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C- V2 \U 9 <br /> A S S O C I A T E S I N C <br /> RESULTS <br /> Water levels have decreased an average of 125 feet since the last monitoring event on April 6, 2001 <br /> (Table 1) A groundwater gradient map was created using the data collected on July 6, 2000 (Figure <br /> 2) Groundwater primarily flows northeast, away from the slough, with a gradient of approximately <br /> 0 073 feet/foot or 387 feet per tulle <br /> TPHg and TPHd were not detected in any of the groundwater samples collected from wells MW 1 <br /> through MW7, although the detection hmlts for TPHg in the sample from well MW7 were elevated <br /> due to dilution factors BTEX and MTBE were not detected in the groundwater samples collected <br /> from wells MW 1 through MW4 and MW6 The samples from wells MW5 and MW7 contained <br /> benzene at concentrations of 0 9 and 27 parts per billion (ppb), respectively The samples from wells <br /> MW5, MW6 and MW7 contained MTBE at concentrations of 1,200 ppb, 7 5 ppb and 150,000 ppb, <br /> respectively Analytical results are summarized in Table 2 Laboratory reports with chain-of-custody <br /> documents are included in Attachment 2 <br /> RECOMMENDATIONS <br /> Due to the detectable concentrations of MTBE in the groundwater samples from wells MW5, MW6 <br /> and MW7, ATC recommends continued monitonng and sampling of all site wells (MW I through <br /> MW6)for TPHg, TPHd,BTEX, and MTBE by EPA Methods 8015/8020 <br /> If you have any questions or comments regarding this project, please contact our office at (209) 579- <br /> 2221 <br /> Respectfully submitted, <br /> ATC Associates Inc <br /> m Kundert <br /> Geologist <br /> a AwHy <br /> Jeanne Hornsey, P E <br /> CA Registered Civil Engineer No C47410 <br /> Attachments <br /> Y <br /> • cc CRWQCB <br /> James"J"Mills, Westrec Properties <br /> w 1625141quarily\3qr-2001 doc 2 <br />