One of the City of Cornwall's largest responsibilities involves the collection and treatment of wastewater. This is accomplished through an extensive sewer network and a primary Wastewater Treatment Plant and pumping station on Montreal Road in the east end of the City.

The City of Cornwall strives to maintain high standards in wastewater treatment to ensure there is minimum effect on the St. Lawrence River.

Located at 2800 Montreal Road, the City of Cornwall Wastewater Treatment Plant was originally built in 1968, and the facility has undergone several expansions since that time. The treatment plant has undergone a $55.5-million upgrade resulting in the addition of secondary treatment and an increase in capacity. 

The existing plant currently serves approximately 46,000 residents as well as numerous commercial and industrial customers. It has an average rated capacity of 54,000 cubic metres per day and a peak design capacity of 108,000 cubic metres per day.

Sewage from the City of Cornwall is collected and transferred by gravity to a pumping station on the south side of Montreal Road, near the entrance to the Wastewater Treatment Plant.

The sewage passes through a screen at the pumping station before being pumped through a forcemain to the treatment plant, where grit is removed in aerated grit tanks. After degritting, the sewage is transferred to four clarifiers where it is disinfected using chlorine. The treated effluent is then discharged into the St. Lawrence River.

Solids that settle in the clarifiers are pumped to two digesters where organic matter is decomposed and methane is generated. This methane is used as a fuel for building heat. The decomposed organic matter is removed from the digesters, dewatered in centrifuges and landfilled for final disposal.

Wastewater Treatment Plant Upgrade


With a budget of $55.5 million, the upgrade of the Cornwall Wastewater Treatment Plant  is the largest construction project ever undertaken by the City of Cornwall.

The project consists of a series of upgrades to the existing plant, and the main objectives of these upgrades are:

  • upgrade the treatment process to include secondary treatment. This will allow the plant to meet higher effluent targets in accordance with Provincial and Federal policies and regulations.
  • increase the plant's overall capacity. This will support future growth and development of the City and it will also assist the City in managing potential Combined Sewer Overflows. 
 Existing Conditions
Located at 2800 Montreal Road, the Cornwall Wastewater Treatment Plant was originally built in 1968 and it has undergone several expansions since that time. The plant currently serves approximately 46,000 people and 

numerous commercial and industrial properties.

The plant currently has an average rated capacity of 54,000 cubic metres per day and a peak capacity of 108,000 cubic metres per day.

 Proposed Upgrades

The upgraded facility will have a peak capacity of 149,000 cubic metres per day.

The project consists of a number of upgrades to the existing Wastewater Treatment Plant and pumping station on Montreal Road. The scope of work is wide-ranging and includes new construction, renovation of existing facilities, earthworks, extensive concrete works, sub-contracting with preselected specialty equipment suppliers and the supply and installation of various instrumentation and control panels.

The major components of the project consist of:

  • General site works
  • Screening and degritting upgrades
  • Chemical system improvements
  • Primary clarifier upgrades
  • New secondary treatment (Biological Aerated Filter (BAF) technology)
  • New ultraviolet disinfection system
  • Solids train upgrades
  • Existing digester and dewatering facility improvements
  • New standby power system
  • Automation of entire facility
  • Electrical system upgrades
  • Pumping station upgrades

Work on the Wastewater Treatment Plant upgrade officially got underway in 2010 with the completion of a Class Environmental Assessment and the confirmation of funding from the senior levels of government. The Project Manager, Ontario Clean Water Agency, started work in early 2010 and in September 2010, the contract for the Consulting Engineering Firm was awarded to J.L. Richards and Associates in partnership with Ch2MHill.

The construction tender was awarded in March 2012 to a joint venture comprising the firms of Graham Construction and Engineering LP (by its general partner Graham Construction and Engineering Inc.) and Jardeg Construction Services Ltd.

 Project Benefits
There are a number of benefits from the project, including:
  • The upgrade of the Cornwall Wastewater Treatment Plant is a major outstanding action to de-list the St. Lawrence River at Cornwall as an Area of Concern (AOC). The upgrade to secondary treatment will meet various Federal and Provincial policies and agreements on water quality and address Ministry of Environment, Conservation and Parks' concerns with effluent quality.
  • The project will consider 'green' construction/building practices, use the latest treatment and monitoring technology and will be designed to meet stringent environmental requirements.
  • Methane gas from the digestion process at the Wastewater Treatment Plant is currently used as an energy source for building heating. Through the project, the City aims to maximize the re-use of methane gas as the digester capacity is increased.
  • Life cycle costing with a high priority given to energy and the environment will be applied to all applicable design decisions.
  • The protection of the St. Lawrence River will be a priority both during and after construction.
 Funding Partners

The Government of Canada is providing up to $18.5 million through the Green Infrastructure Fund toward eligible project costs, while the Province of Ontario is contributing $18.5 million.

The City of Cornwall will contribute the remaining project cost of $18.5 million. This amount is being funded through the Water and Sewer Budget. To date, the City has already set aside nearly $4 million in reserves to assist with its share of the project. The remaining portion will be funded through a combination of reserve contributions and long-term borrowing.

 Project History

A plant-wide evaluation was performed in 2003 to determine the requirements for upgrades to the plant.  As such a Schedule C Class Environmental Assessment (Class EA) was completed in 2005 and updated on January 29, 2010.

Click on the following links to view the various reports:

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Carl Goodwin
Division Manager, Environment
861 Second Street West, Box 877, Cornwall ON, K6H 5T9
Phone: 613-930-2787 ext. 2582
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