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8 August 2000 <br /> • AGE-NC Project No 95-0143 <br /> Page 6 of 8 <br /> screened intervals of each vapor well The approximate hydraulic gradient was calculated to be 0 002 <br /> ft/ft with a northeasterly flow direction on the subject property Ground water elevation was higher <br /> in wells VW-1 and VW-3, indicating ground water mounding possibly due to the vapor extraction <br /> The ground water elevation in MW-3 also showed an increase of 0 62 feet, indicating that ground <br /> water mounding may be occurring beyond the immediate vicinity of the extraction wells However, <br /> ground water elevations in VW-2 and VW-4 had elevation decreases Ground water elevation <br /> contours for the May 2000 monitoring event are illustrated in Figure 4 <br /> Ground Water Depth Field Log dated 5-9-00 contained in Appendix C was found to contain data that <br /> may have been switched or recorded erroneously Ground water elevations were determined using <br /> Monitoring Well Field Logs dated 5-10-00 through 5-12-00 and are included in Appendix C <br /> 3 4 ANALYTICAL RESULTS OF WATER SAMPLES <br /> During the May 2000 monitoring event, TPH-g was detected in samples collected from six of the <br /> nine monitoring wells at concentrations ranging from 250 µg/1 to 200,000 µg/1 (MW-3) BTEX <br /> compounds were also detected in seven of the wells at concentrations as high as 48,000 µg/l(toluene <br /> in the sample from MW-3) Fuel oxygenates were not detected in samples collected from the site <br /> . during the May 2000 sampling event <br /> Measurable free product was not encountered in any of the wells on the site Analytical results of <br /> ground water samples collected during the May 2000 monitoring event are summarized on Table 4 <br /> Analytical results of historical ground water samples are sunanarized on Tables 5 and 6 The <br /> laboratory report (MAI Laboratory I D Nos 38023A-38031) and chain-of-custody forms are <br /> included in Appendix D <br /> High concentrations of dissolved oxygen were observed in water samples from vapor wells MW-7, <br /> VW-1,and VW-3 during the June 2000 monitoring,the latter two wells also exhibiting ground water' <br /> mounding Dissolved oxygen dropped significantly in VW-2 and VW-5 The concentration of <br /> dissolved oxygen in ground water remained generally stable at the site relative to previous <br /> monitoring events Dissolved oxygen data are summarized on Table 7 <br /> 3 5 OPERATION OF SVE/IAS UNITS <br /> The SVE system operated at a capacity of approximately 270 cubic feet per minute (cftn) over the <br /> quarter The burner temperature was maintained near 650°F for catalytic operation The lower <br /> explosive lumt (LEL) of the intake vapor stream was approximately 4 to 6 percent <br /> Advanced GeoEnvironmentai,Inc <br />