Squamish's dikes do not meet the provincial standard and bringing them up to that standard will cost the District of Squamish $2 to $4 million.
"It's calculated, based on the good information we have now, that the dike will overtop and breach in a one-in-200-year flood event," engineering manager Brian Barnett told council on Jan. 11. "This is a top priority item."
Barnett presented the detailed report by Kerr Wood Leidal Associates Ltd., a report he referred to as a "post-mortem study" using all the information from Squamish's last major flood in 2003.
"The 2003 October flood is considered the flood of record," Barnett said. "From that event there were surveys taken of the high water marks, analysis of level gauges that are located in different rivers throughout Squamish and quite a bit of information was collected just by doing a post-mortem exercise."
He said the results were alarming, explaining that three areas need to have the dike raised to meet provincial standards - Brackendale, Eagle Run and North Yards.
"Our system is designed for one-in-200-year, but this analysis found that it was one in 75 years in certain rivers, and at one in 150 years in other rivers because of when the watershed came down," he said.
One in 200-year level refers to the likelihood of the flooding - once in 200 years there will be enough heavy rain that the dike will be overtopped. One in 200 years is the provincial standard but when the consequences of a flood would severely impact a community, often the community will opt for greater protection.
Barnett said a good example of supporting the need for a more secure debris structure is a precarious section of the Fitzsimmons Creek dike in the Resort Municipality of Whistler.
"They brought their debris structure standard to one in 1,500 because if the dike was breached it would wipe out the entire Whistler Village and destroy the economic viability of the town," said Barnett in an interview with The Chief on Friday (Jan. 21).
He said as the diking authority, mayor and council hold the power to decide what diking level is sufficient, as long as the provincial standard is met. Until a few years ago, diking was a provincial responsibility but in 2003 the province made flood protection the responsibility of municipalities.
"It's up to the municipalities to protect themselves," said Barnett.
Barnett said one issue outlined in the report was that very little gravel has been removed from the Squamish River in the past 10 years.
"It turns out there's about 117,000 cubic metres a year coming down and settling into the Squamish River," he said. "So we have a limited dike system and a creek bed filling up with gravel - that's an alarm bell that's been identified in this report."
He said at a minimum 1.6 kilometres of dike should be upgraded to meet the flood freeboard profile.
Coun. Doug Race suggested getting started as soon as possible and testing the marketplace while "there's some bottom basement prices going on."
Barnett said Race had a point.
"It looks like the market's good right now," Barnett said. "If council's ready we could move forward on this issue immediately."
The response from council made it clear that lawmakers were more than ready.
"I agree this is one of our highest priorities and should be dealt with as such," said Coun. Paul Lalli.
"I think we should move forward immediately - I don't want to wait until it's too late," said Coun. Corinne Lonsdale. "How can this not be a priority?"
Barnett didn't shy away from the price tag on the project - he told council the entire project would cost between $2 and $4 million and said gravel removal is a costly component, at $10 per cubic metre of gravel removed.
However, he said there are some grants available and that in other communities, grants have paid approximately two thirds of the capital cost.
Barnett has already applied for two grants - $650,000 from the Emergency Management of British Columbia and another approximately $2 million grant for gravel removal specifically.
He said it's unlikely the engineering department will ask to include the work in this year's capital budget because "it could take a year to get the planning work done between getting permits from the Ministry of Environment and the Department of Fisheries and Oceans.
"It's more likely the department would ask to spend $50,000 in 2011 for planning and then start the expensive dike project in 2012," he said.
Race put forward a recommendation that staff pursue establishing a joint committee with the Squamish Nation and bring back a recommendation on the structure and mandate of the committee. Staff was also instructed to investigate including a diking component in the 2011 capital budget and to review dike impacts on Official Community Plan designations.
