46362-001: Angat Water Transmission Improvement Project
Project Data Sheet (PDS): Details
The Project will secure raw water supply to the 13 million inhabitants of Metropolitan Waterworks and Sewerage System (MWSS) service area, through the rehabilitation of the Angat transmission line. It is estimated that currently each day about 800,000 m3 or 20% of the total potential capacity of raw water is lost , due to leakage of the aqueducts . The main components of the Angat transmission line are as old as 50 years, in poor condition, and not in compliance with structural and seismic requirements, risking the partial interruption of Metro Manila s water supply. The impact of the Project is sustained and secured water supply from the Angat reservoir. The outcome is the sustained operation of the aqueducts, to be achieved by (i) retrofitting, rehabilitating and/or re-construction of the aqueducts; and (ii) operationalization of an integrated water safety, risk- and asset management plan. The Project will finance the (i) rehabilitation and/or reconstruction of the aqueducts, and (ii) technical assistance to (a) assess structural and seismic integrity of the transmission system; (b) prepare water safety, risk- and asset management plans, covering the optimization of the system; (c) prepare designs of structural and non-structural measures to support the implementation of these plans; and (d) prepare subsequent investments. These investments may include rehabilitation and retrofitting of intakes, stilling basins and the remaining aqueducts.
Project Rationale and Linkage to Country/Regional Strategy
Leakage reduction. Provision of water supply and sanitation in Metro Manila (Manila) is the responsibility of MWSS, a government-owned corporation. In 1997, it awarded two concession contracts to private firms for water distribution. MWSS retained responsibility for bulk water supply. Manila s main water supply source is the Angat reservoir , which provides about 97% of Manila s water supply . Water from the reservoir is conveyed through a system of tunnels and aqueducts to water treatment plants in Manila. The treated water is then distributed to households, businesses, and industries in Manila, and parts of Cavite and Rizal. The demand on the Angat water source is about 4.48 million m3/day, and is slightly decreasing from 2010 to 2015, as result from the very successful nonrevenue water (NRW) reduction programs of the concessionaires. However, following 2015, the demand will increase rapidly due to expected water supply area expansion and population growth. The demand is expected to increase by 38% in 2025, to 6.16 million m3/day About 15 years ago, MWSS recognized the need to rehabilitate the aqueducts. At that time, the total potential transport capacity of the Angat transmission system, consisting of three parallel tunnels and five parallel aqueducts, was 4.76 million m3/day. However, the actual capacity was about 30% less, due to the high leakage rate especially of aqueduct number 5. To rehabilitate aqueduct number 5, MWSS built a new parallel aqueduct (number 6) in two phases: first bypassing the upstream part of aqueduct number 5, completed in 2003, followed by bypassing the downstream part, completed in July 2012. The current capacity of the system, without aqueduct number 5, is sufficient to match the projected 2015 demand. In order to match 2025 demand, it is essential to rehabilitate to full capacity (i) aqueduct number 5, bringing potential transport capacity to 6.22 million m3/day; and (ii) the other four aqueducts, bringing potential transport capacity to 6.45 million m3/day. Besides restoring the transport capacity of the aqueducts, potential other bottlenecks will need to be identified and addressed, such as the limited capacity of the tunnels and the general configuration of the whole system. Disaster risk management. Besides rehabilitation to restore capacity, the aqueducts need to be reinforced to restore their structural integrity, reducing the risk of complete collapse, possibly due to earthquake damage. This is especially true for aqueducts number 1 and 2 which were commissioned in 1948. In addition, a proper risk assessment will be carried out, and risk management, asset management and water safety plans will be prepared.
Stakeholder Participation and Consultation
During Project Design
MWSS and water concessionaires
During Project Implementation
MWSS and water concessionaires
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