Six-Phase Soil Heating of the Saturated Zone, Dover Air Force Base, Delaware

摘要

As part of Armstrong Laboratory's efforts to identify technologies to treat DenseNon-Aqueous-Phase Liquids (DNAPL), a field test of Six-Phase Soil Heating (SPSH) was performed at the Groundwater Remediation Field Laboratory (GRFL) at Dover Air Force Base. The goal of the test was to determine the effectiveness of SPSH for heating the aquifer to temperatures sufficient to remove target DNAPL contaminants. This field test was conducted in an uncontaminated aquifer using tracer compounds to mimic DNAPLs commonly found at Air Force sites. Six-Phase Soil Heating uses electrical resistance to raise the temperature of the soil and groundwater to boiling. A single, six-electrode array was installed into the aquifer (approximately 34 feet below ground surface) at the GRFL site. Temperatures in the saturated zone rose to boiling over 12 to 17 days. Heating and boiling of the aquifer continued for another 13 days. Tracer sampling results showed no significant migration of the tracers in the groundwater, some migration of tracers in the unsaturated zone, full recovery of the perfluoromethylcyclohexane (PMCH) in the extracted offgas, and 35 percent recovery of the perfluorotrimethlycyclohexane (PTMCU). Most of the tracer removal occurred in 21 days.