Underwater noise monitoring during dredging operations in the Ob bay

In 2015, G-tec was awarded a contract with Mordraga (part of the DEME-group) to perform an underwater noise monitoring campaign during dredging operations for the Yamal LNG Project at Sabetta. The site is located on the western shore of the Gulf of Ob on the Yamal Peninsula (Siberia – Russia). Given the limited time window (ice!), dredging operations are only possible in summer. The underwater noise monitoring was done in August and September 2015.

DEME-group promotes a sustainable approach throughout the organisation, whereby the environment is considered one of its core values.  As such, the dredging project team is very engaged with any potential impact of their operations on the environment. The remote and pristine location of the project in the Arctic Region resulted in an elaborated Environmental Management Plan, including the appointment of an Environmental Captain. Underwater sound was one of the many environmental topics under investigation.

G-tec’s mission concerned the measurement of the underwater noise originating from different vessels like trailing suction hopper dredgers, a cutter suction dredger, ploughing vessels, etc. under different operations. Underwater noise monitoring was performed both at the Sea Channel in the Ob bay and the Sabetta Port area, separated some 100 km from each other. A flexible and stable measurement system was used including acoustic recorders at different heights in the water column.

At the end of the noise monitoring campaign on site, a large dataset was gathered. To undertake an efficient processing, the in-house developed software “SonoMar” was used to merge all available information, to calculate the applied acoustic parameters and to link each noise measurement to a specific vessel. Moreover, the environment was simulated by using an acoustic model to obtain the so-called source levels of the vessels.