Anacostia Waterfront

Complex contamination, prohibitive physical characteristics, or any combination of the two can render a hazardous waste or chemical spill site "untreatable." Typically, "untreatable" hazardous wastes sites possess one of more of the following:

• Located in areas that are inaccessible to more traditional technologies
• Contained within complex gelogic matrices, such as fractured bedrock that traps contaminants
• Contaminated by chemicals whose physical or chemical characteristics render them impossible to clean up to acceptable levels using conventional technologies
• Contain multiple contaminants from multiple sources over a great distance
• Contain large volumes of materials for which removal can create significant environmental disturbance

Contaminated sediments may be the result of direct dumping, washed in or come from multiple sources over long periods of time. Organic contaminants in sediment typically adsorb to fine particles. Metals also adsorb to sediment and may bind to other chemicals. Contaminated sediment can enter the food chain through bioaccumulation. Contaminated sediments posed a significant economic challenge. The sediments of Anascostia River were severely contaminated with polycyclic aromatic hydrocarbons (PAHs), PCBs and heavy metals. These contaminants have hindered local commercial, industrial and recreational uses of the Anacostia River. A ban on consumption of several species of fish in this river were imposed because of the PCB and chlordane contamination.

The SITE program supported a demonstration of an innovative "active" sediment capping technology. Sediment caps are typically design to be deposited on top of toxic sediments and to form a barrier between sediment and aquatic life in the water above. The patented "active" sediment cap technology goes a step further. It is capable of encouraging both degradation and sequestration of the contaminants; therefore, it is a treatment technology as well as a containment technology. As of 2006, the cap's integrity has been maintained. The cap shows little to no erosion or redistribution of cap material. The cap also appears to support ecological health. Continued success with this technology will help to improve the environmental quality of the Anacostia River and protect human health from the potential risks associated with consuming contaminated fish.