Soil reclamation puts bison, bacteria and plants to work

FORT MCMURRAY, Alta. — Bison play a role in reclamation efforts at Syncrude’s Mildred Lake Oil Sands Mine.

When the oilsands were depleted at this site north of Fort McMurray in the late 1970s, the company began reclamation projects involving development of a bison herd, lake formation and the Sandhill Fen project.

The bison element, now the Beaver Creek Wood Bison Ranch, was initially stocked with animals from Elk Island National Park and now numbers about 300 head.

Part of the bison paddock used for seasonal grazing can be seen from a viewpoint on South Bison Hill.

The bulk of the ranch is located further west of the viewpoint, from which visitors can also see an active part of Syncrude’s mining operations.

The viewpoint was a stop during the May 29-31 Alberta Soils Tour that took participants to various sites in the Athabasca region.

Konstantin Dlusskiy, a soil scientist with Paragon Soil and Environmental Consulting, provided an overview.

“Sooner or later they propose to reclaim it to the forested area or wetland, as required,” he said of the former mine site. “They’re not there yet. Instead, they decided to show the bison and show the success of reclamation by introducing bison that were brought from Elk Island National Park here in the late ’90s.”

The role of bison and co-operation from the Fort McKay First Nation are also depicted on information posts along the viewpoint and on a monument along the southbound lanes of Highway 63.

Another part of the reclamation project involves a lake created from a 60-metre deep pit that was once part of the mining operation.

“Instead of levelling it and filling it with waste rock, they came to a different technique,” said Dlusskiy.

“They started filling it with tailings sand, so a mix of sand, water and hydrocarbons that are not extractable from oilsands.”

The addition of gypsum separated water from some of the remaining hydrocarbons, which were collected. The rest formed a jelly-like soupy material that remains suspended for long periods of time.

Fresh water was added to the surface, and it’s believed that sooner or later the mature tailings will sink and decompose as a result of gravity and bacterial activity.

“Actually there is fish in this lake,” said Dlusskiy, noting they sneaked in during pond fill from a nearby creek. “The bottom is poisonous and I would not swim here … but it is still in the progress of reclamation, so the experiment is not over. It’s a large-scale experiment. It’s the best technique known at the time, so give it respect.

“It is one of the first approaches to reclaim the mature tailings before it was known how to do it.”

Dlusskiy said the pond, its water quality and fish are being monitored as the experiment continues.

Yet another part of Syncrude’s reclamation efforts involve the formation of Gateway Hill, a 257-acre landform about 40 metres high. The area was the first site to obtain a land reclamation certificate from the province.

The hill is an overburden dump from Syncrude’s Mildred Lake and Aurora North Mines. Overburden is material removed from the surface so oilsands can be mined.

According to Alberta Soils Tour data, reclamation at Gateway Hill was done progressively beginning in 1982 and finishing in 1994.

One area of the site was provided with one lift, or layer, of soil, while another received two lifts. All oilsands operators now use the latter technique for overburden reclamation.

In the early days of reclamation, vegetation was chosen for its ability to grow quickly and build soil. These days operators are required to plant only native species.

Gateway Hill now features a wetland and hiking trails through bush and forest.

“They have quite diverse plants growing, so it is, I would say, a success,” Dlusskiy said. “It is not a regional forest, but it is pretty good looking.”

The Pembina Institute expressed some reservations about the Gateway Hill project in a 2008 report.

“While it is encouraging to know that reclaimed land is being certified and returned to Albertans, it is equally disconcerting to consider the challenges that lie ahead. Gateway Hill represents .2 percent of the total land base disturbed by mines.”

The institute also noted the area that is now a hill was once a wetland-dominated, low-lying landscape, so “clearly what was lost is not being replaced.”

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