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' d BTEX concentrations were detected in twelve of the fourteen groundwater monitoring wells (MW-1, MW-2, MW-3, MW-4, MW-5, MW-6, MW-7, MW-8, VW-1, VW-2, MW-11, ' and MW-12) Detectable concentrations of benzene ranged from 0 4 to 2,300 micrograms per liter (ug/1) The concentrations have typically decreased since the previous quarters sampling event o MTBE concentrations were detected in seven of the fourteen monitoring wells sampled (MW-1, MW-2, MW-6, MW-7, VW-1, VW-2) Detectable concentrations ' ranged from 0 7 to 22 micrograms per liter (ug/1) MTBE concentrations have generally stayed constant since the previous sampling event 4.0 SUMMARY AND CONCLUSIONS ' o Based on the September 25, 1997 groundwater data, a groundwater flow direction beneath the site could not be inferred Previous quarter monitoring shows the flow ' direction to be to the east with a hydraulic gradient of 0 001 meter per meter (0 001 foot per foot) o Groundwater elevations have risen an average of 0 66 meters (2 2 feet) from the previous average elevations measured for the fourth quarter 1996 monitoring event o TPH-D was not detected in all of the monitoring wells, while TPH-G was detected in four of the monitoring wells at concentrations similar to previous sampling events ' o BTEX concentrations were detected in twelve of the fourteen groundwater monitoring wells ' 0 MTBE was detected in seven of the fourteen groundwater monitoring wells ' 0 Seven monitoring wells at the site have benzene concentrations above the State of California Primary Drinking Water Standards (PDWS) for benzene ' 4 0 RECOMMENDATIONS ' As benzene concentrations in seven monitoring wells were above PDWS in this quarters sampling event, PSI recommends that quarterly sampling continue at the site 4 F TransfeflReparlSCALTRANS%Ca1fy097%710171gm397 fin