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The City of Moose Jaw began its work on the Unidirectional Water Main Flushing Program in Zone 2 early last month, and has since wrapped up operations throughout the central portion of the city.
We reached out to Staci Dobrescu, Manager of Public Works and Utilities at the City of Moose Jaw, to find out more about the program.
“The purpose of unidirectional flushing is for us to control water flow through the water mains for the purpose of cleaning the water mains.” Dobrescu explained.
“So, by closing valves and forcing the direction of the flow of water it will scour the inside of the water mains. What it does is it removes all the sediment, mineral deposits and scaling. Anything on the inside of that water pipe will release it through a hydrant.”
Many residents have noticed a large amount of water being released as a part of this process, raising the question of exactly how much water is needed to fully clean out each water main.
“It varies. I'm not going to lie, it's a huge variable. It all depends on the line that we're in the process of cleaning. If it's PVC lines, it's fairly quick. We open the line and within a couple minutes the water is clear. We collect a sample and that's it. We're able to close it and move on to our next run.” said Dobrescu.
She noted that while the exact volume of water needed to complete the process is not known, the timeline for completion is directly related to the material that the water main is made of.
“Unfortunately, we do have a lot of cast iron lines, and they have a lot of built-up deposits inside of them, so those lines can take a lot longer. I can say that the last time we did Zone 2 it took us four days longer than it did this time, so the water clearing up and the process has become a lot quicker.”
“Because the water is clearing a lot faster, it's really important that once you start doing these programs to stay with them, because if you don't, it's like starting back at square one because you have that much more build up inside the water mains.”
The results speak for themselves, said Dobrescu, pointing to examples of cast iron mains that do not receive regular flushing and the constricting effect the build-up of minerals and sediment can have on water flow, colour and taste.
The deposits are disturbed and subsequently removed during the process, creating a discoloured or rusty appearance to the water which is one of the reasons why residents are asked to refrain from using their water while flushing is taking place.
“That's why a lot of people are like, ‘That's coming out of our hydrants?’ when it's discolored and it's because of the iron (from the cast iron mains) that discolor the water and until it's running completely clean – and we determine that with a turbidimeter – so we check their turbidity, make sure that it's reaching the levels it's supposed to be reaching from the hydrant and then we're able to close those down.”
We asked Dobrescu if the city takes samples of the water being flushed, and if any tests are conducted during the process.
“We do a couple different tests. We're not required to but it's for us to see what's going on inside the water mains, what we do is a metal test just to make sure, it's a water quality test, but it tests everything. It tests for magnesium, iron, and lead. It tests for all those minerals and metals to ensure that everything is within regulatory compliance. Then we also do a chlorine test to test what the chlorine residual (levels are like) in the line and then we also test the turbidity, which is the clarity of the water.”
She explained that these tests aren’t conducted at every single point of flushing, with many locations selected at random during the process, although locations that previously showed signs of concern are selected to diagnose any issues with the issues above.
The information gathered by those tests is then processed and depending on the nature of a potential issue that has come to light as a result, a plan for replacement or repair can be made.
“That gives us the opportunity to go out and repair the valves, repair the hydrants, repair the catch basins, drainage issues, we're able to address them.”
Dobrescu went on to explain that the Unidirectional Water Main Flushing Program has been a mainstay in the Public Works department for many years, having proven itself a valuable tool for maintenance and testing since 2008. Noting that the communication about the progress of the work has ramped up in recent years.