No Feet of Clay

by George Alther, President; Bentec, Inc., Ferndale, MI,
Jeffrey Evans, Prof. of Civ. Engrg.; Bucknell Univ., Lewisburg, PA,
Stephen Pancoski, Engr.; Gannett-Fleming Geotechnical, Inc., Harrisburg, PA,

Serial Information: Civil Engineering—ASCE, 1990, Vol. 60, Issue 8, Pg. 60-61

Document Type: Feature article


The methods of dealing with hazardous waste are evolving. At Superfund sites, for instance, excavation and removal was once the popular choice for treating pollutants, but stabilization and solidification has now emerged as a viable option. The key to waste stabilization is to produce a material that minimizes the leaching rate of hazardous pollutants. Conventional agents, such as cement, cement kiln dust or fly ash, are successful in stabilizing metal-bearing wastes, but they are generally less effective when used exclusively with organic wastes. New organically modified clays, however, can help solve the problem. When these clays are mixed with conventional stabilization agents, they adsorb and retain pollutants while solidifying organic wastes into a stable mass. Waste stabilization is not the only environmental application for organically modified clays. They're on the market for water treatment, and they have shown potential for spill control and as tank and landfill liners. Their future use in landfills is especially crucial because of EPA's concern that both geomembrane and natural clay liners may be subject to degradation in the presence of organic contaminants. Furthermore, organic contaminants may migrate through conventional materials in response to chemical diffusion gradients. To evaluate the relative adsorption capacity of a number of commercially available organically modified clays, a sedimentation or free-swell volume test may be conducted.

Subject Headings: Clays | Pollutants | Recycling | Clay liners | Water treatment | Solidification | Soil stabilization

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