Predicting Effluent PCBs from Superfund Site Dredged Material

The Corps of Engineers and EPA conducted a feasibility study of using dredges to remove PCBs from the highly contaminated sediments of the New Bedford, Mass., harbor, a Superfund site. Three types of dredges were tested. Also, a confined disposal facility (CDF) was constructed to test the feasibility of onshore containment of the dredged material. Laboratory settling tests and modified elutriate tests were conducted prior to dredging to predict the release of PCBs in the effluent. Comparisons and predictions with field measurements showed that the prediction method was valid and useful for PCBs. The average concentration of dissolved PCB of 4.8 g L was close to the prediction of 7.5 g L. The average total concentration of 28 g L was less than the predicted value of 65 g L, because the average effluent suspended solids (SS) of 67 mg L was less than the predicted 120 mg L, due to dredge operating problems. Other data showed that dredging is a feasible remediation method.