BEC’s workplan for a removal action to address a residual DNAPL source to groundwater at depths of approximately 120 feet (55 feet below the water table) has been approved. The remedial approach involves the application of hot water injected at approximately 78°C (to achieve a target subsurface temperature of ~60°C) and surfactant/cosolvent enhancements. The heated water will significantly improve DNAPL solubility, reducing viscosity, and lowering interfacial and surface tension in fine-grained soils, while the surfactants will enhance the wettability, further lower the interfacial tension and further reduce viscosity allowing for increased residual DNAPL removal form the fine-grained silts and clays. The system is designed to operate well below co-boiling temperatures of PCE and TCE, eliminating the need for vapor controls. Recovery will be facilitated by extraction of groundwater, which will be treated, heated, amended and reinjected. The system is currently being installed and is scheduled to go on-line in December.
