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' 15 October 2002 AGE-NC Project No 96-0232 Page 10 of 19 ' generally decreased an average 6 36 feet between the June 2002 and the September 2002 ground water monitoring events ' Ground water elevation data collected from multi-level wells MW-9 (A, B and C), MW-11 (A, B, C and D) and MW-13 (A, B, C and D) on 04 September 2002 was depicted on cross section C-C' (Figure 3),the vertical gradient between adjacent screen intervals is depicted on cross section C-C' ' The vertical gradient between adjacent screen intervals was calculated by determining the difference between groundwater elevations(dh)and dividing by the difference ofthe screen interval midpoints (dl) Generally,very slight upward and downward vertical gradients were observed between the First ' Zone, Second Zone, Rocky's Upper Zone and Secondary Zone screen intervals of MW-9, MW-11 and MW-13, however, a substantial increase in upward vertical gradient, by more than a factor of one, was measured at wells MW-9, MW-11 and MW-13 in screen intervals located between the ' Secondary Zone and Primary Zone ' The 04 September 2002 ground water elevation data collected from the Flag City Chevron site and the adjacent Three B's Truck Plaza site were plotted for the informal First Zone, Second Zone, Secondary Aquifer Zone and Primary Aquifer Zone hydrogeologic flow units as defined in AGE's lie Final Remediation Plan, and are depicted in Figures 4, 5 and 6 3 4 1 1 First Zone Aquifer Ground water elevation data collected in the First Zone Aquifer (5 to 35 feet bsg) indicated that ' ground water flow direction was inferred to be west to northwest in the area of Flag City Chevron wells MW-1,MW-2,MW-5 and MW-6A,but apparently veering towards west to southwest between Flag City Chevron wells MW-7, MW-13A and Three B's Truck Plaza wells MW-1 though MW-6 (Figure 4) The ground water gradients ranged from approximately 0 005 ft/ft near the Flag City Chevron site to 0 006 ft/ft near the Rocky's Restaurant and Three B's Truck Plaza sites ' 3 4 12 Second Zone Aquifer ' Ground water elevation data collected in the Second Zone Aquifer(40 to 60 feet bsg)was inferred to be towards the southwest in the area of Flag City Chevron wells MW-6B,MW-SA and MW-9A, ' veering to a west-southwest direction between Flag City Chevron wells MW-11A, MW-12B and MW-13B(Figure 5) Ground water gradients ranged from approximately 0 002 ft/ft near the Flag City Chevron site to 0 006 f1/ft near the Rocky's Restaurant and Three B's Truck Plaza sites Advanced Geo E nviron mental,Inc 1