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05/14/01 MON 16:48 FAX KLEINFELPER • The annular space,between the screen and the wall of the boring is backfilled with the appropriate clean wild to approximately 2 feet above the top of the per&rated sections. Based on soil logs or a sieve test,modifications may be made regarding the size of sand to be used. Installa ien of the satxl may require that the sand be t numied,using clew water. + A 3- to 5-foot bentonite plug is placed above the sand pack to provide a seal against surface water infiltration and to reduce the potential for cement grout to infiltrate into the water. • The remaining annular space is filled to the surface with cement/bentonite grout. + The,wells are secured in an abovegmund or underground locking stovepipe. 11M well heads may be enclosed in a water tight cement utility box set flush to the Wound surfaoe whcn located in a traffic area. B-3.2 Monitoring Wen Ilevelopment The wells are developed to reduce the effects of drilling on the formation attd to increase the eOeetive hydraulic radius of the wells. AlOuitoriug wells are generally developed 24 to 48 hours after installation to allow the gout to set. Each well is first sampled with,a clear disposable bailer to visually inspect for a hydmcarbon layer or sheen. If no Product layer or sheen is observed on the water, the well is developed by surgin& pumping or bailing. Surging along the scmened intergyral of the well is performed to draw the sediment from the formation into the filter pack and the well, and to set the sand pack. D6veloptMrrt continues until tfic discharge naffs relatively clear'of fines. Approximately 5 to to well volumes are generally removed fi,om each Monitoring well. Discharge water is stored in 55- gallon strums and left on site for later discharge or disposal by the client,depending on laboratory results. The drums are labeled with the date, well number, and a contact person and phone number. B-33 Equipment Decontandnation To reduce the potential for crosa-oontarn ination between wells,developing equipment is uwadW in a trisodium phosphate, or non-phosphate detergent solution and rinsed in distilled water or steam cleaned prior to use in the next monitoring well, 20-YP 1-56=01 l P13 7 fx011 0235 Page,A-5 l:OPftM 1001,K)oin&lder,Inn I&y 14,2001