Draft Environmental Impact Statement for Roca Honda Mine

Chapter 3. Affected Environment and Environmental Consequences
The soils within the permit area have a high potential for erosion. Storm water can transport soil
and sediment downslope and downstream, potentially increasing the turbidity of the receiving
surface waters and causing exceedance of surface water quality standards. Additionally,
developing the site would increase the impervious area, which can increase the amount of storm
water discharging from the site. However, with the planned storm water controls, the amount of
storm water discharge from the permit area is expected to decrease during the operational period
of the mine. Water flowing over alluvial stream sediments can potentially mobilize chemical
constituents found in the sediments or physically move those sediments.
Of particular concern are the stockpiles of nonore materials. While this material does not contain
enough ore for economic recovery, it is mineralized in the same way as the recoverable ore rock,
but to a lesser extent. As this material is brought to the surface, the minerals will oxidize and tend
to become more soluble in water. Storm water impinging on these stockpiles could be more
enriched in metals such as arsenic, molybdenum, selenium, uranium, and vanadium.
Table 9 shows the potential contaminants that could affect storm water quality at the site during
the construction and operation phases of the mine. Table 10 shows excavated materials that would
be stockpiled for some length of time at the mine surface that could potentially pollute surface
water or groundwater (through infiltration), if not properly controlled and managed.
Table 9. Potential site storm water contaminants from equipment and nonequipment
Material
Chemical/Physical
Description
Antifreeze Oily liquid – colorless or
colored
Cleaning
Solvents
Liquid – colorless, blue or
yellow green
Diesel fuel Liquid – clear, blue-green or
yellow
Gasoline Liquid – colorless, pale brown
or pink
Petroleum-
Based Grease
148 DEIS for Roca Honda Mine, Cibola National Forest
Use
Antifreeze coolant for
equipment
Storm Water Constituent
of Concern
Ethylene Glycol
Cleaning equipment Perchloroethylene, Methylene
Chloride, Trichloroethylene,
Petroleum Distillate
Fuel for generator,
trucks, heavy equipment
Petroleum Hydrocarbon,
Benzene, Ethyl Benzene,
Toluene, Xylene, Methyl
Tertiary-Butyl Ether
Fuel for trucks Petroleum distillates, Oil and
Grease, Naphthalene, Xylene
Semi-solid gel – reddish Lubricant Petroleum Hydrocarbon
Hydraulic fluid Oily Liquid – brown Hydraulic devices Mineral Oil
Oil Liquid – Oily liquid - brown Lubricant Petroleum Hydrocarbon
Barium chloride;
acids; sodium
hydroxide
Water-soluble crystal; liquid;
granule or solution
Water treatment plant
chemicals
Sediment Particulate earth materials -- Sediment
Material
stockpile areas
Source: Table 5-1 in MOP, Rev 1
Barium chloride, acids, sodium
hydroxide
Soluble metals --- Dissolved Metals - Arsenic,
Molybdenum, Selenium,
Uranium, and Vanadium