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i 17 August 2004 AGE-NC Project No 01-0827 Page 2 of 6 I dissolved hydrocarbons in the deep ground water well samples at the site(VW-2D),but has reduced the dissolved hydrocarbon concentration in the shallow well samples (MW-1 and VW-1)as well as the concentrations of hydrocarbons In the soil vapor extraction (SVE) influent to below detection levels Subsequently, AGE had proposed to augment the IAS system with a low-flow ozone generator in the work plan dated 28 January 2003 Operation of the ozone Injection system has been ongoing since July 2003, resulting in a general downward concentration trend 2.0. PROCEDURES Field procedures for ground water sampling are described below All field work was performed in accordance with Central ValleyReglonal Water Quality Control Board(CVRWQCB)guidelines for the investigation of underground storage tank (UST) sites 2 1 OZONE SPARGE SYSTEM OPERATION The ozone-spargmg (OS) system has operated continuously since 01 July 2003, the system was lie monitored and serviced at regular intervals throughout the quarter The OS system consists of an ozone generator, which produces ozone-rich air at 10 standard cubic feet per minute (scfm) and a pressure of 20 pounds per square inch This ozone-rich air is delivered to the IAS wells IAS-1 through IAS-3 via a subsurface network of 3/a-inch polyethylene tubing Because the Injected ozone will eventually break down to dissolved oxygen(DO), a DO meter was utilized at each monitoring well during the monitoring events to determine the effectiveness of ozone sparging DO and/or oxidation/reduction potential(ORP)in ground water wells adjacent to the IAS wells were measured on 10 May, 10 June and 12 July 2004 Dissolved oxygen has increased moderately in ground water wells since remediation-system startup in July 2003, negative ORP values in the monitoring wells near ozone injection well IAS-1 suggest a reducing environment ' around the ozone discharge points (Appendix A) ' 2 2 QUARTERLY WELL MONITORING On 10 May and 10 June 2004,the depth to ground water was measured in monitoring wells MW-1, IMW-3,MW-4,MW-5,VW-2d and VW-5d,afterwards,well VW-2d was purged and sampled Well VW-2d also was monitored and sampled on 12 July 2004 I • Advanced CeoEnvironmentat,Inc I