Deformational Behaviour of Pyroclastic Rocks Beneath the Upper Reservoir of the Hydro-Wind Plant at El Hierro

El Hierro Hydro-wind Plant is a singular project, as its aim is to make the island energy self-sufficient. It involves constructing two reservoirs—the higher of which began being constructed in September 2009. This article attempts to reflect the peculiarity of the behaviour of the materials at the bottom of this reservoir, which will have to support a significant hydrostatic load, and the difficulty of characterising these in laboratories and design offices in order to assign geotechnical parameters to them which will reflect their geotechnical performance in situ. The studies undertaken to achieve this characterisation are described and the expected settlement of the materials is analysed. Finally, the article describes in detail the ground treatment proposed in order to minimize settlements, whose estimated values are compared with those obtained at the works site.