Barrier wall materials for containment of dense nonaqueous phase liquid (DNAPL)

Four barrier wall materials (cement-asphalt emulsion, bentonite clay-sand, organophilic clay-cement, and attapulgite clay-cement) were evaluated to determine which would have low hydraulic conductivity to water and the ability to maintain that low hydraulic conductivity (less than 1 x 10 super(-7) cm/s) when permeated by a dense nonaqueous-phase liquid (DNAPL). A full-strength DNAPL, methylene chloride, was used to stimulate the worst-case scenario of permeation of a barrier wall by a DNAPL. Cement-asphalt emulsion (Aspemix) and bentonite clay-sand were found to be incompatible with the DNAPL used because large hydraulic conductivity increases occurred when the material was permeated by the DNAPL. Organophilic clay-cement and attapulgite clay-cement (Impermix) were compatible with the DNAPL, because there was little to no change in hydraulic conductivity after permeation by the DNAPL.