November 17, 2008

Sewer and Watermain

McGillivray & Sons Contractors deploys “pipe bursting” technology

DAN PELTON

correspondent

When talking about sewer and watermain replacement and repair, one tends to conjure visions of streets transformed into open pits, the roar of trucks and bulldozers, and the presence of tonnes of earth and gravel.

McGillivray & Sons Contractors Ltd. of Kitchener is out to change that scenario by being the first company in Ontario to deploy “pipe bursting,” a method of replacing existing sewer, watermain or gas lines.

It uses a new custom length line of the same, or larger, size without digging up and restoring the surface along the whole length of the replaced pipe section.

McGillivray’s most recent project involves replacing a sewermain and 18 residential sewer laterals that had been permeated by water and tree roots in Kitchener.

The new high-density polyethylene being installed is seamless making it watertight and airtight.

The advantages of pipe bursting over open excavation are obvious on this project.

First off, residents were still able to use the road as only one lane was cut off.

Secondly, the project was completed within three weeks (two to three weeks ahead of schedule) and caused little inconvenience to those living on the street.

Finally, the only heavy equipment required is a backhoe and the entire Acacia project was handled by a five-man crew.

“This is the first time in Ontario where the main and the laterals are all high-density polyethylene and tied into a completely seamless unit,” claimed company president Dale McGillivray.

In pipe bursting, an access pit is excavated, using a hydro vac that extends down to the main.

A four-foot-diameter by eight-foot-high can is then placed in the pit, where it is backfilled for added safety and stability.

Utilizing a winch assembly on the backhoe, a boom is lowered into the access pit and a telescopic extension leg is adjusted to the required depth.

At this point, a cone-shaped tool is pulled through the inside of the old pipe that is being replaced.

Simultaneously, the old pipe is broken into fragments and the new polyethylene pipe is pulled into place.

Before all this takes place, however, an underground camera is run through the laterals to provide visuals that aid in the measuring and execution of the process.

McGillivray pointed out pipe-bursting is 90 per cent more green efficient than traditional open excavation methods.

It might be assumed that, due to shorter work times and less labour and machinery required, pipe bursting would be a much cheaper method.

Yet McGillivray said it is not necessarily the case.

“I don’t propose to say this is cheaper (than open excavation),” he said.

“It can be $30 to $40 a metre more expensive.”

He pointed out that, in the Kitchener-Waterloo area, competition among contractors performing open excavation is fierce.

As a result, he said prices are pretty well the same as they were five years ago.

He added that his costs for high-density polyethylene have risen five to seven per cent since May, largely due to its petroleum content.

On the other hand, the open excavation prices don’t usually include the cost of replacing asphalt.

Also containing a considerable amount of oil, asphalt has also been subject to soaring costs.

The City of Kitchener, meanwhile, doesn’t seem to mind that McGillivray’s costs are higher.

It’s the results that count, and the city seems to be delighted with them.

“McGillivray & Sons is doing a great job for us,” said Robert Trussler, the city’s manager of the Acacia Street project, figuring the process takes a quarter the time of other methods.

“We’re going to look at doing five times as many laterals using pipe bursting technology.”

According to Trussler, consideration is being given to using the technology on a major watermain project.

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