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stormwater treatment system

New stormwater treatment and conveyance system will feature state-of-the-art technology in a beautifully designed facility.

Waterfront Toronto is constructing an innovative stormwater treatment and conveyance system to service the West Don Lands community and future development in the North Keating portion of the Lower Don Lands. The system will feature a new purpose built plant that will utilize the latest technology to treat stormwater.


West Don Lands and North Keating are located within the floodplain of the Don River and flood mitigation and stormwater management are critical issues that need to be addressed as part of revitalization.


As a former industrial area, the West Don Lands lacks appropriate stormwater infrastructure to support the influx of new residents that redevelopment will bring. Plus, construction of the area’s flood protection land form has rerouted stormwater flows away from the Don River, which previously received the bulk of the area’s stormwater.


Managing and treating stormwater – created by rain and melting snow – is critical to safely convey runoff, prevent flooding, and to ensure pollutants in the water are removed prior to the water being discharged into Lake Ontario.


The new system for the West Don Lands is an innovative approach to managing stormwater in the area. The state-of-the-art design addresses a number of constraints posed by its location within a dense, downtown urban setting and the use of the selected technologies in the multi-step treatment system is the first of its kind in Canada.


innovative treatment system


The innovative treatment system will achieve the stormwater treatment guidelines set out by the City of Toronto, as well as Waterfront Toronto’s broader commitment to protecting and enhancing the natural environment.


The system consists of a treatment plant, an oil grit separator, a series of strategically located underground shafts and tunnels, and a discharge outfall at the Keating Channel. Once captured, the stormwater will undergo several stages of treatment before being discharged into Lake Ontario.


The system was planned to maximize the extremely tight footprint of the site and reduce the need for above ground space for the plant equipment; and, at the same time to minimize the environmental effects and associated soil remediation efforts of construction.


The West Don Lands system will treat only stormwater, as opposed to treating combined sewer systems with stormwater overflows. Another unique feature of the system is the plant will use a combination of several adapted technologies as well as the main shaft as part of the treatment process.


The tunnel portion of the system was constructed by boring through bedrock deep beneath the soil, which minimizes intrusion in the area. Unlike traditional systems that fill in the shaft following construction, the West Don Lands system will reuse the tunnel construction shaft, built to launch the tunnel boring machine, as a storage facility to decrease flows to the stormwater treatment facility. This unique approach reduced the overall size of the system, thereby reducing both the cost to construct it and maintain it.


treatment process


In the first stage of treatment, stormwater is collected and conveyed to a hydro dynamic oil grit separator located on the east side of Cherry Street, just north of the rail line. The oil grit separator removes sediment, screens debris and separates oil from the stormwater. After leaving the oil grit separator, the stormwater is conveyed to a storage chamber to await the second stage of treatment.


The second stage removes any fine suspended solids not captured by the oil grit separator using ballasted flocculation. Ballasted flocculation is a process that introduces a substance that binds the material together to make it heavier. The weighted material then sinks to the bottom of the chamber where it is isolated from the clarified water. The treated water is then conveyed to the third and final stage of treatment where it is treated using ultraviolet (UV) disinfection.


In the final stage of treatment, UV disinfection uses radiation from UV light to disrupt any organisms/bacteria in the water to deactivate or prevent them from reproducing. Following UV disinfection, the treated water is discharged into Lake Ontario at the Keating Channel.


West Don Lands Class Environmental Assessment Master Plan Stormwater Quality Revision & East Bayfront Class Environmental Assessment Master Plan Stormwater Quality Revision


Waterfront Toronto and the City of Toronto initiated an Addendum to expand the treatment capacity of the West Don Lands Stormwater Quality Facility to accept flows from the East Bayfront and from the westerly portion of the North Keating area, update the stormwater treatment process and update the phasing of the implementation.


In order to facilitate these changes, Waterfront Toronto and the City of Toronto initiated Addendums to both the West Don Lands Class Environmental Assessment Master Plan and the East Bayfront Class Environmental Assessment Master Plan.



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treatment plant


The 300-square-metre treatment plant facility that is being built at the northeast corner of Lake Shore Boulevard and Cherry Street is intended to be a landmark structure for the West Don Lands. gh3, the architecture team, had to address the challenges of the site. The facility’s use and the project’s modest budget but still meet Waterfront Toronto’s requirements for design excellence. Their approach was to design a simple elegant building that brings a modern interpretation to the ancient story of water. The design of the facility enclosure comes from the idea of a stone well, inverted to be displayed as a sculptural form above ground. The building will be embellished by etchings on its surface that act as a system of rain channels running from roof to wall, to ground plane and shaft that represent the broader system of urban hydrology in which the structure is rooted.


The faceted, limestone–clad building will be surrounded by the same material, creating a composition that will be a striking counterpoint to the infrastructural complexity around it. Strategically placed glazed openings will be set within the facade to reveal glimpses of the building’s inner workings and become glowing highlights at night. While interior and exterior LED lighting will abstractly register information about the building’s performance to transparently and compellingly convey the workings of civil infrastructure sustaining a city for its inhabitants.


The building was honoured with a 2011 Award of Excellence by Canadian Architect magazine. One of only two national award programs devoted exclusively to architecture, the Awards of Excellence have recognized significant building projects in Canada on an annual basis since 1968. The awards honour buildings in the design stage. Jurors considered response to the building program, site, geographical and social context and evaluated physical organization, structure, materials and environmental features.

An image showing the construction of the Stormwater Facility


An aerial photo of the Stormwater Facility

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project status

Approved Budget:

quick facts

Location: Treatment plant and main shaft located at 480 Lake Shore Boulevard East


Design Team: R.V. Anderson Associates Limited, Conestoga-Rovers & Associates, and gh3


Construction Teams: Graham Construction and Eastern Construction Co. Ltd.


Treatment plant size: housed in a 279-square-metre (3,000 square foot) building.


Tunnel and shafts:

The main shaft is 25 metres (82 feet) deep and can store approximately 3,000 cubic metres (106,000 cubic feet) of water.
The concrete-lined tunnel is three metres (10 feet) in diameter, 350 metres (1,150 feet) long, and 25-metres (82 feet) deep.
The tunnel was constructed deep in bedrock using a tunnel boring machine.


Oil Grit Separator:

Twin treatment chambers and a total treatment capacity of 385 gallons of water per second (1.75 cubic metres per second)
The structure is approximately 95 square metres (1,023 square feet), and 12 metres (39 feet) deep.


Project Status: The treatment plant is under construction.


The original project scope was for a storm water management facility at 480 Lake Shore Blvd to receive storm runoff and to treat stormwater from the West Don Lands area. It was decided to combine the West Don Lands and East Bayfront stormwater systems, which required opening and amending the related Environmental Assessments. The amendments were completed and the West Don Lands system will be expanded to accommodate flows for both areas – West Don Lands and East Bayfront.


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