Technology Needs

Most DOE sites have been contami-
nated with volatile organic com-
pounds, including chlorinated sol-
vents like TCE and PCE, non-chlor-
inated solvents like methylethylke-
tone (MEK), benzene and acetone, and fuels like gasoline. Techni-
ques for retrieving these VOCs from soils are being developed and demonstrated at various Inte-
grated Demonstrations. These techniques include in situ air sparging, radio frequency heating and six-phase soil heating. All of these techniques remove VOCs as vapors from contaminated soils. The baseline technologies are soil vapor extraction within the vadose zone and pump-and-treat for groundwater. These technologies are limited by the mobility of the

contamination in the subsurface. Six-phase soil heating increases mobility and should result in faster and more complete removal of contamination from less perme-
able soils.

Accomplishments

In FY92, a small-scale field test of six-phase soil heating was suc-
cessfully performed at the in situ vitrification site in the 300 Area of Hanford, Washington. The test heated a 20-ft diameter cylinder of uncontaminated Hanford soil to a 10-ft depth. The test ran unattend-
ed, using a computer-based system. After 50 days of heating, soil at a 4-to-10 foot depth reached an equilibrium temperature of 76.5°C. A 1/10 pilot-scale test us-
ing TCE- and PCE-contaminated