We need a tool that will create a Feature Line at a user specified longitudinal grade, while maintaining a user specified cross slope relative to another feature line.
You need to create a 2% swale in the greenbelt behind the homes. You need the 2% swale flowline to be at a 4:1 cross slope from all the back lot property lines.
For back to front drainage, you need to bring a flowline around from the back of the building to the front @ 2%, while maintaining the required 10% foundation grading cross slope up the adjacent grade at the foundation. The adjacent foundation grade is represented by a feature line that is wrapped around the foundation.