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' 15 January 2001 • AGE-NC Project No 96-0232 Page 6 of 20 On 23, 24 and 25 October 2000, a backhoe equipped with an 18-inch bucket was utilized to excavate soil in the above referenced trench-line to approximately 24-inches deep, additional trench- line was excavated in the landscaped area between wells EW-4 and EW-5 measuring 18-Inches deep by 18-inches wide Excavation cuttings were stockpiled in a northeast section of the site, and covered with plastic sheeting A map depicting the on-site trench system is depicted in Figure 11 5 2 UNDERGROUND PIPING INSTALLATION On 26 and 27 October 2000, 2-inch diameter, schedule 80 PVC piping (process piping) and I-inch diameter, schedule 80 PVC electrical piping (electrical conduit) were installed in the on-site trench- line at approximately I8-inches bsg A manifold PVC piping system was utilized in the trench-line to connect the process piping system from each extraction well head to the ground water pump and treat system From the ground water extraction pump, electrical wiring was routed through individual one-inch diameter PVC conduit through the trench-line to the pump and treat system electrical control panel Following placement of all PVC piping, the trench-line was backfilled with imported 3/8-inch pea gravel to 8-inches bsg The remaining space was resurfaced with concrete, a plan view 10 drawing of the piping network is depicted in Figure 11 1 5 3 GROUND WATER PUMP AND TREAT SYSTEM INSTALLATION Between 01 November and 10 November 2000, a ground water pump and treat system was installed at the site Prior to installation, a secondary containment(approximately 30 feel long by 15 feet wide) system was Installed inside the remediation system gated enclosure The secondary containment consisted of a 3-foot high wood berm and heavy duty polyethylene plastic liner attached to the floor Iand sides of the berm Four 1,000-gallon media vessels, one 1,000-gallon poly tank (holding tank), one process pump and one sediment filter chamber were installed for the ground water pump and treat system Initially, the influent piping was routed to a 1,000-gallon poly tank (holding tank) at the east-section of the gated enclosure to temporarily store extracted ground water prior to processing The holding tank was equipped with various water level float controls to control the rate at which extracted water was introduced into the treatment vessels, to allow coarser sediment to settle out prior to treatment and to provide safety shutoff capabilities A high float (high-high) was installed near the top of the holding tank and is designed to shut the entire system down if water level exceeds the high-high float A middle float{high-low)was installed near the middle of the holding tank and is designed to I turn on the process pump when water level exceeds the high-low float A low float was installed near the bottom of the holding tank (low-low) and is designed to turn off the process pump I Advanced GeoEnvuronmentai,Inc