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Dames & Moore, 1999 - USDA Forest Service

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Subsurface Soils<br />

Cadmium, copper, and iron were identified as PCOCs in thirteen subsurface soil samples collected from the<br />

tailings piles.<br />

8.3.2.3 Wind-blown Tailings<br />

Iron was identified as a PCOC in five samples collected of wind-blown tailings downwind of the tailings<br />

piles.<br />

8.3.2.4 Holden Village<br />

Beryllium and iron were identified as PCOCs in nine surface soil samples collected in Holden Village<br />

(included four historical soil samples collected by others).<br />

8.3.2.5 Baseball FieldICampground Area<br />

Iron was identified as a PCOC in one surface soil sample collected in the baseball field.<br />

8.3.2.6 Holden USFS Guard Station<br />

Arsenic was identified as a PCOC in one sample collected and analyzed fiom the Holden USFS Guard<br />

Station.<br />

8.3.3 Surface Water<br />

Surface water samples were collected in April. MayIJune, July, and SeptemberIOctober in order to<br />

characterize water quality during the low flow conditions, the rising limb of the hydrograph, the peak and<br />

declining limb of the hydrograph, and low flow conditions which are expected to generally persist between<br />

September and March when spring thaw begins. The samples were analyzed for total recoverable and<br />

dissolved metals and conventional parameters as discussed in detail in Section 5.0. Three of the Railroad<br />

Creek stations were also analyzed for polychlorinated biphenyls (PCBs) and total petroleum hydrocarbons<br />

(TPH as gasoline, diesel, and heavier than diesel'range).<br />

8.3.3.1 Railroad Creek<br />

Upstream of Site<br />

Data from upstream stations were analyzed statistically and the 90' percentile concentrations were<br />

calculated and then compared to water quality criteria. The area background concentrations (as determined<br />

by the total data set) for arsenic, beryllium, cadmium, chromium, copper, iron. lead, mercury, nickel,<br />

selenium, silver, and zinc were compared to WQC. For those metals requiring hardness correction,<br />

background values were compared to the WQC using a minimum hardness of 6.7 ppm. This value was<br />

selected as it is representative of the lower hardness values obtained in the R1 data and provides the most<br />

conservative WQC levels. Hardness concentration in Railroad Creek varied fiom 6.7 to 31 mg/L<br />

dependent upon the station location and sampling event. The lowest hardness values generally occurred<br />

in stations upstream of the Holden Mine. The background values were also compared to WQC based on<br />

\\DM-SEAI\VOLI\COMMOMW~WPDATA\OO~\REPORTSWOLDEN-~UU\B-O,~OC<br />

8-27<br />

17693-005-019Uuly 28. <strong>1999</strong>;10:24 AM;DRAFT FINAL RI REPORT

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