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13 August 1996 AGE-NC Project No 95-0125 Page 3 of 3 ' 32 ANALYTICAL RESULTS OF GROUND WATER SAMPLES TPH-g was detected in MW-2 and MW-6 at concentrations of 540 and 600 µg/1 (micrograms per ' liter, equivalent to parts per billion ppb), respectively BTE&X were detected in MW-2 and MW-6 at concentrations up to 30 ppb (benzene, MW-6) MTBE was not detected in the samples collected ' Analytical results of ground water samples are summarized in Table 2 The laboratory report(Alpha Analytical Laboratory batch No 96-0605-011) and chain-of-custody are presented as Appendix C 4.0. CONCLUSIONS AND RECOMMENDATIONS 41 CONCLUSIONS Between March and June 1996, concentrations of TPH-g and BTE&X increased in wells MW-2 and MW-6 However,only concentrations of benzene (12 ppb in MW-2, 30 ppb in MW-6)remain above the State of California drinking water Maximum Contaminant Level (MCL) of 1 0 ppb Excavated soil is presently aerating on-site under permit from the SJVUAPCD The aerating soil is scheduled to be sampled in late September or early October 1996 42 RECOMMENDATIONS ' Although low concentrations of petroleum hydrocarbons remain near the north end of the December 1995 excavation limits, we do not recommend active remediation at this time The next quarterly monitoring should be scheduled for September 1996 I5.0. LIMITATIONS Our professional services were performed using that degree of care and skill ordinarily exercised by environmental consultants practicing in this or similar localities The findings were based mainly upon analytical results provided by an independent laboratory Evaluations of the geologic/hydrogeologic conditions at the site for the purpose of this investigation are made from a limited number of available data points(i a monitoring wells) and subsurface conditions may vary away from these data points No other warranty, expressed or implied, is made as to the professional recommendations contained in this report