subjected to additional bursts of air and or mechanical agitation followed by additional pumping and air lifting until the discharge water is substantially free of all traces of bacteria and particle matter 0028 fig4 depicts an alternative arrangement that is used primarily for smaller diameter wells and or wells that are provided with louvers 116 in place of screen 16 louver openings 116 a are provided between adjacent louvers 116 which are typically inclined upwardly at an angle from the inside of the casing 14 to the outside of the casing in the arrangement shown in fig4 the assembly of the nozzles 98 is replaced with a shroud 104 which includes on its upper portion a horizontal disc 106 and on its lower portion a conical plate 108 the disc 106 and plate 108 are spaced apart to provide an interior chamber 110 between them the outside edges of disc 106 and plate 108 are adjacent to the casing and louvers 116 and are spaced slightly apart to provide an annular discharge slot 112 through which the gas is applied the chamber 110 is supplied with gas through ports 114 when the valve 92 is open the plate 108 inclines upwardly as it extends toward the casing 14 and is preferably oriented.