ABSTRACT
Thermal remediation technologies are gaining acceptance for in situ clean up of subsurface contamination by non-aqueous phase liquid. The in situ vaporisation of the water is direct in electrical heating if current is supplied to the soils after the subsurface temperature has already reached the local boiling point of water. In that regard, it is important to note that for thermal technologies that do not exceed the boiling point of water, the rebound of active microbial populations to levels comparable to pre-heated conditions have been observed. Indeed, some enhancement in biotic and abiotic contaminant degradation processes can be achieved once the contaminant concentrations have been dramatically decreased. The technology is well-suited for shallow, low permeability soils contaminated with low volatility constituents. The technology is not suited for sites where there is significant water influx. Hexagonal patterns are preferred and injection wells should surround the contaminated zone to eliminate spreading.
