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Federal Register / Vol. 86, No. 145 / Monday, August 2, 2021 / Proposed Rules
there must be a publication of a notice by prominent advertisement in the relevant geographic area of the proposed SIP revision, a public comment period of at least 30 days, and an opportunity for a public hearing.
The Clark County Department of Environment and Sustainability CCDES 15 published a notice of a 30day comment period and notice of a public hearing for the 2019 LMP on the Clark County website, and the departments website, Twitter, and Facebook pages. An email notice was distributed to officials in relevant cities as well as in state and local-level departments, districts, authorities, commissions, and associations. The CCDES held a public comment period from February 15, 2019 to March 18, 2019. No formal comments were submitted. On May 7, 2019, the Clark County Board of County Commissioners held a public hearing on the 2019 LMP.
No formal comments were submitted during this hearing. The CCDES then forwarded the 2019 LMP to the State of Nevada and the State submitted the plan to the EPA as a revision to the Nevada SIP. The process followed by the CCDES
adheres with procedural requirements for SIP revisions outlined under CAA
section 110 and the EPAs implementing regulations.
B. LMP Requirements The EPA reviewed the 2019 LMP that addresses maintenance of the CO
NAAQS within the Las Vegas Valley area through the end of the 20-year period following the areas redesignation, as required under CAA
section 175Ab.
1. Attainment Emissions Inventory For maintenance plans, a state should develop a comprehensive, accurate inventory of actual emissions for an attainment year to identify the level of emissions sufficient to maintain the NAAQS. For CO, the inventory should represent the typical winter day
emissions of CO for the time period associated with the monitoring data showing attainment.16 The 2019 LMP
includes a CO attainment inventory for the Las Vegas Valley area that reflects typical winter weekday emissions in 2017. Table 1 presents a summary of the inventory for the year contained in the maintenance plan. Under an LMP, states are not required to project emissions over the maintenance period.

TABLE 12017 AVERAGE WINTER
WEEKDAY CO EMISSIONS FOR THE
LAS VEGAS VALLEY AREA
Tons per day
latest release of the EPAs Motor Vehicle Emission Simulator MOVES model version MOVES2014b.
Based on our review of the methods, models, and assumptions used by CCDES to develop the CO estimates, we find that the 2019 LMP for the Las Vegas Valley CO maintenance area includes a comprehensive, accurate inventory of CO emissions in the year 2017, and conclude that the plans inventories are acceptable for the purposes of a subsequent maintenance plan under CAA section 175Ab.
2. Maintenance Demonstration
Consistent with prior EPA guidance, if a maintenance area demonstrates a maximum 8-hour CO design value of less than or equal to 85 percent of the CO NAAQS, or 7.65 ppm, for eight consecutive quarters, then the EPA
Total 448.96 considers the area to have met the maintenance plan demonstration requirement and that the area will CCDES derived point source emissions using semiannual compliance maintain the NAAQS for the second 10year maintenance period.18 Such a reports submitted to the agency by demonstration also assumes continued stationary sources located in the Las applicability of prevention of significant Vegas Valley area. These reports are deterioration PSD requirements,19
required by CCDES federally-approved continued implementation of any CAA title V operating permits program existing control measures in the SIP, and include monthly reporting data for and that federal measures will remain in the facility.17 CCDES derived the place through the end of the second 10nonpoint source emissions from the year maintenance period. The EPA does EPAs 2016 modeling platform alpha not require areas using the LMP option version and used 2016 as a surrogate to project emissions over the for 2017 because the 2017 National maintenance period.
Emissions Inventory NEI for nonpoint sources was not available at the time Table 2 presents the design values for CCDES developed the 2019 LMP.
the Las Vegas Valley area over the 2012
CCDES determined that the differences 2020 period. As shown in Table 2, between 2016 and 2017 would be historically, the area has consistently insignificant. Aviation operation data been well below 85 percent of the for 2014 and 2017 were obtained from NAAQS. Because the CO design values the Federal Aviation Administrations in the Las Vegas Valley area are below air traffic activity system and terminal the LMP threshold over the most recent area forecast databases and used in eight quarters, the EPA finds that the conjunction with the 2014 NEI to State has adequately demonstrated that estimate aviation CO emissions for the area will continue to maintain the 2017. Onroad and nonroad mobile CO NAAQS over the second 10-year source data were generated using the maintenance period and in the future.
Point
Nonpoint
Aviation
Onroad Mobile
Nonroad Mobile

0.93
43.48
12.53
217.18
114.35

TABLE 2CURRENT AND HISTORICAL CO DESIGN VALUES DV FOR THE LAS VEGAS VALLEY AREA
Highest second maximum 8-hour CO value ppm Year
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Jerome Mack 320030540
2012
2013
15 Formerly Clark County Department of Air Quality.
16 Paisie Memo, 3.
17 CCDES used reporting data for the CO season months January, February, and December 2017 to
VerDate Sep<11>2014

16:46 Jul 30, 2021

Jkt 253001

J.D. Smith 320032002

2.8
2.8

2.1
2.4

Rancho &
Teddy 320031501

develop emissions for those months and convert to daily emissions. See 2019 LMP, 18.
18 Paisie Memo, 3.
19 PSD applies to new major sources or major modifications at existing sources for pollutants where the area of the sources location is designated
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Fmt 4702

Sfmt 4702

Sunrise Acres 320030540
3.1
3.1

DV
ppm
3.1
3.1

Is DV less than 7.65
ppm?

Yes.
Yes.

by the EPA as attainment or unclassifiable with the NAAQS. Its requirements include, but are not limited to, the following: Installation of best available control technology, an air quality analysis, an additional impact analysis, and public involvement.

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