BOX 9–1 Midcourse Evaluation at New Bedford Harbor
From the 1940s until the late 1970s, the New Bedford Harbor area (the Achusnet River estuary) received wastes from industries using PCBs in the manufacture of capacitors and other electrical components. Following several years of assessment (1976–1981), EPA added this site to the National Priorities List. Sediments in the upper part of the harbor (Figure 9–1) contained PCBs at concentrations of as much as 100,000 ppm or greater on a dry-weight basis. Management action concerns were focused on the hot spots; the upper and lower Harbor, and the Buzzards Bay area. In 1983, EPA began to evaluate alternatives for addressing the PCB contamination. Initial remediation included PCB-contaminated sediments with concentrations in excess of 4,000 ppm with a sediment volume of about 10,000 m3. An environmental feasibility study (EFS) and pilot studies for remediation were completed in 1989, and EPA recommended the use of a cutterhead dredge connected to a hydraulic pipeline, which would deliver sediment to a confined disposal facility (CDF), where, dewatering, treatment of the water, and incineration of the PCBs in the sediment would occur (EPA 1997).
However, concerned community groups raised strong objections to the incineration of the PCBs, and the incineration plan was modified. The revised plan called for the temporary storage of the dewatered sediment in a CDF along the edge of the upper harbor near the hot spot (Figure 9–2) until a final decision for treatment of the dredged sediments could be made.
Dredging of the hot spot was completed in 1995. Subsequently, after consideration of several alternatives, including pilot studies of solidification and chemical destruction of the sediments, the sediments were further dewatered and moved to an offsite Toxic Substances Control Act-permitted landfill.
This example shows how mid-course correction might be necessary in certain stages of the framework and illustrates the importance of involving affected parties early in the process to achieve a desirable outcome.