Site C earthfill dam complete

FORT ST. JOHN, B.C. — The Site C earthfill dam, a key component to begin reservoir filling this fall, is now complete.

The purpose of the earthfill dam is to direct water from the Peace River to the approach channel, which will lead to the powerhouse to generate electricity. 

The Site C earthfill dam is 60 metres tall, stretches more than one kilometre across the Peace River, and is approximately 500 metres wide at its base, according to BC Hydro. The dam consists of approximately 16 million cubic metres of earthfill material. 

The earthfill dam’s core is made from glacial till, a material containing clay impervious to water. Granular shells, which are larger and heavier, are used outside the dam to support the glacial till. Another example of an earthfill dam is the W.A.C. Bennett Dam.

In a release, Bc Hydro said the earthfill dam is made mostly of material taken directly from the dam site, while other material used was sourced locally offsite and transported to the dam on a conveyor belt. The placement of material for the earthfill dam began in 2021.

With the completion of the earthfill dam, the next steps involve capping it and building roads across it for crews to travel on once the Site C project comes into operation. 

Completion of the earthfill dam is an “essential milestone” required before BC Hydro can begin filling the Site C reservoir.

BC Hydro is anticipating filling to commence in the fall of this year, but there are still several key project areas that need to be completed, including the approach channel, spillways, tailrace area, dam intake structures, and certain components of the powerhouse. 

Another key component that needs to be completed before reservoir filling can begin is the conversion of one of the tunnels that currently diverts the Peace River around the project site, BC Hydro said.

The conversion process requires the installation of constrictions inside one of the tunnels in order to restrict the flow of water. BC Hydro says this work is currently underway.

More information about tunnel conversion and reservoir filling can be found on the Site C project’s website.

The earthfill dam isn’t the only component of the Site C project to recently reach completion. Earlier this month, BC Hydro announced the completion of the Highway 29 realignment project.