EDITOR,
My special interest is natural hazards and public safety. I have been following the election through The Chief and attendance at two all-candidates' forums. In this election, I have not witnessed any meaningful discussion of dike safety despite the fact that it is one of the most pressing issues facing Squamish today.
The Sea to Sky experienced its last regional flood event in 2003. At Eagle Run the Squamish River came within 50 centimetres of overtopping the dike and caused strong seepage through the dike. Both the near overtopping and seepage illustrated the potential for a dike breach. If the dike were to breach at Eagle Run, a rush of water would tear down Government Road, affecting residential properties, a gas station, commercial properties, a school, and important municipal infrastructure including the sewage treatment plant and the Dryden Creek and Harris Slough pump stations.
At the time, the 2003 flood was described as having a 100-year recurrence interval, but has more recently been estimated to be a 150-year return. To frame these odds statistically from a human lifetime perspective, a flood of that magnitude has a 30 to 40 per cent chance of occurring in 50 years, and just because one happened recently does not lessen the chance of another similar or larger event occurring again in the immediate future. Further, by legislation the dikes are supposed to protect us against the 200-year return event, or one with a 22 per cent chance of occurrence in 50 years. The 2003 flood event clearly demonstrated that our dike system is not up to that provincial public safety standard. The conclusion is obvious - we face a very severe and unacceptable risk of dike failure.
So what are our staff and council doing about it? Staff and past councils can point to an upgraded pump station at Judd Slough, a section of raised dike downstream of the Mamquam River confluence, the addition of riprap at a few locations and last year, the completion of two major engineering reports. But given the risk, this has happened all too slowly, and one may question whether there has been a proper prioritization of works.
Finally, in April 2011 the District announced the receipt of a grant of $1.2 million to apply to various dike projects including gravel removal and remediation of Eagle Run seepage. It is up to this council to oversee this very important work. In doing so, there are some very difficult issues that need to be addressed including landowner negotiations and possibly expropriations, and negotiations with the Federal Department of Fisheries and Oceans. Our new council needs to become familiar with this file, spending needs to be prioritized to address the most pressing risks first, and pressure needs to be put on staff to get it done before another decade goes by.
Pierre Friele
Professional Geoscientist
Squamish
