On Tuesday, the Summit County Sheriff’s Office reported an avalanche in the Dutch Draw area on the canyon side of Park City Mountain, between the Peak Five and Ninety-99 90 lifts.
According to Andy Van Houten, director of snow safety at Park City Mountain, the avalanche occurred in a backcountry area.
“We’re working with helicopters from the Department of Public Safety,” he said. “We were able to establish that no one was involved. We investigated all witnesses and everything is fine.”
Van Houten is in great demand on the mountain. He has worked in avalanche control for 20 years and said an avalanche like Tuesday’s is an example of what happens in places without avalanche mitigation; for backcountry skiers, it can be life-threatening.
“We’re not doing any mitigation outside of the resort, so it’s 100 per cent on the user’s part; from a rescue standpoint, we do worry about it, but we’re not doing anything to mitigate the danger,” he said.
Van Houten’s team began working when most people were asleep to assess avalanche hazard.
“Our crews start showing up around 3 a.m. or 3:30 a.m., we start gathering snow information, weather information, we make plans, we have to start assembling the explosives,” Van Houten said. “And then generally most of our crew will show up around 5:30 in the morning, we load the lifts at 6, and usually the earliest we leave is the sun, it’s the first sun. So It’s usually around 7am, depending on the time of year.”
Early in the season, Van Houten said they were doing eight to 10 hours a day of avalanche control as conditions called for more explosives.He said it was not uncommon to hear gunshots around 4 or 5 p.m.
There are several ways to reduce avalanche risk. One is the ski cut, where the patrol will purposely slide quickly from the top of the slope on the right to the left. This will trigger an avalanche if the slope is crossed. This method is used for smaller slides; for larger ones, they bring dynamite.
Van Houten said a team of rescuers went out in groups of two or three with explosives in their backpacks.
“It’s a projectile booster, about the size of a large pot of soup, and it’s a Pentolite-TNT mix,” he said. It has a 120-second fuse strain. It’s basically like a little cardboard tube with a spark inside. That’s what ignites the end of the fuse when we pull it. So basically we either tie them up with string or throw them away. It’s like throwing a can of soup into a snowdrift. This is, this is a good shot, this is a good shot. But when it explodes, we’re usually so far away that we plug our ears and turn our backs on it a little bit. So we’re not, we’re not even close to it anyway. “
Avalanches can happen anywhere with slopes and snow, in other words, avalanches can happen anywhere. He said the slope angle is one of the big variables.
“Mainly, an avalanche can happen anywhere from 35 to 45 degrees, with 38 degrees being the bull’s-eye number there,” he said. Black or black trimmed runs, so those are the places people want to ski and those are our main focus.”
The final form of relief is called pure compaction, Van Houten said.
“The best thing we can do is make this terrain open to the public and make it skiable,” he said. “That’s why we’ve worked so hard to open up this terrain, you know, in a timely manner so we can have our guests ski there, and that’s what’s helping us, the kind of skis where all the snow breaks up in layers. “
Deer Valley ski patrol manager Chris Erkkila told KPCW that most of the explosives were used in the Empire Canyon area, specifically the Daly Bowl and Daly Chutes . He said patrols also used explosives in the Sudan, Mayflower and Mrs Morgan areas.
Erkkila said Deer Valley was working on explosives early in the morning to get it done by the time the first chairs were turned. They also use ski cutting as a mitigation technique. He said he’s seen both approaches unleash avalanches of all sizes.