Auger head; the perfect tool for (extreme) environmental dredging operations?!
Type:
Presented during:
CEDA Dredging Days 2005 - Dredging: The Extremes, Rotterdam
Authors:
Winkelman M.O. and Tenwolde D.
Abstract: Environmental, or environmentally friendly, dredging aims to remove polluted sediment layers with minimal ecotoxicological impact on flora and fauna. Damen Dredging Equipment (DDE) is a leader in the design and construction of sophisticated auger systems for use in environmental dredging.
Special designs and procedures are applied to minimise the volume of material dredged so as to limit treatment or storage costs and to prevent further distribution of pollutants. This results in designs characterised by minimal dilution of the bottom material excavated, high precision positioning, minimal spillage, minimal turbidity contribution caused by the dredging action, and optimal manoeuvrability to optimise the excavation pattern.
The auger excavates and moves the bottom material to the suction entrance at a transport density close to the in-situ density. Through the combined measurement of bottom depth in front and behind the auger head and the hauling speed, the volume is linked to the flow in the dredge pipeline, which is adjusted by the dredge pump speed to a bottom material concentration up to 80% of the total flow. DDE's submerged dredge pump design is positioned as close as possible to the suction inlet to increase densities that can be transported to the extreme maximum.
The continuous mechanical excavation possible with the auger and its trailing bottom shoe in combination with the high vertical position accuracy ensure that minimal spillage occurs. As the dredge encounters widely varying soil and debris conditions, the auger design maintains low turbidity and high efficiency.
Keywords: environmental dredging, auger head, minimal turbidity, precise positioning.