Functioning, monitoring and maintenance of urban horizontal subsurface drainage systems

Functioning, monitoring and maintenance of urban horizontal subsurface drainage systems

Van der Steen, A.J.

Van de Giesen, N.C. (mentor)
Van de Ven, F.H.M. (mentor)
Langeveld, J. (mentor)
Kruithof, A. (mentor)

Civil Engineering and Geosciences

Water Management

Water Resources

2013-10-10

Introduction Dutch municipalities have a legal duty in groundwater management. Adequate and effective management of horizontal subsurface drainage systems is important in fulfilling this duty. The service life time of these systems have to be optimized. Financial resources should be used efficiently. Only since a few years there is a proactive attitude towards management and maintenance of subsurface drainage systems. There is still little experience on how to manage and maintain urban subsurface drainage systems. Current knowledge on system behavior, failure mechanisms and effectiveness of maintenance is mainly based on research to field drainage in agricultural context. More fundamental knowledge on these topics is required in order to assess which maintenance and monitoring efforts are suitable for adequate system management. Approach My research focused on municipally managed, horizontal subsurface drainage systems (mainly installed in the sewer trench). System failure processes, possible locations of system failure, effectiveness of maintenance by jet-flushing and required monitoring and inspection efforts are studied. The knowledge is gained by execution of a detailed case study to two different system types located in the municipality of Utrecht. A predominantly submerged and a predominantly dry system. Past system state inspection and system behavior monitoring data are studied. Time series are analyzed with time series analyses tool Menyanthes. In the context of this research project, an extensive system behavior monitoring campaign is executed in the case systems. Furthermore, several inspection techniques including CCTV camera inspection are applied Results - Knowledge on failure mechanisms. The major failure mechanism observed in the case systems was the formation of ochre. Ochre contamination, a dynamic process, can lead to major problems with high groundwater tables. - Insight in location of failure. Results from this research show that besides problems in the drain-soil interface focused on in literature, internal network clogging can also be a major driver for system failure. - Insight in effectiveness of maintenance by jet-flushing. Jet-flushing appeared to be primary effective in removal of ochre blockages from the internal drain cross-sections. Time-scale of re-clogging is however short. Within several months, the effect can be negated. - A possible approach in system investigation and assessment. Based on the obtained experience in inspecting and monitoring the case systems, an approach in system investigation and assessment is developed. The approach is presented in a decision tree-like scheme. The scheme can be used for the development of a management and maintenance plan for a particular system. Recommendation for future research This research can be considered as initiating research. New questions arose during the research. Permanently submerged (modern) subsurface drainage systems are not yet studied in detail. Some processes are not fully understood yet. Further research is therefore recommended. Literature Leidraad Riolering B2300, 2012. Functioneel ontwerp grondwateroverlast maatregelen (Functional design groundwater nuisance measures) Stichting RIONED, Ede

subsurface drainage systems
horizontal subsurface drainage
groundwater management

http://resolver.tudelft.nl/uuid:36e09b1d-2c13-4e8c-b230-9c62aebde60f

2013-10-10

Student theses

master thesis

(c) 2013 Van der Steen, A.J.