Recent investigations indicate that organic chemicals are found in significant concentrations in sanitary landfill leachates. Previous research shows that sorption of organic chemicals is controlled by the amount of organic matter in clay and typical liner clays contain only about 1% organic carbon. Therefore, there is a concern about the fate of organic chemicals found in the leachate. Recent studies indicate the importance of test specimen size on hydraulic conductivity determination and the importance of diffusive transport through low-permeability clay liners. In this paper, development of a large-size liner test is presented. The test was designed to evaluate transport/attenuation behavior of volatile organic compounds through a compacted clay under realistic representation of field conditions. The results of a test that lasted 11 months (9 months of chemical transport) are presented along with the methods for testing and analysis. The results point out to the importance of large-scale, long-term tests and the need to develop other means of attenuation of organic chemicals.