Adding a Vertical position (Z)

[janehansen]

Hi I have been asked to include the vertical position component (Z) using the orthometric hight referenced to the Canadian Geodetic Vertical Datum of 1928 (CGVD28).  I have been provided with polygons that do not have any z values included.  My question is, is there anyway to add a z value to an existing shapefile or featureclass?

Thanks,

Jane