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i 1 27 September 2007 AGE-NC Project No. 99-0682 �J Page 3 of 6 - 2. 1 .3 . Results of the Lower Vadose SVE Pilot Test The flow rate was measured between 40 standard cubic feet per minute (scfm) and 65 scfm for the 8-hour test. Influent organic vapor readings were greater than 10,000 parts per million (ppm). Induced vacuum measured at the extraction well (VW-1 ) was between 48 and 52 inches of water. The highest vacuum was measured at 0.30 inches of water in the upper vadose-screened observation 'I point approximately 9 feet southeast of the extraction well (VW-4). Vacuum measurements taken from the lower vadose-screened observation extraction well VW-3 were steady at 0.25 inches of water after the thirty minutes of pumping. Vacuum measurements recorded from the other observation wells (MW- lA, MW-3 , MW-4 and MW-5) ranged from 0 to 0.20 inches of water. Observation well MW-IA drilled within the UST excavation, southwest of extraction well VW- I , did not record any change in vacuum throughout the test. 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 radius of influence (ROI) was determined by drawing a best-fit line though these data points to correlate distance to vacuum data; the data from well MW- IA was not utilized in the correlation. At a vacuum of 0 .01 inches of water, the ROI is approximately 35 feet; at a vacuum of 0 . 10 inches of water, the ROI is approximately 24 feet. Based on the United States Environmental Protection Agency (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. � I 2.2. UPPER VADOSE SVE PILOT TEST I1 On 18 July 2007, an &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 test was conducted using the same procedures and SVE equipment used during the lower vadose pilot test on 17 July 2007. The pilot test was initiated at 0815 hr and continued for approximately 8 hours, at which time the test was terminated. An induced vacuum potential was applied to the casing of vapor well VW-2. The vacuum-induced pressure reduction was monitored at surrounding observation points (lower ! j vadose vapor extraction wells. VW- I and VW-3, upper vadose vapor well VW-4, and monitoring - wells MW- IA, MW-3 , MW-4 and MW-5 screened from 20 feet to 40 feetbsg) with air-tight well _ caps fitted to each observation well. �._. Advanced GeoEnvironmental, Inc.