March 26, 2010

FEATURE | Sewer and Watermain

Georgina, Ontario anticipates growth with sewer, road expansion

$47 million project is one of the biggest yet

DAN O’REILLY

correspondent

It will be a beehive of construction activity in the Keswick area later this year when one of the largest infrastructure projects ever in the Town of Georgina gets underway.

New planned growth is the driving force behind a $47-million watermain/forcemain/road-widening project. Construction will start in the spring almost immediately after the tender award has been announced by the Region of York, says regional project manager Ben Pressman.

“It just makes sense to do everything at once,” says Pressman in explaining the decision to combine all three segments into one contract.

The project will take well into 2012 to complete and will be overseen by one contractor rather than divided into several phases, says Pressman.

Open-cut construction will be used to install a seven-kilometre 750-mm concrete pressure water main from the Georgina water treatment plant south to the Keswick Reservoir, just off Ravenshoe Road. A small 1.4 km portion of the watermain was installed last year.

The project will also include the installation of twin 6.4-kilometre-long, 400-mm forcemains which will link the Joe Dales pumping station to the Keswick Water Pollution Control plant. While there will be some installation along Ravenshoe Road and some side streets, the primary route of the water and forcemains will be adjacent Woodbine Avenue.

As the pipes are being installed, the contractor will also be doing the preparation work for a major expansion of Woodbine Avenue from three to five lanes from just north of Ravenshoe Road to Morton Avenue. The road work will also include widening the Maskinonge River Bridge from three to five lanes, with the addition of two bike lanes and a sidewalk, says Pressman.

While the terrain is fairly flat with few environmental constraints, determining the most appropriate method of installing the pipes across the river was one of the major design challenges.

Geotechncial and hydro geological investigations revealed the soils near the river were extremely poor consisting of layered silt and silty clay, says Mark Tarras, partner, the Municipal Infrastructure Group Ltd., the project’s consulting engineers.

“We considered crossing the river either via a tunnel or directional drilling. However that was ruled out once we considered the potential of flowing conditions in the tunnel option and the potential for frac-out with directional drilling,” he says.

The solution was to suspend the pipes from the underside of the bridge expansion between the girders. Each pipe will be insulated, heat traced monitored for temperature and protected with a steel casing. Expansion joints will allow the pipes to expand and deflect, says Tarras.

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