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r ATTACHMENT B OVERVIEW OF OXYGEN DIFFUSION TREATMENT The treatment is the application of a patented method developed at the University of Waterloo by Drs. D. Mackay and R Wilson, that uses oxygen diffusion to increase biological activity and the biodegradation of TPH, BTEX, and MtBE in groundwater. It works as an in - well remediation system that forms an oxygen diffusion halo around the treatment well. Details of the oxygen diffuser are described in the attached patent (Attachment Q. The system uses sealed low density polyethylene (LDPE) tubing charged with 60 pounds per square inch (psi) of oxygen to diffuse oxygen into the treatment well at an equilibrium concentration of approximately 30 milligrams per liter (mg/L or ppm). The tubing is coiled around a cylinder that fits into a 2 or 4 -inch diameter well. Oxygen diffuses through the walls of the tubing into the water without bubbling or going into a separate phase. The oxygen is fed from an oxygen tank that fits inside a 4 -inch diameter well. The University of . Waterloo design will be altered to include a downhole low -flow pump that will increase the radius of influence of the dissolved oxygen to approximately 10 or 15 feet. Water pumped from the bottom of the well, travels up the well past coils of LDPE tubing up to the screened interval at the groundwater surface where it mounds and increases water flow out of the well into the surrounding sediments. The treatment radius of influence is assumed to be 1.5 times the distance between the inlet and outlet point. Assuming that the pump is placed ten feet below the groundwater surface, the treatment radius can be approximately 10 to 15 feet depending on the site lithology. An oxygen enrichment system was applied at a site with similar lithology and the resultant radius of influence reported for high oxygen was approximately 15 feet. The presence of elevated concentrations of TPH and BTEX has been shown in benchscale studies to decrease the efficiency of oxygen dispersion and decrease the efficiency of MtBE degradation. It is anticipated that the pump and treat system in the source area in addition to the vapor extraction system will increase both oxygenation and hydrocarbon removal. The result will be a lower oxygen demand in the treatment area around the oxygen diffusion wells and a higher effective radius of influence for treatment. •