High-Resolution Inspection of AWWA C303 Bar-Wrapped Pipe with Detailed Field Verification

Following a high-consequence failure of a pipeline at a major freeway crossing experienced by another city in Arizona in 2022, the city of Mesa prioritized inspection of its high-consequence-of-failure AWWA C303 Bar-Wrapped Steel-Cylinder type concrete pressure pipelines (BWP) with a technology that can provide high enough resolution with actionable results. Based on the recent advances and increased track record of electromagnetic inspection, proprietary tools offered by PICA were incorporated into a visual and sounding inspection project to pilot the electromagnetic tools in about 1.7 mi of 30 in. diameter and 1 mi of 36 in. diameter BWP. The project included not only inspection of buried pipelines with unknown condition but also blind inspection of aboveground test pipes with hidden defects in the steel cylinder and reinforcing bars as well as subsequent field verification of defects that the tools identified in the buried pipelines. Field verifications included internal person-entry inspections and local external inspections in selected excavated areas as needed. This paper presents the findings from these inspections with particular emphasis on the field verification of results and discusses the effectiveness of the utilized condition assessment approach in assisting the city in its asset management program.