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GEOSYNTEC CONSULTANTS Ms. Amy Terrell 8 June 2001 Page 3 safety meeting will be held prior to the start of field activities and air monitoring will be performed throughout the investigation. The field operations will be conducted in accordance with all applicable federal, state, and local policies and regulations including training and medical monitoring required under 29 CFR 1910.120. Monitoring Well Installations Installation of the new monitoring well (MW-6) and HRC injections will be performed by EnProb Environmental Probing of Oroville, California (EnProb), C-57 License #777007. Existing monitoring well MW-4 will be used to monitor upgradient groundwater quality and existing wells MW-2 and MW-5 will monitor downgradient groundwater quality. The purpose of the new well is to measure changes in groundwater quality in the center of the HRC injection grid. The new monitoring well (MW-6) will be a small-diameter, pre-packed well with an outside diameter of 2 inches and an inside diameter of 3/a of an inch. Figure 3 shows a diagram of a typical small-diameter monitoring well. The screen lengths of the new monitoring well will be similar to that of MW-2 extending from approximately 15 ft to 30 ft below ground surface (bgs). The well screen will be constructed of Schedule 40 PVC with 0.01-inch slots. The well screen will be covered with a stainless steel mesh pre-packed with #2/12 filter sand. The annular space surrounding the well screen will be filled using the same #2/12 filter sand. The riser pipe will be constructed of blank, Schedule 40 PVC. A PVC seal will be placed on top of the well screens and approximately 18 inches of bentonite will be placed on top of the PVC seal. Following hydration of the bentonite seal, cement grout will be used to seal the annular space to the ground surface. The monitoring well will be sealed at the bottom and top with threaded or friction caps and at the surface with a flush-mount well box and sealable, traffic-rated cover plates. Following monitoring well installation, and prior to HRC injection, the new well will be developed and then sampled along with wells MW-4, MW-2, and MW-5. The purpose of the initial groundwater sampling is to obtain baseline groundwater quality data prior to HRC injection. Details of the analytical methods and sampling protocol are discussed in the groundwater monitoring section. \\WCREEK-01\DATA\PR1l\WFS\SHELL\VER\HRC plans\RWQCB Plan.doc el RECYCLED AND RECYCLABLE gj�