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Federal Register / Vol. 86, No. 168 / Thursday, September 2, 2021 / Proposed Rules mg/m3 outlined in the LMP Option Memo. Therefore, the EPA finds that the Eagle River area meets the design value criteria outlined in the LMP options memo.
Third, the area must meet the motor vehicle regional emissions analysis test described in the LMP Option Memo.
The State submitted an analysis showing that growth in on-road mobile PM10 emissions sources was minimal and would not threaten the assumption of maintenance that underlies the LMP
policy. Using the EPAs methodology, the State calculated total projected growth in on-road motor vehicle PM10
emissions through 2033 the end of the 20-year maintenance period for the Eagle River area. This calculation is derived using Attachment B of the EPAs LMP Option Memo, where the projected percentage increase in vehicle miles traveled over the next ten years VMTpi is multiplied by the on-road mobile portion of the attainment year inventory DVmv, including reentrained road dust. This test is met when VMTpi DVmv plus the design value for the most recent five years of quality assured data is below the margin of safety MOS for the relevant PM10
standard in mg/m3 for a given area. This MOS value can be 98 mg/m3 or a sitespecific value computed from data collected at the site of interest using methods outlined in Attachment A of the LMP Option Memo. The computed site-specific MOS selected for the Parkgate monitoring site in Eagle River is 125.7 mg/m3 the critical design value for all the empirical data. See the Eagle River LMP, Section III.D.2.5 and associated appendix, placed in the docket for this action, for details of this computation. The motor vehicle regional emissions analysis test results of 109.6 mg/m3, when adjusted for growth, are below the calculated sitespecific critical design value, or MOS, of 125.7 mg/m3. The EPA has reviewed the calculations in the States Eagle River
LMP submittal and proposes to find that the area meets the motor vehicle regional emissions analysis test.
As described above, the Eagle River PM10 maintenance area meets the qualification criteria set forth in the LMP Option Memo and accordingly qualifies for the LMP option. To ensure these requirements continue to be met, the State commits to evaluate monitoring data annually to ensure the area continues to qualify for the LMP
option. However, if after performing the annual recalculation of the areas average design value in a given year, the State determines that the area no longer qualifies for the LMP, the State will take action to attempt to reduce PM10
concentrations enough for the area to requalify for the LMP. One possible approach the State may take is to implement a contingency measure found in its SIP. See Section III.D.2.10
of the States submittal, placed in the docket for this action, for a description of the contingency measures. If the attempt to reduce PM10 concentrations fails, or if it succeeds but in future years it becomes necessary again to address increasing PM10 concentrations in the area, the area will no longer qualify for the LMP option.
B. Attainment Inventory Pursuant to the LMP Option Memo, the States submission should include an emissions inventory, which can be used to demonstrate attainment of the relevant NAAQS. The inventory should represent emissions during the same five-year period associated with air quality data used to determine whether the area meets the applicability requirements of the LMP option. The State should review its inventory every three years to ensure emissions growth is incorporated in the inventory if necessary.
Alaskas Eagle River PM10 LMP
includes an emissions inventory, with a base year of 2017. In the past, the
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highest PM10 concentrations have typically occurred during spring breakup and fall freeze-up. For this reason, the emissions inventories reflect conditions and activity levels e.g., amount of silt loading on roads and residential wood heating rates that commonly occur during these two times of the year. The same assumptions and methods used to develop the first 10year LMP were used to develop the 2017
base year PM10 emissions inventory for the second 10-year LMP and are described in detail in the Appendix to III.D.2.6 of the Eagle River LMP
submittal in the docket for this action.
The 2017 base year represents the most recent emissions inventory data available, is representative of the level of emissions during a period of time used to calculate the area is attaining the NAAQS, and is consistent with the data used to determine applicability of the LMP option i.e., having no violations of the NAAQS during the five-year period used to calculate the design value.
Unlike the first 10-year LMP, where five sources of PM10 emissions were identified and inventoried, the second 10-year LMP inventoried six sources as shown in Table 2 of this preamble. The first 10-year LMP assumed emissions from non-road equipment were zero, however, the second 10-year LMP
calculated these emissions to be less than 1% of the 2017 emissions inventory. The most significant of the PM10 emission sources for the Eagle River area are still paved road dust, windblown dust, and residential wood combustion. Like the emission inventory prepared for the first 10-year LMP, unpaved roads emissions are not included in the inventory for the second 10-year LMP. This is because since 2007, all the unpaved roads in Eagle River have been paved with either hot asphalt paving or surfaced with recycled asphalt product.

TABLE 22017 EMISSIONS INVENTORY IN TONS/DAY AND % OF TOTAL EMISSIONS
Spring break-up March, April tons/day percent
lotter on DSK11XQN23PROD with PROPOSALS1

Source category
Paved Roads
Wind-blown Dust from Paved Roads, Parking Lots and Un-Vegetated Areas
Fireplaces and Wood Stoves
Natural Gas Combustion
Exhaust, Tire and Brake Wear Emissions
from Motor Vehicles
Non-Road Equipment Emissions

0.026 0.39
0.0135 0.20

0.027 1.23
0.0132 0.60

Total

6.58 100

2.18 100

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3.71
2.48
0.35
0.009

56.3
37.6
5.31
0.13

Fall freeze-up October, November tons/day percent
02SEP1

1.06
0.73
0.35
0.009

48.6
33.4
16.0
0.41