August Mack News

In the in-situ remedial technology of soil vapor extraction (SVE), the following occurs:

• Vacuum is applied to the unsaturated zone through extraction wells.
• Vacuum causes movement of vapors toward extraction wells.
• Volatile constituents are removed through the extraction wells.
• The extracted vapors are discharged to the atmosphere.

• Proven performance; readily available equipment; easy installation; agency approved.
• Minimal disturbance to site operations.
• Short treatment times (usually six months to two years under optimal conditions).
• Easily combined with other remedial technologies.
• Can be used under buildings and other locations that cannot be excavated.

The disadvantages of in-situ SVE are the following:

• Concentration reductions greater than about 90 percent are difficult to achieve.
• Effectiveness less certain when applied to sites with low-permeability soil or stratified soils.
• May require costly treatment for atmospheric discharge of extracted vapors.
• Air emission permits generally required.
• Only treats unsaturated-zone soils; other methods may also be needed to treat saturated-zone soils and groundwater.