Inspecting Small Pipes with Big Consequence—Case Studies on Condition Assessment of DIP and BWP at Freeway Crossings

Following a high-consequence failure of a pipeline at a major freeway crossing experienced in 2022 by another city in Arizona, the City of Mesa prioritized inspection of its high-consequence-of-failure water mains, including freeway crossings, with a technology that can provide high enough resolution with actionable results. This paper presents three case studies involving assessments of two 12-in. diameter ductile-iron water mains and one 18-in. diameter concrete cylinder bar-wrapped pipe water main, all crossing a major freeway at three different locations. Discussions include the utilized inspection methods, including electromagnetic Remote Field Testing, CCTV, and external inspections in accessible areas; an overview of the blind verification studies on DIP and BWP that form the basis of electromagnetic inspection tool selection; and how the condition assessment data was used to develop recommendations for future monitoring or repairs and replacements that allowed the safe return of the pipelines to service.