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r r12 February 2003 AGE-NC Project No 95-0128 rPage 6of7 r3 4 MASS CALCULATION OF RECOVERED PRODUCT The mass of hydrocarbons removed was calculated from the volume of water treated and the r concentrations from laboratory analysis A total volume of 267,904 gallons was extracted between 15 August and 16 December 2002, based on effluent flow meter observations r Based on the total water volume extracted, 0 27 kg or 0 59 lbs of MTBE, 0 21 kg or 0 46 lbs of benzene and 1 64 kg or 3 61 lbs of TPH-g were removed from the site and treated r The hydrocarbon mass removal calculations and the concentrations of the influent samples over time are displayed in Appendix D r4.0. SUMMARY AND CONCLUSIONS rThe following conclusions were drawn from the results of this quarterly investigation • Ground-water elevations measured during the November 2002 monitoring event ranged 10 between 21 10 and 22 70 feet below MSL, ground water flow direction at the site was inferred to be northeast towards a well-defined cone of depression at extraction well EW-1 • Dissolved petroleum hydrocarbons quantified as TPH-g and TPH-d were detected in ground water samples MW-4,MW-5 and VW-1,collected within the northeastern portion of the site, TPH-d was also detected in sample MW-6 r0 Various BTEX compounds were detected in ground water samples MW-1 through MW-5 and V W-1 The highest concentrations of benzene,ethylbenzene and xylenes were detected in sample MW-5, the highest toluene concentration was In sample VW-1 The benzene concentrations in samples MW-4,MW-5 and VW-1,the toluene concentration 1n VW-1 and the ethylbenzene and xylenes concentrations in MW-5 were above the DHS' Maximum r Contaminant Levels (MCLs) in drinking water • The highest concentration of MTBE(640µg11)was detected in the ground water sample from off-site monitoring well MW-11 A Lower or non-detectable MTBE concentrations in down- gradient and cross gradient wells defined the dissolved MTBE plume toward the north and west, however, the dissolved M TBE p lume has not been defined east of well MW-15 (Figure 4) r0 TBA and 1,2-DCA were detected in samples MW-5 (67 gg/l) and MW-3 (1 4 µg/l), respectively, these concentrations are above the DHS' Action Level of 12 µg/l for TBA and MCL of 0 5 µg11 for MTBE in drinking water rAdvanced GeoEnvironmental Inc r