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The science of spring

City works department in a delicate dance during each year's thaw

Darren Stewart
Northern News Services

Yellowknife (Apr 04/03) - At the end of every winter, Mother Nature throws Sean Mailloux a few wrenches.

"Murphy is on the job every day here," he said, referring to the "law" which says everything which can go wrong will.

NNSL Photo

City worker Byron Butt shows off the steam sprayer he uses to thaw frozen drains and culverts each spring. - Darren Stewart/NNSL photo

Mailloux is the city's sub-foreman in charge of streets and sidewalks.

Each spring he co-ordinates a delicate but complicated dance of street cleaners, flush trucks, gravel, melted snow, dust suppression and water run-off.

When the season starts to turn, the works department picks a day to jump into high gear.

They move fast to remove snow around the clock, scrape off the layer of gravel below, steam-thaw culverts, sweep debris and dirt off the streets and flush them clean to reduce summertime dust.

If they start too soon, the streets freeze over at night and the city becomes an ice rink -- or it may snow again, forcing the expensive process to be repeated. Crews have to make sure the hundreds of catch basins are clear of snow and ice, which is expensive and time consuming to do once, let alone two or three times.

If they wait too long, melted snow collects in pond-sized puddles in the streets and can run off into people's basements in houses at lower elevations.

"It would be great if winter ended one day and spring started the next," said Mailloux. "Of course it doesn't work that way."

"We don't have the luxury of resting on our laurels."

As soon as the first really warm weather strikes, city workers go out to the 15 outflow pipes on the lakes and blast the ice clear with steam guns to start the run-off process.

Mailloux said there is very little margin of error in the process.

"We have to be proactive; reactive is too expensive."

Weather is everything

City superintendent Mike Elgie watches the weather forecasts closely at this time of year. He said it's typically the second or third week in April that the process begins, but can be as early as mid-March. He called the snow removal and run-off management a "balancing act."

"The more snow we can get the less dust we're going to have when everything melts," he said.

The weather rarely co-operates, Elgie said. As soon as they remove compacted snow there's a blizzard; as soon as they flush the streets and drains with water, there's a cold snap that freezes the water making for dangerous driving and slick sidewalks.

He said the streets have to be cleared of gravel and dirt before dust starts kicking up each year or people with allergies would be in trouble.

The boss, the costs

Public Works director Greg Kehoe said ensuring the streets are safe and dust-free, and no basements are flooded -- while keeping costs down in the tight time frame -- is a complicated science.

The city's drainage system is governed by the simple science of gravity, but his team has to time everything right, and keep their work within budget -- a whole other science.

"It's more difficult than it sounds," he said. "The spring melt happens all at once."