Geocomposite leachate collection systems are increasingly being considered as a replacement for conventional graded sand filters in coal combustion products (CCP) landfills. The geocomposites liners are attractive because they are not as thick as the graded sand filters still largely in use. To be a satisfactory substitute for filters constructed of natural materials, the geocomposite must not restrict the flow of leachate to the collection system while, at the same time, prevent the migration of the material to be retained through the filter and into the leachate collection system. An experimental program designed to test the suitability of a specific geocomposite system in a CCP landfill was performed. In a modified triaxial chamber, the hydraulic conductivity of the geocomposite was measured alone and with four different materials. The effluent was collected at several times during the test and the amount of particulate material in the water as a function of the volume of liquid passing through the CCP was determined. Three of these materials were CCPs commonly placed in utility landfills: fly ash, stabilized FGD (calcium sulfite), and FGD gypsum. The fourth material was uniformly graded sand used as a control.
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