I am trying to design a proper drain for a 6 gpm flow. Does anybody know the title of any government publications that I might easily find or some reference materials for recommended specs and proceedures for constructing a ground dispersement type drain? What is technical type name for this (drain). Or can anyone just tell me how to do it? AMI contracting recommended a minimum of 4" drain pipe....is a proper drain difficult to engineer? Do I need a pro or a hydraulic engineer or NRCS involvement? The grade of the wooded hill of the proposed drainsight is approx. 25 percent. The drain could be anywhere from 10-40 foot wide. The piping leading to the drain could be either 1" or 1 1/4". The second option for a drain sight would be at the bottom of the same hill where the land is flat. This option would require an extra 200-250 feet of piping and trenching. Which optional location would be best? I imagine the level sight would be prefered to reduce erosion chances and flow cleaner water with less contamination (dirt/mud). Any other information needed just ask. Thanks for any tips or advice.