Abstract: A system for optimizing the dredging of an area by a vessel (25) equipped with a cutter head (4), including an apparatus to measure local seismic velocity in front of the vessel (25), said apparatus including a set of seismic receivers (11, 11?, 11?, 11??) supported by a frame (10) configured for attachment to and projection from the bow end of the vessel, which frame aligns the seismic receivers (11, 11?, 11?, 11??) above and in front of the cutter head (4). A method for optimizing dredging.

Abstract: A process for immobilizing impurities present in silt This invention relates to a process for immobilizing, inactivating and/or neutralizing impurities present in silt, the silt layer being covered with a layer of a material in finely distributed state, after which at least part of the silt layer is worked loose, a hardenable additive composition is injected in the silt layer and is mixed with the silt layer for binding, immobilizing, inactivating and/or neutralizing the impurities in the silt.

Abstract: An apparatus and method for dredging under water ground layers includes the steps of providing a dredging device composed of a mechanical dredging component having a part operative to contact the under water ground layers and exert a dredging action; and at least one water jet effective to inject water under pressure in an area where the mechanical dredging component is operative; mechanically impacting the underwater ground layers with the part to fracture the underwater ground layers and form fractured material; and injecting water under pressure from the at least one water jet simultaneously with the mechanical impacting to remove the fractured material so that an improved break-away pattern of material is obtained and reduced wearing of said part.