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grained aquarium gravel and #3 Monterey Sand was slowly poured down the annulus between the well casing and the inner wall of the hollow stem auger The filter pack was placed adjacent to the screened casing from the bottom of the boring to a point approximately two feet above the top of the screen Following filter pack placement, a surge block was inserted into the well casing and was alternately raised and lowered (surged)repeatedly for approximately 20 minutes to settle the filter pack material A nominal three-foot seal of bentonite pellets was placed above the filter pack and allowed to hydrate with clean tap water The remaining annular space was backfilled with portland cement INSTALLATION OF GROUND WATER EXTRACTION SYSTEM The ground water extraction system consisting of the ground water treatment unit and associated piping was installed between January and March 2002 A 1-inch diameter,schedule 40 PVC process piping and 3/4-inch diameter,schedule 80 PVC electrical piping conduit were installed in the on-site trench at approximately 18-inches bsg A manifold PVC piping system was utilized in the trench to connect the process piping system from each extraction wellhead to the groundwater treatment system 4-inch diameter,stainless steel model 5S 10 Grundfos Rediflow down-well pumps equipped with 230 volt Franklin %2-horsepower 3-wire motors were installed in ground water extraction wells EW-1, EW-2, EW-3, VW-6 The Grundfos pumps were installed in each well at a depth of approximately 30 feet bsg Electrical PumpTec controller boxes were installed In the electrical control panel for individual control measures of extractionwell pumps Pump controls are supplied by an amperage sensing/time control switch This switch will detect any decrease in amperage when water level drops below the impeller intake from any of the Grundfos pumps Three 2,000-gallon media vessels, one 1,000-gallon poly holding tank, one process pump and one sediment filter chamber were installed for the groundwater treatment system Groundwater pumped from the recovery wells is initially routed via the piping system to the 1,000-gallon holding tank prior to processing The process pump is designed to process ground water through the treatment system at a maximum flow rate of 20 gallons per minute(GPM) The ground water was routed to the three 2,000 pound vessels containing granular activated carbon (GAC) The GAC media vessels are designed to adsorb TPH-g and BTEX compounds Brass sampling ports were installed at the influent, between the media vessels and at the effluent to allow detection ofpotential media breakthrough and to obtain final discharge samples A F-2000 model RT Blue-White Industries flow meter was installed on the effluent line to continuously measure and display the effluent flow rate and to continuously measure and display the total flow GROUND WATER TREATMENT OPERATION AND MONITORING The ground water treatment system is designed to operate at a maximum flow rate of up to 15 gallons per minute(GPM), therefore each of the three recovery wells was adjusted to extract ground water at a flow rate of approximately 5 to 6 GPM by extracting on an intermitting cycle The operation of Advanced GeoEnvironmental,Inc