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For the second time in six months, a steel plate inside a narrow sewer shaft buried deep beneath a New Edinburgh street broke off, got stuck and sent untreated sewage streaming into the Ottawa River.
The city estimates 18 million litres of sewage and rain water — enough to fill seven Olympic-sized swimming pools — flowed into the river Thursday before crews were able to remove the plate.
The incident is the latest in a long line of problems caused by the Keefer Regulator, one of five float-operated gates installed in the early 1960s to control the flow between the city’s combined rain-and-sewage pipes and an interceptor pipe designed to carry sewage for treatment at the Robert O. Pickard Environmental Centre.
On July 31, a dislodged plate backed up the system and released eight million litres of sewage into the river.
Before that, in 2008, the province fined the city $562,500 after the regulator’s gate jammed open for 11 days in August 2006, releasing nearly a billion litres of untreated sewage into the river.
On Friday, Dixon Weir, the city’s general manager of environmental services, admitted incidents like this shake an already tenuous public confidence in the city’s pipes.
“Infrastructure failures are sometimes unpredictable and even through best intentions and best efforts, one is not able to prevent certain situations from occurring, so one relies on early detection, quick response and rectification,” he said.
Weir said there is no construction-ready plan to remove the remaining steel plates in the shaft, but that is likely to change soon.
“The events of (Thursday) night have certainly caused that to become a more pressing issue than it was when we were just looking at one failure in 50 years.”
There is no alternate route for directing sewage from one pipe to another, so Weir said a diversion chamber will have to be built to re-direct flows away from the shaft before work can be done on it.
“We certainly wouldn’t ask for or consider diverting all sewage to the river while we carried out that longer, necessary repair, so we’ll have to come up with a solution that will allow us to divert sanitary sewage around the drop shaft while the repairs are carried out,” he said, adding it’s too soon to know how much the project could cost.
Of the five gates in the sewer system, the Keefer Regulator is the only one with steel plates inside the shaft.
According to Weir, the plates were installed to protect the four-metre cement shaft from being damaged by the constant flow of liquid through it. The rectangular shaft is less than a metre wide and about two metres across.
Workers in protective gear had to be lowered down on cables to remove the dislodged plate.
“All of this work is carried out in an inhospitable and dangerous environment,” Weir said.
Rideau-Rockcliffe Councillor Jacques Legendre said Friday he wasn’t aware of the latest spill until the Citizen requested an interview with him to discuss it.
“It’s frustrating to hear that things are falling off the internal walls there,” he said, adding that work done to the regulator over the summer disrupted the neighbourhood.
He couldn’t say when Ottawa residents could expect the regulator to work properly. “I don’t have an answer for this. I’ll be discussing this with senior staff as soon as possible.”