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Is the perception of dredging all wrong?

17 January 2020

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With environmental changes and increasing demands on waterways dredging has become a common practice throughout the world. For many years people have cited the definition of dredging is ‘to damage’ but when it is also ‘an act of cleaning or clearing[1] our waterways’ we must examine the negative perception of dredging and ask if the critics are mistaken.

People often state that dredging has a negative effect on the environment, especially to marine life and how it can alter the environment. However, when effectively managed many maintain dredging can have a positive impact on our environment by supporting environmental remediation, flood control, maintaining waterways and result in the placement of better infrastructure.

Are we wrong to dredge? 

Many activists and campaigners claim dredging causes major damage to our ecosystem because large parts of the seabed are removed and dumped elsewhere, some of which are contaminated. Marine environments are sensitive and complex.  Several claims have been made that dredging causes the release of toxic chemicals which harms marine life, damages marine ecosystems and that bio-accumulation of toxins ends up in our food chain. It is reported that the full impact dredging has on fish is yet to be fully evaluated but research suggests dredging related stressors have been found to have a negative impact on the marine environment[2]. Many argue it can be the noise which has the biggest impact in upsetting marine life while others maintain it is the replacement of dredged sediment, especially around delicate areas such as coral reefs and fish roe[3].

For many years dredged sediment was not effectively managed meaning contaminated sediment was being sent to landfill. However, in recent years most developed countries have introduced strict federal and government regulations for dredging and dealing with contaminated waste. Effective equipment solutions can remove contaminants from dredged materials as well as extracting recoverable materials which results in a mass reduction of sediment disposal.

The impact if we do not dredge

If we were to stop dredging it would have huge impacts upon our waterways and the land that surrounds them. Dredging has been crucial in developing pathways for the global commercial shipping industry and maintaining the width and depth of waterways to enable the safe passage of vessels- bearing in mind the ships carrying potentially harmful materials such as raw materials and oil. We must ensure we do all we can to maintain waterways and reduce any accident risk. Without adequate depths and widths, the commercial and leisure shipping industries would struggle to find viable pathways. For construction projects near waterways, underwater excavation is essential for the development and maintenance of docks, piers, bridges and underwater tunnels. Without dredging for this purpose, many countries would find it difficult to develop their infrastructure.

Dredging also aids land reclamation projects where dredged sediment is used for land building projects. The reclamation of materials which were previously discarded in our waterways is another huge benefit of dredging. Materials left to rot can now be recovered to help sustain a circular economy and generate new revenue streams. Dredging can also allow contaminated waterways to be cleaned from historical industrial waste which will help the waterways thrive again and provide eutrophication from water bodies.

A balance must be maintained

We must be mindful that our most delicate marine eco-systems need to be protected, especially those like the Great Barrier Reef where dredging has been a huge topic of debate. Getting the correct balance is key and companies must accept the responsibility placed upon them to improve local infrastructure while at the same time following procedures that will protect the delicate marine environment around us.

Leading dredging companies have shown that with investment in new solutions, they can greatly minimise disruption more than ever before. They are often seen to work with local government to ensure the correct type of dredging is carried out and that any damage risks are kept to a minimum. Investment in equipment is reclaiming recoverable materials, removing historical contamination and protecting the environment which are all key in creating a circular economy.

For more information on CDEnviro solutions for treating dredged materials, visit our Solutions Pages or get in touch at info@cdenviro.com.

[1] https://dredgeyard.com/news/dredging-the-environment/ last accessed 03/01/2020

[2]https://onlinelibrary.wiley.com/doi/pdf/10.1111/faf.12218 last accessed 03/01/2020

[3]https://doi.org/10.1093/icesjms/fsu187 last accessed 10/01/2020

Dredging processes Dredging Circular Economy