I imported a Import a surveyor DWG file. I followed the instruction in the tutorial (Import a Surveyor DWG file for a Site Plan or Terrain Perimeter (chiefarchitect.com) . And got some strange spikes hills. I have tired cleaning up the elevation data but no luck. There is simply no elevation data in the area that is that tall, not sure what is generate this. Pleas see the attached pic and surveyor map.  17045-Topo.pdf 17045-Topo-C.dwg existing terrian2.plan