City staffers hope to test a special salt spray on St. Albert Trail this winter that could make it as smooth as Ray Gibbon Drive come the next snowstorm.
Drivers rolling down Ray Gibbon Dr. last week after the big snowstorm might have noticed something unusual – unlike the rest of the city’s streets, which had thick layers of bumpy, rock-like snow on them for days, it was snow-free within hours of the initial dump.
The reason was a salt spray applied by contractor Carmacks Maintenance Services Ltd. to Ray Gibbon in advance of the storm, said Tony Lake, public works director for St. Albert.
“Indications are that had we treated St. Albert Trail and our arterials in (that) manner, we wouldn’t have the build-up (of snow) we currently have.”
St. Albert doesn’t currently have the equipment to apply liquid salt to its roads, Lake said. Instead, it mixes various salts in with its sand and gravel and distributes it that way.
But regular road salt doesn’t work below about -13 C and tends to fly off the road due to traffic, said Graeme Douglas, operations manager for Carmacks. You also have to clean it and the gravel up come springtime.
Carmacks started using a salt spray around 2012 to treat the northwest part of Anthony Henday Dr., Douglas said.
St. Albert has piggybacked on this initiative since the start of this year by having Carmacks also treat Ray Gibbon Dr., Lake said.
The spray is a coffee-brown, almost slimy mix of water, calcium chloride, magnesium chloride and an organic rust inhibitor that’s sprayed out the back of a tanker truck, Douglas said.
“It’s more or less the same stuff they use for dust control on gravel roads.”
The spray is made by Tiger Calcium Services. A promotional video on the company’s website features Douglas speaking about his company’s use of the product and footage of it being used on the Henday. (Douglas said he volunteered for the video and was not paid for his appearance.)
Snow melts when it hits a road because the surface is hot from the friction of rolling tires, says Steven Plamondon, spokesman for Tiger. It then refreezes, creating a concrete-like snow pack that’s tough to scrape off.
Douglas says his crews apply the spray before a snowstorm, creating a salt film on the road that lasts for about 10 days.
Snow still melts when it hits the film and the hot road, but stays liquid for longer because of the calcium chloride, which releases heat when it dissolves, Plamondon said.
That keeps the snow from freezing to the pavement and turns it into an easy-to-remove mush, Douglas said – that’s why Ray Gibbon was clear last week while the trail was not.
“We had that layer on there that we could break the snow off of and didn’t get that packed-on ice everyone else was having a problem with.”
The spray equipment is expensive, and the liquid itself is touchy to work with since it sucks in moisture, Douglas said.
But he estimates that the spray reduces the amount of salt his company needs to use on roads by about 15 per cent. Carmacks uses about 900 litres of spray to get snow off Ray Gibbon, for example, and would need about 15 tonnes of sand and salt with conventional methods.
“We’ve used it successfully to about minus 32 for breaking off ice pack,” Douglas said, making it well suited for Alberta temperatures.
The spray also costs less than regular salt – he expects to make back the cost of the spray equipment with the savings – and might be more environmentally friendly, as it doesn’t pile up on the roadside like conventional salt.
It costs about $3,500 to do a spray treatment of Ray Gibbon, Lake said – the city has done two treatments so far this year.
The treatment has worked so well that the city is now in talks to try it on St. Albert Trail, Lake continued. He’s not yet sure where on the trail, as they need to find a spot that would be comparable to Ray Gibbon.
Questions on the spray trials should go to public works at 780-459-1557.
