Flood-proofing Ottawa won’t be cheap

Jean-Marc Leger August 29, 2017 0
Flood-proofing Ottawa won’t be cheap

Cleaning up the messes from last spring’s floods here is costing millions of dollars, which gives us a clue to just how expensive it will be to prepare Ottawa for decades of more severe weather than we’ve been used to.

Land-use planners typically plan construction and drainage to withstand once-in-a-century water. They painstakingly map out the floodplains around rivers and nobody’s supposed to build on them. Ottawa’s spring inundation was a trifle compared with what’s happening in Houston, roughly a once-in-50-years flood rather than the 500-year flood Texas is facing.

But cities like Ottawa have old neighbourhoods we didn’t build to modern standards or with modern data. Parts of New Edinburgh and Old Ottawa South would be underwater in 100-year floods. So would most of Constance Bay.

Sandy Yzh, co-owner of the Lighthouse general store and restaurant, surveys the water damage caused by flooding, in Constance Bay, Tuesday May 9, 2017. FRED CHARTRAND / THE CANADIAN PRESS

Other neighbourhoods could be vulnerable if the sewers can’t keep up with a deluge. And we’re starting to build neighbourhoods again where homeowners rely on sump pumps because the ground’s too poor for sewers to drain them without help.

It’s not just the big rivers that are worrying, as people whose houses back onto Bilberry Creek in Orléans learned last May. The creek runs north from Innes Road to the Ottawa River, just west of Place d’Orléans, and one day it started eating people’s backyards.

Small landslide near Turnberry road in Orléans, May 5, 2017. Photo by Jean Levac. JEAN LEVAC / POSTMEDIA NEWS

We’ve been reinforcing the ravine with boulders, walls and steel pilings and running a six-foot sewer pipe under the creek bed, at a cost that’s climbed from an early estimate of $2 million to $4.5 million.

Way back in the ’70s the Ontario Geological Survey checked out Ottawa-Carleton’s watercourses and reported that long stretches of Bilberry Creek were risky to build near, with some slopes of the ravine alongside the creek needing “extreme remedial measures” to stay stable.

Orléans grew up around it anyway, at what we must have thought was a safe distance.

Every few years, the city and local conservation authorities send volunteer “streamwatchers” out to inspect streams and creeks. In 2015, the streamwatchers checked out Bilberry Creek.

“Very high active levels of erosion were observed from the mouth of the creek to just downstream of Jeanne D’Arc Boulevard as well as downstream of Des Epinettes Avenue in the south end of the creek,” the streamwatchers reported.

As last spring’s floods began, just north of Des Epinettes, exactly where the streamwatchers said the ravine was eroding, backyards started to slide and 20 households had to be ordered out. The last of them have only recently returned.

In the west end, years of planning have produced a plan for the Carp River after serious flooding in south Kanata in 2009. Estimated cost: $5 million. No, wait, $15 million. Actually, make it $18 million.

Hazeldean Bridge over the Carp River in Kanata in May 2012. Photo by Julie Oliver.

The National Capital Commission’s post-flood cleanup is costing $3.4 million, much of it to rebuild paths to better standards.

The city’s still tallying up its recovery costs, says Pierre Poirier, city hall’s director of emergency management. It’s also preparing an after-action report that will “review best practices and include input from a variety of internal (and) external partners.”

Partners such as Alex Cullen, the president of the Belltown Neighbourhood Association, which represents residents along the Ottawa River in the old west end, north of the Coliseum movie theatre.

Cullen is a former city councillor and knows more than most people would about his community’s hidden guts. He knew that a lot of Belltown’s water runs off into the Ottawa River through one particular drain, and that backwash up that drain was a major threat. So as the rain fell and the river rose, he and other residents went to take a look.

Alex Cullen in 2015. JULIE OLIVER / OTTAWA CITIZEN

“They’d put a steel plate across it,” Cullen says of the city. “It was like the kind you’d use to cover a hole in the road. Big and solid, but it had gaps for handles and a bit around the edges. It was good to see it there but it wasn’t going to be enough. It was going to let water through.”

Cullen and his crew piled sandbags around the gaps in the makeshift flood barrier. He donned a wetsuit himself, he says, to get in close and make sure the cracks were sealed.

Which brings us to the second worry Cullen points out: A lack of direction from the city. When they needed to tell the city something or ask a question, they called 311 or emailed — and got boilerplate replies promising full responses within a couple of weeks.

Residents woke up one day to find sand and bags by the Belltown Dome.

“The city left it to the community to organize itself and figure out where and when to use this material,” Cullen says. Everyone was willing to do the work and was glad to get the stuff, but an alert that it was coming would have been helpful. Also, a warning that the sand had salt in it, so the bags would deflate a bit once they got wet.

Volunteers patrolled the riverbank, watching to see whether the water would overtop the berm along the water’s edge, an old rail line with a bike path. That didn’t happen but likely would have in a 100-year flood. To keep Belltown safe, about a kilometre of berm needs raising.

Cullen says an old study estimated the cost of reinforcing the bank there at $16 million, though that’s for a more ambitious project than he thinks is needed — including adding an underwater slope along the outside of the berm to protect it from getting hit by waves. Even a lesser project won’t be cheap.

East of Belltown, Britannia Village is built on a little urban spit in the Ottawa River. It stayed pretty dry last spring, thanks to a decades-long effort to build berms. We got them done in 2016, at a cost of $2 million to protect about 100 households.

A lot of these projects are expensive but protect relatively few people directly, against a threat that’s practically invisible until it’s at the door. But if we don’t get ahead of flooding, it’ll swamp us whether we’re ready or not.

Original article written by David Reevely can be found here.

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