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DOP Saves Explosive Dredging Situation
01 Feb 2007
Works have been ongoing to enlarge the Twentekanaal, an important shipping channel in the east of Holland. Enlargement will allow the canal to accommodate larger ships and will also provide additional capacity for water drainage. The project was proceeding in a normal fashion until explosive devices were found in the dredged mixture, halting all works with immediate effect.
A survey identified the explosives as ammunition dating from the Second World War which had been dumped into the canal in large quantities, especially near convenient quaysides and bridges. The explosives could not be brought above water level for obvious security reasons, so all backhoes and other excavators were banned from the works.
Still, the dredging had to continue and contractor Martens en van Oord contacted Damen Dredging Equipment for an instant solution to an explosive problem which was impeding project planning. Within two months the necessary equipment was designed, built and delivered.
Martens en van Oord was doingt the job with a pontoon based hydraulic excavator. In close cooperation with Damen Dredging Equipment, the two companies designed a specialised suction mouth which could be attached to a DOP submersible dredge pump. The heavily constructed suction mouth was given a grid with relatively small openings to prevent explosives entering and jetwater nozzles. With explosives thus left on the canal bed, the powerful jetwater assistance prevents the grid from clogging and increases mixture flow.
The DOP3530LD submersible dredge pump, to which the special head is directly attached, was connected to the boom of the existing hydraulic excavator. It pumps the dredged mixture through a discharge line over the pontoon to a very heavy duty, funnel shaped barge loader. Should any explosive manage to get through the grid and the dredge pump, it is caught in the funnel, allowing barges to be filled without danger. The funnel has a hatch to empty it from below. The complete configuration has now been patented by Martens en van Oord.
The new DOP configuration, which was delivered complete with power pack, hoses and other accessories, has now been working long enough to prove it a complete success. Barges have been filled continuously with no explosives found and the project continues apace once more.
MJ Information No: 22717
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