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31 August 2005 <br /> AGE-NC Project No 96-0232 <br /> Page 12 of 30 <br /> 2 4 1 Ground Water Depths <br /> Generally,ground water levels between 1991 and 2005 were recorded at the site to be between 7 and <br /> 15 feet bsg,although a ground water low of approximately 3 feet was observed in February 1998 and <br /> ground water high of approximately 18 feet was observed in September 2002 Ground water <br /> elevations at the site generally fluctuated between 2 feet above mean sea level(msl)and 6 feet below <br /> msl <br /> 2 4 2 Ground Water Flow Direction and Gradient <br /> Between May 1991 and August 2000 and prior to any pump-and-treat (P&T) ground water <br /> remediation activities at the site (November 2000), ground water flow direction was typically <br /> inferred to be towards the north-northeast-northwest, however, ground water flow direction was <br /> documented towards the south-southwest-southeast on two occasions(July and August 1996),locally <br /> varying between northeast and southwest on one occasion (February 1999) and locally varying <br /> between northwest and southeast on one occasion(June 1999) Generally,groundwater gradient was <br /> presumed relatively horizontal at the site ranging between 0 001 and 0 003 <br /> Between December 2000 and August 2004 (during pump-and-treat ground water remediation <br /> activities),ground water flow direction at the site was typically inferred to be towards a ground water <br /> depression in the area of Flag City Chevron wells MW-1, MW-2 and MW-4 Generally, ground <br /> water gradient varied between 0 003 and 0 01 <br /> Ground water pump-and-treat operations were terminated in August 2004, following termination of <br /> pump-and-treat operations, ground water monitoring events were performed in September 2004, <br /> December 2004 and March 2005 During these events, ground water flow direction was typically <br /> inferred between east and southeast at a hydraulic gradient of 0 001 Groundwater monitoring data <br /> is summarized in Table 6, representative ground water elevations and ground water flow directions <br /> between 1996 and 2005 are presented as Appendix H <br /> 2 4 3 Dissolved MTBE Concentrations <br /> Between July 1996 and March 2005,AGE performed thirty-two quarterly ground water monitoring <br /> well events to monitor petroleum hydrocarbon concentrations in ground water,based on the results <br /> of the July 1996 to March 2005 quarterly ground water samples,MTBE has been established as the <br /> contaminant of concern at the site (See Table 7) <br /> Advanced GeoEnvironmentai,Inc <br />