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I08 May 1997 AGE-NC Project No 95-0104 Page 3 of 4 I xylenes were detected at concentrations as high as 860 ppb Analytical results of TPH-g and BTE&X in ground water are summarized in Table 2 -Analytical Results of Ground Water Samples Halogenated volatile organic compounds (HVOCs) were detected in samples collected from wells MW-1, MW-5, MW-6 and VW-1 at concentrations ranging from 110 ppb (1,2-Dichloroethane in MW-6)to 170 ppb (1,2-dichloroethane in VW-1) Analytical results ofHVOCs in ground water are summarized in Table Nos 3 through 5 - Analytical Results Halogenated Volatile Organic Compounds ' MTBE was not detected from any ground water monitoring wells at the site during tlus quarterly sampling event The laboratory report (AAL Batch Number 97-0317-030) and chain-of-custody forms are presented in Appendix B 4 0. CONCLUSIONS AND RECOMMENDATIONS 41 CONCLUSIONS lie Based upon data collected during this investigation, AGE has the following conclusions I • Ground water flow direction and gradient remains relatively constant at the site In March 1997, the gradient was approximately 0 009 ft/ft(approximately 48 feet per mile) and directed easterly Monitoring well MW-2 is located up-gradient from the former UST area, while monitoring wells MW-3 through MW-6 are located in more down-gradient positions I a The ground water surface elevation at the site continues to remain above the slotted screened intervals in wells MW-2 through MW-6 Therefore, samples collected from these wells may not be representative of shallower ground water conditions at the site I • Due to elevated concentrations of petroleum hydrocarbons detected at VW-1, it appears that VW-I is located near the center of the dissolved hydrocarbon plume Concentrations of benzene detected in MW-1, MW-6 and VW-1 exceeded the State of California Maximum Contaminant Levels(MCLs) for drinking water of 1 0 µg/1, respectively • Concentrations of toluene detected in VW-I exceed the MCLS for drinking water of 150µg/1 • MTBE was not detected during the December 1996 sampling I