Diamond saws, live hawks, soil ovens: Eight things that helped make the new Don River valley

Here are some tidbits the Star has learned about what it’s taken to get this far in helping to restore Mother Nature.

Diamonds are a river’s best friend

There are three massive concrete walls currently separating the new river valley from Lake Ontario and the Shipping Channel. Workers are preparing to remove the first wall by first slicing it into chunks — with diamonds.

They’re using a diamond wire saw, which is a steel cable with actual diamonds threaded into its edges, said Don Forbes, Waterfront Toronto’s project director overseeing remediation and earthworks.

A diamond’s hardness and sharpness allow wire saws to smoothly cut through abrasive materials like stone and ore (as long as it’s less abrasive than a diamond).

A new lease on life

The Port Lands was built in the early 1900s, providing the city’s only industrial port, which included manufacturing and energy generation. Its grounds were subject to more than a century of built-up contamination from coal storage, factories and oil refineries.

Before all that, it was once upon a time one of the largest freshwater marshes on Lake Ontario. In 2021, some plants from those lush aquatic days such as soft-stem bulrush unexpectedly reappeared — from seeds that clearly survived.

“Imagine being buried for 100 years with seven metres of dirt piled on you,” said Shannon Baker, project director of parks and public realm with Waterfront Toronto. “Then the right conditions emerge and these tiny little seeds were able to sprout up.” 

A site manager stopped operations briefly. They called in botanists from the Toronto and Region Conservation Authority and members of the Indigenous consultancy group MinoKamik Collective, and replanted some sprouts in Tommy Thompson Park and in the wetlands.

Digging in the dirt 

Decontaminating a Rogers Centre amount of soil isn’t easy. Workers used two methods and they were both done on site.

The first was through bioremediation, Forbes said, where the soil was collected into big piles of windrows then filled with various types of nutrients, moisture and other compounds. An excavator was then used to turn the batch in order to oxygenate the soil.

If the soil was extremely contaminated, workers used thermal remediation where soil was subjected to intense heat in custom-made steel boxes, like industrial ovens, that could hold about 10,000 cubic metres of soil, according to Forbes. Because the soil was mainly minerals, it didn’t combust. Any organic content was reduced to ash.

“All the gas that comes off the top is cleaned through carbon filters before discharging, so we’re not pumping noxious gases into the air,” Forbes added.

Life after death

Trees that naturally grow in wetlands over time will die from being inundated with water. They fall over or sink to the bottom and become habitat for little critters such as turtles, frogs or fish.

So workers planted some vegetation, including trees, in the four wetlands — even though they were dead.

Since the trees didn’t grow there and get the chance to put down roots, Forbes said they had to anchor them in the ground using massive stainless steel cables, which were drilled into large boulders to replicate a natural system as closely as possible.

“The dead trees that are standing are more to provide habitat for birds, moths and avian creatures. They all serve different ecological niches,” Forbes said.

Birds of a feather

Another organism that returned during the naturalization process was birds, from ducks to swallows. They aren’t yet welcome in the area though, because there’s still a lot of work to do. In fact, at one point nesting barn swallows delayed demolition, according to Forbes. One swallow even set up camp inside a diesel generator in a storage container.

The solution? Setting up sculptures of owls — and bringing in live birds of prey, including Harris’s hawks named Ace, Bruce and Suzie. Elsewhere, colourful ribbons blowing in the breeze repel birds.

Specially trained Australian Shepherds named Dexter, Daisy and Tudo are among those who patrol the area in shifts, on high alert, wearing orange safety vests. According to their handlers, the coworkers are gentle with wildlife and will chase geese or seagulls off the property when cued. If there is an injured or moulting bird, they know to leave it alone.

A sticky situation

Seems like something out of a comedy: multiple times workers got stuck in mud — even waist-deep — because there’s just no way to tell what you were about to walk into in some areas.

This happened to photographers Vid Ingelevics and Ryan Walker, who were commissioned to document the project.

“I stepped into what I thought was solid ground, and I sank instantly,” Ingelevics said of an incident from a few years ago. “I had all my camera gear and there was no one around. I was thinking, ‘Do I write my will now?’

“I was able to extricate myself from my boots. My boots were still in the mud,” he said, adding he later pulled them out too.

There was also a time, Ingelevics said, where a worker was mired in mud so firmly that others had to yank him out with a two-by-four.

Shades of the past

There are multiple relics incorporated or preserved from the area’s industrial heritage.

A concrete wall on the North-West corner of the island near the Keating Channel, just south-west of Cherry Street North Bridge, is the foundation of Marine Terminal 35. It was created after the St. Lawrence Seaway opened in 1959 and renewed hope for Toronto’s flourishing port and shipping industry. Visitors will only see the top surface of its footprint since it’s going to be cut down. This will be located in what’s currently named Promontory Park.

The white Atlas Crane, west of Cherry Street South Bridge, is a designated heritage structure and the last of its kind on the Great Lakes, according to Waterfront Toronto. It was used to unload cargo at Marine Terminal 35, including the city’s streetcars in 1966.

Fire Hall No. 30, which stopped operating in 1980, is a designated heritage structure at the end of what’s currently called Munitions Street. It was relocated farther south and will be used as a pavilion at the entrance to what’s now known as River Park.

Cleanup time

Before the new river valley was flooded, it produced about 1.2 million litres of groundwater every day, Forbes said. Because the soil was previously contaminated, so was the groundwater coming out of it. (The riverbed is now lined with a barrier to keep contaminants out.)

“We couldn’t just discharge it to (the Don River) or the sanitary sewer system. So we built our own water treatment plant on-site,” Forbes said, noting it had a capacity of 2.5 million litres per day.

After running the water through it, which is collected through an underdrain system, and ensuring its cleanliness meets the Provincial Water Quality Objectives (PWQO), it gets dumped into Lake Ontario.

“The kicker is that Lake Ontario doesn’t even meet the PWQO, so we’re pumping cleaner water into the lake than the lake,” Forbes said.