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i i i C A M B R ' A Mr Jeffrey Wong • February 15, 2006 INVESTIGATION RESULTS Analytical Results in Soil TPHg was detected in soil samples from borings SB-12 and SB-13 at concentrations ranging from 1 1 to 1,800 ppm Benzene was"only detected in one soil sample (SB-13-7) at 0 010 ppm MTBE was detected in all soil borings except SB-14 at concentrations ranging from 0 0056 to 15 ppm TBA was detected in soil samples from borings SB-11, SB-12, and SB-13 at concentrations ranging from 0 016 to 2 0 ppm 1,2-DCA was detected in samples from boring SB-13 up to 0 018 ppm i i Soil samples from the well borings did not contain any detectable concentrations of chemicals of concern with the exception of one soil sample (MW-5-35), which contained 0 062 ppm MTBE and 0 038 ppm TBA Table 2 summarizes soil chemical analytical data, and Figure 2 presents TPHg, benzene, MTBE, and TBA concentrations The laboratory analytical report is included in Attachment E Analytical Results to Groundwater TPHg was detected in groundwater samples collected from wells MW-1 and MW-5 at concentrations of 190 and 85 ppb, respectively ' BTEX was not detected in any of the wells MTBE was detected in groundwater samples collected from wells MW-1, MW-5, and MW-6 at concentrations ranging from 13 to 1,700 ppb TBA was detected in wells MW-1 and MW-5 at concentrations of 3,700 and 12 ppb, respectively 1,2-DCA was detected in groundwater samples collected from wells MW-5 and MW-6 at concentrations of 63 and 7 6 ppb, respectively The groundwater chemical analytical data are summarized' in the well concentrations table in Blaine's report (Attachment C) Benzene and MTBE concentrations are shown on Figure 3, and the laboratory analytical report is included in Blaine's report(Attachment C) CONCLUSIONS AND RECOMMENDATIONS i II Shell advanced soil borings SB-11 through SB-16 to assess the lateral extent of petroleum hydrocarbons and MTBE in soil near the dispenser islands _Following over-excavation in the dispenser area up to 11,000 ppm TPHg, 10 ppm benzene, and,0 11 ppm MTBE were present to soil I TPHg was not detected in soil from borings SB-11, SB-14, SB-15, SB-16, MW-5, MW-6 or in soil samples D-4-5', S-5-12 0, S-6-12 0, and S-14-7 0, delineating TPHg in soil around the + dispensers in all directions except southwest of Dispenser 1 Soil samples collected from boring 7 1