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Reflections on the Inco Superstack

Built in 1972 to clean up Sudbury’s environment and decommissioned in 2020, Canada’s onetime tallest freestanding structure is still standing

An older man holding a photo of his younger self.
Matteo Campagnaro holds a photo of himself in the early 1970s when he was working on Sudbury's Superstack. He says it will be bittersweet when the structure is eventually demolished.Jonathan Migneault/CBC

For Matteo Campagnaro, working on the Inco Superstack — Canada’s tallest structure for a brief time — was a pleasure.

Campagnaro, who immigrated to Canada from Italy in 1965, said his time on the Superstack, from 1969 to 1972, made him fall in love with northern Ontario.

“The hunting, the lakes, the fish, the atmosphere, the outdoors, the friendly people — this is the best place in the world,” he said.

Thanks to his job as a welder, he met his wife in Sudbury. They have two children and a grandson, and still live in Sudbury’s south end.

More than 50 years after it was built, many of the men who worked on the 381-metre-high Superstack are no longer alive.

A large smokestack in the winter.
When it was completed in 1972 the Inco Superstack was the tallest freestanding structure in Canada, until the CN Tower was completed in 1976. (Jonathan Migneault/CBC)

In 2018, mining giant Vale said it would be demolishing the once iconic Superstack because it was no longer needed. It was turned off for the last time on Oct. 30, 2020.

The Brazilian company that bought Inco in 2006 and took over its Sudbury operations later invested $1 billion in what it called the Clean AER (atmospheric emissions reduction) project. That investment reduced sulphur dioxide emissions to the point where the Superstack was obsolete, and it was replaced by two smaller stacks.

An outdated solution to pollution

When the Superstack was built, the idea was to spread Inco’s sulphur dioxide emissions over a wide area to dissipate its concentration.

“The fact that there’s sulphur in the ore is really the key in this conversation, and that’s not true all over the world,” said Glen Watson, a sustainability and regulatory affairs specialist with Vale Canada.

Watson has spent 23 years working to reduce Vale’s sulphur dioxide and greenhouse gas emissions.

After the Sudbury area’s nickel deposits were discovered in the 1880s, miners smelted the ore with roast yards, burning wood to separate the valuable metals from the rock.

“When you’re burning sulphur, you’re creating sulphur dioxide and you have dust that contains metals,” Watson said.

“And the impact of those roast yards was pretty severe on the local landscape.”

The sulphur dioxide in the atmosphere created acid rain that polluted nearby lakes and stunted plant growth.

For decades, Sudbury had a barren landscape where the trees that were still left didn’t grow much bigger than saplings.

As technology improved and environmental regulations tightened up, Inco decided it would build the tallest freestanding structure in Canada to help reduce the environmental impact on the local landscape.

“But of course the disadvantage is that you were then impacting a much larger area at less concentration,” Watson said.

When the Superstack was operational, it spread emissions over an area of about 80,000 hectares.

An old photo from a tall building look down onto a city.
A view from the top of the Superstack when it was under construction in the early 1970s. (Submitted by Matteo Campagnaro)

The Clean AER project

By 2008, technology advanced to the point where Vale was able to start a feasibility study into its $1-billion AER project. Construction began in 2012 and it was completed in 2018.

The main technology that helped drastically reduce emissions was something called a wet gas cleaning plant.

“So you’re cleaning the gas, essentially removing sulphur dioxide before it ever gets to a stack in the first place,” Watson said.

With the wet-gas cleaning plant and other technologies like bag houses — essentially giant vacuum cleaners located near the stacks — Vale was able to cut its sulphur dioxide emissions by 85 per cent.

Since the Superstack was built, the company has reduced those emissions by 95 per cent. When it was decommissioned, Watson said, Vale was also able to reduce its natural gas emissions by a significant margin.

The company used natural gas to heat the Superstack. That created more pressure inside and allowed it to expel sulphur dioxide further.

Watson said the company saves around $10 million per year not having to heat the Superstack with natural gas.

The structure was initially supposed to come down in 2020, but that never happened.

Watson said the company still plans to demolish the Superstack, which needs regular maintenance, so it doesn’t become a safety hazard.

He said the timing will come down to available funding for the demolition.

“Any business is making the same decisions on where to put their capital investments,” Watson said.

“All I can say is that at some point, it will be taken down.”

The Superstack brings mixed feelings

For Campagnaro, demolition of the Superstack will be a bittersweet moment.

“I kind of feel bad,” he said.

“It’s a symbol that when you arrive from Timmins, you arrive from Toronto, you’re arriving from Levack or Sault Ste. Marie, it’s a symbol that you see many miles before and you say, ‘That is where Sudbury is,’ because you see the chimney before you see everything.”

An old photo of four men at the top of a construction site.
Benoit Dufour, third from left, was 25 when he started working on the Superstack in 1970. (Submitted by Benoit Dufour)

Benoit Dufour isn’t as sad to know the Superstack will be taken down one day.

“If they decide to take it down, that’s fine,” he said in a French interview. “Not much we can do about it.”

Dufour grew up in the Lac-Saint-Jean region of Quebec and started working on the Superstack in 1970. He was 25.

Dufour was a welder and worked on a giant steel liner that covered the inside of the Superstack’s concrete exterior.

When he first arrived in Sudbury, he said, he was struck by the barren landscape.

“There were almost no woods. It was just rock in those years.”

While the structure was nearing completion, Dufour was welding nearly 381 metres above the ground.

But he said he always felt safe on the job. During his time at the site, Dufour said, no workers suffered any serious injuries.

Despite his first impression of the city, Dufour stayed in Sudbury for 40 years and worked jobs on major industrial sites across Ontario. He later retired to the Ottawa area.

A large smokestack with a smaller one in the background.
Vale shut down the Superstack in 2020. The company now uses two smaller smokestacks at the site, a move that has drastically reduced emissions. (Jonathan Migneault/CBC)

Deadly tornado strikes

While Dufour said he never felt unsafe, ironworker Lawrence Maltais said there was one particular day he will never forget.

Maltais was toiling away near the top of the Superstack on Aug. 20, 1970, when a deadly tornado touched down in the town of Lively next to Copper Cliff, the location of Inco’s operations and the Superstack.

The carnage killed six people and injured 200.

“It was very scary because we had never seen that in Sudbury,” Maltais said.

He said that was supposed to be his last day on the job, because he and some other workers were scheduled to be laid off as they concluded their part of the work.

At 8:20 a.m. they were waiting for a work elevator outside the structure when the sky turned black.

Maltais said he and around eight other workers were on a platform nearly 381 metres above the ground when the storm hit.

Their elevator arrived around the same time, and they were able to use it for cover.

“We could feel the stack move,” he said.

An engineer later told him the Superstack was designed to sway a bit in the wind to help it withstand powerful storms.

Maltais said the storm lasted around 20 minutes, and everyone up there with him was unharmed. But the tornado cut power in the area and they had to wait almost six more hours to get back down.

An older man sitting on a couch.
Fred Maltais worked on many of the structures around the Superstack when it was under construction in the 1970s. He was across the highway the day a deadly tornado struck. (Jonathan Migneault/CBC)

His older brother, Fred Maltais, was working across the highway from the Superstack that day on a pelletizer, machinery that produces iron-ore pellets.

“The pellets that were on the floor were actually flying around like bullets,” Fred said.

Thinking back on the Superstack, Fred said he always comes back to that day, which he said will live on in his memory for the rest of his life.

Like Dufour, he’s not disappointed Vale will take down the Superstack one day.

Fred said it’s a sign of progress that the structure is no longer needed thanks to significant reductions in sulphur dioxide emissions.

For others, the Superstack remains an important part of Sudbury’s skyline and a symbol of the city.

A man wearing a hart hat at the top of a construction site.
Aarne Kovala, shown in this image at the top of the Superstack, was a foreman when it was under construction. (Submitted by Liisa Kovala)

Liisa Kovala’s father, Aarne Kovala, was a foreman who worked on the Superstack in the early 1970s.

Liisa is president of the Sudbury Writers’ Guild, which is now asking for people to submit short stories, poetry and non-fiction about the Superstack.

She too has mixed emotions about it coming down one day.

“I don’t remember a time when the Superstack didn’t exist.”

She still sees the tall structure whenever she drives from her home in Naughton, west of Sudbury, to the city.

“I really hope we get a great variety of viewpoints on this smokestack, whether you worked on it or had a family member work on it, or lived below it,” Liisa said.

“Maybe you were a kid growing up in Copper Cliff, or maybe you’re part of the regreening of Sudbury and you want to talk about those aspects.”

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