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Dames & Moore, 1999 - USDA Forest Service

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8.3.4.1 Western Portion of Site<br />

During the MayIJune 1997 sampling events, the results of the analysis indicated concentrations of cadmium,<br />

copper, and zinc above groundwater regulatory threshold (MTCA Method B) for the western portion of the<br />

Site. Two seeps sampled below the west waste rock pile (SP-6 and SP-I5E) were found to have<br />

concentrations of beryllium and manganese slightly above the MTCA groundwater levels, respectively.<br />

Seeps SP-11 contained arsenic and SP-IOE contained iron above groundwater threshold levels.<br />

The results of the SeptemberIOctober 1997 sampling event detected concentrations of cadmium, copper, and<br />

zinc below those measured during the MayIJune sampling events, but above groundwater MTCA Method B<br />

levels.<br />

8.3.4.2 Eastern Portion of Site<br />

During the MayIJune sampling events, the results of the analyses indicated that concentrations of cadmium,<br />

copper, iron, and zinc were above the MTCA Method A or B groundwater levels. The area of the highest<br />

groundwater concentrations was found in tailings pile 1. The concentrations in wells and seeps associated<br />

with tailings piles 2 and 3 were generally lower than for tailings pile 1. For tailings piles 1 and 2.<br />

concentrations of cadmium, copper, arsenic, beryllium, manganese, iron, and zinc were also detected<br />

slightly above the groundwater regulatory levels. For tailings pile 3, lead, beryllium, manganese, cadmium,<br />

copper, and iron were detected above the groundwater regulatory levels.<br />

In comparison, the results of the SeptemberIOctober sampling detected higher concentrations of iron, and<br />

lower concentrations of the other metals found in the MayIJune sampling event at all tailings piles.<br />

Cadmium, copper, arsenic, manganese and iron were detected above the groundwater regulatory criteria for<br />

tailings piles 1 and 2. Iron and manganese exceeded groundwater MTCA levels were detected for tailings<br />

pile 3 for the SeptemberIOctober event. iron concentrations were generally much higher in the eastern<br />

portion of the Site during the SeptemberlOctober sampling event than during the MayIJune event.<br />

8.3.4.3 Lucerne USFS Guard Station Well<br />

The water supply well located at the USFS Guard Station in Lucerne was sampled during the<br />

SeptemberIOctober event. The results of the analyses indicated concentrations of iron slightly above the<br />

secondary MCL (less than 20 percent higher), a non-health based standard.<br />

8.3.5 Sediment<br />

8.3.5.1 Railroad Creek<br />

Sediment in Railroad Creek was observed to consist primarily of relatively large grain size gravel, cobbles,<br />

and boulders. The grain size of the stream substrate decreases slightly from the Site to the mouth of<br />

Railroad Creek. Stream sediment samples were collected by others in 1994, 1995, and 1996. The results<br />

indicate a general increase in iron, zinc, and copper concentrations from upstream of the Site to River Mile<br />

7. However, the metal concentrations were below the Ecology freshwater sediment quality guidance value<br />

(FSQV).<br />

\U)M-SEAI\VOLI\COMMOMWP\WPDATA\OOS\REWRTS\HOLDEN-~\R~~-O.~OC<br />

8-3 1<br />

17693-005-019Uuly 28. <strong>1999</strong>;10:37 AM;DMFT FINAL RI REPORT

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