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CrcologualTeck�ucs!►rG Page 2 <br /> Dual Phase Extraction Pilot Test Report <br /> Project No 662 2 <br /> February 22,2005 <br /> 1 <br /> On May 16 & 17, 2001 Geological Technics Inc (GTI) advanced seven (7) GeoProbe <br /> i boreholes (GP-3 through GP-9), collected soil and groundwater samples, and analyzed these <br /> samples for petroleum hydrocarbon compounds The results of the laboratory analyses did <br /> not reveal shallow soil or groundwater contamination along the eastern or southern side of <br /> ' the property <br /> In accordance with SJC/EHD directives, a continuously cored, single boring was installed on <br /> May 30, 2002 A discretely screened deep monitoring well, MW-104, was installed in the <br /> boring This well has been sampled six times since its installation and it has contained <br /> MTBE on all occasions <br /> iSince well MW-104 was installed, SJC/EHD staffing had changed In their November 18, <br /> i 2002 letter correspondence, SJC/EHD rescinded previously submitted work plans and called <br /> for phased approach to continue the site investigation The phased approached consisted of <br /> cone penetrometer testing (CPT), followed by monitoring well installation, and groundwater <br /> i extraction well installation and aquifer testing GTI submitted our January 17, 2003 work <br /> plan to meet the SJC/EHD directives and they approved the CPT and groundwater extraction <br /> well portion of the work plan in their February 14, 2003 letter Eight CPT borings, CPT-1 <br /> through CPT-8, and an extraction well, EW-1, were installed in December 2003 <br /> Groundwater samples obtained from the CPT boreholes reveal that the residual <br /> i contamination is sourcing a submerged plume that has migrated to the location of CPT-7 A <br /> sand layer is present at a depth of 38 — 48 feet across the site and it appears to act as a <br /> preferential pathway for contaminant migration <br /> iGTT subrrutted our April 19, 2004 work plan for a dual phase extraction feasibility study and <br /> further soil and groundwater investigation The work plan included provisions for 1) the <br /> ' installation of a shallow soil vapor/groundwater extraction well, 2) performing a dual phase <br /> aquifer pumping test to determine if soil vapor extraction is feasible at the site and to <br /> determine aquifer pumping characteristics, and 3) the installation of two additional <br /> igroundwater monitoring wells for further site definition SJC/EHD approved the work plan <br /> in their May 21, 2004 facsimile correspondence <br /> iThe following sections detail the completion of the field activities as proposed in our April <br /> 19, 2004 Work Plan <br /> i <br /> 2.0 ADDITIONAL SITE CHARACTERIZATION <br /> iThe CPT boreholes advanced in December 2003 revealed that most of the residual soil <br /> contamination is located under the former USTs This soil contamination continues to source <br /> a submerged plume that is migrating off site to the location of CPT-7 at a depth of 45 feet <br />