Protecting Winnipeg
The Manitoba Floodway Authority has selected Acres Manitoba, a Hatch Acres company, as part of a team undertaking the detailed design and contract administration for Parcel 2 of the Red River Floodway Expansion – continuing more than 30 years of Acres involvement with the floodway. Our Winnipeg office was established in 1965, in part, to assist in the floodway’s design and construction.
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History In 1997, Manitoba experienced the ‘Flood of the Century’ which came close to the floodway's capacity and threatened Winnipeg’s protection. |
Expansion
The expansion project will more than double the floodway channel capacity from 1,700 cubic meters (60,000 cubic feet) per second to 4,000 cubic meters (140,000 cubic feet) per second. This will increase Winnipeg’s flood protection from a 1-in-90-year probability of recurrence to a 1-in-700-year probability.
When completed, the project will protect more than 450,000 Manitobans, 140,000 homes and 8,000 businesses; and prevent more than $12 billion in potential damages to the provincial economy in the event of a design flood (1-in-700-year flood).
The expansion involves extending and raising the 65-km west dyke, widening the floodway channel by 60 percent, modifying the inlet structure, replacing/modifying eight drainage structures, reconstructing Winnipeg’s potable water aqueduct, replacing and upgrading 12 bridge crossings, modifying utilities and services, expanding the outlet structure, and improving erosion protection downstream of the floodway. The team performed a sophisticated optimization analysis to define the most economical floodway channel geometry. This process determined the optimal channel cross-section at intervals along the channel by taking into account the unit excavation costs, incremental costs for raising and widening bridges, variations in flow conveyance for increases in channel width and/or depth, hydraulic losses at bridges, tributary inflows, and other hydraulic and geotechnical criteria. The analysis significantly reduced the overall cost of the floodway expansion. |
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We also analyzed the expansion of the outlet structure. Various design concepts and options were first assessed using a 3D numerical model to determine the most economical and feasible design. A 1:50 scale physical model was subsequently constructed and tested to verify and confirm the results of the numerical modeling. The physical model also provided a visual assessment of the performance of the design and provided additional data that was not readily identified by numerical modeling. Using the physical model results, the numerical model was further refined and used in the final design.
The team was also responsible for modifications to the 65-km west dyke that prevents flood waters from flowing over the western flood plain into the city. This dyke will need to be raised and extended to provide adequate protection against overtopping during the design flood. The team used sophisticated 2D hydraulic and wave simulation models to estimate the necessary crest elevations over the length of the dykes. We also assessed erosion protection requirements along the dyke line to prevent wave-induced erosion should a wind event occur coincident with the flood peak.
Approximately 27 million cubic meters (35 million cubic yards) of earth will be moved in the process. The expansion is expected to last five years, with channel widening complete by spring 2009 and bridge work carrying over into spring 2010.
For further information, please contact:
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Warren Gendzelevich |
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