Soil Mixing/Thermally Enhanced Soil Vapor Extraction (SM/TESVE)

The I-SF Dual Auger® soil mixing equipment provides the capability to do active soil vapor extraction (SVE). This approach is particularly useful for low permeability soils, such as clay and soils with layers of variable permeability. These are conditions where conventional SVE and single mixing blade equipment experiences difficulties or cannot be successfully used. This technique is applied with equally good success to soils in both the vadose zone and the saturated zone. The soil is treated in batches with the Dual Auger® breaking up and mixing the soil. This greatly increases the permeability and permits all the soils to be treated evenly. During the mixing, hot air and high-pressure steam are injected into the contaminated soil. The steam heats the VOC contaminated soil, thermally desorbing the VOCs and also volatilizing the non-adsorbed free VOCs. The air carries the volatilized contamination to the surface. The contaminated vapors, following the path of least resistance, are captured in the shroud as they come to the surface. The shroud is under a vacuum that conveys the vapors to a surface treatment system such as activated carbon, scrubber or catalytic/thermal oxidizer. The chemistry of the contaminated vapors (off-gas) is determined during the mixing/ injection/ desorption/ volatilization process. This technique is applicable to a wide variety of soil types containing chlorinated solvents and historically achieves greater than 90% contaminant removal rates.

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