The 'Paardenmarkt' site is a former dumpsite of WWI munition (conventional and chemical). Excavation of the munition is to expensive, so a possible management alternative is capping of the site. A first step is to determine the hydrodynamic and sedimentological boundary conditions. These boudnary conditions serves as a basis to select to the most appropriate capping construction, and a preliminary design is elaborated. Special attention is being paid to the cost price and difficulties or limitations of the execution.