I have created points (Approx-3,000,000) from raster clip of area of a city using spatial analyst tool. The X and Y coordinates are fine but there is a problem with the elevations. The elevations are set to be in the default layer as that of the raster clip. When I export the points into an excel the elevations of few points were either way below "0" or in thousands of feet above the ground even when the terrain doesn't have such massive difference in elevation and some elevations are not even recorded (as shown in attachments below). The surface generated from such points have irregular shaped contours with straight lines passing from one side of the site to the other.
How should I get the points with (X,Y,Z) so that I can import them into Civil 3D and create a surface from them?