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20 March 2006 AGE-NC Project No . 03- 1071 Page 11 of 13 4.4, RESULTS OF SVE PILOT TEST The SVE unit was operated at approximately 2,500 RPMs for the eight-hour test. The flow rate was measured between 30 scfm (standard cubic feet per minute) and 36 scfm for the eight-hour test. OV readings ranged from 1158 to 1401 ppm. Induced vacuum measured at the extraction well (V W-3) was a constant 94 inches of water. As expected, the greatest vacuum was measured in the observation point nearest the extraction well (VW-4). The lowest vacuum was measured in MW-2, approximately 33 feet north of the extraction point. The maximum vacuum measured at the observation points during the pilot test was plotted versus the distance from the extraction well. The effective radius of influence was determined by drawing a best-fit line though these data points to correlate distance to vacuum data. At a vacuum potential of 0. 10 inches of water, the radius of influence is approximately 28 feet; at an induced vacuum potential of 1 .0 inches of water, the radius of influence is approximately 18 .3 feet; at 10.0 inches of water the radius of influence is approximately 8 .7 feet. Based on the United States Environmental Protection Agency (EPA)-prepared document, How to Evaluate Alternative Cleanup Technologies For UST sites the radius of influence 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 an effective vacuum potential of 0. 1 inches of water, the calculated effective radius of influence at the site will be approximately 28 feet. Figure 5 depicts the effective radius of influence. 5.0. SUMMARY The implications from the August 2005 well installations, aquifer ground water pumping test, and SVE pilot test are as follows: • On 16 and 17 August 2005 , four vapor extraction wells (VW- 1 through VW-4) and one ground water extraction well (EW- 1 ) were installed at the site for performance of a ground water pumping test and SVE pilot test. • Generally, orange brown, dry to moist, silt, clayey silt, and silty clay was encountered between 5 and 20 feet bsg. Layers of hydrocarbon-stained poorly graded fine to medium grained sand, or silty sand, were usually encountered at various depths between 20 and 30 feet bsg. Hydrocarbon-stained sandy silt, silt, clay, or clayey silt was encountered between 25 and 35 feet bsg. Hydrocarbon-stained, saturated silty sand to sand (fine to coarse grained, poorly graded) was encountered between 35 and 55 feet bsg in pilot boring EW- I . • A total of twelve soil samples from the five pilot borings were submitted to a DHS-certified laboratory for analysis ofTPH-g, BTEX, MTBE, TAME, DIPE, ETRE, TBA, 1 ,2-DCA, and EDB. TPH-g was detected in all analyzed samples from EW- I at concentrations between I k jAdvanced GeoEnvironmental, Inc. r f l