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I , I I' 23 December 2603' w`h AGE-NC Project No 97-0333 I ' ' II Page 9:1of i 1 1 I { I M ' The results of pump and treat ground water remediation between 19 June 2003 and 10 September '2003 are as,follows I, • Approximately 218,888 gallons of hydrocarbon-Impacted groundwater were extracted from well EW-1,which was completed In the First Zone aquifer A total volume of approximately f, 1,666,498 gallons of hydrocarbon-Impacted ground water has been treated ati the site since ' the start-up period in January 2002 (Table 5) I F • Dissolved MTBE was detected from grab sample's collected at the Influent-end of the treatment system at concentrations between 3;100 µg11 and 4,600 µg/1, laboratory analysis ' of'grab water samples collected at the effluent-end of the pump and treat system detected TBA during the'August and September monthly monitoring events concern(Table 1) II , • Between 19 June 2003 and 10 September 2003, an estimated 6 60 pounds of MTBE was ' extracted from ground water(Table 5,Appendix B),a total mass of 215 16 pounds of MTBE has been removed since Initiation of the pump and treat system on 21 January 2002 A plot t of cumulative ground water pump and treat mass removal versus time and a plot of influent ground water MTBE concentrations versus time are Included In Appendix C, although a slight Increase was reported in August 2003,the overall general trend of decreasing MTBE ' concentrations Is evident f I I The results from theground water monitoring and,sampling events performed in August 2003 are i' as follows I • Generally, depth to groundwater at-the site varied between 22 and 27 Meet bsg,ground water elevations ranged between 5 26 feet(MW-11 C)and 9 44`feet(MW-5)above mean sea level 'The ground water'elevation decreased approximately 2 90 feet between June 2003 and the August 2003 ground water monitoring events, 'the average decrease in may be due to, ! seasonal fluctuation, however, the ground water elevation is the lowest documented at the 'site , • First Zone ground water flow was linferred to be towards a ground water depression in the area of wells EW-1 and MW-7A ata gradient between 0 007 ft/ft and 0 025 ft/ft(Figure 4) Second Zone,Third Zone and Primary Aquifer ground water flow was inferred to be towards the northwest at approximate gradients of 0 004 ft/ft 6r less(Figures 5,6 and 7,'respectively) C • [Due to the low ground water gradient atl the site, sma111 variations i"n ground water measurements or changes of recharge/discharge of the local ground water'could l greatly modify the inferred ground water flow direction ;, i i • The highest on-site concentrations of dissolved MTBE were detected m the samples �y I collected in the area of First'Zone monitoring wells MW-2 and MW-6 at concentrations as high as 5,400 µg/1 Lower concentrations of on-site MTBE were detected in water samples=k SII �� I I f i I Advanced GeoEnv�ronmental,Inc 1 I I