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r k I , '^ 30 January 2004 - AGE-NC Project No 00-0769 .: Page 6 of 7 , I „r BTEX compounds were detected in samples MW-4E and MW-5E at concentrations of 20 gg/L and , ' 32 gg/L of benzene,20 gg/L and 38 lig/L oftoluene,5 7 µg/L and 8 2 µg/L ofethylbenzene and 18 2 µg/L and-47 gg/L of total xylenes, respectively The fuel oxygenate MTBE was detected in the HU-5 sample from MW-4E at a concentration of 12 pg/L ' No other constituents of concern were detected above laboratory reporting limits in the water u ' samples collected during the second quarter sampling event Analytical results of ground water monitoring well samples are summarized in Tables 2 through 5 The laboratory reports,(CTEL Project No CT214-0305161) and chain-of-custody forms are presented in Appendix C Y I I I 4.0. SUMMARY AND CONCLUSIONS I The following conclusions were drawn from the results of the site investigation • Depth to ground water at the site vaned between 25 02 and 29 00 feet bsg, relative ground ' water elevations at the site ranged between 14 32 and 18 25 feet below MSL during the May 2003 monitoring event HU-1 generally flowed southeast with a limb flowing 0 005 ft/ft to ' the southeast and 0 005 ft/ft to the east-southeast HU-2 generally flowed to the southwest with a limb flowing east-southeast at 0 002 ft/ft and north-northwest at 0 002 ft/ft HU-3 general ly,flowed north-northeast with a limb flowing east of north at 0 008 ft/ft and north- northeast at 0 011 ft/ft HU-4 generally flowed east-southeast with a limb flowing northeast j ' ','at 0 006 ft/ft and southeast at 0 004 ft/ft (Figures 3 through 6) � r, , rr • ; ,The most highly impacted ground water appears to be located near the first and second ' „former UST, Ilocations, figures 7 through 11 illustrate the lateral extent of Hydrocarbon-impacted ground water, as depicted within each modeled hydrogeologic unit , 'Vertically, hydrocarbon-impacted ground water was detected inleach each of the screened intervals of'multi-level wells MW-4 through MW-7 The concentrations of dissolved hydrocarbons increased at the total depth of well MW-7, representing the'lowest, down- ' " 'gradient point,in the`monitoring well network Up-gradient multi-level well MW-9 and F ' z cross-gradient multi-level well'MW-8 had low to nori-detectable concentrations ofpetroleu n ' hydrocarbon compounds ' — I ' , H • ' Concentrations of benzeneiwere detected in ground water samples collected from monitoring wells MW-4 and MW-5, screened in each of the five identified hydrogeologic units, above the DHS's Maximum Contaminant Levens (Mds) of 0 5 gg/L, 1,2-DCA was detected in, ' every unit except HU-5 E r ' I i 1 r a i Advanced Geol:nvironmental,Inc F I s, y I