surface (subgrade-based)

Either of the following takeoff surfaces created by assigning area-based site improvements with material layers to the Original and Design layer surfaces, thereby subtracting subgrades from the Original ground or Finished design layer-based surfaces:

• Original (subgrade) - This surface represents the uppermost strata of the original surface minus the volume of existing, in-ground site improvements that are to be demolished.
• Design (subgrade) - This surface represents the uppermost strata of the design surface minus the volume of in-ground site improvements that are to be constructed.