In 2009, the Michigan Department of Transportation (MDOT) became concerned about ongoing slope movements adjacent to a segment of M-222 located on outside bend of the Kalamazoo River in the City of Allegan, Michigan. Over the next couple years, continued river erosion and seasonally wet springs caused 8- to 10-foot high scarps adjacent to M-222, condemnation of a home, and several large block slides into the river. In the early spring of 2011, MDOT secured their first Construction Manager/General Contractor (CMGC) delivery method contract to protect M-222 and repair the slope. Improvements included constructing an up to 26-foot tall retaining wall, re-grading the roughly 70-foot high slope, and armoring the toe of slope. The improvements used were selected based on assessed risks and mobility requirements. Construction of the project began in July of 2011 and was completed in spring of 2012. A history of the slope instability progression using aerial photography, selection and design of the improvements, and resulting construction challenges are discussed. The authors conclusions on geotechnical lessons learned are shared
