New York-based studio Agency—Agency has collaborated with local studio SHEEEP to design stormwater gardens underneath an expressway in Toronto.

Located two blocks east of The Bentway park, a rehabilitated stretch of greenspace underneath Toronto's Gardiner Expressway, the Staging Grounds installation will funnel and cleanse rainwater from the expressway using a passive filtration system.

"It's a privilege working with The Bentway on Staging Grounds to think creatively about the city's infrastructure and to centre the design of water in the public's daily experience," said Agency—Agency director Tei Carpenter.

The installation will feature a system of re-routed downspouts that funnel stormwater and melted snow into circular planters located at the base of the expressway's support columns in order to mitigate local flooding.

An initial stormwater filter placed at the top of each planter will perform passive filtration before the water runs into a circular garden container below.

Native plants such as milkweed, Agastache and yarrow will further absorb excess water, as well as salt.

A secondary shallow overflow garden located at the base of the stormwater garden will collect additional run-off and be populated by volunteer species – plants that grow without deliberate planting.

Visitors will access the installation through a series of interconnected, elevated paths that span a 20,000-square-foot (1,858 square metres) site, which is a satellite laboratory of The Bentway, a 1-mile-long (1.75 kilometre) multi-use trail along Toronto's waterfront.

"We're really excited to share this project with the city and to see how an underutilized part of our infrastructure can be actively and passively used throughout the year," said SHEEEP founding director Reza Nik.

Urban design and landscape studio Public Work led the design of the park alongside design advisors Greenberg Consultants.

The first phase opened in 2018 and features year-round activities and public art commissions, including a 220-metre long ice skating path.

The Staging Grounds installation will remain on display until the city's Gardiner Expressway Rehabilitation Strategy commences in the area, which aims to keep the entire expressway safe and operable for traffic and pedestrians alike.

As of March 2021, phase two of The Bentway moved forward with a redesign of a wooden pedestrian footbridge.

Imagery is courtesy Agency—Agency and SHEEEP

Staging Grounds will be on display starting September 2023 until late 2025 in Toronto, Canada. See Dezeen Events Guide for an up-to-date list of architecture and design events taking place around the world.