Evaluation of the physical stability, groundwater seepage control, and faunal changes associated with an AquaBlok® sediment cap

Active sediment caps are being considered for addressing contaminated sediment areas in surface-water bodies. A demonstration of an active cap designed to reduce advective transport of contaminants using AquaBlok® (active cap material) was initiated in a small study area of the Anacostia River in Washington, D.C. The cap remained physically stable, demonstrated the ability to divert groundwater flow, and was recolonized with native organisms after 30 months of monitoring following cap placement. However, the long-term performance of active caps associated with harsh environmental conditions, hydrogeological settings, and subsurface gas production needs to be further evaluated.