Harnessing water pressure to breakup boulders

By Doug Adamson

The power of water in the form of torrential rain can bring mammoth-sized boulders down onto state highways. The power of water can also be used to help get rid of them.

Sometimes, boulders that come down hillsides are too big to lift, even with an excavator. Maintenance crews then have to break apart large boulders using jackhammers, which leads to traffic delays. Explosives could be used, but they pose additional risks.

Enter the Boulder Buster™ - a portable rock-smashing tool that’s slightly bigger than a shoe box and uses pressurized water to break up or ‘blast’ large boulders.

But the ‘blast’ is not what you might think. Forget about Hollywood explosions. There are no giant booms, fireballs or flying debris. That’s the benefit.

Instead, the process produces a muffled ‘poof’ that might not even startle a dog, let alone the people who live nearby. The non-detonating rock-breaking tool – which uses just a bit of gunpowder and water pressure - breaks a rock open like an egg. A heavy plastic cover limits flying debris.

This tool can be safely used near pipes. It also is safe to use near structures and much safer overall when compared to something like dynamite.

Much safer compared to dynamite, the Boulder Buster™ breaks
up boulders with a muffled ‘poof.’
During a recent training session on a windswept State Route 112 in Clallam County, maintenance staff took advantage of a Boulder Buster™ training session to clear the roadway shoulder of several big boulders that had come down in a recent slide. Maintenance crews who took part in the training exercise became qualified to teach others at our agency how to safely use the Buster.

After the rock-busting session was complete, the remnants of the boulders were used as fill for another project.

So, how does it work?

First, we drill a hole about 75 percent through the boulder. Then, we pour the “secret ingredient” – water – into the hole.
Pouring water into the breech body
Next, we place the “breech body” inside the hole. It’s similar to a cast iron vase that has no bottom. A heavy plastic cover, similar to an industrial-sized door mat, then goes over the breech body, followed by a single shotgun shell-sized cartridge.

A representative from Boulder Buster™ leading the training.
A metal top that works as the firing mechanism is screwed to the top of the boulder. We then attach a lanyard, go a safe distance away and pull once on the “trigger” – a rope.

The boulder busting aftermath.
With the telltale ‘poof,’ the boulder breaks apart.