Evaluation of Different Slurry Materials for Containment Wall Construction at a Dense Nonaqueous Phase Liquid-Contaminated Site

Abstract

A water-bearing granular soil layer within the subsurface of a former manufactured gas plant ~MGP! site is impacted with tarry dense nonaqueous phase liquid ~DNAPL!. A containment wall constructed with the vibrated beam method is considered feasible. Different slurry materials were tested and then selected to prevent the migration of DNAPL to offsite properties. This paper presents the slurry compatibility study to evaluate different self-hardening slurry materials for their compatibility with the DNAPL. Specifically, the study simulated the emplacement of slurry material in the granular unit that is impacted with DNAPL and determined the effect of DNAPL interaction with the slurry material on permeability and shear strength of hardened slurry. Four different types of slurry materials, namely cement-sodium bentonite-dispersant, cement-sodium bentonite, cement-calcium bentonite, and IMPERMIX ~slag cement and Attapulgite clay mix! were used to prepare cylindrical samples under different simulated emplacement conditions ~mixing or pouring with site DNAPL! and were cured. Both permeability and unconfined compression tests were conducted on the cured slurry samples. Both groundwater and DNAPL were used as permeants in permeability testing. Overall, the results showed that the IMPERMIX slurry possesses low permeability ~less than 10 28 cm/s) and high shear strength for all of the simulated test conditions. Because of good chemical compatibility and ease to use with the vibrated beam construction method, IMPERMIX slurry mix was recommended for the construction of the containment wall at the site. DOI: 10.1061/~ASCE!1090-025X~2004!8:3~173! CE Database subject headings: Containment; Slurry walls; Permeability; Shear strength; Waste sites.