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ti <br /> File No. 20-3941-01.E01 KLEINFELDER <br /> March 6, 1997 <br /> A-3.2 Monitoring Well Development <br /> The wells are developed to reduce the effects of drilling on the formation and to increase the <br /> effective hydraulic radius of the well. <br /> Monitoring wells are generally developed 24 to 48 hours after installation to allow the grout to <br /> set. Each well is first sampled with a clear acrylic bailer to visually inspect for hydrocarbon <br /> layer or sheen. If no product layer of sheen is observed on the water, the well is developed by <br /> surging, pumping, or bailing. Surging along the screened interval of the well is performed to <br /> draw the sediment from the formation into the filter pack and the well and to set the sand pack. <br /> The sediment-laden water is purged from the well at a rate of between 0.75 to 10 gallons per <br /> minute (gpm) depending on recharge rate and casing size. Development continues until the <br /> discharge runs relatively clear of fines. Approximately 5 to 10 well volumes generally are <br /> removed from each monitoring well. Discharge water is stored in 55-gallon drums and left on <br /> site for later discharge or disposal by the client, depending on laboratory results. <br /> A-33 Equipment Decontamination <br /> To reduce the potential for cross-contamination between wells, developing equipment is <br /> washed in a trisodium phosphate or lab grade detergent solution and rinsed in distilled water or <br /> steam cleaned prior to use in the next monitoring well. <br /> A-3.4 Well Survey <br /> The locations of soil borings and monitoring wells and the elevation of the top of the PVC <br /> casings will be surveyed and tied into permanent markers, if readily available. Survey accuracy <br /> is 0.1 foot for the "x" and "y" coordinates and 0.01 foot for the "z" coordinate. The depth to <br /> static groundwater is measured from a set location at the top of the PVC casing. The depth of <br /> water is then subtracted from the elevation of the top of the well casing to provide a <br /> groundwater elevation for each monitoring well location. <br /> 20-3941-01.E011207PE075 PageA-4 0 1997, Kleinfelder. Inc. <br /> I <br />