WORK PLANS - Laserfiche WebLink

Home Browse Search

OUTLINE FOR OXYGEN DIFFUSER TREATMENT Treatment Description: The treatment is the application of a patented method developed at the University of Waterloo that uses oxygen diffusion to increase biological activity and the biodegradation of BTEX and MtBE in groundwater. It works as an in -well remediation system that forms an oxygen diffusion hallo around the treatment well. Details of the oxygen diffuser are presented in the patent attached to this outline. 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). SECOR will alter the design to increase oxygen dispersion around the well by placing an in -well low -flow pump at the bottom of the well. Water pumped from the bottom of the well, travels up the tubing placed in the well to the screened interval at the groundwater surface where it mounds and increases water flow out of the well into the surrounding sediments. The radius influence of the treatment is assumed to be 1.5 times the distance between the inlet and outlet point. Assuming a the pump is placed ten feet below the groundwater surface, the treatment radius can be approximately 10 to fifteen feet depending on the permeability. Based on evaluation of sediments in boring logs from the Site, the heterogeneity of sediments will likely limit the zone of influence to under 15 feet. In addition, the presence of elevated concentrations of BTEX has been shown in benchscale studies to decrease the efficiency of MtBE biodegradation. The most effective treatment of MtBE has been demonstrated in the field by researchers at the University of Waterloo. The researchers demonstrated that MtBE can be degraded under high oxygen conditions (>20 ppm) in a 2 mile long plume composed only of MtBE. The detailed description of the study is presented in the papers attached to this document. Proposed Treatment: 6 to 8 - 4" treatment wells spaced downgradient dispenser island from outside the western edge of the former tank cavity to the eastern edge of the cavity forming an oxygen permeable barrier to MtBE transport. Ideal spacing would be under 10 feet, to maintain high oxygen concentrations in the treatment area, significantly increasing the effectiveness of MTBE degradation, but generating a treatment system that would be cost prohibitive. 2 to 4 — 4" treatment wells within the tank cavity area to increase treatment in the source area. Wells will be treated with an oxygen diffusion device amended with an in -well pump. Well monitoring, oxygen canister replacement, pump O & M, and biofouling evaluation will be every two to four weeks. Well monitoring would be on a quarterly basis.