Redefining dredging: Tiamat versus traditional dredging methods
You may have heard that Tiamat offers port authorities and dredging companies a cleaner and greener method of maintenance dredging. One that is easy to deploy, adaptable and at a lower cost. But what are the differences between Tiamat and traditional dredging methods?
Tiamat is a hydrodynamic dredger, that harnesses the power of the tide and currents, promoting self-replenishment in the estuarian system through the natural re-suspension of sediment.
The standard Tiamat has three pumps, two of which are used to inject water into the sediment overlying the bed of the harbour, whilst the third pump extracts the diluted sediment and pumps it up a flume, where it is released into the water column. Sediment is naturally redistributed in the ecosystem, using the tide and the current.
Tiamat offers many benefits over traditional dredging methods, such as Trailing Suction Hopper Dredging (TSHD):
- Lower greenhouse gas emissions of up to 90%
- Cost reductions of up to 50%
- Works with small boats of 25-27 metres
- Greater adaptability (Smaller, larger, move by container)
- Time and fuel savings
- Dredging with Nature
- Commercial opportunities.
Our table below compares the dredging methods of Tiamat and TSHDs to show how they differ:
| Tiamat | Trailing Suction Hopper Dredgers | |
| What is it? | Tiamat is designed to be towed behind a relatively small vessel, such as workboat or multi-cat with an A frame. It features three pumps, two to inject water into the harbour bed sediment, and one to extract diluted silt, pump it up and release into the water column. | Self-propelled dredger ships with hoppers, which are storage areas in the hull for keeping dredged material |
| What does it do? | Tiamat pumps sediment from the harbour bed or seabed using a suction pump. This system of dredging with nature brings major environmental and cost-saving benefits. | Fill their hoppers by sucking material from the seabed using a trailing suction head fitted to pipes that trail over the harbour bed |
| Main point of difference | Tiamat pumps the sediment into the mid-water column where it is discharged. This means the Tiamat can dredge continuously without needing to sail to an offshore placement site. It also releases sediment into the estuarine flow. | Sediment is pumped onto the dredger ship where it is stored in a large hopper. Once the hopper is full, the TSHD sails to a designated offshore disposal site and the hopper doors are opened to place the sediment. |
| Disposal site needed? | No trips to the disposal site mean lower greenhouse gas emissions by up to 90% and cost savings of up to 35%.
| Needs to travel to and from the disposal site to offload sediment. |
| Fuel savings | By not needing to travel to a disposal site multiple times a day, Tiamat saves valuable time, as well as reducing fuel costs and emissions.
| Have to budget for fuel to and from the disposal site. The trips also produce CO2 emissions. |
| Production | Monitoring undertaken at the Port of Felixstowe has estimated that using Tiamat has a daily production rate of 23,500 m3/day (in-situ volume). These production rates are based on Tiamat operating continuously for 12 hours per day. | This is comparable to the daily production rate of a small to medium TSHD (hopper size of around 5, 000 to 9,000 m3). The figures are based on the TSHD operating for 24 hours per day with dredging occurring for 35% of the time, combined with sailing to and from the disposal site occurring for 65% of the time.
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| Size | Our standard Tiamat operates on small boats of 25-27 metres, making it cheaper to operate, more environmentally sustainable and flexible in approach. Also, we have an XXL version that would require a 30m+ workboat | TSHDs come in various sizes, but large suction dredger ships can have hopper capacities of over 45,000 cubic metres. |
| Sediment distribution | Tiamat pumps sediment from the seabed using a suction pump. Tiamat only pumps the sediment into the mid-water column where it is discharged. This means that the dredger can dredge continuously without needing to sail to an offshore placement site. It also means sediment is released into the estuarine system, through the natural re-suspension of sediment through “dredging with nature”. | TSHD suction dredger ships also pump sediment from the seabed using a suction pump. The TSHD pumps sediment onto the vessel where it is stored in a large hopper. Once full, the TSHD sails to a designated offshore disposal site and the hopper doors are opened to place the sediment, using a considerable amount of time and energy. |
Here are some further differences between Tiamat and other traditional dredging methods.
Side casting
Tiamat uses a suction pump to take the sediment up from the bed. With side casting, the sediment can be pumped to the surface and then discharged through an elevated discharge boom over the side of the dredge vessel into the air before reaching the water’s surface. Tiamat pumps the sediment into the mid-water column where it is discharged, meaning the sediment is not pumped above the water surface, and not exposed to the air. The Tiamat does this without the need of an expensive TSHD nor creating large plumes or turbidity.
Bed levelling
Tiamat looks similar to a bed levelling bar and both can be operated by similar vessels. However, a bed levelling bar does not have pumps, meaning it is only able to redistribute bed sediment, so only high spots can be removed or sediment from high sedimentation areas moved away. Tiamat includes pumps to help dilute and mobilise the bed sediment and to pump it into the mid-water column, meaning it can remove sediment from the bed rather than just redistributing it as a bed leveller does.
Water Injection Dredging (WID)
WID involves injecting water into the sea, or riverbed sediment, to create a density current which flows due to gravity. Ideally, the seabed must slope away from the dredging area; so, using WID in the deepest part of a channel or port can be problematic. Tiamat also injects water into the bed sediment to dilute and help mobilise it, but Tiamat has a suction pump which extracts the diluted bed sediment up a pipe where it is released into the mid-water column and transported away by tidal currents.
Adaptability
Tiamat can be adapted (bigger, smaller) for projects where traditional methods would be inaccessible or too costly.
If you would like to learn more about how Tiamat is redefining dredging, contact us for more information.
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