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CLEARWA" T C." R U 11 -;,� Environ rnen luf Scrvrces 4.3 Groundwater Field Testing &Monitoring j<= On September 7th and 8th, 2004, Clearwater performed field testing and monitoring of groundwater I ' chemistry, and field tests for DO, ORP, total Fe, and ferrous Fe were performed on water samples collected from the twelve injection wells (IW-1 through IW-12), and from the eight monitoring wells (MW-1 through MW-8). DO and ORP are measured with pre-cleaned down-well probes. Iron testing is performed by collecting water samples and use of a field test kit. The results of these field measurements and tests are presented in Tables 4 and 5. Clearwater's field data collection forms are `.1 provided in Appendix C. 1n general, initial DO concentrations were in the range of 0.1 mg/L to 2 =� mg/L, and ORP levels were in the range of 0 mV to +35 mV. Total iron concentrations ranged between 0 mg/L and 4 mg/L. Ferrous iron concentrations ranged between 0 mg/L and 1.4 mg/L. 4.4 iSOC System Installation On August 7a', and 8`h, 2004, Clearwater installed an underground tubing network, which connects the oxygen supply to each of the twelve injection wells. Tubing was installed in narrow 124nch- i a :' deep (approx.) saw-cut trenches. A single iSOC diffuser was deployed in each well, and was connected to its individual 02 supply line. Each 02 supply line is connected to one of the four 3-way ==� control panels located in the gas supply/control cage, which is baited-down to the concrete pavement. ;<;=a The system consists of twelve diffusers, four control panels, and five 02 supply tanks. Based on the != =E manufacturer's recommendations, the system is operated at an oxygen flow rate of 15 cubic centimeters per minute (cc/min) and pressure of approximately 5 pounds per square inch (psi) per 1=:-1 = ! diffuser. Figure 7 illustrates the trenching layout, injection well locations, and equipment cage k location. a �.� �r ,�, _ s��. l .�� .,te 4.5 iSOC System Operations &Maintenance On September 24th, October 7th, and November 4th, 2004, Clearwater performed periodic system inspection and monitoring. Field monitoring for DO and ORP, and testing for total Fe, ferrous Fe, pH, and specific conductivity were performed on injection and monitoring wells. DO concentrations in the injection wells increased to within the range of approximately 20 mg/L to 35 mg/L (initial DO readings were within the range of 0.1 mg/L to 2 mg/L). ORP readings in the injection wells have generally decreased from readings in the range of 0 mV to +30 mV to the range of 0 mV to—30 mV. ZB178E iSOC System installation/Start-up 13 Nov.24,2004