Dames & Moore, 1999 - USDA Forest Service

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Ingestion of Fish. Some ingestion of Site-related constituents could occur if recreational
users (i.e., fishermen) eat the fish caught in Railroad Creek or Copper Creek. This.route
is evaluated; however, exposure to Site constituents in fish is expected to be minimal
based on the small number of fish caught in the mine influenced areas that are later
consumed. Fish may also be ingested fiom Railroad Creek at Lucerne or from Lake
Chelan.
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Ingestion of Groundwater. Ingestion of ground water at the Site is not considered a
viable exposure route. However, because USFS personnel utilize a well downgradient of
the Site, this exposure route is evaluated for the Lucerne well in this assessment. Under
certain limited circumstances there could be incidental ingestion of groundwater at the
Site, such as during a construction scenario. However, exposure under these
circumstances would be considered insignificant considering the likelihood of such
scenarios occurring and the length of exposure should such an activity occur.
Dermal Absorption Through Soil, Tailings or Sediment. The dermal exposure route is
complete; however, exposure related to dermal absorption was eliminated since this
pathway was considered insignificant as compared with risk through ingestion. For
dermal exposure to solid media (i.e., sediments, soil, and tailings) to be equal to or
greater than the risk posed by ingestion, the absorption fraction, which is an indication of
the amount of compounds of concern absorbed through the skin, must be greater than 0.1
(USEPA, 1992a). The absorption fraction is estimated on a compound of concern-
specific basis and is dependent upon a compound of concern's permeability coefficient in
addition to its soiuwater partition coefficient. For inorganics, the absorption fraction can
be assumed to range from 0.001 to 0.01. (similar to experimental values for cadmium).
For PCBs, the absorption fraction can be assumed to range from 0.006 to 0.06 (similar to
experimental values for 3,3',4,4'-tetrachlorobiphenyl). As a result, the dermal exposure
route' for solid media was considered insignificant and thuS eliminated from the
preliminary exposure pathways model.
Dermal Absorption Through Surface Water and Groundwater. The dermal exposure
route is complete for surface water (i.e., Railroad and Copper Creeks, the sauna, seeps.
mine portal drainage); however, exposure related to dermal absorption was eliminated.
For dermal exposure in water to be equal to or greater than the risk posed by ingestion of
those media, the permeability coefficient for the chemical from the compound of concern
through skin must be greater than 0.1 cmhr (USEPA, 1992a). For inorganics, the
permeability coefficient used to estimate dermal exposure is normally assumed to be
0.001 cmhr, which is two orders of magnitude less than the 0.1 cmhr level referred to
above. Organics have not been detected in aqueous media. As a result, the dermal
exposure route for surface water was eliminated fiom the preliminary exposure pathways
model.
Potential Human Receptor Populations
The potential human receptors for the Site were identified based on the land use characteristics. The
primary receptors were identified as Holden Village residents, recreational users of the mine area (i.e., an
infrequent visitor to the Site such as a hiker or tourist), and USFS personnel utilizing the Lucerne bell
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