Last week, a number of stakeholders signed a memorandum of agreement (MoU) for the 47-year-old 246-MW Angat hydropower facility, located about 58 km northeast of Manila in Norzagaray, Bulacan, Philippines, to undergo a US$24 million rehabilitation project.
Angat Dam impounds the Angat River, creating the Angat Reservoir. In addition to supplying power to the Luzon grid, Angat Reservoir provides for the irrigation needs of 25,000 hectares of farm lands in Bulacan and Pampanga.
The Angat plant contains four turbine-generating units, each with a capacity of 50 MW, commissioned in 1967 and 1968. The plant also uses five auxiliary units that have a total capacity of 46 MW.
The facility supplies more than 90% of Metro Manila’s potable water needs and this is its first major rehabilitation since the facility was commissioned in 1967.
The MoU is between the Dumagat community (indigenous people), Power Sector Assets and Liabilities Management Corp., the National Power Corp. and Angat Hydropower Corp. (AHC), which is co-owned by Korea Water Resources Corp. and San Miguel Corp.’s SMC Global Power through its subsidiary Power Ventures Energy Inc.
According to AHC, the to mitigate potential dam safety issues, the rehabilitation will consist of:
- Raising the impervious or clay portion of the core of the main dam by 1.2 m to substantially improve the overall strength of the dam;
- Widening the base and the downstream slope of the dam and dykes using rockfill from a nearby quarry used during the original construction of the dam; and
- Increasing the new slope from 1:1.40 to 1:1.55 in proportion.
According to a dam safety study completed in 2015 for AHC, in case of an extreme flood event, Angat Dam will remain safe if all three of its existing spillway gates remain functional.
AHC said, “Thus, the immediate priority is to ensure the proper maintenance of these gates so they continue to operate during floods and remain efficient at lowering the volume of water in the dam.”
The company did not specifically name what, if any, work will be done on the spillway gates.
AHC noted the country’s Department of Environment and Natural Resources issued an Environmental Compliance Certificate for the project in June 2015 and preconstruction work began the next month.