SVE is the preferred presumptive remedy. SVE has been selected most frequently to address VOC contamination at Superfund sites, and performance data indicate that it effectively treats waste in place at a relatively low cost. In cases where SVE will not work or where uncertainty exists regarding the ability to obtain required cleanup levels, thermal desorption may be the most appropriate response technology. In a limited number of situations, incineration may be most appropriate.
Another commonly used technology, bioventing, uses a similar approach to vapor extraction in terms of equipment type and layout but uses air injection rather than extraction and has a different objective: The intent of bioventing is to use air movement to provide oxygen for aerobic degradation using either indigenous or introduced microorganisms. While some organic materials are usually brought to the surface for treatment with the exhaust air, additional degradation is encouraged in situ. This difference in approach renders less volatile materials (particularly fuel products such as diesel fuel) amenable to the process because volatilization into the soil air is not the primary removal process.
The AFCEE Bioventing Initiative currently encompasses more than 145 fuel sites at 56 military installations, including one Marine, three Army, and one Coast Guard facility. Approximately 50% of the current systems are full scale. As of September 1995, approximately 125 are installed and operating. The remainder are to be installed.