Preliminary Public Dose Evaluation in Support of the Development of the
November 2012
Rare Element Resources Bear Lodge Project
26
Dust Emission from Haul Trucks
The total suspended particulate (particles ≤ 30 microns) emission from haul truck travel at the
BHM was estimated using the equation below, adopted from Chapter 13.2.2 of AP-42 for
unpaved road surfaces:
= ( 12) ⁄ ( 3)⁄
Where:
EF
HT
= TSP emission factor (lbs per vehicle mile traveled [VMT])
s
= silt content (8.4 percent for western coal mines, from Table 13.2.2-1 of AP-42)
W
= mean vehicle weight in tons (assumed 200 tons)
k,a,b = empirical constants from Table 13.2.2-2 of AP-42. (k=4.9, a=0.7, and b=0.45)
Based on the equation and assumptions above, the dust emission factor for haul trucks at the
BHM is 25.3 lb VMT
-1
(11.5 kg VMT
-1
). The VMT (vehicles traveled in a year by haul trucks) is
estimated using the follow equation:
= ℎ
Where:
VMT = VMT y
-1
by haul trucks
f
t
= fraction of time vehicles are traveling on haul roads (assumed 0.7)
h
= work h d
-1
(20 h d
-1
)
D
= work d wk
-1
(5 d wk
-1
)
S
= average speed of haul truck (10 mi. h
-1
)
W
= number of wk per year (52 wk y
-1
)
N
= number of haul trucks (9; from(RER, 2012a)
Using this equation, the total VMT is 327,600 mi. Given that the VMT is an annual rate, the
estimated dust emission from these vehicles is estimated to be 3.75 x 10
6
kg y
-1
.
Summary of Dust Emission from Four Operations Considered at the BHM
Table 4.3 summarizes the dust emission estimates for the BHM as well as other parameters used
to model off-site impacts of dust emissions. The total dust emission rate from all sources at the
BHM is 4.1 x 10
6
kg y
-1
.
