And then there were two…
The contractor for BC Hydro’s John Hart Generating Station project in Campbell River successfully felled one of three historic surge towers Friday morning.
“At about 10:20 am, we detonated precise explosives attached to some of the base girders of the tower so it directionally fell as planned, similar to a large tree, up the penstock corridor,” said BC Hydro spokesperson Stephen Watson.
The demolition was part of the approximately $1 billion John Hart Generating Station Replacement Project which moved generating facilities underground to make them seismically safer. Currently, the old above-ground structures are being removed.
A 450-metre safety closure radius was put in place around the surge towers, so the two access roads into the site and the surrounding public trails were closed off for the controlled blast event. The contractor InPower BC, with FMI/ASL-JV and subcontractor Pacific Blasting and Demolition leading the actual surge tower removal, obtained a blast permit from the City of Campbell River. People near the site may have heard the blast and wondered what the sound was from.
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.
“We will now remove the felled surge tower, with the steel to be recycled,” Watson said. “The second tower may be felled sometime next week.”
The third (south) tower, while not part of the new hydroelectric facilities, is in good condition and will stay in place given it has communications equipment and is a visual aid to the local airport. There is also the heritage value in keeping one tower in place, Watson said.
At 90 metres or 295 feet tall, for a period of time the surge towers were the highest structures on Vancouver Island. The iconic white towers are visible from certain areas of Campbell River, including from boats on the ocean.
They were in operation from 1947 to 2018, and protected the 1.8-km 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 conversely 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. The old facility is being removed.