AquaBlok (Trade Name) is an innovative, proprietary clay polymer composite developed by AquaBlok, Ltd. of Toledo, OH, and represents an alternative to traditional sediment capping materials such as sand. It is designed to swell and form a continuous and highly impermeable isolation barrier between contaminated sediments and the overlying water column, and claims superior impermeability, stability, and erosion resistance and general cost-competitiveness relative to more traditional capping materials. AquaBlok is generally marketed as a non-specific capping material that could encapsulate any class or type of contaminant as well as theoretically any range of contaminant concentration. Although there is claimed to be no practicable limit to the depth at which the material would function, AquaBlok is typically formulated to function in relatively shallow, freshwater to brackish, generally nearshore environments and is commonly comprised of bentonite clay with polymer additives covering a small aggregate core. In addition, other specific formulations of AquaBlok are available, including varieties that can function in saline environments and advanced formulations that incorporate treatment reagents to actively treat or sequester sediment contaminants or plant seeds to promote the establishment or regrowth of vegetated habitat.