In a pilot project by the City of Ottawa, permeable pavers have been used at the Carlingwood branch of the Ottawa Public Library, with local stream and river health in mind.
When regular pavers are used, rain water hits the pavement and flows off to the side in parking lots, collecting pollutants as it flows — going directly into a stormwater sewer, wrote the City of Ottawa in December’s climate change newsletter.
But when permeable pavers are used, this does not happen, explained the city.
Instead, water goes straight down through the spaces between pavers, into extra layers of gravel and soil beneath the surface.
While some will still end up in the storm sewer, this is after the majority of rainwater has been soaked up by the soil, they added.
According to Ottawa, this same process applies to melting snow.
“When it melts, it will follow the same path as rain. Less surface water means parking lots will dry faster and have less ice in general,” the city wrote in a news release.
A permeable surface means that less water goes into the storm sewer and it moves more slowly, reducing the risks of habitat degradation, flooding and erosion in creeks and rivers, added the city.
Rainwater management can work to reduce contaminants in local creeks and streams, resulting in a cleaner Ottawa River — our source for drinking water — and fewer beach closures during the summer months.
In urban centres, stormwater runs off into roadside ditches and storm sewers — ending up creeks, rivers and lakes, noted Ottawa.
Uncontrolled urban runoff can lead to increased flooding, erosion and can pollute bodies of water.
“Stormwater management aims to reduce these impacts by implementing measures that reduce, slow down and treat runoff,” they explained.
According to the City of Ottawa, the Carlingwood parking lot is the first permeable paver pilot project at a city facility.
“It’s part of the City’s overall effort to manage rainwater in older urban areas of the City that were built without stormwater management in a way that will reduce the risk of flooding and treat runoff,” they wrote.
In a statement from the city, other rainwater management projects in Ottawa include:
- The new Pinecrest Creek Stormwater Management Pond
- Rain gardens built along Sunnyside Avenue, Stewart Street and Hemmingwood Way
- A bioretention median at Dovercourt Community Centre, scheduled for construction in 2025
- Soil cells installed along Glebe Avenue at Bank Street that will support healthy urban trees while collecting and treating road runoff
- Rain Ready Ottawa, which offers rebates to residents who install rainwater management on their own properties
- The Combined Sewage Storage Tunnel
While it’s impossible to create infrastructure that will eliminate the risk of urban flooding, exploring rainwater management in Ottawa is critical as record rainfalls continue falling in a record amount of time.
“But, as we rebuild roads and City facilities, over time we can include ways to reduce the impact,” wrote the City of Ottawa.
In the Dovercourt Recreation Centre Proposed Parking Lot Reconstruction, the city has also proposed Stormwater Management retrofit measures, including a permeable paver surface. This project is currently underway.