On-line survey and diagnose of sewer networks

Optimal maintenance strategies of sewer networks require an important work force as well as strong experience and knowledge. To ensure both a complete survey of the network and real time estimation of the current state of the network is necessary. A project was started in order to develop a new decision support tool for sewer managers. A new sensor measuring water level was first developed combining four major characteristics: a good resistance to corrosive atmosphere, long term autonomy, reduced cost and the ability to transfer data using radio waves. Further, a deployment campaign of these sensors was undertaken involving 100 sensors coupled with the commissioning of a wireless data transfer system. Finally, a decision support tool was developed to treat the data provided by the sensors to reach three aims: detect drifts, estimate the amount of parasite water and inflow during rainy days, and report any alarms. The pilot site chosen for this program is a main sanitary sewer of the city of Toulouse (France). This article presents the complete methodology, including the development of the decision support tool, as well as the difficulties met and the first results obtained in term of rehabilitation strategies of the network.