MEasurement sites conception method for sewer NeTwORks. – MENTOR

Besides the general management and valorization work packages (WP), the project is structured in six work packages defined by their aims and tools :
• WP 2 is based on surveys by network authorities in order to analyse the way the measurement network is integrated in their activities,
• WP 3 uses numerical modelling to calibrate water height – flowrate relations,
• WP 4 and part of WP 6 investigate experimentally and numerically how flowmeters are able to tackle the spatial distribution of velocities and their impact on uncertainties,
• WP 5 and part of WP 6 investigate experimentally and numerically how to characterize the reliability and the spatial distribution of suspended solids and their impact on uncertainties,
• WP 7 investigate the potentialities of Monte Carlo simulations applied to temporal chronicles in order to define the representativeness of the measured pollutant concentrations and to quantify uncertainties.

• Importance of the interactions between site and sensor and necessity of an hydraulic analysis in any instrumentation project
• Numerical calibration concept for water height-flowrates relations and application to various cases
• Creation of the 3D EAU start-up to implement those knowledge in engineering domain,
• Necessity to punctually check the spatial representativity of the results obtained by continuous monitoring, eventually using numerical extrapolations
• Method to evaluate the uncertainties of temporal representativity by Monte Carlo simulations on reference chronicles

• Promote the numerical calibration concept of water height-flowrates relations and investigate how it can be applied to velocity measurements,
• Widen the investigation of the spatial heterogeneity of pollutants to dissolved pollutants and to mixing length downstream of a junction,
• Spread the notion of uncertainty into the culture of all the actors and propose training programs, in particular on methods adapted to continuous measurements
• Investigate how to have a better appropriation of the supervision systems to make them become a real tool that can improve the management of sewer systems

The obtained data have been distributed among the project partners and the results have been published in academic journals. The main results have been presented to the practitionners during two technical training sessions and the proceedings can be freely downloaded from the project internet site.

The project coordinator is now a member of the national standard commission X10C « hydrometry. She takes part to the working party in charge of the revision of the “ Charte Qualité de l'Hydrométrie ».

With more than 70 % of the national population living in urban areas, the anthropisation of the urban water cycle is obvious and requires a holistic approach. Reaching the WFD (European Water Framework Directive) objective prescribing a good ecological status of water bodies will not be possible without an adequate operation of sewer systems. However, their functionning is rather unknown even if they represent a huge asset. According to the data provided by IFEN (French Environment Institute), 24.8 millions of flats and houses in France in 2004 were connected to sewer systems whose total length was above 280000 km. These figures reveal the economical signification of the operation and the management of sewer systems. From an environmental point of view, it is known since many years that pollutant loads discharged by urban water systems during storm weather significantly contribute to the degradation of the quality of water bodies. It is thus necessary to estimate these pollutant loads at both event and annual scales in order to better evaluate the functionning and to improve the operation of urban sewer systems, and to contribute to a better chemical and ecological quality of water bodies. The concepts of permanent diagnosis and self-monitoring of sewer systems have been introduced more than 15 years ago in order to improve the operation of sewer infrastructures, the planning of works and the regulatory and financial issues (e.g. to allocate investment costs within inter-municipal structures). Consequently, in situ measurements shall be carried out in order to evaluate, and then to improve, the real functionning of sewer systems. Measurement networks are a key instrument for monitoring and operation, with a increased interest in case of continuous on line measurements. However, an efficient operation of sewer systems also depends on the ability of both sewer systems and measurement networks to be resources for their operating organisations : how do they contribute to create economic and usage value ?

The main objective of the MENTOR project consists to propose a methodology for the design and the audit of discharge and particulate pollutant loads measurement sites in sewer systems. MENTOR will also provide operational tools for data processing and use. The steps of the methodology are the following ones:
1. defining the characteristic parameters of the flow,
2. modelling the hydrodynamics of an existing or planned measurement site,
3. simulating various sensors configurations for this site,
4. qualifying or not the site,
5. defining appropriate methods for interpretation of measured data,
6. establishing organisational recommendations ensuring the implementation of best metrological practices.