Field test of six-phase soil heating at the Savannah River Site

Six-Phase Soil Heating (SPSH) was demonstrated as a viable technology for heating low permeability soils containing volatile organic contaminants as part of the Volatile Organic Compounds in Non-Arid Soils Integrated Demonstration (VOC Non-Arid ID) at the Savannah River Site. The soil at the integrated demonstration site is contaminated with perchloroethylene (PCE) and trichloroethylene (TCE); the highest soil contamination occurs in clay rich zones that are ineffectively treated by conventional soil vapor extraction due to the very low permeability of the clay. The SPSH demonstration sought to heat the clay zone and enhance the performance of conventional soil vapor extraction. Thermocouples at 30 locations quantified the areal and vertical heating within the treated zone. Results show successful heating of the targeted clay zone that contained the higher levels of soil contamination. The clay-zone temperatures increased to 1,000 C after 8 days of heating and were maintained near 1,000 C for 17 days. Electrical heating removed 17,000 gal of water from the soil as steam, with peak removal rate of 1,500 gpd of condensed steam.