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I locations, but are generally complicated, expensive to install and maintain, generate wastes, and consume substantial quantities of electricity and/or natural gas Enhanced bioremediation by the use of infected dissolved oxygen has been proven to be an effective technology to reduce both BTEX and MTBE However many ground water I environments that are high in ferrous iron and BOD, for example, will consume large volumes of injected dissolved oxygen before aerobic bacteria can utilize the oxygen as part of the process of consuming BTEX and MTBE Therefore delivery of super-saturated levels of dissolved oxygen ' into ground water is essential to insure that an abundance of oxygen will remain for the bioremediation of BTEX and MTBE IOxygen Infusion via iSOC Technology A growing number of remediation contractors in the US, Canada and Brazil are utilizing a ' Canadian technology called in-situ Submerged Oxygen Curtain (1SOC) that infuses oxygen, using a spargeless technique, into ground water via monitor wells The proprietary structured polymer used in iSOC provides large surface area for gas transfer into a 15 inch by 175 inch ' probe which is placed down a 2 or 4-inch monitor well The probe is connected to a regulated canister supply of industrial compressed oxygen secured within a remediation compound Oxygen infusion enriches the dissolved oxygen (DO) content of groundwater without causing ' aeration and volatilization of organic compounds Super saturation levels of oxygen can be achieved in the range of 40 to 50 milligrams per liter (mg/L or ppm) This technology requires no ' external power, with a minimum monthly exchange of oxygen canisters During this time, the continuous supply of oxygen infused into the ground water system is able to provide significant enhanced degradation of petroleum hydrocarbons, including BTEX and MTBE The dissolved ' oxygen is infused from the iSOC into the monitoring well at a typical rate of 15 to 20 cubic centimeters per minute The effective radius of influence of super-saturated ground water leaving the monitoring wells with the iSOC's is typically 10-15 feet Illustrations of equipment and a typical setup are shown in Appendix E The iSOC technology has been reported to remediate BTEX levels in excess of 100,000 ppb at 1 sites in Canada and Brazil In those countries MTBE is currently not being used in gasoline In the United States 1SOC technology is being used to remediate BTEX and both MTBE and TBA ' Although the 1SOC is most effective on sites with higher soil permeabilities, it has demonstrated success on sites with low permeability soils (i a clays and silts) However, the expected results would generally occur over a greater period of time than for the ideal project location The ' success of oxygen infusion also depends on the lack of liquid phase hydrocarbons (LPH), with the presence of dissolved phase concentrations of total VOC and MTBE LPHs have not been observed by Clearwater on the Barnes Trucking site The infusion system also requires the ' presence of a monitoring well network (2 inches in diameter or larger) that can be used for infusion and to monitor performance The system may be installed onsite within the existing • network of monitoring wells to treat the "source" area, or it may be used in a downgradient well ' ZB 178C Addendum to CAP 3 December 31, 2003