Sometimes when you’re driving on a long trip, it feels like the road will never end. But on Oct. 8, 2011, a near half-mile stretch of Utah’s SR-14 actually came to an end when a massive landslide swallowed up the road. The landslide dumped nearly a million cubic yards of debris — 100 ft. deep in some areas — down the mountainside.
Located in Cedar Canyon along the route between Cedar City and Cedar Breaks National Monument in southern Utah, the road was going to need some huge equipment to reconstruct a passage for motorists who depend on the road on a regular basis, as well as those who would be traveling through the area when tourist season ramped up again.
The Utah Department of Transportation (UDOT) immediately began aerial surveys and piecing together funding scenarios to move the monumental work forward while also assembling a design team that would pull in construction expertise geared toward massive earth removal, according to Kevin Kitchen, public involvement manager, UDOT.
“Within a few weeks the Utah Transportation Commission allocated $3-million toward the project,” said Kitchen. “Several design variations followed while geotechnical and additional survey data was collected under winter conditions and fed to the team. Environmental documentation, application for emergency funds, right-of-way acquisition and risk analysis were ongoing in a race to provide access through the landslide at the earliest possible date.”
Big Slide Means Big Iron
Kiewit Infrastructure West was awarded the $11-million base contract to remove the slide debris, establish a temporary roadway, pave the roadway and make other safety improvements. Kiewit also was given the job of addressing other trouble spots along SR-14, including an active slide at mile post 17.
The first heavy construction equipment began arriving at the site on March 2. About 25 oversized tractor trailer loads and 10 regular loads of equipment were trucked to the site over the next two weeks. Kiewit’s Cat 5130 excavator with a 13-cu. yd. (9.9 cu m) bucket was the first to arrive on the site. It took 11 oversized tractor trailer loads to haul it there and required one 100-ton (91 t) truck crane to assemble it. In addition to the large excavator, Kiewit also brought in various excavators, rock trucks, dozers, articulating trucks, front end loaders, road graders and cranes. In all, approximately 25 oversized tractor trailer loads and 40 regular loads of equipment was hauled to the site and assembled. Once the equipment arrived and was assembled, the contractor began breaking up and hauling away debris from the site.
There were a lot of unknowns at that point. They didn’t know what they were going to encounter as far as rocks and boulders. The landslide contained many large rocks, some as large as buildings or 18-wheelers, which had to be broken up in order to haul them to the fill area. A Komatsu PC 400 track hoe with a 10,000 lb. rock hammer was used to break up the rocks to meet project specifications.
Keeping the road in its previous location would have required moving one million cubic yards (764,555 cu m) of material. Designers and the contractor decided that moving the road slightly north would require the removal of less than half that amount: 400,000 cu. yds. (305,822 cu m) of material. To put that into perspective, that is the equivalent of 40,000 regular dump truck loads. Another way to think of it is, if all that earth were placed on a football field, the debris would be 190 ft. (58 m) tall.
Moving the Project Forward
UDOT kept an online weekly update so folks could keep informed about the progress they were making on the project. The following gives the highlights of the story:
A couple of weeks after the equipment was set up, work started on building pioneering roads to access the top of the landslide. Kiewit used the Cat 5130 excavator, Cat D9 and D10 bulldozers, Cat 777 trucks and other heavy machinery.
They tackled the landslide from both the east and west sides of the road as well as at the foot of the slide area near the creek. Workers built access roads to move equipment to different areas of the slide so they could access and remove additional material and begin construction of the temporary roadway.
Besides replacing and improving the section of SR-14 affected by the landslide and implementing mitigation measures for that section, the Restore 14 project also addresses other smaller slides and erosion issues between mileposts 7 and 17. At milepost 9.7 crews were tasked with rebuilding the end of tunnel under SR-14 and restoring the shoulder, mitigating an active slide at milepost 10, and installing a wall to repair an active slide at milepost 17.
By the first week of April, workers were moving an average of 900 cu. yds. (688 cu m) of material an hour, though they expected that rate to increase significantly as the project progressed. Once they were able to get the haul roads created, and get a system in place, the work went more smoothly, depending on the material. Crews working on a drop structure in the water channel at the west end of the project placed 1,400 yds. (1,280 m) of rip-rap to protect the structure. Meanwhile, workers on the west end of the slide started seeding the top and seeding and mulching along the cut slopes of the main slide area.
Pre-emptive measures also were needed to stabilize the hillside farther west at MP 7.5 to prevent future landslides. At the main slide site, crews worked day and night excavating the area using the Cat 5130 and 777 trucks, with the goal of having the roadway open by June. Workers prepared for the installation of an earth stabilizing wall.
The excavated material from MP 10 was used as fill for the stabilization wall at MP 8.
The roadway at MP 17 is unstable and continually moving. In order to stabilize the roadway in this location, construction crews will install a 200-ft. (61 m) long soldier pile wall to keep the roadway in place.
Much of the work on the landslide was weather dependent. The construction team was ready to adjust production rates and crew size to make up for lost time due to weather delays. Fortunately for the most part the weather was on their side, and didn’t create many problems. They were shut down for just a couple of days in late March due to about a foot of snow.
By the beginning week of May, the mass excavation work was done, and the major pieces of equipment that were utilized during excavation, including the 777 trucks, were demobilized and parked at the bottom of the canyon. While this marked a significant milestone on the project, there was still a lot of work to do to get the road ready for opening.
Construction of the 3,300 sq. ft. (306 sq m) earth stabilizing wall was nearly complete. Crews set their sights on finalizing the roadway grade and getting ready to place road base in preparation for paving activities. Specifications called for a hard packed dirt road for motorists to go through by Memorial Day weekend, but due to their productivity, they were able to have a section of the road paved for the opening.
Crews opened the road on May 24, and had made more progress on paving than they had originally expected, so vehicles traveling through the canyon would have better access. One small section near MP 7.5 remained unpaved. Currently the road is opened only at night and on weekends. This will continue to be the schedule now through the month of July.
The Challenges of Geology
Despite finishing initial pre-emptive stabilization efforts in their original work contract, the mountain began to bulge out at MP 7.5, west of the main slide. UDOT approved additional excavation to further reduce stress loads in this area. Currently workers are hauling out an additional 309,000 cu. yds. (236,247 cu m) of dirt and rock from the upper slopes across the road, amidst occasional rolling boulders from the excavation. Doing the work during the day ensures the safety of workers and motorists and keeps project costs down.
Kiewit Infrastructure West is a subsidiary of Kiewit Corporation. Kiewit is accustomed to challenges. One of North Americas largest transportation contractors, they constructed some of the most difficult and picturesque miles of the highway system, including sections through Arizona’s Virgin River Canyon and Colorado’s Glenwood Canyon, the Eisenhower Tunnel through the Colorado Rockies, and the Fort McHenry Tunnel beneath Baltimore Harbor.
The company built more lane-miles of the interstate highway system than any other contractor, prompting Forbes magazine to call the company’s founder, Peter Kiewit, The Colossus of Roads.
Kiewit has worked with eight subcontractors on the project, with more than 60 workers on the site during the peak of work activities. The project is scheduled for total completion in September 2012, which will provide more travel options for the folks who work and live in the area, as well as those who are driving through to take in the views of this scenic byway.
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