My 8" (edit-6") siphon got primed last night...I think. It couldn't drain fast enough to keep up and water went over the emergency spillway. I say I think it primed because the water was well over the top of the pipe, but I'm not sure since I looked at the discharge. I expected water to fill the entire circumference of the pipe, but instead only about 10% of the opening was water. I even stuck my hand up into the pipe thinking something might be obstructing it.
The water that's coming out is shooting out 4 or 5 feet.
The culvert that carries water to the pond ran all night at 150 gpm (WAG) or maybe more. I estimate that because I'm sure I could fill a 5 gallon bucket in 2 seconds. In addition to the culvert there is runoff from another 6 or 7 acres.
Should an 8" siphon be able to handle that much water?
One odd thing is that the siphon is making a noise, kind of like faint tom tom drums, or a deep sounding "ping" of varying pitch. It's happening constantly but at irregular intervals of a few seconds +/-.
Sorry if I'm rambling a little, I didn't sleep last night. I'm asking this now because the forecast is for more heavy rains and would like to determine if I can do anything to improve the flow through the siphon. If we get another rain like last night I don't know if I can save the dam.
You can hear the "ping" sound in the video:
