One hundred years ago, capturing the power of Niagara Falls meant transporting flows through a system of canals to the Queenston-Chippawa generating station. Demand grew over the 20th century, hand in hand with the city’s population. As the Hydro-Electric Power Commission of Ontario made plans for a new generating station, nearly three times larger, building more canals was out of the question.
Construction for the Sir Adam Beck II (SAB II) generating station began in January 1951, and included a new powerhouse at Queenston, two intake structures in the Niagara River above the falls, and two 9km-long tunnels to convey the water from above Niagara Falls to the station.
David Heath and Clair Murdock wrote in homage to the builders of the twin tunnels in 2007. They describe the threeyear undertaking deep beneath the city of Niagara Falls as having achieved, “remarkable progress, considering the technology of the day, comparing very well with the rapid excavation and tunnelling methods of the 21st century.” The authors call it, “big, fast, and deadly—at least 20 lives were lost in construction accidents.”
The excavation volume for the 15.55m-diameter tunnels and the shafts exceeded 3,500,000 cubic meters, which is still today the largest underground civil works excavation by drill and blast in the Western Hemisphere. Heath and Murdock explain, “the tunnels were excavated using drill and blast methods, with a top heading and bench approach. The shot rock was loaded with electric shovels and transported to the five shafts with offhighway trucks. The tunnel muck was hoisted to the surface by skip and transported by truck to disposal areas.”
SAB II opened on August 30, 1954, and according to Ontario Power Generation (OPG) it is its largest capacity hydroelectric station. Its namesake, Sir Adam Beck, served as chairman of the Hydro-Electric Power Commission of Ontario until his death in 1925. He championed the idea of municipal and provincial power ownership to spur economic development, and was instrumental in developing the Queenston-Chippawa station, which would later be renamed Sir Adam Beck I in his honour. Upgrades to the turbines at Sir Adam Beck have increased the capacity of the station, and with decommissioning of three generating stations at the crest of Niagara Falls, more water was made available for power generation. However, the existing tunnels and canals were not capable of conveying this water, and OPG embarked on a project to build a third tunnel, 10km long and mined by TBM, which was completed in March of 2013.
