Laserfiche WebLink
passes through the former underground storage tank location, and adjacent, shallower wells <br /> (DMW-5 and DMW-6) show residual groundwater contamination. The wells will be overdrilled <br /> with 12-inch hollow-stem augers by Gregg Drilling and Testing of Martinez, California. The <br /> resulting boring will then be backfilled with a cement-based grout. <br /> The remaining monitoring eight wells (DMW-1, DMW-2, DMW-3, DMW-4, DMW-7, DMW-K, <br /> DM.W-10, and DMW-13) will be destroyed by over-drilling with a hollow stem auger drill rig to <br /> a depth of approximately 5 feet bgs. The remaining casing will be scaled with a cement-based <br /> grout placed under pressure. The grout will be placed with a tremmic pipe from the bottom up. <br /> When the grout has filled the casing to the surface, a pressure-grouting adaptor will be installed <br /> and a pressure of 25 psi will be applied for ten minutes. The adaptor will then be removed and <br /> the grout topped off and allowed to spill into the excavation above the top of the retraining <br /> casing. The surface will then be capped to match the surrounding surface. <br /> A well destruction permit will be obtained from the San Joaquin County Environmental Health <br /> Department, and a minimum 48-h0ur notice will be provided prior to commencing work. Daily <br /> health and safety briefings will be held in accordance with the existing Site Health and Safety <br /> Plan. Soil cuttings generated during the well destruction activities will be stored onsite in a <br /> rolloff bin or in 55-gallon drums prior to appropriate disposal pending analytical results. <br /> Approximately four weeks following completion of the work a report of well destruction will be <br /> prepared describing the procedures used, and providing analytical laboratory reports and <br /> manifests related to waste disposal. <br /> URS Corporation <br /> 2870 Gateway Oaks Drive, Suite 300 <br /> Sacramento,CA 95833 <br /> Tel 916.679.2200 <br /> Fax9166792900 <br />