Civil 3D Boundary.
Ever have an Existing ground Surface and you create a Corridor and want to remove the Corridor shape from the existing ground. In most cases the answer is yes and likely we all do at some point. There is a feature added to Civil 3D 2013 that allows users to use Surfaces to created Boundaries such as a Corridor Surface boundary.
1.) you will want to make a copy of EG and call it something else (I use FG in most cases for finished ground)
2.) Under the Surface you want to add the Boundary to (Copy of EC now called FG) Expand the Surface in the Tool space.
3.) Expand Definition under the Surface Name
4.) Right click on top of Boundaries
5.) Select Add
6.) The Boundary Dialog box opens up. Select Hide from the Boundary List.
8.) The surface Object is not an option at this point. In the Drawing Windows right click and select surface.
9.) Now that Surface has been selected you can select the Corridor Surface.
10.) The Boundary command completes and there is now a Hide Boundary that is identical to the Surface you selected