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Cwbecca[Technics/nc Page 4 <br /> Groundwater Monitormg Report ' <br /> Project No 425 2 <br /> July 26,2002 <br /> 13 Laboratory Analyses <br /> The groundwater samples collected on June 5, 2002, 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 /> • EPA method 8020/8015 —BTEX, MTBE <br /> • EPA method 5030/8015(m) - TPH-Gasoline <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 GeoTracker <br /> on July 29, 2002 - confirmation number 3852575957 <br /> 2.0 FINDINGS AND DISCUSSION <br /> The laboratory analytical data generated during the event indicate that gasoline constituents <br /> TPH-G & BTEX have been detected in monitoring wells MW-1, MW-2, MW-4 and MW-5 <br /> ' The results of the June 5, 2002, event are comparable with the results from previous <br /> monitoring events The following observations are made <br /> ' a The horizontal groundwater gradient is currently towards the northeast - <br /> • Vertical groundwater gradients were positive or upward in the shallow/intermediate and <br /> intermediate/deep well pairs <br /> • Groundwater levels have previously exhibited a trend of decreasing elevation This <br /> situation may have stabilized or reversed as of this monitoring event <br /> ' • TPH-G and benzene concentrations in MW-1 exhibited a sharp increase to the highest <br /> levels recorded during the February 2002 event The concentrations dropped <br /> significantly during the June event See Figure 6 for a graph of Benzene and TPH-G <br /> versus time and Figure 8 for the distribution of TPH-G <br /> • BTEX & TPH-G concentrations in MW-2 continue to decrease since the impacted soils <br /> in the vicinity of the former USTs were excavated in July 2001 See Figure 7 for graph <br /> of Benzene and TPH-G versus time and Figure 8 for the distribution of TPH-G <br /> • Contaminant concentrations in wells MW-4 and MW-5 fluctuate seasonally but exhibit <br /> ' an overall stable trend <br /> o For the seventh consecutive event, wells MW-102 and MW-202 did not Contain <br /> contaminant concentrations above the laboratory reporting limits <br /> �'�f�r� �f�ry1 yLwE i A)lei,, c41c["&tj-43(e ye'o /r <br /> alt �•�L� d¢� C!/KCL�s{72�Ttnj Irt 1402 <br /> l LC1v6G P� Hv�7/c.�f �YIG1120?/ f� 'ekZCX1k4C0d -Nv /1", fO4lS <br />