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01 February 2006 . AGE-NC Project No 99-0657 ' Page 4of5 ' the previous monitoring events • The highest concentrations of dissolved hydrocarbons generally occurred In monitoring wells MW-1 and MW-4, which are located at or down-gradient of the UST area Concentration maps depicting the approximate distribution of dissolved TPH-g,benzene, MTBE, and 1,2- DCA are Illustrated on Figures 4 through 7, respectively ' Concentrations of dissolved TPH-g Increased this quarter In monitoring wells MW-1 and MW-2, TPH-g decreased below laboratory detection limits In wells MW-5 and MW-6 Concentrations of benzene Increased in wells MW-1, MW-2, and MW-4, and decreased to ' non detect In samples from well MW-5 since the previous monitoring event • MTBE concentrations Increased in wells MW-1, MW-2, and MW-4, and decreased to non ' detect In well MW-3 1,2-DCA concentrations Increased in wells MW-1,MW-2,and MW-4, and decreased in well MW-6 • No target analytes were detected at or above laboratory reporting limits In the ground water ' samples analyzed from annually-sampled wells MW-7 and MW-8 or deep Interval wells MW-10 and MW-11 ' The lateral extent of petroleum hydrocarbon contamination in ground water has been defined to the current west by well MW-5,east,south and north(CPT-1)of the UST area The lateral extent is not fully defined to the southwest of the UST area beyond well MW-6 (Figures 4 ' through 7) • The vertical extent of petroleum hydrocarbon-Impacted ground water is defined off-site In the area of soil boring CPT-1 The vertical extent ofpetroleum hydrocarbon-Impacted ground water is defined on-site by wells MW-10 and MW-11 ' 5.4. RECOMMENDATIONS ' Based on the findings of this Investigation, AGE recommends • Continuation of the quarterly ground water monitoring program, as required by the EHD ' Preparation of a remediation feasibility report for soil and ground water I I ' Advanced CeoEnvironmental,Inc