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clealogu'al Tec/uucs/a Page 6 Groundwater Monitoring Report Project No 724 2 March 29,2005 • Figure 6 illustrates the distribution of TPH-G in the intermediate wells A localized high is centered in well MW-106 and the concentrations attenuate to the locations of ' MW--107 &MW-108 • Figure 7 illustrates the distribution of TPH-G in the deep wells A localized lugh is centered in well MW-208 and the concentrations attenuate to non-detectable levels in ' the southwest and south locations of MW-202, MW-209 &MW-210 2 MTBE • Figure 8 illustrates the distribution of MTBE in the intermediate wells A localized ' high of 23 l.gh is present in well MW-106 that attenuates west to the location of MW- 107 ' • Figure 9 illustrates the distribution of MTBE in the deep wells A node of MTBE (8 8 [tg/1) is present in well MW-209 that attenuates to the northwest to the location of MW-208 3 Benzene • Figure 10 illustrates the distribution of Benzene in the intermediate wells Trace concentration is present in well MW-2, MW-103, MW-106, and MW-107 ' • Figure 11 illustrates the distribution of Benzene in the deep wells A node of elevated Benzene concentration (9 9 µg/1) is present in well MW-208 that attenuates to non- detectable levels in the southeast, south and southwest locations of MW-209, MW- 2 10 W-210 & MW-202, respectively Oxidation/Reduction Potential (ORP) and dissolved oxygen (DO) measurements (Table 6) show that all of the sampled wells have a mixture of positive and negative ORP values and low DO readings The negative ORP values observed in the wells show that they are either within the core of the contamination plume or are in the reaction/depletion shadow down gradient of the plume Dissolved oxygen values generally corroborate with the ORP values measured in these wells and suggest that the plume is relatively stable ' As indicated in Figure 12 —MW-2 TPH-G vs GW Elevation, with the exception of June 20, 1997, contaminant concentrations have generally rmrmcked the pattern of groundwater elevation changes for the past 10 years in down gradient well MW-2 The well was non- detect for the second time in the investigation ' 3.0 CONCLUSIONS & RECOMMENDATIONS ' Based on our interpretation of the data collected over the course of this subsurface investigation, GTI has reached several conclusions These conclusions assume that the premise that the data we considered, although incomplete, are representative of actual site ' conditions We acknowledge that there may be undiscovered conditions, which would upon their consideration, change our interpretation and thus our conclusions