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k+ <br /> F. GeofogicafTechnicsinc. <br /> F; 2741 River Road <br /> Modesto,cafifamia 95.351 <br /> (209)538-G4241Tar,#538-5852 <br /> Work Plan <br /> Well Abandonment <br /> F. Ted Peters Tr eking <br /> 1985 Yosemite Ave. <br /> Manteca,'CA 95336 <br /> Project No. 640.2 <br /> June 14, 2001 <br /> 1.0 INTRODUCTION <br /> There are eight groundwater monitoring wells currently located at the site (see Figures I & <br /> 2). Wells MW-1 through MW-3 were placed in the vicinity of a former gasoline <br /> underground storage tank located on the southern portion of the property. The rest of the <br /> monitoring wells were installed for the purpose of investigating the above ground tank area <br /> in the central portion of the property. In our " roundwater Monitoring Report -- Spring <br /> ..Quarter 2000" dated August 18, 2000, Geological Technics Inc. recommended site closure <br /> based on the fact that there is a negligible gasol ind impact to soil and groundwater and there <br /> are no oxygenates detected in groundwater from the wells. <br /> Even though we have not received comment from the San Joaquin County PHS/EHD on the <br /> Fproposed site closure, we are submitting this plan lbr closure to facilitate the process. <br /> -We propose to abandon 'two of the monitoring wells, MW-2 and MW-3. The third well <br /> (MW-1) will be retained in order to support the above ground storage tank investigation <br /> r being conducted for the rear of the parcel. <br /> 2.0 PROPOSED FIELD WORK-WELL ABANDONMENT <br /> The following procedure is proposed for the destruction of wells MW-2 and MW-3: <br /> ❑ The wells will be over drilled to their to inus depth of 20' feet below grade surface <br /> (bgs) utilizing a hollow stem auger drill rip. <br /> ❑ A neat cement grout (containing less th n 4% bentonite) will be pumped under <br /> pressure through a tremie pipe to the bo tom of the borehole. In this manner the <br /> F grout will displace the water in the borelic le insuring that the borehole is completely <br /> filled with grout. <br /> D After the grout has been installed, the top three feet of the borehole will be filled up <br /> to ground surface with concrete. <br /> ❑ The estimated grout-volumes are included in Table 1. Actual grout volume used in <br /> the field will be tracked. <br />