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My understanding 21st December 2025
Netherlands standard - https://connect.nen.nl/ - full text freely visible on line after registration. In the Netherlands, before dredging first you have to conduct a preliminary investigation following: NEN5717 Soil - Sediment - Strategy for the preliminary investigation of the environmental quality One of the outputs of the preliminary investigation is a stratification of the area to be dredged into sublocations which are internally relatively homogeneous and typically between 10 and 30 hectares in size. then you follow: NEN5270 Soil - Sediments - Strategy for exploratory investigation or the environmental quality The Port of Rotterdam authority follow this procedure and take 6 samples from each of 300 different locations within the dredged area.
The Netherlands does not dump dredged material at sea, instead it relocates sediment for beneficial uses and takes contaminated sediment to land where it is treated. Rivers are dredged by a national authority with the maintenance dredging process being described here and a series of dredging depots are operated to store and treat contaminated dredged material.
Licensing of disposal to sea is not used, instead dredging is licensed under national water / soil standards and as these exceed OSPAR requirements, so the developer/port authority does not touch OSPAR.
Policy Rule on the Application and Distribution of Dredged Material in the North Sea