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APPENDIX E <br /> ALTON GEOSCIENCE GENERAL FIELD PROCEDURES <br /> FOR <br /> GROUND WATER MONITORING WELL CONSTRUCTION <br /> Monitoring wells were constructed of clean, 4-inch-diameter, <br /> flush-threaded, Schedule 40 polyvinyl chloride (PVC) , blank <br /> casing which extended from grade level to a depth estimated at <br /> the highest anticipated water level, and 4-inch-diameter screened <br /> casing with 0 . 020-inch perforations extending to a depth of at <br /> least 10 feet into the water table. The casings, fittings, <br /> screens, and other components of the well construction were clean <br /> before installation. <br /> The annular space surrounding the screened portion was backfilled <br /> with No. 3 Monterey sand (filter pack) to approximately 1 foot <br /> above the top of the screened section. A bentonite annular seal <br /> (approximately 1 foot thick) was placed above the filter pack. <br /> The remaining annulus was grouted with neat cement to the <br /> surface. Monument well boxes were installed slightly above grade <br /> to minimize infiltration of surface water. Locking, watertight <br /> well caps were installed to ensure the integrity of the well . <br />