​Slag pile re-vegetation

Vale began progressively re-greening the outer perimeter of the slag pile near the Copper Cliff Smelter in 2007. The process began by ‘ripping’ the slag with bull dozers to return the material to a loose aggregate state, which allows it to be more easily worked with heavy equipment. 

The relatively steep outer slopes of the pile were then graded and contoured to allow the growth of vegetation and promote proper surface water drainage.

Clay material was borrowed from local Vale-owned aggregate sources and placed on the slag piles slopes. Bulldozers were used to compact the clay to a final thickness of 45 centimeters.   

The clay was then immediately sprayed with hydro-seed to stabilize the soil and begin the re-vegetation process. Once grass cover was established on the treatment site, the area was planted with a mixture of Vale-grown pine seedlings and mature trees.

To date approximately 150 acres of the Copper Cliff Smelter Slag Pile have been treated this way.

Tree growing and planting

Two Vale employees working in a greenhouseVale’s Environment Department operates two greenhouses in the Sudbury area. A surface greenhouse located in Copper Cliff and an underground greenhouse at Creighton Mine’s 4,800-foot level.

Vale grows upwards of 400,000 tree seedlings annually, up to three crops in the surface greenhouse and two crops underground. The most successfully grown species are pine (white, red, jack, mugo) and white spruce.

In addition to use for in-house re-vegetation programs, seedlings are donated to various community events and the City of Greater Sudbury vegetation enhancement program.

Aerial seeding

An aerial seed plane flies high in the sky among dark, grey cloudsAerial seeding is a land reclamation tool that has been used by Vale since the early 1990s to re-vegetate historically stressed land in the Sudbury area. Ground-level sulfur and metal particulate emissions resulting from early smelting and refining practices had a wide-spread impact to the land throughout the Sudbury basin. Although these areas have begun to rehabilitate themselves naturally, the process can be accelerated by amending the soil and introducing seed to encourage re-vegetation.

Accessible stressed land can be easily treated by conventional means. However, a more creative solution is required for large remote sites.

In the early 1990s Vale partnered with Laurentian University to develop a process to effectively re-vegetate inaccessible impact lands, eventually developing into Vale’s modern Aerial Seeding Program.

Agricultural aircraft are used to uniformly apply a mixture of pelletized lime, fertilizer and grass seed to stressed land that cannot be treated by standard techniques. Five 100-acre treatment sites are selected annually in conjunction with the City of Greater Sudbury’s Vegetation Enhancement Technical Advisory Committee (VETAC).