A 150-foot section buckled and sank four feet. (Source: ADOT)
PHOENIX (CBS5) -
The final step is underway that will lead to the best solution to restore the landslide-damaged U.S. 89 highway, the Arizona Department of Transportation said.
A 150-foot section of the highway buckled and sank four feet on Feb. 20. ADOT said at the time the event might have been caused by a "geologic event."
Heavy construction began Tuesday as crews begin a two-week project to cut a pathway down the slope.
The access path will allow the geotechnical engineers to dig pits, between 20 to 40 feet long and 10 to 15 feet deep, which will provide critical information about any movement that may be present at the base of the slide, ADOT said.
The excavation work is necessary because it will lead to recommendations by the geotechnical team on what options are available within the site to realign the roadway or rebuild the existing roadway.
"Prior to this, our drilling crews were only able to access this area via helicopters," said Steve Boschen, ADOT deputy state engineer of design.
ADOT's geotechnical investigation at the U.S. 89 landslide site is the first phase of the solution.
Crews are monitoring the stability of the slope and the ultimate repair of the highway will be based on the results of the geotechnical investigation. Efforts also continue on exploring the use of Navajo Route 20 as a temporary detour route while U.S. 89 repairs are addressed.
Click here for the ADOT blog with the latest information on the project.
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