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{ Laurie Cotulla I I <br /> July 31, 1990 ' <br /> Page 3 f <br /> I� <br /> 2-inch diameter Schedule 40 PVC blank casing and slotted screen. Filter pack material <br /> and slot size will be engineered based on soil samples collected from the soil/water I <br /> interface at the base of the former tank location. !} <br /> i <br /> Each well will be constructed by installing flush-threaded casing and slotted screen down <br /> through the hollow stem of the auger. Filter pack material will be placed by backfilling <br /> the annulus between the borehole wall and the well screen as the auger is retracted. Filter <br /> pack material will be placed to extend 2 feet over the top of, the well screen. A 2-foot <br /> layer of bentonite pellets will be installed above the filter pack, in the same manner as the <br /> filter pack material was placed. The bentonite seal will then be allowed to hydrate for <br /> approximately 30 minutes. Following hydration of the seal, a cement/bentonite grout will i <br /> be pumped into place and will extend from the top of the seal to the surface. The well <br /> will then be completed below grade with the installation of a traffic rated. Figure 2 <br /> provides an example of the typical well to be installed (during this phase of the <br /> investigation. i1 <br /> Surveying i <br /> I, <br /> Upon completion of all three wells, the areal Iocation andcasing elevation of each well will <br /> be surveyed and added to the existing site pian. Casing lielevations will be used to obtain <br /> accurate groundwater elevations, and thus, flow direction. Atotal station surveying unit <br /> will be used to obtain the location and elevation data. I <br /> ,i <br /> Well Development <br /> t <br /> Well development for the two new wells will be accomplished by swabbing the inside of <br /> each well with a surge block in a plunger-like fashion arid then pumping the wells with a <br /> rr i� <br /> submersible pump until the discharge water clears. This procedure will be repeated twice <br /> for each well. Surging of the wells will also take place during the pumping phase of <br /> development by turning off the submersible pump (with (the foot valve removed) <br /> intermittently during pumping. Each well will be swabbed approximately 30 to 40 times <br /> at a slow speed over the entire length of the well screenr�followed by pumping of the well <br /> until the discharge water clears. This step will then be repeated with the swabbing speed <br /> increased. Following clearing of the pump discharge water in ,the final pumping, the well J <br /> will be pumped at the submersible pump's maximum pump rate of 30 minutes. <br /> � if <br /> All discharge water will be pumped into 55-gallon drums and contained on-site until an <br /> analysis of the groundwater has been completed. If the water;is free of contaminants the <br /> water will be discharged to the storm sewer. If contamination is present, the water will <br /> be disposed of off-site at the Chemical Waste Management facility at Kettleman Hills. <br /> k� <br />