Canadian Niagara Power Tailrace Tunnel

Contents: About the Collection | About the About Page | Tech

About the Collection

The Canadian Niagara Power Company’s powerhouse in Niagara Falls, Ontario, was the first hydroelectric generating station to be built on the Canadian side of the Niagara River.  Upon opening in 1905, the powerhouse boasted the largest generators of their kind in the world, with a capacity of 10,000 electrical horsepower each.  The powerhouse was named after William Birch Rankine in 1927, who was instrumental in its development and construction.  

One of the most impressive parts of the project was the tailrace tunnel.  The tunnel was an enormous construction project and a critical component of the power plant’s operations.  The tunnel is 2,200 feet long, beginning at the powerhouse and ending at a portal in the gorge near the base of the Horseshoe Falls.  It was at this portal that water diverted to the powerhouse from the Niagara River was discharged and rejoined the river. 

Initially the design called for two separate tunnels emerging from the powerhouse, which were to be joined at a later point.  This would enable the plant to continue operating while one tunnel was being repaired or inspected, as the alternate tunnel would be available to carry the discharged water.  Although practical, this design would cost more money.  It was decided to build a single tunnel.   In order to reduce the risk of the tunnel being unavailable due to repairs, a great deal of effort was put into its design and construction.  It was imperative that the tunnel be able to withstand the continual force of the water with minimal damage to its structure.  

The portal, where the water was discharged into the river, was designed so that the water was discharged near the river’s level.  This avoided the unappealing sight of water discharging well above the river, as it often did on the American side.  In order to accommodate this design, a sharp drop at the end of the tunnel was required  so that the water could exit under the surface of the river.   

Excavation for the tunnel began in 1901 and was completed by late 1902.  At this point, much consideration was given to the construction of the interior of the tunnel.    The tunnel surface needed to be as smooth as possible.  Water would be flowing through it at  a rate of 30 feet per second.  Any irregularities on the surface would erode the tunnel prematurely. It was decided that  a combination of brick and concrete would be used.  The walls and floor would be made with concrete and covered with a single layer of high-quality brick.  The tunnel was completed in 1904.

In 1957, the Rankine Generating Station temporarily shut down operations so that the discharge tunnel could be inspected and any necessary repairs made.  It was found that the tunnel was in excellent condition, even after 50 years of operation, and very little maintenance was required.

The powerhouse ceased operations in 2006 and is currently owned by the Niagara Parks Commission. It was recently opened to the public and there are plans to open the tailrace tunnel in July 2022.

For full details of creating your own collection site, visit CollectionBuilder Documentation!