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J M f 27 September 2007 AGE-NC Project No. 99-0682 Page 5 of 6 The maximum vacuum measured at the observation points during the pilot test was plotted versus the distance from the extraction well (Appendix C).The theoretical ROI was determined by drawing a best-fit line though these data points to correlate distance to vacuum data; the data from well MW- 1 A was not utilized in the correlation. At a vacuum of 0.01 inches of water, the ROI is approximately 34 feet; at a vacuum of 0. 10 inches of water, the ROI is approximately 24 feet. Based on the EPA. prepared document, How to Evaluate Alternative Cleanup Technologies For UST Sites, the ROI is considered to be the distance from the extraction well at which a vacuum of at least 0 . 1 inches of { water is observed. Based upon a vacuum of 0. 1 inches of water, the extrapolated ROI at the site will be approximately 24 feet. Figure 3 depicts the ROI. l 3.0. SUMMARY AND CONCLUSIONS - 1 The implications of the SVE pilot tests are as follows : • On 17 July 2007, an 8-hour SVE pilot test was conducted at the site using lower vadose- screened vapor well VW- 1 , screened from 20 feet to 30 feet bsg, as the extraction well. The pilot test was initiated at 0900 hr and continued for approximately 8 hours, at which time the test was terminated. The flow rate was measured between 40 and 65 scfin for the &hour test. ` J Influent organic vapor readings were over the value of 10,000 ppm and induced vacuum measured at the extraction well was between 48 and 52 inches of water. I Based upon a vacuum of 0. 1 inches of water, the projected ROI of lower vadose SVE at the site will be approximately 24 feet (Figure 3 ; Appendix C) . TPH-g was detected in the influent vapor samples at concentrations ranging from 69,000 µg/1 to 90,000 µg/1. Toluene, ethylbenzene and total xylenes were detected in the vapor samples I at concentrations as high as 2,300 µg/l, 1 ,800 µg/1 and 5 ,800 µg/1, respectively. MTBE and J benzene were not detected at or above the laboratory detection limits in all the samples analyzed. Constituents of concern were not detected in the effluent vapor sample collected at 1658 hr on 17 July 2007. On 18 July 2007, an 8-hour SVE pilot test was conducted at the site using upper vadose- screened vapor well VW-2, screened from 10 feet to 20 feet bsg, as the extraction well. The pilot test was initiated at 0815 hr and continued for approximately 8 hours, at which time the test was terminated. The flow rate was measured between 40 and 45 scfm for the 8-hour test. Influent organic vapor readings ranged between 560 ppm and 974 ppm and induced vacuum measured at the extraction well was between 50 and 54 inches of water. Based upon a vacuum of 0. 1 inches of water, the projected ROI of upper vadose SVE at the I ll site will be approximately 24 feet (Figure 3 ; Appendix Q. 1-1 Advanced GeoEnvironmental, Inc.