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Work Plan for Destruction of <br /> Soil Vapor Extraction and Sparge Wells <br /> Former Ranch Market,Riverbank CA <br /> Page 5 <br /> original bore hole,applying a mushroom cap of neat cement grout in the upper bore hole,and restoring <br /> the ground surface to like conditions. Over-drilling is difficult on small diameter wells because the <br /> drilling contractor does not have a pilot"reamer" small enough to effectively remain centered over <br /> the well to the full installation depth,which varies at this site from approximately 43 to 45 feet deep. <br /> However, since the annular seal of the sparge wells extend to a depth of 37 feet bgs,coupled with the <br /> very coarse-grained nature of the shallow aquifer in which the sparge points are completed,there will <br /> be no potential for vertical migration of contaminants once the sparge wells are pressure-grouted and <br /> the mushroom caps are emplaced. Well construction details for the sparge wells and estimated grout <br /> volumes for well destruction are included in the table below. <br /> Well Construction Details—Air S ar a Wells <br /> Boring Casing Total Sand Pack Estimated Neat Estimated Neat <br /> Diameter Diameter Depth Depth Interval Cement to Cement for <br /> (inches) (inches) (feet) (feet bgs) Grout Casing Mushroom Cap <br /> (gallons) (gallons) <br /> S-1 8 0.75 44 37-44 1 10 <br /> S-2 8 0.75 45 37-45 1 10 <br /> S-3 8 0.75 43 37-43 1 10 <br /> S-4 8 0.75 43 37-43 1 10 <br /> S-5 8 0.75 43 37-43 1 10 <br /> S-6 8 0.75 43 37-43 1 10 <br /> S-7 8 0.75 45 37.45 1 10 <br /> S-8 8 0.75 44 37-44 1 10 <br /> S-9 8 0.75 43 37-43 1 10 <br /> S-10 8 0.75 43 37-43 1 10 <br /> S-11 8 0.75 44 37-44 1 10 <br /> S-12 8 0.75 43 37-43 1 10 <br /> S-13 8 0.75 44 37-44 1 10 <br /> S-14 8 0.75 44 37-44 1 10 <br /> S-15 8 0.75 44 37-44 1 10 <br /> S-15 8 0.75 44 37-44 1 10 <br /> S-16 8 0.75 43 37-43 1 10 <br /> S-17 8 0.75 44 37-44 1 10 <br /> S-18 8 0.75 43 37-43 1 10 <br /> S-19 8 0.75 43 37-43 1 10 <br /> S-20 8 0.75 43 37-43 1 10 <br /> The abandonments will be conducted under the supervision of a Condor geologist. The traffic box will be <br /> removed from around each well casing to attach a pressure fitting, and the casing will be pressurized at <br /> approximately 15-20 pounds per square inch (psi) for approximately five to 10 minutes to allow for <br /> maximum•displacement of grout from the well casing into the sand pack. The grout will be placed in one <br /> continuous operation if possible. The volume of neat cement injected will be recorded for each well and <br /> �il� CONDOR <br />