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> t ` JI _ I f ` 16 August 2004 AGE-NC Project No 96-0235 Page 4 of 6 t I MTBE was detected in the water samples collected from MW-9,MW-11 B,MW-12B,MW-13B and I MW-14B at concentrations ranging from 25 }Ig/1 (MW-12B) to 110 µg/1 (MW-9) Water samples k analyzed from MW-1, MW-2, MW-11B,MW-14B and EW-2 contained detectable concentrations of 1,2-DCA ranging from-2 2 µg/l (EW-2) to 29 µg/1 (MW-14B) Concentrations of D1PE, ETBE, TAME,TBA,EDB,methanol and ethanol were not detected above laboratory reporting limits in any ' of the water samples collected during the May 2004 monitoring event ; Analytical results of water samples collected during the Second Quarter of 2004 are summarized on Tables 2 and 3,analytical results from previous monitoring events are summarized in Tables 4 and 5 Figures 5 and 6 illustrate the ground water contamination plumes in upper and lower ground water ' intervals, respectively The laboratory report (CTEL Laboratory IDs 0405-018=1 through 0405-018-10 and 0405-030-1 through 0405-030-10),-chain of custody forms and the laboratory ' QA/QC report are included In Appendix C GeoTracker confirmation pages of the submitted laboratory electronic deliverable format (EDF) files are included In Appendix D 4.0. SUMMARY AND CONCLUSIONS I ' • Based on the data collected from the former northern UST cluster area, AGE finds • The shallow-screened data delineate a radial ground water flow pattern, with a net flow ' towards the northeast at a gradient of 0 003 ft/ft, the deep-screened data delineated a ground water flow direction toward the northeast at a gradient of 0 002 ft/ft Ground water gradient and flow direction observed dunng the Second Quarter 2004 were similar to'the previous 1 ' - y quarter E ' • TPH-g was detected In ground' water, samples collected from MW-9 and MW-14B 'at concentrations of 110 pg/1'and 130 µg/l, respectively ' r • MTBE was riot'detected In the,shallow-screened wells sampled during the Second Quarter 2004 MTBE was detected by EPA Method 8260B in the deep-screened wells MW-9, '. MW-12B, MW-13B and MW-14B at concentrations as high as 110 µg/1 (MW-9) The " I reported MTBE concentrations were above the DHS' Pnrnary MCL of-13 pg/l in drinking j -r ' wafer" 1 • 1,2-DCA was detected in ground water samples,collected from, wells MW-11B and ' MW-14B,,the detected concentration exceeded the-DHS' MCL • The,most Impacted ground water appears to be centered around the former UST dispenser location The vertical extent of the contamination plume,as,well as the lateral extent east and south'of the former UST cluster, Is not well defined 1 Advanced GeoEnv►ronmental,Inc S � F I IS M1 1 I I I I I -