Protecting water quality - Stormwater management
Watershed Management
The City manages the watersheds within its boundaries by implementing a variety of controls. One such control is the control of the impact of its sewer systems on the terrestrial (land) and aquatic (water) environments.
Most of the former municipalities have developed strategies and have constructed sewer projects not only to better serve their residents, but also with environmental protection/preservation as a key objective. The preferred option for, and the design and implementation of all projects have followed and will continue to follow the Environmental Assessment process. To complement and to supplement the work previously done by the former municipalities, the City is developing the "Toronto Master Plan for Wet Weather Flow Management" to guide the management of wet weather flow on a watershed basis.
An example of a strategy and resultant projects carried out, or in the process of being carried out is the former City of Toronto's Sewer System Master Plan. Arising out of this plan are the completed Kenilworth Avenue and the MacLean Avenue detention tanks to protect the eastern beaches, and the Western Beaches Storage Tunnel (under construction) to protect the western beaches from bacterial pollution.
As an integral part of any strategy, the City employs not only proven technologies, but also new innovative ones. The following are examples of innovative technologies applied to our sewer system as pilot projects:
- In Etobicoke and Scarborough: Flow Balancing Stormwater Treatment Facilities, which uses an existing water body, e.g. a lake, pond or embankment for the storage and treatment of stormwater (Invented by Karl Dunkers of Sweden);
- In Scarborough: Vortex Separators a high rate treatment facility to treat combined sewer overflows;
- In Etobicoke: Infiltration sewer pipes to encourage stormwater to infiltrate into the ground as opposed to being discharged to a water body;
- In North York: The use of Oil-Grit Separators to remove oil and grit/sediment from stormwater on site before it is discharged into the sewer system.
Other controls include:
- A requirement for a stormwater management plan to control both water quality and quantity for all developments;
- A program to disconnect downspouts/roof leaders from the sewer system;
- A prohibition against the connection of new downspouts/roof leaders to the sewer system;
- Enforcement of the Sewers Bylaw.