Toronto examines a new stormwater management approach

A successful pilot
photo of stormwater retention area at Calstone
The Collective Stormwater Infrastructure Project at Calstone Inc., which features both a rainwater harvesting tank and retention pond seen above.

Supported by project funding from regional municipal partners, Partners in Project Green pursues collaborative sustainable initiatives with hundreds of private companies and public organizations. In 2014, its Water Stewardship team focuses on projects aimed at developing innovative low-impact stormwater management technologies on ICI sector properties, using a network of service and technology vendors. The first installation was completed in 2015 at Calstone Inc., a mid-sized steel furniture manufacturer in Scarborough, Ontario.

Calstone initially approached Partners in Project Green after receiving the City of Toronto’s $5,000 Hometown Heroes award, with the goal of completing a small rainwater harvesting and garden project. Using funds from the Ontario Ministry of the Environment and Climate Change’s Showcasing Water Innovation program and water stewardship capital grants, as well as leveraging exclusive discounts from its vendor network, Partners in Project Green was able to scale-up the value of the project to more than $125,000.

The Calstone project involved disconnecting three of six downspouts from the company’s 42,000 ft2 roof to feed into a series of LID features. One downspout connects to a 9,300-litre rainwater harvesting tank. When full, it irrigates Calstone’s on-site garden and vegetation, and overflows to a retention pond that serves as an attractive water feature. The other two downspouts are connected to an infiltration trench at the back of the property. During larger storms, these will overflow into a pair of connected infiltration ponds, allowing the water to slowly return to the water table and, eventually, flow to Highland Creek. The 8,400 ft2 infiltration and retention system will divert an estimated 1.9 million litres of rainwater annually.

photo of stormwater retention and infiltration pond
The series of stormwater retention and infiltration ponds at Calstone Inc.’s installation with Partners in Project Green.

This collective infrastructure project expanded upon an existing Calstone water stewardship initiative. More than a decade ago, the company’s President and CEO Jim Ecclestone happened upon an old milk pasteurization tank while walking through a farm field, and decided to find a use for it. The Calstone team disconnected one of their downspouts to flow into the salvaged tank, and, since then, has used the greywater both for their toilet fixtures and to cool spot welders in their manufacturing operations. In addition to relieving the strain on the local storm sewer system, this creative retrofit reduces potable water use. Calstone’s ultimate goal, however, is to remove itself completely from the municipal grid.

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Performance evaluation of the system is now underway, and will continue for two years. Partners in Project Green will use the results to evaluate the effectiveness and cost viability of these kinds of stormwater technologies, and to promote the installation of future ICI retrofits across southern Ontario.

Building a network of projects

One-off projects cannot, on their own, generate significant results on a watershed-level or municipal scale. It takes networks and clusters of projects to create measurable impacts on local water and stormwater footprints. Individual projects must be informed by a holistic outlook that takes into account not just an organization’s own water usage, but also the water falling beyond its property line. Projects such as Calstone’s demonstrate the advantages of such an approach.

Partners in Project Green looks forward to continuing its efforts to develop a network of unique, ICI sector water stewardship initiatives. Through such projects, the group hopes to promote best practices and efficiency in stormwater and process and wastewater management, and to connect organizations within and across watersheds to form the “Watershed of the Future.”

Eric Meliton and Alyssa Cerbu are with Partners in Project Green.

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  1. Timely article. More citiess and towns seem to be addressing wastewater in
    this manner. Infrastructure is an ongoing issue for all of us. Spread the news.
    thank you.


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