I am currently working on a project where we have areas of both pavement reconstruction and mill-overlay. For the pavement reconstruction areas, I am building the SS (storm and sanitary) model showing proposed drainage. However, for the mill-overlay section, I only have to check the existing structures for spread, i am told that the spread in those sections is apparently not an issue, but I have to verify. Hence, I may not expect too many new inlets in these areas.
Should I include the existing structures in my SS model? Or should I perform the calculations outside (excel)?