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Bennett's Dump Site Ecological Risk Assessment
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Site Background
The Bennett's Dump site consists of two adjacent land parcels totaling about 4 acres in size. The site is located approximately 2.5 miles northwest of Bloomington in Monroe County, Indiana (see Figure 1). The site was formerly a limestone quarry pit, which was filled with waste materials including demolition debris, household wastes, and electrical parts. During the 1960s and 1970s, a large number of electrical capacitors containing PCBs were dumped at the site. Labeling on the capacitors linked the PCB contamination to the Westinghouse Electric Corporation (Westinghouse; later known as CBS Corporation and now known as Viacom), which manufactured capacitors in Bloomington between 1958 and the mid- 1970s.
Discussion/Conclusions
Remedial actions have been undertaken at the Bennett's Dump site to reduce the release of PCBs to the environment. However, PCB-impacted groundwater discharging from the Bennett's Dump site has been released to Stout's Creek. The FERA evaluated risk to piscivorous mammals (mink) and birds (kingfisher). Mink have been shown to be sensitive to the effects of PCBs. Both species are potentially highly exposed through the piscivorous diet. As PCBs elicit reproductive effects in both species, and as reproductive success is a critical endpoint for population stability, risks were evaluated based on the likelihood of PCB-exposure to cause adverse reproductive effects in the mink or kingfisher. Fish data from three sampling stations on Stout's Creek were used to estimate risks to the mink and kingfisher.
Despite the reductions in potential PCB release from the Bennett's Dump site due to the remedial action, fish in the upper portion of Stout's Creek (i.e., near Station 1 at Hunter Valley Road, which is approximately 1 mile from the site) are accumulating PCBs at concentrations greater than those shown to cause reproductive effects in the mink or kingfisher.
PCB concentrations in fish at Station 1 are approximately an order of magnitude higher than at stations located farther downstream. The Station 1 location may be impacted by the release of PCB-impacted groundwater from the site, which flows into the on-site springs and then discharges to Stout's Creek upstream of Station 1. Although risks were lower at Station 2 (3 miles downstream) that at Station 1, the low-effect HQs for both the mink and kingfisher were greater than the threshold of 1, indicating the exposure concentration may be greater than the concentration shown to cause an adverse effect (i.e., a potential risk). At Station 3 (5 miles downstream), exposure concentrations are decreased from those estimated at Stations 1 and 2. For the mink, the no-effectbased HQs were equivalent to 1; the no-effect- and LOAEL-based HQs were equal to or less than 1 respectively; although the low-effect-based HQ was equivalent to 1, indicating concentrations equal to those shown to cause an adverse effect.