A fresh look on the sewer system
Flooded, stinking streets and no toilet facilities anywhere. That is what a world without sewers would look like. Inspection and maintenance are vital, but how do you organise this as efficiently as possible?
With some 150,000 kilometres of sewer pipes running beneath Dutch soil, the sewer system is one of the country’s most important infrastructures. Researchers from Delft and Leiden are working together in the ‘SewerSense’ project to develop a new inspection method.
‘Sewer management starts with good inspection’, explains Lisa Scholten, Assistant Professor of Urban Water Infrastructure (CEG). ‘You'll need the right information about the condition of the sewer, and you need to be able to analyse those data correctly. The aim is to create long-term maintenance policy that pre-empts potential problems. This is not possible with the current inspection methods and decision-making processes’.
Why not? A camera takes pictures inside the sewer, after which someone assesses these images and determines the current condition of the pipes. Is something acutely wrong, or can repairs be put off for a few more years? It is sometimes difficult to tell from the images. More – and more reliable – information will make it possible to plan targeted sewer maintenance.
The required information is collected by an inspection vehicle that was developed in collaboration with Leiden University. The vehicle is fitted with various sensors and cameras, allowing it to actually ‘see’ in the sewer, as it can perceive depth and collect data both above and below water. ‘By using a self-learning algorithm, we can automatically identify potential problems’.
But how do you make decisions regarding sewer maintenance based on this information? Scholten and her colleagues organised workshops with representatives from the field to find out. Scholten: ‘We expected to quickly discover how this process works, but that was not the case. People agreed on the strategic maintenance objectives, but not on how you translate these into practice and on which maintenance activities are required to achieve these goals’.
Feeding the existing data, the data from the inspection vehicle and those from the Leiden algorithms into a model that enables researchers to recreate the situation digitally. It is then possible to compare various inspection and maintenance strategies and make assumptions about how long a sewer pipe will remain safe.
Scholten: ‘If would be great if this new technology could help us to develop a fresh perspective on sewer policy and management’. But first, laboratory experiments will have to be performed. ‘It is a four-year project. That is a negligible period of time compared to the lifespan of a sewer system; some pipes last for a century! The new method will offer us even greater insight in this respect’.