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Evaluation of Sediment Agitation and Mixing into the Surrounding WaterColumn from Capping Activities at the Wyckoff/Eagle Harbor Superfund Site
Citation:
BATTELLE. Evaluation of Sediment Agitation and Mixing into the Surrounding WaterColumn from Capping Activities at the Wyckoff/Eagle Harbor Superfund Site. U.S. Environmental Protection Agency, Washington, DC, EPA/540/R-05/013, 2005.
Impact/Purpose:
to publish information
Description:
Capping is a common remediation technology for the containment of contaminated sediments. While capping is a common remediation technology for contaminated sediments, little information exists on the potential release of contaminated sediments during and after the capping operation.
The U.S. Corps of Engineers (COE) performed capping operations on creosote contaminated sediments at Eagle Harbor, Bainbridge Island, WA. Clean sand was flushed off a barge with ocean water pumped through a high pressure nozzle. During the capping activities, U.S. EPA/ORD sampled the surrounding water column for TPH, PAH, and RCRA metals. Sampling was conducted with a continuous flow towfish which also took continuous measurements of several water parameters, including depth, temperature, salinity, DO, and turbidity.
Analytical results of water samples collected before, during and after capping activities were compared to quantify changes in contaminant concentrations in the water column caused by the capping activities. The highest total PAH concentration in the water column was observed on Day 1, where average total PAHs were 14 times pre-run background concentrations. Day 2 average total PAH concentrations were above the pre-run background levels, but were much lower than Day 1 levels. By Day 3, average total PAH concentrations were almost background concentrations. The first sampling day also showed the strongest correlation (r-squared values greater than or equal to 0.72) between PAHs and turbidity, when PAH concentrations were plotted against TSS concentrations for the capping survey sampling events. Resuspended contaminated sediment traveled downstream with the current and dissipated within hours after capping activities ceased.