by Frank Bucholtz, Mission Record
Strengthening the dikes protecting low-lying areas of Mission from high-water events along the Fraser River will be a multi-year challenge.
Mission council discussed the two dikes it is responsible for at its Oct. 19 meeting. One protects the low-lying area in Mission City from Lougheed Highway near The Junction shopping area (on the west) to the area east of the West Coast Express staging area along the Canadian Pacific railway tracks. That area is about 121 hectares in size.
The second dike is in the Silverdale area, and protects 364 hectares, most of which is agricultural land.
A report to council said the most recent work on the Mission city dike took place in 2011, and the dike is in good condition from its western end to the Mission harbour office on Harbour Avenue. However, east of that location, there are a number of areas where it requires strengthening to handle the largest freshets.
However, the district does not have a right-of-way in all areas where the dike is located, and to obtain that would be expensive. The report suggests improvements be done on a gradual basis as redevelopment of area properties allows Mission to obtain a right-of-way.
The report suggests that improvements to the Silverdale dike would be too expensive.
Both dikes were designed in 1969 to withstand flooding equivalent to the 1894 Fraser River flood, the highest recorded flood on the river. However, modeling in recent years has indicated that they need to be somewhat higher to handle an equivalent flood.
During high water in 2007 and 2012, the district needed to use lock blocks and bastions as temporary flood protection. Another concern is that some areas north of Lougheed Highway flooded in 2007. That had not previously been recorded.
Staff recommend the district work on a design and business plan for upgrades, so that if grant money becomes available, it can apply.