How do I "drop" Civil Cells to "dumb" elements?

I created a roundabout using Civil Cells but need to "drop" it to "dumb" elements to create an exhibit.  What is the best way to do this?

Also, how do I understand and troubleshoot the errors I am seeing?  See linked .dgn here: https://www.dropbox.com/s/0p541ornkz4zpz5/ADG_working.dgn?dl=0