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'Excellent' results from Vale's use of municipal waste to green up mine tailings

Terrapure Environmental brings award-winning solution to Sudbury
Vale Tailings Reclamation  (16)[172]
To date, Terrapure Environmental and Vale Canada have diverted over 100,000 tonnes of biosolids from disposal and treated over 175 acres of mine-impacted land which are now able to provide a natural habitat. (Supplied photo)

Terrapure Environmental and Vale Canada have now won so many awards for their innovative mine tailings rehabilitation project that their team members have almost lost count. 

The Burlington-based advanced waste management and field services company broke ground when they approached Vale's Sudbury Operations in 2012 with an idea to solve a municipal and mining problem. 

They wanted to apply treated biosolids to Vale's Central Tailings Area in Copper Cliff for reclamation and revegetation. 

The result of the discussion was a wildly successful collaboration. 

Last May, both companies jointly won an Environmental Leader Award for Project of the Year. By June, they took home a Tom Peters Memorial Mine Reclamation Award, among others. 

To date, they have diverted over 100,000 tonnes of biosolids from disposal and treated more than 175 acres of mine-impacted land in providing a natural habitat to the surrounding area. 

Their efforts have been recognized as a win-win situation for recycling municipal waste and finding a sustainable solution to tailings reclamation.  

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Biosolids is the name for different kinds of treated sewer sludge that can be used for nutrients in soil. 

Essentially, the wastewater treatment process results in two different outputs: clean water, which gets discharged back into a creek or a lake, and solids, which are removed, treated and stabilized for beneficial use such as fertilizer.

During the summer months, biosolids are often spread on agricultural land. But they can only be applied to fields in a limited capacity.

From Dec. 1 to Mar. 31, farmers are prohibited from spreading the material. This is due to potential runoff and public perception. And it presents a challenge for companies like Terrapure. 

The company has long-term contracts with different municipalities. They collect biosolids 52 weeks out of the year. During the winter months, the waste tends to pile up. 

Storing biosolids can get complicated. 

“In the past, we had a large storage facility, but we just closed it because of public encroachment,” said Jeff Newman, director of business development at Terrapure. “We were in the Niagara region, and it just wasn't a good site.” 

If biosolids cannot be properly stored, they are incinerated or sent to landfills. 

“I looked at reclamation because they use reclamation in B.C. and down in the States, but in Ontario no one had really been able to do reclamation on mine sites with biosolids,” said Newman. “I looked at that as an opportunity.” 

Revegetation has been a prominent discussion in Sudbury for years. 

During the '60s and '70s, the prevailing notion was that tailings basins were forever doomed to be wastelands. The only solution at the time was to dig up clean soil from areas outside the Sudbury basin and import it. 

“Even in the '60s, the concept of digging up virgin lands, that had never been impacted by mining, and bringing them into a waste storage area for reclamation was not considered a sustainable concept,” said Quentin Smith, project manager for Vale's environment department in Sudbury. 

Dr. Tom Peters, who was in the agricultural department of INCO at the time, came up with a different formula. 

Peters, well-known as a founding member of the Canadian Land Reclamation Association, became INCO's agriculturalist in 1973. He is considered a pioneer in the use of agricultural practices in regreening mine tailings. 

In rejecting the idea that tailings basins were doomed, Peters determined that by using standard agricultural supplies like dolomitic agricultural limestone, fertilizer, and grass seed, it would be possible to get vegetation to grow without having to import clean soil.

It is this formula that was widely used for tailings reclamation until recently, but it wasn't perfect. 

Lime is not a renewable resource. To get the necessary results, quite a bit of lime had to be added to the tailings.

While this method was moderately successful, it still left the company with large areas of bare or sparsely vegetated sites. 

This led to wind erosion management challenges. Vale would have to cover the areas with hay and chemical dust suppressants, practices that are expensive and time consuming.

Back in 2006, Vale was already exploring different solutions. They had originally looked into pulp and paper mill biosolids. While the results of their research and development project were favourable, the pulp and paper mill industry wasn't producing enough biosolids to make that option sustainable. 

They had to look elsewhere, which eventually led to the 2012 partnership with Terrapure. 

At the start, their biggest obstacle was obtaining the right permits and approvals to do this kind of work. There were no regulations in place for applying biosolids to mine tailings in Ontario. 

In April 2014, they received their Environmental Compliance Approval and then the team got to work.

Their early activities included experimenting with application methods, tonnage per hectare, and the right combination of nutrients.

Early mistakes taught them that their biosolids mixture was too high in nitrogen. They determined that they needed more carbon sources for better results. 

While applying biosolids to mine tailings has been done before, every environment is unique. In Sudbury, they had to account for the changing seasons, and the nature of the material they were trying to cover. 

Through trial and error, Vale and Terrapure were able to create something called a custom reclamation mix (CRM). They used different blends of materials to create something that resembles compost you can buy at the store. 

It was important to Vale that the team worked to minimize odours and to stabilize the nutrients due to high application rates. 

Through their experimentation, they partnered with the City of Greater Sudbury to use the city's leaf and yard waste in the CRM as a source of carbon. 

Vale also looked internally and decided to use their recycled cardboard for the same. 

All of this is done at Vale's Central Tailings Area in Coppy Cliff. They have a facility established in an inactive part of the tailings basin. They bring all of their material to the facility and Terrapure employees create the biosolids mix on site.

Both companies are very pleased with the results of the project. In fact, Vale has begun to rehabilitate their decommissioned tailings facility in Levack with the same technique.

In the future, they hope to continue their recycling efforts by creating a green bin program for their offices. Any food waste produced by employees can also be used in the CRM. 

They also hope to expand and diversify the project. Project manager Quentin Smith believes this technique can be used not just in tailings basins but to rehabilitate other mine-impacted lands as well.

Terrapure wants to continue to build their relationship with Vale. 

They have also begun to work on different projects in the mining industry with IAMGOLD in Gogama and with the Ministry of Energy, Northern Development and Mines at the Kam Kotia mine site in Timmins.

Glen Watson, superintendent of reclamation and decommissioning of Vale's Ontario Operations, has a very optimistic outlook. 

“We've had excellent plant growth yield under very challenging conditions.

“The success of this program is something we can all be proud of and learn from in the future.” 

About the Author: Colleen Romaniuk

Colleen Romaniuk is a Local Journalism Initiative reporter based out of The Sudbury Star. The LJI is funded by the government of Canada
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