In just two days, the November 2021 atmospheric river dropped months worth of rain across southern British Columbia, causing widespread flooding and damaging critical infrastructure, including Highway 8. Highway 8, which traverses the adjacent Nicola River, provides vital access to several communities between Merritt and Spences Bridge. There were 25 sites where damage occurred, with 7km+ of highway lost and 60km+ of river channel devastated. This resulted in communities losing access to their homes, electricity service, and emergency services. The few secondary roads connecting to the Highway 8 corridor were not an option for heavy construction access, requiring construction to progress linearly through the corridor.

The Nicola River experienced a flood of record, estimated at 750 m3/s, almost double the previous flood. The lateral migration of the river channel and bank erosion changed the river alignment and exposed Highway 8 to new/increased slope stability, rockfall and landslide hazards (geohazards), and river related hazards (hydrotechnical hazards). Where possible, the highway was reinstated along the pre-flood highway alignment, however this was not always feasible due to the presence of geohazards created by the flood. The flood also devastated fish habitat and riparian vegetation throughout the river system.

The highway was rapidly reconstructed using the non-traditional approach of Construct-Design-Construct-Plan (CDCP). KWL and Ecora developed a typical cross-section for the corridor based on previous KWL and Ecora knowledge of the Nicola River valley, with the intent to have the erosion protection in the ultimate location, minimizing future instream works in the recovery phase. This approach also eliminated design delays as subsequent isolated sites were accessed. Through collaboration with the project partners along the Hwy 8 corridor and local communities, the highway was rebuilt and residents were able to return to their homes in less than a year.

Restoring connectivity to the cut off communities required immediate reconstruction of the highway. With the existing and new flood-induced hazards, a balance between public safety and nature was essential. To avoid geohazards, the highway would need to be pushed further into the newly defined river channel to a safe off-set distance, but to maintain river capacity and fish habitat, the river encroachment would need to be minimal.

Construction began immediately, with work starting at both ends of the damaged highway. KWL and Ecora developed a cross section template utilized available riprap gradations, minimized encroachment into the river, and protected the public from geohazards. As the updated design parameters were unavailable at the time required, the design had to allow flexibility for raising the road without additional instream works and for the implementation of additional erosion protection measures (e.g. groynes, spurs, etc.), if required in the future. As work progressed through the corridor and new sites were accessed, the design cross section was refined as required. Habitat enhancement features of live willow staking, boulder clusters, and habitat groynes were installed at select sites to initiate habitat recovery.

Hwy 8 was reopened to the public 360 days after the catastrophic flood. The 25 repaired sections of highway are more resilient to future floods through placement of riprap and road fills of less erodible materials and incorporation of geohazard experience. The CDCP approach allowed the response works to be initiated and completed before the identification and acceptance of updated design parameters. This resulted in faster reconnection of communities and getting families back into their homes.