Restoring abandoned mine sites in Canada for the "crater" good

 

- Schefferville, Quebec

Strike while the iron is hot

Until Québec's 1987 Mining Act and Newfoundland and Labrador's 1999 Mining Act were established, no set regulations existed for mining companies to take responsibility for the rehabilitation and revegetation of sites in these provinces. Abandoned mining sites exist across Canada, where all that is left is waste rock and fine fluid tailings. This can lead to environmental problems like water contamination, which can be especially dangerous to aquatic life if left untreated.

This is why, for the past 3 years, Tata Steel Minerals of Canada (TSMC) has been funding research projects to restore its mine sites in the region north of Schefferville, in both Quebec and Newfoundland and Labrador with the help of various organizations including Université Laval, McGill University, local industry, Aboriginal environmental technicians, and the National Research Council of Canada (NRC). NRC researchers Dr. Charles Greer and Didier Barré, P.Geo, M.Sc. from the NRC's Energy, Mining and Environment Research Centre have been working alongside these organizations to facilitate the revegetation of these disturbed mining sites.

In addition, the Innu and Naskapi First Nations local community are working with these organizations to closely monitor the progress of the sites' remediation.

Digging up answers

Typical sparse vegetation composed of a variety of moss cover, ericaceae, and alders, with islands of spruce growing on the undisturbed glacial deposit (photograph provided by TSMC).

As a first step, geomorphologist, Didier determined the type of soil the plants would grow on later. To do so, he looked at the existing mineral matrix (i.e. particle size distribution of natural soils and waste rock piles, mineralogy, geochemistry, organic content and toxicity) and the type of plants that grow naturally in the region.

The growth and survival rate of plants in these cold climate conditions is very short.

Based on this analysis, Didier is now generating nutrients to be added to the soil, based on a Biochar which has the ability to retain moisture and provide a carbon source, absent from the waste rock. The nutrient mixture will then be added into disturbed soil and the waste rock on TSMC's site to promote the development of a soil for plants to grow in.

A sparse vegetation dominated by alders, willows, and some spruces that are colonizing an iron tailings deposit (photograph provided by TSMC).

This is where Charles' knowledge in biodegradation and bioremediation/phytoremediation of environmental pollutants, microbiology and genomics comes in. Charles explored the relationship between the pioneer plants (plants that perform the initial colonization process on poor soils) and other plants growing in the Schefferville area alongside the microbes (fungi or bacteria) associated with each. Since plants have bacteria that can protect, help or hurt them, Charles needed to find which root microbes would help the plants grow.

Charles noted "when material is dug up and has had extractions performed on it, what's left behind is known as the waste rock and this material may be a very poor soil for any plant to grow on. We are trying to get plants to grow on material like this because they start the process of improving soil quality. Once they do that, other organisms can begin to grow there and colonize the same habitat."

Rocking on

Once TSMC has finished extractions, restoration of the site will begin with a view to its closure. To do so, there will be companies doing outplanting work and looking at the survival rate and growth performance of the plants. This part of the project will support the effort to revegetate the mining site until a successful formula is attained and the plants begin to grow back sufficiently to restore the site to a pre-disturbed state.

"For TSMC, collaborations with organizations such as the National Research Council of Canada allow us to go beyond regulatory requirements and dig deeper into understanding the landscape in which we work," noted Mariana Trindade, Corporate Environment Manager of TSMC's Environment Department.

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