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. Is Free Product(FP) Present on Site No <br /> FP Recovered This Quarter NA <br /> Cumulative FP Recovered to Date NA <br /> Approximate Depth to Groundwater 42 57 to 43 40 feet below ground surface(bgs) <br /> Groundwater Flow Direction Northeast <br /> Groundwater Gradient 0 0038 ft/ft <br /> INTERIM REMEDIATION SYSTEM OPERATION AND PERFORMANCE <br /> Equipment Inventory Ozone Injection System Manufactured b KVA� <br /> Operating Mode Operational <br /> Reporting Period July.12, 2005 through September 30, 2005 <br /> Historical Highest GRO Concentration 55,000 gg/L (MW-6, 2002) <br /> Historical Highest Benzene Concentration __18,000 Vg/L(MW-8, 2001) _ <br /> Historical Highest MTBE Concentration 85,000 gg/L(MW-6, 2002) <br /> Highest GRO Concentration this Period 6 900 /L MW-8 <br /> Highest Benzene Concentration this Period 53 ug/L(MW-4) <br /> Highest MTBE Concentration this Period 9,500 req/L (MW-8) �- <br /> • Number of System Shutdowns This Period 0 <br /> DISCUSSION <br /> At the time of the third quarter 2005 monitoring event, groundwater elevations had decreased between <br /> 0 34 and 1 14 feet in all wells since the previous sampling event (June 8, 2005) Depth-to-water <br /> measurements were corrected to mean sea level (MSL) and used to construct a groundwater elevation <br /> contour map (Figure 3) Wells MW-9 and MW-10 are screened in a deeper portion of the water-bearing <br /> zone and were not used in contouring The groundwater flow direction was generally to the northeast at <br /> an average gradient of 0 0038 ft/ft Northeast groundwater flow has been the predominant flow direction <br /> observed at this site during previous quarters <br /> REMEDIATION SYSTEM STATUS <br /> System Description <br /> The C-SpargeTM system, manufactured by KVAe, consists of a control panel (ozone generator, air <br /> compressor, and tubing manifold), and strategically located injection points (IW-1 through IW-5, see <br /> Figure 2) used to inject low concentrations of ozone into groundwater In addition, the control panel also <br /> has a programmable timer that limits the amount of ozone injected into each injection point The system <br /> injects a timed pulse of ozone at low flows and low pressures (10-30 psi) to each of the five injection <br /> points in a sequence The ozone dissolved in groundwater is expected to oxidize petroleum hydrocarbons <br /> into carbon dioxide and water, and any un-reacted ozone will degrade to dissolved oxygen, which is likely <br /> to enhance natural biodegradation of residual petroleum hydrocarbons <br /> K ft-Arco for LJRS154691Quarterly120051Arco 5469_3Q05 docPage 3 of 6 3r9A716 <br />