JICA okays P500-M for Angat Dam rehab

SAN RAFAEL, Bulacan – The Japan International Cooperation Agency (JICA) has approved a P500-million grant-in aid to the government for the repair and improvement of the Angat Afterbay Regulatory Dam (AARD) in Bustos, Bulacan, the National Irrigation Administration (NIA) said here over the weekend.

Engineer Manuel Collado, NIA regional director for Central Luzon, said that the amount is intended for scour protection of the concrete apron at the downstream portion of the dam.

He said that the rehab work which will start soon, will ensure the stability of the dam after a series of typhoons which wreaked damage to six of its bays in the past.

It will be the second time that the dam, the longest rubber dam in Asia at 79 meters and the second in the world, will be rehabilitated over a five-year period.

Last March, the JICA dispatched a basic design study team led by team leader Masayuki Watanabe, development specialist of JICA’s institute for internal cooperation, and discussed the project with then-NIA Administrator Manuel Arevalo.

Among the 2.5-meter high, six-span dam’s main features are easily deflatable and inflatable rubber body, resistance to sedimentation, economical and having auto-deflation system.

In December 1996, the rehab work was undertaken under a P400-million grant-in aid from the Japanese government by the Zenitaka Corp. along with Filipino technical counterparts, some two years after the government requested that it be rehabilitated.

The AARD, which was originally known as the Angat Multi-purpose Dam, was built in 1926 50 kilometers upstream from the Bustos Dam as a fixed type river weir without gates.

In 1967, steel sector gates were installed on top of the regulator dam for the purpose of generating irrigation water, power supply and domestic water supply.

With its construction, the Bustos Dam’s height was increased by 2.5 meters and later renamed Angat Afterbay Regulator Dam, increasing the service area of the Angat-Maasim Rivers Irrigation System (AMRIS), which operates the AARD from 25,000 hectares in 1927 to 31,485 hectares in 20 towns in Bulacan and Pampanga benefitting 20,562 farmers.

Collado said the series of typhoons from 1968 to the early part of 1980 was damaging to the dam whose Bay 1 sector gate finally gave way in September 1990 after typhoon "Iriang" carried away the structure 250 meters downstream from its original post.

He said that the agency has undertaken temporary rehab works in the dam using their own budget and through funding assistance from the World Bank.

Once completed, the rehabilitated dam will be maintained by the NIA regional office. - Manny Galvez