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22 October 2009 AGE-NC Project No. 00-0697 Page 5 of 10 2.4. GROUND WATER MONITORING:EVENTS Between November 2004 and October 2008,seventeen(17)ground water monitoring events were performed at the site to monitor dissolved petroleum hydrocarbon concentrations in ground water and to characterize ground water flow direction and gradient.on the site. Since initiation of the ground water monitoring program,ground water elevations ranged between 16.58 feet to 21.03 feet below the North American Vertical Datum(NAVD);depths to ground water ranged between 2.56 to 6.82 feet below the tops of the well casings(btoc)..From November 2004 to August 2005, and from August 2007 to October 2008, ground water flow direction at the site was inferred to be generally towards the north,at hydraulic gradients ranging between 0.007 fr/ft and 0.4 ft/ft.Between, November 2005 and May 2007 ground water flow direction at the site was inferred to range between the west and south at hydraulic gradients between 0.007 ftJft and 0.01 ft/ft.Ground water elevation data is summarized in Table 4. Ground water elevation figures depicting ground water flow directions and gradients from November 2004 to October.2008 are presented in Appendix D. Based on quarterly ground water monitoring results between November 2004 and October 2008, TPH-g and benzene were established as the contaminants of concern at the site(Table 5). Between February 2005 and February 2008, TPH-g and benzene concentrations were detected from well MW-3 at concentrations as high as 3,300 pg/I and 490 µg/l, respectively. However, TPH-g and benzene have not been detected from well MW-3 since May 2008 and February 2008,respectively. Laboratory analysis of ground water samples only detected TPH-g and benzene on one occasion from wells MW-1, MW-2, and MW-5; TPH-g and benzene have never,been detected above laboratory reporting limits from wells MW-4 and MW-6. Ground water monitoring well analytical data is summarized in Table 5. Based on a plot of TPH=g and benzene versus time(Appendix E),a definitive trend of decreasing dissolved concentrations is evident at the site from monitoring well MW-3. 2.5. STRATIGRAPHY In general,moist,black peat and silty peat were encountered from surface grade to 5 feet bsg across most of the site. However,peat and silty peat were encountered from surface grade to 9.5 feet bsg in the area of well MW-2.Additionally,fill dirt was encountered in boring MW-3 from surface grade to approximately 5 feet bsg. Silty clay, sandy clay, and clayey silt were generally encountered in borings MW-1,MW-3 and MW4 from 5 feet bsg to approximately 15 feet bsg,in boring MW-2 from 9.5 feet bsg to approximately 15 feet bsg, and in boring MW-6 from 5 feet bsg to approximately 20 feet bsg. Silty fine sand was encountered.froml 5 feet bsg to the;total depths of borings MW-1 through MW-4 and from 20 feet bsg to approximately 29 bsg in boring MW-6. A layer of moist clay was identified between 29 feet and 31 feet bsg..From 31 feet bsg to the total depth Advanced G mEavironmental,Inc.