November 2008

Engineering Exchange

It’s like setting up a town: AMEC’s work at Snap Lake goes well beyond the usual mine-building

By M. Eisner

Tanks make their way to Snap Lake over the ice road.

De Beers' Snap Lake mine (see "Featured Mines" for full mine profile) in the Northwest Territories has faced major challenges from inception. The weather, the isolation and the geology all act in tandem to make logistics, design and operation fiendishly complicated.

Because of its remote location, access to the site is only possible by air, except for a six to eight week window each year. Building and operating the mine therefore required careful and extensive planning. To help with it, De Beers Canada signed an alliance agreement with AMEC, charging them with the engineering and managing of site construction and procurement. Duane Gingrich, vice president, projects, at AMEC’s mining and metals division was the project manager at Snap Lake. He spoke at length of the challenges specific to developing a northern mine that he encountered on the project.

The work before the work begins

It all begins with a single initial focus: site capture. Site capture entails setting up a site to efficiently manage the construction of facilities and the mine itself. “For these facilities, we end up establishing the services required for a small town, putting in a camp for housing and feeding, fresh water supplies, sewage and waste treatment, containment facilities, a power plant, diesel generators and telecommunications,” explained Gingrich.

The unique challenge in the North is the isolation of the site and the logistics in getting all the materials needed to the area. Snap Lake is 220 kilometres northeast of Yellowknife and there were no access roads. Before construction could begin, transportation infrastructure had to be built. In 2005, an airstrip was constructed. Built in stages, it first accommodated small aircraft, and was eventually extended to handle 737 jets and Hercules C-130 transport planes. Planes fly in materials needed to build virtually everything at Snap Lake, from shelter and recreational facilities for employees to critical equipment like heating and ventilation systems for the underground tunnels, fuel storage facilities, access ramps and containment for waste rock and spent kimberlite.

Two months of trucking

It’s not as if having an onsite airstrip bypasses the need for trucking. Much of the mechanized equipment is more efficiently and economically transported by truck rather than by air. Trucking must fit into the short two-month window when a 300-kilometre-long ice road from Yellowknife to Snap Lake is available. In February and March, as many trucks as are available are used to transport large equipment and heavy supplies.

Initial development at Snap Lake began with building the airstrip, some site capture work and initial mine development and setup. Most of it was done in the summer of 2005 and spring of 2006, after material was transported on the ice road in February and March. This phase saw the construction of expanded facilities for camp water and sewer treatment plants, temporary power, along with a facility to treat water pumped from the mine.

A second major delivery campaign followed in February and March of 2007, with an automated process plant capable of handling 3,150 tonnes of ore per day, permanent power plant and utilities building, allowing for the continuation of some underground mine development into February and March of 2008. There were, however, a number of glitches that were solved with quick thinking and ingenuity.

Accelerated engineering

“One of the key features of developing these mines is being able to advance engineering quickly enough so you can procure all the major items. This means that everything needed to construct facilities must be sourced, collected and ready each year in November, December and January, in time for the February-March trip over the ice road. There is a lot of trucking in a short period of time, so you need to do a lot of preparation in the months ahead, because that’s the only window (for road transportation) you have,” said Gingrich.

Of course, Mother Nature can stymie the best-laid plans. The mild winter of 2006 had an adverse effect on the winter road. “We only got in 80 per cent of the material that we planned, so we had to reconfigure construction plans to make use of some of the materials we had on site,” recalled Gingrich.

“We ended up with quite a large flying campaign in the summer of 2006 in order to hold to our schedule,” Gingrich added. “It was quite an intense time when we had to essentially rebuild our plan. We had to take some things apart so we could fly them in. We worked with two other existing mines and the provider of our heavy equipment aircraft. We also brought in two other Hercules aircraft to stay on schedule.”

From site management to people management, waste management and building containment facilities, there is only one way to ensure that all puzzle pieces fall into place. “You need to develop very strong planning right at the beginning when you are evaluating your project,” said Gingrich. “You have to think of how you are going to plan this; you have to schedule your construction needs, what elements have to be procured first to hit the small window each year. Planning becomes very critical to the success of these projects.”

All that planning paid off in the end. The mine reached commercial production earlier this year, and is now ramping up to full production.

Post a comment


PDF Version