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tai G F= s. 04 February 2000 AGE Project No. 95-0118 - Page 4 of 7 3.0. FINDINGS Ground water elevations and flow direction were determined from field measurements,hydrocarbon ;. impact on ground water was assessed by laboratory analysis. 3.1. IN--SITU AIR SPARGING Elevated concentrations of dissolved oxygen were detected in monitoring wells MW-1,MW-2 and MW-3 on the site. Dissolved oxygen concentrations in the remaining wells, down gradient showed smaller changes (MW-5). The greatest changes in dissolved oxygen were observed in monitoring wells closer to the sparging well/point(MW-2). Sparging rates were measured at approximately 8 :i to 10 scfm during each monitoring event. A pressure of approximately 15 psi was maintained for the air sparging flow rate. 3.2. SOIL VAPOR EXTRACTION The SVE unit operated at an extraction flow rate that varied from 60 to 70 scfm. An induced vacuum s (negative pressure) of approximately 10 to 24 inches of water was measured in the piping between the blower and the extraction wells. The vacuum at the well-heads was observed in wells at.potential as high as 0.8 inches of water at vapor well VW-l. TPH-g was detected in the 15 September, 01 October, 01 November, 06 December 1999 and 03 January 2000 samples collected from influent vapor stream.at concentrations of 1,800 micrograms per liter (ug/l) 2,560pg/l, 2,690 ,ug/l, 1,040 /ig/l, 1,000 ,ug/1 and 2,3001ug/l respectively. The i analytical data for the set of vapor samples collected on 01 November 1999 appears to show that the influent and effluent samples were inadvertently mislabeled or switched. BTEX were detected at concentrations as high as 1,100gg/l of xylene on 15 September 1999. `I The analytical results are summarized on Table 3. The laboratory report (PET Sample Nos. PE5954- j 01-03,PE6080-01-02,PE 6331-01-02,PE6604-01-02 and MAI 28423-28424), Quality Assurance and Quality Control (QA/QC) reports and chain-of-custody forms are included in Appendix B. Concentrations of extracted volatile organics measured with the PID correspond only roughly to analytical results obtained from the influent stream samples. Measurements collected before the catalytic oxidizer and the effluent stream indicate that the rate of VOC destruction is poor. Measures to correct the destruction ratio of the IC unit are currently being determined and the correction action are being performed. Advanced GeoEnviron mental,Inc.