Calgary Feedermain Inspection Program

The city of Calgary carries out an annual asset management program of concrete water feedermain inspection to ensure the safety and reliability of its water network. The program began in 2004, when a 48 in wire wrapped C-301-L feedermain burst apart in Calgary's northeast, flooding the roadway, and releasing over 20 ML of water. Investigations of the failure pointed towards sulphate attack; the sulphate resistant concrete coating was not resistant enough to handle the local conditions of 5,000 PPM. Over time the coating had degraded, letting water seep in and corrode the steel wires that provide most of the strength of this material. The initial inspection program focused on feedermains that were in the same soil type and vintage as the original break. In 2011 our focus expanded, as a 24 in bar wrapped C303 main burst, damaging a nearby garage and flooding alleyways.