STRATEGIES FOR MANAGEMENT OF DREDGED MATERIALS IN THE NETHERLANDS

摘要

Dredging of waterways is of vital importance for our economy, ecology and water-management. Each year tens of millions of cubic meters, partly contaminated, dredged materials have to be removed. The main reason is maintenance of waterways for shipping and water discharge but also remediation of contaminated sites can be the reason to execute dredging. Dredging is needed to fulfil objectives in the Dutch policy for ecology, environment, transport over water, accessibility of harbours, water discharge and reduction of risks for flooding. However, because of lack of financial means and insufficient destinations for the dredged materials, dredging is in arrears. Most of the dredged materials, which are clean or lightly polluted (following the strict Dutch standards), are relocated in sea, surface water and on land, but these solutions are under discussion. Proposals for new legislation on relocation on land and in the sea, based on ecological criteria, are in preparation. Less relocation will lead to huge volumes of dredged materials that have to be disposed or treated, for which the available facilities have insufficient capacity; this means a dramatic increase of the costs. For the more heavily contaminated dredged materials some large sub-aquatic confined disposal sites have been built. More disposal sites are needed but the resistance against new sites is growing (nimby) and politicians plea for more sustainable but also more expensive solutions such as treatment for beneficial use. Up to now only small volumes of dredged materials have been treated, mainly by sand separation. One of the problems is to find a market for the products. From the foregoing it is clear that destinations for dredged materials will become scarcer and more expensive in the future, while the present budgets are already insufficient.