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.

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: and

This article is posted in behalf of:

Judy Anne Teo
Christopher Cahilig Consultancy Services
Unit 2203 Cityland Shaw Tower,
St. Francis Street cor. Shaw Blvd.,
Mandaluyong City
Cellphone: 09322453779
Landline: (02)687-2649