At sites where contamination is in the saturated zone, a process called air sparging may be used along with the SVE system. For air sparging to be successful, the soil in the saturated zone must be loose enough to allow the injected air to readily escape up into the unsaturated zone. Air sparging, therefore, will work fastest at sites with coarse-grained soil, like sand and gravel. As with SVE, an added benefit of air sparging is that it provides an oxygen source that helps stimulate the bioremediation of some contaminants. Bioremediation is an innovative treatment technology that uses microorganisms, such as bacteria, that live in the soil or groundwater to break down contaminants into harmless substances.
Air sparging also can be a quick and effective treatment for VOCs in groundwater.
Air injection wells use air compressors to force air into the ground. When incoming air passes through the soil on its way to the extraction wells, contaminants evaporate out of the spaces between the soil particles and are pulled by the air to the wells and removed. Vapor extraction wells can be placed either vertically or horizontally. Typically, they are placed vertically and are designed to penetrate the lower portion of the unsaturated zone. Vapors extracted by the SVE process are typically treated using carbon adsorption, incineration, catalytic oxidation, or condensation.