Controlled submerged deposition of fine grained dredged sediment with various diffuser types
Type:
Presented during:
WODCON XVII: "Dredging in a Sensitive Environment" - 2004, Hamburg, Germany
Authors:
Mastbergen, Dick R., Van Kesteren, Walther G.M. and Loman, Gerard J.A.
Abstract: For the disposal of fine grained dredged sediments and soft soil under water in confined disposal facilities or in open water in sea or lakes, often a vertical pipe with a diffuser is applied to reduce turbidity generation. It will be shown that the density of the dredged soil-water mixtures defines the geometric design of the diffuser and successively the free falling plume flow towards the sea bed.
A bell type diffuser and a multiple tremy were tested on model scale at WL|Delft Hydraulics. Furthermore, field measurements of reduced turbidity generation by an improved Boskalis-patented diffuser are shown. This radial double-plate diffuser type has been developed by Boskalis for the placement of soft soil in a lake in the Netherlands These measurements prove the importance of the release height and the control of the outlet slurry flow velocity.
Keywords: diffuser, tremy, Boskalis-patented diffuser, turbidity, plumes, scale model tests, field measurements