Grading Optimization has an integrated workflow with Civil 3D. All surface grading related objects are sketched with Civil 3D commands onto your existing drawing containing a TIN surface. Once sketched, Grading Optimization grading objects are then applied to the geometry.
Some of these objects likely already exist in your project, such as building pads, parking lots, and ponds. The existing geometry can be used to apply grading objects. However, some of the more conceptual objects will need to be planned and sketched such as drain lines, low points, zones, and offset points. The objects influence the Grading Optimization and can simplify problematic areas.
Once applied, the grading object data is added as a property set to your drawing geometry.
From Civil 3D, open the drawing in Grading Optimization where the grading object properties are translated into location-based constraints that are the building blocks for the grading configuration.