placement of numerous wells. By selectively heating the soils, the release of the solvents from the soil can be significantly enhanced.

Accomplishments

The RF heating demonstration integrated RF application and va-
cuum extraction from a single, horizontal well. The horizontal well was drilled through a con-
taminated clay layer located be-
tween the M Area and an adjacent seepage basin at the SRS. Off-
gases drawn from the well were destroyed with a skidmounted thermal-catalytic oxidation system.

During the 21-day demonstration period, approximately 11,000 kilo-
watt-hours of RF energy were

successfully coupled to the subsu-
face clay layer and heated a sedi-
ment volume of approximately 1,500 cubic feet to greater than 600°C. Wellhead concentrations of VOCs increased during the heating phase, indicating an increase in liberation of VOCs from the soil; over 170 kg of VOCs were success-
fully extracted over the course of the demonstration. Two significant findings made during the test im-
peded the full assessment of the technology. First, a steam block formed downhole when tempera-
ture exceeded 100°C. This vapor block limited the achievable va-
cuum and, therefore, reduced the extractive rates. Second, the choice of casing material, and in particular, the temperature limits of the fiberglass screen, reduced