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10 KLEINFELDER <br /> A 3- to 5-foot bentonite plug is placed above the sand pack to provide a seal against <br /> surface water infiltration and to reduce the potential for cement grout to infiltrate into the <br /> water. <br /> The remaining annular space is filled to the surface with cement/bentonite grout. <br /> The wells are secured in an aboveground or underground locking stovepipe. The well <br /> heads may be enclosed in a water tight cement utility box set flush to the ground surface <br /> when located in a traffic area. <br /> B-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 wells. <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 disposable bailer to visually inspect for a <br /> hydrocarbon layer or sheen. If no product layer or sheen is observed on the water, the well is <br /> developed by surging, pumping or bailing. Surging along the screened interval of the well is <br /> performed to draw the sediment from the formation into the filter pack and the well, and to set <br /> the sand pack. Development continues until the discharge runs relatively clear of fines. <br /> Approximately 5 to 10 well volumes are generally removed from each monitoring well. <br /> Discharge water is stored in 55-gallon drums and left on site for later discharge or disposal by <br /> the client, depending on laboratory results. The drums are labeled with the date, well number, <br /> and a contact person and phone number. <br /> B-3.3 Equipment Decontamination <br /> To reduce the potential for cross-contamination between wells, developing equipment is washed <br /> in a trisodium phosphate or non-phosphate detergent solution and rinsed in distilled water or <br /> steam cleaned prior to use in the next monitoring well. <br /> B-3.4 Well Survey <br /> The locations of soil borings and monitoring wells, and the elevation of the top of the PVC <br /> casings are 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 (usually <br /> 0200IPROP.ENV/ST04PI18/DH:ss Page B-5 <br /> Copyright 2004,Kleinfelder,Inc. March 22,2004 <br />