If not carefully stored, mining operation waste—finely crushed ore known as tailings—can contaminate the environment. Tailings are typically stored in large pits in the ground. The pits are sealed with covers that block out air to prevent a chemical reaction between tailings and oxygen; a reaction that leaches toxic components into water flowing naturally in and out of pits. Covers come in several flavours, one of which is known as a Cover with Capillary Barrier Effects (CCBE)—multiple layers of carefully selected soils that act as an oxygen barrier.

One of the benefits of CCBEs is that plants in the surrounding area can colonize the soil layers. But, there’s a catch to the restorative abilities of CCBEs: roots make holes in the layers and oxygen seeps in. “We want[ed] to know if the natural evolution of the reclaimed mine site towards a temperate forest could impact the cover performance in the long term,” explained Dr. Marie Guittonny, co-author of a new study in Canadian Geotechnical Journal, led by her PhD student Alex Proteau at the University of Quebec at Abitibi-Témiscamingue…

This story was written for (and can be read in full at) Canadian Science Publishing.

Header Image: Ancash San Marcos Antamina Mine (Peru). Credit Paulo Tomaz (CC BY-SA 2.0)