The sight of drifts piled against snow fencing is less common along local roadways than it once was.
These days it seems one is more likely to see orange plastic snow fencing used to cordon off a construction site or mark the perimeter of a temporary beer garden, than deployed to manage snow drifts.
Snow fences work by making the wind speed on the downwind side and near upwind side lower than on the far windward side, causing blown snow to settle to the ground, mostly downwind from the fence. Thus, snow fences actually cause snow drifts, rather than prevent them. The fences are placed to cause a snow drift where it is not harmful so that the snow does not drift onto undesired areas, such as roadways.
Wellington County engineer Gord Ough says snow fencing is still used by the county roads department, but a number of elements factor into when and where it’s employed.
“Sometimes it’s less and sometimes it’s more,” said Ough, who notes there is on-going debate about the effectiveness of snow fences as a winter road maintenance tool.
“The jury’s been out on both sides of the issue over the long haul,” he said. “There was a lot of effort to erect the stuff and then take it down and then, depending on the winter, it might be effective some winters but not other winters. So we are probably being more selective on where we put it. But there is certainly a value to snow fence, we realize that.”
Sometimes, Mother Nature interferes with the planned deployment, Ough points out.
“If winter comes in early and the fence isn’t up already, given that the winter started early, we’re into plowing and sanding and all that stuff – and it’s very labour intensive to get the fence up,” he explained, adding that it’s also more difficult to set up the fence once there’s a lot of snow on the ground.
Effectiveness of snow fences also varies from year to year.
“If you get a lot of snow, your snow fence kind of fills up behind it … once the snow is up to the top of the fence it’s not as effective,” said Ough, adding, “Your snow fence might be more effective in the early part of the winter. If you get a lot of snow it loses its effectiveness.”
Ough says that about a decade ago, “we pretty well discontinued the use of it, because we had some up that we weren’t sure was worth putting up.”
After analyzing the effects on key areas, Ough explained, decisions were made to use snow fences in areas where it was most likely to be useful. He also pointed out the need for snow fencing “changes with the terrain, with trees and stuff that grow up” in given areas.
Snow fencing doesn’t have to mean man-made orange plastic, or wooden slat constructions, says Ough.
“Probably the best snow fence we can have is if a farmer happens to have corn in a field where we want to hang our fence – we ask him to leave four or five rows of corn because it’s higher than our fence and more effective.”
Also in recent years, the county has been promoting its Green Legacy program, which has planted more than a million trees in Wellington County since 2004, as a possible solution.
Strategically-planted trees and hedgerows can become a “living snow fence,” Ough explained, although he says it will be a few years before these plantings “grow up to be effective as a snow fence.”
The County of Wellington Living Snow Fence Program fully subsidizes the planting of potted trees with a planting incentive program. Green Legacy is working with the county engineering services department on locating sites and pairing volunteers with landowners to make these plants possible.
For more information go to www.wellington.ca/en/discover/livingsnowfences.asp.
