COMPLIANCE INFO_FILE 7 - Laserfiche WebLink

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installed to the base of the A-zone (approximately 25 feet) and screened from 10 feet bgs to 24.5 feet bgs. Each extraction well will be constructed of 4-inch-diameter, Schedule 40 PVC blank casing, and 4-inch-diameter, Schedule 40 PVC screen with 0.020 inch machine slots. The construction schematic for the plume margin ground water extraction wells is shown on Drawing C-5. Each margin extraction well will house a submersible, air-displacement type, bottom loading, ground water extraction pump. Each pump will have a 3-inch-diameter, fiberglass reinforced plastic body, with internal mechanical switches. Pump operation will be controlled by the internal switches and by the hydrostatic pressure of recharging ground water. During "off-cycle" of the pumps, ground water flows into the pump casing under hydrostatic pressure until it trips an internal mechanical switch whereby the compressed air supply is opened. The compressed air displaces ground water from within the pump casing and to above ground conveyance piping. Plume margin ground water extraction wells will be completed above ground surface within 24-inch-diameter stovepipes with concrete skirts. The wellhead assemblies for the extraction wells will include a connection to compressed air supply with a pressure regulator, a ground water sample port, a pump cycle counter, and flow control valves. Extraction System Process Piping Process piping for dual phase extraction wells will be 2-inch-diameter, schedule 40 PVC. This pipe diameter size is selected such that adequate velocity of the extracted vapor/liquid stream is maintained. SVE well process piping will be 2-inch-diameter Schedule 40 PVC, as this pipe size is adequate for expected soil vapor flowrates. Existing process piping will be utilized for transfer of ground water extracted at plume margin wells to the Treatment Svstem. Process piping layouts are shown in Drawings C-2 and C-3. 5-3