So this is actually happening about 100m from my house, my partner is currently staying with a friend so she can watch their kid because that friend works for the Calgary Emergency Management Agency (CEMA) and is working night shift doing analysis and mapping. I also used to work as a pipeline integrity engineer (but being a dirty hippy I took a catastrophic pay cut to move into sustainability consulting a few years ago). What I'm trying to say is that I am up close and personal with this in a way few people are.
Calgary and Edmonton are less conservative than you think - the cities mostly vote NDP and the UCP gets elected by the farmers and oil field workers. The mayors of both cities are at constant war with the provincial government who just introduced new rules to keep the cities from being able to work with the feds without permission. Alberta is still way more conservative than I like, but so are a lot of provinces.
Now - the break. This is the largest section of the main artery of the municipal water system. It's made from rebar reinforced concrete, is 2m in diameter, and was built in 1975. With steel pipe there's lots of very cool and sophisticated tools you can use for inspection. You can run 'Smart Pigs' down steel pipe which can use ultrasonic sensors to check for internal and external pitting and you can use magnetic flux leakage to inspect for cracks. Concrete is brutal to inspect. The city recently installed acoustic monitoring in this area; these are basically microphones that are trying to listen for cracking or debonding of the concrete from the rebar. This pipe is next to/under the Trans Canada Highway. So you are trying to listen for micro-cracking in the middle of a speed-metal concert and most of the damage that caused this would have accumulated over decades - there'd be little to no warning.
Integrity engineering is about risk and risk is a combination of how likely an outcome is and the consequences of that outcome. With potable water, the consequence is normally pretty low. Water distribution systems normally leak like crazy because the money required to make them perfectly water tight is way better spent on social services. This particular site was always going to be catastrophic if it failed, and the city was doing everything they could to try and manage the risk. Simultaneously, they are trying to manage it without shutting down one of the key road arteries, without spending millions of dollars unnecessarily, and without the risk to people and infrastructure that come with major earthworks in congested areas (look at what's happening with UBCO's construction in Kelowna).
Calgary actually has a lower loss rate in our water distribution system than the majority of major cities.
I would love to call the water department incompetent since I currently have a lake next to my house, haven't had a shower, done laundry, or washed dishes in three days - but having gone to technical presentations by the city's water system integrity team, and having some expertise in the field, I have mad respect for the people who manage our water system.