Barrier Wall Materials for Containment of Dense Nonaqueous Phase Liquid (DNAPL)

Abstract

ABSTRACT

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 × 10⁻⁷ cm/s) when permeated by a dense nonaqueous-phase liquid (DNAPL). A full-strength DNAPL methylene chloride, was used to simulate 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. The organophilic clay-cement, however, had hydraulic conductivity values that were higher than 1 × 10⁻⁷ cm/s to both water and DNAPL. Attapulgite clay-cement had low conductivity values to both water and DNAPL.