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ate, 06 August 2000 Er " AGE Project No. 95-0118 Page 4of5 The prevailing ground water flow direction is to the north with an average gradient of 0.007. Relative ground water elevation contours are depicted in Figure 3. - Elevated concentrations of dissolved oxygen in excess of 50% were detected in monitoring wells MW-2,MW-3 and MW-6. In the remaining wells, dissolved oxygen contents ranged between 20%- 30%. 3.4. ANALYTICAL RESULTS OF GROUND WATER SAMPLES `'- Water samples collected from the monitoring wells did not contain detectable concentrations of TPH-g or BTE&X. Analytical results of ground water samples are summarized in Table 2. The laboratory report (MAI Lab ID 31642 to 31647), Quality Assurance and Quality Control (QA/QC)report and a chain-of-custody form are included as Appendix D. 4.0. CONCLUSIONS Based upon results of ground water monitoring well sampling, AGE concludes: == The lowering of the water table ground by almost 3 feet is attributed to the seasonal fluctuation pattern from the wet to the dry season. The dissolved hydrocarbon concentrations have decreased to below detection limits. This i decrease is.attributed to the vapor extraction and air sparging activities at the site. Additional ground water sampling should be conducted to confirm the nature of the dissolved :1 hydrocarbon concentrations and evaluate the plume stability. • During the past six months of soil vapor extraction, an estimated 15 gallons of petroleum as =' gasoline have been extracted. TPH-g in the year 2000 has declined to concentrations that would not regture a destruction process of the recovered vapor stream according to the permit to operate the SVE. 5.0. RECOMMENDATIONS Based upon the results of the investigation, the recommendations are presented for your review: • Continue monitoring of ground water wells. Tthe next event scheduled for late August 2000. Advanced GeoEnvironmental,tic. _J