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John Hart Generating Station replacement on schedule — and on budget

Tall as a 10-storey building and long as an American football field, the new powerhouse cavern at the John Hart Generating Station replacement project is starting to fill up. It took 13 months and 485 blasts to create the massive subterranean space.
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Construction crews work underground on a massive tunnel at B.C. Hydro's John Hart hydroelectricity project near Campbell River.

Tall as a 10-storey building and long as an American football field, the new powerhouse cavern at the John Hart Generating Station replacement project is starting to fill up.

It took 13 months and 485 blasts to create the massive subterranean space.

A total of 60,000 cubic metres of rock was hauled away — enough to fill 24 Olympic-size swimming pools.

The cavern was finished in the spring. Workers are now placing concrete inside the cavern to prepare it for three turbines, three generators and a water bypass system, B.C. Hydro spokesman Stephen Watson said Wednesday.

The cavern measures 40 metres high and 93 metres long. It is 60 metres below the surface, where it is being built near Campbell River.

Hydro is pleased to see that “it is amazingly dry. There is very little seepage from ground water. That is better than we expected,” Watson said. “The density of the rock is good.”

The John Hart Generating Station replacement project is valued at $1.1 billion. InPower B.C. (SNC-Lavalin) was hired as general contractor. Work began in July 2014.

“The project remains on schedule for commission in fall of 2018 and on budget,” Watson said.

B.C. Hydro decided to replace its existing 1947 facility because of fears that it would not survive a low-to-moderate earthquake. Its generating stations are in poor shape and their capacity is decreasing.

The new development will deliver power to 80,000 homes, up from the current 74,000, when complete.

The project is a major economic generator for the region. At this time, 350 people — everyone from professionals to trades — are on the job. As well, more than 100 subcontractors and suppliers have been hired on Vancouver Island, Watson said.

The contractor was able to solve a thorny problem of routing the 384-metre-long main access tunnel. Last year, tunnellers came up against a 50-metre-long stretch of loose rock. Rather than trying to work through it, the contractor developed a detour route, Watson said.

“Kudos to the contractor because they were able to probe around that loose rock.”

“As of this week, it is all fully connected to the powerhouse cavern,” he said. The main access tunnel is six metres high and nine metres wide. It will be used by semi-trailer trucks delivering equipment.

Work is continuing on the new water intake at the John Hart Spillway dam.

Also complete is a vertical power tunnel shaft, running about 80 metres. The power tunnel itself will be about 1.5 kilometres and is about one-third complete. The power tunnel will transport water from the dam to the generating station and then another 600 metres to the Campbell River.

Contractors also drilled 130 metres to create space for the surge tank that connects to the power tunnel. Surge tanks can handle sudden rises in water pressure.

cjwilson@timescolonist.com