The tests were completed on an innovative hydrodynamic dredging solution, Tiamat, by the environmental hydraulics consultancy HR Wallingford, a leading specialist in the modeling and measurement of marine noise, in Harwich Harbor, Essex, UK, in April and May 2023.
The comprehensive research compared sound pressure levels (SPLs) of Tiamat from Haven Dredging against the 3,500 cubic meters Trailing Suction Hopper Dredger (TSHD); Tiamat was shown to be 15 decibels quieter, on average.
While being pulled by a small workboat, the noise level of Tiamat was around 170 decibels (dB), while the TSHD was around 185 dB. The US National Oceanic and Atmospheric Administration (NOAA) suggests approximate sound pressure level (SPL) thresholds are 180 dB for whales and 190 dB for seals.
Jake Storey, Executive Director of Haven Dredging, comments on the feedback from the report, saying, “We are committed to working with nature, for nature, and to sustain nature. The results of this study are a testament to the years of research and field testing that have been put into creating Tiamat.
“Tiamat aims to not only build awareness around environmental issues from traditional dredging methods in the port and dredging community but also to provide businesses with the opportunity to choose a more responsible, sustainable, and economical method of dredging.”
The full results are detailed in the 43-page report, Measurements of Tiamat and TSHD Noise Disturbance.
Dr. Thomas Benson from HR Wallingford—who completed the noise study—adds, “Measuring underwater dredger noise within a busy harbor environment presents considerable challenges because of all the other noise generating activities taking place, but the results of this study are clear in that the Tiamat makes a lot less noise compared to more traditional trailer dredgers. This adds to the other benefits of the Tiamat, such as having a low-carbon footprint and being cheaper to run.”
In addition to being quieter, Tiamat provides a cleaner and greener method of maintenance dredging that is easy to deploy, adaptable, and at a lower cost.
Tiamat is designed to be mounted on a small workboat or multi-cat. It features three pumps: two to inject water into the sediment overlying the harbor bed and a third pump to extract diluted silt, pump it up, and release it into the water column. By “Dredging with Nature”, Tiamat encourages self-replenishment of sediment through the natural re-suspension in the marine environment. By harnessing the power of the tide and currents and only needing a small workboat, Tiamat can reduce costs by up to 67% compared to traditional maintenance dredging methods.
Haven Dredging, the commercial arm and wholly owned subsidiary of Harwich Haven Authority, launched in April 2023.
At Harwich Haven Authority, the organization is already reaping Tiamat’s rewards. Thanks to the success of Tiamat trials, the organization has included Tiamat in its dredging strategy, thereby reducing costs by two-thirds and greenhouse gases (GHGs) from maintenance dredging by up to 35%.
For more information about Haven Dredging, visit: www.havendredging.com
