The ScaleZ command scales most objects in just the Z direction (the elevation), without changing the horizontal location.
Type ScaleZ at the command line, and select the items you wish to scale. When you have finished selecting items, right-click. Or, you may select items first, then run the ScaleZ command. You will then be prompted for a scale factor. Alternatively, instead of entering a scale factor, you may type "B" to specify a new Base Elevation, or "P" to select a predefined scale factor from a list of common scale factors.
This command does not work on all objects, but it works on most of them. In particular, this command will not work on Survey Points (Cogo Points inserted from a Survey Database) unless those points are unlocked in the drawing.
Scales Civil-3D Cogo Points horizontally without applying a datum adjustment to the points.
Scales most objects in just the XY direction, maintaining the original elevation.