Navigable Mud: A smarter approach to waterway management and dredging

Managing sediment in waterways is more critical than ever. With vessels growing in size and sailing deeper, the traditional reliance on frequent dredging to maintain navigable depths has become increasingly costly and, quite frankly, unsustainable.

There is growing interest in the idea that navigable mud management might be part of the solution to the pressures faced by the sector, and adoption of strategies around this could significantly reduce dredging costs, lower greenhouse gas emissions and sustain delicate marine ecosystems, but why should companies consider this option and is it really a viable solution.

Larger vessels, less dredging

As vessels get bigger, the instinctive response is to dredge more. After all, larger ships have deeper drafts, so it wouldn’t be surprising to assume they need more space to move.

However, it is important to avoid excessive dredging whilst accommodating these larger vessels. By recognising that fluid mud does not necessarily create a barrier to navigation, ports should look for more advanced management strategies that allow these vessels to pass safely through these areas, without the need for continuous dredging.

Using innovative methods such as mechanical shredding of mud flocs, ports can manage the sediment by delaying its consolidation, keeping it in a navigable state. These practices, applied to maintain nautical depth, ensure that larger vessels can continue to use these waterways safely without escalating dredging operations – saving money, reducing greenhouse gas emissions (GHGs) and protecting the marine environment.

Why survey more to dredge less?

Whilst it can be an expensive tool, advanced surveying methods can optimise the need for operations including dredging. This means operations are likely to be more efficient and cost-effective.

Fluid mud, which has densities between 1.1 to 1.35 kg/L, can exist in a state where it appears to be problematic for vessel passage. However, new technologies, such as Stema Systems Rheotune and its SILAS software used in private U.S. facilities, allow ports to measure the mud’s yield stress as well as its density, as well as its yield stress – giving a clearer picture of whether ships can safely navigate through, without any loss of control or damage. This approach helps in defining the nautical bottom, which is the critical depth where a ship’s keel can interact with the sediment without compromising safety.

Ports such as Harwich Haven, Emden, Hamburg, Rotterdam and Antwerp have already started to embrace sophisticated surveying techniques to assess the properties of fluid mud locally, and are already seeing the long-term benefits of this process. These surveys allow the teams to determine the true navigable depth, rather than solely relying on traditional sediment removal methods.

Reducing costs, emissions and the environmental impact

Dredging is a labour-intensive, resource-heavy activity that demands considerable financial investment. However, it is a vital process to maintain navigable waterways for marine traffic. In addition to the operational costs of dredging, there is an ethical responsibility across the sector to consider the impact that managing waterways has on our marine ecosystems.

With this in mind, it is important to manage mud to prevent the rapid consolidation, allowing ports to reduce the frequency and duration of dredging, while maintaining clear waterways. To do this, a port must invest in understanding their fluid mud dynamics to enable the move forward in their goal to achieve sustainable operations and achieve the bonus of reduced maintenance costs.

Part of this should also include an understanding of how vessels impact the mud that it is sailing through. The nautical depth could be different for different types of vessels.

The more we know about the whole maritime environment – vessels, mud rheology and the hydrographic characteristics of the location and their interactions – in which we are managing, the more educated we can be about the decisions and dredging campaigns we are planning. This means, when we need to plan maintenance dredging campaigns, we can do it as convenient times in our calendar, as well as using the most suitable tools and resources, and they will be planned for the right duration and with the least impact towards the marine environment.

Tiamat as an alternative solution

We are always looking for innovation across our industry and it is promising to know there are solutions available. Companies should be actively looking for solutions such as Tiamat to manage challenging sediments issues.

While Tiamat represents a promising new technology, it is also worth understanding that it will be deployed as a complimentary solution, joined by other methods of dredging such at TSHDs and ploughs, as part of a program of navigable mud management, as is the case in Harwich. ?

When considering alternative solutions, surveying and understanding the dynamics of your sediments at a more granular level allows for smarter, more targeted interventions. Whether this is by using advanced software or introducing new dredging tools, the goal remains the same – to reduce the amount of sediment that needs to be dredged, and the frequency and duration of the dredging, thereby decreasing operational costs and the environmental impact.

The Future of waterway management

Ports around the world are already experiencing the benefits of engaging with the idea of defining and effectively managing navigable mud as part of their strategy. Ports including Harwich Haven, Hamburg, Rotterdam and Emden are proving that surveying more to dredge less is a viable strategy, and as a result, they are leading the movement towards more sustainable and cost-efficient port management.

Regular surveying to correctly identify the dept of navigable mud is the key to the journey to smarter, greener and more cost-effective waterway management. By focusing on managing and understanding mud, rather than removing it, ports can accommodate larger vessels, protect ecosystems and reduce their carbon footprint. It is also an opportunity for innovation and sustainability in the maritime industry.

To find out more about Tiamat and the latest news from Haven Dredging, please visit www.havendredging.com/latest-news.

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