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• apart near the property limits and that pumping rates will range from 0.1 to 1 gpm per well. The proposed extraction pump is a controller-less air-powered pump that is activated only when the pump's internal float rises as sufficient water fills the pump, at which point air pressure drives the water out of the pump through the discharge line. The float then drops down and shuts off the air supply, allowing the pump to refill. Since it is likely that some wells will produce more water than others, extraction pumps capable of pumping up to about 4 gpm were assumed in the extraction system design. The pump design is an AP4 Hammerhead stainless steel pump. The pump system assumes a 3-tube hose system (%-inch discharge line and 3/8-inch air supply line, %-inch air exhaust), support rope, stainless steel fittings, vacuum well seal, and cycle counter(flowmeter). All extraction wells were assumed to be constructed using 4-inch diameter PVC well casing and well screen. The well screen within the Corcoran Clay aquifer was estimated to extend through the saturated zone to the base of the aquifer. At each of the lines of extraction, an air compressor, sized to 24 horsepower, was assumed to provide an estimated 7.5 horsepower to operate the pumps. The air and groundwater discharge lines will be hard- plumbed underground along the series of extraction wells. Pumped groundwater will then be conveyed to an aboveground treatment system that is unique for each remedial alternative. Effluent Disposal. Following treatment, it is assumed that the treated groundwater can be discharged to the stormwater retention basin at the southwestern corner of the site. Once in the basin, treated groundwater will slowly infiltrate the ground, providing local recharge to the deep regional aquifer. 4.5.2 Alternative No. 5A-Groundwater Extraction - Passive Air Stripper The first of the two ex-situ treatment option to be considered involves the use of passive air- stripping technology to remove VOCs from the extracted groundwater. The air stripper treatment alternative includes the following components: • Influent equalization tank (included with groundwater extraction systems). • Influent transfer pump. • Filtration systems. • A corrugated high-density polyethylene pipe air stripper channel. • pH control unit. 40 Engineering Feasibility Study Geo-Logic Page ■ 26 Corral Hollow Sanitary Landfill A S S O C I AT E S January 25,2013