Case Study: Ductile Iron Forcemain Failure

Congratulations to Laura Christensen for delivering an engaging and insightful presentation at the 2025 BCWWA Conference in Victoria!

Laura, alongside Thomas from the City of Vancouver (CoV), explored Ductile Iron Forcemain Failures, shedding light on a critical issue in wastewater infrastructure.

Ductile iron is a common material for sewage forcemains. However, several forcemain failures on ductile iron pipes occurred in a short period of time in Vancouver. Coincidence or not?  Investigations of the breaks showed a similar failure mechanism – internal corrosion on the pipe invert. It is hypothesized that build-up of debris on the pipe invert (exacerbated by low velocities) caused an anoxic environment to form, proliferating sulphate reducing bacteria, that caused the failure of the cement mortar lining and subsequent corrosion of the ductile iron pipe wall.

Similar failures are rare but have been documented in other jurisdictions. Potential causes, investigation technologies, and rehabilitation options are discussed. Given the results of investigations to date, they explore whether design criteria for forcemains should change to minimize this type of failure.

We appreciate Laura’s expertise and contribution to this important conversation!