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' 08 April 2005 AGE-NC Project No 95-0173 ' Page 8 of 10 ' screened Intervals of all other wells at the site and should be representative of shallow ground water conditions • Ground water elevation data collected on 30 November 2004 implies that ground water fmounding did not occur at the site due to the on-going IAS activities • The elevated concentrations of petroleum hydrocarbons detected in samples collected from ' wells MW-2 (screened 30 feet to 50 feet) and MW-4 (screened 30 feet to 50 feet) indicate that these wells are within the remaining dissolved petroleum hydrocarbon"core area"of the plume (Figure 4) ' The rapid decrease in dissolved petroleum hydrocarbon concentrations at AW-1 (A and B) and AW-2 (A and B)can be attributed to the ongoing air sparging activities at well AW-1 B during July through December 2004 However, previous analytical ground water data has indicated this concentration reduction may later rebound • The rapid,upward movement of volatilized hydrocarbons at AW-IB was substantiated with ' the observed `spikes' in the August, September, October and November influent air flow samples � . Generally, an overall apparent trend of decreasing dissolved petroleum hydrocarbon concentrations is evident in water samples collected from wells MW-3, MW-4, MW-6, AW-1 (A and B), and AW-2 (A and B), the trend of decreasing concentrations may be attributed to the air sparge activities being performed at well AW-1B (Table 3) • A moderate increase in dissolved hydrocarbons was observed in well MW-1,the increase in I hydrocarbon concentrations may be attributed to a`rebound' effect from the second quarter 2004 IAS activities previously conducted from well AW-2B • A significant decrease in dissolved hydrocarbons was observed at well MW-2,the significant decrease may be representative of a eastward shift of the ground water plume probably caused by 3`a quarter 2004 reconfiguration of air spargmg from well AW-2B (60-70 feet)to AW-1B (50-60 feet) • Previous and current laboratory results of ground water samples suggest that there is a minor 1,2-DCA impact to ground water in the areas of wells MW-2 through MW-4 and AW-2 (A and B, Tables 3 and 4) Based on SVE remediation data collected between 23 September and 22 December 2004, AGE concludes • The average SVE inlet vapor concentration was approximately 820 µg11, the average SVE Inlet flow rate was approximately 74 cubic feet per minute (Table 6) ' Advanced GeoEnvironmental,Inc