clays to temperatures at or above 100°C, the release and transport of TCE and PCE will be enhanced as a result of several factors, includ-
ing: (1) an increase in the contami-
nant vapor pressure and diffusivity; (2) an increase in the effective per-
meability with the release of water vapor and contaminant; and (3) enhanced removal from in situ steam stripping by the water vapor generated from heating to tem-
peratures in excess of 100°C. Vapor released in the heated zone will be removed through a vacuum extraction well.

The radio frequency method tested at the ID entailed the placement of

a RF transmitter in a horizontal well. The radio frequency is selec-
ted to excite molecules present and thereby produce heat. This heating volatilizes the VOCs, allowing their recovery via the screened portion ofthe same well.

Another system, recently demon-
strated, involves in situ heating by the use of six-phase electrical cur-
rent being applied to the soil using six vertically emplaced electrodes surrounding a single recovery well. The electrical current causes resistive heating of the soil column and the volatilization of VOCs, which can then be recovered via the central well.