How can we successfully prioritise investment to boost network efficiency ?
The Grenelle 2 law of 2010 addressed the issue of reducing losses from the drinking water supply network increasing the abstraction tax payable by local authorities that have not prepared a detailed description of their supply networks or an action plan. These action plans are required where efficiency falls below a defined threshold, which varies from 65% in rural areas to 85% in urban areas. This tightening of regulation was to be expected, given that 22% of the 6 billion m³ of drinking water produced annually in France is lost once it enters the 920,000 km of supply pipelines.
The fact remains that pipeline replacement is a considerable financial challenge, especially at a time when local authority budgets are being squeezed. Each linear metre costs between €100 and €200 to replace in rural areas – between €400 and €800 in urban areas – and the average age of these pipelines is somewhere between 30 and 35 years.
The most satisfactory solution is to optimise network performance. New mapping and modelling systems are providing a much more detailed knowledge of distribution network assets. The volumes of water entering the supply system are known in real time thanks to network sectorisation (the installation of control valves and meters at strategic points), which is the most effective solution for detecting water losses. Sector control valves also provide effective regulation of pipeline pressures, which can then be regulated to contain leakage rates directly and immediately.
This more detailed knowledge of networks, when combined with multi-criteria risk assessment (material, diameter, average pressure, failure history and road traffic volumes), is the basis for preparing the optimum renewal plan shared with the local authority.
Thanks largely to these technical solutions, and given the fact that its main presence is in rural areas, which are naturally the most seriously affected by the problem, Saur achieves an average efficiency level of 78%, 86% of its contracts exceed the efficiency threshold set by Grenelle 2, and 100% of the required detailed descriptions have been prepared and submitted