Sustainability, Cooperation At The Heart Of 'Mount 402' Dirt Mound

Dec 10, 2018

In case you missed it, Colorado has a new mountain. But it's not near Breckenridge or Vail, and there's no skiing allowed.

Mount 402 sits just off Interstate 25 near one of the Loveland exits. It's a part of the ongoing highway expansion between Fort Collins and Johnstown, and it has an unusual backstory.

Shortly after flooding devastated sections of the Big Thompson Canyon in September 2013, an army of trucks and cranes rolled in to begin rebuilding the area.

Promotional video produced by the Colorado Department of Transportation captures how massive the undertaking was.

To carve out space for the new road, crews blasted out large sections of the canyon, creating a lot of rubble.

At the same time, CDOT managers were also planning I-25's expansion between Fort Collins and Johnstown. Managers from the two project teams got together and decided to make the best of the situation in front of them: They decided to share.

Crews piled up the excess rock generated from the canyon rebuilding, hundreds of thousands of tons of it. They then fed it through a machine that grinded it down into finer material and, one dump truck at a time, carried it to a spot next to Highway 402 near Loveland.

The view of I-25 from the top of Mount 402.
Credit Matt Bloom / KUNC

Samantha Overton-Katz, an engineer on the I-25 team, said the pile has grown to be about five stories tall with a total volume of about 220,000 cubic yards of crushed rock. The material is called aggregate, a commonly used ingredient in construction projects. It's the stuff that goes underneath a paved road.

CDOT is adding a third lane on north and southbound lanes of I-25 between Fort Collins and Johnstown and the project will take a lot of aggregate.

"We really do need some people looking ahead to say, 'Where can those materials be used and how can we reuse materials?'"

The mound's size and proximity to the highway led to its playful nickname, Overton-Katz said.

"I actually don't know who named it," she said. "But it kind of makes sense just being next to 402. So, I think it just naturally got its name of Mount 402."

She added that Mount 402's proximity to I-25 also helps speed up the project by making the aggregate easier to move.

"Because the (I-25) project just isn't just here at 402," she said. "It goes all the way up through Fort Collins. So instead of taking it from the canyon, trying to get through town, then get on the interstate, then get to our site - it's just much easier to have it right next to 25 so you can load it and then be on your way."

She also stressed that the mountain is not for hiking.

"You don't want to be that person that gets run over or anything," she said. "So definitely stay out of the area. There's a reason it's called a construction zone."

Building sustainably

On a recent drive from Denver to Fort Collins, Brian Dunbar craned his neck to glance at the giant mountain of dirt outside. It was Mount 402.

Brian Dunbar is director of Colorado State University's Institute for the Built Environment.
Credit Matt Bloom / KUNC

Dunbar, director of Colorado State University's Institute for the Built Environment , which works with governments and companies to build more sustainable infrastructure projects, said he was thrilled to learn the material was recycled.

"Sustainable road construction is all about creating durability, using local materials, using renewable energy and lowering our carbon footprint," he said. "That's an important thing for all of our environment, our state, our cities and all the people in them."

Dunbar added that recycling waste materials from natural disasters like floods and wildfires saves money, energy and time. But not a lot of communities think about it.

"Often people are in a hurry to clean something up and so too much of it goes to the landfill," he said. "We really do need some people looking ahead to say, 'Where can those materials be used and how can we reuse materials?'"

­­The expansion of I-25 is just getting started. In spring 2019 CDOT will close the Highway 402 exit for four months to rebuild the interchange.

As for Mount 402, it'll slowly shrink. In its place crews will build a new Park-n-Ride.