Sub-centimetre measuring

In Linkou, different types of soil are being dredged: mudstone, boulders, fine sand... This makes it difficult to establish the perfect volume balance and production levels. The survey team monitors the dredged volumes very accurately, in real time and down to the nearest centimetre.

In every marine project of Jan De Nul, the survey team is a crucial link within the supply chain. Without accurate positioning and accurate measurements of the starting levels and production volumes, our vessels would sail blindly and it would be impossible to determine whether we would be able to achieve the target levels, within the pre-set deadlines.

“I personally find this the best job there is”

says Vicky Gelaude, chief surveyor for the project in Linkou.

“The most hectic period is the start-up phase. We set up a base station with our own GPS system to enable us to accurately measure everything down to the last centimetre. We double-check all fixed coordinates passed on by the client. This determines the position of our vessels. This first step is absolutely essential. We also install a tide station, which transmits the water levels in real time to the vessels, and fully equip our survey vessel, connecting our measuring devices ourselves. Sometimes, you can even see us soldering the wires. All this makes it a very varied job.”

A major challenge in Linkou is the different types of soil. “Our data determine how deep the cutter and suction hopper dredgers must go to realise the contractually established delivery target. But in Linkou, we had to consider the fact that the soil is raised compared to the pre-determined starting level because we first have to cut it loose with the cutter dredger. As a result, the production levels are continuously changing in the course of the dredging process, which makes it even more important for us to monitor and measure everything very intensively and accurately. Checking and double-checking the results is crucial in this project.

 

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