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kn KLEINFELDER <br /> o The wells are screened from 5 feet above to 15 feet below Hirst ground water. <br /> Every effort is made not to screen across two aquifers. Wells are not set in <br /> areas of suspected significant soil contamination. <br /> o All PVC pipe and end caps are steam cleaned prior to installation. <br /> o The annular space between the screen and the wall of the boring is backfilled <br /> with clean Lone Star Industries 0/30 Monterey sand to approximately 2 feet <br /> above the top of the perforated sections. Based on soil logs or a sieve test, <br /> modifications may be made regarding the size of sand to be used. <br /> Installation of the 0/30 sand frequently requires that the sand be tremied, <br /> w. using potable water. <br /> o A 3-foot bentonite plug is placed above the sand pack to provide a seal <br /> against surface water infiltration. <br /> L. o The remaining annular space is tremied with grout consisting of Portland <br /> cement, 4 to 6 percent bentonite gel and potable water. <br /> L" o The wells are secured using a locking stovepipe inside a cement utility box <br /> 4 that is set flush to the ground surface. If not located in a traffic area, a utility <br /> LM box will not be used and wells can be extended to 3 feet above ground <br /> surface. <br /> MONITORING WELL DEVELOPMENT AND SAMPLING <br /> Monitoring wells are developed after installation. Well development can begin after a <br /> minimum of 24 hours after well construction is completed. Each well is first sampled with <br /> a clear acrylic bailer to visually inspect for hydrocarbon layer or sheen. If no product layer <br /> or sheen is observed on the water, the well is developed by surging, pumping„ or bailing. <br /> Surging along the screened interval of the well is performed to draw the sediment from the <br /> formation into and out of the well, and to set the sand pack. Development continues until <br /> �. the discharge runs relatively clear of fines. Approximately 5 to 10 well volumes are <br /> generally removed from each monitoring well. Discharge water is stored in 55-gallon <br /> drums and left onsite for later discharge or disposal, depending on laboratory results. <br /> V <br /> La 163-89-161 <br />