text: The soil vapor extraction remediation technology uses vacuum blowers and extraction wells to induce gas flow through the subsurface, collecting contaminated soil vapor, which is subsequently treated aboveground.  SVE systems can rely on gas inflow through natural routes or specific wells may be installed for gas inflow (forced or natural).  The vacuum extraction of soil gas induces gas flow across a site, increasing the mass transfer driving force from aqueous (soil moisture), non-aqueous (pure phase), and solid (soil) phase into the gas phase.  Air flow across a site is thus a key aspect, but soil moisture and subsurface heterogeneity (i.e., a mixture of low and high permeability materials) can result in less gas flow across some zones.  In some situations, such as enhancement of monitored natural attenuation, a passive SVE system that relies on barometric pumping may be employed.
  SVE has several advantages as a vadose zone remediation technology.  The system can be implemented with standard wells and off-the-shelf equipment (blowers, instrumentation, vapor treatment, etc.).  SVE can also be implemented with a minimum of site disturbance, primarily involving well installation and minimal aboveground equipment.  Depending on the nature of the contamination and the subsurface geology, SVE has the potential to treat large soil volumes at reasonable costs.
  The soil gas (vapor) that is extracted by the SVE system generally requires treatment prior to discharge back into the environment.  The aboveground treatment is primarily for a gas stream, although condensation of liquid must be managed (and in some cases may specifically be desired).  A variety of treatment techniques are available for aboveground treatment and include thermal destruction (e.g., direct flame thermal oxidation, catalytic oxidizers), adsorption (e.g., granular activated carbon, zeolites, polymers), biofiltration, non-thermal plasma destruction, photolytic/photocatalytic destruction, membrane separation, gas absorption, and vapor condensation.  The most commonly applied aboveground treatment technologies are thermal oxidation and granular activated carbon adsorption.  The selection of a particular aboveground treatment technology depends on the contaminant, concentrations in the offgas, throughput, and economic considerations.