Assessment methods for the Remedial Investigation (RI) included soil gas surveys to quickly target areas of concern, direct-push soil sampling, monitoring well installation in a complex multi-aquifer Coastal Plain setting, wetland delineation, extensive stream and sediment sampling, and indoor air sampling. Impacts were detected in groundwater, streams, a pond, wetland areas, and sediments. Compounds of concern include chlorinated solvents, metals, PCBs, and PAHs.
Hart & Hickman conducted a Tier III-type Human Health Risk Assessment (HHRA) in accordance with DEQ and EPA guidance, working closely with DEQ’s Superfund Section toxicologist. Our HHRA included receptor surveys, an evaluation of potential risks posed to site workers and off-site residents including children who might come in contact with the nearby impacted streams and wetlands and office workers potentially exposed to vapor intrusion. The results were accepted by DEQ and indicated that there were no unacceptable risks to human health even though compounds were present in surface water above surface water quality standards and in indoor air above screening levels. Hart & Hickman also performed an 8-step Ecological Risk Assessment (ERA) in accordance with DEQ and EPA guidance. Working closely with DEQ’s toxicologist, we completed ecological fish tissue collection, small mammal collection, and stream macroinvertebrate assessments to evaluate potential impacts to wetlands, pond, streams, and associated ecological receptors.
Hart & Hickman also conducted groundwater fate and transport modeling to establish cleanup goals significantly above groundwater standards that would be protective of the creeks, ponds, and wetlands that were located downgradient of the site. By performing the risk evaluations and modeling, a much less extensive and less costly remedial action can be supported for the site.