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_ 1 discharge to the 93 water carbon and recirculate (sprays) the remaining water back into the aeration tank. There should be no off gasses from the aeration tank, MtBE and TBA are highly water soluble and the gasoline range hydrocarbons (TPHg) and BTEX would have been already removed in the 91 and 42 water carbon units. If the aeration tank high- level float switch is activated a relay to the submersible pump controller turns off the well Pump (MW10). Pressure gauges are positioned at the influent to each water carbon unit to monitor that proper pressure guidelines are being met for each carbon canister (maximum 15 psig). The I" carbon unit has a pressure regulator that is set at 12 psig that once reached shuts off the well pump. Pressure gauges warn against fouling due to solids build-ups in the carbon. The treated water passes through the water carbon units into a 55-gallon dump tank that allows gravity flow discharge to the sewer clean out. An LEL monitor is positioned in the dump tank and will shut off any flow if the alarm is reached (10%). The LEL value is continuously chart recorded. A flow totalizing meter is positioned at the discharge of the dump tank prior to discharge to sewer and records the total gallons of treated groundwater that has been discharged to sewer. A high level float switch in the durnp tank will turn the recirculation pump off, if the water level approaches within 12 inches of the top of the dump tank, preventing overspill. The treatment system automatic responses to various contingencies are shown in Table I. Sample ports are positioned at the following: inlet to carbon unit #1 from well MW 10; inlet to carbon unit 42; inlet to aeration tank; inlet to carbon unit #3; inlet to carbon unit #4; inlet to carbon unit 45 and outlet of carbon unit 45. Samples are obtained between the #1 and 42 carbon units and analyzed for TPHg, BTEX and MTBE. If this sample shows any analytes, the water treatment system is turned off. The number one carbon is removed from the system, the #2 carbon is placed into the #1 position, the #3 carbon is placed into the #2 position, the 44 is placed into the 43 position, the #5 is placed into the #4 position. A new virgin carbon unit is delivered pre-conditioned and flooded. It is placed into the #5 position. The water treatment system is then restarted. Samples for TBA are obtained from influent of carbon unit 41, influent of carbon 43, influent of carbon #4 and influent of carbon 45. If TBA is found in the influent to carbon 45, the system is shut down and a carbon change out is ordered. Compliance TABLE I. RESONSE TO CONTINGENCIES CONTINGENCY .RESPONSE LOSE OF POWER TO ALL SYSTEMS SHUT OFF, NO DISCHARGE TREATMENT COMPOUND HIGH INFLUENT TURNS OFF PUMP AT WELL MW 10. MANUALLY PRESSURE AT INLET TO INSPECTED AND DETERMINED IF SYSTEM CARBON #1 SHOULD BE RESTARTED. HIGH WATER LEVEL IN TURNS OFF RECIRCULATION PUMP AT DUMP TANK AERATION TANK, PREVENTING OVERFLOW OF DUMP TANK. PUMPS WILL NOT TURN ON UNTIL WATER LEVEL HAS DROPPED BELOW HIGH LEVEL FLOAT SWITCH POSITION. 2 WATER TREATMENT modification May 2005