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16 April 2012 <br /> AGE-NC Project No. 98-0497 <br /> Page 2of3 <br /> WELL DESTRUCTION PROCEDURES <br /> On 26 and 27 March 2012, monitoring wells MW-1 through MW-6 were destroyed under <br /> EHD oversight utilizing a CME-75 truck mounted drill rig equipped with 8.25-inch diameter <br /> hollow stem augers. The drill rig .and two-person crew were supplied by All Well <br /> Abandonment, of Sacramento, California. <br /> Prior to destruction activities, each well casing as sounded with a Solinst water level <br /> meter to ensure no obstructions were present in the casings. Subsequently,well boxes and <br /> caps were removed to expose the well casings. <br /> Monitoring wells MW-1 and MW-6 were complete) drilled-out to depths of approximately <br /> 78 feet and 135 feet bsg, respectively, using 8.25-inch hollow-stem augers. All original <br /> construction materials were removed during the rill-out (including casing, screen, filter <br /> pack and annular seal) to ensure that no residual contamination was sealed within the <br /> abandoned borehole. At total depth, the remaining borehole space was then backfilled to <br /> surface grade with a Portland type II grout mixture, and completed at the surface with <br /> concrete. A ratio of three gallons of water for every 50-pound sack of portland cement was <br /> utilized to prepare the grout mixture. <br /> Monitoring wells MW-2 through MW-5 were destr yed by grouting the well casing under <br /> pressure. The well heads were fitted with a pressure tight adapter connected to a hose <br /> extending from a grout mixer. The grout mix ratio consisted of three gallons of water for <br /> every 50-pound sack of portland cement. The grout mixture was pumped into each well <br /> casing under approximately 25 pounds per sq are inch (psi) of pressure and was <br /> sustained for ten minutes to allow for grout to infil rate the casing screen. <br /> Following pressure grouting procedures,a 20-inch diameterarea was excavated to a depth <br /> of approximately 3 feet bsg, around the casing of each well. The top two and one-half feet <br /> of each well casing was removed and the 3-foot d ep excavation was grouted to the near <br /> surface using the portland cement grout mixture and completed at the surface with <br /> concrete. <br /> Well construction materials and auger returns generated by drilling were containerized in <br /> properly labeled Department of Transportation (DOT)-approved model 17H 55-gallon <br /> drums and were stored on-site. <br /> Advanced CeoEnvironmental,Inc. <br />_ I <br />