Despite mitigation, Mount Harris Canyon slides still happen
STEAMBOAT SPRINGS — Crews from the Colorado Department of Transportation were back at work Sunday, March 8, clearing large boulders and rocks from U.S. 40 Highway in Mount Harris Canyon despite the department’s best efforts and millions of dollars spent on rockfall mitigation.
“It would be challenging to eliminate it entirely, but we are working hard to reduce that risk as much as possible,” said Elise Thatcher, CDOT’s Region 3 communications manager. “We only have the roads open when it’s safe to drive on. During the time when the road was closed Sunday, we removed rocks from the road and assessed to make sure the road itself was safe to drive on and that it wasn’t damaged. We also reviewed whether there were any remaining loose rocks up above that were likely to come down.”
The rockslide caused a section of U.S. 40 east of the Hayden Station to be closed for over five hours Sunday.
Since 2001, CDOT has spent between $1.5 million and $2 million mitigating rockfall in Mount Harris Canyon, which is located between Milner and Hayden. The canyon was the site of Sunday’s closure. The mitigation work included scaling, or bringing down, 480 yards of loose rocks, erecting a rockfall fence above the road and installing 212,660 square feet of wire mesh, which is called rockfall netting.
“Those projects have mostly been on the smaller side with our biggest one being in 2012,” Thatcher said. “That was a little under a million dollars.”
She said the netting serves to redirect rockfall and debris into a nearby ditch rather than allowing the rocks falling down on the highway. On Sunday, the netting was not enough to stop the slide, but Thatcher said it may have reduced the damage.
“The netting system is not meant to contain the size of the slide that occurred there,” Thatcher said. “What the netting did do was prevent rocks from bouncing off the side of the cliff and landing directly in the road. With the netting there, the rock stayed behind the net until it hit the ditch, overwhelmed the ditch then rolled onto the road. In this case, there was too much rock to be contained within the ditch.”
She said she believes the work in the canyon has been a success. Highway maintenance crews have had to remove fewer rocks from the roadway, and the office that oversees rockfall mitigation has responded to the canyon less than before the 2012 project.
Prior to 2012, rockslides and rockfall were a regular occurrences in the canyon. In March 2010, a woman traveling from Craig to Steamboat for work was killed when a boulder fell on the passenger side of a car in which she was riding.
- Call Colorado State Patrol at 970-824-6501
- Make a note of the nearest mile marker, approximate size of the rock or rocks — softball, basketball, refrigerator, car, etc.
- Also report how many rocks are in the roadway. Don’t notify CSP about small rocks unless there is a constant stream of rocks in a particular location.
Thatcher said CDOT was already planning on adding more rockfall netting in the canyon. Because contractors are coming to repair damage to the netting from Sunday’s slide, it may make sense to add more netting at this time.
In the meantime, she said drivers need to be aware that the freeze-thaw cycle can lead to loose rocks, rockfall and slides this time of year. Drivers need to remain alert and be on the lookout for rocks in the roadway, especially in the spring.
“We certainly appreciate that there’s a lot of activity on the roads up there, and that living in Northwest Colorado you are very dependent on the roads in order to get to the places that you need to go to whether it’s for work or a doctor’s appointment,” Thatcher said. “So making sure the road is safe to drive on is extremely important to us.”
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