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1 <br />' 20 January 2005 <br /> AGE-NC Project No 97-0343 <br />' Page 7 of 21 <br />' 6.0. ASSESSMENT OF HYDROCARBON-IMPACTED GROUND WATER <br /> Between 29 February 2000 and 28 September 2004, 19 ground water monitoring events were <br />' conducted on Flsco Warehouse wells MW-1 through MW-3, 15 events on wells MW-4 through <br /> MW-7 and five events on well MW-8 These ground water monitoring events were preformed to <br /> monitor shallow and deeper dissolved fuel component concentrations and to characterize ground <br />' water flow direction and gradient on the site In addition, grab ground water samples were collected <br /> from soil borings CPT1, CPT2 and CPT3 at discreet depths ranging from 78 feet to 98 feet <br /> Laboratory analysis of water samples from the wells and soil borings Indicated that ground water at <br />' the site locally has been Impacted by TPH-g, TPH-d, BTEX, TBA, EDB and 1,2-DCA (Tables 7 <br /> and 8) <br />' The highest dissolved petroleum hydrocarbon concentrations detected in ground water monitoring <br /> well samples were detected in the samples collected from monitoring wells MW-1 through MW-3, <br /> located at or near the former UST pit TPH-g, TPH-d, BTEX, TBA, EDB and 1,2-DCA have been <br />' detected at concentrations as high as 44,000 µg/1 (MW-2), 25,000 fig/1 (MW-2), 93 µg/l (MW-1), <br /> 3,300µg/1 (MW-1), 2,200 µg/1 (MW-2), 11,000 µg/l (MW-2), 5 1 µg/1 (MW-2), 21 pg/1 (MW-1), <br /> 200 µg/1 (MW-2) respectively, during the site Investigation Minor concentrations of dissolved <br /> petroleum hydrocarbons have been detected in ground water samples from monitoring wells MW-4 <br /> through MW-7 With the exception of 1,2-DCA(MW-4),contaminants of concern(COC)have not <br /> Ibeen detected after the fourth quarter 2001 in these wells (Table 7) <br /> The extent of TPH-g, TPH-d and BTEX compound-Impacted ground water appears to be limited to <br />' the immediate area surrounding MW-1 through MW-3, relative to the inferred source area near the <br /> former UST area Mass of dissolved CDCs cannot be calculated accurately at this time due to the <br /> continued decline in ground water level at the site, currently only one well, MW-8 screened at 90 <br />' feet to 95 feet bsg, is continually producing water for quarterly sampling Ground water samples <br /> have not been obtained from MW-1 through MW-3 since second quarter 2002, with exception to <br /> first quarter 2004 (MW-2 and MW-3 were sampled with out purging and indicated dissolved <br />' hydrocarbons remain at those two locations) Ground water samples have been obtained <br /> Intermittently from wells MW-4 through MW-7 since second quarter 2002, with samples coming <br /> during the winter and spring quarters <br /> 7.0. SITE CONCEPTUAL MODEL <br />' Based on the data collected to date from soil borings and monitoring well installations, AGE has <br /> developed a site conceptual model (Figure 9) for the release, migration and distribution of the <br /> contaminants in the subsurface as described below <br /> Advanced GeoEnvironmental,Inc <br />