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1 <br /> Geofogwaf?eckntcs Inc Page 3 <br /> Groundwater Monitoring Report <br /> Project No 662 2 <br /> December 22, 2000 <br /> ' 1.3 Laboratm y Analyses <br /> ' The groundwater samples collected on November 10, 2000 were delivered to Sherwood <br /> Labs (Department of Health Services Certification No 1400), of Hilmar, California, for <br /> analysis <br /> ' Sherwood analyzed the three monitoring well groundwater samples for <br /> ' • Benzene, Toluene, Ethyl Benzene, and Xylene (BTEX) by EPA method 602 <br /> • Total Petroleum Hydrocarbons as Gasoline (TPH-G)by EPA method 5030/8015(M) <br /> Additional samples were sent to California Laboratory Services from Sherwood Labs for the <br /> analysis of <br /> • MTBE, DIPE, ETBE, TAME and TBA by EPA method 8260 <br /> ' • Methanol and Ethanol by GC-FID <br /> ' The detection limits for the above analyses are listed in Table 2 of Appendix A while the lab <br /> analytical results are presented in Appendix B <br /> 2.0 FINDINGS AND DISCUSSION <br /> ' The results of the groundwater sample analysis show the following <br /> • The laboratory results indicate that several OFCs have impacted the groundwater in the <br /> vicinity of wells MW-I and MW-3 MTBE has the highest concentration while TAME <br /> & TBA have low concentrations <br /> • MW-2, which is upgradient of the former USTs, remained free of detectable <br /> contamination for the fourth consecutive event <br /> Neither BTEX nor TPH-G was present in any of the groundwater samples above the <br /> laboratory reporting limits <br /> ' The lateral extent of the contamination is only defined upgradient to the northwest by MW- <br /> 2 The vertical extent has not been defined <br /> ' GTI makes the following recommendations <br /> • Perform additional soil and groundwater investigation by installing borings and <br /> ' monitoring wells to define the lateral and vertical extent of the plume and to evaluate <br /> the mass of contaminants present <br />