Monday’s move is meant “manage risk” between increasing water flow to lessen restrictions and the overall stability of the pipe, said Michael Thompson, the City’s general manager of infrastructure services.
Water restrictions could be eased further by Thursday, as the city plans to further increase flow through the Bearspaw feeder main.
A second pump will be turned on the Bearspaw water treatment facility mid-day on Monday, to begin increasing flow of the feeder main above its current 55 per cent capacity — up to 70 per cent.
Monday’s move is meant to strike a balance or “manage risk” between increasing water flow to lessen restrictions and the overall stability of the pipe, said Thompson.
“If things continue to go well, we would then look to move to stage one outdoor restrictions on Monday July 22,” Thompson said. “If we get to stage one restrictions and the pipe is operating as expected, we will once again increase the flow through the pipe which will allow us to remove all restrictions.”
Stage 1 and 2 restrictions are both possible with flow at 70 per cent and the threshold for no restrictions is 75 per cent according to the City.
Since bringing the pipe back into service it has been monitored closely for further issues, with a particular focus on the area where the initial June 5 rupture occurred to where repair work was completed.
“We are not concerned about the sections that were just repaired, but we are watching other sections of the pipe in this stretch,” he said.
Three snaps were detected last week on wires coiled around segments of the Bearspaw feeder main — wires coil hundreds of times around each 16-foot pipe segment.
“A single snap is not a sign that a new break in the pipe is imminent, but it does give us information about how the pipe is responding to pressure,” said Francois Bouchart, the City’s director of capital priorities on Sunday.
Robotic inspections and acoustic monitoring of the pipe continue, along with a pipe diver — which is expected to yield information by the end of July.
The city is also in the process of installing a fibre optic monitoring system, which expected to be complete early in August.
“This monitoring system will provide more detailed location information about future wire snaps,” Thompson said.
There are risks as the taps get turned and pressure increases inside the pipe, from more bursts or “hotspots” that may require repair.
Thompson said they are ready to take the next step. “We’re ready to do this and we’re going to be listening to the pipe to see how it responds as we turn that additional pump on today.”
“If a new break were to happen, we’re ready to respond,” Thompson said. “We have materials available, contractors on standby and we can rapidly respond to any situation.”
Many ‘expressed frustration’ with communication: Mayor
Uncertainty about why it was taking so long to lift water restrictions and “risks” city officials warned Calgarians about, along with various questions led to frustration by the second week of July according to Mayor Jyoti Gondek.
“The rain disappeared and we were hit with a mighty heatwave, your understanding very quickly shifted to concern,” Gondek said. “Many of you expressed frustration about what you perceived as lack of communication.”
Gondek said she took questions and concerns forward to the team working to restore water flow, reminding them that regular updates are “critical”.
Daily updates were reinstated on Wednesday last week, and Gondek reviewed communication on Friday for the week.
“It was evident that we needed to do more — there had not been enough clear information — or thorough enough information,” she said.
Gondek will be providing communications three days per week, on Mondays, Wednesdays, and Fridays at 8:30 a.m. until further notice — an addition to the daily afternoon updates.
“The goal is to keep you informed on the status of the outdoor water restrictions and any other pertinent developments with the pipe and the water supply,” said Gondek.