SITE INFORMATION AND CORRESPONDENCE_CASE 1

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Second Quarter 1997 Groundwater Monitoring Report Moore Petroleum, 14800 W.Frontage Rd,Manteca,CA September 11, 1997 Page 3 Groundwater Samnlina and Analvsis On May 29, 1997, Apex personnel collected groundwater samples from monitoring wells MW-6 f through MW-9, from the station's domestic well (DM-1), and the domestic well located at the trailer park south of the subject site (DM-2)- On June 14, 1997, Apex personnel collected groundwater samples from monitoring wells MW-I through MW-5. All samples were submitted, under chain-of-custody, to Sparger Technology, Inc. in Sacramento, California, a state-certified analytical laboratory. All samples were collected according to the Apex SOP included in Appendix A. Groundwater samples collected from MW-1 through MW-4 were analyzed for total petroleum hydrocarbons (TPH), as gasoline; benzene, toluene, ethylbenzene and total xylenes (BTEX) by EPA Method 802018015; TPH, as diesel, by EPA Method 8015 Modified; methyl-tert-butyl-ether (MTBE) by EPA Method 8020; and 1,2 Dichloroethane (DCE)by EPA Method 601. The groundwater sample collected from MW-5 was analyzed for TPH, as gasoline;BTEX by EPA Method 8020/8015; MTBE by EPA Method 8020; and 1,2 DCE by EPA Method 601. Groundwater samples collected from monitoring wells MW-6 through MW-9 were analyzed for TPH, as gasoline; BTEX by EPA Method 802018015; and MTBE by EPA Method 8020. Groundwater samples collected from the domestic wells (DM-1 and DM-2)were analyzed for TPH, as gasoline; BTEX by EPA Method 8020/8015; MTBE by EPA Method 8020; TPH, as diesel, by EPA Method 8015 Modified; and 1,2 DCE by EPA Method 601. The result of this sampling event is summarized in Table 2. The most recent Iaboratory analytical . reports and chain-of-custody forms are included in Appendix B. RECOM3UNDATIONS The analytical results of the groundwater samples collected on June 14, 1997 from MW-1 through MW-5 indicate that levels of TPH as gasoline;BTEX; TPH, as diesel; MTBE are below detection Emits (BDLs). Laboratory analysis identified 1,2 DCE above the California Department of Health Services, Drinking Water Standard Maximum Contaminant Level (MCL) of 0.5 ppb in MW-1 through MW-4; however, these Ievels are below the U.S. Environmental Protection Agencyos MCL of 5 ppb (1,2 DCE was not identified above'the laboratory detection limit in MW-5). With the exception of low concentrations of TPH; as gasoline(less than 60 ppb), xylenes (less than 2.8 ppb), and MTBE (less than 44 ppb), analytical results of the groundwater samples collected on May 29, 1997 from MW-6 through MW-9 indicate that previous contaminant levels are BDLs_ Laboratory analysis of the groundwater samples collected from DM-I and DM-2 identified low levels of TPH as gasoline(less than 63 ppb), xylenes (less than 3.5 ppb), and MTBE (less than 11 ppb). In addition, 1,2 DCE above the California Department of Health Services, Drinking Water Standard MCL of 0.5 ppb was identified in DM-2'(2.2 ppb); however, this level is below the U.S. Environmental Protection Agency's MCL of 5 ppb (1,2 DCE was not identified above the laboratory detection limit in DM-1). s•in�.rvn�o�ivon