Toronto’s Evergreen Brick Works is located in the floodplain of the Don River. What green design features help mitigate flood risk during severe weather?
During the revitalization of the Brick Works site, it was determined that an adaptive strategy to withstand severe weather events, especially flooding, was needed since the site absorbs water on a regular basis. The natural systems and cycles that define the local landscape offered cues for developing the following four green design features, which help divert excess water when flooding inevitably occurs.
1. Greenways and stormwater management ponds
Set between the site’s buildings, greenways have been planted with grasses and shrubs that slow down the flow of rainwater, trap sediment and release oxygen. Lined with a geotextile material, greenways prevent rainwater from seeping into and contaminating groundwater. They also clean the water and channel it into the stormwater management pond, which allows sediment within the water to be filtered before it’s released into the Don River.
2. Pervious concrete
Featured on the site’s eastern parking lot, pervious concrete contains less sand and up to 25 per cent more air than normal mixtures, making it more porous for absorbing rainwater and recharging the water table. Rainwater percolates through and into the soil, where it’s naturally filtered and helps replenish the groundwater supply.
3. Rainwater cisterns
Fifteen 20,000-litre cisterns are situated strategically around the site to minimize the amount of run-off from the buildings’ rooftops by collecting rainwater to store for other uses such as gardening and in toilets. During normal operations, waste from washrooms is pumped from a pumping station. In the event of a flood, the pumping station will shut down and be diverted to an emergency cistern.
4. Flood proofing
The concrete ground floor space is essentially waterproof, allows for minimal water damage and is mould-resistant. Major mechanical systems such as elevators are placed above the height of even the most severe flood levels.
Seana Irvine is chief operating officer (COO) of Evergreen, a national charity that makes cities more livable. She oversees Evergreen’s staff and volunteers, organization-wide operational planning and risk-management planning, policies and procedures.