First it happened in Calgary. Then it happened in Montreal. What is behind the water main break crisis which is drawing worldwide attention to infrastructure and the state of the pipe network in Canada?
Leaks and bursts happen on public water networks every day in every country of the world. They are rarely headline news. What makes these incidents in Canada different is the scale of damage and disruption.
Calgary had to introduce varying levels of water rationing in response to its break. The burst on the 11km long Bearspaw South Feeder Main impacted the supply of 1.2 million people.
Residents are still having to watch their usage three months later as the line is reinforced in an attempt to prevent future failure.
Montreal saw a 10-metre geyser burst through a street and into the air. Roads were turned into rivers. Homes had to be evacuated. Water escaped up to 4km from the leak site, flooding 300 private and 60 municipal buildings.
Whilst Calgary and Montreal clean up, questions are being asked. What other cities and towns in Canada are in danger of a catastrophic water main break?
How ready are Canadian municipal authorities pipe repair plans? Is it possible to identify at-risk water mains and treat them before they burst?
But before answering any of those… what is causing the water main break crisis in Canada?
What links water main break cases in Canada?
There are many similarities between the Calgary and Montreal water main breaks. Both pipes which burst were carrying drinking water, two metres in diameter and buried underground.
Their failures came unexpectedly. Millions of litres of water were rapidly lost because of the dramatic nature in which both mains blew. That in turn caused severe flooding and damage to property.
Most concerning of all is that neither pipe was close to the end of its expected lifespan. Bearspaw was installed in 1975. The line in Montreal in 1985.
Regular readers of PipeRepair.co.uk will know the links between the two incidents are common factors in one of this author’s favourite subjects – prestressed concrete cylinder pipe, better known as PCCP.
North America and its PCCP problem
PCCP has been used in North American water pipe networks since the 1950s. It consists of a concrete core, a thin steel cylinder, high tensile steel wires and a mortar outside coating.
When first introduced, PCCP was subject to stringent safety standards. These though were diluted over time for reasons of cost.
By the 1970s, manufacturers believed they were producing stronger steel wires, enabling them to cut the number used in PCCP. They also thought the new-found strength of their steel meant wires could be cut thinner.
Big mistake. Fewer wires meant more stress on the pipe. When overpressure led to the mortar shell cracking, water from the soil surrounding a buried pipe was able to enter.
These thinner prestressing wires were brittle and more susceptible to corrosion. Once the wires broke, water could seep into other parts of the pipe. It was then just a matter of time before the line suddenly and unexpectedly failed.
Fewer, thinner steel wires drastically cut the average 70-year lifespan of PCCP. Unfortunately, this was discovered the hard way via a serious of catastrophic, premature breaks.
Regulations governing the composition of PCCP were tightened in response. Modern PCCP has an overall failure rate of less than four percent – the lowest of any pipe material.
The damage though has already been done. PCCP was installed everywhere across the United States and Canada through the 1970s and 1980s.
Tens of thousands of miles of pipework in both nations potentially laid with below specification PCCP is now starting to reach the end of its reduced lifespan. A ticking time bomb.
PCCP in Canada
The US has been alert to the threat posed by PCCP for some time. According to the American Concrete Pressure Pipe Association (ACPPA), 90 of the 100 largest water utility companies in the US use prestressed concrete cylinder pipe on their networks.
An assessment by the U.S. Environmental Protection Agency and the American Water Works Association estimated the repair or replacement of all known PCCP would across the country could cost $40 billion.
Canada in contrast seems almost blissfully unaware of how much PCCP its water networks operate on. Even more worrying is it has take two high-profile incidents in major cities for the dangers posed by PCCP to be publicly being discussed and acknowledged.
This despite the National Research Council presenting a paper to Western Canada Water’s annual conference in Regina in September 2008 on the importance of vigilance for water operators.
Riad Al Wardany, an NRC research officer, wrote: “PCCP failure is often catastrophic because it occurs with no leak that can serve as an alarm by being visually detected at the surface, and would allow for rapid intervention to repair the pipe and therefore prevent the failure.”
“PCCP failure is always associated with lack in maintenance operations due to underestimating the condition of the pipe and thus its priority to be repaired.”
Lessons from Calgary and Montreal
When the water main break in Calgary happened and authorities said the cause was unknown, I theorised a PCCP failure. It has since been confirmed that Bearspaw South is constructed of PCCP. Of course it is.
Following the burst, the entire 11km line was inspected. The analysis revealed a number of snapped wires along the length of the pipe. The sections which have been weakened by wire snaps are to be repaired and reinforced to prevent a repeat of the June break.
Whilst the failure of Bearspaw caught Calgary by total surprise, Montreal were monitoring their water main for vulnerabilities.
It was last inspected in 2018 as part of a seven-yearly assessment programme. The pipe should therefore have been inspected again at some point in the next 12 months.
The 2018 inspection suggested the main would last at least another 10 years. Its steel wires were degrading at a rate of one or two per year.
That pace though accelerated over the past six years, leading to the break. Officials have theorised corrosion could have been sped up by more road salt infiltrating the pipe and mixing with the wires than had been estimated.
What can Canada do to prevent future PCCP failures?
There are several steps Canada can take to address the issue of PCCP. Frequent inspections of PCCP will reveal areas where wires have snapped and sections of pipe at risk of failing. These can then have pressure through them reduced or be shut off completely with water diverted.
The biggest obstacle to inspections used to be that PCCP is underground and inaccessible. Technological advances such as noise loggers and robots now allow for in-depth monitoring.
Calgary installed noise loggers along Bearspaw South in response to its failure. They listen and detect the sound of wires snapping, feeding back data which provides a clear idea of where PCCP is in danger of failing.
Where weak spots exist, PCCP can be reinforced. Calgary is building a reinforced steel cage around sections of Bearspaw, pouring in concrete and then backlifting the excavation. This will strengthen the line, prevent future water ingress and contain any future bursts.
Other solutions such as epoxies and composite repair wraps can be applied to reinforce pipework, creating a protective sleeve with pressure resistance of up to 30 bar.
In an ideal world, Canada would replace all PCCP installed in the 1970s and 1980s as the solution to prevent water main break incidents attracting such attention again.
Such an undertaking would obviously be costly. And it would need support at a provincial or even federal level, being far beyond the capabilities or budgets of municipal authorities responsible for water pipe networks.
Leaders have their say
Federation of Canadian Municipalities president Geoff Stewart spoke to CBC in response to the incidents in Calgary and Montreal. He called on all three levels of government to come together and discuss crumbling infrastructure.
“Municipalities own approximately 60 percent of the infrastructure in this country and yet when it comes to taxes, we get less. Eight to 10 cents of every tax dollar that’s collected goes to municipalities.”
Extra funding is also the solution of Calgary mayor Jyoti Gondek, who now knows a thing or two about the damage and problems a water main break can cause in Canada.
Speaking after Montreal suffered its burst, Ms Gondek said: “My thoughts are with the people of Montreal after this morning’s major water main break.”
“Calgarians know all too well what it’s like to have to deal with the sudden failure of water infrastructure.”
“Montreal joins cities like Calgary and Quebec City as clear examples of the need for increased investment from all orders of government in infrastructure that isn’t always in plain view.”
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