Battle to make slopes safe
There are no comments for this page [ Add Comment ]Friday, December 28, 2007
By Jeff DeMoss
Standard-Examiner staff
jdemoss@standard.net
Ski resorts put a lot of resources into preventing avalanches
EDEN -- Ski patrollers at Powder Mountain have been starting work extra early this week, heading to the ski area before dawn to plant explosives by hand at strategic locations.
It's not a war game, although it is a battle with the elements. They're trying to trigger avalanches that, if left to the whims of Mother Nature or an unsuspecting skier or snowboarder, might come crashing down while guests are on the slopes.
While recent storms piling snow in the mountains were a welcome sight to local ski resorts after a lean start to the season, they also present challenges to those charged with making the experience safer for everyone.
"Most of it is done in the dark or near dark," said Rod Kelly, mountain manager at Powder Mountain. "We're out before sunup to get it done before customers arrive."
Considerable resources are spent every winter on avalanche control at local ski areas.
Mike Jenkins, operations manager for safety and snow control at Snowbasin, said as many as 42 full-time employees devoted to avalanche control will be at the resort on a "full-control" day, when hazardous conditions are at their peak.
Snowbasin's avalanche control workers are busy about 30 days each season, Jenkins said.
"There's generally some level of avalanche control whenever we get at least six inches of snow and windy conditions," Jenkins said.
Every avalanche within resort boundaries is recorded, whether man-made or natural. Details such as time, location, and weather conditions are recorded in a database and the information is used in future training.
Snowbasin and others use a variety of equipment and tactics to minimize avalanche danger. Most resorts utilize both passive and active approaches.
In the passive approach, workers use signs, gates and ropes to warn visitors and limit access to questionable terrain.
"It's passive because we don't do anything to change or mitigate the actual hazard," Jenkins said.
Active approaches include the use of explosives, mortar shells, or other devices to intentionally trigger an avalanche and thus clear hazards.
Many resorts, including Snowbasin, use a Gazex brand system. In a Gazex system, oxygen and propane gases are mixed and piped through a portable system to a desired location, where they are ignited to create explosions of the desired magnitude.
After the explosions and resulting avalanches, patrollers conduct "slope cuts," where they traverse a slope on skis to determine how stable it is.
In general, more snow equals more avalanches. As of Thursday, the U.S. Forest Service's Utah Avalanche Center had recorded 47 in December, about of half of which occurred after heavy snowfalls that began last week.
Avalanches occur when new snow falling from the sky or blown by wind accumulates on top of an older, weaker layer of snow, causing the underlying layer to buckle and sending the new snow thundering downhill.
Despite the recent snowfall, certain terrain within Snowbasin boundaries is still off-limits because a weak layer of older snow from October remains on some north-facing slopes, Jenkins said.
Avalanches can happen on slopes measuring 35 degrees or steeper. A typical dry-snow avalanche reaches 60 to 80 miles per hour within five seconds -- an acceleration rate that would make many sports cars envious.
Wind is the biggest factor in creating dangerous avalanche conditions, said Bruce Tremper, director of the Utah Avalanche Center, which has offices in Salt Lake City, Logan and Moab.
Wind can pile snow on a given slope up to 10 times faster than natural snowfall, quickly creating new hazards.
Contrary to popular belief, avalanches are not triggered by noise, but usually by treading in hazard areas, Tremper said.
"With avalanche accidents, the victim or someone in the victim's party triggers the avalanche over 90 percent of the time," he said.
There is some debate as to whether skiers or snowboarders are more likely to trigger avalanches. Jenkins said a recent study from Canada found that wider equipment rides higher in the snow and puts less stress deep into the snowpack, suggesting that snowboards may be a less likely trigger.
However, snowboarders tend to turn in wider swaths than skiers, exposing them to more potentially weak patches. A skier with an expert parallel technique skiing in a relatively straight downhill line is probably the safest, he said.
"But that's not something we base our decisions on," Jenkins said. "Any area that we determine as a potential hazard will be off-limits to everyone, regardless of what's on their feet."
On average, 20 people are caught in Utah avalanches each year, resulting in four deaths. Most avalanche victims are skiers, snowboarders or snowmobilers in the backcountry.
So far, there have been six avalanche deaths in the state in 2007. Four of those occurred in a five-day span in February, including one near Snowbasin, when a skier went out of bounds.
There are no avalanche control efforts in the backcountry, and no requirements for who can go there.
"Our biggest worry is that our lifts go right to the boundary of the backcountry," Jenkins said. "I believe an open boundary policy is a good thing, but I'm afraid some people have no business going out there."
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