Stimulation of biooxidation processes in subterranean formations

A process in which oxygen and nutrients are effectively supplied to biota for stimulating the biooxidation of a contaminant within a subterranean formation containing groundwater comprising introducing an aqueous solution of hydrogen peroxide into at least one site of the subterranean formation, the 24-hour average concentration of the hydrogen peroxide initially introduced being between 0.0001% and 0.1% and increasing the 24-hour average concentration of hydrogen peroxide with time at a rate sufficient to provide a corresponding increase in oxygen available to the biota within the subterranean formation to bioxidize said contaminant but without providing a toxic environment to the biota, and increasing intermittently the hydrogen peroxide concentration introduced into the formation for a short time sufficiently to be toxic to biota at or closely adjacent to the site of introduction thereof thereby removing the biota and thus increasing the permeability of the formation at or adjacent to the site of hydrogen peroxide introduction and degrading said biota into cell material providing nutrients to biota remove from said site.