Volatile organic compound diffusion and sorption coefficients for a needle-punched GCL

摘要

Test apparatus designed to examine volatile organic compound (VOC) diffusionnthrough geosynthetic clay liners (GCLs) are described, together with procedures for evaluating thenrelevant diffusion and sorption parameters. Test results show that the rate of contaminant migrationnproceeded through the hydrated GCL in the decreasing order of DCM and DCA>benzene>TCEnand toluene. This was attributed to varying degrees of sorption of DCA, benzene, TCE and toluenento the geotextile component of the GCL as well as to the bentonite present in the GCL. Diffusionncoefficients deduced from VOC diffusion testing conducted on the GCLs at confining pressures lowernthan approximately 10 kPa range from 2610710 m2/s to 3610710 m2/s. This is generally lowernthan those reported in the literature for compacted clay liner materials. Assessments of thenenvironmental protection afforded by a landfill liner require that all underlying soil andngeosynthetics components be considered in landfill contaminant migration assessments. The resultsnin this paper provide some of the first published data for laboratory GCL diffusion and sorptionncoefficients, required to perform contaminant migration assessments for five VOC contaminantsncommonly found in municipal solid waste leachate.