BUTTE - A giant boulder has been a giant pain in the neck for Butte’s Department of Transportation crew, who have spent the past several weeks trying to break it apart, but now they’re using a new technique that they’re confident will bust this bad boy up.

“This one is way bigger than we can handle,” said Butte District Maintenance Chief Jim Pesanti.

WATCH: Butte DOT Uses Innovative Technique to Bust Giant Boulder on I-90

The boulder fell onto the side of the westbound lane of I-90 on Homestake Pass near Butte earlier this year. The dump truck-sized boulder proved too hard to break apart.
“We rented an excavator with a jackhammer attachment on it. It ruined the point. It’s hard,” said Pesanti.

The crew decided on a technique called Boulder Buster, which involves drilling deep holes in the rock and splitting it with a controlled explosion.
“I’m confident it will be gone this afternoon,” he said.

The Boulder Busting technique works by crews putting four of these four shells into the water filled hole that they drilled into the boulder, then they’ll use a primer to set these shells off and the hydraulic pressure from the blast will hopefully split the boulder.
“It’s the water pressure that blows the rock apart. And with this you don’t need a blasting license, so it’s really easy for us now, if this happens again, take care of the situation a lot quicker,” said Pesanti.

The first blast was a success.

“It did exactly what we wanted … broke it in half. Now, we’ll break each half in half. We’ll be in good shape,” said Pesanti.

It took five more blasts to finally get the boulder down to sizes that could be moved off the highway. Traffic was temporarily blocked on both sides during the blasting.