3D Topography STEP Model

I have a block of land that has already been surveyed, and I now need the ground profile translated into a workable 3-D STEP file so my construction team can begin grading, earthworks, and drainage studies... (Budget: $30 - $250 AUD, Jobs: 3D CAD, 3D Design, 3D Modelling, 3D Rendering, 3ds Max, AutoCAD, Autodesk Inventor, Building Architecture, Civil Engineering)