If you had looked at the right time, you would have seen artifacts of Montreal’s history in the dusty pit that is now St-Denis St.
The ancient infrastructure, some more than 100 years old, is being replaced.
A tour of the site last week did not reveal any of the old pipes — most were taken away several weeks ago. However, photographs of the sewer submitted by the city showed tunnels made out of red bricks, with grout holding them together, built in 1943.
“It was done on site by masons and day labourers — and the wall was three bricks wide,” said Fernando Rivera, an engineer and project manager for the city’s public works department.
The sewer is relatively new compared with the old pipes used to supply drinking water to the buildings. Some of them date back to 1888. Those pipes were showing their age in recent years, leaking profusely, and resulting in many water main breaks, Rivera said.
Montreal executive committee member Lionel Perez said the city identified spots on the street that were in danger of crumbling because of all the erosion caused by the water leaking out of the Victorian-era pipes.
The old cast iron pipes are being replaced by new ones made of ductile steel, which Rivera explained is a superior material.
“The old steel is very fragile, and not very resistant to corrosion,” he said. “It was made of the same type of steel used to build the Titanic (scientists have suggested the ship had poor quality steel, which ultimately led to its rapid sinking). These were good products for the time, but now we use ductile steel, which is more flexible. It stands up better to cars and trucks driving over the road, and doesn’t corrode as quickly.”
The new pipes are now all built to measure in factories, and the steel water supply pipes fit together like puzzle pieces, and lined with plastic to reduce corrosion and leakage. On Thursday, a pile of the black pipes was sitting at the construction site, with pink marks on them, showing that a city engineer had been to the plant and tested the batch of pipes to assure they were made well.
“We don’t install the pipes unless we see that pink mark,” Rivera said.
New sewer pipes are made of concrete rather than brick, and are also fabricated in a factory beforehand.
“The new pipes have a theoretical useful life of 75 and 100 years,” Rivera said. “The old materials had a theoretical useful of 40 years, but it obviously lasted much longer.”
As the city is replacing pipes, crews are noticing some parts of the underground that were made with lead. The city is replacing its portion of the pipes, up to the property lines, and advising property owners when it finds that the pipes on their property are made of lead, Rivera said. Property owners are not obliged to change lead pipes to conform with new standards for lead content in drinking water, but they have to pay for it themselves if they do.
St-Denis St. was last paved in an era where city workers laid a coat of concrete under the asphalt. That method is no longer used — now crushed rocks are laid under asphalt. So the city sends the concrete pieces to be crushed into small stones that will be used as roadbeds for future projects.
Other materials are also recycled. The bricks are crushed and new bricks are made out them. Manhole covers and old valves are sent to the boroughs to be reused for repair projects.
THE PROJECT: Replacing pipes, underground wiring, lampposts and asphalt on St-Denis St. between Duluth Ave. and Marie-Anne St.
PROJECTED COST: $14.4 million
DATE STARTED: Fall 2015
PROJECTED END DATE: November 2016
PROGRESS UPDATE: East side work completed. West side: 40 per cent of the work to replace aqueduct pipes completed.
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