I am building a french drain about 20 feet long that is only needed during very heavy storms, sloped correctly, that will terminate at the spot I want a few inches below the ground surface. Will the flowing pipe water be strong enough to make the short upward turn to utilize an emitter, or should I end the drain with some other method like a box, etc?
Ending the perf pipe slightly below grade will cause the water to back up and not drain.
I like placing large rocks (2” - 6”) around the pipe outlet. This allows the water to flow out and is dispersed out on the surface without eroding the ground. (I try not to use small rocks, because they get “washed” out in heavy rain.)