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04 September 2007 <br /> AGE NC Project No. 95-0121 <br /> Page 7 of 9 <br /> the potential for vapor recovery from the exposed saturated zone, after the de-watering of the DPE <br /> remediation well occurs. Additionally, ground water samples collected from well EW- 1 have been <br /> reported to be heavily impacted and the well is located near the former UST area. The test will <br /> include./a constant-flow rate, at the maximum vacuum allowable from the DPE system. Results <br /> from these tests will be used to establish the effective radius of influence, ground water draw down <br /> and to determine the optimum operating level of the extraction system. <br /> A 14nch diameter stinger will be placed into EW- 1 into the saturated zone to a depth of <br /> approximately 30 feet bsg. The well connection will be accomplished using a vacuum tight well seal <br /> and above ground hoses. The stinger will allow the extraction of impacted ground water and, after <br /> some period of system operation, may dry out the well and the surrounding soils to the corresponding <br /> depth. The stinger will be lowered within the well over time to enhance the drawdown. As the <br /> vacuum is applied to the extraction tube, a high velocity vapor stream is generated in the extraction <br /> stinger. The vapor stream entrains the impacted ground water and lifts the hydrocarbon vapor/water <br /> t a treatments stem. As the hydrocarbon-laden water travels u the extraction stinger, the majority <br /> o Y Y P g � J tY <br /> of the contaminants in the ground water are stripped into vapor phase by the high velocity vapor <br /> stream. Stripping efficiencies of>90% are possible; however, stripping efficiency is dependent upon <br /> site-specific variables, including vacuum, air/water ratios, contaminant concentrations and <br /> contaminant physical properties. Extracted vapors will be routed to the catalytic oxidizer with an <br /> intermediate "knock out' to trap excessive moisture contained with the vapors. <br /> Assuming the extraction system is successful in drawing EW-1 down to a depth of 30 feet bsg, there <br /> will be an exposed screen interval of 10 feet. Vapor extraction wells VW-1 and VW-2 are screened <br /> from 15 to 30 feet bsg, while vapor extraction wells VW-3 though VW-5 are screened from 5 to 20 <br /> feet bsg. These wells will be utilized to determine the radius of influence and ground water draw <br /> down. <br /> The well connection details are shown in Figure 6. Those fluids from the knock out and stinger pipes <br /> will be routed to the holding tank. From the holding tank, the wastewater will be pumped as required <br /> and recycled at an authorized facility under waste manifests. <br /> 3 .4. 1 . Field Measurements <br /> During the DPE pilot test the air flow will be monitored using a Dwyer DS-200 flow sensor. The <br /> flow rate will be determined from the measured differential pressure and the piping diameter using <br /> a nomograph. Flow rates will be measured and documented in standard cubic feet per minute (scfm), <br /> inches of water of differential pressure. Induced vacuum measurements will be recorded from the <br /> surrounding SVE wells utilizing Magnehelic gauges. The induced vacuum will be monitored for <br /> stabilization in units of inches of water and Hg (DPE unit) during the pilot test. Hydrocarbon <br /> Advanced GeoEnvironmental, Ina <br />