ABSTRACT
Cutoff walls and other barrier systems have a long history of use in traditional geotechnical construction for the control of water seepage, flows, and pressures. With the increased awareness of the hazard posed by contaminated soils and groundwater, it was a natural step to employ barrier wall systems to contain and prevent the spread of contaminants. Bentonite slurries, soil-bentonite mixes, and portland cement-bentonite mixes are commonly used in what is termed slurry wall construction to form vertical cutoff walls. An important aspect of the slurry wall construction is the formation of the bentonite filter cake along the sides of the trench. The filter cake forms along the sides of the trench during excavation as long as the level of the slurry is such that flow is directed out of the trench and into the surrounding soil. The use of asphalt slurries for cutoff walls is relatively new.
