Calgary officials aiming for 'low end' of repair timeline after pipes arrive from San Diego
Water expert says he's aware of roughly 600 'catastrophic' failures with similar pipe across North America
Two key pieces of pipe needed to complete repairs to a water feeder main that ruptured, triggering citywide water restrictions, arrived Tuesday night from San Diego and are being prepped for installation.
City of Calgary officials now say repairs could move quicker than previously expected.
On Wednesday afternoon, the city's general manager of infrastructure services, Michael Thompson, provided an update on the repair timeline.
"As we look at the work completed to date — specifically the excavations and exposing the five sections of pipe — we can now share we are aiming for the low end of our original timeline of three to five weeks, which would be July 5," said Thompson."
"There are still many risks ahead, but every day we work through this complex repair, we become more confident in our timeline."
During the city's Wednesday morning briefing, Mayor Jyoti Gondek thanked the southern California county's water authority, saying a local shop is in the process of sandblasting the pipe and coating it with epoxy to ensure it's ready to go as crews set to work on five "hot spots" along the main that need fixing.
"As we heard yesterday, these hot spots are not leaks, they are sections of the feeder main that needed an immediate repair," Gondek said.
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Wednesday marks two weeks since the Bearspaw south feeder main — which is 11 kilometres long and as wide as two metres in parts — suffered a rupture. Since then, Stage 4 water restrictions on outdoor water use were enacted alongside a citywide fire ban.
Responding to questions about why the infrastructure was brought in from San Diego as opposed to it being sourced from somewhere closer, Gondek said the city did consider local options first, but the size of the pipe posed a significant challenge.
"This is not generally the size of pipe that is used in oil and gas operations," she said.
"Generally, if this type of a part is available, it's because an organization that provides water to residents is the one that has it on hand. And that's why the San Diego County Water Authority has been such an important partner for us."
Gondek says the city chose the option that would make repairs faster.
All of this has put a spotlight on water infrastructure, and one expert says the rupture might have something to do with what the water feeder main is made of.
After travelling 1,600+ miles, two pipes have arrived in Calgary, Canada, to aid in the repair of five sections of pipeline where structural deficiencies were found. Repairs on the original feeder main break have been completed. Our hearts go out to <a href="https://twitter.com/cityofcalgary?ref_src=twsrc%5Etfw">@cityofcalgary</a>. <a href="https://t.co/jSHm6rbQWk">pic.twitter.com/jSHm6rbQWk</a>
—@sdcwaGraham Bell is a research associate professor with the department of Civil and Environmental Engineering at the University of Tennessee. He's also the vice-president of technical services for Structural Technologies, which specializes in the repair of large diameter pipe.
In an interview with CBC Radio's The Current on Tuesday, Bell explained the Bearspaw south feeder main is a prestressed concrete cylinder pipe (PCCP), which is a composite pipe material made primarily out of concrete.
"Most of our pipes were made of a single material, like cast iron, or steel, or maybe slightly reinforced concrete up until about World War II when we needed steel for the war effort," said Bell.
To explain the layers of this PCCP, he says concrete is first cast with a thin steel cylinder inside of it, and that steel cylinder exists as a membrane to keep the water inside the the pipe. Then, it's wrapped with incredibly high-strength steel wires, which Bell says is "about four to five times stronger than the steel can that's on the inside of it."
It's those steel wires that determine the structural capacity of the pipe.
"Those steel wires over time developed some metallurgical problems, and in particular, the pipes manufactured from about 1960 to 1980 have a greater amount of problems than the other pipes outside of that [time period]."
So what happened with those pipes?
Bell says some parameters were changed in the manufacturing process around that time that made the pipes "less robust."
"Now what we're dealing with is these pipes are 40 to 50 years old, they're maturing and they're interacting with the environment, they're deteriorating and they're having problems," he said.
"It's not uncommon for this era of pipe."
PCCP problems?
City officials say the ruptured section of the Bearspaw south feeder main was installed in 1975, though they haven't confirmed the cause of the rupture that occurred on June 5.
"They generally do not leak before they break," added Bell in an interview Wednesday with the Calgary Eyeopener.
He says these high-tension wires are brittle and don't allow for much give.
"They snap, and then that leads to the catastrophic failures that you see and are experiencing."
He says that in 1970s there were some changes to the standards, but it hasn't been a problem since the 1980s once that was corrected
Bell said he's been involved in a number of studies revolving around PCCP. He's aware of roughly 600 examples of catastrophic failures that have occurred since 1968.
"They occur basically wherever prestress was used," he said.
"It just depends on the manufacturing, how much was used. It's not all pipes, not all the wire is bad."
He says the challenge with PCCP is repairing the wires in distress before it becomes a problem, calling the process difficult.
However, Bell believes the City of Calgary has been proactive in monitoring and assessing water main pipes.
"They're doing exactly what you have to do.… Sometimes you can't get to the pipes that are distressed in time," he said.
In response to the ongoing water supply woes, some city services such as street sweeping, pools and recreation centres remain disrupted.
Three violation tickets for misuse of water have been issued to corporations as well, which is up from the two reported by officials on Tuesday afternoon.
As of now, the total number of calls to the city's bylaw service regarding outdoor water restrictions and the fire ban has reached over 7,200.
Crews have been harassed, says city
City officials also say what appears to be wasteful use of water on behalf of the city is actually just crews doing their jobs.
"I want to address reports of our crews being harassed, called names, and filmed and photographed while out doing critical repair work. This behaviour is not OK," Coby Duerr, deputy chief of the Calgary Emergency Management Agency (CEMA), said during Wednesday afternoon's briefing.
"We have heard this happening when crews are performing necessary procedures where they must flush water from pipes."
Duerr said that, for residents, seeing this "might evoke an emotional response."
"While the city has prioritized reducing our water usage, we must continue practices that are necessary to meet regulatory standards for water quality, public health and safety, and to maintain our water distribution system. Flushing occurs for many reasons, such as restoring water service following a main break, repairs, or quality investing."
He added that crews are trying to use as little water necessary to complete this work, and the work is a necessary part of water quality investigations to assure drinking water is clean and safe for consumption.
"If you have a question or concern about something you're seeing, I'd ask you to call 311 rather than approach staff or making negative assumptions."
600 Olympic-sized swimming pools
While repairs continue, officials are still urging Calgarians to continue being water-conscious. Gondek said 450 million litres were used across the city on Tuesday, meaning usage has remained relatively consistent this week.
Over the past two weeks, 600 Olympic-sized swimming pools worth of water have been conserved, according to the mayor.
Gondek thanked Calgarians for "holding the line" and remaining below the safe usage threshold, which is 480 million litres.
River diversion options
On Tuesday, the provincial government issued two temporary diversion licences to the City of Calgary, which now allows for 200,000 cubic metres (200 million litres) for non-potable industrial use via diversion points out of the Bow River.
This means the City of Calgary is now able to track and manage water withdrawals from the river for the duration of those permits.
Ryan Fournier, the press secretary for the provincial ministry of Environment and Protected Areas, said it's an attempt to ease the pressure put on the potable water system because of the critical feeder main break.
During Wednesday afternoon's briefing, Duerr said the city is working closely with the local construction Industry to open two locations along the Bow River to provide non-potable water for construction work.
"This water will be free of charge and will be the responsibility of the end user to ensure that the water is appropriate for its intended application," said Duerr, adding the city would be able to provide more information in the coming days.
"We want to thank the provincial government for expediting the permits needed to help move this program forward quickly."
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