Geotechnical study in Ullà

In Ullà, the predominant soils correspond to muds and peats of deltaic origin, followed by fine sands, silts, and detrital formations such as sandstones, conglomerates and flysch. The significant proportion of muds and peats implies the need to avoid these materials as a bearing level for the foundations, due to their low bearing capacity and high compressibility. On the other hand, the presence of fine sands and silts requires careful analysis of densification and possible settlements, whereas the detrital and carbonate materials offer better stability conditions and bearing capacity at depth.

With regard to geotechnical risks, seismicity in Ullà is very low, with only 2 events in 30 years and an Mmax of 1.6, so it is not relevant for structural design. There are no indications of karst processes and, since it has a non-clayey substratum, expansivity risk is ruled out. The main constraint for the feasibility of the foundations in the area lies in the identification and avoidance of layers containing muds and peats, prioritising support on stable granular or rocky materials.