Environmentally Sound Precision Dredging Using a Mud Cat Dredge

The Mud Cat dredgehead has very high precision, minimum turbidity and low water flow as its special features.

Long-term discharge from industries means that our lakes and waterways are exposed to major stress – stress that finally leads to waterways silting up. Sometimes chemical and biological pollution has been allowed to continue for so long that the only chance for rescue is to dredge and treat the sediments that have collected on the bottom.

At NCC Facilities there is long experience and solid capabilities gained from research and development projects in environmental dredging and sediment treatment and in efficient and environmentally safe dredging. We have chosen to gather and concentrate our resources in a consortium under the name of MILMAN Environmental Dredging. We handle dredging and cleanup projects from project planning through execution.

Advanced technology

Our technology is very advanced and Mud Cat dredging equipment is specially adapted for clean-up dredging. The dredgehead designed by Mud Cat’s™ Division has very high precision, minimum turbidity and low water flow as its special features. That makes our equipment unsurpassed in cleanup where the sediments have excess nitrogen or contain heavy metals, for example.

The technology on board our vessels includes both positioning and depth sounding equipment that shows exactly where we are on the bottom to better than an inch. Computers on board can store facts and information about the appearance of the bottom, obstacles, flow and dry material content, along with much more.

The dredgehead is held in position and moved – like a pendulum, from side to side – by four anchored wire cables. With its unique design – horizontal auger and adjustable shields – the material to be dredged is loosened and removed with a minimum intake of water and agitation of the sediment. By pumping straight sediment without unnecessary water mixing in, removal is very efficient and capacity is comparable to dredgeheads many times larger.

Positioning is done with the help of a 140T Geodimeter that operates with infrared light and radio. The progress of the dredging is monitored continuously with scanning echo depth sounders ahead of and behind the auger.

Continuous on-board monitoring

We maintain continuous on-board monitoring of both sediment removal and environmental effects. We maintain a constant check on water turbidity and sediment removal. The position of the dredge auger relative to the bottom terrain is monitored continuously by the computer system with the help of precision positioning. Continual echo depth soundings are made to be certain that sediment removal is proceeding correctly and that no uncleared areas or mounds have been left. In addition we can continuously calculate the theoretical volume of material removed.

Facts about the MILMAN II Mud Cat suction dredge.


Length overall: 33.0 m
Beam: 4.3 m
Draft: 0.8 m
Displacement: 40 T
Engine: Scania 282 kW @ 1800 rpm
Pump: Gould 10/8 inch, 600 m3 @ 60 m head
Auger width: 3.5 m
Auger diameter: 0.5 m

Operating Data

Working depth: 1-14 M
Swing width: 0-200 m
Swing speed: 0-12 m/min
Depth of cut: 0.1-0.5 m
Removal rate: 100-200 m3/hr (dry material)
Pump range: 200 m @ 10 m head with booster pump:> 2000 m

You’re welcome to contact us!

NCC Facilities and our specialties are represented all over Sweden. Specialist capabilities for environmental dredging are based in Kalmar and Ljungsbro. You can contact us by telephone at +46-480-47 64 26 or +46-13-637 55, or call your local NCC representative.

170 80 SOLNA
Telephone: +46-8-655 20 00
Fax: +46-8-624 05 19

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