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Shady Island could become part of city’s dike system
Some potentially view-spoiling decisions will be made at city hall in the coming months and years as the city begins planning on how it will brace itself against the threat of rising sea levels and the damage posed by storm surges and high tides.
At Monday’s council meeting, staff presented a report on the first phase of the Dike Master Plan, which will look at necessary fortifications against flood threats in Steveston and the southern West Dike area. The work, once approved, would be done over the course of many decades.
The master plan is intended to protect the city from ocean storm surges and the Fraser River freshet, and help the city adapt to rising sea level.
A 49-kilometre system of sea and river dikes are the backbone of Richmond’s flood protection infrastructure.
Creating a master plan for the Steveston area is a “priority,” and the lack of such a plan hinders development, the report by John Irving, director of engineering for the city, said.
Armed with a $200,000 budget to study the issue, the city hired Delcan/DHV as the lead consultant of the effort.
And Delcan came up with two primary dike alignment solutions, one of which would incorporate Shady Island as part of a new dike structure, the other to raise dikes in their current alignment.
Using the existing dikes and simply raising them is problematic because of a lack of space, conflict with utilities and development and construction scheduling, the report to council states.
If the city opts to make Shady Island part of its diking system, the Steveston Harbour would be enclosed on both its eastern and western ends by “gates or other structures that would close the channel during combined high tides and storm surge events,” the report states.
Another option being explored is closing the eastern opening of the channel, though the impact of that on the ecology must still be examined, the report states.
If Shady Island were to become part of the dike, that would come with many benefits:
•low community disruption
•relatively easy to raise in the future
•minimises ground improvement impacts to existing buildings and infrastructure
•minimises impact on village character and heritage assets.
Among the challenges is the fact that the city does not have jurisdiction over land use on Shady Island.
Using the existing dike location is made easier since the city owns the land and rights of ways, and can build the structure in pieces and use temporary infrastructure for effective flood proofing. But construction would lead to high community disruption, will result in further disruptions if the dike needs to be raised in the future, and the ground improvement may impact existing buildings and infrastructures.
At the same time, using the current dike location would have a “high impact on existing village character and heritage assets,” the report states.
As far as the cost of the project, it would be in the millions of dollars, though no figures were mentioned in the staff report, other than a mention that “initial cost estimates are similar for both options.”