Despite the category title, I thought this would be the best place for this question, please correct me if I'm wrong.

How can I provide an adequate overflow system for a pond that was dug out, and not built with a dam (and therefore has no low ground to which a siphon/spillway system can drain excess water).

---

I am in the middle of a pond renovation project, in which the final state of the pond should be about 3/4 acre surface area and 8ft average depth (ranging to 15 or more feet in spots, depending on soil suitability testing, still pending). Probably +/-2M gallons capacity.

In the past the water level of the pond varied considerably (2-3ft or so, probably). It is my understanding that the pond, when overfilled, naturally overflowed into the front or side street bordering my property and from there into the storm drains/culverts. As far as I know, this only happened once, in August 2016 during major rains and flooding throughout S Louisiana (I didn't own the house at the time). Photo of possible drainage path below - not sure whether it went to the culvert or storm drain.

In the future I plan to keep the pond full using well water. However, if I am keeping the pond full all the time, rain events are going to much more quickly affect me. I'd rather not soak and wash the pond out through my yard every time it rains, so I need a dedicated drainage/overflow set. Since my pond is dug out and does not have a dam, I'm not sure that the standard siphon/spillway system work for me, though I'd certainly like it to.

I know at this point that I need to measure the depth of the storm drains and culverts on each side of the property to see if tapping into the bases of those would be a viable option. How much deeper than the "normal" pond level would these drains need to be to get a siphon system to work? Alternatively, do I just need to make a dedicated/cemented channel for water to flow in these events? (or perhaps constantly, if I go with a solar water well pump?)

(One other data point - when it is raining HARD, my 3in Honda trash pump rated at 18,000gph at times cannot keep up with the rainfall and drainage from surrounding yards.)

Looking forward to hearing some thoughts and ideas on this problem. Thanks!

Thanks to Redonthehead for posting this explanation of the pond siphon system on this thread.


Last edited by Kris B; 08/28/19 01:16 PM. Reason: typo - gpm is actually gph

Kris