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4 > <br /> Ms Vicky McCartney <br /> Page 2 <br /> • 80% water level recovery Purge water was contained in a properly labeled DOT-approved 55- <br /> gallon drum The drum is currently being stored onsite Purge logs are included in Attachment A <br /> Groundwater samples were delivered under chain of custody protocol to Argon Laboratories (ELAP <br /> #2359) Analysis consisted of TPHg using modified EPA method 8015B, and BTEX using EPA <br /> method 8021B Per the March 22, 2000 letter from San Joaquin County Environmental Health <br /> Department, groundwater samples were not analyzed for fuel oxygenates <br /> Groundwater Analytical Results <br /> r�O cr'�it.,,p� <br /> TPHg, toluene, ethylbenzene and xylenes were not detected above laboratory 4=1h- r�P+Pnt,rvi <br /> limits s) in any site wells <br /> JY'"gyiiIaIa1( <br /> Benzene was detected in wells MW 1 and MW3 at concentrations of 20 parts per billion (ppb) and <br /> 54 ppb, respectively Benzene was not detected in well MW2 Analytical results are summarized in <br /> Table 2 Attachment B contains laboratory reports and chain of custody documentation Graphs of <br /> benzene concentrations over time are included in Attachment C <br /> Summary <br /> • Groundwater levels at the site fell since last monitored in February 2004 These are the <br /> • lowest water table elevations measured since monitoring began in October 1998 The average <br /> groundwater gradient across the site was 0 01 ft/ft Groundwater flowed predominantly in a <br /> northeasterly direction, which is consistent with previous measurements <br /> m�'" <br /> • TPHg, toluene, ethylbenzene and xylenes were not detected above 1 fs in any site well <br /> • TPHg in all site wells has decreased to non-detectable levels The benzene in well MW1 was <br /> the same as when it was previously sampled in February of 2004 Benzene was not detected <br /> in well MW2 Benzene in well MW3 decreased since last sampled <br /> Conclusions <br /> Dissolved benzene is the only groundwater contaminant of significance identified at the site Benzene <br /> concentrations in well MW 1 have been steadily decreasing since the late 1990's Concentrations in <br /> downgradient well MW3 have historically exhibited significant variability between sampling events <br /> However, there had been an overall trend of increasing benzene levels in this well since the late <br /> 1990's The latest data suggest that concentrations may have begun to stabilize in well MW3 <br /> G 1GR0UNDZEIW-E\SAR125AR2004 doe <br />