### Appendix F: Paved and Unpaved Road Dust

1996 and 2018 Inventories for Re-entrained Road Dust From Paved and Unpaved Roads

Paved and unpaved road dust em issions in the WRAP states were estimated to determ ine if road dust has an effect on visibility in each of the 16 Colorado Plateau Class I areas. In brief, paved road dust em issions were estim ated using the standard EPA approach, while unpaved road dust

em issions were estim ated using revised silt c ontents, revised activity data, and transport fractions. Paved and unpaved road dust PM 10 

### and PM 2. 5 

### em issions by state for 1996 and 2018 are provided in Tables 45 and 46. Paved road dust em issions increase by about three percent per year from 1996 to 2018, per the increase in vehicle m iles traveled. The incr ease varies by state, with the largest projected growth in vehicle travel in W a s h ington, Idaho, and Utah. Unpaved road dust em issions are projected to decr ease between 1996 and 2018, by about 0.75% per year, because of reduction s in unpaved ro ad m ileage over tim e as m o re roads are paved. As a result, unpaved road dust em issions are about 80% of road dust PM 10 

### em issions in 1996, and about 65% of road dust PM 10 

### em issions in 2018. Overall, road dust PM 10 

### em issions increase by about 6% from 1996 to 2018.

Table 45: 1996 WRAP States Fugiti ve Road Dust Emissions (TPY) State Paved Road Dust Unpaved Road Dust Total Road Dust P M 10 

### P M 2. 5 

### P M 10 

### P M 2. 5 

### P M 10 

### P M 2. 5 A r i z o n a * 7,31 8 1,83 0 1 8
, 6 0 5 2,79 1 2 5
, 9 2 3 4,62 0 C a l i f o r n i a * 35,6 4 3 8
, 9 1 1 8 6
, 4 7 4 14,0 9 0 122, 1 1 7 23,0 0 1 C o l o r a d o * 7,89 7 1,97 4 3 0
, 6 0 1 4,59 0 3 8
, 4 9 8 6,56 4

Idaho * 3,50 2 876 28,3 04 4,24 6 31,8 06 5,12 1 M o n t a n a 2
, 9 0 9 7 2 7 15,7 9 6 2,36 9 18,7 0 5 3,09 7 Nevada * 2,52 8 632 9,46 0 1,44 9 11,9 88 2,08 1 New M e x i c o * 5,39 5 1,34 9 2 7
, 9 7 2 4,19 6 3 3
, 3 6 7 5,54 5 North Dakota 2,46 1 615 34,4 19 5,16 3 36,8 80 5,77 8

O r e g o n * 8,06 7 2,01 7 1 9
, 0 7 8 2,86 2 2 7
, 1 4 4 4,87 8 South Dakota 2,29 6 574 46,1 99 6,93 0 48,4 95 7,50 4 Utah * 3,68 0 920 16,0 40 2,40 6 19,7 21 3,32 6 W a s h i n g t o n 7,80 4 1,95 1 3 4
, 3 6 5 5,15 5 4 2
, 1 6 9 7,10 6 Wyom i n g * 1,82 3 4 5 6 3
, 4 4 9 5 1 7 5
, 2 7 1 9 7 3 13 states total 91,3 22 22,8 31 370, 762 56,7 63 462, 084 79,5 94 * 9 GCVTC States 75,8 53 18,9 63 239, 983 37,1 46 315, 835 56,1 09

NM Regi onal Haze SIP Page F-1 12/ 31/ 03

### Table 46: 2018 WRAP States Fugiti ve Road Dust Emissions (TPY) State Paved Road Dust Unpaved Road Dust Total Road Dust P M 10 

### P M 2. 5 

### P M 10 

### P M 2. 5 

### P M 10 

### P M 2. 5 A r i z o n a * 12,6 1 8 3
, 1 5 4 1 2
, 9 7 6 1,94 5 2 5
, 5 9 4 5,09 9 C a l i f o r n i a * 59,7 9 4 1 4
, 9 5 0 5 6
, 4 4 7 9,19 8 1 1 6
, 2 4 2 24,1 4 8 C o l o r a d o * 13,7 7 1 3
, 4 4 2 3 6
, 9 5 6 5,54 4 5 0
, 7 2 8 8,98 6

I d a h o * 7,54 8 1,88 7 1 7
, 9 7 6 2,69 7 2 5
, 5 2 4 4,58 4 M o n t a n a 4,79 6 1,20 1 1 7
, 9 0 7 2,68 6 2 2
, 7 0 3 3,88 7 N e v a d a * 5,01 9 1
, 2 5 6 7
, 1 9 8 1,10 2 12,2 1 7 2,35 8 New M e x i c o * 10,1 9 8 2
, 5 5 1 3 2
, 7 3 0 4,90 9 4 2
, 9 2 8 7,46 1 North Dakota 3,72 3 931 34,2 55 5,13 9 37,9 78 6,07 0

O r e g o n * 14,6 8 4 3
, 6 7 2 1 2
, 1 5 8 1,82 5 2 6
, 8 4 2 5,49 7 South Dakota 3,72 3 931 50,2 39 7,53 7 53,9 62 8,46 8 U t a h * 7,54 1 1,88 3 2 0
, 4 8 7 3,07 3 2 8
, 0 2 8 4,95 7 W a s h i n g t o n 18,6 8 1 4
, 6 6 8 2 2
, 9 9 1 3,44 9 4 1
, 6 7 2 8,11 8 Wyom i n g * 3,01 9 7 5 6 3
, 7 1 9 5 5 8 6
, 7 3 8 1,31 4
13 states t o t a l 165, 1 1 5 4 1
, 2 8 2 3 2 6
, 0 4 0 49,6 6 6 4 9 1
, 1 5 5 90,9 4 7 * 9 GCVTC States 134, 192 33,5 51 200, 648 30,8 53 334, 840 64,4 04



### Road Dust significance analysis and finding for the Colorado Plateau 16 Class I areas

Section 309 of the Regional Haze Ru le requ ires the following for Road Dust:

Area sources of dust emissions from paved and unpaved roads. The plan must include an assessment of the impact of dust emissions from paved and unpaved roads on visibility conditions in the 16 Class I Areas. If such dust emissions are determined to be a significant contributor to visi b i lity impairment in the 16 Cl ass I areas, the S t ate must implement emissions m anagement strategies to address the impact as necessary and appropriate.

As described above, road dust em issions inventories were devel oped, and the significance of road dust was then tested using the regional air quality m o del at the Regional Modeling Center. The m odeling results are presented in Table 47, below.

NM Regi onal Haze SIP Page F-2 12/ 31/ 03NM Regional Haze SIP Page F-3 12/31/03 

### Table 47: Road Dust Sign ificance Modeling Results

Colorado Plateau

Class I Areas 2018 Base Case (Mm -1 ) 2018 No Road

Dust (Mm -1 ) EPA Natural Conditions Worst 20% Days (Mm -1 ) Bext change 

### No Road Dust (Mm -1 ) Bext change No Road Dust (%) dv Change No Road Dust (dv)

Arches NP 25.91 25.63 20.12 0.29 1.42 0.14 Black Canyon of

Gunnison NP 32.84 32.20 20.26 0.63 3.13 0.31
Bryce Canyon NP 24.24 23.99 20.12 0.25 1.24 0.12 Canyonlands NP 23.89 23.71 20.08 0.18 0.89 0.09 Capitol Reef NP 25.56 25.30 20.18 0.26 1.29 0.13 Flat Tops Wilderness 28.55 28.37 20.28 0.19 0.92 0.09

Grand Canyon NP 27.78 27.53 20.08 0.25 1.22 0.12

Maroon BellsSnowmass Wilderness 31.78 31.46 20.30 0.32 1.57 0.16

Mesa Verde NP 34.47 34.21 20.18 0.26 1.30 0.13

Mount Baldy Wilderness 41.63 41.26 20.04 0.37 1.87 0.19

Petrified Forest NP 32.46 32.22 20.08 0.24 1.20 0.12

San Pedro Parks

Wilderness 28.90 28.65 20.18 0.24 1.21 0.12
Sycamore Canyon Wilderness 35.34 34.95 20.34 0.39 1.92 0.19

West Elk Wilderness 31.15 30.85 20.26 0.30 1.47 0.15
Weminuche Wilderness 29.93 29.77 20.20 0.16 0.80 0.08
Zion NP 25.57 24.95 20.06 0.61 3.05 0.30



### In the regional model, the road dust inventory was set to zero for the entire modeling domain, other 2018 base case emissions were included as normal, and the resulting modeled effect of road dust emissions were calculat ed in terms of the impact on visibility at each of the 16 Colorado Plateau Class I areas, on the predicted worst 20% days. The modeled regional impact of road dust emissions ranged from 0.31 deciviews (3.1% of natural conditions to be reached by 2064) at the Black Canyon of the Gunnison Nati onal Park to 0.08 decivi ews (0.8% of natural conditions to be reached by 2064) at the Weminuch e Wilderness. These data were presented and discussed by WRAP’s Modeling and Mobile S ources Forums, the Oversight Committees, and the Board of Directors, and all agreed that th e regional impacts of road dust emissions are not significant at the 16 Colorado Platea u Class I areas at this time.

The Board of Directors directed the Technical Foru ms to continue to track and evaluate road dust emissions, as dust aerosols have been shown to be an important contri butor to visibility impairment at many WRAP region Class I areas. The finding of no signi ficance is a rigorous test, as no windblown dust emission s are included in the model, so the modeled significance of road dust is not masked by a larg e mass of other dust emissions.