Blasting has resumed in the main access tunnel that will eventually get to the powerhouse cavern. The cavern

BC Hydro resumes blasting in tunnel

BC Hydro is warning residents who live near the John Hart Generating Station that they may hear blasting now that regular operations have resumed on the project.

While blasting has been ongoing for the past several months, the noise had quieted because of an obstacle encountered while blasting into the ground to create the main access tunnel to what will be a new underground generating station.

Stephen Watson, spokesperson for BC Hydro, said crews encountered a loose rock area of cobbles and sand about 155 metres into the tunnel.

Watson said Hydro’s contractor, InPower BC – a special purchase project company of SNC-Lavalin – discovered a detour route that involved probe drilling upwards from the excavated surge chamber area. The detour is 80 metres in length and curves around the majority of the loose rock area before continuing along the original main access tunnel alignment.

Watson said drilling and blasting of that detour route began in mid-December.

“The process was drilling in the canopy tubes, which had holes in them to then put through lots of grout to bind the loose rock area together, and then excavating the area under a steel umbrella support system,” Watson said. “Now with the ability to go around this area, our contractor, InPower BC, has resumed blasting where they can go through about three to four metres of rock mass per blast – a blast per day.

“Much better than the metre of tunnel advancement in a week or so through that loose rock area.”

Watson said that also means residents who live in the surrounding area may once again be hearing the blasts.

“Residents may hear blasting noise now that the regular blasting method has resumed within the main access tunnel,” he said. “This is expected to become quieter as the contractor moves deeper into the tunnel, along with the angled tunnel direction.”

Watson said it’s expected to take at least one month to get around the loose rock area within the main access tunnel which is nine metres wide by six metres high.

“A project of this scale will come across various challenges over the five-year construction period and hopefully this detour route will overcome this particular challenge,” Watson said.

“We’re 18 months in and the project’s looking to be completed by the fall of 2018,” he added. “There’s now just over a kilometre of underground tunnelling and work is progressing at all the key site areas.

“Looking forward to an exciting 2016 as the project continues to take shape.”

Construction on the $1.1 billion project has been ongoing since early 2014. The project will produce a new, seismically-sound underground John Hart Generating Station for BC Hydro, as well as a new drinking water intake system for the city and a brand-new, 80-stall parking lot for Elk Falls Park which opened in October, 2013.