outline method
   

LAWS’ unique, 10” cutter suction dredger, is mobilized to site by road and craned into the water-body using a mobile crane (total mass = 14,300kg). A fixed pipeline is then established alongside the foreshore using a small, tracked excavator to deploy the pipeline. The fixed pipeline will discharge to a purpose made settling lagoon (excess waters arising from the settlement process are back-pumped or gravity fed to the water-body in which the dredger is operating). The dredger is connected to the fixed pipeline on the edge of the water-body using a floating, flexible umbilical pipeline. 

Dredging is undertaken in a series of parallel cuts (in a similar fashion to a combine harvester), by a shrouded dredge head which is lowered beneath the dredger on a fixed arm. The dredge head comprises a scroll feeder (the “cutter head”) which agitates the sediments within the dredge head/shroud and feeds them directly into the mouth of the pump which is mounted immediately behind the scroll. The fixed dredge arm is pivoted beneath the dredger on a winch operated gantry and has a maximum dredge depth of 6.7m. The slow rotation of the scroll feed within the dredge head shroud mitigates the turbidity and local impact of the dredge operation. 

The dredger is positively positioned with the hydraulically driven star wheels (propelling the vessel along the floor of the water-body) or by means of deck mounted hydraulic winches on a guide wire system. 

 

 

Road Transportable Cutter Suction Dredger, Dredging Cohesive Mineral Waste (note one of the Star Wheel drive units is raised at the rear).    
Once inside the pump the sediments are mixed to an approximate concentration of circa 15-20% solids (80-85% water), and pumped down the pipeline as a thoroughly mixed solution.  

Pumped Discharge of the Dredge-Mixture