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= �= ! �" "Em". w <br /> i <br /> c-. <br /> i <br /> 1 <br /> ALTON GEOSCIENCE, INC. <br /> GENERAL FIELD PROCEDURES <br /> FOR <br /> GROUND WATER MONITORING WELL CONSTRUCTION <br /> The number, location, and depths of the ground water <br /> monitoring wells will be selected prior to commencement of <br /> work, and may require relocation or modification as the work <br /> proceeds. The ground water wells will be constructed of of <br /> clean 2-inch-diameter, flush-threaded, Schedule 40 PVC blank <br /> casing which extends from grade level to a dent.; estimated at <br /> the highest anticipated water level, and 2-inch diameter <br /> screened casing with 0.010 or 0.020-inch perforations <br /> extending to a depth of at least 10 feet into the water <br /> table. The casings, fittings, screens, and other components <br /> of the well construction shall be thoroughly steam cleaned <br /> before installing the well. <br /> The annular space surrounding the screened portion will be <br /> backfilled with No. 3 Monterey sand (filter pack) to . <br /> approximately 2 foot above the top of the screened section. <br /> A bentonite annular seal (approximately 1-foot thick, will be <br /> placed above the filter pack. The remaining annulus will be <br /> grouted with neat cement to the surface. Monument well boxes <br /> will be installed slightly above grade to minimize <br /> _ infiltration of surface waters. Locking, water-tight well <br /> caps will be installed to ensure the integrity of the well. <br />