Towards a better understanding of failures occurring in SUDS

Abstract

In recent decades, sustainable urban drainage systems (SUDS) are more often seen as an addition to, or a replacement of, traditional piped urban drainage (UD) systems. Unfortunately, failures in SUDS still occur regularly, resulting in malfunctioning systems, water nuisance and high costs. To learn from past experiences and to ensure that SUDS in the future can function as a credible alternative to piped UD systems, these failures should be identified, and the underlying reasons more thoroughly understood. Therefore, the research objective of this study was to create a better understanding of technical failures in SUDS and identify their root causes. In creating this understanding, cases of technical failures in SUDS were collected and interviews were conducted to reveal information about their root causes. The observations showed that the implementation of SUDS in the urban environment present new interfaces between systems, disciplines and responsibilities. These interfaces between SUDS and subsystems were shown to be prominent failure locations. The interviews revealed that designers, constructors and operators often lack knowledge about these interactions and their impact on the performance of SUDS. Combining the results of technical failures and the underlying root causes showed that throughout the whole development process of SUDS (i.e. design phase, construction phase and user/maintenance phase) technical failures arise. In minimizing these technical failures, every project phase should focus on certain root causes behind technical failures. The classification of the 13 identified root causes revealed that root causes stem from uncertainties in technical, social and institutional systems and are located both within (internal) and between systems (interface). Previous research focused mainly on barriers in the socio-institutional system, this research however showed that we should just as much focus on the technical system. Moreover, previous research primary focused on the performance of SUDS in their context, this study revealed that interfaces between SUDS and other urban subsystems are critical and deserve extra attention in future projects. Further research is required to systematically keep record of the problems and failures occurring in SUDS.