Chapter 3 Site Characterization and Technology Screening

(1) Airflow is induced in the subsurface by applying a pressure gradient through vertical or horizontal wells or horizontal trenches. In SVE, this is usually accomplished by withdrawal, rather than injection, of air. The SVE gas flow increases rates of contaminant mass transfer to air in the unsaturated zone by evaporation of NAPL, volatilization of contaminants dissolved in pore water, and desorption of contaminants from soil particle surfaces. SVE is dependent on contaminant properties, such as volatility, and soil properties, such as air permeability and stratigraphy.