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MEASURING CONTAMINANT RESUSPENSION RESULTING FROM SEDIMENT CAPPING
Citation:
BATTELLE. MEASURING CONTAMINANT RESUSPENSION RESULTING FROM SEDIMENT CAPPING. U.S. Environmental Protection Agency, Washington, DC, EPA/600/S-08/013, 2008.
Impact/Purpose:
To evaluate the resuspension of surface materials contaminated with polycyclic aromatic hydrocarbons and polychlorinated biphenyls before, during, and after capping of contaminated sediments, at the Boston Harbor/Mystic River Site and the Wyckoff/Eagle Harbor Superfund Site off Bainbridge Island.
Description:
This Sediment Issue summarizes two studies undertaken at marine sites by the National Risk Management Research Laboratory of U.S. EPA to evaluate the resuspension of surface materials contaminated with polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) before, during, and after capping of contaminated sediments. One study was conducted at the Boston Harbor/Mystic River Site in cooperation with U.S. EPA Region 1 and the U.S. Army Corps of Engineers (USACE). The other study took place at the Wyckoff/Eagle Harbor Superfund Site off Bainbridge island, WA in cooperation with U.S. EPA Region 10 and USACE. These studies examined whether the placement of conventional sand caps results in the disturbance of contaminated surface sediments and thus the release of contaminants into the surrounding water column through resuspension. In general, contaminant resuspension, although substantially higher than observed during pre-capping sampling, was relatively low for all capping events with contaminant concentrations remaining in the low ng/L range for most samples. Resuspension of suspended solids and chemicals-of concern occurred continuously throughout capping operations but dissipated to background levels in a matter of hours following cessation of capping activities. Resuspension concentrations were highest when capping was conducted over uncapped sediments, indicating that the first lift of cap material should be placed using techniques that minimize potential disturbance. This finding further suggests that subsequent lifts can be place more aggressively once the contaminated sediment surface is covered.