June 18, 2007) and
73 FR 38124, at 38127 (July 3, 2008). According to the 2014
PM10 Maintenance Plan, District Regulations 040.051 and
050.001 (as implemented in part through the public outreach program)
reduced PM10 emissions in the Truckee Meadows area on a
``typical PM10 Season Day'' during 2011 by approximately 800
lbs/day and approximately 4,300 lbs/day, respectively. 2014
PM10 Maintenance Plan at 10, 12 (Table 4-1).
    Second, the 2014 PM10 Maintenance Plan cites the Health
District's street sanding and sweeping program as a source of
significant emissions reductions in Truckee Meadows. PM10
emissions from street sanding and sweeping are generated directly from
application of traction control material (i.e., sand, salt, and
chlorides) and indirectly from increased silt loading on paved streets.
Motor vehicle traffic grinds and re-entrains the material into the
ambient air. 2014 PM10 Maintenance Plan at 11. The Health
District adopted Regulation 040.031, ``Street Sanding Operations,'' and
Regulation 040.032, ``Street Sweeping Operations,'' to limit
PM10 emissions from street standing and sweeping activities
throughout the urbanized portions of Washoe County south of Township
22N, which includes the cities of Reno and Sparks. See 2014
PM10 Maintenance Plan at 11; 2002 PM10 Attainment
Plan at 12-16.
    These regulations require, among other things, that municipalities:
(1) Use a harder and cleaner type of sand on paved roads following snow
storms; (2) reduce the sand application rate by 50 percent compared to
1999 rates; (3) remove the sand within four days after a storm event;
and (4) only purchase new sweepers that are PM10 certified.
The EPA approved District Regulations 040.031 and 040.032 as revisions
of the Nevada SIP in 2006, making them permanent and enforceable for
the purposes of CAA section 107(d)(3)(E)(iii). 71 FR 14386 (March 22,
2006). According to the 2014 PM10 Maintenance Plan, District
Regulations 040.031 and 040.032 reduced PM10 emissions in
the Truckee Meadows area on a ``typical PM10 Season Day''
during 2011 by approximately 1,600 lbs/day. 2014 PM10
Maintenance Plan at 11, 12 (Table 4-1).
    Third, the 2014 PM10 Maintenance Plan cites District
Regulation 040.030, ``Dust Control,'' as another source of significant
emissions reductions in Truckee Meadows. District Regulation 040.030
limits emissions of fugitive dust from a variety of dust generating
activities, including, but not limited to, public or private
construction; mining; processing of sand, gravel, or dirt; and
operation and use of unpaved parking facilities. See section A of
District Regulation 040.030. Specifically, District Regulation 040.030
establishes (1) stabilization requirements for unpaved parking lots/
staging areas, unpaved haul/access roads, and open, vacant, or
disturbed areas, and open storage piles; (2) work practice requirements
for bulk material hauling, and spillage, carry-out, erosion and/or
trackout; and (3) dust control permit requirements for dust generating
activities. The EPA approved District Regulation 040.030 as a revision
of the Nevada SIP in 2007 making it permanent and enforceable for the
purposes of CAA section 107(d)(3)(E)(iii). 72 FR 25969 (May 8, 2007).
According to the 2014 PM10 Maintenance Plan, District
Regulation 040.030 reduced PM10 emissions in the Truckee
Meadows area on a ``typical PM10 Season Day'' during 2011 by
approximately 400 lbs/day. 2014 PM10 Maintenance Plan at 11,
12 (Table 4-1).
    The 2014 PM10 Maintenance Plan also provides an analysis
of economic and meteorological conditions in Washoe County during the
1990 to 2011 period to demonstrate that the emission reductions in the
Truckee Meadows area did not result from temporary reductions (e.g.,
economic downturns or shutdowns) or unusually favorable meteorology.
According to the plan, demographic and economic indicators such as
population, full-time

employment, total industry earnings, and VMT demonstrated steady,
positive growth during this period. See 2014 PM10 Plan at
13, Table 4-2 (``Washoe County Demographic and Economic Indicators
(1990-2011)''). For example, during the 1990-2011 period in Washoe
County, growth in several key economic indicators (i.e., population
64%, full-time employment 41%, total industry earnings 158%, and VMT
\19\ 86%) coincided with improved air quality. Id. With respect to
meteorological conditions, the 2014 PM10 Maintenance Plan
presents data from the 1990-2011 period that indicate that wintertime
precipitation, wind speed, and barometric pressure levels fluctuated
above and below historic averages throughout that period. Id. at 14-16.
---------------------------------------------------------------------------

    \19\ The VMT data in this table are expressed in miles per day
and represent only the Truckee Meadows portion of Washoe County. See
2011 PM10 Maintenance Plan at 13, Table 4-2 (``Washoe
County Demographic and Economic Indicators (1990-2011)'').
---------------------------------------------------------------------------

    Thus, we find that the improvements in PM10 air quality
during the 1990-2011 period resulted from implementation of permanent
and enforceable control measures that significantly reduced
PM10 emissions in the Truckee Meadows area, rather than from
temporary emission reductions or unusually favorable meteorology.
During the 2011 PM10 season, implementation of these SIP-
approved measures reduced daily PM10 emission levels by
approximately 68 percent, indicating that these SIP control measures
countered the emissions increases that otherwise would have occurred
due to steady growth in the area during this period. As such, we find
that the criterion for redesignation in CAA section 107(d)(3)(E)(iii)
has been met.

D. The Area Has a Fully-Approved Maintenance Plan, Including a
Contingency Plan, Under CAA Section 175A

    Section 107(d)(3)(E)(iv) of the CAA requires the EPA, in order to
approve a redesignation to attainment, to fully approve a maintenance
plan for the area as meeting the requirements of section 175A of the
Act. Section 175A sets forth the elements of a maintenance plan for
areas seeking redesignation from nonattainment to attainment. We
interpret this section of the Act to require, in general, the following
core elements:
     An attainment emissions inventory to identify the level of
emissions in the area sufficient to attain the NAAQS;
     A demonstration of maintenance of the NAAQS for at least
10 years after redesignation;
     Provisions for continued operation of an air quality
monitoring network;
     Provisions to verify continued attainment; and
     Contingency provisions that the EPA deems necessary to
assure that the state will promptly correct any violation of the NAAQS
that occurs after redesignation of the area.

See Calcagni Memo at 7-12. We discuss below how each of these core
elements is addressed in the 2014 PM10 Maintenance Plan.
1. Attainment Inventory
    A maintenance plan for the PM10 standard must include an
inventory of emissions of PM10 in the area to identify a
level of emissions sufficient to attain the PM10 NAAQS.\20\
This inventory must be consistent with the 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 sources, area
sources, nonroad mobile sources and on-road mobile sources, and must be
based on actual emissions during the appropriate season or episode, if
applicable. See CAA section 172(c)(3). EPA's primary guidance for
developing PM10 emissions inventories is a document titled,
``PM10 Emissions Inventory Requirements,'' EPA-454/R-94-033
(September 1994).
---------------------------------------------------------------------------

    \20\ PM10 precursor emissions may also be required
depending upon the contribution of secondarily-formed particulate
matter to ambient PM10 concentrations. As discussed
above, a 1988 DRI study concluded that the PM10
contribution from precursors (i.e., ammonium nitrates and ammonium
sulfates) was very small (i.e., approximately 5-6%) compared to the
contributions of other direct PM10 sources in Truckee
Meadows. As such, we find that the absence of PM10
precursors from the attainment inventory in the 2014 PM10
Maintenance Plan to be acceptable.
---------------------------------------------------------------------------

    The 2014 PM10 Maintenance Plan provides an emissions
inventory of actual emissions from all direct PM10 sources
within Truckee Meadows on an average day during the winter season
during year 2011. See table 2 below. The WCAQMD developed this
inventory based on the methods and assumptions presented in detail in
the WCAQMD's 2011 Periodic Emissions Inventory (November 2012), with
the following adjustments:
     Paved road fugitive dust was re-calculated based on the
most recent VMT estimates provided by the Regional Transportation
Commission of Washoe County (RTC) and the most recent version of EPA
emission factors published in AP-42,\21\ section 13.2.1 (``Paved
Roads''), dated January 2011, whereas the corresponding estimates in
the 2011 Periodic Emissions Inventory relied on earlier VMT estimates
and an earlier version of AP-42 section 13.2.1 (dated November 2006);
---------------------------------------------------------------------------

    \21\ AP-42, Compilation of Air Pollutant Emission Factors, is a
document published by the EPA as the primary collection of EPA
approved emission factor information. The emission factors have been
developed and compiled from source test data, material balance
studies, and engineering estimates.
---------------------------------------------------------------------------

     Unpaved road fugitive dust was re-calculated based on the
most recent VMT estimates provided by the RTC and updated silt loading
factors; and
     On-road mobile source emissions (combustion, brake and
tire wear) were re-calculated based on the most recent VMT estimates
provided by the RTC and a different traffic demand model.
    In addition to showing the estimated actual emissions in 2011,
table 2 below also the baseline maintenance plan inventory used by the
2014 PM10 Maintenance Plan to demonstrate maintenance
through 2030. The only difference between the 2011 actuals and the
maintenance plan baseline is in the wildfire source category. An
unusually high number of wildfires occurred during the winter of 2011,
which greatly increased the contribution of wildfires to the overall
2011 PM10 inventory, and thus, for the purposes of
developing a baseline attainment inventory for maintenance plan
purposes, the WCAQMD replaced the actual PM10 emissions from
wildfires in 2011 with the average of wildfire emissions from the four
previous inventory years (1999, 2002, 2005, and 2008). 2014
PM10 Maintenance Plan at 25. We find that adjustment to be
reasonable. Even with the adjustment for wildfires, over 85 percent of
direct PM10 emissions is attributed to nonpoint sources.

                 Table 2--Truckee Meadows 2011 Winter-Season Emission Inventory for Direct PM10
                                                    [lbs/day]
----------------------------------------------------------------------------------------------------------------
                                                                                Estimated
                  Category                               Subcategory                  actual        Maintenance
                                                                                emissions     plan baseline
----------------------------------------------------------------------------------------------------------------
Point Sources..............................  All................................              25              25
Nonpoint Sources                             Fuel Combustion....................             111             111
                                             Residential Wood Combustion........           5,888           5,888
                                             Construction \a\...................             460             460
                                             Non-Construction Industrial                     929             929
                                              Processes.
                                             Paved Roads--Fugitive Dust.........           1,453           1,453
                                             Paved Road--Sanding and Salting....             339             339
                                             Unpaved Roads--Fugitive Dust.......           2,623           2,623
                                             Wildfires..........................          10,947              21
                                             All Other Nonpoint.................              61              61
                                            --------------------------------------------------------------------
                                             Subtotal--Nonpoint.................          22,812          11,885
Non-road Mobile............................  All................................             606             606
Onroad Mobile..............................  All................................           1,183           1,183
                                            --------------------------------------------------------------------
    Totals.................................  ...................................          24,626          13,700
----------------------------------------------------------------------------------------------------------------
\a\ Construction-related emissions represents a sum of several different types of construction. One such type,
  road construction (178 lbs/day), is included in the motor vehicle emissions budget (MVEB) discussed in section
  V.D.6 of this proposed rule (along with paved road fugitive dust, unpaved road fugitive dust, and on-road
  mobile sources).
Source: 2014 PM10 Maintenance Plan, appendix C.
Totals may not add up due to rounding.

    The EPA believes that the selection of 2011 as the attainment year
inventory is appropriate given that it represents emissions from an
attainment year and the year for which the most recent emissions
inventory information was available at the time of preparation of the
maintenance plan. Moreover, preparation of a seasonal (winter)
inventory in this instance is appropriate given that winter is
typically the season when the highest ambient PM10
concentrations are monitored in Truckee Meadows. We find that the
WCAQMD's 2011 emissions inventory for direct PM10 is based
upon reasonable assumptions and methodologies, as described in the 2014
PM10 Maintenance Plan and 2011 Periodic Emissions
Inventory,\22\ and that the inventory is comprehensive, current and
accurate. We therefore propose to approve the inventory of actual
emissions in 2011 as meeting the requirements of CAA section 172(c)(3)
and find the 2011 inventory, as adjusted to discount 2011 wildfire
emissions, acceptable for use in demonstrating maintenance of the
PM10 standard in the future.
---------------------------------------------------------------------------

    \22\ The WCAQMD's 2011 Periodic Emissions Inventory, dated
November 2012 and submitted to the EPA for purposes of meeting the
AERR requirements, provides significant detail regarding the
assumptions and methodologies used to develop the 2011
PM10 inventory used in the 2014 PM10
Maintenance Plan. The 2011 Periodic Emissions Inventory also
includes emissions inventories for VOCs, NOX,
SOX, and ammonia. AERR requires state, local and tribal
agencies to collect and submit emissions data for criteria
pollutants to EPA's Emissions Inventory System.
---------------------------------------------------------------------------

2. Maintenance Demonstration
    Section 175A of the CAA requires a demonstration of maintenance of
the NAAQS for at least 10 years after redesignation. A state may
generally 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. See Calcagni Memo at 9-11.
    The 2014 PM10 Maintenance Plan demonstrates that the
Truckee Meadows area will maintain the PM10 NAAQS through
2030 by comparing the adjusted 2011 attainment inventory (also referred
to as the maintenance plan baseline) against the projected emissions
for 2015, 2020, 2025, and 2030. See 2014 PM10 Maintenance
Plan at 26-28 (Tables 6-4 and 6-5) and Appendix C (``Truckee Meadows
Projected PM10 Seasonal Emissions (lbs/day)''). Using the
adjusted 2011 emissions inventory as a baseline and appropriate growth
factors described in appendix B of the 2014 PM10 Maintenance
Plan, the WCAQMD projected emissions inventories for 2015, 2020, 2025,
and 2030. These projections were based on Washoe County's forecasts of
population, employment, and VMT (see 2014 PM10 Maintenance
Plan at appendix B, table B-2), consistent with the forecasts used by
the local metropolitan planning organization (MPO); the EPA nonroad and
on-road emissions models (i.e., NONROAD2008a and MOVES2010a) that the
WCAQMD used to calculate the 2011 emissions inventory; and a survey of
RWC activities that the WCAQMD conducts at least once every three
years. See 2014 PM10 Plan at appendix B (``Growth Factors
for 2015, 2020, 2025, and 2030 Projections''). The WCAQMD's projected
PM10 emission levels for 2015, 2020, 2025, and 2030 are
shown in table 3.

            Table 3--Truckee Meadows PM10 Maintenance Plan Projections for 2015, 2020, 2025, and 2030
                                          [Average winter day, lbs/day]
----------------------------------------------------------------------------------------------------------------
                                Maintenance plan
           Category               baseline--2011       2015            2020            2025            2030
----------------------------------------------------------------------------------------------------------------
Point Sources.................                25              28              32              37              42

Nonpoint Sources..............            11,885          11,510          11,379          11,361          11,512
Non-road Mobile...............               606             501             386             328             307
Onroad Mobile.................             1,183             953             839             828             883
                               ---------------------------------------------------------------------------------
    Totals....................            13,700          12,992          12,637          12,554          12,744
----------------------------------------------------------------------------------------------------------------
Source: 2014 PM10 Plan at 27, Table 6-4.

    Despite expected growth in the area, the maintenance plan's
projected PM10 emissions in Truckee Meadows for 2015, 2020,
2025, and 2030 are below the 2011 maintenance inventory of 13,700 lbs/
day. The downward trend in PM10 emissions reflects the
offsetting effects of the WCAQMD's RWC program and the gradual
replacement over time of older motor vehicle and nonroad equipment with
newer models that are designed to meet more stringent emissions
standards than had applied to the older models. Based on our review, we
find that the methods, growth factors, and assumptions used by the
WCAQMD to project emissions to 2015, 2020, 2025 and 2030 levels are
reasonable. Given that the projections (summarized in table 3 above)
show future emissions in 2015, 2020, 2025, and 2030 to be below those
in 2011 (and that reflect attainment conditions), we find that the
projections provide an adequate basis to demonstrate maintenance of the
PM10 standard within Truckee Meadow through 2030. Also, as
described further in section V.D.6 of this document, the WCAQMD has
chosen to include ``safety margins'' in the motor vehicle emissions
budgets for 2015 (708 lbs/day), 2020 (1,063 lbs/day), 2025 (1,146 lbs/
day), and 2030 (955 lbs/day), but we find that the overall emissions
projections, including the safety margins, continue to demonstrate
maintenance because they do not exceed the emissions in 2011, and thus,
the safety margins are consistent with maintenance through 2030.
    Section 175A requires that the EPA approve a plan providing for
maintenance in the area for at least ten years after redesignation. If
this redesignation becomes effective in 2015, the projected 2030
inventory demonstrates that Truckee Meadows will maintain the
PM10 NAAQS for more than 10 years beyond redesignation.
Moreover, the projected emissions inventories for 2015, 2020, and 2025,
i.e., milestone years between the attainment inventory and the
maintenance plan horizon year, sufficiently demonstrate that Truckee
Meadows will maintain the standard throughout the period from
redesignation through 2030. As such, the EPA concludes that the 2014
PM10 Maintenance Plan adequately demonstrates maintenance of
the standard through 2030.
3. Monitoring Network
    Continued ambient monitoring within an area is required over the
maintenance period. See Calcagni Memo at 11. In the 2014
PM10 Maintenance Plan, the WCAQMD indicates its intention to
continue to operate an air quality monitoring network consistent with
40 CFR part 58 to verify the attainment status. 2014 PM10
Maintenance Plan at 29. The plan also notes that Washoe County's
PM10 monitoring network will be reviewed annually pursuant
to 40 CFR 58.10 to ensure the network meets the monitoring objectives
defined in 40 CFR part 58, appendix D. As discussed above in section
V.A, the WCAQMD operates an EPA-approved air quality monitoring
network. The WCAQMD obtains funding to meet the requirements of part 58
primarily from CAA section 105 grants and from the Nevada Department of
Motor Vehicles. For these reasons, we find that the 2014
PM10 Maintenance Plan provides adequately for continued
ambient PM10 monitoring through the maintenance period.
4. Verification of Continued Attainment
    Each state should ensure that it has the legal authority to
implement and enforce all measures necessary to attain and maintain the
NAAQS, including the acquisition of ambient and source emission data to
demonstrate attainment and maintenance, pursuant to CAA sections
110(a)(2)(B) and (F). See Calcagni Memo at 11. The NDEP and the WCAQMD
have the legal authority to implement and enforce the requirements of
the 2014 PM10 Maintenance Plan. This includes the authority
to adopt, implement and enforce any emission control contingency
measures determined to be necessary to correct PM10 NAAQS
violations. As noted above, to implement the maintenance plan, the
WCAQMD will continue to monitor PM10 levels in Truckee
Meadows. The WCAQMD will also continue to use three existing mechanisms
to track emissions levels to screen for significant increases in actual
PM10 emissions.
    First, the WCAQMD will continue to prepare and submit to the EPA
comprehensive periodic PM10 emissions inventories on a
triennial schedule. Second, the WCAQMD will continue to submit regular
updates of stationary and area sources within Washoe County, consistent
with the requirements of EPA's Consolidated Emissions Reporting Rule
(CERR) and AERR. Finally, the WCAQMD remains committed to conducting
its residential wood use surveys at least once every three years, to
estimate the number of devices (fireplaces, woodstoves, and pellet
stoves), amounts of wood burned, and PM10 emissions from
these activities in Washoe County. See 2014 PM10 Maintenance
Plan at 29-30.
    We find that the WCAQMD's commitments to verify continued
attainment of the PM10 NAAQS through continued ambient air
monitoring and emissions tracking are acceptable.
5. Contingency Plan
    Section 175A(d) of the CAA requires that maintenance plans include
such contingency provisions as the EPA deems necessary to promptly
correct any violations of the NAAQS that occur after redesignation of
the area. These contingency measures are distinguished from those
generally required for nonattainment areas under section 172(c)(9) in
that they are not required to be fully adopted measures that will take
effect without further action by the state. However, the contingency
plan is 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 maintenance plan should clearly identify the measures to be
adopted, a schedule and procedure for adoption and implementation, and
a specific timeline for action by the state. Contingency provisions
should also identify indicators or triggers which will be used to
determine when the contingency measures need to be implemented. The EPA
evaluates contingency measures on a case-by-case basis.\23\ Calcagni
Memo at 12, 13.
---------------------------------------------------------------------------

    \23\ Section 175A(d) also requires contingency provisions to
include a requirement that the state will implement all measures
with respect to the control of the air pollutant concerned which
were contained in the SIP for the area before redesignation of the
area to attainment. In this case, no SIP measures for the control of
PM10 in Truckee Meadows are being rescinded or relaxed,
and thus, the contingency provisions in the 2014 PM10
Maintenance Plan need not address this requirement.
---------------------------------------------------------------------------

    The 2014 PM10 Maintenance Plan contains a contingency
plan that is triggered upon a violation of the PM10
standard, that requires the WCAQMD to make certain recommendations to
the Health District within a certain time period after the triggering
event, and that commits the Health District to adopting and
implementing such recommendations as promptly and expediently as
possible, but not later than the next PM10 (i.e., winter)
season. 2014 PM10 Maintenance Plan at 30-32.
    More specifically, the contingency plan is triggered when any
monitor operated by the WCAQMD records a violation of the
PM10 NAAQS, as defined by 40 CFR part 50, Appendix K (i.e.,
when the expected number of exceedances at the monitoring site during
the calendar year is greater than one).\24\ If the contingency plan is
triggered, the WCAQMD will provide recommendations for implementation
of specific contingency measures to the Washoe County District Board of
Health (referred to herein as the ``Health District.''). The
recommendations must occur at the next regularly scheduled meeting but
no later than 45 days after the violation. The recommendations will
include a timeline for adoption and implementation as expeditiously as
possible, but no later than the next PM10 season (November,
December, and January). The WCAQMD maintains a list of potential
contingency measures, focusing on significant PM10 emission
sources, for recommendation in such events. Table 4 presents the
WCAQMD's current list of potential contingency measures.
---------------------------------------------------------------------------

    \24\ An exceedance is defined as a daily value that is above the
level of the 24-hour standard (i.e., 150 [micro]g/m\3\) after
rounding to the nearest 10 [micro]g/m\3\ (i.e., values ending in 5
or greater are to be rounded up).

        Table 4--2014 PM10 Maintenance Plan Contingency Measures
------------------------------------------------------------------------
                Category                  Potential contingency measure
------------------------------------------------------------------------
Paved Streets..........................  [ssquf] Increase stringency of
                                          street sanding and sweeping
                                          programs.
                                         [ssquf] Improve unpaved
                                          shoulders.
                                         [ssquf] Transportation control
                                          measures to reduce VMT.
Unpaved Streets........................  [ssquf] Improve unpaved streets
                                          and shoulders.
                                         [ssquf] Post speed limits to
                                          decrease vehicle speeds.
                                         [ssquf] Restrict access to
                                          decrease Average Daily Trips
                                          and VMT.
Dust Control...........................  [ssquf] Phased mass grading.
                                         [ssquf] Mass grading allocation
                                          system.
                                         [ssquf] Stabilize projects
                                          during PM10 season.
                                         [ssquf] Decrease one acre dust
                                          control permit exemption.
Residential Wood Combustion............  [ssquf] Increase one acre lot
                                          size exemption.
                                         [ssquf] Mandatory curtailment
                                          at lower PM10 concentrations.
                                         [ssquf] Change-out program to
                                          clean burning device.
Mobile Sources (Diesel)................  [ssquf] Non-road diesel engine
                                          repowers and rebuilds.
                                         [ssquf] Non-road diesel
                                          tailpipe controls (i.e.,
                                          filters and catalysts).
                                         [ssquf] Truck Stop
                                          Electrification systems for
                                          heavy-duty vehicles.
                                         [ssquf] More stringent heavy-
                                          duty diesel vehicle idling
                                          limits.
                                         [ssquf] Fleet modernization.
                                         [ssquf] More stringent
                                          inspection & maintenance
                                          program of light-duty, medium-
                                          duty, and heavy-duty vehicles
------------------------------------------------------------------------
Source: 2014 PM10 Plan at 32, Table 6-7, ``Potential PM10 Contingency
  Measures.''

    To address changes in growth and technology, which may alter the
effectiveness of different measures over time, the WCAQMD will conduct
a triennial review and reprioritization of these potential contingency
measures in coordination with the periodic PM10 emissions
inventory. See 2014 PM10 Plan at 31. The WCAQMD will notify
EPA Region 9 within 30 days of implementation of a contingency measure.
Id.
    In addition to the contingency plan described above, the
maintenance plan identifies a SIP-approved program that serves as an
automatically triggered measure when 24-hour PM10
concentrations reach or are predicted to reach ``Stage 1'' levels (154
[micro]g/m\3\). Specifically, District Regulation 050.001, ``Emergency
Episode Plan,'' is a SIP-approved program that requires the WCAQMD to
take certain actions when 24-hour PM10 concentrations reach
or are predicted to reach ``Stage 1'' levels such as: (1) Implementing
procedures to notify the public of potential health problems; (2)
prohibiting all open and prescribed burning; (3) prohibiting the use of
permitted incinerators, crematoriums, and pathological incinerators;
(4) prohibiting the use of solid fuel burning devices; and (5)
activating control plans for the largest PM10 sources in
Washoe County. 2014 PM10 Maintenance Plan at 11. As such,
implementation of District Regulation 050.001 acts to reduce the
chances that the contingency plan set forth in the 2014 PM10
Maintenance Plan will be triggered.
    Based on our review of the contingency provisions in the 2014
PM10 Maintenance Plan, as described above, we find that they
are adequate to ensure that the Health District will promptly correct
any violation of the PM10 NAAQS that occurs after
redesignation, as required by CAA section 175A(d).
6. Transportation Conformity and Motor Vehicle Emissions Budgets
    Transportation conformity is required by section 176(c) of the CAA.
Our

transportation conformity rule (codified in 40 CFR part 93, subpart A)
requires that transportation plans, programs and projects conform to
SIPs and establishes the criteria and procedures for determining
whether or not they do so. Conformity to the SIP means that
transportation activities will not produce new air quality violations,
worsen existing violations, or delay timely attainment of the NAAQS. In
this context, ``transportation activities'' refers to plans, programs,
and projects affecting the road network (paved and unpaved) and the
public transit system in nonattainment areas and in former
nonattainment areas that have been redesignated to attainment (commonly
referred to as ``maintenance'' areas.).
    PM10 maintenance plan submittals must specify the
maximum emissions of transportation-related PM10 emissions
\25\ allowed in the last year of the maintenance period, i.e., the
motor vehicle emissions budgets (MVEBs). (MVEBs may also be specified
for additional years during the maintenance period.) The MVEBs serve as
a ceiling on emissions that would result from an area's planned
transportation system. The MVEB concept is further explained in the
preamble to the November 24, 1993, transportation conformity rule (58
FR 62188). The preamble describes how to establish MVEBs in the SIP and
how to revise the MVEBs if needed.
---------------------------------------------------------------------------

    \25\ Transportation-related emissions of volatile organic
compounds (VOC) and/or oxides of nitrogen (NOX) emissions
must also be specified in PM10 areas if the 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. 40 CFR 93.102(b)(2)(iii). Neither of these
conditions apply to Truckee Meadows.
---------------------------------------------------------------------------

    The maintenance plan submittal must demonstrate that these
emissions levels, when considered with emissions from all other
sources, are consistent with maintenance of the NAAQS. In order for us
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). For more information on the transportation
conformity requirement and applicable policies on MVEBs, please visit
our transportation conformity Web site at: http://www.epa.gov/otaq/stateresources/transconf/index.htm. EPA's process for determining
adequacy of a MVEB consists of three basic steps: (1) Notifying the
public of a SIP submission; (2) providing the public the opportunity to
comment on the MVEB during a public comment period; and, (3) making a
finding of adequacy or inadequacy. The process for determining the
adequacy of a submitted MVEB is codified at 40 CFR 93.118(f).
    On January 19, 2010, the EPA announced the availability of the
Truckee Meadows 2009 PM10 Maintenance Plan with MVEBs (for
2009, 2013, 2018, and 2020) and of a 30-day public comment period on
the EPA's Adequacy Web site at: http://www.epa.gov/otaq/stateresources/transconf/currsips.htm. The comment period for this notification ended
on February 19, 2010, and the EPA received no comments from the public.
Later that year, the EPA found the MVEBs from the 2009 PM10
Maintenance Plan adequate for transportation conformity purposes. 75 FR
27776 (May 18, 2010).
    The 2014 PM10 Maintenance Plan contains PM10
MVEBs for Truckee Meadows for 2015, 2020, 2025, and 2030. The MVEBs are
the on-road mobile source primary PM10 emissions inventory
plus a safety margin for the Truckee Meadows nonattainment area for
2015, 2020, 2025, and 2030. The MVEBs in the 2014 PM10
Maintenance Plan are presented in table 5 below. The derivation of the
MVEBs is discussed on page 28 of the 2014 PM10 Maintenance
Plan and further described below.

   Table 5--2014 PM10 Maintenance Plan Motor Vehicle Emissions Budgets
                      [Average winter day, lbs/day]
------------------------------------------------------------------------
                       Budget year                             PM10
------------------------------------------------------------------------
2015....................................................           5,638
2020....................................................           6,088
2025....................................................           6,473
2030....................................................           6,927
------------------------------------------------------------------------
Source: 2014 PM10 Maintenance Plan at table 6-6, page 28.

    The WCAQMD developed the MVEBs in the 2014 PM10
Maintenance Plan by using the on-road motor vehicle emission inventory
factors in MOVES2010b and AP-42 and recent vehicle activity data from
TransCAD, a travel demand model used by the RTC, which is the MPO for
the area. The components of the MVEBs are shown in table 6 and are
comprised of direct on-road mobile source emissions, road construction
emissions, fugitive emissions from paved and unpaved roads, and safety
margins.

  Table 6--Source Categories and Direct PM10 Emissions Comprising the Motor Vehicle Emissions Budgets (Lbs per
                                 Day, Average Winter Day) in the 2014 PM10 Plan
----------------------------------------------------------------------------------------------------------------
                    Category                           2015            2020            2025            2030
----------------------------------------------------------------------------------------------------------------
Diesel Idling...................................               7               4               1               1
Paved Road--Fugitives...........................           1,414           1,517           1,627           1,736
Unpaved Road--Fugitives.........................           2,380           2,479           2,688           3,174
Road Construction...............................             183             189             185             180
On-road Motor Vehicles \a\......................             946             835             825             880
Safety Margin...................................             708           1,063           1,146             955
                                                 ---------------------------------------------------------------
    Totals......................................           5,638           6,088           6,473           6,927
----------------------------------------------------------------------------------------------------------------
\a\ On-road Motor Vehicles includes directly emitted PM10 from combustion and also reflects tire and brake wear.
Source: 2014 PM10 Maintenance Plan at table 6-6, page 28.

    A state may choose to apply a safety margin under our
transportation conformity rule so long as such margins are explicitly
quantified in the applicable plan and are shown to be consistent with
attainment or maintenance of the NAAQS (whichever is relevant to the
particular plan). See 40 CFR 93.124(a). As shown in table 7 below, each
safety margin was calculated by subtracting a future inventory from the
2011 maintenance inventory. Also, see table 6-5 in the 2014
PM10 Maintenance Plan. The safety margins equal the
difference between

the projected level of overall PM10 emissions in Truckee
Meadows in each of the maintenance years and the 2011 maintenance
inventory. Each safety margin, when combined with its corresponding
future-year inventory, is consistent with continued maintenance of the
PM10 NAAQS through 2030.

                                Table 7--Calculation of Safety Margins (lbs/day)
----------------------------------------------------------------------------------------------------------------
                                                       2015            2020            2025            2030
----------------------------------------------------------------------------------------------------------------
2011 Maintenance Inventory......................          13,700          13,700          13,700          13,700
Future-Year Inventory...........................          12,992          12,637          12,554          12,744
Safety Margin...................................             708           1,063           1,146             955
----------------------------------------------------------------------------------------------------------------
Source: 2014 PM10 Maintenance Plan at table 6-5, page 28.

    With respect to the 2014 Plan and related MVEBs, we have evaluated
the budgets against our adequacy criteria in 40 CFR 93.118(e)(4) and
(5) as part of our review of the budgets' approvability and are
completing the adequacy review of these budgets concurrent with our
final action on the 2014 Plan.\26\ The details of the EPA's evaluation
of the MVEBs for compliance with the budget adequacy criteria of 40 CFR
93.118(e) are provided in the TSD for this proposed rulemaking. On
September 10, 2015, the EPA announced the availability of the 2014 Plan
with MVEBs and a 30-day public comment period. This announcement was
posted on EPA's Adequacy Web site at: http://www.epa.gov/otaq/stateresources/transconf/reg9sips.htm#nv.
---------------------------------------------------------------------------

    \26\ Under the Transportation Conformity regulations, the EPA
may review the adequacy of submitted motor vehicle emission budgets
simultaneously with the EPA's approval or disapproval of the
submitted implementation plan. 40 CFR 93.118(f)(2).
---------------------------------------------------------------------------

    The EPA is proposing to approve the MVEBs for 2015, 2020, 2025 and
2030, shown in table 5 above, as part of our approval of 2014
PM10 Maintenance Plan. The EPA has determined that the MVEB
emission targets are consistent with emission control measures in the
SIP and are consistent with maintenance of the PM10 standard
in Truckee Meadows through 2030.\27\ As noted above, we found the MVEBs
(for years 2009, 2013, 2018, and 2020) in the 2009 PM10
Maintenance Plan to be adequate for transportation purposes, and those
are the PM10 MVEBs in effect for transportation conformity
purposes today. If we finalize today's action, as proposed, the
PM10 MVEBs (for years 2015, 2020, 2025, and 2030) from the
2014 PM10 Maintenance Plan would replace the PM10
MVEBs previously found adequate. Any and all comments on the adequacy
and approvability of the MVEBs in the 2014 PM10 Maintenance
Plan should be submitted during the comment period stated in the DATES
section of this document.
---------------------------------------------------------------------------

    \27\ On page 28 of the 2014 Plan, the WCAQMD explains ``For
years beyond 2030, the MVEB will remain at the 2030 level of 6,927
bs/day.'' This sentence refers to the fact that if the SIP does not
have a budget in a particular analysis year, the budget established
for the most recent prior year is used as described in 40 CFR
93.118(b)(ii). The 2014 Plan does not establish budgets for any
subsequent year after 2030. To avoid any ambiguity about the intent
of the language on page 28 of the 2014 Plan, WCAQMD staff clarified
that ``For years beyond 2030'' means ``For analysis years beyond
2030.'' See September 16, 2015 email from Daniel Inouye, WCAQMD, to
John Ungvarsky, EPA Region 9.
---------------------------------------------------------------------------

7. Conclusion
    Based on the review presented above of the various elements of the
state's submitted maintenance plan, we are proposing to approve the
2014 PM10 Maintenance Plan as a revision to the Nevada SIP.
In so doing, we find that the 2014 PM10 Maintenance Plan,
adopted on August 28, 2014 by the Health District and submitted by the
NDEP to the EPA on November 7, 2014, satisfies the requirements of
section 175A of the Act. If finalized as proposed, our approval of the
2014 PM10 Maintenance Plan will satisfy the criterion for
redesignation under CAA section 107(d)(3)(E)(iv).

VI. Proposed Deletion of TSP Designation for Truckee Meadows

A. General Considerations

    Consistent with CAA section 107(d)(4)(B), we have considered the
continued necessity for retaining the remaining TSP area designation in
Nevada, and as discussed below, we have decided that the TSP
nonattainment designation for Truckee Meadows (HA #87) is no longer
necessary. As a result, we are proposing to delete it from the TSP
table in 40 CFR 81.329.
    To evaluate whether the TSP area designation should be retained or
can be deleted, we have relied upon the final rule implementing the
PM10 NAAQS (see 52 FR 24634, July 1, 1987), a policy
memorandum on TSP redesignations (see memo dated May 20, 1992 from
Joseph W. Paisie, Acting Chief, SO2/Particulate Matter
Programs Branch, EPA Office of Air Quality Planning and Standards, to
Chief, Air Branch, Regions I-X, entitled ``TSP Redesignation
Request''), and our proposed and final rules establishing maximum
allowable increases in concentrations (also known as ``increments'')
for PM10 (see the proposed rule at 54 FR 41218, October 5,
1989, and the final rule at 58 FR 31622, June 3, 1993).
    Based on the above references, we believe that the relevant
considerations for evaluating whether the necessity of retaining the
TSP area designations depend upon the status of a given area with
respect to TSP and PM10. For areas that are nonattainment
for TSP but attainment for PM10, we generally find that the
TSP designations are no longer necessary and can be deleted when the
EPA (1) approves a state's revised PSD program containing the
PM10 increments, (2) promulgates the PM10
increments into a state's SIP where the State chooses not to adopt the
increments on their own, or (3) approves a state's request for
delegation of PSD responsibility under 40 CFR 52.21(u). See 58 FR
31622, at 31635 (June 3, 1993).
    For areas that are nonattainment for TSP and nonattainment for
PM10, an additional consideration is whether deletion of the
TSP designations would automatically relax any emissions limitations,
control measures or programs approved into the SIP. If such a
relaxation would occur automatically with deletion of the TSP area
designations, then we will not delete the designations until we are
satisfied that the resulting SIP relaxation would not interfere with
any applicable requirement concerning attainment, reasonable further
progress (RFP), or maintenance of the NAAQS or any other requirement of