Thank you for the replies, and sorry for being mia...work picked up, a lot. I had the watershed looked at and it was determined I have approximately less than a 2 acre watershed. I also ended up going with the 8 inch riser for the main spillway, and two 12" culvert pipes for an emergency spillway. Based on the watershed area, that is more than adequate. Next question I have is that the contractor insisted on steel pipe, and where the riser is welded to the barrel pipe is my only concern as it is the first place to rust through and fail. I'm considering coating yhe joint with a metal primer, flex seal, tar, or something. What do you all recommend for that?
