Abstract: When a large-scale contaminant plume is located under a surface area with conditions that prevent placement of a network of injection and associated extraction wells, embodiments of the invention may be used to pump a specific volume of the contaminant plume to at least one remote in-situ treatment cell, comprising at least one injection well surrounded by a plurality of associated extraction wells, where each extraction well is less than 300 feet from the associated injection well, and has a treatment zone with treatment reagent between injection and associated extraction wells.