Here's a photo of the offending WW2 bomb.
In Hamburg-Finkenwerder: Bagger saugt Fliegerbombe aus der Elbe an | MOPO.de
I remember an interview with the UXB men of Hamburg harbour ( a specialised team due to the ongoing finds from the WW2) where the question was asked, 'Did they feel fear ?'....Very cooly they explained that the human reaction to an unfortunate explosion was such that they would be blown so many ways asunder before they would realise, therefore they wouldn't know, therefore there was no reason to worry about it happening....Very brave chaps in my book.