City of Hamilton City of Hamilton
Submit SearchSubmit Search
City of Hamilton – Public Works

Water Quality Program

Site Map   
Home Drinking Water Sewer Water Conservation / Education Rates Programs Reports and Plans Conatct Us

            Woodward Avenue Wastewater Treatment Plant

Executive Summary

The City of Hamilton currently owns and operates two wastewater treatment plants located at 35 King Street in Dundas and the largest one at 700 Woodward Avenue in the City’s east end. The Woodward plant is rated at an average daily capacity of 409 Million litres and has a peak wet weather capacity of 614 Million litres per day. The plant is classed as a conventional activated sludge facility providing secondary biological treatment.

The first process is the collection of sanitary and combined sewage into a wet well that is 23m deep and 12 m in diameter located at the main pumphouse. This influent (sanitary and combined sewage) is collected via two large interceptor sewers transporting wastewater from the City of Hamilton, including the former Town of Ancaster, the Township of Glanbrook, and the City of Stoney Creek.

The influent to the plant then undergoes Preliminary, Primary and Secondary treatment as follows:

Preliminary Treatment

As wastewater moves to the Headworks building Ferric Sulphate is added to aid in removal of phosphorus. This is the beginning of the preliminary treatment process which involves wastewater moving through screens to remove large floatable materials and coarse solids. It then flows through vortex separator devices which are designed to remove grit. The collected materials within preliminary treatment are transferred to large bins for disposal at a landfill site.

Primary Treatment

After preliminary treatment, wastewater enters one of 14 large settling tanks, called primary clarifiers. These tanks remove both floating material called scum and settled material called raw sludge. Scum is removed by skimmers and dewatered prior to being transported by truck for disposal at a landfill. Raw sludge that settles in the primary clarifiers is collected and pumped to the primary digesters where it is mixed with thickened waste activated sludge and anaerobically digested.


The secondary treatment process consists of 2 separate trains; one provides treatment for approximately 273 million litres per day (MLD), the second for approximately 136 MLD. Primary effluent enters the secondary treatment process and is mixed with air in large basins to encourage the growth of desirable micro-organisms. These microbes biologically treat the wastewater. This mixture is then conveyed to the secondary clarifiers where sludge and liquid are finally separated. The activated sludge that settles to the bottom of the secondary clarifier is divided into 2 streams known as Return Activated Sludge and Waste Activated Sludge. Return Activated Sludge is pumped back into the aeration basins by Archimedes screw pumps to maintain healthy populations of micro-organisms. The Return Activated Sludge rate is closely controlled to maintain adequate biomass in the aeration basins for treatment of material received from the collection system. Waste Activated Sludge is a separate stream that is pumped to 3 gravity belt thickeners where it is thickened and conveyed to primary anaerobic digesters for further treatment.

As part of the City’s Water and Wastewater Master Plan an upgrade and expansion project was proposed for the Woodward site to allow the City to respond to growth as identified in the Provincial Places to Grow legislation as well as improve the quality of treated effluent from the plant flowing to the environment. This work will address city targets identified in the Hamilton Harbour Remedial Action Plan (HHRAP).

Plans were adopted by City Council in support of this initiative and capital projects were placed into the capital budget forecast. Subsequent to this, staff with the help of local stakeholders, were successful in receiving an announcement for federal and provincial funding support for the capital work under the Green Infrastructure Fund (GIF). This announcement was made in March of 2010 and reflected a $200M financial contribution provided in equal parts from the provincial and federal governments based on completion timelines to 2014.

Over the course of the last few years a trend in reduced water consumption was developing as a result of a decline in the economy as well as the proliferation of water efficient fixtures being more available in the marketplace. A corresponding decline in flow to the wastewater treatment plant occurred over this same timeframe reducing the need to expand the facility to meet the needs of growth within the city. As a result, budgets for the project were deferred to the year 2019 which was not in keeping with the GIF funding announcement.

In November 2011, senior City staff met with Federal Green Infrastructure Fund (GIF) representatives to discuss options for a revised Agreement-in-Principle that would allow the Federal GIF contribution to proceed. This new approach divided the expansion into two phases on different timelines: 1) Water Quality Improvements and 2) Growth.

The below table shows the individual capital projects and Phase costs.

Phase 1 - Works in Progress
    Dewatering and Biogas Upgrades (Phase 1 Completed):
    Primary Clarifiers Upgrades (Project Ongoing):

Works in Progress:

$ 132.8 million

Phase 1 Clean Harbour Project (2012 to 2016)
    Tertiary Treatment
    Chlorine Tank, Outfall, 
    RHC Upgrade, Spur Line Relocation
    Power Upgrades
    Raw WW Pumping Station
    Collection System Control Upgrades

Total Clean Harbour Project:

$ 332.2 million

Total Phase 1

$ 465.0 million

Phase 2 - Plant Expansion (2017 to 2025)
    Tertiary Treatment
    Dewatering and Biogas Upgrades (Phase 2)
    Power Upgrades 

Total Woodward WWTP Growth:

$ 265.1 million

Note: Remaining program funds are Thermal Reduction which are being managed under Biosolids P3 Program

Expansion of the wastewater treatment plant for the growth component would be undertaken in the future at a time when demand monitoring indicates expanded capacity is needed. This is expected to be sometime between 2019 and 2025. The Water Quality Initiative agreed to by city council in 2012 reflects an upgrade with a target completion date in 2017. City Staff are working with the Federal government to confirm these changes within the GIF program. The resulting project is one of the largest undertakings necessary for the success of the Hamilton Harbour Remedial Action Plan effort to delist Hamilton Harbour as an area of concern.