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I <br />' 20 May 1998 <br /> AGE-NC Project No 95-0130 <br />' Page 4 of 5 <br /> . Ground water flow direction at the site(the area containing wells MW-1 through MW-5)was <br />' estimated to be in a northeast flow direction <br /> . The ground water surface elevation at the site continues to remain above the slotted screened <br />' intervals in wells MW-1 through MW-5 and VW-1C Therefore, samples collected from <br /> these wells may not be representative of dissolved petroleum hydrocarbon concentrations In <br /> shallow ground water <br />' . From November 1997 to February 1998, substantial dissolved hydrocarbon-concentration <br /> decreases were observed from wells MW-5 and VW-1C The substantial decreases reported <br /> from MW-5 and VW-I C could be attributed to the recent submergence of screen intervals <br /> observed at these well locations <br /> TBA continues to be detected in water samples collected from MW-3 TBA was detected for <br /> the first time in water samples collected from wells MW-1 <br /> Concentrations of benzene detected in samples collected from wells MW-2, MW-3, MW-5, <br /> VW-I C, VW-2A and VW-3A were above the State of California Maximum Contaminant <br /> Level (MCL) for drinking water of 10 ppb <br /> • . Concentrations of toluene were above the MCL of 150 ppb in wells VW-I C, VW-2A and <br /> VW-3A <br /> a Concentrations of ethylbenzene were above its MCL of 700 ppb in wells VW-1C, VW-2A <br /> and VW-3A <br /> Concentrations of xylenes were above the MCL of 1,750 ppb in wells VW-I C, VW-2A and <br /> VW-3A <br /> . Utilizing EPA Methods 8020 and 8260, concentrations of MTBE were detected above the <br /> laboratory reporting limits in samples from wells MW-1,MW-3, VW-I C, VW-2A and VW- <br /> 3A <br /> . DIPE was detected utilizing EPA method 8260 in ground water samples collected from MW- <br /> 2 for the first time <br /> . TBA was detected from MW-I for the first time <br /> The elevated concentrations of petroleum hydrocarbons detected in samples collected from <br /> wells VW-IC,VW-2A and VW-3A,indicate that these wells are within or near the dissolved <br /> petroleum hydrocarbon "core area" of the plume <br /> A plot of depth to ground water and TPH-g concentrations over time (Appendix C) suggests <br /> a negative correlation at wells MW-3 and MW-5 between increasing/decreasing ground <br /> • water elevation and increasing/decreasing TPH-g concentrations <br /> Advanced GeoEnvirORmental,Inc <br />