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Ge0l09ical7'ech41cs lac Page 4 <br /> Groundwater Monitoring Report <br /> Project No 425 2 <br /> • May 12,2003 <br /> rThe sampling technician wore disposable gloves while collecting all samples <br /> A chain of custody document, listing all samples collected and their intended analyses, <br /> accompanied the samples from field to the laboratory, thereby providing a means to track <br /> the movement and insure the integrity of the samples t <br /> ' 13 Laboratory Analyses <br /> The groundwater samples collected on Match 21, 2003, were delivered to Sherwood Labs <br /> (Department of Health Services Certification No 1400), of Hilmar, California, for analysis <br /> The samples were analyzed using the following methods <br /> ® BTEX—EPA method 8020/8015(m) <br /> • TPH-Gasoline --EPA method 8020/8015(m) <br /> G MTBE— EPA method 8020/8015(m) <br /> The detection limits for the above analyses are listed in Table 4 of Appendix A and the <br /> laboratory data are presented in Appendix B <br /> As required under AB2886, the laboratory data were submitted electronically to GeoTrac ker <br /> on April 17, 2003 - confirmation number 4561712861 <br /> 1 <br /> 2.0 FINDINGS AND DISCUSSION <br /> rFhe laboratory analytical data generated during the March 21, 2003 groundwater-monitoring <br /> event indicate that gasoline constituents TPH-G & BTEX have been detected in monitoring <br /> ' wells MW-1, MW-2, MW-4 and MW-5 <br /> The iesults of the March 2003 event are comparable with the results from previous <br /> monitoring events The following observations are made <br /> • The horizontal groundwater gradient, calculated from the water table wells, is currently <br /> towards the east <br /> • The gradient calculated from the intermediate wells is to the northeast <br /> • Vertical groundwater gradients were positive or upward in the shallow/intermediate and <br /> intermediate/deep well pairs <br /> i TPH-G concentrations in MW-1 continue to fluctuate within levels usually observed for <br /> the site A historical trend of increasing TPH-G concentrations may indicate lateral <br /> spreading of the plume to the west See Figure 6 for a graph of Benzene and TPH-G <br /> ' versus time (MW-1) and Figure 8 for the distribution of TPH-G <br /> r <br />