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SOP No. 5.0 Monitoring Well Install 1, <br />Alternatively, the annular space can be backfilled with a bentonite slurry if the potential exists for <br />cross-containination of adjacent wells. This may occur when wells are installed in pairs, and the <br />grouted interval in a deep well coincides with the water bearing zone to be screened in a shallow <br />well. <br />5.2.1.5 Surface Seal Installation <br />Groundwater monitoring wells will be constructed with above-ground completions. A concrete <br />surface seal will be placed around the annulus of the well to a minimum depth of one foot or to <br />the top of the bentonite/cement grout, whichever is deeper. Twenty-four hours should elapse <br />between grout emplacement and installation of the surface seal to allow the grout to cure and <br />shrink and prevent a cavity from forming between the two seals. The well casing will be <br />extended 2 to 3 feet above land surface, and a reference point will be marked for future water <br />level measurements on the north side of the casing using a decontaminated metal file. A casing <br />cap for each well will be provided, and the extended casing will be shielded with a protective <br />steel casing that has a locking cap placed over the PVC well casing. The steel casings will be <br />cemented in place and will extend a minimum of 3 feet below ground surface and 3 feet above <br />ground surface. Center the protective steel casing around the monitoring well casing and insert <br />the steel casing approximately 3 feet into the cemented annulus. The protective casings will be a <br />minimum of 6 inches larger in diameter than the PVC monitoring wells. The protective steel <br />casing will be seated in a 4-foot by 4-foot by 6-inch concrete surface pad. The pad will be sloped <br />away from the protective casing. The concrete pad surface will extend approximately 1 inch <br />above ground surface with about 5 inches below grade. At least one small hole will be drilled at <br />the base of the protective casing to allow water to drain from the casing. The well number or <br />identification code will be indelibly marked on the protective casing and on the well cap. A <br />lockable cap or lid will be installed on the protective casing. In high traffic areas near roads or <br />parking areas, the steel protective casing will be protected by four, 4-inch-diameter, Schedule 40, <br />steel guard posts. The guard posts will be 6 feet in total length, with 3 feet bgs and 3 feet above <br />ground surface. The guard posts will be set in concrete, but will not be installed in the concrete <br />pad placed at the well base (ASTM 1996, EPA 1990). <br />All wells will be secured as soon as possible after drilling. Corrosion-resistant locks will be <br />provided for the steel protective casing. The locks must either have identical keys or be keyed for <br />opening with one master key. <br />5.3 Well Types <br />Four types of monitoring well or tensiometer completions could potentially be completed from <br />the drill holes and they may be completed in clusters (SRT Drilling Plan, 2003). The wells and <br />tensiometers will be located to most advantageously meet the data quality objectives (DQOs) as <br />determined by the Pls. The Type 1 well will be a monitoring well completed within the <br />narrowest drill hole available. This well would be completed with 2.0 inch PVC casing in a 6 <br />5/8 inch drill hole (Becker) or 7 5/8 inch (Sonic) drill hole. The purpose of the Type 1 well is to <br />collect a subsurface water sample, if water encountered and/or to provide access to the <br />geophysical tools (SOP 23). The Type 2 well will be composed of nested monitoring wells <br />completed in a 9 inch diameter drill hole (Becker) or 8 5/8 inch (Sonic) drill hole. The purpose <br />7/28/08 Page 7 of 10 R Squared Inc.