On the spillway question, always go with an open channel spillway. That will flow WAY more than you'll ever get a normal pipe to flow. If you think about it, even if you submerge the inlet of a 24" diameter culvert, it will likely be flowing around half full at the culvert outlet. That is essentially the same flow as a 24" wide earthen spillway, which is very very small. Build a wide open channel spillway and be better off.
Last edited by Hogfan; 09/11/13 11:47 AM.
