Application of Over-the-Line Surveys for Indirect Condition Assessment of Buried Water/Wastewater Pipelines

Abstract Failure of water/wastewater mains incurs heavy repair and replacement costs, in addition to customer inconvenience. Taking preventive measures, such as condition assessment for early determination of corrosion in aging infrastructures, is crucial for agencies from both a safety and an economic standpoint. Direct assessment techniques provide valuable insight into the existing condition of any buried structures, but can be expensive and likely require excavation. Indirect assessment techniques (special over-the-line potential testing using multiple electrodes, and soil corrosivity surveys) for external condition assessment of water/wastewater lines can be conducted to identify the high-risk corrosion areas prior to direct assessment being performed. With this approach, the need for excessive excavation and direct assessment is reduced. This paper is an update to previously published work1 and presents the methodology along with three case studies where such indirect assessment techniques were successfully applied on buried metallic and concrete water/wastewater pipelines, including electrically discontinuous pipelines. The results of the direct assessment agreed with the over-the-line survey findings.