SITE INFORMATION AND CORRESPONDENCE

Home Browse Search

20 May 2011 AGE-NC Project No. 00-0764 Page 2of3 WELL DESTRUCTION PROCEDURES On 26, 27 and 28 April 2011, monitoring wells MWA through MW4 were destroyed at the site, under EHD oversight, utilizing a CME-75 truck mounted drill rig equipped with 8.25-inch diameter hollow stem augers. The drill rig and two to three-person crew were supplied by RSI Drilling, of Woodland, California. Prior to destruction activities, each well casing was sounded with a Solinst water level meter to ensure no obstructions were present in the casings. Subsequently,well boxes and caps were removed to expose the well casings. r Monitoring wells MW-2 through MW-4 were drilled-out to depths of approximately 71 feet bsg; using 8-inch hollow-stem augers. All original construction materials were removed (including casing, screen, filter pack and annular seal) to ensure that no residual contamination was sealed within the abandoned borehole. The remaining borehole was then backfilled to surface grade with a grout mixture, to form a barrier to the vertical movement of water, at completed at the surface with concrete. A ratio of three gallons of water for every 4/7 pound sack of portland cementwas utilized to prepare the grout mixture. Monitoring well MWA was destroyed by grouting the well casing under pressure. Well MWA was fitted with a pressure tight adapter connected to a hose exten g from a grout mixer. A grout mix ratio consisted of three gallons of water for every -Pound sack of portland cement.The grout mixture was pumped into each well casing under approximately 2b 5.-V pounds per square inch (psi) of pressure. A 21-inch diameter area was excavated to a depth of approximately 3.5 feet bsg, around the casing of well MW-1. The top.three feet of the well casing was removed and the boring were grouted to the near surface using the portland cement grout mixture and completed at the surface with concrete. Well construction materials and auger returns generated by drilling were containerized in properly labeled Department of Transportation (DOT)-approved model 17H 55-gallon drums and were stored on-site. NON-HAZARDOUS WASTE DISPOSAL On 29 April 2011, approximately 250 gallons of non-hazardous rinse water containerized in 55-gallon drums, were removed from the site by InStrat, Inc., of Davis, California. Additionally, on 03 May 2011, approximately 11,880 pounds of soil cuttings, solid waste (i.e. well materials) and 110 gallons of rinse water were containerized in 55-gallon drums and removed from the site by Slaby Environmental, Inc., of Borrego Springs, California. Advanced CeoEnvironinental,Inc.