Ten inches of rain that fell over two days in June 2012 saturated the ground and caused massive slope failures along Minnesota Highway 210. These failures compromised the road’s structural integrity in several areas and washed out other sections. The Minnesota Department of Transportation (MnDOT) selected the team of Veit & Company, Inc., Barr, and SRF Consulting to repair and stabilize 74 sites and rebuild approximately 3.5 miles of the highway, which runs through a state park.
Barr began by conducting site mapping and geotechnical investigations of soil, rock, and groundwater conditions to inform slope stabilization designs. We completed more than 120 soil borings, performed in-situ strength testing, and installed inclinometers and piezometers to monitor groundwater pressure and ground movement. We then conducted laboratory testing to develop soil-water characteristic curves and permeability and strength parameters for use in seepage and slope-stability modeling.
Our repair and stabilization designs use anchor-reinforced vegetated slopes, soldier pile walls, geocell toe buttresses with slope grading, and geosynthetically reinforced slopes. These methods lessen the risk of future failures, allow safe travel on the rebuilt highway, and will require minimal long-term maintenance. Barr also developed and oversaw installation of a state-of-the-art monitoring and instrumentation system that included more than 2,700 sensors to verify the integrity of the highway and surrounding slopes now and in the future.
The highway reopened in 2017. The reconstruction project won a 2019 Grand Award for Engineering Excellence from the American Council of Engineering Companies of Minnesota and an Honor Award in the ACEC national competition.