Calgary water main work, restrictions to stretch into next week

Calgary has several days' more worth of work to fully restore the city's water system, as officials detailed on Thursday the repairs and testing that will to stretch into next week to recover from the ruptured Bearspaw feeder main.

But the city said it is too soon to say when water restrictions could be lifted.

The replacement pipe has been installed, and crews are now backfilling the hole, said Michael Thompson, the general manager of Infrastructure Services.

Next, crews will begin to repave the broken stretch of 16th Ave. N.W. above the feeder main.

After that, there are four steps to restore the feeder main to service, Thompson said. He says workers will need to move carefully through each stage.

“This is delicate work. Each one of these steps carries risk and it is likely that we could have setbacks along the way,” said Thompson. 

The city had previously set a goal to have repairs completed two weeks from when the pipe burst on Dec. 30. However, it's unclear all this work can by done by next Tuesday, Jan 13.

It will take about 48 hours to fill the replaced pipe with 22 million litres of water from the Bearspaw water treatment plant. There will be an increase in pressure as that happens, which increases the risk of another rupture, Thompson said. 

Once its filled, the water will need to be tested to ensure it is clean and safe. Water samples will be taken and sent for analysis, a process that takes another 24 hours to monitor for any bacteria growth.

If there are any issues with the water quality, the water in the pipe will need to be replaced and retested.

Then the water system's pressure needs to be stabilized, a process that takes another 48 hours, and comes with the highest level of risk, Thompson said. 

Only after all those steps can water conservation measures end. That will happen in stages, Thompson said, with a timeline still to come. 

In the meantime, the city will be taking some mitigation actions to reduce the risk of more flooding if another water main break happens. 

That includes removing two sections of the Bow River flood barrier along Montgomery Blvd. N.W. across from Bow View Manor, said Sue Henry, chief of Calgary Emergency Management Agency.