Challenge. Assess potential health risks from polychlorinated biphenyls (PCBs) in soils in the vicinity of Waste Management Area C.

Solution. INTERA used PCB congener analytical results and the U.S. Environmental Protection Agency’s Toxicity Equivalency Factors methodology to calculate a total 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) toxicity equivalent to evaluate the potential health risks associated PCBs in soils. Results of total 2,3,7,8-TCDD toxicity equivalent for each of the shallowest samples collected were found to be many times lower than the published Revised Code of Washington 70.105D, “Hazardous Waste Cleanup — Model Toxics Control Act” value of 0.5 mg/kg. Based on our review of these PCB congener analytical results, sampling and analysis plans for a Phase 2 RCRA Facility Investigation were reevaluated and a recommendation was made to eliminate analysis of PCB congeners in further sampling activities.