Dames & Moore, 1999 - USDA Forest Service

9.2.11 . 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.
9.3 POTENTIAL ENVIRONMENTAL CONCERNS
The following potential environmental concerns were identified at the Site:
9.3.1 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 snowrnelt 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.
9.3.2 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 comparison
to reference reaches of RC-7, located adjacent to tailings pile 2, and at RC-5, located
approximately one-half mile downstream of the Site. Macroinvertebrate counts were lower
than reference reach counts from the Site to the mouth of Railroad Creek, but increased with
distance from the Site. However, the presence of unique species of filter feeder aquatic insects
in the affected reaches of Railroad Creek suggests that the dissolved metals are not the cause of
the reduced macroinvertebrate populations. The reduction in benthic macroinvertebrates and
fish populations adjacent to the site appears to be principally from physical effects of iron
flocculent in the stream. In addition, bioassays completed by Ecology using Cladocerans
(Ceriodaphnia), a sensitive filter feeder, and water from Railroad Creek above and below the
tailings piles, RC- 10 and RC-3 indicated no adverse effects.
The fish populations at the RC-10 sampling station approximately three miles downstream of
the Site are within the range of values collected at the control or reference sites. Young fish
were observed at this station.
9.3.3 Tailings Pile Slope Stability
Based on the results of slope stability analyses, the tailings pile slopes facing Railroad Creek
are relatively stable under static conditions. However, the tailings could be released to
Railroad Creek in the event of a moderate edquake. Only the slopes steeper than
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17693-005-019Uuly 28.1999;10:07 AM;DRAFT FINAL RI REPORT