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Mr. Soon Kim <br /> Page 4 <br /> August 11, 1995 <br /> 102429.AS.T8 <br /> Groundwater Gradient <br /> Water levels were measured at the site on June 20, 1995, by Del-Tech while the AS/SVE <br /> system was in operation. Shallow groundwater surface elevations are provided in Table 1. for <br /> each well measured since September 1991. Shallow groundwater elevation contours are <br /> drawn in Figure. 2 for the June 20, 1995 monitoring event. Groundwater elevation has <br /> generally increased across the site by approximately 2.5 feet since the last measurement in <br /> March 1995. Groundwater mounding around the AS/SVE wells appears to be more <br /> pronounced than in the previous quarter. Historically,-the groundwater flow. direction has <br /> varied from slightly northeast to northwest, and the gradient has been roughly 0.001 fttft. <br /> Comparison of the groundwater elevation measurements in well pair MW-DIS-8S/8D reveals <br /> a 0.012 ft/ft downward gradient that is consistent with the previous quarter. <br /> Analytical Results <br /> Analyses of groundwater samples from monitoring wells are presented in Table 2. Highlights <br /> of the analytical results include; <br /> 1. The more easily biodegradable gasoline constituents (i.e., toluene and xylenes) show a <br /> favorable declining concentration trend over the period of record (1991 - 1995) in MW- <br /> DIS-2. This well is believed to be out of the range of influence of the AS/SVE system. <br /> 2. Dissolved phase gasoline constituent concentrations in the immediate vicinity of the <br /> AS/SVE system (i.e. MW-DIS-1) have declined by greater than an order of magnitude <br /> since active remediation start up. <br /> 3. Low gasoline constituent concentrations were observed in MW-DIS-3. This well has had <br /> no measurable contamination since June 1992. <br /> 4. For the second consecutive quarter, MW-DIS-8D has produced groundwater with trace <br /> BTEX concentrations. <br /> 5. A very low benzene concentration was measure in groundwater from MW-DIS-10. <br /> 6. Monitoring wells MW-DIS-4, 5, 6, 7S, and 7D were not sampled this quarter. <br /> Laboratory reports and chain of custody forms are attached. <br />