Soil Clean Up byin-situAeration. I. Mathematical Modeling

Abstract
Mathematical models are developed suitable for use in evaluating the feasibility of in-situ vapor stripping approaches for selected chemicals and site-specific environments. These models simulate the operation of both laboratory soil stripping columns and field-scale vacuum extraction wells (vent pipes). The effect of an anisotropic Darcy's constant is examined and the compressibility of the extracting gas is taken into account. The models incorporate the assumption of local equilibrium for the volatile compounds between the condensed and vapor phases. These models may use Henry's law or more complex isotherms for this equilibrium. A method is developed for calculating Henry's constant from field analytical data, and it is noted that use of Henry's constants calculated from laboratory data on solutions of volatile solutes in pure water can lead to very serious errors. It is shown that evacuation wells should be screened only down near the impermeable layer beneath the zone of stripping (unsaturated zone) for most efficient functioning

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