Dames & Moore, 1999 - USDA Forest Service

stressors present to the values resources of the site. To accomplish these goals, PCOCs were evaluated.
habitats were investigated, ROCs were selected, assessment and measurement endpoints were selected. and
the CSM was refmed. A review of historical data, identification of potentially complete exposure pathways.
and identification of preliminary compounds of potential conern (PCOCs) is presented in Section 5.0.
7.2.2.1 Potential Compounds of Concern
Since'the mine closure, a large number of studies and activities have been completed at the Site. Summaries
of documented studies and activities completed at the Site that were relevant to this ERA and considered to
be representative of current site conditions are provided below. The data presented include only those
compounds that were detected consistently over time and that represent compounds typically associated
with copper and zinc mining in sulfide deposits prevalent at the Holden Mine Site.
The summary of historical and data collected during the FU as presented in Section 5.0 and other studies
associated with the Holden Mine Site (Section 2.0) reveals a wide array of analyses have been conducted
over time to evaluate individual study-specific objectives. The following is a summary. by media. of the
highest, lowest, mean, and median concentrations of all measured PCOCs (Table 7.2-2-la through 7.2-2-lh).
Table 7.2.2- 1 A - Surface Water
Tables 7.22-1B1,72.2-1B2,7.2.2-1B3 - Surface Water
Table 7.2.2- 1 C - Sediments
Table 7.2.2-1D - Flocculent
Table 7.2.2-1E - Soils
Table 7.2.2-1F - Tailings
Table 7.2.2- 1 G - Portal Drainage
Table 7.2.2- 1 H - Seeps
The data presented in these tables serve as the basis for the ERA risk characterization.
7.2.2.2 Habitats and Potential Receptors of Concern
There are two basic habitats present at Holden Mine. the aquatic and the terrestrial. In this ERA, the aquatic
habitat is limited to the surface waters and sediments that lie beneath surface waters. The terrestrial habitat
includes sediments that are exposed to air, riverine and riparian habitats, and terrestrial habitats such as
tailings piles and soils. Within each of these habitats, different plant and animal species exist. The
following is an exposition of the major observed habitats and receptors associated with each habitat, as well
as a listing of rare or endangered species that may exist at the site.
Aquatic Areas
A number of studies have characterized the aquatic insect and fish communities in Railroad Creek (Dames
& Moore 1996). 'Ihese studies found a variety of benthic macroinvertebrate species in Railroad Creek,
including Ephemeroptera (mayflies), Plecoptera (stoneflies), Trichoptera (caddis flies), and Diptera (flies).
Investigators observed rainbow trout, cutthroat trout, kokanee, and sculpin, with cutthroat trout being the
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