The following is from the Autodesk site. I do not know much about it, but here is some info...
Solution
As there is no Object Enabler available for Softdesk 8 Civil/Survey users, Autodesk recommends the use of the Explode AEC Objects routine. The recommended procedure depends on whether the file needs to be used again in Autodesk Architectural Desktop.
Method #1
Use this transfer method if there is no requirement to use the file again in Autodesk Architectural Desktop.
Create a copy of the file and open it in Autodesk Architectural Desktop.
Use the Explode AEC Objects routine to reduce all AEC objects to basic AutoCAD® objects.
Note: The Explode AEC Objects command is part of a default installation of Autodesk Architectural Desktop, Release 3 or 3.3. If you use AutoCAD Architectural Desktop(tm) Release 2.0 or Release 2i, you need to download this routine from the Autodesk Beta website. Refer to TS60464 for instructions on loading AEC Object Explode.
Use the WBLOCK command to extract the geometry from this file into a new drawing.
The resultant file will not include any AEC objects and can be transferred to the Softdesk 8 Civil/Survey user who can modify it as needed.
Method #2
Use this transfer method if the file needs to be returned to Autodesk Architectural Desktop.
Create a copy of the file and open it in Autodesk Architectural Desktop.
Use the Explode AEC Objects routine to reduce all AEC objects to basic AutoCAD objects.
Note: The Explode AEC Objects command is part of a default installation of Autodesk Architectural Desktop, Release 3 or 3.3. If you use AutoCAD Architectural Desktop(tm) Release 2.0 or Release 2i, you need to download this routine from the Autodesk Beta website. Refer to TS60464 for instructions on loading AEC Object Explode.
Use the WBLOCK command to extract the geometry from this file into a new drawing.
Send the resultant drawing file to the Softdesk 8 Civil/Survey user who should insert this file as an xref into their drawing.
When the Softdesk 8 Civil/Survey user has finished working on the drawing, they need to detach the xref and save the file, and then send it back to you.
In Autodesk Architectural Desktop, insert the file as an xref in the original version of this drawing.