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r <br /> Ir <br /> • 07 September 1999 <br /> AGE-NC Project No 95-0104 <br />' Page 4 of 8 <br />' 4.0. FINDINGS <br /> From ground water monitoring data,AGE was able to determine the ground water flow direction and <br />' gradient Laboratory analysis detected TPH-g and BTEX in all four ground water samples <br /> From field data collected during operation of the SVE/IAS pilot test and from laboratory analysis <br />' of five soil gas samples,AGE was able to estimate the volume of vapor gasoline extracted from well <br /> VW-1 <br /> I <br /> 41 RELATIVE GROUND WATER ELEVATION AND GRADIENT <br /> During the July 1999 monitoring event, depths to ground water in wells MW-1, MW-5, MW-6 and <br /> VW-1 were measured between 58 37 and 60 32 feet below the tops of well casings, between the <br /> April 1999 and July 1999 ground water monitoring events, ground water elevat.on at the site <br /> decreased an average 6 15 feet The ground water elevation data for wells MW-1, MW-5,MW-6 and <br /> VW-1 during the July 1999 ground water monitoring event is depicted in Figure 3 and shown on <br /> Table 1 <br /> Ground water flow direction was generally toward the southeast at a gradient of 0 15 ft/ft, or <br /> approximately 800 feet per mile (Figure 3) Ground water was approximately 5 to 7 feet above the <br /> screen intervals at MW-5 and MW-6 Therefore these wells are "drowned", and may yield samples <br /> more representative of deeper ground water than of shallowest ground water, which is commonly <br /> the more intensely impacted by petroleum hydrocarbons Monitoring well MW-1 and vapor <br /> extraction well VW-1 are screened across the top of the saturated zone <br /> 42 ANALYTICAL RESULTS OF GROUND WATER SAMPLES <br /> A total of four ground water samples were submitted to a DHS-certified laboratory° in July 1999 <br /> TPH-g was detected in water samples collected from wells MW-1, MW-5, MW-6 and VW-1 at <br /> concentrations ranging as high as 1,100 micrograms per liter(µg/1) <br /> BTEX compounds were detected from ground water samples collected at MW-1, MW-5,MW-6 and <br /> IVW-I at concentrations ranging as high as 190 ,ug/l The greatest concentration of benzene was <br /> detected from well MW-5 at a concentration of 49 µg/1 <br /> Analytical results of the ground water samples are summarized in Table 2 The laboratory reports <br /> • (McCambell Analytical Inc Lab I D No 16504 through 16507) and chain-of-custody forms are <br /> presented in Appendix B <br /> IAdvanced GeoEnvironmental,Inc <br />