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  • Writer's pictureTallulah

Why You Shouldn’t Dread Dredging

With over 2,000 miles of canals and rivers in the UK, as well as marinas, lakes, ponds, reservoirs, wetlands and thousands of miles of coastline in need of careful management, keeping these waterways well maintained and clear of debris can be a constant challenge.

A lack of proper care when it comes to such areas can lead to poor water quality and blockages, which in turn can result in biodiversity issues and boat users becoming stuck or stranded. Prioritising regular marine maintenance is therefore key, so by working with specialists who are able to clear waterways correctly, problems can be avoided before they begin.

What is Canal Dredging?

Dredging work clears the sediment and debris along the bottom of a body of water, whether it’s a canal, lake, river or marina. This process helps to manage the effects of climate change through flooding, drought and coastal erosion, as well as helping minimise the impact of urbanisation.

Without carrying out dredging, stretches of water would soon become impassable for canal boats trying to navigate them. Left unchecked, sediment, silt and debris are naturally washed along, which means it can build up along key chokepoints, like river banks, and block access over time.

For organisations using waterways for commercial and construction purposes, this could present operational problems, as failure to make deliveries may have financial implications or mean building projects can’t be completed. Those using the canal network for recreation and pleasure might also find themselves struggling to reach their destination, if certain sections of the network are impassable.

While such scenarios are extremely limiting to boat users, they can also pose a risk to wildlife. For example, sediment coming from the outskirts of cities and industrial areas can often be contaminated with a variety of pollutants. These substances are a threat to plant life, as well as organisms living below the water’s surface, so it is essential these are effectively removed.

Why is waterway dredging necessary?

There are two core reasons for dredging, best described as maintenance dredging and environmental dredging.

In the case of maintenance dredging, this process often focusses on maintaining or increasing the depth of navigation channels to allow the safe passage of boats. The UK is reliant upon its canals and rivers to transport heavy goods, which makes the network hugely important from an economic point of view. Ensuring that routine maintenance dredging projects are planned and carried out is therefore crucial, as vessels require a certain amount of water to float, and a build-up of sediment will interfere with this.

In terms of environmental considerations, canals are unique ecological corridors which provide important habitats for wildlife in both urban and rural areas. Some hold important populations of nationally rare species of insects or plants, so preserving these is essential in protecting biodiversity in the UK. If pollutants are present in waterways, then the sediment in river channels and canals can become contaminated and harmful to these organisms. Removing this has a positive impact on water-dwelling life, creating better fish spawning grounds and generally leading to much healthier waterways.

How is dredging carried out?

A team of marine engineering experts, together with the correct canal dredging equipment, are both essentials when considering how best to tackle dredging. This is to ensure no damage is done to the bed of the canal or river as the excavator drags along the bottom. Canal beds are often sealed with puddling clay to prevent leakage, which has to remain intact for the canal to be functional. Piercing this would lead to further canal repair being needed.

In addition to this, there are also culverts and underground services which must be taken into consideration when carrying out canal maintenance to avoid further waterway repairs. This is another reason why specialist equipment is an absolute necessity. For example, workboats called ‘dredgers’ have been specially designed to handle this process and can take multiple forms. They come in different sizes dependent on the project in question. Sites may have varying levels of access or requirements, so there are a number of versions available.

For situations where operation from the bank or a boat is required, a long reach excavator is available. An excavator on a pontoon can also be booked in cases where steadying stability legs will be useful. As debris must be removed completely, crane or grab barges with clamshell buckets can pick this material straight out of the water. Amphibious diggers also offer an effective way to access and get rid of silt and debris.

What is the cost of dredging a canal?

The cost of dredging depends on a number of factors, making it impossible to provide a one price fits all approach. Factors, such as the complexity of the project, location and site access must all be taken into account – and as these can vary quite significantly, quotations for dredging work are developed on a case-by-case basis.

If you have any further questions about dredging, or would like to know more about the services The Rothen Group can offer, please contact us on 01827 215715, or email

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