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18 August 2004 S AGE-NC Project No 98-0534 Page 3 of 4 _ 32 ANALYTICAL RESULTS OF GROUND WATER SAMPLES TPH-g was detected in the ground water samples collected from wells MW-2,PW-4, MW-6 and MW-8 at concentrations ranging between 170 micrograms per litef(pg/1)in sample MW-8 and 330 ' pg/l in sample MW-6 TPH-d and BTEX compounds were not detected in the groundwater samples analyzed MTBE was detected by EPA Method 8260 in the samples from wells MW-3, MW-4, MW-6 and ti MW-8 at concentrations ranging between 3 9 pg/1(MW-8)and 320 Ag/1(MW-6) EDB was detected x ' for the first time in sample MW-6 at a concentration of 5 4 pg/l F No other target analytes were detected in the analyzed samples The current and historical ground ' water analytical results are summarized on Table 2 The laboratory report (Cal Tech Project No CT214-0407121), chain of custody forms and the laboratory QA/QC report are included in ' Appendix B GeoTracker confirmation pages of the submitted Iaboratory electronic deliverable format (EDF) files are included in Appendix C ' 4.0. SUMMARY AND CONCLUSIONS ' The implications from the July 2004 ground water monitoring event are as follows 1 • The potentiometric surface was inferred to be relatively flat in the area of the former UST ' area, but sloped steeply towards a n3%Kkest-trending trough north of the UST area • TPH-g concentrations increased to their highest-recorded values in wells MW-4 and MW-6, and were detected for the first time in wells MW-2 and MW-8 A TPH-g isoconcentration map is Illustrated on Figure 4 • MTBE was detected In four monitoring wells, with the highest dissolved concentration occurring in well MW-6, within the former UST area, at a concentration of 320 µg/1 An MTBE Iso concentration map Is Illustrated on Figure 5 • Dissolved MTBE in shallow ground water appeared to be delineated by the well network I Advanced GeoEnvironmental,Inc