Housatonic River Channel/Floodplain Interaction and Associated Transport of Solids and PCBs

摘要

Widespread PCB contamination of the Housatonic River downstream ofPittsfield, Massachusetts, is present in both river sediment and floodplain soil. Estimatesindicate that over half of the mass of PCBs in the Housatonic River system downstreamof the confluence of the East and West Branches, is located in the 10-year floodplainwithin the Primary Study Area (PSA), a 10.5 mile reach between the confluence andWoods Pond Dam. The application of the hydrodynamic and sediment/contaminanttransport and fate model, EFDC, to the PSA includes both the river channel and theadjacent 10-year floodplain in the model grid, incorporating simulation of PCB transportassociated with channel-floodplain interactions. The primary processes in this interactionare advection and subsequent deposition of solids and associated PCBs onto thefloodplain during out-of-bank flow conditions, and transport of PCBs and solids from theriverbanks to the channel as a result of bank erosion and mass failure.