If the Contour lines were originally created from a AutoCAD Data file you may want to look into Cigraphs ArchiTerra Plug-in. Info found
here.
With this plug-in you can import the DXF file (contains the 3D point information that ArchiTerra reads) and you can generate that Mesh directly from the DXF data file.
Alternatively you can import a TXT file of the Points (AutoCAd can create a ASC file of the Survey data that can in turn be saved as a TXT file in say MS Excel. From the imported TXT data a mesh can be created. And from the ArchiTerra Mesh you can use a Tool that creates the Contour lines of your mesh as a Library part.