Innovative Waste Containment Barriers for Subsurface Pollution Control

Abstract

Bentonite modified by cationic surfactants has been the focus of attention for engineering applications such as in horizontal cut-offs, grout mixes, cut-off slurries, soil motars, and landfill liners because of its high organic removal capacity. In this study, the feasibility of using modified clays in conjunction with conventional soil-bentonite admixtures as a waste containment barrier with the combined abilities of acting as a sealant and effectively retaining dissolved organic contaminants was investigated by a series of experimental tests. The sorption isotherms of total organic carbon, a gross organic term, by five types of soil admixtures are nonlinear. The soil specimen with more modified clays exhibits higher organic sorption capacity and a larger retardation factor. The specimens with 20% of pure bentonite by dry weight have a higher optimum water content and plasticity. With the addition of bentonite in the soil material consisting of natural soils and modified clays, the hydraulic conductivity to leachate decreases from about