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I07 September 2005 AGE-NC Project No 97-0249 Page 7 of 8 Hydrologic Units 1 and 2 are depicted on Figures 10 and 11, respectively • Low concentrations of TBA and 1,2-DCA have been detected from wells MWA, MW-2, MW-3, MW-5, MW-6, MW-8A, MW-l0A and MW-11A, suggesting that only a minor TBA-impact and 1,2-DCA-impact to ground water in Hydrologic Unit 1 is present at the site • The lateral and vertical extent of the dissolved petroleum hydrocarbon plume is not known toward the northeast of Three B's Truck Plaza well MW-2, toward the south of Three B's Truck Plaza well MW-6 and toward the south of Flag City Chevron wells MW-16/17/18 (Figures 8 through 11) I 5.0. RECOMMENDATIONS Based upon the results of the first quarter 2005 investigation, AGE recommends • Continued quarterly ground water monitoring of wells MW-1 through MW-12, the next quarterly ground water monitoring event is tentatively scheduled for 28, 29 and 30 March I • 2005, • Continue to conduct future ground water monitoring events concurrently with the Flag City Chevron site (6421 Capitol Avenue), • Additional multi-level ground water monitoring wells MW-13, MW-14 and MW-15 were installed at the site during July 2005, a report of findings is forthcoming and, I • The higher concentrations off-site at Flag City Chevron well MW-19 represent an additional release and source of dissolved MTBE program should be implemented at the site as soon as possible An interim groundwater remediationp g p to establish hydraulic controls,inhibit potential off-site migration of the contaminated ground water plume,and to protect the on-site domestic water from the on-site ground water plume Additionally • the high concentrations of contaminants(i e BTEX and MTBE and 1,2-DCA)encountered at the site that are significantly above the DHS's MCLS • the high mobility of the above contaminants dissolved in the First Water Zone(30 to 50 feet) and Second Water Zone (70 to 85 feet) • the apparent southeastward dispersion (downgradient) of the Three B's Truck Plaza dissolved hydrocarbon plume towards the Flag City Chevron dissolved plume Advanced GcoEnvironmentai,Inc