The Ten Mile Slide (BC Highway 99)


Nov 16 @ 12 PM

Presented by Sarah Gaib from the B.C. Ministry of Transportation and Infrastructure

Highway 99 is an essential route between the rural communities of Lillooet, Xaxli’p and the Thompson-Cariboo.  Landslide activity was first documented in 1988 at the Ten Mile site, 17 km north of Lillooet on the south side of the Fraser River.  The Ten Mile slide is located entirely within Xaxli’p Indian Reserve.


The Ten Mile slide is a geotechnical anomaly being one of the only known continuously moving landslides in North America. From the project’s initiation the team recognized its uniqueness in that it moves all day, every day.  Prior to stabilization, average movement rates were 10 mm/day with rates up to 50 mm/day following rain or snow melt events.

In the Fall of 2015, the BC Ministry of Transportation & Infrastructure committed to a long-term solution to stabilize the slide.  The slide is 200 m wide at the highway and 300 m long with an estimate volume of 1M m3 of soil material and forms part of a much larger, dormant “soil glacier” called the Tunnel Earthflow.  By late 2016, this section of highway was the most expensive for the Ministry to maintain in the province, was subject to 50% load restrictions and had 24 hour flagging to maintain single lane alternating traffic.  

To attend the event contact the SGG using the Chat option in the bottom right corner or via email at:


Sarah Gaib is the Engineering Director for the Highway 1 264th St to Whatcom Road Project with the B.C. Ministry of Transportation and Infrastructure. She graduated from UBC with a degree in geological engineering and upon graduation began her career with the ministry as part of their EIT program. Sarah returned to UBC to complete her Masters in Engineering. As a geotechnical engineer for the Ministry Sarah has been regularly tasked with foundation designs and natural hazard assessments and has worked throughout the province on a number of interesting projects including the Ten Mile slide stabilization, George Massey Crossing, Sea to Sky Upgrades, Kicking Horse Canyon project, as well as, providing input into ministry policy and procedures.