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If Don Valley pipe collapses, raw sewage would spill into river
Jan 01, 2009 04:30 AM
Comments on this story (7)
John Spears
City Hall Bureau
A huge sewer line buried beneath the Don Valley has cracked, and city officials are scrambling to find out how bad the problem is, and how to fix it.
The pipe, 2.4 metres to 2.7 metres in diameter, carries sewage from 750,000 people, living in an arc from western Scarborough to Downsview. It starts in the Don Valley, and runs beneath Coxwell Ave. to the Ashbridges Bay sewage plant.
At worst, if it were to break or collapse, its contents would spill into the Don River.
On the plus side, there's no current indication of trouble. The cracking, discovered by a robotic camera during routine checks last week, may have been there for years.
Lou Di Gironimo, general manager of Toronto Water, said a series of cracks are visible along a 60-metre section of sewer line, just north of O'Connor Dr. In some cases, one edge of the crack is several centimetres lower than the other.
"We're not seeing a collapse, there's no obstructions, the flow is working fine," Di Gironimo said. Extra monitors have been placed in the sewer to keep a closer eye on how it's working.
The pipe, built about 50 years ago, is steel plate on the outside, with 56 centimetres of concrete inside the steel.
The cracked section appears to have sunk about 15 centimetres from its original position, but Di Gironimo said it's hard to be certain.
What is certain is that the city is taking the cracks seriously.
"Our staff have said it's like seeing a crack in the foundation of your house," said Councillor Glenn De Baeremaeker, who chairs Toronto's public works committee.
"The alarm bells have gone off for the City of Toronto. If this pipe collapses, we would have a catastrophic event on our hands. Because you have more water going through that sewer pipe than is in the Don River."
If the pipe is blocked, it's designed to spill its contents into the Don.
"The Don River, from bank to bank, would be covered with raw human sewage," said De Baeremaeker.
"It would devastate the Don River. Our harbourfront would very quickly get filled up with raw human sewage, and everything else that goes in there."
Di Gironimo said the cracking has occurred just downstream from where four other big sewer pipes converge into the Coxwell sewer. Those sewers service western Scarborough, Don Mills, Downsview and North Toronto, he said.
City staff and outside consultants are now using an array of tools, including sonar and laser equipment, to assess the damage and analyze how stable the ground is around the sewer.
The problem was picked up because Toronto Water's long-term plan is to twin the Coxwell sewer, Di Gironimo said. Assessing the existing sewer was part of the project, and it's tough to do because it can't be shut down and emptied.
"Our recommendation is we need to proceed to work on a bypass route as quickly as we can," he said.
That would involve building a new sewer line 500 to 600 metres long around the damaged area, Di Gironimo said. He couldn't estimate the cost.
De Baeremaeker said it's likely to cost in the tens of millions of dollars to fix the problem.
A report on the status of the sewer and the prospects of fixing it is to be delivered to a meeting of the works committee on Tuesday.
If Don Valley pipe collapses, raw sewage would spill into river
Jan 01, 2009 04:30 AM
Comments on this story (7)
John Spears
City Hall Bureau
A huge sewer line buried beneath the Don Valley has cracked, and city officials are scrambling to find out how bad the problem is, and how to fix it.
The pipe, 2.4 metres to 2.7 metres in diameter, carries sewage from 750,000 people, living in an arc from western Scarborough to Downsview. It starts in the Don Valley, and runs beneath Coxwell Ave. to the Ashbridges Bay sewage plant.
At worst, if it were to break or collapse, its contents would spill into the Don River.
On the plus side, there's no current indication of trouble. The cracking, discovered by a robotic camera during routine checks last week, may have been there for years.
Lou Di Gironimo, general manager of Toronto Water, said a series of cracks are visible along a 60-metre section of sewer line, just north of O'Connor Dr. In some cases, one edge of the crack is several centimetres lower than the other.
"We're not seeing a collapse, there's no obstructions, the flow is working fine," Di Gironimo said. Extra monitors have been placed in the sewer to keep a closer eye on how it's working.
The pipe, built about 50 years ago, is steel plate on the outside, with 56 centimetres of concrete inside the steel.
The cracked section appears to have sunk about 15 centimetres from its original position, but Di Gironimo said it's hard to be certain.
What is certain is that the city is taking the cracks seriously.
"Our staff have said it's like seeing a crack in the foundation of your house," said Councillor Glenn De Baeremaeker, who chairs Toronto's public works committee.
"The alarm bells have gone off for the City of Toronto. If this pipe collapses, we would have a catastrophic event on our hands. Because you have more water going through that sewer pipe than is in the Don River."
If the pipe is blocked, it's designed to spill its contents into the Don.
"The Don River, from bank to bank, would be covered with raw human sewage," said De Baeremaeker.
"It would devastate the Don River. Our harbourfront would very quickly get filled up with raw human sewage, and everything else that goes in there."
Di Gironimo said the cracking has occurred just downstream from where four other big sewer pipes converge into the Coxwell sewer. Those sewers service western Scarborough, Don Mills, Downsview and North Toronto, he said.
City staff and outside consultants are now using an array of tools, including sonar and laser equipment, to assess the damage and analyze how stable the ground is around the sewer.
The problem was picked up because Toronto Water's long-term plan is to twin the Coxwell sewer, Di Gironimo said. Assessing the existing sewer was part of the project, and it's tough to do because it can't be shut down and emptied.
"Our recommendation is we need to proceed to work on a bypass route as quickly as we can," he said.
That would involve building a new sewer line 500 to 600 metres long around the damaged area, Di Gironimo said. He couldn't estimate the cost.
De Baeremaeker said it's likely to cost in the tens of millions of dollars to fix the problem.
A report on the status of the sewer and the prospects of fixing it is to be delivered to a meeting of the works committee on Tuesday.
