Releases to the Environment Soil contamination may occur if contaminated soil containing VOCs and SVOCs leaks or mixes with uncontaminated soil during drilling. Ground water contamination may occur in the event of releases of contaminated water into the water table during the drilling of the extraction well. The potential exists for releases of VOCs around the air vent or injection well during treatment. Vapor and liquid treatment residual must be properly managed to protect against release onto land or into ground or surface water. Parameters Affecting Performance Treatment of soil through in situ vapor extraction increases in difficulty as soil composition varies.
Inconsistent soil offers variable flow rates and desorption performances.
This problem can be mitigated, however, with proper design of the vacuum extraction system. In situ soil vapor extraction works best in loose soil, such as sand and gravel, because the air can more easily penetrate the soil layer to extract vaporous contaminants. The physical and chemical properties of the released product control, to a great extent, the movement and ultimate fate of that product in the subsurface. The released product's volatility controls in large part the quantity present as vapor in the soil pores. Volatility is perhaps the most important product characteristic affecting applicability of soil vapor extraction to that compound.