QUOTE(Hack @ Nov 20 2009, 6:51 AM)
If you can't view the current yard (too old), you could use Google Earth to see how other yards are laid out.
As for generating new tiles, did you first generate them using the RGE? IIRC, they have to be in place before generating any DEM.
Instead, I delete those tiles and generate them again, which will solve the problem as well as adding the terain again.