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Geological Tecluucs Iftc Page 3 t Groundwater Monitoring Report Project No 640 2 February 5,2002 1.3 Laboratory Analyses ' The groundwater samples collected on November 7, 2001 were delivered to Sherwood Labs (Department of Health Services Certification No 1400), of Hilmar, California, for the analysis of BTEX by EPA method 602 ' • TPH -G by EPA method 5030/8015(M) Sherwood forwarded samples to Entech Analytical Labs Inc (Department of Health ' Services Certification No 2346), of Santa Clara, California, for analysis of • The oxygenated fuel compounds (MTBE, ETBE, DIPE, TAME & TBA) by EPA method 8260 The detection limits for the above analyses are lasted in Table 2 of Appendix A, while the lab analytical results are presented in Appendix B 2.0 FINDINGS AND DISCUSSION The results of the groundwater sample analysis show the following • None of the three wells contained BTEX, TPH-G or gasoline oxygenate concentrations above the laboratory reporting limits This is the second time the wells have not contained detectable contaminants During field monitoring & well purging work, water quality parameters were measured, including Oxidation-Reduction Potential (ORP) This data is included in the field logs in Appendix C The ORP results are all positive This data supports the analytical data and shows that the groundwater in the vicinity of the wells is not significantly impacted by these hydrocarbons 3.0 CONCLUSIONS ' The groundwater in the area of the former gasoline UST does not appear to be significantly impacted In a letter from San Joaquin County, dated June 25, 2001, Mr Jeffrey Wong requested that three quarters of additional groundwater monitoring be performed in order to provide at least one complete annual groundwater monitoring cycle before closure can be considered This report documents the completion of the first of these three events When