Hello Neo, welcome to the forum. Myself and others wish that we would have found this forum before building our ponds, as I wish that you would have found this forum before constructing your pond.
Hate to be a downer and I hope that I am wrong, but from looking at the pics I suspect it’s just a matter of time before the runoff from a heavy rain event completely overwhelms that shallow buried 15” drain pipe. The resulting flow of water over the dam could completely unearth the pipe as it carves a deep trench thru the dam, draining the pond
Normally, the top of the primary drain pipe should be about 1ft below the level of the emergency spillway. ( the spillway is a wide flat path going around the end of the dam, over undisturbed soil, often covered with grass, rip rap, or concrete) The elevation of the emergency spillway should be 2 or more feet lower than the top of the dam. The difference in elevation from the top of dam to the spillway is known as the free board. (from the pictures it appears you only have less than 1ft of freeboard above the primary drain)
When determining the size of the primary and secondary drains it is important to calculate the area of watershed which funnels into the pond. From the pictures it appears to me that your pond could receive a massive influx of water during a heavy rain event. (then again, I don’t know the total size of the watershed, or how much of the runoff may be diverted around the pond)
Personally, I would either lower the primary drain, or increase the height of the dam, thereby increasing the free board. And I would definitely use a tractor or other equipment to carve an emergency spillway around the dam.
If you do add to the existing drain pipe down the backside of the dam you should probably dig a trench and bury the pipe, as a way of anchoring it. A 15” lightweight pipe pulling a siphon needs to be securely anchored.
Oh yeah, I forgot to mention that your pond is actually pretty cool looking, and I hope you're successful with it.
Thank you gully washer.... Well the concern about the drain being so high was also a concern of mine when I spoke with the creator of the pond, but he told me it would be fine... I suppose building up the dam would be the easiest and less costly fix for increasing the free board. I have a tractor that I could use and plenty of places on the property to get the dirt.
On the emergency spillway, I am not sure clear on what you are saying, but I assume it is a spot in the dam that is higher than the exit pipe and around 2 ft less than the top of the dam.... I could possibly do that on the far right side of the dam, as it was natural hillside and not man made. So I guess if I built the dam up all the way across except for a few feet on the right side of the exit pipe that could work..?
The inflow of water is from a small stream, actually just ravines that direct are naturally directed down toward the pond from the hills behind it. Normally it is fairly dry to non-existent, but I have seen it flow fairly good if we have had a lot of rain.
I appreciate the input...and the way you presented it. I have attached a few more epics to show it during the building phase...
