A rock- and landslide that shut down Berthoud Pass this morning was likely caused by rapid snowmelt and abundant moisture.
The slide happened about 6:30 a.m. on Berthoud Pass and initially shut down U.S. Highway 40 in both directions, according to the Colorado Department of Transportation.
Rocks, dirt, trees, water and boulders — including a rock the size of a pickup truck weighing about 16 tons — were swept onto the highway about seven miles east of Winter Park.
“More often than not, that’s an indication of snowmelt and wet ground,” said Stacey Stegman, a CDOT spokeswoman, of the scope, and material mix, of the slide.
A CDOT geologist inspected the mountain Monday above the slide area to evaluate the stability of the slope and determine what, if any, mitigating work should be done.
“The ground is saturated, and it just starts to slide a bit,” Stegman said. “The hard part right now is looking for drainage patterns because a lot of it is underground.”
Berthoud Pass is among the most traveled passes in Colorado, and it’s also among the most watched by highway officials because of the heavy traffic volume it absorbs.
At about 11 a.m. Monday one lane of U.S. 40 was reopened. Eastbound and westbound traffic were allowed through, but drivers had to take turns going through in each direction.
At about 2:40 p.m. a second lane reopened and highway officials expect to open a third lane later today. The highway span usually carries four lanes of traffic through the area pounded by the slide.
CDOT earmarks $4 million annually to deal with falling rock mitigation, Stegman said, and the highway department has identified 750 sites statewide that have heightened potential for rock slides. Crews work on five to seven scheduled projects a year, like the ongoing rock scaling operation on I-70 above Georgetown.
Heavy traffic volumes below or along threatened areas increase the likelihood of mitigation efforts because that’s where slides raise the most concerns for public safety.
Mitigation efforts, mostly rock removal, were done earlier this year on Berthoud, but not in the same area where Monday’s slide took place.
No one was injured in the slide.
Crews clearing the debris on Monday kept an eye on the mountain above as they worked.
“It’s as safe as any highway we have in the Rocky Mountains,” Stegman said. “It’s typically not a problem. It’s just so wet from snow melt, it’s dripping mud.”
Kieran Nicholson: 303-954-1822 or knicholson@denverpost.com.
