20 boulders rip through I-70; no one hurt in midnight slide
State highway crews cast frequent and wary glances toward the cliff above them Monday as they scrambled to clear a jumble of fallen boulders that closed a major interstate highway through Glenwood Canyon.
Despite a gaping hole in the pavement and other damage caused by the rockfall, it’s the threat of more boulders tumbling from the canyon wall that may determine whether Interstate 70 can be reopened later today.
Colorado Department of Transportation spokeswoman Stacey Stegman said one rock in particular that looks in a photograph to be about 20 times as large as the geologist who was inspecting it has fractures around it and needs to be brought down.
“In a perfect world,” it will be dealt with today and one-lane travel each direction through the canyon will be allowed by the day’s end, Stegman said. She said she’s pretty hopeful that can occur.
Meanwhile, I-70 is closed for 17 miles between Glenwood Springs and Dotsero and motorists are being forced to make a detour of at least 200 miles incorporating U.S. Highway 40 and passing through Steamboat Springs.
Highway officials say about 20 boulders fell onto about 100 yards of the interstate a little after midnight Monday just west of Hanging Lake Tunnel. Rocks punched several holes into the roadway, part of which is elevated above the canyon wall, and the largest hole is one about 10 feet by 20 feet in size.
No one was injured and no vehicles were damaged, although Stegman said two semitrailers came across the scene shortly afterward and had to be turned around.
The rocks ranged from 3 feet to 10 feet in diameter. Crews used dynamite to splinter larger boulders, including one weighing about 66 tons, into smaller pieces that could be hauled away.
Meanwhile, geologists made a two-hour climb up the canyon side Monday to determine the likelihood of more rocks falling. Stegman said crews typically bring down threatening rocks through means such as blasting or inflating an airbag that loosens them. She said they presumably would try to dynamite the rock that concerns them to shatter it so it doesn’t cause more major damage to the highway as it falls.
As Joe Elsen peered into the biggest of the holes left behind by the rock, it brought back memories for the program engineer in the transportation department’s Glenwood Springs office. He saw similar damage in almost the exact same location after a rockfall on Thanksgiving Day of 2004.
Although it took only a day to reopen the interstate to two-way travel then, repairs required a couple of months, Elsen said. Stegman said the repairs cost about $1.2 million.
Elsen said Monday’s rockfall damaged fewer 23-foot-long retaining wall panels than last time. The state also may benefit from the lower bids that have been typical since contractors have struggled to find work as a result of the recession.
Whatever the repairs cost, they will begin soon, under emergency contract bidding provisions. Engineering and planning work will be occurring this week.
“We’re looking forward to getting a quality contractor in here to make the repairs in a timely manner,” Elsen said.
No protective fence is in place above the part of the interstate hit by the rockfalls Monday and in 2004, but one may be considered now, Stegman said. She said the 2004 rockfall came from higher up the canyon wall and wouldn’t have been stopped by a fence.
“This one is a little bit lower. I think they’re going to be looking at that,” she said.
Monday’s incident came at a time of year when there’s high rockfall danger because of thawing and freezing cycles that widen fractures and loosen rocks.