Expansion of the largest hydropower plant in Ontario by adding a 10.4 km long tunnel, running beneath the city of Niagara Falls, with the purpose of energy production increase and reduction of Niagara Falls erosion.
The dimensions of this project are outside of common experiences. The height in the tunnel is comparable with a 5 story building. The alignment of the tunnel follows positive and negative inclinations. The heading is executed with the world wide largest tunnel boring machine measuring 14.4 m in diameter and reaching 1’500t/h excavation mass.
The dimensions and the geological conditions are demanding special and high requirements of the back-up installation.
The TBM and the back-up are building one unit. The front of the back-up lays within the L1 (first possible area of rock support) directly behind the boring head. TBM and back-up are being designed and matched by Robbins and Rowa together from the very beginning.