Desperately need to turn surface into solid(conventional methods not working)

I am taking this data orginally from an stl file generated from scan data and trying to convert it to a solild with the "scan to 3D" tools.  Once I go through that whole sequence I end up with a surface which has no dimensional thickness. I cannot seem to find a way to add a thickness to it! I have attempted to use tools such as surface extrude, thicken, surface offset, fill and they do not work. Am I doing something wrong here? Or is there a more clever way to do this? I am attatching the mesh and surface file. Any attempt would be greatly appreciated!

Thank you,

Shawn