Dames & Moore, 1999 - USDA Forest Service

Comparison of sulfate and aluminum supports the general conclusion of buffering by alumino-silicates.
Aluminum concentrations are lowered by aluminum hydroxide precipitation.
8.4.3 Western Portion of Site
8.4.3.1 Mine to Railroad Creek
Upslope surface water runon in the form of snowmelt and precipitation infiltrates into the soil and bedrock
through fractures and joints. Some of the water enters the mine workings, comes into contact with metal
salts formed on the walls of the workings, resulting in some of the metals going into solution. The water
flows out of the 1500-level main portal, which becomes the portal drainage, and flows into Railroad Creek.
Some of the water in the portal drainage infiltrates to shallow groundwater before discharging to Railroad
Creek. The shallow groundwater moves to the northeast, eventually discharging to Railroad Creek.
Referring to Figure 8.4-1, the 1500-level main portal drainage as represented by sampling station P-5 at the ,
Railroad Creek confluence, contained exceedances of surface water aquatic life criteria for cadmium,
copper, lead, and zinc in the spring and cadmium and zinc in the fail. The 1500-level main portal drainage
represents approximately 64 to 67 percent of the loading source of dissolved cadmium, copper, and zinc in
the spring, and reduces to less than 20 percent of the cadmium and zinc load to Railroad Creek in
September. The 1500-level main portal, therefore, represents the primary point source loading of dissolved
cadmium, copper, and zinc from the Site to Railroad Creek.
The groundwater component from the infiltration of overland flow from the 1500-level main portal drainage
may be accounted for by seeps SP-9, SP- 1 1, SP- 15 W, and SP- 1 5E, and/or as a portion of the unaccounted
groundwater base flow to Railroad Creek.
8.4.3.2 Honeymoon Heights to Railroad Creek
An intermittent drainage was observed in the Honeymoon Heights area, immediately east of the 1100- and
800-level mine portals and waste rock piles. The source of water is snowmelt and precipitation. The water
comes into contact with the waste rock before infiltrating into a mixture of mostly talus with some waste
rock near the base of the avalanche chute in which the drainage flows. The water is assumed to enter into
Railroad Creek as diffuse groundwater flow, potentially mixing with water flowing from seeps at sampling
stations SP-12 and SP-23, located between RC-1 and P-5; however, a dye test completed as part of the R1 to
test this hypothesis was inconclusive. These seeps flowed during the spring snowmelt and storm event
periods only and combined provided approximately 8 percent, 32 percent, and 7 percent of the loading of
cadmium, copper, and zinc to Railroad Creek, respectively.
8.4.3.3 Mill Area
1500-Level Waste Rock Piles
Upslope surface water runon in the form of snowmelt and precipitation infiltrates into the waste rock piles
situated to the west and east of the abandoned mill building. The water comes into contact with the
relatively low grade mineralization in the rock and is assumed to flow down to a layer of relatively low
permeability glacial till. The water discharges as seeps near the base of the waste rock piles, where the
glacial till contacts the ground surface.
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