Winnipeg Free Press - PRINT EDITION
Lengthy Assiniboine earthen-dike boost
The province is raising 70 kilometres of earthen dikes along the Assiniboine River, in preparation for what could approach a one-in-one-hundred-year flood.
The province began last week raising and fortifying the dikes from Portage la Prairie to east of the Baie St. Paul Bridge near Elie.
"This is one of the hot spots in the province," said Doug McMahon, the province's executive director of water control and structures. Dikes will be raised by up to three feet. Their height will be the 1976 level -- the year of the one-hundred-year flood on the Assiniboine -- plus two feet of free board, which is an extra safety margin.
"Free board is that insurance policy," McMahon said.
Over 200 pieces of heavy equipment are on site. The upgrade is to be completed by early April.
In addition to 1976, the Assiniboine had a series of floods in the 1940s and high flows in 1995, McMahon said.
The Assiniboine dikes were first constructed in 1912, then reinforced in 1950 and again after the 1997 flood. The dikes protect farmland, farms and residences, as well as the communities of Elie, La Salle, Sanford and Starbuck. For high flood events, the Assiniboine dikes prevent the transfer of Assiniboine water to the La Salle watershed.
The work includes reinforcement with rock in some locations to protect banks from high river currents. Any large trees removed from the dikes are being salvaged for further use.
The cost of raising these dikes hasn't yet been defined but it is a multimillion-dollar project, McMahon said.
Other steps taken to reduce the potential flood impact of the Assiniboine include lowering the Shellmouth Reservoir level and maintenance work on the Portage Diversion.
Republished from the Winnipeg Free Press print edition March 19, 2011 B2
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