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How to Ensure an Environmentally Friendly Practice in Dredging

03 June 2019

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Throughout the world, dredging is helping to make harbors usable again through the deepening of navigation channels and berthing areas to ensure the safe passage of boats and ships as well as uncovering archaeological artefacts and returning habitats to their original state. Yet, there seems to be two standout ways to conduct dredging projects: the risky way and the environmentally conscious way.  We discuss both options below:


The risky way

The risky way of dredging is often seen as the easy way as well.  Materials are dredged to maintain the waterways and the dredged spoils are returned unprocessed to the water body further out at sea. This isn’t risky if the materials are simply made up of soil, sock, shell material and sand. However, if the spoils are contaminated, or even suspected to be contaminated, they should be treated before being returned to any water body. Otherwise the problem is being moved around, rather than solved. It is rare that there is no contamination present in dredged materials- in harbors oil spills can cause contamination of total petroleum hydrocarbons (TPH), while unfortunately harbors, lakes and rivers are sometimes used by the public as a dumping ground too.  There are many other ways the dredged materials could have become contaminated- it’s a sad reality, but one that we must face up to.


The environmentally conscious way

The environmental way takes the destination of the returning spoils in mind- whether the materials will go back to sea or elsewhere, it’s important that they are safe and won’t damage the ecosystem or environment. By processing dredged material, contamination in the form of heavy metals, hydrocarbons, man-made chemicals and other harmful constituents, is removed which could otherwise be harmful to the receiving ecosystem.  What’s more, this method is less risky for the dredging contractor, who could be liable if the returned spoils are found to be contaminated and as a result are affecting coral reefs, fish nurseries and other marine wildlife.

If it’s not appropriate to return dredge spoils to the ocean, another environmentally friendly option exists.  By processing the material, valuable resources such as sand and stone can be extracted and reused in low-grade construction applications, reducing the reliance on virgin resources.


Although the benefits of dredging are numerous, controversy remains around the subject, and to prove the benefits, we must work to ensure the most environmentally friendly practice possible.  If that happens, waterways can be managed and made safe, contamination can be removed from the water body and the receiving ecosystem won’t be polluted- everyone wins.

Learn more about CDEnviro’s role with dredging material processing or get in touch at


CDEnviro are exhibiting at the Western Dredging Association (WEDA) 4th-7th June in Chicago, Illinois. If you’re attending, get in touch to book an appointment to discuss a solution for your dredged materials.

We’d love to see you there!



Dredging processes Dredged spoils Dredging Environmental Remediation