Memo to my future self. If a pipe structure should appear at station 0+00, but shows up somewhere totally wrong, verify the insertion point’s location. The insertion may have snapped to some object near, but not quite on, station 0+00. Because of whatever algorithm Civil 3D uses, the result may appear odd. This catch basin was inserted a fraction of a foot to the left of station 0+00 and Civil 3D somehow placed it at station 15+XX.
If a structure shows up at an unexpected place on the profile view, check the insertion point of the structure.