Upcoming work on the Bearspaw water feeder main will last until the end of September but will just be the start of a plan to rehabilitate the city’s largest water supply line.

Calgary Mayor Jyoti Gondek provided an overview Friday morning of repairs on 16 new spots discovered after reviewing data from the PipeDiver tool that was inserted along 10 kilometres of the troubled pipeline.

She said that beginning August 26, they will begin taking the feeder main offline, requiring citizens to go back to Stage 4 outdoor water restrictions. This will help ensure that the Glenmore water treatment plant can keep up with the water demand both in Calgary and the surrounding areas.

The Bearspaw main will be shut down on August 28 when excavation work will begin to reach the pipe along 33 Avenue NW and 16 Avenue NW.

“Once the pipe is exposed, there will be rebar and concrete that is added to the places that need additional strength, and that encasement work will provide strengthening of the pipe,” Mayor Gondek said.

Come spring, the mayor said they were considering one of two options: A liner put into the pipe to add structural integrity. They may also dig alongside the main and put in a new one.

“There is current planning for mid- and long-term around the Bearspaw feeder main and there is work that is already underway with a private engineering firm to design the medium- and long-term plan to reinforce or replace the line,” she said.

Long term, there’s a design for a north feeder main and a south feeder main. The mayor said that would mean there are additional pipes coming out of the Bearspaw water treatment plant.

“This is the situation that we find ourselves in now, with only that one pipe coming out of there, we have to shut it down and limit water flow out of Bearspaw treatment facility,” Mayor Gondek said.

“With this additional North and South feeder main, we will have more ways of getting water out of the Bearspaw water treatment facility.”

They will also be expanding the capacity of the Bearspaw plant to accommodate future population growth.

Examining potential problems citywide with precast concrete pipes

Infrastructure Services GM Michael Thompson said he has been asked how much of the precast concrete pipes are in Calgary's more than 5,000-kilometre water pipeline system. This particular section is 10.4 kilometres, he said.

He said that the vast majority is made up of polymer pipe, with three per cent being precast concrete or 187 kilometres.

Thompson said they're still finalizing their review of the PipeDiver analysis.

"We are currently estimating 16 sections of pipe which need to be repaired, but as we are still finalizing the analysis, this number may change," he said.

The repair plan involves excavating the sites, installing reinforcing steel around the areas they've identified as hotspots, and then putting concrete around them.

Repair impacts to homes and businesses

The mayor said she hopes the work has no impact on businesses across Calgary. Still, she said she wants Calgarians and business owners to be very mindful of the water they’re using.

“You did an excellent job in June figuring out ways to limit the amount of water you were using, and I think we can go back to relying on some of those methods as we are doing this maintenance and repair work,” she said.

Does that mean indoor water conservation, too? Yes, the mayor said.

“If you could go back to the ways that you reduce your consumption indoors, things like taking shorter showers, when you're running the shower, to capture that water in a bucket as it's warming up, and using that to water your plants or your garden,” she said.

“Things like less toilet flushes, things like only a full load of laundry or dishes. I am asking you to do all of those things. I will be doing them along with you.”

Mayor Gondek said the City of Calgary is working with business and residents that will be impacted in the construction areas along 16 Avenue and 33 Avenue NW.

“This is a very iterative and interactive process where people who are impacted are directly involved in the planning of what we're going to be doing,” she said.

GM Thompson said that part of letting people know was a door-knocking campaign that started on Thursday, to homes and businesses that will be affected along 33 Avenue NW, 16 Avenue and Parkdale Boulevard.

"We have committed to residents and businesses in the impacted areas that when we know more details about the specific repair locations required road closures or any further impacts, we will share this with them and with you," he said.

Thompson also said that even though they may not be cutting into the pipe, the water can't remain on to service the city.

"It is moving significant volumes of water. Even with the current reduced flow through the pipe, it still transports approximately 200 million liters of water a day," he said.

"If the pipe is exposed while operating, there's a high risk it could break, and that could pose a serious safety risk for our crews doing the repairs, similar to how we needed to backfill the previous repair areas before repressurizing. We need to depressurize the pipe to start any repair work, regardless of the repair type."

The mayor’s hoping that by giving advanced notice of the planned outage, both citizens and businesses have time to prepare and they could have conversations with those who may be impacted.

She hopes Calgarians continue to work together as the repairs are completed, and offered reassurance they are handling these 16 repairs to preserve the city’s water system.

“We could have said that we don't want to do it right now. We will do it next year. We didn't think that was prudent,” she said.

“So, thank you for understanding that we are going to get this repair work done to make sure you have a strong working network for your water.”