Design Aspects of Site C Earthfill Dam,

May 23, 2024

ABSTRACT The Site C Clean Energy 1100 MW Hydroelectric Project is located on the Peace River approximately 800 km north of Vancouver, 7 km southwest of the city of Fort St. John. It is 106 km downstream of the existing W.A.C. Bennett Dam. This paper covers the design aspects of the dam. The project includes an earthfill dam which has a maximum height of about 60 m above original ground and 78 m above its lowest foundation. The dam has been built on a very challenging foundation comprising weak shale with an unconfined compressive strength of 5 to 15 MPa. The foundation bedrock has closely spaced, nearly horizontal bedding planes with friction angles as low as 10 degrees. These bedding planes dictated the selection of dam type and controlled the design of the dam and appurtenant structures. All dam types were considered before selecting an earthfill dam for the site. The earthfill dam has a central core and filter zones founded on bedrock and upstream and downstream granular shells founded on riverbed alluvium.