September 9, 2010

FOCUS | Sewer and Watermain

Copper replaces polybutylene as way to stop water leakage

DAN O’REILLY

correspondent

In what might be considered ground breaking work, both literally and figuratively, all of Durham Region’s approximately 25,000 aging and deteriorating polybutylene water service connections will be replaced with copper ones over the next several years.

“It’s a huge project, probably at a cost of $100 million,” says Uldis Siksna, the region’s manager of maintenance operations.

But the mammoth undertaking became a lot easier last fall when the region decided to adapt existing technology to a new use. Similar to its CCTV camera examination of sewer laterals and water reservoirs, it is using two sets of Pearpoint P332 model cameras with signal transmitters and receivers, plus a monitor and associated equipment to locate the connections.

DAN O’REILLY

Water service connections are located by feeding a camera head through a hydrant with water pressure kept at a low and constant level.

A three-person crew operating from a van locates the connections in a process that involves carefully feeding a camera head through a fire hydrant whose water pressure is kept at a low but constant pressure. The video footage is then displayed on a small screen.

“The camera is pushed slowly to avoid stirring up too much sediment or debris and the direction it enters can be controlled by twisting the cable until it points the right way. The operator inserting the camera is guided by another operator who is viewing the progress on the monitor,” Siksna explains.

After the crew has identified the connections, survey stakes are installed and the sites are plotted on to a geographic information system.

Drawings are produced to assist the private contractors who will be replacing them.

“We usually group them (the connections) in bunches of 75 to 100 in the same area and then issue contracts,” says Siksna.

Last fall, the region applied for $25 million in federal infrastructure stimulus funds and, of that figure, $10 million was earmarked for the purchase of the cameras and some of the contract field work, he says.

“We wanted to take advantage of the fund and get as much work out there before the (March 2011) deadline.”

Like many municipalities across North America, Ontario’s Durham Region is grappling with water-loss problems stemming from the installation of the polybutylene water service connections in new home subdivisions from the late 1970s to the early 1980s. The connections extend from municipal watermains to shut-off valves at the property lines in front of houses.

Developers pushed for approval of the new product because it was easier to work with and less expensive than copper.

But they’re made from a plastic resin that cracks with age, with the result they deteriorate and leak. Durham is losing about $250,000 in water leakage annually, Siksna points out.

“It was about five years ago that the problem became particularly noticeable.”

In other jurisdictions that problem is even more serious, says Siksna, who has heard of situations where mould growth caused by leaking water has forced the demolition of some houses.

To replace the pipes, the connections must be located at both ends. As the material is plastic, it’s not possible to do that from the surface. Before the cameras were purchased, the connections had to be found through “trial and error” vacuum excavation.

“It was not uncommon to spend most of the day searching to find them,” says Siksna. He estimates the cost just to find the main stop was $800.

“We knew we had to speed up the process,” he says in emphasizing the pivotal role of the camera system.

“Already, the equipment has increased productivity, reduced main stop locating costs and limited the intrusion on residential streets.”

As the federal stimulus funding covers only a portion of the project’s overall costs, however, the pace and duration of the replacement program is contingent on yearly regional budgets, he says.

Print | Email | Comment