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�`■ 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 tremmied, 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 /> 204587-02.WP2/2002R489 Page A-5 <br /> Copyright 2002,Kleinfelder,Inc. June 6,2002 <br />