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% ../ <br /> water table surface in order to convert the boring into a monitoring well. If groundwater <br /> contamination is encountered a minimum of three and a maximum of four monitoring wells will <br /> be installed in the contaminated site. <br /> All monitoring wells will be constructed of four-inch diameter, schedule 40, PVC blank <br /> casing with 30-feet of 0.02 slotted screen at its bottom (Figure 2). Typically twenty feet of <br /> perforated casing will extend below the water table surface and the remaining ten feet will <br /> extend above it. The annular space between the perforated casing and the excavation wall will be <br /> sand packed with Lapis Luster#lc sand to a level two feet above the screened interval. Directly <br /> above the sand pack a one-foot spacer of bentonite pellets or crushed natural bentonite granules <br /> will be placed. All depths of sand pack and sealing grout will be verified by sounding with a <br /> weighted tape. The remaining annular space will be filled up to the surface with a neat <br /> cement/bentonite grout. <br /> Surface completions of the wells will depend on the protective needs for each well. In areas <br /> of low probability of damage the top of each well will be just below grade and the casing will be <br /> capped with a flush mounted"Christy type" box. In areas of higher damage probability, the well <br /> will be completed above grade with a three-foot standpipe and a locked cap. Construction details <br /> of each well will be recorded and presented in the final report. Any remaining borings not turned <br /> into monitoring wells will be backfilled and grouted flush with the surface. <br /> Well Development <br /> All wells will be fully developed to the extent practical in order to improve hydraulic <br /> continuity with the native matrix. Development will be performed using pumping, bailing or <br /> surging of the well to a sand free state. All water volumes will be recorded along with the <br /> periodic pH and conductivity measurements. Development will cease when the well produces <br /> little or no fine sediment and the water parameters have stabilized. <br /> Groundwater Sample Collection <br /> At the conclusion of all drilling and well development work groundwater sampling will <br /> be undertaken on all installed wells. Sample volumes will consist of two one-liter containers and <br /> a pair of 40-m1 VOA vials. Each sample container will be filled to overflowing, capped and then <br /> checked for trapped gas by inversion and tapping. If an air bubble is observed in a vial, that vial <br /> will be reopened and topped off with additional water from the bailer. All samples will be <br /> properly labeled and then placed into a chilled cooler for transportation to a state certified <br /> laboratory for analysis. Strict chain-of-custody protocol will be followed during all phases of <br /> sample handling. In conjunction with the collection of water samples, field analysis for specific <br /> conductance, pH and temperature will be performed at each wellhead using appropriate test <br /> equipment. <br /> 4 <br />