The blast was expected to dislodge about 400 cubic yards from a Colorado mountain.
But the explosion along Highway 119 in Boulder Canyon Wednesday unleashed a surprisingly gigantic rockfall, sending roughly 8,000 cubic yards of blasted rock down the mountain and right into the road, Colorado Department of Transportation officials said in a news release. That means the blast brought down about 20 times more rocky debris than anticipated.
“A cubic yard is about the size of a normal washing machine,” officials said.
No one was hurt in the blast or rockslide “as the area was clear due to regular safety protocols during blasting,” according to the Transportation Department.
“There are local detours available and Colorado Highway 72 is the main way for people to bypass this area,” officials said.
The road “will be closed indefinitely” — and at least for a full day — as officials work to remove the obstruction the size of 8,000 washing machines, according to the news release.
Transportation officials said “some of the rock is too large to be moved and additional blasts will be needed to break it up before it can be taken away.”
The blasting carried out Wednesday was part of a flood control project. It wasn’t aimed to prevent future rockfall, officials said.
“We are blasting into the mountain to move more of the road on to bedrock so it will survive during the next major flood,” officials said.
Aerial video footage posted on Facebook by CBS Denver shows construction crews starting to dig into the massive pile of rock.
Officials said that they also “found another area of rock that was loosened in this blast that will need to be blasted out to ensure the roadway is safe for regular traffic. Crews will be working overnight through this process to clear the road as soon as possible.”