Drainage help
So I have a question in regards to a 4 inch cast-iron drainage pipe that used to discharge into the parking lot that was paved over. It is a 4 inch rainwater discharge pipe that comes from a second story flat roof of a 1940s building and my issue is is the customer does not want a grate trench dug she wants something simple that will just allow the water to pass as it did beforehand, but they destroyed and ran over the old PVC so I’m going to cut it back to the cast-iron and go from there. Any suggestions the driveway is already pitched and the water would drain fine. I’m just not really sure if I should use a catch basin or if I should be doing something else that is simpler. I cannot do a through drain either because the driveway is over 300 feet. That hole is where I found the pipe now I want to move the drain a little farther out from the building.