Sherbourne Common Stormwater Treatment Facility, Toronto, Ontario, Canada
Sherbourne's stormwater treatment facility is located in the Sherbourne Common waterfront park in Toronto, in the state of Ontario, Canada. The facility is built on a former industrial site which was redeveloped into public recreational space.
Construction of the facility was started in July 2009 and completed in July 2011. The total cost of the project, including preparation of the site, demolition, soil remediation, construction and installation of the facility equipment, was $30m. The project was developed by Waterfront Toronto.
The 1.5ha Sherbourne Common park and the waterfront promenade form the central part of the East Bayfront precinct redevelopment. The East Bayfront redevelopment project includes a one kilometre long waterfront promenade. It will have a ten metre wide granite mosaic promenade and 11m wide wooden boardwalk.
It will also include development of a nine metre wide pedestrian area between buildings and promenade. About 200 trees will be planted across the development. The park will serve the surrounding communities that are being developed with residential, educational, commercial and mixed-use facilities.
Need for the stormwater treatment facility
The area is prone to combined sewer overflow (CSO) during heavy rains, resulting in the microbial contamination of water supplied to the park.
Ultraviolet (UV) water disinfection was chosen to treat the runoff water to make it suitable for human contact in Lake Ontario.
The UV treatment process does not require any chemicals and also regulates the chlorine-resistant protozoa, such as Giardia and Cryptosporidium, to low levels.
The project is designed to meet the NWQMS Australian Guidelines for Water Recycling: Stormwater Harvesting and Reuse standards.
Design of the Sherbourne Common system
The stormwater management system is integrated into the public area infrastructure located in East Bayfront to enable pleasing aesthetics, cost efficiency, functionality and sustainability.
The project consists of lake water intake facilities, clean water discharge channels, Sherbourne park channel, UV facility and pumping station.
The stormwater treatment facility is located in the basement of the Pavilion of the Sherbourne Common park. The pumping station consists of divided wet wells with submersible pumps and associated valves and discharge pipelines. Discharging pipes are connected to a common discharge header at the upstream. The entire infrastructure, processing equipment and the UV units lie within the basement.
Trojan supplied and installed two TrojanUVFit reactors at the UV facility. The reactors have capacity to treat stormwater at a rate of 70L/s (1.6MGD) each. One of the two units is redundant and will be used when the duty UV unit is unavailable (100% redundancy). The facility has space for installing another reactor to bring the total treatment capacity to 140L/s, with 50% redundancy.
Water treatment processes
The City of Calgary officially unveiled its advanced Pine Creek Wastewater Treatment Plant (WWTP) in May 2010.
Stormwater runoff is collected in storage tanks located below the Boardwalk (West) Water's Edge Promenade, for initial treatment. These underground tanks provide sedimentation of suspended solids in the water.
The clarified water then flows through a large tank below the planned Parliament WaveDeck, which acts as an artificial wetland. Its platform has three holes for penetration of ultraviolet (UV) rays for treatment.
The water is then conveyed to the pumping station and UV facility of the Sherbourne Common park. The UV plant is installed with Trojan UV equipment which emits strong UV light to disinfect the water.
The treated water is then conveyed through a 240m long artificial water channel of the park which is accessible to the public. Three nine metre tall art sculptures cascade the treated water to allow its flow throughout the channel. These Light Showers combine lighting and water for aesthetics at the recreational park.
The cascaded water is collected from the park or drawn from the lake. The channel has biofiltration beds which further treat the water before discharging it into Lake Ontario.
UV technology used at Toronto's Sherbourne Common
TrojanUVFit closed-vessel UV disinfection system was installed at the facility.
It is a compact and energy-efficient reactor which allows treatment of water at different flow rates based on the configurations.
The reactors are equipped with automated wiping system to reduce the fouling of quartz sleeves that surround the UV lamps and increase its efficiency.
Each reactor system has a design flow of 70L/s or 1.6MGD. The ultraviolet transmittance is 52%. The E. Coli of the effluent is less than 10CFU/100mL; cryptosporidium is less than 0.32oocysts/L; giardia is less than 0.05cysts/L and rotavirus is less than 0.05PFU/L.
Contractors involved with the stormwater treatment facility
The stormwater management facility was designed by the Municipal Infrastructure Group. The company also provided engineering and contract administration services for the UV treatment system and pumping station.
West 8 and DTAH designed the public promenade and boardwalk. Eastern Construction was the construction manager. Somerville Construction and Aldershot Landscape Contractors were the landscape contractors. The City of Toronto Parks department operates the water treatment facility, Water's Edge Promenade and Boardwalk.