A 2014 landslide on a hill above a residential subdivision destroyed one home and required the evacuation of several others. Though a temporary fix addressed immediate concerns, areas that were not remediated reactivated in 2016, and testing showed continued downslope movement. This project provided a permanent fix to the issues that continued to threaten the subdivision.

The solution called for the excavation of 14,800 cu yd of earth at the base of the landslide to install a new drain system consisting of perforated solid pipe and horizontal drains, which directs water flowing down the hill into the existing storm drain. During excavation, the team discovered unexpected conditions, including numerous previously installed drain lines. They developed a plan to dig multiple sumps to contain the water while they located the source, and they eventually tied those drains into the new design.

Photo by Jeremy Gudac

In all, 19,000 cu yd of earth were reimported to reshape the hillside into a stable slope that includes drainage benches and surface drainage features to ensure that the surrounding community remains safe.