WAMS understands that surveys for dredging need to be extremely accurate, since a few centimetres error in measurement over a large area to be dredged can drastically affect the calculations for volume of material to be removed, while many dredging contracts are priced on the volume of sediment being extracted.

WAMS survey team applies ultra-high frequency multibeam echo sounders in combination with side scan sonars to not only establish the relevant bathymetry, but also to detect any hazards that may need to be removed prior excavation of the material. Large rock, or even a piece of rubbish like a tire, could cause major breakdowns if the dredgers were to pump it up with the surrounding seabed. WAMS can also offer conducting an environmental impact assessment for the proposed dumping ground area where the excavated volumes are to be laid down since its also a major consideration – the material must not be dumped so close to where it was extracted that it is washed back in again due to strong currents.

WAMS has experience and expertise to undertake a comprehensive marine site pre-dredge survey from which, knowing the required depths and sediments composition type, the volume of material to be extracted can be computed and dredging companies invited to tender for contract. In regions characterized by mobile sediments type or subjects to rapid siltation, by the time the contract has been let and the work is due to begin, further shoaling may have occurred, so in this case the dredging company will arrange to conduct another survey, to show if they are going to have to remove more spoil than they had tendered for. Monitoring surveys may be conducted by WAMS during the ongoing dredging operation to confirm that the required depths are being met – too deep and the dredging company squanders its money, too shallow and it does not get paid. Our experience has proven that in some cases it is cheaper to monitor the depths as dredging progresses as frequently as daily, rather than to bring the dredger back later to dig more deeply. In a lengthy and large-scale dredging projects, periodic monitoring surveys may be used to award stage payments to the dredging company. Upon completion of the dredging operations WAMS will carry out a site post-dredge or so called “payment” survey, which will determine if the contracted work has been achieved and so trigger final payment to the dredging company.

WAMS can also offer an independent and reliable audit-assessment of the dredged volume so the commissioner of the dredging project (the main client) can rely on its unbiased results rather than taking for granted the surveys arranged by the dredging company.