Dredging Investigation at State Superfund Site

PES personnel managed this investigation to characterize the extent of chlorinated pesticides in soil, groundwater, and adjacent submerged Bay sediments at a former pesticide formulating and packaging site. There were several phases of the investigation, including hydrogeological studies, an analytical testing program, contaminant transport evaluations, study of offshore contaminant migration in marine sediments, evaluation of bioavailability of contaminants to marine organisms, and dredging of a portion of the contaminated sediments. In-place remediation of sediments which were found to not be suitable for dredging and Bay disposal were also evaluated. Alternatives analysis included: (1) in-place encapsulation of the sediments using a geosynthetic membrane covered with a blanket of sand, cobbles, and boulders for protection from tidal action and in-channel ship traffic; and (2) relocation of contaminated sediments within the channel to a secure containment cell bounded by sheet piling and capped in place. The project included close coordination and involvement with various regulatory agencies.