Geophysical supporting to the civil engineering: an example in the construction of the pipeline of Portugal

The pipeline coming from Algeria to the north part of Portugal and Spain, concretely between the localities of Braga and Ponte of Lima, runs by a superficial soft layer, relatively constant, caused from the alteration of palaeozoic materials (schists and graywackes). The pipeline construction found problems upon attempting to cross two important rivers, Cávado and Lima, as the geotechnical wells drilled in the surroundings gave different geological information in both borders.