Downtown tunnels finally ready to keep sewage out of river

More than a decade after Ottawa city council launched a series of projects aimed at keeping sewage from spilling into the Ottawa River, amassivestorage system under the city is finally ready to hold all that dirtywater.

Mayor Jim Watson stood at LeBreton FlatsFriday afternoon to announce that the $232-million "engineering marvel," which began construction in 2016, was now ready to store water when the next big storm hits.

The city built apair of tunnels, 6.2 kilometres in total,and 15 underground chambers capable of holding up to 18 Olympic-sized swimming pools worth of sewage.

One tunnelruns east-west from LeBreton Flats to New Edinburgh, intersecting another thatruns north-southalong Kent Street from the Queensway to behind the Supreme Court of Canada.

"The [tunnels]will capture and allow proper treatment of surface runoff and wastewater that would otherwise flow untreated into the Ottawa River during very wet weather," Watson said, thanking federal infrastructure minister Catherine McKenna and NepeanMPP Lisa McLeod for the $62 milliontheir governments each contributed.

The tunnels will also help reduce basement flooding in some low-lyingneighbourhoods, like the Glebe and Centretown, and will allow the city to better inspect its existing pipes under the downtown, Watson noted.

The water could also be cleaner next summer at Petrie Island beach, which is downstream from locations where Ottawa's combined sewage and rain pipes release water to the river.

Overflows dramatically reduced

The sewage storage tunnel is the "cornerstone" of the Ottawa River Action Plan, a set of 17 projects approved by city council in February 2010, said Alain Gonthier, the city's associate general manager of public works.

Over the years, the city has been working to build pipes tocarry sewage and rainwater separately. No longer does Ottawa send sewage into theOttawa River 70 to 80 times annually, he said.

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These storage tunnels will be the final milestone, Gonthiersaid.

"In a typical year, we'restill having 20 to 30 overflows to the river. They've been reduced over the years," explained Gonthier."What this is going to do is to reduce it to two or less, so it'sa significant reduction."