Beginning in the 10.05.00.30 release, the Create Cut Fill Volumes tool has been enhanced to use featurized meshes in the analysis. It is no longer required to create a terrain model for the proposed rough grade.  The objects in the civil model are compared based on the "Volume Option" in the assigned Feature Definition in order to calculate the cut and fill volumes.

The video below discusses basic cut and fill volumes using the Existing, Design, Subgrade, and None Volume Options.