Second Tahtsa tunnel near completion

RioTinto Alcan has completed an important tie-in section of a tunnel-twinning project southwest of Burns Lake.

RioTinto Alcan (RTA) has completed an important tie-in section of a tunnel-twinning project southwest of Burns Lake. Tahtsa Lake, at the western end of the Nechako Reservoir, flows into the Kemano hydropower plant south of Kitimat via an underground tunnel approximately 16 kms long.

The original plans called for two tunnels, and although two were begun, only one was completed.

Called the back-up tunnel project, construction will complete an unfinished extension of a second tunnel running from the west end of Tahtsa Lake to the existing penstocks. The penstocks are a steep sluice system that feeds and controls water flow into the turbines at Kemanos.

The back-up tunnel project was recently described to directors of the Regional District of Bulkley Nechako (RDBN) as a precautionary measure to ensure that a steady supply of water to the Kemano hydro-electric turbines would not be interrupted if the main tunnel were to collapse or require repair.

Colleen Nyce, RTA manager of corporate affairs and community relations, presented an update regarding the Kitimat modernization project and the back-up tunnel project on Oct. 10, 2013.

“The project completes the second tunnel and links it to the existing penstock,” Nyce explained. “This is not a resurrection of the old Kemano completion project. The Kemano completion project envisioned another powerhouse and more penstocks.”

The completion of the secondary tunnel was mandatory as far as RTA was concerned.

“RIoTinto was not willing to invest in our smelter modernization [project] without us de-risking this single source of power to the smelter,” Nyce said.

The Kitimat smelter modernization project will double the aluminum producing capacity of the aging smelter operation – originally built in 1952 – by replacing the old smelters with a modern system.

“The new smelter is sized to use all the firm power [from Kemano],” Nyce said. “The firm power is what we can rely on 24 hours a day, 365 days per year. Anything more than that is not reliable; it’s contingent on conditions and weather.”

The original tunnel, which is 60 years old, had a collapse in the 1950s which shut down the Kitimat smelter for 10 months. Rio Tinto Alcan doesn’t want that kind of risk associated with the new smelter.

“We are essentially putting another tap on the same faucet,” Nyce explained. “It allows us to use tunnel two if tunnel one goes down for maintenance or repairs. Or to use both tunnels at the same time. But we are not planning to use more water.”

Water use is a delicate subject surrounding Kemano.

Water levels in the Nechako Reservoir now control the flow of the Nechako River. Conservationists have blamed the reduced flow of the Nechako – directly related to the construction of the reservoir – to the decline of the genetically unique Nechako River White Sturgeon.

RioTinto Alcan has a water license for 170 cubic metres per second (m3/sec), but only uses 140 m3/sec.

“One-hundred-and-seventy m3/sec has always been a concern for us,” said Jerry Peterson, RDBN director of area E (Vanderhoof/Rural), “If Alcan ever went to that much it would dry up the Nechako river.”

Rob Newell, RDBN director area G (Houston Rural) suggested a reduction of the current license to the level that RTA actually needs to power their Kemano station.

“If you only intend to use a part of the water license, why don’t you cap it off at what you use,” asked Newell.

The semantic distinction lay on the word ‘intend’.

“To clarify, I didn’t say we don’t intend to use that 170 m3/sec,” Nyce explained. “I said we’re not using it and this project doesn’t envision using it.”

“I can’t speak for the company that will come years after me about we intend to do with the rest of that water license.”

The Kitimat modernization project is valued at over $3 billion, and according to Nyce is 50 per cent complete. The modernization project will inject $370 million directly into the Northern B.C. economy. The back-up tunnel construction will inject another $30 million, Nyce said.

The Kemano power plant has a capacity of 1000 megawatts, although RTA targets 790 megawatts and relies on a consistent 700 to 710 megawatts. RioTinto Alcan expects to sell little power back to the province once the modernized smelter is operational and using most of Kemano’s power-generating capacity.

RioTinto Alcan has 1200 employees in B.C., working in Kitimat, Burns Lake, Vanderhoof and Vancouver. Company assets include the Kitimat smelter, the Kemano powerhouse, the transmission line from Kemano to Kitimat, the Kenney Dam, the Nechako Reservoir and the Skins Lake Spillway. The remainder of the tunnel project will be completed over then next few years as preparatory work is completed.