Swift Powerhouse 2 Canal Failure

Cougar, Washington
In April 2002, the Swift II dam embankment suddenly failed and damaged a powerhouse located immediately downstream. Water for the Swift II complex is supplied through an open channel originating below PacifiCorp’s Swift I Dam Powerhouse, located a few miles upstream. The dam failure resulted in the temporary shutdown of power generation at Swift I until a side channel could be established to route flow past Swift II. The sudden drawdown of water in the canal also caused numerous small to medium slope failures along the canal side slopes.

​Cornforth Consultants (CCI) provided emergency reconnaissance of the failed dam, and met with senior PacifiCorp engineers to discuss possible causation. Subsequently, CCI assisted PacifiCorp with the development of conceptual options to stabilize and enhance an existing side channel spillway to allow the canal flow to safely bypass Swift II, and prepared a cost-effective design for the repair of the canal slope failures.
Rockslide Impacting the Banks-Lowman Highway
Swift Canal Failure Aftermath

​Services Provided:

  • Geologic Hazards
  • Hydrogeology
  • Forensic Failure Analysis
  • Embankment Stability Analysis
  • Embankment Design
  • Field Explorations