A landslide that damaged Highway 87 four months ago and caused numerous road closures due to repairs has created another closure this week.
The Arizona Department of Transportation (ADOT) has closed one lane of Highway 87 for up to eight days, weather permitting.
On July 16 crews restricted southbound traffic to one lane between mileposts 224 and 226. One southbound lane will remain open as well as both northbound lanes, said ADOT Public Information Officer Bill Williams.
Crews will be installing a 4-foot wide pipe to improve drainage and further stabilize the slope on the west side of the highway.
The pipe is designed to channel rainwater away from the hillside and down into a natural drainage system at the bottom of the hill.
So far crews have installed concrete pilings that will connect to a large piece of metal, creating a retaining wall, Williams said.
Through the fall, ADOT will be working to stabilize the slopes on the west and east side.
"We did notice that the opposite side from the landslide needed some reinforcement and we'll be working on that," Williams said.
Engineers do not expect to close any northbouind lanes of the highway to make repairs because damages are not extensive. They are primarily maintenance issues dealing with slope reinforcement, he said.
A March 21 landslide, 20 miles south of Payson, originally caused several hundred thousand cubic yards of dirt to flow off the hillside and into the roadway.
The pavement buckled from the force of the dirt going down and under the roadway, pushing the road up.
The highway was completely closed for six days until the northbound lanes could be reopened. Both sides of the highway reopened in May.
ADOT has so far spent $3.6 million to make repairs and estimates once the entire canyon is finished they will have spent $18 million.
Part of the money comes from an emergency fund that was tapped into shortly after the landslide and the rest comes from state funding, Williams said.
As to what caused the landslide, an Arizona geological survey said multiple factors contributed.
Recent rainfall along with different types of rock plates moving against each other factored into the collapse, he said.
There is a natural spring in the area, but it was never discovered running down the slope, he said. It could have been a contributing factor.
There have never been any landslides on the highway before and they are extremely rare around the state, he said.
ADOT continues to monitor the area with sensing devices installed underground. In the past several weeks there has been minimal movement, Williams said. The sensors will be removed when the project is complete.