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ANALYTICAL METHODS AND RESUL'T'S Laboratory Analyses ' Groundwater samples were delivered to Creek Environmental Laboratories, Inc , a Caltrans-approved and California-certified analytical laboratory, for the analyses of TPHg and TPHd following EPA Test Method 8015, BTEX following EPA Test Method 8020 and fuel oxygenate compounds (FOCS) ' including MTBE, tert-amyl methyl ether (TAME), ethyl tert-butyl ether (ETBE), di-isopropyl ether (DIPE) and tert-butanol (TBA) following EPA Test Method 8260 Groundwater analytical results are summarized on Table 1 Laboratory reports and chain-of-custody documentation are presented in ' Appendix C Groundwater Analytical Results ' TPHg was detected in samples collected from wells MW-1, MW-2, MW-6, MW-11, VW-1 and VW- 2 at concentrations ranging from 72 to 13,000 µg/1 TPHd was detected in the groundwater samples ' collected from wells MW-2, MW-3 and VW-2 at concentrations of 3,400, 1,800 and 2,400 µg/l, respectively Benzene was detected in groundwater samples collected from wells MW-1 through MW-5, MW-10, MW-11, MW-12 and VW-2 at concentrations ranging from 0 7 to 2,200 }Lg/l Toluene, ethylbenzene and total xylenes were also detected in the samples collected from wells MW- 1, MW-2, MW-4, MW-5, MW-10, MW-11, MW-12 and VW-2 at concentrations ranging from 0 7 (MW-5 - toluene and MW-12 - ethylbenzene) to 3,200 (MW-2 - total xylenes) µg/1 MTBE was detected in one sample, VW-2, at 30 µg/1 TAME, DIPE, TBA and ETBE were not detected above ' their respective laboratory method detection limits in each of the groundwater samples collected TPHg, TPHd, benzene, and MTBE concentrations for the Fourth Quarter- 2002 monitoring event are depicted on Figure 3, Petroleum Hydrocarbons in Groundwater-December 2002 CONCLUSIONS AND RECOMMENDATIONS ' Geocon recommends that quarterly groundwater monitoring continue at the Site to evaluate seasonal trends in groundwater elevation and contaminant concentrations in the vicinity of the former UST locations at the Site The next groundwater monitoring event is scheduled for March 2003 i I Project No S8475-06-24C -3- January 23,2003