By MARK SIMMONS
Shooting explosives into mountain ridges and letting nature take its course are two methods the Utah Department of Transportation uses to keep canyon safe for motorists during winter storms.
UDOT used such methods last week to fight heavy snow from packing above canyon roads.
Steve Conger, UDOT's avalanche safety official for Big and Little Cottonwood Canyons, said when a snow storm hits he typically flies a helicopter over the mountains to find where the slides will start.
'After years of studying avalanche behavior, we know where a snow slide will tend to start its descent,' he said.
Conger said they know how snow slides will occur from the beginning of the snow season on.
After UDOT officers decide where the potential snow slides will begin, they shoot explosives down into the pack to 'shake the carpet and break loose the weaknesses,' Conger said. They only shoot where an avalanche may actually cross paths with canyon roads.
Not all explosives are dropped from a helicopter, Conger said. Some fixed mount artillery is shot from the ground into danger spots.
Another method of keeping motorists safe from harm is simply closing a road temporarily to let the avalanche fall its natural descent over the road.
Despite UDOT's efforts, some avalanches slip past their notice before they can get to them. Heavy snows caused a couple avalanches onto canyon roads last week.
One avalanche in Little Cottonwood Canyon descended upon a couple driving home from skiing Thursday afternoon. The north fork of Provo Canyon by Sundance was another site of minor slides.
The Bronco Jessica Hernandez and Hayes Hill were riding in came within three feet of the edge of the road when the avalanche struck.
Hill said the snow blasted through the passenger side window onto him and the truck filled waist deep with snow. But they got out of the truck safely. Salt Lake County Fire Captain Bill Brass reported that Hill had minor facial cuts and scratches and Hernandez was uninjured.
Brass reported another sport utility vehicle ran off the road behind them in the embankment, but the two men inside escaped unharmed.
The road up the canyon was closed for three hours. Meanwhile, helicopters shot explosives into snow-packed ridges to break up the excessive snow pack in avalanche-prone areas. During that time, another small avalanche fell above the first.
The road was reopened shortly around 6:30 pm to let skiers get out of the canyon. It closed again overnight through Friday morning.
Experts at the U.S. Forest Service's Utah Avalanche Forecast Center said the avalanche that landed on Hernandez and Hill likely fell about 3,500 feet to its destination on the canyon road. On a scale of 1 to 5 they said it was a Class 4 avalanche. They said the avalanche likely fell due to high ridgeline winds combined with the heavy snowfall.
The road to Sundance up Provo Canyon was closed Thursday afternoon after snow tumbled onto that road as well. UDOT worked to clear up the mess.
Rip Griffith is an independent contractor who oversees the avalanche risks in the Provo Canyon. He flies a helicopter into the mountains over the Provo Canyon and Sundance area and shoots explosives wherever there is a potential threat of avalanche.
However, the threat of avalanches in the canyons were very low risk Tuesday, said Seth Shaw at the Avalanche Forecast Center Tuesday morning.
Skiers and others planning on driving into canyons in the Wasatch Front can call the Utah Avalanche Forecast Center to determine the most up-to-date conditions. The forecast is updated at 7:30 am daily on their hotline at 378-4333.