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26 November 1996 <br /> AGE-NC Project No 95-0120 <br /> ' Page 3 of 4 <br /> concentrations of 130 parts per billion (ppb, reported as micrograms per kilogram), ,TPH-d was <br /> detected in ground water samples collected from MW-2 and MW-3 at concentrations of 73 and 98 <br /> ppb, respectively <br /> ' Benzene was detected in a ground water sample collected from MNV-3 at a concentration of 0 S ppb <br /> BTE&X and MTBE were not detected in any other ground water samples collected in September <br /> 1996 The laboratory report(AAL Laboratory Batch No 96-0910-008-01 through 03) and chain-of- <br /> custody form are included in Afpendix B <br /> i <br /> 4 0. CONCLUSIONS & RECOMMENDATIONS <br /> 1 41 CONCLUSIONS <br /> Ground water flow direction remained relatively constant at the site over the past two years, flowing <br /> 1 in a Southeasterly direction Under that condition, monitoring well MW-1 is consistently located in <br /> an up-gradient location from the former UST area, while monitoring wells MW-2 and MW-3 are <br /> located in the down-gradient positions <br /> r monitoring rin end the round water surface was between 0 15 feet and 0 28 feet above <br /> During this a to g p a g , <br /> the top of screen intervals in monitoring wells MW-2 and MW-3 Typically, the sand filter pack of <br /> these ground water monitoring wells extends between 2 and 3 feet above the slotted interval <br /> Thei efore, all analytical results of ground water samples collected from these wells are considered <br /> representative of the aquifer G <br /> 6 <br /> Based upon the low to moderate concentrations of hydrocarbon compound in the ground water over <br /> the monitoring periods since 1993' the concentration of hydrocarbon compounds leached from the <br /> vadose (soil) zone, reaching and the <br /> the water table appears to be relatively minor The <br /> majority of the hydrocarbon-impacted soil has previously been removed As hydi ocarbons commonly <br /> are held by adsorption to clay and silt, most of the hydrocarbons remaining in the soil are probably <br /> adhering to the fine soil particles and have little mobility <br /> I42 RECOItW'ENDATIONS <br /> t <br /> No further subsurface investigation is recommended for the site As part of site closure preparations, <br /> proper monitoring well abandonment should be performed ` <br />