Failure modes assessments for three multipurpose dams in the Philippines

Client: First Gen Hydro Power Corporation
Location: Philippines
Date: June - August 2017

Assessing dam failure modes to focus surveillance and mitigate risks for safe and sustainable dams.


Three key dams supply water to the 120 MW Pantabangan Hydro Electric Project and the 12 MW Masiway Hydro Electric Project owned by First Gen Hydro Power Corporation (FGHPC): Pantabangan Dam, Aya Dam and Masiway Dam. Pantabangan Dam and Aya Dam impound Pantabangan Lake that is considered one of the largest reservoirs in South-East Asia, and is critical for irrigation as well as for power generation. Masiway Dam impounds a regulating storage downstream of Pantabangan Dam, providing a consistent discharge for irrigation.

Previously, Entura had identified that failure of any of these dams would have significant consequences both for FGHPC and for the dam owner, the National Irrigation Administration (NIA), with major potential impacts on food supply and power generation from the loss of the Philippines’ most important multi-purpose water supply.


For the three dams, Entura developed a methodology to systematically assess the failure modes while also providing input and enabling knowledge transfer between Entura dam engineers and
staff of both FGHPC and NIA.

Entura listed the key failure modes for each of the dams based on a background review, initial assessment and site visit. We then undertook a failure modes workshop that included a generic presentation on failure modes and dam safety monitoring as an introduction, equipping workshop attendees with the knowledge required to fully participate in the workshop.

The results of the failure modes assessment were presented and discussed in a follow-up workshop with FGHPC and NIA staff to obtain further feedback and ensure the final report met their expectations. This presentation included a review of the dams’ inspection and monitoring programs and improvements required to focus on the key failure modes.


Through the dam safety failure modes analysis, we identified the critical dam surveillance tasks appropriate for the associated failure modes and made recommendations to focus the dam safety program on the key failure modes. 

We also identified a number of unknowns and recommended additional studies that would obtain further information to better understand certain failure modes, enabling improved dam safety and risk management.