Helicopter-dropped explosives trigger planned avalanches that shut down I-70 mountain corridor
It was undoubtedly a frustrating day for motorists heading to Summit County along Interstate 70 on Tuesday after a number of controlled avalanches wreaked havoc on roadways in the mountain corridor.
Early Tuesday morning the Colorado Department of Transportation began avalanche mitigation work in areas around the Western Slope, including at the Bethel slide path between the Eisenhower/Johnson Memorial Tunnels and Herman Gulch, at the Disney slide path above Berthoud Pass at US 40 and at Ten Mile Canyon near Copper Mountain.
But as the mitigation work began, primarily via helicopter bombing missions, CDOT got a lot more than they bargained for. A giant plume of snow descending from Mount Bethel covered eastbound I-70 with 8 feet of snow, and upwards of 15 feet on the westbound lane. The slide effectively shut down large portions of the interstate — about a 15-mile stretch from Silverthorne to Herman Gulch — well into the evening.
CDOT initially expected about a four-hour cleanup period, but due to the severe nature of the avalanche, things took quite a bit longer. Tracy Trulove, a spokeswoman from CDOT, said that the slide path went all the way down to the dirt, meaning CDOT crews needed to clean up debris like trees and rocks in addition to massive piles of snow. The avalanche also destroyed part of the cable guardrail along the side of the road, raising safety concerns for cleanup crews and substantially extending the cleanup.
“They discovered the cable guardrail still had tension in it, which is a safety concern,” said Trulove. “So that took us getting some of that snow cleared to get to the guardrail. It proved to be a challenge, because it was wrapped around culverts and things … but again, for keeping our team safe we had to get to a place where we could get to the guardrail and clear a path.”
Not long after the I-70 closure, CDOT also shut down US 6 at Loveland Pass, closing off any ingress or egress out of the east side of the county. At around 11 a.m., CDOT began another avalanche mitigation project on I-70 at Ten Mile Canyon — near Copper Mountain where a pair of natural avalanches closed down the road on Sunday — which again closed I-70 between Copper Mountain and Frisco for much of the day, and closed access to the west side of the county.
In addition to mitigation efforts in Summit, the controlled avalanche from the Disney slide path covered Berthoud Pass in snow for several hours, closing off the main alternative route in and out of the county and leaving CO 9 to Fairplay as the only alternative route available to drivers for most of the day.
According to representatives with CDOT, the controlled avalanches may not have been simply substantial, but also historic.
“These are paths that CDOT mitigates regularly, and we haven’t seen large natural events for some time,” said Ethan Greene, director of the Colorado Avalanche Information Center. “At the Disney slide path on US 40, the last time it actually reached the road was in 1957. … With Bethel on I-70, the last time we saw something of this size was in 1986.”
“There were pretty significant avalanches with every shot placement,” added Jamie Yount, avalanche program manager with CDOT. “So it’s been a very active day, and almost a historic avalanche cycle with big impacts in areas we don’t usually see them.”
While the mitigation efforts were certainly less than ideal on Tuesday, there’s still a chance there could be more in the area in the coming days as another snowstorm is expected to hit Summit County over the next week. And as exasperated as some travelers were at the lack of notice before Tuesday’s mitigation, they shouldn’t expect better notice next time.
Avalanche mitigation is a joint effort between CDOT and the Colorado Avalanche Information Center, which sends out individuals with CDOT crews daily — along with weather and avalanche forecasting — to recommend the timing of mitigation efforts.
Bob Wilson, a spokesman for CDOT, said that the department is actually prohibited from giving advanced notice of avalanche mitigation efforts, in large part due to the militaristic nature of their equipment and conditions set by the U.S. Army.
“It’s a security issue that started after 9/11,” said Wilson. “They’re dealing with live ordinance, some of it comes from the U.S. Army. It’s one of those things we don’t announce as a security precaution. So if somebody has other ideas, they’re not aware we’re going to be on the roadway with live ordinance.”
Wilson said that mitigation efforts typically aren’t announced until about 30 minutes before they begin. He continued to say that CDOT tries their best to avoid weekends, and tries to begin efforts at first light to lessen the impact on drivers, though things don’t always work out that way.
“As much snow as we’re getting you never know when we’ll need to get out there,” said Wilson. “It’s all about public safety.”
With very little notice before mitigation efforts take place, CDOT recommends travelers check COTrip.org and CDOT’s Twitter page for traffic information before leaving, and always properly prepare for the trip with a well-stocked emergency bag in case the worst should happen. For up-to-date avalanche forecasts, visit Colorado.gov/avalanche.
“We’re dealing with Mother Nature here,” said Trulove. “As much as we can forecast, we still have situations come up. … it’s just that kind of winter.”
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