In November 2021, during an unprecedented atmospheric river event, the Sumas River Dike was breached resulting in flooding of a large area of the Sumas Prairie in Abbotsford, BC. The site of the Sumas River Dike breach is
approximately 4.5 km southwest (upstream) of the Barrowtown Pump station along the base of Sumas Mountain. This paper describes the main breach that occurred including the failure mechanism and the key geotechnical engineering considerations related to design and construction of the breach repair. A two-staged strategy was adopted for repair of the dike breach that included the initial emergency repair to close the breach followed by the additional remedial work required to restore the temporarily repaired dike section back to a dike with a low permeability core . Details of the two-stage repair strategy are described including the various options considered, as well as the challenges faced during construction. The flood event also created significant challenges during construction in terms of the supply of the materials required to repair the breach, access to these materials, and maintenance of access between the work site and material supply. These challenges are presented with the intent of providing some insights for future emergency preparedness plannin