I am running 3 pipes for drainage out to my back fence. One 4” pulling 3 downspouts and a driveway drain, one 4” perf for all the runoff from my RV driveway and neighbors yard, and one 3” for a final downspout. The 2 4” have a 110 foot run with 1” reverse grade until the final 20 feet, which has a 16” drop. The 3” (pictured poking out the inside of the trench) has 50 feet with the same 16” drop. The ditch is being expanded to handle the 4” pipes side-by-side.
How should I terminate them? Some kind of catch basin? Open ended under the fence with a drain cap? Dig the last 20 feet deeper and do a 90 degree cap/pop-up?
Having a tough time figuring it out because the 1 percent slope eats up my entire drop and I am trying to avoid a sump pump. I will respond to questions for more info.