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_-•, 4 . 3 MONITORING WELL CONSTRUCTION <br /> The soil borings will be converted to a groundwater monitoring <br /> wells following drilling. The wells will be constructed of 4- <br /> inch-diameter Schedule 40 PVC flush-threaded casing. The <br /> screened interval will consist of 0.010- or 0.020-inch slotted <br /> rasing (depending on grain size), placed from 10 feet above the <br /> water table to 15-20 feet below it. A threaded end plug or a <br /> slip cap secured with stainless steel screws will be placed on <br /> the bottom of the well, and a locking well cap will secure the <br /> top of the well. <br /> A gravel pack of No. 3 or 2/16 Monterey or equivalent sand will <br /> be placed in the annular space around the well screen to approxi- <br /> mately 3 feet above the top of the screen. A Bentonite plug 2-3 <br /> feet thick will be placed on top of the sand pack and hydrated <br /> with deionized water. The well will then be sealed to the sur- <br /> face using a 3-5 percent Bentonite cement grout. <br /> T The well will be completed on the surface i.n a slightly raised, <br /> 14-inch-diameter, traffic-rated water-tight steel well box which <br /> - requires a special wrench to open. The well box will be set in <br /> concrete. The proposed well completion is shown in Figure 4. <br /> 4 .4 WELL DEVELOPMENT <br /> The well will be developed a day or two after installation. <br /> Development will consist of surging the screened interval of the <br /> well with a 4-inch flapper valve surge block for approximately 15 <br /> minutes. The well will then be puryed, with a submersible <br /> electric pump, of 2 to 4 casing volumes of wat=er. The surgJng <br /> and pumping procedure will be repeated until the water is free of <br /> sand and is apparently free of suspended particles (turbidity < 50 <br /> NTG? . . . <br /> c51 /97780/6-90,`tx 8 <br />