A greener ‘dredging with nature’ invention has saved millions of pounds and cut emissions at Harwich Haven by combining the use of tides and currents with new technology.
Sustainable and non-invasive, the new machine will change maintenance dredging of the seabed or riverbed while delivering huge economic, social and environmental benefits, its owners say.
Harwich Haven Authority (HHA), a trust port, was spending 25% of its revenue on traditional dredging, with regular 16-mile trips offshore to its sediment disposal site.
After half an hour’s dredging, four hours was then spent going out to the disposal site.
Jake Storey, HHA chief financial officer and Haven Dredging executive director, said: “It wasn’t great productivity and then there were all the emissions caused by going so far offshore.”
A conversation with harbour engineer Jim Warner about how CO2 emissions and costs could be cut during operations prompted him to voice an idea for a hydrodynamic maintenance dredging solution.
This conversation developed into Tiamat, an easy-to-deploy adaptable agitation dredging solution that has been working at Harwich since April 2023 as part of its dredging strategy.
It has more than 120 patents across the world and is ideal technology for authorities and harbour engineers responsible for muddy ports.
Already piloted in Rotterdam, Hamburg and German ports, the technology offers huge potential for the right profile of port, Jake said.
Its invention launched a commercial arm of the authority, Haven Dredging – a wholly owned subsidiary of the HHA, which has responsibility for the basic dredging of the haven.
Haven Dredging is a compelling offer for muddy and silty ports and waterways across the world. It also has potential for use in offshore renewables to keep seabed cable trenches free of sediment between trenching and cable laying.
“Tiamat is a tool,” said Jake. “It needs to be the right type of port to benefit from Tiamat. It is very good at moving silt and light sediment along and making it very weak.
“If you leave silt, it gets consolidated, and you can’t sail through it. Tiamat is ideal for ports like ours, and Hamburg, Antwerp, Rotterdam and any muddy ports.
“This is not about replacing existing technology; it is about supplementing it. We are not a dredging operator. We are a dredging technology supplier.”
The standard Tiamat is a frame carrying two pumps to inject water into the sediment overlying the bed of the harbour, and a third pump to extract diluted silt, pump it up and release it into the water column.
Mounted on a small workboat with an A frame, Tiamat is lowered into the water depth needed then, using the power of the tide and currents, promotes self-replenishment in the estuarian system by natural re-suspension of the sediment, described as “dredging with nature” by Haven Dredging.
The sediment returns to the water column at the appropriate depth, and there has been no evidence of water quality being impacted.
Jake said that using a small workboat solved capacity and resource constraints in the traditional dredging market, cutting fuel consumption, harmful emissions and time, depending on the location of the disposal site.
Jake said: “As a trust port and a port authority, we wanted Tiamat to be accepted as dredging technology that sits alongside existing technology and have those attributes. It is going to supplement what exists out there in a positive manner and with the advantage that it reduces carbon footprints.
“It saves us easily about 50% of what it would cost with traditional methods. We have saved millions by using Tiamat. If we hadn’t been going 16 miles offshore to our disposal site, we might not have invested in it.”
After the first conversation in 2019, it was trialled in March 2020, with independent environmental impact assessments conducted by leading experts in dredging practices, Royal Haskoning and HR Wallingford, and independent reviews by the Environmental Agency and Natural England.
“There is a concern that sediment doesn’t get washed into the Orwell and Stour and we are looking to use Tiamat there rather than the current solution of taking sediment in trailers up to the mud flats and overflowing,” said Jake.
Last October the US Corps of Engineers visited for a technical assessment, including using Tiamat for reservoirs. Haven Dredging is also in discussions about trialling in Europe.
“In the US we are speaking with big dredging companies and hopefully we will get some traction,” said Jake.
Other ideas are being explored to reduce HHA’s environmental footprint with commercial value in the UK and around the world, and Jim Warner has already come up with another invention.
“Because the Stour and Orwell come into the basin, they create eddies in the harbour where sediment can get trapped, however, Tiamat weakens the sediment. Jim has come up with an invention to move soft material that build up in the harbour to the faster flowing areas of the harbour,” explained Jake.
Tiamat also has a huge potential for offshore renewables as well as ports.
“One of the advantages of Tiamat is that it can be deployed with a standard vessel and can be dismantled and put into a container and be sent anywhere and then reassembled for use in ports, harbour or offshore.”
To explore its potential in offshore renewables, HHA took part in ORE Catapult’s technology accelerator programme, Launch Academy, to help form a value proposition to access the market.
“We held a mirror up to what we had done, and it showed us how it could work in the offshore sector,” said Jake. “We don’t have an entry point, so we identified ways into that sector, and decided a way in was through the big dredging companies working in offshore renewables.”
Its main potential in offshore wind is to keep seabed trenches free of sediment between trenching and cable laying, especially if there are delays.
Sediment collecting in trenches would obstruct an efficient laying process. Tiamat – a modular transportable system that can be mobilised and deployed quickly – would deliver “relatively cheap support” to prevent delays on multi-billion-pound projects.
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