Dames & Moore, 1999 - USDA Forest Service

Portal Drainage
Groundwater infiltrating from the portal drainage overland flow is a component of the unaccounted load
(groundwater) of copper, cadmium and zinc to Railroad Creek.
Waste Rock Piles
Several seeps flow seasonally from near the base of west and east waste rock piles. Two seeps, SP-6 and
SP-I5W contain concentrations of cadmium, copper, zinc, beryllium and manganese above the MTCA
groundwater levels. Seeps SP-6 and SP-15W account from less than 2 percent of the cadmium, copper
and zinc loading to Railroad Creek measured at RC-2. Seep SP-11 contained arsenic and SP-1OE
contained iron above groundwater threshold levels.
Mill Building
One primary seep, SP-7, flows seasonally fiom ,the abandoned mill building 'and contained cadmium,
copper and zinc above MTCA groundwater levels. The seep accounts for less than 2 percent of the
cadmium,:4 percent of the copper, and 2 percent of the zinc loading to Railroad Creek as measured at RC-
2.
Seeps SP- 12 and SP-23
Seeps SP-12 and SP-23 are assumed to represent Honeymoon Heights drainage and flow seasonally from
the south bank of Railroad Creek to the west of the portal drainage. These seeps contain copper,
cadmium, and zinc concentrations above MTCA groundwater levels. The two seeps combined account
for approximately 8 percent of the cadmium, 3 1 percent of the copper, and 7 percent of the zinc loading to
Railroad Creek as measured at RC-2.
The loading analysis further demonstrates that overland flow from the 1500-level main portal is the
primary source area contributing dissolved cadmium, copper, and zinc concentrations to Railroad Creek.
Source areas including the waste rock piles, mill building, Honeymoon Heights drainage, and
groundwater infiltrating fiom the 1500-level main portal overland flow also contribute metals, primarily
copper, cadmium and zinc to Railroad Creek, but represent significantly lower load sources as compared
to the overland from the 1500-level main portal. Based on the physical characteristics of the west portion
of the site, a high likelihood exists that infiltration of overland flow fiom the 1500-level main portal
contributes to dissolved copper, cadmium and zinc to groundwater in the western portion of the site as
well as to groundwater beneath the tailings piles.
East Portion of the Site
The east portion of the Site includes the tailings piles and Copper Creek diversion. The groundwater
underlying the portion of the Site east of the Copper Creek diversion, including tailings piles 1, 2, and 3.
~roundwate; bellow the tailings piles contains concentrations of arsenic, cadmium, beryllium, copper,
lead, manganese, zinc, and iron above MTCA groundwater levels. Cadmium, copper and zinc were not
identified in water within the tailings which indicates that these constituents most likely originate from
the western portion of the site.
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SUMMARY.doc
1769340S-O 09Uuly 28,1999; 12: 16 PM:DRAFI' FINAL RJ REPORT ES-8