New dredgers yield more coral fill


28-November-2011

Ministry of Land Use and Housing (MLUH) officials said this at the Ile du Port where Jan De Nul's Cristobal Colon – the world’s largest high-tech ocean dredger that was here on a two-day transit – extracted fresh supplies of coral fills for the construction industry.

The world’s largest high-tech ocean dredger

The material is mainly sand that can be used for construction if washed off of its salt content.

The trailing suction hopper dredger was transiting on its way to Vietnam and was due to leave Seychelles during the weekend.

The MLUH said the government is investing 4.6 million euros in the new dredging project which will give enough coral fills to supply the construction industry within the next five years.

Fresh supplies of coral fills extracted by Cristobal Colon

Cristobal Colon did the initial phase of the project involving much heavier work, and by December a smaller dredger will be coming to Seychelles to complete the dredging, said the officials.

The principal secretary of Land Use and Housing Christian Lionnet said the government has carried out a feasibility study under the Environmental Impact Assessment (EIA) two years ago to decide on the best area to carry out the extraction. This was due to the depletion in the stock of coral fills for the construction industry, largely attributed to a major increase in demand. The ministry had previously allocated an area at the Ile Persévérance for extraction, but the available stock there has already been used.

“We have started to reach water, which means that it was no longer feasible to continue extraction in that area,” PS Lionnet said.

The said area has now been turned into a small lake.
Ps Lionnet said the stock pile will be placed at Ile du Port, where bunding work has been carried out.

Besides deepening the seabed in the mentioned area near the Silhouette island, the dredging work is not expected to have any negative effects on the environment.

Cristobal Colon which forms a part of the huge vessel fleet of the Belgian shipping infrastructure conglomerate Jan De Nul was launched in 2008. Among its main design specs is 46,000 cubic metre hopper, which is nearly 40% more than what the Vasco da Gama has, and a very high dredging depth of 155 metres.

Being the world’s largest dredger, Cristobal Colon forms the flagship of the company’s dredging operations. Also, owing to its massive capacity and several other salient features, the Colon is currently rated as the top class dredging ship.

Reaching such a depth is possible because of its technologically powered dredging pumps which are submerged beneath the water surface. These pumps are operated electrically and provide a power of 6,500 kilowatts each.

There are two pipes which provide suction for the dredger and which measure 1,300 millimetres in diameter while the pumps to discharge the collected deposits are also operated electrically with a power of 8000 kW each

The pipes to carry out the suction can be altered or customised to dredge deposits at three various depths. This facility gives the Cristobal Colon the feasibility to carry out the dredging operation irrespective of the level of deposits in the water

The material used to build this largest ship is steel as it is non-corrosive in nature and offers a lightweight movement in the water, enabling the ship to carry out its operations without any problems whatsoever.

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