The main advantage of in situ thermal treatment is that it allows soil to be treated without being excavated and transported, resulting in significant cost savings. However, in situ treatment generally requires longer time periods, and there is less certainty about the uniformity of treatment because of the variability in soil and aquifer characteristics and because the efficacy of the process is more difficult to verify.

Thermal treatment offers quick cleanup times, but it is generally the most costly treatment group. Cost is driven by energy and equipment costs and is both capital and O&M-intensive.

Thermally enhanced SVE is an extraction technique that uses temperature to increase the volatility of the contaminants in the soils. Thermally enhanced SVE may require off-gas and/or residual liquid treatment. In situ vitrification uses heat to melt soil, destroying some organic compounds and encapsulating inorganics.

An available in situ thermal treatment technology is thermally enhanced SVE. This technology is discussed in Section 4. Completed in situ thermal treatment projects for soil, sediment, bedrock and sludge are shown in Table 3-6 and additional information on completed demonstration projects are shown on the FRTR Web Site.