Barrier Keeps Mud From Slide Off Hwy. 87

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If you’ve driven south on Highway 87 after the recent thrash of rainstorms, you may have noticed mud accumulating at the site of the March landslide and wondered if another landslide took place.

But don’t be alarmed because the Arizona Department of Transportation says the mud has not reached the concrete barrier wall and they continue to monitor the site for any movement.

“Our geological team from the ADOT Phoenix office visited the site on Friday (Feb. 13) and noted there was some mud that slid toward the southbound lane of the highway,” said public information officer Bill Williams.

“The mud did not reach the road or shoulder. A concrete barrier is sill installed between the southbound traffic lane and the shoulder, and the mud did not reach the barrier.”

In March, a landslide broke nearly 45 feet of ground, leaving the southbound lane of Highway 87 near milepost 224, six miles north of Sunflower, broken, uplifted and buckled. The highway was closed for six days and southbound lanes were reopened in late May.

Royden Construction crews of Phoenix have already installed a 4-foot-wide drainage pipe, concrete pilings and monitoring devices to measure any future movement in phase one of the project. Several of the concrete pilings are almost covered in soil as the hill continues to settle.

During phase two of the project, which is expected to begin in March, crews will create a 20-foot-high retaining wall with the pilings.

They will also install additional drainage pipes, excavate and reshape the embankments on both sides of the highway, add more shafts to prevent earth from moving toward the southbound lanes and construct rock and soil buttresses, Williams said.

Work will begin on phase two of the Slate Creek landslide repair project if the State Transportation Board approves a $2.37 million contract to Royden Friday. According to the contract, crews will have 115 working days, excluding weekends and holidays, to complete the project.

A study by the Arizona Geological Survey (AZGS) completed in November states the site of the landslide is on an ancient landslide deposit that occurred several thousands of years ago, one of four such landslide deposits in nearby hills.

AZGS could not determine what caused the ancient landslide site to collapse, but it could have been triggered, in part, by heavy rainfall on nearby Mount Ord.

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