Greater Winnipeg Water District aqueduct
The Greater Winnipeg Water District aqueduct supplies the city of Winnipeg, Manitoba with water from Shoal Lake, Ontario. It was put in service in 1919 [1] and cost nearly CDN $16 million. It has a capacity of 85 million Imperial gallons per day (4.4 cubic metres per second) and extends approximately 96 miles (153 km) from an intake structures on Shoal Lake to the Deacon reservoir on the east side of the city. Water flows by gravity from the lake, since the aqueduct drops about 300 feet (90 metres) over its length.[2] The Greater Winnipeg Water District Railway was built for construction and maintenance of the aqueduct. The capacity was planned for a city of one million inhabitants; peak water usage by the city was in 1988 and the capacity of the aqueduct has never been entirely used. An additional 12-mile (19 km) branch was completed in 1960.
Description
The entry structure is located at Indian Bay, Shoal Lake Ontario at 49°37′21″N 95°11′44″W / 49.62250°N 95.19556°WCoordinates: 49°37′21″N 95°11′44″W / 49.62250°N 95.19556°W. On its way to Winnipeg the aqueduct and railway pass through East Braintree, McMunn, Hadashville, Spruce, Larkhill, Monominto, Millbrook and Deacon stations. [3]
The system consists of about 134 km of buried concrete unpressurized conduit and 16 km of buried pressurized inverted siphons. Over its length the aqueduct crosses eight rivers. The conduit was built using the "cut and cover" method with an unreinforced concrete arch resting on a cast in place base invert. Sections at road and rail crossings had reinforcing steel. Siphon crossings of rivers were made as reinforced round concrete tubes. The interior dimensions of the aqueduct were selected so that no internal pressure was developed by the water flow; nineteen different interior sections were required. For inspection and maintenance, manholes were provided at approximately 1 mile intervals, which allow insertion of a small boat for inspections. Vent pipes in the manholes allowed controlled entry of air.
Structural design was complicated by the widely varying ground conditions, ranging from rock to soft peat soil. In some places, gravel fill was brought in to replace unsuitable material excavated. The depth of backfill was intended to protect the aqueduct from freezing.
To allow surface water to drain freely across the path of the aqueduct, inverted siphons were installed at fifty-six locations. Freezing was prevented by ensuring the outlet level was always below water level, preventing cold air from entering the siphon.
Since the Falcon River entering Shoal Lake drains a considerable area of muskeg, a dike was built in the lake to prevent brown, organics-laden water from being drawn into the aqueduct. The intake structure included dual intake chambers to allow for maintenance of one while the other was in use. Again, to prevent cold air from entering, the intake level was well below the lake level.
Initially the aqueduct terminated at a reservoir built on McPhillips Street, which had been the center of the city's original water system. The design of the project included provisions for an additional reservoir approximately 21 km east of the McPhillips reservoir. This would allow for peak loads to be served in excess of the aqueduct's nominal capacity and allow for maintenance shutdowns of the aqueduct without interrupting the city's water supply. The McPhillips reservoir in the north-west part of the city holds 227 megalitres. The Wilkes reservoir in the southern part holds 251 megalitres. The McLean reservoir in the eastern part of the city holds 205 megalitres. The Deacon reservoir near 49°50′57.29″N 96°56′07.63″W / 49.8492472°N 96.9354528°W, built in 1972 with eight open cells, holds 8800 megalitres, equal to a 20-day supply for the city. It is named after Thomas Russ Deacon, who as Mayor of the city drove efforts to secure the Shoal Lake water supply.
See also
References
- ↑ http://www.mhs.mb.ca/docs/pageant/24/winnipegaqueduct.shtml The Building of the Winnipeg Aqueduct, retrieved 2014 July 25
- ↑ http://www.winnipegrealtors.ca/Resources/Article/?sysid=936 90th anniversary of Shoal Lake aqueduct, retrieved 2014 July 25
- ↑ http://www.ryerson.ca/~amackenz/history/national/w.html Shoal Lake Aqueduct, retrieved 2014 08 30
Further reading
- David Ennis, Developing a Domestic Water Supply for Winnipeg from Shoal Lake and Lake of the Woods: The Greater Winnipeg Water District Aqueduct, 1905 – 1919, retrieved 2014 07 29, Master's thesis with photographs