The last big rock blast for the John Hart Generating Station Replacement Project went according to plan on Monday, BC Hydro says.
BC Hydro’s contractor InPower BC performed the blast right beside the existing generating station to remove the large area of rock that was between the outlet from the new tunnel and the Campbell River.
The blast took place at 5:20 p.m. on Monday. Sections of the Canyon View Trail near the John Hart facility were briefly closed during the blast for public safety.
“Just like the successful underwater rock blast near the John Hart dam in early October, a great deal of preparation went into this blast event to ensure that it went as planned, and it did,” Paul Sawyer, InPower BC CEO, said in a press release. “We will now begin removing the shattered loose rock by using a crane and clam bucket method to create a clear open channel from the tunnel into the river.”
Sawyer said that about 200 holes were drilled into the bedrock for the placement of the packaged explosives. The blast dislodged about 2,500 cubic metres of rock. The specifications of the blast were to have very little ground vibrations, which was achieved, given it taking place very close to the 70-year-old generating station.
Bubble curtains and other scare tactics were employed to get any fish that may have been in the area to move out just prior to the blast. The timing of the blast in early December was also done out of consideration of the end of the salmon spawning cycle, and was coordinated through discussions with federal and provincial government fish agencies.
“The generators inside the powerhouse are in poor condition and very susceptible to conditions that could cause them to go off-line,” said BC Hydro spokesperson, Stephen Watson. “The best course of action, to protect the units and most importantly the downstream fish habitat from a sudden reduction in river flow should some generators go offline, was to temporarily divert all the generating station water flow down Elk Falls Canyon. When we got the all clear after the successful rock blast, we slowly transferred water flows back through the generating station. That process went well.”
BC Hydro was coming to an end of their flood risk management operations from all the storm activity and snowmelt into the system reservoirs. The Campbell River flows below the John Hart generating station were reduced down 105 m3/s on Monday night. The flows in the river were as high as 200 m3/s last week.
“We’re excited about the prospect of having water, from the new intake at the John Hart dam, flowing down the new 2.2 kilometres of underground tunnels and into the Campbell River around March or April 2018,” says Watson. “That will be another big milestone, one of many that this project keeps hitting. For now, we’ll celebrate how well the tunnel outlet rock blast was successfully completed.”
The John Hart project remains on schedule for the new facility to be in full operation by fall 2018.