Showing foundation on surface model

[Srana123]

Hi I currently have an existing survey with building footprints shown. I need to make a plan where we demolish the buildings and leave a 10 foot deep hole (to represent the foundation of the building post demo). What would be the best way to do this? I drew a feature line around each building and got the elevation data from the existing data, but I'm not sure what to do next. 

[tcorey · Accepted solution]

Use stepped offset to make a copy of the feature line about 0.01 inside and 10.0 down. Add both the top and bottom feature lines as breaklines.

[chriscowgill7373 · Accepted solution]

is the hole realistic or theoretical?  in other words do you need to account for the dirt falling in or can you just show vertical walls?  If the latter, offset your featureline to the inside 0.001 or so and then drop its elevation to the bottom of the hole.

[Srana123]

Thanks for the solutions, the stepped offset is exactly what I needed

Another question I have, I want to keep this existing surface as it is before the demo and I want to make a new surface which has the existing surface post demo. How can I copy my existing surface into a new surface? I thought it was simply add the point group to the post demo surface but looking at the definition of the existing surface, there seems to be points and breaklines that were added 

[chriscowgill7373 · Accepted solution]

The best way to do this in my opinion is to create a new surface, go Definition-> Edits Right click and select paste surface to paste the existing surface inside of it.  That way if the existing surface changes (get more topo, etc.) the other surface does the same.  Then you can paste your demo surface over that to get a finished overall surface.