Controlling Risk to Critical Infrastructure during Construction: Seine Riverbank Stabilization at the Branch 1 Aqueduct, Winnipeg, Manitoba

ABSTRACT: The 100-year old Branch 1 Aqueduct is a critical part of the City of Winnipeg’s water system, transporting 40% of the City’s treated water. In recent years, undesirable riverbank movements were observed at the Seine River crossing which, if left unmitigated, could lead to complete catastrophic failure of the Aqueduct. The optimal method of stabilization was selected with consideration to the risk of construction induced movement and vibration adversely impacting the 100-year-old aqueduct, as well as environment, schedule, constructability and cost. A highly prescriptive construction methodology incrementally increased existing stability at each stage of the work. Construction began with a full-scale rockfill column field testing program to develop site-specific techniques. Real-time and cloud-based monitoring data were collected to facilitate refinements to the construction methodology, as necessary. All riverbank stabilization and erosion protection works were successfully completed during the winter of 2018. Pre and post-construction inspections revealed that the Branch 1 Aqueduct was not compromised by the construction.