British Columbia’s historic mega-project of building the Site C hydroelectric dam on the Peace River in the northeastern sector of the province has reached its first major operational milestone — the step of holding back water.
On Sunday, August 25, 2024, crews began the process of filling the reservoir behind the dam.
Site C’s reservoir will stretch a length of 83 km and cover a land area of about 13,700 acres or nearly 56 sq km — equivalent to the driving distance between the University of British Columbia and Abbotsford, and roughly half the area of the City of Vancouver.
This is the third dam on the Peace River; the 1980-built Peace Canyon Dam and the 1968-built WAC Bennett Dam are located to the west. Although significant in size, the Site C reservoir will be about 5% of the size of the Williston Reservoir of the WAC Bennett Dam.
BC Hydro anticipates it will take about two to four months to fill the Site C reservoir, with water levels rising between 0.3 metres and three metres per day.
When filled, the reservoir will have a depth of up to 52 metres (171 ft) near the dam. The total surface area of the reservoir will be over 93 sq km or about 80% the size of the City of Vancouver.
July 2024 construction progress on the Site C hydroelectric dam. (BC Hydro)
July 2024 construction progress on the Site C hydroelectric dam. (BC Hydro)
July 2024 construction progress on the Site C hydroelectric dam. (BC Hydro)
The electric utility is advising the public to stay away from the reservoir area during filling and for at least one year after due to the potential risk of landslides.
The process to fill the reservoir is one of the last steps in building the dam, which precedes the steps of enabling the generation station, spillways, turbines, and generators to come into operation.
The dam is an L-shaped structure, with most of its length being the one-km-long, north-south, 60-metre-tall (200-ft-tall) earthfill dam, which reached completion in August 2023. The earthfill dam — containing 15.5 million cubic metres of material — has a width of about 500 metres at its base on the floor of the valley.
The smaller east-west concrete dam structure, spillway, and generating station are situated on the south side of the river.
The overall L-shaped structure better enables the dam to withstand the area’s geotechnical challenges, especially its soft sedimentary shale.
Diagram of the Site C dam. (BC Hydro)
July 2024 construction progress on the Site C hydroelectric dam. (BC Hydro)
July 2024 construction progress on the Site C hydroelectric dam. (BC Hydro)
July 2024 construction progress on the Site C hydroelectric dam. (BC Hydro)
If all goes as planned, Site C will be operational by 2025, with all six generating units in service. Construction first began in 2015.
It will have an output capacity of 1,100 megawatts and produce about 5,100-gigawatt hours (GWh) annually — enough power for the equivalent of 450,000 homes or 1.7 million battery-electric cars.
Shortly after the BC NDP provincial government came to power in 2017, they considered canceling the Site C project. However, a decision was ultimately made to proceed with the controversial project, as abandoning it would still result in a $4 billion loss with nothing to show for it.
At the time of the final decision to continue construction, the estimated cost of the project had increased from $8.8 billion to $10.7 billion. In 2021, the project’s cost officially further increased to $16 billion, which includes enhanced design considerations to withstand a major one-in-10,000-year seismic event.
July 2024 construction progress on the Site C hydroelectric dam. (BC Hydro)
July 2024 construction progress on the Site C hydroelectric dam. (BC Hydro)
July 2024 construction progress on the Site C hydroelectric dam. (BC Hydro)
Some critics previously suggested the dam would produce an unnecessarily large supply of surplus energy. But as it turns out, BC will need much more electricity supply starting at the end of this decade, which already takes into account the new capacity that will be gained for BC Hydro’s grid from Site C starting in 2025.
This is happening much earlier than anticipated, as electrical demand is expected to increase by 15% between 2023 and 2030. This growth is driven by population and economic expansion, new home construction, and the transition from fossil fuel-powered systems to electrification in both building systems and transportation, such as the provincial government’s mandated accelerated adoption of battery-electric vehicles.
In 2023, BC Hydro announced it will make its first call for additional power in 15 years, with the expectation that it will acquire new sources as early as 2028. This call is expected to provide BC Hydro with about 3,000 GWh of additional electricity each year — equivalent to 60% of Site C’s expected output.
“Thank God we have Site C. And remember, I was there in 2010 standing with Gordon Campbell when we announced we were going to build Site C and that was in the teeth of opposition from the NDP and their allies,” BC United leader Kevin Falcon, who held various ministerial roles during Premier Gordon Campbell’s tenure, told Daily Hive Urbanized in an interview last week.
“But just imagine today where we would be if Site C wasn’t built, if it didn’t go forward, given the growth of electric vehicles and the growth of our power demands with a growing economy. We knew back then in 2010 that we were building this for the next generation, not the next election.”
Further east along the Peace River within Alberta, another hydroelectric dam project — called the Amisk Hydroelectric Project — is currently in the early stages of consideration. It would generate 1,875 GWh of electricity per year or about 37% of Site C’s annual output.