SDR35 is what my ponds have for overflow pipes. I would imagine the 400 feet of drain would not require pressure rated pipe, but they may or may not have used it.
He said a flapper valve operated by a pull lever. If that is the case I would think it might be a smaller valve like maybe a 4 or 6 inch. I can't imagine a 12" flapper valve as the amount of pull to initially open it would not be practical.
We are still trying to read between the lines of the design but my best guess now is that the flapper valve is smaller then the drain pipe is 12".
Last edited by snrub; 11/13/17 05:00 PM.
