Seismic safety |
Seismic upgrades: dams reinforced
From Vancouver Island to Kariba, engineering projects tackle earthquake risks, safeguarding water, power, and ecosystems in seismic zones
Above: Seismic upgrades included the construction of a plastic concrete cut-off wall on the Middle Earth-fill Dam. Bauer utilized two MC 96 machines with a hydraulic grab and cutter to excavate the new primary seepage barrier. © BAUER Group
ONE OF THREE DAMS on the Campbell River on Vancouver Island in Canada, the John Hart Dam was built in 1947. Designed with seismic considerations based on the information available at the time, there is now greater understanding of the risks posed by earthquakes in what’s known as the Cascadia Subduction Zone. With a major earthquake occurring on an average of about every 500 years, and with a range of 300 and 800 years between events, it means one could be due at any time. So that’s why seismic upgrades are now underway at BC Hydro’s dam. Located just a six-minute drive upstream from
the town of Campbell River, the dam passes water to generate power at the John Hart Powerhouse, provides flood risk management operations, supplies the City of Campbell River with drinking water, as well as providing water for spawning habitat in an area known as the Salmon Capital of the World.
14 | February 2025 |
www.waterpowermagazine.com
Over the past ten years, BC Hydro has replaced the downstream generating station at John Hart to meet seismic standards, maintain reliability, and protect fish habitat, and is now in the process of rebuilding the dam itself. Once completed, it will be able to withstand a 1-in-10,000-year event, a severe earthquake of magnitude 9.0 or stronger. Started in 2023, the six-year John Hart Seismic Upgrade Project is part of BC Hydro’s recently announced C$36 billion, ten-year plan to sustain and upgrade existing assets including BC’s network of dams, transmission lines, and substations. BC Hydro says the current upgrades – mainly
through ‘widening’ of the dam base through the addition of upstream and downstream berms, and the insertion of an additional water seepage barrier in the dam itself – are designed to bolster the ability of the dam to withstand the severe shaking of a quake.
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