PNNL

Abstract

Marine sediment remediation at the United Heckathorn Superfund Site in Richmond, California, was completed in April 1997. The Record of Decision included a requirement for five years of post-remediation monitoring be conducted in the waterways near the site. The present monitoring year, 2001? 2002, is the fifth and possibly final year of post-remediation monitoring. In March 2002, water and mussel tissues were collected from the four stations in and near Lauritzen Channel that have been routinely monitored since 1997-98. A fifth station in Parr Canal was sampled in Year 5 to document post-remediation water and tissue concentrations there. Dieldrin and dichlorodiphenyl trichloroethane (DDT) were analyzed in water samples and in tissue samples from resident (i.e., naturally occurring) mussels. As in Years 3 and 4, mussels were not transplanted to the study area in Year 5. Year 5 concentrations of dieldrin and total DDT in water and total DDT in tissue were compared with those from Years 1 through 4 of post-remediation monitoring, and with preremediation data from the California State Mussel Watch Program and the Ecological Risk Assessment for the United Heckathorn Superfund Site. Year 5 water samples and mussel tissues were also analyzed for polychlorinated biphenyls (PCB), which were detected in sediment samples during Year 2 monitoring and were added to the water and mussel tissue analyses in 1999. Contaminants of concern in Year 5 water samples were analyzed in both bulk (total) phase and dissolved phase, as were total suspended solids, to evaluate the contribution of particulates to the total contaminant concentration.