MERN - Québec Mines








        ISSN en ligne :
        1499-383X





February 2002
 


The rehabilitation os State-owned mining sites
$20 million invested
Johanne Cyr
Direction du développement minéral
The mining industry has acquired an unflattering reputation, after abandoning countless mine tailings sites to erosion by wind and water and to oxidization processes that lead to the production of acid mine drainage. Other problems include abandoned waste rock dumps, trenches and other dangerous openings, unsecured infrastructures and machinery, and badly-stored products of varying toxicity.

To ensure that situations like these will not occur in the future, the gouvernement du Québec introduced changes to the Mining Act on March 9, 1995. Since then, whenever mineral exploration or mine extraction activities are undertaken, a rehabilitation plan must be submitted and a financial guarantee covering 70% of the foreseeable cost of rehabilitation work on stocking areas must be deposited by the mining company concerned.

The program to restore State-owned mine sites

Between 1967 and 1985, 11 mine sites, covering a total area of more than 500 hectares, were transferred back to the government by the mining industry. They are located in Abitibi-Témiscamingue (East Sullivan, Sullivan, Terrains Aurifères A, Canadian Malartic, Wood Cadillac, Preissac, Stadaconna and Lorraine), Mauricie (Somex) and Gaspésie (Candego and Les Mines Madeleines). In view of the extensive environmental problems caused by these mining sites, the Department launched a rehabilitation program for State-owned mining sites in 1987. Since 1991, over $20 million has been invested in the program.

A great deal of energy has been directed at the development of efficient, economical restoration methods. Many different experts from the university and engineering consultancy fields have contributed to the work undertaken by the Department. In several cases, an exhaustive characterization of the site concerned has led to the development of innovative technological approaches using various residual materials, such as forest residue, sludge from sewage treatment plants, septic tanks or paper mills, and ash from co-generation power plants. These technologies have reduced costs and offered a solution to the problem of stockpiling at least some of the residues concerned. Various studies have also been carried out to develop passive treatment systems adapted to the specific parameters of mine effluents (biofilters, wetlands, limestone drains, organic barriers, etc.).

As an illustration, the following pages describe the results of some of these mine rehabilitation projects.

Recognized expertise

The rehabilitation of State-owned sites has led to the development, within Québec, of recognized expertise in site characterization, the understanding of mine tailings alteration processes, and the development of effective and economical technologies. In addition, the use and revalorization of various types of residue, the design of passive treatment systems and the integration of wildlife habitat creation as part of the mine site rehabilitation process are entirely in keeping with a concept of sustainable development.

The MRN must now work to promote technology transfers and the diffusion of knowledge in the underworld to ensure that its expertise is put to good use, while continuing to focus on research and technological innovation. Although the restoration of the sites transferred back to the State has now been practically completed, many other sites that have been abandoned over the years still await restoration.

The mining companies that ceased their operations before the amendments to the Mining Act came into force are not required to provide rehabilitation plans or financial guarantees, but they still remain responsible for the tailings produced at their mines. However, there are around 70 sites where the companies concerned either cannot be traced or are insolvent, and are therefore unable to carry out the work required. 15 of these sites are considered to have a major impact on the environment, and must be prioritized for future work. The estimated cost of restoring these 15 sites is around $40 million, and the total cost for all abandoned sites could reach $70 million.

Bibliography

  1. Bertrand, P. and J. Cyr. Restauration du site minier Sullivan : un concept écologique d'aménagement. Vecteur environment- Volume 34, number 4, July 2001.
  2. Isabel, D., N. Tassé, C. Dufour and F. Bergeron. Traitement des résurgences d'un parc à résidus miniers au moyen d'un biofiltre réducteur. Colloque Nedem 2000, October 3-5, 2000, Sherbrooke.
  3. Dagenais, A.M., M. Aubertin, B. Bussière, L. Bernier and J. Cyr. Monitoring at the Lorraine mine site : a follow up on the remediation plan. 2001 National Association of Abandoned Mine Lands Annual Conference, August 19-22, 2001, Athens, Ohio.













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