Thanks for your guidance. Yes, I have done that reading and get the concept. I guess it is a problem that I am working from CAD with contour lines that cross the property line (which is at 0). I trimmed all the contours at the property line, but when the "from contours" makes the terrain, it is just slightly different, not exactly the same shape for as built versus existing, when I look in plan view. So I guess I need to enter z values around the edge of the park/property line. I will keep working. Thanks.