The Casecnan Project was the subject of numerous studies from 1980-1994 that focused on maximizing the potential resource for power generation and diversion of water into the Pantabangan reservoir to expand an existing irrigation system. The studies also focused on a concept involving full regulation of the Casecnan River with a 190 m high dam, 28 km power tunnel and powerhouse.
Knight Piésold developed an alternative concept for the overall scheme with a view to optimizing its potential and making it attractive for privately funded development. This eliminated significant concerns over flooding of villages by converting the project into a run-of-river scheme.
Knight Piésold developed the revised concept into a 150 MW run-of-river multi-purpose hydroelectric and water transfer scheme. The project involves two run-of-river intakes, 26 km of power tunnel, and an underground powerhouse containing two vertical axis 75 MW Francis type turbine/generator units operating under a gross head of 265 m.
The scope of the project involved: review of excavation progress for three 6.5 m diameter TBMs; geotechnical mapping and rock mass classification; hydrogeological assessment; temporary support assessment; inspection of final tunnel support installation; review of final lining design and construction QA/QC.