Tamale Water Supply Expansion & Optimisation, GHANA

Key features:

• Turnkey contract
• Hydraulic modelling to optimise design and reduce water losses.
• Pre-contract study undertaken to determine clients requirements
• Training in Water Asset Management and Operation and Maintenance provided by Biwater to client's staff
• All construction using local labour
• Extensive additions to existing distribution networks)
• Reliable water supply achieved

Intake Tower Tamale, the capital of Ghana's Northern Region, is the third largest locality and an important administrative and commercial centre. The water supply for Tamale and the surrounding environs was established in 1972 with the construction of an intake at Nawuni on the White Volta river some 37 km north west of Tamale and a Treatment Plant at Dalun. Since its inception the number of inhabitants has grown from 120,000 to a population of 400,000. The distribution system suffered from acute water shortage and the vast majority of inhabitants of Tamale did not have access to a reliable supply of potable water. Those that were connected were subject to a programme of water restriction. The most serviced zone in Tamale only received water for two and a half days a week. The project provided for the expansion and rehabilitation of the existing water treatment works to increase capacity from 19 to 44 Mld, extensions to the distribution network and a programme to reduce water losses (NRW) through leak detection and pressure management. The improvements included replacing the pumps in the existing water intake structure, 7 km of Ø600 mm raw water pipeline, a new treatment plant, replacement treated water pumps, 22 km of Ø700/800 mm transmission pipeline, a 20,000 m³ reservoir at Kukuo Yapalsi and 96 km of new distribution mains.

Water Asset Management Biwater has used a global information system (GIS) to map the existing distribution network and build a hydraulic model to optimise the design of the network extensions. The Water Asset Management component of the project has reduced the current high levels of non–revenue water by leakage detection, flow and pressure control and improve revenue collection and network management with new computer systems. An intensive training program has been implemented to train the client's staff to maintain the installed systems and to effectively operate and maintain the assets. WAM key Stages: Information gathering on current network Creation of a Network Model and Graphical Information Systems (GIS) Design of the Control System Establishment of District Meter Areas (DMAs) Upgrading water distribution sites Categorising customers and per capita consumption calculations. Customer Education Pre-pay metering trials for stand pipes Meter installation, retrofit and repair Design, installation and commissioning of distribution extensions Leakage Control Pressure Management GWCL Staff Training Current leakage levels in Tamale were relatively low but the introduction for District Meter Areas (DMA) and pressure management had further reduced leakage to 30%. The installation of meters and PRVs controls flow from the transmission main and allows more of the water produced at Dalun WTW to be supplied to Tamale. This has resulted in significant reductions to NRW. A Technical Assistance programme included a 12 month operational supervision period following the commissioning of the plant and a two year co-ordination programme that introduced a mechanism for payment of water consumption in local villages. This ensured that the water treatment facilities are being efficiently managed and operated, water analysis is carried out to ensure quality is maintained, proper records are maintained and that all users pay for the water consumed.

Summary:

Location:	Tamale, Northern Region, Ghana	Scope of Works:	Turnkey design, supply & construct
Client	Ghana Water Company Limited	Work Types:	Civil Mechanical Electrical Water Asset Management
Project Duration:	24 months	Participation:	100 %
Completion Date:	August 2008
Plant Capacity:	44 Mld