Niagara Falls channels through $1.6bn hydro tunnel
Record-breaking hard-rock-bored hydroelectric project enters service
Niagara Falls is generating renewable electricity for Ontario following completion of a 10km tunnel to channel water by the falls from the Niagara River to the nearby Sir Adam Beck hydroelectric plant.
Strabag AG employed world’s largest hard-rock tunnel-boring machine on the project, which was bored 14.4m wide and 10.2km long and at a depth of 140m beneath the city of Niagara Falls.
Originally planned at a cost of $985m, the project ended up being delivered four years late and is $615m over budget after slower than projected progress caused by constant tunnel roof over-break.
However, the tunnel is an engineering marvel with a diameter one and-a-half times that of the Channel Tunnel between England and France, and with a power capacity of 1.6bn kilowatt hours.
President and CEO of Ontario Power Generation, Tom Mitchell, said: “Congratulations to Strabag and the hundreds of men and women who worked with extremely difficult rock conditions to safely complete this engineering marvel. This will serve Ontario for more than 100 years.”
The undertaking also displaced about 1.6m cubic meters of rock and debris, and the cast-in-place tunnel lining required 500,000m3 of concrete in its 600mm-thick walls.
According to Energy Minister Brad Duguid construction crews hit unexpectedly hard rock early on in the project, and had to redesign the tunnel to make it safer for workers, which slowed things down and added to cost overruns.
Nevertheless he commented: "This is an incredible engineering feat. It's a tunnel that's four storeys in diameter and may well be the largest tunnel ever dug to this point, anywhere in the world."
The tunnel is now channelling water at a rate of 500m3 per second, enough to fill an Olympic-sized swimming pool in seconds, and to power a population of more than 135,000 people.
Previously the amount of water in the Niagara River exceeded the capability of the existing power canal and diversion tunnels almost two thirds of the time; now this will occur only 15% of the time.
For the most part, the new tunnel and two existing tunnels follow a route that runs below and to the west of Stanley Avenue under the city of Niagara Falls.