Regreening results look positive.

Paper mill sludge used to enhance growth of vegetation at former mine tailings site

Mining and academic researchers are experimenting with wood sludge near Elliot Lake in bringing a former mine tailings site back to life. In closing up their Pronto Mine site at Spragge, Rio Algom Ltd. has been spreading paper mill sludge to determine if it provides an adequate capping material to re-green a copper tailings waste area.

Working in conjunction with Laurentian University, the Northern Ontario Mines and Mills Alliance (NOMMA) and St. Marys Pulp and Paper, the scientists and technologists observing the vegetation growth on a barren one-hectare test plot are encouraged enough by what's taken root to expand the program to five hectares and eventually clean up the whole site.

Rio Algom operated 16 mines sites in the Elliot Lake area, dumping millions of tons of copper and uranium tailings in a number of waste properties.

Providing some transportation issues can be addressed, Graeme Spiers, director of Laurentian's Centre for Environmental Monitoring says the process could be mutually beneficial down the road for both the mining and paper industries in finding new uses for waste material.

"Wood sludge is a relatively clean, benign material," Spiers says. "It doesn't have some of the bleaching chemicals used later in the (pulp and paper) process.

"It's sort of like putting a woody layer of compost on top."

During the winter of 1998-99, researchers spread a centimetre-layer of coarse limestone at Pronto to neutralize the high-acid runoff of dissolved metals. Next, a 50-centimetre layer of sludge was put down, then the whole area was hydroseeded.

The results were apparent within a few months.

"I've got photographs from the hydro-seeding in May, to having pretty lush-looking vegetation by July-August, and for the year after,' Spiers says. "It looks like pretty good hay country."

Spiers says the only stumbling block may be transportation costs in trucking such a low-grade waste material over any distance greater than 100 kilometres. Fortunately about 60 per cent of all active and abandoned mine sites are within that threshold distance to make it economically feasible.

Besides enhancing vegetation growth, paper sludge also minimizes erosion of the tailings caused by winter and water, reduces acid generation and runoff, and lowers metal concentrations in vegetation and pore water.

In the first year of the program, the concentration of metals in the tailings at the Pronto site was reduced by 50 per cent.

The Ministry of Environment, which issued the certificate of approval, is taking an active interest. "They are watching the results pretty carefully. as well," he says, "because the generally accepted paradigm is you don't mix waste streams."

Spiers says the Pronto site should probably be kept as a meadow for browsing wildlife with native grasses, sedges and reeds, although a former Falconbridge Ltd. tailings site found use as a baseball diamond.