What does the US Army Corps of Engineers say about Tiamat?

The US Army Corps of Engineers (USACE) recently published its findings on the potential use of Tiamat in America.

With stringent regulations in place, dredging activities that take place in America must follow strict rules and where possible, support the wider environmental goals. Following the USACE research, we are delighted that it highlights some key opportunities, with regards to the versatility and effectiveness of the Tiamat in various dredging applications across the continent.

Particularly for dredging operations on the US West Coast, where state air emission regulations limit the use of current Trailing Suction Hopper Dredgers (TSHDs), Tiamat was commended for reducing greenhouse gas (GHGs) – one of the biggest polluters from traditional dredging. The report called out a 2022 study by Port and Coastal Solutions which revealed Tiamat’s impressive environmental performance, emitting five times less CO2 over a 24-hour period compared to traditional TSHDs. During the trial, Tiamat and M/V Barney showcased significantly lower fuel usage, averaging approximately 86.67 L/hr (22.89 gal/hr) and 1,040 L/day (274.68 gal/day) during standard 12-hour shifts.

In contrast, similar-sized US Hopper Dredgers typically consume between 4,000-6,000 gallons of fuel daily! This clearly highlights the opportunity for Tiamat to considerably reduce the environmental pollution in the US.

Similarly, as environmental concerns grow, this includes the impact of underwater noise on aquatic organisms, especially marine mammals. At Haven Dredging, we remain committed to understanding and mitigating these effects to ensure our dredging operations have little to no impact on marine life. The USACE report also looked at a recent study with HR Wallingford which compared the underwater noise generated by Tiamat (towed by the Multicat, Bella) with that of a traditional TSHD, of 3,500 cubic meters.

Over a six-day period, the analysis revealed that Tiamat and the Bella workboat combination produce sound pressure levels approximately 15 dB lower than the TSHD. In addition, the sound source levels associated with each dredger were approximately 170 dB for the Tiamat and 185 dB for the TSHD.

While Tiamat demonstrates a significant noise reduction compared to traditional TSHDs, it’s essential to note that the study found Tiamat’s noise levels within the range associated with behavioural disturbance (120-160 dB). However, these levels still remain below the background noise experienced during normal shipping activities in Harwich Harbour.

A new opportunity following this report is as a cost-effective solution for marsh and wetland restoration, allowing natural sediment settling without disrupting existing flora and fauna. Often, many US reservoirs face significant siltation issues, impacting dam intake towers – and traditional dredging methods struggle with the limited acreage for upland placement and the large quantities of sediment involved.

However, thanks to Tiamat’s advanced agitation capabilities, it offers a solution to this problem. By fluidising the sediment, Tiamat can enable the material to bypass the dam and move downstream naturally, aligning with existing outflows. This method not only addresses the sedimentation problem effectively, but also minimises the environmental disruption and improves reservoir management.

Finally, another highlight is Tiamat’s ability to improve navigability, by altering the density and shear stress of fluid mud left behind after dredging. Particularly in open water, Tiamat is believed to able suitable to support strong, natural flows and where there are currently long distance disposal sites – indicating yet another benefit for US shipping channels.

These findings highlight Haven Dredging’s commitment to innovation and sustainable practices in dredging operations. We’re excited about the potential of the Tiamat to address diverse environmental challenges across the world and to continue to Dredge with Nature.

To read the full USACE report, please request a copy here: www.havendredging.com/research-and-performance.