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These tiny green islands are designed to help Toronto's aging stormwater system

The University of Toronto Scarborough uses bioswales, specifically engineered feats of landscape architecture, to manage rain water on campus. (Photo by Alexa Battler)

Thousands of students and visitors, and over 675 busses, pass by the bus loop and Scarborough Circle every week. At the centre of these loops are sloping land and diverse, overflowing plantlife.
These areas are actually a meticulously designed feat of landscape engineering – and the reason why the campus is not underwater. They are a stormwater management system called bioswales.

Garland Xie, a researcher at the Cadotte Lab, says bioswales have become more important in light of increasingly intense and sporadic weather conditions.

“Recently with climate change we’re seeing more flash floods,” says Xie. “The problem is Toronto’s sewer systems are very old. Bioswales are one way to prevent more water from going into our storm sewer system.”
Bioswales are carefully selected vegetation on land that slopes downwards to usher rain into a stormwater drain. The vegetation soaks up not only a portion of the rainwater, but many of the toxins and pollutants. The water that then flows into the drain is not only lower in volume, it is also cleaner. 

Two bioswales are in the bus loop and one is in the Scarborough Circle. 

A quick walk around the parking lot is a testament to the bus loop bioswale’s impact. Smaller bioswales line the areas separating lines of parking spaces and along the sides of the roads, the grates of which lead beneath the bus loop through underground pipes.

The bioswales at the bus loop were designed by Du Toit Architects Ltd. (DTAH), a multidisciplinary Toronto architecture firm that worked with U of T Scarborough’s original architect, John Andrews, to design the CN Tower.

“Any good university is going to want to deal with water themselves and take water off the storm system,” says Bryce Miranda, one of the landscape architects at DTAH that designed the bus loop bioswales. “It’s taking all of the storm water, in most cases that doesn’t happen, it feeds into the regular system.”

The bus loop bioswales are significantly steeper than the traditional six-degree slope. The three large mounds stand taller than the busses themselves, and represent a significant piece of U of T Scarborough’s infrastructural history.

Miranda says the design was, in part, an homage the internationally-acclaimed Andrews building – the building that composes the H and S-Wings. Andrews, and the Andrews building, were considered pioneers in the Brutalist architecture movement, a style characterized by grandiose buildings, bold designs and exposed materials (as seen in the campus’ famous concrete walls).

“It speaks to the brutal architecture of the Andrews building and the large, monolithic shapes that hug the landscape,” says Miranda. “If we left it just as a regular, straight or level landscape, I don’t think you’d have that impact.” 

The bus loop bioswale was built in 2012, along with the East parking lot and bus loop itself. These structures solidified the entrance by the Scarborough Circle as the campus’ main entrance, and created a new architectural flow to the campus. 

“You want to express and go strong, just like the brutalist buildings. They’re a strong piece of architecture and this is a strong piece of landscape”

When designing a bioswale, landscape architects carefully select plantlife based on a number of factors. The bus loop bioswale has three types of trees, all which were chosen for their symbolic and environmental value: white oak (the official tree of the University of Toronto), maple trees (traditionally Canadian trees) and populus trees (good beginner trees for new land).

“To me there’s a rawness to the University of Toronto Scarborough that we wanted to convey with those types of trees,” says Miranda.

The grasses in the bioswale were also meticulously picked. A blend of native grasses that do not require any irrigation, and could not become invasive in areas like The Valley, were chosen. Many of the plants in both of the bioswales are also pollinators, and attract wildlife to the campus.

Miranda says one of the greatest compliments he has ever received was overhearing someone saying they would meet a colleague at “the three sisters” – a nickname for the three large mounds the compose the bioswales. 

“It makes me understand that people actually took ownership of this space and created something out of it, I think that’s what makes it really special.”

© University of Toronto Scarborough