Statistical analysis of lateral house connection failure mechanisms

Abstract

The performance of lateral house connections can have a substantial impact on the overall level of service provided by sewer systems. However, knowledge on the failure probability of these components remains scarce. This paper analyses field data to determine failure rates. A distinction is made between different mechanisms that contribute to the overall failure probability of lateral house connections. Root causes that promote the occurrence of these failure mechanisms are derived from a literature review. Results of a trend analysis shows a time constant failure rate, which exceeds blockage rates reported for main sewers. Fat, oil, and grease deposits are the dominant failure mechanism for both a specific case study in Rotterdam and the Netherlands. Literature suggests misuse and the structural condition as main root causes for this failure mechanism. The sheer number of failures associated with lateral house connections suggests that these components should be taken into account in sewer asset management.

Keywords:

• Lateral house connections
• Serviceability
• Sewer blockages
• System assessment

Acknowledgements

The authors would like to extend their gratitude to Riool Reinigings Service (RRS) for providing failure data. The research is performed within the Dutch ‘Kennisprogramma Urban Drainage’ (Knowledge Programme Urban Drainage). The involved parties are: ARCADIS, Deltares, Gemeente Almere, Gemeente Breda, Gemeente ‘s-Gravenhage, Gemeentewerken Rotterdam, Gemeente Utrecht, GMB Rioleringstechniek, Grontmij, KWR Watercycle Research Institute, Platform Water Vallei en Eem, Royal HaskoningDHV, Stichting RIONED, STOWA, Tauw, vandervalk+degroot, Waterboard De Dommel, Waternet and Witteveen+Bos.