piler10,
Do the terms 'deep' and 'longwall' go together? If so, would you expect any settlement?
You might try searching for the term 'subsidence' as one of your keywords.
While not a longwall operation, I seem to recall hearing about subsidence in the town of Flin Flon, Manitoba (Canada) when I was there a number of years ago. The mine underneath the town was creating building settlement issues (not sure if it affected the mill, etc.).
Cheers,
CanuckMiner