Comparison of Volatile Organic Compound Transport in Composite Liners with HDPE and Ethylene-Vinyl Alcohol Co-Extruded Geomembranes

Abstract

This study evaluated migration of five common volatile organic compounds (VOCs) through simulated composite landfill liners that employ a co-extruded geomembrane (GM) with an interior layer of ethylene-vinyl alcohol (EVOH). A series of column tests was conducted with composite liner configurations employing 1.5-mm- and 1.0-mm-co-extruded EVOH GMs with outer layers of high-density polyethylene (HDPE) or linear low-density polyethylene (LLDPE) and 1.5-mm HDPE GMs. A simulated compacted clay liner (CCL) or a geosynthetic clay liner (GCL) was placed under the GM in each test. VOC breakthrough in composite liners employing HDPE GMs (approximately 30 days) occurred approximately four times faster than for co-extruded EVOH GMs with a HDPE outer layer (approximately 130 days) and with significantly higher VOC concentrations. Co-extruded EVOH GMs with LLDPE and HDPE as an outer layer have diffusion coefficients (0.11–0.58×10−13 m2/s) more than 20 times lower than those for conventional HDPE GM (2.86–11.05×10−13 m2/s). Numerical modeling of toluene migration through a composite liner with a 0.6-m-thick CCL and a co-extruded EVOH GM indicates that toluene concentrations are approximately 42% lower at one hundred years compared with a similar composite liner with a HDPE GM.