A crew on Sunday blasted one of two boulders that has shut down Colorado Highway 145 north of Dolores for two days, according to the San Miguel Sheriff’s Office.
Trucks have begun hauling the fragments away and will continue Monday, the Sheriff’s Office said on Facebook.
The section of Colorado 145 about 10 miles north of Dolores remains closed, and a temporary bypass lane was being build around the boulder. The Colorado Department of Transportation said earlier Sunday that it hoped to open the bypass Tuesday or Wednesday.
The boulders closed both lanes of traffic at mile marker 21, about 10 miles north of Dolores, about 4 p.m. Friday.
On Saturday, officials assessed the ridgeline above the highway for additional threats. CDOT had two priorities: to “patch the damaged road” and to ensure the stability of the rock ridge formation.
“A geo-technical crew conducted a ground and aerial investigation of the steep terrain earlier today and determined rock scaling is needed,” CDOT spokeswoman Lisa Schwantes said Saturday. A team was airlifted to the ‘brow’ of the ridgeline to clean and clear loose rock that has been found on the face of the ridge.
Additionally, loose and unstable rock was cleared from the mountain slope.
By Sunday, a crew had finished scaling the top of the ridge to ensure it was stable, and began drilling blasting holes on top of one of the boulders.
The geo-technical crew calculated that 15 to 20 holes, each 15 feet deep, were needed to be drilled vertically into the rock, Schwantes said Sunday. The holes were then filled with explosive charges to pop the rock into smaller chunks which can then be hauled away.
An earthwork ramp was built to the top of the boulder on the highway to drill holes to place explosives so it could be “boulder blasted” into smaller rock for removal, Schwantes said. The boulders were too large to move.
Crews are building a temporary, dirt bypass road so the highway can be reopened to alternating, one-lane northbound and southbound traffic. The temporary road could open Tuesday or Wednesday, unless problems crop up, Schwantes said.
The boulder on the highway was estimated to be 48 feet long, 18 feet wide and 18 feet high. It weighs about 2.3 million pounds, according to Schwantes. The other boulder crossed the highway and “blew out an eight-foot trench.” It was estimated to be 50 feet long, 50 feet wide and 26 feet high and weigh 8.5 million pounds.
Rain Monday could delay efforts to remove the boulders. Up to 0.1 inch was expected at lower elevations, with snowfall in Silverton and Telluride and 4 to 6 inches above 9,000 feet in the San Juan Mountains.
Warm and breezy under strong SW flow with gusts of 20 to 30 mph and isolated showers this afternoon. Unsettled weather returns Monday night. pic.twitter.com/Man5UkCfUR
— NWS Grand Junction (@NWSGJT) May 26, 2019
It was unclear how long work to clear the boulders will take.
“There are a lot of unknowns right now,” Schwantes said Sunday. “We don’t know how long it will take to drill the holes, and then we have to remove the rubble, and the rain could delay things.”
The stretch of highway remained closed Sunday, and the CDOT maintenance division was redirecting traffic.
Colorado 145: Alternate routes
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The closure made travel tricky during the holiday weekend in Southwest Colorado. Colorado 145 was identified as an alternative route for drivers traveling between Durango and Ouray on Saturday morning, when U.S. Highway 550 was closed from Purgatory Resort to Silverton for the Iron Horse Bicycle Classic. The highway also is a main route to Telluride.
The slide occurred about 4 p.m. Friday and knocked down a power pole. No injuries were reported, and one vehicle was damaged. Traffic was redirected.
Sheriff’s Office Detective Rick Shadden on Friday estimated the boulders to be the size of a “two-story house.” He said the slide was largely due to recent precipitation.
Empire Electric was notified, and the power line was de-energized. The power outage initially affected residents from a few miles south of the incident up to Rico.
One family stopped by the rock slide had been transporting horses from Arizona up through Dolores via Colorado 145. Space at the Montezuma County Fairgrounds was provided for the animals, Shadden said.
The Dolores Fire Department, Cortez Fire Protection District, Colorado Department of Transportation, Colorado State Patrol and Montezuma County Sheriff’s Office responded to the incident.
Patrick Armijo contributed to this article.
Colorado 145: Alternate routes (PDF)
