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1 <br /> 1 <br /> 30 April 1996 <br /> r AGE-NC Project No 95-0128 <br /> Page 3 of 4 <br />' 4.0. FINDINGS <br />' 4 1 GROUND WATER GRADIENT AND DIRECTION <br /> Ground water depth at the site ranged from 37 71 to 38 78 feet below the tops of the well casings <br /> Between December 1995 and March 1996, ground water elevation rose an average of 6 8 feet The <br /> increase in ground water elevation corresponds to an abnormally high amount of rainfall received in <br />' the region during the winter of 1995-1996 Ground water elevations are summarized on Table 1 <br /> Using data collected on 07 March 1996,the ground water gradient and flow direction were calculated <br /> to be 0 002 ft/ft, directed N 8°E Ground water elevation contours for the 07 March 1996 momtoring <br /> event is illustrated in Figures 3 -Relative Ground Water Elevation <br /> I Because of the significant rise in ground water at the site over the past two years, the water Ievel is <br /> above tops of the screened interval in all monitoring wells at the site <br /> 4 2 PETROLEUM HYDROCARBON-IMPACTED GROUND WATER <br /> TPH-g and TPH-d were detected in VW-1 at concentrations of 240,000 and 4,600 ,ugA (micrograms <br /> per liter or parts per billion ppb), respectively BTE&X were detected in VW-1 at concentrations <br /> up to 33,000 ppb (toluene) MTBE was detected at 590 ppb in the sample collected from VW-1 <br /> Analytical results of the ground water samples are summarized in Table 2 The laboratory report <br /> (AAL Batch No 96-0308-009) and chain-of-custody are included in Appendix B <br /> 5.0. CONCLUSIONS AND RECOMMENDATIONS <br /> The hydrocarbon plume continues to remain in the immediate vicinity of Well VW-1 However, <br /> because the top of the screened intervals in the monitoring wells at the site are beneath ground water, <br /> E samples collected from these wells may not be representative of ground water conditions in the area <br /> Thus, the lateral extent of ground water contamination at the site cannot be established with <br /> confidence from data derived from the existing wells <br /> It is likely that the PHS-EHD will require the installation of additional monitoring wells with <br /> appropriately screened intervals Soil samples collected during drilling and installation procedures <br /> should undergo analysis for microbiological enumeration, physicochemical parameters and <br /> geotechnical properties to determine the feasibility of enhanced bioremediation or natural attenuation <br /> of the hydrocarbon-impacted soil <br /> The next quarterly monitoring should be scheduled for June 1996 If additional monitoring wells are <br />