Dual-Phase Extraction In South Texas Using the RSI S.A.V.E. System

摘要

Dual-Phase Extraction (DPE) is an aggressive in situ technology that is capable of recovering Non-Aqueous Phase Liquid (NAPL) and treating affected soils and groundwater simultaneously. The technology, involves the removal of NAPL, groundwater and soil vapor from a series of extraction well points utilizing a vacuum source. NAPL and groundwater are separated at the surface, upstream of the vacuum source and the soil vapor is allowed to pass through the vacuum source where it is processed by combustion, adsorption or other effective means. Remediation Service International (RSI) has developed an internal combustion engine (ICE) for utilization as a vacuum source for DPE. The engine uses the extracted vapor contaminates as fuel, thereby reducing the need for off-gas treatment. The engine does not require electricity and is designed to function as a mobile self-contained remediation unit. A computer controlled carburetion system assures a near-stoichiometric air/fuel ratio with propane or natural gas used as a supplemental fuel. In stack tests, the computer-controlled system has been measured at 99.5% combustion efficiency. The system has the capability to separate vapor and liquid and treat the vapor and liquid streams. The unit processes the extracted vapors and the vapor contaminate are used as fuel for the engine. The liquid is transferred to storage then drawn into a spray aeration system. The system operates under vacuum, with supplied heat from the engine, to volatize the dissolved-phase hydrocarbon from the recovered fluid. This vapor phase is also routed to the engine for fuel. The treated water stream is routed through polishing carbon before disposal into the city sewer system. Applied Petroleum Technologies Ltd. (APT) has applied this technology to remediate a gasoline release from an underground storage tank system at a convenience store in Corpus Christi, Texas. The present recovery system consists of seven extraction well points. Each well point has an effective radius of influence of 30 feet at 25 inches water column vacuum. An underground network of six-inch PVC piping connects the extraction wells and serves as secondary containment. Flexible PVC reinforced tubing is used to connect each well to a control valve on the unit. The tubing continues to the PSH/water interface and acts as a slurp-tube. Project manager control valves are located at the system influent manifold and control each extraction well point separately.