BOULDER COUNTY, Colo. — Colorado Highway 7 between Lyons to Allenspark reopened Monday after being closed for 12 days.
The highway closed because of a rockslide about eight miles east of Allenspark on June 14.
The Colorado Department of Transportation (CDOT) had to close Highway 7 at mile point 23 between Spruce Drive and Old St. Vrain Road, just past where the Peak to Peak Highway meets Highway 7.
CDOT said its crews spent nearly two weeks pulling down loose rock from the highway's rock slide wall and blasting boulders the size of fire trucks. More than 180 truckloads of rock were hauled off from the location.
On Friday, CDOT said that after clearing more than 90% of the rocks that slid onto the road, geotechnical experts discovered a deeper fracture area on the mountain that forced the extension of the closure through Monday.
Highway 7 rockslide
The cause of the slide was likely from the rainy weather pattern this spring. That area has not seen as much rain as the lower Front Range metro areas, but the precipitation has still been well above average since May 10.
“We recognize the impact this closure is having on residents and others who use this road every day,” CDOT Regional Transportation Director Heather Paddock said last week.
“Understanding the geology of rock formations is a true science. Predicting when failures occur requires modern technology to measure movement as well as visual inspection. Once the massive rocks were cleared away from the initial slide area, additional fracture lines were exposed,” said Paddock.
The rocks in the new fracture area had to be brought down by a system that uses air bags in the open crevices that are expanded to bring down the rocks.
“These fracture lines have been monitored visually over the past few days and movement is occurring. Geotechnical experts know these rocks will come down naturally in the near future," said Paddock. "CDOT’s approach to eliminate the risk and hazard to the traveling public is to remove these in a controlled environment to keep everyone safe.”
“That’s how loose these rocks are. We don’t need to blast,” Paddock said. “The only drilling and blasting we are doing is to break up the large boulders that come down so we can haul them away.”
CDOT said it maintains roadways over 35 mountain passes and have previously identified high-risk rock walls, including several on Colorado Highway 7. This spot was not one of them.
That part of Colorado Highway 7 was just rebuilt last May after it was destroyed by flood in September 2013.
> WATCH: Sky9 video shows rockslide on Highway 7
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