Retardation of volatile organic compound movement by a soil-bentonite slurry cutoff wall amended with ground tires

Laboratory-scale column tests were conducted to investigate the retardation of volatile organic compound (VOC) movement through a soil-bentonite (SB) slurry cutoff wall material amended with ground tires, which was found to sorb a significant amount of VOCs. The hydraulic conductivity of the SB slurry cutoff wall backfill material was not affected by the addition of ground tires. The hydraulic conductivity of the ground-tire-amended SB backfill specimen increased 1.1 to 1.2 times after the spiking with VOCs; however, that of the conventional SB backfill specimen increased 1.7 to 1.8 times. The effective porosity of the backfill specimens tested was in the range of 70 to 100%. The partition coefficient of trichloroethylene (TCE) increased from 0.96 to 13.41 L/kg when 15% by weight of ground tires was added. As a result, the time for TCE to break through to 10% of the influent concentration became approximately 10 times longer by the addition of 15% ground tires by weight. Ground tire addition to the SB slurry cutoff wall appears to provide a significant amount of VOC retardation capacity without deteriorating the performance of the slurry cutoff wall.