Small Hydro On The Welland Canal
October 1, 2009
By Canadian Consulting Engineer
The historic Welland Canal system is an engineering marvel of the early 19th century. It connects Lake Ontario and Lake Erie through a series of eight locks, allowing ships to by-pass the 51-m high Ni...
The historic Welland Canal system is an engineering marvel of the early 19th century. It connects Lake Ontario and Lake Erie through a series of eight locks, allowing ships to by-pass the 51-m high Niagara Falls.
During the original construction of the locks, weirs were built to regulate the water levels. Two of these structures, Locks 1 and 2, were spilling water at a rate of 20m3 a second.
Recognizing that they could convert this spilled water to generate green energy, the St. Lawrence Seaway Management Corporation asked Hatch and Rankin Renewable Power to design and construct generating units within each of Locks 1 and 2. The two 2-MW plants altogether generate 25 GWh of green energy and offset 16,000 tonnes of carbon dioxide per year.
They were constructed with a lower environmental footprint and life cycle emissions than would be the case at any conventional greenfield water power site.
Leaving the locks fundamentally unchanged
Since the design could not fundamentally change the locks themselves, Hatch developed solutions to make maximum use of the structures already in place.
First, one of the existing gates at each of the locks was converted into a water intake for the generating units. This seemingly simple task required modifications to the concrete water passageway and the installation of 12-m high trash racks (bar screens).
To maximize the energy production at the new facilities, Hatch’s design required excavating the bottom of the canal. At Lock 2, the excavation unexpectedly exposed a very weak silty-clay soil, which meant real-time design modifications had to be made as the geological conditions were progressively exposed. Piles to support the new powerhouse struc- tures had to be driven down to the bedrock 20 metres below the bottom of the excavation.
All the in-water construction had to be conducted during the winter months when the canal was out of operation. The winter turned out to be one of the coldest on record requiring special provisions such as cold weather concreting. Design and construction had to be fast-tracked and completed before the watering up of the canal to ensure that its normal operations were not affected.
Since the projects are within St. Catharine’s and Niagara-on-the-Lake, Hatch undertook a state-of-the-art acoustic assessment to ensure that the operating facilities would not present a problem for local residents. To protect the transient fish populations of the canal, Kaplan-type turbines that minimize impacts on fish, and upstream trash racks designed to min- imize fish entrainment, were installed.
The project was completed on schedule by December 2007, within budget.
Project: Locks 1 and 2, Small Hydro Project, Niagara Falls, Ont.
Award-winning firm –prime consultant: Hatch (Ivor A. Shaw, P. Eng., James Neufeld, P. Eng., Harold Witt, Lisa Carson, Michael Parnya, P. Eng., Brian Fleming, P. Eng.)
Owner: Rankin Construction
Initial planning: St. Lawrence Seaway Management Corp.