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The laboratory is currently preparing electronic data files for submittal to Geotracker Geocon will • upload the data and provide Caltrans with a Geotracker confirmation number as soon as the process is complete Groundwater Analytical Results TPHg was detected in samples collected from wells MW-14, VM-1 and VM-2 at concentrations of 2,900, 1,100 and 3,400 µg11, respectively TPHd was detected in the groundwater samples collected from wells MW-12, MW-14, VM-1 and VM-2 at concentrations of 60, 660, 440 and 2,400 µg/l, respectively Benzene was detected in the groundwater samples collected from wells MW-14, VM-1 and VM-2 at concentrations of 1,400, 270 and 1,200 pg/l, respectively Toluene, etbylbenzene and total xylenes were also detected in wells MW-14, VM-1 and VM-2 at concentrations ranging from 2 1 µg/1 (VM-1 - toluene) to 160 pg/1 (MW-14 - ethylbenzene and VM-2 - total xylenes) FOCs were not detected above their respective laboratory method detection limits in each of the groundwater samples TPHg, TPHd and benzene concentrations for the Third Quarter - 2003 monitoring event are depicted on Figure 3, Petroleum Hydrocarbons in Groundwater- September 2003 CONCLUSIONS AND RECOMMENDATIONS The highest concentrations of dissolved phase petroleum hydrocarbons appear to be limited to the immediate vicinity of the former UST excavation area (monitoring wells MW-14, VM-1 and VM-2) Geocon recommends that the Central Valley Regional Water Quality Control Board (CVRWQCB) consider the Site for possible low risk closure and regulatory "no further action" status Pending evaluation by the CVRWQCB, the next quarterly monitoring event is scheduled for December 2003 If there are any questions concerning the contents of this report, or if Geocon may be of further service, please contact the undersigned at your convenience Sincerely, GEOCON CONSULTANTS,I QQIA� /Q C * (46681 * Rebecca L Silva,REA Pro anager EJ4X WWI" Project Scientist RLS JEJ krc OFCAL�� (5) Addressee Attachments Figure 1, Vicinity Map Figure 2, Groundwater Elevation Map - September 2003 Figure 3, Petroleum Hydrocarbons in Groundwater- September 2003 Table 1, Summary of Groundwater Elevation and Analytical Data Appendix A, Summary of Historical Groundwater Analytical Data Appendix B, Monitoring Well Sampling Data Sheets Appendix C, Laboratory Reports and Chain of Custody Records Project No 58475-06-24H -3- October 23,2003