Thank you all for your quick and concise responses. I have decided to go with a 4-inch pipe, based on quadtracker and katmar's references (GREAT online references). The PDF file (Table 2 on pages 9 and 10 of the PDF) that katmar directed me to shows that a 4" pipe with a 0.0806 ft/ft slope...
I have searched many threads and found many useful tips leading me in the right direction (Manning equation and Hazen-Williams) but not one that directly answers my question or offers a good reference.
I am designing a system with two bent screens (separating solid material from water). The...
