Laboratory Evaluation of Slurry Wall Materials of Construction To Prevent Contamination of Groundwater From Organic Constituents

Abstract

The installation of earthen liners and slurry wall trenches constructed of soils treated with bentonite and/or bentonite/cement mixtures are frequently used today as a means of retarding or controlling the flow of contaminants from surface impoundments and landfill disposal areas. Although effective in reducing the rate of flow of water and some contaminants, standard bentonite treatment is not always effective in controlling some types of contaminants, such as chlorinated hydrocarbons. Past handling and disposal of liquid chlorinated hydrocarbon waste in earthen impoundments and a landfill at an existing plant resulted in shallow ground water and soil contamination over a broad area. Following field investigations, extensive laboratory tests were conducted to investigate the feasibility of confining the plume of contamination through the installation of a slurry trench barrier. Specially designed methods of testing were used during the investigation. Standard bentonite soil mixtures using up to 6% or more bentonite were shown to be ineffective in restricting the flow of the concentrated wastes found in the subsurface strata. However, a 12%/12% bentonite/ cement dust/soil mixture was shown to restrict completely the flow or movement of the concentrated waste while reducing the flow of ground water and contaminated leachate.