The mood was subdued at City hall Tuesday as a city engineering official presented a mostly reassuring freshet update to Chilliwack council.
Water levels on the Lower Fraser are expected to crest by Friday or Saturday, and properties inside the dikes are not at risk to be overtopped, say city officials.
Projections for the next week or so have peak flow estimates coming in at between 12,500 and 13,500 cubic metres per second on the Fraser River at Hope, or about the equivalent of 6.4 or 7 metres at Mission.
That’s more snow melt and rain water coming down the river than has been seen in decades. There’s also more rain on the way.
“To put everything into context, we haven’t seen flows over 12,000 cm/s since 1972,” said David Blain, director of engineering for the city, in his freshet report to council.
But despite the high water, everything located inside the city’s 50 km of diking infrastructure will be protected, up to a level of 8 metres at Mission.
“Even the highest projection so far is only up to 7 metres. There’s no risk the dike will be overtopped,” he said. “It’s not even going to come close.”
For the 42 homes outside the dike protection, the story is a little different. Owners are nervously watching the water levels.
Several could likely see some water on their properties, depending on weather conditions in the next few days.
“Areas outside the dike generally will get wet,” Blain said. “The other thing we’ll see is seepage through the dike.”
That’s expected.
“But some (property owners) who haven’t seen seepage for years, are going to see it this year.”
Weather is still a factor, and rain that could add to peak totals are being called for the end of the week.
“The River Forecast Centre isn’t factoring in projected rainfalls into the peak flow projections they’ve give us, so the final totals could be much higher,” said Blain. “It makes makes the forecast more accurate but it gives us less lead time.”
At Carey Point, more than half the trees along one section are going into the water rapidly due to ongoing erosion. It’s near the newly constructed berm, put in by a group of residents, made of gravel and dirt that stretches a kilometre long.
Both the recently completed berm and the engineered check dam are built to protect up to a measure of 6.4 metres at Mission, Blain explained.
“The reason why we picked that elevation is that it ties into existing farms, which are all at that elevation,” he said.
City crews are making standard freshet preparations, checking pumps and conducting daily dike patrols. All the pump stations have been checked and restored by city crews and are “functioning well,” according to Blain.
They’ll upgrade the dike monitoring to 24-hour patrols if the river gets up to 6.5 metres.
Most of the 42 homes or structures, located on a total of 200 properties outside the dike, are situated “up high” and built to “proper flood construction levels,” he said.
Only a few older structures are not, and sandbagging might be undertaken by owners as a precautionary measure.
“We’ll be keeping an eye on them,” Blain said.
An evacuation alert was already issued earlier this week to have residents in the unprotected areas ready to leave at a moment’s notice. Emergency Social Services will find accommodations for any evacuees for a maximum of three days.
“We’re encouraging people to get ready by getting together what they need to be prepared to go,” said Mayor Sharon Gaetz. “I hope we all stay high and dry.”
Check out more at chilliwack.com for emergency preparedness details, like what to put in grab-and-go bags.
jfeinberg@theprogress.com
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