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;_9 CPT-2 and CPT-3 Relatively clean soil conditions in MW-4 to the northwest of CPT-4 appear to define the lateral extent of hydrocarbons to the northwest • The vertical extent of TPHg-impacted groundwater 1s not fully defined, however, MTBE and BTEX compounds benzene and toluene do not extend below the fine-grained interval from approximately 75 to 90 feet bgs, and the remaining compounds were present in only very low concentrations (Figures D-1, D-2, and D-3) • Dissolved-phase hydrocarbon concentrations in well MW-5 have declined overall from 1993 through 2004, concentrations of TPHg and MTBE are 3,240 ug/L and 3,650 ug/L, ' respectively as of August 17, 2004 • The possibility exists that an offsite source may be contributing to the dissolved groundwater plume beneath the site The former service station located at 1440 Harding Way is located immediately west or upgradient of the site The site has never been investigated and it is possible that a release has occurred given the fact that USTs were in ' use at the site from 1955 or earlier to 1977 when the USTs were removed 11.0 RECOMMENDATIONS Based on the data presented in the PSCM, the following recommendations are provided • The existing wells (MW-2, MW-3R, MW-4, MW-5, MW-6, TB-1, TB-7, TB-8, and TB- 10) should all be redeveloped to remove the silt build up using a well development rig Removal of the silt build up will result in more representative groundwater samples being collected from the wells • A workplan should be prepared to include a scope of work to address groundwater contamination at the site including the installation of at least one groundwater extraction well and subsequent testing of the well to determine if additional extraction wells are necessary to remediate the groundwater beneath the site • The SJCEHD should require that a site assessment be conducted at the former service ' station property at 1440 Harding Way upgradient of the Thrifly site to determine if hydrocarbon-impacted soil and groundwater is present at the site and possibly contributing to the dissolved hydrocarbon plume beneath the Thnfly site ' Should you have any questions, please contact the undersigned at (562) 921-3581 x404 Sincerely, D G�0�0 ' MICHAEI K BOW�Y Michael H �,Bowery, R G EV, 2. U6 !a M 6027 Q. Project Manager Rh of oAt�Fo 13