Mayor Gondek update on critical water main break July 15th, 2024

Since we started bringing the pipe back into service, we have been closely monitoring for any signs of further issues. We know there are other areas of structural weakness in the pipe, and our recent monitoring has provided valuable insights into its condition.
As we carefully increased the pressure and flow in the pipe, we have been monitoring its reaction. We measured pressure at various points and used acoustic monitoring devices to listen for snaps in the wires that coil 350 times around each 16-foot long segments. We are particularly focused on the area from the initial rupture to the repair site, although we are not concerned about the newly repaired sections.
The road to lifting restrictions
We understand the eagerness to lift Outdoor Water Restrictions. The key to being able to do this is increasing the flow of water through the feeder main. The pipe is full of water right now, but it is not moving as quickly as it usually does. Currently, the flow is at 55% of its maximum, and at this rate, we need Stage 3 Outdoor Water Restrictions in place to ensure our water demand doesn’t exceed supply.
By using pumps to increase the speed of water flow, we can increase the amount of water we can supply to Calgarians each day. Our plan involves gradually increasing the flow while monitoring the pipe stability. Once we achieve a 70% flow rate, we will be able to move into Stage 2 Outdoor Water Restrictions.
Starting today, we will turn on an additional pump at the Bearspaw Water Treatment Plant, which will increase the flow through the pipe. If all goes well, we expect to move to Stage 2 Outdoor Water Restrictions on Thursday, July 18 and potentially to Stage 1 Outdoor Water Restrictions on Monday, July 22.
If we get to Stage 1 Outdoor Water Restrictions and the pipe is operating as expected, we will activate another pump and further increase the flow through the pipe allowing us to remove all restrictions.
Bearspaw Water Main
Preparing for setbacks
We are managing the risk between increasing water flow and the pipe’s overall stability. As we increase the water flow it creates pressure in the pipe, which could result in additional wire snaps. This may stop our progress and prolong some level of Outdoor Water Restrictions.
There is also a risk of another pipe failure as we increase the flow, which may be alarming to hear given recent events. However, after careful analysis, we believe the risk is low enough to proceed and if a new break occurs, we are ready to respond rapidly with materials and crews on standby.
What to expect at each stage of water restrictions
Moving from Stage 3 to Stage 2 Outdoor Water Restrictions will allow activities such as using a sprinkler for up to 1 hour per week and using hoses with spray nozzles. Stage 1 Outdoor Water Restrictions permit sprinkler use for up to 2 hours a week, among other things.
Water restrictions chart
Next steps
We recently conducted a thorough inspection using a pipe diver device. This device was inserted into the pipe to inspect the entire concrete pipe from the Bearspaw Water Treatment Plant to downtown. We expect the results by the end of July.
Pipe Diver
We are also in the process of installing a fibre optic monitoring system that will be completed in early August and will provide us more detailed location information of future wire snaps.
Looking forward, we are developing a medium-to-long-term rehabilitation plan for the pipe and will incorporate the information we receive from the results of our pipe diver inspection and fibre optic monitoring system. Some of the plans we are considering include:
Placing a liner inside the existing pipe,
Replacing additional segments of pipe which have lower structural capacity due to wire snaps,
Exterior reinforcing of the pipe
And, installing a new pipe.
We are committed to keeping you updated on our progress and any potential setbacks as we work to ease restrictions over the next two weeks and restore full water service to Calgarians.