| Summary: | The Anacostia Active Capping Project (AACP) is a United States Environmental Protection Agency (EPA) funded initiative to develop and implement, on a field scale, active capping barrier technologies. Overseen by the Hazardous Substance Research Center, South and Southwest (HSRC), the AACP plans to demonstrate the ability of active capping barrier technologies to prevent the migration of contaminants from the sediment bed to the overlying water column of the Anacostia River. The demonstration project will involve the placement and monitoring of four individual types of capping materials (apatite, Aquablok, coke breeze, and sand) and the monitoring of one control (i.e. uncapped) area.
An integral part of this capping/monitoring effort will be the use of the Model for the Assessment and Remediation of Sediments (MARS) to project long term cap stability and effectiveness. Developed by the Electric Power Research Institute (EPRI), MARS allows for the modeling of river hydrodynamics, sediment transport, chemical fate/transport, and contaminated sediment remediation with one stand-alone model. It is the object of this research to not only model river characteristics and cap effectiveness but to also identify those areas of the MARS model which could benefit from revisions to allow for future active capping barrier simulations.
Model projections illustrate the demonstration area as being a zone of sediment deposition during normal flow events. Furthermore, MARS predicts Aquablok and coke breeze as being the most effective capping barriers when considering PAH migration from the sediment column to the overlying water body. Apatite displayed little PAH contaminant retardation as this barrier is being implemented in the AACP in an attempt to precipitate heavy metals from the sediment and pore water.
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