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blank casing, and 4-inch-diameter, Schedule 40 PVC screen with 0.020 inch <br /> machine slots, as shown in Drawing C-5. <br /> A 1-inch-diameter, Schedule 40 PVC extraction tube will be placed in each <br /> extraction well. As shown in Drawing M-2, each extraction tube will be <br /> 9 feet in length and will be designed to allow for approximately 2.5 feet of <br /> vertical adjustment in the positioning of the extraction tube within the <br /> extraction well. The extracted vapor/liquid stream will be extracted <br /> through the extraction tube and through subsurface piping to the <br /> Treatment System. <br /> Each dual phase extraction well will be completed at the ground surface <br /> within traffic rated (H-20 loading) concrete vault boxes. Each extraction <br /> tube will be connected to subsurface process piping with 1 inch flexible <br /> PVC vacuum hose, rated to withstand the extraction vacuum of 20 inches <br /> Hg. Flexible hose is utilized to facilitate extraction tube positioning and <br /> dissipate vibrations associated with water hammer resulting from the <br /> high extraction velocity of ground water droplets in the extraction tube. <br /> Each dual phase extraction well head will include an air dilution valve, a <br /> ground water and soil vapor sample port, and a vacuum gauge. <br /> Soil Vapor Extraction Wells <br /> Three SVE wells (HVEX-09 through HVEX-11) will be installed at the <br /> locations shown in Drawing C-3. SVE wells will be screened from 5 feet <br /> above the water table to the water table surface (approximately 10 feet <br /> bgs). SVE wells will be constructed of 2-inch-diameter, Schedule 40 PVC <br /> blank casing, and 2-inch-diameter, Schedule 40 PVC screen with 0.020 inch <br /> machine slots. The construction schematic for the SVE wells is shown on <br /> Drawing C-5. <br /> All three SVE wells will be completed at the ground surface within traffic <br /> rated (H-20 loading) concrete vault boxes. The wellhead assemblies for <br /> SVE wells will include a vacuum gauge, soil vapor sample ports, and flow <br /> control valves. A construction schematic for the SVE wellhead assemblies <br /> is shown in Drawing M-2. <br /> Plume Margin Ground Water Extraction Wells <br /> Five 4-inch-diameter ground water extraction wells (EWP-17 through 21) <br /> will be installed at the northern edge of the plume margin, as shown on <br /> Drawing F-1. Each plume margin ground water extraction well will be <br /> 5-2 <br />