The city of Thunder Bay is testing a new way to deal with stormwater runoff as it unveils what it hopes will be the first in a series of new stormwater retention sites.

Thunder Bay stormwater

The stormwater retention facility uses specially designed soil and select plant species to treat runoff from nearby roads. (Adam Burns/CBC)

The pilot project, located on a traffic island at the intersection of Beverley and High Streets, close to Memorial Avenue, uses specially-designed soil and select plant species to help treat runoff from nearby streets.

"This facility is trying to mimic what it looked like 500 years ago,” said Brad Doff, Thunder Bay’s sustainability coordinator. “We're trying to take each raindrop, so to speak, and treat it as if it was falling prior to our urbanization."

This means filling the site with an "extremely permeable" engineered soil that allows stormwater from the streets to funnel into a retention area, where contaminants and sedimentation are filtered out and the stored water can eventually reach the underlying soils.

Future sites planned

"Where the real work of the facility takes place is in what's called the bioretention area,” said Doff. “This is an engineered, designed space that can take on a lot of water, and treat it."

These kinds of facilities divert stormwater from sewer systems, helping avoid common problems associated with runoff, including flooding, erosion and pollution.

Thunder Bay Brad Doff

Thunder Bay sustainability co-ordinator Brad Doff said the stormwater retention site tries to mimic what the area looked like 500 years ago. (Supplied)

Lee Amelia, acting urban forestry specialist with the city of Thunder Bay, says the new installation is an improvement from what was there before.

"We've excavated a large amount of soil from this space that was impermeable, [and] served very little purpose in terms of vegetation or … beautification on Memorial Avenue," he said.

Amelia says he hopes the $60,000 project, the first of its kind in Thunder Bay, will set the standard for future projects.

"We'll get to learn what types of vegetation works in these areas, [and] how exactly we need to design these things in the northwest Ontario climate," he said.