Sedimentation and Dredging

Channel siltation at ports and harbours requires regular dredging to maintain suitable conditions for navigation.

This may involve sand that moves along the coast and nearshore areas or fine cohesive mud material suspended in bays and estuaries by waves and currents.

BMT WBM undertakes investigations to determine the key processes causing the siltation, the nature and possible contamination of the sediments and strategies for cost-effective dredging and spoil disposal.  An extensive in-house field data collection and modelling capability is available to support these investigations to assist port authorities and regulatory agencies in managing these vital infrastructure facilities.

Recent Relevant Projects

Port of Brisbane Siltation Studies (Queensland)

BMT WBM has provided assistance to the Port of Brisbane over many years, undertaking the EIS for the Fisherman Islands expansion and a range of studies related to siltation within the Brisbane River and Port channels, as well as strategies for disposal of the dredged material.  During 2011, an analysis was undertaken to establish the asset value of the navigation channels, based on the present day cost of dredging and related works to establish them.  As well, a recent study identified the primary sources and contamination status of sediments that deposit in the river channel as a basis for assessing the best strategy to mitigate the dredging commitment.

Yarra River Dredge Options Study (Victoria)

BMT WBM provided assistance to the Wesley College to develop the necessary documentation in support of the approval submissions for dredging works at their boat launching facility on the Yarra River in Melbourne. A range of technical studies were undertaken to assess the risk of environmental impact to ecologically sensitive areas in the river. A detailed hydrodynamic TUFLOW-FV model of the Lower Yarra River has been developed and validated to extensive field measurements. The model was used to investigate turbidity plume and smothering effects of a number of dredging and disposal options and to determine impacts of dredging on sediment transport processes in the river.

Townsville Port Development (Queensland)

BMT WBM has been involved in studies at the Port of Townsville in North Queensland for many years. We were responsible for the extensive oceanographic data collected in 1992 – 1993 for the modelling and monitoring of the Platypus Channel deepening and extension works at that time.  We have also undertaken data collection and modelling of Cleveland and Halifax Bays associated with a proposed Nickel Ore import facility in the 1990s. This included modelling and assessment of dredging and siltation of Platypus Channel.  As part of the Preliminary Engineering and Environmental Study (PEES) for the port expansion, which was undertaken in 2008/2009, BMT WBM was engaged to develop and employ a suite of numerical modelling tools to assess the range of potential hydrodynamic, water quality and coastal process impacts from future port expansion.  BMT WBM has continued to develop this suite of modelling tools as part of the Townsville Port Expansion EIS using the 3D Finite Volume model engine TUFLOW-FV and has assessed the potential impact of the proposed port expansion.