A qualitative analysis of early defects present in PVC-U sewers but not observed in rigid pipes

• The types, sizes and frequencies of defects in PVC-U pipes were determined.
• Dents, deflections and buckling were analyzed in detail.
• The applicability of trenchless rehabilitation was assessed for damaged sewers.
• Recommendations were formulated on how to prevent pipe failure incidents.

The objective of the study was to analyze early defects in PVC-U sewer pipes that are not observed in rigid pipes. Field investigations were conducted on newly laid PVC-U sewer pipes in more than a dozen cities in Poland using CCTV equipment and a special device for measuring deflections. The analysis focused on qualitative data concerning defects observed in PVC-U sewers. Three types of defects, i.e. dents, deflections and buckling, were thoroughly analyzed to determine whether trenchless rehabilitation of such pipes is possible and to improve the existing sewer deterioration models. The major conclusions concern the types, sizes and frequencies of defects in PVC-U pipes, their causes, and the possibility of future rehabilitation as well as the improvement in the deterioration models.