Stabilizing a Landslide to Preserve the Historic Irishtown Bend in Cleveland, OH

The Irishtown Bend Stabilization Project is a major infrastructure project in Cleveland, Ohio, that involves stabilization of a massive landslide to restore a historic neighborhood to public use and prevent a slope failure that threatens to impair navigation along the economically vital Cuyahoga River shipping channel at the toe of slope. Urban development and fill placement in the 1960s added load to the top of the Irishtown Bend hillside. The added load reactivated ancient slide planes at a depth of more than 30 m (100 ft) and triggered large, on-going slope movements including a major head scarp at the top of slope. The slide is retrogressive today with local slope failures at the hillside toe occurring due to on-going erosion from river action and turbulence caused by ship traffic. This paper discusses the geologic history of the Irishtown Bend, site development, hillside instability, and the on-going slope movement. The results of a 2019 subsurface investigation and slope movement monitoring program are described with focus on defining the landslide failure geometry and developing peak and residual friction angles in the glacial lacustrine clay for use in stability assessment. This paper also discusses the results of back analysis of slope stability and assessment of the necessary stabilization measures to achieve target safety factors. Finally, design and construction of long-term stabilization measures are presented including major earthwork to facilitate hillside unloading and installation of a permanent anchored bulkhead consisting of a steel sheet pile and pipe pile combination wall braced by tieback anchors extending to shale bedrock.