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B ZONE <br /> --- Monitor wells-MW2,-MW3,—MW4,—MW5-penetrate boththe A and B zones Figure 4B— <br /> show the gradient determination for the B Zone The B zone gradient and flow direction <br /> shows a ridge developed from Country Club Food & Fuel wells MW3 and MW4 to <br /> Sanchez well MW6B The current groundwater gradient shows a flow direction to the <br /> northwest at a gradient of 0 0015 ft/linear ft (Country Club Food and Fuel MW3 to <br /> Sanchez MW613) <br /> RESULTS OF CERTIFIED ANALYSES OF GROUNDWATER SAMPLES <br /> MONITOR WELLS <br /> Monitor ,vells MW2, MW3, MW4, and MW5 penetrated both the A and B zones <br /> Contaminants found to these wells would mix with the groundwater of both zones <br /> Figure 5A represents the hydrocarbon groundwater plume in the A zone and shows an <br /> elongated plume extending west of MW2 out to "Geoprobe" hole P9 were degradation <br /> has left only minor TPHg(470 ug/L), Toluene (0 65 ug/L) and tert-Butanol (11 ug/L), the <br /> degradation byproduct of MTBE Highest concentrations of TPHg are associated with <br /> well M�V6A at 11000 ug/L The area that was over-excavated contained temporary <br /> piezometers PZ1A and PZ2A and contained the highest concentration of hydrocarbons <br /> with 140,000 ug/L and 62,000 ug/L TPHg respectively on January 31, 2003 <br /> Figure 5B represents the hydrocarbon groundwater plume to 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 monitor well <br /> MW6B, 1300 ug/L The area that was over-excavated contained temporary piezometers <br /> PZ1B and PZ2B with 40,000 ug/L and 16,000 ug/L TPHg respectively on January 31, <br /> 2003 <br /> Figure 6 illustrates the subsurface ltthology and the extent of the A and B zones <br /> groundwater plumes within the A and B zones Also shown to cross section is the extent <br /> of the over-excavation and residual soil contamination February 28, 2003 <br /> RECOMMENDATIONS <br /> 1) The workplan to install a 4 inch diameter monitor well within the excavated area, a <br /> northern extent cluster monitoring well (A and B zones), north of former well <br /> location MW1 and a down gradient cluster monitoring well (A and B zones) to <br /> document the lateral extent west of probe hole P9 has been approved, see Figure 3 <br /> 2) Western Geo-Engineers is currently obtaining bids from drilling contractors to install <br /> these wells <br /> 6 Sanchez QM 1 ST 2004 <br />