The Michigan Ditch Landslide and Tunnel Case History and Unique Delivery Method

The Michigan Ditch is located in Jackson County, Colorado and is part of the City of Fort Collins water supply system. It conveys water from the west side of the Never Summer Mountains to Joe Wright Reservoir on the east side of the range. The 5.2 mi long ditch was constructed in the early 1900’s and has been plagued by slope instability since it was built. An area known as the “Mudslide” has experienced accelerated slope instability in recent years and the piped portion of the ditch through the landslide was destroyed in 2015 when the landslide moved over 20 ft horizontally and 7 ft vertically. Following an extensive geotechnical investigation utilizing vertical and horizontal borings at the site, several mitigation alternatives were evaluated, the associated risks were weighed, and a tunnel behind and under the landslide was selected. The project was designed and will be constructed utilizing the City of Fort Collins utilities alternative product delivery system (APDS). APDS is a collaborative approach unique to the City of Fort Collins utilities and focuses on delivering quality projects that are built on time and on or under budget. The total construction cost for this project is estimated at $8.5 million dollars and will be constructed between May 2016 and October 2016.