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1 <br />' 3 3 LABORATORY ANALYSIS AND RESULTS <br /> Fourteen groundwater samples were submitted for analyses to Pace Analytical of <br />' Petaluma, California, a State of California-certified hazardous waste analytical laboratory <br /> The samples were analyzed for the following <br />' o EPA 8015 modified - Total petroleum hydrocarbons as Gasoline (TPH-G), <br /> o EPA 8015 modified - Total Petroleum Hydrocarbons as Diesel (TPH-D), <br /> EPA 8020 — Benzene, Toluene, Ethylbenzene, Total Xylenes (BTEX), and Methyl Tert <br /> i Butyl Ether (MTBE), <br />■ o EPA 8260 —Volatile Organic Compounds (VOCs), <br /> 1 Additionally, Tertiary Butyl Alcohol (TBA), DAsopropyl Ether (DIPS), Ethyl Tertiary Butyl <br /> Ether (ETBE), and Tertiary Methyl Ether (TAME) were analyzed EPA Method 8260 <br /> 1 detected none of these compounds <br /> A summary of the laboratory results for groundwater samples is presented in Table 1 A <br /> copy of the laboratory reports and chain-of-custody records are presented in Appendix B <br /> The following are the results of the groundwater sampling <br /> o TPH-D concentrations were not detected in any of the groundwater samples collected <br /> this sampling event <br /> 1 o TPH-G concentrations were detected in 2 of the 14 groundwater samples (MW-6 and <br /> VW-2) Detectable concentrations ranged from 760 to 9,000 pg/l The concentrations <br /> are slightly higher, but consistent with the previous quarter's sampling event <br /> 0 BTEX concentrations were detected in 9 of the 14 groundwater monitoring wells (MW- <br /> 2 through MW-6, MW-8, MW-12, VW-1 and VW-2) Detectable concentrations of <br /> Ibenzene ranged from 0 4 to 1,400 pgll The concentrations have generally decreased <br /> since the previous quarters sampling event Charts presenting benzene concentration <br /> Iover time for wells MW-6 and VW-2 are included as Figures 3 and 4 <br /> o MTBE concentrations were not detected in any of the groudwater samples collected <br /> 1 during this sampling event <br /> 4 0 SUMMARY AND CONCLUSIONS <br /> G Based on the June 17, 1998 groundwater data the groundwater flow direction 1s to the <br /> east with a hydraulic gradient of 0 001 meter per meter (0 001 foot per foot) <br /> 0 Groundwater elevations have risen approximately 1 17 meters (3 82 feet) from the <br /> previous average elevations measured for the First Quarter 1998 monitoring event <br /> IF TransferlRepart\CALTRANS4Gaity097%710175STOCKTON5gm298fin 3 <br />