Volatile Organic Compound (VOC) Transport through Compacted Clay |
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Authors: | Jae Y Kim Tuncer B Edil Jae K Park |
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Affiliation: | 1Associate Member, ASCE 2Member, ASCE 31Asst. Prof., Div. of Civ., Urban, and Geosys. Engrg., Seoul Nat. Univ., 151-742, Seoul, Korea. 42Prof., Dept. of Civ. and Envir. Engrg., Univ. of Wisconsin-Madison, Madison, WI 53706 (corresponding author). 53Assoc. Prof., Dept. of Civ. and Envir. Engrg., Univ. of Wisconsin-Madison, Madison, WI.
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Abstract: | Movement of volatile organic compounds (VOCs) through compacted clay liners was investigated using laboratory-scale column and tank tests. Hydraulic conductivity of the compacted clay was not significantly impacted by the introduction of VOCs in concentrations up to 20 mg∕L. Soil-water partition coefficients of the seven VOCs tested had a strong logarithmic relationship with the octanol-water partition coefficient. Partition coefficients from batch tests were in good agreement with those measured directly on soil samples at the termination of the column∕tank tests. The VOCs were degraded in the clay, with estimated half-lives ranging from 2 to 116 days. Mechanical dispersion was not significant in the range of the hydraulic conductivities of the test specimens (i.e., <10?7 cm∕s). Effective molecular diffusion coefficients were mostly in 10?6 cm2∕s and generally decreased with increasing aqueous solubility. Mass transport parameters of VOCs in clay liners can be estimated from laboratory batch tests and properly prepared small-scale column tests. However, accounting for degradation of VOCs and minimizing the number of transport parameters that are simultaneously estimated from a single response-time record are important considerations for accurate determination of transport parameters. |
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