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.• fr �" R' fir a <br /> s <br /> f� h <br /> 7 11 <br /> ..fl E7J` <br /> A S S O C I A T E S I N C r'3 4 n ? v 24 <br /> RESULTS <br /> Water levels have increased an average of 0 18 feet smce the last monitoring event on September 2, <br /> 1999 (Table 1) A groundwater gradient map was created using the data collected on December 1, <br /> 1999 (Figure 2) Groundwater primarily flows northeast, away from the slough, with a gradient of <br /> approximately 0 05 feet/foot or 260 feet per mile <br /> TPHg and BTEX were not detected m any of the groundwater Samples collected from wells MW 1 <br /> through MW6, although the detection limits for the sample from well MW5 were elevated due to <br /> dilution factors The samples from wells MW2, MW3, MW4R, MW5 and MW6 contained TPHd at <br /> concentrations of 50 8, 619, 70 4, 381 and 141 parts per billion (ppb), respectively TPHd was <br /> reported as an unidentified hydrocarbon in the samples from wells MW5 and MW6 The samples from <br /> wells MW5 and MW6 contained MTBE at concentrations of 9,350 ppb and 4 06 ppb, respectively <br /> Analytical results are summarized in Table 2 Laboratory reports with chain-of-custody documents are <br /> included in Attachment 2 <br /> RECOMAMNDATIONS <br /> Due to the detectable concentrations of MTBE in the groundwater samples from wells MW5 and <br /> MW6, ATC recommends continued morutonng and sampling of all site wells (MW 1 through MW6) <br /> 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 /> a <br /> -b(kLvo-,,� <br /> J <br /> Drew Van Allen s+ r <br /> Project Manager � ► `��� r <br /> JEANNE <br /> HQMS <br /> Jeanne Homsey <br /> CA Registered Civil Engineer No C47410 i °3 - <br /> �f F N ' `k <br /> Attachments �-� ,OF C AV, <br /> cc CRWQCB <br /> James"J"Mills,Westrec Properties <br /> w\625141quw l)l4gr-1999 doc 2 <br />