April 21, 2008

Underground Utilities

Potholes wreak havoc on Ontario’s infrastructure

DON PROCTOR

correspondent

Mountains of snow and frequent freeze-thaw conditions in Toronto and much of Ontario this winter have pounded streets and highways into pothole nightmares. But municipalities could face more than road repairs in the months to come as a result of the pothole epidemic.

The water infrastructure and a host of other utilities buried beneath those roads can be weakened by the damaged road surfaces.

“Potholes have a dramatic impact on the water infrastructure,” said Frank Zechner, executive director of the Ontario Sewer and Watermain Construction Association.

“What happens to the road surfaces impacts the densely-packed subsoil which, in turn, impacts the pipes below it.”

If a watermain is old, brittle and fragile, a busted up road may be enough to speed up the potential for a serious break in the pipe.

In a city like Toronto, where many watermains are reaching maturity, potholes could spell disaster for the water infrastructure over the next 10 years, he said.

The average age of Toronto’s watermains is more than 50 years old, but some of the oldest cast iron mains are about 100 years.

“They may be good for another 10-20 years but some of them won’t last that long,” said Zechner.

Also nearing its lifespan is the network of thin-wall steel pipes installed in the 1950s and ’60s.

While Zechner said he doesn’t see Toronto’s aging water infrastructure in critical condition, he said money needs to be allocated for proper repair and replacement programs now.

“Municipalities like Toronto must do a thorough inventory of what needs replacing and prioritize the repairs and replacements,” he said. “The key is to know what the life expectancy is well before it’s up and have a plan in place to replace it. That way you’ll see less breaks and disruptions.”

It is simpler said than done as it is impractical and often unnecessary for cities to just start digging up roads to inspect watermains.

“Quite often when they (the municipalities) do tie-ins, replacements or a repair to a break, they have the opportunity to assess the condition of other connecting pipes,” Zechner said.

Sometimes the signs that a line needs replacement are obvious. He cited a case where a watermain broke three times over a nine-month period at Lakeshore Road and Spadina Avenue in Toronto.

“The first couple of times the city put patch sleeves on it because they hadn’t scheduled it for major work for a couple of more years.”

It might have been smarter for the city to move that schedule up, rather than get stung by the hefty cost of Band-Aid measures, he said. When a watermain breaks, emergency repairs often involve curbs and sidewalk replacements and extensive work to, or complete replacement of, the roadbed.

What’s more, premium prices are paid to get the job done immediately, he pointed out.

Potholes are created when moisture from rain and thawing snow finds its way into cracks and crevices in road surfaces and then expands during rapid freezes to damage the asphalt.

Add heavy pounding vehicular traffic to the scenario and the damage caused by vibrations in the subsoil can wreak havoc on the infrastructure below the surface.

The freeze-thaw problem has increased over recent years, said Zechner. It is no coincidence that many major watermain breaks are directly under roads with high volumes of heavy truck traffic, he added.

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