Add a Surcharge Volume Option for Meshes & Terrains. This would need to function so as to compare the Surcharge to Design and Existing volumes/terrains. Surcharge embankment will always be above finished or existing grade, so consider this as sort of opposite of subsoil/unsuitable. Provide the option for the user to select Surcharge to stop at the top of Design meshes or the bottom of Design meshes, as agencies handle this differently.