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' k' ■ KL EINFE LD ER <br /> ' usually not set above the depth of first encountered groundwater. Wells are usually not <br /> set in areas of suspected significant soil contamination. <br /> ' • The PVC pipe and end caps are steam cleaned prior to installation. <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 cement/bentonite grout. <br /> ' • The wells are secured in an aboveground or underground locking stovepipe. The well heads <br /> may be enclosed in a water tight cement utility box set flush to the ground surface when <br /> ' 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 increasb 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 /> ' 204341-1LE01/201IL635 Page A-5 <br /> Copyright 2001,Kleinfelder,Inc. September 24,2001 <br />