USE OF ORGANOPHILIC CLAY IN SAND-BENTONITE AS A BARRIER TO DIESEL FUEL

A laboratory research program was conducted to evaluate the long-term hydraulic performance of sand-bentonite liners augmented with organoph ilic clay and permeated with diesel fuel. This program was also design ed to establish guidelines for the incorporation of organophilic clay in sand-bentonite liners. The study involved three areas of testing. T he first was to characterize the materials. The second was to evaluate various combinations of materials and preparation techniques through hydraulic conductivity tests. The third area involved unconfined infil tration tests. The primary hydraulic conductivity testing was broken i nto three phases. These investigated the hydraulic conductivity of org anophilic sand-bentonite liners using various percentages of organophi lic clay and evaluated the hydraulic performance of these specimens wh en permeated with distilled water and diesel fuel. Hydraulic conductiv ity was measured in specially designed low gradient, low effective str ess stainless-steel triaxial permeameters. The results of this test pr ogram indicated that small percentages (3%) of organophilic clay in a sand-bentonite liner material could effectively be used to avoid desic cation cracking in a liner permeated with petroleum products. High per centages (7.5%) of organophilic clay in a sand-bentonite mixture resul ted in a liner permeable to water, but reduced permeability to diesel fuel.