September 28, 2007
Halton Region finds water pipe data often full of costly errors
When Halton Region firefighters discovered that an Oakville fire hydrant failed to provide enough pressure to douse a blaze in time, alarms went up over the state of the area’s watermains.
Severe scaling of mains installed between 1960 and 1972 had caused the reduction in water pressure. In 1996, the region implemented the Accelerated Cast Iron Watermain Replacement Program to completely replace 255 km of 150-mm and 200-mm cast iron pipe.
Priorities were set based on fire flows, watermain break data and water quality complaints, with a heavy reliance on the region’s Geographic Information System (GIS) database. The problem: the data wasn’t always correct.
“In 2004, a small section of factory cement-lined pipe was inadvertently lined with a structural liner,” say Mark Bajor, Design Supervisor with the Region of Halton’s Planning and Public Works Department.
“The problem was that the GIS data was grossly inaccurate. When we re-lined the pipe, the second liner folded up inside sections of the main and we had to cut into the pipe to repair it, making Swiss cheese out of the road.
“At that point, we thought we might have overlooked the importance of the actual as-built drawings, some of which showed that the section of pipe and adjacent lengths were already lined.”
However, even the drawings were sometimes difficult to make out. While one set of drawings showed the pipe was lined, another showed it as unlined. Halton considered an inspection program that would have involved talking coupons (pipe samples) in a 100-to 200-day program with an estimated cost of $880,000.
Instead, the region invested in a lateral closed-circuit television (CCTV) camera to fully inspect the mains covered in the replacement program.
“Our CCTV inspections confirmed the presence of over 30 kms of factory cement-lined cast iron watermain,” says Bajor.
The cost of the program, including the purchase of the camera, totaled about $190,000 over 40 days—about $3.50 per metre—with little disruption to the community.
The result; the replacement of more than $22 million worth of older, but serviceable, pipe infrastructure was deferred until it reached the end of its actual service life.
“Premature replacement is an inefficient, messy, disruptive, distracting, unpopular and wasteful business,” adds Bryan Karney, a professor of Civil Engineering at the University of Toronto.
“A lot of our water infrastructure is buried and all we know about it is how old it is. Age is a poor surrogate for what we really need to know about these systems.
“What is needed is a complete set of metrics that can relate funding levels to system performance, taking into account cost, hydraulics, water quality, high days and low days, climate databases, price and variability.”
Bajor and Karney spoke at the fourth annual Future of Canada’s Infrastructure conference in Toronto on Wednesday.
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