Rio Tinto Alcan has applied for a permit to complete the half-finished tunnel bored as part of the long-dead Kemano Completion Project (KCP).
However, RTA vice-president of BC Operations and Strategic Projects Paul Henning emphasizes, “This is not KCP being done under the radar.”
Rather it is to ensure there is a back-up to the existing tunnel which in both 1958 and 1961 saw significant roof collapses.
Henning explained that in September of last year RTA sent an unmanned mini-sub into the old tunnel in order to check out its condition.
To do that RTA had to reduce the flow in the tunnel because the small submersible was “not man enough to force against the (full) flow.” That in turn reduced power generated at the Kemano powerhouse.
Which left them with a four to five hour window before that reduced power caused problems at the smelter. “So in that time you’ve got to get in as far as you can and get out.”
Coming in from the reservoir end of the tunnel, the sub got in 2.6 kilometres, about six kms short of the location of the 1958 collapse.
It did, however, get as far as the location of the 1961 collapse, “the hot spot we wanted to get to,” Henning said.
And everything looked good there, although they did see evidence of a couple of small rock falls.
This year RTA sent in a larger sub with better sonar and 3D imaging technology with the intention of covering 8-9kms from the reservoir intake, past the halfway point of the tunnel. It managed to cover just short of 5kms.
And an attempt to go in via the surge tunnel – it angles down into the tunnel at the Kemano end – failed because they couldn’t get “round the corner” and into the main tunnel.
The upshot was that 10kms of tunnel was not inspected.
The hope had been that a full inspection would guide RTA on which of three options it pursued with regard to the old tunnel.
The first would have been to do nothing, assuming the inspection had found the tunnel to be in good shape.
The second would have been to take advantage of a window of opportunity presented by the modernisation project (KMP), taking a “full outage” as the existing plant came to the end of its life and before firing up KMP.
“That seems like the logical thing to do,” said Henning.
Except that the outage would have been anywhere between six and nine months, depending on what they found.
“We’ve got 1,400 employees – what do we do with all those employees?” he asked.
Also, what would they do about the reservoir where water would continue to flow in while no water was being taken out at the intake.
And that in turn would mean changes to the water flows in the Kemano River.
Given those last two, Henning said it would be unlikely that federal Fisheries would approve that option.
The final one was to complete the KCP tunnel and connect it to the existing penstocks – the twin penstocks at Kemano are the shafts through which the water from the tunnel plunges 800 metres to drive the generator turbines.
“We feel it’s a valid option”, Henning said, adding the plan would be to give priority to completing the connection of the second tunnel before KMP starts up in early to mid-2014 while keeping the existing smelter running throughout.
Once that connection was made, RTA would turn its attention to connecting the second tunnel to the reservoir – it at present covers about half the distance from Kemano to the reservoir.
Henning said the application has gone to the environmental agencies and pointed to disposing of rock from boring the tunnel, the re-opening of old roads and construction of a coffer dam at the new intake prior to opening that end up as the environmental aspects of the project.
Repeating that this project was not KCP in disguise, Henning said, “There are two key points: we’re not adding capacity to Kemano so the generator capacity stays the same. And we’re not changing our water licence.”
On the latter, he explained that the current water licence dates back to 1997 and is sized to meet only the needs of Kemano as is.
He also emphasized that the tunnel completion was a stand-alone project and that KMP was not dependent on it going ahead.
Once the second tunnel is operational, Henning said they would likely use both tunnels at the same time because that would reduce the head pressure and allow them to produce more power.
Kemano at present has a 1,000 megawatt capacity but generates an average of 795mw.
Asked what the project would cost, Henning said it was “a bit premature” to put a number on it at this stage, but conceded “it’s not a cheap solution”.
He expected the approval process would take anywhere between six and 15 months.