Preliminary Public Dose Evaluation in Support of the Development of the
November 2012
Rare Element Resources Bear Lodge Project
24
RG 3.59 suggests that particulate emission estimates from ore pads subject to wind erosion be 10
percent of that calculated for the tailings pile. Ten percent of the TSF estimate is 9.72 x 10
-7
g m
2
s
-1
(30.7 g m
2
y
-1
). A value of 1.36 x 10
-6
g m
2
s
-1
(43 g m
2
y
-1
) is cited in an example provided in
Section 1.2.2 in RG 3.59. The latter was selected as the dust emission rate for the LGOS used for
this evaluation, because it is conservative.
4.2.2.2
Bull Hill Mine
Dust emission from the BHM was estimated using methods described in Chapters 11.9 and
13.2.2 of
Compilation of Air Pollutant Emission Factors, Volume I: Stationary Point and Area
Sources
AP-42 (EPA, 1995). It includes the contributions from blasting, truck loading, dozer
operations and haul vehicle traffic.
Dust Emission from Blasting
The total suspended particulate (particles ≤ 30 microns) emission from blasting at the BHM was
estimated using the equation below, adopted from Table 11.9-2 of AP-42 for overburden:
= 0.00022
1.5
Where:
EF
B
= dust emission factor for blasting (kg blast
-1
)
A
= horizontal area with blasting depth ≤ 21 m (assumed as 1,590 m
2
, the geometric
mean reported in Table 11.9.3 of AP-42)
Based on the equation and assumptions above, the dust emission factor for blasting at the BHM
is 13.95 kg blast
-1
. The number of blasts per year is estimated at 260, resulting in a dust emission
rate of 3,627 kg y
-1
.
