I am analyzing a storm water problem for a civil engineering, senior capstone project. Our storm water problem occurs in a very urban environment. With this said, much of the runoff that the storm water pipes collect comes from roof drains. These are 6” PVC connected directly to the storm water system. The question I have is, how does one model a roof drain in StormCAD? Should it be modeled as a catch basin at ground elevation? Or is there a way to model it at the roof elevation and then model the 6” PVC connection?