Soil Cleanup by In-Situ Aeration. XXIII. Effect of Air Channeling

A distributed diffusion model for soil vapor extraction (SVE) is developed in which air advection occurs through conducting channels or tubes of high air permeability; volatile organic compound (VOC) is removed by diffusion from the surrounding porous medium to these channels, where it is removed by advection. The results obtained with this model are similar to those obtained with other distributed diffusion SVE models in that initial rapid VOC removal is followed by a rather rapid decrease in effluent soil gas VOC concentration and extended tailing of the cleanup. It is noted that soil gas VOC concentration rebound after SVE well shutdown provides useful information about the extent of cleanup only if the soil gas is recovered from the domain which was actually contaminated.