Abstract: Biological fouling of water wells is inhibited by replacing the air in the well column with an anoxic gas such as nitrogen to deprive aerobic bacteria of oxygen. The anoxic gas is applied from a cylindrical tank at the surface and through a gas pipe extending from the tank down into the well casing. The well casing is sealed near the top to prevent air infiltration and maintain a positive gas pressure. The anoxic gas is applied at a slightly positive pressure to maintain the well column filled with it and to prevent air penetration. The gas can be supplied to the well column only or to both the well column and the aquifer so that a blanket of gas in the area of the well inhibits air penetration of the water from the unsaturated cover layer above the aquifer.

Abstract: A method and apparatus are disclosed for restoring and/or maintaining an underground aquifer water supply system plagued with decreased water flow attributable to accumulation of undesirable flow impeding agents in the aquifer wherein a plurality of injection wells are drilled in the ground in surrounding relationship to the production well and a part of the water from the discharge thereof is treated with an additive capable of altering the nature of the plugging agents and returned to the aquifer via the satellite injection wells on a continuous basis. The proportion of bypass and recycle treatment water sent back to the aquifer may be varied with up to 50% normally being recycled for well restoration purposes while only about 10% need be returned for maintenance of the well flow at a desired level.