Understanding the effects of dredging on the marine environment

Harwich Haven Authority (HHA) is a Trust Port in the UK, founded in 1863 by the UK parliament. One its main responsibilities is the management and maintenance dredging of the five ports that make up the Harwich Haven.

Following robust trials of a new, hydrodynamic maintenance dredging solution, Haven Dredging was established to commercialise Tiamat in 2023.

Tiamat offers port authorities and dredging companies a cleaner and greener method of maintenance dredging in the marine environment, that is easy to deploy, adaptable and at a lower cost.

Harnessing the power of the tide and currents, Tiamat is “Dredging with Nature” by encouraging self-replenishment of sediment through the natural re-suspension in the marine environment. As the sediment is placed back into the water column at the appropriate depth, turbidity and water quality are not impacted.

Three specific ways that Tiamat works with nature, for nature and to sustain nature, is by minimising habitat disturbance, natural sediment redistribution and improving water quality.

Let’s examine each of these benefits to see how Tiamat can make a substantial difference to the marine environment…

Minimising habitat disturbance

Tiamat uses innovative dredging technology to minimise habitat disturbance in the marine environment across ports and harbours worldwide, through precision dredging. Its unique design promotes efficient maintenance dredging while minimising disruption to critical habitats and underwater ecosystems. Wildlife in and around the dredging zone are less impacted because Tiamat shortens the dredging process – by encouraging the sediment to disperse naturally, rather than locating it somewhere else.

Matthew Simpson, Technical Director for HaskoningDHV UK, engineering sustainability consultants that work with Haven Dredging, explains, “The technology works with tidal processes to minimise the loss of fine sediments from the estuarine system, supporting the natural evolution of estuarine habitats, such as mudflats and saltmarsh which host important populations of waterbirds and other species.”

Natural sediment redistribution
Tiamat’s new maintenance dredging solution dilutes the sediment on the seabed and pumps it into the upper levels of the water column so it can be taken away by the tide or current. Unlike other traditional maintenance dredging methods, there is no need to move sediment to a disposal site, often several times a day once extracted, so Tiamat significantly reduces harmful greenhouse gas emissions being released into the marine environment.

In fact, Tiamat’s carbon emissions are up to 90% lower in Harwich Haven than a comparable Trailing Suction Hopper Dredger, which has to travel to a disposal site. This means fewer emissions are released into the atmosphere and the local community – residents, professionals and visitors – avoid disruption, noise, extra traffic and pollution.

A high suspended sediment concentration (SSC) plume forms behind the Tiamat, but it quickly disperses and does not impact the wider area. Where a localised plume could pose a risk to sensitive receptors, the pump rate can be reduced, thus limiting the SSC to the required levels. Thanks to its unique adaptability, port authorities can easily alter the size and power of Tiamat, so it can also be used in locations where conventional dredging methods are either too expensive or inaccessible, such as reservoirs, canals, and small waterways. Here the Tiamat can help to keep the sediment in suspension for longer periods and deposited in the estuarine system if required.

So, if you are concerned about the effect traditional dredging methods are having on the marine environment, contact Haven Dredging and let us know about your needs and see how you can start “Dredging with Nature” with Tiamat, while saving port authorities and dredging companies money and time.