Following the atmospheric river of October 2024, a significant slope failure occurred along Thain Creek in the City of North Vancouver. The failure advanced the slope crest to within 6 metres of a nearby building, creating an immediate public safety risk. The event also caused severe channel erosion, limiting fish migration and forcing significant volumes of water to flow below the channel surface.

Tetra Tech provided hydrotechnical, geotechnical, and environmental engineering services to support emergency stabilization and ecological restoration efforts. Given the urgency the full design, tendering, permitting, and construction process was successfully completed within an accelerated 10 month window. This was made possible by the close collaboration with the City of North Vancouver, Fisheries and Oceans Canada (DFO), and the BC Ministry of Lands, Water, and Resources.

Rather than concentrating all the efforts on addressing the erosion on one side of the channel, The entire ravine was raised providing long term stability along both sides of the creek.

Key Engineering Solutions

• Channel Raising & Habitat Enhancement
  The creek bed was raised by up to 4 metres, allowing for the construction of a stepped series of pools and riffles to restore fish passage and improve habitat quality.

• Bank Stabilization & Revetment Works
  A vegetated revetment system combining riprap armouring and riparian planting was installed to stabilize slopes and re establish shading and bank structure.

• Large Woody Debris & Boulder Features
  Large woody debris and boulder clusters were incorporated to increase channel complexity and support aquatic habitat diversity.
• Materials & Innovative Methods
  To ensure channel stability and prevent subsurface seepage, the design employed nonwoven geotextiles, bentonite, and fine sands and gravels. The use of large quantities of riprap enabled the project team to condense in stream construction to just six weeks while maintaining schedule and budget.

The completed works improved long term slope stability of the entire ravine, removed fish passage barriers, enhanced habitat connectivity, and reduced ongoing erosion risks. Through integrated engineering and environmental planning—executed on an emergency timeline—the project restored ecological function while addressing critical public safety concerns.