The day after.
The 500 KG bomb was found right next to the Glauburgbunker, an world war 2 civil defence bunker that is currently demolished to build an appartment building. The fuse of the bomb was damaged but still active and anything, movement, even a temerature change could have set the bomb off, so it was decidet to detonate the bomb controled with a charge of 4.5 KG of explosiveds. The bomb was covered with 70 truckloads of sand, 30 tons each, to direct the blast underground, which was possible because there are no subway tunnels, utillity lines or other structures underneath. This was sucessfull, as no damage was caused by the blast, it still left a 3 meter deep and 10 Meter wide crater.