The City of Toronto has been preparing contingency measures to address the effects of climate change in the coming years and one project that they proposed focuses on managing excess wastewater, particularly during storm surges.
The City’s officials launched a storm water management program called the Don River and Central Waterfront and Connected Project which aims to restrict the sewage outflow into Lake Ontario and improve the waterways when storm surges occur.
The project will come in 5 phases which will cost around $3 billion to complete. The first phase is the Coxwell Bypass Tunnel which is a 10.5 kilometre long and 6.3 metre wide tunnel that will cost an estimated $400 million.
Toronto’s Mayor John Tory said that “when a major storm hits our city… and dumps huge quantities of rainwater onto the city, the wastewater system goes into overdrive to prevent major flooding. As the water rushes in, the system pushes wastewater overflows into the rivers and into Lake Ontario when it reaches a certain threshold.”
The International Joint Commission identified Toronto’s waterfront as one of the 43 polluted areas of concern in the Great Lakes basin, with the Don River and inner harbour being particularly polluted by combined sewer outflows.
Plans to address the pollution of Lake Ontario were already drawn up by previous administrations over the years and proposed that by 2038, they would cut wastewater pollution of the lake to close to zero. Tory believed that this was too long, and he proposed to make this into a reality in about half the time.
Once complete, the Don River and Central Waterfront Tunnel System is expected to include a 22-kilometre tunnel system composed of three integrated tunnels, 12 wet weather flow storage shafts along the tunnels, 12 connection points to the tunnels for storm water and combined sewer overflows, seven offline storage tanks and the technology necessary to regulate the flows, especially during storm surges, inside the city’s sewer system.
“Once this work is complete, it will capture and store combined water-sewer outflows during significant rainfall,” Tory said. The combined sewer overflows will then be pumped to the Ashbridges Bay Wastewater Treatment Plant for ultraviolet disinfection. A new high-rate treatment facility will be built at Ashbridges Bay to accommodate the excessive flows during heavy rains.
“While we’re continuing to urge the federal and provincial governments to partner with is in this crucial environmental initiative, we’re not waiting to get going,” Tory said.
By completing the project, the city will then be able to improve the aquatic habitat for fish and other wildlife, support the revitalization efforts along the central waterfront, provide greater opportunities for residents and visitors to enjoy water activities, and enhance the overall water quality of one of the world’s largest freshwater lakes.
Tory believes that “It is a core responsibility that we have for our generation, but also for the next generation to stop dumping raw sewage into Lake Ontario and into the waterways that flow into it. We now know that in a post climate change world, these storms unfortunately are a part of life that is going to happen for some time to come and we just can’t allow the status quo to prevail.”
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