Laserfiche WebLink
BENZENE <br /> FIGURE 6A <br /> Figure 6A represents the benzene groundwater plume in the A zone No benzene was <br /> detected iri the wells associated with CCFF The Sanchez plume is elongated extending <br /> west of MW2 out towards "Geoprobe" hole P9 where degradation has left only minor <br /> TPHg (470 ug/L), Toluene (0 65 ug/L) and tert-Butanol (I 1 ug/L), the degradation <br /> bypioduct of MTBE the highest concentration of Benzene is associated with the area <br /> that was over-excavated, MWIO This area formerly contained temporary piezometers <br /> PZ I A and MA (highest concentration of benzene 14,000 ug/L and 4,100 ug/L benzene <br /> respectively on January 31, 2003) The MW1O area has since reduced to 290 ug/L The <br /> down gradient well 6A currently contains 270 ug/L and cross gradient well MW8A <br /> contains 120 ug/L Newly installed downgradient well MW9A is below laboratory lower <br /> detection limits <br /> FIGURE 6B <br /> Figure 6B represents the benzene groundwater plume in the B zone The Sanchez plume <br /> is elongated extending west of MW2 out towards "Geoprobe" hole P9 Again the highest <br /> concentrations are associated with the area that was over-excavated and contained <br /> temporary piezometers PZIB and PZ2B with 1,800 ug/L and 32 ug/L Benzene <br /> respectively on January 31, 2003 Newly installed excavation monitor well MW1O <br /> contains 290 ug/L, downgradient well MW6B contains 4 4 ug/L and cross gradient well <br /> MW8B contains 5 9 ug/L Newly installed downgradient well MW9B is below <br /> laboratory lower detection limits <br /> MTBE <br /> FIGURE 7A <br /> Figure 7A represents the MtBE groundwater in the A zone along with the plume beneath <br /> CCFF The Sanchez plume is elongated extending west of the over-excavated area <br /> (MW I O) out to "Geoprobe" hole P9 were degradation has left only minor TPHg (470 <br /> ug/L), Toluene (0 65 ug/L) and tert-Butanol (I l ug/L), the degradation byproduct of <br /> MTBE Highest concentrations of MtBE are associated with the areas north and west of <br /> CCFF well MW 1 which currently contains 440 ug/L The excavated area (MW 10) <br /> formerly contained temporary piezometers PZIA and PZ2A (highest concentration of <br /> MtBE 420 ug/L and 72 ug/L respectively on January 31, 2003) The MW 1 O area has <br /> since reduced to 6 8 ug/L Newly installed downgradient well MW9A is below <br /> laboratory Iower detection limits <br /> The CCFF MtBE plume is associated with well MWI and shows a connection to the <br /> • Sanchez plume The natural downgradient groundwater movement along with pumping <br /> 10 Sanchez QM 4th 2005 <br />