Trenching in the Arctic

Think about what usually qualifies as a difficult underground project. Challenging soil conditions. Extreme weather. An isolated jobsite. Perhaps special environmental considerations.

No doubt many utility installation contractors have had projects in which some of those conditions were present.

Rohl Enterprises is dealing with all of them and more during a two-year fibre optic installation in northern Canada that extends above the Arctic Circle. Not that it bothers the Canadian company.

“We like the big, challenging projects, which a lot of people try to steer away from,” owner Jason Rohl says. “We always do it on time, and we do it on budget – and even crazier, we enjoy it.”

The Mackenzie Valley Fibre Link project meets that standard in spades. The objective is to install approximately 1,200 kilometres of fibre, mostly with open-cut methods, on a route running north to south in the Northwest Territories.

When work started in mid-January, the sun was out for just a couple of hours each day and crews were working in temperatures that were regularly minus 34 degrees Celsius, and lower. The soil conditions included permafrost – ground that is frozen year-round.

21st century technology

The end result will be a fibre optic line that brings high-speed Internet and improved telecommunications to several communities in a remote region that even by Canadian standards is far north. Consider that the southern point of the fibre line is almost 1,500 kilometres from the border with the continental U.S.

The Northwest Territories is vast at 1,346,104 square kilometres. It is also sparsely populated, with 43,485 residents as of the last census in 2011.

“The fibre project brings these communities into the 21st century as far as telecommunications infrastructure goes,” says Sean Craig, an analyst with the Finance Department of the Government of the Northwest Territories. “The communities up in the Mackenzie Valley are either on a microwave radio system or on satellite. So fibre optics, it’s hard to put into words just how much better that is.”

The $82-million project is being led by a consortium made up of Ledcor Developments, a Vancouver-based construction company, and Northwestel from Yellowknife. The NWT Government is the project owner.

Groundbreaking occurred in January in the town of Inuvik, which is the northernmost point on the fibre line and is above the Arctic Circle. Given that a shovel would be useless on the permafrost, a Vermeer T555 Commander 3 tractor with a rockwheel attachment did the honours.

That is one of eight pieces of Vermeer equipment Rohl Enterprises, the installer, ordered specifically for the project. There were two more T555s with rockwheels, two T655 Commander 3 tractors with rockwheels, an RTX1250 ride-on tractor with a rockwheel, another RTX1250 but with a vibratory plow, and an RTX550 ride-on tractor with a vibratory plow.

Rohl Enterprises has very specific needs for the project. The work in the north must occur in the winter because the ground has to be frozen enough and have a certain amount of snow on it to support the construction equipment. Rohl says he needed solid, reputable machines, but they couldn’t be too heavy.

Rohl Enterprises would normally use a cable plow instead of rockwheels, but plowing causes more surface disruption, and the government wants as little of the permafrost touched as possible.

‘Everything known to man’

The project is to be completed in April 2016 but will occur in phases because of the winter-work requirements. The winter season runs until early April. Rohl Enterprises will work on the southern section in the warmer months, and then it will start up again in the north next January.

So while it may seem counterintuitive to those who work in warmer climates, trenching crews started on the northern section of the line in the heart of winter. Six crews were deployed, each led by a track trencher with a rockwheel. Three started in Inuvik and three near Norman Wells, a community near the middle of the fibre path.

The half-inch (12.7 mm) fibre cable was installed between 18 and 24 inches (45.7 and 61 cm) below ground mostly in the right of way of a highway and a winter road. The trench width was 4 inches (10.2 cm), as narrow as feasible so as to protect the permafrost. The plow attachments were used to place the fibre in the trench.

In the north, the ground was solid permafrost. Around Norman Wells, the permafrost came and went. Other ground conditions included rock, boulders, clay, frozen sands, frozen aggregate and frozen peat moss.

“When dealing with a job 1,200 kilometres long, we are going to hit everything known to man,” Rohl says.

Cold and dark

The one constant was the cold. Temperatures reached as low as minus 50 degrees Celsius.

Rohl says that being a Canadian company, his crews weren’t terribly bothered by the cold. Keeping busy and wearing the proper gear were the best ways to keep warm.

Equipment maintenance becomes extra important in such low temperatures. Add to that the hard ground, and Rohl Enterprises decided to hire three service technicians from Vermeer Canada to keep the machines in peak condition.

The Vermeer equipment handled the frozen ground better than Rohl anticipated, and by early March his crews where installing about 10 kilometres of fibre a day. “The equipment has made me as productive as I could be, without a doubt,” he says.

Night can be a relative term so far north. Because of the earth’s axial tilt, the Arctic Circle has more darkness in the winter than areas to the south. When fibre installation started, there were only a couple hours of sunlight each day starting at about noon. Vitamin D supplements were available to workers to combat the low sun exposure, and crews had light towers, head lamps and flashlights.

Not your normal logistics

The crews working the farthest north lived in mobile camps transported on sleigh-mounted trailers. None of the waste from man or machine was to touch the ground.

“It is a task in itself when you are talking about being 100 kilometres in the middle of the tundra,” Rohl says. “It’s so remote it’s tough to even fathom what I am talking about when I say we have to haul out gray water and haul in fresh water and you have a 22-man camp.”

Environmental monitors followed every crew watching for everything from camp waste to at-risk wildlife, which if spotted could require a work stoppage to let them pass.

Crews were restricted to a right of way of six metres. They could double the width every five kilometres to use as a passing zone and staging area.

Rohl says that moving equipment and supplies took a great deal of planning and coordination, but his company is becoming well versed in jobs with complex tasks like this.

“The projects have gotten bigger and more remote and bigger and more remote,” Rohl says. “We just take what we’ve learned and apply it to the current job, and learn a little bit more and keep getting better.”