Waterloo Emitters were installed starting in May 2004, in accordance with Ministry of Environment Certificate of Approval, at a food processing plant in Guelph, Ontario to remediate groundwater contaminated from leaking gasoline and chemical storage tanks. The contaminant plume containing BTEX and TPH occurs within shallow sands and gravels, silty tills, and underlying weathered dolostone to a depth of approximately 13 m. Numerical modeling was used to help determine the best locations for placement of Waterloo Emitters which would be used to diffuse oxygen into the contaminant plume to enhance the natural biodegradation of BTEX and TPH.
A total of 10 Emitters were installed inside 2 diameter overburden wells and 12 were installed inside 2 diameter bedrock wells. Emitters were connected to a bottled oxygen supply, which delivers oxygen at between 15-25 psi. At 20 psi, 1.8 Emitters using silicone tubing will release approximately 4.1 litres of oxygen per day to the aquifer.
As of November 2004, use of the Emitters had resulted in the following observations:
- Emitter wells averaged 12 mg/L of dissolved oxygen (43.0 mg/L max.), a 900% increase over concentrations prior to Emitter installation.
- The areal extent of the plume has decreased.
- Core plume concentrations of BTEX and TPH have decreased by 20% in the overburden aquifer and 39% in the bedrock aquifer.
The use of the Waterloo Emitter on this project has been determined to be very effective, and will continue toward full site remediation.