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h� KLEINFELDER <br /> I <br /> A-4 2 MONITORING WELL DEVELOPMENT AND SURVEY <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 or sheen is observed on the water, the well is developed by <br /> t 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 /> The locations of soil borings and monitoring wells, and the elevation of the top of the PVC <br /> casings is usually surveyed and tied into permanent markers, if readily available Survey <br /> accuracy is 0 1 foot for the "x" and "y" coordinates and 01 foot for the "z" coordinate The <br /> depth to static groundwater is measured from a set location at the top of the PVC casing The <br /> depth of 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 /> A-4 3 EQUIPMENT DECONTAMINATION <br /> To reduce the potential for cross-contamination between wells, developing equipment is washed <br /> in a trisodium phosphate solution and rinsed in distilled water or steam cleaned prior to use in the <br /> next monitoring well <br /> A-5 GROUNDWATER MONITORING <br /> 23-482276-B00/CR96S276 A -6 October 17, 1996 <br /> Copyright 1996 Klemtelder Inc <br />