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1 maintained through the air stripper to trunimize scale formation on the tower packing. Pump P9 and flow control valve FCV 1 have been selected to deliver a constant flow rate of 20 gpm to the iair stnpper The air stripper is designed conservatively, and even under severe operating conditions (air temperature 30 F, water temperature 60 F) it should remove at least 99.9 percent of the gasoline from the groundwater Water not recirculated back to tank T3 flows by gravity into holding tank T4 Pump P10 pumps the air stripper effluent from tank T4 through two activated carbon vessels (CV 1, CV2) plumbed in series. The carbon will be used to remove any detectable residual gaso- line remaining in the air stripper effluent so that a portion of the treated water may safely be reinfected into the uppermost saturated zone The effluent from the carbon absorbers is transferred to monitoring tank T5 The headspace of this tank is monitored for the percentage of the lower explosive limit (LEL) of gasoline If hydrocarbon vapors are detected above one percent of the LEL in this tank, a ball valve is ' automatically closed, and the entire groundwater extraction and treatment system is shut down to prevent untreated water from being discharged from the system Before fluid discharge, the treated water goes through sterilizer UV2 The entire system, including piping, hose, and equipment,uipment, will be secondarily contained Four- inch piping will be trenched from the recovery wells and reinfection wells to the base of the treatment system to act as ducting and secondary containment for the well pump hoses The treatment system itself will be placed on a bermed concrete pad The treatment area will be appropriately marked with the necessary Uniform Fire Code (UFC} and National Fire Protection Association (NFPA) approved hazardous materials storage signs t2.6 TASK V - SYSTEM STARTUP, OPERATION,MAINTENANCE, AND REPORT- ING ' After the treatment system is installed, the system will be brought online over a three-day period This startup will include the adjustment of the recovery pumps, measurement of water and air flows, and measurement of treated effluent quality. - After the treatment system is brought online, the influent and effluent will be sampled and ana- lyzed to ensure that treatment equipment is functioning properly and meeting discharge stand- ards. The extraction and treatment system operation and maintenance manual is provided as Appendix D The effects that the pumping and percolation system have on the aquifer will be closely monitored to ensure that the system is not overpumping and that the hydraulic barrier is sufficient to isolate the site hydraulically from any adjacent sites 06W-s6 n3%2rJ 191/m 16