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Site Background Information: Bob's Muffler Page 5 of 5 Significant petroleum-hydrocarbon impact to soil in the vadose zone is present in borings B2-20.25, ' 134-20,MW2-25,and MW4-20,in the area of the former USTs and in off-site well MW9-20.TPH-g, TPH-d, and TPH-mo are present at maximum concentrations of 670 mg/kg(132-20.25), 150 mg/kg (MW9-20), and 120 mg/kg (132-20.25), respectively. Most of the contamination appears to reside ' at the top of the clay layer, at approximately 20 feet bsg. ' Soil Vapor Extraction(SVE) Pilot Test On 01 April 2005 one soil boring was advanced at the site for the collection of soil samples and the ' installation of one SVE well(VW-1).Pilot boring VW 1 was completed as an SVE well using 2-inch diameter PVC casing with a 0.020-inch slotted screen installed from approximately 11 to 21 feet bsg. ' On 16 September 2005, AGE conducted a SVE pilot test. The SVE unit operated for eight hours at an engine speed of 1,950 to 2,375 revolutions per minute, inducing a vacuum at the extraction well of between 28 and 30 inches of water. The gas flow rate was measured at between 70 and 72 scfm ' (standard cubic feet per minute), and OV readings detected hydrocarbons at concentrations of between 78 and 162 ppm. The highest vacuum measured at the observation wells was at well MW-5, located approximately 7 feet from extraction well VW-1. The lowest vacuum was measured in MW-2, located approximately 67 feet from well VW-1_ AGE determined the effective SVE radius of influence by plotting the maximum vacuum measured ' at the observation wells during pilot testing versus the distance from the extraction well on a logarithmic scale;the effective radius of influence was determined by drawing a best-fit line though these data points. At a vacuum potential of 0.10 inches of water, the radius of influence is ' approximately 80 feet;at an induced vacuum potential of 1.0 inches of water,the radius of influence is approximately 35 feet; at 5.0 inches of water the radius of influence is less than Hoot. ' No constituents of concern were detected in the four air samples collected from well VW-1 during the 8-hour SVE pilot test. 1 I I I Advanced GeoEnviron mental,Inc.