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1' <br /> Ljeofoguaf?echnus Inc Page 4 <br /> Groundwater Monitoiing Report <br /> Pioject No 724 2 <br /> April 11,2001 <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 />' their movement and ensure their integrity <br /> 1.3 Laboratory Analyses <br /> The groundwater samples collected on March 15, 2001, were delivered to Sherwood Labs <br /> of Hilmar, California (certification #1400) for analysis of <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 />' Sherwood also sent the samples to California Laboratory Services (certification #1233) for <br /> the analysis of <br />' 9 MTBE, RIPE, ETBE, TAME, TBA, 1,2- DCA, EDB by EPA Method 8260 <br /> • Metanol, Ethanol by GC-FID <br />' The detection limits for the above analyses are listed in Table 4 of Appendix A, while the <br /> lab analytical results are presented in Appendix B <br /> 20 FINDINGS AND DISCUSSION <br /> The results of the groundwater sample analysis show the following <br /> • Wells MW-1, MW-5, MW-6, MW-7 and MW-104 did not contain contaminant <br />' concentrations above the laboratory reporting limits <br /> + Wells MW-2 and MW-4 have low to moderate benzene contamination and trace to low <br /> concentrations of the other BTEX analytes <br /> s Wells MW-2, MW-3 and MW-4 contain low concentrations of TPH-G <br /> Intermediate wells MW-106 and MW-107 contained low BTEX concentrations and low <br /> to moderate TPH-G <br /> • Deep well MW-104 did not contain contaminant concentrations above the laboratory <br /> reporting limits for the second consecutive event <br /> • Gasoline oxygenate MTBE was detected in well MW-2, MW-106 and MW-107 at 8 4, <br /> 16 and 77 ug/l, respectively <br /> 1 The shallow groundwater plume is evident in well MW-4 and defined laterally to the east <br /> (down gradient) by MW-5 and MW-6 The presence of contamination in wells MW-106 <br /> and MW-107 suggests that a submerged plume is being sourced by residual soil <br />' contamination beneath the present water table It is noted that the screened intervals of <br /> these wells (55-60 feet bgs) are placed near the elevation of the groundwater table in 1992 — <br /> approximately 54 feet bgs <br />