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1 <br /> Geological red=s Inc Page 6 <br /> Groundwater Monitoring Report <br /> Project No 724 2 <br /> August 27, 2004 <br /> • Figure 7 illustrates the distribution of TPH-G in the deep wells A localized high is <br /> centered in well MW-208 and the concentrations attenuate to non-detectable levels in <br /> ' the southwest and south locations of MW-202, MW-209 & MW-210 <br /> 2 MTBE <br /> • Figure 8 illustrates the distribution of MTBE in the water table wells A node of <br /> ' MTBE (3 9 µg/1) is present in well MW-7 that attenuates to non-detectable levels in <br /> the northwest, northeast and east locations of MW-4, MW-5 &MW-6, respectively <br /> ' • Figure 9 illustrates the distribution of MTBE in the intermediate wells A localized <br /> high of 15 8 µg11 is present in well MW-106 that attenuates west to the location of <br /> MW-107 <br /> • Figure 10 illustrates the distribution of MTBE in the deep wells A node of MTBE <br /> (11 9 µg/1) is present in well MW-209 that attenuates to the northwest to the location <br /> of MW-208 <br /> ' 3 Benzene <br /> • None of the shallow monitoring wells contained Benzene above the laboratory <br /> reporting limits, and therefore a contour diagram was not produced <br /> ' • Figure 11 illustrates the distribution of Benzene in the intermediate wells Trace <br /> concentrations are present in wells MW-306 & MW-108 <br /> • Figure 12 illustrates the distribution of Benzene in the deep wells A node of elevated <br /> Benzene concentration (2 8 µg11) is present in well MW-202 that attenuates to the <br /> northeast, east and southeast locations of MW-208, MW-209 & MW-210, <br /> respectively <br /> ' Oxidation/Reduction Potential (ORP) and dissolved oxygen (DO) measurements (Table 6) <br /> show that all of the sampled wells have negative ORP values and low DO readings The <br /> ' negative ORP values observed in the wells show that they are either within the core of the <br /> contarmnation plume or are in the reaction/depletion shadow down gradient of the plume <br /> Dissolved oxygen values corroborate with the ORP values measured in these wells and <br /> suggest that the plume is relatively stable <br /> As indicated in Figure 13 —MW-2 TPH-G vs GW Elevation, with the exception of June 20, <br /> 1997, contaminant concentrations have generally minucked the pattern of groundwater <br /> elevation changes for the past 10 years in down gradient well MW-2 The well has returned <br /> to detectable levels of TPH-G after being in the non detect range for one monitoring event <br /> ' 3.0 CONCLUSIONS & RECOMMENDATIONS <br /> Based on our interpretation of the data collected over the course of this subsurface <br /> investigation, GTI has reached several conclusions These conclusions are based on the <br /> premise that the data we considered, although incomplete, are representative of actual site <br />