In June 2012, more than 10 inches of rain fell in two days on parts of northeastern Minnesota, saturating the ground and causing massive slope failures in the greater Duluth area. Minnesota Highway 210, through Jay Cooke State Park, was significantly damaged in many locations by landslides and in other locations completely destroyed by wash-outs. While emergency repairs in late 2012 restored portions of the highway for access to hydropower facilities and most park facilities, a large section of roadway remained closed due to unsafe slope conditions. Beginning in 2015, the Minnesota Department of Transportation (MnDOT) repaired and stabilized 74 discrete landslide sites totaling more than 28 acres of steep slopes along approximately 3.5 miles of the highway using a design-build contracting framework. The performance-based project allowed the contractor to use a large variety of site-specific geotechnical and structural designs to effectively stabilize the roadway and slopes. A robust monitoring program was used to evaluate the performance of each repair. The paper focuses in particular on the variety of design solutions and the associated challenges and benefits of multi-year continuous geotechnical performance evaluation for landslide stabilization.
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