Kitimat Rio Tinto will have a proposal before the company’s board before the end of the year to secure the go-ahead for the completion of the second tunnel to the Kemano power plant.
Rio Tinto General Manager for B.C. Works Gareth Manderson said the $500 million project to complete the construction of the remaining 7.6km of the 16km tunnel is essential if Kemano is to be able to guarantee power supply to the Rio Tinto plant in Kitimat.
“Initially the rationale behind the construction of the second tunnel was additional power generation,” said Manderson. “Now it’s just about ensuring the safety and security of the Nechako Watershed.”
He said the stability of the first tunnel, or T1, has been assessed by five different experts, who came up with a number of scenarios which indicate a probability of between 20 and 50 per cent that T1 will suffer a collapse before 2021.
“The life of a tunnel is finite. The tunnel has served us well for 60 years,” said Manderson.
He said there has been a slight increase in the amount of rock being caught in the rock trap in T1. The rock trap prevents loose rock from the walls of the tunnel from ending up in the turbines in the power plant.
A collapse of T1 will shut off supply of water to the generator, which will in turn cut the electricity supply to the plant in Kitimat.
“The Kemano power plant is the only competitive edge that the plant in Kitimat holds over other plants around the world, keeping it in the first quartile,” said Manderson.
Globally aluminium production is divided into four quartiles, and plants are ranked according to how cost effective it is to produce aluminium at those plants. Aluminium production consumes a lot of electricity, which the plant in Kitimat receives from the Kemano power plant.
Kitimat’s ability to produce its own electricity is a major competitive advantage, which along with factors like the increased output since the completion of the modernization project, is responsible for its ranking in the first quartile.
Currently T1 carries water from the Nechako Watershed through the mountains to the generation plant at Kemano, constructed in the 1950s.
A second tunnel, or T2, was proposed and construction began on the Kemano Completion Project, but the project became bogged down in controversy over the impact that the extra water being drained from the watershed would have on salmon stocks as a result of rising water temperatures in the Nechako River.
Construction of T2 was halted in the 1990s after half the tunnel had been bored. After two years of negotiations a settlement agreement was signed by the B.C. government and the company in 1997, paving the way for the completion of T2, on condition that the company spend $50 million on a cold water release facility at Kenney Dam to regulate the temperature of the water in the Nechako River.
Manderson stressed that the T2 Project is different to the Kemano Completion Project, because it won’t result in additional power generation and will not result in changes to the company’s water licence (no more water will be drawn from the Nechako Watershed than is currently being drawn).
“This project is just about securing the power supply to the smelter,” said Manderson.
Phase 1 of the completion of T2 was completed in 2013, which included construction of tunnels connecting T1 and the already bored section of T2.
The current and final phase, Phase 2, involves the completion of the remaining portion of T2 and the refurbishment of the completed 8.4km section, completing the construction of the 16km tunnel to the penstocks (channels for conveying water to the turbines) at Kemano.
Preliminary work for Phase 2 has already been completed this year, including road infrastructure which gives contractors access to the Heretzski adits at the 8km mark (an adit is a horizontal passage bored for the purposes of access or drainage).
Manderson is expecting approval of the final design and engineering before the end of the year and expects construction to begin in 2018.
Rio Tinto will engage a main contractor to manage the majority of the construction, who will be responsible for hiring the various subcontractors and employees necessary for the project.
At peak construction, the total construction workforce is expected to be in the range of 350, depending on the main contractor’s workforce plan.
“Rio Tinto will work with the main contractor to ensure they have the information they need to maximize the involvement of local businesses, contractors and labourers.”