The scope of this project was the development of a coherent framework of principles and practices, established in international practice, for achieving the overall goal set by the Client and defined as reducing AAWSA’s overall Non-Revenue Water (NRW) from a current level of about 36% to 40% to a level of 20% by the year 2020. Addis Ababa and its surrounding areas has currently population estimated at about 3.5 million inhabitants. The total pressurized water network length was 3,700 Km.
All aspects of NRW management were addressed in the project. In order to achieve the overall project goal a Strategic Plan was implemented including the following tasks:
- Review of Existing Situation.
- Organizational Structure Assessment.
- Bulk Flow Meter Installation and Replacement Proposals
- Sampling and Testing of Existing Customer Meters
- Development of Specifications for the Procurement of New Customer Meters and Test Benches.
- Development of strategic (skeletal) and all-mains hydraulic models.
- Development of a GIS Management System for the Addis Ababa water supply network
- Implementation of ten pilot District Metered Areas and active leakage control activities using acoustic techniques.
- Initial and End Case Water Audits and evaluation of Performance Indicators.
- Training and Institutional Capacity Building.
Emphasis was placed on improving network monitoring and water metering practices. A detailed proposal for the installation of bulk flow meters at selected locations was developed. Technical specifications for the procurement of state-of-the-art customer meters, DMA inlet meters and customer meter test benches were developed. A program for the random sampling of testing of customer meters was implemented and a total 683 meters from two Branch Office Areas were replaced and tested. A sample of 1,214 unused customer meters was also tested. Statistical processing of the test results took place and the conclusions were used to estimate apparent (commercial) water losses in the network. A Metering Database was established to store customer meter information and test results.
Ten pilot District Metered Areas each including approximately 800-1200 customers were proposed and their creation was overseen. Zero pressure tests were performed to test DMA watertightness and the Active Leakage Control was carried out at all ten DMAs using listening sticks, leak noise correlators and ground microphones. On-the –job training was provided by the Consultant to AAWSA staff in the course of the Active Leakage Control. DMA Minimum Night Flow analysis was carried out using available field data. A program of individual consumer demand monitoring of sampled customers was implemented for use in the Minimum Night Flow Analysis.
Network hydraulic modeling was used to study the effective distribution of the output of new water supply sources in order to provide continuous supplies to all consumers, eliminate supply interruptions and rationalize the flow and pressure regime. In this context, present and future water demand estimates were obtained and the distribution of water demand within the supply area was studied. Improved hydraulic operation and achieving continuous supply to customers is considered as a key issue in achieving reduced leakage losses.