SOIL CLEANUP BY IN-SITU AERATION .23. EFFECT OF AIR CHANNELING

A distributed diffusion model for soil vapor extraction (SVE) is devel oped in which air advection occurs through conducting channels or tube s of high air permeability; volatile organic compound (VOC) is removed by diffusion from the surrounding porous medium to these channels, wh ere it is removed by advection. The results obtained with this model a re similar to those obtained with other distributed diffusion SVE mode ls in that initial rapid VOC removal is followed by a rather rapid dec rease in effluent soil gas VOC concentration and extended tailing of t he cleanup. It is noted that soil gas VOC concentration rebound after SVE well shutdown provides useful information about the extent of clea nup only if the soil gas is recovered from the domain which was actual ly contaminated.