Air Plan Approval; Nevada; Revisions to Clark County Ozone Maintenance Plan, 33035-33045 [2019-14630]
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continue to make, these materials
generally available through https://
www.regulations.gov and at the EPA
Region III Office (please contact the
person identified in the ‘‘For Further
Information Contact’’ section of this
preamble for more information).
V. Statutory and Executive Order
Reviews
Under the CAA, the Administrator is
required to approve a SIP submission
that complies with the provisions of the
CAA and applicable Federal regulations.
42 U.S.C. 7410(k); 40 CFR 52.02(a).
Thus, in reviewing SIP submissions,
EPA’s role is to approve state choices,
provided that they meet the criteria of
the CAA. Accordingly, this action
merely approves state law as meeting
Federal requirements and does not
impose additional requirements beyond
those imposed by state law. For that
reason, this proposed action:
• Is not a ‘‘significant regulatory
action’’ subject to review by the Office
of Management and Budget under
Executive Orders 12866 (58 FR 51735,
October 4, 1993) and 13563 (76 FR 3821,
January 21, 2011);
• Is not an Executive Order 13771 (82
FR 9339, February 2, 2017) regulatory
action because SIP approvals are
exempted under Executive Order 12866.
• 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 EPA with the
discretionary authority to address, as
appropriate, disproportionate human
health or environmental effects, using
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practicable and legally permissible
methods, under Executive Order 12898
(59 FR 7629, February 16, 1994).
In addition, this proposed rule, the
District’s 2008 8-hour ozone RACT SIP
revision does not have tribal
implications as specified by Executive
Order 13175 (65 FR 67249, November 9,
2000), because the SIP is not approved
to apply in Indian country located in the
District, and EPA notes that it will not
impose substantial direct costs on tribal
governments or preempt tribal law.
List of Subjects in 40 CFR Part 52
Environmental protection, Air
pollution control, Incorporation by
reference, Nitrogen dioxide, Ozone,
Reporting and recordkeeping
requirements, Volatile organic
compounds.
Authority: 42 U.S.C. 7401 et seq.
Dated: June 26, 2019.
Cosmo Servidio,
Regional Administrator, Region III.
[FR Doc. 2019–14628 Filed 7–10–19; 8:45 am]
BILLING CODE 6560–50–P
ENVIRONMENTAL PROTECTION
AGENCY
40 CFR Part 52
[EPA–R09–OAR–2019–0365; FRL–9996–40–
Region 9]
Air Plan Approval; Nevada; Revisions
to Clark County Ozone Maintenance
Plan
Environmental Protection
Agency (EPA).
ACTION: Proposed rule.
AGENCY:
The Environmental Protection
Agency (EPA) is proposing to
conditionally approve a revision to the
State of Nevada’s State Implementation
Plan (SIP) for Clark County. The
revision consists of an update to certain
elements of the maintenance plan for
the Clark County air quality planning
area for the 1997 8-hour ozone national
ambient air quality standards (NAAQS
or ‘‘standards’’), including the emissions
inventories, maintenance
demonstration, and motor vehicle
emissions budgets. The EPA is
proposing to conditionally approve the
SIP revision because the Clark County
ozone SIP, as revised, continues to
provide for maintenance of the 1997
ozone NAAQS and, upon fulfillment of
certain commitments, will not interfere
with attainment or reasonable further
progress of the other NAAQS, and the
budgets meet the applicable
transportation conformity requirements.
SUMMARY:
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The proposed approval is conditional
because it is based on commitments to
submit a SIP revision to reduce the
safety margin allocations for the budgets
within one year of final conditional
approval.
DATES: Comments must be received on
or before August 12, 2019.
ADDRESSES: Submit your comments,
identified by Docket ID No. EPA–R09–
OAR–2019–0365, 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.
FOR FURTHER INFORMATION CONTACT:
Karina O’Connor, Air Planning Office
(AIR–2), EPA Region IX, 75 Hawthorne
Street, San Francisco, CA 94105; By
phone: (775) 434–8176 or by email at
oconnor.karina@epa.gov.
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. What action is the EPA proposing?
II. Background
A. NAAQS, SIPs, Designations, and
Transportation Conformity
B. 1997 Ozone NAAQS and Clark County
C. 2008 Ozone NAAQS and Clark County
D. 2015 Ozone NAAQS and Clark County
E. The MOVES Emission Model
III. What did the State submit?
IV. Procedural Requirements for Adoption
and Submittal of SIP Revisions
V. The EPA’s Evaluation of the 2018 Ozone
Maintenance Plan Revision
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A. Revised Attainment Inventory
B. Revised Maintenance Demonstration
C. Revised Motor Vehicle Emissions
Budgets
D. CAA Section 110(l) Evaluation
VI. Proposed Action and Request for Public
Comment
VII. Statutory and Executive Order Reviews
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I. What action is the EPA proposing?
Under section 110(k) of the Clean Air
Act (‘‘Act’’ or CAA), the EPA is required
to take action by approving,
disapproving, or conditionally
approving, in whole or in part, SIPs and
SIP revisions submitted by the states. In
today’s action, the EPA is proposing to
conditionally approve a SIP revision
titled ‘‘Revision to Motor Vehicle
Emissions Budgets in Ozone
Redesignation Request and Maintenance
Plan: Clark County, Nevada’’ (October
2018) (herein, referred to as the ‘‘2018
Ozone Maintenance Plan Revision’’),
submitted by the Nevada Division of
Environmental Protection (NDEP) on
October 31, 2018. The 2018 Ozone
Maintenance Plan Revision updates
certain elements of the maintenance
plan for Clark County for the 1997
ozone NAAQS, including the attainment
inventory, the maintenance plan, and
the motor vehicle emissions budgets
(‘‘budgets’’ or MVEBs). The budgets
were updated using the EPA’s MOtor
Vehicle Emission Simulator emission
model released in 2014 (MOVES2014a).
If the EPA takes final action to
conditionally approve the SIP revision,
the updated budgets will replace Clark
County’s existing budgets for the 1997
ozone NAAQS. At that time, the
previously-approved budgets would no
longer be applicable for transportation
conformity purposes, and the revised
budgets would need to be used
beginning on the publication date of the
EPA’s final conditional approval in the
Federal Register.1 The proposed
conditional approval is based on
commitments from NDEP and the Clark
County Department of Air Quality
(DAQ) to submit a SIP revision within
one year of final conditional approval.2
The purpose of the future SIP revision
is to reduce the safety margin
allocations to the budgets to ensure that
the 2018 Ozone Maintenance Plan
Revision, as revised to reduce the safety
margin allocations, will not interfere
with reasonable further progress or
1 40
CFR 93.118(f)(2)(v).
from Jodi Bechtel, Assistant Director,
Clark County DAQ, to Greg Lovato, Administrator,
NDEP, dated June 14, 2019; and letter from Greg
Lovato, Administrator, NDEP, to Elizabeth Adams,
Director, Air Division, EPA Region IX, dated June
21, 2019.
2 Letter
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attainment of the 2008 and 2015 ozone
NAAQS.
II. Background
A. NAAQS, SIPs, Designations, and
Transportation Conformity
Under section 109 of the CAA, the
EPA promulgates NAAQS for pervasive
air pollutants, such as ozone. The
NAAQS are concentration levels that,
the attainment and maintenance of
which, the EPA has determined to be
requisite to protect public health and
welfare. Once the EPA has established
a NAAQS or revised a NAAQS, section
110 of the CAA requires states to adopt
and submit to the EPA a plan, referred
to as the SIP, that provides for the
implementation, maintenance, and
enforcement of such NAAQS. As noted
previously, the EPA is required to take
action to approve, disapprove, or
conditionally approve SIPs and SIP
revisions under CAA section 110(k).
Under CAA section 107(d), the EPA
must designate all areas of the country
as attainment, nonattainment or
unclassifiable for new or revised
NAAQS. States with areas designated as
nonattainment must develop, adopt and
submit SIP revisions to provide for,
among other things, attainment as
expeditiously as practicable but no later
than certain dates and for reasonable
further progress (RFP) towards
attainment.3 Once a nonattainment area
has attained the NAAQS, the state may
request redesignation of the area from
nonattainment to attainment, and the
EPA grants such requests if the criteria
in CAA section 107(d)(3)(E) are met,
including the approval of a maintenance
plan (under CAA section 175A) that
demonstrates how the area will
maintain the NAAQS for at least 10
years after the redesignation. Such
former nonattainment areas that have
been redesignated to attainment are
referred to as ‘‘maintenance areas.’’
In the State of Nevada, NDEP is the
Governor’s designee for adoption and
submittal of SIPs and SIP revisions to
the EPA. NDEP is also responsible for
regulation of stationary sources and
development of local air quality plans
throughout much of the State of Nevada.
In Clark County, the Clark County DAQ
is responsible under state law for
regulation of most types of stationary
sources within the county and for
development of local air quality plans.
Once adopted by the Clark County
Board of County Commissioners, such
county plans are forwarded to NDEP for
adoption and submittal to the EPA as
revisions to the Nevada SIP.
3 See, generally, part D (‘‘Plan Requirements for
Nonattainment Areas’’) of Title I of the CAA.
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The emission control strategy SIP
revisions (e.g., RFP and attainment
demonstration SIP revisions) and
maintenance plans include budgets of
on-road mobile source emissions for
criteria pollutants and/or their
precursors to address pollution from
cars and trucks. The budgets are the
portions of the total allowable emissions
that are allocated to on-road vehicle use
that, together with emissions from other
sources in the area, will provide for
RFP, attainment or maintenance. The
budgets serve as a ceiling on emissions
from an area’s planned transportation
system.4
The CAA recognizes the connection
between air quality planning and
transportation planning in
nonattainment and maintenance areas
and includes specific provisions related
to adoption and approval of
transportation programs, plans, and
projects by Metropolitan Planning
Organizations (MPOs) and the U.S
Department of Transportation’s (DOT’s)
Federal Highway Administration
(FHWA) or Federal Transit
Administration (FTA). More
specifically, under section 176(c) of the
CAA, transportation plans,
Transportation Improvement Programs
(TIPs), and transportation projects must
‘‘conform’’ to (i.e., be consistent with)
the SIP before they can be adopted or
approved. Conformity to the SIP means
that transportation activities will not
cause new air quality violations, worsen
existing air quality violations, or delay
timely attainment of the NAAQS or
delay an interim milestone. The EPA’s
transportation conformity rule at 40 CFR
part 93, subpart A establishes the
criteria and procedures that MPOs and
DOT must use to determine whether
transportation activities conform to the
SIP. Transportation conformity applies
to areas that are designated
nonattainment and those former
nonattainment areas that have been
redesignated to attainment and have a
CAA section 175A maintenance plan
(‘‘maintenance areas’’), but does not
apply to areas designated as attainment
or unclassifiable.5
Under certain circumstances, MPOs
and DOT must determine conformity
based, in part, on a ‘‘budget test’’ that
involves a comparison between
estimates of regional on-road mobile
source emissions under a given
transportation plan or program with the
budgets.6 Before budgets can be used in
4 For more information about budgets, see the
preamble to the November 24, 1993, transportation
conformity rule (58 FR 62188).
5 CAA section 176(c)(5).
6 CAA section 176(c)(1) and 40 CFR 93.109 and
93.118.
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conformity determinations, however,
the EPA must affirmatively find the
budgets adequate.7 However, adequate
budgets do not supersede approved
budgets for the same CAA purpose. If
the submitted SIP budgets are meant to
replace budgets for the same purpose,
the EPA must approve the budgets, and
can affirm that they are adequate at the
same time. Once the EPA approves the
submitted budgets, they must be used
by state and federal agencies in
determining whether transportation
activities conform to the SIP as required
by section 176(c) of the CAA. The EPA’s
substantive criteria for determining the
adequacy of budgets are set out in 40
CFR 93.118(e)(4).
In Clark County, the area’s MPO, the
Regional Transportation Commission of
Southern Nevada (RTC) and DOT are
the relevant transportation agencies that
must use approved or adequate budgets
in determining the conformity of
transportation plans and TIPs within
Clark County.
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B. 1997 Ozone NAAQS and Clark
County
Ground-level ozone pollution is
formed from the reaction of volatile
organic compounds (VOC) and oxides of
nitrogen (NOX) in the presence of
sunlight. These two pollutants, referred
to as ozone precursors, are emitted by
many types of sources, including on-and
off-road motor vehicles and engines,
power plants and industrial facilities,
and smaller area sources such as lawn
and garden equipment and paints.
Scientific evidence indicates that
adverse public health effects occur
following exposure to ozone,
particularly in children and adults with
lung disease. Breathing air containing
ozone can reduce lung function and
inflame airways, which can increase
respiratory symptoms and aggravate
asthma or other lung diseases.8
As noted previously, the EPA
promulgates NAAQS for pervasive air
pollutants, such as ozone, under CAA
section 109. In 1997, the EPA revised
the ozone NAAQS to set the acceptable
level of ozone in the ambient air at 0.08
parts per million (ppm), averaged over
an 8-hour period (herein referred to as
the ‘‘1997 ozone NAAQS’’).9 In 2004,
7 The ‘‘adequacy’’ process is established in the
EPA’s transportation conformity rule to provide a
mechanism whereby budgets in a submitted SIP
revision that has undergone preliminary review by
the EPA can be used for transportation planning
purposes prior to final approval of the SIP revision.
8 ‘‘Fact Sheet—2008 Final Revisions to the
National Ambient Air Quality Standards for Ozone’’
dated March 2008.
9 62 FR 38856 (July 18, 1997) and 40 CFR 50.10.
Due to the number of significant figures in the level
of the standard, a computed 3-year average ozone
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the EPA designated and classified all
areas with respect to the 1997 ozone
NAAQS, and designated Clark County
as a ‘‘Subpart 1’’ nonattainment area for
the 1997 ozone NAAQS.10 Later that
year, the EPA reduced the geographic
extent of the ozone nonattainment area
to a portion of Clark County.11 In 2005,
we published a final rule that we would
treat the effective date of the partialcounty nonattainment area designation
the same as the designations for the rest
of the country, i.e., June 15, 2004.12
As a ‘‘Subpart 1’’ area, the Clark
County ozone nonattainment area was
subject to a number of requirements
including the requirement to
demonstrate attainment of the 1997
ozone NAAQS as expeditiously as
practicable, but no later than five years
from the date that the area was
designated nonattainment.13 In 2011,
the EPA determined that the Clark
County 8-hour ozone nonattainment
area had attained the 1997 8-hour ozone
NAAQS, based on complete, qualityassured, and certified ambient air
monitoring data that showed the area
monitored attainment of the 1997 ozone
NAAQS for the 2007–2009 monitoring
period.14
In 2011, in light of ambient
monitoring data showing that the Clark
County ozone nonattainment had
attained the 1997 ozone NAAQS, NDEP
submitted the ‘‘Ozone Redesignation
Request and Maintenance Plan, Clark
County, Nevada (March 2011)’’ (herein,
the ‘‘2011 Ozone Maintenance Plan’’) to
the EPA for approval as a revision to the
concentration of 0.085 ppm is the smallest value
that is greater than 0.08 ppm. 40 CFR part 51,
appendix I.
10 69 FR 23858 (April 30, 2004). The ‘‘Subpart 1’’
classification meant that the area was subject solely
to the general nonattainment area requirements
under subpart 1 of part D (of title I) of the CAA
rather than to the requirements under both subparts
1 and the ozone-specific requirements under
subpart 2. Several years later, in response to
litigation over the designations for the 1997 ozone
NAAQS, the EPA revised the classification of the
Clark County ozone nonattainment area from
‘‘Subpart 1’’ to ‘‘Subpart 2/Marginal.’’ 77 FR 28424
(May 14, 2012).
11 69 FR 55956 (September 17, 2004). The
boundaries of the Clark County ozone
nonattainment (now maintenance) area for the 1997
ozone NAAQS are defined in 40 CFR 81.329.
Specifically, the area is defined as: ‘‘That portion
of Clark County that lies in hydrographic areas
164A, 164B, 165, 166, 167, 212, 213, 214, 216, 217,
and 218, but excluding the Moapa River Indian
Reservation and the Fort Mojave Indian
Reservation.’’ The area includes a significant
portion of the unincorporated portions of central
and southern Clark County, as well as the cities of
Las Vegas, Henderson, North Las Vegas and Boulder
City. The hydrographic areas are illustrated in
Figure 1–1 of the Clark County Ozone Maintenance
Plan (March 2011).
12 70 FR 71612 (November 29, 2005).
13 CAA section 172(a)(2).
14 76 FR 17343 (March 29, 2011).
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Clark County portion of the Nevada SIP.
Prepared by the Clark County DAQ, the
2011 Ozone Maintenance Plan includes
the various elements found in most
maintenance plans, including an
attainment inventory, maintenance
demonstration, monitoring network,
verification of continued attainment,
contingency plan, and motor vehicle
emissions budgets.
For the 2011 Ozone Maintenance
Plan, Clark County DAQ selected 2008
as the year for the attainment inventory
of ozone precursors (i.e., VOC and
NOX), and demonstrated maintenance of
the 1997 ozone NAAQS through year
2022 by reference to emissions
inventories developed for future years
2015 and 2022 that showed that future
emissions of VOC and NOX would not
exceed the level of the corresponding
emissions of the attainment inventory.
The 2011 Ozone Maintenance Plan
established budgets for NOX and VOC
for years 2008, 2015 and 2022. The
budgets were derived from the on-road
motor vehicle emissions estimates
prepared using the EPA’s then-current
on-road vehicle emissions model,
MOBILE6.2, and the most recent vehicle
mix and activity data then available
from the RTC. In 2013, the EPA
approved the 2011 Ozone Maintenance
Plan and redesignated the Clark County
ozone nonattainment area to attainment
for the 1997 ozone NAAQS.15 The
subject of today’s proposed action is a
revision to the attainment inventory, the
maintenance demonstration and budgets
of the 2011 Ozone Maintenance Plan to
reflect updated emissions models,
vehicle mix and speed data, and
transportation activity projections. The
other elements of the 2011 Ozone
Maintenance Plan (monitoring network,
verification of continued attainment,
contingency plan) are not affected by
this action.
Through adoption of the 2011 Ozone
Maintenance Plan, Clark County DAQ
committed to maintaining an ambient
air quality monitoring network to verify
the continued attainment of the 1997
ozone NAAQS in the Clark County
ozone maintenance area.16 At the
present time, monitors operating at 10
monitoring sites continuously monitor
ambient concentrations of ozone within
the maintenance area. Since 2008, i.e.,
the year used for the attainment
inventory in the 2011 Ozone
Maintenance Plan, Clark County has
experienced a decrease in ambient
ozone concentrations. As shown in
Table 1, 8-hour ozone design values
have decreased from 0.082 ppm in 2008
15 78
FR 1149 (January 8, 2013).
Ozone Maintenance Plan, page 6–11.
16 2011
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Federal Register / Vol. 84, No. 133 / Thursday, July 11, 2019 / Proposed Rules
In 2015, the EPA issued a SIP
Requirements Rule (SRR) for the 2008
ozone NAAQS (‘‘2008 Ozone SRR’’) that
addressed implementation of the 2008
standards, including attainment dates,
requirements for emissions inventories,
attainment and reasonable further
progress (RFP) demonstrations, among
other SIP elements, as well as the
TABLE 1—EIGHT-HOUR OZONE DESIGN VALUES FOR THE CLARK transition from the 1997 ozone NAAQS
COUNTY
OZONE
MAINTENANCE to the 2008 ozone NAAQS and
associated anti-backsliding
AREA, 2008–2017
requirements.20 The 2008 Ozone SRR
revoked the 1997 ozone NAAQS
Design value
Year
effective April 6, 2015.
(ppm)
The EPA’s 2008 Ozone SRR was
2008 ......................................
0.082 challenged, and on February 16, 2018,
2009 ......................................
0.078 the U.S. Court of Appeals for the D.C.
2010 ......................................
0.076 Circuit (‘‘D.C. Circuit’’) published its
2011 ......................................
0.075 decision in South Coast Air Quality
2012 ......................................
0.076 Management District v. EPA (‘‘South
2013 ......................................
0.077 Coast II’’) vacating certain portions of
2014 ......................................
0.078 the 2008 Ozone SRR, but upholding the
2015 ......................................
0.075
EPA’s revocation of the 1997 ozone
2016 ......................................
0.075
NAAQS.21 The only aspect of the South
2017 ......................................
0.074
Coast II decision that affects this
Source: 2017 Ozone Design Values Report proposed action is the vacatur of the
at
https://www.epa.gov/air-trends/air-quality- elimination of transportation conformity
design-values#report. Note that design values
reported for a given year reflect data from that in areas that were maintenance areas for
year and the two previous years, e.g., the de- the 1997 ozone NAAQS at the time of
sign value for 2008 reflects data from 2006– revocation of the 1997 ozone NAAQS
2008.
and were designated as attainment for
the 2008 ozone NAAQS, which the
C. 2008 Ozone NAAQS and Clark
court referred to as ‘‘orphan
County
maintenance areas.’’ The Clark County
Meanwhile, in 2008, the EPA lowered 1997 ozone maintenance area is an
orphan maintenance area. The 2008
the ozone NAAQS to a level of 0.075
ozone SRR had provided that such areas
ppm, 8-hour average (herein, the ‘‘2008
are no longer required to determine
ozone NAAQS’’),18 and in 2012, the
transportation conformity for the 1997
EPA designated all of the hydrographic
ozone NAAQS after the 1997 ozone
areas within the State of Nevada as
NAAQS is revoked.22 The court,
‘‘Unclassifiable/Attainment’’ for the
however, held that transportation
2008 ozone NAAQS.19 Because all the
conformity continues to apply for the
hydrographic areas located entirely, or
1997 ozone NAAQS in orphan
partially, within Clark County were
designated as Unclassifiable/Attainment maintenance areas notwithstanding
revocation of the 1997 ozone NAAQS.
for the 2008 ozone NAAQS, no RFP or
Following the South Coast II decision,
attainment SIP revision was required for
the EPA issued guidance that addresses
any portion of the county, and the
how transportation conformity
transportation conformity requirements
determinations can be made for the
did not apply for that ozone NAAQS.
1997 ozone NAAQS in orphan
maintenance areas, such as the Clark
17 Under EPA regulations at 40 CFR 50.10 and
County ozone maintenance area.23 In
appendix I, the 1997 ozone NAAQS is attained at
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to 0.074 ppm in 2017.17 In more recent
years, the design value has remained
relatively steady, varying little from year
to year. Table 1 shows that Clark County
has maintained the 1997 ozone NAAQS
through the first 5 years (2013 through
2017) of the first maintenance period.
a site when the 3-year average of the annual fourthhighest daily maximum 8-hour average ozone
concentration is less than or equal to 0.08 ppm.
This 3-year average is referred to as the design
value. When the design value is less than or equal
to 0.084 ppm (based on the rounding convention in
40 CFR part 50, appendix I) at each monitoring site
within the area, then the area is meeting the 1997
ozone NAAQS. The highest design value among the
various ozone monitoring sites represents the
design value for the area.
18 73 FR 16436 (March 27, 2008) and 40 CFR
50.15.
19 77 FR 30088 (May 21, 2012). Hydrographic
areas are those that are shown on the State of
Nevada Division of Water Resources’ map titled
‘‘Water Resources and Inter-basin Flows’’
(September 1971).
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20 80 FR 12264 (March 6, 2015) and 40 CFR part
51, subpart AA.
21 South Coast Air Quality Management District v.
EPA, 882 F.3d 1138 (D.C. Cir. 2018) (‘‘South Coast
II’’). The term ‘‘South Coast II’’ is used in reference
to the 2018 court decision to distinguish it from a
decision published in 2006 also referred to as
‘‘South Coast.’’ The earlier decision involved a
challenge to the EPA’s Phase 1 implementation rule
for the 1997 ozone NAAQS. South Coast Air
Quality Management District v. EPA, 472 F.3d 882
(D.C. Cir. 2006).
22 80 FR 12264, 12284 (March 6, 2015).
23 EPA, Office of Transportation and Air Quality,
‘‘Transportation Conformity Guidance for the South
Coast II Court Decision,’’ November 2018, EPA–
420–B–18–050.
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the guidance document, the EPA
explains that transportation conformity
for transportation plans and TIPs for the
1997 ozone NAAQS can be
demonstrated without a regional
emissions analysis pursuant to 40 CFR
93.109(c).24 In the case of the Clark
County ozone maintenance area, while
the transportation conformity
requirement continues to apply for the
revoked 1997 ozone NAAQS, RTC and
DOT do not need to use the approved
MOBILE6.2-based budgets from the
2011 Ozone Maintenance Plan in a
conformity determination for the
revoked 1997 ozone NAAQS because a
regional emissions analysis is not
required for that determination.
D. 2015 Ozone NAAQS and Clark
County
In 2015, the EPA further lowered the
ozone NAAQS to 0.070 ppm, eight-hour
average (herein the ‘‘2015 ozone
NAAQS’’).25 In 2018, the EPA
designated the Las Vegas Valley portion
of Clark County as a ‘‘Marginal’’
nonattainment area for the 2015 ozone
NAAQS, effective August 3, 2018.26 The
Clark County nonattainment area for the
2015 ozone NAAQS is about half the
size of the Clark County maintenance
area for the 1997 ozone NAAQS and
includes only hydrographic area 212
(‘‘Las Vegas Valley’’).
The nonattainment area designation
for Las Vegas Valley for the 2015 ozone
NAAQS triggers the requirement for
certain SIP revisions, but, under CAA
section 176(c)(6) and 40 CFR 93.102(d),
transportation conformity does not
apply for the 2015 ozone NAAQS for
one year following the effective date of
the nonattainment area designation
(referred to as the ‘‘grace period’’), or, in
this case, does not apply until August 3,
2019. However, to avoid a conformity
‘‘lapse,’’ a MPO and DOT must make a
conformity determination for the 2015
ozone NAAQS for the applicable
transportation plan and program before
the end of the 1-year grace period.27
Under our Transportation Conformity
Rule, the latest approved or adequate
emission budgets for a previous ozone
24 Id.,
25 80
section 2.4.
FR 65292 (October 26, 2015) and 40 CFR
50.19.
26 83 FR 25776 (June 4, 2018).
27 EPA, Office of Air Quality Planning and
Standards, ‘‘Transportation Conformity Guidance
for 2015 Ozone NAAQS Nonattainment Areas,’’
June 2018, EPA–420–B–18–023. During a
conformity lapse, only certain projects can receive
additional federal funding or approvals to proceed
(i.e., exempt projects, project phases that were
approved before the lapse, and transportation
control measures (TCMs) in approved SIPs) until
the area has both a conforming transportation plan
and TIP.
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NAAQS (i.e., the 2008 or the 1997 ozone
NAAQS) must be used in conformity
determinations for the 2015 ozone
NAAQS until emission budgets are
established and found adequate or are
approved for the 2015 ozone NAAQS.28
Since the latest approved or adequate
emission budgets for a previous ozone
NAAQS for Clark County are the
approved MOBILE6.2-based budgets for
the 1997 8-hour ozone NAAQS, the RTC
and DOT must use these budgets for
conformity determinations for the 2015
ozone NAAQS until they are replaced
by updated budgets.
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E. The MOVES Emission Model
The MOVES model is the EPA’s tool
for estimating highway emissions. The
model is based on analyses of millions
of emission test results and considerable
advances in the agency’s understanding
of vehicle emissions. MOVES
incorporates the latest emissions data,
more sophisticated calculation
algorithms, increased user flexibility,
new software design, and significant
new capabilities relative to those
reflected in the EPA’s previous motor
vehicle emission factor model,
MOBILE6.2.
The EPA announced the release of
MOVES2010 on March 2, 2010 (75 FR
9411) and approved the use of
MOVES2010 in states other than
California for official SIP submissions to
the EPA and for regional emissions
analyses for transportation conformity
purposes. The EPA released
MOVES2014 on October 7, 2014 (79 FR
60343). MOVES2014 was a major
revision to MOVES2010 and
incorporated new emissions and fleet
data, emission standards and functional
improvements and features to the
model. The October 7, 2014 notice
approved the use of MOVES2014 in
states outside of California for official
SIP submissions to the EPA and for
regional emissions analyses for
transportation conformity purposes. In
addition, the notice started a two-year
grace period before MOVES2014 was
required to be used in new regional
emissions analyses for transportation
conformity determinations outside of
California. Since October 7, 2016,
MOVES2014 was required to be used for
new transportation conformity analyses
outside California. In November 2015,
the EPA released MOVES2014a, a minor
update to MOVES2014.29
28 40
CFR 93.109(c)(2).
August 2018, the EPA released
MOVES2014b to improve estimates of emissions
from nonroad mobile sources. MOBILE2014b does
not significantly change the on-road criteria
pollutant emissions results of MOVES2014 and is
29 In
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III. What did the State submit?
On October 31, 2018, NDEP submitted
the 2018 Ozone Maintenance Plan
Revision (for the 1997 ozone NAAQS) to
the EPA as a revision to the Clark
County portion of the Nevada SIP.30
Earlier that month, on October 16, 2018,
the Clark County Board of County
Commissioners adopted the 2018 Ozone
Maintenance Plan Revision and
forwarded the plan to NDEP for
adoption and submittal to the EPA.31
The 2018 Ozone Maintenance Plan
Revision updates certain elements of the
2011 Ozone Maintenance Plan for the
1997 ozone NAAQS, including the
emissions inventories, the maintenance
demonstration, and the MOBILE6.2derived budgets. The 2018 Ozone
Maintenance Plan Revision also
includes a technical support document
(appendix A of the plan revision) and
documentation of the public review
process (appendix B of the plan
revision). These updated inventories
and budgets in the 2018 Ozone
Maintenance Plan Revision are based on
MOVES2014a. The budgets for the 1997
ozone NAAQS were developed so that
the RTC would have updated budgets
available to use for transportation
conformity determinations with respect
to the 2015 ozone NAAQS until budgets
developed specifically for the 2015
ozone NAAQS are adopted and found to
be adequate or approved.
33039
submittal,32 Clark County DAQ
provided evidence of the required
public notice and opportunity for public
comment prior to the October 16, 2018
public hearing and adoption of the 2018
Ozone Maintenance Plan Revision. We
find, therefore, that the submittal of the
2018 Ozone Maintenance Plan Revision
meets the procedural requirements for
public notice and hearing in CAA
sections 110(a) and 110(l).
CAA section 110(k)(1)(B) requires the
EPA to determine whether a SIP
submittal is complete within 60 days of
receipt. This section also provides that
any plan submittal that the EPA has not
affirmatively determined to be complete
or incomplete will be deemed complete
by operation of law six months after the
date of submittal. The EPA’s SIP
completeness criteria are found in 40
CFR part 51, Appendix V. The 2018
Ozone Maintenance Plan Revision
submission, dated October 31, 2018,
became complete by operation of law on
April 30, 2019.
V. The EPA’s Evaluation of the 2018
Ozone Maintenance Plan Revision
IV. Procedural Requirements for
Adoption and Submittal of SIP
Revisions
CAA sections 110(a)(1) and (2) and
110(l) require a state to provide
reasonable public notice and
opportunity for public hearing prior to
the adoption and submittal of a SIP or
SIP revision. To meet this requirement,
every SIP submittal should include
evidence that adequate public notice
was given and an opportunity for a
public hearing was provided consistent
with the EPA’s implementing
regulations in 40 CFR 51.102.
The Clark County Board of County
Commissioners and NDEP have satisfied
applicable statutory and regulatory
requirements for reasonable public
notice and hearing prior to adoption and
submittal of the 2018 Ozone
Maintenance Plan Revision. In the
documentation included as part of the
October 31, 2018 SIP revision
The 2018 Ozone Maintenance Plan
Revision is not a required submittal but
has been submitted to establish revised
budgets reflecting the most recent
emissions models and planning
estimates and to thereby provide the
basis for RTC and DOT to make future
transportation conformity
determinations for transportation plans,
TIPs and projects with respect to the
2015 ozone NAAQS. We have reviewed
the 2018 Ozone Maintenance Plan
Revision for compliance with the
relevant requirements for maintenance
plans under CAA section 175A and for
noninterference under CAA section
110(l), and we have evaluated the
budgets in the 2018 Ozone Maintenance
Plan Revision for compliance with the
budget adequacy criteria in 40 CFR
93.118(e).
CAA 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: Attainment inventory,
maintenance demonstration, monitoring
network, verification of continued
not considered a new model for SIP and
transportation conformity purposes.
30 Letter, Greg Lovato, Administrator, NDEP to
Mike Stoker, Regional Administrator, EPA Region
IX, October 31, 2018 with enclosures.
31 Clark County Board of County Commissioners
Meeting, Meeting Summary, pages 14 and 15 (of
19), October 16, 2018.
32 Appendix B provides evidence that reasonable
notice of a public hearing was provided to the
public and that a public hearing was conducted
prior to adoption. Specifically, notice of the
availability of, and opening of a 30-day comment
period on, the draft ozone maintenance plan
revision was published on August 17, 2018 on the
County’s web page. No comments were submitted.
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attainment, and contingency plan.33 The
2018 Ozone Maintenance Plan Revision
updates two of the core elements of the
approved 2011 Ozone Maintenance Plan
for the 1997 ozone NAAQS, the
attainment inventory and maintenance
demonstration, and it also updates the
budgets.
CAA section 110(l) applies to all SIP
revisions, and under that section, the
EPA shall not approve any SIP revision
if the revision would interfere with any
applicable requirement concerning
attainment and reasonable further
progress or any other applicable
requirement of the CAA.
A. Revised Attainment Inventory
A maintenance plan for the 1997
ozone NAAQS must include an
inventory of emissions of ozone
precursors (VOC and NOX) in the area
to identify a level of emissions that are
sufficient to attain the 1997 ozone
NAAQS. 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 point sources, area
sources, nonroad mobile sources, and
on-road mobile sources, and must be
based on actual ‘‘ozone season data’’
(i.e., summertime) emissions.
Clark County DAQ selected 2008 as
the year for the attainment inventory in
the 2011 Ozone Maintenance Plan. The
attainment year inventory in the 2011
Ozone Maintenance Plan is
comprehensive in that it includes
estimates of summertime average
weekday VOC and NOX emissions from
all of the relevant source categories,
which the plan divides among point
sources,34 nonpoint sources,35
commercial aviation, federal aviation
(i.e., Nellis Air Force Base), on-road
mobile, nonroad mobile, and biogenic 36
sources.37 The 2018 Ozone Maintenance
Plan Revision includes a comprehensive
update to the 2008 attainment inventory
but, to the extent that the original
estimates (i.e., from 2011 Ozone
Maintenance Plan) are based on actual
reported emissions or activity levels for
year 2008, there is little change in the
related emissions estimate. Appendix A
to the 2018 Ozone Maintenance Plan
Revision contains source-specific
descriptions of emission calculation
procedures and sources of input data
used for the update.
Table 2 below compares the
attainment inventory from the 2011
Ozone Maintenance Plan with the
corresponding inventory from the 2018
Ozone Maintenance Plan Revision. As
shown in Table 2, the change in the
attainment inventory in the 2018 Ozone
Maintenance Revision is primarily due
to the update to the on-road mobile
source category and the nonpoint source
category.
TABLE 2—2008 ATTAINMENT INVENTORY
[Average summer weekday, tons/day]
NOX emissions
2011 Ozone
Maintenance
Plan
Source category
VOC emissions
2018 Ozone
Maintenance
Plan Revision
2011 Ozone
Maintenance
Plan
2018 Ozone
Maintenance
Plan Revision
Point source .....................................................................................................
Nonpoint source ...............................................................................................
Commercial aviation ........................................................................................
Federal aviation ...............................................................................................
On-road mobile ................................................................................................
Nonroad mobile ...............................................................................................
Biogenic ...........................................................................................................
28.73
5.41
11.41
1.27
68.46
43.28
5.00
28.97
6.6
11.41
1.27
89.50
40.63
5.00
1.32
57.07
2.60
0.79
65.08
42.91
132.00
1.50
67.56
2.60
0.79
42.46
42.07
132.00
Total ..........................................................................................................
163.56
183.38
301.77
288.98
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Sources: 2011 Ozone Maintenance Plan, tables 6–2 and 6–3; 2018 Ozone Maintenance Plan Revision, table 2–1.
With respect to on-road mobile source
emissions, Clark County DAQ updated
the emissions estimates using the
SMOKE–MOVES approach, which
incorporates MOVES2014a model
emission rates, Sparse Matrix Operator
Kernel Emissions (SMOKE) modeling,38
RTC travel demand modeling, and
Highway Performance Monitoring
System (HPMS) data from the Nevada
Department of Transportation.39 Clark
County DAQ selected the SMOKE–
MOVES approach to be consistent with
the EPA’s approach in developing the
National Emissions Inventory (NEI), as
well as with the EPA’s modeling
platform. This approach is also
consistent with the one used in Clark
County’s photochemical modeling
applications. In contrast, the 2011
Ozone Maintenance Plan’s on-road
mobile source emissions were estimated
using the CONCEPT MV emissions
model 40 and EPA’s MOBILE6.2
emissions factors. Generally, on-road
mobile source emissions estimates made
using MOVES2014a are higher for NOX
33 John Calcagni, Director, Air Quality
Management Division, EPA Office of Air Quality
Planning and Standards, memo titled ‘‘Procedures
for Processing Requests to Redesignate Areas to
Attainment,’’ September 4, 1992.
34 The 2018 Ozone Maintenance Plan Revision
uses the term, ‘‘point sources,’’ to refer to those
stationary source facilities that are required to
report their emissions to Clark County DAQ or
NDEP.
35 The 2018 Ozone Maintenance Plan Revision
uses the term, ‘‘nonpoint sources,’’ to refer to those
stationary and area sources that fall below point
source reporting levels and that are too numerous
or small to identify individually.
36 For the 2018 Ozone Maintenance Plan
Revision, ‘‘biogenic sources’’ include agricultural
crops; lawn grass; forests that produce isoprene,
monoterpene, alpha-pinene, and other VOC
emissions; and soils that generate trace amounts of
NOX.
37 See Table 2–1 in the 2018 Ozone Maintenance
Plan Revision.
38 SMOKE is an emission-generating and
processing model used in developing hourly
gridded emissions for photochemical modeling. The
EPA has integrated the MOVES model with the
SMOKE model with a set of integration software
tools that allows the MOVES emission rate model
to automatically run numerous iterations to
generate the most accurate modeling results. The
SMOKE–MOVES integrated approach takes
advantage of gridded hourly temperature and
humidity information from the Weather Research
and Forecasting (WRF) meteorology model used for
air quality modeling.
39 2018 Ozone Maintenance Plan Revision,
Appendix A, page A–2.
40 ‘‘CONCEPT’’ refers to the CONsolidated
Community Emissions Processor Tool (CONCEPT)
and ‘‘MV’’ refers to the motor vehicle module of the
CONCEPT model.
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and lower for VOC relative to those
made using MOBILE6.2. With respect to
nonpoint emissions sources, the change
in the 2008 emissions inventory is
largely due to the use of the SMOKE
model.
Based on our review of the emissions
inventories (and related documentation)
from the 2018 Ozone Maintenance Plan
Revision, we find that the inventories
for 2008 are comprehensive, that the
methods and assumptions used by Clark
County DAQ to update the 2008
emission inventory are reasonable, and
that the inventories reasonably estimate
actual ozone season emissions in the
2008 attainment year. Moreover, we find
that the 2008 emissions inventories in
the Ozone Maintenance Plan reflect the
latest planning assumptions and
emissions models available at the time
the 2018 Ozone Maintenance Plan
Revision was developed.
B. Revised Maintenance Demonstration
CAA section 175A(a) 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.’’
Generally, a state may demonstrate
maintenance of the ozone NAAQS by
either showing that future emissions
will not exceed the level of the
attainment inventory or by modeling to
show that the future mix of sources and
emissions rates will not cause a
violation of the NAAQS.
The 2018 Ozone Maintenance Plan
Revision uses the same method as the
2011 Ozone Maintenance Plan to
demonstrate continued maintenance of
the 1997 ozone NAAQS. The 2018
Ozone Maintenance Plan Revision
demonstrates maintenance through the
initial 10-year period after redesignation
by showing that emissions in 2015 and
2022 would be less than those in the
2008 attainment year.
To provide the basis for the
comparison of future emissions with the
updated attainment year (2008)
emissions, Clark County DAQ updated
the 2015 and 2022 emissions
inventories using the SMOKE–MOVES
approach for the on-road mobile sources
as described above for the update to the
2008 attainment year emissions
inventory and by incorporating more
recent emissions and travel demand
data. Tables 3 and 4 below compare the
NOX and VOC emissions inventories,
respectively, for 2015 and 2022 from the
2018 Ozone Maintenance Plan Revision
with the corresponding values from the
2011 Ozone Maintenance Plan.
TABLE 3—COMPARISON OF NOX INVENTORIES ASSOCIATED WITH APPROVED AND REVISED MAINTENANCE PLAN FOR THE
1997 OZONE NAAQS
[Tons per average summer weekday]
2011 Ozone
Maintenance Plan a
Source category
2015
2018 Ozone
Maintenance Plan Revision
2022
2015
Net
change b
2022
2015
2022
Stationary and Area (point and nonpoint)
On-road ....................................................
Nonroad (including aviation) ....................
Biogenic ...................................................
Emission Reduction Credits .....................
37
35
47
5
22
38
23
51
5
22
18
64
41
5
22
17
27
37
5
22
¥19
+29
¥6
0
0
¥21
+4
¥14
0
0
Totals c ..............................................
146
139
150
109
+4
¥30
a The
emissions shown for the approved ozone plan are from Table 6–3 of Clark County’s 2011 Ozone Maintenance Plan.
the net change, a negative number indicates a reduction in emissions, and a positive number indicates an increase in emissions relative
to the corresponding figure in the 2011 Ozone Maintenance Plan.
c Because of rounding conventions, totals may not reflect individual subcategories.
b For
TABLE 4—COMPARISON OF VOC INVENTORIES ASSOCIATED WITH APPROVED AND REVISED MAINTENANCE PLAN FOR THE
1997 OZONE NAAQS
[Tons per average summer weekday]
2015
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2018 Ozone
Maintenance Plan Revision
2011 Ozone
Maintenance Plan a
Source category
2022
2015
2022
Net
change b
2015
2022
Stationary and Area (point and nonpoint)
On-road ....................................................
Nonroad (including aviation) ....................
Biogenic ...................................................
Emission Reduction Credits .....................
68
45
36
132
<1
78
37
35
132
<1
63
33
35
132
<1
62
17
32
132
<1
¥5
¥12
¥1
0
0
¥16
¥20
¥3
0
0
Totals c ..............................................
282
282
263
244
¥19
¥38
a The
emissions shown for the approved ozone plan are from Table 6–3 of Clark County’s 2011 Ozone Maintenance Plan.
the net change, a negative number indicates a reduction in emissions, and a positive number indicates an increase in emissions relative
to the corresponding figure in the 2011 Ozone Maintenance Plan.
c Because of rounding conventions, totals may not reflect individual subcategories.
b For
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As shown in tables 3 and 4, total
emissions for 2015 and 2022 in the 2018
Ozone Maintenance Plan Revision are
lower than the corresponding emissions
in the 2011 Ozone Maintenance Plan
with the exception of a 4 tpd higher
estimate in 2015 for NOX. With respect
to the on-road mobile sources, the
update results in higher NOX emissions
but lower VOC emissions and reflects
primarily the differences in the
emissions rates calculated using
MOVES2014a relative to those
calculated using MOBILE6.2. The onroad mobile source emission estimates
in the 2018 Ozone Maintenance Plan
Revision reflect the most recent
published data concerning vehicle
registration data, vehicle miles traveled
(VMT) temporal distribution, VMT mix
profiles, vehicle speeds and travel
demand forecasts from RTC.41 The
higher estimates for NOX from on-road
mobile sources are offset by decreases in
the actual reported emissions for point
source emissions compared to their
projected emissions in the 2011 Ozone
Maintenance Plan (which includes the
shutdown of the Reid Gardner coal-fired
power plant). Other significant
differences include: (1) A reduction in
commercial aviation emissions because
the Sloan Regional Heliport and South
County Ivanpah Airport projects, which
had been assumed for the 2011 Ozone
Maintenance Plan, have not been
constructed and (2) reductions in
nonpoint source emission projection
factors.42
Based on our review of the methods,
assumptions, and data sources, as
described in Appendix A to the 2018
Ozone Maintenance Plan Revision, and
briefly summarized above, we find that
Clark County DAQ’s estimates for 2015
and 2022 for the various source
categories to be based on the best
available emissions models and data
sources, and thus to provide a
reasonable basis upon which to evaluate
whether the area will maintain the 1997
ozone NAAQS through 2022.
A state may choose to allocate all or
a portion of the safety margin 43 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).44 For the 2018 Ozone
Maintenance Plan Revision, Clark
County DAQ allocated 80 percent of the
safety margin for NOX and VOC in 2015
and 2022 to the projected on-road
emissions estimates for NOX and VOC.
Table 5 below summarizes the revised
maintenance demonstration (including
the safety margins) for the 1997 ozone
NAAQS. As shown in Table 5, the
revised emission estimates for NOX and
VOC in 2015 and 2022 (including the
safety margins) would remain below the
corresponding 2008 attainment levels
throughout the 10-year maintenance
period and thereby adequately
demonstrate maintenance through that
period.
TABLE 5—REVISED MAINTENANCE DEMONSTRATION FOR 1997 OZONE NAAQS
Emissions
(average summer weekday, tpd)
Source description
Attainment
(2008)
Projected Emissions—Excluding On-Road Mobile Sources ....................................................
Projected On-Road Mobile Source Emissions .........................................................................
Allocation of Portion of Safety Margin to On-Road ..................................................................
Total Emissions (with Safety Margins) .....................................................................................
Maintenance Demonstrated? ....................................................................................................
Motor Vehicle Emissions Budget (Projected On-Road Plus Safety Margin) ............................
2015
NOX
VOC
93.88
89.50
0
183.38
................
89.50
246.52
42.46
0
288.98
................
42.46
2022
NOX
VOC
NOX
VOC
85.81
64.30
26.62
176.73
Yes
90.92
229.82
33.04
20.90
283.76
Yes
53.94
81.71
27.02
59.72
168.45
Yes
86.74
227.06
17.12
35.84
280.02
Yes
52.96
Source: 2018 Ozone Maintenance Plan Revision, Tables 2–1, 2–2 and 3–1. Note: Maintenance is demonstrated where future emissions (with the safety margins)
are less than the corresponding attainment inventory emissions.
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C. Revised Motor Vehicle Emissions
Budgets
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 timely
attainment of the standards. Conformity
to the SIP’s goals means that such
actions will not: (1) Cause or contribute
to violations of a NAAQS, (2) worsen
the severity of an existing violation, or
(3) delay timely attainment of any
NAAQS or any interim milestone.
41 Key references used by Clark County DAQ
include Eastern Research Group, Inc.’s ‘‘Clark
County On-Road Vehicle Classification Study,’’
final report, June 29, 2018 and the Coordinating
Research Council, Inc.’s ‘‘Improvement of Default
Inputs for MOVES and SMOKE–MOVES,’’ final
report, February 2017.
42 Clark County projected emissions from 2014
NEI data with factors derived from the 2011–2023
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Under the transportation conformity
rule, MPOs in nonattainment and
maintenance areas coordinate with state
and local air quality and transportation
agencies, the EPA, the FHWA, and the
FTA to demonstrate that an area’s
regional transportation plans and TIPs
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 budgets contained in all control
strategy or maintenance SIPs. Budgets
are generally established for specific
years and specific pollutants or
precursors. Maintenance ozone plans
should identify budgets for on-road
emissions of ozone precursors (NOX and
VOC) in the area for the last year of the
maintenance period. Budgets may also
be specified for additional years during
the maintenance period.
For budgets to be approvable, they
must meet the EPA’s adequacy criteria
(40 CFR 93.118(e)(4) and (5)) and
comply with all pertinent SIP
requirements. With respect to
maintenance plans, to meet these
requirements, the budgets must be
consistent with the maintenance plan
and reflect all the motor vehicle control
measures contained in the maintenance
annual rate of change for all nonpoint sectors from
EPA’s 2011 Version 6 Air Emissions Modeling
Platform. Nonpoint source emissions in the 2011
Ozone Maintenance Plan were based on the 2008
NEI and higher growth correlated to population and
economic growth factors.
43 In this context, ‘‘safety margin’’ means the
amount by which the total projected emissions from
all sources of a given pollutant are less than the
total emissions that would satisfy the applicable
requirements for reasonable further progress,
attainment or maintenance. With respect to the
2018 Ozone Maintenance Plan Revision, the safety
margin is the difference between the projected
emissions in 2015 and 2022 of NOX and VOC and
the actual emissions of NOX and VOC in the 2008
attainment year.
44 See 40 CFR 93.124(a).
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demonstration.45 The EPA’s process for
determining adequacy of a budget
consists of three basic steps: (1)
Providing public notification of a SIP
submission; (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.46 We will complete the
adequacy review of the budgets in the
2018 Ozone Maintenance Plan Revision
concurrent with our final action on the
2018 Ozone Maintenance Plan Revision.
The EPA is not required under its
transportation conformity rule to find
budgets adequate prior to proposing
approval of them.47
The 2018 Ozone Maintenance Plan
Revision includes revised budgets for
VOC and NOX for years 2008, 2015 and
the last year of the initial maintenance
period, i.e., 2022. The revised budgets
from the 2018 Ozone Maintenance Plan
Revision are shown in Table 6 below
and compared with the corresponding
budgets from the approved 2011 Ozone
Maintenance Plan. As noted previously,
Clark County DAQ developed the
revised budgets using the latest
emissions model (MOVES2014a)
available at the time the 2018 Ozone
Maintenance Plan Revision was being
33043
developed, and the most recent travel
activity projections provided by the
NDOT and RTC. As such, we find that
the revised budgets reflect the most
recent planning forecasts and are based
on the most recent emission factor data
and approved calculation methods.
Clark County DAQ included 80% of the
safety margin in the budgets. In this
context, the term ‘‘safety margin’’ refers
to the difference between the updated
emissions inventories in the 2018 Ozone
Maintenance Plan Revision for years
2015 and 2022 and the updated
attainment (2008) emissions inventory
in the plan revision.
TABLE 6—OZONE MOTOR VEHICLE EMISSION BUDGETS
[Average summer weekday, tons/day]
2011 Ozone Maintenance
Plan
Year
NOX
2008 .................................................................................................................
2015 .................................................................................................................
2022 .................................................................................................................
VOC
68.46
34.69
23.15
65.08
45.32
36.71
2018 Ozone Maintenance
Plan Revision
NOX
89.50
90.92
86.74
VOC
42.46
53.94
52.96
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Sources: 2011 Ozone Maintenance Plan, Table 7–1; 2018 Ozone Maintenance Plan Revision, Table 3–1.
As documented in a May 22, 2019
memorandum to the docket for this
rulemaking, we find that the budgets in
the 2018 Ozone Maintenance Plan
Revision meet each adequacy
criterion.48 We have completed our
detailed review of the 2018 Ozone
Maintenance Plan Revision and find
them acceptable. We have also reviewed
the budgets in the 2018 Ozone
Maintenance Plan Revision and found
that they are consistent with the revised
maintenance demonstration; 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
93.1118(e)(4) and (5). Therefore, we are
proposing to find adequate and
conditionally approve the 2008, 2015
and 2022 budgets in the 2018 Ozone
Maintenance Plan Revision. If we
finalize our adequacy determination and
conditional approval of the revised
budgets in the 2018 Ozone Maintenance
Plan Revision, as proposed, they will
replace the budgets for the 1997 ozone
NAAQS from the 2011 Ozone
Maintenance Plan that we previously
found adequate and approved for use in
transportation conformity
determinations. The proposed approval
of the budgets is conditional because it
is based on commitments by NDEP and
Clark County DAQ to submit a SIP
revision within one year of final
conditional approval to reduce the
safety margin allocations to avoid
interference with reasonable further
progress or attainment of the 2008 and
2015 ozone NAAQS. For more
information on why the reduction of the
safety margin is needed, see the
following section of this notice.
45 40 CFR 93.118(e)(4)(iii), (iv) and (v). For more
information on the transportation conformity
requirements and applicable policies on budgets,
please visit our transportation conformity website
at: https://www.epa.gov/otaq/stateresources/
transconf/index.htm.
46 40 CFR 93.118(f)(2).
47 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).
48 Memorandum from Karina O’Connor, Air
Planning Office, EPA Region IX, to Air Plan
Approval; Revisions to the Clark County Ozone
Maintenance Plan, dated May 22, 2019.
49 As a general matter, NO is also considered a
X
precursor for PM10. However, in approving the Las
Vegas Valley Serious Area PM10 Plan, the EPA
determined that major stationary sources of PM10
precursors do not contribute significantly to
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D. CAA Section 110(l) Evaluation
In relevant part, CAA section 110(l)
provides that the EPA shall not approve
a SIP revision that would interfere with
any applicable requirement concerning
attainment or RFP of any of the NAAQS
or any other applicable requirement of
the CAA. The 2018 Ozone Maintenance
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Plan Revision would establish budgets
that are larger than those that are
currently approved from the 2011
Ozone Maintenance Plan. Thus,
approval of the 2018 Ozone
Maintenance Plan Revision would
accommodate a higher level of VOC and
NOX emissions from on-road mobile
source emissions than would otherwise
be allowed under the existing budgets.
In the following paragraphs, we evaluate
the higher level of VOC and NOX
emissions with respect to the potential
for interference with RFP and
attainment of the NAAQS for which
VOC and NOX are precursors, namely,
the 2008 and 2015 ozone NAAQS and
the 2006 and 2012 PM2.5 NAAQS.49
2008 Ozone NAAQS. In 2012, the EPA
designated all the hydrographic areas
within the State of Nevada as
unclassifiable/attainment for the 0.075
ppm 2008 ozone NAAQS based on
ambient ozone concentration data for
elevated ambient PM10 concentrations in Las Vegas
Valley. 69 FR 32273 (June 9, 2004). Moreover, the
approved Las Vegas Valley PM10 Maintenance Plan
relies on direct PM10 control measures (rather than
PM10 precursor controls) to demonstrate
maintenance of the PM10 NAAQS within Las Vegas
Valley. 79 FR 42258 (July 21, 2014) (proposed PM10
redesignation and approval of related maintenance
plan) and 79 FR 60078 (October 6, 2014) (final PM10
redesignation and approval of related maintenance
plan).
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years 2009–2011.50 After the original
designation, the 8-hour ozone design
values within Clark County exceeded
the 2008 ozone NAAQS for a few years
but, since 2015, the design values have
returned to attainment levels for the
2008 ozone NAAQS. See Table 1 above.
Thus, emissions of VOC and NOX in
2015 represent conditions under which
Clark County meets the 2008 ozone
NAAQS. As updated in the 2018 Ozone
Maintenance Plan Revision,
summertime weekday average emissions
in 2015 were approximately 262 tpd of
VOC and 128 tpd of NOX.51 Including
the safety margin allocations to the onroad emissions estimates, the 2018
Ozone Maintenance Plan Revision
allows for 280 tpd of VOC and 168 tpd
of NOX emissions in 2022, i.e., a higher
level of VOC and NOX emissions than
is consistent with continued attainment
of the 2008 ozone NAAQS.
However, in recognition of the need to
avoid interference with attainment of
the 2008 ozone NAAQS and progress
toward attainment of the 2015 ozone
NAAQS, NDEP and Clark County DAQ
have committed to submit a SIP revision
to remove the safety margin allocations
to the 2015 budgets and to reduce the
safety margin allocations to the 2022
budgets such that total estimated
emission in 2022 (with the allocations)
would not exceed actual emissions in
year 2017. As shown in Table 1 above,
the design value in year 2017 was 0.074
ppm, which is consistent with
attainment of the 0.075 ppm 2008 ozone
NAAQS.
Based on the commitments by NDEP
and Clark County DAQ, the total
projected emissions (with the reduced
safety margin allocations) in year 2022
would be less than the actual emissions
estimated for year 2017, a year in which
the 2008 ozone NAAQS was attained in
Clark County. Therefore, the 2018
Ozone Maintenance Plan, as revised
consistent with NDEP’s and Clark
County DAQ’s commitments, would not
interfere with attainment of the 2008
ozone NAAQS in Clark County.
2015 Ozone NAAQS. In 2018, the EPA
designated the Las Vegas Valley (i.e.,
hydrographic area #212) as a Marginal
nonattainment area for the 0.070 ppm
2015 ozone NAAQS based on ambient
ozone concentration data for years
2015–2017.52 The 2017 ozone design
50 Letter from Jared Blumenfeld, Regional
Administrator, EPA Region IX, to Brian Sandoval,
Governor, State of Nevada, dated December 9, 2011.
51 Assumes that no emission reduction credits
(ERCs) were used in 2015.
52 EPA, ‘‘Nevada, Las Vegas Nonattainment Area,
Final Area Designations for the 2015 Ozone
National Ambient Air Quality Standards, Technical
Support Document (TSD).’’
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value is 0.074 ppm, and VOC and NOX
emissions in 2017 are estimated (based
on interpolating the 2015 and 2022
updated inventories in the 2018 Ozone
Maintenance Plan Revision) to be
approximately 257 tpd and 116 tpd,
respectively.53 To attain the 0.070 ppm
2015 ozone NAAQS by the applicable
Marginal area attainment date, i.e., by
August 3, 2021, VOC and NOX
emissions must decrease relative to
those in 2017. With the allocation of the
safety margin to the on-road emissions
estimates, the 2018 Ozone Maintenance
Plan Revision would allow for VOC and
NOX emissions that are greater than
those in 2017.
However, based on the commitments
by NDEP and Clark County DAQ
described above for the 2008 ozone
NAAQS, the total projected emissions
(with the reduced safety margin
allocations) in year 2022 would be less
than the actual emissions estimated for
year 2017, the base year for
implementation of the 2015 ozone
NAAQS. Therefore, the 2018 Ozone
Maintenance Plan, as revised consistent
with NDEP’s and Clark County DAQ’s
commitments, would not interfere with
RFP towards attainment of the 2015
ozone NAAQS.
2006 and 2012 PM2.5 NAAQS. The
EPA has designated the State of Nevada,
on a hydrographic area basis, as
unclassifiable/attainment for both the 35
mg/m3, 24-hour average, 2006 PM2.5
NAAQS and the 12.0 mg/m3, annual
average, 2012 PM2.5 NAAQS.54 The
design values for 24-hour average PM2.5
concentrations have ranged from 19 to
26 mg/m3 over the 2008–2017 period,
well below the corresponding NAAQS
of 35 mg/m3.55 With respect to annual
average PM2.5 concentrations, the design
values have ranged from 7.7 to 10.3 mg/
m3 over that same period, i.e., well
below the corresponding NAAQS of
12.0 mg/m3.56 Thus, since at least 2008,
ambient PM2.5 concentrations have been
well within the applicable NAAQS, and
given that the VOC and NOX emissions
that would be allowed under the 2018
Ozone Maintenance Plan Revision
(including the safety margin allocations
that no ERCs were used in 2017.
CFR 81.329.
55 2017 PM
2.5 Design Values Report at https://
www.epa.gov/air-trends/air-quality-designvalues#report. The 24-hour PM2.5 NAAQS design
value is the 3-year average of annual 98th percentile
24-hour average values recorded at each monitoring
site, and the 24-hour PM2.5 design value for the area
is the highest design value among the monitoring
sites.
56 Id. The annual PM
2.5 NAAQS design value is
the 3-year average of annual mean concentrations
recorded at each monitoring site, and the annual
PM2.5 design value for the area is the highest design
value among the monitoring sites.
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53 Assumes
54 40
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to on-road emissions) would be less
than those that occurred in 2008,
approval of the 2018 Ozone
Maintenance Plan Revision would not
interfere with attainment of the 2006 or
2012 PM2.5 NAAQS in Clark County.
VI. Proposed Action and Request for
Public Comment
For the reasons discussed above,
under CAA section 110(k)(4), the EPA is
proposing to conditionally approve the
2018 Ozone Maintenance Plan Revision
submitted by NDEP on October 31, 2018
as a revision for the Clark County
portion of the Nevada SIP. In so
proposing, we find that the 2011 Ozone
Maintenance Plan, as revised by the
updated attainment inventory and
maintenance demonstration in the 2018
Ozone Maintenance Plan Revision,
continues to provide for maintenance of
the 1997 ozone NAAQS and, upon
fulfillment of the commitments made by
NDEP and Clark County DAQ to reduce
the safety margin allocations to the
budgets, will not interfere with RFP or
attainment of the other NAAQS in Clark
County. In proposing conditional
approval of the 2018 Ozone
Maintenance Plan Revision, the EPA is
also proposing to find adequate and
conditionally approve the updated
budgets for 2008, 2015 and 2022 for the
1997 ozone NAAQS (shown in Table 6
of this document) based on our
conclusion that the updated budgets
meet the applicable transportation
conformity requirements.
The proposed approval of the 2018
Ozone Maintenance Plan Revision is
conditional because it is based on
commitments from NDEP and the Clark
County DAQ to submit a SIP revision
within one year of final conditional
approval.57 The purpose of the future
SIP revision is to reduce the safety
margin allocations to the budgets to
ensure that the 2018 Ozone
Maintenance Plan Revision, as revised
to reduce the safety margin allocations,
will not interfere with reasonable
further progress or attainment of the
2008 and 2015 ozone NAAQS.
Lastly, if the EPA takes final action to
approve conditionally the 2018 Ozone
Maintenance Plan Revision as proposed,
the revised budgets will replace the
existing approved budgets from the
2011 Ozone Maintenance Plan, and RTC
and DOT must use the revised budgets
for future transportation conformity
determinations.
57 Letter from Jodi Bechtel, Assistant Director,
Clark County DAQ, to Greg Lovato, Administrator,
NDEP, dated June 14, 2019; and letter from Greg
Lovato, Administrator, NDEP, to Elizabeth Adams,
Director, Air Division, EPA Region IX, dated June
21, 2019.
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The EPA is soliciting public
comments on the issues discussed in
this document or on other relevant
matters. We will accept comments from
the public on this proposal for the next
30 days. We will consider these
comments before taking final action.
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VII. Statutory and Executive Order
Reviews
Under the Clean Air Act, the
Administrator is required to approve a
SIP submission that complies with the
provisions of the Act and applicable
federal regulations. 42 U.S.C. 7410(k);
40 CFR 52.02(a). Thus, in reviewing SIP
submissions, the EPA’s role is to
approve state choices, provided that
they meet the criteria of the Clean Air
Act. Accordingly, this proposed action
merely proposes to approve
conditionally 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);
• Is not an Executive Order 13771 (82
FR 9339, February 2, 2017) regulatory
action because SIP approvals are
exempted under Executive Order 12866;
• Does not impose an information
collection burden under the provisions
of the Paperwork Reduction Act (44
U.S.C. 3501 et seq.);
• Is certified as not having a
significant economic impact on a
substantial number of small entities
under the Regulatory Flexibility Act (5
U.S.C. 601 et seq.);
• Does not contain any unfunded
mandate or significantly or uniquely
affect small governments, as described
in the Unfunded Mandates Reform Act
of 1995 (Pub. L. 104–4);
• Does not have Federalism
implications as specified in Executive
Order 13132 (64 FR 43255, August 10,
1999);
• Is not an economically significant
regulatory action based on health or
safety risks subject to Executive Order
13045 (62 FR 19885, April 23, 1997);
• Is not a significant regulatory action
subject to Executive Order 13211 (66 FR
28355, May 22, 2001);
• Is not subject to requirements of
Section 12(d) of the National
Technology Transfer and Advancement
Act of 1995 (15 U.S.C. 272 note) because
application of those requirements would
be inconsistent with the Clean Air Act;
and
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• 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, the SIP is not approved
to apply on any Indian reservation land
or in any other area where the EPA or
an Indian tribe has demonstrated that a
tribe has jurisdiction. In those areas of
Indian country, the proposed rule does
not have tribal implications and will not
impose substantial direct costs on tribal
governments or preempt tribal law as
specified by Executive Order 13175 (65
FR 67249, November 9, 2000).
List of Subjects in 40 CFR Part 52
Environmental protection, Air
pollution control, Incorporation by
reference, Intergovernmental
regulations, Nitrogen dioxide, Ozone,
Reporting and recordkeeping
requirements, Volatile organic
compounds.
Authority: 42 U.S.C. 7401 et seq.
Dated: June 27, 2019.
Deborah Jordan,
Acting Regional Administrator, EPA Region
IX.
[FR Doc. 2019–14630 Filed 7–10–19; 8:45 am]
BILLING CODE 6560–50–P
ENVIRONMENTAL PROTECTION
AGENCY
40 CFR Parts 141 and 142
National Primary Drinking Water
Regulations: Perchlorate; Proposed
Rule
Correction
In proposed rule document 2019–
12773 beginning on page 30524 in the
issue of Wednesday, June 26, 2019,
make the following correction:
On page 30558, in the third column,
in the third paragraph, ‘‘[INSERT DATE
30 DAYS AFTER DATE OF
PUBLICATION IN THE Federal
Register]’’ should read ‘‘July 26, 2019’’.
[FR Doc. C1–2019–12773 Filed 7–10–19; 8:45 am]
BILLING CODE 1301–00–D
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33045
ENVIRONMENTAL PROTECTION
AGENCY
40 CFR Part 142
[FRL–9996–39–Region 3]
Public Water System Supervision
Program Revisions for the State of
Delaware
Environmental Protection
Agency (EPA).
ACTION: Notification of tentative
approval and solicitation of requests for
a public hearing.
AGENCY:
Notification is hereby given in
accordance with the provision of section
1413 of the Safe Drinking Water Act, as
amended, and the requirements
governing the National Primary
Drinking Water Regulations
Implementation that the State of
Delaware is revising its approved Public
Water System Supervision Program. The
State has adopted several regulations
which will provide for better public
health protection by reducing exposure
to potential contaminants in drinking
water. EPA has determined that these
revisions are no less stringent than the
corresponding Federal regulations. EPA
is taking action to tentatively approve
these program revisions.
DATES: Comments or a request for a
public hearing must be submitted by
August 12, 2019.
ADDRESSES: Comments or a request for
a public hearing must be submitted to
the U.S. Environmental Protection
Agency Region III, 1650 Arch Street,
Philadelphia, PA 19103–2029.
Comments may also be submitted
electronically to Rizzo.George@epa.gov.
All documents relating to this
determination are available for
inspection between the hours of 8:00
a.m. and 4:30 p.m., Monday through
Friday, at the following offices:
• Drinking Water Section (3WD21),
Water Division, U.S. Environmental
Protection Agency Region III, 1650 Arch
Street, Philadelphia, PA 19103–2029.
• Office of Drinking Water, Delaware
Division of Public Health, 43 South
DuPont Highway, Dover, DE 19901–
7430.
SUMMARY:
FOR FURTHER INFORMATION CONTACT:
George Rizzo at the Philadelphia
address given above, telephone (215)
814–5781, fax (215) 814–2302, or email
Rizzo.George@epa.gov.
SUPPLEMENTARY INFORMATION: The State
regulations which EPA has determined
are no less stringent than the
corresponding Federal regulations are:
Lead and Copper Rule Minor Revisions;
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[Federal Register Volume 84, Number 133 (Thursday, July 11, 2019)]
[Proposed Rules]
[Pages 33035-33045]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2019-14630]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 52
[EPA-R09-OAR-2019-0365; FRL-9996-40-Region 9]
Air Plan Approval; Nevada; Revisions to Clark County Ozone
Maintenance Plan
AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed rule.
-----------------------------------------------------------------------
SUMMARY: The Environmental Protection Agency (EPA) is proposing to
conditionally approve a revision to the State of Nevada's State
Implementation Plan (SIP) for Clark County. The revision consists of an
update to certain elements of the maintenance plan for the Clark County
air quality planning area for the 1997 8-hour ozone national ambient
air quality standards (NAAQS or ``standards''), including the emissions
inventories, maintenance demonstration, and motor vehicle emissions
budgets. The EPA is proposing to conditionally approve the SIP revision
because the Clark County ozone SIP, as revised, continues to provide
for maintenance of the 1997 ozone NAAQS and, upon fulfillment of
certain commitments, will not interfere with attainment or reasonable
further progress of the other NAAQS, and the budgets meet the
applicable transportation conformity requirements. The proposed
approval is conditional because it is based on commitments to submit a
SIP revision to reduce the safety margin allocations for the budgets
within one year of final conditional approval.
DATES: Comments must be received on or before August 12, 2019.
ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R09-
OAR-2019-0365, 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.
FOR FURTHER INFORMATION CONTACT: Karina O'Connor, Air Planning Office
(AIR-2), EPA Region IX, 75 Hawthorne Street, San Francisco, CA 94105;
By phone: (775) 434-8176 or by email at [email protected].
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. What action is the EPA proposing?
II. Background
A. NAAQS, SIPs, Designations, and Transportation Conformity
B. 1997 Ozone NAAQS and Clark County
C. 2008 Ozone NAAQS and Clark County
D. 2015 Ozone NAAQS and Clark County
E. The MOVES Emission Model
III. What did the State submit?
IV. Procedural Requirements for Adoption and Submittal of SIP
Revisions
V. The EPA's Evaluation of the 2018 Ozone Maintenance Plan Revision
[[Page 33036]]
A. Revised Attainment Inventory
B. Revised Maintenance Demonstration
C. Revised Motor Vehicle Emissions Budgets
D. CAA Section 110(l) Evaluation
VI. Proposed Action and Request for Public Comment
VII. Statutory and Executive Order Reviews
I. What action is the EPA proposing?
Under section 110(k) of the Clean Air Act (``Act'' or CAA), the EPA
is required to take action by approving, disapproving, or conditionally
approving, in whole or in part, SIPs and SIP revisions submitted by the
states. In today's action, the EPA is proposing to conditionally
approve a SIP revision titled ``Revision to Motor Vehicle Emissions
Budgets in Ozone Redesignation Request and Maintenance Plan: Clark
County, Nevada'' (October 2018) (herein, referred to as the ``2018
Ozone Maintenance Plan Revision''), submitted by the Nevada Division of
Environmental Protection (NDEP) on October 31, 2018. The 2018 Ozone
Maintenance Plan Revision updates certain elements of the maintenance
plan for Clark County for the 1997 ozone NAAQS, including the
attainment inventory, the maintenance plan, and the motor vehicle
emissions budgets (``budgets'' or MVEBs). The budgets were updated
using the EPA's MOtor Vehicle Emission Simulator emission model
released in 2014 (MOVES2014a). If the EPA takes final action to
conditionally approve the SIP revision, the updated budgets will
replace Clark County's existing budgets for the 1997 ozone NAAQS. At
that time, the previously-approved budgets would no longer be
applicable for transportation conformity purposes, and the revised
budgets would need to be used beginning on the publication date of the
EPA's final conditional approval in the Federal Register.\1\ The
proposed conditional approval is based on commitments from NDEP and the
Clark County Department of Air Quality (DAQ) to submit a SIP revision
within one year of final conditional approval.\2\ The purpose of the
future SIP revision is to reduce the safety margin allocations to the
budgets to ensure that the 2018 Ozone Maintenance Plan Revision, as
revised to reduce the safety margin allocations, will not interfere
with reasonable further progress or attainment of the 2008 and 2015
ozone NAAQS.
---------------------------------------------------------------------------
\1\ 40 CFR 93.118(f)(2)(v).
\2\ Letter from Jodi Bechtel, Assistant Director, Clark County
DAQ, to Greg Lovato, Administrator, NDEP, dated June 14, 2019; and
letter from Greg Lovato, Administrator, NDEP, to Elizabeth Adams,
Director, Air Division, EPA Region IX, dated June 21, 2019.
---------------------------------------------------------------------------
II. Background
A. NAAQS, SIPs, Designations, and Transportation Conformity
Under section 109 of the CAA, the EPA promulgates NAAQS for
pervasive air pollutants, such as ozone. The NAAQS are concentration
levels that, the attainment and maintenance of which, the EPA has
determined to be requisite to protect public health and welfare. Once
the EPA has established a NAAQS or revised a NAAQS, section 110 of the
CAA requires states to adopt and submit to the EPA a plan, referred to
as the SIP, that provides for the implementation, maintenance, and
enforcement of such NAAQS. As noted previously, the EPA is required to
take action to approve, disapprove, or conditionally approve SIPs and
SIP revisions under CAA section 110(k).
Under CAA section 107(d), the EPA must designate all areas of the
country as attainment, nonattainment or unclassifiable for new or
revised NAAQS. States with areas designated as nonattainment must
develop, adopt and submit SIP revisions to provide for, among other
things, attainment as expeditiously as practicable but no later than
certain dates and for reasonable further progress (RFP) towards
attainment.\3\ Once a nonattainment area has attained the NAAQS, the
state may request redesignation of the area from nonattainment to
attainment, and the EPA grants such requests if the criteria in CAA
section 107(d)(3)(E) are met, including the approval of a maintenance
plan (under CAA section 175A) that demonstrates how the area will
maintain the NAAQS for at least 10 years after the redesignation. Such
former nonattainment areas that have been redesignated to attainment
are referred to as ``maintenance areas.''
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\3\ See, generally, part D (``Plan Requirements for
Nonattainment Areas'') of Title I of the CAA.
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In the State of Nevada, NDEP is the Governor's designee for
adoption and submittal of SIPs and SIP revisions to the EPA. NDEP is
also responsible for regulation of stationary sources and development
of local air quality plans throughout much of the State of Nevada. In
Clark County, the Clark County DAQ is responsible under state law for
regulation of most types of stationary sources within the county and
for development of local air quality plans. Once adopted by the Clark
County Board of County Commissioners, such county plans are forwarded
to NDEP for adoption and submittal to the EPA as revisions to the
Nevada SIP.
The emission control strategy SIP revisions (e.g., RFP and
attainment demonstration SIP revisions) and maintenance plans include
budgets of on-road mobile source emissions for criteria pollutants and/
or their precursors to address pollution from cars and trucks. The
budgets are the portions of the total allowable emissions that are
allocated to on-road vehicle use that, together with emissions from
other sources in the area, will provide for RFP, attainment or
maintenance. The budgets serve as a ceiling on emissions from an area's
planned transportation system.\4\
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\4\ For more information about budgets, see the preamble to the
November 24, 1993, transportation conformity rule (58 FR 62188).
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The CAA recognizes the connection between air quality planning and
transportation planning in nonattainment and maintenance areas and
includes specific provisions related to adoption and approval of
transportation programs, plans, and projects by Metropolitan Planning
Organizations (MPOs) and the U.S Department of Transportation's (DOT's)
Federal Highway Administration (FHWA) or Federal Transit Administration
(FTA). More specifically, under section 176(c) of the CAA,
transportation plans, Transportation Improvement Programs (TIPs), and
transportation projects must ``conform'' to (i.e., be consistent with)
the SIP before they can be adopted or approved. Conformity to the SIP
means that transportation activities will not cause new air quality
violations, worsen existing air quality violations, or delay timely
attainment of the NAAQS or delay an interim milestone. The EPA's
transportation conformity rule at 40 CFR part 93, subpart A establishes
the criteria and procedures that MPOs and DOT must use to determine
whether transportation activities conform to the SIP. Transportation
conformity applies to areas that are designated nonattainment and those
former nonattainment areas that have been redesignated to attainment
and have a CAA section 175A maintenance plan (``maintenance areas''),
but does not apply to areas designated as attainment or
unclassifiable.\5\
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\5\ CAA section 176(c)(5).
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Under certain circumstances, MPOs and DOT must determine conformity
based, in part, on a ``budget test'' that involves a comparison between
estimates of regional on-road mobile source emissions under a given
transportation plan or program with the budgets.\6\ Before budgets can
be used in
[[Page 33037]]
conformity determinations, however, the EPA must affirmatively find the
budgets adequate.\7\ However, adequate budgets do not supersede
approved budgets for the same CAA purpose. If the submitted SIP budgets
are meant to replace budgets for the same purpose, the EPA must approve
the budgets, and can affirm that they are adequate at the same time.
Once the EPA approves the submitted budgets, they must be used by state
and federal agencies in determining whether transportation activities
conform to the SIP as required by section 176(c) of the CAA. The EPA's
substantive criteria for determining the adequacy of budgets are set
out in 40 CFR 93.118(e)(4).
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\6\ CAA section 176(c)(1) and 40 CFR 93.109 and 93.118.
\7\ The ``adequacy'' process is established in the EPA's
transportation conformity rule to provide a mechanism whereby
budgets in a submitted SIP revision that has undergone preliminary
review by the EPA can be used for transportation planning purposes
prior to final approval of the SIP revision.
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In Clark County, the area's MPO, the Regional Transportation
Commission of Southern Nevada (RTC) and DOT are the relevant
transportation agencies that must use approved or adequate budgets in
determining the conformity of transportation plans and TIPs within
Clark County.
B. 1997 Ozone NAAQS and Clark County
Ground-level ozone pollution is formed from the reaction of
volatile organic compounds (VOC) and oxides of nitrogen
(NOX) in the presence of sunlight. These two pollutants,
referred to as ozone precursors, are emitted by many types of sources,
including on-and off-road motor vehicles and engines, power plants and
industrial facilities, and smaller area sources such as lawn and garden
equipment and paints. Scientific evidence indicates that adverse public
health effects occur following exposure to ozone, particularly in
children and adults with lung disease. Breathing air containing ozone
can reduce lung function and inflame airways, which can increase
respiratory symptoms and aggravate asthma or other lung diseases.\8\
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\8\ ``Fact Sheet--2008 Final Revisions to the National Ambient
Air Quality Standards for Ozone'' dated March 2008.
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As noted previously, the EPA promulgates NAAQS for pervasive air
pollutants, such as ozone, under CAA section 109. In 1997, the EPA
revised the ozone NAAQS to set the acceptable level of ozone in the
ambient air at 0.08 parts per million (ppm), averaged over an 8-hour
period (herein referred to as the ``1997 ozone NAAQS'').\9\ In 2004,
the EPA designated and classified all areas with respect to the 1997
ozone NAAQS, and designated Clark County as a ``Subpart 1''
nonattainment area for the 1997 ozone NAAQS.\10\ Later that year, the
EPA reduced the geographic extent of the ozone nonattainment area to a
portion of Clark County.\11\ In 2005, we published a final rule that we
would treat the effective date of the partial-county nonattainment area
designation the same as the designations for the rest of the country,
i.e., June 15, 2004.\12\
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\9\ 62 FR 38856 (July 18, 1997) and 40 CFR 50.10. Due to the
number of significant figures in the level of the standard, a
computed 3-year average ozone concentration of 0.085 ppm is the
smallest value that is greater than 0.08 ppm. 40 CFR part 51,
appendix I.
\10\ 69 FR 23858 (April 30, 2004). The ``Subpart 1''
classification meant that the area was subject solely to the general
nonattainment area requirements under subpart 1 of part D (of title
I) of the CAA rather than to the requirements under both subparts 1
and the ozone-specific requirements under subpart 2. Several years
later, in response to litigation over the designations for the 1997
ozone NAAQS, the EPA revised the classification of the Clark County
ozone nonattainment area from ``Subpart 1'' to ``Subpart 2/
Marginal.'' 77 FR 28424 (May 14, 2012).
\11\ 69 FR 55956 (September 17, 2004). The boundaries of the
Clark County ozone nonattainment (now maintenance) area for the 1997
ozone NAAQS are defined in 40 CFR 81.329. Specifically, the area is
defined as: ``That portion of Clark County that lies in hydrographic
areas 164A, 164B, 165, 166, 167, 212, 213, 214, 216, 217, and 218,
but excluding the Moapa River Indian Reservation and the Fort Mojave
Indian Reservation.'' The area includes a significant portion of the
unincorporated portions of central and southern Clark County, as
well as the cities of Las Vegas, Henderson, North Las Vegas and
Boulder City. The hydrographic areas are illustrated in Figure 1-1
of the Clark County Ozone Maintenance Plan (March 2011).
\12\ 70 FR 71612 (November 29, 2005).
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As a ``Subpart 1'' area, the Clark County ozone nonattainment area
was subject to a number of requirements including the requirement to
demonstrate attainment of the 1997 ozone NAAQS as expeditiously as
practicable, but no later than five years from the date that the area
was designated nonattainment.\13\ In 2011, the EPA determined that the
Clark County 8-hour ozone nonattainment area had attained the 1997 8-
hour ozone NAAQS, based on complete, quality-assured, and certified
ambient air monitoring data that showed the area monitored attainment
of the 1997 ozone NAAQS for the 2007-2009 monitoring period.\14\
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\13\ CAA section 172(a)(2).
\14\ 76 FR 17343 (March 29, 2011).
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In 2011, in light of ambient monitoring data showing that the Clark
County ozone nonattainment had attained the 1997 ozone NAAQS, NDEP
submitted the ``Ozone Redesignation Request and Maintenance Plan, Clark
County, Nevada (March 2011)'' (herein, the ``2011 Ozone Maintenance
Plan'') to the EPA for approval as a revision to the Clark County
portion of the Nevada SIP. Prepared by the Clark County DAQ, the 2011
Ozone Maintenance Plan includes the various elements found in most
maintenance plans, including an attainment inventory, maintenance
demonstration, monitoring network, verification of continued
attainment, contingency plan, and motor vehicle emissions budgets.
For the 2011 Ozone Maintenance Plan, Clark County DAQ selected 2008
as the year for the attainment inventory of ozone precursors (i.e., VOC
and NOX), and demonstrated maintenance of the 1997 ozone
NAAQS through year 2022 by reference to emissions inventories developed
for future years 2015 and 2022 that showed that future emissions of VOC
and NOX would not exceed the level of the corresponding
emissions of the attainment inventory. The 2011 Ozone Maintenance Plan
established budgets for NOX and VOC for years 2008, 2015 and
2022. The budgets were derived from the on-road motor vehicle emissions
estimates prepared using the EPA's then-current on-road vehicle
emissions model, MOBILE6.2, and the most recent vehicle mix and
activity data then available from the RTC. In 2013, the EPA approved
the 2011 Ozone Maintenance Plan and redesignated the Clark County ozone
nonattainment area to attainment for the 1997 ozone NAAQS.\15\ The
subject of today's proposed action is a revision to the attainment
inventory, the maintenance demonstration and budgets of the 2011 Ozone
Maintenance Plan to reflect updated emissions models, vehicle mix and
speed data, and transportation activity projections. The other elements
of the 2011 Ozone Maintenance Plan (monitoring network, verification of
continued attainment, contingency plan) are not affected by this
action.
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\15\ 78 FR 1149 (January 8, 2013).
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Through adoption of the 2011 Ozone Maintenance Plan, Clark County
DAQ committed to maintaining an ambient air quality monitoring network
to verify the continued attainment of the 1997 ozone NAAQS in the Clark
County ozone maintenance area.\16\ At the present time, monitors
operating at 10 monitoring sites continuously monitor ambient
concentrations of ozone within the maintenance area. Since 2008, i.e.,
the year used for the attainment inventory in the 2011 Ozone
Maintenance Plan, Clark County has experienced a decrease in ambient
ozone concentrations. As shown in Table 1, 8-hour ozone design values
have decreased from 0.082 ppm in 2008
[[Page 33038]]
to 0.074 ppm in 2017.\17\ In more recent years, the design value has
remained relatively steady, varying little from year to year. Table 1
shows that Clark County has maintained the 1997 ozone NAAQS through the
first 5 years (2013 through 2017) of the first maintenance period.
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\16\ 2011 Ozone Maintenance Plan, page 6-11.
\17\ Under EPA regulations at 40 CFR 50.10 and appendix I, the
1997 ozone NAAQS is attained at a site when the 3-year average of
the annual fourth-highest daily maximum 8-hour average ozone
concentration is less than or equal to 0.08 ppm. This 3-year average
is referred to as the design value. When the design value is less
than or equal to 0.084 ppm (based on the rounding convention in 40
CFR part 50, appendix I) at each monitoring site within the area,
then the area is meeting the 1997 ozone NAAQS. The highest design
value among the various ozone monitoring sites represents the design
value for the area.
Table 1--Eight-Hour Ozone Design Values for the Clark County Ozone
Maintenance Area, 2008-2017
------------------------------------------------------------------------
Design value
Year (ppm)
------------------------------------------------------------------------
2008.................................................... 0.082
2009.................................................... 0.078
2010.................................................... 0.076
2011.................................................... 0.075
2012.................................................... 0.076
2013.................................................... 0.077
2014.................................................... 0.078
2015.................................................... 0.075
2016.................................................... 0.075
2017.................................................... 0.074
------------------------------------------------------------------------
Source: 2017 Ozone Design Values Report at https://www.epa.gov/air-trends/air-quality-design-values#report. Note that design values
reported for a given year reflect data from that year and the two
previous years, e.g., the design value for 2008 reflects data from
2006-2008.
C. 2008 Ozone NAAQS and Clark County
Meanwhile, in 2008, the EPA lowered the ozone NAAQS to a level of
0.075 ppm, 8-hour average (herein, the ``2008 ozone NAAQS''),\18\ and
in 2012, the EPA designated all of the hydrographic areas within the
State of Nevada as ``Unclassifiable/Attainment'' for the 2008 ozone
NAAQS.\19\ Because all the hydrographic areas located entirely, or
partially, within Clark County were designated as Unclassifiable/
Attainment for the 2008 ozone NAAQS, no RFP or attainment SIP revision
was required for any portion of the county, and the transportation
conformity requirements did not apply for that ozone NAAQS.
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\18\ 73 FR 16436 (March 27, 2008) and 40 CFR 50.15.
\19\ 77 FR 30088 (May 21, 2012). Hydrographic areas are those
that are shown on the State of Nevada Division of Water Resources'
map titled ``Water Resources and Inter-basin Flows'' (September
1971).
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In 2015, the EPA issued a SIP Requirements Rule (SRR) for the 2008
ozone NAAQS (``2008 Ozone SRR'') that addressed implementation of the
2008 standards, including attainment dates, requirements for emissions
inventories, attainment and reasonable further progress (RFP)
demonstrations, among other SIP elements, as well as the transition
from the 1997 ozone NAAQS to the 2008 ozone NAAQS and associated anti-
backsliding requirements.\20\ The 2008 Ozone SRR revoked the 1997 ozone
NAAQS effective April 6, 2015.
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\20\ 80 FR 12264 (March 6, 2015) and 40 CFR part 51, subpart AA.
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The EPA's 2008 Ozone SRR was challenged, and on February 16, 2018,
the U.S. Court of Appeals for the D.C. Circuit (``D.C. Circuit'')
published its decision in South Coast Air Quality Management District
v. EPA (``South Coast II'') vacating certain portions of the 2008 Ozone
SRR, but upholding the EPA's revocation of the 1997 ozone NAAQS.\21\
The only aspect of the South Coast II decision that affects this
proposed action is the vacatur of the elimination of transportation
conformity in areas that were maintenance areas for the 1997 ozone
NAAQS at the time of revocation of the 1997 ozone NAAQS and were
designated as attainment for the 2008 ozone NAAQS, which the court
referred to as ``orphan maintenance areas.'' The Clark County 1997
ozone maintenance area is an orphan maintenance area. The 2008 ozone
SRR had provided that such areas are no longer required to determine
transportation conformity for the 1997 ozone NAAQS after the 1997 ozone
NAAQS is revoked.\22\ The court, however, held that transportation
conformity continues to apply for the 1997 ozone NAAQS in orphan
maintenance areas notwithstanding revocation of the 1997 ozone NAAQS.
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\21\ South Coast Air Quality Management District v. EPA, 882
F.3d 1138 (D.C. Cir. 2018) (``South Coast II''). The term ``South
Coast II'' is used in reference to the 2018 court decision to
distinguish it from a decision published in 2006 also referred to as
``South Coast.'' The earlier decision involved a challenge to the
EPA's Phase 1 implementation rule for the 1997 ozone NAAQS. South
Coast Air Quality Management District v. EPA, 472 F.3d 882 (D.C.
Cir. 2006).
\22\ 80 FR 12264, 12284 (March 6, 2015).
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Following the South Coast II decision, the EPA issued guidance that
addresses how transportation conformity determinations can be made for
the 1997 ozone NAAQS in orphan maintenance areas, such as the Clark
County ozone maintenance area.\23\ In the guidance document, the EPA
explains that transportation conformity for transportation plans and
TIPs for the 1997 ozone NAAQS can be demonstrated without a regional
emissions analysis pursuant to 40 CFR 93.109(c).\24\ In the case of the
Clark County ozone maintenance area, while the transportation
conformity requirement continues to apply for the revoked 1997 ozone
NAAQS, RTC and DOT do not need to use the approved MOBILE6.2-based
budgets from the 2011 Ozone Maintenance Plan in a conformity
determination for the revoked 1997 ozone NAAQS because a regional
emissions analysis is not required for that determination.
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\23\ EPA, Office of Transportation and Air Quality,
``Transportation Conformity Guidance for the South Coast II Court
Decision,'' November 2018, EPA-420-B-18-050.
\24\ Id., section 2.4.
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D. 2015 Ozone NAAQS and Clark County
In 2015, the EPA further lowered the ozone NAAQS to 0.070 ppm,
eight-hour average (herein the ``2015 ozone NAAQS'').\25\ In 2018, the
EPA designated the Las Vegas Valley portion of Clark County as a
``Marginal'' nonattainment area for the 2015 ozone NAAQS, effective
August 3, 2018.\26\ The Clark County nonattainment area for the 2015
ozone NAAQS is about half the size of the Clark County maintenance area
for the 1997 ozone NAAQS and includes only hydrographic area 212 (``Las
Vegas Valley'').
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\25\ 80 FR 65292 (October 26, 2015) and 40 CFR 50.19.
\26\ 83 FR 25776 (June 4, 2018).
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The nonattainment area designation for Las Vegas Valley for the
2015 ozone NAAQS triggers the requirement for certain SIP revisions,
but, under CAA section 176(c)(6) and 40 CFR 93.102(d), transportation
conformity does not apply for the 2015 ozone NAAQS for one year
following the effective date of the nonattainment area designation
(referred to as the ``grace period''), or, in this case, does not apply
until August 3, 2019. However, to avoid a conformity ``lapse,'' a MPO
and DOT must make a conformity determination for the 2015 ozone NAAQS
for the applicable transportation plan and program before the end of
the 1-year grace period.\27\
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\27\ EPA, Office of Air Quality Planning and Standards,
``Transportation Conformity Guidance for 2015 Ozone NAAQS
Nonattainment Areas,'' June 2018, EPA-420-B-18-023. During a
conformity lapse, only certain projects can receive additional
federal funding or approvals to proceed (i.e., exempt projects,
project phases that were approved before the lapse, and
transportation control measures (TCMs) in approved SIPs) until the
area has both a conforming transportation plan and TIP.
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Under our Transportation Conformity Rule, the latest approved or
adequate emission budgets for a previous ozone
[[Page 33039]]
NAAQS (i.e., the 2008 or the 1997 ozone NAAQS) must be used in
conformity determinations for the 2015 ozone NAAQS until emission
budgets are established and found adequate or are approved for the 2015
ozone NAAQS.\28\ Since the latest approved or adequate emission budgets
for a previous ozone NAAQS for Clark County are the approved MOBILE6.2-
based budgets for the 1997 8-hour ozone NAAQS, the RTC and DOT must use
these budgets for conformity determinations for the 2015 ozone NAAQS
until they are replaced by updated budgets.
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\28\ 40 CFR 93.109(c)(2).
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E. The MOVES Emission Model
The MOVES model is the EPA's tool for estimating highway emissions.
The model is based on analyses of millions of emission test results and
considerable advances in the agency's understanding of vehicle
emissions. MOVES incorporates the latest emissions data, more
sophisticated calculation algorithms, increased user flexibility, new
software design, and significant new capabilities relative to those
reflected in the EPA's previous motor vehicle emission factor model,
MOBILE6.2.
The EPA announced the release of MOVES2010 on March 2, 2010 (75 FR
9411) and approved the use of MOVES2010 in states other than California
for official SIP submissions to the EPA and for regional emissions
analyses for transportation conformity purposes. The EPA released
MOVES2014 on October 7, 2014 (79 FR 60343). MOVES2014 was a major
revision to MOVES2010 and incorporated new emissions and fleet data,
emission standards and functional improvements and features to the
model. The October 7, 2014 notice approved the use of MOVES2014 in
states outside of California for official SIP submissions to the EPA
and for regional emissions analyses for transportation conformity
purposes. In addition, the notice started a two-year grace period
before MOVES2014 was required to be used in new regional emissions
analyses for transportation conformity determinations outside of
California. Since October 7, 2016, MOVES2014 was required to be used
for new transportation conformity analyses outside California. In
November 2015, the EPA released MOVES2014a, a minor update to
MOVES2014.\29\
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\29\ In August 2018, the EPA released MOVES2014b to improve
estimates of emissions from nonroad mobile sources. MOBILE2014b does
not significantly change the on-road criteria pollutant emissions
results of MOVES2014 and is not considered a new model for SIP and
transportation conformity purposes.
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III. What did the State submit?
On October 31, 2018, NDEP submitted the 2018 Ozone Maintenance Plan
Revision (for the 1997 ozone NAAQS) to the EPA as a revision to the
Clark County portion of the Nevada SIP.\30\ Earlier that month, on
October 16, 2018, the Clark County Board of County Commissioners
adopted the 2018 Ozone Maintenance Plan Revision and forwarded the plan
to NDEP for adoption and submittal to the EPA.\31\ The 2018 Ozone
Maintenance Plan Revision updates certain elements of the 2011 Ozone
Maintenance Plan for the 1997 ozone NAAQS, including the emissions
inventories, the maintenance demonstration, and the MOBILE6.2-derived
budgets. The 2018 Ozone Maintenance Plan Revision also includes a
technical support document (appendix A of the plan revision) and
documentation of the public review process (appendix B of the plan
revision). These updated inventories and budgets in the 2018 Ozone
Maintenance Plan Revision are based on MOVES2014a. The budgets for the
1997 ozone NAAQS were developed so that the RTC would have updated
budgets available to use for transportation conformity determinations
with respect to the 2015 ozone NAAQS until budgets developed
specifically for the 2015 ozone NAAQS are adopted and found to be
adequate or approved.
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\30\ Letter, Greg Lovato, Administrator, NDEP to Mike Stoker,
Regional Administrator, EPA Region IX, October 31, 2018 with
enclosures.
\31\ Clark County Board of County Commissioners Meeting, Meeting
Summary, pages 14 and 15 (of 19), October 16, 2018.
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IV. Procedural Requirements for Adoption and Submittal of SIP Revisions
CAA sections 110(a)(1) and (2) and 110(l) require a state to
provide reasonable public notice and opportunity for public hearing
prior to the adoption and submittal of a SIP or SIP revision. To meet
this requirement, every SIP submittal should include evidence that
adequate public notice was given and an opportunity for a public
hearing was provided consistent with the EPA's implementing regulations
in 40 CFR 51.102.
The Clark County Board of County Commissioners and NDEP have
satisfied applicable statutory and regulatory requirements for
reasonable public notice and hearing prior to adoption and submittal of
the 2018 Ozone Maintenance Plan Revision. In the documentation included
as part of the October 31, 2018 SIP revision submittal,\32\ Clark
County DAQ provided evidence of the required public notice and
opportunity for public comment prior to the October 16, 2018 public
hearing and adoption of the 2018 Ozone Maintenance Plan Revision. We
find, therefore, that the submittal of the 2018 Ozone Maintenance Plan
Revision meets the procedural requirements for public notice and
hearing in CAA sections 110(a) and 110(l).
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\32\ Appendix B provides evidence that reasonable notice of a
public hearing was provided to the public and that a public hearing
was conducted prior to adoption. Specifically, notice of the
availability of, and opening of a 30-day comment period on, the
draft ozone maintenance plan revision was published on August 17,
2018 on the County's web page. No comments were submitted.
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CAA section 110(k)(1)(B) requires the EPA to determine whether a
SIP submittal is complete within 60 days of receipt. This section also
provides that any plan submittal that the EPA has not affirmatively
determined to be complete or incomplete will be deemed complete by
operation of law six months after the date of submittal. The EPA's SIP
completeness criteria are found in 40 CFR part 51, Appendix V. The 2018
Ozone Maintenance Plan Revision submission, dated October 31, 2018,
became complete by operation of law on April 30, 2019.
V. The EPA's Evaluation of the 2018 Ozone Maintenance Plan Revision
The 2018 Ozone Maintenance Plan Revision is not a required
submittal but has been submitted to establish revised budgets
reflecting the most recent emissions models and planning estimates and
to thereby provide the basis for RTC and DOT to make future
transportation conformity determinations for transportation plans, TIPs
and projects with respect to the 2015 ozone NAAQS. We have reviewed the
2018 Ozone Maintenance Plan Revision for compliance with the relevant
requirements for maintenance plans under CAA section 175A and for
noninterference under CAA section 110(l), and we have evaluated the
budgets in the 2018 Ozone Maintenance Plan Revision for compliance with
the budget adequacy criteria in 40 CFR 93.118(e).
CAA 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: Attainment inventory, maintenance demonstration,
monitoring network, verification of continued
[[Page 33040]]
attainment, and contingency plan.\33\ The 2018 Ozone Maintenance Plan
Revision updates two of the core elements of the approved 2011 Ozone
Maintenance Plan for the 1997 ozone NAAQS, the attainment inventory and
maintenance demonstration, and it also updates the budgets.
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\33\ John Calcagni, Director, Air Quality Management Division,
EPA Office of Air Quality Planning and Standards, memo titled
``Procedures for Processing Requests to Redesignate Areas to
Attainment,'' September 4, 1992.
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CAA section 110(l) applies to all SIP revisions, and under that
section, the EPA shall not approve any SIP revision if the revision
would interfere with any applicable requirement concerning attainment
and reasonable further progress or any other applicable requirement of
the CAA.
A. Revised Attainment Inventory
A maintenance plan for the 1997 ozone NAAQS must include an
inventory of emissions of ozone precursors (VOC and NOX) in
the area to identify a level of emissions that are sufficient to attain
the 1997 ozone NAAQS. 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 point sources, area sources, nonroad mobile sources, and on-
road mobile sources, and must be based on actual ``ozone season data''
(i.e., summertime) emissions.
Clark County DAQ selected 2008 as the year for the attainment
inventory in the 2011 Ozone Maintenance Plan. The attainment year
inventory in the 2011 Ozone Maintenance Plan is comprehensive in that
it includes estimates of summertime average weekday VOC and
NOX emissions from all of the relevant source categories,
which the plan divides among point sources,\34\ nonpoint sources,\35\
commercial aviation, federal aviation (i.e., Nellis Air Force Base),
on-road mobile, nonroad mobile, and biogenic \36\ sources.\37\ The 2018
Ozone Maintenance Plan Revision includes a comprehensive update to the
2008 attainment inventory but, to the extent that the original
estimates (i.e., from 2011 Ozone Maintenance Plan) are based on actual
reported emissions or activity levels for year 2008, there is little
change in the related emissions estimate. Appendix A to the 2018 Ozone
Maintenance Plan Revision contains source-specific descriptions of
emission calculation procedures and sources of input data used for the
update.
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\34\ The 2018 Ozone Maintenance Plan Revision uses the term,
``point sources,'' to refer to those stationary source facilities
that are required to report their emissions to Clark County DAQ or
NDEP.
\35\ The 2018 Ozone Maintenance Plan Revision uses the term,
``nonpoint sources,'' to refer to those stationary and area sources
that fall below point source reporting levels and that are too
numerous or small to identify individually.
\36\ For the 2018 Ozone Maintenance Plan Revision, ``biogenic
sources'' include agricultural crops; lawn grass; forests that
produce isoprene, monoterpene, alpha-pinene, and other VOC
emissions; and soils that generate trace amounts of NOX.
\37\ See Table 2-1 in the 2018 Ozone Maintenance Plan Revision.
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Table 2 below compares the attainment inventory from the 2011 Ozone
Maintenance Plan with the corresponding inventory from the 2018 Ozone
Maintenance Plan Revision. As shown in Table 2, the change in the
attainment inventory in the 2018 Ozone Maintenance Revision is
primarily due to the update to the on-road mobile source category and
the nonpoint source category.
Table 2--2008 Attainment Inventory
[Average summer weekday, tons/day]
----------------------------------------------------------------------------------------------------------------
NOX emissions VOC emissions
---------------------------------------------------------------
Source category 2011 Ozone 2018 Ozone 2011 Ozone 2018 Ozone
Maintenance Maintenance Maintenance Maintenance
Plan Plan Revision Plan Plan Revision
----------------------------------------------------------------------------------------------------------------
Point source.................................... 28.73 28.97 1.32 1.50
Nonpoint source................................. 5.41 6.6 57.07 67.56
Commercial aviation............................. 11.41 11.41 2.60 2.60
Federal aviation................................ 1.27 1.27 0.79 0.79
On-road mobile.................................. 68.46 89.50 65.08 42.46
Nonroad mobile.................................. 43.28 40.63 42.91 42.07
Biogenic........................................ 5.00 5.00 132.00 132.00
---------------------------------------------------------------
Total....................................... 163.56 183.38 301.77 288.98
----------------------------------------------------------------------------------------------------------------
Sources: 2011 Ozone Maintenance Plan, tables 6-2 and 6-3; 2018 Ozone Maintenance Plan Revision, table 2-1.
With respect to on-road mobile source emissions, Clark County DAQ
updated the emissions estimates using the SMOKE-MOVES approach, which
incorporates MOVES2014a model emission rates, Sparse Matrix Operator
Kernel Emissions (SMOKE) modeling,\38\ RTC travel demand modeling, and
Highway Performance Monitoring System (HPMS) data from the Nevada
Department of Transportation.\39\ Clark County DAQ selected the SMOKE-
MOVES approach to be consistent with the EPA's approach in developing
the National Emissions Inventory (NEI), as well as with the EPA's
modeling platform. This approach is also consistent with the one used
in Clark County's photochemical modeling applications. In contrast, the
2011 Ozone Maintenance Plan's on-road mobile source emissions were
estimated using the CONCEPT MV emissions model \40\ and EPA's MOBILE6.2
emissions factors. Generally, on-road mobile source emissions estimates
made using MOVES2014a are higher for NOX
[[Page 33041]]
and lower for VOC relative to those made using MOBILE6.2. With respect
to nonpoint emissions sources, the change in the 2008 emissions
inventory is largely due to the use of the SMOKE model.
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\38\ SMOKE is an emission-generating and processing model used
in developing hourly gridded emissions for photochemical modeling.
The EPA has integrated the MOVES model with the SMOKE model with a
set of integration software tools that allows the MOVES emission
rate model to automatically run numerous iterations to generate the
most accurate modeling results. The SMOKE-MOVES integrated approach
takes advantage of gridded hourly temperature and humidity
information from the Weather Research and Forecasting (WRF)
meteorology model used for air quality modeling.
\39\ 2018 Ozone Maintenance Plan Revision, Appendix A, page A-2.
\40\ ``CONCEPT'' refers to the CONsolidated Community Emissions
Processor Tool (CONCEPT) and ``MV'' refers to the motor vehicle
module of the CONCEPT model.
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Based on our review of the emissions inventories (and related
documentation) from the 2018 Ozone Maintenance Plan Revision, we find
that the inventories for 2008 are comprehensive, that the methods and
assumptions used by Clark County DAQ to update the 2008 emission
inventory are reasonable, and that the inventories reasonably estimate
actual ozone season emissions in the 2008 attainment year. Moreover, we
find that the 2008 emissions inventories in the Ozone Maintenance Plan
reflect the latest planning assumptions and emissions models available
at the time the 2018 Ozone Maintenance Plan Revision was developed.
B. Revised Maintenance Demonstration
CAA section 175A(a) 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.'' Generally, a state may demonstrate
maintenance of the ozone NAAQS by either showing that future emissions
will not exceed the level of the attainment inventory or by modeling to
show that the future mix of sources and emissions rates will not cause
a violation of the NAAQS.
The 2018 Ozone Maintenance Plan Revision uses the same method as
the 2011 Ozone Maintenance Plan to demonstrate continued maintenance of
the 1997 ozone NAAQS. The 2018 Ozone Maintenance Plan Revision
demonstrates maintenance through the initial 10-year period after
redesignation by showing that emissions in 2015 and 2022 would be less
than those in the 2008 attainment year.
To provide the basis for the comparison of future emissions with
the updated attainment year (2008) emissions, Clark County DAQ updated
the 2015 and 2022 emissions inventories using the SMOKE-MOVES approach
for the on-road mobile sources as described above for the update to the
2008 attainment year emissions inventory and by incorporating more
recent emissions and travel demand data. Tables 3 and 4 below compare
the NOX and VOC emissions inventories, respectively, for
2015 and 2022 from the 2018 Ozone Maintenance Plan Revision with the
corresponding values from the 2011 Ozone Maintenance Plan.
Table 3--Comparison of NOX Inventories Associated With Approved and Revised Maintenance Plan for the 1997 Ozone NAAQS
[Tons per average summer weekday]
--------------------------------------------------------------------------------------------------------------------------------------------------------
2011 Ozone Maintenance Plan 2018 Ozone Maintenance Plan Net change \b\
\a\ Revision -------------------------------
Source category ----------------------------------------------------------------
2015 2022 2015 2022 2015 2022
--------------------------------------------------------------------------------------------------------------------------------------------------------
Stationary and Area (point and nonpoint)................ 37 38 18 17 -19 -21
On-road................................................. 35 23 64 27 +29 +4
Nonroad (including aviation)............................ 47 51 41 37 -6 -14
Biogenic................................................ 5 5 5 5 0 0
Emission Reduction Credits.............................. 22 22 22 22 0 0
-----------------------------------------------------------------------------------------------
Totals \c\.......................................... 146 139 150 109 +4 -30
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ The emissions shown for the approved ozone plan are from Table 6-3 of Clark County's 2011 Ozone Maintenance Plan.
\b\ For the net change, a negative number indicates a reduction in emissions, and a positive number indicates an increase in emissions relative to the
corresponding figure in the 2011 Ozone Maintenance Plan.
\c\ Because of rounding conventions, totals may not reflect individual subcategories.
Table 4--Comparison of VOC Inventories Associated With Approved and Revised Maintenance Plan for the 1997 Ozone NAAQS
[Tons per average summer weekday]
--------------------------------------------------------------------------------------------------------------------------------------------------------
2011 Ozone Maintenance Plan 2018 Ozone Maintenance Plan Net change \b\
\a\ Revision -------------------------------
Source category ----------------------------------------------------------------
2015 2022 2015 2022 2015 2022
--------------------------------------------------------------------------------------------------------------------------------------------------------
Stationary and Area (point and nonpoint)................ 68 78 63 62 -5 -16
On-road................................................. 45 37 33 17 -12 -20
Nonroad (including aviation)............................ 36 35 35 32 -1 -3
Biogenic................................................ 132 132 132 132 0 0
Emission Reduction Credits.............................. <1 <1 <1 <1 0 0
-----------------------------------------------------------------------------------------------
Totals \c\.......................................... 282 282 263 244 -19 -38
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ The emissions shown for the approved ozone plan are from Table 6-3 of Clark County's 2011 Ozone Maintenance Plan.
\b\ For the net change, a negative number indicates a reduction in emissions, and a positive number indicates an increase in emissions relative to the
corresponding figure in the 2011 Ozone Maintenance Plan.
\c\ Because of rounding conventions, totals may not reflect individual subcategories.
[[Page 33042]]
As shown in tables 3 and 4, total emissions for 2015 and 2022 in
the 2018 Ozone Maintenance Plan Revision are lower than the
corresponding emissions in the 2011 Ozone Maintenance Plan with the
exception of a 4 tpd higher estimate in 2015 for NOX. With
respect to the on-road mobile sources, the update results in higher
NOX emissions but lower VOC emissions and reflects primarily
the differences in the emissions rates calculated using MOVES2014a
relative to those calculated using MOBILE6.2. The on-road mobile source
emission estimates in the 2018 Ozone Maintenance Plan Revision reflect
the most recent published data concerning vehicle registration data,
vehicle miles traveled (VMT) temporal distribution, VMT mix profiles,
vehicle speeds and travel demand forecasts from RTC.\41\ The higher
estimates for NOX from on-road mobile sources are offset by
decreases in the actual reported emissions for point source emissions
compared to their projected emissions in the 2011 Ozone Maintenance
Plan (which includes the shutdown of the Reid Gardner coal-fired power
plant). Other significant differences include: (1) A reduction in
commercial aviation emissions because the Sloan Regional Heliport and
South County Ivanpah Airport projects, which had been assumed for the
2011 Ozone Maintenance Plan, have not been constructed and (2)
reductions in nonpoint source emission projection factors.\42\
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\41\ Key references used by Clark County DAQ include Eastern
Research Group, Inc.'s ``Clark County On-Road Vehicle Classification
Study,'' final report, June 29, 2018 and the Coordinating Research
Council, Inc.'s ``Improvement of Default Inputs for MOVES and SMOKE-
MOVES,'' final report, February 2017.
\42\ Clark County projected emissions from 2014 NEI data with
factors derived from the 2011-2023 annual rate of change for all
nonpoint sectors from EPA's 2011 Version 6 Air Emissions Modeling
Platform. Nonpoint source emissions in the 2011 Ozone Maintenance
Plan were based on the 2008 NEI and higher growth correlated to
population and economic growth factors.
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Based on our review of the methods, assumptions, and data sources,
as described in Appendix A to the 2018 Ozone Maintenance Plan Revision,
and briefly summarized above, we find that Clark County DAQ's estimates
for 2015 and 2022 for the various source categories to be based on the
best available emissions models and data sources, and thus to provide a
reasonable basis upon which to evaluate whether the area will maintain
the 1997 ozone NAAQS through 2022.
A state may choose to allocate all or a portion of the safety
margin \43\ 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).\44\ For the 2018 Ozone Maintenance
Plan Revision, Clark County DAQ allocated 80 percent of the safety
margin for NOX and VOC in 2015 and 2022 to the projected on-
road emissions estimates for NOX and VOC.
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\43\ In this context, ``safety margin'' means the amount by
which the total projected emissions from all sources of a given
pollutant are less than the total emissions that would satisfy the
applicable requirements for reasonable further progress, attainment
or maintenance. With respect to the 2018 Ozone Maintenance Plan
Revision, the safety margin is the difference between the projected
emissions in 2015 and 2022 of NOX and VOC and the actual
emissions of NOX and VOC in the 2008 attainment year.
\44\ See 40 CFR 93.124(a).
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Table 5 below summarizes the revised maintenance demonstration
(including the safety margins) for the 1997 ozone NAAQS. As shown in
Table 5, the revised emission estimates for NOX and VOC in
2015 and 2022 (including the safety margins) would remain below the
corresponding 2008 attainment levels throughout the 10-year maintenance
period and thereby adequately demonstrate maintenance through that
period.
Table 5--Revised Maintenance Demonstration for 1997 Ozone NAAQS
----------------------------------------------------------------------------------------------------------------
Emissions (average summer weekday, tpd)
-----------------------------------------------------------------
Source description Attainment (2008) 2015 2022
-----------------------------------------------------------------
NOX VOC NOX VOC NOX VOC
----------------------------------------------------------------------------------------------------------------
Projected Emissions--Excluding On-Road Mobile 93.88 246.52 85.81 229.82 81.71 227.06
Sources......................................
Projected On-Road Mobile Source Emissions..... 89.50 42.46 64.30 33.04 27.02 17.12
Allocation of Portion of Safety Margin to On- 0 0 26.62 20.90 59.72 35.84
Road.........................................
Total Emissions (with Safety Margins)......... 183.38 288.98 176.73 283.76 168.45 280.02
Maintenance Demonstrated?..................... ......... ......... Yes Yes Yes Yes
Motor Vehicle Emissions Budget (Projected On- 89.50 42.46 90.92 53.94 86.74 52.96
Road Plus Safety Margin).....................
----------------------------------------------------------------------------------------------------------------
Source: 2018 Ozone Maintenance Plan Revision, Tables 2-1, 2-2 and 3-1. Note: Maintenance is demonstrated where
future emissions (with the safety margins) are less than the corresponding attainment inventory emissions.
C. Revised Motor Vehicle Emissions Budgets
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 timely attainment of the standards. Conformity to the SIP's
goals means that such actions will not: (1) Cause or contribute to
violations of a NAAQS, (2) worsen the severity of an existing
violation, or (3) delay timely attainment of any NAAQS or any interim
milestone.
Under the transportation conformity rule, MPOs in nonattainment and
maintenance areas coordinate with state and local air quality and
transportation agencies, the EPA, the FHWA, and the FTA to demonstrate
that an area's regional transportation plans and TIPs 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 budgets contained in all control
strategy or maintenance SIPs. Budgets are generally established for
specific years and specific pollutants or precursors. Maintenance ozone
plans should identify budgets for on-road emissions of ozone precursors
(NOX and VOC) in the area for the last year of the
maintenance period. Budgets may also be specified for additional years
during the maintenance period.
For budgets to be approvable, they must meet the EPA's adequacy
criteria (40 CFR 93.118(e)(4) and (5)) and comply with all pertinent
SIP requirements. With respect to maintenance plans, to meet these
requirements, the budgets must be consistent with the maintenance plan
and reflect all the motor vehicle control measures contained in the
maintenance
[[Page 33043]]
demonstration.\45\ The EPA's process for determining adequacy of a
budget consists of three basic steps: (1) Providing public notification
of a SIP submission; (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.\46\ We will complete the adequacy
review of the budgets in the 2018 Ozone Maintenance Plan Revision
concurrent with our final action on the 2018 Ozone Maintenance Plan
Revision. The EPA is not required under its transportation conformity
rule to find budgets adequate prior to proposing approval of them.\47\
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\45\ 40 CFR 93.118(e)(4)(iii), (iv) and (v). For more
information on the transportation conformity requirements and
applicable policies on budgets, please visit our transportation
conformity website at: https://www.epa.gov/otaq/stateresources/transconf/index.htm.
\46\ 40 CFR 93.118(f)(2).
\47\ 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).
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The 2018 Ozone Maintenance Plan Revision includes revised budgets
for VOC and NOX for years 2008, 2015 and the last year of
the initial maintenance period, i.e., 2022. The revised budgets from
the 2018 Ozone Maintenance Plan Revision are shown in Table 6 below and
compared with the corresponding budgets from the approved 2011 Ozone
Maintenance Plan. As noted previously, Clark County DAQ developed the
revised budgets using the latest emissions model (MOVES2014a) available
at the time the 2018 Ozone Maintenance Plan Revision was being
developed, and the most recent travel activity projections provided by
the NDOT and RTC. As such, we find that the revised budgets reflect the
most recent planning forecasts and are based on the most recent
emission factor data and approved calculation methods. Clark County DAQ
included 80% of the safety margin in the budgets. In this context, the
term ``safety margin'' refers to the difference between the updated
emissions inventories in the 2018 Ozone Maintenance Plan Revision for
years 2015 and 2022 and the updated attainment (2008) emissions
inventory in the plan revision.
Table 6--Ozone Motor Vehicle Emission Budgets
[Average summer weekday, tons/day]
----------------------------------------------------------------------------------------------------------------
2011 Ozone Maintenance Plan 2018 Ozone Maintenance Plan
-------------------------------- Revision
Year -------------------------------
NOX VOC NOX VOC
----------------------------------------------------------------------------------------------------------------
2008............................................ 68.46 65.08 89.50 42.46
2015............................................ 34.69 45.32 90.92 53.94
2022............................................ 23.15 36.71 86.74 52.96
----------------------------------------------------------------------------------------------------------------
Sources: 2011 Ozone Maintenance Plan, Table 7-1; 2018 Ozone Maintenance Plan Revision, Table 3-1.
As documented in a May 22, 2019 memorandum to the docket for this
rulemaking, we find that the budgets in the 2018 Ozone Maintenance Plan
Revision meet each adequacy criterion.\48\ We have completed our
detailed review of the 2018 Ozone Maintenance Plan Revision and find
them acceptable. We have also reviewed the budgets in the 2018 Ozone
Maintenance Plan Revision and found that they are consistent with the
revised maintenance demonstration; 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 93.1118(e)(4) and (5). Therefore, we are proposing
to find adequate and conditionally approve the 2008, 2015 and 2022
budgets in the 2018 Ozone Maintenance Plan Revision. If we finalize our
adequacy determination and conditional approval of the revised budgets
in the 2018 Ozone Maintenance Plan Revision, as proposed, they will
replace the budgets for the 1997 ozone NAAQS from the 2011 Ozone
Maintenance Plan that we previously found adequate and approved for use
in transportation conformity determinations. The proposed approval of
the budgets is conditional because it is based on commitments by NDEP
and Clark County DAQ to submit a SIP revision within one year of final
conditional approval to reduce the safety margin allocations to avoid
interference with reasonable further progress or attainment of the 2008
and 2015 ozone NAAQS. For more information on why the reduction of the
safety margin is needed, see the following section of this notice.
---------------------------------------------------------------------------
\48\ Memorandum from Karina O'Connor, Air Planning Office, EPA
Region IX, to Air Plan Approval; Revisions to the Clark County Ozone
Maintenance Plan, dated May 22, 2019.
---------------------------------------------------------------------------
D. CAA Section 110(l) Evaluation
In relevant part, CAA section 110(l) provides that the EPA shall
not approve a SIP revision that would interfere with any applicable
requirement concerning attainment or RFP of any of the NAAQS or any
other applicable requirement of the CAA. The 2018 Ozone Maintenance
Plan Revision would establish budgets that are larger than those that
are currently approved from the 2011 Ozone Maintenance Plan. Thus,
approval of the 2018 Ozone Maintenance Plan Revision would accommodate
a higher level of VOC and NOX emissions from on-road mobile
source emissions than would otherwise be allowed under the existing
budgets. In the following paragraphs, we evaluate the higher level of
VOC and NOX emissions with respect to the potential for
interference with RFP and attainment of the NAAQS for which VOC and
NOX are precursors, namely, the 2008 and 2015 ozone NAAQS
and the 2006 and 2012 PM2.5 NAAQS.\49\
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\49\ As a general matter, NOX is also considered a
precursor for PM10. However, in approving the Las Vegas
Valley Serious Area PM10 Plan, the EPA determined that
major stationary sources of PM10 precursors do not
contribute significantly to elevated ambient PM10
concentrations in Las Vegas Valley. 69 FR 32273 (June 9, 2004).
Moreover, the approved Las Vegas Valley PM10 Maintenance
Plan relies on direct PM10 control measures (rather than
PM10 precursor controls) to demonstrate maintenance of
the PM10 NAAQS within Las Vegas Valley. 79 FR 42258 (July
21, 2014) (proposed PM10 redesignation and approval of
related maintenance plan) and 79 FR 60078 (October 6, 2014) (final
PM10 redesignation and approval of related maintenance
plan).
---------------------------------------------------------------------------
2008 Ozone NAAQS. In 2012, the EPA designated all the hydrographic
areas within the State of Nevada as unclassifiable/attainment for the
0.075 ppm 2008 ozone NAAQS based on ambient ozone concentration data
for
[[Page 33044]]
years 2009-2011.\50\ After the original designation, the 8-hour ozone
design values within Clark County exceeded the 2008 ozone NAAQS for a
few years but, since 2015, the design values have returned to
attainment levels for the 2008 ozone NAAQS. See Table 1 above. Thus,
emissions of VOC and NOX in 2015 represent conditions under
which Clark County meets the 2008 ozone NAAQS. As updated in the 2018
Ozone Maintenance Plan Revision, summertime weekday average emissions
in 2015 were approximately 262 tpd of VOC and 128 tpd of
NOX.\51\ Including the safety margin allocations to the on-
road emissions estimates, the 2018 Ozone Maintenance Plan Revision
allows for 280 tpd of VOC and 168 tpd of NOX emissions in
2022, i.e., a higher level of VOC and NOX emissions than is
consistent with continued attainment of the 2008 ozone NAAQS.
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\50\ Letter from Jared Blumenfeld, Regional Administrator, EPA
Region IX, to Brian Sandoval, Governor, State of Nevada, dated
December 9, 2011.
\51\ Assumes that no emission reduction credits (ERCs) were used
in 2015.
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However, in recognition of the need to avoid interference with
attainment of the 2008 ozone NAAQS and progress toward attainment of
the 2015 ozone NAAQS, NDEP and Clark County DAQ have committed to
submit a SIP revision to remove the safety margin allocations to the
2015 budgets and to reduce the safety margin allocations to the 2022
budgets such that total estimated emission in 2022 (with the
allocations) would not exceed actual emissions in year 2017. As shown
in Table 1 above, the design value in year 2017 was 0.074 ppm, which is
consistent with attainment of the 0.075 ppm 2008 ozone NAAQS.
Based on the commitments by NDEP and Clark County DAQ, the total
projected emissions (with the reduced safety margin allocations) in
year 2022 would be less than the actual emissions estimated for year
2017, a year in which the 2008 ozone NAAQS was attained in Clark
County. Therefore, the 2018 Ozone Maintenance Plan, as revised
consistent with NDEP's and Clark County DAQ's commitments, would not
interfere with attainment of the 2008 ozone NAAQS in Clark County.
2015 Ozone NAAQS. In 2018, the EPA designated the Las Vegas Valley
(i.e., hydrographic area #212) as a Marginal nonattainment area for the
0.070 ppm 2015 ozone NAAQS based on ambient ozone concentration data
for years 2015-2017.\52\ The 2017 ozone design value is 0.074 ppm, and
VOC and NOX emissions in 2017 are estimated (based on
interpolating the 2015 and 2022 updated inventories in the 2018 Ozone
Maintenance Plan Revision) to be approximately 257 tpd and 116 tpd,
respectively.\53\ To attain the 0.070 ppm 2015 ozone NAAQS by the
applicable Marginal area attainment date, i.e., by August 3, 2021, VOC
and NOX emissions must decrease relative to those in 2017.
With the allocation of the safety margin to the on-road emissions
estimates, the 2018 Ozone Maintenance Plan Revision would allow for VOC
and NOX emissions that are greater than those in 2017.
---------------------------------------------------------------------------
\52\ EPA, ``Nevada, Las Vegas Nonattainment Area, Final Area
Designations for the 2015 Ozone National Ambient Air Quality
Standards, Technical Support Document (TSD).''
\53\ Assumes that no ERCs were used in 2017.
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However, based on the commitments by NDEP and Clark County DAQ
described above for the 2008 ozone NAAQS, the total projected emissions
(with the reduced safety margin allocations) in year 2022 would be less
than the actual emissions estimated for year 2017, the base year for
implementation of the 2015 ozone NAAQS. Therefore, the 2018 Ozone
Maintenance Plan, as revised consistent with NDEP's and Clark County
DAQ's commitments, would not interfere with RFP towards attainment of
the 2015 ozone NAAQS.
2006 and 2012 PM2.5 NAAQS. The EPA has designated the State of
Nevada, on a hydrographic area basis, as unclassifiable/attainment for
both the 35 [micro]g/m\3\, 24-hour average, 2006 PM2.5 NAAQS
and the 12.0 [micro]g/m\3\, annual average, 2012 PM2.5
NAAQS.\54\ The design values for 24-hour average PM2.5
concentrations have ranged from 19 to 26 [micro]g/m\3\ over the 2008-
2017 period, well below the corresponding NAAQS of 35 [micro]g/
m\3\.\55\ With respect to annual average PM2.5
concentrations, the design values have ranged from 7.7 to 10.3
[micro]g/m\3\ over that same period, i.e., well below the corresponding
NAAQS of 12.0 [micro]g/m\3\.\56\ Thus, since at least 2008, ambient
PM2.5 concentrations have been well within the applicable
NAAQS, and given that the VOC and NOX emissions that would
be allowed under the 2018 Ozone Maintenance Plan Revision (including
the safety margin allocations to on-road emissions) would be less than
those that occurred in 2008, approval of the 2018 Ozone Maintenance
Plan Revision would not interfere with attainment of the 2006 or 2012
PM2.5 NAAQS in Clark County.
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\54\ 40 CFR 81.329.
\55\ 2017 PM2.5 Design Values Report at https://www.epa.gov/air-trends/air-quality-design-values#report. The 24-hour
PM2.5 NAAQS design value is the 3-year average of annual
98th percentile 24-hour average values recorded at each monitoring
site, and the 24-hour PM2.5 design value for the area is
the highest design value among the monitoring sites.
\56\ Id. The annual PM2.5 NAAQS design value is the
3-year average of annual mean concentrations recorded at each
monitoring site, and the annual PM2.5 design value for
the area is the highest design value among the monitoring sites.
---------------------------------------------------------------------------
VI. Proposed Action and Request for Public Comment
For the reasons discussed above, under CAA section 110(k)(4), the
EPA is proposing to conditionally approve the 2018 Ozone Maintenance
Plan Revision submitted by NDEP on October 31, 2018 as a revision for
the Clark County portion of the Nevada SIP. In so proposing, we find
that the 2011 Ozone Maintenance Plan, as revised by the updated
attainment inventory and maintenance demonstration in the 2018 Ozone
Maintenance Plan Revision, continues to provide for maintenance of the
1997 ozone NAAQS and, upon fulfillment of the commitments made by NDEP
and Clark County DAQ to reduce the safety margin allocations to the
budgets, will not interfere with RFP or attainment of the other NAAQS
in Clark County. In proposing conditional approval of the 2018 Ozone
Maintenance Plan Revision, the EPA is also proposing to find adequate
and conditionally approve the updated budgets for 2008, 2015 and 2022
for the 1997 ozone NAAQS (shown in Table 6 of this document) based on
our conclusion that the updated budgets meet the applicable
transportation conformity requirements.
The proposed approval of the 2018 Ozone Maintenance Plan Revision
is conditional because it is based on commitments from NDEP and the
Clark County DAQ to submit a SIP revision within one year of final
conditional approval.\57\ The purpose of the future SIP revision is to
reduce the safety margin allocations to the budgets to ensure that the
2018 Ozone Maintenance Plan Revision, as revised to reduce the safety
margin allocations, will not interfere with reasonable further progress
or attainment of the 2008 and 2015 ozone NAAQS.
---------------------------------------------------------------------------
\57\ Letter from Jodi Bechtel, Assistant Director, Clark County
DAQ, to Greg Lovato, Administrator, NDEP, dated June 14, 2019; and
letter from Greg Lovato, Administrator, NDEP, to Elizabeth Adams,
Director, Air Division, EPA Region IX, dated June 21, 2019.
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Lastly, if the EPA takes final action to approve conditionally the
2018 Ozone Maintenance Plan Revision as proposed, the revised budgets
will replace the existing approved budgets from the 2011 Ozone
Maintenance Plan, and RTC and DOT must use the revised budgets for
future transportation conformity determinations.
[[Page 33045]]
The EPA is soliciting public comments on the issues discussed in
this document or on other relevant matters. We will accept comments
from the public on this proposal for the next 30 days. We will consider
these comments before taking final action.
VII. Statutory and Executive Order Reviews
Under the Clean Air Act, the Administrator is required to approve a
SIP submission that complies with the provisions of the Act and
applicable federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a).
Thus, in reviewing SIP submissions, the EPA's role is to approve state
choices, provided that they meet the criteria of the Clean Air Act.
Accordingly, this proposed action merely proposes to approve
conditionally 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);
Is not an Executive Order 13771 (82 FR 9339, February 2,
2017) regulatory action because SIP approvals are exempted under
Executive Order 12866;
Does not impose an information collection burden under the
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
Is certified as not having a significant economic impact
on a substantial number of small entities under the Regulatory
Flexibility Act (5 U.S.C. 601 et seq.);
Does not contain any unfunded mandate or significantly or
uniquely affect small governments, as described in the Unfunded
Mandates Reform Act of 1995 (Pub. L. 104-4);
Does not have Federalism implications as specified in
Executive Order 13132 (64 FR 43255, August 10, 1999);
Is not an economically significant regulatory action based
on health or safety risks subject to Executive Order 13045 (62 FR
19885, April 23, 1997);
Is not a significant regulatory action subject to
Executive Order 13211 (66 FR 28355, May 22, 2001);
Is not subject to requirements of Section 12(d) of the
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272
note) because application of those requirements would be inconsistent
with the Clean Air Act; and
Does not provide 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, the SIP is not approved to apply on any Indian
reservation land or in any other area where the EPA or an Indian tribe
has demonstrated that a tribe has jurisdiction. In those areas of
Indian country, the proposed rule does not have tribal implications and
will not impose substantial direct costs on tribal governments or
preempt tribal law as specified by Executive Order 13175 (65 FR 67249,
November 9, 2000).
List of Subjects in 40 CFR Part 52
Environmental protection, Air pollution control, Incorporation by
reference, Intergovernmental regulations, Nitrogen dioxide, Ozone,
Reporting and recordkeeping requirements, Volatile organic compounds.
Authority: 42 U.S.C. 7401 et seq.
Dated: June 27, 2019.
Deborah Jordan,
Acting Regional Administrator, EPA Region IX.
[FR Doc. 2019-14630 Filed 7-10-19; 8:45 am]
BILLING CODE 6560-50-P
