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I 1 IA 1 1 11I I 15 September 2003 AGE-NC Project No 97-0333 Page 8 of 11 I IY I trough in the area of wells MW-7F,MW-9D and MW-'l 1 E (Figure 7) Ground water'gradients were estimated at approximately 0 004 ft/ft or less EI ' � f I 315 2 'Laboratory Results of Ground Water Samples During the June 2003 sampling event, TPH-g was detected in water samples collected from wells MW-1 through MW-4, MW-6,MW-7 (A-D),MW-8 (B-D),MW-9 (A-B),MW-10(B-D),MW-11° (C-E) and MW-12 (A-D) at concentrations as high as 170,000 µg/l (MW-2) BTEX constituents were detected in water samples collected from wells MW-2 and MW-6 at � p maximum concentrations of 2,300 µg/1 (toluene and xylenes,'MW-2) Benzene was detected from wells MW-2 and MW-6 at concentrations of 810 µg/1 and 1,200 µg/1, respectjvley MTBE (utilizing EPA Method 8260M) was detected in water samples collected from monitoring ' wells MW-f through MW-4,MW-6,MW-7(A-E),MW-8(B-C),MW-11 C,MW-12B and MW-13D k at concentrations as high as,150,000 ug/l (MW-6), isoconcentration maps displaying the estimated extent of dissolved MTBE 1n First Zone and Second Zone aquifer are depicted 1n Figures 8 and 9 ` TAME was detected in w4ater samples collected from monitoring wells MW-1, MW-2, MW-3 and 1 MW-6 at concentrations as high as 1,100 µg/l,(MW-6), 1,2-DCA was detected in water samples collected from monitoring wells MW-7 (B-D), MW-8 (B-C) and MW-10 (B-C) at concentrations i i as high as 8 µg/l (MW-8B) I'� PCE,and/or TCE were detected in 41 of 47 water samples collected from monitoring wells MW-1 through MW-13 at concentrations as high as 1,200 µg/1 from MW-4 and 1,300 µg/l from well MW-12A An rsoconcentration map displaying the estimated extent of dissolved PCE lin First Zone 'water is depicted in I Figure 10 I No other constituents of concern Iwere detected above laboratory reporting limits in the water samples collected during the first quarter 2003 sampling event Analytical results of ground water i monitoring well samples are summanzed an Tables 3 and'4 The laboratory reports (Cal Tech A' I Environmental Laboratories Identification No 0306-055-1 through 47)and chain-of-custody forms 1 are presented in Appendix E " ` 4.0 " SUMMARY AND CONCLUSIONS II ` ' II Previous soil characteristics data obtained by a CPT investigation 'enabled AGE ,to define four Oil informal hydrologicunits (CPTSate Investigation-Fourth Quarter 2000dated 07 February 2001) I''II i Advanced Ge oEovlronmental,I Inc i I si f I JII, { I