An Innovative and Sustainable Solution for Sediment Disposal Problems
Type:
Presented during:
WODCON XVIII - 2007 Orlando, Florida, USA
Authors:
Foged
Abstract: Vast amounts of sediments must be dredged from ports, harbours, and waterways around the world to maintain and improve navigation systems for commercial, defence, and recreational purposes. Globally, several hundred million cubic metres of sediments must be disposed of. Traditional dredging methods discharge sediments into confined disposal facilities (CDF) or oceans, rivers, lakes, wetlands and estuaries. In several countries, dredged material containment facilities currently in use are nearing or are already full to capacity with dredged material. Identifying new containment sites is difficult due to conflicting land uses, potential environmental impacts, and high value of near-water real estate. To counter these difficulties, MWH proposes an innovative approach.
Dewatering the sediment’s material, yields an end product with good soil mechanical characteristics. High dry matter content can be obtained, which results in a high reduction in volume. A volume of sediment of 1.000.000 m³ at 30 % dry matter (DM) can be reduced to a volume of sediment of 385.000 m³ at 60 % DM. In an environment with increasing demand for land, this gives an important advantage.
Additionally, the good soil mechanical characteristics make it possible to actually stockpile the dewatered material, and the permeability of the compacted dewatered material can also reach a value of 1.10-9 m/s. This offers a huge benefit towards the reduction of risks of stockpiled material towards the environment. Also, a significant decrease in the amount of leachate can be observed.
The dewatering process offers a feasible and sustainable solution and results in a material that shows new possibilities for future applications and reuse of the dewatered sediments. Possible re-use examples are landscape dikes, isolation layers for disposal sites or remediation activities, road construction, sintering and clay-substitution in other industries.
In this paper numerous advantages of dewatered sediments on a social, economic and ecological scale will be demonstrated.
Keywords: Mechanical dewatering, separation of co