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20 May 1996 <br /> AGE-NC Project No 95-0101 <br /> Page 4 of 4 <br /> but the gradient and flow direction is variable toward the north end of the site April 1996 ground <br /> water contours are illustrated on Figure 3 <br /> 4 2 LABORATORY ANALYSIS OF WATER SAMPLES <br /> Xylenes were detected in samples collected from monitoring wells MW-2 and MW-3 at <br /> concentrations of 2 0 pg/l (rrucrograms per liter, equivalent to parts per billion, ppb) and 0 92 ppb, <br /> respectively No other petroleum hydrocarbons were detected in samples collected during the April <br /> 1996 monitoring event The analytical results are summarized on Table 2 The laboratory report (MAI <br /> sample Nos 63015 to 63017) and chain-of-custody form are included in Appendix B <br /> 5.0. CONCLUSIONS & RECOMMENDATIONS <br /> Low concentrations of xylenes were detected ;n two of the wells sampled during the current <br /> monitoring event However, petroleum hydrocarbons were not detected in the two monitoring wells <br /> during the May or August 1995 sampling events <br /> Based upon the intermittent, low concentrations of hydrocarbons detected at the site, ground water <br /> remediation is not recommended at this time The next quarterly sampling for the site should be <br /> scheduled for July 1996 <br /> Impacted soil at the site appears to be limited to a narrow vertical zone between 35 and 45 feet bsg <br /> near VW-1 and MW-2 The effected soil consists of relatively impermeable silt and clay Since May <br /> 1995, only traces of xylenes have been detected in monitoring wells at the site It appears that the <br /> limited quantity of impacted soil remaining at the site has not resulted in increased ground water <br /> degredation We therefore recommend the preparation of a soil contaminant fate and transport model <br /> to determine the potential future risk to ground water at the site <br /> 6.0. LIMITATIONS <br /> Our professional services were performed using that degree of care and skill ordinarily exercised by <br /> environmental consultants practicing in this or similar localities The findings were based upon <br /> analytical results provided by an independent laboratory Evaluations of the geolognc/hydrogeologic <br /> conditions at the site for the purpose of this investigation are made from a limited number of available <br /> data points(i a monitoring wells) and subsurface conditions may vary away from these data points <br /> No other warranty, expressed or implied, is made as to the professional recommendations contained <br /> in tins report <br />