Van Oord and joint venture partner Boskalis recently completed an extensive dredging project in Walvis Bay, Namibia.
With trailing suction hopper dredgers Vox Alexia and Gateway, the companies deepened the 10-kilometre-long access channel to the port of Walvis Bay from 14.4 to 16.8 metres and widened it from 130 to 200 metres.
In addition, both vessels worked to dredge the harbour basin to a depth of 16.3 metres and expanded it by more than 400 metres.
"A major challenge on the project was the presence of excessive concentrations of toxic hydrogen sulfide (H2S) in the dredged sediment," said Van Oord.
"To mitigate this risk, a large number of health and safety measures were taken during the mobilisation prior to the project, including modifications to the vessels and the installation of dozens of sensors and special H2S filters.
"Also, the vessel crews were trained on how to deal with H2S. They were able to measure the concentration of H2S in the air at all times and established safe working protocols on board."
A large number of sensors were also installed on the quays of the port area to alert the workers and users of the port in time in case the gas appeared.