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AIR SPARGING WELLS <br /> Air sparging wells are drilled with a truck-mounted auger rig equipped with 6-inch (or <br /> smaller) inside-diameter hollow-stem augers. To prevent cross contamination, all drilling <br /> equipment is steam cleaned prior to and between use at each well. <br /> The total depth of each air sparging well is determined on the basis of depth to water. The <br /> air sparging wells are cased with 1-inch-diameter PVC flush-threaded blank casing, and 0.20-inch <br /> machine-slotted, flush-threaded slotted casing (screen). The wells are typically screened at least <br /> 5 feet below the lowest recorded groundwater depth. The screen interval is approximately 2 feet. <br /> The blank casing extends from the top of the slotted casing to the ground surface. <br /> The annular space around the slotted casing is filled with Lonestar Coarse Aquarium sand <br /> or equivalent, from the bottom of the screened interval to approximately 1 feet above the screen. <br /> A 2-foot-thick seal of bentonite'is placed immediately above the sand and hydrated. The <br /> remainder of the annular space is grouted with bentonite-cement slurry or neat cement from the <br /> top of the bentonite seal to the surface. <br /> Air sparging wells are completed at grade, and fitted with a top cap until such time as they <br /> are connected to the air sparging blower system. Further discussion on connecting the air <br /> sparging wells to the sparge blower system is delayed until that phase of work is to be <br /> implemented. <br />