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i 12 January 2004 AGE-NC Project No 95-0143 ' Page 2 of 5 installed from approximately 25 to 20 5 feet bsg A nominal 2-foot bentonite plug was then installed above the filter pack The wells were then grouted to near the ground surface with portland cement ' A water-tight,traffic-rated well box was installed over the ozone sparge wells The well locations are shown on Figure 3 In-situ ozone sparge well construction is illustrated in Figure 4 I2 1 2 Ozone Distribution System Installation Following installation of the ozone sparge wells,trenches were dug from the ozone generator location to each well head for Installation 318-inch and 112-inch PVC tubing The tubing is utilized to distribute the ozone to individual wells Following installation of the tubing, the trenches were backfilled to surface grade A schematic diagram of the ozone distribution system is illustrated in Figure 3 2 1 3 Ozone Generator Installation To provide ozone for the in-situ ozone sparge system, AGE installed an ASI ozone generating unit lie The unit is rated by the manufacturer to produce 0 5 pounds of ozone per day The ozone generator is equipped with solenoid valves to control the distribution of ozone to each sparge well Ozone is cycled through each valve for one-hour intervals utilizing a computer controlled timer Based on the average sparging period per day perwell, approximately0 03 pounds of ozone is sparged at each well during a 24-hour period A calculation for ozone sparge rates is included in Appendix A 22 QUARTERLY WELL MONITORING PROCEDURLS IA quarterly ground water monitoring event was performed on 08 May 2003 The ground water monitoring was performed in accordance with the revised monitoring schedule established during a meeting with EHD staff on 25 September 2002 2 2 1 Well Monitoring and Purging A Sohnst water level meter was used to measure the depth to ground water in twelve monitoring wells at the site and in fifteen monitoring wells at the neighboring Madison site relative to the tops of the well casings The ground water elevations (Table 1) and hydraulic gradient (Figure 5) were Idetermined from these data . After measurement of depths to water,between 4 25 and 13 5 gallons of water(approximately three ' casing-water volumes)were purged from wells MW-3, MW-6, MW-7, MW-10, MW-14, MW-15, Advanced GeoEnvironmentai,Inc I