Rockfall mitigation work in Glenwood Canyon is wrapping up as crews complete the last of four rockfall barrier fences during the next week.

The project, which is in response to a major rockfall that closed Interstate 70 for nearly a full week in February, was initially planned to finish prior to Sept. 1, but crews are now expected to work until Sept. 6.

However, that will only mean one additional day of work since crews will not be working Friday through Monday during Labor Day weekend.

Additionally, both lanes of westbound traffic near mile marker 125 west of Hanging Lake Tunnel will be open during the holiday weekend. Traffic has been limited to one lane in the area, with the other lane being used for equipment staging. A one-lane closure might be necessary on Tuesday after the holiday weekend.

Repair and mitigation work has been ongoing — off and on — since the February slide, which resulted in the longest closure in the history of the interstate through the canyon.

The permanent rockfall mitigation project, which includes the barrier fences, started in May. Two alternating crews of about eight people have been working seven days a week for the majority of the project.

It has been a labor-intensive, physically demanding project, said Lee Barger, transportation team leader for SGM, a Glenwood Springs firm working on the project. At the same time, it’s also rewarding to get to work in such a scenic location and to work on a project that’s important to the community, with I-70 being a high impact corridor.

“This is a group of hardworking guys (who are) working on steep terrain,” which Barger compared to a double-black diamond ski slope.

Crews from Yenter Companies, which is based in Arvada and has an office in Grand Junction, have hiked up each day — navigating unstable talus fields where rocks can easily turn over under foot and which become slick after the late summer rains.

The crews have tied off ropes to help them climb up the steep terrain, which becomes a hand-and-knees scramble in many places.

“There was nothing easy about this project,” said Jonny MacFarlane, a Yenter foreman.

The last barrier fence to be completed is the highest, which project manager Jim Stepisnik said is about 300 feet up the northern canyon wall. All the heavy poles and materials have been placed with the help of a helicopter and crane, though much of the equipment had to be hiked in on foot.

The fences are strategically placed with a boulder’s trajectory in mind, said MacFarlane. The engineers looked at the terrain and projected where a rock would likely bounce and where it would come into contact with the ground.

Now crews are in the final stages of putting all the pieces together — stretching the lengths of ring net fencing and anchoring the fences to concrete bases.

In total the project used about 100 cubic feet of concrete, said MacFarlane. Digging the holes and pouring the concrete for the anchors was one of the more difficult parts of the project; crews ran a concrete hose up the rocky hillside, he said.

MacFarlane said he recently worked on a similar project in Minturn. Yenter also does a lot of rock scaling projects, a recent one being in Monarch Pass.

“We do get amazing views like this often,” said MacFarlane.

Glenwood Canyon already has about 40 rockfall fences in place, but this project is taking advantage of the latest technology developed by a Swiss company. These are the first 5,000 kilojoule fences to be installed in America, said Barger.

When the fences catch a rock the mechanism is akin to a fishing net enveloping its catch, he said.

“It’s an incredible design and we’re fortunate to be on the forefront of this technology.”