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. 25 January 2001 AGE-NC Project No 99-0559 Page 5 of 14 42 TREATMENT SYSTEM DESIGN AGE proposes the use of a closed-loop, three-chamber air stripper to address TPH-g, BTEX and MTBE, and a 1,000-pound granular activated carbon (GAC) absorption vessel to ensure treatment of MTBE in the extracted ground water Prior to chemical processing, extracted ground water will be routed into a 750-gallon poly holding tank used to store extracted water and sediment This tank is equipped with upper and lower level control switches that serve to control the rate at which extracted water is introduced into the closed- loop air stripper to provide safety shutoff capabilities and to allow coarse sediment to settle out prior to treatment An emergency shut-off switch will be located Immediately below the top of the raw holding tank A "low" float control switch will be placed approximately 8 inches above the base of the holding tank to activate the process pump, located within the holding tank The raw water will pass through to the closed-loop air stripper The closed-loop air stripper circulates water through a series of aeration chambers Diffusers within each chamber release air bubbles providing an air-to-water interface that facilitates volatile hydrocarbon removal from the water to the bubbled air The air exhaust system of the air-stripper is designed to remove volatilized hydrocarbons through carbon adsorption Two 55-gallon capacity vapor vessels or the equivalent will receive the exhaust from the air-stripper The second stage of treatment media will consist of a 1 000-pound GAC absorption vessel The GAC vessel is designed to adsorb TPH-g, volatile organic compounds (VOCs) and MTBE The estimated ground water extraction flow rate will be between two and four GPM AGE anticipates the total ground water extraction flow rate to be four GPM from the individual well, therefore active ground water extraction may need to be alternated between wells to control the volume of produced water Sample collection ports will be located in appropriate positions downstream of the air-stripper, the GAC vessel and the air-stripper exhaust to allow raw water sampling to detect potential process break through and to obtain final discharge samples Electricity is readily available to the site, a dedicated electricity meter will be installed by representatives of AGE, that will connect directly to the pump and treat system The location of the ground water pump and treat system is proposed to be at the east corner of the site (Figure 4) The proposed location of the pump and treat system will allow the site to conduct day-to-day business without interference by operation of the remediation system The pump and treat system will be secured in a chain-linked, gated enclosure approximately 15 feet wide, 15 feet long and six feet high A generalized design of the treatment system is depicted in Figure 4 • Aduntc�rt GcaLnvironmcntal,Inc