SR 89A Jerome: Emergency Wall Repair

Due to heavy rainfall, a dry-stacked rock wall experienced partial failure in the area of Jerome, an old mining town on Highway 89A between Prescott and Flagstaff. This failure undermined the northbound lane of Highway 89A. As a precaution, ADOT closed the roadway which serves as a major connection between Prescott and the Cottonwood/Camp Verde area. Hence, time was a crucial factor in the remediation effort.

The Arizona Department of Transportation (ADOT) retained NCSG to develop a plan for the emergency stabilization of the surficial slide failure and the permanent remediation of the undercut roadway.

NCSG designed a soil nail fix to stabilize the slope. ADOT opted for rebuilding the dry-stacked rock wall instead of using a carved shotcrete facing. The tight timeline of the project prevented NCSG from doing an in-depth soil investigation, so available literature on previous investigations and geology had to be employed. Also, in the absence of survey data, the soil nail wall had to be designed based on the soil nails superimposed on digital photographs taken by ADOT. The soil nail were then field adjusted during construction.

The scope of work included the following tasks:

• Site reconnaissance and review of pertinent literature
• Soil nail wall design based on photographs
• Field test supervision

This project has been completed and is in service.