[en] Pacific Northwest Laboratory (PNL) has undertaken a project to develop and demonstrate an in situ heating (ISH) technique for rendering organic, contaminated soil sites non-hazardous. By heating contaminated soils to elevated temperatures, organic materials can be volatilized and removed, organic volatility tests have proven that soil heating can effectively detoxify organic-contaminated soils. An organic removal efficiency of greater than 99.5% for the moderate-boiling 2-chlorophenol was achieved by heating soil samples to 330/degree/C in a laboratory furnace. A direct current (DC) arcing method was selected for development and demonstration after evaluating several possible ISH concepts. The DC arcing method passes a series of electrical discharges between electrodes inserted in the contaminated soil. Energy dissipated by the discharges heats the soil and volatilizes any organic wastes present in the soil. Removal of organics from soil can be augmented by drawing the volatilized organics to the surface using an induced draft through hollow electrodes. This concept was successfully demonstrated on an engineering-scale test system using soils spiked with 2-chlorophenol as a simulated hazardous chemical. When ISH was performed using the DC arcing method with hollow electrodes to remove volatilized organic vapors, a 95% removal efficiency of 2-chlorophenol from soil was attained. Higher efficiencies are expected as the process becomes more refined. 3 refs., 3 figs., 4 tabs