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�y <br /> Mr. Harlin Knoll <br /> RI . N <br /> San Joaquin County Environmental Health Division <br /> 13 November 2001 <br /> Page 3 <br /> ❑ Overdrill each well boring and remove well, screening material, and sealing <br /> material for three 2-inch-diameter Schedule 40 PVC groundwater <br /> monitoring wells (designated as MW-1, MW-2, and MW-3; Figure 2) using a <br /> hollow stem auger rig. <br /> •. Backfill the former well borings with a bentonite slurry using the <br /> hollow-stem auger as a tremie pipe <br /> • Dispose of former well materials <br /> • Place auger cuttings (grout and soil) and any generated wastewater into <br /> 55-gallon drums for offsite disposal <br /> • Finish the surface of each boring to match the surrounding sidewalk <br /> surface <br /> ❑ Pressure grout one 3/4-inch-diameter Schedule 40 PVC groundwater <br /> monitoring well located inside an auto repair building (MW-4; Figure 2) by <br /> filling the casing and annular space with a bentonite slurry to a height of <br /> 5 feet below ground surface, removing the upper 5 feet of well casing and <br /> materials, and capping the upper 5 feet with concrete to the building floor <br /> su rface. <br /> • Casing and annular space will be backfilled by attaching a pressure-tight <br /> fitting at the well head and pumping a bentonite slurry mix into the well <br /> to a height of 5 feet below grade <br /> • Remove and dispose of upper 5 feet of well casing and materials <br /> • Backfill upper 5 feet of well boring with concrete <br /> • Finish the surface of the boring to match the surrounding building floor <br /> Details of Orion's field procedures for the proposed field program are described in <br /> Attachment 1 — Field and QA/QC Procedures. Also enclosed with this letter are <br /> Monitoring Well Destruction permit applications (Attachment 2) and a sample <br /> i <br /> IS:\BFS\Stockton\WKP\WKP004.doc] 11/13/01 <br /> I <br /> f <br />