SeaTerra Clears UXO from DolWin3 Cable Route

Target investigation inside the safety zone of the converter platform DolWin alpha with 2 dive support vessels.Source: SeaTerra

SeaTerra GmbH has completed investigation of 278 objects and removal of eight unexploded ordnance (UXO) targets from the DolWin3 cable route in the German part of the North Sea.

Commissioned by the transmission system operator TenneT, SeaTerra GmbH recently examined and cleared numerous metal objects from the future DolWin3 cable route between Emden and the seaward converter platform DolWin Alpha.

The DolWin3 project establishes a 900MW direct current (DC) grid connection for offshore wind farms in the south-western part of the German North Sea, namely offshore wind farms Merkur and Borkum Riffgrund 2.

As part of the required ordnance investigation, eight major UXOs were identified along the DolWin3 route. Three grenades and a partly destroyed mine were classified as transportable and salvaged from the seabed. Two of them were handed over to the Ordnance Disposal Authority, two shells – each weighing 400 kg – were moved to a sandbank near Borkum, where they were demolished by members of the Ordnance Disposal Authority.

 Recovered 400 kg grenades on board “SeaScan1”. Source: SeaTerra
Recovered 400 kg grenades on board “SeaScan1”. Source: SeaTerra

The non-transportable ordnance which included four sea mines was demolished in situ by explosives specialists and ordnance divers of SeaTerra GmbH. All demolitions were prepared and designed in cooperation with the responsible regulators. Marine mammals were protected by scaring devices and a “Big Bubble Curtain” to minimize noise.

The ordnance clearance operations were preceded by geophysical surveys. Approximately 700 ha of the seabed was surveyed with high-resolution magnetometers and Side Scan Sonar, Multibeam Echo Sounder and Sub-bottom Profiler systems.

Subsequent data interpretation led to the identification of hundreds of anomalies. SeaTerra identified 278 potentially dangerous objects and investigated and cleared them with the help of remote-controlled devices, cranes and ordnance divers.

A special feature was the geophysical investigation within the 500 metre safety zone of the existing converter platform DolWin Alpha. The work was carried out under the highest safety requirements and only under ideal weather conditions.

The handover of the last shell on 18 August to the responsible Ordnance Disposal Authority completed the ordnance clearance works along the DolWin3 cable route.

Share this article

Follow Offshore Wind


<< Jan 2018 >>
1 2 3 4 5 6 7
8 9 10 11 12 13 14
15 16 17 18 19 20 21
22 23 24 25 26 27 28
29 30 31 1 2 3 4

Maintenance and Pumps & Valves 2018

Pumps & Valves focuses on industrial pumps, (control) valves, seals, filters, filtration solutions, processing equipment, (pipe) pipes…

read more >

Asia Offshore Wind Day 2018

The event will bring together senior executives active in the offshore wind industry in Asia…

read more >

6th Int’l Wind Energy Expo & Conference WIND EXPO 2018

From components, devices, various services to wind turbines…a wide range of cutting-edge products and technologies will be exhibited…

read more >

SNS2018 – The Southern North Sea Conference & Exhibition

EEEGR’s flagship Southern North Sea conference is the most important event for the energy sector in the East of England…

read more >


Offshore Wind jobs in Taiwan at New Power Partners

New Power Partners offers global management and support services to the Offshore Wind Industry within development, planning and construction activities ...


Looking to fill a job opening?

By advertising your job here, on the homepage of, you’ll reach countless professionals in the sector. For more information, click below...


Looking to fill a job opening?

By advertising your job here, on the homepage of, you’ll reach countless professionals in the sector. For more information, click below...