Engagés pour l'eau et l'assainissement urbains

Leak Reduction and monitoring

Summary

LYDEC supplies 500,000 customers with water. At the start of the concession, in 1998, the technical output was of the order of 60%. The network comprises 180 km of primary pipes and 3,120 km of secondary and tertiary pipes. Structured in 7 pressure stages, there was no leak detection equipment, although 80 leaks were declared per month on pipes and 3,200 on connections.

Description: 

Description of the leak detection services:

1. Reduction of losses was one of the main tasks required to improve the network's output, which was taken over by a department divided into 4 units:

  • metering unit: meter renewal, surveys, studies, large meters,
  • analysis and result monitoring unit
  • production metering unit,
  • network unit: feeders, sectorial metering, leak detection and repair.

2. Leak detection

4 teams were formed to carry out leak detection, each team being equipped with an acoustic correlator. They were preceded by a team responsible for preliminary acoustic location. The decentralised teams were in charge of preparatory work (cleaning of valves, curb valve boxes, etc.).

On the primary network, 44 leaks were found on 277 km of network between January and October 2000.

On the secondary and tertiary networks, 465 leaks were found on the pipes in the network and 2,400 on the pipes in connections (i.e. 2,865 invisible leaks), plus 125 leaks on valves and 5,100 inside accessible structures (connection boxes, valve chambers, etc. ; - i.e. 5,225 semi-visible leaks), on 4,200 km of pipes that were inspected (some of them gave rise to several campaigns), from January to October 2000.

3. Reoccurrence of leaks

Two pilot zones were chosen to analyse the reoccurrence of leaks. It was shown that the leaks detected were not those that had been repaired previously, but new leaks. These leaks occurred mainly on asbestos cement pipes.

Increases in output from 1998 to 2000

As invoicing was quarterly, the output was calculated by quarter. In rounded values, the output of the network increased from 60% to 70% in two years.