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cicologkcal mala"fac Page 4 <br /> 2"4 Quarter 2004 Groundwater Monitoring Report <br /> Project No 507 2 <br /> August 30,2004 <br /> Groundwater monitoring field logs are included in Appendix C <br /> ' 1.3 Laboratory Analyses <br /> The groundwater samples collected on June 4, 2004, were delivered to Sherwood Labs <br /> ' Corporation, Department of Health Services Certification No 1400, of Hilmar, California, <br /> for analysis <br /> Sherwood Labs analyzed the groundwater samples for <br /> • Benzene, Toluene, Ethyl Benzene, and Xylene (BTEX)by EPA method 8020 <br /> • Total Petroleum Hydrocarbons as Gasoline (TPH-G)by EPA method 5030/8015 <br /> • MTBE by EPA Method 8020 <br /> The results and detection limits for the above analyses are listed in Table 3 of Appendix A <br /> while the lab analytical results are presented in Appendix B <br />' As required under AB2886, the laboratory and groundwater elevation data were submitted <br /> electronically to GeoTracker on June 18 and August 19, 2004 - confirmation numbers <br /> 2524654507 & 5473560929 <br /> 2.0 FINDINGS AND DISCUSSION <br /> The results of the groundwater sample analyses indicate the following <br /> ® Wells MW-1,MW-2 and MW-3 remain free of detectable contamination <br />' i MW-4, MW-5 and MW-9 have significant BTEX and TPH-G contamination <br /> • MW-6 and MW-8 have minor TPH-G and/or BTEX contamination <br /> • Water table well MW-7 did not contain BTEX or TPH-G concentrations above the <br /> laboratory reporting limits but did contain 4 9 µg/1 MTBE The well has intermittently <br /> contained MTBE since its installation in May 2001 The source of this contamination <br />' may be surface infiltration from unpaved areas and from the open storm water drainage <br /> ditch traversing the front of the parcel <br /> • Water table well MW-10 did not contain contaminant concentrations above the laboratory <br />' reporting limits since February 2002 The well has previously contained xylene at levels <br /> Just above the laboratory reporting limit of 0 3 [tg/l <br />' • Deep well MW-109 did not contain contaminants above the laboratory reporting limits <br /> for the fifth consecutive event The reduction in contaminant concentrations from the <br /> first sampling event on June 1, 2001 is noted and sufficient monitoring has been <br />' performed to conclude that it was probably a drilling artifact or the bottom of the <br /> groundwater plume <br /> 1 <br />