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f 23 November 1998 AGE-NC Project No 95-0103 Page 6 of 7 ' lesser concentrations in wells MW-1, MW-3 and MW-5 Detectable concentrations of hydrocarbons were not present in the samples collected from the off-site wells MW-2 and MW-6 and MW-7 ' - A reduction of the dissolved-phase hydrocarbon plume concentrations in the central and eastern portion of the site has occurred A minor increase of the dissolved hydrocarbon ' concentrations has occurred at the location of well MW-5, however a reduction of contaminant concentrations has occurred in well MW-3 The current concentration of benzene in well MW-1 is 0 2 % of the initial and highest ' concentration of benzene detected in the well The detection of benzene in well MW-1, during the December 1997 sampling event when the ground water level was two feet above ' the well screen interval,was 0 5 %of the initial concentration of benzene detected in the well (Appendix E) The current concentration of benzene in well MW-4 is 7 % of the initial and highest ' concentration of benzene detected in the well The current concentration of benzene in well MW-3 is seven time greater than the initial concentration of benzene detected in the well However,the current concentration of benzene in well MW-3 is 22 time less than the current concentration of benzene in well MW-4, in the site(Appendix E) DIPE,MTBE,TBA were detected in water samples collected from wells MW-1,MW-3 and MW-5 MTBE was detected at concentrations less than the State of California Action Limit of 14 ppb in ground water samples collected from all four wells The MTBE was encountered in ground water samples at concentrations ranging as high m 13 ppb (MW-1) - The concentrations of benzene exceeds the state maximum contaminant level (MCL) of 1 ppb in three wells ' - Between July and September 1998,the SVE system extracted an estimated 13 48 gallons of gasoline from the site Since initiation of the SVE system an estimated total of 407 gallons ' of gasoline have been removed. AGE believes that the SVE system has removed most of the hydrocarbons from the vadose soil zone in the SVE system's area of influence It is likely that soil contamination remains ' in saturated soil in the core portion of the dissolved hydrocarbon plume Benzene concentrations in the extracted soil-vapor have been reduced to less than the ' detection limit of the soil vapor analytical method 8020 (Table 4) Advanced GeoEnvironmental,Inc.