The Network Improvement Project
Over recent years the Network Improvement Project has been critical in controlling leakage across London and the Thames Valley. Sustained leakage savings from the project in excess of 145Mld (million litres per day) have been achieved. Lower and more stable network pressures delivered by the project continue to reduce mains failures across the network: failure is deferred by improved operating conditions in the system (a calm network).
This project was conceived following the Ofwat report entitled Leakage and the Efficient Use of Water[1]; in which Leakage at Thames Water was specifically referenced. Steps were agreed between the water company and the regulator to the recover customer’s security of supply by:
- returning leakage to economic levels,
- establishing a robust Water Balance, and
- producing a plan to recover target supply-demand headroom.
The Network Improvement Project is in fact a programme of related projects that was conceived in response to these “Agreed Steps”.
Project benefits began to accrue and company leakage stopped increasing within one year of project initiation. Thereafter progressive reductions were achieved that enabled successive Thames Water leakage targets to be achieved for 11 consecutive years.
More details of this case study are contained within the publication UK Water Projects Online[2] .
[1] Leakage and the Efficient Use of Water
Nature of the work
The network improvement programme comprises two distinct types of project: Pressure Management and Zonal Reconfiguration. Both deliver reduced levels of leakage through lower and more stable pressures across the pipe network.
Pressure Management is well established across the UK water industry. Pressure managed areas are formed that are normally similar in size to District Metered Areas (2000-5000 properties) using pressure boundaries that are often coterminous with DMA or Zone boundaries. The pressure within this area is then controlled using one or more pressure reducing valves.
Zonal Reconfiguration is a complete rethink of the structure of the pressure zone aided by hydraulic modelling. Boundary valves are modified or verified and anomalies between model and field behaviour are resolved. Transmission routes are modified to improve interactions between transmission and distribution functions within the network. Control valves are also used, but these tend to be much larger than those used in traditional pressure management and fundamentally change the way the network operates.
Programme Management Challenges
Network improvements of this nature require modifications to a network that is in constant service. Very close and constructive relations with operations staff must be maintained as a priority. Service levels in terms of pressure, security of supply and water quality are not negotiable. Intense leakage detect-and-repair activities take place concurrently and the Project Sponsor looks for benefits to be measured on a weekly basis alongside leakage savings from day to day operations.
A cultural shift within Thames Water early in programme ensured that substantial project benefits were, and continue to be, sustained. Until initiation of this project, “detect and repair only” was considered the most appropriate response to leakage. We shifted hearts and minds in this respect and in due course asset investment was adopted as a primary means to cut leakage for the short, medium and long term. Initially our proposals were met with scepticism but when measured and proven benefits started to flow, operational managers appreciated that our project could help them meet their own objectives. In time, effective delivery engendered the full confidence of managers and front line staff; enabling efficient and sustained project delivery going forward.
Prior to the project, owners of tall buildings in London had become used to mains pressures in-excess of service levels set by statute or regulation. To have the desired effect on mains leakage it is necessary to lower historic pressures so they are closer to the required service levels. This creates a problem for many property owners who had allowed their building pumping systems to fall in to disrepair. In some cases, building pumps are not present in their buildings at all. In the early stages of the project a group of influential property owners, including public sector service providers, asserted that the water company must bear the cost of pressurising the water system throughout their tall buildings, whatever the pressure in the mains. This is clearly contrary to the statutory and regulatory position which measures service levels at street level. Nevertheless, success of the project was put at risk when the Association of London Government (ALG) supported the property owner’s position and proceeded to brief the media accordingly. Extended negotiations with property owners and several high-level presentations to the ALG were needed before a compromise solution was reached which allowed the project to continue to deliver benefits for the broader population of London.
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