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Sea Level Rise and Coastal Flooding Requirements for Waterfront Structures in Vancouver, BC

A study made in 2008 study on the effect of Sea Level Rise in British Columbia (1) estimates Sea Level Rise in Vancouver will be ranging from 0.89 m to 1.03 m by the year 2100 (based on extreme high estimate of global sea level rise).

As a result of expected Sea Level Rise, the Flood Construction Levels in Vancouver, which define the minimum elevation of the underside of a floor system or top of concrete slab of any building used for habitation, business or storage of goods, are being raised in flood-prone areas. Around Burrard Inlet, English Bay, False Creek and Fraser River Flood Plains, the new flood construction level requirements are:

· For buildings located within the areas shown shaded on Figure 1, the flood construction

level 4.6 m Greater Vancouver Regional District datum.

· For buildings located in the areas shown shaded on Figure 2, an additional elevation

allowance above 4.6 m may be required for wave run-up.

Figure 1 - Burrard Inlet, English Bay, False Creek and Fraser River Flood Plains (2)

Figure 2 - Burrard Inlet, English Bay, False Creek and Fraser River Flood Plain Wave Effect Zone (2)

Marine and coastal structures need to be designed to protect Vancouver’s heavily urbanized environment against Sea Level Rise and coastal flooding. As such, new Waterfront Structures for the City shall have a design crest elevation equal or greater than the Flood Construction Level (4.6 m), plus an appropriate allowance for wave run-up, which is dependent on site-specific wavestructure interaction.

If the City approves a lower top elevation than the Flood Construction Level, the design of new Waterfront Structures shall address:

· The frequency of inundation, i.e. the minimum recurrence interval of events which will

cause flooding.

· Public safety implications of flooding / overtopping including safe access and egress from

the flooded / overtopped areas.

· Potential damage to property as a result of overtopping or flooding.

· How floodwater will be dealt with. Where possible, positive drainage paths will exist to

return floodwater to the river / sea without reliance on pumping systems.

Maintenance implications for the City for cleanup of public areas after the flood has passed.

The design of new Waterfront Structures shall also incorporate discussion and conceptualization of possible adaptation measures of the newly design structures to further Sea Level Rise of at least one additional meter. This conceptualization shall be at a minimum at the feasibility stage with estimates and sketches produced illustrating the cost, the concept, and the land requirements to complete the future upgrades (inclusive of construction staging) and identification of future proofing modification works that should be incorporated in the current design.

[1] BC Ministry of Environment, 2008, Projected Sea Level Changes for British Columbia in

the 21st Century

[2] City of Vancouver, adopted September 16th, 2014, effective January 1st, 2015, Flood Plain Standards and Requirements

[3] City of Vancouver, adopted December 2nd 2016, Marine and Coastal Structures Design Reference.

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