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30 January 2004 AGE-NC Project No 96-0232 Page 14 of 15 900 4g/1) detected in northernmost Flag City Chevron well MW-8 during the previous seven quarterly ground water monitoring events It is not clear at this time why MTBE was detected at MW-8A over the past eight quarters, at concentrations which fluctuated between 4 7 µg/1 and 900µg/1, after non-detectable concentrations were recorded in nine previous quarters of monitoring Since initiation of ground water extraction activities at the site, First and Second Zone ground water flow direction in the area of MW-8 has generallybeen towards the south-southeast,and should draw on-site contaminants away from MW-8 (Figure 5) The most intense MTBE detections were reported during the March 2002 and the March 2003 sampling events, which could be related to re-mobilization of adsorbed MTBE in soil as a result of the seasonal high ground water levels observed at the site each year near March(Table 4), however,intermediate well MW-4, located between MW-8 and the UST area, have no detection of MTBE, although screened in the First Zone, and three soil borings (P-36 through P-38) advanced in October 2002 to assess the area near MW-8 (Figure 2)did not detect MTBE in grab ground water samples collected from First Water and Second Water At this time,AGE has tentatively concluded that the MTBE detections in MW-8 are related to a separate dissolved MTBE plume (Figure 10) . 6.0 RECOMMENDATIONS Based upon data collected from the site, AGE recommends Continued quarterly ground water monitoring and sampling of monitoring wells MW-1 through MW-18 Continued coordinated quarterly ground water monitoring and sampling events with Three B's Truck Plaza Continued ground water extraction(pump-treat)from wells EW-4,EW-5, EW-7 and EW-8 Between 20 and 22 January 2004, five Geoprobe soil borings were advanced at the site for collection of soil and ground water samples to assess the migration pathway of MTBE-impacted ground water detected at MW-8A A report of findings and recommendations for addressing MTBE-impacted ground water at MW-8A will be prepared during the first quarter 2004 7.0. LIMITATIONS Our professional services were performed using that degree of care and skill ordinarily exercised by environmental consultants practicing in this or similar localities The findings were based mainly upon analytical results provided by an independent laboratory Evaluations of the hydrogeologic conditions at the site for the purpose of this investigation are made from a limited number of Advanced GeoEnviranmental,Inc