One of three surge towers at the John Hart dam was knocked down Friday using explosives as part of decommissioning efforts for the 70-year-old power station near Campbell River, which has been replaced with a $1.1-billion generating station.
Two access roads into the site and surrounding public trails were closed for the controlled blast.
For the felling process, some of the eight supporting legs of the tower were cut using linear shape charges, with kicker charges used to ensure full metal separation and displacement.
B.C. Hydro spokesman Stephen Watson said the second tower could be felled next week. Steel from the towers is expected to be recycled.
The third tower, while not part of the new hydroelectric facilities, is in good condition and will stay in place, since it contains communications equipment and is a visual aid to the local airport, said Watson, adding there is heritage value in keeping one tower in place.
For years, the surge towers were the highest structures on Vancouver Island, at 90 metres or 295 feet tall.
The white towers are visible from certain areas of Campbell River, including from boats on the ocean, Watson said. They were in operation from 1947 to 2018, and protected the 1.8-kilometre-long penstocks that led from the dam to the generating station from short-duration water-pressure changes that occur when the flow velocity is increased or decreased.
They do this by allowing the water to go up, or come down.
The surge tanks were half-filled with water and at the same elevation as the upstream John Hart Reservoir.
The old John Hart facility was officially shut down last fall and replaced with a new and improved underground hydroelectric facility that’s expected to better withstand an earthquake.