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i <br /> 6� <br /> o The well casing will be 2-inch inside diameter,flush threaded joint,schedule <br /> 40 PVC pipe. <br /> �.� 0 The wells will be constructed in 8-inch diameter boreholes. <br /> i - <br /> o Well screen sections are perforated with 0.010- or.02-inch factory-cut slots. <br /> "# This parameter is assessed (and modified if required) after the boring logs <br /> and,if warranted,a sieve test has been performed and the results received. <br /> r o The wells are generally screened from 5 feet above to 20 feet below first <br /> ,.� ground water. The screen length is reduced if an aquitard with a minimum <br /> thickness of 5 feet is encountered. If an aquitard is encountered the well is <br /> usually terminated 1 to 2 feet into the aquitard. Effort is made not to screen <br /> i across two aquifers. If confined aquifer conditions or high vadose zone <br /> 4 <br /> contar3ination is encountered, the Y.-11 screen is usually not set above the <br /> depth of first encountered ground water. Wells are usually not set in areas of <br /> suspected significant soil contamination. <br /> ,,... % o Tar PVC pipe and end caps are steam cleaned prior to installation. <br /> r ' o The annular space between the screen and the wall of the boring is back sled <br /> with the appropriate clean Lone Star Industries 0/30 or 2/12 Monterey sand <br /> a to approximately 2 feet above the top of the perforated sections. Based on <br /> soil logs or a sieve test,modifications may be made regarding the size of sand <br /> # a to be used. Installation of the 0/30 sand may require that the sand be <br /> k tremmied,using clean water. In this event, a sample of tate tremie water is <br /> collected,unless the source is known to be clean. <br /> l <br /> 0 A 3- to 5-foot bentonite plug is placed above the sand pack to provide a seal <br /> } against surface water infiltration. <br /> U The remaining annular space is filled to the surface with tremmied <br /> cement/bentonite grout to the surface. <br /> 1,Y <br /> 0. The wells are secured in a locldng stovepipe. The well Beads may be <br /> t' enclosed in a cement utility box set flush to the ground sur ace located in a <br /> s . <br /> toffic area. <br /> r� <br /> F6-FIELDPRO <br /> 4'� <br />