To protect the historic city of Venice against recurrent flooding, a huge project has been undertaken, involving the design of movable gates located at the three lagoon inlets for controlling tidal flow. Selection of the gate foundations demands very careful experimental investigation and modeling of the Venice lagoon soils, composed of a prevalent silt fraction combined with clay and/or sand forming an erratic interbedding of various types of sediments. To this end two typical test sites in the lagoon area - the Malamocco and Treporti Test Site – have been selected for characterization of the silts. Some interesting results from the research carried out at the two sites concerning the mechanical behavior in secondary compression are here presented and discussed.