May 2007

Engineering Exchange

Engineering for a safe environment

By H. Weldon

Work on the Beaufort project

Golder Associates, founded by Hugh Golder, first put down roots in Toronto in 1960. Since then, the company has quickly expanded, with more than 140 offices worldwide, boasting a skilled and experienced workforce 5,300 strong.

The Montreal Golder office, including their subsidiary Golder Associates Innovative Applications (GAIA), has recently expanded to take up an entire building, giving everybody a little more elbow room as they go about their busy days. The Montreal group is made up of a young, vibrant workforce that enthusiastically takes on new projects around the world as well as in their own backyard.

One of the keys to Golder’s success is its access to an international pool of talent. “We have the ability to pull in experts,” from all areas of engineering, earth and environmental sciences, and computer sciences, stated Veronique Falmagne, associate. These experts may be located either in Montreal or in Golder offices in Canada and around the world, depending on the needs of the project. Collaborations with universities and participation in research groups provide additional avenues for accessing the necessary talent.

The geo-engineering group in Montreal is busy working on a wide variety of exciting projects. In 1995, Golder Associates was retained by Barrick Gold Corporation to provide consulting services for the closure of Les Terrains Aurifères tailings facility in northern Quebec. The project required a significant amount of R&D investment on the part of Barrick. “They were very keen,” Mayana Kissiova, associate with Golder, said, “and enthusiastic on undertaking a project of this magnitude in a way that had never been done before.”

Les Terrains Aurifères, or LTA, was originally an old non-acid-generating tailings pond when Barrick added on their own tailings, which proved to be acid generating. Golder took on the challenge of the closure and developed the first multi-layer oxygen barrier soil cover done on such a large scale. The cover was constructed over the winter of 1996. The first layer, 50 centimetres of thick sand, keeps moisture from escaping from the overlaying layer by the capillary barrier effect. Layer two is 80 centimetres of non-acid-generating tailings, which are fine low-permeability materials with good water retention capacity. These two layers are capped with a compacted layer of sand and gravel acting as an erosion protection layer. Golder collaborated with École Polytechnique Professor Michel Aubertin in the design of the cover layout, and Université du Québec en Abitbi-Témiscamingue (UQAT) is responsible for continuous monitoring of the site. The multi-layer design proved to be a success and has reduced the tailings oxidation rate by an average of 95 per cent over a period of five years. Others are now applying the same technology and using this type of rehabilitation at other sites.

In 2000, Golder was retained by Aurizon Mines Ltd. to conduct a geo­technical and geomechanical investigation of the crown pillars of near surface stopes at the Beaufor mine, Val d’Or, Quebec. The old Beaufor mine had recently been reopened but the discovery of thinner than expected crown pillars in the old area of the mine triggered a detailed investigation. The stope crown pillars were assessed and instrumented. Risk was further mitigated by diverting a creek flowing over one of the targeted areas and by backfilling some of the old stopes. Golder conducted an inventory of aquatic species and, with government approval, was able to redirect the creek away from the mine, with minimal impact on the native fish and other aquatic life. For the mine itself, bulkheads were constructed in drifts and around the mine shaft. Innovative technologies, such as energy-absorbing barriers, were installed to further protect the shaft against potential mud flows that could be associated with failure of a crown pillar located below liquefiable soils. An advanced monitoring system was designed with extensometers and adjacent TDR cable installations throughout the mine. The system can detect movement and/or displacement in critical zones. For their assessment and remediation measures at the Beaufor mine, Golder was nominated for the Grands Prix du genie-conseil québecois.

Golder Montreal has been engaged with IAMGOLD’s Mine Doyon for a number of years in areas of rock mechanics and tailings management. The mine experienced ground control difficulties in 2004 associated with rock mass degradation and rockbursting. Golder is providing ongoing geomechanics expertise and assistance with ground support design and mining strategy in order to help the mine continue to operate safely during the late stages of extraction in some critical areas.

Golder was involved with Hydro Québec’s Eastmain 1 project in James Bay, Quebec. Golder engineering personnel with experience in dyke construction assisted the Cree Construction and Development Company Ltd. (CCDC) on the project. Nine dykes were constructed by CCDC, with a cumulative length of 2.6 kilometres, as part of a larger network of dykes to create a 600 square kilometre artificial lake. The main challenge of the project was building the dams on the bedrock base. “The rock was faulted and fissured, which required cleaning and grouting the base to reduce permeability,” said Michel Lemieux, an associate with Golder. These operations are similar to those used for tailings ponds, so the same basic technology can be applied.

Golder Montreal is made up of three main groups: geo-engineering, which accounts for the bulk of mining engineering, geomechanics, and geotechnical engineering; geoscience, with expertise in contaminated sites, clean up, and groundwater; and the environmental management team, who takes care of EIA, audits, and ISO 14000 implementation. People from the three areas coalesce and together are capable of taking on mining projects from the feasibility stage straight through to closure and reclamation. “Utilizing tools such as sophisticated numerical models and 3D modelling tools like GOCAD, coupled with solid engineering experience, allows Golder to be one of the top engineering consulting firms in mining and industry around the world,” Falmagne stated.

Their motto is “Glocal.” Think globally, act locally. No matter where Golder lands, they hire locally and carry out their work with utmost respect of the people and community.

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