I am living 4 km away from Siegburg. The ammonition factories in Siegburg closed already after WWI, the ones in Troisdorf are still working
The next POW camp to Siegburg was in Rösrath: Stalag VI G Arb-Kdo 281. Concededly this camp was freed not on 8 but on 12 April 1945, by taskforce Delnore of the 46th Tank Battalion, but German sources say that the German soldiers left the camp alone a few days before the Americans reached it. It was not only a camp for prisoners of war but also for foreign forced laborers. The next camps were in Bonn, about 20 km away and taken already on 8 March, and in Bergisch Gladbach which was taken on 13 April. Today there is a memorial stone and a cemetery for prisoners of war and forced laborers, and kind of child care center, where at least one of the old barracks is still in new use.
Translation of the memorial stone:
This was the POW camp Hoffnungsthal in the second world war, where people of different nationalities were victims of hunger, disease and violence. Their sufferings and their death urge for peace.
Christoph