Method for in situ removal of a spilled fluid from soil

Abstract

In a preferred method, a spilled fluid, lighter than and immiscible with water, is removed by, first, penetrating through the fluid zone and at least partially through the groundwater zone to provide a bore in communication therewith. Then, at suitable intervals, an amount of fluid is extracted from the fluid zone through the bore at a rate selected to maintain contact between at least a portion of the fluid being extracted through the bore and at least a portion of the fluid remaining in the fluid zone. In addition, at suitable intervals, an amount of water from the groundwater zone is extracted through the bore to produce a head of fluid above the fluid/water interface adjacent the bore sufficient to cause gravity drainage of the fluid from the fluid zone in a direction generally toward the bore. Meanwhile, a major portion of the fluid/water interface and any unstressed portions of the water table are maintained at levels closely adjacent the levels occupied prior to commencing any extraction of the fluid and the water to prevent further spread of the fluid. A combination well to practice the method comprises two preferably concentric tubes, an inside tube and a shallower, larger diameter outside tube which are disposed in a well bore and hydraulically isolated from one another by sealing means. Respective suction means extract fluid and water from the respective fluid and water zones, while maintaining the fluid/water interface and any unstressed portions of the water table at about the pre-extraction position.