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Pombo Ranch Facility May 2006 <br /> Site Closure Report <br /> 1 <br /> . for a removal efficiency of approximately 97.47 per cent. Post excavation benzene <br /> ' contamination is shown in Figure 12. <br /> Toluene hot spots were located in the southeast portion of the excavation in the vicinity <br /> ' of boring B-3 and in the eastern portion of excavation in the vicinity of MW4 and boring <br /> B-11 as shown in Figure 13. North — south and east- west cross sections showing the <br /> extent of the toluene contamination are shown in Figure 14 and Figure 15. Approximately <br /> 1.20 pounds of toluene was removed by the remedial excavation. Residual toluene <br /> ' contamination was detected in the confirmation soil sample in the eastern sidewall. An <br /> estimated 0.016 pounds of residual toluene contamination is present in the eastern side of <br /> ' the excavation for a removal efficiency of approximately 99.68 per cent. Post excavation <br /> toluene contamination is shown in Figure 16. <br /> ' Ethyl benzene hot spots were located in the southeast portion of the excavation in the <br /> vicinity of boring B-3 and in the northeastern portion of excavation in the vicinity of <br /> MW4 and boring B-1 1 as shown in Figure 17. North— south and east- west cross sections <br /> ' showing the extent of the ethyl benzene contamination are shown in Figure 18 and Figure <br /> 19. Approximately 3.13 pounds of ethyl benzene was removed by the remedial <br /> excavation. Residual ethyl benzene contamination was detected in the confirmation soil <br /> ' sample in the eastern sidewall. An estimated 0.021 pounds of residual ethyl benzene <br /> contamination is present in the eastern side of the excavation for a removal efficiency of <br /> approximately 99.33 per cent. Post excavation ethyl benzene contamination is shown in <br /> Figure 20. <br /> Xylene hot spots were located in the southeast portion of the excavation in the vicinity of <br /> boring B-3 and in the northeastern portion of excavation in the vicinity of MW4 and <br /> boring B-11 as shown in Figure 21. North — south and cast- west cross sections showing <br /> the extent of the xylene contamination are shown in Figure 22 and Figure 23. <br /> ' Approximately 4.13 pounds of xylene was removed by the remedial excavation. Residual <br /> xylene contamination was detected in the confirmation soil sample in the western and <br /> eastern sidewalls. An estimated 0.041 pounds of residual xylene contamination is present <br /> ' predominantly in the eastern side of the excavation for a removal efficiency of <br /> approximately 99.02 per cent. Post excavation xylene contamination is shown in Figure <br /> ' 24. <br /> Gasoline petroleum hydrocarbon hot spots were located in the southeast portion of the <br /> ' excavation in the vicinity of boring B-3 and in the northeastern portion of excavation in <br /> the vicinity of MW4 and boring B-11 as shown in Figure 25. North---south and east- west <br /> cross sections showing the extent of the xylene contamination are shown in Figure 26 and <br /> Figure 27. Approximately 211.56 pounds of gasoline was removed by the remedial <br /> excavation. Residual gasoline contamination was not detected in the confirmation soil <br /> samples in the excavation sidewalls. Post excavation gasoline contamination is shown in <br /> ' Figure 28. <br /> A MTBE hot spot was located in the southeast portion of the excavation in the vicinity of <br /> ' boring B-3 as shown in Figure 29. North — south and east- west cross sections showing <br /> 9 <br />