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TOTAL PETROLEUM HYDROCARBONS,GASOLINE RANGE(TPHG) <br /> FIGURE 5A <br /> Figure 5A represents the TPHg hydrocarbon groundwater plume in the A zone along with <br /> the plume beneath CCFF The Sanchez plume is elongated extending west of MW2 out <br /> to "Geoprobe" hole P9 were degradation has left only minor TPHg (470 ug/L), Toluene <br /> (0 65 ug/L) and tert-Butanol (11 ug/L), the degradation byproduct of MTBE Highest <br /> concentrations of TPHg are associated with the area that was over-excavated, MW 10 <br /> This area formerly contained temporary piezometers PZ1A and PZ2A (highest <br /> concentration of hydrocarbons 140,000 ug/L and 62,000 ug/L TPHg respectively on <br /> January 31, 2003) The MW10 area has since reduced to 4,300 ug/L Newly installed <br /> downgradient well MW9A is below laboratory lower detection limits <br /> The CCFF TPHg plume is associated with well MW 1 and seems to be confined to the <br /> north pump island area and areas to the west northwest <br /> FIGURE 5B <br /> Figure 513 represents the hydrocarbon groundwater plume in the B zone and shows a <br /> similar elongated plume extending west from MW2 out to "Geoprobe" hole P9 where <br /> . degradation has left only minor amounts of Toluene (0 81 ug/L), Xylenes (0 83 ug/L) <br /> and MTBE (1 6 ug/L) Again the highest concentrations are associated with the area that <br /> was over-excavated contained temporary piezometers PZ113 and PZ213 with 40,000 ug/L <br /> and 16,000 ug/L TPHg respectively on January 31, 2003 Newly installed excavation <br /> monitor well MW10 contains 4,300 ug/L <br /> BENZENE <br /> FIGURE 6A <br /> Figure 6A represents the benzene groundwater plume in the A zone No benzene was <br /> detected in the wells associated with CCFF The Sanchez plume is elongated extending <br /> west of MW2 out to "Geoprobe" hole P9 were degradation has left only minor TPHg <br /> (470 ug/L), Toluene (0 65 ug/L) and tert-Butanol (11 ug/L), the degradation byproduct of <br /> MTBE Highest concentration of Benzene is associated with the area that was over- <br /> excavated, MW 10 This area formerly contained temporary piezometers PZ1 A and <br /> PZ2A (highest concentration of benzene 14,000 ug/L and 4,100 ug/L benzene <br /> respectively on January 31, 2003) The MW 10 area has since reduced to 520 ug/L and <br /> down gradient well 6A currently contains 570 ug/L Newly installed downgradient well <br /> MW9A is below laboratory lower detection limits <br /> 9 Sanchez QM 3rd 2005 <br />