We got almost an inch of rain yesterday on top of saturated ground so the outlet mods got tested.
The only change I made was to add a one foot piece of pipe to the existing 45 and then one additional 45 elbow on that. The result was that the siphon started perfectly as soon as the water reached the top of the pipe. I still had a garbage bag around the unglued joint secured with a bungee cord from the other day. I could hear it sucking some air but it wasn't enough to prevent a siphon from starting. It doesn't seem very critical to have an air tight seal because when the drain goes into a siphon the joint is submerged already. It still kept siphoning even after the water level went down the 3 inches below full pool, where the vent opening is.
I still want to lose the double 90's on the back side and replace them with a single 45. I'll need to bury more of the outlet pipe to do that but I wouldn't think that would matter. The current pipe follows the 2/1 slope of the dam and after switching to a 45 it would look like this:
Any thoughts?
