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Ge0lag1c1J(7"tChAWSPtC Page 2 <br /> Soil and Groundwater Investigation Work Plan <br /> Cardoza(Main St) <br /> . ProtectNo 662 2 <br /> 1 <br /> January 17,2003 <br /> In accordance with SJC/EHD directives, a continuously cored, single boring was installed <br /> on May 30, 2002 A discretely screened deep monitoring well, MW-104, was installed in <br /> the boring This well has been sampled twice since its installation and it has contained <br /> MTBE on both occasions <br /> Since well MW-104 was installed, SJCIEHD staffing has changed In their November 18, <br /> 2002 letter correspondence, SJCIEHD has rescinded previously submitted work plans and <br /> have called for phased approach to continue the site investigation The phased approached <br /> consists of cone penetrometer testing (CPT), followed by monitoring well installation, and <br /> 1 groundwater extraction well installation and aquifer testing <br /> 2.0 WELL ABANDONMENT <br /> SJCIEHD expressed a concern that the existing shallow wells at the site, MW-1 through <br /> MW-3, are acting as a conduit for contamination to reach the deeper aquifer To alleviate <br /> this concern, GTI proposes abandoning the three wells and replacing them with new shallow <br /> wells as discussed below in Section 3 <br /> The wells will be abandoned by over drilling the borehole using a 10-12 inch outside <br /> diameter, continuous flight, hollow stem auger drill rig owned and operated by V&W <br /> Drilling (C574 720904) This method will ensure that the entire casing, filter pack and <br /> grout are removed The boreholes will be filled by pumping neat cement grout (augmented <br /> with < 4% bentonite) through the tremie tube inserted in the augers as the auger sections are <br /> removed The top five feet of the borehole will be filled with clean soil and a concrete cap <br /> will be used to match grade surface 5"ia ak l� L, a»L " f.74t #{tt ePT,"V 5t,5a1 rk ry J <br /> .;4,- ti"e+r prF<.ss�r�•�•F aF n.+� ak tGi. kt[L:r,'�j <br /> 3.0 PROPOSED INVESTIGATION <br /> �ah�tw.,,4.,1, f 3 <br /> ' To further investigate the extent of soil and groundwater impacted with gasoline range <br /> petroleum hydrocarbons, GTI proposes to install additional groundwater monitoring wells <br /> using a phased approach as mandated 'by SJC/EHD The first phase will consist of <br /> advancing boreholes with CPT inethods to determine site lithology Based on the site <br /> lithology, GTI will then select the screened intervals of the proposed monitoring wells that <br /> may be individual PVC casings or continuous multi-chamber tubing (CMTT") wells In <br /> addition, GTI will collect soil and groundwater samples during the CPT field work and <br /> ' analyze these samples for petroleum hydrocarbon compounds <br /> An additional water table well is proposed adjacent to MW-104 for plume definition As <br /> stated above well MW-104 has contained MTBE for the two sampling events conducted <br /> 3.1 Cone Penetrometer Testing <br /> ' Cone penetrometer testing (CPT) uses specialized technology to determine subsurface <br /> lithology It consists of using a large truck to apply massive force to drive a cone at the <br /> head of rods through the subsurface Friction, pore water pressure and tip resistance are <br /> ' measured as the cone moves downward and these values can be correlated to determine the <br /> type of soil present <br />