Abstract: A waste containment system utilizing a manufactured soil useful for the remediation of waste disposal sites for municipal and industrial waste products. To form the manufactured soil, conditioned clay materials, in particular bentonite clay, are mixed with sand and water to form a colloidal suspension. The mixture can be either placed into trenches, as a slurry, to form vertical barriers or allowed to de-water and then spread and compacted to create surface caps and/or sub-surface liners. Normally, the a containment system includes an imbedded sand drainage layer so as to make the composite system impervious to air and water penetration. The percentage of clay in the manufactured soil is varied depending on installation site characteristics and desired performance standards. Manufactured soil with as little as approximately 1% to 3% clay (dry wt.) can be made to achieve and maintain hydraulic conductivities as low as 1.7.times.10.sup.-9 cm/sec.

Abstract: A method and composition are shown for capping exposed land areas, such as landfills, toxic waste sites, and mineral waste sites areas. A formulation is prepared by making a hydrated solution of a particular sodium Bentonite clay and mixing the solution with a specific proportion of sand material. The mixture is distributed over a prepared subgrade by means of a slurry pumping technique. A multilayer cap is created by overlaying additional layers having different clay formulations. The clay mixtures are optimized to be effective water and oxygen barriers while eliminating the problem of desiccation cracking. An anisotropic barrier is achieved as a result of interlayer hydraulic conductivity differences. This barrier together with the establishment of a 1-6% slope of the layer interface encourages lateral movement of water while inhibiting its downward penetration. The overall hydraulic conductivity of the composite cap is extremely low.