Apparatus and method for in-situ treatment of a medium

摘要

An apparatus for treating a medium in situ includes counter-rotating shafts and intermeshed blades arranged on the shafts in a helical array to define mixing zones along the length of the shafts. Reagent supply conduits are disposed in a housing surrounding the upper ends of the shafts for introducing reagents into the mixing zones. The housing is attached to a mobile excavator which moves the shafts horizontally and vertically. The shafts are lowered into the medium by the excavator and are counter-rotated to cause the blades to pump the medium and the reagents along the shafts. Once at the desired operating depth, the shafts are moved below the surface of the medium in the horizontal direction generally perpendicular to the plane of the axes of the shafts to define a volume in the medium. The medium and the reagent are mixed vertically and laterally in the mixing zones and are further mixed horizontally as the mixing zones traverse the medium in the horizontal direction, thereby mixing the reagent and the medium in the volume in both the vertical and the horizontal direction to stabilize and homogenize the medium. The shafts are then withdrawn from the medium and the process is repeated for a second volume disposed adjacent the first volume. The apparatus and the method associated with operating the apparatus result in very uniform stabilization and homogenization of a medium at a rapid rate and a low cost.