Cornwall sewage treatment plant expansion protects St. Lawrence

Aerial view of Cornwall Wastewater Treatment plant with new buildings in place. Image courtesy City of Cornwall.

A $55.5-million expansion to a wastewater treatment plant in Cornwall in eastern Ontario is the largest construction project that the city has ever undertaken.

The new treatment improves the effluent and will reduce the number of sewage discharges into the St. Lawrence River.

J.L. Richards and Associates were the consulting engineer on the project, which took two years. Secondary treatment was added with biological aerator filtration, along with ultraviolet disinfection. The sludge thickener was also upgraded and the plant’s overall capacity was expanded.

To house the new processes buildings were added on the existing site. The plant dates originally from 1968 and serves the entire population of 46,000 people in the city which lies between Kingston and Montreal on the St. Lawrence River. The plant last had a major expansion in 1985, but the latest changes have increased its capacity from 108,000 to 149,000 cubic metres per day.

The project was funded by all three levels of government. At an opening ceremony in November, Bob Kilger, the mayor of Cornwall, said: “The upgrade of the Cornwall Wastewater Treatment plant represents the largest construction project ever undertaken by the City of Cornwall. In addition to the numerous environmental benefits, this project also places Cornwall in a strong position for future growth and expansion.”