ARCHIVED REPORTS XR0000244 - Laserfiche WebLink

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0 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-10, VW-1, VW-2, MW- 11, and MW-12) Detectable concentrations of benzene ranged from 0 59 to 1,300 ' ugll The concentrations have typically decreased since the previous quarters sampling event G MTBE concentrations were detected in one of the fourteen monitoring wells sampled (MW-6 at 7 4 ug/1 MTBE concentrations are slightly lower than measured in the previous sampling event 4 0 SUMMARY AND CONCLUSIONS ' Q Based on the December 29, 1997 groundwater data, a groundwater flow direction beneath the site could not be determined 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) ' C Groundwater elevations have declined approximately 0 15 meters (0 5 feet) from the previous average elevations measured for the third quarter 1997 monitoring event Q TPH-D concentrations were detected in five of the fourteen groundwater samples, while TPH-G was detected in seven of the monitoring wells at concentrations similar to previous sampling events C BTEX concentrations were detected in twelve of the fourteen groundwater monitoring wells The concentrations have generally declined since the previous quarters sampling event (Figures 3 and 4) ' o MTBE was detected in one of the fourteen groundwater monitoring wells o Six monitoring wells at the site have benzene concentrations above the State of ' California Primary Drinking Water Standards (PDWS) for benzene ' 5 0 RECOMMENDATIONS ' As benzene concentrations in six monitoring wells were above PDWS in this quarters sampling event, PSI recommends that quarterly sampling continue at the site 4 F TransfeftRepontCALTRANS%Calty097171017%gm497tin