Civil3D extension plots boreholes incorrectly?

Hello,

I'm a newcomer to Civil3D in general, but I've discovered what seems to be a bug in the way the boreholes get plotted.  as seen below, both the borehole top of ground and the nearest contour agree they should be at 662.

I have a plot of boreholes and a surface contour extracted from LIDAR.  Both agree when you open up properties for them, on the elevation they should be at, about 662 feet

When I turn to a side view, however, all the boreholes are floating in the air.  I've got the civil3d xyz data from the top of the borehole below, and it says the z coordinate is about 3311.59 feet, where the surface below it is in the ballpark of the 662=700 feet even from the side (grey blob in the middle).

Is there some way I'm importing into civil3d incorrectly?