Essential Surfaces – EG and FG
Surfaces are essential to just about anything done in Autodesk Civil 3D. Often existing surfaces are created and referenced into design drawings, for grading, corridor creation, etc. Existing surfaces are usually named EG (existing ground) or OG (original ground). 
For the final design drawings, existing surfaces are represented with contours in half-tone so that they can be plotted out as grey lines. Final design surfaces will have bolder contours. The colors of these final or finished ground (FG) contours should be set to print out with proper pen widths in black. 
A variety of other design surfaces derived from corridors or grading objects are also created, and these are usually pasted into one overall final surface.
Final Surface
The final or finished surface is usually named FG (final or finished ground). One workflow is to make a copy of the EG, directly on top of it, and rename the copy to FG (and give it the appropriate styles).
Then by pasting in the appropriate design surfaces into the FG, one derives the final ground!