New 10-kilometre tunnel to boost power at Niagara Falls
10/7/2005


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Construction of an additional tunnel at Niagara Falls' generating facilities was due to begin in September. It is part of the ongoing efforts to boost power production at the famous site.

The new tunnel is being constructed under a design/build contract awarded to Strabag AG of Austria. Morrison Hershfield, consulting engineers of Toronto, are part of the Strabag team.

The design-build contract, worth $600 million, involves the use of a 1.4 metre diameter tunnel boring machine to excavate the tunnel about 140 metres below ground level. The tunnel is over 10 kilometres long. It will supply additional water from the falls to the Sir Adam Beck generating complex at Queenston Heights, increasing its output by an average of 1.6 Terawatt-hours a year. The power is enough to provide electricity to meet the annual needs of a city twice the size of Niagara Falls.

That article has one huge error (I thought the tunnel seemed small).

Ref: http://www.waterkeeper.ca/lok/index.cfm?DSP=content&ContentID=7796

The boring machine is 14.4 m, not 1.4 m, and the finished ID of the tunnel will be 12.7 m. It will transport 500 m^3/s. The water is needed to support a capacity increase of 194 MW resulting from generator upgrades at the facility.

Another article points out the US and Canada each currently draw 1800 m^3/s around the falls for hydro generation. I don't know whether the US gets to increase its draw (or has the generator capacity to use it).

Neither article mentions that to maintain daytime flow for tourists, water is drawn into impoundment reservoirs late at night, and the hydro plants run off the impounded water by day. I don't know whether they have the water storage to support. Flow over the falls is GREATLY reduced at night while they flood reservoirs.

The 1950 water diversion treaty (when neither country used SI much) commits 100,000 cu ft/s to go over the falls during summer daytime hours for scenic purposes, and 50,000 cu ft/s at all other times. Dates and hours are rigorously defined in the treaty. The balance of water (roughly 2/3 the flow) goes through power plants instead of over the falls. This diversion has decreased erosion of the falls by reducing flow (although the purpose is to make power). Power generation varies from year to year based on available water, although during part of the year, flow exceeds generating capacity and is diverted over the falls. Canada in particular had inadequate aquaducts to use their total allotment during peak flow.

During the summer, the water level in the lower Niagara changes by 3' in the morning and evening as a result of diversion. The tour boat Maid of the Mist is hauled on the final days of the "summer months" because the water is too shallow to accomodate it either at night or during the winter.

In modern units used in Canada and the rest of the world the treaty becomes:

The 1950 water diversion treaty commits 2800 m^3/s (or 3000 m^3/s if rounded) to go over the falls during summer daytime hours for scenic purposes, and 1400 m^3/s (1500 m^3/s rounded)at all other times. Dates and hours are rigorously defined in the treaty. The balance of water (roughly 66 % of the flow) goes through power plants instead of over the falls. This diversion has decreased erosion of the falls by reducing flow (although the purpose is to make power). Power generation varies from year to year based on available water, although during part of the year, flow exceeds generating capacity and is diverted over the falls. Canada in particular had inadequate aquaducts to use their total allotment during peak flow.

During the summer, the water level in the lower Niagara changes by 1 m in the morning and evening as a result of diversion. The tour boat Maid of the Mist is hauled on the final days of the "summer months" because the water is too shallow to accomodate it either at night or during the winter.




At least when it it is specified in cubic metres, I or anyone can see that 2800 m^3 is 2 800 000 litres or about 3 ML. I didn't need a calculator or a conversion table to convert it to litres as a person not understanding what cubic feet are if they have to change it to gallons would require, and then with a 50 % chance of error if you used the wrong version of the the gallon conversion factor.

<<In modern units used in Canada and the rest of the world the treaty becomes:

The 1950 water diversion treaty commits 2800 m^3/s (or 3000 m^3/s if rounded) to go over the falls during summer daytime hours for scenic purposes, and 1400 m^3/s (1500 m^3/s rounded)at all other times. >>

Well the treaty is in cubic feet per second, and 2800 m^3/s is in violation of it. We have talked before of rounding "specward." Since it is a minimum, the number needs to be rounded up. Whether to choose 2831.7, 2832, or 2840 m^3/s or some larger, more rounded number is certainly a matter for engineering debate. 2800 m^3/s is a matter for a lawsuit by the Maid of the Mist and others associated with the tourism industry, and a violation of the treaty. On the other hand, the power companies don't want to round up too much as it comes from their water allocation and water is power.

There have been several technical amendments to the treaty since 1950 and none have converted the number to SI, even though Canada has since gone metric, and the US is now at least partially metric.