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' GeoloquaCTechnws Inc Page 3 Groundwater Monitormg Report Project No 662 2 February 17,2000 ' 1.3 Laboratory Analyses ' The groundwater samples collected on January 20, 2000 were delivered to Sherwood Lab (Department of Health Services Certification No 1400), of Hilmar, California, for analysis 1 The three groundwater samples were analyzed by Sherwood for • Benzene, Toluene, Ethyl Benzene, and Xylene (BTEX) by EPA method 602 • Total Petroleum Hydrocarbons as Gasoline (TPH-G)by EPA method 5030/8015(M) ' Additional samples were sent to Kiff Analytical from Sherwood Labs for the analysis of p Yt Y ' • MTBE, DIPE, ETBE, TAME and TBA by EPA method 8260 • Methanol and Ethanol by EPA method 8260 The detection limits for the above analyses are listed 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 • The laboratory results show that several OFC compounds impact the groundwater around MW-1 and MW-3 The only OFC compound that was not detected was DIPE ' • MW-2 did not show the presence of any of these compounds • BTEX and TPH-G were not present in any of the groundwater samples ' During field monitoring I well purging work, water quality parameters were measured, including Oxidation-Reduction Potential (ORP) These data are included in the Monitoring ' Field Logs in Appendix C The ORP results are relatively high for an impacted site, however, the ORP values for MW-1 and MW-3 are lower then MW-2 which 1s not impacted ' The lateral extent of contamination is only defined to the northwest by MW-2 The vertical extent has not been defined ' GTI makes the following recommendations • Continue quarterly groundwater monitoring to determine if the results are reproducible ' • Perform a receptor survey to determine if there are any domestic or production wells within 2,000 feet of the site