The purpose of this study is to determine if bioreactor leachate alters the hydraulic conductivity of geosynthetic clay liners (GCLs). Previous studies on geosynthetic clay liners (GCLs) indicate that permeating the GCL with salt solutions of varying concentrations has affected the hydraulic conductivity of these GCLs. This project will test the chemical compatibility of eight leachates (Picture 1) and one brand of GCL. The leachates are from five different bioreactor landfills within the United States. Hydraulic conductivity is being measured in flexible wall permeameters. The test set up is shown in Pictures 2 and 3. The tests will run for at least one year. Effluent from the tests will be analyzed for metals and trace elements using Inductively Coupled Plasma – Optical Emission Spectrometry (ICP-OES). Composition of the exchange complex will also be evaluated.