ARCHIVED REPORTS XR0000687 - Laserfiche WebLink

Home Browse Search

15 January 2002 • AGE-NC Project No 96-0232 IPage 12 of 16 I The results from the ground water monitoring and sampling events performed in December 2001 are as follows • Generally, depth to ground water at the site vaned between 14 and 17 feet bsg • First Zone ground water flow direction at the site appeared to be oriented toward the area of MW-i and MW-2 radially Inward from all directions at an approximate gradient of 0 002 f1/ft or less (Figure 3) Outside the area of Influence of MW-1, First Zone ground water flow direction was inferred east at an approximate gradient of 0 001 or less Second Zone ground water flow direction was Inferred to be generally toward the east- southeast at an approximate gradient of 0 002 f1/ft or less (Figure 4) • Secondary Aquifer Zone ground water flow direction was Inferred to be generally toward the east-southeast at an approximate gradient of 0 001 ft/ft or less (Figure 5) I Primary Aquifer Zone ground water flow direction was inferred to be generally toward the east-southeast at an approximate gradient of 0 002 ft/ft or less (Figure 6) • First Zone and possibly Second Zone ground water flow direction and gradient during the �. Flag City Chevron monitoring event appeared to be influenced by the remedial ground water extraction • Due to the low ground water gradient at the site, small variations In ground water measurements or changes of recharge/discharge of the local ground water could greatly modify the Inferred ground water flow direction ' • Increasing ground water elevations were reported at the site between September 2001 and December 2001 monitoring events Hydrographs depicting recorded ground water elevations ' at wells MW-2, MW-6A and MW-6B vs time are in Appendix I • On-site, the greatest concentration of dissolved MTBE was detected in the sample collected from First Zone extraction well EW-4 at a concentration of 53 ug/1 (Figure 8), low ' concentrations of on-site MTBE were detected in water samples from First Zone extraction wells EW-5,EW-6,EW-8,EW-9,EW-10, and from Second Zone monitoring well MW-9A, ' (Table 6, Figure 9) • Off-site,the greatest concentration of MTBE was detected in Rocky's Upper Zone water near the Rocky's Restaurant domestic water well in MW-1 IB at a concentration of 120µg11, in ' First Zone water from Flag City Chevron monitoring well MW-7 at a concentration of 42 yg/l, and in Three B's Truck Plaza monitoring well MW-4 at a concentration of 80 gg/l (Figure 7) Low concentrations of off-site MTBE were detected in First Zone water in ' samples collected from wells MW-12A, MW-13A, Three B's Truck Plaza monitoring wells MW-1, MW-2 and MW-6, Second Zone water from well MW-11A and Primary Aquifer water from well MW-11 D (Table 6, Figures 10 and 11) Advanced GeoEnvironmental,Inc