In May 2002, a landslide on the south bank of the Blackwater River damaged the Missouri Route K bridge that crosses it. A flood on the river triggered the landslide. Based on the field investigation and stability back-analysis, it appeared that the landslide actually consisted of two separate slides – a shallow slide triggered by rapid drawdown of the river and a deep slide triggered by artesian water pressures in a subsurface gravel layer. A rock berm that was keyed into the gravel was constructed to stabilize the slope. The rock toe berm was designed to resist both the shallow and deep slide by providing weight to the slope to prevent a rapid drawdown failure and providing a drainage outlet to relieve artesian pressures in the gravel layer
