Soil vapor extraction is an in situ remedial technology that reduces concentrations of volatile constituents in petroleum products adsorbed to soils in the unsaturated (vadose) zone. A vacuum is applied through wells near the source of contamination in the soil. Volatile constituents of the contaminant mass "evaporate" and the vapors are drawn toward extraction wells. Extracted vapor is then treated (commonly with carbon adsorption) before being released to the atmosphere.