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An engineering marvel 

Ambuklao's green sinews 
The Rebirth of Ambuklao

A road trip to the Ambuklao hydroelectric power plant is hardly for the faint-hearted. It may very well be a mere 40 kilometers from idyllic Baguio which, when considering the 210 travelled from Manila, may seem paltry. Just like the history of this majestic piece of history, the road has its ups and downs and, to the uninitiated, may seem like an eternity.

Yet it is well worth it, if only to see for yourself this magnificent marvel of engineering from 60 years past, once again providing electricity to the country after years and years of inactivity.



Checkered past

Ambuklao’s story began in July 1950 when the Guy F. Atkinson Company of San Francisco, USA (it is still around…) broke ground on the construction of the project. Based on the design and engineering of Harza Engineering of Chicago, USA (also still standing as Montgomery Harza) and the Widmark & Platzer Company of Sweden, the project was to have a 129-meter high dam, 452 meters at its crest with a spillway 124-meters wide. The resulting reservoir would extend back 11 kilometers from the dam while three 25-megawatt (MW) Francis horizontal shaft turbine generators made by General Electric provided 75 MW of capacity for the Luzon grid.

She was completed by mid-1956, and began to deliver 41 MW to Meralco in August of the same year. Total project cost was reported to be P132 million. At the time of its inauguration by President Ramon Magsaysay in January 1957, it was the largest hydroelectric power plant in the Philippines in terms of generating capacity, eclipsing 25-MW Maria Cristina hydroelectric power plant in Lanao, likewise completed in 1956.

It could not have come at a better time. The electric appetite of post-war Manila was insatiable, growing at double-digit rates and wreaking havoc on the country’s power planners. In 1956, Meralco’s power sales for the year were 917,000 megawatt-hours (MWh). Despite 185,000 MWh delivered by Ambuklao in 1957, the utility still found itself in need of additional generation and installed another 25-MW unit for its Rockwell power plant in 1958.

By 1959, 100-MW Binga hydroelectric power plant, located 19-kilometers downstream from Ambuklao and dependent on its water, was commissioned. The duo served the Philippines well, together providing 175-MW or enough power for approximately 350,000 households.

Beginning of the end

Sadly, in the earthquake that struck the Philippines in July 1990, heavy siltation began to take place in the Ambuklao reservoir. The accumulation constricted the intake, hindering flow of water into the powerhouse. Numerous attempts by different parties failed to resurrect this sleeping giant. By 1999, Ambukao hydro ceased to produce electricity, languishing in inoperational silence ever since. The degree of siltation was simply too difficult to overcome.

In December 2007, a consortium comprising AboitizPower and SN Power of Norway (SNAP) bid for, and obtained the Ambuklao and Binga plants from the Philippine government for $325 million. The failure of prior attempts to rehabilitate Ambuklao did not deter the new owners—immediately they set out to find a solution to the Ambuklao puzzle.

A tremendous challenge to all

Ambuklao was acquired primarily because of the prospect of bringing it back into working order. This did not take long to be afoot.

“We knew from the start that our work was cut out for us. First, we had to adopt a different strategy to engage our community stakeholders, win social acceptability of our projects, and ensure the sustainability of our business. The facilitated dialogue process sponsored by the World Bank also provided an effective framework for continued communication with our stakeholders. Through our CSR and stakeholders engagement program, we have hurdled these initial challenges and rallied community support and cooperation in our rehabilitation of the Ambuklao plant,” shared SNAP President and CEO Manny Rubio.

In August 2008, contracts were signed with suppliers and by October 2008, excavation and tunneling works commenced. By November 2009, the silted inlet valves that were causing so much trouble were permanently plugged, after which, work in the now completely dry powerhouse could begin. Thus began the dismantling of the old turbines and assemblies.

Rubio added that the rehabilitation of the Ambuklao plant posed enormous technical and logistics hurdles such that previous attempts to rehabilitate the plant did not succeed.

“We were bent on overcoming those challenges, massive as they were, requiring major replacements and construction works in the intake and tunnel areas, the powerhouse, and even the tailrace area. So we had to find the right technical solution, plan alternatives, bring in the right people, acquire the best equipment and find the best way to transport some 90-ton electro-mechanical parts while doing everything in the safest way possible,” he said.

On top of this, SNAP had to constantly consider timing the rehabilitation work during the driest time of the year, considering that the plant was located in the wettest part of the Philippines. Their worst nightmare came true during the onslaught of Typhoon Pepeng (Parma) in 2009 when, at the peak of the rehabilitation work, the Ambuklao and Binga dams experienced record inflows in 60 years. Compounding the problem were the prevalent landslides experienced along the only major road leading to and from Ambuklao, which isolated the area for more than two weeks at height of the typhoon.

A promising renewal

In March 2010, the project team abandoned what had heretofore been the primary water channeling solution, which was the use of the old headrace, or the tunnel that fed water from the intakes into the powerhouse. Additional silt formation from the past year's typhoon led to this decision and the adoption of the back-up plan: the construction of a new and extended headrace.

“There was a growing sense of pride, gratitude, and even relief that almost three years of rehabilitation work would soon be over. It has been very fulfilling for those who have been involved in this project. Perhaps we can say we made our own little history here, but for the most part we are just happy to bring Ambuklao back to life after 12 years. Now, we are looking forward to full operations. After all, a project is said to be really complete when it starts working for you, rather than you working for it,” observed a delighted Rubio.

SNAP had ensured that no detail was too small for upgrading. The team had replacement done on turbines, main inlet valves, generators, transformers, switchgears, control system, circuit breakers and hydraulic structures (specifically intake gates, draft tube gates and stop logs).

Finally, by May 2, 2011, water was allowed into the tunnel to determine the viability of the new solution. Having passed with flying colors, in May 17 water turned a turbine at Ambuklao Hydro for the first time in more than 20 years. In June 1, it synchronized with the grid and commercial operations began.

As they say, done is better than perfect and the challenges that SNAP faced now faded into the background as they neared the completion of the project.

“To our knowledge, no other plant in the Philippines has undergone rehabilitation work with the scope and magnitude of Ambuklao. We were very determined to be the company that revived Ambuklao and with the successful rehabilitation, also committed to be the company that creates shared value for host communities,” Rubio said.

AboitizPower is the holding company for the Aboitiz Group’s investments in power generation, distribution, retail and power services. It is a major producer of Cleanergy, its brand for clean and renewable energy in the Philippines with several hydroelectric and geothermal assets in its generation portfolio and also has non-renewable power plants located across the country. The company owns distribution utilities that operate in high-growth areas in Luzon, Visayas and Mindanao. (For more details, please visit: www.aboitizpower.com and www.cleanergy.com.ph.)
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