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4 0 SUMMARY AND CONCLUSIONS <br /> • Based on the September 28, 1998 groundwater data the groundwater flow direction is <br /> to the east with a hydraulic gradient of 0 00076 meter per meter (0 00076 foot per <br /> foot) <br /> • Groundwater elevations have declined approximately 0 57 meters 1 9 feet from the <br /> previous average elevations measured in the Second Quarter 1998 monitoring event <br /> o TPH-D concentrations were t n detected ected in any of the groundwater samples collected <br /> this sampling event <br /> o TPH-G concentrations were detected in 3 of the 14 groundwater samples (MW-6, VW- <br /> 1, and VW-2) Detectable concentrations ranged from 500 to 8,400 pg/l <br /> • Benzene concentrations were detected in 6 of the 14 groundwater monitoring wells <br /> (MW-2, MW-3, MW-6, MW-8, VW-1, and VW-2) Detectable concentrations ranged <br /> from 0 8 to 1,800 pg/I <br /> o MTBE concentrations were detected in 4 of the 14 groundwater samples (MW-2, MW- <br /> 6, VW-1, and VW-2) Detectable concentrations ranged from 0 8 to 75 pg/l A <br /> confirmation analysis of the sample from VW-2 (75 pgll) by EPA Method 8260 <br /> resulted in a lower reported concentration (37 4 pg/1) <br /> o Four monitoring wells at the site have benzene concentrations above the State of <br /> California Primary Drinking Water Standards (PDWS) for benzene <br /> 5 0 RECOMMENDATIONS <br /> As benzene concentrations in four monitoring wells were above PDWS in this sampling <br /> event, PSI recommends that quarterly sampling continue at the site <br /> 4 <br /> F TransfeAReport\CALTRANSICalty097571017�STOCKTCNlgm39alri <br />