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DER <br /> Bright Bright People.Right Solutions. <br /> Installation of the sand may require that the sand be tremmied, using <br /> clean water. yl,� 307o !:'#lick <br /> • A 3- to 5-foot bentonite plug is placed above the sand pack to provide a /-� FG� <br /> seal against surface water infiltration and to reduce the potential for 3 .r /G�Pwf <br /> cement rout to infiltrate into the water. ��v� �`'� <br /> g wtia� VhtX i . '•' c (1 <br /> • The remaining annular space is filled to the surface with cement/bentonite <br /> grout. <br /> • The wells are secured in an aboveground or underground locking <br /> stovepipe. The well heads may be enclosed in a water tight cement utility <br /> box set flush to the ground surface when located in a traffic area. <br /> 3.2 Monitoring Well Development <br /> The wells are developed to reduce the effects of drilling on the formation and to <br /> increase the effective hydraulic radius of the wells. <br /> Monitoring wells are generally developed 24 to 48 hours after installation to allow the <br /> grout to set. Each well is first sampled with a clear disposable bailer to visually inspect <br /> for a hydrocarbon layer or sheen. If no product layer or sheen is observed on the water, <br /> the well is developed by surging, pumping or bailing. Surging along the screened <br /> interval of the well is performed to draw the sediment from the formation into the filter <br /> pack and the well, and to set the sand pack. Development continues until the discharge <br /> runs relatively clear of fines. Approximately 5 to 10 well volumes are generally removed <br /> from each monitoring well. Discharge water is stored in 55-gallon drums and left on site <br /> for later discharge or disposal by the client, depending on laboratory results. The drums <br /> are labeled with the date, well number, and a contact person and phone number. <br /> 3.3 Equipment Decontamination <br /> To reduce the potential for cross-contamination between wells, developing equipment is <br /> washed in a trisodium phosphate or non-phosphate detergent solution and rinsed in <br /> distilled water or steam cleaned prior to use in the next monitoring well. <br /> 3.4 Well Survey <br /> The locations of soil borings and monitoring wells, and the elevation of the top of the <br /> PVC casings are usually surveyed and tied into permanent markers, if readily available. <br /> Survey accuracy is 0.1 foot for the "x" and "y" coordinates and .01 foot for the "z" <br /> coordinate. The depth to static groundwater is measured from a set location at the top <br /> of the PVC casing (usually the north rim). The depth of water is then subtracted from <br /> the elevation of the top of the well casing to provide a groundwater elevation for each <br /> monitoring well location. <br /> 114050.WP/STO12P0580 Page v of vii July 16, 2012 <br /> Copyright 2012 Kleinfelder <br />