Good asset management is a necessity for long-term economic leakage management, and the objective is to tackle leaks in the most cost-effective way.
Valve and air valve operation & maintenance
The correct operation of air valves is an essential part in reducing pipe bursts. To ensure that water company’s air valves are operating efficiently, they should be serviced at least once per year. This servicing will involve dismantling the air valve, cleaning all of the parts and replacing those that are deemed too worn or are broken.
PRV operation & maintenance
System pressure has a significant affect on leakage and the frequency of pipe bursts. Controlling pressure will have an immediate and long term impact on NRW levels. Each DMA will be assessed for the cost benefit effectiveness of installed a PRV and those that have a cost benefit payback deemed acceptable will undergo PRV installation works. These PRVs can be installed with the latest controllers which ensure the pressures are optimized to the specific location either through a ‘time-operated controllers’ or ‘flow modulation’. To ensure correct operation of water company’s PRVs it is important that they are serviced every six months. This servicing will involve dismantling and cleaning of the main valve body, any pilot valves and the strainer.
Altitude valve operation & maintenance
To ensure correct operation of water company’s altitude valves it is important that they are serviced every six months. This servicing will involve dismantling and cleaning of the main valve body, any pilot valves and the strainer. During this operation any faults to the altitude valve, including a broken diaphragm, damaged pilot, etc, should be reported immediately or if possible rectified on site. Those altitude valves reported as faulty should be repaired or replaced immediately.
Data logger and meter maintenance
Meter servicing is essential, especially in areas of poor water quality. The accuracy of mechanical meters changes over time as the mechanical bearings wear down, causing friction to increase and thus the meters to under-register. These changes will occur over a number of years, depending on the quality of manufacture. The water utility should regularly test a sample of its customer meters, including a range of meter brands and ages, using a calibrated meter test bench. This testing will determine the optimum age at which customer meters should be replaced.
Pipe replacement programmes
Good asset management is a necessity for long-term economic leakage management, and the objective is to tackle leaks in the most cost-effective way. This requires priority setting and decisions on whether to repair, replace, rehabilitate, or leave the assets as they are, while simultaneously implementing pressure management and improving the operation and maintenance programme.
Water companies should identify a list of pipelines to be replaced. The NRW teams shall prioritize this list for pipeline replacement. In addition, pipelines within established NRW zones may be identified for replacement where the frequency of failure is high. In such cases, pipe replacement will be carried out and the volume saved before and after pipe replacement programme will be measured and accounted for as savings in physical loss.
The selection criteria pipe replacement should be based on the following
- The frequency of leaks and burst along a pipeline
- Failure profile
- General pipe condition
- Existing pipe location