Prefeasibility Access Road Design-Revised
31
As discussed above suppression of dust for unpaved roads can be accomplished
with the use of water or chemicals. Dust can be mitigated for paved roads
through a combination of sweeping, vacuuming, and/or water flushing.
UNPAVED PORTION
Water Suppression
This analysis provides an estimate of the water required for dust suppression on
the Warren Peak Route (application intensity) as determined by Control of
Fugitive Dust Sources, EPA-450/3-88-908 (1988).
The annual weighted daily average water consumption necessary for the
reduction of 75% of dust for the initial unpaved portion is 35,137 gallons per
day. Water consumption for the final aggregate coverage of the entire road
would be an annual weighted daily average of 59,762 gallons per day.
As described in the Miller Creek Route discussion above, Equation 3-2 resulted in
an application rate of 0.0034 gal/ft2 per hour to achieve the targeted 75%
control efficiency during non-summer months, and 0.0045 gal/ft2 per hour
during summer months (See Warren Peak Route, Table 3). This estimate does
not account for traffic other than RER vehicles (i.e. there is existing traffic on the
road that is not accounted for in this review).
Table 4, Warren Peak Route, Estimation of Unpaved Road Emissions (attached)
presents a theoretical calculation of emissions that result from RER vehicle traffic
on the unpaved portion of the Warren Peak Route and the corresponding
efficiency of water usage assuming the application rates from Table 3. The
estimated uncontrolled PM10 emissions for this road, assuming only the RER
traffic, are 0.11 tons/day for the initial build, and 0.18 tons/day at the final
aggregate coverage.
Assuming 75% control, the application of 35,137 gallons of water per day would
result in PM10 emissions of 0.03 tons/day (reduction of 0.08 tons/day of PM10
compared to no control) for the initial build. After the final aggregate coverage,
application of 59,762 gallons of water per day would result in PM10 emissions of
0.05 tons/day (reduction of 0.13 tons/day of PM10 compared to no control).
This table also demonstrates that water application beyond 75% is less efficient,
and requires more water to control each ton of dust beyond the 75% control
level.
Chemical Suppression
As described for the Miller Creek Route, this analysis assumed the use of chloride
as a chemical suppressant option for the unpaved portion of the Warren Peak
Route. Chemical suppressants are not used for paved roads.
