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Geologuot recknccs/xc Page 3 <br /> Groundwater Monitoring Report <br /> Project No 662 2 <br /> March 27,2002 <br /> ' 1.3 Laboratory Analyses <br /> ' The groundwater samples collected on January 8, 2002, were delivered to Sherwood Labs <br /> (Department of Health Services Certification No 1400) of Hilmar, California, for analysis <br /> The groundwater samples were analyzed for <br /> • Benzene, Toluene, Ethyl Benzene, and Xylene (BTEX)by method EPA method 602 <br /> ' . Total Petroleum Hydrocarbons as Gasoline (TPH-G)by EPA method 5030/8015(M) <br /> Sherwood forwarded samples to Entech Analytical Labs Inc (Department of Health <br /> Services Certification No 2346) of Santa Clara, California, for analysis of <br /> • Oxygenated Fuel Compounds (MTBE, DIPE, ETBE, TAME & TBA) by EPA method <br /> 8260 <br /> The detection limits for the above analyses are listed in Table 2 of Appendix A while the lab <br /> Y P <br /> ' analytical results are presented in Appendix B <br /> As required under AB2886, the laboratory data was submitted electronically to GeoTracker <br /> on March 1, 2002 (confirmation # 6289347827) <br /> ' 2.0 FINDINGS AND DISCUSSION <br /> The results of the groundwater sample analysis show the following <br /> ' • Well MW-I contained the gasoline oxygenate MTBE at 1500 pg/l <br /> • Well MW-3 contained the gasoline oxygenates MTBE and TBA at 4100 and 540 µg/l, <br /> respectively <br /> ' • Figure 4 MTBE vs Elev MW-3 suggests the concentration of MTBE in groundwater is <br /> related to the elevation of groundwater in well MW-3 <br /> ' • MW-2, which is upgradient of the former USTs, has not contained contaminant <br /> concentrations above the laboratory detection limits for all nine quarterly events <br /> completed thus far in the investigation <br /> • Neither BTEX nor TPH-G was present in any of the groundwater samples above the <br /> laboratory reporting limits <br /> • Oxidation-Reduction Potential measurements (Table 3) show that the values for all three <br /> ' wells are positive, suggesting that there is a limited amount of biodegradation of the <br /> contaminant plume occur-ring This is to be expected, since the primary contaminant is <br /> ' MTBE, which is very resistant to biodegradation <br /> The lateral extent of the groundwater contamination plume is only defined upgradient to the <br /> northwest by MW-2 The vertical extent has not been defined <br />