Long-Term Effect of an Aqueous Landfill Leachate on the Permeability of a Compacted Clay Liner

ABSTRACT Recent regulations have banned the disposal of solvents and organic liquids in hazardous waste landfills. Studies conducted over the last decade have shown that the permeability of compacted clay liners is increased by short-term exposure to concentrated organic liquids but not to dilute aqueous leachates. However, the long-term effect of dilute aqueous leachates have not been evaluated. A study of long-term exposure to aqueous leachate from a hazardous waste landfill was conducted to investigate whether the permeability of a compacted clay liner would be increased. Relatively undisturbed samples of compacted clay liners were tested in double-ring permeameters to determine their permeability to both water (0.005N CaSO4) and leachate. One sample was treated with more than four pore volumes of aqueous leachate. No substantial increase in permeability was found to have occurred after two years of leachate application.