For as long as Inco has been smelting and refining nickel, slag, a dark grey and black by-product comprised of silica and iron, has gathered into ever increasing piles covering an estimated area of 2.25 square kilometres.
Approximately 1.4 million tons of slag is produced annually, totalling roughly 50 million tons, said Gary Holman, Vale Inco public affairs specialist.
The company diverts a portion of the slag into the mines as backfill and to grade underground road surfaces.
The remainder is hauled by rail to one of four dump sites and poured from eight 30-ton slag pots every hour on a 24-hour basis.
During the ’50s and ’60s, it was popular to watch the fiery, lava-like liquid spill out onto the slag piles. The company no longer gives tours. Over the years, the dump sites have worked their way inland from the road, making it inaccessible to passers-by.
The need to curtail dust and smelter noise has prompted Vale Inco to cover the waste product with grassy, green hills that will eventually look like any other forested area in Northern Ontario.
Mike Peters, Vale Inco’s grounds supervisor and grower, has been working on regreening the slag hills adjacent to the smelter along Regional Road 55 for the last 10 years. Funds became available to accelerate the greening along Big Nickel Road in Copper Cliff in late 2006.
“There is an effort on now to try and reduce the environmental footprint of the smelter site,” Peters said. “We worked at pushing the slag during the winter and put the cover on the slopes last summer.”
Peters and his crew of five deposited a combination of peat and clay up to half a metre thick on steeper inclines, providing the base for a healthy mix of hardy fescue grasses and clover, now growing on many of the steep slopes. They are hydroseeded onto a custom mulch blend of wood fibres and glues.
“We find it excellent for this type of work,” said Peters. “The tactifier glue locks it together and holds it on the slope.”
It is sprayed from several directions to create an interlocking matte, which Peters said is a different process from the Sudbury regreening project in which his father, renowned reclamationist Tom Peters, participated in as a company agriculturist. The mulch controls temperature fluctuations and helps retain water on the 50 degree-angled slopes, preventing erosion. The steeper the slope, the greater the amount of mulch applied.
Erosion control tubes called wattles are placed along the length of the slopes to control water runoff, preventing the seeds from being washed away with the rain.
To date, approximately 30 hectares have been covered.
Once the grasses have been established over the next two years, red and jack pine, and white spruce trees from Vale Inco’s greenhouses will be planted along the slopes.
“We grow between 200,000 to 250,000 seedlings every year,” said Peters, who sits on the City’s Vegetation Enhancement Technical Advisory Committee (VETAC), which receives 80,000 seedlings per year for distribution to various organizations throughout the Sudbury district.
Vale Inco’s greenhouses, both surface and underground, have been operational for at least 50 years. Peters said the company has grown more than four million seedlings since 1985, when it began growing its own trees.
The plan is to continue regreening from the outer edges, retreating back toward the smelter, presenting a greener healthy forested landscape.