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' 25 January 2005 . AGE-NC Project No 97-0301 ' Page 5 of 6 ' ground water elevation is probably due to seasonal fluctuation • Generally, a steep downward vertical gradient was observed from wells MW-8,MW-9,and MW-12 and between the Second Water Zone, Third Water Zone, and Fourth Water Zone, ' near neutral vertical gradients were observed between the First Water Zone and the Second Water Zone in the southern portionof the site (Figure 3) l rj M-1 - , • Analysis of ground water samples collected from MW/and MW-7 suggest the dissolved V YY\ plume is compnsed of TPH-g, BTEX, and 1,2-DCA The core of the First Water Zone dissolved gasoline plume appears to be currently distributed near the location of wells MW-1 ' and MW-7, and contained within network of wells consisting of MW-2, MW-3, MW-4, MW-6, MW-9A, MW-10A, MW-11A, and MW-12A(Figure 4) ' Substantial concentrations of dissolved TPH-d and TPH-k have previously been detected in water samples collected from wells MW-1 and MW-7, indicating a limited distribution of TPH-d and TPH-k in the area assessed However, for the fifth consecutive quarterly ' monitoring event,TPH-d,TPH-k,and TPH-mo were not detected from any of the twenty-six water samples analyzed ' BTEX and 1,2-DCA concentrations in ground water samples MW-1 and MW-7 were • substantially above their respective Maxim Contaminant Levels in drinking water un� Vin ? X31I or • Very low concentrations of MTBE, TAME, �andaye been detected at wells ' MW-1, N 2, M,W' , M)Y-44, MW,.-6, and MW-7, indicating that there is only a minor impact of these components ' Based on the past five quarterly ground water monitoring events, the lateral and vertical extent of dissolved petroleum hydrocarbons appears to be limited to First Water Zone wells MW-1 and MW-7 at the site and approximately Z feet east of the site ' S.O. RECOMMENDATIONS Based upon data collected during the 3rd Quarter 2004, AGE recommends • Continued ground water monitoring utilizing wells MW-1 through MW-12, the fourth quarter 2004 ground water monitoring event was performed on 09 and 10 December 2004 ' • If applicable,conduct future ground water monitoring events concurrently with the Cal-Tank Lines site (3105 South El Dorado Street) • Continued quarterly depth-to-water measurements in all monitoring wells at the site, but ' reduced ground water sampling frequency at wells MW-2, MW-3 and MW-4 from a quarterly to an annual program, AGE believes that continued quarterly ground water ' Advanced GeoEnvironmental,Sue 1