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kg KLEINFELDER <br />The annular space between the screen and the wall of the boring is backfilled with the <br />appropriate clean sand to approximately 2 feet above the top of the perforated sections. <br />Based on soil logs or a sieve test, modifications may be made regarding the size of sand <br />to be used. Installation of the sand may require that the sand be tretnmied, using clean <br />water. <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 neat cement grout / bentonite <br />powder slurry. <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 />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 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 hydrocarbon <br />layer or sheen. If no product layer or 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 />Development continues until the discharge runs relatively clear of fines. Approximately 5 to 10 <br />well volumes are generally removed from each monitoring well. Discharge water is stored in 55- <br />gallon drums and left on site for later discharge or disposal by the client, depending on laboratory <br />results. The drums are labeled with the date, well number, and a contact person and phone <br />number. <br />24134.E01 / STO3R304 Page A-5 <br />Copyright 2003, Kleinfelder, Inc. February 26, 2003