Dames & Moore, 1999 - USDA Forest Service

Windblown Tailings Material
The erosion of the tailings from the piles has resulted in the deposition of the materials on the ground
surface adjacent to and downwind of the Site. The majority of the windblown tailings deposits'were
found to be less than several millimeters in thickness. Concentrations of all metals analyzed, other than
iron, were below the regulatory standard for soil. Based on the results of human health and ecological
risk assessment, the potential for adverse effects from the iron concentrations was low.
Riprap and Soil Source Evaluation
An evaluation was completed to identify a source of riprap within the Railroad Creek drainage and
sources of granular soil that may be needed for remedial actions. The results of the evaluation confirmed
that the rock quality within the existing quany is relatively poor. However, a potential source of higher
quality rock exists nearer the Site as a talus deposit (cobble- to boulder-sized rock at the base of a bedrock
outcrop). The riprap source had been iliminated by the USFS during the Site work between 1989 and
1991' due to safety considerations; however, it appears feasible to design measures to mitigate the
concerns. A potential source of granular soil was identified near tailings pile 3.
Winston Home Sites Fuel Storage Tanks
The results of the evaluation of the Winston Home Sites identified up to 38 underground storage tanks
(USTs) remaining in the area. No indications of petroleum hydrocarbons were noted in soils exposed in
backhoe test pits excavations completed adjacent to seven of the tank locations. It was reported that
some, if not all, of the tanks were pumped during the 1960s in order to supply fuel for Holden Village.
All of the tanks appeared to be less than 1000 gallons in size and, therefore, not regulated as USTs. These
tanks have been sufficiently evaluated.
POTENTIAL ENVIRONMENTAL CONCERNS
The following potential environmental concerns were identified at the Site:
Seasonal Exceedances of Water Quality Criteria
The discharge of portal drainage water and Site groundwater in the western portion of the
site (represented as seeps) into Railroad Creek results in exceedances of water quality
criteria for cadmium, copper, lead, and zinc during the spring snowmelt period at the Site in
Railroad Creek. Dissolved metal concentrations decreased as streamflow declined. By
September, State water quality criteria were exceeded for copper only in a south bank
sample and for zinc only at stations adjacent to and immediately downstream of the site.
Groundwater concentrations of arsenic, beryllium, cadmium, copper, iron and manganese
beneath the tailings piles are above the MTCA groundwater levels in the spring. By fall
only iron and manganese are above MTCA levels.
Reduction in Benthic Macroinvertebrate and Fish Populations
Both benthic macroinvertebrate and fish populations are reduced downstream of tailings
pile 1 when compared to the control or reference sites. Fish populations remained low in
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17693-005-OI9Uuly 28. 1999;12:16 PM;DRAFT FINAL R1 REPORT ES- 13 DAMES & MOORE
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