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Dames & Moore, 1999 - USDA Forest Service

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areas and loading to Railroad Creek. Concentrations of cadmium, copper, and zinc were above the MTCA<br />

Method B levels in groundwater in the western portal of the site.<br />

Portal Drainage<br />

Groundwater infiltrating from the portal drainage overland flow is a component of the unaccounted load<br />

(groundwater) of copper, cadmium and zinc to Railroad Creek.<br />

Waste Rock Piles<br />

Several seeps flow seasonally from near the base of west and east waste rock piles. Two seeps, SP-6 and SP-<br />

15W contain concentrations of cadmium, copper, zinc, beryllium and manganese above the MTCA<br />

groundwater levels. Seeps SP-6 and SP-15W account from less than 2 percent of the cadmium, copper and<br />

zinc loading to Railroad Creek measured at RC-2. Seep SP- 1 1 contained arsenic and SP- I OE contained iron<br />

above groundwater threshold levels.<br />

Mill Building<br />

One primary seep, SP-7, flows se,asonally from the abandoned mill building and contained cadmium, copper<br />

and zinc above MTCA groundwater levels. The seep accounts for less than 2 percent of the cadmium, 4<br />

percent of the copper, and 2 percent of the zinc loading to Railroad Creek as measured at RC-2.<br />

Seeps SP-12 and SP-23<br />

Seeps SP-12 and SP-23 are assumed to represent Honeymoon Heights drainage and flow seasonally from the<br />

south bank of Railroad Creek to the west of the portal drainage. These seeps contain copper, cadmium, and<br />

zinc concentrations above MTCA groundwater levels. The two seeps combined account for approximately 8<br />

percent of the cadmium, 31 percent of the copper, and 7 percent of the zinc loading to Railroad Creek as<br />

measured at RC-2.<br />

The loading analysis hrther demonstrates that overland flow from the 1500-level main portal is the primary<br />

source area contributing dissolved cadmium, copper, and zinc concentrations to Railroad Creek. Source<br />

areas including the waste rock piles, mill building, Honeymoon Heights drainage, and groundwater<br />

infiltrating from the 1500-level main portal overland flow also contribute metals, primarily copper, cadmium<br />

and zinc to Railroad Creek, but represent significantly lower load sources as compared to the overland from<br />

the 1500-level main portal. Based on the physical characteristics of the west portion of the site, a high<br />

likelihood exists that infiltration of overland flow from the 1500-level main portal contributes to dissolved<br />

copper, cadmium and zinc to groundwater in the western portion of the site as well as to groundwater<br />

beneath the tailings piles.<br />

East Portion of the Site<br />

The east portion of the Site includes the tailings piles and Copper Creek diversion. The groundwater<br />

underlying the portion of the Site east of the Copper Creek diversion, including tailings piles 1, 2, and 3.<br />

Groundwater bellow the tailings piles contains concentrations of arsenic, cadmium, beryllium, copper, lead,<br />

manganese, zinc, and iron above MTCA groundwater levels. Cadmium, copper and zinc were not identified<br />

in water within the tailings which indicates that these constituents most likely originate from the western<br />

portion of the site.<br />

O:\WPDATAUX)mPORTSWOLDEN-2WO.doc 9-5<br />

17693-005-019Uuly 28. <strong>1999</strong>:10:07 AM:DRAFT FINAL R1 REPORT

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