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� I <br /> 16 indicated the lateral extent of gasoline hydrocarbons in soil to the north and south of soil <br /> boring TB-5 had been defined Elevated concentrations of TPHg and BTEX were detected in <br /> ' soil samples collected from boring SB-22 to a depth of approximately 15 feet bgs Low <br /> concentrations of gasoline hydrocarbons were detected in soil samples collected from boring <br /> SB-22 from a depth of 25 to 60 feet bgs LH further concluded that gasoline hydrocarbons <br /> ' detected beneath the northwest portion of the site were limited to the vicinity of TB-5, <br /> between depths of approximately 5 and 25 feet bgs (Leedshill Herkenhoff, Inc September <br /> 1990) <br /> i <br /> On August 24, 1992 Kennedy/Jenks Consultants (Kennedy/Jenks) collected four sidewall <br /> g samples from the former gasoline UST excavation, approximately 2 feet bgs near the center <br /> ' of the excavation sidewall face Concentrations of TPHg ranged from below laboratory <br /> detection limits to a maximum of 4 0 ppm, which is below the SJCPHS-EHD's established <br /> detection limit of 10 ppm Trace levels of toluene and total xylenes were detected in the <br /> sidewall samples Samples from the floor of the former UST excavation were <br /> not collected <br /> (Kennedy/Jenks, October 1992) <br /> Mill Creek AssociatesMill Creek)) performed an additional subsurface investigation in order <br /> to further evaluate the extent of petroleum hydrocarbons in soil and groundwater onsite and <br /> offsite Work included drilling one onsite and one offsite soil boring, and constructing <br /> o monitoring wells MW-7 and MW-8, respectively, in the borings Monitoring well MW-7 <br /> was installed to replace well MW-3 (which had gone dry), and monitoring well MW-8 was <br /> installed to evaluate the lateral extent of gasoline hydrocarbons in groundwater offsite, <br /> f 4 downgradient of onsite well MW-5 Gasoline hydrocarbons were not detected in soil <br /> samples collected from the soil borings Gasoline hydrocarbons were detected in <br /> groundwater samples collected from the newly installed monitoring wells as well as existing <br /> monitoring well MW-6 1,2 dichloroethane was detected insam les <br /> roundwater <br /> g p collected <br /> from monitoring wells MW-6 and MW-7 Tetrachloroethene was detected in groundwater <br /> samples collected from monitoring well MW-7 Diesel hydrocarbons were not detected in <br /> groundwater samples collected from wells MW-6 through MW-8 Groundwater was not <br /> present in monitoring wells MW-1 through MW-5 (Mill Creek, November 21, 1994) <br /> � Analytical results for soil and groundwater samples, and groundwater elevation data collected <br /> by previous consultants is summarized in the tables prepared by Mill Creek included in <br /> Appendix 2 <br /> 1.4 Work performed by Ground Zero in 1995 <br /> 1.41 Additional Investigation <br /> In April 1995, Ground Zero performed an additional investigation at the site to further I <br /> evaluate the extent of gasoline hydrocarbons in soil onsite, and the lateral extent of gasoline <br /> hydrocarbons in groundwater offsite Work performed included drilling a total of eleven <br /> onsite and offsite soil borings and constructing monitoring wells in the four offsite borings, <br /> groun&xtraeklc p 3 <br />