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### ARIZONA DEPARTMENT OF ENVIRONMENTAL QUALITY

Payson Update using MOVES November 8, 2013

The Payson Limited Maintenance Plan (LMP) update su bmitted to EPA January, 2012, contained Exhaust, Tire and Brake PM 10 emission estimates using the EPA NMIM (Mobile6.2) model. Table 3, from that document, summarizing these emissions est imates, is shown below:

(Table 3: Yearly VMT, and PM 10 Vehicular Emissions in 2007 in Payson PM 10 Non-Attainment Area)

Roadway Name or Roadway Class Yearly VMT (2007) Fugitive

Dust PM 10 (tpy) Tire, Exhaust,

& Brake PM 10 (tpy)

Paved Roads SR-87 65,046,464 54.29 5.73 SR-260 27,448,297 22.91 2.10 Urban Minor Arterial 16,331,967 13.63 1.00 Rural Major Collector 5,160,532 4.31 0.34 Urban Collector 4,378,434 3.65 0.26 Urban Local 438,915 0.37 0.03 Rural Minor Collector 196,747 0.16 0.01 Total Paved 119,001,356 99.33 9.47 Unpaved Roads Rural Local 514,549 105.10 0.03 Total Unpaved 514,549 105.10 0.03
Total PM10 emissions 119,515,905 204.43 9.50 *: tpy: tons per year

ADEQ was asked by EPA to recalculate emission estim ates for exhaust, tire, and brake wear using the MOVES model. To establish reasonable MOVES data, MO VES was run for Gila County with the default model values for both 2008 and 2011 and then compar ed to the EPA generated MOVES runs reported in the 2008 and 2011 NEI on-road emission inventory (u sing MOVES). The NEI total tons per year of onroad PM 10 was larger than the value obtained from running MOV ES itself. ADEQ contacted EPA about the discrepancy, and David Brzezinski (EPA OTAQ ASD ) indicated “The default values in MOVES2010b do not (and cannot) reflect all of the i nformation we have about counties. When we do the NEI, we use county specific databases (CDBs) that c ontain much more of the information we have about counties, both information from states and our own estimates. The data we used can be obtained on the EPA web site for the 2008 and 2011 NEI.” Given the indication from EPA regarding the specificity of data used to construct the NEI, ADEQ determined tha t using the emission estimates from the NEI were likely more accurate than the default MOVES model r uns.

The tons per year on-road emissions data from the 2 008 and 2011 NEI are shown in Table 1. Due to differences in model inputs and outputs between NMI M and MOVES, a breakdown of the roadway classes that was originally provided in the Payson maintenance plan (Table 3) was not possible for the more recent MOVES data obtained through the NEI. I nstead, an emission factor of grams/VMT (gm/vmt) was calculated for each of the NEI years u sing the total emissions and VMT estimates.2

The default VMT EPA used for the county-level emiss ion estimates in the NEI is from the Highway Performance Monitoring System (HPMS). For this anal ysis, ADEQ also used HPMS data from the Arizona Department of Transportation (ADOT).

Table 1: Annual MOVES / NEI Mobile Source Emissions Estimates, Gila County Annual VMT, and resultant MOVES / NEI emission factors

NEI Year Gila County Yearly VMT Total PM 10 Mobile Emissions (tpy) Gila County gm/vmt

2008** 814,680,000 56 0.082 2011*** 621,595,000 45 0.066
** http://www.azdot.gov/docs/default-source/planning/d vmt-2008.pdf?sfvrsn=2
*** http://www.azdot.gov/docs/default-source/planning/d vmt-2011.pdf?sfvrsn=6

The emission factors that were calculated in Table 1 were then linearly interpolated to 2007 to obtain a 2007 emission factor which could then be applied to the 2007 VMT data from the Payson NA. The calculation for this interpolation method is provid ed below:

The extrapolation is as follows: A = 0.0657 gm/vmt for 2011 B = 0.0820 gm/vmt for 2008 C = (A – B) / 3 = - 0.005 gm/vmt change in emission factor per year D = B – C = 0.082 + 0.005 = 0.087 gm/vmt emission f actor for 2007

Using the 2007 interpolated MOVES / NEI mobile sour ce emission factor and the 2007 VMT estimates from table 3, PM10 emissions from exhaust, tire, an d brake were estimated for the Payson NA. A comparison of the emission estimates using NMIM (Mo bile 6.2) and MOVES / NEI is provided below in Table 2.

Table 2 Comparison of Mobile Emission Estimates usi ng Mobile 6.2 and MOVES

Mobile Source
Model Emission

Factor (gm/vmt) Payson NA

VMT Total Tire,

Exhaust, & Brake PM10 Emissions (tpy) Fugitive

Dust PM10 Emissions (tpy) Total

Mobile
PM 10 Emissions NMIM (Mobile 6.2) 0.072 119,515,905 9.50 204.43 213 .93 MOVES / NEI 0.087 119,515,905 11.52 204.43 215.95

As a result of this analysis, there was a change of +2.02 tons per year in total on-road PM 10 emissions as a result of going from the Mobile6.2 results to the M OVES results, thus only a small (+1.0%) change in t he Payson Area Motor Vehicle Growth Analysis adding 0. 1 μg/m 3 to the Motor Vehicle Regional Analysis value.3

(From the “2011 Update of the Limited Maintenance P lan for the Payson PM 10 Maintenance Area” we have Figure 4.2, a computation of the Payson Area M otor Vehicle Growth Analysis and how it relates to the MOS.) (Figure 4.2 Revised Payson Area Motor Vehicle Growt h Analysis)

DV + (VMT pi ∗ DV
mv ) < MOS Where: DV = the area’s design value based on the most rec ent 5 years of quality assured data in μg/m 3

VMT pi = the projected percentage increase in VMT over th e next ten years 1

DV
mv = motor vehicle design value based on on-road mobi le portion of the attainment year inventory in μg/m 3 MOS = margin of safety for the relevant PM 10 standard for a given area: 98 μg/m 3 for the 24-hour standard Applying the test for the 24-hour average PM 10 standard yields the following result: DV = 66 μg/m 3

VMT pi = 23.8 percent
DV
mv = 40.9 μg/m 3 (estimated using the PM 10 emissions in Table 4-1) MOS = 98 μg/m 3 for 24-hour average PM 10 standard

66 + (0.238 ∗ 40.9) = 75.7 μg/m 3

Because the Motor Vehicle Regional Analysis is less than 98 μg/m 3 , the area continues to pass this criterion for the 24-hour average PM 10 standard.

1 Based on a trend analysis of the most recent 10 ye ars of HPMS data, ADEQ calculated an increase in VM T to be approximately 20,000,000 per year or 200,000,000 ov er a 10 year period for Gila County. Based on an an nual VMT of 840,000,000 for the county in 2008 it represents an increase of 23.8%. The same percentage (23.8%) is applied for the Payson VMT growth projection.