Document ID: EPA-R09-OAR-2021-0549-0001
Agency: epa
Document Type: Proposed Rule
Title: Air Quality State Implementation Plans; Approvals and Promulgations:Second 10-Year Maintenance Plan for the Indian Wells Valley PM10Planning Area; California,
Posted Date: 2021-10-13T04:00Z

[Federal Register Volume 86, Number 195 (Wednesday, October 13, 2021)]
[Proposed Rules]
[Pages 56848-56857]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-22168]

=======================================================================
-----------------------------------------------------------------------

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R09-OAR-2021-0549; FRL-8856-01-R9]

Second 10-Year Maintenance Plan for the Indian Wells Valley PM10 
Planning Area; California

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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

SUMMARY: The Environmental Protection Agency (EPA) is proposing to 
approve the ``Indian Wells Valley Second 10-Year PM10 
Maintenance Plan'' (``Indian Wells Second Maintenance Plan'' or 
``Plan'') as a revision to the state implementation plan (SIP) for the 
State of California. The Indian Wells Second Maintenance Plan includes, 
among other elements, a base year emissions inventory, a maintenance 
demonstration, contingency provisions, and motor vehicle emissions 
budgets for use in transportation conformity determinations. The EPA is 
proposing these actions because the SIP revision meets the applicable 
statutory and regulatory requirements for such plans and motor vehicle 
emissions budgets. Lastly, the EPA is beginning the adequacy process 
for the 2020 and 2025 motor vehicle emissions budgets in the Plan 
through this proposed rule.

DATES: Comments must be received on or before November 12, 2021.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R09-
OAR-2021-0549, at https://www.regulations.gov. For comments submitted 
at Regulations.gov, follow the online instructions for submitting 
comments. Once submitted, comments cannot be edited or removed from 
Regulations.gov. The EPA may publish any comment received to its public 
docket. Do not submit electronically any information you consider to be 
Confidential Business Information (CBI) or other information whose 
disclosure is restricted by statute. Multimedia submissions (audio, 
video, etc.) must be accompanied by a written comment. The written 
comment is considered the official comment and should include 
discussion of all points you wish to make. The EPA will generally not 
consider comments or comment contents located outside of the primary 
submission (i.e., on the web, cloud, or other file sharing system). For 
additional submission methods, please contact the person identified in 
the FOR FURTHER INFORMATION CONTACT section. For the full EPA public 
comment policy, information about CBI or multimedia submissions, and 
general guidance on making effective comments, please visit https://www.epa.gov/dockets/commenting-epa-dockets. If you need assistance in a 
language other than English or if you are a person with disabilities 
who needs a reasonable accommodation at no cost to you, please contact 
the person identified in the FOR FURTHER INFORMATION CONTACT section.

FOR FURTHER INFORMATION CONTACT: Ashley Graham, EPA Region IX, 75 
Hawthorne St., San Francisco, CA 94105. By phone: (415) 972-3877 or by 
email at [email protected].

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

Table of Contents

I. Background
    A. The PM10 National Ambient Air Quality Standards
    B. The Indian Wells Valley PM10 Planning Area
II. Procedural Requirements for Adoption and Submittal of State 
Implementation Plan Revisions
III. Requirements for Second 10-Year Maintenance Plans
IV. Evaluation of the Indian Wells Second Maintenance Plan
    A. Emissions Inventories
    B. Maintenance Demonstration
    C. Verification of Continued Attainment
    D. Contingency Provisions
    E. Motor Vehicle Emissions Budgets for Transportation Conformity
V. Proposed Action and Request for Public Comment
VI. Statutory and Executive Order Reviews

I. Background

A. The PM10 National Ambient Air Quality Standards

    Under section 109 of the Clean Air Act (CAA or ``Act''), the EPA 
established national ambient air quality standards (NAAQS or 
``standards'') for certain pervasive air pollutants (referred to as 
``criteria pollutants'') and conducts periodic reviews of the NAAQS to 
determine whether they should be revised or whether new NAAQS should be 
established. The EPA sets the NAAQS for criteria pollutants at levels 
required to protect public health and welfare.\1\ Particulate matter is 
one of the ambient pollutants for which the EPA has established 
NAAQS.\2\
---------------------------------------------------------------------------

    \1\ For a given air pollutant, ``primary'' standards are those 
determined by the EPA as requisite to protect the public health. 
``Secondary'' standards are those determined by the EPA as requisite 
to protect the public welfare from any known or anticipated adverse 
effects associated with the presence of such air pollutant in the 
ambient air. CAA section 109(b).
    \2\ 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 dioxide (SO2), oxides of 
nitrogen (NOX), volatile organic compounds (VOC), and 
ammonia (NH3). The chemical and physical properties of 
particulate matter vary greatly with time, region, meteorology, and 
source category. SO2, NOX, VOC, and 
NH3 are referred to as PM10 precursors. As 
discussed later in this proposed rule, precursors do not contribute 
significantly to elevated ambient PM10 concentrations in 
the Indian Wells Valley planning area. Some California air quality 
plans use the term reactive organic gases (ROG) instead of VOC. The 
terms cover essentially the same compounds, and herein we use the 
term VOC.
---------------------------------------------------------------------------

    In 1987, the EPA established primary and secondary NAAQS for 
particles with an aerodynamic diameter less than or equal to a nominal 
10 microns in diameter (PM10).\3\ At that time, the EPA 
established two PM10 standards; an annual standard and a 24-
hour standard.\4\ The annual PM10 standard was subsequently 
revoked.\5\ More recently, the EPA announced that it was retaining the 
24-hour PM10 NAAQS as a 24-hour standard of 150 micrograms 
per cubic meter ([micro]g/m\3\).\6\ In this document, ``PM10 
NAAQS'' or ``PM10 standard'' refer to the 24-hour 
PM10 NAAQS.
---------------------------------------------------------------------------

    \3\ 52 FR 24634 (July 1, 1987).
    \4\ The primary and secondary standards were set at the same 
level for both the 24-hour and the annual PM10 standards.
    \5\ In 2006, the EPA retained the 24-hour PM10 
standards but revoked the annual standards. 71 FR 61144 (October 17, 
2006).
    \6\ 78 FR 3086 (January 15, 2013).
---------------------------------------------------------------------------

    An area attains the 24-hour standard of 150 [micro]g/m\3\ when the 
expected number of days per calendar year with a 24-hour

[[Page 56849]]

concentration above the standard (referred to as an ``exceedance''),\7\ 
averaged over three years, is equal to or less than one. The expected 
number of exceedances averaged over a three-year period at any given 
monitor is known as the PM10 design value. The 
PM10 design value for the area is the highest design value 
within the nonattainment area.\8\
---------------------------------------------------------------------------

    \7\ 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 
five or greater are to be rounded up). Thus, a recorded value of 154 
[micro]g/m\3\ would not be an exceedance because it would be rounded 
to 150 [micro]g/m\3\. A recorded value of 155 [micro]g/m\3\ would be 
an exceedance because it would be rounded to 160 [micro]g/m\3\. 40 
CFR part 50, Appendix K, section 1.0.
    \8\ 40 CFR 50.6 and 40 CFR part 50, appendix K. 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). 40 CFR part 50, appendix K, section 2.1(b).
---------------------------------------------------------------------------

    Generally, the EPA determines whether an area's air quality is 
meeting the PM10 NAAQS based on the most recent complete,\9\ 
quality-assured, and certified data measured 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 
monitoring sites operated by state, local, or tribal agencies in 
compliance with the EPA's monitoring requirements must be submitted to 
AQS. These monitoring agencies annually certify that these data are 
accurate to the best of their knowledge. Accordingly, the EPA relies 
primarily on data in AQS when determining the attainment status of an 
area.\10\ All valid data are reviewed to determine the area's air 
quality status in accordance with 40 CFR part 50, appendix K.
---------------------------------------------------------------------------

    \9\ For PM10, a complete year of air quality data 
includes all four calendar quarters with each quarter containing a 
minimum of 75 percent of the scheduled PM10 sampling 
days. 40 CFR part 50, Appendix K, section 2.3(a).
    \10\ 40 CFR 50.6; 40 CFR part 50, appendix J; 40 CFR part 53; 
and 40 CFR part 58, appendices A, C, D, and E.
---------------------------------------------------------------------------

B. The Indian Wells Valley PM10 Planning Area

    Under section 107 of the CAA, the EPA is required to designate all 
areas of the country as attainment, nonattainment, or unclassifiable 
for each of the NAAQS. In response to an area designation of 
nonattainment, states are required to adopt and submit SIP revisions 
that, among other things, provide for attainment of the NAAQS within 
such area. Once a nonattainment area attains the NAAQS and meets 
certain other prerequisites, the state may request that the EPA 
redesignate the area to attainment.
    Through its enactment of the CAA Amendments of 1990, Congress 
designated certain areas of the country as nonattainment areas for the 
PM10 NAAQS. The Searles Valley planning area was one of the 
areas designated as nonattainment.\11\ In 1991, the EPA classified the 
Searles Valley planning area, as a ``Moderate'' PM10 
nonattainment area.\12\
---------------------------------------------------------------------------

    \11\ CAA section 107(d)(4)(B)(i) and 52 FR 29383 (August 7, 
1987).
    \12\ 56 FR 56694 (November 6, 1991).
---------------------------------------------------------------------------

    The Searles Valley planning area included three subregions (Coso 
Junction, Indian Wells Valley, and Trona) under the planning 
jurisdiction of different air pollution control agencies. On August 6, 
2002, the EPA changed the boundaries of the Searles Valley 
PM10 nonattainment area by dividing this area into three 
separate, newly created PM10 nonattainment areas, including 
the Indian Wells Valley planning area.\13\ The Indian Wells Valley 
planning area is under the planning jurisdiction of the Eastern Kern 
Air Pollution Control District (EKAPCD or ``District''). The planning 
area boundaries include the portion of Kern County contained within the 
United States Geological Survey Hydrologic Unit #108090205.\14\ It 
covers approximately 300 square miles and is populated by about 30,000 
persons, with only one community of significant size, Ridgecrest.
---------------------------------------------------------------------------

    \13\ 67 FR 50805.
    \14\ For the definition of the Indian Wells Valley planning 
area, see 40 CFR 81.305.
---------------------------------------------------------------------------

    On May 7, 2003, the EPA determined that the Indian Wells Valley 
planning area had attained the 24-hour PM10 NAAQS.\15\ The 
determination was based on complete, quality-assured, and certified 
ambient air monitoring data that showed the area monitored attainment 
of the PM10 NAAQS during 1999-2001.\16\ Based on the 
determination, the EPA finalized approval of the maintenance plan and 
redesignated the Indian Wells Valley planning area to attainment, 
effective June 6, 2003.\17\
---------------------------------------------------------------------------

    \15\ 68 FR 24368.
    \16\ 67 FR 77196 (December 17, 2002).
    \17\ 68 FR 24368.
---------------------------------------------------------------------------

    EKAPCD is a monitoring organization within the California Air 
Resources Board (CARB) Primary Quality Assurance Organization. EKAPCD 
operates the PM10 monitoring network in the Indian Wells 
Valley area. CARB submits annual monitoring network plans to the EPA 
that cover monitors operated by EKAPCD. These network plans describe 
the monitoring network operated by EKAPCD within the Indian Wells 
Valley area and discuss the status of the air monitoring network, as 
required under 40 CFR 58.10. The EPA regularly reviews these annual 
plans for compliance with the applicable reporting requirements in 40 
CFR part 58. With respect to PM10, the EPA has found that 
CARB's network plans meet the applicable reporting requirements for the 
area under 40 CFR part 58, appendix D.\18\ EKAPCD and CARB annually 
certify that the data they submit to AQS are complete and quality-
assured.\19\
---------------------------------------------------------------------------

    \18\ For example, see letter dated November 5, 2020, from Gwen 
Yoshimura, Manager, Air Quality Analysis Office, EPA Region IX, to 
Ravi Ramalingam, Chief, Consumer Products and Air Quality Assessment 
Branch, Air Quality Planning and Science Division, CARB.
    \19\ For example, see letter dated June 21, 2021, from Sylvia 
Vanderspek, Chief, Air Quality Planning Branch, CARB, to Gwen 
Yoshimura, Manager, Air Quality Analysis Office, EPA Region 9.
---------------------------------------------------------------------------

    EKAPCD operates one PM10 SLAMS monitoring site, 
Ridgecrest (AQS ID: 06-029-0018), within the Indian Wells Valley 
PM10 planning area.\20\ The monitor is located at the 
northeast corner of Sydnor Avenue and Primavera Street in Ridgecrest, 
California \21\ (see Figure 8 in the Indian Wells Second Maintenance 
Plan) and was sited to monitor the highest concentration in the area at 
a neighborhood scale. SLAMS monitors produce data comparable to the 
NAAQS, and therefore the monitor must be an approved federal reference 
method, federal equivalent method (FEM), or approved regional method. 
The Ridgecrest monitor measures hourly PM10 concentrations 
on a daily, year-round basis using a method that has been designated as 
an FEM by the EPA.
---------------------------------------------------------------------------

    \20\ The EPA approved the relocation of the Ridgecrest monitor 
from the California Ave (06-029-0015) site to the Ward Ave site (06-
029-0018) on June 27, 2018. See letter dated June 27, 2018, from 
Gwen Yoshimura, Manager, Air Quality Analysis Office, Air Division, 
EPA Region IX, to Glen E. Stephens, P.E., Air Pollution Control 
Officer, EKAPCD.
    \21\ Monitoring site address is 2051 Ward Ave., Ridgecrest, CA 
93555.
---------------------------------------------------------------------------

    Table 1 shows the maximum monitored 24-hour PM10 
concentrations at the Ridgecrest monitoring site for 2002-2020. The 
table reflects that values for the Indian Wells Valley area are 
typically well below the PM10 NAAQS of 150 [micro]g/m\3\.

[[Page 56850]]

        Table 1--Indian Wells Valley PM10 Maximum 24-Hour Values
 [Ridgecrest monitor, AQS identification number 06-029-0015/06-029-0018]
------------------------------------------------------------------------
                                                           Maximum value
                          Year                              ([micro]g/
                                                               m\3\)
------------------------------------------------------------------------
2002....................................................              84
2003....................................................             162
2004....................................................              47
2005....................................................              55
2006....................................................              65
2007....................................................              72
2008....................................................              57
2009....................................................              46
2010....................................................              52
2011....................................................             143
2012....................................................              43
2013....................................................              56
2014....................................................              51
2015....................................................              44
2016....................................................              66
2017....................................................              60
2018....................................................             107
2019....................................................             177
2020....................................................             401
------------------------------------------------------------------------
Sources: EPA Air Quality System Quicklook Report 2001-2021, accessed
  February 8, 2021, and EPA Air Quality System Maximum Values Report
  2019-2020, accessed August 10, 2021.

    Table 2 shows the estimated number of exceedances for the Indian 
Wells Valley PM10 area for the three-year design value 
periods starting in 2002 and ending in 2020. As shown in Table 1, one 
exceedance of the PM10 NAAQS was recorded in 2003 at the 
Ridgecrest monitor. The District attributed the February 2, 2003 
exceedance to transport of windblown dust from the Owens Lake area, 
citing high PM10 concentration readings at several nearby 
sites.\22\ Because the monitor operated on a one-in-six day sampling 
schedule during that time, the resulting estimated number of 
exceedances (i.e., 24-hour design values) for the 2001-2003, 2002-2004, 
and 2003-2005 periods are 2.0 at the Ridgecrest monitor. Since that 
time, the Indian Wells Valley has attained the PM10 NAAQS.
---------------------------------------------------------------------------

    \22\ Email dated August 20, 2021, from Jeremiah Cravens, EKAPCD, 
to Ashley Graham, EPA Region IX. See also EPA Air Quality System Raw 
Data Qualifier Report 2003, accessed August 10, 2021. The report 
shows that the District flagged the February 2, 2003 exceedance with 
the ``High Winds'' qualifier with a request to exclude the data as 
an exceptional event. The State did not submit documentation and a 
request for the EPA to concur on the exceedance as an exceptional 
event pursuant to 40 CFR 50.14.

             Table 2--Indian Wells Valley PM10 Design Values
 [Ridgecrest monitor, AQS identification number 06-029-0015/06-029-0018]
------------------------------------------------------------------------
                                                           Design value
                   Design value period                      ([micro]g/
                                                               m\3\)
------------------------------------------------------------------------
2000-2002...............................................             0.0
2001-2003...............................................             2.0
2002-2004...............................................             2.0
2003-2005...............................................             2.0
2004-2006...............................................         \a\ 0.0
2005-2007...............................................         \a\ 0.0
2006-2008...............................................         \a\ 0.0
2007-2009...............................................             0.0
2008-2010...............................................             0.0
2009-2011...............................................             0.0
2010-2012...............................................             0.0
2011-2013...............................................             0.0
2012-2014...............................................             0.0
2013-2015...............................................             0.0
2014-2016...............................................             0.0
2015-2017...............................................             0.0
2016-2018...............................................             0.0
2017-2019...............................................             0.3
2018-2020...............................................             0.7
------------------------------------------------------------------------
Sources: EPA Air Quality System Design Value Report 2001-2021, accessed
  February 8, 2021 and EPA Air Quality System Design Value Report 2020,
  accessed August 10, 2021.
\a\ Invalid design value due to incomplete data in data years 2004,
  2005, and 2006.

    In California, CARB is the state agency responsible for the 
adoption and submission to the EPA of California SIPs and SIP 
revisions, and it has broad authority to establish emissions standards 
and other requirements for mobile sources. Local and regional air 
pollution control districts in California are responsible for the 
regulation of stationary sources and are generally responsible for the 
development of air quality plans. In the eastern portion of Kern 
County, EKAPCD develops and adopts air quality plans to address CAA 
planning requirements applicable to the Indian Wells Valley planning 
area. Such plans are then submitted to CARB for adoption and submittal 
to the EPA as revisions to the California SIP.
    On July 30, 2020, CARB submitted the ``Revised PM10 
Maintenance Plan for Indian Wells Valley Attainment/Maintenance Area'' 
(``Indian Wells Second Maintenance Plan'') for the 24-hour 
PM10 NAAQS.\23\
---------------------------------------------------------------------------

    \23\ The submittal package included the following two documents 
that make up the Indian Wells Second Maintenance Plan: ``Revised 
PM10 Maintenance Plan for Indian Wells Valley Attainment/
Maintenance Area'' and ``Indian Wells Valley Condensable 
PM10 Emission Inventory.''
---------------------------------------------------------------------------

II. Procedural Requirements for Adoption and Submittal of State 
Implementation Plan Revisions

    CAA sections 110(a)(1) and (2) and section 110(l) require states to 
provide reasonable notice and opportunity for public hearing prior to 
adoption and submission of a SIP or SIP revision. To meet these 
procedural requirements, every SIP submission should include evidence 
that the state provided adequate public notice and an opportunity for a 
public hearing consistent with the EPA's implementing regulations in 40 
CFR 51.102.
    CARB's July 30, 2020 SIP submittal package includes documentation 
of the public processes used by the District and CARB to adopt the 
Indian Wells Second Maintenance Plan. As documented in the submittal 
package, on April 1, 2020, the District published a notice in the 
Bakersfield Californian, a newspaper of general circulation in Kern 
County, that a public hearing to consider adoption of the Plan would be 
held on May 7, 2020. As documented in EKAPCD Resolution No. 2020-003-05 
included in the SIP revision submittal package, the Air Pollution 
Control Board of the EKAPCD adopted the Indian Wells Second Maintenance 
Plan on May 7, 2020, following the public hearing. On May 22, 2020, 
CARB published on its website a notice of public hearing to be held on 
June 25, 2020, to consider adoption of the Plan. As evidenced by CARB 
Resolution 20-18, CARB adopted the Indian Wells Second Maintenance Plan 
on June 25, 2020, following a public hearing. Based on documentation 
included in the July 30, 2020 SIP revision submittal package, we find 
that both the District and CARB have satisfied the applicable statutory 
and regulatory requirements for reasonable public notice and hearing 
prior to adoption and submission of the Plan. Therefore, we find that 
the submission of the Indian Wells Second Maintenance Plan meets the 
procedural requirements for public notice and hearing in CAA sections 
110(a) and 110(l) and in 40 CFR 51.102.\24\
---------------------------------------------------------------------------

    \24\ On January 30, 2021, the Indian Wells Second Maintenance 
Plan was deemed complete by operation of law under CAA section 
110(k)(1)(B).
---------------------------------------------------------------------------

III. Requirements for Second 10-Year Maintenance Plans

    Section 175A of the CAA provides the general framework for 
maintenance plans. The initial 10-year maintenance plan must provide 
for maintenance of the NAAQS for at least 10 years after redesignation, 
including any additional control measures necessary to ensure such 
maintenance. In addition, maintenance plans are to contain contingency 
provisions necessary to ensure the prompt correction of a violation of 
the NAAQS that occurs after redesignation. The contingency

[[Page 56851]]

measures must include, at a minimum, a requirement that the state will 
implement all control measures contained in the nonattainment SIP prior 
to redesignation.
    Section 175A(b) of the CAA requires states to submit a subsequent 
maintenance plan revision (``second 10-year maintenance plan'') eight 
years after redesignation. The Act requires only that this second 10-
year maintenance plan maintain the applicable NAAQS for 10 years after 
the expiration of the first 10-year maintenance plan. Beyond these 
provisions, section 175A of the CAA does not define the content of a 
second 10-year maintenance plan.
    The primary guidance on maintenance plans and redesignation 
requests is a September 4, 1992 memorandum from John Calcagni, titled 
``Procedures for Processing Requests to Redesignate Areas to 
Attainment'' (``Calcagni Memo'').\25\ The Calcagni Memo outlines the 
key elements of a maintenance plan, which include an attainment 
emissions inventory, maintenance demonstration, monitoring and 
verification of continued attainment, and a contingency plan.
---------------------------------------------------------------------------

    \25\ Memorandum dated September 4, 1992, from John Calcagni, 
Director, EPA Air Quality Management Division, to Regional Office 
Air Division Directors, Subject: Procedures for Processing Requests 
to Redesignate Areas to Attainment.
---------------------------------------------------------------------------

    Maintenance plan submittals are SIP revisions, and as such, the EPA 
is obligated under CAA section 110(k) to approve them or disapprove 
them depending upon whether they meet the applicable CAA requirements 
for such plans.

IV. Evaluation of the Indian Wells Second Maintenance Plan

A. Emissions Inventories

    A maintenance plan for the PM10 NAAQS should include an 
inventory of direct PM10 emissions in the area.\26\ The 
inventory should be consistent with the EPA's most recent guidance on 
emissions inventories for nonattainment areas available at the time; 
must be comprehensive, including emissions from stationary point 
sources, area sources, and mobile sources; and must be based on actual 
emissions during the appropriate season, if applicable.\27\
---------------------------------------------------------------------------

    \26\ PM10 precursor emissions should also be included 
depending upon the contribution of secondary particulate matter to 
high ambient PM10 concentrations in the area. In this 
instance, an inventory of PM10 precursor emissions is not 
required because PM10 precursor controls were not relied 
upon to achieve attainment of the PM10 NAAQS in the 
Indian Wells Valley planning area nor are they relied upon to 
demonstrate maintenance of the NAAQS (see Indian Wells Second 
Maintenance Plan, section IV, and 67 FR 77196, 77201 (December 17, 
2002)). While not required, the Indian Wells Second Maintenance Plan 
includes inventories of NOX, SOX, and ammonia 
in appendix D (``IWV Precursor Emission Inventories'').
    \27\ CAA section 172(c)(3).
---------------------------------------------------------------------------

    The specific PM10 emissions inventory requirements are 
set forth in the Air Emissions Reporting Requirements rule,\28\ which 
requires that emissions inventories report filterable and condensable 
components, as applicable.\29\ The EPA has provided additional guidance 
for developing PM10 emissions inventories in 
``PM10 Emissions Inventory Requirements,'' EPA-454/R-94-033 
(September 1994) and ``Emissions Inventory Guidance for Implementation 
of Ozone and Particulate Matter National Ambient Air Quality Standards 
(NAAQS) and Regional Haze Regulations'' (May 2017).
---------------------------------------------------------------------------

    \28\ 40 CFR part 51, subpart A.
    \29\ 40 CFR 51.15(a)(1)(vii).
---------------------------------------------------------------------------

    The Indian Wells Second Maintenance Plan includes inventories for 
total primary PM10 and for the PM10 precursors 
NOX, SOX, and ammonia for the years 2013 (the 
final year of the first maintenance period) through 2025 (the final 
year of the second maintenance period).\30\ The 2017 emissions 
inventory represents current emissions and was used to project 
emissions through 2025, as discussed further in section IV.B of this 
document. The emissions inventories in the Plan include estimates from 
all relevant source categories that the Plan divides among fuel 
combustion, waste disposal, cleaning and surface coatings, industrial 
processes, miscellaneous processes, on-road motor vehicles, and off-
road motor vehicles.\31\ CARB and the District developed the emissions 
inventories based on the methods and assumptions presented in detail in 
Appendix D (``IWV Precursor Emission Inventories 2002-2025'').\32\ The 
direct PM10 and PM10 precursor emissions are 
presented in tables 2 and 3 and Appendix D of the Plan, and the 
specific filterable and condensable components of the direct 
PM10 emissions estimates are identified in the accompanying 
document titled ``Indian Wells Valley Condensable PM10 
Emission Inventory.'' Table 3 provides a summary of the 2017 direct 
PM10 base year emissions inventory in tons per day (tpd) for 
the Indian Wells Valley area. Because the Indian Wells Second 
Maintenance Plan depends on direct PM10 emissions to 
demonstrate compliance, the EPA reviewed those direct PM10 
emissions estimates and not the District's emissions estimates for 
PM10 precursor emissions.
---------------------------------------------------------------------------

    \30\ Indian Wells Second Maintenance Plan, sections IV.B and 
IV.D, and Appendix D.
    \31\ Indian Wells Second Maintenance Plan, sections IV.B and 
IV.D.
    \32\ While Appendix D is titled ``IWV Precursor Emission 
Inventories 2002-2005,'' the appendix presents the full emissions 
inventory documentation for direct PM10 in addition to 
PM10 precursors.

     Table 3--Indian Wells PM10 Base Year (2017) Emissions Inventory
                          [Annual average, tpd]
------------------------------------------------------------------------
        Source category                Subcategory             PM10
------------------------------------------------------------------------
Stationary Point Sources.......  Fuel Combustion........           0.031
                                 Waste Disposal.........           0.002
                                 Cleaning & Surface                0.001
                                  Coatings.
                                 Industrial Processes...           0.019
Areawide Sources...............  Miscellaneous Processes           1.199
Mobile Sources.................  On-Road Motor Vehicles.           0.039
                                 Off-Road Motor Vehicles           1.172
                                                         ---------------
    Total......................  All Stationary,                   2.462
                                  Areawide, and Mobile
                                  Sources.
------------------------------------------------------------------------
Source: Indian Wells Second Maintenance Plan, Table 3 and Appendix D.
\a\ Emissions inventories are required to include direct PM10 emissions,
  separately reported as PM10 filterable and condensable emissions. 40
  CFR 51.15(a)(1)(vii). The accompanying document titled ``Indian Wells
  Valley Condensable PM10 Emission Inventory'' provides this
  information.
Totals may not add up due to rounding.

[[Page 56852]]

    As discussed in Appendix D of the Indian Wells Second Maintenance 
Plan, direct PM10 emissions estimates for stationary point 
sources reflect actual emissions reported to the District in 2017 by 
owners or operators of industrial point sources in the Indian Wells 
Valley planning area. Areawide sources, such as consumer products and 
agricultural burning, occur over a wide geographic area. Emissions for 
these categories are estimated by both CARB and the District using 
various models and methodologies.
    Emissions from on-road mobile sources, which include passenger 
vehicles, buses, and trucks, were estimated using outputs from CARB's 
EMFAC2017 model.\33\ These emissions were calculated by applying 
EMFAC2017 emissions factors to the transportation activity data 
provided by the Kern Council of Governments (KCOG) from their 2018 
Regional Transportation Plan/2019 Federal Transportation Improvement 
Program (2018 RTP/2019 FTIP).\34\ KCOG is the metropolitan planning 
organization representing Kern County and the 11 incorporated cities 
within Kern County.
---------------------------------------------------------------------------

    \33\ EMFAC is short for EMission FACtor. The EPA approved 
EMFAC2017 for SIP development and transportation conformity purposes 
in California on August 15, 2019. 84 FR 41717. EMFAC2017 was the 
most recently approved version of the EMFAC model that was available 
at the time of preparation of the Indian Wells Second Maintenance 
Plan.
    \34\ The Kern Council of Governments Board of Directors adopted 
the 2018 RTP/2019 FTIP on August 16, 2018.
---------------------------------------------------------------------------

    Emissions from off-road mobile sources (e.g., cargo handling 
equipment, pleasure craft, recreational vehicles, and locomotives) were 
estimated using a suite of category-specific models or, where a new 
model was not available, the OFFROAD2007 model. Many of the newer 
models were developed to support recent regulations, including in-use 
off-road equipment.
    Based on the estimates for the year 2017 in Table 3, areawide and 
off-road mobile sources account for a majority (approximately 96 
percent) of total PM10 emissions in the Indian Wells Valley 
planning area.\35\ Fugitive windblown dust and unpaved road dust 
account for a majority of the areawide emissions (54 percent and 17 
percent, respectively), whereas aircraft account for a majority of the 
off-road mobile source emissions (98 percent).
---------------------------------------------------------------------------

    \35\ Indian Wells Second Maintenance Plan, Appendix C.
---------------------------------------------------------------------------

    The EPA considers the selection of the 2017 base year inventory to 
be appropriate given that it is the most recent emissions inventory 
associated with the triennial reporting schedule required under the Air 
Emissions Reporting Requirements rule. Moreover, preparation of an 
annual average daily inventory, as opposed to a seasonal or episodic 
inventory, is appropriate given that elevated PM10 
concentrations in the Indian Wells Valley do not exhibit a clear 
seasonal or episodic pattern. Based on our review of the documentation 
provided with the plan, we find that the 2017 emissions inventory for 
direct PM10 is based on reasonable assumptions and 
methodologies, and that the inventory is comprehensive, current, 
accurate, and consistent with applicable CAA provisions and the 
Calcagni Memo.

B. Maintenance Demonstration

    Section 175A(a) of the CAA requires that the maintenance plan 
``provide for the maintenance of the national primary ambient air 
quality standard for such air pollutant in the area concerned for at 
least 10 years after the 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 conducting modeling that shows that the 
future mix of sources and emissions rates will not cause a violation of 
the NAAQS.\36\ Projected emissions inventories for future years must 
account for, among other things, the ongoing effects of economic growth 
and adopted emissions control requirements, and the inventories are 
expected to be the best available representation of future emissions. 
The plan submission should include documentation explaining how the 
state calculated the emissions data for the base year and projected 
inventories.
---------------------------------------------------------------------------

    \36\ Calcagni Memo, 9-11.
---------------------------------------------------------------------------

    The Indian Wells Second Maintenance Plan demonstrates continued 
maintenance of the PM10 NAAQS by projecting the direct 
PM10 emissions in the area through 2025 and showing that 
future emissions of PM10 will not exceed the level of the 
attainment inventory. As discussed in section IV.A, the Plan includes 
emissions inventories representing actual emissions in 2013 (the final 
year of the first maintenance period) through 2017 (the Plan's base 
year inventory), and projected emissions for 2018 through 2025 (the 
final year of the second maintenance period) for sources in the Indian 
Wells Valley planning area.\37\
---------------------------------------------------------------------------

    \37\ Indian Wells Second Maintenance Plan, sections IV.B and 
IV.D, and Appendix D.
---------------------------------------------------------------------------

    Projected inventories are derived by applying expected growth 
trends for each source category and are based on data that reflect 
historical trends, current conditions, and recent economic and 
demographic forecasts with expected emissions reductions resulting from 
adopted control measures to the base year inventory. For the Indian 
Wells Second Maintenance Plan, emissions projections for 2018 through 
2025 were generated by applying growth and control profiles to the 2017 
base year inventory. Growth forecasts for most point and areawide 
sources were developed by CARB. Mobile sources were forecast using 
total vehicle miles traveled projections provided by KCOG. Off-road 
sources were forecast using various growth surrogates as shown in Table 
7 of Appendix D of the Plan. Appendix D documents the methods and 
assumptions used to develop the emissions projections upon which the 
maintenance demonstration relies and presents the detailed source-
category-specific estimates for each of the analysis years.
    Table 4 presents a summary of the Indian Wells Second Maintenance 
Plan's estimates of direct PM10 emissions in an interim year 
(2020) and the horizon year (2025) along with the corresponding 
emissions estimates for the year 2013 (the final year of the first 
maintenance period) and the 2017 base year. For simplicity, Table 4 
shows emissions for just one of the interim years (i.e., 2020) between 
the base year and the horizon year, but as discussed above, the Plan 
provides emissions estimates for each year from 2013 through 2025.\38\
---------------------------------------------------------------------------

    \38\ Id. at Table 2 and Table 3.

[[Page 56853]]

                   Table 4--Indian Wells PM10 Emissions Inventory, 2013, 2017, 2020, and 2025
                                              [Annual average, tpd]
----------------------------------------------------------------------------------------------------------------
       Source  category            Subcategory         2013            2017            2020            2025
----------------------------------------------------------------------------------------------------------------
Stationary Point Sources......  Fuel Combustion.           0.018           0.031           0.027           0.018
                                Waste Disposal..           0.000           0.002           0.002           0.002
                                Cleaning &                 0.000           0.001           0.001           0.001
                                 Surface
                                 Coatings.
                                Industrial                 0.009           0.019           0.020           0.021
                                 Processes.
Areawide Sources..............  Miscellaneous              1.424           1.199           1.193           1.262
                                 Processes.
Mobile Sources................  On-Road Motor              0.051           0.039           0.037           0.036
                                 Vehicles.
                                Off-Road Motor             1.228           1.172           1.167           1.161
                                 Vehicles.
                                                 ---------------------------------------------------------------
    Total.....................  All Stationary,            2.679           2.462           2.446           2.501
                                 Areawide, and
                                 Mobile Sources.
----------------------------------------------------------------------------------------------------------------
Source: Indian Wells Second Maintenance Plan, Table 2 and Table 3.
Totals may not add up due to rounding.

    The emissions estimates in the Plan predict a gradual change in 
direct PM10 emissions within the Indian Wells Valley 
planning area over time, with slight decreases in certain categories 
(e.g., fuel combustion, on-road motor vehicles, off-road motor 
vehicles) nearly offsetting slight increases in certain other source 
categories (i.e., industrial processes, miscellaneous processes) 
relative to the 2017 base year emissions. By 2025, overall direct 
PM10 emissions are estimated to be approximately 0.039 tpd 
(1.6 percent) higher than in the 2017 base year. However, despite the 
expected growth in the area, the Plan's projected PM10 
emissions through 2025 are approximately 0.178 tpd (6.6 percent) lower 
than emissions in 2013, the final year of the first maintenance period 
and a year in which there were no recorded exceedances of the 
PM10 NAAQS.
    Based on our review, we find that the projected emissions 
inventories for direct PM10 for years 2018 through 2025 are 
based on reasonable methods, growth factors, and assumptions, and are 
based on the most current and accurate information available to CARB 
and EKAPCD at the time the Plan and its inventories were being 
developed. Given that the projections of direct PM10 
emissions show future emissions increases through 2025 are within 1.6 
percent of those in 2017 and below those in 2013 (both of which reflect 
attainment conditions), we find that the Indian Wells Second 
Maintenance Plan provides an adequate basis to demonstrate maintenance 
of the PM10 NAAQS within the Indian Wells Valley planning 
area through 2025. Lastly, we find that by providing emissions 
projections through 2025, the Plan demonstrates maintenance of the 
PM10 NAAQS for more than 10 years after the expiration of 
the first 10-year maintenance plan (i.e., 2023) in accordance with 
section 175A(b) of the CAA.

C. Verification of Continued Attainment

    Once an area has been redesignated, the state should continue to 
operate an appropriate air quality monitoring network, in accordance 
with 40 CFR part 58, to verify the attainment status of the area.\39\ 
Data collected by the monitoring network are also needed to implement 
the contingency provisions of the maintenance plan.
---------------------------------------------------------------------------

    \39\ Calcagni Memo, 11.
---------------------------------------------------------------------------

    As discussed in section I.B, EKAPCD monitors ambient concentrations 
of PM10 in the Indian Wells Valley planning area at the 
Ridgecrest monitoring station. In section V.A (``Tracking'') of the 
Indian Wells Second Maintenance Plan, the District commits to continue 
to operate and maintain a PM10 air quality monitor in 
Ridgecrest in accordance with 40 CFR part 58. We find that the Indian 
Wells Second Maintenance Plan contains adequate provisions for 
continued ambient PM10 monitoring to verify continued 
attainment through the maintenance period.
    The EPA also recommends that the state verify continued attainment 
through methods in addition to the ambient air monitoring program, 
e.g., through periodic review of the factors used in development of the 
attainment inventory to show no significant change.\40\ In the Indian 
Wells Second Maintenance Plan, EKAPCD commits to perform periodic 
reviews of the air monitoring data and emissions inventory, to review 
the inputs and assumptions used to develop the emissions inventory on 
an annual basis, and, if the District finds that these inputs have 
changed significantly, to request that CARB update the existing 
inventory and to compare the revised inventory with the inventories in 
the Indian Wells Second Maintenance Plan.\41\ We find that the 
District's commitment to verify continued attainment of the 
PM10 NAAQS through continued ambient air monitoring and 
annual review of the inputs and assumptions used to develop the 
emissions inventories in the Indian Wells Second Maintenance Plan are 
acceptable.
---------------------------------------------------------------------------

    \40\ Id.
    \41\ Indian Wells Second Maintenance Plan, section VI 
(``Subsequent Maintenance Plan Revisions'').
---------------------------------------------------------------------------

D. Contingency Provisions

    Section 175A(d) of the CAA requires that maintenance plans include 
contingency provisions, as the EPA deems necessary, to promptly correct 
any violations of the NAAQS that occur after redesignation of the area. 
Such provisions must include a requirement that the state will 
implement all measures with respect to the control of the relevant air 
pollutants that were contained in the SIP for the area before 
redesignation of the area as an attainment area. These contingency 
provisions are distinguished from contingency measures required for 
nonattainment areas under CAA 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 for the maintenance plan to be approved. 
However, the contingency provisions of a maintenance plan are 
considered to be an enforceable part of the SIP and should ensure that 
contingency measures are adopted expeditiously once they are triggered. 
The maintenance plan should clearly identify the measures to be 
adopted, include a schedule and procedure for adoption and 
implementation of the measures, and contain a specific timeline for 
action by the state. In addition, the state should identify the 
specific indicators or triggers that will

[[Page 56854]]

be used to determine when the contingency measures need to be 
implemented.
    The District has adopted a contingency plan to address possible 
future PM10 air quality problems in the Indian Wells Valley 
planning area. The contingency plan is included in section V of the 
Plan.
    As noted by the District in the Indian Wells Second Maintenance 
Plan, contingency provisions are typically implemented when air quality 
deteriorates beyond a specified level, such as a certain number of 
exceedances of the standard or a violation of the standard. In this 
case, the contingency provisions will be triggered when the number of 
exceedances at the monitor, averaged over three years, is greater than 
1.05. However, the contingency plan also includes a screening process 
that allows the District and CARB, subject to EPA review, to exclude 
exceedances from the trigger calculation if the agencies collectively 
determine that information developed by the District is sufficient to 
support exclusion. The purpose of the screening process is to 
differentiate between exceedances that are not within the District or 
State control (i.e., exceedances that occur despite the implementation 
of reasonable measures), and exceedances that are within the District's 
or State's control and should be included in the trigger calculation. 
It is important to note that, should the District or State exclude an 
exceedance from the contingency trigger calculation using this process, 
it would not constitute the EPA's concurrence that the exceedance was 
caused by an exceptional event. The exceedance will therefore continue 
to be included in design value calculations for the Indian Wells Valley 
planning area unless CARB, following opportunity for public comment, 
submits a request for the EPA to concur on the exceedance as an 
exceptional event pursuant to 40 CFR 50.14, and the EPA reviews the 
submittal and formally concurs.
    Under the contingency trigger screening process, within 60 days of 
the end of each calendar quarter, the District will complete the 
following: Provide a list of exceedances that occurred during that 
previous quarter to CARB, identify those exceedances that the District 
believes to be exceedances that are not within the District's or 
State's control, and flag the relevant data and provide an initial 
description in AQS. The State then has 60 days to review the 
information, during which time it may request additional information 
from the District to supplement the District's analysis. Following 
CARB's review, CARB will transmit the information to the EPA, including 
information for those exceedances the District believes should be 
excluded from the contingency plan trigger calculation.
    The Indian Wells Second Maintenance Plan anticipates that the EPA 
will review the submitted information, notify the District if the 
submitted information is insufficient to support exclusion from the 
contingency plan trigger calculation, include such exceedances in 
calculating the trigger for the contingency plan, and notify the 
District if the contingency plan has been triggered. The EPA intends to 
notify the District, within 60 days of receipt, whether submitted 
information is sufficient or insufficient to support the exclusion of a 
given exceedance from the contingency plan trigger calculation and to 
take the other actions described in the plan. If the submitted 
information is not sufficient, the EPA will include the exceedance in 
the calculation to determine if the contingency plan has been 
triggered. If the State or District subsequently provide additional 
information sufficient to support the conclusion that the exceedance 
meets the criteria for exclusion from the trigger calculation, the EPA 
will notify the District that the calculation will be adjusted.
    Under the contingency plan, if the EPA determines that contingency 
provisions have been triggered, (i.e., the number of exceedances, 
averaged over three years, is greater than 1.05 excluding those 
exceedances identified through the screening process), EKAPCD commits 
to the following steps:

    (1) Within six months of EPA notification, EKAPCD will complete 
an analysis of the exceedances and available contingency measures. 
During this time, the District will determine the possible cause of 
the exceedances and will consult with community and local industry 
members to determine if any voluntary or incentive measures could be 
implemented to reduce the magnitude of or eliminate the source of 
emissions. If voluntary and incentive-based measures do not 
adequately address the problem, the EKAPCD will evaluate its 
fugitive dust rules (402, 402.2, and 419), or other rules as 
appropriate, to determine where such rules could be improved or 
expanded to achieve additional emissions reductions. The measures 
that EKAPCD would consider and analyze include but are not limited 
to those listed in Table 5.
    (2) Within 12 months of completing its analysis, the District 
will adopt and implement the new contingency measures.

  Table 5--Emissions Sources and Associated Control Measures; Rules To
                     Revise if Contingency Triggered
------------------------------------------------------------------------
                        Emissions source                           Rule
------------------------------------------------------------------------
Construction and Earthmoving Activities........................      402
Storage Piles/Bulk Materials...................................      402
Track-out/Carry-out............................................      402
Agricultural Operations........................................    402.2
Paved and Unpaved Roads........................................    402 &
                                                                   402.2
Nuisance.......................................................      419
Open Areas.....................................................    402 &
                                                                     419
------------------------------------------------------------------------
Source: Indian Wells Second Maintenance Plan, Table 7.

    Based on our review of the Indian Wells Second Maintenance Plan, as 
summarized herein, we propose to find that the contingency provisions 
of the Plan clearly identify specific contingency measures, contain a 
triggering mechanism to determine when contingency measures are needed, 
contain a description of the process of recommending and implementing 
contingency measures, and contain specific and appropriate timelines 
for action. We also propose to find that the contingency trigger 
screening process, including the associated EPA review, is reasonably 
designed to distinguish between exceedances that are not within the 
District or State control, and exceedances that are within the 
District's or State's control and for which new or tightened control 
measures might be effective. Thus, we propose to conclude that the 
contingency plan in the Indian Wells Second Maintenance Plan is 
adequate to ensure correction of any violation of the PM10 
NAAQS that occurs after redesignation, as required by section 175A(d) 
of the CAA.

E. Motor Vehicle Emissions Budgets for Transportation Conformity

    Section 176(c) of the CAA requires federal actions in nonattainment 
and maintenance areas to conform to the SIP's goals of eliminating or 
reducing the severity and number of violations of the NAAQS and 
achieving expeditious attainment of the standards. Conformity to the 
SIP's goals means that such actions will not: (1) Cause or contribute 
to violations of the NAAQS, (2) worsen the severity of an existing 
violation, or (3) delay timely attainment of any NAAQS or any interim 
milestone.
    Actions involving Federal Highway Administration (FHWA) or Federal 
Transit Administration (FTA) funding or approval are subject to the 
EPA's transportation conformity rule, codified

[[Page 56855]]

at 40 CFR part 93, subpart A. Under this rule, metropolitan planning 
organizations (MPOs) in nonattainment and maintenance areas coordinate 
with state and local air quality and transportation agencies, the EPA, 
FHWA, and FTA to demonstrate that an area's regional transportation 
plans and transportation improvement programs conform to the applicable 
SIP. This demonstration is typically done by showing that estimated 
emissions from existing and planned highway and transit systems are 
less than or equal to the motor vehicle emissions budgets (``budgets'') 
contained in submitted or approved control strategy SIPs and 
maintenance plans.\42\
---------------------------------------------------------------------------

    \42\ Control strategy SIPs refer to reasonable further progress 
and attainment demonstration SIPs. 40 CFR 93.101.
---------------------------------------------------------------------------

    These control strategy SIPs and maintenance plans typically set 
budgets for criteria pollutants and/or their precursors to address 
pollution from cars and trucks. Budgets are generally established for 
specific years and specific pollutants or precursors. PM10 
maintenance plan submittals should identify budgets for transportation-
related PM10 emissions in the last year of the maintenance 
period.\43\
---------------------------------------------------------------------------

    \43\ Transportation-related emissions of VOC and NOX 
must also be specified in PM10 maintenance plans if the 
EPA or the state find 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 MPO and the U.S. Department of 
Transportation (DOT), or the applicable SIP (or SIP revision 
submission) establishes an approved (or adequate) budget for such 
emissions as part of the reasonable further progress, attainment, or 
maintenance strategy. 40 CFR 93.102(b)(2)(iii). Neither of these 
conditions apply to the Indian Wells PM10 maintenance 
area.
---------------------------------------------------------------------------

    For budgets in a maintenance plan to be approvable, they must meet, 
at a minimum, the EPA's adequacy criteria.\44\ To meet these 
requirements, the budgets must be consistent, when considered with 
emissions from all other sources, with maintenance of the NAAQS and 
reflect all the motor vehicle control measures relied upon for the 
maintenance demonstration.
---------------------------------------------------------------------------

    \44\ 40 CFR 93.118(e)(4).
---------------------------------------------------------------------------

    The EPA's process for determining adequacy of a budget consists of 
three basic steps: (1) Notifying the public of a SIP submittal, (2) 
providing the public the opportunity to comment on the budget during a 
public comment period, and (3) making a finding of adequacy or 
inadequacy. The process for determining the adequacy of a submitted 
budget is codified at 40 CFR 93.118(f). The EPA can notify the public 
by either posting an announcement that the EPA has received SIP budgets 
on the EPA's adequacy website,\45\ or via a Federal Register notice of 
proposed rulemaking when the EPA reviews the adequacy of a maintenance 
plan budget simultaneously with its review and action on the SIP 
submittal itself.\46\
---------------------------------------------------------------------------

    \45\ 40 CFR 93.118(f)(1).
    \46\ 40 CFR 93.118(f)(2).
---------------------------------------------------------------------------

    The Indian Wells Second Maintenance Plan includes budgets for 
direct PM10 for the last year of the maintenance Plan (2025) 
and an interim year (2020). The applicable source categories included 
in the budgets include vehicle emissions (including exhaust, brake 
wear, and tire wear), entrained dust from vehicle travel over paved and 
unpaved roads, and road construction dust. To develop the budgets, the 
District also rounded up the motor vehicle emissions estimates to the 
nearest tenth of a ton and included a safety margin.\47\ The 2020 and 
2025 annual average day conformity budgets for PM10 are 
provided in Table 6.
---------------------------------------------------------------------------

    \47\ The text of the Plan identifies the safety margin for VOC 
in 2020 only. However, Table 5 in the Plan indicates that the safety 
margin is for PM10 emissions. CARB confirmed via email 
that the reference to VOC in the text is a typographic error and 
that the safety margin is for PM10 emissions. See email 
dated February 4, 2021, from Nesamani Kalandiyur, CARB, to Karina 
O'Connor, EPA Region IX, Subject: ``RE: Question Regarding Indian 
Wells 2nd Maintenance Plan.''

 Table 6--Transportation Conformity Budgets for the Indian Wells Valley
                                PM10 Area
                       [PM10 tpd, annual average]
------------------------------------------------------------------------
             Source category                   2020            2025
------------------------------------------------------------------------
Vehicular Exhaust, Tire, and Brake Wear             0.04            0.04
 \a\....................................
SAFE Rule Adjustment....................            0.00            0.00
Re-Entrained Paved Road Dust............            0.11            0.12
Re-Entrained Unpaved Road Dust..........            0.13            0.13
Road Construction Dust..................            0.03            0.10
Safety Margin...........................             0.0            0.10
Total \b\...............................            0.31            0.49
Motor Vehicle Emissions Budget \c\......            0.40            0.50
------------------------------------------------------------------------
\a\ This reflects the adjustment factor for the Safer Affordable Fuel-
  Efficient (SAFE) Vehicle Rule part one (84 FR 51310, September 27,
  2019) using EMFAC2017.
\b\ Values from California Emissions Projection Analysis Model v1.00 may
  not add up due to rounding.
\c\ Motor vehicle emissions budgets calculated are rounded up to the
  nearest tenth of a tpd.
Source: Indian Wells Second Maintenance Plan, Table 5.

    CARB developed the on-road mobile portion of the emissions 
inventory for the maintenance plan using California's on-road mobile 
source emissions projection model, EMFAC2017, and vehicle activity data 
provided by the KCOG from its 2019 Federal Transportation Improvement 
Program, as amended July 2019. The EMFAC2017 model calculated tire 
wear, brake wear, and exhaust emissions. Paved road dust emissions were 
estimated using AP-42 with California-specific silt loading data.\48\ 
The unpaved road dust emissions were estimated using CARB's methodology 
7.10, updated in 2012 for non-farm roads. The road construction dust 
emissions were estimated based on road miles constructed according to 
data from KCOG.
---------------------------------------------------------------------------

    \48\ AP-42 is an EPA document that includes a compilation of 
emissions factors.
---------------------------------------------------------------------------

    As discussed in the March 10, 2006 final transportation conformity 
rulemaking, unlike the exception for paved and unpaved road dust 
emissions in PM2.5 analyses in 40 CFR 93.102(b)(3), the 
conformity rule does not include an exception for PM10 for 
paved and unpaved road dust emissions to be determined significant. The 
EPA intends for road dust emissions to be included in all conformity 
analyses of direct PM10 emissions because fugitive dust from 
roadways and other sources dominate PM10 emissions 
inventories. The budgets in the Indian Wells Second Maintenance Plan, 
therefore, include paved and unpaved road emissions.
    Regional PM10 emissions analyses for transportation 
conformity

[[Page 56856]]

determinations in PM10 nonattainment and maintenance areas 
must account for highway and transit project construction-related 
fugitive PM10 emissions if the control strategy or 
maintenance plan identifies such emissions as a contributor to the air 
quality problem, but it is not required if such emissions are not 
identified as a contributor to the air quality problem.\49\ Emissions 
estimates developed for the Indian Wells Second Maintenance Plan show 
that fugitive PM10 emissions from highway and transit 
project construction represent approximately 1.2 percent and 4.0 
percent of the total annual-average daily PM10 emissions in 
2020 and 2025, respectively.\50\ Based on these emissions estimates, 
the Indian Wells Second Maintenance Plan concludes that fugitive 
PM10 emissions from highways and transit project 
construction are significant and must be accounted for in regional 
emissions analyses for transportation conformity determinations made 
for the Indian Wells Valley planning area. Consequently, the budgets in 
the Indian Wells Second Maintenance Plan reflect highway and transit 
project construction-related fugitive dust.
---------------------------------------------------------------------------

    \49\ 40 CFR 93.122(e).
    \50\ Indian Wells Second Maintenance Plan, Table 4.
---------------------------------------------------------------------------

    We evaluated the budgets against our adequacy criteria in 40 CFR 
93.118(e)(4) and (5) as part of our review of the budget's 
approvability and expect to complete the adequacy review of the budgets 
concurrent with our final action on the Indian Wells Second Maintenance 
Plan. The EPA is not required under its transportation conformity rule 
to find budgets adequate prior to proposing approval of them.\51\ In 
this document, the EPA is announcing that the adequacy process for 
these budgets begins, and the public has 30 days to comment on their 
adequacy, per the transportation conformity rule at 40 CFR 
93.118(f)(2)(i) and (ii).
---------------------------------------------------------------------------

    \51\ Under the transportation conformity rule, the EPA may 
review the adequacy of submitted budgets simultaneously with the 
EPA's approval or disapproval of the submitted control strategy or 
maintenance plan. 40 CFR 93.118(f)(2).
---------------------------------------------------------------------------

    As documented in the separate memorandum included in the docket for 
this rulemaking, we preliminarily conclude that the budgets in the 
Indian Wells Second Maintenance Plan meet each adequacy criterion.\52\ 
While adequacy and approval are two separate actions, reviewing the 
budgets in terms of the adequacy criteria informs the EPA's decision to 
propose to approve the budgets. We have completed our detailed review 
of the Indian Wells Second Maintenance Plan and are proposing herein to 
approve the Plan including the demonstration of maintenance of the 
PM10 NAAQS in the area through the year 2025. We have also 
reviewed the budgets in the Indian Wells Second Maintenance Plan and 
found that they are consistent with the maintenance demonstration for 
which we are proposing approval, are clearly identified and precisely 
quantified, are based on control measures that have already been 
adopted and implemented, and meet all other applicable statutory and 
regulatory requirements including the adequacy criteria in 40 CFR 
93.118(e)(4) and (5). For these reasons, the EPA proposes to approve 
the 2020 and 2025 motor vehicle emissions budgets in the Indian Wells 
Second Maintenance Plan. At the point when we either finalize the 
adequacy process or approve the budgets as proposed (whichever occurs 
first, although they could also occur concurrently),\53\ the budgets 
must be used by KCOG (i.e., the MPO for this area) for transportation 
conformity determinations for the Indian Wells Valley planning area.
---------------------------------------------------------------------------

    \52\ Memorandum dated February 4, 2021, from Karina O'Connor, 
EPA, to Rulemaking Docket ID EPA-R09-OAR-0549, Subject: ``Adequacy 
Documentation for Plan Motor Vehicle Emissions Budgets in the Indian 
Wells Second PM10 Maintenance Plan.''
    \53\ 40 CFR 93.118(f)(2)(iii).
---------------------------------------------------------------------------

V. Proposed Action and Request for Public Comment

    Under CAA section 110(k)(3), and for the reasons set forth in this 
document, the EPA is proposing to approve the Indian Wells Second 
Maintenance Plan submitted by CARB by letter on July 30, 2020, as a 
revision to the California SIP. We are proposing to approve the 
maintenance demonstration and contingency provisions as meeting all of 
the applicable requirements for maintenance plans and related 
contingency provisions in CAA section 175A, and the motor vehicle 
emissions budgets for 2020 and 2025 (shown in Table 6) for 
transportation conformity purposes because we find they meet all 
applicable criteria for such budgets including the adequacy criteria 
under 40 CFR 93.118(e).
    We are soliciting comments on these proposed actions. We will 
accept comments from the public for 30 days following publication of 
this proposal in the Federal Register and will consider any relevant 
comments before taking final action.

VI. Statutory and Executive Order Reviews

    Under the CAA, the Administrator is required to approve a SIP 
submission that complies with the provisions of the Act and applicable 
federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in 
reviewing SIP submissions, the EPA's role is to approve state choices, 
provided that they meet the criteria of the CAA. Accordingly, this 
proposed action merely proposes to approve a state plan as meeting 
federal requirements and does not impose additional requirements beyond 
those imposed by state law. For that reason, this proposed action:
     Is not a ``significant regulatory action'' subject to 
review by the Office of Management and Budget under Executive Orders 
12866 (58 FR 51735, October 4, 1993) and 13563 (76 FR 3821, January 21, 
2011);
     Does not impose an information collection burden under the 
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
     Is certified as not having a significant economic impact 
on a substantial number of small entities under the Regulatory 
Flexibility Act (5 U.S.C. 601 et seq.);
     Does not contain any unfunded mandate or significantly or 
uniquely affect small governments, as described in the Unfunded 
Mandates Reform Act of 1995 (Pub. L. 104-4);
     Does not have federalism implications as specified in 
Executive Order 13132 (64 FR 43255, August 10, 1999);
     Is not an economically significant regulatory action based 
on health or safety risks subject to Executive Order 13045 (62 FR 
19885, April 23, 1997);
     Is not a significant regulatory action subject to 
Executive Order 13211 (66 FR 28355, May 22, 2001);
     Is not subject to requirements of section 12(d) of the 
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 
note) because application of those requirements would be inconsistent 
with the CAA; and
     Does not provide the EPA with the discretionary authority 
to address disproportionate human health or environmental effects with 
practical, appropriate, and legally permissible methods, under 
Executive Order 12898 (59 FR 7629, February 16, 1994).
    In addition, there are no areas of Indian country within the Indian 
Wells Valley planning area, and the State plan for which the EPA is 
proposing approval does not apply on any Indian reservation land or in 
any other area where the EPA or an Indian tribe has

[[Page 56857]]

demonstrated that a tribe has jurisdiction. In those areas of Indian 
country, this proposed action does not have tribal implications and 
will not impose substantial direct costs on tribal governments or 
preempt tribal law as specified by Executive Order 13175 (65 FR 67249, 
November 9, 2000).

List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Incorporation by 
reference, Intergovernmental relations, Nitrogen dioxide, Particulate 
matter, Reporting and recordkeeping requirements, Sulfur dioxide, 
Volatile organic compounds.

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

    Dated: October 5, 2021.
Deborah Jordan,
Acting Regional Administrator, Region IX.
[FR Doc. 2021-22168 Filed 10-12-21; 8:45 am]
BILLING CODE 6560-50-P