Urban stormwater management

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What we face

Urban areas don’t soak up a lot of water. When fields and forests are replaced with roads, parking lots and buildings, less rainfall can seep into the ground, and more water collects on hard surfaces. Gravity then moves the runoff from those paved surfaces towards catch basins and into storm sewers.

What we do

Older areas

In neighbourhoods built prior to the 1980s, stormwater runoff does not typically receive any treatment. Contaminated with a lot of dirt and debris, stormwater runoff flows directly from the storm sewer into streams and rivers. There is little space in older urban areas to install large-scale stormwater facilities, like ponds, and parks can only compensate for so much.

The City has started exploring retrofit solutions to minimize the negative impact of uncontrolled runoff in Ottawa’s densely populated areas. Permeable parking lots, green streets, bioswales and rain gardens are only a few examples of stormwater infrastructure that can capture and filter runoff. The Pinecrest Creek/Westboro Stormwater Management Retrofit Plan contains a combination of measures to be implemented over the next 50 years in the Pinecrest/Westboro area.

Two engineered rain garden sites have already been constructed within the road right-of-way in Ottawa, one on Sunnyside Avenue in Old Ottawa South and one on Stewart Street in Sandy Hill. These retrofit projects allow runoff on an otherwise paved surface to infiltrate back into the ground. Hiding underneath the perennials and flowerbeds is a complex drainage system, monitored and maintained by City staff.

Newer areas

In neighbourhoods built in the 1980s and later, runoff is being collected in stormwater ponds that drain to a nearby waterway. The man-made ponds slow down the flow so that dirt and other pollutants can settle. Cleaner water leaves the ponds at a controlled rate, and there is less danger of flooding and erosion. These days, stormwater management infrastructure is required for every new suburban development.

Stormwater is the runoff that occurs when it rains or when snow and ice melts.

In natural areas, most rain soaks into the ground, with some slowly making it’s way to nearby creeks and rivers. Seems like a self-sufficient process, right?

Well, it’s not so simple in the city.

When natural land is covered by buildings, streets and parking lots, rain collects and pools against surfaces. It isn’t naturally absorbed.

The stormwater drains into city sewers that eventually lead it back to our streams and rivers through a network of pipes underground.

Unfortunately, stormwater runoff picks up all sorts of pollutants like dust and soil, litter, fertilizers, pesticides and auto fluids.

This can lead to problems, like poor water quality in creeks and rivers, increased flooding and erosion, fish habitat degradation and beach closures. But don’t worry, there’s a solution!

Since the 1980’s, stormwater management ponds have been built with all new developments to slow down and clean up the polluted runoff before it drains to local creeks and rivers.

The City of Ottawa has more than 2700km of storm sewers and over 100 stormwater management ponds.

Today we’re going to check out the Clarke Bellinger stormwater management pond.

This pond treats a large portion of Barrhaven’s stormwater, and it’s one of the biggest in Ottawa! Over the last few decades, sediment has built up on the bottom of the pond, so we need to clean it out.

The method being used to clean out this pond is called “dredging” and it will take several weeks to complete for each of the pond’s 2 cells.

This is a hydraulic dredger. It’s kind of like a big floating vacuum.

It moves slowly across the surface of the pond while sucking up sediment from the bottom through a large hose that leads to a Geotube.

Geotubes are very large bags made out of tightly woven material that holds sediment in while water leaks out, basically like a giant tea bag.

Once the Geotubes are full and the water has drained out, the sediment is removed and trucked away to a licensed landfill for disposal.

Regular maintenance of stormwater management ponds is important to ensure they continue to do their job.
Urban areas can really take a toll on local streams and rivers, and that’s why stormwater management ponds are here—to help protect them, and us!

Find more information about stormwater management at www.ottawa.ca