Dames & Moore, 1999 - USDA Forest Service

9.2.4.1 Portal Drainage
The chemical loading analyses completed during the RI accounted for the overland flow and
groundwater loading sources of dissolved metals to Railroad Creek.
Conclusions associated with the water quality and chemical loading of component inflow
sources including the portal drainage, groundwater, the waste rock piles, mill building, Copper
Creek diversion and seeps SP-12 and SP-23 are provided below.
Water quality measured at P-1 (main portal)'and P-5 (confluence with Railroad Creek) as overland flow
indicates that metals presented in the following table were above regulatory surface and groundwater quality
regulatory levels.
Surface
Water
Criteria
Groundwater
Criteria
Locations
P- 1
P-5
P-1
, July 1997
Cd, Cu, Pb, Zn, pH
C4 Cu, Pb. Zn, pH
Cd, Cu, Pb, Zn, SO4,
PH
These dissolved metals concentrations are influenced by seasonal changes in groundwater flow discharging
from the main portal. The loading analysis reflects these differences.
MayIJune - The portal drainage discharge flows were as high as approximately 3.5 cubic feet
per second (cfs) in ~a~ 1997 and approximately 1.8 cfs in May 1998, and accounts for more
than 65 percent of the load of dissolved cadmium, copper, and zinc to the creek during the
spring snowmelt period.
OctoberISeptember - Discharge flow rates were measured as low as approximately 0.10 cfs.
The drainage accounts for less than 1 percent of the copper load, and approximately one-third
of the cadmium and zinc load to Railroad Creek.
The portal drainage overland flow represents the primary source of dissolved copper, cadmium and zinc to
Railroad Creek during spring conditions; however during the fall, the concentrations of these metals is
greatly reduced.
9.2.4.2 Groundwater
May 1997
C4 Cu, Pb, Zn, pH
Cd, Cu, Pb, Zn, pH
As, Be, Cb Cu, Pb, Zn,
SO,, pH
September 1997
Cd, Cu, Zn
cd, zn, pH
Cd, SO4, TDS
The groundwater geochemistry in the east and west portions of the Site is different due to the different source
rock types (mine ore deposit versus tailings) and differences in oxygen availability and water flow.
Groundwater data from monitoring wells and expressed as seeps and springs were used to evaluate
groundwater quality associated with the Site, particularly for the west side of the Site.' Groundwater
underlying the Site is not currently being used as drinking water.
West Portion of the Site
May 1998
Cd, Cu, Pb, Zn, pH
Cd, Cu, Pb, Zn, pH
Cd, Cu, Fc. Pb, Zn, SO,,
TDS, pH
The west portion of the site includes the following source areas: underground mine and Honeymoon Heights,
portal drainage, west waste rock piles, and the mill building. Groundwater monitoring wells are not present
in these areas; therefore, seep water quality was used to evaluate groundwater quality exceedances, source
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17693-00S-019Uuly 28. 1999;10:07 AM;DRAFT FINAL RI REPORT
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