Dames & Moore, 1999 - USDA Forest Service

deer mice fed only on plants growing in the UCL metal concentrations areas
deer mice consumed soil equivalent to 2 percent of their plant ingestion rate
deer mice drink only the UCL concentrations from Railroad Creek
the modeled plant metal concentrations were accurate
Table 7.2.4-9 shows that there is no risk to deer mice b m the consumption of plants growing at even the
worst case locations. Therefore, there is no need to conduct further analyses of risk to this ROC.
- Mink
Hazard quotients for mink feeding on small mammals (Table 7.2.4-IOA) were calculated by diving the
doses estimated in Table 7.2.3-14 by the TRVs in Table 7.2.3-4B. The default assumptions were:
mink feed only on small mammals from locations where soil samples were collected
mink feed only on small mammals found in the highest metal concentrations areas
mink drink only the UCL concentrations from Railroad Creek
the modeled small mammal metal concentrations were accurate
Table 7.2.4-10A shows that mink feeding on small insectivorous mammals could be at risk from cadmium
in the subsurface tailings piles, and the lagoon.
Since mink are not restricted to feeding in only the worst case locations, risk was further characterized at
median metals concentrations in small mammals. When mink were exposed to small mammals living on
median subsurface soil concentrations there was no risk from the subsurface tailings (Table 7.2.4-IOB).
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 as herbivores, it is also unlikely that mink could feed 100 percent on insectivores. When the mink diet
is 10 percent insectivores and 90 percent herbivores (or omnivores), there is no risk to mink even in the
lagoon and maintenance yard.
Red-Tailed Hawk
Hazard quotients for red-tailed hawk feeding on small mammals (Table 7.2.4-1 1) were calculated by
dividing the doses estimated in Table 7.2.3-16 by the TRVs in Table 7.2.3-4A. The default assumptions
were:
hawks feed only on small mammals from locations where soil samples were collected
hawks feed only on small mammals found in the highest metal concentrations areas
hawks drink only the UCL concentrations from Railroad Creek
the modeled small mammal metal concentrations were accurate
G:\~W)~ruUIoldco-2\n17QQdoc 7-68
17693-00J-019Uuly 27.1999.5: 16 PWRAFT FINAL R1 REPORT