Since 1912, Boskalis Hirdes has met the challenges and tasks of hydraulic engineering in the onshore and offshore sector with a high level of discipline and engineering performance - since 1978 also with its own division for explosive ordnance disposal. When Boskalis Hirdes GmbH deepened the inland port of Heligoland, various explosive devices from World War II were found. To ensure the safety of the on-site staff, protective measures had to be taken as soon as possible. Due to the adverse circumstances, MMA (111) and the MAG welding process with filler wire (136) were used to show their strengths in this environment.