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  • Writer's pictureTallulah

Why are canals dredged?

Canal dredging plays a crucial role in maintaining the navigability and environmental health of waterways across the UK. The process involves the removal of debris, sediment, and unwanted substances to ensure safe passage for vessels, improved water quality and the protection of the vital canal ecosystems.

There are several reasons why canal dredging is so important, including:

  • Safe navigation: By removing sediment and debris from canals it helps to maintain clear channels and support the water depth needed for boats, barges, and other traffic so they can navigate canals with ease. There are many canals throughout the UK which have both heavy commercial and leisure traffic, with these channels being a priority for regular dredging maintenance.

  • Flood prevention: Without regular dredging canals often struggle with waterway blockages that can lead to flooding. By removing these blockages, the water capacity of canals will increase and the likelihood of flooding during periods of heavy rainfall will reduce.

  • Preserving the ecosystems: Canal dredging plays a vital role in preserving the delicate waterway balance, with harmful pollutants, organic sediments and unwanted debris removed to improve water quality and to create an environment where important plant and animal species are able to thrive.

How do you dredge a canal?

So, what are canal dredging methods? The exact methods vary depending on the objectives of the project, the scale, and the condition of the canal, with the most common methods in the UK being:

  • Mechanical dredging – This method involves the use of excavators, dredgers, and other specialist machinery to physically remove the sediment and debris from the canal bed. These machines can be used together to lift the unwanted material, which can then be transported via barges or trucks for disposal or treatment for use elsewhere.

  • Grab dredging – In a similar way to mechanical dredging, grab dredging involves the use of large mechanical buckets which are attached to cranes, excavators, and specially adapted barges to remove materials from the canal bed. In difficult to reach areas or where there is a heavy buildup, this is often the method of choice.

  • Hydraulic dredging – Although not as common, there are times when powerful pumps are used to remove sediment and debris from the canal bed. The jets are directed at the built-up areas to suspend the debris, which is then collected and transported to disposal or treatment centres.

How often are canals dredged?

Although canals will need dredging to maintain water depths and navigability, the frequency of canal dredging depends on several factors, including the canal itself, its usage, the level of sediment build up and any environmental conditions. This means that the intervals between dredging can vary from every few months to every few years, with a professional contracting team able to advise on this depending on the buildup and canal waterway requirements.

The canals which have high levels of traffic and those which are located in areas with a high level of sediment disposition will naturally require regular dredging. This is often referred to as maintenance dredging, as the removal of debris and sediment is completed on a routine basis. There are also times when dredging is required for a specific purpose, such as when a canal needs to be widened or deepened for a project, or when dredging has not been completed for a significant period of time.

Why can canal dredging be bad?

With any canal dredging method it is essential to hire an experienced team as it important to minimise any potential risks to the environment. For example, dredging can temporarily disrupt the habitats within the canal channel, however experienced contractors will carefully plan and implement solutions to reduce these impacts, such as avoiding sensitive sites and breeding seasons. If careful planning is not in place the habitats, fish, invertebrates, and other organisms within the canal could all be disrupted.

In addition, the sediment removed needs to be handled and disposed of correctly, and with strict regulations in place across the UK, it is important to hire contractors that will understand these rules and use designated treatment and disposal sites. Here at The Rothen Group, we work in collaboration with organisations such as the Canal & River Trust, the Environment Agency, and many private owners to deliver essential and reliable dredging services, and we guarantee to always plan projects in accordance with the environmental requirements.

What happens to dredged materials?

There are designated treatment and disposal sites which are designed to ensure that environmental sustainability is upheld through careful management and treatment of the waste material. In general, the most popular disposal options here in the UK are:

  • The reuse of material – Dredged materials with low contamination levels can be reused in beneficial ways, such as within construction projects, coastal defences, habitat creation and agriculture.

  • Disposal – If materials are contaminated or cannot be reused, typically they will be transported to a containment area or a licensed disposal facility. These sites follow strict UK regulations and are required to uphold environmental standards that prevent any possible contamination of the surrounding areas.

  • Sediment treatment – There are situations where pollutants and contaminants can be removed from sediment before disposal or reuse. This involves steps such as the physical separation of material, dewatering and stabilisation.

The Rothen Group – A leading provider of canal dredging services

We are proud to specialise in the maintenance and management of inland waterways throughout the UK, and through our proactive and knowledge-based approach combined with our professional equipment, we are able to undertake canal dredging projects of every scale.

Our versatile fleet includes floating dredgers, modular pontoons, and long-reach excavators, so whether you require spot dredging near a bridge or regular canal dredging services, we can assist. To discuss your project in more detail or to find out more about our wide range of services, please contact our team today.

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