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Chemical analysis <br /> • <br /> The groundwater samples collected were analyzed for Total Petroleum <br /> Hydrocarbons as Gasoline (TPHG) and Benzene, Toluene, Ethylbenzene <br /> and Xylene (BTEX) . The groundwater samples were analyzed for TPHG <br /> by EPA Method 8015 modified with purge and trap preparation 5030 <br /> (GC/FID) with detection limits of 50ug/1. EPA Method 602 will be <br /> utilized for BTEX with a detection limit of 0. 5ug/1 as required by <br /> the SJCEHD. <br /> The results of the analysis of the groundwater samples in parts per <br /> billion (ppb) are shown .in Table 3 . The laboratory data sheets <br /> with detection limits and COC documentation are contained in <br /> Appendix B. <br /> TABLE 3 <br /> Groundwater Sample Analysis Results in ppb. <br /> Sample ID TPHG B T E X <br /> MW-1 3 , 400 25 3 . 0 110 120 <br /> MW-2 3 , 200 1000 9. 6 90 24 <br /> �Mw3 5, 700 83 6. 5 130 120 <br /> ND = Not Detected <br /> The concentrations of TPHG and BTEX in the groundwater are high. <br /> Quarterly sampling should be continued for at least two more <br /> quarters, to determine the water quality and gradient status over <br /> a year period. <br /> SUMMARY, CONCLUSIONS AND RECOMMENDATIONS <br /> The groundwater samples from the three wells had actionable levels <br /> of TPHG and Benzene. <br /> The calculated gradient is to the north west at approximately 0. 01 <br /> ft/ft. The slope of this gradient is suspiciously large for the <br /> geology of this region. There maybe unusual conditions which are <br /> impacting the gradient both -in direction and slope. The irrigation <br /> ditches to the east of the property, recent irrigation of the <br /> property, slow recharge of the wells and the high water table maybe <br /> some of the reasons for suspecting the gradient values. <br /> The levels of TPHG and BTEX in groundwater are similar to the <br /> 6 <br />