Product skimmer and/or groundwater pumps are used instead of drop tubes to recover larger LNAPL volumes, or to draw down the water table in more transmissive aquifer units to expose the capillary/smear zone to airflow.įor the drop tube and total fluids pumping approaches, the combined liquid and vapor streams are transported together in a single conveyance line. Drop tube applications involve using high velocity airflow to entrain LNAPL/water droplets at the liquid interface for removal. "Slurping" involves use of a drop tube (stinger) that is placed near the oil-water interface (or bottom of the LNAPL saturated thickness) in each extraction well to focus recovery at the capillary/smear zone fringe and shallow saturated zone where a significant portion of LNAPL and residual hydrocarbon mass tends to accumulate (NFESC, 1996). For vacuum induced LNAPL or groundwater recovery and "slurping" applications, one or more aboveground liquid ring pumps or high-vacuum blowers are used to generate the required vacuum.
#ASTM TREATMENT WELL DRAWDOWN FREE#
MPE is a technology application that teams vacuum-assisted free product and/or groundwater recovery with bioventing and SVE to simultaneously recover free product (if present) and remediate the vadose and capillary/smear zones and shallow saturated zone.Ģ Groundwater, LNAPL, and soil gas typically are recovered simultaneously from wells placed throughout the aerial extent of the treatment area. Vacuum-enhanced free product recovery Description Volatile organic compounds (VOCs) also will partition into the air and be removed through the extraction wells ( soil vapor extraction ). This process aerates the soil and can stimulate aerobic biodegradation of petroleum hydrocarbon constituents ( bioventing). The vacuum also draws recharge air from above the ground surface into the vadose zone. LNAPL or groundwater recovery can be enhanced by creating a vacuum to induce fluid flow toward recovery wells. Treatment by MPE targets remediation of the vadose (or unsaturated) zone, as well as the difficult to treat capillary/smear zone and shallow saturated zone where a large percentage of residual contaminant mass and LNAPL often accumulates. Multi-phase extraction (MPE) is a technology designed to simultaneously remove any combination of light non-aqueous phase liquid (LNAPL), groundwater, and vapor.
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