Wastewater Systems

The City of Hamilton collects and treats both sanitary and combined sewage from the large underground wastewater collection sewer system. The City owns and operates two wastewater treatment plants; Woodward Avenue Wastewater Treatment Plant and Dundas Wastewater Treatment Plant.

Wastewater collection

Hamilton’s wastewater collection system includes:

This collection system services the city of Hamilton including:

Combined sewer overflow tanks were added to the system to reduce the number of combined sewer overflows to the local receiving waters. These tanks capture and store excess combined sewage during rainstorms and later send it to the Woodward Avenue Treatment Plant for treatment after the storm.

Wastewater treatment

Woodward Avenue Wastewater Treatment Plant

The Woodward Avenue Wastewater Treatment Plant has an average daily capacity of 409 million litres. The facility is a conventional activated sludge plant with tertiary filtration and anerobic sludge digestion. There are six wastewater treatment processes used at this plant, including:

The Woodward Avenue Wastewater Treatment Plant digester complex treats

• primary treatment sludge

• thickened secondary activated sludge

This complex has three primary and one secondary anaerobic digesters in operation. The digestion process uses a heated biological process to reduce the volume of organic matter and destroy pathogens. This process produces methane gas and biosolids. The methane gas is used as a fuel or converted into electricity. The treated biosolids, after being conditioned, are approved for use on agricultural land.

Treatment process diagram(PDF, 207.43 KB)

Dundas Wastewater Treatment Plant

The Dundas Wastewater Treatment Plant has an average daily capacity of 18.2 million litres. The facility is a conventional activated sludge plant with tertiary filtration. There are five wastewater treatment processes used at this Plant, including:

Biosolids are stored on site in covered holding tanks until they are transported to the Woodward Avenue Treatment Plant for further processing.

Wastewater Facilities Annual Report

The City of Hamilton owns and operates the Woodward Avenue Wastewater Treatment Plant and Dundas Wastewater Treatment Plant, as well as an extensive wastewater collection system that conveys both sanitary and combined sewage to these facilities. 

The City operates 71 sewage pumping stations and nine combined sewer overflow tank facilities. It is required to report on the performance of 21 facilities in accordance with Environmental Compliance Approval (ECA) requirements. The 2025 Wastewater Facilities Annual Report provides an overview of the performance of these treatment plants and the associated facilities within the Collection System as per the requirements of the ECA’s. 

This report provides the following requirements but is not limited to the: 

• Summary and interpretation of all monitoring data including an overview of the success and adequacy of the Works
• Description of any operating problems encountered, and corrective actions taken
• Summary of all normal and emergency repairs and maintenance activities carried out on any major structure and equipment
• Summary of all Bypasses, Overflows, other situations outside Normal Operating Conditions including spills
• Changes or updates to the schedule for the completion of construction and commissioning operation of major process(es) / equipment

2025 Wastewater Facilities Annual Report(PDF, 2.1 MB)

Biosolids Management

The Biosolids Master Plan provides direction for managing biosolids generated from the City’s wastewater treatment plants. Currently all of the biosolids are processed through the Woodward Avenue Wastewater Treatment Plant. The new Biosolids Management process uses thermal drying system which takes the nutrient-rich organic materials that result from the wastewater treatment process and turn them into pellets to be sold for fertilizer or fuel.

Electricity production from wastewater

Hamilton is the first municipality in Ontario to be accepted to build a generator for sustainable green energy by the Ontario Electricity Financial Corporation. It is also the only wastewater biogas co-generation plant in Ontario with a 20 year contract to sell electricity to the Ontario Power Authority. The project is one of the most innovative, large-scale examples of biogas co-generation in Canada.

This facility aims to:

• Produce clean renewable electricity from a waste product
• Reduce greenhouse gas, or GHG, emission to the atmosphere
• Increase energy efficiency of the facility
• Generate revenue and reduce operating costs for the existing wastewater treatment plant by producing electricity and utilizing waste heat to offset natural gas usage