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i KLE/NFELDER <br /> B 9h oPl 9h(Solulioni. <br /> n !P¢ ¢Rr <br /> using clean water. In this event, a sample of the tremie water is collected, <br /> unless the source is known to be clean. <br /> • A 3- to 5-foot bentonite plug is placed above the sand pack to provide a seal <br /> against surface water infiltration. <br /> The remaining annular space is filled to the surface with tremmied <br /> cement/bentonite grout to the surface. <br /> The wells are secured in a locking stovepipe. The well heads may be <br /> enclosed in a cement utility box set flush to the ground surface located in a <br /> traffic area. <br /> A-3.2 Monitoring Well Development and Sampling <br /> The wells are developed to reduce the effects of drilling on the formation and to <br /> increase the effective hydraulic radius of the well. <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 acrylic bailer to visually inspect for <br /> hydrocarbon layer or sheen. If no product layer or sheen is observed on the water, the <br /> 1 well is developed by surging, pumping, or bailing. Surging along the screened interval of <br /> the well is performed to draw the sediment from the formation into the filter pack and <br /> the well and to set the sand pack. The sediment laden water is purged from the well at <br /> a rate of between 0.75 to 10 gallons per minute (gpm) depending on recharge rate and <br /> casing size. Development continues until the discharge runs relatively clear of fines. <br /> Approximately 5 to 10 well volumes are generally removed from each monitoring well. <br /> Discharge water is stored in 55-gallon drums and left on site for later discharge or <br /> disposal by the client, depending on laboratory results. <br /> After the wells are developed, the aquifer is allowed to equilibrate for at least 24 to 48 <br /> hours. The wells can then be purged and sampled. Purging and sampling may be <br /> accomplished with Teflon bladder pumps and/or bailers. During the purging of the wells, <br /> field parameters (pH, conductivity, and temperature) are monitored. Samples are <br /> collected after the field parameters have stabilized (normally requiring the removal of <br /> 101486.4/ST011 R242 Page A-5 October 31, 2011 <br /> Copyright 2011 Kleinfelder <br />