Dames & Moore, 1999 - USDA Forest Service

Table 7.2.4-1 1A shows that red-tailed hawks could be at risk from the consumption of insectivorous small
mammals exposed to cadmium in the subsurface tailings and the lagoon.
Since red-tailed hawk are not re&cted to the tailings piles, but are free roaming animals, fiuther analysis
under more realistic exposure conditions was conducted. When hawks were exposed to insectivorous small
mammals living on median subsurface soils, no risk was found (Table 7.2.4-1 18).
However, because of the limited data for the lagoon and maintenance yard soils, it was not possible to
further estimate risk in these areas. It should be noted however, that since the soils are probably toxic to
plants and earthworms, it is likely that there is not a complete exposure pathways from small mammals to
mink in these areas. Furthermore, since carnivorous animals are usually only about 10 percent as abundant
and herbivores, it is also unlikely that mink could feed 100 percent on insectivores. When the hawk diet is
10 percent insectivores and 90 percent herbivores (or omnivores), there is no risk to hawks even in the
lagoon and maintenance yard.
Duskv Shrew
Hazard quotients for Dusky shrews feeding on earthworms (Table 7.2.4-12) were calculated by dividing the
doses estimated in Table 7.2.3-15 by the TRVs in Table 7.2.3-4B. The default assumptions were:
shrews feed only on earthworms from locations where soil samples were collected
shrews feed only on earthworms found in the highest metal concentrations areas
shrews drink only the UCL concentrations from Railroad Creek
the modeled small mammal metal concentrations were accurate
Table 7.2.4-12A shows that Least shrews could be at risk from the consumption of earthworms exposed to
cadmium in the subsurface tailings, tailings pile 1, tailings pile 2, the lagoon, and the maintenance yard, and
to zinc in the lagoon.
Although Least shrews have small forage ranges, they are not restricted to the tailings piles, but are free
roaming animals. When shrews are exposed to the median concentrations in subsurface soils, and tailings
piles 1 and 2, there is no risk (Table 7.2.4-128).
However, because of the limited data for the lagoon and maintenance yard soils, it was not possible to
further estimate risk in these areas. It should be noted however, that since the soils are probably toxic to
plants and earthworms, it is likely that there is not a complete exposure pathways to shrews in these areas.
American Robin
Hazard quotients for robins feeding on earthworms (Table 7.2.4-13) were calculated by dividing the doses
estimated in Table 7.2.3-17 by the TRVs in Table 7.2.3-4A.
.The default assumptions were:
• Robins feed only on earthworms from locations where soil samples were collected
Robins feed only on earthworms found in the highest metal concentrations areas
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17693405419Uuly 27.1999;5:16 PM;DRAFT FINAL RI REPORT